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Sample records for pattern generation involved

  1. Modelling spinal circuitry involved in locomotor pattern generation: insights from deletions during fictive locomotion

    PubMed Central

    Rybak, Ilya A; Shevtsova, Natalia A; Lafreniere-Roula, Myriam; McCrea, David A

    2006-01-01

    The mammalian spinal cord contains a locomotor central pattern generator (CPG) that can produce alternating rhythmic activity of flexor and extensor motoneurones in the absence of rhythmic input and proprioceptive feedback. During such fictive locomotor activity in decerebrate cats, spontaneous omissions of activity occur simultaneously in multiple agonist motoneurone pools for a number of cycles. During these ‘deletions’, antagonist motoneurone pools usually become tonically active but may also continue to be rhythmic. The rhythmic activity that re-emerges following a deletion is often not phase shifted. This suggests that some neuronal mechanism can maintain the locomotor period when motoneurone activity fails. To account for these observations, a simplified computational model of the spinal circuitry has been developed in which the locomotor CPG consists of two levels: a half-centre rhythm generator (RG) and a pattern formation (PF) network, with reciprocal inhibitory interactions between antagonist neural populations at each level. The model represents a network of interacting neural populations with single interneurones and motoneurones described in the Hodgkin-Huxley style. The model reproduces the range of locomotor periods and phase durations observed during real locomotion in adult cats and permits independent control of the level of motoneurone activity and of step cycle timing. By altering the excitability of neural populations within the PF network, the model can reproduce deletions in which motoneurone activity fails but the phase of locomotor oscillations is maintained. The model also suggests criteria for the functional identification of spinal interneurones involved in the mammalian locomotor pattern generation. PMID:17008376

  2. Modelling spinal circuitry involved in locomotor pattern generation: insights from the effects of afferent stimulation

    PubMed Central

    Rybak, Ilya A; Stecina, Katinka; Shevtsova, Natalia A; McCrea, David A

    2006-01-01

    A computational model of the mammalian spinal cord circuitry incorporating a two-level central pattern generator (CPG) with separate half-centre rhythm generator (RG) and pattern formation (PF) networks has been developed from observations obtained during fictive locomotion in decerebrate cats. Sensory afferents have been incorporated in the model to study the effects of afferent stimulation on locomotor phase switching and step cycle period and on the firing patterns of flexor and extensor motoneurones. Here we show that this CPG structure can be integrated with reflex circuits to reproduce the reorganization of group I reflex pathways occurring during locomotion. During the extensor phase of fictive locomotion, activation of extensor muscle group I afferents increases extensor motoneurone activity and prolongs the extensor phase. This extensor phase prolongation may occur with or without a resetting of the locomotor cycle, which (according to the model) depends on the degree to which sensory input affects the RG and PF circuits, respectively. The same stimulation delivered during flexion produces a temporary resetting to extension without changing the timing of following locomotor cycles. The model reproduces this behaviour by suggesting that this sensory input influences the PF network without affecting the RG. The model also suggests that the different effects of flexor muscle nerve afferent stimulation observed experimentally (phase prolongation versus resetting) result from opposing influences of flexor group I and II afferents on the PF and RG circuits controlling the activity of flexor and extensor motoneurones. The results of modelling provide insights into proprioceptive control of locomotion. PMID:17008375

  3. [The central pattern generators].

    PubMed

    Balaban, P M; Vorontsov, D D; Dyakonova, V E; Dyakonova, T L; Zakharov, I S; Korshunova, T A; Orlov, O Yu; Pavlova, G A; Panchin, Yi V; Sakharov, D A; Falikman, M V

    2013-01-01

    The central pattern generator (CPG) is defined as a set of neurons involved in joint production of patterned motor output. The roundtable discussion on the CPG was a part of the 5th All-Russian Conference on Animal Behavior (Moscow, Nov. 21, 2012). The discussion centred on three core themes: 1) the mechanisms of the organization and reconfiguration of pattern generating neuronal ensembles, 2) extrapolations that extend the CPG concept beyond the motor systems, and 3) evolutionary and developmental aspects of CPG.

  4. Multifunctional pattern-generating circuits.

    PubMed

    Briggman, K L; Kristan, W B

    2008-01-01

    The ability of distinct anatomical circuits to generate multiple behavioral patterns is widespread among vertebrate and invertebrate species. These multifunctional neuronal circuits are the result of multistable neural dynamics and modular organization. The evidence suggests multifunctional circuits can be classified by distinct architectures, yet the activity patterns of individual neurons involved in more than one behavior can vary dramatically. Several mechanisms, including sensory input, the parallel activity of projection neurons, neuromodulation, and biomechanics, are responsible for the switching between patterns. Recent advances in both analytical and experimental tools have aided the study of these complex circuits.

  5. Apparatus for generating nonlinear pulse patterns

    DOEpatents

    Nakamura, N.M.I.

    Apparatus for generating a plurality of nonlinear pulse patterns from a single linear pulse pattern. A first counter counts the pulses of the linear pulse pattern and a second counter counts the pulses of the nonlinear pulse pattern. A comparator compares the counts of both counters, and in response to an equal count, a gate is enabled to gate a pulse of the linear pattern as a pulse of the nonlinear pattern, the latter also resetting the first counter. Presettable dividers divide the pulses of each pattern before they are counted by the respective counters. Apparatus for generating a logarithmic pulse pattern from a linear pulse pattern to any log base is described. In one embodiment, a shift register is used in place of the second counter to be clocked by each pulse of the logarithmic pattern to generate the pattern. In another embodiment, a memory stores the logarithmic pattern and is addressed by the second counter which is clocked by the pulses of the logarithmic pulse pattern.

  6. Apparatus for generating nonlinear pulse patterns

    DOEpatents

    Nakamura, Michiyuki

    1981-01-01

    Apparatus for generating a plurality of nonlinear pulse patterns from a single linear pulse pattern. A first counter counts the pulses of the linear pulse pattern and a second counter counts the pulses of the nonlinear pulse pattern. A comparator compares the counts of both counters, and in response to an equal count, a gate is enabled to gate a pulse of the linear pattern as a pulse of the nonlinear pattern, the latter also resetting the first counter. Presettable dividers divide the pulses of each pattern before they are counted by the respective counters. Also, apparatus for generating a logarithmic pulse pattern from a linear pulse pattern to any log base. In one embodiment, a shift register is used in place of the second counter to be clocked by each pulse of the logarithmic pattern to generate the pattern. In another embodiment, a memory stores the logarithmic pattern and is addressed by the second counter which is clocked by the pulses of the logarithmic pulse pattern.

  7. Involvement of bacterial TonB-dependent signaling in the generation of an oligogalacturonide damage-associated molecular pattern from plant cell walls exposed to Xanthomonas campestris pv. campestris pectate lyases

    PubMed Central

    2012-01-01

    Background Efficient perception of attacking pathogens is essential for plants. Plant defense is evoked by molecules termed elicitors. Endogenous elicitors or damage-associated molecular patterns (DAMPs) originate from plant materials upon injury or pathogen activity. While there are comparably well-characterized examples for DAMPs, often oligogalacturonides (OGAs), generated by the activity of fungal pathogens, endogenous elicitors evoked by bacterial pathogens have been rarely described. In particular, the signal perception and transduction processes involved in DAMP generation are poorly characterized. Results A mutant strain of the phytopathogenic bacterium Xanthomonas campestris pv. campestris deficient in exbD2, which encodes a component of its unusual elaborate TonB system, had impaired pectate lyase activity and caused no visible symptoms for defense on the non-host plant pepper (Capsicum annuum). A co-incubation of X. campestris pv. campestris with isolated cell wall material from C. annuum led to the release of compounds which induced an oxidative burst in cell suspension cultures of the non-host plant. Lipopolysaccharides and proteins were ruled out as elicitors by polymyxin B and heat treatment, respectively. After hydrolysis with trifluoroacetic acid and subsequent HPAE chromatography, the elicitor preparation contained galacturonic acid, the monosaccharide constituent of pectate. OGAs were isolated from this crude elicitor preparation by HPAEC and tested for their biological activity. While small OGAs were unable to induce an oxidative burst, the elicitor activity in cell suspension cultures of the non-host plants tobacco and pepper increased with the degree of polymerization (DP). Maximal elicitor activity was observed for DPs exceeding 8. In contrast to the X. campestris pv. campestris wild type B100, the exbD2 mutant was unable to generate elicitor activity from plant cell wall material or from pectin. Conclusions To our knowledge, this is the

  8. Spinal cord pattern generators for locomotion.

    PubMed

    Dietz, V

    2003-08-01

    It is generally accepted that locomotion in mammals, including humans, is based on the activity of neuronal circuits within the spinal cord (the central pattern generator, CPG). Afferent information from the periphery (i.e. the limbs) influences the central pattern and, conversely, the CPG selects appropriate afferent information according to the external requirement. Both the CPG and the reflexes that mediate afferent input to the spinal cord are under the control of the brainstem. There is increasing evidence that in central motor diseases, a defective utilization of afferent input, in combination with secondary compensatory processes, is involved in typical movement disorders, such as spasticity and Parkinson's disease. Recent studies indicate a plastic behavior of the spinal neuronal circuits following a central motor lesion. This has implications for any rehabilitative therapy that should be directed to take advantage of the plasticity of the central nervous system. The significance of this research is in a better understanding of the pathophysiology underlying movement disorders and the consequences for an appropriate treatment.

  9. Mask pattern generator employing EPL technology

    NASA Astrophysics Data System (ADS)

    Yoshioka, Nobuyuki; Yamabe, Masaki; Wakamiya, Wataru; Endo, Nobuhiro

    2003-08-01

    Mask cost is one of crucial issues in device fabrication, especially in SoC (System on a Chip) with small-volume production. The cost mainly depends on productivity of mask manufacturing tools such as mask writers and defect inspection tools. EPL (Electron Projection Lithography) has been developing as a high-throughput electron beam exposure technology that will succeed optical lithography. The application of EPL technology to mask writing will result in high productivity and contribute to decrease the mask cost. The concept of a mask pattern generator employing EPL technology is proposed in this paper. It is very similar to EPL technology used for pattern printing on a wafer. The mask patterns on the glass substrate are exposed by projecting the basic circuit patterns formed on the mother EPL mask. One example of the mother EPL mask is a stencil type made with 200-mm Si wafer. The basic circuit patterns are IP patterns and logical primitive patterns such as cell libraries (AND, OR, Inverter, Flip-Flop and etc.) to express the SoC device patterns. Since the SoC patterns are exposed with its collective units such as IP and logical primitive patterns by using this method, the high throughput will be expected comparing with conventional mask E-beam writers. In this paper, the mask pattern generator with the EPL technology is proposed. The concept, its advantages and issues to be solved are discussed.

  10. Early rheumatoid disease. II. Patterns of joint involvement.

    PubMed Central

    Fleming, A; Benn, R T; Corbett, M; Wood, P H

    1976-01-01

    Data from the first research clinic visit (Fleming and others, 1976) have been subjected to factor analysis to identify early patterns of joint involvement. Nine patterns emerged. Two patterns, if present early, were found to have prognostic significance. An eventually more severe disease was associated with a pattern of large joint involvement (shoulder, elbow, wrist, knee) and a pattern based on metatarsophalangeal joints I and III. PMID:970995

  11. Test pattern generation for ILA sequential circuits

    NASA Technical Reports Server (NTRS)

    Feng, YU; Frenzel, James F.; Maki, Gary K.

    1993-01-01

    An efficient method of generating test patterns for sequential machines implemented using one-dimensional, unilateral, iterative logic arrays (ILA's) of BTS pass transistor networks is presented. Based on a transistor level fault model, the method affords a unique opportunity for real-time fault detection with improved fault coverage. The resulting test sets are shown to be equivalent to those obtained using conventional gate level models, thus eliminating the need for additional test patterns. The proposed method advances the simplicity and ease of the test pattern generation for a special class of sequential circuitry.

  12. Central pattern generators and interphyletic awareness.

    PubMed

    Stein, P S

    1999-01-01

    Our understandings of how neuronal networks organized as central pattern generators generate motor behavior have greatly increased in the last 40 years. In the 60s, many investigators studying invertebrate motor behaviors were not aware of the work of those studying vertebrate motor behaviors, and vice versa. In the 70s, key conferences provided venues for important interactions among investigators working on preparations in different species. These interactions, termed interphyletic awareness, continued in the 80s and 90s at major conferences and played important roles in the development of our understandings of central pattern generators for motor behavior in these decades.

  13. Intersecting circuits generate precisely patterned retinal waves.

    PubMed

    Akrouh, Alejandro; Kerschensteiner, Daniel

    2013-07-24

    The developing retina generates spontaneous glutamatergic (stage III) waves of activity that sequentially recruit neighboring ganglion cells with opposite light responses (ON and OFF RGCs). This activity pattern is thought to help establish parallel ON and OFF pathways in downstream visual areas. The circuits that produce stage III waves and desynchronize ON and OFF RGC firing remain obscure. Using dual patch-clamp recordings, we find that ON and OFF RGCs receive sequential excitatory input from ON and OFF cone bipolar cells (CBCs), respectively. This input sequence is generated by crossover circuits, in which ON CBCs control glutamate release from OFF CBCs via diffusely stratified inhibitory amacrine cells. In addition, neighboring ON CBCs communicate directly and indirectly through lateral glutamatergic transmission and gap junctions, both of which are required for wave initiation and propagation. Thus, intersecting lateral excitatory and vertical inhibitory circuits give rise to precisely patterned stage III retinal waves.

  14. Nonlinear ring resonator: spatial pattern generation

    NASA Astrophysics Data System (ADS)

    Ivanov, Vladimir Y.; Lachinova, Svetlana L.; Irochnikov, Nikita G.

    2000-03-01

    We consider theoretically spatial pattern formation processes in a unidirectional ring cavity with thin layer of Kerr-type nonlinear medium. Our method is based on studying of two coupled equations. The first is a partial differential equation for temporal dynamics of phase modulation of light wave in the medium. It describes nonlinear interaction in the Kerr-type lice. The second is a free propagation equation for the intracavity field complex amplitude. It involves diffraction effects of light wave in the cavity.

  15. Central pattern generators deciphered by molecular genetics.

    PubMed

    Kiehn, Ole; Kullander, Klas

    2004-02-05

    Central pattern generators (CPGs) are localized neuronal networks that have the ability to produce rhythmic movements even in the absence of movement-related sensory feedback. They are found in all animals, including man, and serve as informative model systems for understanding how neuronal networks produce behavior. Traditionally, CPGs have been investigated with electrophysiological techniques. Here we review recent molecular and genetic approaches for dissecting the organization and development of CPGs.

  16. The Human Central Pattern Generator for Locomotion.

    PubMed

    Minassian, Karen; Hofstoetter, Ursula S; Dzeladini, Florin; Guertin, Pierre A; Ijspeert, Auke

    2017-03-01

    The ability of dedicated spinal circuits, referred to as central pattern generators (CPGs), to produce the basic rhythm and neural activation patterns underlying locomotion can be demonstrated under specific experimental conditions in reduced animal preparations. The existence of CPGs in humans is a matter of debate. Equally elusive is the contribution of CPGs to normal bipedal locomotion. To address these points, we focus on human studies that utilized spinal cord stimulation or pharmacological neuromodulation to generate rhythmic activity in individuals with spinal cord injury, and on neuromechanical modeling of human locomotion. In the absence of volitional motor control and step-specific sensory feedback, the human lumbar spinal cord can produce rhythmic muscle activation patterns that closely resemble CPG-induced neural activity of the isolated animal spinal cord. In this sense, CPGs in humans can be defined by the activity they produce. During normal locomotion, CPGs could contribute to the activation patterns during specific phases of the step cycle and simplify supraspinal control of step cycle frequency as a feedforward component to achieve a targeted speed. Determining how the human CPGs operate will be essential to advance the theory of neural control of locomotion and develop new locomotor neurorehabilitation paradigms.

  17. Patterning techniques for next generation IC's

    NASA Astrophysics Data System (ADS)

    Balasinski, A.

    2007-12-01

    Reduction of linear critical dimensions (CDs) beyond 45 nm would require significant increase of the complexity of pattern definition process. In this work, we discuss the key successor methodology to the current optical lithography, the Double Patterning Technique (DPT). We compare the complexity of CAD solutions, fab equipment, and wafer processing with its competitors, such as the nanoimprint (NIL) and the extreme UV (EUV) techniques. We also look ahead to the market availability for the product families enabled using the novel patterning solutions. DPT is often recognized as the most viable next generation lithography as it utilizes the existing equipment and processes and is considered a stop-gap solution before the advanced NIL or EUV equipment is developed. Using design for manufacturability (DfM) rules, DPT can drive the k1 factor down to 0.13. However, it faces a variety of challenges, from new mask overlay strategies, to layout pattern split, novel OPC, increased CD tolerances, new etch techniques, as well as long processing time, all of which compromise its return on investment (RoI). In contrast, it can be claimed e.g., that the RoI is the highest for the NIL but this technology bears significant risk. For all novel patterning techniques, the key questions remain: when and how should they be introduced, what is their long-term potential, when should they be replaced, and by what successor technology. We summarize the unpublished results of several panel discussions on DPT at the recent SPIE/BACUS conferences.

  18. Multivariable Harmonic Balance for Central Pattern Generators.

    PubMed

    Iwasaki, Tetsuya

    2008-12-01

    The central pattern generator (CPG) is a nonlinear oscillator formed by a group of neurons, providing a fundamental control mechanism underlying rhythmic movements in animal locomotion. We consider a class of CPGs modeled by a set of interconnected identical neurons. Based on the idea of multivariable harmonic balance, we show how the oscillation profile is related to the connectivity matrix that specifies the architecture and strengths of the interconnections. Specifically, the frequency, amplitudes, and phases are essentially encoded in terms of a pair of eigenvalue and eigenvector. This basic principle is used to estimate the oscillation profile of a given CPG model. Moreover, a systematic method is proposed for designing a CPG-based nonlinear oscillator that achieves a prescribed oscillation profile.

  19. Silicon central pattern generators for cardiac diseases

    PubMed Central

    Nogaret, Alain; O'Callaghan, Erin L; Lataro, Renata M; Salgado, Helio C; Meliza, C Daniel; Duncan, Edward; Abarbanel, Henry D I; Paton, Julian F R

    2015-01-01

    Cardiac rhythm management devices provide therapies for both arrhythmias and resynchronisation but not heart failure, which affects millions of patients worldwide. This paper reviews recent advances in biophysics and mathematical engineering that provide a novel technological platform for addressing heart disease and enabling beat-to-beat adaptation of cardiac pacing in response to physiological feedback. The technology consists of silicon hardware central pattern generators (hCPGs) that may be trained to emulate accurately the dynamical response of biological central pattern generators (bCPGs). We discuss the limitations of present CPGs and appraise the advantages of analog over digital circuits for application in bioelectronic medicine. To test the system, we have focused on the cardio-respiratory oscillators in the medulla oblongata that modulate heart rate in phase with respiration to induce respiratory sinus arrhythmia (RSA). We describe here a novel, scalable hCPG comprising physiologically realistic (Hodgkin–Huxley type) neurones and synapses. Our hCPG comprises two neurones that antagonise each other to provide rhythmic motor drive to the vagus nerve to slow the heart. We show how recent advances in modelling allow the motor output to adapt to physiological feedback such as respiration. In rats, we report on the restoration of RSA using an hCPG that receives diaphragmatic electromyography input and use it to stimulate the vagus nerve at specific time points of the respiratory cycle to slow the heart rate. We have validated the adaptation of stimulation to alterations in respiratory rate. We demonstrate that the hCPG is tuneable in terms of the depth and timing of the RSA relative to respiratory phase. These pioneering studies will now permit an analysis of the physiological role of RSA as well as its any potential therapeutic use in cardiac disease. PMID:25433077

  20. Silicon central pattern generators for cardiac diseases.

    PubMed

    Nogaret, Alain; O'Callaghan, Erin L; Lataro, Renata M; Salgado, Helio C; Meliza, C Daniel; Duncan, Edward; Abarbanel, Henry D I; Paton, Julian F R

    2015-02-15

    Cardiac rhythm management devices provide therapies for both arrhythmias and resynchronisation but not heart failure, which affects millions of patients worldwide. This paper reviews recent advances in biophysics and mathematical engineering that provide a novel technological platform for addressing heart disease and enabling beat-to-beat adaptation of cardiac pacing in response to physiological feedback. The technology consists of silicon hardware central pattern generators (hCPGs) that may be trained to emulate accurately the dynamical response of biological central pattern generators (bCPGs). We discuss the limitations of present CPGs and appraise the advantages of analog over digital circuits for application in bioelectronic medicine. To test the system, we have focused on the cardio-respiratory oscillators in the medulla oblongata that modulate heart rate in phase with respiration to induce respiratory sinus arrhythmia (RSA). We describe here a novel, scalable hCPG comprising physiologically realistic (Hodgkin-Huxley type) neurones and synapses. Our hCPG comprises two neurones that antagonise each other to provide rhythmic motor drive to the vagus nerve to slow the heart. We show how recent advances in modelling allow the motor output to adapt to physiological feedback such as respiration. In rats, we report on the restoration of RSA using an hCPG that receives diaphragmatic electromyography input and use it to stimulate the vagus nerve at specific time points of the respiratory cycle to slow the heart rate. We have validated the adaptation of stimulation to alterations in respiratory rate. We demonstrate that the hCPG is tuneable in terms of the depth and timing of the RSA relative to respiratory phase. These pioneering studies will now permit an analysis of the physiological role of RSA as well as its any potential therapeutic use in cardiac disease.

  1. Patterns in Group Involvement Experiences during College: Identifying a Taxonomy

    ERIC Educational Resources Information Center

    Dugan, John P.

    2013-01-01

    This study explored whether latent phenomena could be identified to classify students based on their patterns of involvement in cocurricular group experiences. The sample was comprised of 11,209 seniors from 50 institutions. A total of 4 latent factors were identified and students were classified into one of 8 latent classes. Findings offer new…

  2. Central pattern generators for bipedal locomotion.

    PubMed

    Pinto, Carla M A; Golubitsky, Martin

    2006-09-01

    Golubitsky, Stewart, Buono and Collins proposed two models for the achitecture of central pattern generators (CPGs): one for bipeds (which we call leg) and one for quadrupeds (which we call quad). In this paper we use symmetry techniques to classify the possible spatiotemporal symmetries of periodic solutions that can exist in leg (there are 10 nontrivial types) and we explore the possibility that coordinated arm/leg rhythms can be understood, on the CPG level, by a small breaking of the symmetry in quad, which leads to a third CPG architecture arm. Rhythms produced by leg correspond to the bipedal gaits of walk, run, two-legged hop, two-legged jump, skip, gallop, asymmetric hop, and one-legged hop. We show that breaking the symmetry between fore and hind limbs in quad, which yields the CPG arm, leads to periodic solution types whose associated leg rhythms correspond to seven of the eight leg gaits found in leg; the missing biped gait is the asymmetric hop. However, when arm/leg coordination rhythms are considered, we find the correct rhythms only for the biped gaits of two-legged hop, run, and gallop. In particular, the biped gait walk, along with its arm rhythms, cannot be obtained by a small breaking of symmetry of any quadruped gait supported by quad.

  3. Generation 1.5 Written Error Patterns: A Comparative Study

    ERIC Educational Resources Information Center

    Doolan, Stephen M.; Miller, Donald

    2012-01-01

    In an attempt to contribute to existing research on Generation 1.5 students, the current study uses quantitative and qualitative methods to compare error patterns in a corpus of Generation 1.5, L1, and L2 community college student writing. This error analysis provides one important way to determine if error patterns in Generation 1.5 student…

  4. Modular neuromuscular control of human locomotion by central pattern generator.

    PubMed

    Haghpanah, Seyyed Arash; Farahmand, Farzam; Zohoor, Hassan

    2017-02-28

    The central pattern generators (CPG) in the spinal cord are thought to be responsible for producing the rhythmic motor patterns during rhythmic activities. For locomotor tasks, this involves much complexity, due to a redundant system of muscle actuators with a large number of highly nonlinear muscles. This study proposes a reduced neural control strategy for the CPG, based on modular organization of the co-active muscles, i.e., muscle synergies. Four synergies were extracted from the EMG data of the major leg muscles of two subjects, during two gait trials each, using non-negative matrix factorization algorithm. A Matsuoka׳s four-neuron CPG model with mutual inhibition, was utilized to generate the rhythmic activation patterns of the muscle synergies, using the hip flexion angle and foot contact force information from the sensory afferents as inputs. The model parameters were tuned using the experimental data of one gait trial, which resulted in a good fitting accuracy (RMSEs between 0.0491 and 0.1399) between the simulation and experimental synergy activations. The model׳s performance was then assessed by comparing its predictions for the activation patterns of the individual leg muscles during locomotion with the relevant EMG data. Results indicated that the characteristic features of the complex activation patterns of the muscles were well reproduced by the model for different gait trials and subjects. In general, the CPG- and muscle synergy-based model was promising in view of its simple architecture, yet extensive potentials for neuromuscular control, e.g., resolving redundancies, distributed and fast control, and modulation of locomotion by simple control signals.

  5. Three brainstem areas involved in respiratory rhythm generation in bullfrogs

    PubMed Central

    Baghdadwala, Mufaddal I; Duchcherer, Maryana; Paramonov, Jenny; Wilson, Richard J A

    2015-01-01

    Key points For most multiphasic motor patterns, rhythm and pattern are produced by the same circuit elements. For respiration, however, these functions have long been assumed to occur separately. In frogs, the ventilatory motor pattern produced by the isolated brainstem consists of buccal and biphasic lung bursts. Previously, two discrete necessary and sufficient sites for lung and buccal bursts were identified. Here we identify a third site, the Priming Area, important for and having neuronal activity correlated with the first phase of biphasic lung bursts. As each site is important for burst generation of a separate phase, we suggest each major phase of ventilation is produced by an anatomically distinct part of an extensive brainstem network. Embedding of discrete circuit elements producing major phases of respiration within an extensive rhythmogenic brainstem network may be a shared architectural characteristic of vertebrates. Abstract Ventilation in mammals consists of at least three distinct phases: inspiration, post-inspiration and late-expiration. While distinct brainstem rhythm generating and pattern forming networks have long been assumed, recent data suggest the mammalian brainstem contains two coupled neuronal oscillators: one for inspiration and the other for active expiration. However, whether additional burst generating ability is required for generating other phases of ventilation in mammals is controversial. To investigate brainstem circuit architectures capable of producing multiphasic ventilatory rhythms, we utilized the isolated frog brainstem. This preparation produces two types of ventilatory motor patterns, buccal and lung bursts. Lung bursts can be divided into two phases, priming and powerstroke. Previously we identified two putative oscillators, the Buccal and Lung Areas. The Lung Area produces the lung powerstroke and the Buccal Area produces buccal bursts and – we assumed – the priming phase of lung bursts. However, here we identify

  6. Neuromodulation of central pattern generators in invertebrates and vertebrates.

    PubMed

    Dickinson, Patsy S

    2006-12-01

    Central pattern generators are subject to extensive modulation that generates flexibility in the rhythmic outputs of these neural networks. The effects of neuromodulators interact with one another, and modulatory neurons are themselves often subject to modulation, enabling both higher order control and indirect interactions among central pattern generators. In addition, modulators often directly mediate the interactions between functionally related central pattern generators. In systems such as the vertebrate respiratory central pattern generator, multiple pacemaker types interact to produce rhythmic output. Modulators can then alter the relative contributions of the different pacemakers, leading to substantial changes in motor output and hence to different behaviors. Surprisingly, substantial changes in some aspects of the circuitry of a central pattern generator, such as a several-fold increase in synaptic strength, can sometimes have little effect on the output of the CPG, whereas other changes have profound effects.

  7. Pattern Generation by Dissipative Parametric Instability

    NASA Astrophysics Data System (ADS)

    Perego, A. M.; Tarasov, N.; Churkin, D. V.; Turitsyn, S. K.; Staliunas, K.

    2016-01-01

    Nonlinear instabilities are responsible for spontaneous pattern formation in a vast number of natural and engineered systems, ranging from biology to galaxy buildup. We propose a new instability mechanism leading to pattern formation in spatially extended nonlinear systems, which is based on a periodic antiphase modulation of spectrally dependent losses arranged in a zigzag way: an effective filtering is imposed at symmetrically located wave numbers k and -k in alternating order. The properties of the dissipative parametric instability differ from the features of both key classical concepts of modulation instabilities, i.e., the Benjamin-Feir instability and the Faraday instabiltyity. We demonstrate how the dissipative parametric instability can lead to the formation of stable patterns in one- and two-dimensional systems. The proposed instability mechanism is generic and can naturally occur or can be implemented in various physical systems.

  8. Generative Acts: Family and Community Involvement of Older Australians

    ERIC Educational Resources Information Center

    Warburton, Jeni; McLaughlin, Deirdre; Pinsker, Donna

    2006-01-01

    The article adopts a developmental approach to successful human aging by exploring the concept of generativity in relation to a study of older Australians' lived experiences of involvement in the family and community. Qualitative data, collected through focus group interviews, were analyzed interpretively using recent developments in Erikson's…

  9. Sentences Generation by Frequent Parsing Patterns

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Takashi; Miura, Takao; Shioya, Isamu

    We propose a sophisticated approach to generate sentences from syntax trees. Users are assumed to give their intent in text or equivalent ones (such as syntax trees). Here we generate standard sentences by examining how the syntax structure consist of frequent structures and how they are constructed. We examine corpus in some domains to extract elementary syntax structures appeared in the corpus as well as standard sentences using the trees.

  10. Challenging giga-feature pattern generation

    NASA Astrophysics Data System (ADS)

    Odselius, Leif; Ivansen, Lars; Thuren, Anders; Savitsky, Mikhail; Larsson, Jan-Erik

    2002-03-01

    Moore's law implies linear growth of integrated circuit density, but the micro-lithographic pattern density grows significantly faster than linear due to OPC embellishments. The progress of technology supporting this growth goes in small steps interleaved by substantial leaps. The leaps occur when the progress in the computing architecture falls behind the requirements from pattern complexity. An established technology can be optimized to a many times surprisingly large extent, but increasing demands eventually crosses the border that makes a given technological architecture inadequate and obsolete. Three major issues with micro-lithographic data processing demand new solutions. One is the need for raw computing power. The second is the data transport mechanisms, which must be designed to prevent bottlenecks. A third issue is the basic data structuring, i.e. the efficiency of the pattern data formats. Exploding reticle pattern complexity requires that backward compatibility with legacy formats is abandoned and that the efficiency of the data format is placed in focus. Micronic Laser Systems maintains a technological roadmap for modular and expandable parallel computing architectures, from data input and pre-processing, through fracturing to rasterizing.

  11. Central Pattern Generator for Locomotion: Anatomical, Physiological, and Pathophysiological Considerations

    PubMed Central

    Guertin, Pierre A.

    2013-01-01

    This article provides a perspective on major innovations over the past century in research on the spinal cord and, specifically, on specialized spinal circuits involved in the control of rhythmic locomotor pattern generation and modulation. Pioneers such as Charles Sherrington and Thomas Graham Brown have conducted experiments in the early twentieth century that changed our views of the neural control of locomotion. Their seminal work supported subsequently by several decades of evidence has led to the conclusion that walking, flying, and swimming are largely controlled by a network of spinal neurons generally referred to as the central pattern generator (CPG) for locomotion. It has been subsequently demonstrated across all vertebrate species examined, from lampreys to humans, that this CPG is capable, under some conditions, to self-produce, even in absence of descending or peripheral inputs, basic rhythmic, and coordinated locomotor movements. Recent evidence suggests, in turn, that plasticity changes of some CPG elements may contribute to the development of specific pathophysiological conditions associated with impaired locomotion or spontaneous locomotor-like movements. This article constitutes a comprehensive review summarizing key findings on the CPG as well as on its potential role in Restless Leg Syndrome, Periodic Leg Movement, and Alternating Leg Muscle Activation. Special attention will be paid to the role of the CPG in a recently identified, and uniquely different neurological disorder, called the Uner Tan Syndrome. PMID:23403923

  12. Automated Camouflage Pattern Generation Technology Survey.

    DTIC Science & Technology

    2014-09-26

    world. Typical applications include: a. Medical Imaging: Digital radiography, x-ray averaging and recording, ultrasonic analysis, NMR, CAT, etc. Ill-i...Multiple Colors The three color pattern in use in this application adds another constraint. If the robot cannot be equipped with multiple nozzles , the... nozzle would require changing while painting each vehicle. This would add significant time and cost to the painting process. 5. General In addition to

  13. Design flow automation for variable-shaped beam pattern generators

    NASA Astrophysics Data System (ADS)

    Bloecker, Martin; Ballhorn, Gerd

    2002-07-01

    Raster scan pattern generators have been used in the photomask industry for many years. Methods and software tools for data preparation for these pattern generators are well established and have been integrated into design flows with a high degree of automation. But the growing requirements for pattern fidelity have lead to the introduction of 50 kV variable shaped beam pattern generators. Due to their different writing strategy these tools use proprietary data formats and in turn require an optimized data preparation. As a result the existing design flow has to be adopted to account for these requirements. Due to the fact that cycle times have grown severely over the last years the automation of this adopted design flow will not only enhance the design flow quality by avoiding errors during manual operations but will also help to reduce turn-around times. We developed and implemented an automated design flow for a variable shaped beam pattern generator which had to fulfill two conflicting requirements: Well established automated tools originally developed for raster scan pattern generators had to be retained with only slight modifications to avoid the (re)implementation and the concurrent usage of two systems while on the other hand data generation especially during fracturing had to be optimized for a variable shaped beam pattern generator.

  14. Computer-Assisted Generation of Patterns and Virtual Reality Techniques for Fashion Design

    NASA Astrophysics Data System (ADS)

    Naud, Mickael; Richard, Paul; Chapeau-Blondeau, François

    2009-03-01

    We present a methodology for the design of aesthetic patterns and their visualization on virtual clothes. Generated patterns are directly mapped on the dress of a virtual mannequin. Furthermore, patterns sets may be interactively mapped on the virtual dress using a specific 3D interaction technique called Back-and-Forth. Pattern generation involves different mathematical approaches such as iterated function systems (IFS) and nonlinear trajectory models. Both model parameters and color space exploration is performed through a simple user interface. This work contributes to promote both computer assistance in the context of mass customization for fashion design.

  15. Bases of motifs for generating repeated patterns with wild cards.

    PubMed

    Pisanti, Nadia; Crochemore, Maxime; Grossi, Roberto; Sagot, Marie-France

    2005-01-01

    Motif inference represents one of the most important areas of research in computational biology, and one of its oldest ones. Despite this, the problem remains very much open in the sense that no existing definition is fully satisfying, either in formal terms, or in relation to the biological questions that involve finding such motifs. Two main types of motifs have been considered in the literature: matrices (of letter frequency per position in the motif) and patterns. There is no conclusive evidence in favor of either, and recent work has attempted to integrate the two types into a single model. In this paper, we address the formal issue in relation to motifs as patterns. This is essential to get at a better understanding of motifs in general. In particular, we consider a promising idea that was recently proposed, which attempted to avoid the combinatorial explosion in the number of motifs by means of a generator set for the motifs. Instead of exhibiting a complete list of motifs satisfying some input constraints, what is produced is a basis of such motifs from which all the other ones can be generated. We study the computational cost of determining such a basis of repeated motifs with wild cards in a sequence. We give new upper and lower bounds on such a cost, introducing a notion of basis that is provably contained in (and, thus, smaller) than previously defined ones. Our basis can be computed in less time and space, and is still able to generate the same set of motifs. We also prove that the number of motifs in all bases defined so far grows exponentially with the quorum, that is, with the minimal number of times a motif must appear in a sequence, something unnoticed in previous work. We show that there is no hope to efficiently compute such bases unless the quorum is fixed.

  16. The generation of antiphase oscillations and synchrony by a rebound-based vertebrate central pattern generator.

    PubMed

    Li, Wen-Chang; Merrison-Hort, Robert; Zhang, Hong-Yan; Borisyuk, Roman

    2014-04-23

    Many neural circuits are capable of generating multiple stereotyped outputs after different sensory inputs or neuromodulation. We have previously identified the central pattern generator (CPG) for Xenopus tadpole swimming that involves antiphase oscillations of activity between the left and right sides. Here we analyze the cellular basis for spontaneous left-right motor synchrony characterized by simultaneous bursting on both sides at twice the swimming frequency. Spontaneous synchrony bouts are rare in most tadpoles, and they instantly emerge from and switch back to swimming, most frequently within the first second after skin stimulation. Analyses show that only neurons that are active during swimming fire action potentials in synchrony, suggesting both output patterns derive from the same neural circuit. The firing of excitatory descending interneurons (dINs) leads that of other types of neurons in synchrony as it does in swimming. During synchrony, the time window between phasic excitation and inhibition is 7.9 ± 1 ms, shorter than that in swimming (41 ± 2.3 ms). The occasional, extra midcycle firing of dINs during swimming may initiate synchrony, and mismatches of timing in the left and right activity can switch synchrony back to swimming. Computer modeling supports these findings by showing that the same neural network, in which reciprocal inhibition mediates rebound firing, can generate both swimming and synchrony without circuit reconfiguration. Modeling also shows that lengthening the time window between phasic excitation and inhibition by increasing dIN synaptic/conduction delay can improve the stability of synchrony.

  17. Automated branching pattern report generation for laparoscopic surgery assistance

    NASA Astrophysics Data System (ADS)

    Oda, Masahiro; Matsuzaki, Tetsuro; Hayashi, Yuichiro; Kitasaka, Takayuki; Misawa, Kazunari; Mori, Kensaku

    2015-05-01

    This paper presents a method for generating branching pattern reports of abdominal blood vessels for laparoscopic gastrectomy. In gastrectomy, it is very important to understand branching structure of abdominal arteries and veins, which feed and drain specific abdominal organs including the stomach, the liver and the pancreas. In the real clinical stage, a surgeon creates a diagnostic report of the patient anatomy. This report summarizes the branching patterns of the blood vessels related to the stomach. The surgeon decides actual operative procedure. This paper shows an automated method to generate a branching pattern report for abdominal blood vessels based on automated anatomical labeling. The report contains 3D rendering showing important blood vessels and descriptions of branching patterns of each vessel. We have applied this method for fifty cases of 3D abdominal CT scans and confirmed the proposed method can automatically generate branching pattern reports of abdominal arteries.

  18. Central pattern generators and the control of rhythmic movements.

    PubMed

    Marder, E; Bucher, D

    2001-11-27

    Central pattern generators are neuronal circuits that when activated can produce rhythmic motor patterns such as walking, breathing, flying, and swimming in the absence of sensory or descending inputs that carry specific timing information. General principles of the organization of these circuits and their control by higher brain centers have come from the study of smaller circuits found in invertebrates. Recent work on vertebrates highlights the importance of neuro-modulatory control pathways in enabling spinal cord and brain stem circuits to generate meaningful motor patterns. Because rhythmic motor patterns are easily quantified and studied, central pattern generators will provide important testing grounds for understanding the effects of numerous genetic mutations on behavior. Moreover, further understanding of the modulation of spinal cord circuitry used in rhythmic behaviors should facilitate the development of new treatments to enhance recovery after spinal cord damage.

  19. Characteristic flow patterns generated by macrozoobenthic structures

    NASA Astrophysics Data System (ADS)

    Friedrichs, M.; Graf, G.

    2009-02-01

    A laboratory flume channel, equipped with an acoustic Doppler flow sensor and a bottom scanning laser, was used for detailed, non-intrusive flow measurements (at 2 cm s - 1 and 10 cm s - 1 ) around solitary biogenic structures, combined with high-resolution mapping of the structure shape and position. The structures were replicates of typical macrozoobenthic species commonly found in the Mecklenburg Bight and with a presumed influence on both, the near-bed current regime and sediment transport dynamics: a worm tube, a snail shell, a mussel, a sand mound, a pit, and a cross-stream track furrow. The flow was considerably altered locally by the different protruding structures (worm tube, snail, mussel and mound). They reduced the horizontal approach velocity by 72% to 79% in the wake zone at about 1-2 cm height, and the flow was deflected around the structures with vertical and lateral velocities of up to 10% and 20% of the free-stream velocity respectively in a region adjacent to the structures. The resulting flow separation (at flow Reynolds number of about 4000 and 20,000 respectively) divided an outer deflection region from an inner region with characteristic vortices and the wake region. All protruding structures showed this general pattern, but also produced individual characteristics. Conversely, the depressions (track and pit) only had a weak influence on the local boundary layer flow, combined with a considerable flow reduction within their cavities (between 29% and 53% of the free-stream velocity). A longitudinal vortex formed, below which a stagnant space was found. The average height affected by the structure-related mass flow rate deficit for the two velocities was 1.6 cm and 1.3 cm respectively (80% of height and 64%) for the protruding structures and 0.6 cm and 0.9 cm (90% and 127% of depth) for the depressions. Marine benthic soft-bottom macrozoobenthos species are expected to benefit from the flow modifications they induce, particularly in terms of

  20. A simple approach for stochastic generation of spatial rainfall patterns

    NASA Astrophysics Data System (ADS)

    Tarpanelli, Angelica; Franchini, Marco; Camici, Stefania; Brocca, Luca; Melone, Florisa; Moramarco, Tommaso

    2010-05-01

    The high floods occurred in the last years in many regions of the world have increased the interest of local, national and international authorities on the flood and risk assessment. In this context, the estimation of the design flood to be adopted represents a crucial factor, mainly for ungauged or poorly gauged catchments where sufficiently long discharge time series are missing. Due to the wider availability of rainfall data, rainfall-runoff models represent a possible tool to reduce the relevant uncertainty involved in the flood frequency analysis. Recently, new methodologies based on the stochastic generation of rainfall and temperature data have been proposed. The inferred information can be used as input for a continuous hydrological model to generate a synthetic time series of discharge and, hence, the flood frequency distribution at a given site. As far as the rainfall generation is concerned, for catchments of limited size, a single site model, as the Neyman-Scott Rectangular Pulses (NSRP), can be applied. It is characterized by a flexible structure in which the model parameters are broadly related to the underlying physical features observed in the rainfall field and the statistical properties of rainfall time series over a range of time scales are preserved. However, when larger catchments are considered, an extension into the two-dimensional space is required. This issue can be addressed by using the Spatial-Temporal Neyman-Scott Rectangular Pulses (STNSRP) model that, however, is not easy to be applied and requires a high computational effort. Therefore, simple techniques to obtain a spatial rainfall pattern starting from the more simple single-site NSRP are welcome. In this study, in order to take account of the spatial correlation that is needed when spatial rainfall patterns should be generated, the practical method of the rank correlation proposed by Iman and Conover (IC), was applied. The method is able to introduce a desired level of correlation

  1. Associative neural network model for the generation of temporal patterns. Theory and application to central pattern generators.

    PubMed Central

    Kleinfeld, D; Sompolinsky, H

    1988-01-01

    Cyclic patterns of motor neuron activity are involved in the production of many rhythmic movements, such as walking, swimming, and scratching. These movements are controlled by neural circuits referred to as central pattern generators (CPGs). Some of these circuits function in the absence of both internal pacemakers and external feedback. We describe an associative neural network model whose dynamic behavior is similar to that of CPGs. The theory predicts the strength of all possible connections between pairs of neurons on the basis of the outputs of the CPG. It also allows the mean operating levels of the neurons to be deduced from the measured synaptic strengths between the pairs of neurons. We apply our theory to the CPG controlling escape swimming in the mollusk Tritonia diomedea. The basic rhythmic behavior is shown to be consistent with a simplified model that approximates neurons as threshold units and slow synaptic responses as elementary time delays. The model we describe may have relevance to other fixed action behaviors, as well as to the learning, recall, and recognition of temporally ordered information. Images FIGURE 2 FIGURE 4 PMID:3233265

  2. The pharmacology of vertebrate spinal central pattern generators.

    PubMed

    Alford, Simon; Schwartz, Eric; Viana di Prisco, Gonzalo

    2003-06-01

    Central pattern generators are networks of neurons capable of generating an output pattern of spike activity in a relatively stereotyped, rhythmic pattern that has been found to underlie vital functions like respiration and locomotion. The central pattern generator for locomotion in vertebrates seems to share some basic building blocks. Activation and excitation of activity is driven by descending, sensory, and intraspinal glutamatergic neurons. NMDA receptor activation may also lead to the activation of oscillatory properties in individual neurons that depend on an array of ion channels situated in those neurons. Coordination across joints or the midline of the animal is driven primarily by glycinergic inhibition. In addition to these processes, numerous modulatory mechanisms alter the function of the central pattern generator. These include metabotropic amino acid receptors activated by rhythmic release of glutamate and GABA as well as monoamines, ACh, and peptides. Function and stability of the central pattern generator is also critically dependent on the array of ion channels found in neurons that compose these oscillators, including Ca2+ and voltage-gated K+ channels and Ca2+ channels.

  3. Generation of pattern and form in the developing limb.

    PubMed

    Towers, Matthew; Tickle, Cheryll

    2009-01-01

    The developing limb is a major model for pattern formation in vertebrate embryos. Many of the seminal discoveries of the mechanisms involved in patterning have been made using chick embryos because of the ease of manipulating their developing limbs. More recently, the molecular basis of limb pattern formation has been increasingly uncovered and now, with the availability of genomic resources, the genetic approaches available are even more powerful. Nevertheless, since the limb is ultimately built of cells, gene action must ultimately be translated into cell behaviour and a major challenge will be to integrate genetics with molecular and cellular biology. In this review, we will first outline the stages in limb development, the major interacting signalling pathways that pattern the limb and the molecules involved. We will describe fate maps of the developing limb, and discuss what is known about cellular activities including proliferation, death, adhesiveness, communication and migration during the patterning process. Finally we will explore how these cell activities produce form.

  4. Contextual modulation of a multifunctional central pattern generator.

    PubMed

    Ramakrishnan, Siddharth; Arnett, Bridgette; Murphy, A Don

    2014-11-01

    The multifunctional buccal central pattern generator in snails, which controls different oral behaviors, has been well characterized. In this work we propose a role for the group of about 40 electrotonically coupled buccal A cluster cells as a context-dependant switch for the buccal central pattern generator, modulating motor patterns that elicit different oral behaviors. We characterize these cells based on location and morphology, and provide evidence for their selective activation under two different stimuli - Listerine perfusion and intestinal nerve stimulation - triggering buccal motor patterns putatively underlying egestion and substrate cleaning. A new role for these electrotonically coupled buccal A cluster neurons is shown. They serve as a context-dependant switch that alters buccal motor patterns depending on input stimuli, thereby eliciting the appropriate behavioral response.

  5. Nanoscale patterning of colloidal quantum dots for surface plasmon generation

    NASA Astrophysics Data System (ADS)

    Park, Yeonsang; Roh, Young-Geun; Kim, Un Jeong; Chung, Dae-Young; Suh, Hwansoo; Kim, Jineun; Cheon, Sangmo; Lee, Jaesoong; Kim, Tae-Ho; Cho, Kyung-Sang; Lee, Chang-Won

    2013-03-01

    The patterning of colloidal quantum dots with nanometer resolution is essential for their application in photonics and plasmonics. Several patterning approaches, such as the use of polymer composites, molecular lock-and-key methods, inkjet printing, and microcontact printing of quantum dots, have limits in fabrication resolution, positioning and the variation of structural shapes. Herein, we present an adaptation of a conventional liftoff method for patterning colloidal quantum dots. This simple method is easy and requires no complicated processes. Using this method, we formed straight lines, rings, and dot patterns of colloidal quantum dots on metallic substrates. Notably, patterned lines approximately 10 nm wide were fabricated. The patterned structures display high resolution, accurate positioning, and well-defined sidewall profiles. To demonstrate the applicability of our method, we present a surface plasmon generator elaborated from quantum dots.

  6. Parental Involvement in Adolescent Romantic Relationships: Patterns and Correlates

    ERIC Educational Resources Information Center

    Kan, Marni L.; McHale, Susan M.; Crouter, Ann C.

    2008-01-01

    This study examined dimensions of mothers' and fathers' involvement in adolescents' romantic relationships when offspring were age 17. Using cluster analysis, parents from 105 White, working and middle class families were classified as positively involved, negatively involved, or autonomy-oriented with respect to their adolescents' romantic…

  7. Computer Generated Holography with Intensity-Graded Patterns

    PubMed Central

    Conti, Rossella; Assayag, Osnath; de Sars, Vincent; Guillon, Marc; Emiliani, Valentina

    2016-01-01

    Computer Generated Holography achieves patterned illumination at the sample plane through phase modulation of the laser beam at the objective back aperture. This is obtained by using liquid crystal-based spatial light modulators (LC-SLMs), which modulate the spatial phase of the incident laser beam. A variety of algorithms is employed to calculate the phase modulation masks addressed to the LC-SLM. These algorithms range from simple gratings-and-lenses to generate multiple diffraction-limited spots, to iterative Fourier-transform algorithms capable of generating arbitrary illumination shapes perfectly tailored on the base of the target contour. Applications for holographic light patterning include multi-trap optical tweezers, patterned voltage imaging and optical control of neuronal excitation using uncaging or optogenetics. These past implementations of computer generated holography used binary input profile to generate binary light distribution at the sample plane. Here we demonstrate that using graded input sources, enables generating intensity graded light patterns and extend the range of application of holographic light illumination. At first, we use intensity-graded holograms to compensate for LC-SLM position dependent diffraction efficiency or sample fluorescence inhomogeneity. Finally we show that intensity-graded holography can be used to equalize photo evoked currents from cells expressing different levels of chanelrhodopsin2 (ChR2), one of the most commonly used optogenetics light gated channels, taking into account the non-linear dependence of channel opening on incident light. PMID:27799896

  8. Mechanochemical models for generating biological pattern and form in development

    NASA Astrophysics Data System (ADS)

    Murray, J. D.; Maini, P. K.; Tranquillo, R. T.

    1988-12-01

    The central issue in development is the formation of spatial patterns of cells in the early embryo. The mechanisms which generate these patterns are unknown. Here we describe the new Oster-Murray mechanochemical approach to the problem, the elements of which are experimentally well documented. By way of illustration we derive one of the basic models from first principles and apply it to a variety of problems of current interest and research. We specifically discuss the formation of skin organ patterns, such as feather and scale germs, cartilage condensations in the developing vertebrate limb and finally wound healing.

  9. Model-based pattern dummy generation for logic devices

    NASA Astrophysics Data System (ADS)

    Jang, Jongwon; Kim, Cheolkyun; Ko, Sungwoo; Byun, Seokyoung; Yang, Hyunjo; Yim, Donggyu

    2014-03-01

    The insertion of SRAF(Sub-Resolution Assist Feature) is one of the most frequently used method to enlarge the process window area. In most cases, the size of SRAF is proportional to the focus margin of drawn patterns. However, there is a trade-off between the SRAF size and SRAF printing, because SRAF is not supposed to be patterned on a wafer. For this reason, a lot of OPC engineers have been tried to put bigger and more SRAFs within the limits of the possible. The fact that many papers about predicting SRAF printability have been published recent years reflects this circumstance. Pattern dummy is inserted to enhance the lithographic process margin and CD uniformity unlike CMP dummy for uniform metal line height. It is ordinary to put pattern dummy at the designated location under consideration of the pitch of real patterns at design step. However, it is not always desirable to generate pattern dummies based on rules at the lithographic point of view. In this paper, we introduce the model based pattern dummy insertion method, which is putting pattern dummies at the location that model based SRAF is located. We applied the model based pattern dummy to the layers in logic devices, and studied which layer is more efficient for the insertion of dummies.

  10. Examining Associations between Race, Urbanicity, and Patterns of Bullying Involvement

    ERIC Educational Resources Information Center

    Goldweber, Asha; Waasdorp, Tracy Evian; Bradshaw, Catherine P.

    2013-01-01

    Research on the role of race and urbanicity in bullying involvement has been limited. The present study examined bullying involvement subgroups that relate to race, urbanicity, and the perceived reason for the bullying. Self-report data were collected from 10,254 middle school youth (49.8% female; 62.4% Caucasian, 19.0% African American, and 5.6%…

  11. Do subitizing deficits in developmental dyscalculia involve pattern recognition weakness?

    PubMed

    Ashkenazi, Sarit; Mark-Zigdon, Nitza; Henik, Avishai

    2013-01-01

    The abilities of children diagnosed with developmental dyscalculia (DD) were examined in two types of object enumeration: subitizing, and small estimation (5-9 dots). Subitizing is usually defined as a fast and accurate assessment of a number of small dots (range 1 to 4 dots), and estimation is an imprecise process to assess a large number of items (range 5 dots or more). Based on reaction time (RT) and accuracy analysis, our results indicated a deficit in the subitizing and small estimation range among DD participants in relation to controls. There are indications that subitizing is based on pattern recognition, thus presenting dots in a canonical shape in the estimation range should result in a subitizing-like pattern. In line with this theory, our control group presented a subitizing-like pattern in the small estimation range for canonically arranged dots, whereas the DD participants presented a deficit in the estimation of canonically arranged dots. The present finding indicates that pattern recognition difficulties may play a significant role in both subitizing and subitizing deficits among those with DD.

  12. Longitudinal Patterns of Nonresident Fathers' Involvement: The Role of Resources and Relations

    ERIC Educational Resources Information Center

    Ryan, Rebecca M.; Kalil, Ariel; Ziol-Guest, Kathleen M.

    2008-01-01

    Using data from the Fragile Families and Child Wellbeing Study, we examined patterns of nonresident father involvement 1 and 3 years after a nonmarital birth (N = 893). Cluster analyses were used to determine patterns of involvement across different father behaviors. About half of fathers displayed low involvement when children were 1 and 3 years…

  13. Action Generation Model Based on Changes in State Patterns

    NASA Astrophysics Data System (ADS)

    Gouko, Manabu; Tomi, Naoki; Nagano, Tomoaki; Ito, Koji

    In this paper, we propose a self-organized learning model that can generate behaviors for successfully performing various tasks. The model memorizes various relationships between changes in a state pattern and a motor command through learning. After the learning, the model can perform various tasks by generating the various behaviors automatically. We confirmed the performance of the model by applying it to a mobile robot simulation. The results indicate that suitable behaviors for all the tasks generated spontaneously. Additionally, we propose a sequential learning method which modifies the memorized various relationships while the model executes the task. And we confirmed the effectiveness of the sequential learning by the simulation.

  14. Central pattern generator for vocalization: Is there a vertebrate morphotype?

    PubMed Central

    Bass, Andrew H.

    2014-01-01

    Animals that generate acoustic signals for social communication are faced with two essential tasks: generate a temporally precise signal and inform the auditory system about the occurrence of one’s own sonic signal. Recent studies of sound producing fishes delineate a hindbrain network comprised of anatomically distinct compartments coding equally distinct neurophysiological properties that allow an organism to meet these behavioral demands. A set of neural characters comprising a vocal-sonic central pattern generator (CPG) morphotype is proposed for fishes and tetrapods that shares evolutionary developmental origins with pectoral appendage motor systems. PMID:25050813

  15. Central pattern generator for vocalization: is there a vertebrate morphotype?

    PubMed

    Bass, Andrew H

    2014-10-01

    Animals that generate acoustic signals for social communication are faced with two essential tasks: generate a temporally precise signal and inform the auditory system about the occurrence of one's own sonic signal. Recent studies of sound producing fishes delineate a hindbrain network comprised of anatomically distinct compartments coding equally distinct neurophysiological properties that allow an organism to meet these behavioral demands. A set of neural characters comprising a vocal-sonic central pattern generator (CPG) morphotype is proposed for fishes and tetrapods that shares evolutionary developmental origins with pectoral appendage motor systems.

  16. Adult Undergraduate Students: Patterns of Learning Involvement. Final Research Report.

    ERIC Educational Resources Information Center

    Kasworm, Carol E.; Blowers, Sally S.

    A research study examined the complex roles of adult life in relation to the student role, the nature of adult undergraduate engagement in learning, and adult perceptions of involvement. Adult students were interviewed in three types of institutions: 38 at two liberal arts colleges, 29 at two community colleges, and 23 at two public universities.…

  17. Order parameter for bursting polyrhythms in multifunctional central pattern generators.

    PubMed

    Wojcik, Jeremy; Clewley, Robert; Shilnikov, Andrey

    2011-05-01

    We examine multistability of several coexisting bursting patterns in a central pattern generator network composed of three Hodgkin-Huxley type cells coupled reciprocally by inhibitory synapses. We establish that the control of switching between bursting polyrhythms and their bifurcations are determined by the temporal characteristics, such as the duty cycle, of networked interneurons and the coupling strength asymmetry. A computationally effective approach to the reduction of dynamics of the nine-dimensional network to two-dimensional Poincaré return mappings for phase lags between the interneurons is presented.

  18. Order parameter for bursting polyrhythms in multifunctional central pattern generators

    NASA Astrophysics Data System (ADS)

    Wojcik, Jeremy; Clewley, Robert; Shilnikov, Andrey

    2011-05-01

    We examine multistability of several coexisting bursting patterns in a central pattern generator network composed of three Hodgkin-Huxley type cells coupled reciprocally by inhibitory synapses. We establish that the control of switching between bursting polyrhythms and their bifurcations are determined by the temporal characteristics, such as the duty cycle, of networked interneurons and the coupling strength asymmetry. A computationally effective approach to the reduction of dynamics of the nine-dimensional network to two-dimensional Poincaré return mappings for phase lags between the interneurons is presented.

  19. Modeling Scalable Pattern Generation in DNA Reaction Networks

    PubMed Central

    Allen, Peter B.; Chen, Xi; Simpson, Zack B.; Ellington, Andrew D.

    2013-01-01

    We have developed a theoretical framework for developing patterns in multiple dimensions using controllable diffusion and designed reactions implemented in DNA. This includes so-called strand displacement reactions in which one single-stranded DNA hybridizes to a hemi-duplex DNA and displaces another single-stranded DNA, reversibly or irreversibly. These reactions can be designed to proceed with designed rate and molecular specificity. By also controlling diffusion by partial complementarity to a stationary, cross-linked DNA, we can generate predictable patterns. We demonstrate this with several simulations showing deterministic, predictable shapes in space. PMID:25506295

  20. Neural Sequence Generation Using Spatiotemporal Patterns of Inhibition

    PubMed Central

    Cannon, Jonathan; Kopell, Nancy; Gardner, Timothy; Markowitz, Jeffrey

    2015-01-01

    Stereotyped sequences of neural activity are thought to underlie reproducible behaviors and cognitive processes ranging from memory recall to arm movement. One of the most prominent theoretical models of neural sequence generation is the synfire chain, in which pulses of synchronized spiking activity propagate robustly along a chain of cells connected by highly redundant feedforward excitation. But recent experimental observations in the avian song production pathway during song generation have shown excitatory activity interacting strongly with the firing patterns of inhibitory neurons, suggesting a process of sequence generation more complex than feedforward excitation. Here we propose a model of sequence generation inspired by these observations in which a pulse travels along a spatially recurrent excitatory chain, passing repeatedly through zones of local feedback inhibition. In this model, synchrony and robust timing are maintained not through redundant excitatory connections, but rather through the interaction between the pulse and the spatiotemporal pattern of inhibition that it creates as it circulates the network. These results suggest that spatially and temporally structured inhibition may play a key role in sequence generation. PMID:26536029

  1. Key central pattern generators of the spinal cord.

    PubMed

    Guertin, Pierre A; Steuer, Inge

    2009-08-15

    In the central nervous system (CNS), central pattern generators (CPGs) are generally considered as specialized networks that can produce oscillatory motor output in the absence of any oscillatory input. For instance, respiration and mastication are among the critical biological functions well known to be controlled by such specialized networks. Several other CPGs have also been found specifically in the spinal cord. Among them, the CPG for locomotion is probably the most extensively studied rhythm- and pattern-generating network of the CNS. Other, less completely understood CPGs have also been associated with the control of scratching, micturition, and ejaculation. This review provides a brief update on CPG organization and function in the spinal cord and focuses on similarities and differences between these networks and their pharmacological modulation.

  2. Override of spontaneous respiratory pattern generator reduces cardiovascular parasympathetic influence

    NASA Technical Reports Server (NTRS)

    Patwardhan, A. R.; Vallurupalli, S.; Evans, J. M.; Bruce, E. N.; Knapp, C. F.

    1995-01-01

    We investigated the effects of voluntary control of breathing on autonomic function in cardiovascular regulation. Variability in heart rate was compared between 5 min of spontaneous and controlled breathing. During controlled breathing, for 5 min, subjects voluntarily reproduced their own spontaneous breathing pattern (both rate and volume on a breath-by-breath basis). With the use of this experimental design, we could unmask the effects of voluntary override of the spontaneous respiratory pattern generator on autonomic function in cardiovascular regulation without the confounding effects of altered respiratory pattern. Results from 10 subjects showed that during voluntary control of breathing, mean values of heart rate and blood pressure increased, whereas fractal and spectral powers in heart rate in the respiratory frequency region decreased. End-tidal PCO2 was similar during spontaneous and controlled breathing. These results indicate that the act of voluntary control of breathing decreases the influence of the vagal component, which is the principal parasympathetic influence in cardiovascular regulation.

  3. A generating function for certain coefficients involving several complex variables.

    PubMed

    Srivastava, H M

    1970-10-01

    In an attempt to unify a number of generating functions for certain classes of generalized hypergeometric polynomials, Lagrange's expansion formula is applied to prove a generating relation for an n-dimensional polynomial with arbitrary coefficients. It is also shown how these coefficients can be specialized to obtain the generalized Lauricella function as a generating function for a class of generalized hypergeometric polynomials of several complex variables.

  4. Towards multifocal ultrasonic neural stimulation: pattern generation algorithms.

    PubMed

    Hertzberg, Yoni; Naor, Omer; Volovick, Alexander; Shoham, Shy

    2010-10-01

    Focused ultrasound (FUS) waves directed onto neural structures have been shown to dynamically modulate neural activity and excitability, opening up a range of possible systems and applications where the non-invasiveness, safety, mm-range resolution and other characteristics of FUS are advantageous. As in other neuro-stimulation and modulation modalities, the highly distributed and parallel nature of neural systems and neural information processing call for the development of appropriately patterned stimulation strategies which could simultaneously address multiple sites in flexible patterns. Here, we study the generation of sparse multi-focal ultrasonic distributions using phase-only modulation in ultrasonic phased arrays. We analyse the relative performance of an existing algorithm for generating multifocal ultrasonic distributions and new algorithms that we adapt from the field of optical digital holography, and find that generally the weighted Gerchberg-Saxton algorithm leads to overall superior efficiency and uniformity in the focal spots, without significantly increasing the computational burden. By combining phased-array FUS and magnetic-resonance thermometry we experimentally demonstrate the simultaneous generation of tightly focused multifocal distributions in a tissue phantom, a first step towards patterned FUS neuro-modulation systems and devices.

  5. Processing and analysis techniques involving in-vessel material generation

    DOEpatents

    Schabron, John F [Laramie, WY; Rovani, Jr., Joseph F.

    2012-09-25

    In at least one embodiment, the inventive technology relates to in-vessel generation of a material from a solution of interest as part of a processing and/or analysis operation. Preferred embodiments of the in-vessel material generation (e.g., in-vessel solid material generation) include precipitation; in certain embodiments, analysis and/or processing of the solution of interest may include dissolution of the material, perhaps as part of a successive dissolution protocol using solvents of increasing ability to dissolve. Applications include, but are by no means limited to estimation of a coking onset and solution (e.g., oil) fractionating.

  6. Processing and analysis techniques involving in-vessel material generation

    DOEpatents

    Schabron, John F.; Rovani, Jr., Joseph F.

    2011-01-25

    In at least one embodiment, the inventive technology relates to in-vessel generation of a material from a solution of interest as part of a processing and/or analysis operation. Preferred embodiments of the in-vessel material generation (e.g., in-vessel solid material generation) include precipitation; in certain embodiments, analysis and/or processing of the solution of interest may include dissolution of the material, perhaps as part of a successive dissolution protocol using solvents of increasing ability to dissolve. Applications include, but are by no means limited to estimation of a coking onset and solution (e.g., oil) fractionating.

  7. Student Involvement in Space Exploration: The Next Generation

    NASA Astrophysics Data System (ADS)

    Bagenal, F.; Horanyi, M.

    2017-02-01

    Involvement of students in space missions exposes them to the technical realities of space exploration – delivers deep learning experience and feeds the professional pipeline. Give students the opportunity to explore every corner of the solar system.

  8. Pattern Recognition on Read Positioning in Next Generation Sequencing

    PubMed Central

    Byeon, Boseon; Kovalchuk, Igor

    2016-01-01

    The usefulness and the utility of the next generation sequencing (NGS) technology are based on the assumption that the DNA or cDNA cleavage required to generate short sequence reads is random. Several previous reports suggest the existence of sequencing bias of NGS reads. To address this question in greater detail, we analyze NGS data from four organisms with different GC content, Plasmodium falciparum (19.39%), Arabidopsis thaliana (36.03%), Homo sapiens (40.91%) and Streptomyces coelicolor (72.00%). Using machine learning techniques, we recognize the pattern that the NGS read start is positioned in the local region where the nucleotide distribution is dissimilar from the global nucleotide distribution. We also demonstrate that the mono-nucleotide distribution underestimates sequencing bias, and the recognized pattern is explained largely by the distribution of multi-nucleotides (di-, tri-, and tetra- nucleotides) rather than mono-nucleotides. This implies that the correction of sequencing bias needs to be performed on the basis of the multi-nucleotide distribution. Providing companion software to quantify the effect of the recognized pattern on read positioning, we exemplify that the bias correction based on the mono-nucleotide distribution may not be sufficient to clean sequencing bias. PMID:27299343

  9. Organization of mammalian locomotor rhythm and pattern generation

    PubMed Central

    McCrea, David A.; Rybak, Ilya A.

    2008-01-01

    Central pattern generators (CPGs) located in the spinal cord produce the coordinated activation of flexor and extensor motoneurons during locomotion. Previously proposed architectures for the spinal locomotor CPG have included the classical half-center oscillator and the unit burst generator (UBG) comprised of multiple coupled oscillators. We have recently proposed another organization in which a two-level CPG has a common rhythm generator (RG) that controls the operation of the pattern formation (PF) circuitry responsible for motoneuron activation. These architectures are discussed in relation to recent data obtained during fictive locomotion in the decerebrate cat. The data show that the CPG can maintain the period and phase of locomotor oscillations both during spontaneous deletions of motoneuron activity and during sensory stimulation affecting motoneuron activity throughout the limb. The proposed two-level CPG organization has been investigated with a computational model which incorporates interactions between the CPG, spinal circuits and afferent inputs. The model includes interacting populations of spinal interneurons and motoneurons modeled in the Hodgkin-Huxley style. Our simulations demonstrate that a relatively simple CPG with separate RG and PF networks can realistically reproduce many experimental phenomena including spontaneous deletions of motoneuron activity and a variety of effects of afferent stimulation. The model suggests plausible explanations for a number of features of real CPG operation that would be difficult to explain in the framework of the classical single-level CPG organization. Some modeling predictions and directions for further studies of locomotor CPG organization are discussed. PMID:17936363

  10. Evolution of central pattern generators and rhythmic behaviours

    PubMed Central

    Katz, Paul S.

    2016-01-01

    Comparisons of rhythmic movements and the central pattern generators (CPGs) that control them uncover principles about the evolution of behaviour and neural circuits. Over the course of evolutionary history, gradual evolution of behaviours and their neural circuitry within any lineage of animals has been a predominant occurrence. Small changes in gene regulation can lead to divergence of circuit organization and corresponding changes in behaviour. However, some behavioural divergence has resulted from large-scale rewiring of the neural network. Divergence of CPG circuits has also occurred without a corresponding change in behaviour. When analogous rhythmic behaviours have evolved independently, it has generally been with different neural mechanisms. Repeated evolution of particular rhythmic behaviours has occurred within some lineages due to parallel evolution or latent CPGs. Particular motor pattern generating mechanisms have also evolved independently in separate lineages. The evolution of CPGs and rhythmic behaviours shows that although most behaviours and neural circuits are highly conserved, the nature of the behaviour does not dictate the neural mechanism and that the presence of homologous neural components does not determine the behaviour. This suggests that although behaviour is generated by neural circuits, natural selection can act separately on these two levels of biological organization. PMID:26598733

  11. Evolution of central pattern generators and rhythmic behaviours.

    PubMed

    Katz, Paul S

    2016-01-05

    Comparisons of rhythmic movements and the central pattern generators (CPGs) that control them uncover principles about the evolution of behaviour and neural circuits. Over the course of evolutionary history, gradual evolution of behaviours and their neural circuitry within any lineage of animals has been a predominant occurrence. Small changes in gene regulation can lead to divergence of circuit organization and corresponding changes in behaviour. However, some behavioural divergence has resulted from large-scale rewiring of the neural network. Divergence of CPG circuits has also occurred without a corresponding change in behaviour. When analogous rhythmic behaviours have evolved independently, it has generally been with different neural mechanisms. Repeated evolution of particular rhythmic behaviours has occurred within some lineages due to parallel evolution or latent CPGs. Particular motor pattern generating mechanisms have also evolved independently in separate lineages. The evolution of CPGs and rhythmic behaviours shows that although most behaviours and neural circuits are highly conserved, the nature of the behaviour does not dictate the neural mechanism and that the presence of homologous neural components does not determine the behaviour. This suggests that although behaviour is generated by neural circuits, natural selection can act separately on these two levels of biological organization.

  12. Temperature-dependent regulation of vocal pattern generator.

    PubMed

    Yamaguchi, Ayako; Gooler, David; Herrold, Amy; Patel, Shailja; Pong, Winnie W

    2008-12-01

    Vocalizations of Xenopus laevis are generated by central pattern generators (CPGs). The advertisement call of male X. laevis is a complex biphasic motor rhythm consisting of fast and slow trills (a train of clicks). We found that the trill rate of these advertisement calls is sensitive to temperature and that this rate modification of the vocal rhythms originates in the central pattern generators. In vivo the rates of fast and slow trills increased linearly with an increase in temperature. In vitro a similar linear relation between temperature and compound action potential frequency in the laryngeal nerve was found when fictive advertisement calls were evoked in the isolated brain. Temperature did not limit the contractile properties of laryngeal muscles within the frequency range of vocalizations. We next took advantage of the temperature sensitivity of the vocal CPG in vitro to localize the source of the vocal rhythms. We focused on the dorsal tegmental area of the medulla (DTAM), a brain stem nucleus that is essential for vocal production. We found that bilateral cooling of DTAM reduced both fast and slow trill rates. Thus we conclude that DTAM is a source of biphasic vocal rhythms.

  13. Gene regulation networks generate diverse pigmentation patterns in plants.

    PubMed

    Albert, Nick W; Davies, Kevin M; Schwinn, Kathy E

    2014-01-01

    The diversity of pigmentation patterns observed in plants occurs due to the spatial distribution and accumulation of colored compounds, which may also be associated with structural changes to the tissue. Anthocyanins are flavonoids that provide red/purple/blue coloration to plants, often forming complex patterns such as spots, stripes, and vein-associated pigmentation, particularly in flowers. These patterns are determined by the activity of MYB-bHLH-WDR (MBW) transcription factor complexes, which activate the anthocyanin biosynthesis genes, resulting in anthocyanin pigment accumulation. Recently, we established that the MBW complex controlling anthocyanin synthesis acts within a gene regulation network that is conserved within at least the Eudicots. This network involves hierarchy, reinforcement, and feedback mechanisms that allow for stringent and responsive regulation of the anthocyanin biosynthesis genes. The gene network and mobile nature of the WDR and R3-MYB proteins provide exciting new opportunities to explore the basis of pigmentation patterning, and to investigate the evolutionary history of the MBW components in land plants.

  14. Phylogenetic and individual variation in gastropod central pattern generators.

    PubMed

    Sakurai, Akira; Katz, Paul S

    2015-09-01

    Gastropod molluscs provide a unique opportunity to explore the neural basis of rhythmic behaviors because of the accessibility of their nervous systems and the number of species that have been examined. Detailed comparisons of the central pattern generators (CPGs) underlying rhythmic feeding and swimming behaviors highlight the presence and effects of variation in neural circuits both across and within species. The feeding motor pattern of the snail, Lymnaea, is stereotyped, whereas the feeding motor pattern in the sea hare, Aplysia, is variable. However, the Aplysia motor pattern is regularized with operant conditioning or by mimicking learning using the dynamic clamp to change properties of CPG neurons. Swimming evolved repeatedly in marine gastropods. Distinct neural mechanisms underlie dissimilar forms of swimming, with homologous neurons playing different roles. However, even similar swimming behaviors in different species can be produced by distinct neural mechanisms, resulting from different synaptic connectivity of homologous neurons. Within a species, there can be variation in the strength and even valence of synapses, which does not have functional relevance under normal conditions, but can cause some individuals to be more susceptible to lesion of the circuit. This inter- and intra-species variation provides novel insights into CPG function and plasticity.

  15. Generation of Viable Cell and Biomaterial Patterns by Laser Transfer

    NASA Astrophysics Data System (ADS)

    Ringeisen, Bradley

    2001-03-01

    In order to fabricate and interface biological systems for next generation applications such as biosensors, protein recognition microarrays, and engineered tissues, it is imperative to have a method of accurately and rapidly depositing different active biomaterials in patterns or layered structures. Ideally, the biomaterial structures would also be compatible with many different substrates including technologically relevant platforms such as electronic circuits or various detection devices. We have developed a novel laser-based technique, termed matrix assisted pulsed laser evaporation direct write (MAPLE DW), that is able to direct write patterns and three-dimensional structures of numerous biologically active species ranging from proteins and antibodies to living cells. Specifically, we have shown that MAPLE DW is capable of forming mesoscopic patterns of living prokaryotic cells (E. coli bacteria), living mammalian cells (Chinese hamster ovaries), active proteins (biotinylated bovine serum albumin, horse radish peroxidase), and antibodies specific to a variety of classes of cancer related proteins including intracellular and extracellular matrix proteins, signaling proteins, cell cycle proteins, growth factors, and growth factor receptors. In addition, patterns of viable cells and active biomolecules were deposited on different substrates including metals, semiconductors, nutrient agar, and functionalized glass slides. We will present an explanation of the laser-based transfer mechanism as well as results from our recent efforts to fabricate protein recognition microarrays and tissue-based microfluidic networks.

  16. Torque-stiffness-controlled dynamic walking with central pattern generators.

    PubMed

    Huang, Yan; Vanderborght, Bram; Van Ham, Ronald; Wang, Qining

    2014-12-01

    Walking behavior is modulated by controlling joint torques in most existing passivity-based bipeds. Controlled Passive Walking with adaptable stiffness exhibits controllable natural motions and energy efficient gaits. In this paper, we propose torque-stiffness-controlled dynamic bipedal walking, which extends the concept of Controlled Passive Walking by introducing structured control parameters and a bio-inspired control method with central pattern generators. The proposed walking paradigm is beneficial in clarifying the respective effects of the external actuation and the internal natural dynamics. We present a seven-link biped model to validate the presented walking. Effects of joint torque and joint stiffness on gait selection, walking performance and walking pattern transitions are studied in simulations. The work in this paper develops a new solution of motion control of bipedal robots with adaptable stiffness and provides insights of efficient and sophisticated walking gaits of humans.

  17. The generation of vertebral segmental patterning in the chick embryo.

    PubMed

    Senthinathan, Biruntha; Sousa, Cátia; Tannahill, David; Keynes, Roger

    2012-06-01

    We have carried out a series of experimental manipulations in the chick embryo to assess whether the notochord, neural tube and spinal nerves influence segmental patterning of the vertebral column. Using Pax1 expression in the somite-derived sclerotomes as a marker for segmentation of the developing intervertebral disc, our results exclude such an influence. In contrast to certain teleost species, where the notochord has been shown to generate segmentation of the vertebral bodies (chordacentra), these experiments indicate that segmental patterning of the avian vertebral column arises autonomously in the somite mesoderm. We suggest that in amniotes, the subdivision of each sclerotome into non-miscible anterior and posterior halves plays a critical role in establishing vertebral segmentation, and in maintaining left/right alignment of the developing vertebral elements at the body midline.

  18. Excitable Oscillators as Models for Central Pattern Generators

    NASA Astrophysics Data System (ADS)

    Taylor, David; Holmes, Philip; Cohen, Avis H.

    Chains of coupled oscillators have been used to model the central pattern generator for locomotion in lamprey1,2,3, as well as electrical waves in the mammalian small intestine4. In this paper we examine a variation on the equations for the coupled oscillators used in a number of these papers. In particular, we investigate the effect of modeling the uncoupled oscillators as excitable. The motivation behind this is that it may provide some insight into the electrical activity of the lamprey spinal cord with brainstem attached5

  19. Vapor-Generator Wand Helps To Reveal Airflow Patterns

    NASA Technical Reports Server (NTRS)

    Robelen, David B.

    1993-01-01

    In vapor-generator wand, liquid propylene glycol flows into electrically heated stainless-steel tube. Liquid boils in heated tube, and emerging vapor forms dense, smoke-like fog used to make airflow patterns visible. Built in variety of sizes, suitable for uses ranging from tabletop demonstrations to research in wind tunnels. For best viewing, plume illuminated by bright, focused incandescent spotlight at right angle to viewing direction. Viewing further enhanced by coating walls of test chamber with flat, dark color to minimize reflections and increase contrast.

  20. Sensory feedback in CNN-based central pattern generators.

    PubMed

    Arena, Paolo; Fortuna, Luigi; Frasca, Mattia; Patane, Luca

    2003-12-01

    Central Pattern Generators (CPGs) are a suitable paradigm to solve the problem of locomotion control in walking robots. CPGs are able to generate feed-forward signals to achieve a proper coordination among the robot legs. In literature they are often modelled as networks of coupled nonlinear systems. However the topic of feedback in these systems is rarely addressed. On the other hand feedback is essential for locomotion. In this paper the CPG for a hexapod robot is implemented through Cellular Neural Networks (CNNs). Feedback is included in the CPG controller by exploiting the dynamic properties of the CPG motor-neurons, such as synchronization issue and local bifurcations. These universal paradigms provide the essential issues to include sensory feedback in CPG architectures based on coupled nonlinear systems. Experiments on a dynamic model of a hexapod robot are presented to validate the approach introduced.

  1. Examining Involvement as a Critical Factor: Perceptions from First Generation and Non-First Generation College Students

    ERIC Educational Resources Information Center

    Davenport, Mona Yvette

    2010-01-01

    This study tested the perceptions of involvement components (Non-Academic Facility Usage, Intra-Racial Relations, Campus and Charleston Involvement, Faculty Interaction, Academic Facility Usage, Inter-Racial Relations, Cultural Center Usage, and Athletic Facilities Usage) for first generation and non-first generation African American and Hispanic…

  2. MULTIOBJECTIVE OPTIMIZATION POWER GENERATION SYSTEMS INVOLVING CHEMICAL LOOPING COMBUSTION

    SciTech Connect

    Juan M. Salazar; Urmila M. Diwekar; Stephen E. Zitney

    2009-01-01

    Integrated Gasification Combined Cycle (IGCC) system using coal gasification is an important approach for future energy options. This work focuses on understading the system operation and optimizing it in the presence of uncertain operating conditions using ASPEN Plus and CAPE-OPEN compliant stochastic simulation and multiobjective optimization capabilities developed by Vishwamitra Research Institute. The feasible operating surface for the IGCC system is generated and deterministic multiobjective optimization is performed. Since the feasible operating space is highly non-convex, heuristics based techniques that do not require gradient information are used to generate the Pareto surface. Accurate CFD models are simultaneously developed for the gasifier and chemical looping combustion system to characterize and quantify the process uncertainty in the ASPEN model.

  3. Error-budget paradigms and laser mask pattern generator evolution

    NASA Astrophysics Data System (ADS)

    Hamaker, H. Christopher; Jolley, Matthew J.; Berwick, Andrew D.

    2009-01-01

    The evolution of the ALTA(R) series of laser mask pattern generators has increased the relative contribution of intensity errors on critical-dimension (CD) control to those from placement errors. This paradigm shift has driven a change in rasterization strategy wherein aerial image sharpness is improved at the cost of a slight decrease in the averaging of column-to-column placement errors. Print performance evaluation using small-area CD test patterns show improvements in stripe-axis local CD uniformity (CDU) 3σ values of 15-25% using the new strategy, and systematic brush-error contributions were reduced by 50%. The increased importance of intensity errors, coupled with the improvement of ALTA system performance, has also made the mask-blank and process-induced errors a more significant part of the overall error budget. A simple model based on two components, a pattern-invariant footprint and one related to the exposure density ρ(x, y), is shown to describe adequately the errors induced by these sources. The first component is modeled by a fourth-order, two-dimensional polynomial, whereas the second is modeled as a convolution of ρ(x, y) with one or more Gaussian kernels. Implementation of this model on the ALTA 4700 system shows improvements in global CDU of 50%.

  4. The New Generation of Thai Fathers: Breadwinners Involved in Parenting.

    PubMed

    Sriyasak, Atcharawadee; Almqvist, Anna-Lena; Sridawruang, Chaweewan; Neamsakul, Wanwadee; Häggström-Nordin, Elisabet

    2016-05-23

    Becoming a father for the first time might cause great changes in a man's identity and lifestyle. Teenage fathers must strive to balance two competing roles: the teenage role and the father role. The current study design followed grounded theory methodology to gain a deeper understanding of how Thai teenage fathers reason about becoming and being a father from a gender equality perspective. Participants were selected from a heterogeneous group of fathers until saturation was reached (n = 25). Most of the fathers were cohabiting with their partner in an extended family. An interview guide was developed, a pilot study was undertaken, and interviews were performed on two different occasions: once during the second trimester of pregnancy and again when the baby was 5 to 6 months old. The core category, "Male breadwinners involved in parenting," encompassed persons making the transition from being solely a teenager to being a teenage father. Most of the fathers accepted the unintended pregnancy and took on the expected breadwinning responsibility of a father. They prepared for fatherhood and changed their lifestyle. Their families provided support. Nevertheless, the fathers sought to avoid further unplanned parenthood by learning about family planning. The teenage fathers emphasized breadwinning first, then involved himself in the child and the housework. These findings provide an increased understanding of Thai teenage fathers.

  5. Octopamine modulates a central pattern generator associated with egg-laying in the locust, Locusta migratoria.

    PubMed

    Wong, Raymond; Lange, Angela B

    2014-04-01

    Egg-laying in Locusta migratoria involves the control of a variety of complex behavioural patterns including those that regulate digging of the oviposition hole and retention of eggs during digging. These two behavioural patterns are under the control of central pattern generators (CPGs). The digging and egg-retention CPGs are coordinated and integrated with overlapping locations of neural substrate within the VIIth and VIIIth abdominal ganglia of the central nervous system (CNS). In fact, the egg-retention CPG of the VIIth abdominal ganglion is involved in both egg-retention and protraction of the abdomen during digging. The biogenic amine, octopamine, has peripheral effects on oviduct muscle, relaxing basal tension of the lateral and upper common oviduct and enabling egg passage. Here we show that octopamine also modulates the pattern of the egg-retention CPG by altering the motor pattern that controls the external ventral protractor of the VIIth abdominal segment. There is no change in the motor pattern that goes to the oviducts. Octopamine decreased the frequency of the largest amplitude action potential and decreased burst duration while leading to an increase in cycle duration and interburst interval. The effects of octopamine were greatly reduced in the presence of the α-adrenergic blocker, phentolamine, indicating that the action of octopamine was via a receptor. Thus, octopamine orchestrates events that can lead to oviposition, centrally inhibiting the digging behavior and peripherally relaxing the lateral and common oviducts to enable egg-laying.

  6. Chromosome catastrophes involve replication mechanisms generating complex genomic rearrangements.

    PubMed

    Liu, Pengfei; Erez, Ayelet; Nagamani, Sandesh C Sreenath; Dhar, Shweta U; Kołodziejska, Katarzyna E; Dharmadhikari, Avinash V; Cooper, M Lance; Wiszniewska, Joanna; Zhang, Feng; Withers, Marjorie A; Bacino, Carlos A; Campos-Acevedo, Luis Daniel; Delgado, Mauricio R; Freedenberg, Debra; Garnica, Adolfo; Grebe, Theresa A; Hernández-Almaguer, Dolores; Immken, LaDonna; Lalani, Seema R; McLean, Scott D; Northrup, Hope; Scaglia, Fernando; Strathearn, Lane; Trapane, Pamela; Kang, Sung-Hae L; Patel, Ankita; Cheung, Sau Wai; Hastings, P J; Stankiewicz, Paweł; Lupski, James R; Bi, Weimin

    2011-09-16

    Complex genomic rearrangements (CGRs) consisting of two or more breakpoint junctions have been observed in genomic disorders. Recently, a chromosome catastrophe phenomenon termed chromothripsis, in which numerous genomic rearrangements are apparently acquired in one single catastrophic event, was described in multiple cancers. Here, we show that constitutionally acquired CGRs share similarities with cancer chromothripsis. In the 17 CGR cases investigated, we observed localization and multiple copy number changes including deletions, duplications, and/or triplications, as well as extensive translocations and inversions. Genomic rearrangements involved varied in size and complexities; in one case, array comparative genomic hybridization revealed 18 copy number changes. Breakpoint sequencing identified characteristic features, including small templated insertions at breakpoints and microhomology at breakpoint junctions, which have been attributed to replicative processes. The resemblance between CGR and chromothripsis suggests similar mechanistic underpinnings. Such chromosome catastrophic events appear to reflect basic DNA metabolism operative throughout an organism's life cycle.

  7. Microfluidics for genome-wide studies involving next generation sequencing

    PubMed Central

    Murphy, Travis W.; Lu, Chang

    2017-01-01

    Next-generation sequencing (NGS) has revolutionized how molecular biology studies are conducted. Its decreasing cost and increasing throughput permit profiling of genomic, transcriptomic, and epigenomic features for a wide range of applications. Microfluidics has been proven to be highly complementary to NGS technology with its unique capabilities for handling small volumes of samples and providing platforms for automation, integration, and multiplexing. In this article, we review recent progress on applying microfluidics to facilitate genome-wide studies. We emphasize on several technical aspects of NGS and how they benefit from coupling with microfluidic technology. We also summarize recent efforts on developing microfluidic technology for genomic, transcriptomic, and epigenomic studies, with emphasis on single cell analysis. We envision rapid growth in these directions, driven by the needs for testing scarce primary cell samples from patients in the context of precision medicine.

  8. Patterns of Romantic Involvement among Emerging Adults: Psychosocial Correlates and Precursors

    ERIC Educational Resources Information Center

    Shulman, Shmuel; Scharf, Miri; Livne, Yaara; Barr, Tamuz

    2013-01-01

    The present study examined patterns of romantic involvement in 100 Israeli emerging adults (54 males) who were followed from age 22 to 29 years. Analyses of interviews at age 29 yielded four distinctive relational patterns that are associated with different levels of concurrent wellbeing: Intimately committed, Intimate, Non- intimately committed,…

  9. Involvement of Working Memory in College Students' Sequential Pattern Learning and Performance

    ERIC Educational Resources Information Center

    Kundey, Shannon M. A.; De Los Reyes, Andres; Rowan, James D.; Lee, Bern; Delise, Justin; Molina, Sabrina; Cogdill, Lindsay

    2013-01-01

    When learning highly organized sequential patterns of information, humans and nonhuman animals learn rules regarding the hierarchical structures of these sequences. In three experiments, we explored the role of working memory in college students' sequential pattern learning and performance in a computerized task involving a sequential…

  10. Anatomical Pathways Involved in Generating and Sensing Rhythmic Whisker Movements

    PubMed Central

    Bosman, Laurens W. J.; Houweling, Arthur R.; Owens, Cullen B.; Tanke, Nouk; Shevchouk, Olesya T.; Rahmati, Negah; Teunissen, Wouter H. T.; Ju, Chiheng; Gong, Wei; Koekkoek, Sebastiaan K. E.; De Zeeuw, Chris I.

    2011-01-01

    The rodent whisker system is widely used as a model system for investigating sensorimotor integration, neural mechanisms of complex cognitive tasks, neural development, and robotics. The whisker pathways to the barrel cortex have received considerable attention. However, many subcortical structures are paramount to the whisker system. They contribute to important processes, like filtering out salient features, integration with other senses, and adaptation of the whisker system to the general behavioral state of the animal. We present here an overview of the brain regions and their connections involved in the whisker system. We do not only describe the anatomy and functional roles of the cerebral cortex, but also those of subcortical structures like the striatum, superior colliculus, cerebellum, pontomedullary reticular formation, zona incerta, and anterior pretectal nucleus as well as those of level setting systems like the cholinergic, histaminergic, serotonergic, and noradrenergic pathways. We conclude by discussing how these brain regions may affect each other and how they together may control the precise timing of whisker movements and coordinate whisker perception. PMID:22065951

  11. General principles of rhythmogenesis in central pattern generator networks.

    PubMed

    Harris-Warrick, Ronald M

    2010-01-01

    The cellular and ionic mechanisms that generate the rhythm in central pattern generator (CPG) networks for simple movements are not well understood. Using vertebrate locomotion, respiration and mastication as exemplars, I describe four main principles of rhythmogenesis: (1) rhythmogenic ionic currents underlie all CPG networks, regardless of whether they are driven by a network pacemaker or an endogenous pacemaker neuron kernel; (2) fast synaptic transmission often evokes slow currents that can affect cycle frequency; (3) there are likely to be multiple and redundant mechanisms for rhythmogenesis in any essential CPG network; and (4) glial cells may participate in CPG network function. The neural basis for rhythmogenesis in simple behaviors has been studied for almost 100 years, yet we cannot identify with certainty the detailed mechanisms by which rhythmic behaviors are generated in any vertebrate system. Early studies focused on whether locomotor rhythms were generated by a chain of coupled reflexes that require sensory feedback, or by a central neural network. By now there is general agreement that for the major rhythmic behaviors (including locomotion, respiration, and mastication, the subjects of this book), there exist CPG networks within the central nervous system that are able to drive the basic rhythmic behavior in the complete absence of sensory feedback. This of course does not eliminate an important role for sensory feedback, which certainly affects cycle frequency and for some behaviors determines the timing of one phase of the behavior (Borgmann et al., 2009; Pearson, 2008). Given the existence of CPGs, the question of rhythmogenesis can be rephrased to ask how these networks determine the timing of the rhythmic behavior. In this chapter, I focus on cellular and molecular mechanisms that could underlie rhythmogenesis in CPG networks, especially those that drive locomotion, respiration, and mastication.

  12. Patterns and Predictors of Involvement among Fathers of Children Born to Adolescent Mothers

    ERIC Educational Resources Information Center

    Lewin, Amy; Mitchell, Stephanie J.; Burrell, Lori; Beers, Lee S. A.; Duggan, Anne K.

    2011-01-01

    Father involvement may be an important support for children born to adolescent mothers. This study examines patterns and predictors of father involvement, as reported by adolescent mothers, from their child's infancy through toddlerhood. Data were collected from urban, primarily African American, adolescent mothers (N = 138) in four interviews,…

  13. Mexican-Origin Mothers' and Fathers' Involvement in Adolescents' Peer Relationships: A Pattern-Analytic Approach

    ERIC Educational Resources Information Center

    Updegraff, Kimberly A.; Perez-Brena, Norma J.; Baril, Megan E.; McHale, Susan M.; Umana-Taylor, Adriana J.

    2012-01-01

    Using latent profile analysis, the authors examined patterns of mother-father involvement in adolescents' peer relationships along three dimensions--support, guidance, and restrictions--in 240 Mexican-origin families. Three profiles were identified: (a) High Mother Involvement (mothers higher than fathers on all three dimensions), (b) High…

  14. Patterns of Parental Involvement in Selected OECD Countries: Cross-National Analyses of PISA

    ERIC Educational Resources Information Center

    Hartas, Dimitra

    2015-01-01

    Using data from the Programme for International Student Assessment (PISA), patterns of parental involvement were examined in selected OECD countries. The findings showed that, irrespective of educational qualifications, parents were frequently involved in their children's learning at the start of primary school and at age 15. Cross-national…

  15. The Differential Patterns of College Involvement between Transfer and Native Students

    ERIC Educational Resources Information Center

    Wang, Xueli; Wharton, Barbara I.

    2010-01-01

    Guided by a conceptual model of student involvement, this study examined the patterns of undergraduate student involvement in academic and social activities and student services, focusing on a comparison between transfer and native students at a large, Midwestern public research university. The results indicated that compared to native students,…

  16. Sexually differentiated central pattern generators in Xenopus laevis.

    PubMed

    Zornik, Erik; Yamaguchi, Ayako

    2008-06-01

    Understanding the neural mechanisms that underlie the function of central pattern generators (CPGs) presents a formidable challenge requiring sophisticated tools and well-chosen model systems. In this article, we describe recent work on vocalizations of the African clawed frog Xenopus laevis. These behaviors are driven by sexually differentiated CPGs and are exceptionally well suited to this objective. In particular, a simplified mechanism of vocal production (independent of respiratory musculature) allows straightforward interpretations of nerve activity with respect to behavior. Furthermore, the development of a fictively vocalizing isolated brain, together with the finding of rapid androgen-induced masculinization of female vocalizations, provides an invaluable tool for determining how new behaviors arise from existing circuits.

  17. Sexually differentiated central pattern generators in Xenopus laevis

    PubMed Central

    Zornik, Erik; Yamaguchi, Ayako

    2008-01-01

    Understanding the neural mechanisms that underlie the function of central pattern generators (CPGs) presents a formidable challenge requiring sophisticated tools and well-chosen model systems. In this article, we describe recent work on vocalizations of the African clawed frog Xenopus laevis. These behaviors are driven by sexually differentiated CPGs and are exceptionally well suited to this objective. In particular, a simplified mechanism of vocal production (independent of respiratory musculature) allows straightforward interpretations of nerve activity with respect to behavior. Furthermore, the development of a fictively vocalizing isolated brain, together with the finding of rapid androgen-induced masculinization of female vocalizations, provides an invaluable tool for determining how new behaviors arise from existing circuits. PMID:18471902

  18. Generation of Earth's First-Order Biodiversity Pattern

    NASA Astrophysics Data System (ADS)

    Krug, Andrew Z.; Jablonski, David; Valentine, James W.; Roy, Kaustuv

    2009-02-01

    The first-order biodiversity pattern on Earth today and at least as far back as the Paleozoic is the latitudinal diversity gradient (LDG), a decrease in richness of species and higher taxa from the equator to the poles. LDGs are produced by geographic trends in origination, extinction, and dispersal over evolutionary timescales, so that analyses of static patterns will be insufficient to reveal underlying processes. The fossil record of marine bivalve genera, a model system for the analysis of biodiversity dynamics over large temporal and spatial scales, shows that an origination and range-expansion gradient plays a major role in generating the LDG. Peak origination rates and peak diversities fall within the tropics, with range expansion out of the tropics the predominant spatial dynamic thereafter. The origination-diversity link occurs even in a "contrarian" group whose diversity peaks at midlatitudes, an exception proving the rule that spatial variations in origination are key to latitudinal diversity patterns. Extinction rates are lower in polar latitudes (≥60°) than in temperate zones and thus cannot create the observed gradient alone. They may, however, help to explain why origination and immigration are evidently damped in higher latitudes. We suggest that species require more resources in higher latitudes, for the seasonality of primary productivity increases by more than an order of magnitude from equatorial to polar regions. Higher-latitude species are generalists that, unlike potential immigrants, are adapted to garner the large share of resources required for incumbency in those regions. When resources are opened up by extinctions, lineages spread chiefly poleward and chiefly through speciation.

  19. Generation of Earth's first-order biodiversity pattern.

    PubMed

    Krug, Andrew Z; Jablonski, David; Valentine, James W; Roy, Kaustuv

    2009-01-01

    The first-order biodiversity pattern on Earth today and at least as far back as the Paleozoic is the latitudinal diversity gradient (LDG), a decrease in richness of species and higher taxa from the equator to the poles. LDGs are produced by geographic trends in origination, extinction, and dispersal over evolutionary timescales, so that analyses of static patterns will be insufficient to reveal underlying processes. The fossil record of marine bivalve genera, a model system for the analysis of biodiversity dynamics over large temporal and spatial scales, shows that an origination and range-expansion gradient plays a major role in generating the LDG. Peak origination rates and peak diversities fall within the tropics, with range expansion out of the tropics the predominant spatial dynamic thereafter. The origination-diversity link occurs even in a "contrarian" group whose diversity peaks at midlatitudes, an exception proving the rule that spatial variations in origination are key to latitudinal diversity patterns. Extinction rates are lower in polar latitudes (> or =60 degrees ) than in temperate zones and thus cannot create the observed gradient alone. They may, however, help to explain why origination and immigration are evidently damped in higher latitudes. We suggest that species require more resources in higher latitudes, for the seasonality of primary productivity increases by more than an order of magnitude from equatorial to polar regions. Higher-latitude species are generalists that, unlike potential immigrants, are adapted to garner the large share of resources required for incumbency in those regions. When resources are opened up by extinctions, lineages spread chiefly poleward and chiefly through speciation.

  20. Flexibility of the axial central pattern generator network for locomotion in the salamander.

    PubMed

    Ryczko, D; Knüsel, J; Crespi, A; Lamarque, S; Mathou, A; Ijspeert, A J; Cabelguen, J M

    2015-03-15

    In tetrapods, limb and axial movements are coordinated during locomotion. It is well established that inter- and intralimb coordination show considerable variations during ongoing locomotion. Much less is known about the flexibility of the axial musculoskeletal system during locomotion and the neural mechanisms involved. Here we examined this issue in the salamander Pleurodeles waltlii, which is capable of locomotion in both aquatic and terrestrial environments. Kinematics of the trunk and electromyograms from the mid-trunk epaxial myotomes were recorded during four locomotor behaviors in freely moving animals. A similar approach was used during rhythmic struggling movements since this would give some insight into the flexibility of the axial motor system. Our results show that each of the forms of locomotion and the struggling behavior is characterized by a distinct combination of mid-trunk motor patterns and cycle durations. Using in vitro electrophysiological recordings in isolated spinal cords, we observed that the spinal networks activated with bath-applied N-methyl-d-aspartate could generate these axial motor patterns. In these isolated spinal cord preparations, the limb motor nerve activities were coordinated with each mid-trunk motor pattern. Furthermore, isolated mid-trunk spinal cords and hemicords could generate the mid-trunk motor patterns. This indicates that each side of the cord comprises a network able to generate coordinated axial motor activity. The roles of descending and sensory inputs in the behavior-related changes in axial motor coordination are discussed.

  1. Two-stage Turing model for generating pigment patterns on the leopard and the jaguar.

    PubMed

    Liu, R T; Liaw, S S; Maini, P K

    2006-07-01

    Based on the results of phylogenetic analysis, which showed that flecks are the primitive pattern of the felid family and all other patterns including rosettes and blotches develop from it, we construct a Turing reaction-diffusion model which generates spot patterns initially. Starting from this spotted pattern, we successfully generate patterns of adult leopards and jaguars by tuning parameters of the model in the subsequent phase of patterning.

  2. Two-stage Turing model for generating pigment patterns on the leopard and the jaguar

    NASA Astrophysics Data System (ADS)

    Liu, R. T.; Liaw, S. S.; Maini, P. K.

    2006-07-01

    Based on the results of phylogenetic analysis, which showed that flecks are the primitive pattern of the felid family and all other patterns including rosettes and blotches develop from it, we construct a Turing reaction-diffusion model which generates spot patterns initially. Starting from this spotted pattern, we successfully generate patterns of adult leopards and jaguars by tuning parameters of the model in the subsequent phase of patterning.

  3. Caregiving Practice Patterns of Asian, Hispanic, and Non-Hispanic White American Family Caregivers of Older Adults Across Generations.

    PubMed

    Miyawaki, Christina E

    2016-03-01

    This study is a cross-sectional investigation of caregiving practice patterns among Asian, Hispanic and non-Hispanic White American family caregivers of older adults across three immigrant generations. The 2009 California Health Interview Survey (CHIS) dataset was used, and 591 Asian, 989 Hispanic and 6537 non-Hispanic White American caregivers of older adults were selected. First, descriptive analyses of caregivers' characteristics, caregiving situations and practice patterns were examined by racial/ethnic groups and immigrant generations. Practice patterns measured were respite care use, hours and length of caregiving. Three hypotheses on caregiving patterns based on assimilation theory were tested and analyzed using logistic regression and generalized linear models by racial/ethnic groups and generations. Caregiving patterns of non-Hispanic White caregivers supported all three hypotheses regarding respite care use, caregiving hours and caregiving duration, showing less caregiving involvement in later generations. However, Asian and Hispanic counterparts showed mixed results. Third generation Asian and Hispanic caregivers used respite care the least and spent the most caregiving hours per week and had the longest caregiving duration compared to earlier generations. These caregiving patterns revealed underlying cultural values related to filial responsibility, even among later generations of caregivers of color. Findings suggest the importance of considering the cultural values of each racial/ethnic group regardless of generation when working with racially and ethnically diverse populations of family caregivers of older adults.

  4. Sensory-induced activation of pattern generators in the absence of supraspinal control.

    PubMed

    Lev-Tov, A; Etlin, A; Blivis, D

    2010-06-01

    Sacrocaudal afferent (SCA) stimulation is used in this work to study neural pathways involved in sensory-activation of central pattern generators (CPGs) in the isolated spinal cord of the neonatal rat. Surgical manipulations of the white matter funiculi and confocal imaging of back-labeled funicular pathways suggest that the CPGs are activated during SCA stimulation by crossed and uncrossed multifunicular projections of sacral neurons and that activation of short projecting proprioneurons is sufficient for the generation of the rhythm by SCA stimulation. The versatile organization of the pathways involved in the SCA-induced rhythm makes it a potent and durable activator of the CPGs in the absence of descending control from the brain. The significance of our findings and their potential clinical use are discussed.

  5. Sequential generation of two distinct synapse-driven network patterns in developing neocortex.

    PubMed

    Allène, Camille; Cattani, Adriano; Ackman, James B; Bonifazi, Paolo; Aniksztejn, Laurent; Ben-Ari, Yehezkel; Cossart, Rosa

    2008-11-26

    Developing cortical networks generate a variety of coherent activity patterns that participate in circuit refinement. Early network oscillations (ENOs) are the dominant network pattern in the rodent neocortex for a short period after birth. These large-scale calcium waves were shown to be largely driven by glutamatergic synapses albeit GABA is a major excitatory neurotransmitter in the cortex at such early stages, mediating synapse-driven giant depolarizing potentials (GDPs) in the hippocampus. Using functional multineuron calcium imaging together with single-cell and field potential recordings to clarify distinct network dynamics in rat cortical slices, we now report that the developing somatosensory cortex generates first ENOs then GDPs, both patterns coexisting for a restricted time period. These patterns markedly differ by their developmental profile, dynamics, and mechanisms: ENOs are generated before cortical GDPs (cGDPs) by the activation of glutamatergic synapses mostly through NMDARs; cENOs are low-frequency oscillations (approximately 0.01 Hz) displaying slow kinetics and gradually involving the entire network. At the end of the first postnatal week, GABA-driven cortical GDPs can be reliably monitored; cGDPs are recurrent oscillations (approximately 0.1 Hz) that repetitively synchronize localized neuronal assemblies. Contrary to cGDPs, cENOs were unexpectedly facilitated by short anoxic conditions suggesting a contribution of glutamate accumulation to their generation. In keeping with this, alterations of extracellular glutamate levels significantly affected cENOs, which are blocked by an enzymatic glutamate scavenger. Moreover, we show that a tonic glutamate current contributes to the neuronal membrane excitability when cENOs dominate network patterns. Therefore, cENOs and cGDPs are two separate aspects of neocortical network maturation that may be differentially engaged in physiological and pathological processes.

  6. Neural basis of singing in crickets: central pattern generation in abdominal ganglia

    NASA Astrophysics Data System (ADS)

    Schöneich, Stefan; Hedwig, Berthold

    2011-12-01

    The neural mechanisms underlying cricket singing behavior have been the focus of several studies, but the central pattern generator (CPG) for singing has not been localized conclusively. To test if the abdominal ganglia contribute to the singing motor pattern and to analyze if parts of the singing CPG are located in these ganglia, we systematically truncated the abdominal nerve cord of fictively singing crickets while recording the singing motor pattern from a front-wing nerve. Severing the connectives anywhere between terminal ganglion and abdominal ganglion A3 did not preclude singing, although the motor pattern became more variable and failure-prone as more ganglia were disconnected. Singing terminated immediately and permanently after transecting the connectives between the metathoracic ganglion complex and the first unfused abdominal ganglion A3. The contribution of abdominal ganglia for singing pattern generation was confirmed by intracellular interneuron recordings and current injections. During fictive singing, an ascending interneuron with its soma and dendrite in A3 depolarized rhythmically. It spiked 10 ms before the wing-opener activity and hyperpolarized in phase with the wing-closer activity. Depolarizing current injection elicited rhythmic membrane potential oscillations and spike bursts that elicited additional syllables and reliably reset the ongoing chirp rhythm. Our results disclose that the abdominal ganglion A3 is directly involved in generating the singing motor pattern, whereas the more posterior ganglia seem to provide only stabilizing feedback to the CPG circuit. Localizing the singing CPG in the anterior abdominal neuromeres now allows analyzing its circuitry at the level of identified interneurons in subsequent studies.

  7. Does Opium Dependency Affect the Pattern of Involvement in Laryngeal Cancer?

    PubMed Central

    Dabirmoghaddam, Peyman; Karimian Taheri, Ali; Ghazavi, Hosein; Ebrahimnejad, Shaghayegh; Karimian, Zahra

    2016-01-01

    Introduction: Laryngeal cancer is the second most common cancer involving the respiratory tract, second only to lung cancer. Previous studies have shown opium dependency to be a possible risk factor for laryngeal cancer. Opium consumption is a major problem in some parts of the world. The aim of this study was to investigate the effect of opium consumption on the pattern of involvement in laryngeal cancer. Methods and materials: In this analytical cross-sectional study, 44 patients diagnosed with laryngeal cancer (41 male and three female) were studied. Data were collected using a questionnaire, physical examination, and paraclinical studies. Patients were defined as opium dependent based on the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM-IV) criteria and duration of opium consumption. Results: Patients were categorized into two groups: opium-dependent (32.6%) and non-opium-dependent (67.4%) patients. The average age of the patients was 58.5±3.2 years in the opium-dependent group and 60.7±2.8 years in the non-opium-dependent group (P=non-significant). An analysis of the pattern of involvement in each group showed glottis involvement in 56%, subglottis involvement in 8%, supraglottis involvement in 32%, and hypopharyngeal involvement in 4% of the opium-dependent group compared with glottis involvement in 55.9%, subglottis involvement in 11.8%, supraglottis involvement in 32.4%, and hypopharyngeal involvement in none of the non-opium-dependent group (P=non-significant). Conclusion: There was a poor correlation between opium dependency and pattern of involvement in laryngeal cancer. Opium dependency did not lead to the development of laryngeal cancer at a younger age, based on our study. PMID:28008394

  8. Pattern of Peripheral Nerve Involvement in Spinocerebellar Ataxia Type 2: a Neurophysiological Assessment.

    PubMed

    Bezerra, Marcio Luiz Escorcio; Pedroso, José Luiz; Braga-Neto, Pedro; Abrahao, Agessandro; de Albuquerque, Marcus Vinicius Cristino; Borges, Franklin Roberto Pereira; Saraiva-Pereira, Maria Luiza; Jardim, Laura Bannach; de Oliveira Braga, Nadia Iandoli; Manzano, Gilberto Mastrocola; Barsottini, Orlando G P

    2016-12-01

    Peripheral neuropathy is frequent in spinocerebellar ataxia type 2 (SCA2), but the pattern and characteristics of nerve involvement are still an unsettled issue. This study aimed to evaluate the prevalence, extent, and distribution of nerve involvement in SCA2 patients through neurophysiological studies. Thirty-one SCA2 patients and 20 control subjects were enrolled in this study. All subjects were prospectively evaluated through electromyography, including nerve conduction, needle electromyography in proximal and distal muscles of the upper and lower limbs, and sural radial amplitude ratio (SRAR). We aimed to differentiate distal axonopathy from diffuse nerve commitment, characterizing neuronopathy. Nerve involvement was observed in 83.6 % (26 individuals) of SCA2 patients. Among these, 19 had diffuse sensory abnormalities on nerve conduction predominantly on the upper limbs, with diffuse chronic denervation on needle electromyography and elevated SRAR values. Four individuals had only diffuse sensory involvement, and 2 had only motor involvement on needle evaluation and normal nerve conduction. These were interpreted as neuronopathy due to the diffuse distribution of the involvement. One individual had distal sensory axonopathy, with lower limb predominance. In this study, we found neuronopathy as the main pattern of nerve involvement in SCA2 patients and that motor involvement is a frequent feature. This information brings new insights into the understanding of the pathophysiology of nerve involvement in SCA2 and sets some key points about the phenotype, which is relevant to guide the genetic/molecular diagnosis.

  9. The Network Spinal Wave as a Central Pattern Generator

    PubMed Central

    Epstein, Donald M.; Lemberger, Daniel

    2016-01-01

    Abstract Objectives: This article explains the research on a unique spinal wave visibly observed in association with network spinal analysis care. Since 1997, the network wave has been studied using surface electromyography (sEMG), characterized mathematically, and determined to be a unique and repeatable phenomenon. Methods: The authors provide a narrative review of the research and a context for the network wave's development. Results: The sEMG research demonstrates that the movement of the musculature of the spine during the wave phenomenon is electromagnetic and mechanical. The changes running along the spine were characterized mathematically at three distinct levels of care. Additionally, the wave has the mathematical properties of a central pattern generator (CPG). Conclusions: The network wave may be the first CPG discovered in the spine unrelated to locomotion. The mathematical characterization of the signal also demonstrates coherence at a distance between the sacral to cervical spine. According to mathematical engineers, based on studies conducted a decade apart, the wave itself is a robust phenomenon and the detection methods for this coherence may represent a new measure for central nervous system health. This phenomenon has implications for recovery from spinal cord injury and for reorganizational healing development. PMID:27243963

  10. Mutual synchronization between structure and central pattern generator

    NASA Astrophysics Data System (ADS)

    Hongu, Junichi; Iba, Daisuke

    2012-04-01

    This paper shows an evaluating method of synchronization between a structure and Central Pattern Generators (CPGs), which are embedded in a controller designed for an active mass damper. A neural oscillator composing the CPGs has nonlinear and entrainment properties. Therefore, the proposed controller has possibility to exhibit the characteristic of robustness, when the structural parameters, i.e. stiffness or damping, are changed by earthquakes and the like. Our earlier studies have proposed the new controller and ascertained the efficacy of vibration suppression. However, there has been no study to evaluate the controller's above-mentioned properties. For tuning into practical application, the reliability and robustness along with the controller's vibration mitigation performance must be analyzed. In this paper, phase reduction theory is tried to appraise the synchronization between a structure and the CPGs. In this case, the synchronization between the target structure and a single neural oscillator constituting the CPGs is required to be investigated. Therefore, the single neural oscillator's the harmonization characteristic with sinusoidal input is firstly examined, and the synchronization region is expressed using phase response curves. In addition, the mutual synchronization between the structure and the single neural oscillator is studied under sinusoidal input using the result of the harmonization characteristic.

  11. Key bifurcations of bursting polyrhythms in 3-cell central pattern generators.

    PubMed

    Wojcik, Jeremy; Schwabedal, Justus; Clewley, Robert; Shilnikov, Andrey L

    2014-01-01

    We identify and describe the key qualitative rhythmic states in various 3-cell network motifs of a multifunctional central pattern generator (CPG). Such CPGs are neural microcircuits of cells whose synergetic interactions produce multiple states with distinct phase-locked patterns of bursting activity. To study biologically plausible CPG models, we develop a suite of computational tools that reduce the problem of stability and existence of rhythmic patterns in networks to the bifurcation analysis of fixed points and invariant curves of a Poincaré return maps for phase lags between cells. We explore different functional possibilities for motifs involving symmetry breaking and heterogeneity. This is achieved by varying coupling properties of the synapses between the cells and studying the qualitative changes in the structure of the corresponding return maps. Our findings provide a systematic basis for understanding plausible biophysical mechanisms for the regulation of rhythmic patterns generated by various CPGs in the context of motor control such as gait-switching in locomotion. Our analysis does not require knowledge of the equations modeling the system and provides a powerful qualitative approach to studying detailed models of rhythmic behavior. Thus, our approach is applicable to a wide range of biological phenomena beyond motor control.

  12. Improving teacher perceptions of parent involvement patterns: Findings from a group randomized trial.

    PubMed

    Herman, Keith C; Reinke, Wendy M

    2017-03-01

    For children with the most serious and persistent academic and behavior problems, parent involvement in education, particularly teacher perceptions of involvement, is essential to avert their expected long-term negative outcomes. Despite the widespread interest in and perceived importance of parent involvement in education, however, few experimental studies have evaluated programs and practices to promote it. In this group randomized trial, we examined the effects of the Incredible Years Teacher Classroom Management program (IY TCM) on teacher perceptions of contact and comfort with parents. One hundred five classrooms with 1818 students were randomly assigned to an IY TCM or to a control, business as usual condition. Measures of key constructs included teacher ratings of parent and student behaviors, direct observations in the classroom, and a standardized academic achievement test. Latent transition analysis (LTA) was used to identify patterns of involvement over time and to determine if intervention condition predicted postintervention patterns and transitions. Four patterns of involvement were identified at baseline and at follow-up; parents of students with academic and behavior problems were most likely to be in classes with the least adaptive involvement patterns. Intervention status predicted group membership at follow-up. Specifically, intervention classroom parents were significantly more likely to transition to more adaptive teacher-rated parenting profiles at follow-up compared to control classroom parents. This is the first randomized trial we are aware of that has found that teacher training can alter teacher perceptions of parent involvement patterns. Clinical implications for students with behavior and academic problems are discussed. (PsycINFO Database Record

  13. Altering cAMP levels within a central pattern generator modifies or disrupts rhythmic motor output.

    PubMed

    Clemens, Stefan; Calin-Jageman, Robert; Sakurai, Akira; Katz, Paul S

    2007-12-01

    Cyclic AMP is a second messenger that has been implicated in the neuromodulation of rhythmically active motor patterns. Here, we tested whether manipulating cAMP affects swim motor pattern generation in the mollusc, Tritonia diomedea. Inhibiting adenylyl cyclase (AC) with 9-cyclopentyladenine (9-CPA) slowed or stopped the swim motor pattern. Inhibiting phosphodiesterase with 3-isobutyl-1-methylxanthine (IBMX) or applying dibutyryl-cAMP (dB-cAMP) disrupted the swim motor pattern, as did iontophoresing cAMP into the central pattern generator neuron C2. Additionally, during wash-in, IBMX sometimes temporarily produced extended or spontaneous swim motor patterns. Photolysis of caged cAMP in C2 after initiation of the swim motor pattern inhibited subsequent bursting. These results suggest that cAMP levels can dynamically modulate swim motor pattern generation, possibly shaping the output of the central pattern generator on a cycle-by-cycle basis.

  14. Generation of cell diversity and segmental pattern in the embryonic central nervous system of Drosophila.

    PubMed

    Technau, Gerhard M; Berger, Christian; Urbach, Rolf

    2006-04-01

    Development of the central nervous system (CNS) involves the transformation of a two-dimensional epithelial sheet of uniform ectodermal cells, the neuroectoderm, into a highly complex three-dimensional structure consisting of a huge variety of different neural cell types. Characteristic numbers of each cell type become arranged in reproducible spatial patterns, which is a prerequisite for the establishment of specific functional contacts. The fruitfly Drosophila is a suitable model to approach the mechanisms controlling the generation of cell diversity and pattern in the developing CNS, as it allows linking of gene function to individually identifiable cells. This review addresses aspects of the formation and specification of neural stem cells (neuroblasts) in Drosophila in the light of recent studies on their segmental diversification.

  15. Function generator for synthesizing complex vibration mode patterns

    NASA Technical Reports Server (NTRS)

    Naumann, E. C.; Hagood, G. J., Jr. (Inventor)

    1973-01-01

    A simple highly flexible device for synthesizing complex vibration mode patterns is described. These mode patterns can be used to identify vibration mode data. This device sums selected sine and cosine functions and then plots the sum against a linear function.

  16. Principal-Generated YouTube Video as a Method of Improving Parental Involvement

    ERIC Educational Resources Information Center

    Richards, Joey

    2013-01-01

    The purpose of this study was to evaluate the involvement level of parents and reveal whether principal-generated YouTube videos for regular communication would enhance levels of parental involvement at one North Texas Christian Middle School (pseudonym). The following questions guided this study: 1. What is the beginning level of parental…

  17. Viewing Generativity and Social Capital as Underlying Factors of Parent Involvement

    ERIC Educational Resources Information Center

    Stevens, Sharon; Patel, Nimisha

    2015-01-01

    Parent involvement in education is a multifaceted support that has many well-documented benefits for students of all ages. Parent involvement is also a common expression of generativity as defined in Erik Erikson's theory of psychosocial development. The activities parents engage in during their children's educational pursuits, as well as their…

  18. Generation of 1D interference patterns of Bloch surface waves

    NASA Astrophysics Data System (ADS)

    Kadomina, E. A.; Bezus, E. A.; Doskolovich, L. L.

    2016-09-01

    Interference patterns of Bloch surface waves with a period that is significantly less than the wavelength of incident radiation are formed using dielectric diffraction gratings located on the surface of photonic crystal. The simulation based on electromagnetic diffraction theory is used to demonstrate the possibility of high-quality interference patterns due to resonant enhancement of higher evanescent diffraction orders related to the excitation of the Bloch surface waves. The contrast of the interference patterns is close to unity, and the period is less than the period of the diffraction structure by an order of magnitude.

  19. Central pattern generators of the mammalian spinal cord.

    PubMed

    Frigon, Alain

    2012-02-01

    Neuronal networks within the spinal cord of mammals are responsible for generating various rhythmic movements, such as walking, running, swimming, and scratching. The ability to generate multiple rhythmic movements highlights the complexity and flexibility of the mammalian spinal circuitry. The present review describes features of some rhythmic motor behaviors generated by the mammalian spinal cord and discusses how the spinal circuitry is able to produce different rhythmic movements with their own sets of goals and demands.

  20. Delayed focal involvement of upper motor neurons in the Madras pattern of motor neuron disease.

    PubMed

    Massa, R; Scalise, A; Iani, C; Palmieri, M G; Bernardi, G

    1998-12-01

    We report the case of a young man from the south of India, initially presenting the typical signs of benign monomelic amyotrophy (BMA) in the left upper limb. After several years, the involvement of other limbs and the appearance of bulbar signs suggested the possible diagnosis of the Madras pattern of motor neuron disease (MMND). Serial motor evoked potential (MEP) recordings allowed detection of the onset of a focal involvement of upper motor neurons (UMN) controlling innervation in the originally amyotrophic limb. Therefore, serial MEP recordings can be useful for the early detection of sub-clinical UMN damage in motor neuron disease presenting with pure lower motor neuron (LMN) signs.

  1. Factors associated with involvement in nonmetropolitan LGBTQ organizations: Proximity? Generativity? Minority stress? Social location?

    PubMed

    Paceley, Megan S; Oswald, Ramona Faith; Hardesty, Jennifer L

    2014-01-01

    Little is known about involvement in LGBTQ organizations. Factors associated with involvement in nonmetropolitan LGBTQ organizations were examined using logistic regression and survey data from 426 LGBTQ individuals residing in a nonmetropolitan region. Involvement was examined in five types of organizations (professional, social/recreational, religious, political, and community center/charity). The same model testing proximity, generativity, minority stress, and social location hypotheses was repeated for each organization type. Results demonstrate that the generativity hypothesis is most strongly supported. Indeed, emotional attachment to the LGBTQ community significantly increased the odds of involvement in every type of organization. However, the factors associated with involvement otherwise differed by organization type. Implications for organizational leaders are discussed.

  2. Micropunching lithography for generating micro- and submicron-patterns on polymer substrates.

    PubMed

    Chakraborty, Anirban; Liu, Xinchuan; Luo, Cheng

    2012-07-02

    Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 1977(1). They offer the advantages of low weight, easy tailoring of properties and a wide spectrum of applications(2,3). Due to sensitivity of conducting polymers to environmental conditions (e.g., air, oxygen, moisture, high temperature and chemical solutions), lithographic techniques present significant technical challenges when working with these materials(4). For example, current photolithographic methods, such as ultra-violet (UV), are unsuitable for patterning the conducting polymers due to the involvement of wet and/or dry etching processes in these methods. In addition, current micro/nanosystems mainly have a planar form(5,6). One layer of structures is built on the top surfaces of another layer of fabricated features. Multiple layers of these structures are stacked together to form numerous devices on a common substrate. The sidewall surfaces of the microstructures have not been used in constructing devices. On the other hand, sidewall patterns could be used, for example, to build 3-D circuits, modify fluidic channels and direct horizontal growth of nanowires and nanotubes. A macropunching method has been applied in the manufacturing industry to create macropatterns in a sheet metal for over a hundred years. Motivated by this approach, we have developed a micropunching lithography method (MPL) to overcome the obstacles of patterning conducting polymers and generating sidewall patterns. Like the macropunching method, the MPL also includes two operations (Fig. 1): (i) cutting; and (ii) drawing. The "cutting" operation was applied to pattern three conducting polymers(4), polypyrrole (PPy), Poly(3,4-ethylenedioxythiophen)-poly(4-styrenesulphonate) (PEDOT) and polyaniline (PANI). It was also employed to create Al microstructures(7). The fabricated microstructures of conducting polymers have been used as humidity(8), chemical(8), and glucose

  3. Polychromatic Optical Vortex Generation from Patterned Cholesteric Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

    2016-06-01

    Generation of optical vortices is described in cholesteric liquid crystals with a singular point in the spatial distribution of a helix phase. The phenomenon uses the fact that a Bragg reflected light phase varies in proportion to the spatial phase of the helix, both at normal and oblique incidences. Our proposal enables high-efficiency, polychromatic generation of optical vortices without the need of a cumbersome fabrication process and fine-tuning.

  4. HIGH PREVALENCE OF RISKY INCOME GENERATION AMONG STREET-INVOLVED YOUTH IN A CANADIAN SETTING

    PubMed Central

    Cheng, Tessa; Kerr, Thomas; Small, Will; Nguyen, Paul; Wood, Evan; DeBeck, Kora

    2016-01-01

    Background Previous research has found a range of barriers to mainstream employment among street-involved youth; however, less is known about the characteristics of street-involved youth who engage in risky income generation and the potential role of substance use in perpetuating engagement in these activities. Methods Data were collected between 2005 and 2012 from the At-Risk Youth Study (ARYS), which is a prospective cohort study of street-involved youth aged 14-26 in Vancouver, Canada. Generalized estimating equations were used to identify factors associated with risky quasi-legal and illegal income generation. Participants also reported their willingness to give up these sources of income if they were not using drugs. Results Among 1,008 participants, 826 (82%) reported engaging in risky income generation activities during the study period. Factors associated with risky income generation included: homelessness, binge drug use, injection drug use, crack use, crystal methamphetamine, overdose, interactions with police, and experiencing violence; regular employment was negatively associated with this outcome (all p<0.05). Among those who reported risky income generation, 440 (53%) were willing to give up these income sources if they were not using drugs. Conclusion Risky income generation was alarmingly prevalent in our sample, and associated with higher intensity drug use and other markers of vulnerability. The majority of participants (53%) reported willingness to give up their risky income sources if they were not using drugs; however, a substantial proportion of youth (47%) indicated that they would continue to engage in risk income generation regardless of their substance use suggesting that both substance use and economic insecurity likely perpetuate risky income generation among our sample. Findings highlight opportunities to reduce risky income generation by addressing problematic substance use through better access and engagement with evidence

  5. Deciphering the organization and modulation of spinal locomotor central pattern generators.

    PubMed

    Gordon, Ian T; Whelan, Patrick J

    2006-06-01

    Networks within our spinal cord generate the basic pattern underlying walking. Over the past decade, much progress has been made in our understanding of their function in a variety of vertebrate species. A significant hurdle has been the identification of candidate populations of neurons that are involved in pattern generation in the spinal cord. Recently, systems neuroscientists in collaboration with molecular biologists have begun to dissect the circuitry underlying spinal locomotor networks. These advances have combined genetic and electrophysiological techniques using in vitro preparations of the mouse spinal cord. This review will discuss new advances in the field of spinal locomotor networks with emphasis on the mouse. Many of the behaviors fundamental to animal life, such as breathing, chewing and locomotion, are rhythmic activities controlled by neuronal networks. Discerning which neurons are members of these networks, their synaptic connectivity and their individual electrophysiological properties is essential to our understanding of how rhythmic motor behaviors are produced. It is well known that the spinal cord contains the basic circuitry to produce locomotion. However, identifying neurons and connections within spinal networks is challenging because cells that comprise the locomotor network form part of a heterogeneous mix of interneurons within the ventral spinal cord. Recently, the merging of electrophysiological and genetic approaches has provided new tools to identify classes of interneurons within the spinal cord that contribute to network function. These new findings will be discussed in this review.

  6. Superoxide Generation and Its Involvement in the Growth of Mycobacterium smegmatis

    PubMed Central

    Yeware, Amar M.; Shurpali, Ketaki D.; Athalye, Meghana C.; Sarkar, Dhiman

    2017-01-01

    Superoxide generation is inevitable in aerobic organisms, most of which have developed mechanisms to detoxify superoxides. However, its significance has not been clearly understood in mycobacteria. This study demonstrates that NADH oxidase is the major source of superoxide in Mycobacterium smegmatis and elucidates the involvement of superoxide in M. smegmatis growth. The maximum inhibition of superoxide generation was observed in the presence of diphenyleneiodonium chloride (DPI), an NADH oxidase inhibitor, compared to other standard inhibitors. After incubation for 24 h, the number of colony forming units (CFUs) was reduced by 6.8 log10 compared to the untreated culture. The inhibitory effect of DPI on M. smegmatis was reversed when the same culture was supplemented with menadione and pyrogallol, which are superoxide generators. Thus, this study reports the source of superoxide generation and its involvement in the growth of M. smegmatis. PMID:28194149

  7. Microstencils to generate defined, multi-species patterns of bacteria

    SciTech Connect

    Doktycz, Mitchel J.; Retterer, Scott T.; Pelletier, Dale A.; Timm, Collin M.; Hansen, Ryan R.

    2015-11-12

    Microbial communities are complex heterogeneous systems that are influenced by physical and chemical interactions with their environment, host, and community members. Techniques that facilitate the quantitative evaluation of how microscale organization influences the morphogenesis of multispecies communities could provide valuable insights into the dynamic behavior and organization of natural communities, the design of synthetic environments for multispecies culture, and the engineering of artificial consortia. In this work, we demonstrate a method for patterning microbes into simple arrangements that allow the quantitative measurement of growth dynamics as a function of their proximity to one another. The method combines parylene-based liftoff techniques with microfluidic delivery to simultaneously pattern multiple bacterial species with high viability using low-cost, customizable methods. Furthermore, quantitative measurements of bacterial growth for two competing isolates demonstrate that spatial coordination can play a critical role in multispecies growth and structure.

  8. The Oncoprotein BRD4-NUT Generates Aberrant Histone Modification Patterns.

    PubMed

    Zee, Barry M; Dibona, Amy B; Alekseyenko, Artyom A; French, Christopher A; Kuroda, Mitzi I

    2016-01-01

    Defects in chromatin proteins frequently manifest in diseases. A striking case of a chromatin-centric disease is NUT-midline carcinoma (NMC), which is characterized by expression of NUT as a fusion partner most frequently with BRD4. ChIP-sequencing studies from NMC patients revealed that BRD4-NUT (B4N) covers large genomic regions and elevates transcription within these domains. To investigate how B4N modulates chromatin, we performed affinity purification of B4N when ectopically expressed in 293-TREx cells and quantified the associated histone posttranslational modifications (PTM) using proteomics. We observed significant enrichment of acetylation particularly on H3 K18 and of combinatorial patterns such as H3 K27 acetylation paired with K36 methylation. We postulate that B4N complexes override the preexisting histone code with new PTM patterns that reflect aberrant transcription and that epigenetically modulate the nucleosome environment toward the NMC state.

  9. The Oncoprotein BRD4-NUT Generates Aberrant Histone Modification Patterns

    PubMed Central

    Zee, Barry M.; Dibona, Amy B.; Alekseyenko, Artyom A.; French, Christopher A.; Kuroda, Mitzi I.

    2016-01-01

    Defects in chromatin proteins frequently manifest in diseases. A striking case of a chromatin-centric disease is NUT-midline carcinoma (NMC), which is characterized by expression of NUT as a fusion partner most frequently with BRD4. ChIP-sequencing studies from NMC patients revealed that BRD4-NUT (B4N) covers large genomic regions and elevates transcription within these domains. To investigate how B4N modulates chromatin, we performed affinity purification of B4N when ectopically expressed in 293-TREx cells and quantified the associated histone posttranslational modifications (PTM) using proteomics. We observed significant enrichment of acetylation particularly on H3 K18 and of combinatorial patterns such as H3 K27 acetylation paired with K36 methylation. We postulate that B4N complexes override the preexisting histone code with new PTM patterns that reflect aberrant transcription and that epigenetically modulate the nucleosome environment toward the NMC state. PMID:27698495

  10. Microstencils to generate defined, multi-species patterns of bacteria

    DOE PAGES

    Doktycz, Mitchel J.; Retterer, Scott T.; Pelletier, Dale A.; ...

    2015-11-12

    Microbial communities are complex heterogeneous systems that are influenced by physical and chemical interactions with their environment, host, and community members. Techniques that facilitate the quantitative evaluation of how microscale organization influences the morphogenesis of multispecies communities could provide valuable insights into the dynamic behavior and organization of natural communities, the design of synthetic environments for multispecies culture, and the engineering of artificial consortia. In this work, we demonstrate a method for patterning microbes into simple arrangements that allow the quantitative measurement of growth dynamics as a function of their proximity to one another. The method combines parylene-based liftoff techniquesmore » with microfluidic delivery to simultaneously pattern multiple bacterial species with high viability using low-cost, customizable methods. Furthermore, quantitative measurements of bacterial growth for two competing isolates demonstrate that spatial coordination can play a critical role in multispecies growth and structure.« less

  11. Microstencils to generate defined, multi-species patterns of bacteria

    PubMed Central

    Timm, Collin M.; Hansen, Ryan R.; Doktycz, Mitchel J.; Retterer, Scott T.; Pelletier, Dale A.

    2015-01-01

    Microbial communities are complex heterogeneous systems that are influenced by physical and chemical interactions with their environment, host, and community members. Techniques that facilitate the quantitative evaluation of how microscale organization influences the morphogenesis of multispecies communities could provide valuable insights into the dynamic behavior and organization of natural communities, the design of synthetic environments for multispecies culture, and the engineering of artificial consortia. In this work, we demonstrate a method for patterning microbes into simple arrangements that allow the quantitative measurement of growth dynamics as a function of their proximity to one another. The method combines parylene-based liftoff techniques with microfluidic delivery to simultaneously pattern multiple bacterial species with high viability using low-cost, customizable methods. Quantitative measurements of bacterial growth for two competing isolates demonstrate that spatial coordination can play a critical role in multispecies growth and structure. PMID:26594264

  12. 32 nm imprint masks using variable shape beam pattern generators

    NASA Astrophysics Data System (ADS)

    Selinidis, Kosta; Thompson, Ecron; Schmid, Gerard; Stacey, Nick; Perez, Joseph; Maltabes, John; Resnick, Douglas J.; Yeo, Jeongho; Kim, Hoyeon; Eynon, Ben

    2008-05-01

    Imprint lithography has been included on the ITRS Lithography Roadmap at the 32, 22 and 16 nm nodes. Step and Flash Imprint Lithography (S-FIL ®) is a unique method that has been designed from the beginning to enable precise overlay for creating multilevel devices. A photocurable low viscosity monomer is dispensed dropwise to meet the pattern density requirements of the device, thus enabling imprint patterning with a uniform residual layer across a field and across entire wafers. Further, S-FIL provides sub-100 nm feature resolution without the significant expense of multi-element, high quality projection optics or advanced illumination sources. However, since the technology is 1X, it is critical to address the infrastructure associated with the fabrication of templates. For sub-32 nm device manufacturing, one of the major technical challenges remains the fabrication of full-field 1x templates with commercially viable write times. Recent progress in the writing of sub-40 nm patterns using commercial variable shape e-beam tools and non-chemically amplified resists has demonstrated a very promising route to realizing these objectives, and in doing so, has considerably strengthened imprint lithography as a competitive manufacturing technology for the sub 32nm node. Here we report the first imprinting results from sub-40 nm full-field patterns, using Samsung's current flash memory production device design. The fabrication of the template is discussed and the resulting critical dimension control and uniformity are discussed, along with image placement results. The imprinting results are described in terms of CD uniformity, etch results, and overlay.

  13. Emergent Central Pattern Generator Behavior in Gap-Junction-Coupled Hodgkin-Huxley Style Neuron Model

    PubMed Central

    Memelli, Heraldo; Solomon, Irene C.

    2012-01-01

    Most models of central pattern generators (CPGs) involve two distinct nuclei mutually inhibiting one another via synapses. Here, we present a single-nucleus model of biologically realistic Hodgkin-Huxley neurons with random gap junction coupling. Despite no explicit division of neurons into two groups, we observe a spontaneous division of neurons into two distinct firing groups. In addition, we also demonstrate this phenomenon in a simplified version of the model, highlighting the importance of afterhyperpolarization currents (IAHP) to CPGs utilizing gap junction coupling. The properties of these CPGs also appear sensitive to gap junction conductance, probability of gap junction coupling between cells, topology of gap junction coupling, and, to a lesser extent, input current into our simulated nucleus. PMID:23365558

  14. Emergent central pattern generator behavior in gap-junction-coupled Hodgkin-Huxley style neuron model.

    PubMed

    Horn, Kyle G; Memelli, Heraldo; Solomon, Irene C

    2012-01-01

    Most models of central pattern generators (CPGs) involve two distinct nuclei mutually inhibiting one another via synapses. Here, we present a single-nucleus model of biologically realistic Hodgkin-Huxley neurons with random gap junction coupling. Despite no explicit division of neurons into two groups, we observe a spontaneous division of neurons into two distinct firing groups. In addition, we also demonstrate this phenomenon in a simplified version of the model, highlighting the importance of afterhyperpolarization currents (I(AHP)) to CPGs utilizing gap junction coupling. The properties of these CPGs also appear sensitive to gap junction conductance, probability of gap junction coupling between cells, topology of gap junction coupling, and, to a lesser extent, input current into our simulated nucleus.

  15. Expression of Genes Involved in Drosophila Wing Morphogenesis and Vein Patterning Are Altered by Spaceflight

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, Patricia A.; Hosamani, Ravikumar; Bhattacharya, Sharmila

    2015-01-01

    Imaginal wing discs of Drosophila melanogaster (fruit fly) defined during embryogenesis ultimately result in mature wings of stereotyped (specific) venation patterning. Major regulators of wing disc development are the epidermal growth factor receptor (EGF), Notch, Hedgehog (Hh), Wingless (Wg), and Dpp signaling pathways. Highly stereotyped vascular patterning is also characteristic of tissues in other organisms flown in space such as the mouse retina and leaves of Arabidopsis thaliana. Genetic and other adaptations of vascular patterning to space environmental factors have not yet been systematically quantified, despite widespread recognition of their critical importance for terrestrial and microgravity applications. Here we report changes in gene expression with space flight related to Drosophila wing morphogenesis and vein patterning. In addition, genetically modified phenotypes of increasingly abnormal ectopic wing venation in the Drosophila wing1 were analyzed by NASA's VESsel GENeration Analysis (VESGEN) software2. Our goal is to further develop insightful vascular mappings associated with bioinformatic dimensions of genetic or other molecular phenotypes for correlation with genetic and other molecular profiling relevant to NASA's GeneLab and other Space Biology exploration initiatives.

  16. A simple approach for stochastic generation of spatial rainfall patterns

    NASA Astrophysics Data System (ADS)

    Tarpanelli, A.; Franchini, M.; Brocca, L.; Camici, S.; Melone, F.; Moramarco, T.

    2012-11-01

    SummaryRainfall scenarios are of considerable interest for design flood and flood risk analysis. To this end, the stochastic generation of continuous rainfall sequences is often coupled with the continuous hydrological modelling. In this context, the spatial and the temporal rainfall variability represents a significant issue, especially for basins in which the rainfall field cannot be approximated through the use of a single station. Therefore, methodologies for the spatially and temporally correlated rainfall generation are welcome. An example of such a methodology is the well-established Spatial-Temporal Neyman-Scott Rectangular Pulse (STNSRP), a modification of the single-site Neyman-Scott Rectangular Pulse (NSRP) approach, designed to incorporate specific features to reproduce the rainfall spatial cross-correlation. In order to provide a simple alternative to the STNSRP, a new method of generating synthetic rainfall time series with pre-set spatial-temporal correlation is proposed herein. This approach relies on the single-site NSRP model, which is used to generate synthetic hourly independent rainfall time series at each rain gauge station with the required temporal autocorrelation (and several other appropriately selected statistics). The rank correlation method of Iman and Conover (IC) is then applied to these synthetic rainfall time series in order to introduce the same spatial cross-correlation that exists between the observed time series. This combination of the NSRP model with the IC method consents the reproduction of the observed spatial-temporal variability of a rainfall field. In order to verify the proposed procedure, four sub-basins of the Upper Tiber River basin are investigated whose basin areas range from 165 km2 to 2040 km2. Results show that the procedure is able to preserve both the rainfall temporal autocorrelation at single site and the rainfall spatial cross-correlation at basin scale, and its performance is comparable with that of the

  17. Chemicals and heat generate different protein patterns in Acinetobacter calcoaceticus.

    PubMed

    Benndorf, D; Loffhagen, N; Babel, W

    1997-01-01

    The effect of exposing Acinetobacter calcoaceticus 69-V to DNP-stress and heat shock was examined by two-dimensional gel electrophoresis of proteins, which were detected either by autoradiography or by silver staining. Both DNP stress and heat shock led to altered patterns of protein synthesis or concentration. About 10% of the proteins which were synthesized newly or at an increased rate and about 25% of those which were found newly or with an increased concentration after DNP treatment were identified after heat shock, too.

  18. GENERATING FRACTAL PATTERNS BY USING p-CIRCLE INVERSION

    NASA Astrophysics Data System (ADS)

    Ramírez, José L.; Rubiano, Gustavo N.; Zlobec, Borut Jurčič

    2015-10-01

    In this paper, we introduce the p-circle inversion which generalizes the classical inversion with respect to a circle (p = 2) and the taxicab inversion (p = 1). We study some basic properties and we also show the inversive images of some basic curves. We apply this new transformation to well-known fractals such as Sierpinski triangle, Koch curve, dragon curve, Fibonacci fractal, among others. Then we obtain new fractal patterns. Moreover, we generalize the method called circle inversion fractal be means of the p-circle inversion.

  19. Developmental approaches to the analysis of vertebrate central pattern generators.

    PubMed

    O'Donovan, M J

    1987-10-01

    The isolated spinal cord of the chick embryo is a new preparation for analyzing the neural mechanisms and development of vertebrate motor activity. The embryonic cord can be isolated in vitro during the period of development when antagonist alternation of hindlimb motoneurons matures. The preparation is spontaneously active in vitro generating episodes of motor activity that can be recorded from muscle nerves and the ventral roots. The neural mechanisms responsible for the development and genesis of motor activity are being investigated using intra- and extracellular recording from motoneurons and electrotonic recordings of motoneuron synaptic activity from muscle nerves. The results suggest that alternating motor activity in the isolated chick cord may be generated by a mechanism in which a synaptically induced motoneuronal shunt conductance regulates the time of discharge of flexor and extensor motoneurons.

  20. Parental Involvement in Middle School Predicting College Attendance for First-Generation Students

    ERIC Educational Resources Information Center

    Bui, Khanh; Rush, Ryan A.

    2016-01-01

    Using data from the National Education Longitudinal Study, this report examined the relationship between parental involvement in eighth grade and college attendance by eight years after high school for students whose parents have no college education (i.e., first-generation students; n = 1,358) in comparison to students whose parents have some…

  1. Morphodynamics and anabranching patterns generated in the Madeira River, Brazil

    NASA Astrophysics Data System (ADS)

    Latrubesse, E. M.; Bonthius, C.; Abad, J. D.; Stevaux, J.; Filizola, N.; Frias, C. E.

    2013-12-01

    The Madeira River is the largest tributary in water discharge and sediment transport of the Amazon River. At present, this river is at the center of a controversial political discussion because the Brazilian government is building two hydroelectric plants on the Bolivia-Brazil border, flooding a long reach from near Cachuela Esperanza in the tributary Beni River, close to the Brazil-Bolivia border, up to Porto Velho. We present results from three field expeditions carried out in July-August 2011, December 2012 and March 2013. The main scope of this article is to disseminate the environmental threat suffered by the Madeira from regulation/disruption, and to present preliminary results on the geomorphologic characteristics of the Madeira channel and floodplain. Using historical radar and satellite imagery, the floodplain morpho-sedimentary units and morphology of the channel were assessed and quantified. Sediment bed and bank sampling, bathymetric surveys and velocity measurements were recorded using a single beam echo sounder and an acoustic Doppler current profiler (ADCP), respectively. Velocity data were analyzed using TRDI's WinRiverII and a MATLAB-based software package Velocity Mapping Tool. We consider that the Madeira River offers some ideal conditions to provide information on critical conditions and geomorphologic thresholds in mega-rivers. The Madeira River has been classified as a simple to moderate anabranching low-sinuosity river. The Madeira flows through a relatively simple pattern, alternating straight reaches with others that exhibit an incipient tendency to anabranch. Single beam and ADCP data yields insight into the bathymetry and flow characteristics in the channel through straight, pseudo-meandering, and anabranching stretches. We studied in detail three selected three reaches zones where three primary mechanisms for anabranching were identified: a) branches upstream and downstream in box shape pseudo-meanders; b) simple branch patterns

  2. A Pulse-Type Hardware CPG Model for Generation and Transition of Quadruped Locomotion Pattern

    NASA Astrophysics Data System (ADS)

    Hata, Keiko; Sekine, Yoshifumi; Nakabora, Yoshifumi; Saeki, Katsutoshi

    The purpose of our research is to clarify information processing functions of living organisms by neural networks using pulse-type hardware neuron models and applying pulse-type hardware neural networks to engineered models. It is known that locomotion such as walking by a living organism is generated and transited by CPG (Central Pattern Generator) in the central nervous system. We investigate a pulse-type hardware CPG model using coupled oscillator composed of pulse-type hardware neuron models. A CPG model is need to generate and control quadruped locomotion. In this paper, we describe generation and transition of oscillation patterns, corresponding to quadruped locomotion patterns. As a result, it is shown that generation and transition of oscillation patterns are possible by giving external inputs of one pulse to the CPG model.

  3. Skeletal muscle imaging in facioscapulohumeral muscular dystrophy, pattern and asymmetry of individual muscle involvement.

    PubMed

    Rijken, N H M; van der Kooi, E L; Hendriks, J C M; van Asseldonk, R J G P; Padberg, G W; Geurts, A C H; van Engelen, B G M

    2014-12-01

    To better understand postural and movement disabilities, the pattern of total body muscle fat infiltration was analyzed in a large group of patients with facioscapulohumeral muscular dystrophy. Additionally, we studied whether residual D4Z4 repeat array length adjusted for age and gender could predict the degree of muscle involvement. Total body computed tomography scans of 70 patients were used to assess the degree of fat infiltration of 42 muscles from neck to ankle level on a semi-quantitative scale. Groups of muscles that highly correlated regarding fat infiltration were identified using factor analysis. Linear regression analysis was performed using muscle fat infiltration as the dependent variable and D4Z4 repeat length and age as independent variables. A pattern of muscle fat infiltration in facioscapulohumeral muscular dystrophy could be constructed. Trunk muscles were most frequently affected. Of these, back extensors were more frequently affected than previously reported. Asymmetry in muscle involvement was seen in 45% of the muscles that were infiltrated with fat. The right-sided upper extremity showed significantly higher scores for fat infiltration compared to the left side, which could not be explained by handedness. It was possible to explain 29% of the fat infiltration based on D4Z4 repeat length, corrected for age and gender. Based on our results we conclude that frequent involvement of fat infiltration in back extensors, in addition to the abdominal muscles, emphasizes the extent of trunk involvement, which may have a profound impact on postural control even in otherwise mildly affected patients.

  4. Topology-generating interfacial pattern formation during liquid metal dealloying

    PubMed Central

    Geslin, Pierre-Antoine; McCue, Ian; Gaskey, Bernard; Erlebacher, Jonah; Karma, Alain

    2015-01-01

    Liquid metal dealloying has emerged as a novel technique to produce topologically complex nanoporous and nanocomposite structures with ultra-high interfacial area and other unique properties relevant for diverse material applications. This process is empirically known to require the selective dissolution of one element of a multicomponent solid alloy into a liquid metal to obtain desirable structures. However, how structures form is not known. Here we demonstrate, using mesoscale phase-field modelling and experiments, that nano/microstructural pattern formation during dealloying results from the interplay of (i) interfacial spinodal decomposition, forming compositional domain structures enriched in the immiscible element, and (ii) diffusion-coupled growth of the enriched solid phase and the liquid phase into the alloy. We highlight how those two basic mechanisms interact to yield a rich variety of topologically disconnected and connected structures. Moreover, we deduce scaling laws governing microstructural length scales and dealloying kinetics. PMID:26582248

  5. Topology-generating interfacial pattern formation during liquid metal dealloying

    SciTech Connect

    Geslin, Pierre -Antoine; McCue, Ian; Gaskey, Bernard; Erlebacher, Jonah; Karma, Alain

    2015-11-19

    Liquid metal dealloying has emerged as a novel technique to produce topologically complex nanoporous and nanocomposite structures with ultra-high interfacial area and other unique properties relevant for diverse material applications. This process is empirically known to require the selective dissolution of one element of a multicomponent solid alloy into a liquid metal to obtain desirable structures. However, how structures form is not known. Here we demonstrate, using mesoscale phase-field modelling and experiments, that nano/microstructural pattern formation during dealloying results from the interplay of (i) interfacial spinodal decomposition, forming compositional domain structures enriched in the immiscible element, and (ii) diffusion-coupled growth of the enriched solid phase and the liquid phase into the alloy. We highlight how those two basic mechanisms interact to yield a rich variety of topologically disconnected and connected structures. Furthermore, we deduce scaling laws governing microstructural length scales and dealloying kinetics.

  6. Topology-generating interfacial pattern formation during liquid metal dealloying

    DOE PAGES

    Geslin, Pierre -Antoine; McCue, Ian; Gaskey, Bernard; ...

    2015-11-19

    Liquid metal dealloying has emerged as a novel technique to produce topologically complex nanoporous and nanocomposite structures with ultra-high interfacial area and other unique properties relevant for diverse material applications. This process is empirically known to require the selective dissolution of one element of a multicomponent solid alloy into a liquid metal to obtain desirable structures. However, how structures form is not known. Here we demonstrate, using mesoscale phase-field modelling and experiments, that nano/microstructural pattern formation during dealloying results from the interplay of (i) interfacial spinodal decomposition, forming compositional domain structures enriched in the immiscible element, and (ii) diffusion-coupled growthmore » of the enriched solid phase and the liquid phase into the alloy. We highlight how those two basic mechanisms interact to yield a rich variety of topologically disconnected and connected structures. Furthermore, we deduce scaling laws governing microstructural length scales and dealloying kinetics.« less

  7. Pattern Generator for Bench Test of Digital Boards

    NASA Technical Reports Server (NTRS)

    Berkun, Andrew C.; Chu, Anhua J.

    2012-01-01

    All efforts to develop electronic equipment reach a stage where they need a board test station for each board. The SMAP digital system consists of three board types that interact with each other using interfaces with critical timing. Each board needs to be tested individually before combining into the integrated digital electronics system. Each board needs critical timing signals from the others to be able to operate. A bench test system was developed to support test of each board. The test system produces all the outputs of the control and timing unit, and is delivered much earlier than the timing unit. Timing signals are treated as data. A large file is generated containing the state of every timing signal at any instant. This file is streamed out to an IO card, which is wired directly to the device-under-test (DUT) input pins. This provides a flexible test environment that can be adapted to any of the boards required to test in a standalone configuration. The problem of generating the critical timing signals is then transferred from a hardware problem to a software problem where it is more easily dealt with.

  8. Crashes involving motorised rickshaws in urban India: Characteristics and injury patterns

    PubMed Central

    Schmucker, Uli; Dandona, Rakhi; Kumar, G. Anil; Dandona, Lalit

    2011-01-01

    Introduction Motorised three-wheeled vehicles (motorised rickshaw) are popular in Asian countries including India. This study aims to describe the crash characteristics and injury patterns for motorised rickshaw occupants and the road users hit-by-motorised rickshaw in urban India. Methods Consecutive cases of road traffic crashes involving motorised rickshaw, irrespective of injury severity, whether alive or dead, presenting to the emergency departments of two large government hospitals and three branches of a private hospital in Hyderabad city were recruited. Crash characteristics, details of injuries, injury severity parameters and outcome were documented in detailed interviews. Results A total of 139 (18%) of the 781 participants recruited were injured as a motorised rickshaw occupant (11%) or were hit by a motorised rickshaw (7%) in 114 crashes involving motorised rickshaw. Amongst motorised rickshaw occupants, single-vehicle collisions (54%) were more frequent than multi-vehicle collisions (46%), with overturning of motorised rickshaw in 73% of the single-vehicle collisions. Mortality (12%), the mean Injury Severity Score (5.8) and rate of multiple injured (60%) indicated a substantial trauma load. No significant differences in injury pattern were found between motorised rickshaw occupants and hit-by-motorised rickshaw subjects, with the pattern being similar to that of the pedestrians and two-wheeled vehicle users. With bivariate analysis for motorised rickshaw occupants, the risk of fatal outcome (odds ratio (OR) 2.60, 95% confidence interval (CI): 0.64–10.54), upper limb injury (OR 2.25, 95% CI: 0.94–5.37) and multiple injuries (OR 2.03, 95% CI 0.85–4.83) was high, although not statistically significant in multi-motorised-vehicle collisions as compared with the single-vehicle collisions or overturning. The risk of having multiple injuries (OR 4.55, 95% CI: 1.15–17.95) was significantly higher in motorised rickshaw occupants involved in front

  9. Perceptions of Father Involvement Patterns in Teenage-Mother Families: Predictors and Links to Mothers' Psychological Adjustment

    ERIC Educational Resources Information Center

    Kalil, Ariel; Ziol-Guest, Kathleen M.; Coley, Rebekah Levine

    2005-01-01

    Based on adolescent mothers' reports, longitudinal patterns of involvement of young, unmarried biological fathers (n=77) in teenage-mother families using cluster analytic techniques were examined. Approximately one third of fathers maintained high levels of involvement over time, another third demonstrated low involvement at both time points, and…

  10. Fruit shape diversity in the Brassicaceae is generated by varying patterns of anisotropy

    PubMed Central

    Eldridge, Tilly; Łangowski, Łukasz; Stacey, Nicola; Jantzen, Friederike; Moubayidin, Laila; Sicard, Adrien; Southam, Paul; Kennaway, Richard; Lenhard, Michael; Coen, Enrico S.

    2016-01-01

    Fruits exhibit a vast array of different 3D shapes, from simple spheres and cylinders to more complex curved forms; however, the mechanism by which growth is oriented and coordinated to generate this diversity of forms is unclear. Here, we compare the growth patterns and orientations for two very different fruit shapes in the Brassicaceae: the heart-shaped Capsella rubella silicle and the near-cylindrical Arabidopsis thaliana silique. We show, through a combination of clonal and morphological analyses, that the different shapes involve different patterns of anisotropic growth during three phases. These experimental data can be accounted for by a tissue-level model in which specified growth rates vary in space and time and are oriented by a proximodistal polarity field. The resulting tissue conflicts lead to deformation of the tissue as it grows. The model allows us to identify tissue-specific and temporally specific activities required to obtain the individual shapes. One such activity may be provided by the valve-identity gene FRUITFULL, which we show through comparative mutant analysis to modulate fruit shape during post-fertilisation growth of both species. Simple modulations of the model presented here can also broadly account for the variety of shapes in other Brassicaceae species, thus providing a simplified framework for fruit development and shape diversity. PMID:27624834

  11. Drosophila poised enhancers are generated during tissue patterning with the help of repression

    PubMed Central

    Koenecke, Nina; Johnston, Jeff; He, Qiye; Meier, Samuel; Zeitlinger, Julia

    2017-01-01

    Histone modifications are frequently used as markers for enhancer states, but how to interpret enhancer states in the context of embryonic development is not clear. The poised enhancer signature, involving H3K4me1 and low levels of H3K27ac, has been reported to mark inactive enhancers that are poised for future activation. However, future activation is not always observed, and alternative reasons for the widespread occurrence of this enhancer signature have not been investigated. By analyzing enhancers during dorsal-ventral (DV) axis formation in the Drosophila embryo, we find that the poised enhancer signature is specifically generated during patterning in the tissue where the enhancers are not induced, including at enhancers that are known to be repressed by a transcriptional repressor. These results suggest that, rather than serving exclusively as an intermediate step before future activation, the poised enhancer state may be a mark for spatial regulation during tissue patterning. We discuss the possibility that the poised enhancer state is more generally the result of repression by transcriptional repressors. PMID:27979994

  12. Eggs illusion: Local shape deformation generated by a grid pattern.

    PubMed

    Qian, Kun; Mitsudo, Hiroyuki

    2016-12-01

    In this study, we report a new visual shape illusion, the eggs illusion, in which circular disks located at the midpoints between adjacent grid intersections are perceived as being deformed to ellipses. In Experiment 1, we examined the eggs illusion by using a matching method and found that grid luminance and patch size play a critical role in producing the illusory deformation. In Experiment 2, we employed several types of elliptic or circular patches to examine the conditions in which the illusory deformation was cancelled or weakened. We observed that the illusory deformation was dependent on local grid orientation. Based on these results, we found several common features between the eggs illusion and the scintillating grid illusion. This resemblance suggests a possibility that similar mechanisms underlie the two phenomena. In addition to the scintillating grid illusion, we also considered several known perceptual phenomena that might be related to the eggs illusion, i.e., the apparent size illusion, the shape-contrast effect, and the Orbison illusion. Finally, we discuss the role of orientation processing in generating the eggs illusion.

  13. Evaluating the Evidence Surrounding Pontine Cholinergic Involvement in REM Sleep Generation

    PubMed Central

    Grace, Kevin P.; Horner, Richard L.

    2015-01-01

    Rapid eye movement (REM) sleep – characterized by vivid dreaming, motor paralysis, and heightened neural activity – is one of the fundamental states of the mammalian central nervous system. Initial theories of REM sleep generation posited that induction of the state required activation of the “pontine REM sleep generator” by cholinergic inputs. Here, we review and evaluate the evidence surrounding cholinergic involvement in REM sleep generation. We submit that: (i) the capacity of pontine cholinergic neurotransmission to generate REM sleep has been firmly established by gain-of-function experiments, (ii) the function of endogenous cholinergic input to REM sleep generating sites cannot be determined by gain-of-function experiments; rather, loss-of-function studies are required, (iii) loss-of-function studies show that endogenous cholinergic input to the PTF is not required for REM sleep generation, and (iv) cholinergic input to the pontine REM sleep generating sites serve an accessory role in REM sleep generation: reinforcing non-REM-to-REM sleep transitions making them quicker and less likely to fail. PMID:26388832

  14. Historical Identity Development Patterns and Contemporary Multicultural Identity in First, Second and Third Generation Counseling Students

    ERIC Educational Resources Information Center

    Byrd, Nola Butler

    2009-01-01

    This study examines the historical and contemporary identity development patterns of first, second, and third generation students to determine the attributes students bring with them and how they develop through their experiences in a multicultural counselor training program. The paper examines patterns between groups, followed by a discussion of…

  15. Central Pattern Generation and the Motor Infrastructure for Suck, Respiration, and Speech

    ERIC Educational Resources Information Center

    Barlow, Steven M.; Estep, Meredith

    2006-01-01

    The objective of the current report is to review experimental findings on centrally patterned movements and sensory and descending modulation of central pattern generators (CPGs) in a variety of animal and human models. Special emphasis is directed toward speech production muscle systems, including the chest wall and orofacial complex during…

  16. Generation of Customizable Micro-wavy Pattern through Grayscale Direct Image Lithography

    PubMed Central

    He, Ran; Wang, Shunqiang; Andrews, Geoffrey; Shi, Wentao; Liu, Yaling

    2016-01-01

    With the increasing amount of research work in surface studies, a more effective method of producing patterned microstructures is highly desired due to the geometric limitations and complex fabricating process of current techniques. This paper presents an efficient and cost-effective method to generate customizable micro-wavy pattern using direct image lithography. This method utilizes a grayscale Gaussian distribution effect to model inaccuracies inherent in the polymerization process, which are normally regarded as trivial matters or errors. The measured surface profiles and the mathematical prediction show a good agreement, demonstrating the ability of this method to generate wavy patterns with precisely controlled features. An accurate pattern can be generated with customizable parameters (wavelength, amplitude, wave shape, pattern profile, and overall dimension). This mask-free photolithography approach provides a rapid fabrication method that is capable of generating complex and non-uniform 3D wavy patterns with the wavelength ranging from 12 μm to 2100 μm and an amplitude-to-wavelength ratio as large as 300%. Microfluidic devices with pure wavy and wavy-herringbone patterns suitable for capture of circulating tumor cells are made as a demonstrative application. A completely customized microfluidic device with wavy patterns can be created within a few hours without access to clean room or commercial photolithography equipment. PMID:26902520

  17. Making a Swim Central Pattern Generator Out of Latent Parabolic Bursters

    NASA Astrophysics Data System (ADS)

    Alaçam, Deniz; Shilnikov, Andrey

    2015-06-01

    We study the rhythmogenesis of oscillatory patterns emerging in network motifs composed of inhibitory coupled tonic spiking neurons represented by the Plant model of R15 nerve cells. Such motifs are argued to be used as building blocks for a larger central pattern generator network controlling swim locomotion of sea slug Melibe leonina.

  18. From Central Pattern Generator to Sensory Template in the Evolution of Birdsong

    ERIC Educational Resources Information Center

    Konishi, Masakazu

    2010-01-01

    Central nervous networks, be they a part of the human brain or a group of neurons in a snail, may be designed to produce distinct patterns of movement. Central pattern generators can account for the development and production of normal vocal signals without auditory feedback in non-songbirds. Songbirds need auditory feedback to develop and…

  19. Generation of Customizable Micro-wavy Pattern through Grayscale Direct Image Lithography

    NASA Astrophysics Data System (ADS)

    He, Ran; Wang, Shunqiang; Andrews, Geoffrey; Shi, Wentao; Liu, Yaling

    2016-02-01

    With the increasing amount of research work in surface studies, a more effective method of producing patterned microstructures is highly desired due to the geometric limitations and complex fabricating process of current techniques. This paper presents an efficient and cost-effective method to generate customizable micro-wavy pattern using direct image lithography. This method utilizes a grayscale Gaussian distribution effect to model inaccuracies inherent in the polymerization process, which are normally regarded as trivial matters or errors. The measured surface profiles and the mathematical prediction show a good agreement, demonstrating the ability of this method to generate wavy patterns with precisely controlled features. An accurate pattern can be generated with customizable parameters (wavelength, amplitude, wave shape, pattern profile, and overall dimension). This mask-free photolithography approach provides a rapid fabrication method that is capable of generating complex and non-uniform 3D wavy patterns with the wavelength ranging from 12 μm to 2100 μm and an amplitude-to-wavelength ratio as large as 300%. Microfluidic devices with pure wavy and wavy-herringbone patterns suitable for capture of circulating tumor cells are made as a demonstrative application. A completely customized microfluidic device with wavy patterns can be created within a few hours without access to clean room or commercial photolithography equipment.

  20. Dynamic contrast enhancement in widefield microscopy using projector-generated illumination patterns

    NASA Astrophysics Data System (ADS)

    Carlo Samson, Edward; Mar Blanca, Carlo

    2007-10-01

    We present a simple and cost-effective optical protocol to realize contrast-enhancement imaging (such as dark-field, optical-staining and oblique illumination microscopy) of transparent samples on a conventional widefield microscope using commercial multimedia projectors. The projector functions as both light source and mask generator implemented by creating slideshows of the filters projected along the illumination planes of the microscope. The projected optical masks spatially modulate the distribution of the incident light to selectively enhance structures within the sample according to spatial frequency thereby increasing the image contrast of translucent biological specimens. Any amplitude filter can be customized and dynamically controlled so that switching from one imaging modality to another involves a simple slide transition and can be executed at a keystroke with no physical filters and no moving optical parts. The method yields an image contrast of 89 96% comparable with standard enhancement techniques. The polarization properties of the projector are then utilized to discriminate birefringent and non-birefringent sites on the sample using single-shot, simultaneous polarization and optical-staining microscopy. In addition to dynamic pattern generation and polarization, the projector also provides high illumination power and spectral excitation selectivity through its red-green-blue (RGB) channels. We exploit this last property to explore the feasibility of using video projectors to selectively excite stained samples and perform fluorescence imaging in tandem with reflectance and polarization reflectance microscopy.

  1. Beyond participation: the association between school extracurricular activities and involvement in violence across generations of immigration.

    PubMed

    Jiang, Xin; Peterson, Ruth D

    2012-03-01

    Participation in extracurricular activities is purported to protect the broad spectrum of youth from a host of behavioral risks. Yet, empirical research on the extent to which this assumption holds for involvement in violence by immigrant youth is limited. Thus, using data for 13,236 (51.8% female) adolescents from the National Longitudinal Study of Adolescent Health, this study explores how the relationship between extracurricular activities and youth violence varies by type of extracurricular activity profile (sports alone, non-sports alone, and a combination of sports and non-sports) and by generations of immigration (first, second, and third-plus). The sample is composed of 9.3% (n = 1,233) first-generation youth, 15.7% (n = 2,080) second generation, and 74.9% (n = 9,923) third-plus generation. The results reveal that adolescents from the third-plus generation (i.e., non-immigrant youth) who participate in non-sports alone or sports plus non-sports have lower odds of involvement in violence than adolescents from the same generation who do not participate in extracurricular activities. However, for first- and second-generation adolescents, participation in extracurricular activities is associated with higher rather than lower odds of violence compared to their non-participating counterparts. These findings challenge the viewpoint that participation in mainstream extracurricular activities as afforded by US schools is equally beneficial for all youth. They also call for additional research that explores why immigrant youth are less likely than non-immigrant youth to gain violence-reducing benefits when they participate in extracurricular activities.

  2. Optimum projection pattern generation for grey-level coded structured light illumination systems

    NASA Astrophysics Data System (ADS)

    Porras-Aguilar, Rosario; Falaggis, Konstantinos; Ramos-Garcia, Ruben

    2017-04-01

    Structured light illumination (SLI) systems are well-established optical inspection techniques for noncontact 3D surface measurements. A common technique is multi-frequency sinusoidal SLI that obtains the phase map at various fringe periods in order to estimate the absolute phase, and hence, the 3D surface information. Nevertheless, multi-frequency SLI systems employ multiple measurement planes (e.g. four phase shifted frames) to obtain the phase at a given fringe period. It is therefore an age old challenge to obtain the absolute surface information using fewer measurement frames. Grey level (GL) coding techniques have been developed as an attempt to reduce the number of planes needed, because a spatio-temporal GL sequence employing p discrete grey-levels and m frames has the potential to unwrap up to pm fringes. Nevertheless, one major disadvantage of GL based SLI techniques is that there are often errors near the border of each stripe, because an ideal stepwise intensity change cannot be measured. If the step-change in intensity is a single discrete grey-level unit, this problem can usually be overcome by applying an appropriate threshold. However, severe errors occur if the intensity change at the border of the stripe exceeds several discrete grey-level units. In this work, an optimum GL based technique is presented that generates a series of projection patterns with a minimal gradient in the intensity. It is shown that when using this technique, the errors near the border of the stripes can be significantly reduced. This improvement is achieved with the choice generated patterns, and does not involve additional hardware or special post-processing techniques. The performance of that method is validated using both simulations and experiments. The reported technique is generic, works with an arbitrary number of frames, and can employ an arbitrary number of grey-levels.

  3. Differences in Parental Involvement Typologies among Baby Boomers, Generation X, and Generation Y Parents: A Study of Select Bay Area Region of Houston Elementary Schools

    ERIC Educational Resources Information Center

    Veloz, Elizabeth Andrea

    2010-01-01

    The purpose of this study was to determine whether differences existed among generations (Baby Boomers, Generation X, and Generation Y) regarding the levels of parental involvement within each of these generations. Also examined were additional factors such as the parents. socioeconomic status, educational level, marital status, and ethnicity. The…

  4. Proposed Tenaska Washington II Generation Project : Final Environmental Impact Statement. Volume 2: Public Involvement.

    SciTech Connect

    United States. Bonneville Power Administration.

    1994-01-01

    In regard to the proposed Tenaska Washington II Generation Project, the goal of the Bonneville Power Administration`s (BPA) Environmental Impact Statement (EIS) public involvement process is to determine the issues to be examined and pertinent analyses to be conducted and to solicit comments on the content and quality of information presented in the Draft Environmental Impact Statement (DEIS). Comments and questions are solicited from the public and government agencies during the scoping process and during the comment period and public hearing on the DEIS, to find out what is of most concern to them. The end product of the public involvement process is the Comment Report which follows in part of this volume on Public Involvement.

  5. Effects of Differences in Working Memory Capacity on Patterns of Word Generation

    ERIC Educational Resources Information Center

    Kawamura, Mimpei; Kobayashi, Yasutaka; Morioka, Shu

    2012-01-01

    In recent years, it has been reported that WM (working memory) is concerned with word generation, but many points regarding the relationship between the individual differences of WM capacity and the patterns of word generation remain unclear. This study is to investigate these unclear points by using three types of word fluency task with different…

  6. Fatty acid transport and activation and the expression patterns of genes involved in fatty acid trafficking.

    PubMed

    Sandoval, Angel; Fraisl, Peter; Arias-Barrau, Elsa; Dirusso, Concetta C; Singer, Diane; Sealls, Whitney; Black, Paul N

    2008-09-15

    These studies defined the expression patterns of genes involved in fatty acid transport, activation and trafficking using quantitative PCR (qPCR) and established the kinetic constants of fatty acid transport in an effort to define whether vectorial acylation represents a common mechanism in different cell types (3T3-L1 fibroblasts and adipocytes, Caco-2 and HepG2 cells and three endothelial cell lines (b-END3, HAEC, and HMEC)). As expected, fatty acid transport protein (FATP)1 and long-chain acyl CoA synthetase (Acsl)1 were the predominant isoforms expressed in adipocytes consistent with their roles in the transport and activation of exogenous fatty acids destined for storage in the form of triglycerides. In cells involved in fatty acid processing including Caco-2 (intestinal-like) and HepG2 (liver-like), FATP2 was the predominant isoform. The patterns of Acsl expression were distinct between these two cell types with Acsl3 and Acsl5 being predominant in Caco-2 cells and Acsl4 in HepG2 cells. In the endothelial lines, FATP1 and FATP4 were the most highly expressed isoforms; the expression patterns for the different Acsl isoforms were highly variable between the different endothelial cell lines. The transport of the fluorescent long-chain fatty acid C(1)-BODIPY-C(12) in 3T3-L1 fibroblasts and 3T3-L1 adipocytes followed typical Michaelis-Menten kinetics; the apparent efficiency (k(cat)/K(T)) of this process increases over 2-fold (2.1 x 10(6)-4.5 x 10(6)s(-1)M(-1)) upon adipocyte differentiation. The V(max) values for fatty acid transport in Caco-2 and HepG2 cells were essentially the same, yet the efficiency was 55% higher in Caco-2 cells (2.3 x 10(6)s(-1)M(-1) versus 1.5 x 10(6)s(-1)M(-1)). The kinetic parameters for fatty acid transport in three endothelial cell types demonstrated they were the least efficient cell types for this process giving V(max) values that were nearly 4-fold lower than those defined form 3T3-L1 adipocytes, Caco-2 cells and HepG2 cells. The

  7. Expression pattern of glycoside hydrolase genes in Lutzomyia longipalpis reveals key enzymes involved in larval digestion

    PubMed Central

    Moraes, Caroline da Silva; Diaz-Albiter, Hector M.; Faria, Maiara do Valle; Sant'Anna, Maurício R. V.; Dillon, Rod J.; Genta, Fernando A.

    2014-01-01

    The sand fly Lutzomyia longipalpis is the most important vector of American Visceral Leishmaniasis. Adults are phytophagous (males and females) or blood feeders (females only), and larvae feed on solid detritus. Digestion in sand fly larvae has scarcely been studied, but some glycosidase activities putatively involved in microorganism digestion were already described. Nevertheless, the molecular nature of these enzymes, as the corresponding genes and transcripts, were not explored yet. Catabolism of microbial carbohydrates in insects generally involves β-1,3-glucanases, chitinases, and digestive lysozymes. In this work, the transcripts of digestive β-1,3-glucanase and chitinases were identified in the L. longipalpis larvae throughout analysis of sequences and expression patterns of glycoside hydrolases families 16, 18, and 22. The activity of one i-type lysozyme was also registered. Interestingly, this lysozyme seems to play a role in immunity, rather than digestion. This is the first attempt to identify the molecular nature of sand fly larval digestive enzymes. PMID:25140153

  8. One-eighth look-up table method for effectively generating computer-generated hologram patterns

    NASA Astrophysics Data System (ADS)

    Cho, Sungjin; Ju, Byeong-Kwon; Kim, Nam-Young; Park, Min-Chul

    2014-05-01

    To generate ideal digital holograms, a computer-generated hologram (CGH) has been regarded as a solution. However, it has an unavoidable problem in that the computational burden for generating CGH is very large. Recently, many studies have been conducted to investigate different solutions in order to reduce the computational complexity of CGH by using particular methods such as look-up tables (LUTs) and parallel processing. Each method has a positive effectiveness about reducing computational time for generating CGH. However, it appears to be difficult to apply both methods simultaneously because of heavy memory consumption of the LUT technique. Therefore, we proposed a one-eighth LUT method where the memory usage of the LUT is reduced, making it possible to simultaneously apply both of the fast computing methods for the computation of CGH. With the one-eighth LUT method, only one-eighth of the zone plates were stored in the LUT. All of the zone plates were accessed by indexing method. Through this method, we significantly reduced memory usage of LUT. Also, we confirmed the feasibility of reducing the computational time of the CGH by using general-purpose graphic processing units while reducing the memory usage.

  9. Microbial communities involved in electricity generation from sulfide oxidation in a microbial fuel cell.

    PubMed

    Sun, Min; Tong, Zhong-Hua; Sheng, Guo-Ping; Chen, Yong-Zhen; Zhang, Feng; Mu, Zhe-Xuan; Wang, Hua-Lin; Zeng, Raymond J; Liu, Xian-Wei; Yu, Han-Qing; Wei, Li; Ma, Fang

    2010-10-15

    Simultaneous electricity generation and sulfide removal can be achieved in a microbial fuel cell (MFC). In electricity harvesting from sulfide oxidation in such an MFC, various microbial communities are involved. It is essential to elucidate the microbial communities and their roles in the sulfide conversion and electricity generation. In this work, an MFC was constructed to enrich a microbial consortium, which could harvest electricity from sulfide oxidation. Electrochemical analysis demonstrated that microbial catalysis was involved in electricity output in the sulfide-fed MFC. The anode-attached and planktonic communities could perform catalysis independently, and synergistic interactions occurred when the two communities worked together. A 16S rRNA clone library analysis was employed to characterize the microbial communities in the MFC. The anode-attached and planktonic communities shared similar richness and diversity, while the LIBSHUFF analysis revealed that the two community structures were significantly different. The exoelectrogenic, sulfur-oxidizing and sulfate-reducing bacteria were found in the MFC anodic chamber. The discovery of these bacteria was consistent with the community characteristics for electricity generation from sulfide oxidation. The exoelectrogenic bacteria were found both on the anode and in the solution. The sulfur-oxidizing bacteria were present in greater abundance on the anode than in the solution, while the sulfate-reducing bacteria preferably lived in the solution.

  10. Motor Neurons Tune Premotor Activity in a Vertebrate Central Pattern Generator.

    PubMed

    Lawton, Kristy J; Perry, Wick M; Yamaguchi, Ayako; Zornik, Erik

    2017-03-22

    Central patterns generators (CPGs) are neural circuits that drive rhythmic motor output without sensory feedback. Vertebrate CPGs are generally believed to operate in a top-down manner in which premotor interneurons activate motor neurons that in turn drive muscles. In contrast, the frog (Xenopus laevis) vocal CPG contains a functionally unexplored neuronal projection from the motor nucleus to the premotor nucleus, indicating a recurrent pathway that may contribute to rhythm generation. In this study, we characterized the function of this bottom-up connection. The X. laevis vocal CPG produces a 50-60 Hz "fast trill" song used by males during courtship. We recorded "fictive vocalizations" in the in vitro CPG from the laryngeal nerve while simultaneously recording premotor activity at the population and single-cell level. We show that transecting the motor-to-premotor projection eliminated the characteristic firing rate of premotor neurons. Silencing motor neurons with the intracellular sodium channel blocker QX-314 also disrupted premotor rhythms, as did blockade of nicotinic synapses in the motor nucleus (the putative location of motor neuron-to-interneuron connections). Electrically stimulating the laryngeal nerve elicited primarily IPSPs in premotor neurons that could be blocked by a nicotinic receptor antagonist. Our results indicate that an inhibitory signal, activated by motor neurons, is required for proper CPG function. To our knowledge, these findings represent the first example of a CPG in which precise premotor rhythms are tuned by motor neuron activity.SIGNIFICANCE STATEMENT Central pattern generators (CPGs) are neural circuits that produce rhythmic behaviors. In vertebrates, motor neurons are not commonly known to contribute to CPG function, with the exception of a few spinal circuits where the functional significance of motor neuron feedback is still poorly understood. The frog hindbrain vocal circuit contains a previously unexplored connection from

  11. Pigment cell movement is not required for generation of Turing patterns in zebrafish skin

    PubMed Central

    Bullara, D.; De Decker, Y.

    2015-01-01

    The zebrafish is a model organism for pattern formation in vertebrates. Understanding what drives the formation of its coloured skin motifs could reveal pivotal to comprehend the mechanisms behind morphogenesis. The motifs look and behave like reaction–diffusion Turing patterns, but the nature of the underlying physico-chemical processes is very different, and the origin of the patterns is still unclear. Here we propose a minimal model for such pattern formation based on a regulatory mechanism deduced from experimental observations. This model is able to produce patterns with intrinsic wavelength, closely resembling the experimental ones. We mathematically prove that their origin is a Turing bifurcation occurring despite the absence of cell motion, through an effect that we call differential growth. This mechanism is qualitatively different from the reaction–diffusion originally proposed by Turing, although they both generate the short-range activation and the long-range inhibition required to form Turing patterns. PMID:25959141

  12. Pigment cell movement is not required for generation of Turing patterns in zebrafish skin

    NASA Astrophysics Data System (ADS)

    Bullara, D.; de Decker, Y.

    2015-05-01

    The zebrafish is a model organism for pattern formation in vertebrates. Understanding what drives the formation of its coloured skin motifs could reveal pivotal to comprehend the mechanisms behind morphogenesis. The motifs look and behave like reaction-diffusion Turing patterns, but the nature of the underlying physico-chemical processes is very different, and the origin of the patterns is still unclear. Here we propose a minimal model for such pattern formation based on a regulatory mechanism deduced from experimental observations. This model is able to produce patterns with intrinsic wavelength, closely resembling the experimental ones. We mathematically prove that their origin is a Turing bifurcation occurring despite the absence of cell motion, through an effect that we call differential growth. This mechanism is qualitatively different from the reaction-diffusion originally proposed by Turing, although they both generate the short-range activation and the long-range inhibition required to form Turing patterns.

  13. Gap junctions are involved in the early generation of left-right asymmetry.

    PubMed

    Levin, M; Mercola, M

    1998-11-01

    Invariant left-right asymmetry of the visceral organs is a fundamental feature of vertebrate embryogenesis. While a cascade of asymmetrically expressed genes has been described, the embryonic mechanism that orients the left-right axis relative to the dorsoventral and anteroposterior axes (a prerequisite for asymmetric gene expression) is unknown. We propose that this process involves dorsoventral differences in cell-cell communication through gap junctions composed of connexin proteins. Global modulation of gap junctional states in Xenopus embryos by pharmacological agents specifically induced heterotaxia involving mirror-image reversals of heart, gut, and gall bladder. Greatest sensitivity was observed between st. 5 and st. 12, well before the onset of organogenesis. Moreover, heterotaxia was also induced following microinjection of dominant negative and wild-type connexin mRNAs to modify the endogenous dorsoventral difference in junctional communication. Heterotaxia was induced by either blocking gap junction communication (GJC) dorsally or by introducing communication ventrally (but not the reverse). Both connexin misexpression and exposure to GJC-modifying drugs altered expression of the normally left-sided gene XNR-1, demonstrating that GJC functions upstream of XNR-1 in the pathway that patterns left-right asymmetry. Finally, lineage analysis to follow the progeny of microinjected cells indicated that they generally do not contribute the asymmetric organs. Together with the early sensitivity window, this suggests that GJC functions as part of a fundamental, early aspect of left-right patterning. In addition, we show that a potential regulatory mutation in Connexin43 is sufficient to cause heterotaxia. Despite uncertainty about the prevalence of the serine364 to proline substitution reported in human patients with laterality defects, the mutant protein is both a mild hypomorph and a potent antimorph as determined by the effect of its expression on left

  14. Generative Models of Segregation: Investigating Model-Generated Patterns of Residential Segregation by Ethnicity and Socioeconomic Status

    PubMed Central

    Fossett, Mark

    2011-01-01

    This paper considers the potential for using agent models to explore theories of residential segregation in urban areas. Results of generative experiments conducted using an agent-based simulation of segregation dynamics document that varying a small number of model parameters representing constructs from urban-ecological theories of segregation can generate a wide range of qualitatively distinct and substantively interesting segregation patterns. The results suggest how complex, macro-level patterns of residential segregation can arise from a small set of simple micro-level social dynamics operating within particular urban-demographic contexts. The promise and current limitations of agent simulation studies are noted and optimism is expressed regarding the potential for such studies to engage and contribute to the broader research literature on residential segregation. PMID:21379372

  15. Fungicidal effect of thymoquinone involves generation of oxidative stress in Candida glabrata.

    PubMed

    Almshawit, Hala; Macreadie, Ian

    2017-01-01

    The antifungal effect of thymoquinone, a component of black seed essential oil, has been studied on different types of fungi. Its mechanism of action as an antifungal has not been described yet. This study demonstrates the fungicidal effect of thymoquinone on different Candida species with particular emphasis on C. glabrata planktonic cells and biofilms. Since cell death was induced via the generation of oxidative stress as evidenced by the abrogation of thymoquinone toxicity in cells incubated with antioxidants, a part of thymoquinone's mechanism of action includes a direct involvement as a pro-oxidant. This was further confirmed by measuring the generation of reactive oxygen species, glutathione level reduction and decrease in mitochondrial membrane potential. The oxidative stress caused by thymoquinone was confirmed to be the cause of death and not a result of cell death.

  16. Cortical regions involved in the generation of musical structures during improvisation in pianists.

    PubMed

    Bengtsson, Sara L; Csíkszentmihályi, Mihály; Ullén, Fredrik

    2007-05-01

    Studies on simple pseudorandom motor and cognitive tasks have shown that the dorsolateral prefrontal cortex and rostral premotor areas are involved in free response selection. We used functional magnetic resonance imaging to investigate whether these brain regions are also involved in free generation of responses in a more complex creative behavior: musical improvisation. Eleven professional pianists participated in the study. In one condition, Improvise, the pianist improvised on the basis of a visually displayed melody. In the control condition, Reproduce, the participant reproduced his previous improvisation from memory. Participants were able to reproduce their improvisations with a high level of accuracy, and the contrast Improvise versus Reproduce was thus essentially matched in terms of motor output and sensory feedback. However, the Improvise condition required storage in memory of the improvisation. We therefore also included a condition FreeImp, where the pianist improvised but was instructed not to memorize his performance. To locate brain regions involved in musical creation, we investigated the activations in the Improvise-Reproduce contrast that were also present in FreeImp contrasted with a baseline rest condition. Activated brain regions included the right dorsolateral prefrontal cortex, the presupplementary motor area, the rostral portion of the dorsal premotor cortex, and the left posterior part of the superior temporal gyrus. We suggest that these regions are part of a network involved in musical creation, and discuss their possible functional roles.

  17. Genes and mechanisms involved in beta-amyloid generation and Alzheimer's disease.

    PubMed

    Steiner, H; Capell, A; Leimer, U; Haass, C

    1999-01-01

    Alzheimer's disease is characterized by the invariable accumulation of senile plaques that are predominantly composed of amyloid beta-peptide (Abeta). Abeta is generated by proteolytic processing of the beta-amyloid precursor protein (betaAPP) involving the combined action of beta- and gamma-secretase. Cleavage within the Abeta domain by alpha-secretase prevents Abeta generation. In some very rare cases of familial AD (FAD), mutations have been identified within the betaAPP gene. These mutations are located close to or at the cleavage sites of the secretases and pathologically effect betaAPP processing by increasing Abeta production, specifically its highly amyloidogenic 42 amino acid variant (Abeta42). Most of the mutations associated with FAD have been identified in the two presenilin (PS) genes, particularly the PS1 gene. Like the mutations identified within the betaAPP gene, mutations in PS1 and PS2 cause the increased generation of Abeta42. PS1 has been shown to be functionally involved in Notch signaling, a key process in cellular differentation, and in betaAPP processing. A gene knock out of PS1 in mice leads to an embryonic lethal phenotype similar to that of mice lacking Notch. In addition, absence of PS1 results in reduced gamma-secretase cleavage and leads to an accumulation of betaAPP C-terminal fragments and decreased amounts of Abeta. Recent work may suggest that PS1 could be the gamma-secretase itself, exhibiting the properties of a novel aspartyl protease. Mutagenesis of either of two highly conserved intramembraneous aspartate residues of PS1 leads to reduced Abeta production as observed in the PS1 knockout. A corresponding mutation in PS2 interfered with betaAPP processing and Notch signaling suggesting a functional redundancy of both presenilins. In this issue, some of the recent work on the molecular mechanisms involved in Alzheimer's disease (AD) as well as novel diagnostic approaches and risk factors for AD will be discussed. In the first

  18. Experimental verification of multilevel spatial pattern generation from binary data page with four-step phase pattern (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Barada, Daisuke; Yatagai, Toyohiko

    2016-09-01

    Holographic memory is expected for cold storage because of the features of huge data capacity, high data transfer rate, and long life time. In holographic memory, a signal beam is modulated by a spatial light modulator according to data pages. The recording density is dependent on information amount per pixel in a data page. However, a binary spatial light modulator is used to realize high data transfer rate in general. In our previous study, an optical conversion method from binary data to multilevel data has been proposed. In this paper, the principle of the method is experimentally verified. In the proposed method, a data page consists of symbols with 2x2 pixels and a four-step phase mask is used. Then, the complex amplitudes of four pixels in a symbol become positive real, positive imaginary, negative real, and negative imaginary values, respectively. A square pixel pattern is spread by spatial frequency filtering with a square aperture in a Fourier plane. When the aperture size is too small, the complex amplitude of four pixels in a symbol is superposed and a symbol is regarded as a pixel with a complex number. In this work, a data page pattern with a four-step phase pattern was generated by using a computer-generated circular polarization hologram (CGCPH). The CGCPH was prepared by electron beam lithography. The page data pattern is Fourier transformed by a lens and spatially filtered by a variable rectangular aperture. The complex amplitude of the spatial filtered data page pattern was measured by digital holography and the principle was experimentally verified.

  19. High-fidelity spherical cholesteric liquid crystal Bragg reflectors generating unclonable patterns for secure authentication

    PubMed Central

    Geng, Yong; Noh, JungHyun; Drevensek-Olenik, Irena; Rupp, Romano; Lenzini, Gabriele; Lagerwall, Jan P. F.

    2016-01-01

    Monodisperse cholesteric liquid crystal microspheres exhibit spherically symmetric Bragg reflection, generating, via photonic cross communication, dynamically tuneable multi-coloured patterns. These patterns, uniquely defined by the particular sphere arrangement, could render cholesteric microspheres very useful in countless security applications, as tags to identify and authenticate their carriers, mainly physical objects or persons. However, the optical quality of the cholesteric droplets studied so far is unsatisfactory, especially after polymerisation, a step required for obtaining durable samples that can be used for object identification. We show that a transition from droplets to shells solves all key problems, giving rise to sharp patterns and excellent optical quality even after polymerisation, the polymerised shells sustaining considerable mechanical deformation. Moreover, we demonstrate that, counter to prior expectation, cross communication takes place even between non-identical shells. This opens additional communication channels that add significantly to the complexity and unique character of the generated patterns. PMID:27230944

  20. High-fidelity spherical cholesteric liquid crystal Bragg reflectors generating unclonable patterns for secure authentication

    NASA Astrophysics Data System (ADS)

    Geng, Yong; Noh, Junghyun; Drevensek-Olenik, Irena; Rupp, Romano; Lenzini, Gabriele; Lagerwall, Jan P. F.

    2016-05-01

    Monodisperse cholesteric liquid crystal microspheres exhibit spherically symmetric Bragg reflection, generating, via photonic cross communication, dynamically tuneable multi-coloured patterns. These patterns, uniquely defined by the particular sphere arrangement, could render cholesteric microspheres very useful in countless security applications, as tags to identify and authenticate their carriers, mainly physical objects or persons. However, the optical quality of the cholesteric droplets studied so far is unsatisfactory, especially after polymerisation, a step required for obtaining durable samples that can be used for object identification. We show that a transition from droplets to shells solves all key problems, giving rise to sharp patterns and excellent optical quality even after polymerisation, the polymerised shells sustaining considerable mechanical deformation. Moreover, we demonstrate that, counter to prior expectation, cross communication takes place even between non-identical shells. This opens additional communication channels that add significantly to the complexity and unique character of the generated patterns.

  1. Pattern and outcome of vascular involvement of Omani patients with Behcet's disease.

    PubMed

    Alkaabi, Juma K; Pathare, Anil

    2011-06-01

    The objective of the study is to study the pattern, frequency and outcome of vascular events in Omani patients with Behcet's disease (BD). Forty BD patients were recruited. Clinical data parameters were recorded, including age at onset, disease duration, current disease activity, and the vascular manifestations of the disease (current and past events). Disease activity was assessed by ESR, CRP and also clinically. For venous and arterial thrombotic events, imaging studies, such as Doppler ultrasonography, angiography, MRI, CT, and echocardiography were performed. Nine patients had vascular events (23%). The mean age of these patients at diagnosis of the vascular event was 24 years (range 15-37) and the mean disease duration at onset of the vascular event was 3.8 years (range 3-5); this was significant when compared with patients without thrombosis (P=0.001, Mann-Whitney test). In these patients with vascular involvement, two patients (22%) had venous lesions, three (33%) patients had arterial lesions and four patients (44%) had mixed lesions. Two patients (22%) had pulmonary artery aneurysm (PAA) and concomitant intracardiac thrombus, and further one patient also had PAA. Immunosuppressive therapy resulted in the resolution of PAA and intracardiac thrombous. In conclusion, the frequency of vascular complications of BD in our patients is similar to those reported around the world. We found younger male patients with short disease duration are at a greater risk of developing thrombosis. Medical treatment with immunosuppressive therapy without anticoagulation seems successful in treating PAA and intracardiac thrombus.

  2. Chronic recurrent multifocal osteomyelitis: typical patterns of bone involvement in whole-body bone scintigraphy.

    PubMed

    Acikgoz, Gunsel; Averill, Lauren W

    2014-08-01

    Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disease of unknown etiology. It affects children and adolescents predominantly and occurs mostly in the female population. It is characterized by the insidious onset of pain and swelling, with a fluctuating clinical course of relapses and remissions. Typically, several bones are affected, either synchronously or metachronously, and bilateral involvement is common. CRMO most commonly affects the metaphysis of long bones, especially the tibia, femur, and clavicle. The spine, pelvis, ribs, sternum, and mandible may also be affected. Although lesions are mostly multiple, patients may present with a single symptomatic focus. Radiographic findings may be negative early in the course of the disease. Bone scintigraphy is useful in determining the presence of abnormality and the extent of disease. The imaging and clinical features of CRMO overlap with those of infectious osteomyelitis, bone malignancy, and inflammatory arthritis. Nonetheless, CRMO can be confidently diagnosed with the recognition of typical imaging patterns in the appropriate clinical setting. This article reviews imaging findings with special emphasis on bone scintigraphy and specific disease sites.

  3. Localization of Motor Neurons and Central Pattern Generators for Motor Patterns Underlying Feeding Behavior in Drosophila Larvae

    PubMed Central

    Hückesfeld, Sebastian; Schoofs, Andreas; Schlegel, Philipp; Miroschnikow, Anton; Pankratz, Michael J.

    2015-01-01

    Motor systems can be functionally organized into effector organs (muscles and glands), the motor neurons, central pattern generators (CPG) and higher control centers of the brain. Using genetic and electrophysiological methods, we have begun to deconstruct the motor system driving Drosophila larval feeding behavior into its component parts. In this paper, we identify distinct clusters of motor neurons that execute head tilting, mouth hook movements, and pharyngeal pumping during larval feeding. This basic anatomical scaffold enabled the use of calcium-imaging to monitor the neural activity of motor neurons within the central nervous system (CNS) that drive food intake. Simultaneous nerve- and muscle-recordings demonstrate that the motor neurons innervate the cibarial dilator musculature (CDM) ipsi- and contra-laterally. By classical lesion experiments we localize a set of CPGs generating the neuronal pattern underlying feeding movements to the subesophageal zone (SEZ). Lesioning of higher brain centers decelerated all feeding-related motor patterns, whereas lesioning of ventral nerve cord (VNC) only affected the motor rhythm underlying pharyngeal pumping. These findings provide a basis for progressing upstream of the motor neurons to identify higher regulatory components of the feeding motor system. PMID:26252658

  4. Localization of Motor Neurons and Central Pattern Generators for Motor Patterns Underlying Feeding Behavior in Drosophila Larvae.

    PubMed

    Hückesfeld, Sebastian; Schoofs, Andreas; Schlegel, Philipp; Miroschnikow, Anton; Pankratz, Michael J

    2015-01-01

    Motor systems can be functionally organized into effector organs (muscles and glands), the motor neurons, central pattern generators (CPG) and higher control centers of the brain. Using genetic and electrophysiological methods, we have begun to deconstruct the motor system driving Drosophila larval feeding behavior into its component parts. In this paper, we identify distinct clusters of motor neurons that execute head tilting, mouth hook movements, and pharyngeal pumping during larval feeding. This basic anatomical scaffold enabled the use of calcium-imaging to monitor the neural activity of motor neurons within the central nervous system (CNS) that drive food intake. Simultaneous nerve- and muscle-recordings demonstrate that the motor neurons innervate the cibarial dilator musculature (CDM) ipsi- and contra-laterally. By classical lesion experiments we localize a set of CPGs generating the neuronal pattern underlying feeding movements to the subesophageal zone (SEZ). Lesioning of higher brain centers decelerated all feeding-related motor patterns, whereas lesioning of ventral nerve cord (VNC) only affected the motor rhythm underlying pharyngeal pumping. These findings provide a basis for progressing upstream of the motor neurons to identify higher regulatory components of the feeding motor system.

  5. Characterization of sacral interneurons that mediate activation of locomotor pattern generators by sacrocaudal afferent input.

    PubMed

    Etlin, Alex; Finkel, Eran; Mor, Yoav; O'Donovan, Michael J; Anglister, Lili; Lev-Tov, Aharon

    2013-01-09

    Identification of the neural pathways involved in retraining the spinal central pattern generators (CPGs) by afferent input in the absence of descending supraspinal control is feasible in isolated rodent spinal cords where the locomotor CPGs are potently activated by sacrocaudal afferent (SCA) input. Here we study the involvement of sacral neurons projecting rostrally through the ventral funiculi (VF) in activation of the CPGs by sensory stimulation. Fluorescent labeling and immunostaining showed that VF neurons are innervated by primary afferents immunoreactive for vesicular glutamate transporters 1 and 2 and by intraspinal neurons. Calcium imaging revealed that 55% of the VF neurons were activated by SCA stimulation. The activity of VF neurons and the sacral and lumbar CPGs was abolished when non-NMDA receptors in the sacral segments were blocked by the antagonist CNQX. When sacral NMDA receptors were blocked by APV, the sacral CPGs were suppressed, VF neurons with nonrhythmic activity were recruited and a moderate-drive locomotor rhythm developed during SCA stimulation. In contrast, when the sacral CPGs were activated by SCA stimulation, rhythmic and nonrhythmic VF neurons were recruited and the locomotor rhythm was most powerful. The activity of 73 and 27% of the rhythmic VF neurons was in-phase with the ipsilateral and contralateral motor output, respectively. Collectively, our studies indicate that sacral VF neurons serve as a major link between SCA and the hindlimb CPGs and that the ability of SCA to induce stepping can be enhanced by the sacral CPGs. The nature of the ascending drive to lumbar CPGs, the identity of subpopulations of VF neurons, and their potential role in activating the locomotor rhythm are discussed.

  6. Intelligent fuzzy-neural pattern generation and control of a quadrupedal bionic inspection robot

    NASA Astrophysics Data System (ADS)

    Sayfeddine, D.; Bulgakov, A. G.

    2017-02-01

    This paper represents a case study on ‘single leg single step’ pattern generation and control of quadrupedal bionic robot movement using intelligent fuzzy-neural approaches. The aim is to set up a flip-flop mechanical configuration allowing the robot to move one step forward. The same algorithm can be integrated to develop a full trajectory pattern as an interconnected task of global path planning for autonomous quadrupedal robots.

  7. Second harmonic generation in a low-loss orientation-patterned GaAs waveguide.

    PubMed

    Fedorova, K A; McRobbie, A D; Sokolovskii, G S; Schunemann, P G; Rafailov, E U

    2013-07-15

    The technology of low-loss orientation-patterned gallium arsenide (OP-GaAs) waveguided crystals was developed and realized by reduction of diffraction scattering on the waveguide pattern. The propagation losses in the OP-GaAs waveguide were estimated to be as low as 2.1 dB/cm, thus demonstrating the efficient second harmonic generation at 1621 nm under an external pumping.

  8. Inspiring the Next Generation of Explorers: Scientist Involvement in the Expedition Earth and Beyond Program

    NASA Technical Reports Server (NTRS)

    Graff, Paige; Stefanov, William; Willis, Kim; Runco, Susan

    2012-01-01

    Scientists, science experts, graduate and even undergraduate student researchers have a unique ability to inspire the next generation of explorers. These science, technology, engineering, and mathematics (STEM) experts can serve as role models for students and can help inspire them to consider future STEM-related careers. They have an exceptional ability to instill a sense of curiosity and fascination in the minds of students as they bring science to life in the classroom. Students and teachers are hungry for opportunities to interact with scientists. They feel honored when these experts take time out of their busy day to share their science, their expertise, and their stories. The key for teachers is to be cognizant of opportunities to connect their students with scientists. For scientists, the key is to know how to get involved, to have options for participation that involve different levels of commitment, and to work with educational specialists who can help facilitate their involvement. The Expedition Earth and Beyond (EEAB) Program, facilitated by the Astromaterials Research and Exploration Science (ARES) Directorate at the NASA Johnson Space Center, is an Earth and planetary science education program designed to inspire, engage, and educate teachers and students by getting them actively involved with NASA exploration, discovery, and the process of science. One of the main goals of the program is to facilitate student research in the classroom. The program uses astronaut photographs, provided through the ARES Crew Earth Observations (CEO) payload on the International Space Station (ISS) as the hook to help students gain an interest in a research topic. Student investigations can focus on Earth or involve comparative planetology. Student teams are encouraged to use additional imagery and data from Earth or planetary orbital spacecraft, or ground-based data collection tools, to augment the astronaut photography dataset. A second goal of the program is to provide

  9. Inspiring the Next Generation of Explorers: Scientist Involvement in the Expedition Earth and Beyond Program

    NASA Astrophysics Data System (ADS)

    Graff, P. V.; Stefanov, W. L.; Willis, K.; Runco, S.

    2012-12-01

    Scientists, science experts, graduate and even undergraduate student researchers have a unique ability to inspire the next generation of explorers. These science, technology, engineering, and mathematics (STEM) experts can serve as role models for students and can help inspire them to consider future STEM-related careers. They have an exceptional ability to instill a sense of curiosity and fascination in the minds of students as they bring science to life in the classroom. Students and teachers are hungry for opportunities to interact with scientists. They feel honored when these experts take time out of their busy day to share their science, their expertise, and their stories. The key for teachers is to be cognizant of opportunities to connect their students with scientists. For scientists, the key is to know how to get involved, to have options for participation that involve different levels of commitment, and to work with educational specialists who can help facilitate their involvement. The Expedition Earth and Beyond (EEAB) Program, facilitated by the Astromaterials Research and Exploration Science (ARES) Directorate at the NASA Johnson Space Center, is an Earth and planetary science education program designed to inspire, engage, and educate teachers and students by getting them actively involved with NASA exploration, discovery, and the process of science. One of the main goals of the program is to facilitate student research in the classroom. The program uses astronaut photographs, provided through the ARES Crew Earth Observations (CEO) payload on the International Space Station (ISS) as the hook to help students gain an interest in a research topic. Student investigations can focus on Earth or involve comparative planetology. Student teams are encouraged to use additional imagery and data from Earth or planetary orbital spacecraft, or ground-based data collection tools, to augment the astronaut photography dataset. A second goal of the program is to provide

  10. When does colonisation of a semi-arid hillslope generate vegetation patterns?

    PubMed

    Sherratt, Jonathan A

    2016-07-01

    Patterned vegetation occurs in many semi-arid regions of the world. Most previous studies have assumed that patterns form from a starting point of uniform vegetation, for example as a response to a decrease in mean annual rainfall. However an alternative possibility is that patterns are generated when bare ground is colonised. This paper investigates the conditions under which colonisation leads to patterning on sloping ground. The slope gradient plays an important role because of the downhill flow of rainwater. One long-established consequence of this is that patterns are organised into stripes running parallel to the contours; such patterns are known as banded vegetation or tiger bush. This paper shows that the slope also has an important effect on colonisation, since the uphill and downhill edges of an isolated vegetation patch have different dynamics. For the much-used Klausmeier model for semi-arid vegetation, the author shows that without a term representing water diffusion, colonisation always generates uniform vegetation rather than a pattern. However the combination of a sufficiently large water diffusion term and a sufficiently low slope gradient does lead to colonisation-induced patterning. The author goes on to consider colonisation in the Rietkerk model, which is also in widespread use: the same conclusions apply for this model provided that a small threshold is imposed on vegetation biomass, below which plant growth is set to zero. Since the two models are quite different mathematically, this suggests that the predictions are a consequence of the basic underlying assumption of water redistribution as the pattern generation mechanism.

  11. Local network parameters can affect inter-network phase lags in central pattern generators.

    PubMed

    Jones, S R; Kopell, N

    2006-01-01

    Weakly coupled phase oscillators and strongly coupled relaxation oscillators have different mechanisms for creating stable phase lags. Many oscillations in central pattern generators combine features of each type of coupling: local networks composed of strongly coupled relaxation oscillators are weakly coupled to similar local networks. This paper analyzes the phase lags produced by this combination of mechanisms and shows how the parameters of a local network, such as the decay time of inhibition, can affect the phase lags between the local networks. The analysis is motivated by the crayfish central pattern generator used for swimming, and uses techniques from geometrical singular perturbation theory.

  12. Structural vibration control by tuned mass damper using central pattern generator

    NASA Astrophysics Data System (ADS)

    Iba, Daisuke; Hongu, Junichi

    2011-04-01

    This paper proposes a new control method for active mass dampers using a Central Pattern Generator in vibration mitigation. The active mass dampers (or active dynamic absorbers) have been applied to structural vibration control of high-rise buildings, bridges and so on. In this case, the mass of the active mass damper must oscillate in an appropriate phase in relation to the control object, and generally, the damper has been designed by linear control theory as pole placement method, optimal control method or H infinity control method, and all the rest. On the other hand, on walking of animate beings like mammals or insects, both side feet have appropriate phase relations; moreover, it is possible to keep moving on irregular ground. That is, algorithms for the walking would be embedded into the animate beings to control the complicated and redundant bodies with ease and robustness. In biological study, the Central Pattern Generators in bodies playing a significant role in the walking have been learned over the last few decades, and some studies said that some animate beings are able to control their feet by using the generators without their brains in the walking. Moreover, mathematical models of the pattern generators have been proposed, and some researchers have been studying to realize walking of biped-robots using the pattern generators embedded in a computer. In this study, the algorithm is installed into a controller for the active mass damper; furthermore, validation of the controller is performed by numerical simulation.

  13. Tunable nano-pattern generation and photolithography using hybrid Kretschmann and Otto structures

    NASA Astrophysics Data System (ADS)

    Xu, Fuyang; Wang, Chinhua; Hu, Jingpei

    2016-10-01

    We propose a continuous tuning SPPs interference photolithography using hybrid Kretschmann and Otto structures. The patterns are formed by the interference of two kinds of SPPs excited by Kretschmann structure and Otto structure respectively, and the tuning capability is implemented by changing the angle between the two kinds of SPPs beams and varying the amplitude and phase of corresponding incident beams. Numerical results show the flexibility and convenience in tuning of interference patterns and resolutions with high contrast, both one and two dimension periodic patterns can be generated and tuned easily. This proposed method is possible to develop a new tunable SPPs photolithography technique for fabrication of periodic nanostructures.

  14. Synaptic patterning of left-right alternation in a computational model of the rodent hindlimb central pattern generator.

    PubMed

    Sherwood, William Erik; Harris-Warrick, Ronald; Guckenheimer, John

    2011-04-01

    Establishing, maintaining, and modifying the phase relationships between extensor and flexor muscle groups is essential for central pattern generators in the spinal cord to coordinate the hindlimbs well enough to produce the basic walking rhythm. This paper investigates a simplified computational model for the spinal hindlimb central pattern generator (CPG) that is abstracted from experimental data from the rodent spinal cord. This model produces locomotor-like activity with appropriate phase relationships in which right and left muscle groups alternate while extensor and flexor muscle groups alternate. Convergence to this locomotor pattern is slow, however, and the range of parameter values for which the model produces appropriate output is relatively narrow. We examine these aspects of the model's coordination of left-right activity through investigation of successively more complicated subnetworks, focusing on the role of the synaptic architecture in shaping motoneuron phasing. We find unexpected sensitivity in the phase response properties of individual neurons in response to stimulation and a need for high levels of both inhibition and excitation to achieve the walking rhythm. In the absence of cross-cord excitation, equal levels of ipsilateral and contralateral inhibition result in a strong preference for hopping over walking. Inhibition alone can produce the walking rhythm, but contralateral inhibition must be much stronger than ipsilateral inhibition. Cross-cord excitatory connections significantly enhance convergence to the walking rhythm, which is achieved most rapidly with strong crossed excitation and greater contralateral than ipsilateral inhibition. We discuss the implications of these results for CPG architectures based on unit burst generators.

  15. Detection of Weak Radiation Involving Generation and Progress of Water Tree

    NASA Astrophysics Data System (ADS)

    Kumazawa, Takao; Taniguchi, Ryouichi

    It is well known that generation and progress of water tree in XLPE cable are remarkably influenced by inorganic impurities. We have investigated the behavior of them in water tree and reported the experimental results as follows: i) the anomalous increase or decrease in several kinds of inorganic elements was observed in water treed XLPE samples, ii) a distinctive relationship was found for the mass numbers for the elements, iii) the isotopic content of the elements such as Zn deviated over 6% from the natural abundance. These results suggest that water tree is concerned with unknown phenomena e.g., cold fusion or nuclear transmutation in condensed matter. In order to study the relationship between water tree and these phenomena, we attempted to detect neutron, γ-ray or X-ray involving generation and progress of water tree in XLPE samples. For the experiments weak and burst-like radiation seemed to be low energy γ-ray or X-ray was often detected by BF3 and/or CdZnTe counter. The radiation tended to be detected from the samples in which a lot of water trees were generated by supplying inorganic cations abundantly.

  16. Impact of cercal air currents on singing motor pattern generation in the cricket (Gryllus bimaculatus DeGeer).

    PubMed

    Jacob, Pedro F; Hedwig, Berthold

    2015-11-01

    The cercal system of crickets detects low-frequency air currents produced by approaching predators and self-generated air currents during singing, which may provide sensory feedback to the singing motor network. We analyzed the effect of cercal stimulation on singing motor pattern generation to reveal the response of a singing interneuron to predator-like signals and to elucidate the possible role of self-generated air currents during singing. In fictive singing males, we recorded an interneuron of the singing network while applying air currents to the cerci; additionally, we analyzed the effect of abolishing the cercal system in freely singing males. In fictively singing crickets, the effect of short air stimuli is either to terminate prematurely or to lengthen the interchirp interval, depending on their phase in the chirp cycle. Within our stimulation paradigm, air stimuli of different velocities and durations always elicited an inhibitory postsynaptic potential in the singing interneuron. Current injection in the singing interneuron elicited singing motor activity, even during the air current-evoked inhibitory input from the cercal pathway. The disruptive effects of air stimuli on the fictive singing pattern and the inhibitory response of the singing interneuron point toward the cercal system being involved in initiating avoidance responses in singing crickets, according to the established role of cerci in a predator escape pathway. After abolishing the activity of the cercal system, the timing of natural singing activity was not significantly altered. Our study provides no evidence that self-generated cercal sensory activity has a feedback function for singing motor pattern generation.

  17. Impact of cercal air currents on singing motor pattern generation in the cricket (Gryllus bimaculatus DeGeer)

    PubMed Central

    2015-01-01

    The cercal system of crickets detects low-frequency air currents produced by approaching predators and self-generated air currents during singing, which may provide sensory feedback to the singing motor network. We analyzed the effect of cercal stimulation on singing motor pattern generation to reveal the response of a singing interneuron to predator-like signals and to elucidate the possible role of self-generated air currents during singing. In fictive singing males, we recorded an interneuron of the singing network while applying air currents to the cerci; additionally, we analyzed the effect of abolishing the cercal system in freely singing males. In fictively singing crickets, the effect of short air stimuli is either to terminate prematurely or to lengthen the interchirp interval, depending on their phase in the chirp cycle. Within our stimulation paradigm, air stimuli of different velocities and durations always elicited an inhibitory postsynaptic potential in the singing interneuron. Current injection in the singing interneuron elicited singing motor activity, even during the air current-evoked inhibitory input from the cercal pathway. The disruptive effects of air stimuli on the fictive singing pattern and the inhibitory response of the singing interneuron point toward the cercal system being involved in initiating avoidance responses in singing crickets, according to the established role of cerci in a predator escape pathway. After abolishing the activity of the cercal system, the timing of natural singing activity was not significantly altered. Our study provides no evidence that self-generated cercal sensory activity has a feedback function for singing motor pattern generation. PMID:26334014

  18. Central pattern generators for a common semiology in fronto-limbic seizures and in parasomnias. A neuroethologic approach.

    PubMed

    Tassinari, C A; Rubboli, G; Gardella, E; Cantalupo, G; Calandra-Buonaura, G; Vedovello, M; Alessandria, M; Gandini, G; Cinotti, S; Zamponi, N; Meletti, S

    2005-12-01

    Central pattern generators (CPGs) are genetically determined neuronal aggregates in the mesencephalon, pons and spinal cord subserving innate motor behaviours essential for survival (feeding, locomotion, reproduction etc.). In higher primates CPGs are largely under neocortical control. We describe how certain motor events observed in parasomnias and epileptic seizures could have similar features and resemble motor behaviours, which can be the expression of the same CPG. Both epilepsy and sleep can lead to a temporary loss of control of neomammalian cortex that facilitates through a common platform (arousal) the emergences of stereotyped inborn fixed action patterns. Therefore we suggest that, independently from the nature of the trigger, be it a seizure or a parasomnia, the same CPGs can be involved, "caught up", leading to a common motor semiology (the "Carillon theory").

  19. Student-Generated Content in College Teaching: Content Quality, Behavioural Pattern and Learning Performance

    ERIC Educational Resources Information Center

    Yang, X.; Guo, X.; Yu, S.

    2016-01-01

    This study investigates the quality of course content, behavioural patterns of students and learning performance in teaching of student-generated content (SGC). A total of 49 third-year university students in educational technology participated in this study. By combining the methods of questionnaire, lag sequence analysis and interview, the study…

  20. The Development of Group Interaction Patterns: How Groups become Adaptive, Generative, and Transformative Learners

    ERIC Educational Resources Information Center

    London, Manuel; Sessa, Valerie I.

    2007-01-01

    This article integrates the literature on group interaction process analysis and group learning, providing a framework for understanding how patterns of interaction develop. The model proposes how adaptive, generative, and transformative learning processes evolve and vary in their functionality. Environmental triggers for learning, the group's…

  1. Variation in motor output and motor performance in a centrally generated motor pattern.

    PubMed

    Wenning, Angela; Norris, Brian J; Doloc-Mihu, Anca; Calabrese, Ronald L

    2014-07-01

    Central pattern generators (CPGs) produce motor patterns that ultimately drive motor outputs. We studied how functional motor performance is achieved, specifically, whether the variation seen in motor patterns is reflected in motor performance and whether fictive motor patterns differ from those in vivo. We used the leech heartbeat system in which a bilaterally symmetrical CPG coordinates segmental heart motor neurons and two segmented heart tubes into two mutually exclusive coordination modes: rear-to-front peristaltic on one side and nearly synchronous on the other, with regular side-to-side switches. We assessed individual variability of the motor pattern and the beat pattern in vivo. To quantify the beat pattern we imaged intact adults. To quantify the phase relations between motor neurons and heart constrictions we recorded extracellularly from two heart motor neurons and movement from the corresponding heart segments in minimally dissected leeches. Variation in the motor pattern was reflected in motor performance only in the peristaltic mode, where larger intersegmental phase differences in the motor neurons resulted in larger phase differences between heart constrictions. Fictive motor patterns differed from those in vivo only in the synchronous mode, where intersegmental phase differences in vivo had a larger front-to-rear bias and were more constrained. Additionally, load-influenced constriction timing might explain the amplification of the phase differences between heart segments in the peristaltic mode and the higher variability in motor output due to body shape assumed in this soft-bodied animal. The motor pattern determines the beat pattern, peristaltic or synchronous, but heart mechanics influence the phase relations achieved.

  2. From central pattern generator to sensory template in the evolution of birdsong.

    PubMed

    Konishi, Masakazu

    2010-10-01

    Central nervous networks, be they a part of the human brain or a group of neurons in a snail, may be designed to produce distinct patterns of movement. Central pattern generators can account for the development and production of normal vocal signals without auditory feedback in non-songbirds. Songbirds need auditory feedback to develop and maintain the normal song of their species. The prerequisite for the use of auditory feedback for the control of song is a set of acoustic criteria or a template to which voice must match. The template method perhaps evolved to free birds from fixed central pattern generators, resulting in the evolution of diverse and complex songs among oscine songbirds. The evolution of human speech may have followed a similar course.

  3. Synergistic action of nectins and cadherins generates the mosaic cellular pattern of the olfactory epithelium

    PubMed Central

    Katsunuma, Sayaka; Honda, Hisao; Shinoda, Tomoyasu; Ishimoto, Yukitaka; Miyata, Takaki; Kiyonari, Hiroshi; Abe, Takaya; Nibu, Ken-ichi; Takai, Yoshimi

    2016-01-01

    In the olfactory epithelium (OE), olfactory cells (OCs) and supporting cells (SCs), which express different cadherins, are arranged in a characteristic mosaic pattern in which OCs are enclosed by SCs. However, the mechanism underlying this cellular patterning is unclear. Here, we show that the cellular pattern of the OE is established by cellular rearrangements during development. In the OE, OCs express nectin-2 and N-cadherin, and SCs express nectin-2, nectin-3, E-cadherin, and N-cadherin. Heterophilic trans-interaction between nectin-2 on OCs and nectin-3 on SCs preferentially recruits cadherin via α-catenin to heterotypic junctions, and the differential distributions of cadherins between junctions promote cellular intercalations, resulting in the formation of the mosaic pattern. These observations are confirmed by model cell systems, and various cellular patterns are generated by the combinatorial expression of nectins and cadherins. Collectively, the synergistic action of nectins and cadherins generates mosaic pattern, which cannot be achieved by a single mechanism. PMID:26929452

  4. Differential Amino Acid, Carbohydrate and Lipid Metabolism Perpetuations Involved in a Subtype of Rheumatoid Arthritis with Chinese Medicine Cold Pattern

    PubMed Central

    Guo, Hongtao; Niu, Xuyan; Gu, Yan; Lu, Cheng; Xiao, Cheng; Yue, Kevin; Zhang, Ge; Pan, Xiaohua; Jiang, Miao; Tan, Yong; Kong, Hongwei; Liu, Zhenli; Xu, Guowang; Lu, Aiping

    2016-01-01

    Pattern classification is a key approach in Traditional Chinese Medicine (TCM), and it is used to classify the patients for intervention selection accordingly. TCM cold and heat patterns, two main patterns of rheumatoid arthritis (RA) had been explored with systems biology approaches. Different regulations of apoptosis were found to be involved in cold and heat classification in our previous works. For this study, the metabolic profiling of plasma was explored in RA patients with typical TCM cold or heat patterns by integrating liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS) platforms in conjunction with the Ingenuity Pathway Analysis (IPA) software. Three main processes of metabolism, including amino acid, carbohydrate and lipid were focused on for function analysis. The results showed that 29 and 19 differential metabolites were found in cold and heat patterns respectively, compared with healthy controls. The perturbation of amino acid metabolism (increased essential amino acids), carbohydrate metabolism (galactose metabolism) and lipid metabolism, were found to be involved in both cold and heat pattern RA. In particular, more metabolic perturbations in protein and collagen breakdown, decreased glycolytic activity and aerobic oxidation, and increased energy utilization associated with RA cold pattern patients. These findings may be useful for obtaining a better understanding of RA pathogenesis and for achieving a better efficacy in RA clinical practice. PMID:27775663

  5. The locust frontal ganglion: a multi-tasked central pattern generator.

    PubMed

    Ayali, A; Zilberstein, Yael

    2004-01-01

    The locust frontal ganglion (FG) constitutes a major source of innervation to the foregut dilator muscles and thus plays a key role in control of foregut movements. This paper reviews our recent studies on the generation and characteristics of FG motor outputs in two distinct and fundamental locust behaviors: feeding and molting. In an in vitro preparation, isolated from all descending and sensory inputs, the FG was spontaneously active and generated rhythmic multi-unit bursts of action potentials, which could be recorded from all efferent nerves. Thus the FG motor pattern is generated by a central pattern generator within the ganglion. Intracellular recordings suggest that only a small fraction (10-20%) of the FG 100 neurons demonstrate rhythmic activity. The FG motor output in vivo was relatively complex, and strongly dependent on the locust's physiological and behavioral state. Rhythmic activity of the foregut was found to depend on the amount of food present in the crop; animals with full crop demonstrated higher FG burst frequency than those with empty crop. At the molt, the FG generates a distinct motor pattern that could be related to air-swallowing behavior.

  6. Production patterns of packaging waste categories generated at typical Mediterranean residential building worksites.

    PubMed

    González Pericot, N; Villoria Sáez, P; Del Río Merino, M; Liébana Carrasco, O

    2014-11-01

    The construction sector is responsible for around 28% of the total waste volume generated in Europe, which exceeds the amount of household waste. This has led to an increase of different research studies focusing on construction waste quantification. However, within the research studies made, packaging waste has been analyzed to a limited extent. This article focuses on the packaging waste stream generated in the construction sector. To this purpose current on-site waste packaging management has been assessed by monitoring ten Mediterranean residential building works. The findings of the experimental data collection revealed that the incentive measures implemented by the construction company to improve on-site waste sorting failed to achieve the intended purpose, showing low segregation ratios. Subsequently, through an analytical study the generation patterns for packaging waste are established, leading to the identification of the prevailing kinds of packaging and the products responsible for their generation. Results indicate that plastic waste generation maintains a constant trend throughout the whole construction process, while cardboard becomes predominant towards the end of the construction works with switches and sockets from the electricity stage. Understanding the production patterns of packaging waste will be beneficial for adapting waste management strategies to the identified patterns for the specific nature of packaging waste within the context of construction worksites.

  7. Generation, ethnicity, and marriage: historical patterns in the northern United States.

    PubMed

    Landale, N S; Tolnay, S E

    1993-02-01

    Immigration was a prominent feature of American life during the early decades of the twentieth century. About 40% of the white population was of foreign birth or parentage, and immigrants were increasingly from diverse national origins. Using data from the Public Use Microdata Sample of the 1910 U.S. Census, we examine generational and ethnic differences in marital timing. The analysis reveals a striking pattern of delayed marriage among native whites with foreign parents, but marked ethnic variation in the extent of marriage delay within the second generation. We hypothesize that locational factors, especially diverse economic opportunities, were important in shaping this marriage pattern. Separate multilevel analyses are conducted for females and for males living in urban and in rural places. Although significant effects for a variety of contextual factors are found, generational and ethnic differences in nuptial timing persist in multivariate models.

  8. [Involvement of carbonate/bicarbonate ions in the superoxide-generating reaction of adrenaline autoxidation].

    PubMed

    Sirota, T V

    2015-01-01

    An important role of carbonate/bicarbonate ions has been recognized in the superoxide generating reaction of adrenaline autooxidation in an alkaline buffer (a model of quinoid adrenaline oxidation in the body). It is suggested that these ions are directly involved not only in formation of superoxide anion radical (О(2)(-)) but also other radicals derived from the carbonate/bicarbonate buffer. Using various buffers it was shown that the rate of accumulation of adrenochrome, the end product of adrenaline oxidation, and the rate of О(2)(-)· formation depend on concentration of carbonate/bicarbonate ions in the buffer and that these ions significantly accelerate adrenaline autooxidation thus demonstrating prooxidant properties. The detectable amount of diformazan, the product of nitro blue tetrazolium (NBT) reduction, was significantly higher than the amount of adrenochrome formed; taking into consideration the literature data on О(2)(-)· detection by NBT it is suggested that adrenaline autooxidation is accompanied by one-electron reduction not only of oxygen dissolved in the buffer and responsible for superoxide formation but possible carbon dioxide also dissolved in the buffer as well as carbonate/bicarbonate buffer components leading to formation of corresponding radicals. The plots of the dependence of the inhibition of adrenochrome and diformazan formation on the superoxide dismutase concentration have shown that not only superoxide radicals are formed during adrenaline autooxidation. Since carbonate/bicarbonate ions are known to be universally present in the living nature, their involvement in free radical processes proceeding in the organism is discussed.

  9. Physical components of soft-tissue ballistic wounding and their involvement in the generation of blood backspatter.

    PubMed

    Davidson, Peter L; Taylor, Michael C; Wilson, Suzanne J; Walsh, Kevan A J; Kieser, Jules A

    2012-09-01

    Gunshot backspatter comprises biological material expelled backward through bullet entry holes. Crime scene investigators analyze backspatter patterns to infer wounding circumstances. An understanding of the mechanism of backspatter generation, and the relationship between spatter patterns and bullet and tissue characteristics, would enhance the predictive value of such analysis. We examined soft-tissue ballistic wounding responses to determine the underlying components and how these might be relevant to the generation of backspatter. We identified five mechanistic components to ballistic wounding (elastic, viscous, crushing, cutting, and thermal), each related to mechanical disciplines (respectively, solid mechanics, fluid mechanics, fracture mechanics, rheology, and thermodynamics). We identified potential roles for these five components in backspatter formation and provide a scenario whereby a sequence of events incorporating these components could lead to backspatter generation and expulsion. This research provides a framework for the mathematical representation, and subsequent computational predictive modeling, of backspatter generation and pattern formation.

  10. Preclinical evidence supporting the clinical development of central pattern generator-modulating therapies for chronic spinal cord-injured patients.

    PubMed

    Guertin, Pierre A

    2014-01-01

    Ambulation or walking is one of the main gaits of locomotion. In terrestrial animals, it may be defined as a series of rhythmic and bilaterally coordinated movement of the limbs which creates a forward movement of the body. This applies regardless of the number of limbs-from arthropods with six or more limbs to bipedal primates. These fundamental similarities among species may explain why comparable neural systems and cellular properties have been found, thus far, to control in similar ways locomotor rhythm generation in most animal models. The aim of this article is to provide a comprehensive review of the known structural and functional features associated with central nervous system (CNS) networks that are involved in the control of ambulation and other stereotyped motor patterns-specifically Central Pattern Generators (CPGs) that produce basic rhythmic patterned outputs for locomotion, micturition, ejaculation, and defecation. Although there is compelling evidence of their existence in humans, CPGs have been most studied in reduced models including in vitro isolated preparations, genetically-engineered mice and spinal cord-transected animals. Compared with other structures of the CNS, the spinal cord is generally considered as being well-preserved phylogenetically. As such, most animal models of spinal cord-injured (SCI) should be considered as valuable tools for the development of novel pharmacological strategies aimed at modulating spinal activity and restoring corresponding functions in chronic SCI patients.

  11. The role of heterarchical control in the evolution of central pattern generators.

    PubMed

    Cohen, A H

    1992-01-01

    The acceptance of the concept of central pattern generators (CPGs) led to the perception that descending inputs initiate stereotyped movements, such as locomotion, but play relatively minor roles after the movement begins. Sensory input could entrain the CPG, and the CPG was responsive to the proper inputs for switching, etc. Evidence is here presented that the influences of both descending and sensory inputs are two-way. Descending inputs are shown to be involved in an ongoing manner during locomotion, as it has been found that CPGs are phasically driving the same descending systems that themselves activate the CPGs. Similarly, sensory inputs are being actively processed by the CPG and, here again, produce a two-way interaction between sensory input and CPGs. Finally, mechanical factors are shown to be major contributors to the form of the movement. Thus, overall the CPG can only be considered as one of several contributors to any movement; all concurrently process the flow of information. Control is viewed as distributed, that is, as heterarchical as opposed to hierarchical. Because of the complexity of interaction between the levels of the system, it is argued that any change in the body will propagate through the system and effect the final output regardless of where the change originates. Thus, ontogenetic and phylogenetic changes must have influences felt throughout the entire system. Examples are presented to demonstrate that this is, indeed, the case. The effect of these changes will primarily be manifest in the interface between the layers, that is, in the interface between the descending and sensory inputs and the CPG, so that the changes can be adaptively accommodated on a moment by moment basis when necessary.

  12. Integument pattern formation involves genetic and epigenetic controls: feather arrays simulated by digital hormone models.

    PubMed

    Jiang, Ting-Xin; Widelitz, Randall B; Shen, Wei-Min; Will, Peter; Wu, Da-Yu; Lin, Chih-Min; Jung, Han-Sung; Chuong, Cheng-Ming

    2004-01-01

    Pattern formation is a fundamental morphogenetic process. Models based on genetic and epigenetic control have been proposed but remain controversial. Here we use feather morphogenesis for further evaluation. Adhesion molecules and/or signaling molecules were first expressed homogenously in feather tracts (restrictive mode, appear earlier) or directly in bud or inter-bud regions ( de novo mode, appear later). They either activate or inhibit bud formation, but paradoxically colocalize in the bud. Using feather bud reconstitution, we showed that completely dissociated cells can reform periodic patterns without reference to previous positional codes. The patterning process has the characteristics of being self-organizing, dynamic and plastic. The final pattern is an equilibrium state reached by competition, and the number and size of buds can be altered based on cell number and activator/inhibitor ratio, respectively. We developed a Digital Hormone Model which consists of (1) competent cells without identity that move randomly in a space, (2) extracellular signaling hormones which diffuse by a reaction-diffusion mechanism and activate or inhibit cell adhesion, and (3) cells which respond with topological stochastic actions manifested as changes in cell adhesion. Based on probability, the results are cell clusters arranged in dots or stripes. Thus genetic control provides combinational molecular information which defines the properties of the cells but not the final pattern. Epigenetic control governs interactions among cells and their environment based on physical-chemical rules (such as those described in the Digital Hormone Model). Complex integument patterning is the sum of these two components of control and that is why integument patterns are usually similar but non-identical. These principles may be shared by other pattern formation processes such as barb ridge formation, fingerprints, pigmentation patterning, etc. The Digital Hormone Model can also be applied to

  13. Integument pattern formation involves genetic and epigenetic controls: feather arrays simulated by digital hormone models

    PubMed Central

    Jiang, Ting-Xin; Widelitz, Randall B.; Shen, Wei-Min; Will, Peter; Wu, Da-Yu; Lin, Chih-Min; Jung, Han-Sung; Chuong, Cheng-Ming

    2015-01-01

    Pattern formation is a fundamental morphogenetic process. Models based on genetic and epigenetic control have been proposed but remain controversial. Here we use feather morphogenesis for further evaluation. Adhesion molecules and/or signaling molecules were first expressed homogenously in feather tracts (restrictive mode, appear earlier) or directly in bud or inter-bud regions (de novo mode, appear later). They either activate or inhibit bud formation, but paradoxically co-localize in the bud. Using feather bud reconstitution, we showed that completely dissociated cells can reform periodic patterns without reference to previous positional codes. The patterning process has the characteristics of being self-organizing, dynamic and plastic. The final pattern is an equilibrium state reached by competition, and the number and size of buds can be altered based on cell number and activator/inhibitor ratio, respectively. We developed a Digital Hormone Model which consists of (1) competent cells without identity that move randomly in a space, (2) extracellular signaling hormones which diffuse by a reaction-diffusion mechanism and activate or inhibit cell adhesion, and (3) cells which respond with topological stochastic actions manifested as changes in cell adhesion. Based on probability, the results are cell clusters arranged in dots or stripes. Thus genetic control provides combinational molecular information which defines the properties of the cells but not the final pattern. Epigenetic control governs interactions among cells and their environment based on physical-chemical rules (such as those described in the Digital Hormone Model). Complex integument patterning is the sum of these two components of control and that is why integument patterns are usually similar but non-identical. These principles may be shared by other pattern formation processes such as barb ridge formation, fingerprints, pigmentation patterning, etc. The Digital Hormone Model can also be applied to

  14. Production patterns of packaging waste categories generated at typical Mediterranean residential building worksites

    SciTech Connect

    González Pericot, N.; Villoria Sáez, P.; Del Río Merino, M.; Liébana Carrasco, O.

    2014-11-15

    Highlights: • On-site segregation level: 1.80%; training and motivation strategies were not effective. • 70% Cardboard waste: from switches and sockets during the building services stage. • 40% Plastic waste: generated during structures and partition works due to palletizing. • >50% Wood packaging waste, basically pallets, generated during the envelope works. - Abstract: The construction sector is responsible for around 28% of the total waste volume generated in Europe, which exceeds the amount of household waste. This has led to an increase of different research studies focusing on construction waste quantification. However, within the research studies made, packaging waste has been analyzed to a limited extent. This article focuses on the packaging waste stream generated in the construction sector. To this purpose current on-site waste packaging management has been assessed by monitoring ten Mediterranean residential building works. The findings of the experimental data collection revealed that the incentive measures implemented by the construction company to improve on-site waste sorting failed to achieve the intended purpose, showing low segregation ratios. Subsequently, through an analytical study the generation patterns for packaging waste are established, leading to the identification of the prevailing kinds of packaging and the products responsible for their generation. Results indicate that plastic waste generation maintains a constant trend throughout the whole construction process, while cardboard becomes predominant towards the end of the construction works with switches and sockets from the electricity stage. Understanding the production patterns of packaging waste will be beneficial for adapting waste management strategies to the identified patterns for the specific nature of packaging waste within the context of construction worksites.

  15. Cellular basis for singing motor pattern generation in the field cricket (Gryllus bimaculatus DeGeer)

    PubMed Central

    Schöneich, Stefan; Hedwig, Berthold

    2012-01-01

    The singing behavior of male crickets allows analyzing a central pattern generator (CPG) that was shaped by sexual selection for reliable production of species-specific communication signals. After localizing the essential ganglia for singing in Gryllus bimaculatus, we now studied the calling song CPG at the cellular level. Fictive singing was initiated by pharmacological brain stimulation. The motor pattern underlying syllables and chirps was recorded as alternating spike bursts of wing-opener and wing-closer motoneurons in a truncated wing nerve; it precisely reflected the natural calling song. During fictive singing, we intracellularly recorded and stained interneurons in thoracic and abdominal ganglia and tested their impact on the song pattern by intracellular current injections. We identified three interneurons of the metathoracic and first unfused abdominal ganglion that rhythmically de- and hyperpolarized in phase with the syllable pattern and spiked strictly before the wing-opener motoneurons. Depolarizing current injection in two of these opener interneurons caused additional rhythmic singing activity, which reliably reset the ongoing chirp rhythm. The closely intermeshing arborizations of the singing interneurons revealed the dorsal midline neuropiles of the metathoracic and three most anterior abdominal neuromeres as the anatomical location of singing pattern generation. In the same neuropiles, we also recorded several closer interneurons that rhythmically hyper- and depolarized in the syllable rhythm and spiked strictly before the wing-closer motoneurons. Some of them received pronounced inhibition at the beginning of each chirp. Hyperpolarizing current injection in the dendrite revealed postinhibitory rebound depolarization as one functional mechanism of central pattern generation in singing crickets. PMID:23170234

  16. Composite axilens-axicon diffractive optical elements for generation of ring patterns with high focal depth

    NASA Astrophysics Data System (ADS)

    Dharmavarapu, Raghu; Vijayakumar, A.; Brunner, R.; Bhattacharya, Shanti

    2016-03-01

    A binary Fresnel Zone Axilens (FZA) is designed for the infinite conjugate mode and the phase profile of a refractive axicon is combined with it to generate a composite Diffractive Optical Element (DOE). The FZA designed for two focal lengths generates a line focus along the propagation direction extending between the two focal planes. The ring pattern generated by the axicon is focused through this distance and the radius of the ring depends on the propagation distance. Hence, the radius of the focused ring pattern can be tuned, during the design process, within the two focal planes. The integration of the two functions was carried out by shifting the location of zones of FZA with respect to the phase profile of the refractive axicon resulting in a binary composite DOE. The FZAs and axicons were designed for different focal depth values and base angles respectively, in order to achieve different ring radii within the focal depth of each element. The elements were simulated using scalar diffraction formula and their focusing characteristics were analyzed. The DOEs were fabricated using electron beam direct writing and evaluated using a fiber coupled diode laser. The tunable ring patterns generated by the DOEs have prospective applications in microdrilling as well as microfabrication of circular diffractive and refractive optical elements.

  17. Generation of conical patterns from circular patch antennas and their performance

    NASA Astrophysics Data System (ADS)

    Kumar, G.; Shafai, L.

    1985-07-01

    The input and radiation characteristics of circular microstrip antennas operated at higher order modes to generate conical patterns are studied. The effects of varying the substrate parameters on characteristics such as radiation pattern, directivity, bandwidth, efficiency and location of the feedpoint to match a 50 ohm line are investigated. Also, a multifeed technique to operate the antenna at any particular higher order mode is proposed. Successful experiments have used this technique to operate the antenna at the desired higher order modes and the experimental results are in close agreement with the theoretical analysis.

  18. Successful retrieval of competing spatial environments in humans involves hippocampal pattern separation mechanisms

    PubMed Central

    Kyle, Colin T; Stokes, Jared D; Lieberman, Jennifer S; Hassan, Abdul S; Ekstrom, Arne D

    2015-01-01

    The rodent hippocampus represents different spatial environments distinctly via changes in the pattern of “place cell” firing. It remains unclear, though, how spatial remapping in rodents relates more generally to human memory. Here participants retrieved four virtual reality environments with repeating or novel landmarks and configurations during high-resolution functional magnetic resonance imaging (fMRI). Both neural decoding performance and neural pattern similarity measures revealed environment-specific hippocampal neural codes. Conversely, an interfering spatial environment did not elicit neural codes specific to that environment, with neural activity patterns instead resembling those of competing environments, an effect linked to lower retrieval performance. We find that orthogonalized neural patterns accompany successful disambiguation of spatial environments while erroneous reinstatement of competing patterns characterized interference errors. These results provide the first evidence for environment-specific neural codes in the human hippocampus, suggesting that pattern separation/completion mechanisms play an important role in how we successfully retrieve memories. DOI: http://dx.doi.org/10.7554/eLife.10499.001 PMID:26613414

  19. Parental Involvement in Infant Sleep Routines Predicts Differential Sleep Patterns in Children With and Without Anxiety Disorders.

    PubMed

    Cowie, Jennifer; Palmer, Cara A; Hussain, Hira; Alfano, Candice A

    2016-08-01

    This study compared parents' retrospective reports of their involvement in infant settling strategies and their relation to current sleep patterns among children (N = 84, ages 7-11) with generalized anxiety disorder (GAD) and healthy controls. Parents of children with GAD were significantly more likely to report rocking their infants to sleep and putting infants down when they were already asleep than parents of healthy controls, even when accounting for infant health-related factors and parental anxiety. Greater involvement in infant sleep routines also predicted sleep patterns (measured via actigraphy) during childhood, though opposite relationships were observed in the two groups. Early involvement was related to poorer sleep in control children but better sleep for children with GAD even after controlling for current parenting practices. Findings suggest differential effects of early sleep-related parenting for children with and without later anxiety disorders with possible implications for early intervention.

  20. SOM-based Pattern Generator: Pattern Generation Based on the Backward Projection in a Self-Organizing Map and Its Applications

    NASA Astrophysics Data System (ADS)

    Wakuya, Hiroshi; Ishiguma, Takahiro

    A major feature of the self-organizing map (SOM) is a topology-preserving projection from the input layer to the competitive layer, and it has been used mainly as an analytical tool for discovering underlying rules in the given data set. Even though recent splendid progress in this area, there are few novel ideas to break such a conventional style. On the contrary, based on its distinctive nature, a new method for generating patterns through backward projection from the competitive layer to the input layer is proposed recently. Moreover, a promising technology for producing animation as a series of backward-projected patterns along with any pathways on the competitive layer is presented. Then, in order to carry out further considerations, some computer simulations with a variety of posed stick figures are tried in this paper. After training, four kinds of pathways, which correspond to different movements such as dancing, exercising and walking, are prepared. Though some of them does not contain any training samples, all of them worked well as we have intended in advance. As a result, it is found that the proposed method shows good performance and it is also confirmed its effectiveness.

  1. Evolving cellular automata for diversity generation and pattern recognition: deterministic versus random strategy

    NASA Astrophysics Data System (ADS)

    Argollo de Menezes, Marcio; Brigatti, Edgardo; Schwämmle, Veit

    2013-08-01

    Microbiological systems evolve to fulfil their tasks with maximal efficiency. The immune system is a remarkable example, where the distinction between self and non-self is made by means of molecular interaction between self-proteins and antigens, triggering affinity-dependent systemic actions. Specificity of this binding and the infinitude of potential antigenic patterns call for novel mechanisms to generate antibody diversity. Inspired by this problem, we develop a genetic algorithm where agents evolve their strings in the presence of random antigenic strings and reproduce with affinity-dependent rates. We ask what is the best strategy to generate diversity if agents can rearrange their strings a finite number of times. We find that endowing each agent with an inheritable cellular automaton rule for performing rearrangements makes the system more efficient in pattern-matching than if transformations are totally random. In the former implementation, the population evolves to a stationary state where agents with different automata rules coexist.

  2. Two-phase Flow Patterns in High Temperature Generator of Absorption Chiller / Heater

    NASA Astrophysics Data System (ADS)

    Furukawa, Masahiro; Kanuma, Hitoshi; Sekoguchi, Kotohiko; Takeishi, Masayuki

    There is a lack of information about vapor-liquid two-phase flow patterns determined using void signals in high temperature generator of absorption chiller/heater. Sensing void fraction has been hampered because lithium bromide aqueous solution of strong alkalinity is employed as working fluid at high temperature and high level of vacuum. New void sensor applicable to such difficult conditions was developed. The void Fractions at 48 locations in a high temperature generator were measured simultaneously in both cooling and heating operations. Analysis of void signals detected reveals that the most violent boiling occurs at the upper part of rear plate of combustion chamber and the first line of vertical tubes located in the flue. The flow patterns are strongly affected by the system pressure difference between the cooling and heating operations: there appear bubbly, slug and froth flows in the cooling operation, but only bubbly flow in the heating operation.

  3. Experimental observation of multistability and dynamic attractors in silicon central pattern generators.

    PubMed

    Zhao, Le; Nogaret, Alain

    2015-01-01

    We report on the multistability of chaotic networks of silicon neurons and demonstrate how spatiotemporal sequences of voltage oscillations are selected with timed current stimuli. A three neuron central pattern generator was built by interconnecting Hodgkin-Huxley neurons with mutually inhibitory links mimicking gap junctions. By systematically varying the timing of current stimuli applied to individual neurons, we generate the phase lag maps of neuronal oscillators and study their dependence on the network connectivity. We identify up to six attractors consisting of triphasic sequences of unevenly spaced pulses propagating clockwise and anticlockwise. While confirming theoretical predictions, our experiments reveal more complex oscillatory patterns shaped by the ratio of the pulse width to the oscillation period. Our work contributes to validating the command neuron hypothesis.

  4. Connection topology selection in central pattern generators by maximizing the gain of information.

    PubMed

    Stiesberg, Gregory R; Reyes, Marcelo Bussotti; Varona, Pablo; Pinto, Reynaldo D; Huerta, Ramón

    2007-04-01

    A study of a general central pattern generator (CPG) is carried out by means of a measure of the gain of information between the number of available topology configurations and the output rhythmic activity. The neurons of the CPG are chaotic Hindmarsh-Rose models that cooperate dynamically to generate either chaotic or regular spatiotemporal patterns. These model neurons are implemented by computer simulations and electronic circuits. Out of a random pool of input configurations, a small subset of them maximizes the gain of information. Two important characteristics of this subset are emphasized: (1) the most regular output activities are chosen, and (2) none of the selected input configurations are networks with open topology. These two principles are observed in living CPGs as well as in model CPGs that are the most efficient in controlling mechanical tasks, and they are evidence that the information-theoretical analysis can be an invaluable tool in searching for general properties of CPGs.

  5. Experimental observation of multistability and dynamic attractors in silicon central pattern generators

    NASA Astrophysics Data System (ADS)

    Zhao, Le; Nogaret, Alain

    2015-11-01

    We report on the multistability of chaotic networks of silicon neurons and demonstrate how spatiotemporal sequences of voltage oscillations are selected with timed current stimuli. A three neuron central pattern generator was built by interconnecting Hodgkin-Huxley neurons with mutually inhibitory links mimicking gap junctions. By systematically varying the timing of current stimuli applied to individual neurons, we generate the phase lag maps of neuronal oscillators and study their dependence on the network connectivity. We identify up to six attractors consisting of triphasic sequences of unevenly spaced pulses propagating clockwise and anticlockwise. While confirming theoretical predictions, our experiments reveal more complex oscillatory patterns shaped by the ratio of the pulse width to the oscillation period. Our work contributes to validating the command neuron hypothesis.

  6. Processing of laminin α chains generates peptides involved in wound healing and host defense.

    PubMed

    Senyürek, Ilknur; Kempf, Wolfgang E; Klein, Gerd; Maurer, Andreas; Kalbacher, Hubert; Schäfer, Luisa; Wanke, Ines; Christ, Christina; Stevanovic, Stefan; Schaller, Martin; Rousselle, Patricia; Garbe, Claus; Biedermann, Tilo; Schittek, Birgit

    2014-01-01

    Laminins play a fundamental role in basement membrane architecture and function in human skin. The C-terminal laminin G domain-like (LG) modules of laminin α chains are modified by proteolysis to generate LG1-3 and secreted LG4-5 tandem modules. In this study, we provide evidence that skin-derived cells process and secrete biologically active peptides from the LG4-5 module of the laminin α3, α4 and α5 chain in vitro and in vivo. We show enhanced expression and processing of the LG4-5 module of laminin α3 in keratinocytes after infection and in chronic wounds in which the level of expression and further processing of the LG4-5 module correlated with the speed of wound healing. Furthermore, bacterial or host-derived proteases promote processing of laminin α3 LG4-5. On a functional level, we show that LG4-5-derived peptides play a role in wound healing. Moreover, we demonstrate that LG4-derived peptides from the α3, α4 and α5 chains have broad antimicrobial activity and possess strong chemotactic activity to mononuclear cells. Thus, the data strongly suggest a novel multifunctional role for laminin LG4-5-derived peptides in human skin and its involvement in physiological processes and pathological conditions such as inflammation, chronic wounds and skin infection.

  7. A Petroleum Vapor Intrusion Model Involving Upward Advective Soil Gas Flow Due to Methane Generation.

    PubMed

    Yao, Yijun; Wu, Yun; Wang, Yue; Verginelli, Iason; Zeng, Tian; Suuberg, Eric M; Jiang, Lin; Wen, Yuezhong; Ma, Jie

    2015-10-06

    At petroleum vapor intrusion (PVI) sites at which there is significant methane generation, upward advective soil gas transport may be observed. To evaluate the health and explosion risks that may exist under such scenarios, a one-dimensional analytical model describing these processes is introduced in this study. This new model accounts for both advective and diffusive transport in soil gas and couples this with a piecewise first-order aerobic biodegradation model, limited by oxygen availability. The predicted results from the new model are shown to be in good agreement with the simulation results obtained from a three-dimensional numerical model. These results suggest that this analytical model is suitable for describing cases involving open ground surface beyond the foundation edge, serving as the primary oxygen source. This new analytical model indicates that the major contribution of upward advection to indoor air concentration could be limited to the increase of soil gas entry rate, since the oxygen in soil might already be depleted owing to the associated high methane source vapor concentration.

  8. Ca2+ involvement in the action potential generation of myenteric neurones in the rat oesophagus.

    PubMed

    De Laet, A; Cornelissen, W; Adriaensen, D; Van Bogaert, P-P; Scheuermann, D W; Timmermans, J-P

    2002-04-01

    Intracellular recordings were used to study the physiological behaviour of rat oesophageal myenteric neurones, which are embedded in striated muscle. Injection of depolarizing pulses evoked action potentials with a clear 'shoulder' in all neurones. This shoulder disappeared under low Ca2+/high Mg2+ conditions. Tetrodotoxin (TTX; 1 micromol L-1) did not impede spike firing, whereas under combined TTX and low Ca2+/high Mg2+ conditions the action potentials were completely abolished, indicating that TTX- resistant action potentials are mediated by a Ca2+ current. Further experiments with omega-conotoxin GVIA (100 nmol L-1) revealed that these Ca2+ currents enter the cell via N-type voltage-activated Ca2+ channels (see also accompanying paper). Tetraethylammonium (10 mmol L-1) caused broadening of the action potentials, which probably resulted from prolonged Ca2+ influx due to blockade of the delayed rectifier K+ channel. Although Ca2+ appears to be involved in the spike generation of all rat oesophageal myenteric neurones, only a minority (14%) shows a slow afterhyperpolarization. Thus, no strict correlation exists between the presence of a shoulder and a slow afterhyperpolarization. Furthermore, morphological identification of 25 of the impaled neurones revealed that there was no strict correlation between morphology and electrophysiological behaviour. Consequently, rat oesophageal myenteric neurones appear to differ in several aspects from myenteric neurones in smooth muscle regions of the gastrointestinal tract.

  9. Phase relationships between segmentally organized oscillators in the leech heartbeat pattern generating network.

    PubMed

    Masino, Mark A; Calabrese, Ronald L

    2002-03-01

    Motor pattern generating networks that produce segmentally distributed motor outflow are often portrayed as a series of coupled segmental oscillators that produce a regular progression (constant phase differences) in their rhythmic activity. The leech heartbeat central pattern generator is paced by a core timing network, which consists of two coupled segmental oscillators in segmental ganglia 3 and 4. The segmental oscillators comprise paired mutually inhibitory oscillator interneurons and the processes of intersegmental coordinating interneurons. As a first step in understanding the coordination of segmental motor outflow by this pattern generator, we describe the functional synaptic interactions, and activity and phase relationships of the heart interneurons of the timing network, in isolated nerve cord preparations. In the timing network, most (approximately 75%) of the coordinating interneuron action potentials were generated at a primary spike initiation site located in ganglion 4 (G4). A secondary spike initiation site in ganglion 3 (G3) became active in the absence of activity at the primary site. Generally, the secondary site was characterized by a reluctance to burst and a lower spike frequency, when compared with the primary site. Oscillator interneurons in G3 inhibited spike activity at both initiation sites, whereas oscillator interneurons in G4 inhibited spike activity only at the primary initiation site. This asymmetry in the control of spike activity in the coordinating interneurons may account for the observation that the phase of the coordinating interneurons is more tightly linked to the G3 than G4 oscillator interneurons. The cycle period of the timing network and the phase difference between the ipsilateral G3 and G4 oscillator interneurons were regular within individual preparations, but varied among preparations. This variation in phase differences observed across preparations implies that modulated intrinsic membrane and synaptic properties

  10. Deposition, characterization, patterning and mechanistic study of inorganic resists for next-generation nanolithography

    NASA Astrophysics Data System (ADS)

    Luo, Feixiang

    The semiconductor industry has witnessed a continuous decrease in the size of logic, memory and other computer chip components since its birth over half a century ago. The shrinking (scaling) of components has to a large extent been enabled by the development of micro- and now nano-lithographic techniques. This thesis focuses on one central component of lithography, the resist, which is essentially a thin film that when appropriately exposed enables a pattern to be printed onto a surface. Smaller features require an ever more precisely focused photon, electron or ion beam with which to expose the resist. The likely next generation source of radiation that will enable sub-20nm features to be written will employ extreme ultraviolet radiation (EUV), 92eV (13.5nm). The work discussed here involves a novel class of inorganic resists (including a solution processed Hf-based resist called HafSOx), as the organic resists that have dominated the microlithography industry for the past few decades have approached fundamental scaling limits. In order to maintain the high throughput required by high volume semiconductor manufacturing, metal oxide resists have been proposed and developed to meet the resolution and sensitivity in EUV lithography. One can think of our resists as the nano-lithographic analog to the silver halide film that dominated the photographic print industry for a century. In this thesis, we mainly describe our work on HafSOx, a "first generation" metal oxide EUV resist system. HafSOx thin films can be deposited by spin-coating a mixed solution of HfOCl2, H2O 2, and H2SO4. Various materials characterization techniques have been employed to achieve a comprehensive understanding of film composition and structure at both surface and bulk level, as well as a mechanistic understanding of the film radiation chemistry. Taking advantage of the high energy x-rays used in the XPS experiment, we developed an experiment to dynamically monitor the photochemistry within the

  11. A method to engineer phase-encoded photon sieve for intensity pattern generations

    NASA Astrophysics Data System (ADS)

    Li, Zhenhua; Ma, Li; Gao, Yaru; Liu, Chunxiang; Xu, Shicai; Zhang, Meina; Cheng, Chuanfu

    2015-11-01

    We propose a novel type of photon sieve where phases of its sieved waves are encoded as radial positions of the pinholes and use such phase-encoded sieves for generating designed intensity patterns in Fresnel domain. The sieve pinholes are arranged around Fresnel-rings to eliminate the quadratic Fresnel phase factor of diffraction of the sieved waves, leading the wave propagation to be equivalent to Fraunhofer diffraction. The pinholes take constant size in this paper and realize equal amplitude in the multiple sieved waves. Their positions are adjusted radially from corresponding rings to encode wave phases, taking effect by resulting in different optical paths from them to the observation plane origin. Then along with wave propagation, the encoded phases are decoded and the required phase differences are obtained in the discrete waves. We first conduct numerical simulations to show satisfactory performance of such phase-encoded photon sieves in generating arbitrarily designed intensity patterns and describe the quality of the reconstructed patterns. Then for qualitatively verifying the phase-encoding method, we experimentally fabricate three such sieves with relatively small pinhole number and obtain the designed patterns.

  12. From Spinal Central Pattern Generators to Cortical Network: Integrated BCI for Walking Rehabilitation

    PubMed Central

    Cheron, G.; Duvinage, M.; De Saedeleer, C.; Castermans, T.; Bengoetxea, A.; Petieau, M.; Seetharaman, K.; Hoellinger, T.; Dan, B.; Dutoit, T.; Sylos Labini, F.; Lacquaniti, F.; Ivanenko, Y.

    2012-01-01

    Success in locomotor rehabilitation programs can be improved with the use of brain-computer interfaces (BCIs). Although a wealth of research has demonstrated that locomotion is largely controlled by spinal mechanisms, the brain is of utmost importance in monitoring locomotor patterns and therefore contains information regarding central pattern generation functioning. In addition, there is also a tight coordination between the upper and lower limbs, which can also be useful in controlling locomotion. The current paper critically investigates different approaches that are applicable to this field: the use of electroencephalogram (EEG), upper limb electromyogram (EMG), or a hybrid of the two neurophysiological signals to control assistive exoskeletons used in locomotion based on programmable central pattern generators (PCPGs) or dynamic recurrent neural networks (DRNNs). Plantar surface tactile stimulation devices combined with virtual reality may provide the sensation of walking while in a supine position for use of training brain signals generated during locomotion. These methods may exploit mechanisms of brain plasticity and assist in the neurorehabilitation of gait in a variety of clinical conditions, including stroke, spinal trauma, multiple sclerosis, and cerebral palsy. PMID:22272380

  13. Towards pattern generation and chaotic series prediction with photonic reservoir computers

    NASA Astrophysics Data System (ADS)

    Antonik, Piotr; Hermans, Michiel; Duport, François; Haelterman, Marc; Massar, Serge

    2016-03-01

    Reservoir Computing is a bio-inspired computing paradigm for processing time dependent signals that is particularly well suited for analog implementations. Our team has demonstrated several photonic reservoir computers with performance comparable to digital algorithms on a series of benchmark tasks such as channel equalisation and speech recognition. Recently, we showed that our opto-electronic reservoir computer could be trained online with a simple gradient descent algorithm programmed on an FPGA chip. This setup makes it in principle possible to feed the output signal back into the reservoir, and thus highly enrich the dynamics of the system. This will allow to tackle complex prediction tasks in hardware, such as pattern generation and chaotic and financial series prediction, which have so far only been studied in digital implementations. Here we report simulation results of our opto-electronic setup with an FPGA chip and output feedback applied to pattern generation and Mackey-Glass chaotic series prediction. The simulations take into account the major aspects of our experimental setup. We find that pattern generation can be easily implemented on the current setup with very good results. The Mackey-Glass series prediction task is more complex and requires a large reservoir and more elaborate training algorithm. With these adjustments promising result are obtained, and we now know what improvements are needed to match previously reported numerical results. These simulation results will serve as basis of comparison for experiments we will carry out in the coming months.

  14. From spinal central pattern generators to cortical network: integrated BCI for walking rehabilitation.

    PubMed

    Cheron, G; Duvinage, M; De Saedeleer, C; Castermans, T; Bengoetxea, A; Petieau, M; Seetharaman, K; Hoellinger, T; Dan, B; Dutoit, T; Sylos Labini, F; Lacquaniti, F; Ivanenko, Y

    2012-01-01

    Success in locomotor rehabilitation programs can be improved with the use of brain-computer interfaces (BCIs). Although a wealth of research has demonstrated that locomotion is largely controlled by spinal mechanisms, the brain is of utmost importance in monitoring locomotor patterns and therefore contains information regarding central pattern generation functioning. In addition, there is also a tight coordination between the upper and lower limbs, which can also be useful in controlling locomotion. The current paper critically investigates different approaches that are applicable to this field: the use of electroencephalogram (EEG), upper limb electromyogram (EMG), or a hybrid of the two neurophysiological signals to control assistive exoskeletons used in locomotion based on programmable central pattern generators (PCPGs) or dynamic recurrent neural networks (DRNNs). Plantar surface tactile stimulation devices combined with virtual reality may provide the sensation of walking while in a supine position for use of training brain signals generated during locomotion. These methods may exploit mechanisms of brain plasticity and assist in the neurorehabilitation of gait in a variety of clinical conditions, including stroke, spinal trauma, multiple sclerosis, and cerebral palsy.

  15. Inferior olivary nucleus involvement in pediatric neurodegenerative disorders: does it play a role in neuroimaging pattern-recognition approach?

    PubMed

    Mirabelli-Badenier, Marisol; Morana, Giovanni; Bruno, Claudio; Di Rocco, Maja; Striano, Pasaquale; De Grandis, Eusa; Veneselli, Edvige; Rossi, Andrea; Biancheri, Roberta

    2015-04-01

    The diagnostic work up of neurometabolic/degenerative disorders is complex. In such context, identification of neuroradiological features suggestive of specific diagnoses is useful to prompt further diagnostic tests. Involvement of the inferior olivary nucleus (ION) has been reported in several pathologic conditions, either as a primary manifestation of disease or secondary to hypertrophic olivary degeneration (HOD). In this study, we analyzed a cohort of 95 children with different neurometabolic/degenerative diseases involving the brainstem and cerebellum, with the aim to evaluate whether ION involvement plays a role in a neuroimaging-based pattern-recognition approach. A total of 13 patients (13.7%) showed bilateral high-signal intensity and enlargement of the ION on T2-weighted images, while 16 (16.8%) had ION T2-hyperintensity without olivary nucleus enlargement. Our study demonstrates that ION involvement is not rare in children with neurometabolic/degenerative disorders. Two main neuroradiological patterns, that is, "T2-hyperintense signal" and "T2-hyperintense signal with enlargement" are found. These patterns can be related to different etiologies, and do not suggest specific diagnoses. Primary ION lesion can be characterized by olivary swelling, and the differentiation from typical secondary HOD may be difficult.

  16. Health Care Waste generation rates and patterns: The case of Lebanon.

    PubMed

    Maamari, Olivia; Brandam, Cedric; Lteif, Roger; Salameh, Dominique

    2015-09-01

    The objective of this study is to analyze Infectious Health Care Waste generation rates and patterns in Lebanon. Therefore, the quantities generated during five years by 57 hospitals from a total of 163 in the country have been analyzed. The seasonal evolution of Infectious Health Care Waste production and the evolution of the evaluation of the trends over years have been studied. Besides, the generation per capita have been estimated and compared to other countries. The variance between categories and the correlation between number of beds and Infectious Health Care Waste generation have been analyzed. The obtained results showed that the large private hospitals (over 200 beds) are characterized by their high generation rate: an average of 2.45kg per occupied bed(-1)day(-1), whereas the average generation rate for other categories is 0.94kg per occupied bed(-1)day(-1). The weighted mean is 1.14 per occupied kgbed(-1)day(-1). Small public hospitals (i.e. less than 100 beds) have the smallest standard deviation: 0.13, whereas large private hospitals (i.e. over than 200 beds) have the highest standard deviation: 0.40. Infectious Health Care Waste generation has been estimated to 1.42kg/capita/year. The correlation between the numbers of hospitals beds in hospitals and the generation rate per bed is weak. The correlation between Infectious Health Care Waste generation per day and beds number is stronger. The total quantity produced by hospitals has increased over the five past years. These results suggest that the quantities of medical waste are not well controlled, and that hospitals have a defective monitoring management system of their waste. Annual peaks are observed in June, July, and December. Thus, this study, for the first time in Lebanon, has provided information on the infectious waste generation, allowing benchmarking between hospitals and between countries.

  17. Lay Referral Patterns Involved in Cardiac Treatment Decision Making among Middle-Aged and Older Adults

    ERIC Educational Resources Information Center

    Schoenberg, Nancy E.; Amey, Cheryl H.; Stoller, Eleanor Palo; Muldoon, Susan B.

    2003-01-01

    Purpose: This study examined age and contextually related factors that are influential in lay referral patterns during cardiac treatment decision making. Design and Methods: A complementary design was used. The Myocardial Infarction (MI) Onset Study identified demographic correlates of who sought medical care for 1,388 MI (heart attack) survivors.…

  18. Direct observation of microcontact behaviours in pattern-generation step of reverse offset printing

    NASA Astrophysics Data System (ADS)

    Kusaka, Yasuyuki; Kanazawa, Shusuke; Yamamoto, Noritaka; Ushijima, Hirobumi

    2017-01-01

    In this study, we investigate the static and dynamic aspects of the nip formed during roll-to-sheet-type reverse offset printing. First, we show that several modes of roof collapses (bottom contact defects) could be formed depending on the poly(dimethylsiloxane) (PDMS) blanket thickness and pattern size. We regulate the manifestation of the defect modes driven by the local pile-up of the incompressible PDMS, as modelled by the contact mechanics formulation, together with a complementary numerical simulation. In dynamics, we first differentiate between the static nip and dynamic nip during printing, where the width is extended by the kinetically controlled adhesion of the blanket PDMS. Further, we observe that depending on the pattern structure, there was spatial deviation of the microscopic contact and subsequent separation behaviours of the cliché from a macroscopically recognizable nip, and consequently, local detachment rates were heterogeneous in the pattern-generation process of the reverse offset printing, even with a constant machine speed. In addition, we found that the parts of a pattern where the ink transfer fails in a high-speed patterning condition corresponded to the region of the locally enhanced detachment rates found during direct observation.

  19. NeuroPG: open source software for optical pattern generation and data acquisition

    PubMed Central

    Avants, Benjamin W.; Murphy, Daniel B.; Dapello, Joel A.; Robinson, Jacob T.

    2015-01-01

    Patterned illumination using a digital micromirror device (DMD) is a powerful tool for optogenetics. Compared to a scanning laser, DMDs are inexpensive and can easily create complex illumination patterns. Combining these complex spatiotemporal illumination patterns with optogenetics allows DMD-equipped microscopes to probe neural circuits by selectively manipulating the activity of many individual cells or many subcellular regions at the same time. To use DMDs to study neural activity, scientists must develop specialized software to coordinate optical stimulation patterns with the acquisition of electrophysiological and fluorescence data. To meet this growing need we have developed an open source optical pattern generation software for neuroscience—NeuroPG—that combines, DMD control, sample visualization, and data acquisition in one application. Built on a MATLAB platform, NeuroPG can also process, analyze, and visualize data. The software is designed specifically for the Mightex Polygon400; however, as an open source package, NeuroPG can be modified to incorporate any data acquisition, imaging, or illumination equipment that is compatible with MATLAB’s Data Acquisition and Image Acquisition toolboxes. PMID:25784873

  20. Generation, Language, Body Mass Index, and Activity Patterns in Hispanic Children

    PubMed Central

    Taverno, Sharon E.; Rollins, Brandi Y.; Francis, Lori A.

    2010-01-01

    Background The acculturation hypothesis proposes an overall disadvantage in health outcomes for Hispanic immigrants with more time spent living in the U.S., but little is known about how generational status and language may influence Hispanic children’s relative weight and activity patterns. Purpose The association between generation and language was investigated with relative weight (BMI z-scores), physical activity, screen time, and participation in extracurricular activities (e.g., sports, clubs) in a U.S.-based, nationally representative sample of Hispanic children. Methods Participants included 2,012 Hispanic children aged 6–11 years from the cross-sectional, 2003 National Survey of Children’s Health. Children were grouped according to generational status (1st, 2nd or 3rd), and the primary language spoken in the home (English vs non-English). Primary analyses included adjusted logistic and multinomial logistic regression to examine the relationships among variables; all analyses were conducted between 2008 and 2009. Results Compared to 3rd generation, English speakers, 1st and 2nd generation, non-English speakers were over two times more likely to be obese. Moreover, 1st generation, non-English speakers were half as likely to engage in regular physical activity and sports. Both 1st and 2nd generation, non-English speakers were less likely to participate in clubs compared to 2nd and 3rd generation, English speakers. Overall, all non–English speaking groups reported less screen time compared to 3rd generation, English speakers. Conclusions The hypothesis that Hispanics lose their health protection with more time spent in the U.S. was not supported in this sample of Hispanic children. PMID:20117570

  1. Implementation of a Data Packet Generator Using Pattern Matching for Wearable ECG Monitoring Systems

    PubMed Central

    Noh, Yun Hong; Jeong, Do Un

    2014-01-01

    In this paper, a packet generator using a pattern matching algorithm for real-time abnormal heartbeat detection is proposed. The packet generator creates a very small data packet which conveys sufficient crucial information for health condition analysis. The data packet envelopes real time ECG signals and transmits them to a smartphone via Bluetooth. An Android application was developed specifically to decode the packet and extract ECG information for health condition analysis. Several graphical presentations are displayed and shown on the smartphone. We evaluate the performance of abnormal heartbeat detection accuracy using the MIT/BIH Arrhythmia Database and real time experiments. The experimental result confirm our finding that abnormal heart beat detection is practically possible. We also performed data compression ratio and signal restoration performance evaluations to establish the usefulness of the proposed packet generator and the results were excellent. PMID:25029280

  2. Efficient second harmonic generation using nonlinear substrates patterned by nano-antenna arrays.

    PubMed

    Bar-Lev, Doron; Scheuer, Jacob

    2013-12-02

    We study theoretically various design considerations for efficient generation of second harmonic using a nonlinear substrate patterned with nano-antennas. The analysis is focused on a gap Bowtie nano-antenna array recessed in LiNbO₃ which is shown to be preferable over on surface structures due to field enhancement, field profile and linear and non-linear polarization considerations. In addition, we develop the nano-antenna counterpart of the Boyd-Klienmann model in order to analyze the impact of a Gaussian shaped fundamental beam on the generated second harmonic. Finally, we show that the dielectric properties of the substrate lead to preferable directions for the incident fundamental harmonic and the emission of the second harmonic. Our analyses lead to several design rules which can enhance second and high harmonic generation from nano-antennas arrays by several orders of magnitude.

  3. Preclinical evidence supporting the clinical development of central pattern generator-modulating therapies for chronic spinal cord-injured patients

    PubMed Central

    2014-01-01

    Ambulation or walking is one of the main gaits of locomotion. In terrestrial animals, it may be defined as a series of rhythmic and bilaterally coordinated movement of the limbs which creates a forward movement of the body. This applies regardless of the number of limbs—from arthropods with six or more limbs to bipedal primates. These fundamental similarities among species may explain why comparable neural systems and cellular properties have been found, thus far, to control in similar ways locomotor rhythm generation in most animal models. The aim of this article is to provide a comprehensive review of the known structural and functional features associated with central nervous system (CNS) networks that are involved in the control of ambulation and other stereotyped motor patterns—specifically Central Pattern Generators (CPGs) that produce basic rhythmic patterned outputs for locomotion, micturition, ejaculation, and defecation. Although there is compelling evidence of their existence in humans, CPGs have been most studied in reduced models including in vitro isolated preparations, genetically-engineered mice and spinal cord-transected animals. Compared with other structures of the CNS, the spinal cord is generally considered as being well-preserved phylogenetically. As such, most animal models of spinal cord-injured (SCI) should be considered as valuable tools for the development of novel pharmacological strategies aimed at modulating spinal activity and restoring corresponding functions in chronic SCI patients. PMID:24910602

  4. Differential effects of opioids on sacrocaudal afferent pathways and central pattern generators in the neonatal rat spinal cord.

    PubMed

    Blivis, D; Mentis, G Z; O'donovan, M J; Lev-Tov, A

    2007-04-01

    The effects of opioids on sacrocaudal afferent (SCA) pathways and the pattern-generating circuitry of the thoracolumbar and sacrocaudal segments of the spinal cord were studied in isolated spinal cord and brain stem-spinal cord preparations of the neonatal rat. The locomotor and tail moving rhythm produced by activation of nociceptive and nonnociceptive sacrocaudal afferents was completely blocked by specific application of the mu-opioid receptor agonist [d-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin acetate salt (DAMGO) to the sacrocaudal but not the thoracolumbar segments of the spinal cord. The rhythmic activity could be restored after addition of the opioid receptor antagonist naloxone to the experimental chamber. The opioid block of the SCA-induced rhythm is not due to impaired rhythmogenic capacity of the spinal cord because a robust rhythmic activity could be initiated in the thoracolumbar and sacrocaudal segments in the presence of DAMGO, either by stimulation of the ventromedial medulla or by bath application of N-methyl-d-aspartate/serotonin. We suggest that the opioid block of the SCA-induced rhythm involves suppression of synaptic transmission through sacrocaudal interneurons interposed between SCA and the pattern-generating circuitry. The expression of mu opioid receptors in several groups of dorsal, intermediate and ventral horn interneurons in the sacrocaudal segments of the cord, documented in this study, provides an anatomical basis for this suggestion.

  5. Legal approaches regarding health-care decisions involving minors: implications for next-generation sequencing

    PubMed Central

    Sénécal, Karine; Thys, Kristof; Vears, Danya F; Van Assche, Kristof; Knoppers, Bartha M; Borry, Pascal

    2016-01-01

    The development of next-generation sequencing (NGS) technologies are revolutionizing medical practice, facilitating more accurate, sophisticated and cost-effective genetic testing. NGS is already being implemented in the clinic assisting diagnosis and management of disorders with a strong heritable component. Although considerable attention has been paid to issues regarding return of incidental or secondary findings, matters of consent are less well explored. This is particularly important for the use of NGS in minors. Recent guidelines addressing genomic testing and screening of children and adolescents have suggested that as ‘young children' lack decision-making capacity, decisions about testing must be conducted by a surrogate, namely their parents. This prompts consideration of the age at which minors can provide lawful consent to health-care interventions, and consequently NGS performed for diagnostic purposes. Here, we describe the existing legal approaches regarding the rights of minors to consent to health-care interventions, including how laws in the 28 Member States of the European Union and in Canada consider competent minors, and then apply this to the context of NGS. There is considerable variation in the rights afforded to minors across countries. Many legal systems determine that minors would be allowed, or may even be required, to make decisions about interventions such as NGS. However, minors are often considered as one single homogeneous population who always require parental consent, rather than recognizing there are different categories of ‘minors' and that capacity to consent or to be involved in discussions and decision-making process is a spectrum rather than a hurdle. PMID:27302841

  6. Cancer Therapy by Catechins Involves Redox Cycling of Copper Ions and Generation of Reactive Oxygen species.

    PubMed

    Farhan, Mohd; Khan, Husain Yar; Oves, Mohammad; Al-Harrasi, Ahmed; Rehmani, Nida; Arif, Hussain; Hadi, Sheikh Mumtaz; Ahmad, Aamir

    2016-02-04

    Catechins, the dietary phytochemicals present in green tea and other beverages, are considered to be potent inducers of apoptosis and cytotoxicity to cancer cells. While it is believed that the antioxidant properties of catechins and related dietary agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, these properties cannot account for apoptosis induction and chemotherapeutic observations. Catechin (C), epicatechin (EC), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) are the four major constituents of green tea. In this article, using human peripheral lymphocytes and comet assay, we show that C, EC, EGC and EGCG cause cellular DNA breakage and can alternatively switch to a prooxidant action in the presence of transition metals such as copper. The cellular DNA breakage was found to be significantly enhanced in the presence of copper ions. Catechins were found to be effective in providing protection against oxidative stress induced by tertbutylhydroperoxide, as measured by oxidative DNA breakage in lymphocytes. The prooxidant action of catechins involved production of hydroxyl radicals through redox recycling of copper ions. We also determined that catechins, particularly EGCG, inhibit proliferation of breast cancer cell line MDA-MB-231 leading to a prooxidant cell death. Since it is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies, cancer cells would be more subject to redox cycling between copper ions and catechins to generate reactive oxygen species (ROS) responsible for DNA breakage. Such a copper dependent prooxidant cytotoxic mechanism better explains the anticancer activity and preferential cytotoxicity of dietary phytochemicals against cancer cells.

  7. Cancer Therapy by Catechins Involves Redox Cycling of Copper Ions and Generation of Reactive Oxygen Species

    PubMed Central

    Farhan, Mohd; Khan, Husain Yar; Oves, Mohammad; Al-Harrasi, Ahmed; Rehmani, Nida; Arif, Hussain; Hadi, Sheikh Mumtaz; Ahmad, Aamir

    2016-01-01

    Catechins, the dietary phytochemicals present in green tea and other beverages, are considered to be potent inducers of apoptosis and cytotoxicity to cancer cells. While it is believed that the antioxidant properties of catechins and related dietary agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, these properties cannot account for apoptosis induction and chemotherapeutic observations. Catechin (C), epicatechin (EC), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) are the four major constituents of green tea. In this article, using human peripheral lymphocytes and comet assay, we show that C, EC, EGC and EGCG cause cellular DNA breakage and can alternatively switch to a prooxidant action in the presence of transition metals such as copper. The cellular DNA breakage was found to be significantly enhanced in the presence of copper ions. Catechins were found to be effective in providing protection against oxidative stress induced by tertbutylhydroperoxide, as measured by oxidative DNA breakage in lymphocytes. The prooxidant action of catechins involved production of hydroxyl radicals through redox recycling of copper ions. We also determined that catechins, particularly EGCG, inhibit proliferation of breast cancer cell line MDA-MB-231 leading to a prooxidant cell death. Since it is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies, cancer cells would be more subject to redox cycling between copper ions and catechins to generate reactive oxygen species (ROS) responsible for DNA breakage. Such a copper dependent prooxidant cytotoxic mechanism better explains the anticancer activity and preferential cytotoxicity of dietary phytochemicals against cancer cells. PMID:26861392

  8. An approach toward an analysis of the pattern recognition involved in the stellar orientation of birds

    NASA Technical Reports Server (NTRS)

    Wallraff, H. G.

    1972-01-01

    A conditioning method was used to investigate the orientational responses of ducks as affected by manipulations of the stellar patterns in a planetarium. Under simulated natural skies it was possible to train a bird to a particular direction successively under all positions of the rotating sphere at a constant latitude. The responses were independent of the phase relationships between local time, season, and appearance of the sky provided the bird had been trained under the particular sector of the sphere some time before.

  9. Officer-involved shooting: reaction patterns, response protocols, and psychological intervention strategies.

    PubMed

    Miller, Laurence

    2006-01-01

    Psychologists who work with law enforcement agencies may be called upon to respond to an officer-involved shooting (OIS). These need not be the most traumatic critical incidents in policing, but when they are, the reasons usually involve a mix of incident characteristics, officer response styles, and departmental handling. This article describes some of the psychological reactions experienced by officers during and following an OIS and provides a model of administrative, legal, mental health, and peer support services for officers in need. Finally, the article discusses several key roles that the police psychologist can play in the process of managing an OIS.

  10. Involvement of Hedgehog and FGF signalling in the lamprey telencephalon: evolution of regionalization and dorsoventral patterning of the vertebrate forebrain.

    PubMed

    Sugahara, Fumiaki; Aota, Shin-ichi; Kuraku, Shigehiro; Murakami, Yasunori; Takio-Ogawa, Yoko; Hirano, Shigeki; Kuratani, Shigeru

    2011-03-01

    Dorsoventral (DV) specification is a crucial step for the development of the vertebrate telencephalon. Clarifying the origin of this mechanism will lead to a better understanding of vertebrate central nervous system (CNS) evolution. Based on the lamprey, a sister group of the gnathostomes (jawed vertebrates), we identified three lamprey Hedgehog (Hh) homologues, which are thought to play central signalling roles in telencephalon patterning. However, unlike in gnathostomes, none of these genes, nor Lhx6/7/8, a marker for the migrating interneuron subtype, was expressed in the ventral telencephalon, consistent with the reported absence of the medial ganglionic eminence (MGE) in this animal. Homologues of Gsh2, Isl1/2 and Sp8, which are involved in the patterning of the lateral ganglionic eminence (LGE) of gnathostomes, were expressed in the lamprey subpallium, as in gnathostomes. Hh signalling is necessary for induction of the subpallium identity in the gnathostome telencephalon. When Hh signalling was inhibited, the ventral identity was disrupted in the lamprey, suggesting that prechordal mesoderm-derived Hh signalling might be involved in the DV patterning of the telencephalon. By blocking fibroblast growth factor (FGF) signalling, the ventral telencephalon was suppressed in the lamprey, as in gnathostomes. We conclude that Hh- and FGF-dependent DV patterning, together with the resultant LGE identity, are likely to have been established in a common ancestor before the divergence of cyclostomes and gnathostomes. Later, gnathostomes would have acquired a novel Hh expression domain corresponding to the MGE, leading to the obtainment of cortical interneurons.

  11. "Simply the Best for My Children": Patterns of Parental Involvement in Education

    ERIC Educational Resources Information Center

    Ule, Mirjana; Živoder, Andreja; du Bois-Reymond, Manuela

    2015-01-01

    This article explores parental involvement in the educational trajectories of children in Europe. The analysis is embedded in the framework of the three dominant contemporary social processes that have been acknowledged as crucial factors for the educational and life trajectories of young people today, i.e. familialization, institutionalization,…

  12. Changing Patterns of Parent-Teacher Communication and Parent Involvement from Preschool to School

    ERIC Educational Resources Information Center

    Murray, Elizabeth; McFarland-Piazza, Laura; Harrison, Linda J.

    2015-01-01

    PreschoolThis study investigated the nature of parent involvement and parent-educator communication in prior-to-school early childhood settings and school, to explore relations to social capital variables and consistencies and changes in practices over time. Parent interview and teacher questionnaire data from two waves of the Longitudinal Study…

  13. Gas generation and migration studies involving recently generated /sup 238/Pu-contaminated waste for the TRU Waste Sampling Program

    SciTech Connect

    Zerwekh, A.; Warren, J.L.

    1986-07-01

    This study is part of the multicontractor TRU Waste Sampling Program. Radiolytically generated gases were vented through a filtering device to determine its effectiveness in maintaining hydrogen concentrations within acceptably safe levels. In the second part of the study measurements were made to determine the ability of these gases, particularly hydrogen, to migrate through a sealed rigid polyethylene drum liner. Void volumes in these drums were found to be generally in excess of 90%. The carbon composite filter was found to satisfactorily vent hydrogen up to moderately high levels of alpha activity in the waste substrate. The sealed 90-mil liner was found to inhibit, but not prevent, the migration of hydrogen and other radiolytically generated gases.

  14. Toward robust phase-locking in Melibe swim central pattern generator models

    NASA Astrophysics Data System (ADS)

    Jalil, Sajiya; Allen, Dane; Youker, Joseph; Shilnikov, Andrey

    2013-12-01

    Small groups of interneurons, abbreviated by CPG for central pattern generators, are arranged into neural networks to generate a variety of core bursting rhythms with specific phase-locked states, on distinct time scales, which govern vital motor behaviors in invertebrates such as chewing and swimming. These movements in lower level animals mimic motions of organs in higher animals due to evolutionarily conserved mechanisms. Hence, various neurological diseases can be linked to abnormal movement of body parts that are regulated by a malfunctioning CPG. In this paper, we, being inspired by recent experimental studies of neuronal activity patterns recorded from a swimming motion CPG of the sea slug Melibe leonina, examine a mathematical model of a 4-cell network that can plausibly and stably underlie the observed bursting rhythm. We develop a dynamical systems framework for explaining the existence and robustness of phase-locked states in activity patterns produced by the modeled CPGs. The proposed tools can be used for identifying core components for other CPG networks with reliable bursting outcomes and specific phase relationships between the interneurons. Our findings can be employed for identifying or implementing the conditions for normal and pathological functioning of basic CPGs of animals and artificially intelligent prosthetics that can regulate various movements.

  15. Central generation of grooming motor patterns and interlimb coordination in locusts.

    PubMed

    Berkowitz, A; Laurent, G

    1996-12-15

    Coordinated bursts of leg motoneuron activity were evoked in locusts with deefferented legs by tactile stimulation of sites that evoke grooming behavior. This suggests that insect thoracic ganglia contain central pattern generators for directed leg movements. Motoneuron recordings were made from metathoracic and mesothoracic nerves, after eliminating all leg motor innervation, as well as all input from the brain, subesophageal ganglion, and prothoracic ganglion. Strong, brief trochanteral levator motoneuron bursts occurred, together with silence of the slow and fast trochanteral depressor motoneurons and activation of the common inhibitor motoneuron. The metathoracic slow tibial extensor motoneuron was active in a pattern distinct from its activity during walking or during rhythms evoked by the muscarinic agonist pilocarpine. Preparations in which the metathoracic ganglion was isolated from all other ganglia could still produce fictive motor patterns in response to tactile stimulation of metathoracic locations. Bursts of trochanteral levator and depressor motoneurons were clearly coordinated between the left and right metathoracic hemiganglia and also between the mesothoracic and the ipsilateral metathoracic ganglia. These data provide clear evidence for centrally generated interlimb coordination in an insect.

  16. Toward robust phase-locking in Melibe swim central pattern generator models.

    PubMed

    Jalil, Sajiya; Allen, Dane; Youker, Joseph; Shilnikov, Andrey

    2013-12-01

    Small groups of interneurons, abbreviated by CPG for central pattern generators, are arranged into neural networks to generate a variety of core bursting rhythms with specific phase-locked states, on distinct time scales, which govern vital motor behaviors in invertebrates such as chewing and swimming. These movements in lower level animals mimic motions of organs in higher animals due to evolutionarily conserved mechanisms. Hence, various neurological diseases can be linked to abnormal movement of body parts that are regulated by a malfunctioning CPG. In this paper, we, being inspired by recent experimental studies of neuronal activity patterns recorded from a swimming motion CPG of the sea slug Melibe leonina, examine a mathematical model of a 4-cell network that can plausibly and stably underlie the observed bursting rhythm. We develop a dynamical systems framework for explaining the existence and robustness of phase-locked states in activity patterns produced by the modeled CPGs. The proposed tools can be used for identifying core components for other CPG networks with reliable bursting outcomes and specific phase relationships between the interneurons. Our findings can be employed for identifying or implementing the conditions for normal and pathological functioning of basic CPGs of animals and artificially intelligent prosthetics that can regulate various movements.

  17. Cytoskeletal stability and heat shock-mediated thermoprotection of central pattern generation in Locusta migratoria.

    PubMed

    Garlick, Kristopher M; Robertson, R Meldrum

    2007-06-01

    Prior exposure to extreme temperatures can induce thermoprotection in migratory locusts, which is important for survival in their natural environment. An important motor activity that needs to be protected is ventilation. The mechanism underlying heat shock is not fully understood, and our goal was to test the idea that cytoskeletal stability is critical for such thermoprotection. Cytoskeletal stabilizers (concanavalin A) and destabilizers (colchicine) were bath-applied in semi-intact locust preparations in both control (C) and pre-treated heat-shocked (3 h, 45 degrees C) animals. We measured parameters of the ventilatory motor pattern during maintained high temperature (43 degrees C) and recorded the times taken for motor pattern generation to fail and then recover on returning to room temperature. We found that concanavalin A mimicked the effects of a prior heat stress in control animals by increasing time to failure and decreasing time to recovery of motor pattern generation. However, colchicine destroyed protection in heat-shocked animals by decreasing time to failure and increasing time to recovery. Our findings confirm that the cytoskeleton has a mechanistic role in preserving neural function at high temperatures, possibly through stabilizing ion channels and other integral membrane proteins (e.g. Na(+)/K(+) ATPase) and their interactions with heat shock proteins.

  18. Frequency spectrum of focused broadband pulses of electromagnetic radiation generated by polarization currents with superluminally rotating distribution patterns.

    PubMed

    Ardavan, Houshang; Ardavan, Arzhang; Singleton, John

    2003-11-01

    We investigate the spectral features of the emission from a superluminal polarization current whose distribution pattern rotates (with an angular frequency omega) and oscillates (with a frequency omega > omega differing from an integral multiple of omega) at the same time. This type of polarization current is found in recent practical machines designed to investigate superluminal emission. Although all of the processes involved are linear, we find that the broadband emission contains frequencies that are higher than omega by a factor of the order of (omega/omega)2. This generation of frequencies not required for the creation of the source stems from mathematically rigorous consequences of the familiar classical expression for the retarded potential. The results suggest practical applications for superluminal polarization currents as broadband radio-frequency and infrared sources.

  19. Asymmetry Factors Shaping Regular and Irregular Bursting Rhythms in Central Pattern Generators

    PubMed Central

    Elices, Irene; Varona, Pablo

    2017-01-01

    Central Pattern Generator (CPG) circuits are neural networks that generate rhythmic motor patterns. These circuits are typically built of half-center oscillator subcircuits with reciprocally inhibitory connections. Another common property in many CPGs is the remarkable rich spiking-bursting dynamics of their constituent cells, which balance robustness and flexibility to generate their joint coordinated rhythms. In this paper, we use conductance-based models and realistic connection topologies inspired by the crustacean pyloric CPG to address the study of asymmetry factors shaping CPG bursting rhythms. In particular, we assess the role of asymmetric maximal synaptic conductances, time constants and gap-junction connectivity to establish the regularity of half-center oscillator based CPGs. We map and characterize the synaptic parameter space that lead to regular and irregular bursting activity in these networks. The analysis indicates that asymmetric configurations display robust regular rhythms and that large regions of both regular and irregular but coordinated rhythms exist as a function of the asymmetry in the circuit. Our results show that asymmetry both in the maximal conductances and in the temporal dynamics of mutually inhibitory neurons can synergistically contribute to shape wide regimes of regular spiking-bursting activity in CPGs. Finally, we discuss how a closed-loop protocol driven by a regularity goal can be used to find and characterize regular regimes when there is not time to perform an exhaustive search, as in most experimental studies. PMID:28261081

  20. Implementation of Imitation Learning using Natural Learner Central Pattern Generator Neural Networks.

    PubMed

    Shahbazi, Hamed; Parandeh, Reyhaneh; Jamshidi, Kamal

    2016-11-01

    In this paper a new design of neural networks is introduced, which is able to generate oscillatory patterns. The fundamental building block of the neural network is O-neurons that can generate an oscillation in its transfer functions. Since the natural policy gradient learning has been used in training a central pattern generator paradigm, it is called Natural Learner CPG Neural Networks (NLCPGNN). O-neurons are connected and coupled to each other in order to shape a network and their unknown parameters are found by a natural policy gradient learning algorithm. The main contribution of this paper is design of this learning algorithm which is able to simultaneously search for the weights and topology of the network. This system is capable to obtain any complex motion and rhythmic trajectory via first layer and learn rhythmic trajectories in the second layer and converge towards all these movements. Moreover this two layers system is able to provide various features of a learner model for instance resistance against perturbations, modulation of trajectories amplitude and frequency. Simulation of the learning system in the robot simulator (WEBOTS) that is linked with MATLAB software has been done. Implementation on a real NAO robot demonstrates that the robot has learned desired motion with high accuracy. These results show proposed system produces high convergence rate and low test errors.

  1. [Central Pattern Generators: Mechanisms of the Activity and Their Role in the Control of "Automatic" Movements].

    PubMed

    Arshavsky, I; Deliagina, T G; Orlovsky, G N

    2015-01-01

    Central pattern generators (CPGs) are a set of interconnected neurons capable of generating a basic pattern of motor output underlying "automatic" movements (breathing, locomotion, chewing, swallowing, and so on) in the absence of afferent signals from the executive motor apparatus. They can be divided into the constitutive CPGs active throughout the entire lifetime (respiratory CPGs) and conditional CPGs controlling episodic movements (locomotion, chewing, swallowing, and others). Since a motor output of CPGs is determined by their internal organization, the activities of the conditional CPGs are initiated by simple commands coming from higher centers. We describe the structural and functional organization of the locomotor CPGs in the marine mollusk Clione limacina, lamprey, frog embryo, and laboratory mammals (cat, mouse, and rat), CPGs controlling the respiratory and swallowing movements in mammals, and CPGs controlling discharges of the electric organ in the gymnotiform fish. It is shown that in all these cases, the generation of rhythmic motor output is based both on the endogenous (pacemaker) activity of specific groups of interneurons and on interneural interactions. These two interrelated mechanisms complement each other, ensuring the high reliability of CPG functionality. We discuss how the experience obtained in studying CPGs can be used to understand mechanisms of more complex functions of the brain, including its cognitive functions.

  2. Asymmetry Factors Shaping Regular and Irregular Bursting Rhythms in Central Pattern Generators.

    PubMed

    Elices, Irene; Varona, Pablo

    2017-01-01

    Central Pattern Generator (CPG) circuits are neural networks that generate rhythmic motor patterns. These circuits are typically built of half-center oscillator subcircuits with reciprocally inhibitory connections. Another common property in many CPGs is the remarkable rich spiking-bursting dynamics of their constituent cells, which balance robustness and flexibility to generate their joint coordinated rhythms. In this paper, we use conductance-based models and realistic connection topologies inspired by the crustacean pyloric CPG to address the study of asymmetry factors shaping CPG bursting rhythms. In particular, we assess the role of asymmetric maximal synaptic conductances, time constants and gap-junction connectivity to establish the regularity of half-center oscillator based CPGs. We map and characterize the synaptic parameter space that lead to regular and irregular bursting activity in these networks. The analysis indicates that asymmetric configurations display robust regular rhythms and that large regions of both regular and irregular but coordinated rhythms exist as a function of the asymmetry in the circuit. Our results show that asymmetry both in the maximal conductances and in the temporal dynamics of mutually inhibitory neurons can synergistically contribute to shape wide regimes of regular spiking-bursting activity in CPGs. Finally, we discuss how a closed-loop protocol driven by a regularity goal can be used to find and characterize regular regimes when there is not time to perform an exhaustive search, as in most experimental studies.

  3. Convergence of pattern generator outputs on a common mechanism of diaphragm motor unit recruitment

    PubMed Central

    Mantilla, Carlos B.; Seven, Yasin B.; Sieck, Gary C.

    2014-01-01

    Motor units are the final element of neuromotor control. In manner analogous to the organization of neuromotor control in other skeletal muscles, diaphragm motor units comprise phrenic motoneurons located in the cervical spinal cord that innervate the diaphragm muscle, the main inspiratory muscle in mammals. Diaphragm motor units play a primary role in sustaining ventilation, but are also active in other non-ventilatory behaviors, including coughing, sneezing, vomiting, defecation and parturition. Diaphragm muscle fibers comprise all fiber types. Thus, diaphragm motor units display substantial differences in contractile and fatigue properties, but importantly properties of the motoneuron and muscle fibers within a motor unit are matched. As in other skeletal muscles, diaphragm motor units are recruited in order such that motor units that display greater fatigue resistance are recruited earlier and more often than more fatigable motor units. The properties of the motor unit population are critical determinants of the function of a skeletal muscle across the range of possible motor tasks. Accordingly, fatigue-resistant motor units are sufficient to generate the forces necessary for ventilatory behaviors whereas more fatigable units are only activated during expulsive behaviors important for airway clearance. Neuromotor control of diaphragm motor units may reflect selective inputs from distinct pattern generators distributed according to the motor unit properties necessary to accomplish these different motor tasks. In contrast, widely-distributed inputs to phrenic motoneurons from various pattern generators (e.g., for breathing, coughing or vocalization) would dictate recruitment order based on intrinsic electrophysiological properties. PMID:24746055

  4. Stress-induced thermotolerance of ventilatory motor pattern generation in the locust, Locusta migratoria.

    PubMed

    Newman, Amy E M; Foerster, Melody; Shoemaker, Kelly L; Robertson, R Meldrum

    2003-11-01

    Ventilation is a crucial motor activity that provides organisms with an adequate circulation of respiratory gases. For animals that exist in harsh environments, an important goal is to protect ventilation under extreme conditions. Heat shock, anoxia, and cold shock are environmental stresses that have previously been shown to trigger protective responses. We used the locust to examine stress-induced thermotolerance by monitoring the ability of the central nervous system to generate ventilatory motor patterns during a subsequent heat exposure. Preparations from pre-stressed animals had an increased incidence of motor pattern recovery following heat-induced failure, however, prior stress did not alter the characteristics of the ventilatory motor pattern. During constant heat exposure at sub-lethal temperatures, we observed a protective effect of heat shock pre-treatment. Serotonin application had similar effects on motor patterns when compared to prior heat shock. These studies are consistent with previous studies that indicate prior exposure to extreme temperatures and hypoxia can protect neural operation against high temperature stress. They further suggest that the protective mechanism is a time-dependent process best revealed during prolonged exposure to extreme temperatures and is mediated by a neuromodulator such as serotonin.

  5. Drosophila TIEG Is a Modulator of Different Signalling Pathways Involved in Wing Patterning and Cell Proliferation

    PubMed Central

    Rodriguez, Isabel

    2011-01-01

    Acquisition of a final shape and size during organ development requires a regulated program of growth and patterning controlled by a complex genetic network of signalling molecules that must be coordinated to provide positional information to each cell within the corresponding organ or tissue. The mechanism by which all these signals are coordinated to yield a final response is not well understood. Here, I have characterized the Drosophila ortholog of the human TGF-β Inducible Early Gene 1 (dTIEG). TIEG are zinc-finger proteins that belong to the Krüppel-like factor (KLF) family and were initially identified in human osteoblasts and pancreatic tumor cells for the ability to enhance TGF-β response. Using the developing wing of Drosophila as “in vivo” model, the dTIEG function has been studied in the control of cell proliferation and patterning. These results show that dTIEG can modulate Dpp signalling. Furthermore, dTIEG also regulates the activity of JAK/STAT pathway suggesting a conserved role of TIEG proteins as positive regulators of TGF-β signalling and as mediators of the crosstalk between signalling pathways acting in a same cellular context. PMID:21494610

  6. Depth and Patterns of Adnexal Involvement in Primary Extramammary (Anogenital) Paget Disease: A Study of 178 Lesions From 146 Patients.

    PubMed

    Konstantinova, Anastasia M; Shelekhova, Ksenya V; Stewart, Colin J; Spagnolo, Dominic V; Kutzner, Heinz; Kacerovska, Denisa; Plaza, Jose A; Suster, Saul; Bouda, Jiri; Pavlovsky, Michal; Kyrpychova, Liubov; Michal, Michal; Guenova, Emmanuella; Kazakov, Dmitry V

    2016-11-01

    Extramammary Paget disease (EMPD) is a rare neoplasm usually presenting in the anogenital area, most commonly in the vulva. Adnexal involvement in primary EMPD is a very common feature and serves as a pathway for carcinoma to spread into deeper tissue. The depth of carcinomatous spread along the appendages and the patterns of adnexal involvement were studied in 178 lesions from 146 patients with primary EMPD. Hair follicles and eccrine ducts were the adnexa most commonly affected by carcinoma cells. The maximal depth of involvement was 3.6 mm in this series. When planning topical therapy or developing novel local treatment modalities for EMPD, this potential for significant deep spread along adnexa should be taken into account.

  7. What Social Bonds have the Greatest Influence on Patterns of Substance Use among Child-Welfare-Involved Youth?

    PubMed

    Snyder, Susan M; Gwaltney, Angela You; Landeck, Emily

    2015-01-01

    Child-welfare-involved youth may lack protective social bonds that could reduce their risk of substance use. We investigated whether caregiver, school, or peer bonds predict distinct patterns of substance use among child-welfare-involved youth. The sample included 720 participants in the National Survey of Child and Adolescent Well-Being II. Latent class analysis (LCA) and the three-step approach to incorporate indicator variables onto the latent classes were used. We found the following classes: (1) severe polysubstance use; (2) moderate polysubstance use; and (3) low use. Youth bonded to primary caregivers were less likely to be severe polysubstance drug users, but caregiver bonds did not protect against moderate polysubstance use. School bonds protected against severe polysubstance and moderate polysubstance. Youth bonded to deviant peers were more likely to be in the severe polysubstance use and moderate polysubstance use classes. Interventions targeting child-welfare-involved youth need to account for social bonds' effect on substance use.

  8. Neuropeptide modulation of pattern-generating systems in crustaceans: comparative studies and approaches.

    PubMed

    Dickinson, Patsy S; Qu, Xuan; Stanhope, Meredith E

    2016-12-01

    Central pattern generators are subject to modulation by peptides, allowing for flexibility in patterned output. Current techniques used to characterize peptides include mass spectrometry and transcriptomics. In recent years, hundreds of neuropeptides have been sequenced from crustaceans; mass spectrometry has been used to identify peptides and to determine their levels and locations, setting the stage for comparative studies investigating the physiological roles of peptides. Such studies suggest that there is some evolutionary conservation of function, but also divergence of function even within a species. With current baseline data, it should be possible to begin using comparative approaches to ask fundamental questions about why peptides are encoded the way that they are and how this affects nervous system function.

  9. Generation of Crystal-Structure Transverse Patterns via a Self-Frequency-Doubling Laser

    NASA Astrophysics Data System (ADS)

    Yu, Haohai; Zhang, Huaijin; Wang, Yicheng; Wang, Zhengping; Wang, Jiyang; Petrov, V.

    2013-01-01

    Two-dimensional (2D) visible crystal-structure patterns analogous to the quantum harmonic oscillator (QHO) have been experimentally observed in the near- and far-fields of a self-frequency-doubling (SFD) microchip laser. Different with the fundamental modes, the localization of the SFD light is changed with the propagation. Calculation based on Hermite-Gaussian (HG) functions and second harmonic generation theory reproduces well the patterns both in the near- and far-field which correspond to the intensity distribution in coordinate and momentum spaces, respectively. Considering the analogy of wave functions of the transverse HG mode and 2D harmonic oscillator, we propose that the simple monolithic SFD lasers can be used for developing of new materials and devices and testing 2D quantum mechanical theories.

  10. Coupled chaotic oscillators and their relation to a central pattern generator for artificial quadrupeds

    NASA Astrophysics Data System (ADS)

    Castellini, Horacio; Yudiarsah, Efta; Romanelli, Lilia; Cerdeira, Hilda A.

    2005-04-01

    Animal locomotion employs different periodic patterns known as animal gaits. In 1993, Collins and Stewart recognized that gaits possessed certain symmetries and characterized the gaits of quadrupeds and bipeds using permutation symmetry groups, which impose constraints on the locomotion center called the central pattern generator (CPG) in the animal brain. They modeled the CPG by coupling four nonlinear oscillators and found that it was possible to reproduce all symmetries of the gaits by changing the coupling strength. Here we propose to extend this idea using coupled chaotic oscillators synchronized using the Pyragas method in order to characterize the CPG symmetries. We also evaluate the time series behavior when the foot is in contact with the ground: this has potential robotic applications.

  11. [Genetic determinants of generating the motor pattern of rhythmic movements in Drosophila melanogaster].

    PubMed

    Fedotov, S A; Bragina, Iu V; Besedina, N G; Danilenkova, L V; Kamysheva, E A; Kamyshev, N G

    2013-01-01

    To investigate molecular and cellular mechanisms of central pattern generators (CPG) functioning, we previously selected candidate genes mutations of which are accompanied with deviations in Drosophila melanogaster motor activity. In this research we tested locomotor parameters in lines with post transcriptional silencing of 12 candidate gene in Drosophila central nervous system. Silencing was provided by synthesis of interfering RNA by means of GAL4/UAS system under control of CNS-specific gene promoters (elav, nrv2, appl, tsh). It was found that RNA interference of most genes are accompanied with changes in one or several locomotor parameters. Pattern of revealed deviations under control of different promotors makes it possible to determine the genes that activity in nervous system is necessary for proper functioning of locomotor CPG.

  12. Models of central pattern generators for quadruped locomotion. II. Secondary gaits.

    PubMed

    Buono, P L

    2001-04-01

    We continue the analysis of the network of symmetrically coupled cells modeling central pattern generators (CPG) for quadruped locomotion proposed by Golubitsky, Stewart, Buono and Collins by studying secondary gaits. Secondary gaits are modeled by output signals from the CPG where each cell emits one of two different output signals along with exact phase shifts. Examples of secondary gaits are transverse gallop, rotary gallop, and canter. We classify secondary gaits that bifurcate when the Poincaré map of a primary gait has a real eigenvalue crossing the unit circle. In particular, we show that periodic solutions modeling transverse gallop and rotary gallop bifurcate from primary gaits. Moreover, we find gaits from period-doubling bifurcations and analyze plausible footfall patterns. Numerical simulations are performed using the Morris-Lecar equations as cell dynamics.

  13. Generation of crystal-structure transverse patterns via a self-frequency-doubling laser.

    PubMed

    Yu, Haohai; Zhang, Huaijin; Wang, Yicheng; Wang, Zhengping; Wang, Jiyang; Petrov, V

    2013-01-01

    Two-dimensional (2D) visible crystal-structure patterns analogous to the quantum harmonic oscillator (QHO) have been experimentally observed in the near- and far-fields of a self-frequency-doubling (SFD) microchip laser. Different with the fundamental modes, the localization of the SFD light is changed with the propagation. Calculation based on Hermite-Gaussian (HG) functions and second harmonic generation theory reproduces well the patterns both in the near- and far-field which correspond to the intensity distribution in coordinate and momentum spaces, respectively. Considering the analogy of wave functions of the transverse HG mode and 2D harmonic oscillator, we propose that the simple monolithic SFD lasers can be used for developing of new materials and devices and testing 2D quantum mechanical theories.

  14. Multiplexed recording with uncorrelated computer-generated reference patterns in coaxial holographic data storage.

    PubMed

    Nobukawa, Teruyoshi; Wani, Yotaro; Nomura, Takanori

    2015-05-15

    A computer-generated reference pattern (CGRP) allows improvement in light efficiency and the quality of reconstructed data in coaxial holographic data storage. In this Letter, a multiplexed recording method with uncorrelated CGRPs is proposed. With this method, crosstalk from adjacent holograms is suppressed without shifting a medium. To confirm the feasibility of the proposed method experimentally, shift selectivity is investigated, and then multiplexed recording is performed. Experimental results show that the proposed method enables high-density recording compared with conventional shift multiplexing. In addition, a theoretical analysis implies that at least 100 uncorrelated CGRPs can be designed and used for multiplexed recording.

  15. Evolution and development of a central pattern generator for the swimming of a lamprey.

    PubMed

    Ijspeert, A J; Kodjabachian, J

    1999-01-01

    This article describes the design of neural control architectures for locomotion using an evolutionary approach. Inspired by the central pattern generators found in animals, we develop neural controllers that can produce the patterns of oscillations necessary for the swimming of a simulated lamprey. This work is inspired by Ekeberg's neuronal and mechanical model of a lamprey [11] and follows experiments in which swimming controllers were evolved using a simple encoding scheme [25, 26]. Here, controllers are developed using an evolutionary algorithm based on the SGOCE encoding [31, 32] in which a genetic programming approach is used to evolve developmental programs that encode the growing of a dynamical neural network. The developmental programs determine how neurons located on a two-dimensional substrate produce new cells through cellular division and how they form efferent or afferent interconnections. Swimming controllers are generated when the growing networks eventually create connections to the muscles located on both sides of the rectangular substrate. These muscles are part of a two-dimensional mechanical simulation of the body of the lamprey in interaction with water. The motivation of this article is to develop a method for the design of control mechanisms for animal-like locomotion. Such a locomotion is characterized by a large number of actuators, a rhythmic activity, and the fact that efficient motion is only obtained when the actuators are well coordinated. The task of the control mechanism is therefore to transform commands concerning the speed and direction of motion into the signals sent to the multiple actuators. We define a fitness function, based on several simulations of the controller with different commands settings, that rewards the capacity of modulating the speed and the direction of swimming in response to simple, varying input signals. Central pattern generators are thus evolved capable of producing the relatively complex patterns of

  16. Closing the Loop: Integrating Body, Muscle and Environment with Locomotion Central Pattern Generators

    DTIC Science & Technology

    2013-06-30

    optimal feedback control, central pattern generator, lamprey , locomotion, neural control Tim Kiemel, Kathleen Hoffman University of Maryland - College Park...between the neural circuitry, body, and fluid environment for swimming locomotion, where the lamprey serves as a model system1,2,3,4,5,6,7,8. Our...have done for a simple plant model of lamprey swimming (§2.2). In our CPG-based approach (§2.3), we have combined a simple CPG model with the plant model

  17. Connection and coordination: the interplay between architecture and dynamics in evolved model pattern generators.

    PubMed

    Psujek, Sean; Ames, Jeffrey; Beer, Randall D

    2006-03-01

    We undertake a systematic study of the role of neural architecture in shaping the dynamics of evolved model pattern generators for a walking task. First, we consider the minimum number of connections necessary to achieve high performance on this task. Next, we identify architectural motifs associated with high fitness. We then examine how high-fitness architectures differ in their ability to evolve. Finally, we demonstrate the existence of distinct parameter subgroups in some architectures and show that these subgroups are characterized by differences in neuron excitabilities and connection signs.

  18. Control of oscillation periods and phase durations in half-center central pattern generators: a comparative mechanistic analysis.

    PubMed

    Daun, Silvia; Rubin, Jonathan E; Rybak, Ilya A

    2009-08-01

    Central pattern generators (CPGs) consisting of interacting groups of neurons drive a variety of repetitive, rhythmic behaviors in invertebrates and vertebrates, such as arise in locomotion, respiration, mastication, scratching, and so on. These CPGs are able to generate rhythmic activity in the absence of afferent feedback or rhythmic inputs. However, functionally relevant CPGs must adaptively respond to changing demands, manifested as changes in oscillation period or in relative phase durations in response to variations in non-patterned inputs or drives. Although many half-center CPG models, composed of symmetric units linked by reciprocal inhibition yet varying in their intrinsic cellular properties, have been proposed, the precise oscillatory mechanisms operating in most biological CPGs remain unknown. Using numerical simulations and phase-plane analysis, we comparatively investigated how the intrinsic cellular features incorporated in different CPG models, such as subthreshold activation based on a slowly inactivating persistent sodium current, adaptation based on slowly activating calcium-dependent potassium current, or post-inhibitory rebound excitation, can contribute to the control of oscillation period and phase durations in response to changes in excitatory external drive to one or both half-centers. Our analysis shows that both the sensitivity of oscillation period to alterations of excitatory drive and the degree to which the duration of each phase can be separately controlled depend strongly on the intrinsic cellular mechanisms involved in rhythm generation and phase transitions. In particular, the CPG formed from units incorporating a slowly inactivating persistent sodium current shows the greatest range of oscillation periods and the greatest degree of independence in phase duration control by asymmetric inputs. These results are explained based on geometric analysis of the phase plane structures corresponding to the dynamics for each CPG type

  19. Reflective electron beam lithography: lithography results using CMOS controlled digital pattern generator chip

    NASA Astrophysics Data System (ADS)

    Gubiotti, Thomas; Sun, Jeff Fuge; Freed, Regina; Kidwingira, Francoise; Yang, Jason; Bevis, Chris; Carroll, Allen; Brodie, Alan; Tong, William M.; Lin, Shy-Jay; Wang, Wen-Chuan; Haspeslagh, Luc; Vereecke, Bart

    2013-03-01

    Maskless electron beam lithography can potentially extend semiconductor manufacturing to the 10 nm logic (16 nm half pitch) technology node and beyond. KLA-Tencor is developing Reflective Electron Beam Lithography (REBL) technology targeting high-volume 10 nm logic node performance. REBL uses a novel multi-column wafer writing system combined with an advanced stage architecture to enable the throughput and resolution required for a NGL system. Using a CMOS Digital Pattern Generator (DPG) chip with over one million microlenses, the system is capable of maskless printing of arbitrary patterns with pixel redundancy and pixel-by-pixel grayscaling at the wafer. Electrons are generated in a flood beam via a thermionic cathode at 50-100 keV and decelerated to illuminate the DPG chip. The DPG-modulated electron beam is then reaccelerated and demagnified 80-100x onto the wafer to be printed. Previously, KLA-Tencor reported on the development progress of the REBL tool for maskless lithography at and below the 10 nm logic technology node. Since that time, the REBL team has made good progress towards developing the REBL system and DPG for direct write lithography. REBL has been successful in manufacturing a CMOS controlled DPG chip with a stable charge drain coating and with all segments functioning. This DPG chip consists of an array of over one million electrostatic lenslets that can be switched on or off via CMOS voltages to pattern the flood electron beam. Testing has proven the validity of the design with regards to lenslet performance, contrast, lifetime, and pattern scrolling. This chip has been used in the REBL demonstration platform system for lithography on a moving stage in both PMMA and chemically amplified resist. Direct imaging of the aerial image has also been performed by magnifying the pattern at the wafer plane via a mag stack onto a YAG imaging screen. This paper will discuss the chip design improvements and new charge drain coating that have resulted in a

  20. Bio-inspired Optimal Locomotion Reconfigurability of Quadruped Rovers using Central Pattern Generators

    NASA Astrophysics Data System (ADS)

    Bohra, Murtaza

    Legged rovers are often considered as viable solutions for traversing unknown terrain. This work addresses the optimal locomotion reconfigurability of quadruped rovers, which consists of obtaining optimal locomotion modes, and transitioning between them. A 2D sagittal plane rover model is considered based on a domestic cat. Using a Genetic Algorithm, the gait, pose and control variables that minimize torque or maximize speed are found separately. The optimization approach takes into account the elimination of leg impact, while considering the entire variable spectrum. The optimal solutions are consistent with other works on gait optimization, and are similar to gaits found in quadruped animals as well. An online model-free gait planning framework is also implemented, that is based on Central Pattern Generators is implemented. It is used to generate joint and control trajectories for any arbitrarily varying speed profile, and shown to regulate locomotion transition and speed modulation, both endogenously and continuously.

  1. Bio-inspired design strategies for central pattern generator control in modular robotics.

    PubMed

    Herrero-Carrón, F; Rodríguez, F B; Varona, P

    2011-03-01

    New findings in the nervous system of invertebrates have shown how a number of features of central pattern generator (CPG) circuits contribute to the generation of robust flexible rhythms. In this paper we consider recently revealed strategies that living CPGs follow to design CPG control paradigms for modular robots. To illustrate them, we divide the task of designing an example CPG for a modular robot into independent problems. We formulate each problem in a general way and provide a bio-inspired solution for each of them: locomotion information coding, individual module control and inter-module coordination. We analyse the stability of the CPG numerically, and then test it on a real robot. We analyse steady state locomotion and recovery after perturbations. In both cases, the robot is able to autonomously find a stable effective locomotion state. Finally, we discuss how these strategies can result in a more general design approach for CPG-based locomotion.

  2. Far-field radiation patterns of second harmonic generation from gold nanoparticles under tightly focused illumination.

    PubMed

    Sun, Jingwei; Wang, Xianghui; Chang, Shengjiang; Zeng, Ming; Shen, Si; Zhang, Na

    2016-04-04

    We study far-field angular radiation patterns of second harmonic generation (SHG) from gold nanosphere, nanocube, nanorod, and nanocup illuminated by tightly focused linearly and radially polarized beams, respectively. It is found that under linearly polarized illumination, far-field forward-scattering SHG (FSHG) dominates second harmonic (SH) responses generated by those gold particles. On the contrary, it is amazing that significant backward-scattering SHG (BSHG) can be observed when those gold nanoparticles are excited by a focused radially polarized beam. For the case of gold nanosphere, the effective point dipole systems are developed to reasonably elucidate this interesting difference. Our investigations suggest that for SHG microscopy with backward detection scheme, tightly focused radially polarized beam could be a promising excitation field to improve the backward SH signal.

  3. The internal flow pattern analysis of a tidal power turbine operating on bidirectional generation-pumping

    NASA Astrophysics Data System (ADS)

    Y Luo, Y.; Xiao, Y. X.; Wang, Z. W.

    2013-12-01

    Using tidal energy can reduce environment pollution, save conventional energy and improve energy structure, hence it presents great advantage and is developing potential. Influenced by flood tide and low tide, a fully functional tidal power station needs to experience six operating modes, including bidirectional generation, pumping and sluice; the internal unsteady flow pattern and dynamic characters are very complicated. Based on a bidirectional tidal generator unit, three-dimensional unsteady flows in the flow path were calculated for four typical operating conditions with the pressure pulsation characteristics analyzed. According to the numerical results, the internal flow characteristics in the flow path were discussed. The influence of gravity to the hydraulic performance and flow characteristics were analysed. The results provide a theoretical analysis method of the hydraulic optimization design of the same type unit as well as a direction for stable operation and optimal scheduling of existing tidal power unit.

  4. Identification of gene expression patterns crucially involved in experimental autoimmune encephalomyelitis and multiple sclerosis

    PubMed Central

    Herrmann, Martin M.; Barth, Silvia; Greve, Bernhard; Schumann, Kathrin M.; Bartels, Andrea

    2016-01-01

    ABSTRACT After encounter with a central nervous system (CNS)-derived autoantigen, lymphocytes leave the lymph nodes and enter the CNS. This event leads only rarely to subsequent tissue damage. Genes relevant to CNS pathology after cell infiltration are largely undefined. Myelin-oligodendrocyte-glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) is an animal model of multiple sclerosis (MS), a chronic autoimmune disease of the CNS that results in disability. To assess genes that are involved in encephalitogenicity and subsequent tissue damage mediated by CNS-infiltrating cells, we performed a DNA microarray analysis from cells derived from lymph nodes and eluted from CNS in LEW.1AV1 (RT1av1) rats immunized with MOG 91-108. The data was compared to immunizations with adjuvant alone or naive rats and to immunizations with the immunogenic but not encephalitogenic MOG 73-90 peptide. Here, we show involvement of Cd38, Cxcr4 and Akt and confirm these findings by the use of Cd38-knockout (B6.129P2-Cd38tm1Lnd/J) mice, S1P-receptor modulation during EAE and quantitative expression analysis in individuals with MS. The hereby-defined underlying pathways indicate cellular activation and migration pathways mediated by G-protein-coupled receptors as crucial events in CNS tissue damage. These pathways can be further explored for novel therapeutic interventions. PMID:27519689

  5. Simultaneously Uncovering the Patterns of Brain Regions Involved in Different Story Reading Subprocesses

    PubMed Central

    Wehbe, Leila; Murphy, Brian; Talukdar, Partha; Fyshe, Alona; Ramdas, Aaditya; Mitchell, Tom

    2014-01-01

    Story understanding involves many perceptual and cognitive subprocesses, from perceiving individual words, to parsing sentences, to understanding the relationships among the story characters. We present an integrated computational model of reading that incorporates these and additional subprocesses, simultaneously discovering their fMRI signatures. Our model predicts the fMRI activity associated with reading arbitrary text passages, well enough to distinguish which of two story segments is being read with 74% accuracy. This approach is the first to simultaneously track diverse reading subprocesses during complex story processing and predict the detailed neural representation of diverse story features, ranging from visual word properties to the mention of different story characters and different actions they perform. We construct brain representation maps that replicate many results from a wide range of classical studies that focus each on one aspect of language processing and offer new insights on which type of information is processed by different areas involved in language processing. Additionally, this approach is promising for studying individual differences: it can be used to create single subject maps that may potentially be used to measure reading comprehension and diagnose reading disorders. PMID:25426840

  6. Generation of static and dynamic patterned co-cultures using microfabricated parylene-C stencils.

    PubMed

    Wright, Dylan; Rajalingam, Bimalraj; Selvarasah, Selvapraba; Dokmeci, Mehmet R; Khademhosseini, Ali

    2007-10-01

    Many biological processes, such as stem cell differentiation, wound healing and development, involve dynamic interactions between cells and their microenvironment. The ability to control these dynamic processes in vitro would be potentially useful to fabricate tissue engineering constructs, study biological processes, and direct stem cell differentiation. In this paper, we used a parylene-C microstencil to develop two methods of creating patterned co-cultures using either static or dynamic conditions. In the static case, embryonic stem (ES) cells were co-cultured with fibroblasts or hepatocytes by using the reversible sealing of the stencil on the substrate. In the dynamic case, ES cells were co-cultured with NIH-3T3 fibroblasts and AML12 hepatocytes sequentially by engineering the surface properties of the stencil. In this approach, the top surface of the parylene-C stencil was initially treated with hyaluronic acid (HA) to reduce non-specific cell adhesion. The stencil was then sealed on a substrate and seeded with ES cells which adhered to the underlying substrate through the holes in the membrane. To switch the surface properties of the parylene-C stencils to cell adhesive, collagen was deposited on the parylene-C surfaces. Subsequently, a second cell type was seeded on the parylene-C stencils to form a patterned co-culture. This group of cells was removed by peeling off the parylene-C stencils, which enabled the patterning of a third cell type. Although the static patterned co-culture approach has been demonstrated previously with a variety of methods, layer-by-layer modification of microfabricated parylene-C stencils enables dynamic patterning of multiple cell types in sequence. Thus, this method is a promising approach to engineering the complexity of cell-cell interactions in tissue culture in a spatially and temporally regulated manner.

  7. Importance of the inherent and the relative surface energies in generating patterned layer in a solution process

    NASA Astrophysics Data System (ADS)

    Kim, Do-Kyung; Kwon, Hyeok Bin; Park, Hongsik; Choe, Eunji; Bae, Jin-Hyuk; Park, Jaehoon; Song, Seong-Ho

    2016-03-01

    We report the importance of the inherent and the relative surface energies in generating a patterned organic semiconductor layer through a solution process. The inherent and the relative surface energies of the substrate can be effectively controlled using polydimethylsiloxane in combination with an UV/ozone treatment. The controlled inherent surface energy in each region, as well as the high-order difference of relative surface energy, plays a significant role in generating the patterned layer. In addition, the patterned metal-semiconductor-metal (MSM) structure shows a lower lateral current than the non-patterned MSM structure because the current path is limited.

  8. TermGenie – a web-application for pattern-based ontology class generation

    SciTech Connect

    Dietze, Heiko; Berardini, Tanya Z.; Foulger, Rebecca E.; Hill, David P.; Lomax, Jane; Osumi-Sutherland, David; Roncaglia, Paola; Mungall, Christopher J.

    2014-01-01

    Biological ontologies are continually growing and improving from requests for new classes (terms) by biocurators. These ontology requests can frequently create bottlenecks in the biocuration process, as ontology developers struggle to keep up, while manually processing these requests and create classes. TermGenie allows biocurators to generate new classes based on formally specified design patterns or templates. The system is web-based and can be accessed by any authorized curator through a web browser. Automated rules and reasoning engines are used to ensure validity, uniqueness and relationship to pre-existing classes. In the last 4 years the Gene Ontology TermGenie generated 4715 new classes, about 51.4% of all new classes created. The immediate generation of permanent identifiers proved not to be an issue with only 70 (1.4%) obsoleted classes. Lastly, TermGenie is a web-based class-generation system that complements traditional ontology development tools. All classes added through pre-defined templates are guaranteed to have OWL equivalence axioms that are used for automatic classification and in some cases inter-ontology linkage. At the same time, the system is simple and intuitive and can be used by most biocurators without extensive training.

  9. TermGenie – a web-application for pattern-based ontology class generation

    DOE PAGES

    Dietze, Heiko; Berardini, Tanya Z.; Foulger, Rebecca E.; ...

    2014-01-01

    Biological ontologies are continually growing and improving from requests for new classes (terms) by biocurators. These ontology requests can frequently create bottlenecks in the biocuration process, as ontology developers struggle to keep up, while manually processing these requests and create classes. TermGenie allows biocurators to generate new classes based on formally specified design patterns or templates. The system is web-based and can be accessed by any authorized curator through a web browser. Automated rules and reasoning engines are used to ensure validity, uniqueness and relationship to pre-existing classes. In the last 4 years the Gene Ontology TermGenie generated 4715 newmore » classes, about 51.4% of all new classes created. The immediate generation of permanent identifiers proved not to be an issue with only 70 (1.4%) obsoleted classes. Lastly, TermGenie is a web-based class-generation system that complements traditional ontology development tools. All classes added through pre-defined templates are guaranteed to have OWL equivalence axioms that are used for automatic classification and in some cases inter-ontology linkage. At the same time, the system is simple and intuitive and can be used by most biocurators without extensive training.« less

  10. Expression pattern of diacylglycerol acyltransferase-1, an enzyme involved in triacylglycerol biosynthesis, in Arabidopsis thaliana.

    PubMed

    Lu, Chaofu Lu; de Noyer, Shen Bayon; Hobbs, Douglas H; Kang, Jinling; Wen, Yancheng; Krachtus, Dieter; Hills, Matthew J

    2003-05-01

    Triacylglycerol (TAG) is the major carbon storage reserve in oilseeds such as Arabidopsis. Acyl-CoA:diacylglycerol acyltransferase (DGAT) catalyses the final step of the TAG synthesis pathway. Although TAG is mainly accumulated during seed development, and DGAT has presumably the highest activity in developing seeds, we show here that TAG synthesis is also actively taking place during germination and seedling development in Arabidopsis. The expression pattern of the DGAT1 gene was studied in transgenic plants containing the reporter gene beta-glucuronidase (GUS) fused with DNA sequences flanking the DGAT1 coding region. GUS activity was not only detected in developing seeds and pollen, which normally accumulate storage TAG, but also in germinating seeds and seedlings. Western blots showed that DGAT1 protein is present in several tissues, though is most abundant in developing seeds. In seedlings, DGAT1 is expressed in shoot and root apical regions, correlating with rapid cell division and growth. The expression of GUS in seedlings was consistent with the results of RNA gel blot analyses, precursor feeding and DGAT assay. In addition, DGAT1 gene expression is up-regulated by glucose and associated with glucose-induced changes in seedling development.

  11. Structural insights into HetR−PatS interaction involved in cyanobacterial pattern formation

    PubMed Central

    Hu, Hai-Xi; Jiang, Yong-Liang; Zhao, Meng-Xi; Cai, Kun; Liu, Sanling; Wen, Bin; Lv, Pei; Zhang, Yonghui; Peng, Junhui; Zhong, Hui; Yu, Hong-Mei; Ren, Yan-Min; Zhang, Zhiyong; Tian, Changlin; Wu, Qingfa; Oliveberg, Mikael; Zhang, Cheng-Cai; Chen, Yuxing; Zhou, Cong-Zhao

    2015-01-01

    The one-dimensional pattern of heterocyst in the model cyanobacterium Anabaena sp. PCC 7120 is coordinated by the transcription factor HetR and PatS peptide. Here we report the complex structures of HetR binding to DNA, and its hood domain (HetRHood) binding to a PatS-derived hexapeptide (PatS6) at 2.80 and 2.10 Å, respectively. The intertwined HetR dimer possesses a couple of novel HTH motifs, each of which consists of two canonical α-helices in the DNA-binding domain and an auxiliary α-helix from the flap domain of the neighboring subunit. Two PatS6 peptides bind to the lateral clefts of HetRHood, and trigger significant conformational changes of the flap domain, resulting in dissociation of the auxiliary α-helix and eventually release of HetR from the DNA major grove. These findings provide the structural insights into a prokaryotic example of Turing model. PMID:26576507

  12. Patterns of mental health, substance abuse, and justice system involvement among youth aging out of child welfare.

    PubMed

    Shook, Jeffrey; Goodkind, Sara; Pohlig, Ryan T; Schelbe, Lisa; Herring, David; Kim, Kevin H

    2011-07-01

    Although research on youth aging out of the child welfare system has increased, there has been limited focus on how their experiences vary. In particular, there is a need to examine patterns in the involvement of these youth in other systems, which indicate constellations of challenges facing these young people as they transition out of care and into adulthood. Using administrative data from a large birth cohort of individuals born between 1985 and 1994 whose families have been involved in the child welfare system, this article presents an analysis of the mental health, substance abuse, juvenile justice, and criminal justice system involvement of youth who have aged out of child welfare. Using a 2-step cluster analysis, we identify 5 subgroups of youth. Two of these groups, accounting for almost half of the youth, have little other system involvement and have child welfare care careers of relative stability. The other 3 groups, consisting of just over half of the youth, have much more extensive other system involvement, as well as care careers marked by instability and a greater proportion of time spent in congregate care.

  13. Low frequency variability of European weather patterns and its impact on power generation in northern Europe

    NASA Astrophysics Data System (ADS)

    Masato, Giacomo; Slavov, Georgi

    2016-04-01

    It is well known that Europe is becoming increasingly reliant on the power generation from the solar and wind sources. Germany is a leader in such a trend - it is then interesting to study to what extent the low-frequency variability of the European weather patterns impacts the power production in this country. Rather than identifying such patterns starting from the weather angle, four weather regimes are identified that maximize and minimize the production of solar and wind power. The analysis of their past occurrence and trends allows us to estimate the potential amount of energy produced for any given year (assuming a constant installed capacity). It is found that the sole change in such weather regimes over the recent years is able to drive up to a 20% annual difference in power generation. This also throws an interesting challenge at the scientific community, whereby the future projection of these regimes can heavily influence both the short- and long-term Eurozone plans in terms of European renewable energy targets.

  14. Scalable and enhanced triboelectric output power generation by surface functionalized nanoimprint patterns.

    PubMed

    Kwon, Yang Hyeog; Shin, Sung-Ho; Jung, Joo-Yun; Nah, Junghyo

    2016-05-20

    We report nanoimprint lithographic submicron surface patterning for scalable output power generation and performance enhancement in triboelectric nanogenerators (TENGs). Specifically, one contact surface of a TENG is nanoimprinted with polyurethane acrylate (PUA) lines in different pitches and the counter contact surface is coated with perfluoropolyether (PFPE). The results show that a TENG with 200 nm pitch PUA lines exhibits voltage and current up to ∼430 V and ∼55 μA cm(-2), generating about a sixfold higher output power than that with a flat PUA surface at an applied force of 0.3 MPa. In addition, scalable output power was obtained by adjusting line pitches. Further enhancement in output power was also demonstrated by chemically functionalizing the PUA line patterns with poly (diallyldimethylammonium chloride) (PDDA). The PDDA functionalization boosted voltage and current up to ∼500 V and ∼100 μA cm(-2), respectively, which corresponds to ∼50% power density enhancement. The approach introduced here is a simple, effective, scalable and reproducible way to fabricate TENGs.

  15. Scalable and enhanced triboelectric output power generation by surface functionalized nanoimprint patterns

    NASA Astrophysics Data System (ADS)

    Hyeog Kwon, Yang; Shin, Sung-Ho; Jung, Joo-Yun; Nah, Junghyo

    2016-05-01

    We report nanoimprint lithographic submicron surface patterning for scalable output power generation and performance enhancement in triboelectric nanogenerators (TENGs). Specifically, one contact surface of a TENG is nanoimprinted with polyurethane acrylate (PUA) lines in different pitches and the counter contact surface is coated with perfluoropolyether (PFPE). The results show that a TENG with 200 nm pitch PUA lines exhibits voltage and current up to ˜430 V and ˜55 μA cm-2, generating about a sixfold higher output power than that with a flat PUA surface at an applied force of 0.3 MPa. In addition, scalable output power was obtained by adjusting line pitches. Further enhancement in output power was also demonstrated by chemically functionalizing the PUA line patterns with poly (diallyldimethylammonium chloride) (PDDA). The PDDA functionalization boosted voltage and current up to ˜500 V and ˜100 μA cm-2, respectively, which corresponds to ˜50% power density enhancement. The approach introduced here is a simple, effective, scalable and reproducible way to fabricate TENGs.

  16. Endogenous rhythm and pattern-generating circuit interactions in cockroach motor centres

    PubMed Central

    David, Izhak; Holmes, Philip

    2016-01-01

    ABSTRACT Cockroaches are rapid and stable runners whose gaits emerge from the intricate, and not fully resolved, interplay between endogenous oscillatory pattern-generating networks and sensory feedback that shapes their rhythmic output. Here we studied the endogenous motor output of a brainless, deafferented preparation. We monitored the pilocarpine-induced rhythmic activity of levator and depressor motor neurons in the mesothoracic and metathoracic segments in order to reveal the oscillatory networks’ architecture and interactions. Data analyses included phase relations, latencies between and overlaps of rhythmic bursts, spike frequencies, and the dependence of these parameters on cycle frequency. We found that, overall, ipsilateral connections are stronger than contralateral ones. Our findings revealed asymmetries in connectivity among the different ganglia, in which meta-to-mesothoracic ascending coupling is stronger than meso-to-metathoracic descending coupling. Within-ganglion coupling between the metathoracic hemiganglia is stronger than that in the mesothoracic ganglion. We also report differences in the role and mode of operation of homologue network units (manifested by levator and depressor nerve activity). Many observed characteristics are similar to those exhibited by intact animals, suggesting a dominant role for feedforward control in cockroach locomotion. Based on these data we posit a connectivity scheme among components of the locomotion pattern generating system. PMID:27422902

  17. Control of traveling-wave oscillations and bifurcation behavior in central pattern generators

    NASA Astrophysics Data System (ADS)

    Landsman, Alexandra S.; Slotine, Jean-Jacques

    2012-10-01

    Understanding synchronous and traveling-wave oscillations, particularly as they relate to transitions between different types of behavior, is a central problem in modeling biological systems. Here, we address this problem in the context of central pattern generators (CPGs). We use contraction theory to establish the global stability of a traveling-wave or synchronous oscillation, determined by the type of coupling. This opens the door to better design of coupling architectures to create the desired type of stable oscillations. We then use coupling that is both amplitude and phase dependent to create either globally stable synchronous or traveling-wave solutions. Using the CPG motor neuron network of a leech as an example, we show that while both traveling and synchronous oscillations can be achieved by several types of coupling, the transition between different types of behavior is dictated by a specific coupling architecture. In particular, it is only the “repulsive” but not the commonly used phase or rotational coupling that can explain the transition to high-frequency synchronous oscillations that have been observed in the heartbeat pattern generator of a leech. This shows that the overall dynamics of a CPG can be highly sensitive to the type of coupling used, even for coupling architectures that are widely believed to produce the same qualitative behavior.

  18. Organisation of the spinal central pattern generators for locomotion in the salamander: biology and modelling.

    PubMed

    Chevallier, Stéphanie; Jan Ijspeert, Auke; Ryczko, Dimitri; Nagy, Frédéric; Cabelguen, Jean-Marie

    2008-01-01

    Among living tetrapods, salamanders are regarded as most closely resembling the first terrestrial vertebrates, and are therefore an interesting group in which the evolutionary changes in the locomotor behaviour from aquatic to terrestrial habitats can be inferred. Salamanders exhibit two locomotor modes: swimming and terrestrial stepping. The swimming is anguilliform and resembles closely that of the lamprey. On the ground, the salamander switches to a stepping gait with axial undulations that is also observed in many reptiles. The salamander is therefore ideally suited for examining the neural mechanisms for the generation of these two locomotor modes, as well as the neural mechanisms of gait transition. In the present paper, we describe the kinematics and patterns of activation of axial and limb muscles during stepping and swimming in adult salamanders. We then review the current neurobiological data about the organisation of the spinal networks underlying swimming and stepping, and the mechanisms of gait transition. Finally we report modelling studies aimed at understanding the organisation and operation of the salamander locomotor circuits. Altogether, the neurobiological and the modelling data support the hypothesis of a phylogenetic conservatism from agnathians to amphibians of the spinal locomotor networks generating axial motor patterns.

  19. Models of central pattern generators for quadruped locomotion. I. Primary gaits.

    PubMed

    Buono, P L; Golubitsky, M

    2001-04-01

    In this paper we continue the analysis of a network of symmetrically coupled cells modeling central pattern generators for quadruped locomotion proposed by Golubitsky, Stewart, Buono, and Collins. By a cell we mean a system of ordinary differential equations and by a coupled cell system we mean a network of identical cells with coupling terms. We have three main results in this paper. First, we show that the proposed network is the simplest one modeling the common quadruped gaits of walk, trot, and pace. In doing so we prove a general theorem classifying spatio-temporal symmetries of periodic solutions to equivariant systems of differential equations. We also specialize this theorem to coupled cell systems. Second, this paper focuses on primary gaits; that is, gaits that are modeled by output signals from the central pattern generator where each cell emits the same waveform along with exact phase shifts between cells. Our previous work showed that the network is capable of producing six primary gaits. Here, we show that under mild assumptions on the cells and the coupling of the network, primary gaits can be produced from Hopf bifurcation by varying only coupling strengths of the network. Third, we discuss the stability of primary gaits and exhibit these solutions by performing numerical simulations using the dimensionless Morris-Lecar equations for the cell dynamics.

  20. Control of traveling-wave oscillations and bifurcation behavior in central pattern generators.

    PubMed

    Landsman, Alexandra S; Slotine, Jean-Jacques

    2012-10-01

    Understanding synchronous and traveling-wave oscillations, particularly as they relate to transitions between different types of behavior, is a central problem in modeling biological systems. Here, we address this problem in the context of central pattern generators (CPGs). We use contraction theory to establish the global stability of a traveling-wave or synchronous oscillation, determined by the type of coupling. This opens the door to better design of coupling architectures to create the desired type of stable oscillations. We then use coupling that is both amplitude and phase dependent to create either globally stable synchronous or traveling-wave solutions. Using the CPG motor neuron network of a leech as an example, we show that while both traveling and synchronous oscillations can be achieved by several types of coupling, the transition between different types of behavior is dictated by a specific coupling architecture. In particular, it is only the "repulsive" but not the commonly used phase or rotational coupling that can explain the transition to high-frequency synchronous oscillations that have been observed in the heartbeat pattern generator of a leech. This shows that the overall dynamics of a CPG can be highly sensitive to the type of coupling used, even for coupling architectures that are widely believed to produce the same qualitative behavior.

  1. Transition of pattern generation: the phenomenon of post-scratching locomotion.

    PubMed

    Trejo, A; Tapia, J A; De la Torre Valdovinos, B; Huidobro, N; Flores, G; Flores-Hernandez, J; Flores, A; Manjarrez, E

    2015-03-12

    A fundamental problem in neurophysiology is the understanding of neuronal mechanisms by which the central nervous system produces a sequence of voluntary or involuntary motor acts from a diverse repertory of movements. These kinds of transitions between motor acts are extremely complex; however, they could be analyzed in a more simple form in decerebrate animals in the context of spinal central pattern generation. Here, we present for the first time a physiological phenomenon of post-scratching locomotion in which decerebrate cats exhibit a compulsory locomotor activity after an episode of scratching. We found flexor, extensor and intermediate single interneurons rhythmically firing in the same phase during both scratching and the subsequent post-scratching locomotion. Because no changes in phase of these neurons from scratching to post-scratching locomotion were found, we suggest that in the lumbar spinal cord there are neurons associated with both motor tasks. Moreover, because of its high reproducibility we suggest that the study of post-scratching fictive locomotion, together with the unitary recording of neurons, could become a useful tool to study neuronal mechanisms underlying transitions from one rhythmic motor task to another, and to study in more detail the central pattern generator circuitry in the spinal cord.

  2. Endogenous rhythm and pattern-generating circuit interactions in cockroach motor centres.

    PubMed

    David, Izhak; Holmes, Philip; Ayali, Amir

    2016-09-15

    Cockroaches are rapid and stable runners whose gaits emerge from the intricate, and not fully resolved, interplay between endogenous oscillatory pattern-generating networks and sensory feedback that shapes their rhythmic output. Here we studied the endogenous motor output of a brainless, deafferented preparation. We monitored the pilocarpine-induced rhythmic activity of levator and depressor motor neurons in the mesothoracic and metathoracic segments in order to reveal the oscillatory networks' architecture and interactions. Data analyses included phase relations, latencies between and overlaps of rhythmic bursts, spike frequencies, and the dependence of these parameters on cycle frequency. We found that, overall, ipsilateral connections are stronger than contralateral ones. Our findings revealed asymmetries in connectivity among the different ganglia, in which meta-to-mesothoracic ascending coupling is stronger than meso-to-metathoracic descending coupling. Within-ganglion coupling between the metathoracic hemiganglia is stronger than that in the mesothoracic ganglion. We also report differences in the role and mode of operation of homologue network units (manifested by levator and depressor nerve activity). Many observed characteristics are similar to those exhibited by intact animals, suggesting a dominant role for feedforward control in cockroach locomotion. Based on these data we posit a connectivity scheme among components of the locomotion pattern generating system.

  3. Voltage-dependent switching of sensorimotor integration by a lobster central pattern generator.

    PubMed

    Nargeot, Romuald

    2003-06-15

    Behavioral adaptations and the underlying neural plasticity may not simply result from peripheral information conveyed by sensory inputs. Central neuronal networks often spontaneously generate neuronal activity patterns that may also contribute to sensorimotor integration and behavioral adaptations. The present study explored a novel form of sensory-induced plasticity by which the resulting changes in motor output depend essentially on the preexisting functional state of an identified neuron of an endogenously active central network. In the isolated lobster stomatogastric nervous system, electrical stimulation of a mechanosensory nerve transiently inactivated rhythmic spike bursting in the lateral pyloric (LP) neuron of the pyloric motor pattern-generating network. Repeated sensory nerve stimulation gradually and long-lastingly strengthened the bursting of the LP neuron to the detriment of sensory-elicited inactivation. This strengthening of pyloric-timed rhythmic activity was enhanced by experimental depolarization of the neuron. Conversely, when the LP neuron was hyperpolarized, the same sensory stimulation paradigm now gradually increased the susceptibility of the pyloric-timed bursting of the network neuron to sensory-elicited inactivation. Modulation of depolarization-activated and hyperpolarization-activated ionic conductances that underlie the intrinsic bursting properties of the LP neuron may contribute via differential voltage-dependent recruitment and effects to the respective adaptive processes. These data therefore suggest a novel state-dependent mechanism by which an endogenously active central network can decrease or increase its responsiveness to the same sensory input.

  4. Factors involved in the generation and replication of rhabdovirus defective T particles.

    PubMed Central

    Holland, J J; Villarreal, L P; Breindl, M

    1976-01-01

    Previous indications that cloned B virions might be genetically predisposed to generate a particular defective T particle are shown to be inaccurate. T particle generation was found to be a much more random process than was previously believed. We show that the previously observed generation of particular sizes of T particles by B virion pools is due to the random generation of T particles during preparation of first-passage pools of cloned B virions, and these breed true during the additional passages needed to produce visible quantities of T particles. It is also shown that different host cell lines selectively amplify different T particles, suggesting a strong role of host cell factors in T particle replication. Surprisingly, our line of HeLa cells did not generate or replicate detectable T particles of vesicular stomatitis virus (VSV) Indiana after either serial undiluted passage or direct addition of T particles, even though the added T particles strongly interfered with B virion replication. In contrast to VSV, rabies virus generates large amounts of T particles during the first passage of cloned B virions, and every rabies-infected baby hamster kidney-21 cell culture evolves into a persistent carrier state. We find that T particle RNA is biologically inactive although T particle nucleocapsid ribonucleoprotein replicates and interferes in cells coinfected with B virions. Efforts to study the mechanism of T particle generation by in vitro attempts to generate T particles or modify their size (using sheared ribonucleoprotein or chemical or UV mutagenesis) were unsuccessful. The kinetics of UV and nitrous acid inactivation of T particles indicate a smaller target size relative to B virions, even after correcting for lengths of RNA molecules. The intercalating dye proflavine does not photosensitize VSV B virions or T particles when present during replication, indicating that there is little or no RNA base pairing in the helical nucleocapsids of either. PMID

  5. Central pattern generators for social vocalization: Androgen-dependent neurophysiological mechanisms

    PubMed Central

    Bass, Andrew H.; Remage-Healey, Luke

    2008-01-01

    Historically, most studies of vertebrate central pattern generators (CPGs) have focused on mechanisms for locomotion and respiration. Here, we highlight new results for ectothermic vertebrates, namely teleost fish and amphibians, showing how androgenic steroids can influence the temporal patterning of CPGs for social vocalization. Investigations of vocalizing teleosts show how androgens can rapidly (within minutes) modulate the neurophysiological output of the vocal CPG (fictive vocalizations that mimic the temporal properties of natural vocalizations) inclusive of their divergent actions between species, as well as intraspecific differences between male reproductive morphs. Studies of anuran amphibians (frogs) demonstrate that long-term steroid treatments (wks) can masculinize the fictive vocalizations of females, inclusive of its sensitivity to rapid modulation by serotonin. Given the conserved organization of vocal control systems across vertebrate groups, the vocal CPGs of fish and amphibians provide tractable models for identifying androgen-dependent events that are fundamental to the mechanisms of vocal motor patterning. These basic mechanisms can also inform our understanding of the more complex CPGs for vocalization, and social behaviors in general, that have evolved among birds and mammals. PMID:18262186

  6. Central pattern generators for social vocalization: androgen-dependent neurophysiological mechanisms.

    PubMed

    Bass, Andrew H; Remage-Healey, Luke

    2008-05-01

    Historically, most studies of vertebrate central pattern generators (CPGs) have focused on mechanisms for locomotion and respiration. Here, we highlight new results for ectothermic vertebrates, namely teleost fish and amphibians, showing how androgenic steroids can influence the temporal patterning of CPGs for social vocalization. Investigations of vocalizing teleosts show how androgens can rapidly (within minutes) modulate the neurophysiological output of the vocal CPG (fictive vocalizations that mimic the temporal properties of natural vocalizations) inclusive of their divergent actions between species, as well as intraspecific differences between male reproductive morphs. Studies of anuran amphibians (frogs) demonstrate that long-term steroid treatments (wks) can masculinize the fictive vocalizations of females, inclusive of its sensitivity to rapid modulation by serotonin. Given the conserved organization of vocal control systems across vertebrate groups, the vocal CPGs of fish and amphibians provide tractable models for identifying androgen-dependent events that are fundamental to the mechanisms of vocal motor patterning. These basic mechanisms can also inform our understanding of the more complex CPGs for vocalization, and social behaviors in general, that have evolved among birds and mammals.

  7. Mechanisms of Left-Right Coordination in Mammalian Locomotor Pattern Generation Circuits: A Mathematical Modeling View

    PubMed Central

    Talpalar, Adolfo E.; Rybak, Ilya A.

    2015-01-01

    The locomotor gait in limbed animals is defined by the left-right leg coordination and locomotor speed. Coordination between left and right neural activities in the spinal cord controlling left and right legs is provided by commissural interneurons (CINs). Several CIN types have been genetically identified, including the excitatory V3 and excitatory and inhibitory V0 types. Recent studies demonstrated that genetic elimination of all V0 CINs caused switching from a normal left-right alternating activity to a left-right synchronized “hopping” pattern. Furthermore, ablation of only the inhibitory V0 CINs (V0D subtype) resulted in a lack of left-right alternation at low locomotor frequencies and retaining this alternation at high frequencies, whereas selective ablation of the excitatory V0 neurons (V0V subtype) maintained the left–right alternation at low frequencies and switched to a hopping pattern at high frequencies. To analyze these findings, we developed a simplified mathematical model of neural circuits consisting of four pacemaker neurons representing left and right, flexor and extensor rhythm-generating centers interacting via commissural pathways representing V3, V0D, and V0V CINs. The locomotor frequency was controlled by a parameter defining the excitation of neurons and commissural pathways mimicking the effects of N-methyl-D-aspartate on locomotor frequency in isolated rodent spinal cord preparations. The model demonstrated a typical left-right alternating pattern under control conditions, switching to a hopping activity at any frequency after removing both V0 connections, a synchronized pattern at low frequencies with alternation at high frequencies after removing only V0D connections, and an alternating pattern at low frequencies with hopping at high frequencies after removing only V0V connections. We used bifurcation theory and fast-slow decomposition methods to analyze network behavior in the above regimes and transitions between them. The model

  8. Mechanisms of left-right coordination in mammalian locomotor pattern generation circuits: a mathematical modeling view.

    PubMed

    Molkov, Yaroslav I; Bacak, Bartholomew J; Talpalar, Adolfo E; Rybak, Ilya A

    2015-05-01

    The locomotor gait in limbed animals is defined by the left-right leg coordination and locomotor speed. Coordination between left and right neural activities in the spinal cord controlling left and right legs is provided by commissural interneurons (CINs). Several CIN types have been genetically identified, including the excitatory V3 and excitatory and inhibitory V0 types. Recent studies demonstrated that genetic elimination of all V0 CINs caused switching from a normal left-right alternating activity to a left-right synchronized "hopping" pattern. Furthermore, ablation of only the inhibitory V0 CINs (V0D subtype) resulted in a lack of left-right alternation at low locomotor frequencies and retaining this alternation at high frequencies, whereas selective ablation of the excitatory V0 neurons (V0V subtype) maintained the left-right alternation at low frequencies and switched to a hopping pattern at high frequencies. To analyze these findings, we developed a simplified mathematical model of neural circuits consisting of four pacemaker neurons representing left and right, flexor and extensor rhythm-generating centers interacting via commissural pathways representing V3, V0D, and V0V CINs. The locomotor frequency was controlled by a parameter defining the excitation of neurons and commissural pathways mimicking the effects of N-methyl-D-aspartate on locomotor frequency in isolated rodent spinal cord preparations. The model demonstrated a typical left-right alternating pattern under control conditions, switching to a hopping activity at any frequency after removing both V0 connections, a synchronized pattern at low frequencies with alternation at high frequencies after removing only V0D connections, and an alternating pattern at low frequencies with hopping at high frequencies after removing only V0V connections. We used bifurcation theory and fast-slow decomposition methods to analyze network behavior in the above regimes and transitions between them. The model

  9. Patterns and rates of riverbank erosion involving ice-rich permafrost (yedoma) in northern Alaska

    NASA Astrophysics Data System (ADS)

    Kanevskiy, Mikhail; Shur, Yuri; Strauss, Jens; Jorgenson, Torre; Fortier, Daniel; Stephani, Eva; Vasiliev, Alexander

    2016-01-01

    Yedoma, a suite of syngenetically frozen silty ice- and organic-rich deposits with large ice wedges that accumulated during the late Pleistocene, is vulnerable to thermal degradation and erosion because of the extremely high ice contents. This degradation can result in significant surface subsidence and retreat of coastal bluffs and riverbanks with large consequences to landscape evolution, infrastructure damage, and water quality. We used remote sensing and field observations to assess patterns and rates of riverbank erosion at a 35-m-high active yedoma bluff along the Itkillik River in northern Alaska. The total volumetric ground-ice content-including wedge, segregated, and pore ice-was estimated to be 86%. The process of riverbank erosion and stabilization include three main stages typical of the areas with ice-rich permafrost: (1) thermal erosion combined with thermal denudation, (2) thermal denudation, and (3) slope stabilization. Active riverbank erosion at the main study site started in July 1995, when the Itkillik River changed its channel. The total retreat of the riverbank during 1995-2010 within different segments of the bluff varied from 180 to 280 m; the average retreat rate for the most actively eroded part of the riverbank was almost 19 m/y. From August 2007 to August 2011, the total retreat varied from 10 to almost 100 m. The average retreat rate for the whole 680-m-long bluff was 11 m/y. For the most actively eroded central part of the bluff (150 m long) it was 20 m/y, ranging from 16 to 24 m/y. More than 180,000 m3 of ground ice and organic-rich frozen soil, or almost 70,000 metric tons (t) of soil solids including 880 t of organic carbon, were transported to the river from the retreating bank annually. This study reports the highest long-term rates of riverbank erosion ever observed in permafrost regions of Eurasia and North America.

  10. Resolution improvement and pattern generator development for the maskless micro-ion-beam reduction lithography system

    NASA Astrophysics Data System (ADS)

    Jiang, Ximan

    have been studied. The dependence of the throughput with the exposure field size and the speed of the mechanical stage has been investigated. In order to perform maskless lithography, different micro-fabricated pattern generators have been developed for the MMRL system. Ion beamlet switching has been successfully demonstrated on the MMRL system. A positive bias voltage around 10 volts is sufficient to switch off the ion current on the micro-fabricated pattern generators. Some unexpected problems, such as the high-energy secondary electron radiations, have been discovered during the experimental investigation. Thermal and structural analysis indicates that the aperture displacement error induced by thermal expansion can satisfy the 3delta CD requirement for lithography nodes down to 25 nm. The cross-talking effect near the surface and inside the apertures of the pattern generator has been simulated in a 3-D ray-tracing code. New pattern generator design has been proposed to reduce the cross-talking effect. In order to eliminate the surface charging effect caused by the secondary electrons, a new beam-switching scheme in which the switching electrodes are immersed in the plasma has been demonstrated on a mechanically fabricated pattern generator.

  11. Adaptive expression pattern of different proteins involved in cellular calcium homeostasis in denervated rat vas deferens.

    PubMed

    Quintas, Luis Eduardo M; Cunha, Valéria M N; Scaramello, Christianne B V; da Silva, Cláudia L M; Caricati-Neto, Afonso; Lafayette, Simone S L; Jurkiewicz, Aron; Noël, François

    2005-11-21

    The activity and protein expression of plasma membrane and sarco(endo)plasmic reticulum (Ca2+-Mg2+)ATPases and ryanodine receptors were investigated in surgically denervated rat vas deferens. The function of thapsigargin-sensitive but not thapsigargin-resistant (Ca2+-Mg2+)ATPase (from sarco(endo)plasmic reticulum and plasma membrane, respectively), evidenced by enzyme activity and Ca2+ uptake experiments, was significantly depressed by 30-50% when compared to innervated vas. Western blots showed that such reduction in sarco(endo)plasmic reticulum (Ca2+-Mg2+)ATPase performance was accompanied by a decrement of similar magnitude in sarco(endo)plasmic reticulum (Ca2+-Mg2+)ATPase type 2 protein expression, without any significant change in plasma membrane (Ca2+-Mg2+)ATPase expression. Finally, [3H]ryanodine binding revealed that the density of ryanodine binding sites was reduced by 45% after denervation without modification in affinity. The present findings demonstrate that sarco(endo)plasmic reticulum proteins involved in intracellular calcium homeostasis are clearly down-regulated and brings further evidence of a modified calcium translocation in denervated rat vas deferens.

  12. Catabolic and regulatory systems in Shewanella oneidensis MR-1 involved in electricity generation in microbial fuel cells

    PubMed Central

    Kouzuma, Atsushi; Kasai, Takuya; Hirose, Atsumi; Watanabe, Kazuya

    2015-01-01

    Shewanella oneidensis MR-1 is a facultative anaerobe that respires using a variety of inorganic and organic compounds. MR-1 is also capable of utilizing extracellular solid materials, including anodes in microbial fuel cells (MFCs), as electron acceptors, thereby enabling electricity generation. As MFCs have the potential to generate electricity from biomass waste and wastewater, MR-1 has been extensively studied to identify the molecular systems that are involved in electricity generation in MFCs. These studies have demonstrated the importance of extracellular electron-transfer (EET) pathways that electrically connect the quinone pool in the cytoplasmic membrane to extracellular electron acceptors. Electricity generation is also dependent on intracellular catabolic pathways that oxidize electron donors, such as lactate, and regulatory systems that control the expression of genes encoding the components of catabolic and electron-transfer pathways. In addition, recent findings suggest that cell-surface polymers, e.g., exopolysaccharides, and secreted chemicals, which function as electron shuttles, are also involved in electricity generation. Despite these advances in our knowledge on the EET processes in MR-1, further efforts are necessary to fully understand the underlying intra- and extracellular molecular systems for electricity generation in MFCs. We suggest that investigating how MR-1 coordinates these systems to efficiently transfer electrons to electrodes and conserve electrochemical energy for cell proliferation is important for establishing the biological basis for MFCs. PMID:26136738

  13. Molecules and mechanisms involved in the generation and migration of cortical interneurons

    PubMed Central

    Hernández-Miranda, Luis R; Parnavelas, John G; Chiara, Francesca

    2010-01-01

    The GABA (γ-aminobutyric acid)-containing interneurons of the neocortex are largely derived from the ganglionic eminences in the subpallium. Numerous studies have previously defined the migratory paths travelled by these neurons from their origins to their destinations in the cortex. We review here results of studies that have identified many of the genes expressed in the subpallium that are involved in the specification of the subtypes of cortical interneurons, and the numerous transcription factors, motogenic factors and guidance molecules that are involved in their migration. PMID:20360946

  14. Molecules and mechanisms involved in the generation and migration of cortical interneurons.

    PubMed

    Hernández-Miranda, Luis R; Parnavelas, John G; Chiara, Francesca

    2010-03-31

    The GABA (γ-aminobutyric acid)-containing interneurons of the neocortex are largely derived from the ganglionic eminences in the subpallium. Numerous studies have previously defined the migratory paths travelled by these neurons from their origins to their destinations in the cortex. We review here results of studies that have identified many of the genes expressed in the subpallium that are involved in the specification of the subtypes of cortical interneurons, and the numerous transcription factors, motogenic factors and guidance molecules that are involved in their migration.

  15. Investigation of vortex clouds and droplet sizes in heated water spray patterns generated by axisymmetric full cone nozzles.

    PubMed

    Naz, M Y; Sulaiman, S A; Ariwahjoedi, B; Ku Shaari, Ku Zilati

    2013-01-01

    The hot water sprays are an important part of many industrial processes, where the detailed knowledge of physical phenomena involved in jet transportation, interaction, secondary breakup, evaporation, and coalescence of droplets is important to reach more efficient processes. The objective of the work was to study the water spray jet breakup dynamics, vortex cloud formation, and droplet size distribution under varying temperature and load pressure. Using a high speed camera, the spray patterns generated by axisymmetric full cone nozzles were visualized as a function water temperature and load pressure. The image analysis confirmed that the spray cone angle and width do not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The formation and decay of semitorus like vortex clouds were also noticed in spray structures generated at near water boiling point temperature. For the nozzle with smallest orifice diameter (1.19 mm), these vortex clouds were very clear at 90°C heating temperature and 1 bar water load pressure. In addition, the sauter mean diameter (SMD) of the spray droplets was also measured by using Phase Doppler Anemometry (PDA) at different locations downstream of the nozzle exit. It was noticed that SMD varies slightly w.r.t. position when measured at room temperature whereas at higher temperature values, it became almost constant at distance of 55 mm downstream of the nozzle exit.

  16. Population genetics of Mediterranean and Saharan olives: geographic patterns of differentiation and evidence for early generations of admixture

    PubMed Central

    Besnard, G.; El Bakkali, A.; Haouane, H.; Baali-Cherif, D.; Moukhli, A.; Khadari, B.

    2013-01-01

    Background and Aims The olive (Olea europaea subsp. europaea) was domesticated in the Mediterranean area but its wild relatives are distributed over three continents, from the Mediterranean basin to South Africa and south-western Asia. Recent studies suggested that this crop originated in the Levant while a secondary diversification occurred in most westward areas. A possible contribution of the Saharan subspecies (subsp. laperrinei) has been highlighted, but the data available were too limited to draw definite conclusions. Here, patterns of genetic differentiation in the Mediterranean and Saharan olives are analysed to test for recent admixture between these taxa. Methods Nuclear microsatellite and plastid DNA (ptDNA) data were compiled from previous studies and completed for a sample of 470 cultivars, 390 wild Mediterranean trees and 270 Saharan olives. A network was reconstructed for the ptDNA haplotypes, while a Bayesian clustering method was applied to identify the main gene pools in the data set and then simulate and test for early generations of admixture between Mediterranean and Saharan olives. Key Results Four lineages of ptDNA haplotypes are recognized: three from the Mediterranean basin and one from the Sahara. Only one haplotype, primarily distributed in the Sahara, is shared between laperrinei and europaea. This haplotype is detected once in ‘Dhokar’, a cultivar from the Maghreb. Nuclear microsatellites show geographic patterns of genetic differentiation in the Mediterranean olive that reflect the primary origins of cultivars in the Levant, and indicate a high genetic differentiation between europaea and laperrinei. No first-generation hybrid between europaea and laperrinei is detected, but recent, reciprocal admixture between Mediterranean and Saharan subspecies is found in a few accessions, including ‘Dhokar’. Conclusions This study reports for the first time admixture between Mediterranean and Saharan olives. Although its contribution

  17. Particular significance of SRD2-dependent snRNA accumulation in polarized pattern generation during lateral root development of Arabidopsis.

    PubMed

    Ohtani, Misato; Demura, Taku; Sugiyama, Munetaka

    2010-12-01

    Lateral root primordia are initiated by anticlinal division of cells in the pericycle and are constructed through an ordered set of cell divisions. At the completion of the development of the primordium, cell division ceases, after which the lateral root meristem is activated. In Arabidopsis, this course of lateral root morphogenesis was found to be significantly susceptible to srd2-1, a temperature-sensitive mutation of the SRD2 gene encoding an activator of small nuclear RNA (snRNA) transcription. The srd2-1 mutation altered the organization of cells of the root primordium and, importantly, maintained primordial cell division for a long period, resulting in the formation of abnormal hemispherical laterals. Expression patterns of various reporter genes suggested that both the apical-basal and radial axes were not well established in the lateral root primordia of the srd2-1 mutant. In the early stages of development of the primordium, the srd2-1 mutation reduced the amount of the auxin efflux facilitator PIN-FORMED (PIN) and, probably by this means, interfered with the generation of an auxin gradient. Spliceosomal snRNAs accumulated at high levels throughout young root primordia and then decreased in association with the arrest of cell division, and finally increased again when the apical meristem became activated. The accumulation of snRNAs was severely suppressed by the srd2-1 mutation, and this was detectable before any morphological defect became evident. These findings suggest that high-level accumulation of snRNA involving the SRD2 function is particularly important for expression of PINs in polarized pattern generation during the development of lateral root primordia.

  18. The New Workforce Generation: Understanding the Problems Facing Parental Involvement in Jordanian Kindergartens

    ERIC Educational Resources Information Center

    Ihmeideh, Fathi; Khasawneh, Samer; Mahfouz, Safi; Khawaldeh, Moustafa

    2008-01-01

    This study aimed to investigate the problems facing parental involvement in Jordanian kindergartens from the parents' perspectives. A 36-item questionnaire that addressed five domains was designed by the researchers and distributed among the study participants. The study sample consisted of 297 parents of kindergarten children from various…

  19. Pattern of inner retinal layers involvement in pigmented paravenous retinochoroidal atrophy as determined by SD-OCT: case report.

    PubMed

    Junqueira, Daniela Laura Melo; Lopes, Flavio Siqueira Santos; Biteli, Luís Gustavo; Prata, Tiago Santos

    2013-01-01

    Pigmented paravenous retinochoroidal atrophy is an ocular disease characterized by outer retina and choroidal atrophy often with overlying intraretinal bone spicule pigment deposition along the retinal veins. As a rare condition, there is scant information in the literature regarding the pattern of inner retinal layers involvement. We present a case of a 41-year-old white man initially referred for a glaucoma evaluation. Fundoscopy revealed patches of retinochoroidal atrophy and light pigmentation extending from the optic nerve head along the inferior-temporal retinal veins in both eyes. Using different spectral-domain optical coherence tomography (SD-OCT) protocols we identified a significant thinning of the inner retinal layers along the inferior-temporal veins, but with a lucid interval surrounding the optic nerve head. Standard automated perimetry revealed a superior absolute arcuate scotoma sparing the central fixation (good structure-functional correlation). This pattern of inner retinal layers involvement was not previously described. We believe SD-OCT added significantly to the anatomical description of this case. Physicians should consider these new anatomical findings and correlate them with functional status while assessing these patients.

  20. Advanced electron-beam pattern generation technology for 180-nm masks

    NASA Astrophysics Data System (ADS)

    Abboud, Frank E.; Sauer, Charles A.; Wang, William; Vernon, Matthew; Prior, Richard; Pearce-Percy, Henry T.; Cole, Damon M.; Mankos, Marian

    1997-02-01

    Optical lithography will be the dominant technique used for 180 nm generation production devices. With a reduced feature size on the wafer, 4X optical reduction, optical proximity correction (OPC), and phase shift lithography techniques, mask-related errors become even more critical to wafer yield. In addition, small feature sizes and lithography enhancement techniques require finer edge resolution. Clearly, new patten generation tools are needed for this generation of maskmaking requirements. Multipass gray (MPG) writing strategy was introduced with the MEBESR 4500S. The ability to deliver a 4X improvement in dose while improving throughput is a significant advantage over previous MEBES systems. Since MPG is used in conjunction with offset scan voting, reduction in butting of over 50% has been demonstrated with MPG. Higher doses are now possible with use of a multipass writing strategy and a brighter source. As a result, resists with higher contrast and process robustness can be used. A significant improvement in uniformity is noted with the new process, an essential step needed in meeting 180 nm requirements. Dry etch is essential to meet these new requirements and with sufficient process margin to be manufacturable. This paper describes the key electron-beam pattern generation technology necessary to meet the requirement of 180 nm masks, including a high dose field- emission gun and column capable of delivering 800 A/cm2; complete dynamic beam correction; a digital stage servo to provide stable, reproducible stage control under high acceleration conditions; a high speed data path to support 320 MHz beam blanking and a 10 nm data address. This paper also examines the improvements made to the MEBES platform and documents the resulting improvements and compares these results to the requirements for 180 nm masks.

  1. The expression pattern of genes involved in early neurogenesis suggests distinct and conserved functions in the diplopod Glomeris marginata.

    PubMed

    Pioro, Hilary L; Stollewerk, Angelika

    2006-01-01

    We have shown recently that the expression and function of proneural genes is conserved in chelicerates and myriapods, although groups of neural precursors are specified in the ventral neuroectoderm of these arthropod groups, rather than single cells as in insects and crustaceans. We present additional evidence that the pattern of neurogenesis seen in chelicerates and in previously analyzed myriapod species is representative of both arthropod groups, by analysing the formation of neural precursors in the diplopod Archispirostreptus sp. This raises the question as to what extent the genetic network has been modified to result in different modes of neurogenesis in the arthropod group. To find out which components of the neural genetic network might account for the different mode of neural precursor formation in chelicerates and myriapods, we identified genes in the diplopod Glomeris marginata that are known to be involved in early neurogenesis in Drosophila and studied their expression pattern. In Drosophila, early neurogenesis is controlled by proneural genes that encode HLH transcription factors. These genes belong to two major subfamilies, the achaete-scute group and the atonal group. Different proneural proteins activate both a common neural programme and distinct neuronal subtype-specific target genes. We show that the expression pattern of homologs of the Drosophila proneural genes daughterless, atonal, and Sox B1 are partially conserved in Glomeris mariginata. While the expression of the pan-neural gene snail is conserved in the ventral neuroectoderm of G. marginata, we found an additional expression domain in the ventral midline. We conclude that, although the components of the genetic network involved in specification of neural precursors seem to be conserved in chelicerates, myriapods, and Drosophila, the function of some of the genes might have changed during evolution.

  2. Atmospheric-pressure plasma jet induces apoptosis involving mitochondria via generation of free radicals.

    PubMed

    Ahn, Hak Jun; Kim, Kang Il; Kim, Geunyoung; Moon, Eunpyo; Yang, Sang Sik; Lee, Jong-Soo

    2011-01-01

    The plasma jet has been proposed as a novel therapeutic method for anticancer treatment. However, its biological effects and mechanism of action remain elusive. Here, we investigated its cell death effects and underlying molecular mechanisms, using air and N₂ plasma jets from a micro nozzle array. Treatment with air or N₂ plasma jets caused apoptotic death in human cervical cancer HeLa cells, simultaneously with depolarization of mitochondrial membrane potential. In addition, the plasma jets were able to generate reactive oxygen species (ROS), which function as surrogate apoptotic signals by targeting the mitochondrial membrane potential. Antioxidants or caspase inhibitors ameliorated the apoptotic cell death induced by the air and N₂ plasma jets, suggesting that the plasma jet may generate ROS as a proapoptotic cue, thus initiating mitochondria-mediated apoptosis. Taken together, our data suggest the potential employment of plasma jets as a novel therapy for cancer.

  3. Atmospheric-Pressure Plasma Jet Induces Apoptosis Involving Mitochondria via Generation of Free Radicals

    PubMed Central

    Kim, Geunyoung; Moon, Eunpyo; Yang, Sang Sik; Lee, Jong-Soo

    2011-01-01

    The plasma jet has been proposed as a novel therapeutic method for anticancer treatment. However, its biological effects and mechanism of action remain elusive. Here, we investigated its cell death effects and underlying molecular mechanisms, using air and N2 plasma jets from a micro nozzle array. Treatment with air or N2 plasma jets caused apoptotic death in human cervical cancer HeLa cells, simultaneously with depolarization of mitochondrial membrane potential. In addition, the plasma jets were able to generate reactive oxygen species (ROS), which function as surrogate apoptotic signals by targeting the mitochondrial membrane potential. Antioxidants or caspase inhibitors ameliorated the apoptotic cell death induced by the air and N2 plasma jets, suggesting that the plasma jet may generate ROS as a proapoptotic cue, thus initiating mitochondria-mediated apoptosis. Taken together, our data suggest the potential employment of plasma jets as a novel therapy for cancer. PMID:22140530

  4. Generating Tonal Distinctions in Mandarin Chinese Using an Electrolarynx with Preprogrammed Tone Patterns

    PubMed Central

    Guo, Liana; Nagle, Kathy; Heaton, James T.

    2016-01-01

    An electrolarynx (EL) is a valuable rehabilitative option for individuals who have undergone laryngectomy, but current monotone ELs do not support controlled variations in fundamental frequency for producing tonal languages. The present study examined the production and perception of Mandarin Chinese using a customized hand-held EL driven by computer software to generate tonal distinctions (tonal EL). Four native Mandarin speakers were trained to articulate their speech coincidentally with preprogrammed tonal patterns in order to produce mono- and di-syllabic words with a monotone EL and tonal EL. Three native Mandarin speakers later transcribed and rated the speech samples for intelligibility and acceptability. Results indicated that words produced using the tonal EL were significantly more intelligible and acceptable than those produced using the monotone EL. PMID:26951783

  5. Generating Tonal Distinctions in Mandarin Chinese Using an Electrolarynx with Preprogrammed Tone Patterns.

    PubMed

    Guo, Liana; Nagle, Kathy; Heaton, James T

    2016-04-01

    An electrolarynx (EL) is a valuable rehabilitative option for individuals who have undergone laryngectomy, but current monotone ELs do not support controlled variations in fundamental frequency for producing tonal languages. The present study examined the production and perception of Mandarin Chinese using a customized hand-held EL driven by computer software to generate tonal distinctions (tonal EL). Four native Mandarin speakers were trained to articulate their speech coincidentally with preprogrammed tonal patterns in order to produce mono- and di-syllabic words with a monotone EL and tonal EL. Three native Mandarin speakers later transcribed and rated the speech samples for intelligibility and acceptability. Results indicated that words produced using the tonal EL were significantly more intelligible and acceptable than those produced using the monotone EL.

  6. Cell polarity-driven instability generates self-organized, fractal patterning of cell layers.

    PubMed

    Rudge, Timothy J; Federici, Fernán; Steiner, Paul J; Kan, Anton; Haseloff, Jim

    2013-12-20

    As a model system to study physical interactions in multicellular systems, we used layers of Escherichia coli cells, which exhibit little or no intrinsic coordination of growth. This system effectively isolates the effects of cell shape, growth, and division on spatial self-organization. Tracking the development of fluorescence-labeled cellular domains, we observed the emergence of striking fractal patterns with jagged, self-similar shapes. We then used a large-scale, cellular biophysical model to show that local instabilities due to polar cell-shape, repeatedly propagated by uniaxial growth and division, are responsible for generating this fractal geometry. Confirming this result, a mutant of E. coli with spherical shape forms smooth, nonfractal cellular domains. These results demonstrate that even populations of relatively simple bacterial cells can possess emergent properties due to purely physical interactions. Therefore, accurate physico-genetic models of cell growth will be essential for the design and understanding of genetically programmed multicellular systems.

  7. [Study on the control of dynamic artificial limb ankle based on central pattern generator].

    PubMed

    Guo, Xin; Xu, Caiyu; Li, Mingyue; Su, Longtao

    2014-12-01

    In order to obtain the normal gait for the prosthesis-carrier with the change of external environment and gait, we designed a model of dynamic ankle prosthesis and control system and introduced the strategy of central pattern generator (CPG) about the moving trail of dynamic ankle prosthesis. The dynamic parts, which are incorporated in the model of dynamic ankle prosthesis, provide power in order to have anthropic function and character. The tool of Matlab/simulink was used to simulate the strategy. The simulation results showed that the strategy of CPG learn- ing control in this study was effective and could track the reference trail rapidly and fit the moving trail of a person's normal limb. It can make the prosthetic timely regulation and action, enhance the prosthetic intelligence. It has im- portant practical value for intelligent prosthesis development based on this analysis of technology.

  8. A model of a flexible anguilliform swimmer driven by a central pattern generator with proprioceptive feedback

    NASA Astrophysics Data System (ADS)

    Hamlet, Christina; Tytell, Eric; Hoffman, Kathleen; Fauci, Lisa

    2015-11-01

    The swimming of a simple vertebrate, the lamprey, can shed light on how a flexible body can couple with a fluid environment to swim rapidly and efficiently. Animals use proprioceptive sensory information to sense how their bodies are bending, and then adjust the neural signals to their muscles to improve performance. We will present recent progress in the development of a computational model of a lamprey swimming in a Navier-Stokes fluid where a simple central pattern generator model, based on phase oscillators, is coupled to the evolving body dynamics of the swimmer through curvature and curvature derivative feedback. Such feedback can be positive (frequency decreasing), negative (frequency increasing), or mixed (positive to one side of the body and negative to the other, or vice versa). We will examine how the emergent swimming behavior and cost of transport depends upon these functional forms of proprioceptive feedback chosen in the model.

  9. On the derivation and tuning of phase oscillator models for lamprey central pattern generators.

    PubMed

    Várkonyi, Péter L; Kiemel, Tim; Hoffman, Kathleen; Cohen, Avis H; Holmes, Philip

    2008-10-01

    Using phase response curves and averaging theory, we derive phase oscillator models for the lamprey central pattern generator from two biophysically-based segmental models. The first one relies on network dynamics within a segment to produce the rhythm, while the second contains bursting cells. We study intersegmental coordination and show that the former class of models shows more robust behavior over the animal's range of swimming frequencies. The network-based model can also easily produce approximately constant phase lags along the spinal cord, as observed experimentally. Precise control of phase lags in the network-based model is obtained by varying the relative strengths of its six different connection types with distance in a phase model with separate coupling functions for each connection type. The phase model also describes the effect of randomized connections, accurately predicting how quickly random network-based models approach the determinisitic model as the number of connections increases.

  10. Reticular activating system of a central pattern generator: premovement electrical potentials.

    PubMed

    Tapia, Jesus A; Trejo, Argelia; Linares, Pablo; Alva, J Manuel; Kristeva, Rumyana; Manjarrez, Elias

    2013-10-01

    For the first time, here we characterize a bulbar reticular activating system (RAS) of neurons in decerebrate, deafferented and decerebellated cats producing a premovement electrical potential that we named obex slow potential (OSP). The OSP occurs about 0.8 ± 0.4 sec prior to the onset of a fictive-scratching-episode. Here, we describe two classes of bulbar neurons, off-on, which are silent but exhibit a 80 ± 56 Hz firing discharge at the beginning of (and during) the OSP, and on-off interneurons, with a 27 ± 14 Hz firing activity that stops at the beginning of (and during) the OSP. We suggest that these OSP-associated neurons belong to a descending RAS, which contributes to the activation of the spinal central pattern generators.

  11. The dynamics of elderly support. The transmission of solidarity patterns between generations.

    PubMed

    Attias-Donfut, C

    2001-02-01

    This paper analyses the support given to the handicapped elderly by their children on the basis of a large survey done in France where both the elderly and their middle-aged children were interviewed. These data allow us to address such questions as: "Who helps?", "Who receives help?" and "According to what principles?". Besides the principle of need which is at work, the results show that there is also the principle of equity, which functions through reciprocity. This study highlights two main processes in the dynamics of support for the elderly, its redistributive effects (family support mainly benefits the poorest elderly), and its complementarity with the state health care systems (family support is mainly directed towards those who also receive public help). Can we make the deduction that the more generous the welfare state, the more developed family solidarity is? Nevertheless, some difficulties arise: support is mostly given by women. Furthermore there are a small number of people on whose shoulders it falls to take care of everybody else in the family. One sign of these difficulties is that the carers are more often in less good health than the non-carers of the same age. Comparisons from one generation to the other, including the youngest (the children of the middle generation who were also interviewed) shows that the younger generation will not want to be so completely involved in parental care at the expense of their own private time and life. Most probably family involvement will be maintained in the future, but to a lesser extent.

  12. A connectionist central pattern generator for the aquatic and terrestrial gaits of a simulated salamander.

    PubMed

    Ijspeert, A J

    2001-05-01

    This article investigates the neural mechanisms underlying salamander locomotion, and develops a biologically plausible connectionist model of a central pattern generator capable of producing the typical aquatic and terrestrial gaits of the salamander. It investigates, in particular, what type of neural circuitry can produce and modulate the two locomotor programs identified within the salamander's spinal cord; namely, a traveling wave of neural activity for swimming and a standing wave for trotting. A two-dimensional biomechanical simulation of the salamander's body is developed whose muscle contraction is determined by the locomotion controller simulated as a leaky-integrator neural network. While the connectivity of the neural circuitry underlying locomotion in the salamander has not been decoded for the moment, this article presents the design of a neural circuit that has a general organization corresponding to that hypothesized by neurobiologists. In particular, the locomotion controller is based on a body central pattern generator (CPG) corresponding to a lamprey-like swimming controller, and is extended with a limb CPG for controlling the salamander's limbs. The complete controller is developed in three stages: first the development of segmental oscillators, second the development of intersegmental coupling for the making of a lamprey-like swimming CPG, and finally the development of the limb CPG and its coupling to the body CPG. A genetic algorithm is used to determine the parameters of the neural circuit for the different stages, given a high-level description of the desired state space trajectories of the different subnetworks. A controller is thus developed that can produce neural activities and locomotion gaits very similar to those observed in the real salamander. By varying the tonic (i.e. non-oscillating) excitation applied to the network, the speed, direction and type of gait can be varied.

  13. A muscarinic cholinergic mechanism underlies activation of the central pattern generator for locust flight.

    PubMed

    Buhl, Edgar; Schildberger, Klaus; Stevenson, Paul A

    2008-07-01

    A central question in behavioural control is how central pattern generators (CPGs) for locomotion are activated. This paper disputes the key role generally accredited to octopamine in activating the CPG for insect flight. In deafferented locusts, fictive flight was initiated by bath application of the muscarinic agonist pilocarpine, the acetylcholine analogue carbachol, and the acetylcholinesterase blocker eserine, but not by nicotine. Furthermore, in addition to octopamine, various other amines including dopamine, tyramine and histamine all induced fictive flight, but not serotonin or the amine-precursor amino acid tyrosine. However, flight initiation was not reversibly blocked by aminergic antagonists, and was still readily elicited by both natural stimulation (wind) and pilocarpine in reserpinized, amine-depleted locusts. By contrast, the muscarinic antagonists atropine and scopolamine reversibly blocked flight initiated by wind, cholinergic agonists, octopamine, and by selective stimulation of a flight-initiating interneurone (TCG). The short delay from TCG stimulation to flight onset suggests that TCG acts directly on the flight CPG, and accordingly that TCG, or its follower cell within the flight generating circuit, is cholinergic. We conclude that acetylcholine acting via muscarinic receptors is the key neurotransmitter in the mechanism underlying the natural activation of the locust flight CPG. Amines are not essential for this, but must be considered as potential neuromodulators for facilitating flight release and tuning the motor pattern. We speculate that muscarinic activation coupled to aminergic facilitation may be a general feature of behavioural control in insects for ensuring conditional recruitment of individual motor programs in accordance with momentary adaptive requirements.

  14. A modeling approach on why simple central pattern generators are built of irregular neurons.

    PubMed

    Reyes, Marcelo Bussotti; Carelli, Pedro Valadão; Sartorelli, José Carlos; Pinto, Reynaldo Daniel

    2015-01-01

    The crustacean pyloric Central Pattern Generator (CPG) is a nervous circuit that endogenously provides periodic motor patterns. Even after about 40 years of intensive studies, the rhythm genesis is still not rigorously understood in this CPG, mainly because it is made of neurons with irregular intrinsic activity. Using mathematical models we addressed the question of using a network of irregularly behaving elements to generate periodic oscillations, and we show some advantages of using non-periodic neurons with intrinsic behavior in the transition from bursting to tonic spiking (as found in biological pyloric CPGs) as building components. We studied two- and three-neuron model CPGs built either with Hindmarsh-Rose or with conductance-based Hodgkin-Huxley-like model neurons. By changing a model's parameter we could span the neuron's intrinsic dynamical behavior from slow periodic bursting to fast tonic spiking, passing through a transition where irregular bursting was observed. Two-neuron CPG, half center oscillator (HCO), was obtained for each intrinsic behavior of the neurons by coupling them with mutual symmetric synaptic inhibition. Most of these HCOs presented regular antiphasic bursting activity and the changes of the bursting frequencies was studied as a function of the inhibitory synaptic strength. Among all HCOs, those made of intrinsic irregular neurons presented a wider burst frequency range while keeping a reliable regular oscillatory (bursting) behavior. HCOs of periodic neurons tended to be either hard to change their behavior with synaptic strength variations (slow periodic burster neurons) or unable to perform a physiologically meaningful rhythm (fast tonic spiking neurons). Moreover, 3-neuron CPGs with connectivity and output similar to those of the pyloric CPG presented the same results.

  15. Remote-sensing satellite ground station evaluation using QPSK emulator with test pattern and PRBS generation

    NASA Astrophysics Data System (ADS)

    Srinivas, R.; Nithyanandan, L.; Umadevi, G.; Padmavathi, C. S.; Nayani, Radha

    2015-12-01

    In order to validate the performance of X-band (8000-8400 MHz) remote-sensing satellite receive chain, when the satellite is not in the vicinity of ground station, local loop end-end evaluation tests are mandatory to certify the RF downlink and base band receive chain performance. A customised test patterns compatible to IRS satellite series and PRBS sequence are generated, which are modulated using QPSK emulator to check and verify the satellite downlink chain performance. The design and implementation are done using novel digital techniques, and QPSK modulator is integrated with Test pattern and PRBS generator using state-of-art FPGAs. The QPSK emulator output is connected to high-speed fibre optic link which transfers the signal to near field bore-site antenna system. The test signal is thus up converted from 2557.5 MHz (S-band) frequency to required satellite carrier frequency of 8212.5 MHz; the emulated test signal is radiated from bore-site antenna, which simulates real-time satellite data transmission from space. Thus, the signal received by the parabolic dish antenna is down converted to 720 MHz, demodulated, bit synchronized, clock recovered, and frame synchronized. The evaluation of frame sync errors is done for good video data quality check. Also in the QPSK emulator, there is option of PRBS mode. Hence, using this option, the RF downlink and receive chain are evaluated for good Bit error rate (BER). The BER requirement is 1 error (tolerable) in 106 Million bits. The QPSK emulator has the provision to support different frequencies and data rates corresponding to all IRS satellite missions.

  16. Identification of serum component involved in generation of neo-lectin with agglutinating and phenoloxidase activities in human serum.

    PubMed

    Manikandan, Beulaja; Ramar, Manikandan; Munusamy, Arumugam

    2014-01-01

    Human serum albumin (HSA) was identified as the component involved in generation of neo-lectin molecules with both lectin and phenoloxidase activities. Pronase treated HSA was able to agglutinate hen RBC and oxidize hydroquinone. Sodium dodecyl sulphate (SDS) treated HSA agglutinated both hen and sheep RBC as well as oxidized dopamine. The hemagglutinating activities of pronase/SDS treated HSA observed against hen RBC were dosimetric. The oxidation of pronase/SDS treated HSA with hydroquinone/dopamine, respectively, was inhibitable by inhibitors of phenoloxidase, namely, phenylthiourea and tropolone. Very low concentrations of HSA could generate these humoral neo-lectin molecules.

  17. Central pattern generators for locomotion control in animals and robots: a review.

    PubMed

    Ijspeert, Auke Jan

    2008-05-01

    The problem of controlling locomotion is an area in which neuroscience and robotics can fruitfully interact. In this article, I will review research carried out on locomotor central pattern generators (CPGs), i.e. neural circuits capable of producing coordinated patterns of high-dimensional rhythmic output signals while receiving only simple, low-dimensional, input signals. The review will first cover neurobiological observations concerning locomotor CPGs and their numerical modelling, with a special focus on vertebrates. It will then cover how CPG models implemented as neural networks or systems of coupled oscillators can be used in robotics for controlling the locomotion of articulated robots. The review also presents how robots can be used as scientific tools to obtain a better understanding of the functioning of biological CPGs. Finally, various methods for designing CPGs to control specific modes of locomotion will be briefly reviewed. In this process, I will discuss different types of CPG models, the pros and cons of using CPGs with robots, and the pros and cons of using robots as scientific tools. Open research topics both in biology and in robotics will also be discussed.

  18. Neuromodulator-evoked synaptic metaplasticity within a central pattern generator network.

    PubMed

    Kvarta, Mark D; Harris-Warrick, Ronald M; Johnson, Bruce R

    2012-11-01

    Synapses show short-term activity-dependent dynamics that alter the strength of neuronal interactions. This synaptic plasticity can be tuned by neuromodulation as a form of metaplasticity. We examined neuromodulator-induced metaplasticity at a graded chemical synapse in a model central pattern generator (CPG), the pyloric network of the spiny lobster stomatogastric ganglion. Dopamine, serotonin, and octopamine each produce a unique motor pattern from the pyloric network, partially through their modulation of synaptic strength in the network. We characterized synaptic depression and its amine modulation at the graded synapse from the pyloric dilator neuron to the lateral pyloric neuron (PD→LP synapse), driving the PD neuron with both long square pulses and trains of realistic waveforms over a range of presynaptic voltages. We found that the three amines can differentially affect the amplitude of graded synaptic transmission independently of the synaptic dynamics. Low concentrations of dopamine had weak and variable effects on the strength of the graded inhibitory postsynaptic potentials (gIPSPs) but reliably accelerated the onset of synaptic depression and recovery from depression independently of gIPSP amplitude. Octopamine enhanced gIPSP amplitude but decreased the amount of synaptic depression; it slowed the onset of depression and accelerated its recovery during square pulse stimulation. Serotonin reduced gIPSP amplitude but increased the amount of synaptic depression and accelerated the onset of depression. These results suggest that amine-induced metaplasticity at graded chemical synapses can alter the parameters of synaptic dynamics in multiple and independent ways.

  19. Family food involvement and frequency of family dinner meals among Australian children aged 10-12years. Cross-sectional and longitudinal associations with dietary patterns.

    PubMed

    Leech, Rebecca M; McNaughton, Sarah A; Crawford, David A; Campbell, Karen J; Pearson, Natalie; Timperio, Anna

    2014-04-01

    Involvement in meal preparation and eating meals with the family are associated with better dietary patterns in adolescents, however little research has included older children or longitudinal study designs. This 3-year longitudinal study examines cross-sectional and longitudinal associations between family food involvement, family dinner meal frequency and dietary patterns during late childhood. Questionnaires were completed by parents of 188 children from Greater Melbourne, Australia at baseline in 2002 (mean age=11.25years) and at follow-up in 2006 (mean age=14.16years). Principal components analysis (PCA) was used to identify dietary patterns. Factor analysis (FA) was used to determine the principal factors from six indicators of family food involvement. Multiple linear regression models were used to predict the dietary patterns of children and adolescents at baseline and at follow-up, 3years later, from baseline indicators of family food involvement and frequency of family dinner meals. PCA revealed two dietary patterns, labeled a healthful pattern and an energy-dense pattern. FA revealed one factor for family food involvement. Cross-sectionally among boys, family food involvement score (β=0.55, 95% CI: 0.02, 1.07) and eating family dinner meals daily (β=1.11, 95% CI: 0.27, 1.96) during late childhood were positively associated with the healthful pattern. Eating family dinner meals daily was inversely associated with the energy-dense pattern, cross-sectionally among boys (β=-0.56, 95% CI: -1.06, -0.06). No significant cross-sectional associations were found among girls and no significant longitudinal associations were found for either gender. Involvement in family food and eating dinner with the family during late childhood may have a positive influence on dietary patterns of boys. No evidence was found to suggest the effects on dietary patterns persist into adolescence.

  20. Diversity of wing patterns and abdomen-generated substrate sounds in 3 European scorpionfly species

    PubMed Central

    Hartbauer, Manfred; Gepp, Johannes; Hinteregger, Karin; Koblmüller, Stephan

    2016-01-01

    In the genus Panorpa (Insecta: Mecoptera), also known as scorpionflies, premating behavior includes repeated sequences of slow wing movements (waving, fanning, flagging) which are accompanied by rapid abdomen vibrations that generate substantial substrate-borne sound. It is still unknown whether wing patterns or vibratory signals contain information about species identity, sex and/or the quality of potential mating partners. Besides species-specific pheromones, these multimodal signals may be of particular importance for the maintenance of reproductive isolation in sympatrically occurring scorpionfly species. Here, we analyzed phyologenetic relationships among, and the pattern of forewings as well as substrate-borne sound in 3 different sympatric Central-European scorpionfly species (P. communis, P. germanica, and P. alpina). Divergence time estimates, based on 879 bp of the mitochondrial COI gene, indicate longstanding separate evolutionary histories for the studied Panorpa species. Morphological analysis revealed that wing length as an indicator of body size increased in the following order: P. alpina < P. germanica < P. communis. Individuals can be assigned to the correct species and sex with high accuracy just by evaluation of the number of dark spots and the proportion of wing pigmentation. Despite high variability of interpulse period at an individual level, across species analysis revealed a positive correlation of average interpulse period as well as mean signal amplitude with forewing length. These results suggest wing patterns, but less likely vibratory signals, to contain information about species identity. Furthermore, receivers may be able to estimate the body size of a signaler solely on the basis of substrate-borne sound. PMID:24818592

  1. Correlation of hierarchal Upper Silurian stacking patterns generated by Milankovitch orbital forcing

    SciTech Connect

    Mauriello, D.J.; Ketterer, M.W. . Dept. of Geology)

    1993-03-01

    The Upper Silurian Wills Creek Formation in Pennsylvania and Maryland is entirely divisible into meter-scale allocycles. Stacking patterns of these allocycles reveal a hierarchy consistent with predictions based on the Milankovitch model of orbital forcing. Asymmetrical Sixth-Order cycles (PACs), bounded by surfaces produced by precessional sea-level rises, are divisible into a lower highstand portion and an upper lowstand portion separated by a sharp sea-level fall surface produced by a rapid sea-level drop within the precessional cycle. Sixth-Order cycles may be genetically grouped into Fifth-Order (100 ky.) and subsequently, Fourth-Order (400 ky.) cycles, each of which exhibits a distinct internal symmetry. Fifth-Order cycles, on average three to four meters in thickness, are composed of a basal transgressive portion consisting of two PACs followed by two or three successively regressive PACs. Four Fifth-Order cycles constitute a complete Fourth-Order cycle, in which the second Fifth-Order cycle contains facies representing the deepest or least restricted paleoenvironments. In each case, the fundamental Sixth-Order cycles were generated by the precessional signal modulated by orbital eccentricity variations. Over distances in excess of 100 km, Wills Creek facies change laterally from nearshore marine to fluvial coastal plain. Stacking patterns in these distinct facies are identical, and thus correlative, indicating the basin-wide extent of the stratigraphic events which produced these patterns. These correlations demonstrate that Milankovitch-driven eustatic sea-level fluctuations were occurring during the Late Silurian.

  2. Dopamine modulation of transient potassium current evokes phase shifts in a central pattern generator network.

    PubMed

    Harris-Warrick, R M; Coniglio, L M; Barazangi, N; Guckenheimer, J; Gueron, S

    1995-01-01

    Bath application of dopamine modifies the rhythmic motor pattern generated by the 14 neuron pyloric network in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus. Among other effects, dopamine excites many of the pyloric constrictor (PY) neurons to fire at high frequency and phase-advances the timing of their activity in the motor pattern. These responses arise in part from direct actions of dopamine to modulate the intrinsic electrophysiological properties of the PY cells, and can be studied in synaptically isolated neurons. The rate of rebound following a hyperpolarizing prestep and the spike frequency during a subsequent depolarization are both accelerated by dopamine. Based on theoretical simulations, Hartline (1979) suggested that the rate of postinhibitory rebound in stomatogastric neurons could vary with the amount of voltage-sensitive transient potassium current (IA). Consistent with this prediction, we found that dopamine evokes a net conductance decrease in synaptically isolated PY neurons. In voltage clamp, dopamine reduces IA, specifically by reducing the amplitude of the slowly inactivating component of the current and shifting its voltage activation curve in the depolarized direction. 4-Aminopyridine, a selective blocker of IA in stomatogastric neurons, mimics and occludes the effects of dopamine on isolated PY neurons. A conductance-based mathematical model of the PY neuron shows appropriate changes in activity upon quantitative modification of the IA parameters affected by dopamine. These results demonstrate that dopamine excites and phase-advances the PY neurons in the rhythmic pyloric motor pattern at least in part by reducing the transient K+ current, IA.

  3. Octopamine-containing (OC) interneurons enhance central pattern generator activity in sucrose-induced feeding in the snail Lymnaea.

    PubMed

    Vehovszky, Agnes; Szabó, Henriette; Elliott, Christopher J H

    2004-10-01

    In the pond snail Lymnaea stagnalis octopamine-containing (OC) interneurons trigger and reconfigure the feeding pattern in isolated CNS by excitation of the central pattern generator. In semi-intact (lip-mouth-CNS) preparations, this central pattern generator is activated by chemosensory inputs. We now test if sucrose application to the lips activates the OC neurons independently of the rest of the feeding central pattern generator, or if the OC interneuron is activated by inputs from the feeding network. In 66% of experiments, sucrose stimulated feeding rhythms and OC interneurons received regular synaptic inputs. Only rarely (14%) did the OC interneuron fire action potentials, proving that firing of OC interneurons is not necessary for the sucrose-induced feeding. Prestimulation of OC neurons increased the intensity and duration of the feeding rhythm evoked by subsequent sucrose presentations. One micromolar octopamine in the CNS bath mimicked the effect of OC interneuron stimulation, enhancing the feeding response when sucrose is applied to the lips. We conclude that the modulatory OC neurons are not independently excited by chemosensory inputs to the lips, but rather from the buccal central pattern generator network. However, when OC neurons fire, they release modulatory octopamine, which provides a positive feedback to the network to enhance the sucrose-activated central pattern generator rhythm.

  4. Bisphenol A Exposure May Induce Hepatic Lipid Accumulation via Reprogramming the DNA Methylation Patterns of Genes Involved in Lipid Metabolism

    NASA Astrophysics Data System (ADS)

    Ke, Zhang-Hong; Pan, Jie-Xue; Jin, Lu-Yang; Xu, Hai-Yan; Yu, Tian-Tian; Ullah, Kamran; Rahman, Tanzil Ur; Ren, Jun; Cheng, Yi; Dong, Xin-Yan; Sheng, Jian-Zhong; Huang, He-Feng

    2016-08-01

    Accumulating evidence suggests a role of bisphenol A (BPA) in metabolic disorders. However, the underlying mechanism is still unclear. Using a mouse BPA exposure model, we investigated the effects of long-term BPA exposure on lipid metabolism and the underlying mechanisms. The male mice exposed to BPA (0.5 μg BPA /kg/day, a human relevant dose) for 10 months exhibited significant hepatic accumulation of triglycerides and cholesterol. The liver cells from the BPA-exposed mice showed significantly increased expression levels of the genes related to lipid synthesis. These liver cells showed decreased DNA methylation levels of Srebf1 and Srebf2, and increased expression levels of Srebf1 and Srebf2 that may upregulate the genes related to lipid synthesis. The expression levels of DNA methyltransferases were decreased in BPA-exposed mouse liver. Hepa1-6 cell line treated with BPA showed decreased expression levels of DNA methyltransferases and increased expression levels of genes involved in lipid synthesis. DNA methyltransferase knockdown in Hepa1-6 led to hypo-methylation and increased expression levels of genes involved in lipid synthesis. Our results suggest that long-term BPA exposure could induce hepatic lipid accumulation, which may be due to the epigenetic reprogramming of the genes involved in lipid metabolism, such as the alterations of DNA methylation patterns.

  5. Bisphenol A Exposure May Induce Hepatic Lipid Accumulation via Reprogramming the DNA Methylation Patterns of Genes Involved in Lipid Metabolism

    PubMed Central

    Ke, Zhang-Hong; Pan, Jie-Xue; Jin, Lu-Yang; Xu, Hai-Yan; Yu, Tian-Tian; Ullah, Kamran; Rahman, Tanzil Ur; Ren, Jun; Cheng, Yi; Dong, Xin-Yan; Sheng, Jian-Zhong; Huang, He-Feng

    2016-01-01

    Accumulating evidence suggests a role of bisphenol A (BPA) in metabolic disorders. However, the underlying mechanism is still unclear. Using a mouse BPA exposure model, we investigated the effects of long-term BPA exposure on lipid metabolism and the underlying mechanisms. The male mice exposed to BPA (0.5 μg BPA /kg/day, a human relevant dose) for 10 months exhibited significant hepatic accumulation of triglycerides and cholesterol. The liver cells from the BPA-exposed mice showed significantly increased expression levels of the genes related to lipid synthesis. These liver cells showed decreased DNA methylation levels of Srebf1 and Srebf2, and increased expression levels of Srebf1 and Srebf2 that may upregulate the genes related to lipid synthesis. The expression levels of DNA methyltransferases were decreased in BPA-exposed mouse liver. Hepa1-6 cell line treated with BPA showed decreased expression levels of DNA methyltransferases and increased expression levels of genes involved in lipid synthesis. DNA methyltransferase knockdown in Hepa1-6 led to hypo-methylation and increased expression levels of genes involved in lipid synthesis. Our results suggest that long-term BPA exposure could induce hepatic lipid accumulation, which may be due to the epigenetic reprogramming of the genes involved in lipid metabolism, such as the alterations of DNA methylation patterns. PMID:27502578

  6. An Historical Comparison of Parental Involvement of Three Generations of Japanese Americans (Isseis, Niseis, and Sanseis) in the Education of Their Children.

    ERIC Educational Resources Information Center

    Shoho, Alan R.

    A study was done that compared the parental involvement of three generations of Japanese Americans in their children's education, particularly their involvement in academic work and extracurricular activities and perceived barriers to involvement. First generation Japanese American immigrants are called "Isseis" in Japanese; second…

  7. Multi-Generational Perspectives: How They Interact and Impact Service to Students and Their Families in an Age of Highly-Involved Parents

    ERIC Educational Resources Information Center

    Wawrzusin, Andrea C.

    2013-01-01

    Although there have always been differences in how generations navigate decision-making in higher education, highly involved parents have led to conflicting inter-generational educational expectations. This research study investigated the phenomenon of parental involvement and how meanings on educational expectations vary depending on generation.…

  8. Study on tobacco components involved in the pyrolytic generation of selected smoke constituents.

    PubMed

    Torikai, K; Torikaiu, K; Uwano, Y; Nakamori, T; Tarora, W; Takahashi, H

    2005-04-01

    The aim of this study was to investigate the contribution of various tobacco components to the generation of smoke constituents using a tobacco pyrolysis model. We analyzed the amounts of primary tobacco components (sugars, protein, polyphenols, alkaloids, organic acids, inorganics etc.) in flue-cured and burley tobacco leaves. Each of the components was added to the tobacco leaves at the 0.5-fold and 1.0-fold amount naturally present in the leaves. The treated tobacco samples were pyrolyzed at 800 degrees C in a nitrogen atmosphere with an infrared image furnace, and the selected smoke constituents (benzo[a]pyrene, hydrogen cyanide, carbonyl compounds, aromatic amines, volatile organic compounds and phenolics) were quantitatively analyzed by several methods, including high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC-MS). The contribution of each tobacco component to the generation of selected smoke constituents was estimated from a regression line determined by the three yields (no addition, 0.5-fold addition, and 1.0-fold addition). The results of this study can provide useful and comprehensive information on the relationship between tobacco components and selected smoke constituents during pyrolysis.

  9. Feedback control of variability in the cycle period of a central pattern generator.

    PubMed

    Hooper, Ryan M; Tikidji-Hamburyan, Ruben A; Canavier, Carmen C; Prinz, Astrid A

    2015-11-01

    We address how feedback to a bursting biological pacemaker with intrinsic variability in cycle length can affect that variability. Specifically, we examine a hybrid circuit constructed of an isolated crab anterior burster (AB)/pyloric dilator (PD) pyloric pacemaker receiving virtual feedback via dynamic clamp. This virtual feedback generates artificial synaptic input to PD with timing determined by adjustable phase response dynamics that mimic average burst intervals generated by the lateral pyloric neuron (LP) in the intact pyloric network. Using this system, we measure network period variability dependence on the feedback element's phase response dynamics and find that a constant response interval confers minimum variability. We further find that these optimal dynamics are characteristic of the biological pyloric network. Building upon our previous theoretical work mapping the firing intervals in one cycle onto the firing intervals in the next cycle, we create a theoretical map of the distribution of all firing intervals in one cycle to the distribution of firing intervals in the next cycle. We then obtain an integral equation for a stationary self-consistent distribution of the network periods of the hybrid circuit, which can be solved numerically given the uncoupled pacemaker's distribution of intrinsic periods, the nature of the network's feedback, and the phase resetting characteristics of the pacemaker. The stationary distributions obtained in this manner are strongly predictive of the experimentally observed distributions of hybrid network period. This theoretical framework can provide insight into optimal feedback schemes for minimizing variability to increase reliability or maximizing variability to increase flexibility in central pattern generators driven by pacemakers with feedback.

  10. Feedback control of variability in the cycle period of a central pattern generator

    PubMed Central

    Tikidji-Hamburyan, Ruben A.; Canavier, Carmen C.; Prinz, Astrid A.

    2015-01-01

    We address how feedback to a bursting biological pacemaker with intrinsic variability in cycle length can affect that variability. Specifically, we examine a hybrid circuit constructed of an isolated crab anterior burster (AB)/pyloric dilator (PD) pyloric pacemaker receiving virtual feedback via dynamic clamp. This virtual feedback generates artificial synaptic input to PD with timing determined by adjustable phase response dynamics that mimic average burst intervals generated by the lateral pyloric neuron (LP) in the intact pyloric network. Using this system, we measure network period variability dependence on the feedback element's phase response dynamics and find that a constant response interval confers minimum variability. We further find that these optimal dynamics are characteristic of the biological pyloric network. Building upon our previous theoretical work mapping the firing intervals in one cycle onto the firing intervals in the next cycle, we create a theoretical map of the distribution of all firing intervals in one cycle to the distribution of firing intervals in the next cycle. We then obtain an integral equation for a stationary self-consistent distribution of the network periods of the hybrid circuit, which can be solved numerically given the uncoupled pacemaker's distribution of intrinsic periods, the nature of the network's feedback, and the phase resetting characteristics of the pacemaker. The stationary distributions obtained in this manner are strongly predictive of the experimentally observed distributions of hybrid network period. This theoretical framework can provide insight into optimal feedback schemes for minimizing variability to increase reliability or maximizing variability to increase flexibility in central pattern generators driven by pacemakers with feedback. PMID:26334008

  11. Development-related expression patterns of protein-coding and miRNA genes involved in porcine muscle growth.

    PubMed

    Wang, F J; Jin, L; Guo, Y Q; Liu, R; He, M N; Li, M Z; Li, X W

    2014-11-27

    Muscle growth and development is associated with remarkable changes in protein-coding and microRNA (miRNA) gene expression. To determine the expression patterns of genes and miRNAs related to muscle growth and development, we measured the expression levels of 25 protein-coding and 16 miRNA genes in skeletal and cardiac muscles throughout 5 developmental stages by quantitative reverse transcription-polymerase chain reaction. The Short Time-Series Expression Miner (STEM) software clustering results showed that growth-related genes were downregulated at all developmental stages in both the psoas major and longissimus dorsi muscles, indicating their involvement in early developmental stages. Furthermore, genes related to muscle atrophy, such as forkhead box 1 and muscle ring finger, showed unregulated expression with increasing age, suggesting a decrease in protein synthesis during the later stages of skeletal muscle development. We found that development of the cardiac muscle was a complex process in which growth-related genes were highly expressed during embryonic development, but they did not show uniform postnatal expression patterns. Moreover, the expression level of miR-499, which enhances the expression of the β-myosin heavy chain, was significantly different in the psoas major and longissimus dorsi muscles, suggesting the involvement of miR-499 in the determination of skeletal muscle fiber types. We also performed correlation analyses of messenger RNA and miRNA expression. We found negative relationships between miR-486 and forkhead box 1, and miR-133a and serum response factor at all developmental stages, suggesting that forkhead box 1 and serum response factor are potential targets of miR-486 and miR-133a, respectively.

  12. Brain networks involved in tactile speed classification of moving dot patterns: the effects of speed and dot periodicity

    PubMed Central

    Yang, Jiajia; Kitada, Ryo; Kochiyama, Takanori; Yu, Yinghua; Makita, Kai; Araki, Yuta; Wu, Jinglong; Sadato, Norihiro

    2017-01-01

    Humans are able to judge the speed of an object’s motion by touch. Research has suggested that tactile judgment of speed is influenced by physical properties of the moving object, though the neural mechanisms underlying this process remain poorly understood. In the present study, functional magnetic resonance imaging was used to investigate brain networks that may be involved in tactile speed classification and how such networks may be affected by an object’s texture. Participants were asked to classify the speed of 2-D raised dot patterns passing under their right middle finger. Activity in the parietal operculum, insula, and inferior and superior frontal gyri was positively related to the motion speed of dot patterns. Activity in the postcentral gyrus and superior parietal lobule was sensitive to dot periodicity. Psycho-physiological interaction (PPI) analysis revealed that dot periodicity modulated functional connectivity between the parietal operculum (related to speed) and postcentral gyrus (related to dot periodicity). These results suggest that texture-sensitive activity in the primary somatosensory cortex and superior parietal lobule influences brain networks associated with tactually-extracted motion speed. Such effects may be related to the influence of surface texture on tactile speed judgment. PMID:28145505

  13. Utility of next-generation RNA-sequencing in identifying chimeric transcription involving human endogenous retroviruses.

    PubMed

    Sokol, Martin; Jessen, Karen Margrethe; Pedersen, Finn Skou

    2016-01-01

    Several studies have shown that human endogenous retroviruses and endogenous retrovirus-like repeats (here collectively HERVs) impose direct regulation on human genes through enhancer and promoter motifs present in their long terminal repeats (LTRs). Although chimeric transcription in which novel gene isoforms containing retroviral and human sequence are transcribed from viral promoters are commonly associated with disease, regulation by HERVs is beneficial in other settings; for example, in human testis chimeric isoforms of TP63 induced by an ERV9 LTR protect the male germ line upon DNA damage by inducing apoptosis, whereas in the human globin locus the γ- and β-globin switch during normal hematopoiesis is mediated by complex interactions of an ERV9 LTR and surrounding human sequence. The advent of deep sequencing or next-generation sequencing (NGS) has revolutionized the way researchers solve important scientific questions and develop novel hypotheses in relation to human genome regulation. We recently applied next-generation paired-end RNA-sequencing (RNA-seq) together with chromatin immunoprecipitation with sequencing (ChIP-seq) to examine ERV9 chimeric transcription in human reference cell lines from Encyclopedia of DNA Elements (ENCODE). This led to the discovery of advanced regulation mechanisms by ERV9s and other HERVs across numerous human loci including transcription of large gene-unannotated genomic regions, as well as cooperative regulation by multiple HERVs and non-LTR repeats such as Alu elements. In this article, well-established examples of human gene regulation by HERVs are reviewed followed by a description of paired-end RNA-seq, and its application in identifying chimeric transcription genome-widely. Based on integrative analyses of RNA-seq and ChIP-seq, data we then present novel examples of regulation by ERV9s of tumor suppressor genes CADM2 and SEMA3A, as well as transcription of an unannotated region. Taken together, this article highlights

  14. Sphingomyelin generated by sphingomyelin synthase 1 is involved in attachment and infection with Japanese encephalitis virus

    PubMed Central

    Taniguchi, Makoto; Tasaki, Takafumi; Ninomiya, Hideaki; Ueda, Yoshibumi; Kuremoto, Koh-ichi; Mitsutake, Susumu; Igarashi, Yasuyuki; Okazaki, Toshiro; Takegami, Tsutomu

    2016-01-01

    Japanese encephalitis virus (JEV) is a mosquito-borne RNA virus which infects target cells via the envelope protein JEV-E. However, its cellular targets are largely unknown. To investigate the role of sphingomyelin (SM) in JEV infection, we utilized SM-deficient immortalized mouse embryonic fibroblasts (tMEF) established from SM synthase 1 (SMS1)/SMS2 double knockout mice. SMS deficiency significantly reduced both intracellular and extracellular JEV levels at 48 h after infection. Furthermore, after 15 min treatment with JEV, the early steps of JEV infection such as attachment and cell entry were also diminished in SMS-deficient tMEFs. The inhibition of JEV attachment and infection were recovered by overexpression of SMS1 but not SMS2, suggesting SMS1 contributes to SM production for JEV attachment and infection. Finally, intraperitoneal injection of JEV into SMS1-deficient mice showed an obvious decrease of JEV infection and its associated pathologies, such as meningitis, lymphocyte infiltration, and elevation of interleukin 6, compared with wild type mice. These results suggest that SMS1-generated SM on the plasma membrane is related in JEV attachment and subsequent infection, and may be a target for inhibition of JEV infection. PMID:27892528

  15. Pattern of Pulmonary Involvement and Outcome of Aspiration Pneumonia in Patients with Altered Consciousness Admitted in Dhaka Medical College Hospital.

    PubMed

    Chowdhury, R A; Azad, A K; Sardar, H; Siddiqui, M R; Saad, S; Rahman, S; Sikder, A S

    2016-01-01

    Aspiration is well recognized as a cause of pulmonary disease and is not uncommon in patients with altered consciousness.The mortality rate of aspiration pneumonia is approximately 1% in outpatient setting and upto 25% in those requiring hospitalization. This study was done to see the pattern of pulmonary involvement and outcome of aspiration pneumonia in patients with altered consciousness admitted in medicine department of a tertiary care hospital in our country. This was a prospective observational study conducted among the 52 adult patients of aspiration pneumonia with altered consciousness admitted in the medicine department of Dhaka Medical College Hospital (DMCH), during June 2010 to December 2010. Aspiration pneumonia was confirmed by clinical examination and laboratory investigations. Hematologic measurements (TC of WBC, Hb%, ESR, platelet count), chest X-ray, blood gas analysis, blood urea, creatinine and random blood sugar, sputum for Gram staining, sputum for culture sensitivity and blood culture were done in all patients.Assessment of altered conscious patient was done by application of the Glasgow Coma Scale. Case record forms with appropriate questionnaire were filled for all patients. The mean±SD age was 57.42±13.63 years with ranged from 25 to 90 years. Out of 52 patients, 37(71.15%) patients were male and 15(28.85%) patients were female. Following aspiration 76.92% patients developed pneumonitis, 13.46% patients developed lung abscess and only 9.62% patients developed ARDS. Most (33) of the patients had opacity in right lower zone and 13 patients had opacity in the left lower zone, 6 patients had opacity in right mid zone. Only 10 patients had opacity in both lower zones. In this study overall mortality rate was 23%. If only one lobe was involved radiologically, mortality was 8.33%. If two or more lobes on one or both sides were involved, mortality was in the range of 25-91%.

  16. Concept and analytical basis for revistas - A fast, flexible computer/graphic system for generating periodic satellite coverage patterns

    NASA Technical Reports Server (NTRS)

    King, J. C.

    1976-01-01

    The generation of satellite coverage patterns is facilitated by three basic strategies: use of a simplified physical model, permitting rapid closed-form calculation; separation of earth rotation and nodal precession from initial geometric analyses; and use of symmetries to construct traces of indefinite length by repetitive transposition of basic one-quadrant elements. The complete coverage patterns generated consist of a basic nadir trace plus a number of associated off-nadir traces, one for each sensor swath edge to be delineated. Each trace is generated by transposing one or two of the basic quadrant elements into a circle on a nonrotating earth model sphere, after which the circle is expanded into the actual 'helical' pattern by adding rotational displacements to the longitude coordinates. The procedure adapts to the important periodic coverage cases by direct insertion of the characteristic integers N and R (days and orbital revolutions, respectively, per coverage period).

  17. Generation of Venus reporter knock-in mice revealed MAGI-2 expression patterns in adult mice.

    PubMed

    Ihara, Kan-ichiro; Nishimura, Tomoki; Fukuda, Tomokazu; Ookura, Tetsuya; Nishimori, Katsuhiko

    2012-01-01

    The membrane-associated guanylate kinase inverted 2 (MAGI-2) protein, which is known to localize at the tight junction of epithelial cells, contains multiple copies of the PDZ and WW domains in its structure. Although the expression pattern of Magi2 mRNA in representative organs has been previously published, its detailed cellular distribution at the histological level remains unknown. Such detailed information would be useful to clarify the biological function of MAGI-2. Here, we report the generation of Venus reporter knock-in mice for Magi2 in which exon 6 of the gene was substituted by the Venus-encoding sequence. We detected the expression of the Venus reporter protein in kidney podocytes from these knock-in mice. We also detected Venus reporter protein expression in spermatids within the testes and within neurons in various regions of the brain. Detection of the reporter protein from these diverse locations indicated the endogenous expression of MAGI-2 in these tissues. Our data suggested a potential function of MAGI-2 in the glomerular filtration process and sperm cell maturation. These data indicate that the Venus reporter knock-in mouse for Magi2 is a useful model for the further study of Magi2 gene function.

  18. Energy efficient walking with central pattern generators: from passive dynamic walking to biologically inspired control.

    PubMed

    Verdaasdonk, B W; Koopman, H F J M; van der Helm, F C T

    2009-07-01

    Like human walking, passive dynamic walking-i.e. walking down a slope with no actuation except gravity-is energy efficient by exploiting the natural dynamics. In the animal world, neural oscillators termed central pattern generators (CPGs) provide the basic rhythm for muscular activity in locomotion. We present a CPG model, which automatically tunes into the resonance frequency of the passive dynamics of a bipedal walker, i.e. the CPG model exhibits resonance tuning behavior. Each leg is coupled to its own CPG, controlling the hip moment of force. Resonance tuning above the endogenous frequency of the CPG-i.e. the CPG's eigenfrequency-is achieved by feedback of both limb angles to their corresponding CPG, while integration of the limb angles provides resonance tuning at and below the endogenous frequency of the CPG. Feedback of the angular velocity of both limbs to their corresponding CPG compensates for the time delay in the loop coupling each limb to its CPG. The resonance tuning behavior of the CPG model allows the gait velocity to be controlled by a single parameter, while retaining the energy efficiency of passive dynamic walking.

  19. Energy efficient and robust rhythmic limb movement by central pattern generators.

    PubMed

    Verdaasdonk, B W; Koopman, H F J M; Helm, F C T Van Der

    2006-05-01

    Humans show great energy efficiency and robustness in rhythmic tasks, such as walking and arm swinging. In this study a mathematical model of rhythmic limb movement is presented, which shows that tight local coupling of Central Pattern Generators (CPGs) to limbs could explain part of this behavior. Afferent feedback to flexor and extensor centers of the CPG is crucial in providing energy efficiency by means of resonance tuning. Feedback of positional information provides resonance tuning above the endogenous frequency of the CPG. Integral feedback provides resonance tuning at and below the endogenous frequency. Feedback of velocity information is necessary to compensate for the time delay in the loop, coupling limb to CPG; without velocity feedback bi-stability occurs and resonance tuning is not possible at high movement frequencies. The concepts of energy efficient and robust control of rhythmic limb movements are also applicable to robotics. It is the first CPG model, which provides resonance tuning at natural limb frequencies above and below its endogenous frequency.

  20. Modulation of respiratory sinus arrhythmia in rats with central pattern generator hardware.

    PubMed

    Nogaret, Alain; Zhao, Le; Moraes, Davi J A; Paton, Julian F R

    2013-01-15

    We report on the modulation of respiratory sinus arrhythmia in rats with central pattern generator (CPG) hardware made of silicon neurons. The neurons are made to compete through mutually inhibitory synapses to provide timed electrical oscillations that stimulate the peripheral end of vagus nerve at specific points of the respiratory cycle: the inspiratory phase (φ(1)), the early expiratory phase (φ(2)) and the late expiratory phase (φ(3)). In this way the CPG hardware mimics the neuron populations in the brainstem which through connections with cardiac vagal motoneurones control respiratory sinus arrhythmia (RSA). Here, we time the output of the CPG hardware from the phrenic nerve activity recorded from rats while monitoring heart rate changes evoked by vagal nerve stimulation (derived from ECG) controlled by the CPG. This neuroelectric stimulation has the effect of reducing the heart rate and increasing the arterial pressure. The artificially induced RSA strongly depends on the timing of pulses within the breathing cycle. It is strongest when the vagus nerve is stimulated during the inspiratory phase (φ(1)) or the early expiratory phase (φ(2)) in which case the heart rate slows by 50% of the normal rate. Heart rate modulation is less when the same exact stimulus is applied during the late expiratory phase (φ(3)). These trials show that neurostimulation by CPG hardware can augment respiratory sinus arrhythmia. The CPG hardware technology opens a new line of therapeutic possibilities for prosthetic devices that restore RSA in patients where respiratory-cardiac coupling has been lost.

  1. The contribution of a central pattern generator in a reflex-based neuromuscular model.

    PubMed

    Dzeladini, Florin; van den Kieboom, Jesse; Ijspeert, Auke

    2014-01-01

    Although the concept of central pattern generators (CPGs) controlling locomotion in vertebrates is widely accepted, the presence of specialized CPGs in human locomotion is still a matter of debate. An interesting numerical model developed in the 90s' demonstrated the important role CPGs could play in human locomotion, both in terms of stability against perturbations, and in terms of speed control. Recently, a reflex-based neuro-musculo-skeletal model has been proposed, showing a level of stability to perturbations similar to the previous model, without any CPG components. Although exhibiting striking similarities with human gaits, the lack of CPG makes the control of speed/step length in the model difficult. In this paper, we hypothesize that a CPG component will offer a meaningful way of controlling the locomotion speed. After introducing the CPG component in the reflex model, and taking advantage of the resulting properties, a simple model for gait modulation is presented. The results highlight the advantages of a CPG as feedforward component in terms of gait modulation.

  2. Sub-wavelength pattern generation by laser direct writing via repeated irradiation.

    PubMed

    Klein-Wiele, Jan-Hendrik; Simon, Peter

    2013-01-14

    A simple technique is presented allowing the fabrication of high density periodic patterns via direct laser ablation. Applying fluence control for reducing the ablated feature sizes combined with lateral translation of an interference pattern between two (or more) irradiation cycles, sub-wavelength period patterns (< 200 nm) are created. Variation of the amount and direction of translation and the applied intensities during subsequent irradiation steps leads to variable pattern design as demonstrated for polymeric and silicon samples.

  3. Parenting across Racial and Class Lines: Assortative Mating Patterns of New Parents Who Are Married, Cohabiting, Dating or No Longer Romantically Involved

    ERIC Educational Resources Information Center

    Goldstein, Joshua R.; Harknett, Kristen

    2006-01-01

    We examine the assortative mating patterns of new parents who are married, cohabiting, romantically involved and no longer romantically involved. Using data from the Fragile Families and Child Wellbeing study, we find that relationship status at the time of a birth depends mainly on father's race rather than on whether mother and father's…

  4. Versatile pattern generation of periodic, high aspect ratio Si nanostructure arrays with sub-50-nm resolution on a wafer scale

    PubMed Central

    2013-01-01

    We report on a method of fabricating variable patterns of periodic, high aspect ratio silicon nanostructures with sub-50-nm resolution on a wafer scale. The approach marries step-and-repeat nanoimprint lithography (NIL) and metal-catalyzed electroless etching (MCEE), enabling near perfectly ordered Si nanostructure arrays of user-defined patterns to be controllably and rapidly generated on a wafer scale. Periodic features possessing circular, hexagonal, and rectangular cross-sections with lateral dimensions down to sub-50 nm, in hexagonal or square array configurations and high array packing densities up to 5.13 × 107 structures/mm2 not achievable by conventional UV photolithography are fabricated using this top-down approach. By suitably tuning the duration of catalytic etching, variable aspect ratio Si nanostructures can be formed. As the etched Si pattern depends largely on the NIL mould which is patterned by electron beam lithography (EBL), the technique can be used to form patterns not possible with self-assembly methods, nanosphere, and interference lithography for replication on a wafer scale. Good chemical resistance of the nanoimprinted mask and adhesion to the Si substrate facilitate good pattern transfer and preserve the smooth top surface morphology of the Si nanostructures as shown in TEM. This approach is suitable for generating Si nanostructures of controlled dimensions and patterns, with high aspect ratio on a wafer level suitable for semiconductor device production. PMID:24289275

  5. Hydrogen peroxide generated by NADPH oxidase is involved in high blue-light-induced chloroplast avoidance movements in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Wen, Feng; Xing, Da; Zhang, Lingrui

    2009-08-01

    One of the most important functions of blue light is to induce chloroplast movements by reducing the damage to photosynthetic machinery under excess light. Hydrogen peroxide (H2O2), generated by various environmental stimuli, can act as a signaling molecule that regulates a number of developmental processes and environmental responses. To investigate whether H2O2 is involved in high blue light-induced chloroplast avoidance movements, we use luminescence spectrometer to observe H2O2 generation with the assistance of the fluorescence probe dichlorofluorescin diacetate (H2DCF-DA). After treatment with high blue light, a large quantity of H2O2 indicated by the fluorescence intensity of DCF is produced in a dose-dependent manner in leaf strip of Arabidopsis. Enzymatic assay shows that the activity of NADPH oxidase, which is a major site for H2O2 generation, also rapidly increases in treated strips. Exogenously applied H2O2 can promote the high blue light-induced chloroplast movements. Moreover, high blue light-induced H2O2 generation can be abolished completely by addition of exogenous catalase (CAT), and partly by diphenylene iodonium (DPI) and dichlorophenyl dimethylurea (DCMU), which are an NADPH oxidase inhibitor and a blocker of electron transport chain. And subsequent chloroplast movements can be abolished by CAT and DPI, but not by DCMU. These results presented here suggested that high blue light can induce oxidative burst, and NADPH oxidase as a major producer for H2O2 is involved in blue light-induced chloroplast avoidance movements.

  6. Involvement of the Cav3.2 T-type calcium channel in thalamic neuron discharge patterns

    PubMed Central

    2011-01-01

    Background Mice that have defects in their low-threshold T-type calcium channel (T-channel) genes show altered pain behaviors. The changes in the ratio of nociceptive neurons and the burst firing property of reticular thalamic (RT) and ventroposterior (VP) neurons in Cav3.2 knockout (KO) mice were studied to test the involvement of thalamic T-channel and burst firing activity in pain function. Results Under pentobarbital or urethane anesthesia, the patterns of tonic and burst firings were recorded in functionally characterized RT and VPL neurons of Cav3.2 KO mice. Many RT neurons were nociceptive (64% under pentobarbital anesthesia and 50% under urethane anesthesia). Compared to their wild-type (WT) controls, fewer nociceptive RT neurons were found in Cav3.2 KO mice. Both nociceptive and tactile RT neurons showed fewer bursts in Cav3.2 KO mice. Within a burst, RT neurons of Cav3.2 KO mice had a lower spike frequency and less-prominent accelerando-decelerando change. In contrast, VP neurons of Cav3.2 KO mice showed a higher ratio of bursts and a higher discharge rate within a burst than those of the WT control. In addition, the long-lasting tonic firing episodes in RT neurons of the Cav3.2 KO had less stereotypic regularity than their counterparts in WT mice. Conclusions RT might be important in nociception of the mouse. In addition, we showed an important role of Cav3.2 subtype of T-channel in RT burst firing pattern. The decreased occurrence and slowing of the bursts in RT neurons might cause the increased VP bursts. These changes would be factors contributing to alternation of pain behavior in the Cav3.2 KO mice. PMID:21639922

  7. Decomposing risk: landscape structure and wolf behavior generate different predation patterns in two sympatric ungulates.

    PubMed

    Gervasi, Vincenzo; Sand, Hakan; Zimmermann, Barbara; Mattisson, Jenny; Wabakken, Petter; Linnell, John D C

    2013-10-01

    Recolonizing carnivores can have a large impact on the status of wild ungulates, which have often modified their behavior in the absence of predation. Therefore, understanding the dynamics of reestablished predator-prey systems is crucial to predict their potential ecosystem effects. We decomposed the spatial structure of predation by recolonizing wolves (Canis lupus) on two sympatric ungulates, moose (Alces alces) and roe deer (Capreolus capreolus), in Scandinavia during a 10-year study. We monitored 18 wolves with GPS collars, distributed over 12 territories, and collected records from predation events. By using conditional logistic regression, we assessed the contributions of three main factors, the utilization patterns of each wolf territory, the spatial distribution of both prey species, and fine-scale landscape structure, in determining the spatial structure of moose and roe deer predation risk. The reestablished predator-prey system showed a remarkable spatial variation in kill occurrence at the intra-territorial level, with kill probabilities varying by several orders of magnitude inside the same territory. Variation in predation risk was evident also when a spatially homogeneous probability for a wolf to encounter a prey was simulated. Even inside the same territory, with the same landscape structure, and when exposed to predation by the same wolves, the two prey species experienced an opposite spatial distribution of predation risk. In particular, increased predation risk for moose was associated with open areas, especially clearcuts and young forest stands, whereas risk was lowered for roe deer in the same habitat types. Thus, fine-scale landscape structure can generate contrasting predation risk patterns in sympatric ungulates, so that they can experience large differences in the spatial distribution of risk and refuge areas when exposed to predation by a recolonizing predator. Territories with an earlier recolonization were not associated with a lower

  8. Physiological and pathophysiological interactions between the respiratory central pattern generator and the sympathetic nervous system

    PubMed Central

    Molkov, Yaroslav I.; Zoccal, Daniel B.; Baekey, David M.; Abdala, Ana P.L.; Machado, Benedito H.; Dick, Thomas E.; Paton, Julian F.R.; Rybak, Ilya A.

    2015-01-01

    Respiratory modulation seen in the sympathetic nerve activity (SNA) implies that the respiratory and sympathetic networks interact. During hypertension elicited by chronic intermittent hypoxia (CIH), the SNA displays an enhanced respiratory modulation reflecting strengthened interactions between the networks. In this chapter, we review a series of experimental and modeling studies that help elucidate possible mechanisms of sympatho-respiratory coupling. We conclude that this coupling significantly contributes to both the sympathetic baroreflex and the augmented sympathetic activity after exposure to CIH. This conclusion is based on the following findings. (1) Baroreceptor activation results in perturbation of the respiratory pattern via transient activation of postinspiratory neurons in the Bötzinger complex (BötC). The same BötC neurons are involved in the respiratory modulation of SNA, and hence provide an additional pathway for the sympathetic baroreflex. (2) Under hypercapnia, phasic activation of abdominal motor nerves (AbN) is accompanied by synchronous discharges in SNA due to the common source of this rhythmic activity in the retrotrapezoid nucleus (RTN). CIH conditioning increases the CO2 sensitivity of central chemoreceptors in the RTN which results in the emergence of AbN and SNA discharges under normocapnic conditions similar to those observed during hypercapnia in naïve animals. Thus, respiratory–sympathetic interactions play an important role in defining sympathetic output and significantly contribute to the sympathetic activity and hypertension under certain physiological or pathophysiological conditions, and the theoretical framework presented may be instrumental in understanding of malfunctioning control of sympathetic activity in a variety of disease states. PMID:25194190

  9. Physiological and pathophysiological interactions between the respiratory central pattern generator and the sympathetic nervous system.

    PubMed

    Molkov, Yaroslav I; Zoccal, Daniel B; Baekey, David M; Abdala, Ana P L; Machado, Benedito H; Dick, Thomas E; Paton, Julian F R; Rybak, Ilya A

    2014-01-01

    Respiratory modulation seen in the sympathetic nerve activity (SNA) implies that the respiratory and sympathetic networks interact. During hypertension elicited by chronic intermittent hypoxia (CIH), the SNA displays an enhanced respiratory modulation reflecting strengthened interactions between the networks. In this chapter, we review a series of experimental and modeling studies that help elucidate possible mechanisms of sympatho-respiratory coupling. We conclude that this coupling significantly contributes to both the sympathetic baroreflex and the augmented sympathetic activity after exposure to CIH. This conclusion is based on the following findings. (1) Baroreceptor activation results in perturbation of the respiratory pattern via transient activation of postinspiratory neurons in the Bötzinger complex (BötC). The same BötC neurons are involved in the respiratory modulation of SNA, and hence provide an additional pathway for the sympathetic baroreflex. (2) Under hypercapnia, phasic activation of abdominal motor nerves (AbN) is accompanied by synchronous discharges in SNA due to the common source of this rhythmic activity in the retrotrapezoid nucleus (RTN). CIH conditioning increases the CO2 sensitivity of central chemoreceptors in the RTN which results in the emergence of AbN and SNA discharges under normocapnic conditions similar to those observed during hypercapnia in naïve animals. Thus, respiratory-sympathetic interactions play an important role in defining sympathetic output and significantly contribute to the sympathetic activity and hypertension under certain physiological or pathophysiological conditions, and the theoretical framework presented may be instrumental in understanding of malfunctioning control of sympathetic activity in a variety of disease states.

  10. Real-time biomimetic Central Pattern Generators in an FPGA for hybrid experiments

    PubMed Central

    Ambroise, Matthieu; Levi, Timothée; Joucla, Sébastien; Yvert, Blaise; Saïghi, Sylvain

    2013-01-01

    This investigation of the leech heartbeat neural network system led to the development of a low resources, real-time, biomimetic digital hardware for use in hybrid experiments. The leech heartbeat neural network is one of the simplest central pattern generators (CPG). In biology, CPG provide the rhythmic bursts of spikes that form the basis for all muscle contraction orders (heartbeat) and locomotion (walking, running, etc.). The leech neural network system was previously investigated and this CPG formalized in the Hodgkin–Huxley neural model (HH), the most complex devised to date. However, the resources required for a neural model are proportional to its complexity. In response to this issue, this article describes a biomimetic implementation of a network of 240 CPGs in an FPGA (Field Programmable Gate Array), using a simple model (Izhikevich) and proposes a new synapse model: activity-dependent depression synapse. The network implementation architecture operates on a single computation core. This digital system works in real-time, requires few resources, and has the same bursting activity behavior as the complex model. The implementation of this CPG was initially validated by comparing it with a simulation of the complex model. Its activity was then matched with pharmacological data from the rat spinal cord activity. This digital system opens the way for future hybrid experiments and represents an important step toward hybridization of biological tissue and artificial neural networks. This CPG network is also likely to be useful for mimicking the locomotion activity of various animals and developing hybrid experiments for neuroprosthesis development. PMID:24319408

  11. Setting the Pace: New Insights into Central Pattern Generator Interactions in Box Jellyfish Swimming

    PubMed Central

    Stöckl, Anna Lisa; Petie, Ronald; Nilsson, Dan-Eric

    2011-01-01

    Central Pattern Generators (CPGs) produce rhythmic behaviour across all animal phyla. Cnidarians, which have a radially symmetric nervous system and pacemaker centres in multiples of four, provide an interesting comparison to bilaterian animals for studying the coordination between CPGs. The box jellyfish Tripedalia cystophora is remarkable among cnidarians due to its most elaborate visual system. Together with their ability to actively swim and steer, they use their visual system for multiple types of behaviour. The four swim CPGs are directly regulated by visual input. In this study, we addressed the question of how the four pacemaker centres of this radial symmetric cnidarian interact. We based our investigation on high speed camera observations of the timing of swim pulses of tethered animals (Tripedalia cystophora) with one or four rhopalia, under different simple light regimes. Additionally, we developed a numerical model of pacemaker interactions based on the inter pulse interval distribution of animals with one rhopalium. We showed that the model with fully resetting coupling and hyperpolarization of the pacemaker potential below baseline fitted the experimental data best. Moreover, the model of four swim pacemakers alone underscored the proportion of long inter pulse intervals (IPIs) considerably. Both in terms of the long IPIs as well as the overall swim pulse distribution, the simulation of two CPGs provided a better fit than that of four. We therefore suggest additional sources of pacemaker control than just visual input. We provide guidelines for future research on the physiological linkage of the cubozoan CPGs and show the insight from bilaterian CPG research, which show that pacemakers have to be studied in their bodily and nervous environment to capture all their functional features, are also manifest in cnidarians. PMID:22073288

  12. Real-time biomimetic Central Pattern Generators in an FPGA for hybrid experiments.

    PubMed

    Ambroise, Matthieu; Levi, Timothée; Joucla, Sébastien; Yvert, Blaise; Saïghi, Sylvain

    2013-01-01

    This investigation of the leech heartbeat neural network system led to the development of a low resources, real-time, biomimetic digital hardware for use in hybrid experiments. The leech heartbeat neural network is one of the simplest central pattern generators (CPG). In biology, CPG provide the rhythmic bursts of spikes that form the basis for all muscle contraction orders (heartbeat) and locomotion (walking, running, etc.). The leech neural network system was previously investigated and this CPG formalized in the Hodgkin-Huxley neural model (HH), the most complex devised to date. However, the resources required for a neural model are proportional to its complexity. In response to this issue, this article describes a biomimetic implementation of a network of 240 CPGs in an FPGA (Field Programmable Gate Array), using a simple model (Izhikevich) and proposes a new synapse model: activity-dependent depression synapse. The network implementation architecture operates on a single computation core. This digital system works in real-time, requires few resources, and has the same bursting activity behavior as the complex model. The implementation of this CPG was initially validated by comparing it with a simulation of the complex model. Its activity was then matched with pharmacological data from the rat spinal cord activity. This digital system opens the way for future hybrid experiments and represents an important step toward hybridization of biological tissue and artificial neural networks. This CPG network is also likely to be useful for mimicking the locomotion activity of various animals and developing hybrid experiments for neuroprosthesis development.

  13. Designing responsive pattern generators: stable heteroclinic channel cycles for modeling and control.

    PubMed

    Horchler, Andrew D; Daltorio, Kathryn A; Chiel, Hillel J; Quinn, Roger D

    2015-02-25

    A striking feature of biological pattern generators is their ability to respond immediately to multisensory perturbations by modulating the dwell time at a particular phase of oscillation, which can vary force output, range of motion, or other characteristics of a physical system. Stable heteroclinic channels (SHCs) are a dynamical architecture that can provide such responsiveness to artificial devices such as robots. SHCs are composed of sequences of saddle equilibrium points, which yields exquisite sensitivity. The strength of the vector fields in the neighborhood of these equilibria determines the responsiveness to perturbations and how long trajectories dwell in the vicinity of a saddle. For SHC cycles, the addition of stochastic noise results in oscillation with a regular mean period. In this paper, we parameterize noise-driven Lotka-Volterra SHC cycles such that each saddle can be independently designed to have a desired mean sub-period. The first step in the design process is an analytic approximation, which results in mean sub-periods that are within 2% of the specified sub-period for a typical parameter set. Further, after measuring the resultant sub-periods over sufficient numbers of cycles, the magnitude of the noise can be adjusted to control the mean period with accuracy close to that of the integration step size. With these relationships, SHCs can be more easily employed in engineering and modeling applications. For applications that require smooth state transitions, this parameterization permits each state's distribution of periods to be independently specified. Moreover, for modeling context-dependent behaviors, continuously varying inputs in each state dimension can rapidly precipitate transitions to alter frequency and phase.

  14. Bidirectional plasticity of pontine pneumotaxic postinspiratory drive: implication for a pontomedullary respiratory central pattern generator.

    PubMed

    Poon, Chi-Sang; Song, Gang

    2014-01-01

    The "pneumotaxic center" in the rostral dorsolateral pons as delineated by Lumsden nine decades ago is known to play an important role in promoting the inspiratory off-switch (IOS) for inspiratory-expiratory phase transition as a fail-safe mechanism for preventing apneusis in the absence of vagal input. Traditionally, the pontine pneumotaxic mechanism has been thought to contribute a tonic descending input that lowers the IOS threshold in medullary respiratory central pattern generator (rCPG) circuits, but otherwise does not constitute part of the rCPG. Recent evidence indicates that descending input from the Kölliker-Fuse nucleus (KFN) within the pneumotaxic center is essential for gating the postinspiratory phase of the three-phase respiratory rhythm to control the IOS in vagotomized animals. A critical question arising is whether such a descending pneumotaxic input from KFN that drives postinspiratory activity is tonic (null hypothesis) or rhythmic with postinspiratory phase modulation (alternative hypothesis). Here, we show that multifarious evidence reported in the literature collectively indicates that the descending pneumotaxic input may exhibit NMDA receptor-dependent short-term plasticity in the form of a biphasic neural differentiator that bidirectionally and phase-selectively modulates postinspiratory phase duration in response to vagal and peripheral chemoreceptor inputs independent of the responses in inspiratory and late-expiratory activities. The phase-selectivity property of the descending pneumotaxic input implicates a population of pontine early-expiratory (postinspiratory/expiratory-decrementing) neurons as the most likely neural correlate of the pneumotaxic mechanism that drives post-I activity, suggesting that the pontine pneumotaxic mechanism may be an integral part of a pontomedullary rCPG that underlies the three-phase respiratory rhythm.

  15. Involvement of dachshund and Distal-less in distal pattern formation of the cricket leg during regeneration.

    PubMed

    Ishimaru, Yoshiyasu; Nakamura, Taro; Bando, Tetsuya; Matsuoka, Yuji; Ohuchi, Hideyo; Noji, Sumihare; Mito, Taro

    2015-02-11

    Cricket nymphs have the remarkable ability to regenerate a functional leg following amputation, indicating that the regenerating blastemal cells contain information for leg morphology. However, the molecular mechanisms that underlie regeneration of leg patterns remain poorly understood. Here, we analyzed phenotypes of the tibia and tarsus (three tarsomeres) obtained by knockdown with regeneration-dependent RNA interference (rdRNAi) against Gryllus dachshund (Gb'dac) and Distal-less (Gb'Dll). We found that depletion of Gb'Dll mRNA results in loss of the tarsal segments, while rdRNAi against Gb'dac shortens the tibia at the two most distal tarsomeres. These results indicate that Gb'Dll expression is indispensable for formation of the tarsus, while Gb'dac expression is necessary for elongation of the tibia and formation of the most proximal tarsomere. These findings demonstrate that mutual transcriptional regulation between the two is indispensable for formation of the tarsomeres, whereas Gb'dac is involved in determination of tibial size through interaction with Gb'ds/Gb'ft.

  16. Involvement of dachshund and Distal-less in distal pattern formation of the cricket leg during regeneration

    PubMed Central

    Ishimaru, Yoshiyasu; Nakamura, Taro; Bando, Tetsuya; Matsuoka, Yuji; Ohuchi, Hideyo; Noji, Sumihare; Mito, Taro

    2015-01-01

    Cricket nymphs have the remarkable ability to regenerate a functional leg following amputation, indicating that the regenerating blastemal cells contain information for leg morphology. However, the molecular mechanisms that underlie regeneration of leg patterns remain poorly understood. Here, we analyzed phenotypes of the tibia and tarsus (three tarsomeres) obtained by knockdown with regeneration-dependent RNA interference (rdRNAi) against Gryllus dachshund (Gb'dac) and Distal-less (Gb'Dll). We found that depletion of Gb'Dll mRNA results in loss of the tarsal segments, while rdRNAi against Gb'dac shortens the tibia at the two most distal tarsomeres. These results indicate that Gb'Dll expression is indispensable for formation of the tarsus, while Gb'dac expression is necessary for elongation of the tibia and formation of the most proximal tarsomere. These findings demonstrate that mutual transcriptional regulation between the two is indispensable for formation of the tarsomeres, whereas Gb'dac is involved in determination of tibial size through interaction with Gb'ds/Gb'ft. PMID:25669615

  17. Massive alterations of the methylation patterns around DNA transposons in the first four generations of a newly formed wheat allohexaploid.

    PubMed

    Yaakov, Beery; Kashkush, Khalil

    2011-01-01

    Rapid and reproducible genomic changes can be induced during the early stages of the life of nascent allopolyploid species. In a previous study, it was shown that following allopolyploidization, cytosine methylation changes can affect up to 11% of the wheat genome. However, the methylation patterns around transposable elements (TEs) were never studied in detail. We used transposon methylation display (TMD) to assess the methylation patterns of CCGG sites flanking three TE families (Balduin, Apollo, and Thalos) in the first four generations of a newly formed wheat allohexaploid. In addition, transposon display (TD), using a methylation-insensitive restriction enzyme, was applied to search for genomic rearrangements at the TE insertion sites. We observed that up to 54% of CCGG sites flanking the three TE families showed changes in methylation patterns in the first four generations of a newly formed wheat allohexaploid, where hypermethylation was predominant. Over 70% of the changes in TMD patterns occurred in the first two generations of the newly formed allohexaploid. Furthermore, analysis of 555 TE insertion sites by TD and 18 cases by site-specific PCR revealed a full additive pattern in the allohexaploid, an indication for lack of massive rearrangements. These data indicate that following allopolyplodization, DNA-TE insertion sites can undergo a significantly high level of methylation changes compared with methylation changes of other genomic sequences.

  18. Influence of bromine substitution pattern on the singlet oxygen generation efficiency of two-photon absorbing chromophores.

    PubMed

    Lanoë, Pierre-Henri; Gallavardin, Thibault; Dupin, Aurore; Maury, Olivier; Baldeck, Patrice L; Lindgren, Mikael; Monnereau, Cyrille; Andraud, Chantal

    2012-08-21

    A molecular engineering strategy based on rational variations of the bromine substitution pattern in two-photon absorbing singlet oxygen sensitizers allows studying the relations that exist between the positioning of an inter-system crossing promoter on the charge-transfer chromophore and its ability to generate singlet oxygen.

  19. Transcriptome profiling of radish (Raphanus sativus L.) root and identification of genes involved in response to Lead (Pb) stress with next generation sequencing.

    PubMed

    Wang, Yan; Xu, Liang; Chen, Yinglong; Shen, Hong; Gong, Yiqin; Limera, Cecilia; Liu, Liwang

    2013-01-01

    Lead (Pb), one of the most toxic heavy metals, can be absorbed and accumulated by plant roots and then enter the food chain resulting in potential health risks for human beings. The radish (Raphanus sativus L.) is an important root vegetable crop with fleshy taproots as the edible parts. Little is known about the mechanism by which radishes respond to Pb stress at the molecular level. In this study, Next Generation Sequencing (NGS)-based RNA-seq technology was employed to characterize the de novo transcriptome of radish roots and identify differentially expressed genes (DEGs) during Pb stress. A total of 68,940 assembled unique transcripts including 33,337 unigenes were obtained from radish root cDNA samples. Based on the assembled de novo transcriptome, 4,614 DEGs were detected between the two libraries of untreated (CK) and Pb-treated (Pb1000) roots. Gene Ontology (GO) and pathway enrichment analysis revealed that upregulated DEGs under Pb stress are predominately involved in defense responses in cell walls and glutathione metabolism-related processes, while downregulated DEGs were mainly involved in carbohydrate metabolism-related pathways. The expression patterns of 22 selected genes were validated by quantitative real-time PCR, and the results were highly accordant with the Solexa analysis. Furthermore, many candidate genes, which were involved in defense and detoxification mechanisms including signaling protein kinases, transcription factors, metal transporters and chelate compound biosynthesis related enzymes, were successfully identified in response to heavy metal Pb. Identification of potential DEGs involved in responses to Pb stress significantly reflected alterations in major biological processes and metabolic pathways. The molecular basis of the response to Pb stress in radishes was comprehensively characterized. Useful information and new insights were provided for investigating the molecular regulation mechanism of heavy metal Pb accumulation and

  20. A 3D Optical Surface Profilometer Using a Dual-Frequency Liquid Crystal-Based Dynamic Fringe Pattern Generator

    PubMed Central

    Joo, Kyung-Il; Kim, Mugeon; Park, Min-Kyu; Park, Heewon; Kim, Byeonggon; Hahn, JoonKu; Kim, Hak-Rin

    2016-01-01

    We propose a liquid crystal (LC)-based 3D optical surface profilometer that can utilize multiple fringe patterns to extract an enhanced 3D surface depth profile. To avoid the optical phase ambiguity and enhance the 3D depth extraction, 16 interference patterns were generated by the LC-based dynamic fringe pattern generator (DFPG) using four-step phase shifting and four-step spatial frequency varying schemes. The DFPG had one common slit with an electrically controllable birefringence (ECB) LC mode and four switching slits with a twisted nematic LC mode. The spatial frequency of the projected fringe pattern could be controlled by selecting one of the switching slits. In addition, moving fringe patterns were obtainable by applying voltages to the ECB LC layer, which varied the phase difference between the common and the selected switching slits. Notably, the DFPG switching time required to project 16 fringe patterns was minimized by utilizing the dual-frequency modulation of the driving waveform to switch the LC layers. We calculated the phase modulation of the DFPG and reconstructed the depth profile of 3D objects using a discrete Fourier transform method and geometric optical parameters. PMID:27801812

  1. The Employment of Structures and Work Patterns in Organizations Involved in Modern, Complex, Multi-National Operations

    DTIC Science & Technology

    2011-06-01

    getting back, as soon as possible, into the complex domain. Choreographed Choreographed patterns provide a generic approach to the construction of the...be adaptable and tailorable to the specific circumstances. Choreographed patterns also need to be understood (and characterised) informatically...Configurations • Parameters • Neither mechanical nor free-play • Not rigid process, but choreographed patterns: − Rules, models and templates

  2. Effect of HF Heating Array Directivity Pattern on the Frequency Response of Generated ELF/VLF.

    DTIC Science & Technology

    1983-01-01

    hhEEE|hhEE 1H ; 11:j28 111125 . mm 11111 II ll1 111 .8 MICROCOPY RESOLUTION TESI CHART I fJC ’RL_-SCI-475l I( .-cmon Numters: 1.5.1. 3.1.4, 3.2.1,.3.3...the high power HF heating facility at the Arecibo Observatory in Puerto Rico. The pattern was calculated using pattern multi- plication and method of...high power HF heating facility at the Arecibo Observatory in Puerto Rico. The pattern was calculated using pattern multiplication and method of

  3. Vocal behavior and vocal central pattern generator organization diverge among toadfishes.

    PubMed

    Chagnaud, Boris P; Bass, Andrew H

    2014-01-01

    Among fishes, acoustic communication is best studied in toadfishes, a single order and family that includes species commonly known as toadfish and midshipman. However, there is a lack of comparative anatomical and physiological studies, making it difficult to identify both shared and derived mechanisms of vocalization among toadfishes. Here, vocal nerve labeling and intracellular in vivo recording and staining delineated the hindbrain vocal network of the Gulf toadfish Opsanus beta. Dextran-biotin labeling of the vocal nerve or intracellular neurobiotin fills of motoneurons delineated a midline vocal motor nucleus (VMN). Motoneurons showed bilaterally extensive dendritic arbors both within and lateral to the paired motor nuclei. The motoneuron activity matched that of the spike-like vocal nerve motor volley that determines the natural call duration and frequency. Ipsilateral vocal nerve labeling with biocytin or neurobiotin yielded dense bilateral transneuronal filling of motoneurons and coextensive columns of premotor neurons. These premotor neurons generated pacemaker-like action potentials matched 1:1 with vocal nerve and motoneuron firing. Transneuronal transport further revealed connectivity within and between the pacemaker-motor circuit and a rostral prepacemaker nucleus. Unlike the pacemaker-motor circuit, prepacemaker firing did not match the frequency of vocal nerve activity but instead was predictive of the duration of the vocal nerve volley that codes for call duration. Transneuronally labeled terminal-like boutons also occurred in auditory-recipient hindbrain nuclei, including neurons innervating the inner ear and lateral line organs. Together with studies of midshipman, we propose that separate premotor populations coding vocal frequency and duration with direct premotor coupling to auditory-lateral line nuclei are plesiomorphic characters for toadfishes. Unlike in midshipman, transneuronal labeling in toadfishes reveals an expansive column of

  4. Beyond the MHC: A canine model of dermatomyositis shows a complex pattern of genetic risk involving novel loci

    PubMed Central

    Evans, Jacquelyn M.; Hill, Cody M.; Anderson, Kendall J.

    2017-01-01

    Juvenile dermatomyositis (JDM) is a chronic inflammatory myopathy and vasculopathy driven by genetic and environmental influences. Here, we investigated the genetic underpinnings of an analogous, spontaneous disease of dogs also termed dermatomyositis (DMS). As in JDM, we observed a significant association with a haplotype of the major histocompatibility complex (MHC) (DLA-DRB1*002:01/-DQA1*009:01/-DQB1*001:01), particularly in homozygosity (P-val = 0.0001). However, the high incidence of the haplotype among healthy dogs indicated that additional genetic risk factors are likely involved in disease progression. We conducted genome-wide association studies in two modern breeds having common ancestry and detected strong associations with novel loci on canine chromosomes 10 (P-val = 2.3X10-12) and 31 (P-val = 3.95X10-8). Through whole genome resequencing, we identified primary candidate polymorphisms in conserved regions of PAN2 (encoding p.Arg492Cys) and MAP3K7CL (c.383_392ACTCCACAAA>GACT) on chromosomes 10 and 31, respectively. Analyses of these polymorphisms and the MHC haplotypes revealed that nine of 27 genotypic combinations confer high or moderate probability of disease and explain 93% of cases studied. The pattern of disease risk across PAN2 and MAP3K7CL genotypes provided clear evidence for a significant epistatic foundation for this disease, a risk further impacted by MHC haplotypes. We also observed a genotype-phenotype correlation wherein an earlier age of onset is correlated with an increased number of risk alleles at PAN2 and MAP3K7CL. High frequencies of multiple genetic risk factors are unique to affected breeds and likely arose coincident with artificial selection for desirable phenotypes. Described herein is the first three-locus association with a complex canine disease and two novel loci that provide targets for exploration in JDM and related immunological dysfunction. PMID:28158183

  5. Beyond the MHC: A canine model of dermatomyositis shows a complex pattern of genetic risk involving novel loci.

    PubMed

    Evans, Jacquelyn M; Noorai, Rooksana E; Tsai, Kate L; Starr-Moss, Alison N; Hill, Cody M; Anderson, Kendall J; Famula, Thomas R; Clark, Leigh Anne

    2017-02-01

    Juvenile dermatomyositis (JDM) is a chronic inflammatory myopathy and vasculopathy driven by genetic and environmental influences. Here, we investigated the genetic underpinnings of an analogous, spontaneous disease of dogs also termed dermatomyositis (DMS). As in JDM, we observed a significant association with a haplotype of the major histocompatibility complex (MHC) (DLA-DRB1*002:01/-DQA1*009:01/-DQB1*001:01), particularly in homozygosity (P-val = 0.0001). However, the high incidence of the haplotype among healthy dogs indicated that additional genetic risk factors are likely involved in disease progression. We conducted genome-wide association studies in two modern breeds having common ancestry and detected strong associations with novel loci on canine chromosomes 10 (P-val = 2.3X10-12) and 31 (P-val = 3.95X10-8). Through whole genome resequencing, we identified primary candidate polymorphisms in conserved regions of PAN2 (encoding p.Arg492Cys) and MAP3K7CL (c.383_392ACTCCACAAA>GACT) on chromosomes 10 and 31, respectively. Analyses of these polymorphisms and the MHC haplotypes revealed that nine of 27 genotypic combinations confer high or moderate probability of disease and explain 93% of cases studied. The pattern of disease risk across PAN2 and MAP3K7CL genotypes provided clear evidence for a significant epistatic foundation for this disease, a risk further impacted by MHC haplotypes. We also observed a genotype-phenotype correlation wherein an earlier age of onset is correlated with an increased number of risk alleles at PAN2 and MAP3K7CL. High frequencies of multiple genetic risk factors are unique to affected breeds and likely arose coincident with artificial selection for desirable phenotypes. Described herein is the first three-locus association with a complex canine disease and two novel loci that provide targets for exploration in JDM and related immunological dysfunction.

  6. Modular organization of the multipartite central pattern generator for turtle rostral scratch: knee-related interneurons during deletions.

    PubMed

    Stein, Paul S G; Daniels-McQueen, Susan; Lai, Jessica; Liu, Z; Corman, Tanya S

    2016-06-01

    Central pattern generators (CPGs) are neuronal networks in the spinal cord that generate rhythmic patterns of motor activity in the absence of movement-related sensory feedback. For many vertebrate rhythmic behaviors, CPGs generate normal patterns of motor neuron activities as well as variations of the normal patterns, termed deletions, in which bursts in one or more motor nerves are absent from one or more cycles of the rhythm. Prior work with hip-extensor deletions during turtle rostral scratch supports hypotheses of hip-extensor interneurons in a hip-extensor module and of hip-flexor interneurons in a hip-flexor module. We present here single-unit interneuronal recording data that support hypotheses of knee-extensor interneurons in a knee-extensor module and of knee-flexor interneurons in a knee-flexor module. Members of knee-related modules are not members of hip-related modules and vice versa. These results in turtle provide experimental support at the single-unit interneuronal level for the organizational concept that the rostral-scratch CPG for the turtle hindlimb is multipartite, that is, composed of more than two modules. This work, when combined with experimental and computational work in other vertebrates, does not support the classical view that the vertebrate limb CPG is bipartite with only two modules, one controlling all the flexors of the limb and the other controlling all the extensors of the limb. Instead, these results support the general principle that spinal CPGs are multipartite.

  7. Effects of ion channel noise on neural circuits: an application to the respiratory pattern generator to investigate breathing variability.

    PubMed

    Yu, Haitao; Dhingra, Rishi R; Dick, Thomas E; Galán, Roberto F

    2017-01-01

    Neural activity generally displays irregular firing patterns even in circuits with apparently regular outputs, such as motor pattern generators, in which the output frequency fluctuates randomly around a mean value. This "circuit noise" is inherited from the random firing of single neurons, which emerges from stochastic ion channel gating (channel noise), spontaneous neurotransmitter release, and its diffusion and binding to synaptic receptors. Here we demonstrate how to expand conductance-based network models that are originally deterministic to include realistic, physiological noise, focusing on stochastic ion channel gating. We illustrate this procedure with a well-established conductance-based model of the respiratory pattern generator, which allows us to investigate how channel noise affects neural dynamics at the circuit level and, in particular, to understand the relationship between the respiratory pattern and its breath-to-breath variability. We show that as the channel number increases, the duration of inspiration and expiration varies, and so does the coefficient of variation of the breath-to-breath interval, which attains a minimum when the mean duration of expiration slightly exceeds that of inspiration. For small channel numbers, the variability of the expiratory phase dominates over that of the inspiratory phase, and vice versa for large channel numbers. Among the four different cell types in the respiratory pattern generator, pacemaker cells exhibit the highest sensitivity to channel noise. The model shows that suppressing input from the pons leads to longer inspiratory phases, a reduction in breathing frequency, and larger breath-to-breath variability, whereas enhanced input from the raphe nucleus increases breathing frequency without changing its pattern.

  8. Traveling-wave pattern generator controls movement and organization of sensory feedback in a spinal cord model.

    PubMed

    Kaske, Alexander; Winberg, Gösta; Cöster, Joakim

    2003-01-01

    A traveling wave in a two-dimensional spinal cord model constitutes a stable pattern generator for quadruped gaits. In the context of the somatotopic organization of the spinal cord, this pattern generator is sufficient to generate stable locomotive limb trajectories. The elastic properties of muscles alone, providing linear negative feedback, are sufficient to stabilize stance and locomotion in the presence of perturbative forces. We further show that such a pattern generator is capable of organizing sensory processing in the spinal cord. A single-layer perceptron was trained to associate the sensory feedback from the limb (coding force, length, and change of length for each muscle) with the two-dimensional activity profile of the traveling wave. This resulted in a well-defined spatial organization of the connections within the spinal network along a rostrocaudal axis. The spinal network driven by peripheral afferents alone supported autonomous locomotion in the positive feedback mode, whereas in the negative feedback mode stance was stabilized in response to perturbations. Systematic variation of a parameter representing the effect of gamma-motor neurons on muscle spindle activity in our model led to a corresponding shift of limb position during stance and locomotion, resulting in a systematic displacement alteration of foot positions.

  9. Control strategies of 3-cell Central Pattern Generator via global stimuli

    PubMed Central

    Lozano, Álvaro; Rodríguez, Marcos; Barrio, Roberto

    2016-01-01

    The study of the synchronization patterns of small neuron networks that control several biological processes has become an interesting growing discipline. Some of these synchronization patterns of individual neurons are related to some undesirable neurological diseases, and they are believed to play a crucial role in the emergence of pathological rhythmic brain activity in different diseases, like Parkinson’s disease. We show how, with a suitable combination of short and weak global inhibitory and excitatory stimuli over the whole network, we can switch between different stable bursting patterns in small neuron networks (in our case a 3-neuron network). We develop a systematic study showing and explaining the effects of applying the pulses at different moments. Moreover, we compare the technique on a completely symmetric network and on a slightly perturbed one (a much more realistic situation). The present approach of using global stimuli may allow to avoid undesirable synchronization patterns with nonaggressive stimuli. PMID:27021970

  10. Control strategies of 3-cell Central Pattern Generator via global stimuli.

    PubMed

    Lozano, Álvaro; Rodríguez, Marcos; Barrio, Roberto

    2016-03-29

    The study of the synchronization patterns of small neuron networks that control several biological processes has become an interesting growing discipline. Some of these synchronization patterns of individual neurons are related to some undesirable neurological diseases, and they are believed to play a crucial role in the emergence of pathological rhythmic brain activity in different diseases, like Parkinson's disease. We show how, with a suitable combination of short and weak global inhibitory and excitatory stimuli over the whole network, we can switch between different stable bursting patterns in small neuron networks (in our case a 3-neuron network). We develop a systematic study showing and explaining the effects of applying the pulses at different moments. Moreover, we compare the technique on a completely symmetric network and on a slightly perturbed one (a much more realistic situation). The present approach of using global stimuli may allow to avoid undesirable synchronization patterns with nonaggressive stimuli.

  11. Control strategies of 3-cell Central Pattern Generator via global stimuli

    NASA Astrophysics Data System (ADS)

    Lozano, Álvaro; Rodríguez, Marcos; Barrio, Roberto

    2016-03-01

    The study of the synchronization patterns of small neuron networks that control several biological processes has become an interesting growing discipline. Some of these synchronization patterns of individual neurons are related to some undesirable neurological diseases, and they are believed to play a crucial role in the emergence of pathological rhythmic brain activity in different diseases, like Parkinson’s disease. We show how, with a suitable combination of short and weak global inhibitory and excitatory stimuli over the whole network, we can switch between different stable bursting patterns in small neuron networks (in our case a 3-neuron network). We develop a systematic study showing and explaining the effects of applying the pulses at different moments. Moreover, we compare the technique on a completely symmetric network and on a slightly perturbed one (a much more realistic situation). The present approach of using global stimuli may allow to avoid undesirable synchronization patterns with nonaggressive stimuli.

  12. Cytotoxicity of citral against melanoma cells: The involvement of oxidative stress generation and cell growth protein reduction.

    PubMed

    Sanches, Larissa Juliani; Marinello, Poliana Camila; Panis, Carolina; Fagundes, Tatiane Renata; Morgado-Díaz, José Andrés; de-Freitas-Junior, Julio Cesar Madureira; Cecchini, Rubens; Cecchini, Alessandra Lourenço; Luiz, Rodrigo Cabral

    2017-03-01

    Citral is a natural compound that has shown cytotoxic and antiproliferative effects on breast and hematopoietic cancer cells; however, there are few studies on melanoma cells. Oxidative stress is known to be involved in all stages of melanoma development and is able to modulate intracellular pathways related to cellular proliferation and death. In this study, we hypothesize that citral exerts its cytotoxic effect on melanoma cells by the modulation of cellular oxidative status and/or intracellular signaling. To test this hypothesis, we investigated the antiproliferative and cytotoxic effects of citral on B16F10 murine melanoma cells evaluating its effects on cellular oxidative stress, DNA damage, cell death, and important signaling pathways, as these pathways, namely, extracellular signal-regulated kinases 1/2 (ERK1/2), AKT, and phosphatidylinositol-3 kinase, are involved in cell proliferation and differentiation. The p53 and nuclear factor kappa B were also investigated due to their ability to respond to intracellular stress. We observed that citral exerted antiproliferative and cytotoxic effects in B16F10; induced oxidative stress, DNA lesions, and p53 nuclear translocation; and reduced nitric oxide levels and nuclear factor kappa B, ERK1/2, and AKT. To investigate citral specificity, we used non-neoplastic human and murine cells, HaCaT (human skin keratinocytes) and NIH-3T3 cells (murine fibroblasts), and observed that although citral effects were not specific for cancer cells, non-neoplastic cells were more resistant to citral than B16F10. These findings highlight the potential clinical utility of citral in melanoma, with a mechanism of action involving the oxidative stress generation, nitric oxide depletion, and interference in signaling pathways related to cell proliferation.

  13. Convective thermal fluxes in unsteady non-homogeneous flows generating complex three dimensional vorticity patterns

    NASA Astrophysics Data System (ADS)

    Tellez Alvarez, Jackson David; Redondo, Jose Manuel; Sanchez, Jesu Mary

    2016-04-01

    The improvements in experimental methods and high resolution image analysis are nowadays able to detect subtle changes in the structure of the turbulence over a wide range of temporal and spatial scales [1], we compare the scaling shown by different mixing fronts driven by buoyancy that form convective driven mixing. We use PIV and density front tracking in several experimental configurations akin to geophysical overturning [2, 3]. We parametrize the role of unstable stratification by means of the Rayleigh and Atwood numbers and compare the scaling and the multifractal structure functions of the different markers used to visualize the non-homogeneous. Both reactive and passive scalar tracers are used to investigate the mixing structure and the intermittency of the flow. Different initial conditions are compared and the mixing efficiency of the overall turbulent process is evaluated [4 - 6]. Diffusion is measured in the transition from a homogeneous linearly stratified fluid to a cellular or layered structure by means of Thermoelectric generated heating and cooling [2, 4]. Patterns arise by setting up a convective flow generated by a buoyant heat flux either in the base or in a side wall of the convective enclosure [1, 6]. The experiments described here investigate high Prandtl number mixing using brine or sugar solutions and fresh water in order to form a density interface and low Prandtl number mixing with only temperature gradients [7]. The set of dimensionless parameters define conditions of numeric and small scale laboratory modeling of environmental flows. Fields of velocity, density and their gradients were computed and visualized [8, 9]. When convective heating and cooling takes place the combination of internal waves and buoyant turbulence is much more complicated if the Rayleigh and Reynolds numbers are high in order to study entrainment and mixing. The experiments described here investigate high Prandtl number mixing using salt or sugar solutions and

  14. Generation of arbitrary lithographic patterns using Bose-Einstein-condensate interferometry

    NASA Astrophysics Data System (ADS)

    Fouda, M. F.; Fang, R.; Ketterson, J. B.; Shahriar, M. S.

    2016-12-01

    We propose an arbitrary pattern lithography process using interference of Bose-Einstein condensates (BECs). A symmetric three-pulse Raman atom interferometer (AI) is used to implement the system. The pattern information, in the form of a phase-only mask, is optically encoded into the BEC order parameter in one of the AI arms. The lithographic pattern is represented by a two-dimensional intensity variation, and is transformed into a two-dimensional phase variation in the BEC order parameter via the use of ac-Stark shift induced by a pulsed laser field. The BEC probability distribution of the interference result at the end of the AI is proportional to the required pattern. In order to produce features smaller than the diffraction limit for the used optical elements, we employ a three-dimensional atomic lens system to scale down the resulting pattern. The operating conditions for this lens structure are investigated in order to identify practical constraints. Simulations of the overall system using the parameters of 87Rb BEC were performed to illustrate its functionality. The proposed process, while perhaps not suitable for general purpose usage, may enable the creation of special purpose patterns on a very small scale, with features as small as a few nanometers.

  15. Exploring a type of central pattern generator based on Hindmarsh-Rose model: from theory to application.

    PubMed

    Zhang, Dingguo; Zhang, Qing; Zhu, Xiangyang

    2015-02-01

    This paper proposes the idea that Hindmarsh-Rose (HR) neuronal model can be used to develop a new type of central pattern generator (CPG). Some key properties of HR model are studied and proved to meet the requirements of CPG. Pros and cons of HR model are provided. A CPG network based on HR model is developed and the related properties are investigated. We explore the bipedal primary gaits generated by the CPG network. The preliminary applications of HR model are tested on humanoid locomotion model and functional electrical stimulation (FES) walking system. The positive results of stimulation and experiment show the feasibility of HR model as a valid CPG.

  16. Mixed Methods Case Study of Generational Patterns in Responses to Shame and Guilt

    ERIC Educational Resources Information Center

    Ng, Tony

    2013-01-01

    Moral socialization and moral learning are antecedents of moral motivation. As many as 4 generations interact in workplace and education settings; hence, a deeper understanding of the moral motivation of members of those generations is needed. The purpose of this convergent mixed methods case study was to understand the moral motivation of 5…

  17. Patterns of Generative Discourse in Online Discussions during the Field Experience

    ERIC Educational Resources Information Center

    Lafferty, Karen Elizabeth; Kopcha, Theodore J.

    2016-01-01

    This study examined how online discussion of the classroom challenges that preservice teachers face during the field experience can lead to problem solving and knowledge generation. Drawing upon Horn and Little's (2010) descriptions of generative discourse, the study examined how a community of preservice teachers, their university supervisors,…

  18. Guiding the self-assembly of a second-generation polyphenylene dendrimer into well-defined patterns.

    PubMed

    Heyen, An J J Ver; Buron, Cédric C; Tianshi, Qin; Bauer, Roland; Jonas, Alain M; Müllen, Klaus; De Schryver, Frans C; De Feyter, Steven

    2008-08-01

    A second-generation polyphenylene dendrimer 1 is shown to self-assemble into nanofibers. To guide the formation of the dendrimer fibers into well-defined patterns, 1H,1H,2H,2H-perfluorodecyltrichlorosilane is grafted in the gas phase onto a silicon substrate. De-wetting of the solution on the nanopatterned surface results in the formation of a nanostructured template, into which fiber growth subsequently occurs under the constraints set by the de-wetted morphology.

  19. Regional hydrocarbon generation, migration, and accumulation pattern of Cretaceous strata, Powder River Basin

    SciTech Connect

    Meissner, F.F.

    1985-05-01

    A cell of abnormally high fluid pressure in the deep part of the Powder River basin is centered in an area where oil-generation-prone source rocks in the Skull Creek (oldest), Mowry, and Niobrara (youngest) formations are presently at their maximum hydrocarbon-volume generation rate. The overpressures are believed to be caused by the high conversion rate of solid kerogen in the source rocks to an increased volume of potentially expellable fluid hydrocarbons. In this area, hydrocarbons appear to be the principal mobile fluid species present in reservoirs within or proximal to the actively generating source rocks. Maximum generation pressures within the source rocks have caused vertical expulsion through a pressure-induced microfracture system and have charged the first available underlying and/or overlying sandstone carrier-reservoir bed. Hydrocarbons generated in the Skull Creek have been expelled downward into the Dakota Sandstone and upward into the Muddy Sandstone. Hydrocarbons generated in the Mowry have been expelled downward into the Muddy or upward into lower Frontier sandstones. Hydrocarbons generated in the Niobrara have been expelled downward into upper Frontier sandstones or upward into the first available overlying sandstone in the Upper Cretaceous. The first chargeable sandstone overlying the Niobrara, in ascending order, may be the (1) Shannon, (2) Sussex, (3) Parkman, (4) Teapot, or (5) Tekla, depending on the east limit of each sandstone with respect to vertical fracture migration through the Cody Shale from the underlying area of mature overpressured Niobrara source rocks.

  20. Design of Spiking Central Pattern Generators for Multiple Locomotion Gaits in Hexapod Robots by Christiansen Grammar Evolution

    PubMed Central

    Espinal, Andres; Rostro-Gonzalez, Horacio; Carpio, Martin; Guerra-Hernandez, Erick I.; Ornelas-Rodriguez, Manuel; Sotelo-Figueroa, Marco

    2016-01-01

    This paper presents a method to design Spiking Central Pattern Generators (SCPGs) to achieve locomotion at different frequencies on legged robots. It is validated through embedding its designs into a Field-Programmable Gate Array (FPGA) and implemented on a real hexapod robot. The SCPGs are automatically designed by means of a Christiansen Grammar Evolution (CGE)-based methodology. The CGE performs a solution for the configuration (synaptic weights and connections) for each neuron in the SCPG. This is carried out through the indirect representation of candidate solutions that evolve to replicate a specific spike train according to a locomotion pattern (gait) by measuring the similarity between the spike trains and the SPIKE distance to lead the search to a correct configuration. By using this evolutionary approach, several SCPG design specifications can be explicitly added into the SPIKE distance-based fitness function, such as looking for Spiking Neural Networks (SNNs) with minimal connectivity or a Central Pattern Generator (CPG) able to generate different locomotion gaits only by changing the initial input stimuli. The SCPG designs have been successfully implemented on a Spartan 6 FPGA board and a real time validation on a 12 Degrees Of Freedom (DOFs) hexapod robot is presented. PMID:27516737

  1. Design of Spiking Central Pattern Generators for Multiple Locomotion Gaits in Hexapod Robots by Christiansen Grammar Evolution.

    PubMed

    Espinal, Andres; Rostro-Gonzalez, Horacio; Carpio, Martin; Guerra-Hernandez, Erick I; Ornelas-Rodriguez, Manuel; Sotelo-Figueroa, Marco

    2016-01-01

    This paper presents a method to design Spiking Central Pattern Generators (SCPGs) to achieve locomotion at different frequencies on legged robots. It is validated through embedding its designs into a Field-Programmable Gate Array (FPGA) and implemented on a real hexapod robot. The SCPGs are automatically designed by means of a Christiansen Grammar Evolution (CGE)-based methodology. The CGE performs a solution for the configuration (synaptic weights and connections) for each neuron in the SCPG. This is carried out through the indirect representation of candidate solutions that evolve to replicate a specific spike train according to a locomotion pattern (gait) by measuring the similarity between the spike trains and the SPIKE distance to lead the search to a correct configuration. By using this evolutionary approach, several SCPG design specifications can be explicitly added into the SPIKE distance-based fitness function, such as looking for Spiking Neural Networks (SNNs) with minimal connectivity or a Central Pattern Generator (CPG) able to generate different locomotion gaits only by changing the initial input stimuli. The SCPG designs have been successfully implemented on a Spartan 6 FPGA board and a real time validation on a 12 Degrees Of Freedom (DOFs) hexapod robot is presented.

  2. Manipulation of micro-particles through optical interference patterns generated by integrated photonic devices.

    PubMed

    Hsu, Li-Chung; Chen, Te-Chang; Yang, Yao-Tsu; Huang, Chieh-Yang; Shen, Da-Wei; Chen, Ya-Tzu; Lee, Ming-Chang M

    2013-03-21

    Micro-particle transport and switch governed by guided-wave optical interference are presented. The optical interference, occurring in a directional coupler and a multi-mode interferometer made by inverted rib waveguides, results in a specific evanescent field dependent on wavelength. Through a detailed theoretical analysis, the field of induced optical force shows a correlative pattern associated with the evanescent field. Experimental results demonstrate that 10 μm polystyrene beads are propelled with a trajectory subject to the interference pattern accordingly. By launching different wavelengths, the polystyrene beads can be delivered to different output waveguide ports. Massive micro-particle manipulation is applicable.

  3. Near-field to far-field characterization of speckle patterns generated by disordered nanomaterials.

    PubMed

    Parigi, Valentina; Perros, Elodie; Binard, Guillaume; Bourdillon, Céline; Maître, Agnès; Carminati, Rémi; Krachmalnicoff, Valentina; De Wilde, Yannick

    2016-04-04

    We study the intensity spatial correlation function of optical speckle patterns above a disordered dielectric medium in the multiple scattering regime. The intensity distributions are recorded by scanning near-field optical microscopy (SNOM) with sub-wavelength spatial resolution at variable distances from the surface in a range which spans continuously from the near-field (distance ≪ λ) to the far-field regime (distance ≫ λ). The non-universal behavior at sub-wavelength distances reveals the connection between the near-field speckle pattern and the internal structure of the medium.

  4. A simple model for polar cap convection patterns and generation of theta auroras

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.

    1985-01-01

    An addition of the uniform interplanetary magnetic field and the earth's dipole magnetic field is used to evaluate electric field convection patterns over the polar caps that result from solar wind flow across open geomagnetic field lines. The model also accounts for field-aligned patterns within, and auroral arcs across, the polar cap. The qualitative predictions derived from the model express the electric field magnitudes, aurora intensity, sunward and antisunward flow, and the dusk-side reversal of the convection field in terms of the x and y components of the interplanetary magnetic field.

  5. NOX4 activity is determined by mRNA levels and reveals a unique pattern of ROS generation

    PubMed Central

    Serrander, Lena; Cartier, Laetitia; Bedard, Karen; Banfi, Botond; Lardy, Bernard; Plastre, Olivier; Sienkiewicz, Andrzej; Fórró, Lászlo; Schlegel, Werner; Krause, Karl-Heinz

    2007-01-01

    NOX4 is an enigmatic member of the NOX (NADPH oxidase) family of ROS (reactive oxygen species)-generating NADPH oxidases. NOX4 has a wide tissue distribution, but the physiological function and activation mechanisms are largely unknown, and its pharmacology is poorly understood. We have generated cell lines expressing NOX4 upon tetracycline induction. Tetracycline induced a rapid increase in NOX4 mRNA (1 h) followed closely (2 h) by a release of ROS. Upon tetracycline withdrawal, NOX4 mRNA levels and ROS release decreased rapidly (<24 h). In membrane preparations, NOX4 activity was selective for NADPH over NADH and did not require the addition of cytosol. The pharmacological profile of NOX4 was distinct from other NOX isoforms: DPI (diphenyleneiodonium chloride) and thioridazine inhibited the enzyme efficiently, whereas apocynin and gliotoxin did not (IC50>100 μM). The pattern of NOX4-dependent ROS generation was unique: (i) ROS release upon NOX4 induction was spontaneous without need for a stimulus, and (ii) the type of ROS released from NOX4-expressing cells was H2O2, whereas superoxide (O2−) was almost undetectable. Probes that allow detection of intracellular O2− generation yielded differential results: DHE (dihydroethidium) fluorescence and ACP (1-acetoxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine) ESR measurements did not detect any NOX4 signal, whereas a robust signal was observed with NBT. Thus NOX4 probably generates O2− within an intracellular compartment that is accessible to NBT (Nitro Blue Tetrazolium), but not to DHE or ACP. In conclusion, NOX4 has a distinct pharmacology and pattern of ROS generation. The close correlation between NOX4 mRNA and ROS generation might hint towards a function as an inducible NOX isoform. PMID:17501721

  6. Novel architecture for high-speed dual-image generation of pattern data for phase-shifting reticle inspection

    NASA Astrophysics Data System (ADS)

    Hosono, Kunihiro; Takeuchi, Susumu; Watakabe, Yaichiro; Wihl, Tim; Brandemuehl, Mark; Joseph, David A.

    1992-06-01

    The pattern data representing ULSI photolithography layers continues to grow exponentially when viewed at the image plane. Data derivation, verification, conversion, and movement have resulted in significant logistical problems and reticle production bottlenecks even with current device densities and reticle manufacturing technologies. With the advent of phase shifting reticle manufacturing and even more dense ULSI devices, database image generation for reticle defect inspection becomes an even more serious issue. Examination of 64 MBit pattern characteristics show that total figure counts per layer approach 1 billion figures per layer. Phase shifting structures increase figure counts per layer to over 1 billion figures. Defect sensitivities of 0.40 micrometers for chrome defects and 0.30 micrometers for phase shift defects are required for 64 MBit reticle inspection. Single die inspection area exceeds 5000 mm2 and die pixel counts are over 1011 pixels. Current reticle inspection database image generation technology requires ten hours per inspection pass. Data load times exceed one hour and data conversion to the inspection format exceeds ten hours. Total reticle inspection time in the manufacturing environment may approach 40 hours. A novel pattern generator architecture allowing 64 MBit reticle inspection in one hour is proposed. The NPG architecture includes a new data format, an integrated data conversion package, and a high resolution, high speed image generator. NPG data conversion performance is analyzed and 782 million figure 64 MBit data conversions are performed in less than one minute. Resulting file sizes are one million bytes. The NPG data format is shown to allow increased edge placement resolution to support increased inspection sensitivity. A method for simultaneously generating chrome and phase shift images is presented.

  7. Stereo transparency in ambiguous stereograms generated by overlapping two identical dot patterns.

    PubMed

    Watanabe, Osamu

    2009-11-30

    In binocular vision, observers can perceive transparent surfaces by fusing a stereogram composed of two overlapping patterns with different disparities. When dot patterns of two surfaces are identical, the stereogram has potential matches leading to both transparency and non-transparency (or unitary surface) perceptions. However, these two matching candidates are exclusive if the uniqueness assumption holds. This stereogram can be regarded as a random-dot version of the double-nail illusion and a stereo version of the locally paired-dot stimulus that was used to investigate the neural mechanism for motion transparency. Which surface is perceived in this ambiguous stereogram would reflect the property of the transparency detection mechanism in human stereopsis. Here we perform a parametric study to examine the perceptual property in this ambiguous stereogram. The result showed that the ability in transparency detection from this stereogram is determined by the contrast reversal ratio between overlapping patterns within small regions the width of which was about 0.4 deg. The width was similar to the receptive field sizes of neurons in striate cortex. The result suggests that the contrast reversal between two identical patterns would modulate activities of binocular neurons, and this modification gives a crucial effect on the neural representation for overlapping disparities.

  8. Pigment Pattern Formation in the Guppy, Poecilia reticulata, Involves the Kita and Csf1ra Receptor Tyrosine Kinases

    PubMed Central

    Kottler, Verena A.; Fadeev, Andrey; Weigel, Detlef; Dreyer, Christine

    2013-01-01

    Males of the guppy (Poecilia reticulata) vary tremendously in their ornamental patterns, which are thought to have evolved in response to a complex interplay between natural and sexual selection. Although the selection pressures acting on the color patterns of the guppy have been extensively studied, little is known about the genes that control their ontogeny. Over 50 years ago, two autosomal color loci, blue and golden, were described, both of which play a decisive role in the formation of the guppy color pattern. Orange pigmentation is absent in the skin of guppies with a lesion in blue, suggesting a defect in xanthophore development. In golden mutants, the development of the melanophore pattern during embryogenesis and after birth is affected. Here, we show that blue and golden correspond to guppy orthologs of colony-stimulating factor 1 receptor a (csf1ra; previously called fms) and kita. Most excitingly, we found that both genes are required for the development of the black ornaments of guppy males, which in the case of csf1ra might be mediated by xanthophore–melanophore interactions. Furthermore, we provide evidence that two temporally and genetically distinct melanophore populations contribute to the adult camouflage pattern expressed in both sexes: one early appearing and kita-dependent and the other late-developing and kita-independent. The identification of csf1ra and kita mutants provides the first molecular insights into pigment pattern formation in this important model species for ecological and evolutionary genetics. PMID:23666934

  9. An Experimental Investigation of the Wave Pattern Generated by a Moving Pressure Source: Solitary Capillary-Gravity Waves

    NASA Astrophysics Data System (ADS)

    Duncan, J. H.; Diorio, J. D.; Lisiewski, A.; Harris, R.

    2009-11-01

    The wave pattern generated by a small pressure source moving across a water surface at speeds less than the minimum phase speed for linear gravity-capillary waves (cmin = 23 cm/s) was investigated experimentally. The resulting wave pattern was measured using cinematic shadowgraph and laser-induced fluorescence (LIF) techniques. The results show the existence of several distinct behavioral states. At low speeds, no wave behavior is observed and the pattern resembles the symmetric stationary condition. However, at a critical speed, but still below cmin, the pattern undergoes a sudden transition to an asymmetric state with a stationary, 2D solitary wave that forms behind the pressure source. This solitary wave is elongated in the cross-stream relative to the stream-wise direction and resembles gravity-capillary ``lumps'' observed in previous numerical calculations. As the translation speed approaches cmin, another time-dependent behavior is observed characterized by periodic ``shedding'' from a V-shaped solitary wave pattern. This work will be discussed in conjunction with the recent numerical calculations of T. Akylas and his research group.

  10. Generation and use of observational data patterns in the evaluation of data quality for AmeriFlux and FLUXNET

    NASA Astrophysics Data System (ADS)

    Pastorello, G.; Agarwal, D.; Poindexter, C.; Papale, D.; Trotta, C.; Ribeca, A.; Canfora, E.; Faybishenko, B.; Gunter, D.; Chu, H.

    2015-12-01

    The fluxes-measuring sites that are part of AmeriFlux are operated and maintained in a fairly independent fashion, both in terms of scientific goals and operational practices. This is also the case for most sites from other networks in FLUXNET. This independence leads to a degree of heterogeneity in the data sets collected at the sites, which is also reflected in data quality levels. The generation of derived data products and data synthesis efforts, two of the main goals of these networks, are directly affected by the heterogeneity in data quality. In a collaborative effort between AmeriFlux and ICOS, a series of quality checks are being conducted for the data sets before any network-level data processing and product generation take place. From these checks, a set of common data issues were identified, and are being cataloged and classified into data quality patterns. These patterns are now being used as a basis for implementing automation for certain data quality checks, speeding up the process of applying the checks and evaluating the data. Currently, most data checks are performed individually in each data set, requiring visual inspection and inputs from a data curator. This manual process makes it difficult to scale the quality checks, creating a bottleneck for the data processing. One goal of the automated checks is to free up time of data curators so they can focus on new or less common issues. As new issues are identified, they can also be cataloged and classified, extending the coverage of existing patterns or potentially generating new patterns, helping both improve existing automated checks and create new ones. This approach is helping make data quality evaluation faster, more systematic, and reproducible. Furthermore, these patterns are also helping with documenting common causes and solutions for data problems. This can help tower teams with diagnosing problems in data collection and processing, and also in correcting historical data sets. In this

  11. 3D Structure Generation, Molecular Dynamics and Docking Studies of IRHOM2 Protein Involved in Cancer & Rheumatoid Arthritis.

    PubMed

    Raj, Utkarsh; Kumar, Himansu; Varadwaj, Pritish Kumar

    2015-01-01

    A short-lived membrane protein IRHOM2 pedals a cascade of events by regulating Epidermal Growth Factor Receptor (EGFR) signalling in parallel with metalloproteases which results their involvement in cancer as well as in rheumatoid arthritis. Therefore, IRHOM2 is a potential therapeutic drug target for these diseases, but its 3D-structure has not been reported yet. In this study, the three-dimensional structure of the IRHOM2 protein was generated using I-TASSER (Iterative Threading Assembly Refinement) server. The modeled structure of IRHOM2 receptor was validated using various Structural Analysis and Verification Server (SAVES) in which 99.7% of amino acid residues are present in the favoured regions of the Ramachandran Plot. Further, the refined modeled structure was subjected to molecular dynamics simulation & docking analysis. Virtual screening studies were carried out using Glide with various selective libraries containing 24552 compounds and the analysis indicated extensive hydrogen bonding network and hydrophobic interactions which play a significant role in its binding. Docking results were analyzed for high ranking compounds using a consensus based docking score to calculate the binding affinity as a measure of protein-ligand interactions. The top ranking molecule against IRHOM2 active site has a glide g-score of -12.565 kcal/mol and glide e-model score of -74.967 with 3 hydrogen bonds and 11 hydrophobic contacts. This compound may act as probable inhibitor against these chronic diseases but further in vitro studies are required.

  12. Fast gamma oscillations are generated intrinsically in CA1 without the involvement of fast-spiking basket cells.

    PubMed

    Craig, Michael T; McBain, Chris J

    2015-02-25

    Information processing in neuronal networks relies on the precise synchronization of ensembles of neurons, coordinated by the diverse family of inhibitory interneurons. Cortical interneurons can be usefully parsed by embryonic origin, with the vast majority arising from either the caudal or medial ganglionic eminences (CGE and MGE). Here, we examine the activity of hippocampal interneurons during gamma oscillations in mouse CA1, using an in vitro model where brief epochs of rhythmic activity were evoked by local application of kainate. We found that this CA1 KA-evoked gamma oscillation was faster than that in CA3 and, crucially, did not appear to require the involvement of fast-spiking basket cells. In contrast to CA3, we also found that optogenetic inhibition of pyramidal cells in CA1 did not significantly affect the power of the oscillation, suggesting that excitation may not be essential for gamma genesis in this region. We found that MGE-derived interneurons were generally more active than CGE interneurons during CA1 gamma, although a group of CGE-derived interneurons, putative trilaminar cells, were strongly phase-locked with gamma oscillations and, together with MGE-derived axo-axonic and bistratified cells, provide attractive candidates for being the driver of this locally generated, predominantly interneuron-driven model of gamma oscillations.

  13. Dopamine receptors set the pattern of activity generated in subthalamic neurons.

    PubMed

    Baufreton, J; Zhu, Z-T; Garret, M; Bioulac, B; Johnson, S W; Taupignon, A I

    2005-11-01

    Information processing in the brain requires adequate background neuronal activity. As Parkinson's disease progresses, patients typically become akinetic; the death of dopaminergic neurons leads to a dopamine-depleted state, which disrupts information processing related to movement in a brain area called the basal ganglia. Using agonists of dopamine receptors in the D1 and D2 families on rat brain slices, we show that dopamine receptors in these two families govern the firing pattern of neurons in the subthalamic nucleus, a crucial part of the basal ganglia. We propose a conceptual frame, based on specific properties of dopamine receptors, to account for the dominance of different background firing patterns in normal and dopamine-depleted states.

  14. Next-generation re-sequencing of genes involved in increased platelet reactivity in diabetic patients on acetylsalicylic acid.

    PubMed

    Postula, Marek; Janicki, Piotr K; Eyileten, Ceren; Rosiak, Marek; Kaplon-Cieslicka, Agnieszka; Sugino, Shigekazu; Wilimski, Radosław; Kosior, Dariusz A; Opolski, Grzegorz; Filipiak, Krzysztof J; Mirowska-Guzel, Dagmara

    2016-06-01

    The objective of this study was to investigate whether rare missense genetic variants in several genes related to platelet functions and acetylsalicylic acid (ASA) response are associated with the platelet reactivity in patients with diabetes type 2 (T2D) on ASA therapy. Fifty eight exons and corresponding introns of eight selected genes, including PTGS1, PTGS2, TXBAS1, PTGIS, ADRA2A, ADRA2B, TXBA2R, and P2RY1 were re-sequenced in 230 DNA samples from T2D patients by using a pooled PCR amplification and next-generation sequencing by Illumina HiSeq2000. The observed non-synonymous variants were confirmed by individual genotyping of 384 DNA samples comprising of the individuals from the original discovery pools and additional verification cohort of 154 ASA-treated T2DM patients. The association between investigated phenotypes (ASA induced changes in platelets reactivity by PFA-100, VerifyNow and serum thromboxane B2 level [sTxB2]), and accumulation of rare missense variants (genetic burden) in investigated genes was tested using statistical collapsing tests. We identified a total of 35 exonic variants, including 3 common missense variants, 15 rare missense variants, and 17 synonymous variants in 8 investigated genes. The rare missense variants exhibited statistically significant difference in the accumulation pattern between a group of patients with increased and normal platelet reactivity based on PFA-100 assay. Our study suggests that genetic burden of the rare functional variants in eight genes may contribute to differences in the platelet reactivity measured with the PFA-100 assay in the T2DM patients treated with ASA.

  15. Parallel streams versus integrated timing in multilimb pattern generation: A test of Korte's Third Law.

    PubMed

    Jagacinski, Richard J; Rizzi, Emanuele; Kim, Tae Hoon; Lavender, Steven A; Speller, Lassiter F; Klapp, Stuart T

    2016-11-01

    Skilled drummers performed a 4:3:2 polyrhythm with 2 hands and 1 foot. For each pair of limbs patterns of temporal covariation were used to infer relatively independent parallel streams versus integrated timing relationships. Parallel timing was more prevalent between hand and foot than between the 2 hands, and parallel timing generally increased with tapping rate. Different combinations of integrated and parallel timing were found among the 3 limbs. A second experiment used a wider range of tapping rates and explored 3:2 tapping with 2 hands, 2 feet, or hand and foot. The latter 2 limb pairs resulted in greater prevalence of parallel timing. These results can be interpreted in terms of a Gestalt principle of grouping known as Korte's Third Law, which can be extended from the perceptual domain to the perceptual-motor domain. This principle indicates that perceived velocity is a key factor in determining whether a sequence of events is represented as a single integrated pattern or as multiple parallel patterns. The present results put disparate previous findings on bimanual polyrhythmic tapping and rhythmic aspects of the golf swing under a common theoretical perspective. (PsycINFO Database Record

  16. The Next Generation of Users: Prevalence and Longitudinal Patterns of Tobacco Use Among US Young Adults

    PubMed Central

    Williams, Valerie; Rath, Jessica; Villanti, Andrea C.; Vallone, Donna

    2014-01-01

    Objectives. We monitored the prevalence and patterns of use of the array of tobacco products available to young adults, who are at risk for initiation and progression to established tobacco use. Methods. We used data from waves 1 to 3 of GfK’s KnowledgePanel (2011–2012), a nationally representative cohort of young adults aged 18 to 34 years (n = 2144). We examined prevalence and patterns of tobacco product use over time, associated demographics, and state-level tobacco policy. We used multivariable logistic regression to determine predictors of initiation of cigarettes as well as noncombustible and other combustible products. Results. The prevalence of ever tobacco use rose from 57.28% at wave 1 to 67.43% at wave 3. Use of multiple products was the most common pattern (66.39% of tobacco users by wave 3). Predictors of initiation differed by product type and included age, race/ethnicity, policy, and use of other tobacco products. Conclusions. Tobacco use is high among young adults and many are using multiple products. Efforts to implement policy and educate young adults about the risks associated with new and emerging products are critical to prevent increased initiation of tobacco use. PMID:24922152

  17. Programming Surface Energy Driven Marangoni Convection in Polymer Thin Films to Generate Topographic Patterns

    NASA Astrophysics Data System (ADS)

    Kim, Chae Bin; Janes, Dustin; Arshad, Talha; Katzenstein, Joshua; Prisco, Nathan; McGuffin, Dana; Bonnecaze, Roger; Ellison, Christopher

    2015-03-01

    The Marangoni effect describes how fluid flows in response to gradients in surface energy. We recently developed a method for photochemically preprograming spatial surface energy patterns in glassy polystyrene (PS) thin films. UV irradiation through a mask selectively dehydrogenates the PS, thus increasing surface energy in the UV exposed regions compared to the unexposed regions. After heating the film to the liquid state, transport of polymer occurs from regions of low surface energy to regions of high surface energy. This method can be harnessed to rapidly manufacture polymer films possessing prescribed three-dimensional topographies reflective of the original light exposure pattern. To quantify and verify this phenomenon, a theoretical model that gives a more thorough understanding of the physics of this process, its limits and ways to apply it efficiently for various target metrics will also be presented along with comparisons between theoretical predictions and experimental observations. Finally, while PS dehydrogenation can be used to produce a variety of topographical patterns, judicious selection of the photosensitizing compounds in an otherwise transparent polymer expands the use of this method to more readily available light sources.

  18. Generating Arbitrary Chemical Patterns for Multi-Point Dosing of Single Cells

    PubMed Central

    Hoppe, Todd J.; Moorjani, Samira G.; Shear, Jason B.

    2013-01-01

    Living cells reside within anisotropic microenvironments that orchestrate a broad range of polarized responses through physical and chemical cues. To unravel how localized chemical signals influence complex behaviors, tools must be developed for establishing patterns of chemical gradients that vary over subcellular dimensions. Here, we present a strategy for addressing this critical need in which an arbitrary number of chemically distinct, subcellular dosing streams are created in real time within a microfluidic environment. In this approach, cells are cultured on a thin polymer membrane that serves as a barrier between the cell-culture environment and a reagent chamber containing multiple reagent species flowing in parallel under low Reynolds number conditions. Focal ablation of the membrane creates pores that allow solution to flow from desired regions within this reagent pattern into the cell-culture chamber, resulting in narrow, chemically distinct dosing streams. Unlike previous dosing strategies, this system provides the capacity to tailor arbitrary patterns of reagents on-the-fly to suit the geometry and orientation of specific cells. PMID:23427919

  19. Optical generation of a circular harmonic filter for rotation and translation invariant optical pattern recognition

    NASA Technical Reports Server (NTRS)

    Cheng, Yeou-Yen

    1987-01-01

    A new method to generate a circular harmonic filter with both rotation and translation invariance is described, which is based on a phase-shifted double-exposure (PSDE) technique. An expression for the peak correlation intensity at the origin for the correlation plane as a function of target orientation for the PSDE filter is derived. Experimental results confirming the theoretical predictions are provided.

  20. Class and University Education: Inter-Generational Patterns in Canada. NALL Working Paper.

    ERIC Educational Resources Information Center

    Livingstone, D. W.; Stowe, Susan

    Young people from lower class origins continue to face major barriers to university education in Canada. This paper documents both substantial inter-generational class mobility and continuing inequalities in formal educational attainments by class origins. While Canada now has the world's higher educational attainments in its youth cohort and has…

  1. Analysis of RNA Interference Lines Identifies New Functions of Maternally-Expressed Genes Involved in Embryonic Patterning in Drosophila melanogaster.

    PubMed

    Liu, Niankun; Lasko, Paul

    2015-03-31

    Embryonic patterning in Drosophila melanogaster is initially established through the activity of a number of maternally expressed genes that are expressed during oogenesis. mRNAs from some of these genes accumulate in the posterior pole plasm of the oocyte and early embryo and localize further into RNA islands, which are transient ring-like structures that form around the nuclei of future primordial germ cells (pole cells) at stage 3 of embryogenesis. As mRNAs from several genes with known functions in anterior-posterior patterning and/or germ cell specification accumulate in RNA islands, we hypothesized that some other mRNAs that localize in this manner might also function in these developmental processes. To test this, we investigated the developmental functions of 51 genes whose mRNAs accumulate in RNA islands by abrogating their activity in the female germline using RNA interference. This analysis revealed requirements for ttk, pbl, Hip14, eIF5, eIF4G, and CG9977 for progression through early oogenesis. We observed dorsal appendage defects in a proportion of eggs produced by females expressing double-stranded RNA targeting Mkrn1 or jvl, implicating these two genes in dorsal-ventral patterning. In addition, posterior patterning defects and a reduction in pole cell number were seen in the progeny of Mkrn1 females. Because the mammalian ortholog of Mkrn1 acts as an E3 ubiquitin ligase, these results suggest an additional link between protein ubiquitination and pole plasm activity.

  2. Revisiting the mechanisms involved in Line Width Roughness smoothing of 193 nm photoresist patterns during HBr plasma treatment

    SciTech Connect

    Brihoum, M.; Ramos, R.; Menguelti, K.; Cunge, G.; Pargon, E.; Joubert, O.

    2013-01-07

    HBr plasma treatments are widely used in nanoscale lithographic technologies to increase the plasma etch resistance of 193 nm photoresist masks as well as to decrease their Line Width Roughness (LWR). VUV irradiation of the photoresist is known to play a major role in this process by inducing polymer chains rearrangement and finally LWR reduction. However, in the plasma environment (i.e., with radical and ion bombardment), the interaction layer formed at the resist surface perturbs this mechanism and a lower LWR reduction is achieved compared to VUV only treatment. So far the nature of the interaction layer, its formation mechanism and its relation with the resist pattern LWR were all unclear. In this paper, we show that a graphite-like layer is formed on the resist patterns by the redeposition of carbon-based species originating from the plasma dissociation of outgassed photo-etched resist moieties. We show that the presence of this layer inhibits the LWR minimization and causes an increase in the LWR when it becomes thick enough (i.e., a few nanometers). We present evidences that the difference in the mechanical properties of the graphite-like top layer which coats the resist patterns and the bulk of the resist patterns is correlated to the LWR after plasma treatment. We can conclude that the optimization of an HBr cure process relies on the minimization of the carbon redeposition while keeping a significant VUV light flux and we show that this can be achieved by using pulsed plasma processes.

  3. First-generation black-hole-forming supernovae and the metal abundance pattern of a very iron-poor star.

    PubMed

    Umeda, Hideyuki; Nomoto, Ken'ichi

    2003-04-24

    It has been proposed theoretically that the first generation of stars in the Universe (population III) would be as massive as 100 solar masses (100 M(O)), because of inefficient cooling of the precursor gas clouds. Recently, the most iron-deficient (but still carbon-rich) low-mass star--HE0107-5240--was discovered. If this is a population III star that gained its metals (elements heavier than helium) after its formation, it would challenge the theoretical picture of the formation of the first stars. Here we report that the patterns of elemental abundance in HE0107-5240 (and other extremely metal-poor stars) are in good accord with the nucleosynthesis that occurs in stars with masses of 20-130 M(O) when they become supernovae if, during the explosions, the ejecta undergo substantial mixing and fallback to form massive black holes. Such supernovae have been observed. The abundance patterns are not, however, consistent with enrichment by supernovae from stars in the range 130-300 M(O). We accordingly infer that the first-generation supernovae came mostly from explosions of approximately 20-130 M(O) stars; some of these produced iron-poor but carbon- and oxygen-rich ejecta. Low-mass second-generation stars, like HE0107-5240, could form because the carbon and oxygen provided pathways for the gas to cool.

  4. Patterns of waste generation: A gradient boosting model for short-term waste prediction in New York City.

    PubMed

    Johnson, Nicholas E; Ianiuk, Olga; Cazap, Daniel; Liu, Linglan; Starobin, Daniel; Dobler, Gregory; Ghandehari, Masoud

    2017-02-15

    Historical municipal solid waste (MSW) collection data supplied by the New York City Department of Sanitation (DSNY) was used in conjunction with other datasets related to New York City to forecast municipal solid waste generation across the city. Spatiotemporal tonnage data from the DSNY was combined with external data sets, including the Longitudinal Employer Household Dynamics data, the American Community Survey, the New York City Department of Finance's Primary Land Use and Tax Lot Output data, and historical weather data to build a Gradient Boosting Regression Model. The model was trained on historical data from 2005 to 2011 and validation was performed both temporally and spatially. With this model, we are able to accurately (R2>0.88) forecast weekly MSW generation tonnages for each of the 232 geographic sections in NYC across three waste streams of refuse, paper and metal/glass/plastic. Importantly, the model identifies regularity of urban waste generation and is also able to capture very short timescale fluctuations associated to holidays, special events, seasonal variations, and weather related events. This research shows New York City's waste generation trends and the importance of comprehensive data collection (especially weather patterns) in order to accurately predict waste generation.

  5. Static envelope patterns in composite resonances generated by level crossing in optical toroidal microcavities.

    PubMed

    Carmon, Tal; Schwefel, Harald G L; Yang, Lan; Oxborrow, Mark; Stone, A Douglas; Vahala, Kerry J

    2008-03-14

    We study level crossing in the optical whispering-gallery (WG) modes by using toroidal microcavities. Experimentally, we image the stationary envelope patterns of the composite optical modes that arise when WG modes of different wavelengths coincide in frequency. Numerically, we calculate crossings of levels that correspond with the observed degenerate modes, where our method takes into account the not perfectly transverse nature of their field polarizations. In addition, we analyze anticrossing with a large avoidance gap between modes of the same azimuthal number.

  6. Generation of Homogeneous and Patterned Electron Beams using a Microlens Array Laser-Shaping Technique

    SciTech Connect

    Halavanau, Aliaksei; Edstrom, Dean; Gai, Wei; Ha, Gwanghui; Piot, Philippe; Power, John; Qiang, Gao; Ruan, Jinhao; Santucci, James; Wisniewski, Eric

    2016-06-01

    In photocathodes the achievable electron-beam parameters are controlled by the laser used to trigger the photoemission process. Non-ideal laser distribution hampers the final beam quality. Laser inhomogeneities, for instance, can be "amplified" by space-charge force and result in fragmented electron beams. To overcome this limitation laser shaping methods are routinely employed. In the present paper we demonstrate the use of simple microlens arrays to dramatically improve the transverse uniformity. We also show that this arrangement can be used to produce transversely-patterned electron beams. Our experiments are carried out at the Argonne Wakefield Accelerator facility.

  7. Diffraction patterns from holographic masks generated using combined axicon and helical phase distributions

    NASA Astrophysics Data System (ADS)

    Mihailescu, M.; Preda, L.; Kusko, C.; Scarlat, E. I.

    2015-02-01

    The diffraction patterns (DPs) from helical phase distributions were intensively studied due to their peculiar capability of carrying orbital angular momentum. In the present study, we investigated the combination between a helical phase distribution and another distribution: axicon in our case. Such phase distributions were digitally embedded into holographic masks (HMs). The reconstruction step is performed by simulating the propagation through these HMs, using scalar diffraction theory, Fraunhofer approximation. The spatial intensity arrangement of the DPs is investigated linked with the radial and azimuthal constructive parameters values of the diffractive phase structures embedded in the HMs and transferred in these DPs. Keywords: helical phase distribution

  8. Evidence of a central pattern generator regulating spermathecal muscle activity in Locusta migratoria and its coordination with oviposition.

    PubMed

    da Silva, Rosa; Lange, Angela B

    2011-03-01

    Electrophysiological recordings were conducted to determine the control of spermathecal contractions during oviposition of interrupted egg-laying locusts, Locusta migratoria. Following transection of the central nervous system below the metathoracic ganglion, rhythmic patterned bursting was detected by extracellular recordings of the nerve N2B2 that innervates the muscles of the spermatheca. Subsequent transections at more posterior regions of the ventral nerve cord revealed more robust rhythmic bursting in N2B2. This rhythmic bursting pattern was found to be coordinated with bursting in the ventral opener nerve (N2B1) that innervates the ventral opener muscle. This muscle controls the ventral ovipositor valves. Electromyographic recordings from the spermathecal muscle and ventral opener muscle confirmed a rhythmic bursting pattern resulting in an increase in muscle activity. Taken together, the results indicate that there is probably a central pattern generator (CPG), which is regulated by descending inhibition, that controls the spermathecal muscle activity. This CPG appears to be located within the VIIth and VIIIth abdominal ganglia, and was found to integrate with the CPG that regulates oviposition digging in locusts. These results provide further insight into the intricate coordination and control of reproductive tissues underlying reproductive behaviours in locusts.

  9. Two-photon polymerization of microstructures by a non-diffraction multifoci pattern generated from a superposed Bessel beam.

    PubMed

    Yang, Liang; Qian, Dongdong; Xin, Chen; Hu, Zhijiang; Ji, Shengyun; Wu, Dong; Hu, Yanlei; Li, Jiawen; Huang, Wenhao; Chu, Jiaru

    2017-02-15

    In this Letter, superposed Bessel beams (SBBs) are realized by alternatively imprinting holograms of opposite-order Bessel beams along the radial direction on a spatial light modulator. The propagation invariance and non-rotation properties of SBBs are theoretically predicted and experimentally demonstrated. The focusing property of SBBs with a high numerical aperture (NA) objective is investigated with the Debye vectorial diffraction theory. Near the focal plane, a circularly distributed multiple foci pattern is achieved. The multiple foci generated from SBBs are adopted in a two-photon fabrication system, and micropattern fabrication by a single exposure is demonstrated. Facile fabrication of three-dimensional microstructures with SBBs is realized by dynamically controlling the number of focal spots, and the diameter and rotation of the focal pattern.

  10. Pattern-dependent Role of NMDA receptors in Action Potential Generation: Consequences on ERK Activation

    PubMed Central

    Zhao, Meilan; Adams, J. Paige

    2005-01-01

    Synaptic long-term potentiation is maintained through gene transcription, but how the nucleus is recruited remains controversial. Activation of extracellular-signal regulated kinases 1 and 2 (ERKs) with synaptic stimulation has been shown to require NMDA receptors (NMDARs), yet stimulation intensities sufficient to recruit action potentials (APs) also appear to be required. This has led us to ask the question whether NMDARs are necessary for AP generation as they relate to ERK activation. To test this, we examined the effects of NMDAR blockade on APs induced with synaptic stimulation using whole-cell current clamp recordings from CA1 pyramidal cells in hippocampal slices. NMDAR antagonists were found to potently inhibit APs generated with 5 and 100 Hz synaptic stimulation. Blockade of APs, and ERK activation, could be overcome with the addition of the GABA-A antagonist bicuculline, indicating that APs are sufficient to activate signals such as ERK in the nucleus and throughout the neuron in the continued presence of NMDAR antagonists. Interestingly, no effects of the NMDAR antagonists were observed when theta-burst stimulation (TBS) was used. This resistance to the antagonists is conferred by temporal summation during the bursts. These results clarify findings from a previous study showing that ERK activation induced with TBS is resistant to APV, in contrast to that induced with 5 Hz or 100 Hz stimulation, which is sensitive. By showing that NMDAR blockade inhibits AP generation, we demonstrate that a major role NMDARs play in cell-wide and nuclear ERK activation is through their contribution to action potential generation. PMID:16049179

  11. Exercise, music, and the brain: is there a central pattern generator?

    PubMed

    Schneider, Stefan; Askew, Christopher D; Abel, Thomas; Strüder, Heiko K

    2010-10-01

    The frequency for movements along the longitudinal axis during running peaks at approximately 3 Hz. Other physiological systems (e.g. heart rate and brain cortical activity) are known to show a dominant frequency of ~3 Hz connected to exercise. As recent studies have proposed a clear correlation between musical tempo, mood, and performance output, we wished to ascertain whether peak locomotion frequency of ~3 Hz during running is synchronized with different intrinsic and extrinsic frequencies. Eighteen healthy regular runners performed three outdoor running sessions at different intensities. Oscillations along the longitudinal axis were recorded using an accelerometer (ActiBelt). Electrocortical activity was recorded using electroencephalography before and after exercise and analysed in the delta frequency range (2-4 Hz). In addition, the frequency spectra of the participants' favourite musical pieces were analysed. Data revealed a peak frequency at around 2.7 to 2.8 Hz for the vertical acceleration during running. Similar oscillation patterns were found for heart rate and musical pieces. Electroencephalographic delta activity increased after running. Results of this study give reason to speculate that a strong relationship exists between intrinsic and extrinsic oscillation patterns during exercise. A frequency of approximately 3 Hz seems to be dominant in different physiological systems and seems to be rated as pleasurable when choosing the appropriate music for exercising. This is in line with previous research showing that an adequate choice of music during exercise enhances performance output and mood.

  12. Synaptic signal streams generated by ex vivo neuronal networks contain non-random, complex patterns.

    PubMed

    Lee, Sangmook; Zemianek, Jill M; Shultz, Abraham; Vo, Anh; Maron, Ben Y; Therrien, Mikaela; Courtright, Christina; Guaraldi, Mary; Yanco, Holly A; Shea, Thomas B

    2014-11-01

    Cultured embryonic neurons develop functional networks that transmit synaptic signals over multiple sequentially connected neurons as revealed by multi-electrode arrays (MEAs) embedded within the culture dish. Signal streams of ex vivo networks contain spikes and bursts of varying amplitude and duration. Despite the random interactions inherent in dissociated cultures, neurons are capable of establishing functional ex vivo networks that transmit signals among synaptically connected neurons, undergo developmental maturation, and respond to exogenous stimulation by alterations in signal patterns. These characteristics indicate that a considerable degree of organization is an inherent property of neurons. We demonstrate herein that (1) certain signal types occur more frequently than others, (2) the predominant signal types change during and following maturation, (3) signal predominance is dependent upon inhibitory activity, and (4) certain signals preferentially follow others in a non-reciprocal manner. These findings indicate that the elaboration of complex signal streams comprised of a non-random distribution of signal patterns is an emergent property of ex vivo neuronal networks.

  13. Intergenerational Relationship Quality, Gender, and Grandparent Involvement

    ERIC Educational Resources Information Center

    Barnett, Melissa A.; Scaramella, Laura V.; Neppl, Tricia K.; Ontai, Lenna; Conger, Rand D.

    2010-01-01

    This prospective, intergenerational study (N = 181) considered how parent (G1, Generation 1) and child (G2, Generation 2) relationship quality during adolescence and adulthood is associated with G1's level of involvement with their 3- to 4-year-old grandchildren (G3, Generation 3). Path model analyses indicated different patterns of results for…

  14. Elucidating the role of topological pattern discovery and support vector machine in generating predictive models for Indian summer monsoon rainfall

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Manojit; Chattopadhyay, Surajit

    2016-10-01

    The present paper reports a study, where growing hierarchical self-organising map (GHSOM) has been applied to achieve a visual cluster analysis to the Indian rainfall dataset consisting of 142 years of Indian rainfall data so that the yearly rainfall can be segregated into small groups to visualise the pattern of clustering behaviour of yearly rainfall due to changes in monthly rainfall for each year. Also, through support vector machine (SVM), it has been observed that generation of clusters impacts positively on the prediction of the Indian summer monsoon rainfall. Results have been presented through statistical and graphical analyses.

  15. Simple Process-Based Simulators for Generating Spatial Patterns of Habitat Loss and Fragmentation: A Review and Introduction to the G-RaFFe Model

    PubMed Central

    Pe'er, Guy; Zurita, Gustavo A.; Schober, Lucia; Bellocq, Maria I.; Strer, Maximilian; Müller, Michael; Pütz, Sandro

    2013-01-01

    Landscape simulators are widely applied in landscape ecology for generating landscape patterns. These models can be divided into two categories: pattern-based models that generate spatial patterns irrespective of the processes that shape them, and process-based models that attempt to generate patterns based on the processes that shape them. The latter often tend toward complexity in an attempt to obtain high predictive precision, but are rarely used for generic or theoretical purposes. Here we show that a simple process-based simulator can generate a variety of spatial patterns including realistic ones, typifying landscapes fragmented by anthropogenic activities. The model “G-RaFFe” generates roads and fields to reproduce the processes in which forests are converted into arable lands. For a selected level of habitat cover, three factors dominate its outcomes: the number of roads (accessibility), maximum field size (accounting for land ownership patterns), and maximum field disconnection (which enables field to be detached from roads). We compared the performance of G-RaFFe to three other models: Simmap (neutral model), Qrule (fractal-based) and Dinamica EGO (with 4 model versions differing in complexity). A PCA-based analysis indicated G-RaFFe and Dinamica version 4 (most complex) to perform best in matching realistic spatial patterns, but an alternative analysis which considers model variability identified G-RaFFe and Qrule as performing best. We also found model performance to be affected by habitat cover and the actual land-uses, the latter reflecting on land ownership patterns. We suggest that simple process-based generators such as G-RaFFe can be used to generate spatial patterns as templates for theoretical analyses, as well as for gaining better understanding of the relation between spatial processes and patterns. We suggest caution in applying neutral or fractal-based approaches, since spatial patterns that typify anthropogenic landscapes are often non

  16. Simple process-based simulators for generating spatial patterns of habitat loss and fragmentation: a review and introduction to the G-RaFFe model.

    PubMed

    Pe'er, Guy; Zurita, Gustavo A; Schober, Lucia; Bellocq, Maria I; Strer, Maximilian; Müller, Michael; Pütz, Sandro

    2013-01-01

    Landscape simulators are widely applied in landscape ecology for generating landscape patterns. These models can be divided into two categories: pattern-based models that generate spatial patterns irrespective of the processes that shape them, and process-based models that attempt to generate patterns based on the processes that shape them. The latter often tend toward complexity in an attempt to obtain high predictive precision, but are rarely used for generic or theoretical purposes. Here we show that a simple process-based simulator can generate a variety of spatial patterns including realistic ones, typifying landscapes fragmented by anthropogenic activities. The model "G-RaFFe" generates roads and fields to reproduce the processes in which forests are converted into arable lands. For a selected level of habitat cover, three factors dominate its outcomes: the number of roads (accessibility), maximum field size (accounting for land ownership patterns), and maximum field disconnection (which enables field to be detached from roads). We compared the performance of G-RaFFe to three other models: Simmap (neutral model), Qrule (fractal-based) and Dinamica EGO (with 4 model versions differing in complexity). A PCA-based analysis indicated G-RaFFe and Dinamica version 4 (most complex) to perform best in matching realistic spatial patterns, but an alternative analysis which considers model variability identified G-RaFFe and Qrule as performing best. We also found model performance to be affected by habitat cover and the actual land-uses, the latter reflecting on land ownership patterns. We suggest that simple process-based generators such as G-RaFFe can be used to generate spatial patterns as templates for theoretical analyses, as well as for gaining better understanding of the relation between spatial processes and patterns. We suggest caution in applying neutral or fractal-based approaches, since spatial patterns that typify anthropogenic landscapes are often non

  17. Calcium-permeable presynaptic kainate receptors involved in excitatory short-term facilitation onto somatostatin interneurons during natural stimulus patterns.

    PubMed

    Sun, H Y; Bartley, A F; Dobrunz, L E

    2009-02-01

    Schaffer collateral synapses in hippocampus show target-cell specific short-term plasticity. Using GFP-expressing Inhibitory Neuron (GIN) transgenic mice that express enhanced green fluorescent protein (EGFP) in a subset of somatostatin-containing interneurons (SOM interneurons), we previously showed that Schaffer collateral synapses onto SOM interneurons in stratum (S.) radiatum have unusually large (up to 6-fold) paired-pulse facilitation. This results from a low initial release probability and the enhancement of facilitation by synaptic activation of presynaptic kainate receptors. Here we further investigate the properties of these kainate receptors and examine their effects on short-term facilitation during physiologically derived stimulation patterns, using excitatory postsynaptic currents recorded in S. radiatum interneurons during Schaffer collateral stimulation in acute slices from juvenile GIN mice. We find that GluR5 and GluR6 antagonists decrease short-term facilitation at Schaffer collateral synapses onto SOM interneurons with no additive effects, suggesting that the presynaptic kainate receptors are heteromers containing both GluR5 and GluR6 subunits. The calcium-permeable receptor antagonist 1-napthyl acetyl spermine (NASPM) both mimics and occludes the effect of the kainate receptor antagonists, indicating that the presynaptic kainate receptors are calcium permeable. Furthermore, Schaffer collateral synapses onto SOM interneurons show up to 11-fold short-term facilitation during physiologically derived stimulus patterns, in contrast to other interneurons that have less than 1.5-fold facilitation. Blocking the kainate receptors reduces facilitation in SOM interneurons by approximately 50% during the physiologically derived patterns and reduces the dynamic range. Activation of calcium-permeable kainate receptors containing GluR5/GluR6 causes a dramatic increase in short-term facilitation during physiologically derived stimulus patterns, a mechanism

  18. Time-resolved measurements with streaked diffraction patterns from electrons generated in laser plasma wakefield

    NASA Astrophysics Data System (ADS)

    He, Zhaohan; Nees, John; Hou, Bixue; Krushelnick, Karl; Thomas, Alec; Beaurepaire, Benoît; Malka, Victor; Faure, Jérôme

    2013-10-01

    Femtosecond bunches of electrons with relativistic to ultra-relativistic energies can be robustly produced in laser plasma wakefield accelerators (LWFA). Scaling the electron energy down to sub-relativistic and MeV level using a millijoule laser system will make such electron source a promising candidate for ultrafast electron diffraction (UED) applications due to the intrinsic short bunch duration and perfect synchronization with the optical pump. Recent results of electron diffraction from a single crystal gold foil, using LWFA electrons driven by 8-mJ, 35-fs laser pulses at 500 Hz, will be presented. The accelerated electrons were collimated with a solenoid magnetic lens. By applying a small-angle tilt to the magnetic lens, the diffraction pattern can be streaked such that the temporal evolution is separated spatially on the detector screen after propagation. The observable time window and achievable temporal resolution are studied in pump-probe measurements of photo-induced heating on the gold foil.

  19. The generation of pharyngeal phase of swallow and its coordination with breathing: interaction between the swallow and respiratory central pattern generators.

    PubMed

    Bautista, Tara G; Sun, Qi-Jian; Pilowsky, Paul M

    2014-01-01

    Swallowing and breathing utilize common muscles and an anatomical passage: the pharynx. The risk of aspiration of ingested material is minimized not only by the laryngeal adduction of the vocal folds and laryngeal elevation but also by the precise coordination of swallows with breathing. Namely, swallows: (1) are preferentially initiated in the postinspiratory/expiratory phase, (2) are accompanied by a brief apnea, and (3) are often followed by an expiration and delay of the next breath. This review summarizes the expiratory evidence on the brainstem regions comprising the central pattern generator (CPG) that produces the pharyngeal stage of swallow, how the motor acts of swallowing and breathing are coordinated, and lastly, brainstem regions where the swallowing and respiratory CPGs may interact in order to ensure "safe" swallows.

  20. K-Medoids-Based Random Biometric Pattern for Cryptographic Key Generation

    NASA Astrophysics Data System (ADS)

    Garcia-Baleon, H. A.; Alarcon-Aquino, V.; Starostenko, O.

    In this paper we report an approach for cryptographic key generation based on keystroke dynamics and the k-medoids algorithm. The stages that comprise the approach are training-enrollment and user verification. The proposed approach is able to verify the identity of individuals off-line avoiding the use of a centralized database. The performance of the proposed approach is assessed using 20 samples of keystroke dynamics from 20 different users. Simulation results show a false acceptance rate (FAR) of 5.26% and a false rejection rate (FRR) of 10%. The cryptographic key released by the proposed approach may be used in several encryption algorithms.

  1. Generating precise mechanical stimuli and recording chordotonal organ discharge patterns using a microcomputer.

    PubMed

    Stephen, R O; Shelton, P M; Bradshaw, M S

    1990-07-01

    A computer-controlled system for the investigation of the response properties of the tibio-femoral chordotonal organ in the locust is described. The computer is used to generate small amplitude sinusoidal movements of the tibia via a small servo-controlled motor. The resulting response recorded via a suction electrode is simultaneously detected, processed and stored on disk. Full constructional details for all hardware required are given. The software, developed for a BBC microcomputer, in addition to controlling all the hardware, has graphics and analysis routines enabling the operator to display and manipulate the stored data.

  2. Direct patterning of vortex generators on a fiber tip using a focused ion beam.

    PubMed

    Vayalamkuzhi, Pramitha; Bhattacharya, Shanti; Eigenthaler, Ulrike; Keskinbora, Kahraman; Samlan, C T; Hirscher, Michael; Spatz, Joachim P; Viswanathan, Nirmal K

    2016-05-15

    The realization of spiral phase optical elements on the cleaved end of an optical fiber by focused ion beam milling is presented. A focused Ga+ ion beam with an acceleration voltage of 30 keV is used to etch continuous spiral phase plates and fork gratings directly on the tip of the fiber. The phase characteristics of the output beam generated by the fabricated structures measured via an interference experiment confirmed the presence of phase singularity in the output beam. The devices are expected to be promising candidates for all-fiber beam shaping and optical trapping applications.

  3. Observing and predicting the spatial-temporal pattern of runoff generation processes from the watershed to the regional scale

    NASA Astrophysics Data System (ADS)

    Weiler, M.

    2012-12-01

    Runoff generation processes are the key to understand and predict watershed dynamics and behaviour under current as well as under changing conditions. A variety of approaches have been developed to observe these processes at the plot scale (e.g. infiltration and sprinkling experiments), the hillslope scale (soil moisture and piezometer networks and trenching) and the watershed scale (hydrograph separation with stable isotopes and natural tracers). However, predicting the four major runoff generation mechanisms (infiltration excess, saturation excess, subsurface flow and deep percolation) without detailed observation in ungauged watershed is still a challenge, but a prerequisite to track water flow pathways and to make adequate prediction for hydrological extremes. Methods have been developed to map dominant runoff generation processes in the field and with digital maps, however, these methods are often static and do not consider the temporal dynamics of runoff generation processes frequently observed with the various experimental approaches. The recently developed parsimonious rainfall-runoff model DROGen can bridge the gap between across spatial scales in ungauged watersheds since parameters are not calibrated. The model incorporates high-resolution GIS data (1m resolution DEM, land-use, impervious surfaces), hydro-geological and pedological data as well as information about the effect of macropores and preferential flow pathways on runoff generation processes with a comprehensive knowledge base from various field observations and experiments. The model was applied to over 6500 meso-scale watershed in the State of Baden-Württemberg in Germany and 15 gauged watersheds were selected for detailed model evaluation. The evaluation was done with field-mapping of runoff generation processes for direct comparison with the simulated pattern of runoff processes for different types of precipitation (high intensity and short duration / low intensity and long duration) and

  4. Factors involved in the distribution pattern of ciliates in the water column of a transparent alpine lake

    PubMed Central

    SONNTAG, BETTINA; SUMMERER, MONIKA; SOMMARUGA, RUBEN

    2011-01-01

    The recurrent depth preference of three ciliate species (two prostomatids and one haptorid) in a transparent alpine lake indicates the existence of niche partitioning among them involving potential factors such as avoidance of high ultraviolet radiation levels and zooplankton predation, as well as competition for food resources. PMID:21984852

  5. Patterns of death in the first and second generation immigrants from selected Middle Eastern countries in California.

    PubMed

    Nasseri, Kiumarss; Moulton, Lawrence H

    2011-04-01

    Migrant studies in the United States (US) have rarely covered the Middle Eastern population (ME), and have never distinguished the first and second generations born in the US. This study aims to describe the mortality patterns of ME immigrants by origin, acculturation, and generation. Death certificates issued from 1997 through 2004 were used to calculate, for Middle Eastern immigrants, the proportional odds ratios (POR) for major causes of death, with comparison to non-Hispanic Whites born in the US to US-born parents. First generation immigrants had higher odds for colorectal cancers, diabetes, and diseases of the heart, while their odds for chronic obstructive pulmonary disease (COPD) and suicide were lower. Men had higher odds for all cancers combined, cancers of the lymphatics, and pancreas. Women had lower odds for lung cancer, and dementia, and higher odds for breast cancer. The second generation men had higher odds for all cancers combined, and diseases of the heart, whereas women had lower odds for lung cancer and cerebrovascular accidents. Higher odds for colorectal cancers and lower odds for COPD were noted in both sexes. Some of the observed differences may be based on ethnic characteristics, including genetic makeup, early exposures, and culturally determined values. Time since immigration is associated with convergence of most odds to that of the native population.

  6. Experiments evaluating subsidence generated within a subaqueous deformable substrate due to varying differential sediment loading patterns

    NASA Astrophysics Data System (ADS)

    Foreman, B.; Chatmas, E. S.; Abeyta, A.; Paola, C.

    2013-12-01

    The intraslope areas of many passive margins display a complex bathymetry of topographic depressions and crests that form series of minibasins. These minibasins are linked to the deformation of subsurface salt layers and act as localized sediment traps. Many mechanisms have been proposed for the initiation of minibasins, including tectonic forces (both extensional and contractional), regional gravitational sliding, density inversion between salt layers and overburden, and differential sediment loading. Regardless of initiation mechanism, it is widely recognized that synkinematic deposition plays a active role in determining subsidence patterns and sediment routing within and among the minibasins. We undertook a series of simplified 1-D and 2-D experiments 1) to evaluate the feasibility of developing a series of well-defined minibasins created exclusively by differential sediment loading and 2) to quantitatively determine the effects of substrate thickness, density contrast, and sedimentation rate on the resultant subsidence pattern. We also present an initial non-dimensionalized formulation of the problem that relates density contrasts, clinoform thickness, substrate thickness, progradation rate, and viscosity of the deformable substrate. Two sets of experiments were performed. The first set (1-D) vertically loaded a subaqueous corn syrup substrate (capturing the rheology of subsurface salt as a Newtonian fluid) with walnut sand. The second set (2-D) of experiments prograded a walnut sediment clinoform across a corn syrup substrate. We systematically varied sedimentation rate, substrate thickness, and, in the case of the prograding clinoform, base level. In no cases did we successfully reproduce a series of minibasins similar to those observed in natural settings. Instead the substrate was simply displaced laterally as sediment was deposited, forming a single depression. High sedimentation rates tended to produce wider zones of subsidence, however, if given

  7. Practical performance and enabling technologies in immersion scanners for the double patterning generation

    NASA Astrophysics Data System (ADS)

    Ishikawa, Jun; Kohno, Hirotaka; Sato, Shinji; Kosugi, Junichi; Shibazaki, Yuichi

    2011-04-01

    At SPIE2010, excellent performance of the cutting edge immersion lithography scanner, the NSR-S620D, which is based on the new "Streamlign" platform was demonstrated. Last year's work focused mainly on machine evaluation data[1]. Now, many S620Ds are employed at customers' sites and being used in device manufacturing. In this paper, the authors will introduce the latest factory data, as well as various techniques that enable superior yield and enhance productivity in IC manufacturing. It is well understood, that in order to achieve further device shrinks without using traditional techniques such as NA expansion or wavelength reduction, several practical issues must be overcome. Extremely tight overlay performance will be required for pitch splitting double patterning, for example. In addition, it is also necessary to control the image plane and the aberration of the optics much more carefully. Of course these improvements must also be achieved with sufficient productivity (throughput). In order to satisfy all of the requirements for mass production at customer factories, many variable factors must be dealt with. One of these variable factors is the characteristics of the processed wafers that include on-flatness, grid distortion, steep topology around the edge, or topography of the previous layers' patterns. These factors typically impact overlay and/or auto focus accuracy. Another variable is the difference in exposure conditions between layers, which include illumination conditions, dose, reticle transmittance, and the alignment marks. Exposure induced heating in particular is the key issue for today's enhanced throughput capabilities, with regards to achieving both optimal accuracy and productivity. In some IC production facilities, and often foundries, many different kinds of products are manufactured in parallel. However, in order to enhance performance and accuracy, it is sometimes necessary to optimize machine parameters for each product. Cleary this

  8. Microstructural Evolution and Creep-Rupture Behavior of Fusion Welds Involving Alloys for Advanced Ultrasupercritical Power Generation

    NASA Astrophysics Data System (ADS)

    Bechetti, Daniel H., Jr.

    Projections for large increases in the global demand for electric power produced by the burning of fossil fuels, in combination with growing environmental concerns surrounding these fuel sources, have sparked initiatives in the United States, Europe, and Asia aimed at developing a new generation of coal fired power plant, termed Advanced Ultrasupercritical (A-USC). These plants are slated to operate at higher steam temperatures and pressures than current generation plants, and in so doing will offer increased process cycle efficiency and reduced greenhouse gas emissions. Several gamma' precipitation strengthened Ni-based superalloys have been identified as candidates for the hottest sections of these plants, but the microstructural instability and poor creep behavior (compared to wrought products) of fusion welds involving these alloys present significant hurdles to their implementation and a gap in knowledge that must be addressed. In this work, creep testing and in-depth microstructural characterization have been used to provide insight into the long-term performance of these alloys. First, an investigation of the weld metal microstructural evolution as it relates to creep strength reductions in A-USC alloys INCONELRTM 740, NIMONICRTM 263 (INCONEL and NIMONIC are registered trademarks of Special Metals Corporation), and HaynesRTM 282RTM (Haynes and 282 are registered trademarks of Haynes International) was performed. gamma'-precipitate free zones were identified in two of these three alloys, and their development was linked to the evolution of phases that precipitate at the expense of gamma'. Alloy 282 was shown to avoid precipitate free zone formation because the precipitates that form during long term aging in this alloy are poor in the gamma'-forming elements. Next, the microstructural evolution of INCONELRTM 740H (a compositional variant of alloy 740) during creep was investigated. Gleeble-based interrupted creep and creep-rupture testing was used to

  9. The ERESE Project: Involving Teachers in the Online Generation and QA/QC of Enduring Teaching Resources

    NASA Astrophysics Data System (ADS)

    Koppers, A. A.; Staudigel, H.; Keller, M.; Russell, J.; Helly, J.; Helly, M.; Miller, S.; Massell Symons, C.

    2005-12-01

    The ERESE project has as its main goal to create, archive and make available "Enduring Resources in Earth Science Education" through a collaboration between teachers, scientists, librarians and information technology (IT) professionals. Over the last two years of this National Science Digital Library (NSDL) project, we have developed such ERESE resources for middle and high school teachers for use in lesson plans with "plate tectonics" and "magnetics" as their main theme. An IT environment has been developed under http://earthref.org/ERESE where researchers, teachers and students can search for and download these resources from the EarthRef.org Digital Archive (ERDA) that now contains more than 600 objects. They do this by searching for researchable questions or by browsing a "Resource Matrix" where the objects (i.e. data files) are displayed based on content (image, data or text) and expert level (1 to 9). Good examples out of the 52 predefined resource matrices are the ones on "Seafloor Spreading", "The Earth's Magnetic Field" and "Hotspots and Absolute Plate Motion". Researchers, teachers and students are encouraged to upload their own contributions in the ERDA online archive, allowing them to share research and teaching materials with their peers and beyond. These uploads can be linked with one or more resource matrices and assigned an expert level. To streamline this uploading process, we have formed a core group of resource developers (students and teachers) that generate new ERESE objects which are subject to an extensive QA/QC (Quality Assessment and Quality Control) protocol by their peers (students and teachers) and by a team of researchers. The peer-to-peer reviews ensure equality and quality amongst the various ERESE resources, whereas the science reviews screen for content correctness and scientific scholarship. The overall goal of this protocol is to ensure digital longevity and scientific validity, while the involvement of teachers and students is

  10. Evolution of Courtship Songs in Xenopus : Vocal Pattern Generation and Sound Production.

    PubMed

    Leininger, Elizabeth C; Kelley, Darcy B

    2015-01-01

    The extant species of African clawed frogs (Xenopus and Silurana) provide an opportunity to link the evolution of vocal characters to changes in the responsible cellular and molecular mechanisms. In this review, we integrate several robust lines of research: evolutionary trajectories of Xenopus vocalizations, cellular and circuit-level mechanisms of vocalization in selected Xenopus model species, and Xenopus evolutionary history and speciation mechanisms. Integrating recent findings allows us to generate and test specific hypotheses about the evolution of Xenopus vocal circuits. We propose that reduced vocal sex differences in some Xenopus species result from species-specific losses of sexually differentiated neural and neuromuscular features. Modification of sex-hormone-regulated developmental mechanisms is a strong candidate mechanism for reduced vocal sex differences.

  11. DOE manufacture with the DUV SLM-based Sigma7300 laser pattern generator

    NASA Astrophysics Data System (ADS)

    Bj÷rn„ngen, Peter; Ekberg, Mats; Ùstr÷m, Thomas; Fosshaug, Hans A.; Karlsson, Johan; Bj÷rnberg, Charles; Nikolajeff, Fredrik K.; Karlsson, Mikael

    2004-05-01

    This paper treats a for the semiconductor industry somewhat different application: The first-ever manufacture of Diffractive Optical Elements (DOE"s) as directly written multilevel diffractive micro-reliefs using the DUV SLM-based Sigma7300 Mask. The reliefs were manufactured in the DUV Chemically Amplified Resist (CAR) FEP-171. This particular application is of direct interest since DOE"s are already incorporated in the Sigma7300 system. The design and manufacture are demonstrated with (1.) A Fan-out element and (2.) A logotype generator. The first attempts, reported here, resulted in a Fan-out element with diffraction efficiency of 64% compared to the theoretical design of 88%.

  12. An in silico central pattern generator: silicon oscillator, coupling, entrainment, and physical computation.

    PubMed

    Lewis, M Anthony; Etienne-Cummings, Ralph; Hartmann, Mitra J; Xu, Zi Rong; Cohen, Avis H

    2003-02-01

    In biological systems, the task of computing a gait trajectory is shared between the biomechanical and nervous systems. We take the perspective that both of these seemingly different computations are examples of physical computation. Here we describe the progress that has been made toward building a minimal biped system that illustrates this idea. We embed a significant portion of the computation in physical devices, such as capacitors and transistors, to underline the potential power of emphasizing the understanding of physical computation. We describe results in the exploitation of physical computation by (1) using a passive knee to assist in dynamics computation, (2) using an oscillator to drive a monoped mechanism based on the passive knee, (3) using sensory entrainment to coordinate the mechanics with the neural oscillator, (4) coupling two such systems together mechanically at the hip and computationally via the resulting two oscillators to create a biped mechanism, and (5) demonstrating the resulting gait generation in the biped mechanism.

  13. Large-scale Generation of Patterned Bubble Arrays on Printed Bi-functional Boiling Surfaces

    PubMed Central

    Choi, Chang-Ho; David, Michele; Gao, Zhongwei; Chang, Alvin; Allen, Marshall; Wang, Hailei; Chang, Chih-hung

    2016-01-01

    Bubble nucleation control, growth and departure dynamics is important in understanding boiling phenomena and enhancing nucleate boiling heat transfer performance. We report a novel bi-functional heterogeneous surface structure that is capable of tuning bubble nucleation, growth and departure dynamics. For the fabrication of the surface, hydrophobic polymer dot arrays are first printed on a substrate, followed by hydrophilic ZnO nanostructure deposition via microreactor-assisted nanomaterial deposition (MAND) processing. Wettability contrast between the hydrophobic polymer dot arrays and aqueous ZnO solution allows for the fabrication of heterogeneous surfaces with distinct wettability regions. Heterogeneous surfaces with various configurations were fabricated and their bubble dynamics were examined at elevated heat flux, revealing various nucleate boiling phenomena. In particular, aligned and patterned bubbles with a tunable departure frequency and diameter were demonstrated in a boiling experiment for the first time. Taking advantage of our fabrication method, a 6 inch wafer size heterogeneous surface was prepared. Pool boiling experiments were also performed to demonstrate a heat flux enhancement up to 3X at the same surface superheat using bi-functional surfaces, compared to a bare stainless steel surface. PMID:27034255

  14. Model of the songbird nucleus HVC as a network of central pattern generators.

    PubMed

    Armstrong, Eve; Abarbanel, Henry D I

    2016-11-01

    We propose a functional architecture of the adult songbird nucleus HVC in which the core element is a "functional syllable unit" (FSU). In this model, HVC is organized into FSUs, each of which provides the basis for the production of one syllable in vocalization. Within each FSU, the inhibitory neuron population takes one of two operational states: 1) simultaneous firing wherein all inhibitory neurons fire simultaneously, and 2) competitive firing of the inhibitory neurons. Switching between these basic modes of activity is accomplished via changes in the synaptic strengths among the inhibitory neurons. The inhibitory neurons connect to excitatory projection neurons such that during state 1 the activity of projection neurons is suppressed, while during state 2 patterns of sequential firing of projection neurons can occur. The latter state is stabilized by feedback from the projection to the inhibitory neurons. Song composition for specific species is distinguished by the manner in which different FSUs are functionally connected to each other. Ours is a computational model built with biophysically based neurons. We illustrate that many observations of HVC activity are explained by the dynamics of the proposed population of FSUs, and we identify aspects of the model that are currently testable experimentally. In addition, and standing apart from the core features of an FSU, we propose that the transition between modes may be governed by the biophysical mechanism of neuromodulation.

  15. Large-scale Generation of Patterned Bubble Arrays on Printed Bi-functional Boiling Surfaces.

    PubMed

    Choi, Chang-Ho; David, Michele; Gao, Zhongwei; Chang, Alvin; Allen, Marshall; Wang, Hailei; Chang, Chih-hung

    2016-04-01

    Bubble nucleation control, growth and departure dynamics is important in understanding boiling phenomena and enhancing nucleate boiling heat transfer performance. We report a novel bi-functional heterogeneous surface structure that is capable of tuning bubble nucleation, growth and departure dynamics. For the fabrication of the surface, hydrophobic polymer dot arrays are first printed on a substrate, followed by hydrophilic ZnO nanostructure deposition via microreactor-assisted nanomaterial deposition (MAND) processing. Wettability contrast between the hydrophobic polymer dot arrays and aqueous ZnO solution allows for the fabrication of heterogeneous surfaces with distinct wettability regions. Heterogeneous surfaces with various configurations were fabricated and their bubble dynamics were examined at elevated heat flux, revealing various nucleate boiling phenomena. In particular, aligned and patterned bubbles with a tunable departure frequency and diameter were demonstrated in a boiling experiment for the first time. Taking advantage of our fabrication method, a 6 inch wafer size heterogeneous surface was prepared. Pool boiling experiments were also performed to demonstrate a heat flux enhancement up to 3X at the same surface superheat using bi-functional surfaces, compared to a bare stainless steel surface.

  16. The influence of aspect ratio and stroke pattern on force generation of a bat-inspired membrane wing.

    PubMed

    Schunk, Cosima; Swartz, Sharon M; Breuer, Kenneth S

    2017-02-06

    Aspect ratio (AR) is one parameter used to predict the flight performance of a bat species based on wing shape. Bats with high AR wings are thought to have superior lift-to-drag ratios and are therefore predicted to be able to fly faster or to sustain longer flights. By contrast, bats with lower AR wings are usually thought to exhibit higher manoeuvrability. However, the half-span ARs of most bat wings fall into a narrow range of about 2.5-4.5. Furthermore, these predictions do not take into account the wide variation in flapping motion observed in bats. To examine the influence of different stroke patterns, we measured lift and drag of highly compliant membrane wings with different bat-relevant ARs. A two degrees of freedom shoulder joint allowed for independent control of flapping amplitude and wing sweep. We tested five models with the same variations of stroke patterns, flapping frequencies and wind speed velocities. Our results suggest that within the relatively small AR range of bat wings, AR has no clear effect on force generation. Instead, the generation of lift by our simple model mostly depends on wingbeat frequency, flapping amplitude and freestream velocity; drag is mostly affected by the flapping amplitude.

  17. Separation of spatial-temporal patterns ('climatic modes') by combined analysis of really measured and generated numerically vector time series

    NASA Astrophysics Data System (ADS)

    Feigin, A. M.; Mukhin, D.; Volodin, E. M.; Gavrilov, A.; Loskutov, E. M.

    2013-12-01

    The new method of decomposition of the Earth's climate system into well separated spatial-temporal patterns ('climatic modes') is discussed. The method is based on: (i) generalization of the MSSA (Multichannel Singular Spectral Analysis) [1] for expanding vector (space-distributed) time series in basis of spatial-temporal empirical orthogonal functions (STEOF), which makes allowance delayed correlations of the processes recorded in spatially separated points; (ii) expanding both real SST data, and longer by several times SST data generated numerically, in STEOF basis; (iii) use of the numerically produced STEOF basis for exclusion of 'too slow' (and thus not represented correctly) processes from real data. The application of the method allows by means of vector time series generated numerically by the INM RAS Coupled Climate Model [2] to separate from real SST anomalies data [3] two climatic modes possessing by noticeably different time scales: 3-5 and 9-11 years. Relations of separated modes to ENSO and PDO are investigated. Possible applications of spatial-temporal climatic patterns concept to prognosis of climate system evolution is discussed. 1. Ghil, M., R. M. Allen, M. D. Dettinger, K. Ide, D. Kondrashov, et al. (2002) "Advanced spectral methods for climatic time series", Rev. Geophys. 40(1), 3.1-3.41. 2. http://83.149.207.89/GCM_DATA_PLOTTING/GCM_INM_DATA_XY_en.htm 3. http://iridl.ldeo.columbia.edu/SOURCES/.KAPLAN/.EXTENDED/.v2/.ssta/

  18. Interference patterns in the Spacelab 2 plasma wave data - oblique electrostatic waves generated by the electron beam

    SciTech Connect

    Feng, Wei; Gurnett, D.A.; Cairns, I.H. )

    1992-11-01

    During the Spacelab 2 mission the University of Iowa's Plasma Diagnostics Package (PDP) explored the plasma environment around the shuttle. Wideband spectrograms of plasma waves were obtained from the PDP at frequencies of 0-30 kHz and at distances up to 400 m from the shuttle. Strong low-frequency (below 10 kHz) electric field noise was observed in the wideband data during two periods in which an electron beam was ejected from the shuttle. This noise shows clear evidence of interference patterns caused by the finite (3.89 m) antenna length. The low-frequency noise was the most dominant type of noise produced by the ejected electron beam. Analysis of antenna interference patterns generated by these waves permits a determination of the wavelength, the direction of propagation, and the location of the source region. The observed waves have a linear dispersion relation very similar to that of ion acoustic waves. The waves are believed to be oblique ion acoustic or high-order ion cyclotron waves generated by a current of ambient electrons returning to the shuttle in response to the ejected electron beam. 31 refs.

  19. A Rich Morphological Diversity of Biosaline Drying Patterns Is Generated by Different Bacterial Species, Different Salts and Concentrations: Astrobiological Implications

    NASA Astrophysics Data System (ADS)

    Gómez Gómez, José María; Medina, Jesús; Rull, Fernando

    2016-07-01

    Biosaline formations (BSFs) are complex self-organized biomineral patterns formed by "hibernating" bacteria as the biofilm that contains them dries out. They were initially described in drying biofilms of Escherichia coli cells + NaCl. Due to their intricate 3-D morphology and anhydrobiosis, these biomineralogical structures are of great interest in astrobiology. Here we report experimental data obtained with various alkali halide salts (NaF, NaCl, NaBr, LiCl, KCl, CsCl) on BSF formation with E. coli and Bacillus subtilis bacteria at two saline concentrations: 9 and 18 mg/mL. Our results indicate that, except for LiCl, which is inactive, all the salts assayed are active during BSF formation and capable of promoting the generation of distinctive drying patterns at each salt concentration. Remarkably, the BSFs produced by these two bacterial species produce characteristic architectural hallmarks as the BSF dries. The potential biogenicity of these biosaline drying patterns is studied, and the astrobiological implications of these findings are discussed.

  20. Resolution Improvement and Pattern Generator Development for theMaskless Micro-Ion-Beam Reduction Lithography System

    SciTech Connect

    Jiang, Ximan

    2006-05-18

    have been studied. The dependence of the throughput with the exposure field size and the speed of the mechanical stage has been investigated. In order to perform maskless lithography, different micro-fabricated pattern generators have been developed for the MMRL system. Ion beamlet switching has been successfully demonstrated on the MMRL system. A positive bias voltage around 10 volts is sufficient to switch off the ion current on the micro-fabricated pattern generators. Some unexpected problems, such as the high-energy secondary electron radiations, have been discovered during the experimental investigation. Thermal and structural analysis indicates that the aperture displacement error induced by thermal expansion can satisfy the 3δ CD requirement for lithography nodes down to 25 nm. The cross-talking effect near the surface and inside the apertures of the pattern generator has been simulated in a 3-D ray-tracing code. New pattern generator design has been proposed to reduce the cross-talking effect. In order to eliminate the surface charging effect caused by the secondary electrons, a new beam-switching scheme in which the switching electrodes are immersed in the plasma has been demonstrated on a mechanically fabricated pattern generator.

  1. Development of a diurnal rainfall pattern generator and assessment of climate change impact on flood risk in Japan

    NASA Astrophysics Data System (ADS)

    Minakawa, H.; Masumoto, T.

    2011-12-01

    An increase in flood risk, especially in low-lying areas, is predicted as a consequence of global climate change. Immediate measures are needed to minimize the damage caused by more-frequent flooding. The capacities of drainage systems in paddy areas are planned on the basis of design rainfall. For example, design rainfall may be represented by a 3-day rainfall event with a 10-year return period. However, design rainfall parameters used in Japan have not been reviewed for a few decades, and changes in rainfall patterns associated with recent climate change are not reflected in current drainage planning. The aim of this study was to develop a diurnal rainfall pattern generator and to use it to evaluate the effects of changing patterns of heavy rainfall due to climate change on flood risk in low-lying areas. Our study area was in the Kaga three-lagoon basin in Ishikawa Prefecture, Japan. There are two lagoons in the study area, and the low-lying paddy areas extend over about 4,000 ha in the lower reaches of the basin. First, we developed a drainage analysis model that incorporates kinematic and diffusive runoff models for upland and inundated areas, respectively. The model was adjusted in accordance with observed discharges and water levels for heavy rainfall events. Next, the rainfall data predicted by MIROC (a Global Climate Model developed by the Center for Climate Systems Research) were analyzed to determine the future trends of changes of heavy rainfall. Our analysis showed that probabilistic 3-day rainfall would increase in the future. In particular, 3-day rainfall events with a 10-year return period were calculated to increase from about 220 mm/3d at present to about 270 mm/3d in the future. These amounts of rainfall were used to represent the future trend of increases of heavy rainfall. Simultaneously, we developed a diurnal rainfall pattern generator based on a Monte Carlo simulation method. For this generator, the beta distribution was used to disaggregate

  2. Cell-differentiation rules that generate regular mosaic patterns: modelling motivated by cone mosaic formation in fish retina.

    PubMed

    Takesue, A; Mochizuki, A; Iwasa, Y

    1998-10-21

    We study characteristics of cell-differentiation rules that realize stable formation of regularly arranged checker-board patterns, exemplified by cone "mosaic" zebrafish retina, or the regular arrangement of cone photoreceptor cells. We consider the situation in which cells are arranged on a square lattice and are initially undifferentiated. Later each cell becomes one of the two differentiated states, affected by the state of the neighboring cells. The cells that undergo differentiation form a "morphogenetic cell row" which sweeps from one end to the other end of the lattice through time. This models an outward sweep of the margin of expanding mosaic region of the retina which occurs as undifferentiated photoreceptor cells become differentiated in concentric circles, joining the mosaic. We introduce an index to measure the ability of cell-differentiation rules to generate regular checker-board patterns from irregular initial patterns, and attempt to characterize the successful rules. We first show the importance of six "preservation conditions" which guarantee perfectly regular photoreceptor arrangement for all the rows after a regular row. Then we select an additional six "optimizing conditions" for responses to configuration that are consistently shown by the rules of high average scores. We also examine the effect of interaction between responses to different configurations. Finally we examine the concept of morphogenetic row precedence, i.e. that the successful rules generating a high score tend to treat the consistency with neighbors in the newly differentiated cells (those in the morphogenetic cell row) as more important that the consistency with previously differentiated neighbors.

  3. Sulforhodamine labeling of neural circuits engaged in motor pattern generation in the in vitro turtle brainstem-cerebellum.

    PubMed

    Keifer, J; Vyas, D; Houk, J C

    1992-08-01

    A fluorescent molecular probe was used in combination with a novel in vitro preparation to study spatial patterns of neural activity associated with motor pattern generation. The in vitro brainstem-cerebellum preparation takes advantage of the turtle's unusual resistance to anoxia to preserve the entire neural network that connects the cerebellum, red nucleus, and reticular formation. This preparation was bathed in a 0.01% solution of sulforhodamine while it was activated unilaterally by electrical stimulation of the dorsal quadrant of the spinal cord for 1 hr. Sulforhodamine is a small, sulfonated, highly charged fluorescent molecule that is taken up by endocytosis. To examine its distribution in the cerebellum and brainstem, coronal sections were prepared and viewed under epifluorescence illumination. Distinctive spatial patterns of labeling were associated with unilateral electrical stimulation of the in vitro network, suggesting that dye uptake was activity dependent. Blockade of uptake with altered magnesium and calcium concentrations indicated that single spike discharge evoked ortho- or antidromically was insufficient to induce dye uptake. Instead, sulforhodamine staining correlated with the presence of burst discharge that was recorded extracellularly from the red nucleus. Blockade of burst discharge with excitatory amino acid receptor antagonists prevented dye uptake in the red nucleus, the lateral cerebellar nucleus, and other structures that are known to be interconnected by recurrent anatomical pathways. These results suggest that sulforhodamine is internalized by intensely active neurons. The spatial distributions of label support the hypothesis that burst discharges in the turtle red nucleus are mediated by excitatory amino acid neurotransmitters and sustained by recurrent excitation in cerebellorubral synaptic pathways. Positive feedback in these recurrent pathways may provide an important driving force for the generation of motor programs that

  4. Thin film passivation of laser generated 3D micro patterns in lithium manganese oxide cathodes

    NASA Astrophysics Data System (ADS)

    Pröll, J.; Kohler, R.; Bruns, M.; Oberst, V.; Weidler, P. G.; Heißler, S.; Kübel, C.; Scherer, T.; Prang, R.; Seifert, H. J.; Pfleging, W.

    2013-03-01

    The increasing need for long-life lithium-ion batteries requires the further development of electrode materials. Especially on the cathode side new materials or material composites are needed to increase the cycle lifetime. On the one hand, spinel-type lithium manganese oxide is a promising candidate to be used as cathode material due to its non-toxicity, low cost and good thermal stability. On the other hand, the spinel structure suffers from change in the oxidation state of manganese during cycling which is also accompanied by loss of active material into the liquid electrolyte. The general trend is to enhance the active surface area of the cathode in order to increase lithium-ion mobility through the electrode/electrolyte interface, while an enhanced surface area will also promote chemical degradation. In this work, laser microstructuring of lithium manganese oxide thin films was applied in a first step to increase the active surface area. This was done by using 248 nm excimer laser radiation and chromium/quartz mask imaging techniques. In a second step, high power diode laser-annealing operating at a wavelength of 940 nm was used for forming a cubic spinel-like battery phase. This was verified by means of Raman spectroscopy and cyclic voltammetric measurements. In a last step, the laser patterned thin films were coated with indium tin oxide (ITO) layers with a thickness of 10 nm to 50 nm. The influence of the 3D surface topography as well as the ITO thickness on the electrochemical performance was studied by cyclic voltammetry. Post-mortem studies were carried out by using scanning electron microscopy and focused ion beam analysis.

  5. Flow patterns generated by vibrations in weightlessness in binary mixture with Soret effect.

    NASA Astrophysics Data System (ADS)

    Shevtsova, Valentina; Melnikov, Denis; Gaponenko, Yuri; Lyubimova, Tatyana; Mialdun, Aliaksandr; Sechenyh, Vitaliy

    2012-07-01

    Vibrational convection refers to the specific flows that appear when a fluid with density gradient is subjected to external vibration. The density gradient may result from the inhomogeneity of temperature or composition. The study of vibrational impact on fluids has fundamental and applied importance. In weightlessness, vibrational convection is an additional way of transporting heat and matter similar to thermo- and solutocapillary convection. The response of the fluid to external forcing depends on the frequency of vibration. The case of small amplitude and high frequency vibration (when the period is much smaller than the characteristic viscous and heat (mass) diffusion times) is of special interest. In this case, the mean flow can be observed in the system, which describes the non-linear response of the fluid to a periodic excitation. The mean flow is most pronounced in the absence of other external forces (in particular, absence of static gravity). The experiment IVIDIL (Influence of Vibration on Diffusion in Liquids) has been conducted on the ISS during more than 3 months in 2009-2010. In the experimental liquids the density changes due to both the temperature and composition. 55 experimental runs of IVIDIL provided rich variety of valuable information about behavior of the liquid in weightlessness which is released with time, [1-3]. The current results provide experimental and numerical evidence of richness of flow patterns and their classification. References: 1. Shevtsova V., Mialdun A., Melnikov D., Ryzhkov I., Gaponenko Y., Saghir Z., Lyubimova T., Legros J.C., IVIDIL experiment onboard ISS: thermodiffusion in presence of controlled vibrations, Comptes Rendus Mecanique, 2011, 339, 310-317 2. Shevtsova V., Lyubimova T., Saghir Z. , Melnikov D., Gaponenko Y. , Sechenyh V. , Legros J.C. , Mialdun A., IVIDIL: on-board g-jitters and diffusion controlled phenomena; Journal of Physics: Conference Series, 2011, 327, 012031 3. Mazzoni S., Shevtsova V., Mialdun A

  6. On the processes generating latitudinal richness gradients: identifying diagnostic patterns and predictions

    SciTech Connect

    Hurlbert, Allen H.; Stegen, James C.

    2014-12-02

    Many processes have been put forward to explain the latitudinal gradient in species richness. Here, we use a simulation model to examine four of the most common hypotheses and identify patterns that might be diagnostic of those four hypotheses. The hypotheses examined include (1) tropical niche conservatism, or the idea that the tropics are more diverse because a tropical clade origin has allowed more time for diversification in the tropics and has resulted in few species adapted to extra-tropical climates. (2) The productivity, or energetic constraints, hypothesis suggests that species richness is limited by the amount of biologically available energy in a region. (3) The tropical stability hypothesis argues that major climatic fluctuations and glacial cycles in extratropical regions have led to greater extinction rates and less opportunity for specialization relative to the tropics. (4) Finally, the speciation rates hypothesis suggests that the latitudinal richness gradient arises from a parallel gradient in rates of speciation. We found that tropical niche conservatism can be distinguished from the other three scenarios by phylogenies which are more balanced than expected, no relationship between mean root distance and richness across regions, and a homogeneous rate of speciation across clades and through time. The energy gradient, speciation gradient, and disturbance gradient scenarios all exhibited phylogenies which were more imbalanced than expected, showed a negative relationship between mean root distance and richness, and diversity-dependence of speciation rate estimates through time. Using Bayesian Analysis of Macroevolutionary Mixtures on the simulated phylogenies, we found that the relationship between speciation rates and latitude could distinguish among these three scenarios. We emphasize the importance of considering multiple hypotheses and focusing on diagnostic predictions instead of predictions that are consistent with more than one hypothesis.

  7. Plant species richness belowground: higher richness and new patterns revealed by next-generation sequencing.

    PubMed

    Hiiesalu, Inga; Opik, Maarja; Metsis, Madis; Lilje, Liisa; Davison, John; Vasar, Martti; Moora, Mari; Zobel, Martin; Wilson, Scott D; Pärtel, Meelis

    2012-04-01

    Variation in plant species richness has been described using only aboveground vegetation. The species richness of roots and rhizomes has never been compared with aboveground richness in natural plant communities. We made direct comparisons of grassland plant richness in identical volumes (0.1 × 0.1 × 0.1 m) above and below the soil surface, using conventional species identification to measure aboveground richness and 454 sequencing of the chloroplast trnL(UAA) intron to measure belowground richness. We described above- and belowground richness at multiple spatial scales (from a neighbourhood scale of centimetres to a community scale of hundreds of metres), and related variation in richness to soil fertility. Tests using reference material indicated that 454 sequencing captured patterns of species composition and abundance with acceptable accuracy. At neighbourhood scales, belowground richness was up to two times greater than aboveground richness. The relationship between above- and belowground richness was significantly different from linear: beyond a certain level of belowground richness, aboveground richness did not increase further. Belowground richness also exceeded that of aboveground at the community scale, indicating that some species are temporarily dormant and absent aboveground. Similar to other grassland studies, aboveground richness declined with increasing soil fertility; in contrast, the number of species found only belowground increased significantly with fertility. These results indicate that conventional aboveground studies of plant richness may overlook many coexisting species, and that belowground richness becomes relatively more important in conditions where aboveground richness decreases. Measuring plant belowground richness can considerably alter perceptions of biodiversity and its responses to natural and anthropogenic factors.

  8. DCC mediated axon guidance of spinal interneurons is essential for normal locomotor central pattern generator function.

    PubMed

    Rabe Bernhardt, Nadine; Memic, Fatima; Gezelius, Henrik; Thiebes, Anja-Lena; Vallstedt, Anna; Kullander, Klas

    2012-06-15

    Coordinated limb rhythmic movements take place through organized signaling in local spinal cord neuronal networks. The establishment of these circuitries during development is dependent on the correct guidance of axons to their targets. It has previously been shown that the well-known axon guidance molecule netrin-1 is required for configuring the circuitry that provides left-right alternating coordination in fictive locomotion. The attraction of commissural axons to the midline in response to netrin-1 has been shown to involve the netrin-1 receptor DCC (deleted in Colorectal Cancer). However, the role of DCC for the establishment of CPG coordination has not yet been resolved. We show that mice carrying a null mutation of DCC displayed an uncoordinated left-right activity during fictive locomotion accompanied by a loss of interneuronal subpopulations originating from commissural progenitors. Thus, DCC plays a crucial role in the formation of spinal neuronal circuitry coordinating left-right activities. Together with the previously published results from netrin-1 deficient mice, the data presented in this study suggest a role for the most ventral originating V3 interneurons in synchronous activities over the midline. Further, it provides evidence that axon crossing in the spinal cord is more intricately controlled than in previously suggested models of DCC-netrin-1 interaction.

  9. Design of irregular screen sets that generate maximally smooth halftone patterns

    NASA Astrophysics Data System (ADS)

    Jumabayeva, Altyngul; Chen, Yi-Ting; Frank, Tal; Ulichney, Robert; Allebach, Jan

    2015-01-01

    With the emergence of high-end digital printing technologies, it is of interest to analyze the nature and causes of image graininess in order to understand the factors that prevent high-end digital presses from achieving the same print quality as commercial offset presses. In this paper, we report on a study to understand the relationship between image graininess and halftone technology. With high-end digital printing technology, irregular screens can be considered since they can achieve a better approximation to the screen sets used for commercial offset presses. This is due to the fact that the elements of the periodicity matrix of an irregular screen are rational numbers, rather than integers, which would be the case for a regular screen. To understand how image graininess relates to the halftoning technology, we recently performed a Fourier-based analysis of regular and irregular periodic, clustered-dot halftone textures. From the analytical results, we showed that irregular halftone textures generate new frequency components near the spectrum origin; and that these frequency components are low enough to be visible to the human viewer, and to be perceived as a lack of smoothness. In this paper, given a set of target irrational screen periodicity matrices, we describe a process, based on this Fourier analysis, for finding the best realizable screen set. We demonstrate the efficacy of our method with a number of experimental results.

  10. Athletic Participation and Intimate Partner Violence Victimization: Investigating Sport Involvement, Self-Esteem, and Abuse Patterns for Women and Men.

    PubMed

    Milner, Adrienne N; Baker, Elizabeth H

    2015-05-14

    This study used representative, quantitative data from The National Longitudinal Study of Adolescent Health (Add Health) and explored the relationship between young adults' sport participation and experiences of intimate partner violence victimization (IPVV) for both women and men. Past research has suggested that sports participation, especially among women, results in increased self-esteem, a prominent protective factor against experiencing IPVV. We found that sports participation was associated with a lower prevalence of experiencing IPVV, but only for women. In addition, this pattern held after controls for race, mother's education, age, number of relationships, and the hypothesized pathways of self-esteem and alcohol consumption. However, controls for the young adult's own education completely mediated the association between sports participation and IPVV. Additional analyses indicated that higher education reduced the risk of experiencing IPVV and increased the likelihood of sports participation. Nonetheless, even among women with the highest educational attainment, sports participation was associated with lower prevalence of experiencing IPVV.

  11. Mask and wafer evaluation of Sigma7500 pattern generator applied to 65nm logic metal and via layers

    NASA Astrophysics Data System (ADS)

    Liu, Frank; Shi, Irene; Liu, Qingwei; Zhu, Likeit; Zhao, Shirley; Guo, Eric

    2009-04-01

    As pattern density and OPC complexity grow, photomask write times on electron beam tools increase in proportion. Reducing the write time would decrease mask-making costs, but the performance of any alternative mask writer must meet all of the technical requirements on both mask and wafer. In addition, it is desirable to use existing OPC models in order to avoid the costs of developing and maintaining separate OPC models for each writer. The Sigma7500 deep-UV pattern generator provides the highest resolution available from a laser-based tool, and it has the advantage of maintaining about a 3 hour write time even as the feature count increases. In this study, the Sigma7500 and a variable shaped e-beam (VSB) tool are compared on 65nm metal1 and via1 layers. In the first phase, the Sigma pattern positioning was matched to a SMIC reference grid and a registration value of 10 nm (3s) was achieved with scales removed. In the second phase, M1 and V1 masks were printed with both laser and e-beam writers using the same pattern data and compared on CD uniformity, linearity and proximity. The Sigma7500 met all of the photomask requirements for these layers. The masks were then printed on wafers and the wafer data was evaluated. The results were comparable to those for the e-beam masks and were within the requirements, indicating that the Sigma7500 can handle these layers without the need to revise the e-beam mask OPC models.

  12. Interactions between segmental leg central pattern generators during fictive rhythms in the locust.

    PubMed

    Ryckebusch, S; Laurent, G

    1994-12-01

    1. Rhythmic activity of leg motor neurons could be evoked in isolated locust thoracic ganglia as well as in preparations of two or three connected thoracic ganglia superfused with the muscarinic agonist pilocarpine. Rhythms were always more regular and reliably elicited in single isolated ganglia. When the ganglia were connected, rhythmic activity of leg motor neurons was not usually simultaneously evoked in all six hemiganglia. Typically, some of the hemiganglia were rhythmically active, whereas others showed tonic or highly irregular activity. 2. Action potentials from leg motor neuron pools were recorded extracellularly from motor nerves and cross-correlated with the use of standard algorithms. The following correlations were observed between activities of motor neurons in different hemisegments. 1) Within a segment, trochanteral levators were coactive with contralateral trochanteral depressors. This correlation was strong in the metathoracic ganglion, and weaker in the pro- and mesothoracic ganglia. 2) Coupling between levators on opposite sides of the same segment was variable in the pro- and mesothoracic ganglia, because phase relationships between levators were different in each preparation and could also change during the course of an experiment. In the metathoracic ganglion, levators on opposite sides were never coactive. 3) Trochanteral levators were often active within a short latency of levator bursts in an ipsilateral adjacent hemiganglion. In addition, levators in one segment were often inhibited during levators bursts in the ipsilateral adjacent segment. 4) Trochanteral levators were strongly coupled to ipsilateral adjacent trochanteral depressors, for all three thoracic ganglia. 3. The phase relationships between motor neuron activities revealed by cross-correlation are discussed in the context of what is known about the mechanisms involved in the control of intersegmental coupling during legged locomotion.

  13. Patterns of colonic involvement at initial presentation in ulcerative colitis: a retrospective study of 46 newly diagnosed cases.

    PubMed

    Robert, Marie E; Skacel, Mark; Ullman, Thomas; Bernstein, Charles N; Easley, Kirk; Goldblum, John R

    2004-07-01

    Studies have shown that rectal sparing and patchiness develop in treated and longstanding ulcerative colitis (UC), making the distinction from Crohn colitis increasingly difficult after treatment is initiated. However, no histologic studies of the incidence of rectal sparing in adults at UC onset have been performed. Colectomy specimens from 46 patients with classic UC histologic features and no Crohn disease features were identified. Biopsy specimens obtained before medical therapy were retrieved and examined blindly by 2 pathologists, along with appropriate control samples. Slides were scored for chronicity (crypt branching, subcryptal plasma cells, lamina propria plasma cells) and activity (cryptitis, crypt abscesses, epithelial injury). In 28 cases, only rectal biopsy specimens were taken; for 16, rectal and at least 1 proximal biopsy specimen were taken. All cases showed rectal involvement; none had rectal sparing at initial biopsy. Of 16 cases with rectal and more proximal biopsy specimens, 5 (31%) showed relative rectal sparing (lower scores in rectum than in more proximal sites). In 16 cases with rectal and more proximal biopsy specimens, chronicity and activity scores were higher in the rectum than in more proximal sites (P = .01; chronicity and activity). The mean overall chronicity score decreased in a linear manner from rectum to cecum. The rectum is involved and shows evidence of chronicity and activity at disease onset in UC, using colectomy as the gold standard for diagnosis. Because rectal sparing at UC onset has been reported, a prospective study using uniform biopsy protocols is needed to establish the true incidence of rectal sparing at presentation.

  14. Expression Patterns of Genes Involved in the Defense and Stress Response of Spiroplasma citri Infected Madagascar Periwinkle Catharanthus roseus

    PubMed Central

    Nejat, Naghmeh; Vadamalai, Ganesan; Dickinson, Matthew

    2012-01-01

    Madagascar periwinkle is an ornamental and a medicinal plant, and is also an indicator plant that is highly susceptible to phytoplasma and spiroplasma infections from different crops. Periwinkle lethal yellows, caused by Spiroplasma citri, is one of the most devastating diseases of periwinkle. The response of plants to S. citri infection is very little known at the transcriptome level. In this study, quantitative real-time PCR (RT-qPCR) was used to investigate the expression levels of four selected genes involved in defense and stress responses in naturally and experimentally Spiroplasma citri infected periwinkles. Strictosidine β-glucosidase involved in terpenoid indole alkaloids (TIAs) biosynthesis pathway showed significant upregulation in experimentally and naturally infected periwinkles. The transcript level of extensin increased in leaves of periwinkles experimentally infected by S. citri in comparison to healthy ones. A similar level of heat shock protein 90 and metallothionein expression was observed in healthy, naturally and experimentally spiroplasma-diseased periwinkles. Overexpression of Strictosidine β-glucosidase demonstrates the potential utility of this gene as a host biomarker to increase the fidelity of S. citri detection and can also be used in breeding programs to develop stable disease-resistance varieties. PMID:22408455

  15. Generations.

    PubMed

    Chambers, David W

    2005-01-01

    Groups naturally promote their strengths and prefer values and rules that give them an identity and an advantage. This shows up as generational tensions across cohorts who share common experiences, including common elders. Dramatic cultural events in America since 1925 can help create an understanding of the differing value structures of the Silents, the Boomers, Gen Xers, and the Millennials. Differences in how these generations see motivation and values, fundamental reality, relations with others, and work are presented, as are some applications of these differences to the dental profession.

  16. Expression pattern in retinal photoreceptors of POMGnT1, a protein involved in muscle-eye-brain disease

    PubMed Central

    Uribe, Mary Luz; Haro, Carmen; Campello, Laura; Cruces, Jesús; Martín-Nieto, José

    2016-01-01

    Purpose The POMGNT1 gene, encoding protein O-linked-mannose β-1,2-N-acetylglucosaminyltransferase 1, is associated with muscle-eye-brain disease (MEB) and other dystroglycanopathies. This gene’s lack of function or expression causes hypoglycosylation of α-dystroglycan (α-DG) in the muscle and the central nervous system, including the brain and the retina. The ocular symptoms of patients with MEB include retinal degeneration and detachment, glaucoma, and abnormal electroretinogram. Nevertheless, the POMGnT1 expression pattern in the healthy mammalian retina has not yet been investigated. In this work, we address the expression of the POMGNT1 gene in the healthy retina of a variety of mammals and characterize the distribution pattern of this gene in the adult mouse retina and the 661W photoreceptor cell line. Methods Using reverse transcription (RT)–PCR and immunoblotting, we studied POMGNT1 expression at the mRNA and protein levels in various mammalian species, from rodents to humans. Immunofluorescence confocal microscopy analyses were performed to characterize the distribution profile of its protein product in mouse retinal sections and in 661W cultured cells. The intranuclear distribution of POMT1 and POMT2, the two enzymes preceding POMGnT1 in the α-DG O-mannosyl glycosylation pathway, was also analyzed. Results POMGNT1 mRNA and its encoded protein were expressed in the neural retina of all mammals studied. POMGnT1 was located in the cytoplasmic fraction in the mouse retina and concentrated in the myoid portion of the photoreceptor inner segments, where the protein colocalized with GM130, a Golgi complex marker. The presence of POMGnT1 in the Golgi complex was also evident in 661W cells. However, and in contrast to retinal tissue, POMGnT1 additionally accumulated in the nucleus of the 661W photoreceptors. Colocalization was found within this organelle between POMGnT1 and POMT1/2, the latter associated with euchromatic regions of the nucleus. Conclusions

  17. Characterization of a non-chemically amplified resist for photomask fabrication using a 257-nm optical pattern generator

    NASA Astrophysics Data System (ADS)

    Rathsack, Benjamen M.; Tabery, Cyrus E.; Stachowiak, Timothy B.; Dallas, Tim E.; Xu, Cheng-Bai; Pochkowski, Mike; Willson, C. Grant

    1999-12-01

    I-line optical pattern generators using non-chemically amplified resists have become the workhorses for high throughput mask fabrication. The demand for smaller and more uniform features on photomasks has driven the development of a 257 nm optical pattern generator. A non-chemically amplified resist is being developed to maximize the performance of this new 257 nm mask tool. Resist characterization and lithography simulation are being used to formulate a non-chemically amplified resist for 257 nm optical pattern generators. Non- chemically amplified resists are advantageous for us in mask fabrication due to their storage and post-exposure stability. Chemically amplified resists may provide higher performance but they also require environmental mini-environments and a post-exposure bake equipment not commonly present in mask houses. Diazonaphthoquinone (DNQ)/novolak resists have not been used for DUV Integrated Circuit (IC) applications mainly due to the low sensitivity and the strong absorbance of the DNQ photoactive compound (PAC) at 248 nm. However, a 2,1,4 DNQ based resist has been characterized that bleaches at 257 nm and inhibits novolak. The photoproduct of the 2,1,4 DNQ PAC is much more transparent at 257 nm than 248 nm. Novolak resin is too strongly absorbing for use in formulating efficient 248 nm resists, but novolak has an absorbance minimum at 257 nm that provides transparency similar to poly (hydroxystyrene). Lithography simulation is being used to develop a non- chemically amplified resist to minimize the expensive iteration of manufacturing trials. An exposure system using a 257 nm frequency double Ar laser system has been constructed to study the resist photokinetics. Dill exposure parameters (A, B and C) have been extracted for a 2,1,4 DNQ/novolak based resist. Dissolution rate measurements have been made with a DRM developed at the University of Texas at Austin. Simulation is used to determine the optimal resist absorption, bleaching, dose and

  18. The Drosophila Retinoblastoma Binding Protein 6 Family Member Has Two Isoforms and Is Potentially Involved in Embryonic Patterning

    PubMed Central

    Hull, Rodney; Oosthuysen, Brent; Cajee, Umar-Faruq; Mokgohloa, Lehlogonolo; Nweke, Ekene; Antunes, Ricardo Jorge; Coetzer, Theresa H. T.; Ntwasa, Monde

    2015-01-01

    The human retinoblastoma binding protein 6 (RBBP6) is implicated in esophageal, lung, hepatocellular and colon cancers. Furthermore, RBBP6 was identified as a strong marker for colon cancer prognosis and as a predisposing factor in familial myeloproliferative neoplasms. Functionally, the mammalian protein interacts with p53 and enhances the activity of Mdm2, the prototypical negative regulator of p53. However, since RBBP6 (known as PACT in mice) exists in multiple isoforms and pact−/− mice exhibit a more severe phenotype than mdm2−/− mutants, it must possess some Mdm2-independent functions. The function of the invertebrate homologue is poorly understood. This is complicated by the absence of the Mdm2 gene in both Drosophila and Caenorhabditis elegans. We have experimentally identified the promoter region of Snama, the Drosophila homologue, analyzed potential transcription factor binding sites and confirmed the existence of an additional isoform. Using band shift and co-immunoprecipitation assays combined with mass spectrometry, we found evidence that this gene may be regulated by, amongst others, DREF, which regulates hundreds of genes related to cell proliferation. The potential transcription factors for Snama fall into distinct functional groups, including anteroposterior embryonic patterning and nucleic acid metabolism. Significantly, previous work in mice shows that pact−/− induces an anteroposterior phenotype in embryos when rescued by simultaneous deletion of p53. Taken together, these observations indicate the significance of RBBP6 proteins in carcinogenesis and in developmental defects. PMID:25955646

  19. Brainstem Involvement as a Cause of Central Sleep Apnea: Pattern of Microstructural Cerebral Damage in Patients with Cerebral Microangiopathy

    PubMed Central

    Duning, Thomas; Deppe, Michael; Brand, Eva; Stypmann, Jörg; Becht, Charlotte; Heidbreder, Anna; Young, Peter

    2013-01-01

    Background The exact underlying pathomechanism of central sleep apnea with Cheyne-Stokes respiration (CSA-CSR) is still unclear. Recent studies have demonstrated an association between cerebral white matter changes and CSA. A dysfunction of central respiratory control centers in the brainstem was suggested by some authors. Novel MR-imaging analysis tools now allow far more subtle assessment of microstructural cerebral changes. The aim of this study was to investigate whether and what severity of subtle structural cerebral changes could lead to CSA-CSR, and whether there is a specific pattern of neurodegenerative changes that cause CSR. Therefore, we examined patients with Fabry disease (FD), an inherited, lysosomal storage disease. White matter lesions are early and frequent findings in FD. Thus, FD can serve as a "model disease" of cerebral microangiopathy to study in more detail the impact of cerebral lesions on central sleep apnea. Patients and Methods Genetically proven FD patients (n = 23) and age-matched healthy controls (n = 44) underwent a cardio-respiratory polysomnography and brain MRI at 3.0 Tesla. We applied different MR-imaging techniques, ranging from semiquantitative measurement of white matter lesion (WML) volumes and automated calculation of brain tissue volumes to VBM of gray matter and voxel-based diffusion tensor imaging (DTI) analysis. Results In 5 of 23 Fabry patients (22%) CSA-CSR was detected. Voxel-based DTI analysis revealed widespread structural changes in FD patients when compared to the healthy controls. When calculated as a separate group, DTI changes of CSA-CSR patients were most prominent in the brainstem. Voxel-based regression analysis revealed a significant association between CSR severity and microstructural DTI changes within the brainstem. Conclusion Subtle microstructural changes in the brainstem might be a neuroanatomical correlate of CSA-CSR in patients at risk of WML. DTI is more sensitive and specific than

  20. Spatial Pattern of Copper Phosphate Precipitation Involves in Copper Accumulation and Resistance of Unsaturated Pseudomonas putida CZ1 Biofilm.

    PubMed

    Chen, Guangcun; Lin, Huirong; Chen, Xincai

    2016-12-28

    Bacterial biofilms are spatially structured communities that contain bacterial cells with a wide range of physiological states. The spatial distribution and speciation of copper in unsaturated Pseudomonas putida CZ1 biofilms that accumulated 147.0 mg copper per g dry weight were determined by transmission electron microscopy coupled with energy dispersive X-ray analysis, and micro-X-ray fluorescence microscopy coupled with micro-X-ray absorption near edge structure (micro-XANES) analysis. It was found that copper was mainly precipitated in a 75 μm thick layer as copper phosphate in the middle of the biofilm, while there were two living cell layers in the air-biofilm and biofilm-medium interfaces, respectively, distinguished from the copper precipitation layer by two interfaces. The X-ray absorption fine structure analysis of biofilm revealed that species resembling Cu₃(PO₄)₂ predominated in biofilm, followed by Cu-Citrate- and Cu-Glutathione-like species. Further analysis by micro-XANES revealed that 94.4% of copper were Cu₃(PO₄)₂-like species in the layer next to the air interface, whereas the copper species of the layer next to the medium interface were composed by 75.4% Cu₃(PO₄)₂, 10.9% Cu-Citrate-like species, and 11.2% Cu-Glutathione-like species. Thereby, it was suggested that copper was initially acquired by cells in the biofilm-air interface as a citrate complex, and then transported out and bound by out membranes of cells, released from the copper-bound membranes, and finally precipitated with phosphate in the extracellular matrix of the biofilm. These results revealed a clear spatial pattern of copper precipitation in unsaturated biofilm, which was responsible for the high copper tolerance and accumulation of the biofilm.

  1. Pattern search in multi-structure data: a framework for the next-generation evidence-based medicine

    NASA Astrophysics Data System (ADS)

    Sukumar, Sreenivas R.; Ainsworth, Keela C.

    2014-03-01

    With the impetus towards personalized and evidence-based medicine, the need for a framework to analyze/interpret quantitative measurements (blood work, toxicology, etc.) with qualitative descriptions (specialist reports after reading images, bio-medical knowledgebase, etc.) to predict diagnostic risks is fast emerging. Addressing this need, we pose and answer the following questions: (i) How can we jointly analyze and explore measurement data in context with qualitative domain knowledge? (ii) How can we search and hypothesize patterns (not known apriori) from such multi-structure data? (iii) How can we build predictive models by integrating weakly-associated multi-relational multi-structure data? We propose a framework towards answering these questions. We describe a software solution that leverages hardware for scalable in-memory analytics and applies next-generation semantic query tools on medical data.

  2. Next generation sequencing (NGS) database for tandem repeats with multiple pattern 2°-shaft multicore string matching

    PubMed Central

    Someswara Rao, Chinta; Raju, S. Viswanadha

    2016-01-01

    Next generation sequencing (NGS) technologies have been rapidly applied in biomedical and biological research in recent years. To provide the comprehensive NGS resource for the research, in this paper , we have considered 10 loci/codi/repeats TAGA, TCAT, GAAT, AGAT, AGAA, GATA, TATC, CTTT, TCTG and TCTA. Then we developed the NGS Tandem Repeat Database (TandemRepeatDB) for all the chromosomes of Homo sapiens, Callithrix jacchus, Chlorocebus sabaeus, Gorilla gorilla, Macaca fascicularis, Macaca mulatta, Nomascus leucogenys, Pan troglodytes, Papio anubis and Pongo abelii genome data sets for all those locis. We find the successive occurence frequency for all the above 10 SSR (simple sequence repeats) in the above genome data sets on a chromosome-by-chromosome basis with multiple pattern 2° shaft multicore string matching. PMID:26981434

  3. Accrual Patterns for Clinical Studies Involving Quantitative Imaging: Results of an NCI Quantitative Imaging Network (QIN) Survey

    PubMed Central

    Kurland, Brenda F.; Aggarwal, Sameer; Yankeelov, Thomas E.; Gerstner, Elizabeth R.; Mountz, James M.; Linden, Hannah M.; Jones, Ella F.; Bodeker, Kellie L.; Buatti, John M.

    2017-01-01

    Patient accrual is essential for the success of oncology clinical trials. Recruitment for trials involving the development of quantitative imaging biomarkers may face different challenges than treatment trials. This study surveyed investigators and study personnel for evaluating accrual performance and perceived barriers to accrual and for soliciting solutions to these accrual challenges that are specific to quantitative imaging-based trials. Responses for 25 prospective studies were received from 12 sites. The median percent annual accrual attained was 94.5% (range, 3%–350%). The most commonly selected barrier to recruitment (n = 11/25, 44%) was that “patients decline participation,” followed by “too few eligible patients” (n = 10/25, 40%). In a forced choice for the single greatest recruitment challenge, “too few eligible patients” was the most common response (n = 8/25, 32%). Quantitative analysis and qualitative responses suggested that interactions among institutional, physician, and patient factors contributed to accrual success and challenges. Multidisciplinary collaboration in trial design and execution is essential to accrual success, with attention paid to ensuring and communicating potential trial benefits to enrolled and future patients. PMID:28127586

  4. Extreme ultraviolet patterned mask inspection performance of advanced projection electron microscope system for 11nm half-pitch generation

    NASA Astrophysics Data System (ADS)

    Hirano, Ryoichi; Iida, Susumu; Amano, Tsuyoshi; Watanabe, Hidehiro; Hatakeyama, Masahiro; Murakami, Takeshi; Suematsu, Kenichi; Terao, Kenji

    2016-03-01

    Novel projection electron microscope optics have been developed and integrated into a new inspection system named EBEYE-V30 ("Model EBEYE" is an EBARA's model code) , and the resulting system shows promise for application to half-pitch (hp) 16-nm node extreme ultraviolet lithography (EUVL) patterned mask inspection. To improve the system's inspection throughput for 11-nm hp generation defect detection, a new electron-sensitive area image sensor with a high-speed data processing unit, a bright and stable electron source, and an image capture area deflector that operates simultaneously with the mask scanning motion have been developed. A learning system has been used for the mask inspection tool to meet the requirements of hp 11-nm node EUV patterned mask inspection. Defects are identified by the projection electron microscope system using the "defectivity" from the characteristics of the acquired image. The learning system has been developed to reduce the labor and costs associated with adjustment of the detection capability to cope with newly-defined mask defects. We describe the integration of the developed elements into the inspection tool and the verification of the designed specification. We have also verified the effectiveness of the learning system, which shows enhanced detection capability for the hp 11-nm node.

  5. Hindbrain medulla catecholamine cell group involvement in lactate-sensitive hypoglycemia-associated patterns of hypothalamic norepinephrine and epinephrine activity.

    PubMed

    Shrestha, P K; Tamrakar, P; Ibrahim, B A; Briski, K P

    2014-10-10

    Cell-type compartmentation of glucose metabolism in the brain involves trafficking of the oxidizable glycolytic end product, l-lactate, by astrocytes to fuel neuronal mitochondrial aerobic respiration. Lactate availability within the hindbrain medulla is a monitored function that regulates systemic glucostasis as insulin-induced hypoglycemia (IIH) is exacerbated by lactate repletion of that brain region. A2 noradrenergic neurons are a plausible source of lactoprivic input to the neural gluco-regulatory circuit as caudal fourth ventricular (CV4) lactate infusion normalizes IIH-associated activation, e.g. phosphorylation of the high-sensitivity energy sensor, adenosine 5'-monophosphate-activated protein kinase (AMPK), in these cells. Here, we investigated the hypothesis that A2 neurons are unique among medullary catecholamine cells in directly screening lactate-derived energy. Adult male rats were injected with insulin or vehicle following initiation of continuous l-lactate infusion into the CV4. Two hours after injections, A1, C1, A2, and C2 neurons were collected by laser-microdissection for Western blot analysis of AMPKα1/2 and phosphoAMPKα1/2 proteins. Results show that AMPK is expressed in each cell group, but only a subset, e.g. A1, C1, and A2 neurons, exhibit increased sensor activity in response to IIH. Moreover, hindbrain lactate repletion reversed hypoglycemic augmentation of pAMPKα1/2 content in A2 and C1 but not A1 cells, and normalized hypothalamic norepinephrine and epinephrine content in a site-specific manner. The present evidence for discriminative reactivity of AMPK-expressing medullary catecholamine neurons to the screened energy substrate lactate implies that that lactoprivation is selectively signaled to the hypothalamus by A2 noradrenergic and C1 adrenergic cells.