Deterministic Switch Research Articles

SEX REVERSAL IN ANIMAL KINGDOM : SPECIAL EMPHASIS ON ROLE OF STEROID HORMONES

Sexual fate is no longer seen as an irreversible deterministic switch set during early embryonic development but as an ongoing battle for primacy between male and female developmental trajectories. That sexual fate is not final and must be actively maintained via continuous suppression of the opposing sexual network creates the potential for flexibility into adulthood. In many Animals, sexuality is not only extremely plastic, but sex change is a usual and adaptive part of the life cycle. Sequential hermaphrodites begin life as one sex, changing sometime later to the other, and include species capable of protandrous (male- to-female), protogynous (female-to-male), or serial (bidirectional) sex change. Natural sex change involves coordinated transformations across multiple biological systems, including behavioural, anatomical, neuroendocrine, and molecular axes. This can be caused by human pollutants, including herbicides, which can act as estrogen promoters or inhibitors, which would respectively increase or decrease the number of female offspring, through controlling aromatase. This review project paper highlights the biological processes underlying this amazing transformation, Gonadal restructuring among germinal and somatic cell interaction, Neuroendocrine control of sex change and Stress response and role of Steroid hormones-balance between 17beta-estradiol & 11- ketotestosterone in sex changes, Endocrine disruption on Changing of Sexual Behaviour, which remains poorly understood, but where new genomic technologies are significantly advancing our understanding of how sex change is initiated and progressed at Hormonal and molecular levels. Knowledge of how a usually committed developmental process remains plastic in sequentially hermaphroditic fishes, Amphibians and Birds are relevant to understanding the evolution and functioning of sexual developmental systems in vertebrates generally, as well as pathologies of sexual development in mammals, some time observed in nematodes and Gastropodes also. Keywords- sex change, hormones, hermaphrodism

Study of Grain Growth in a Ni-Based Superalloy by Experiments and Cellular Automaton Model.

The grain growth behavior in a typical Ni-based superalloy was investigated using isothermal heat treatment experiments over a holding temperature range of 1353–1473 K. The experimental results showed that the grain structure continuously coarsened as the holding time and holding temperature increased during heat treatment. A classical parabolic grain growth model was used to explore the mechanism of grain growth under experimental conditions. The grain growth exponent was found to be slightly above 2. This indicates that the current grain growth in the studied superalloy is mainly governed by grain boundary migration with a minor pinning effect from the precipitates. Then, the grain growth in the studied superalloy during isothermal heat treatment was modelled by a cellular automaton (CA) with deterministic state switch rules. The microscale kinetics of grain growth is described by the correlation between the moving velocity and curvature of the grain boundary. The local grain boundary curvature is well evaluated by a template disk method. The grain boundary mobility was found to increase with increasing temperature. The relationship between the grain boundary mobility and temperature has been established. The developed CA model is capable of capturing the dependence of the grain size on the holding time under different holding temperatures.

Strain-mediated electric manipulation of magnetic skyrmion and other topological states in geometric confined nanodiscs

Magnetic skyrmions in multilayer stack structures are promising magnetic memory bits for applications in race-track storage devices or random-access memories. For practical implementation in energy efficient memory devices, it is essential to achieve a deterministic switch of skyrmion states, e.g. nucleation and elimination, triggered by electric fields. In this work, by means of micromagnetic simulation, we demonstrate the strain-mediated electric field driven switching of magnetic skyrmion and other topological states without the presence of a magnetic field in a proposed device consisting of nanodiscs of trilayer Pt/Co/Ta stacks on a piezoelectric substrate. It is revealed that the multiple magnetic state switching behaviors, including the nucleation and elimination of skyrmion or labyrinth stripe domain states, as well as topological transitions between skyrmion, vortex, skyrmionium and vertical single domain states, can be triggered by applying an external electric field mediated by strains. The corresponding critical strains and their dependence on the geometric parameters of the nanodiscs (e.g. size and number of stacks) for triggering such magnetic switching are also explored. The stability of these topological domain states and possible switching behaviors (e.g. volatile and non-volatile) between the different states are discussed as well. The capability for controlled switching of these topological states provides a new pathway to energy efficient high-density magnetoelectric memory and logic devices.

A computational method for the investigation of multistable systems and its application to genetic switches.

BackgroundGenetic switches exhibit multistability, form the basis of epigenetic memory, and are found in natural decision making systems, such as cell fate determination in developmental pathways. Synthetic genetic switches can be used for recording the presence of different environmental signals, for changing phenotype using synthetic inputs and as building blocks for higher-level sequential logic circuits. Understanding how multistable switches can be constructed and how they function within larger biological systems is therefore key to synthetic biology.ResultsHere we present a new computational tool, called StabilityFinder, that takes advantage of sequential Monte Carlo methods to identify regions of parameter space capable of producing multistable behaviour, while handling uncertainty in biochemical rate constants and initial conditions. The algorithm works by clustering trajectories in phase space, and iteratively minimizing a distance metric. Here we examine a collection of models of genetic switches, ranging from the deterministic Gardner toggle switch to stochastic models containing different positive feedback connections. We uncover the design principles behind making bistable, tristable and quadristable switches, and find that rate of gene expression is a key parameter. We demonstrate the ability of the framework to examine more complex systems and examine the design principles of a three gene switch. Our framework allows us to relax the assumptions that are often used in genetic switch models and we show that more complex abstractions are still capable of multistable behaviour.ConclusionsOur results suggest many ways in which genetic switches can be enhanced and offer designs for the construction of novel switches. Our analysis also highlights subtle changes in correlation of experimentally tunable parameters that can lead to bifurcations in deterministic and stochastic systems. Overall we demonstrate that StabilityFinder will be a valuable tool in the future design and construction of novel gene networks.Electronic supplementary materialThe online version of this article (doi:10.1186/s12918-016-0375-z) contains supplementary material, which is available to authorized users.

Design of a Deterministic Service Switch for Avionics Networks

Avionics full-duplex switched Ethernet, with its capability of delivering deterministic latency at low deployment costs, represents a major advance for avionics communication systems. However, avionics full-duplex switched Ethernet does not eliminate contentions at network switches, which may result in an uncontrolled increase in end-to-end latencies, and hence limit the potential of this technology. The use of time to pace packet transmission and forwarding (that is, the adoption of pipeline forwarding) has been demonstrated to avoid contentions at switching nodes in wide-area communication networks, thus being potentially attractive also for avionics networks in general, and avionics full-duplex switched Ethernet in particular. However, questions might arise concerning the actual feasibility of such an approach in the avionics domain due to the possibly high costs required to deploy packet switches able to operate according to a very precise time schedule, which is necessary to respect the stringent delivery deadlines of avionics systems. This paper focuses on the development of a pipeline forwarding switch, showing how simple design guidelines allow a general-purpose symmetric multiprocessor architecture (such as modern personal computers) to offer deterministic and low latency delivery, thus being able to satisfy avionics requirements. The paper also describes a real implementation of a pipeline forwarding switch prototype, based on a dual-processor personal computer and the FreeBSD operating system.

On the Gaussian Half-Duplex Relay Channel

This paper considers Gaussian relay networks where a source transmits a message to a sink terminal with the help of one or more relay nodes. The relays work in half-duplex mode, in the sense that they can not transmit and receive at the same time. For the case of one relay, the generalized Degrees-of-Freedom is characterized first and then it is shown that capacity can be achieved to within a constant gap regardless of the actual value of the channel parameters. Different achievable schemes are presented with either deterministic or random switch for the relay node. It is shown that random switch in general achieves higher rates than deterministic switch. For the case of K relays, it is shown that the generalized Degrees-of-Freedom can be obtained by solving a linear program and that capacity can be achieved to within a constant gap of K/2log(4K). This gap may be further decreased by considering more structured networks such as, for example, the diamond network.

Cellular automata modeling of static recrystallization based on the curvature driven subgrain growth mechanism

A two-dimensional cellular automata model was developed to describe the static recrystallization (SRX) arising from the subgrain growth, the driving force of which is dependent on boundary energy and local curvature. At the same time, the subgrain boundary energy and mobility rely on the boundary misorientation angle. On the basis, a deterministic switch rule was adopted to simulate the subgrain growth and kinetics of recrystallization quantitatively to provide an insight into the grain boundary bulging nucleation mechanism. Microstructure evolutions during SRX in different cases were simulated by the developed model. At the beginning of the simulation, the initial polycrystalline microstructure which contains large number of uniformly distributed subgrains in every pre-existing grain was prepared using simple assumption based on experimental observations. Then, both homogeneous and inhomogeneous subgrain growth phenomena were captured by the simulation with different inter-subgrain misorientation, which showed continuous and discontinuous recrystallization, respectively. The effects of initial mean subgrain radius, distribution of initial subgrains, distribution of inter-subgrain misorientations, and annealing temperature on the recrystallization kinetics were also investigated.

Wide-Field Multispectral Super-Resolution Imaging Using Spin-Dependent Fluorescence in Nanodiamonds

Recent advances in fluorescence microscopy have enabled spatial resolution below the diffraction limit by localizing multiple temporally or spectrally distinguishable fluorophores. Here, we introduce a super-resolution technique that deterministically controls the brightness of uniquely addressable, photostable emitters. We modulate the fluorescence brightness of negatively charged nitrogen-vacancy (NV(-)) centers in nanodiamonds through magnetic resonance techniques. Using a CCD camera, this "deterministic emitter switch microscopy" (DESM) technique enables super-resolution imaging with localization down to 12 nm across a 35 × 35 μm(2) area. DESM is particularly well suited for biological applications such as multispectral particle tracking since fluorescent nanodiamonds are not only cytocompatible but also nonbleaching and bright. We observe fluorescence count rates exceeding 1.5 × 10(6) photons per second from single NV(-) centers at saturation. When combined with emerging NV(-)-based techniques for sensing magnetic and electric fields, DESM opens the door to rapid, super-resolution imaging for tracking and sensing applications in the life and physical sciences.

Transcription Stochasticity of Complex Gene Regulation Models

Transcription is regulated by a multitude of factors that concertedly induce genes to switch between activity states. Eukaryotic transcription involves a multitude of complexes that sequentially assemble on chromatin under the influence of transcription factors and the dynamic state of chromatin. Prokaryotic transcription depends on transcription factors, sigma-factors, and, in some cases, on DNA looping. We present a stochastic model of transcription that considers these complex regulatory mechanisms. We coarse-grain the molecular details in such a way that the model can describe a broad class of gene-regulation mechanisms. We solve this model analytically for various measures of stochastic transcription and compare alternative gene-regulation designs. We find that genes with complex multiprotein regulation can have peaked burst-size distributions in contrast to the geometric distributions found for simple models of transcription regulation. Burst-size distributions are, in addition, shaped by mRNA degradation during transcription bursts. We derive the stochastic properties of genes in the limit of deterministic switch times. These genes typically have reduced transcription noise. Severe timescale separation between gene regulation and transcription initiation enhances noise and leads to bimodal mRNA copy number distributions. In general, complex mechanisms for gene regulation lead to nonexponential waiting-time distributions for gene switching and transcription initiation, which typically reduce noise in mRNA copy numbers and burst size. Finally, we discuss that qualitatively different gene regulation models can often fit the same experimental data on single-cell mRNA abundance even though they have qualitatively different burst-size statistics and regulatory parameters.

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Quasi-Output-Buffered Switches

It is well known that output-buffered switches have better performance than other switch architectures. However, output buffered switches also suffer from the notorious scalability problem, and direct constructions of large output-buffered switches are difficult. In this paper, we study the problem of constructing scalable switches that have comparable performance (in the sense of 100 percent throughput and first-in first-out (FIFO) delivery of packets from the same flow) to output-buffered switches. For this, we propose a new concept, called quasi-output-buffered switch. Like an output-buffered switch, a quasi-output-buffered switch is a deterministic switch that achieves 100 percent throughput and delivers packets from the same flow in the FIFO order. Using the three stage Clos network, we show that one can recursively construct a larger quasi-output-buffered switch with a set of smaller quasi output-buffered switches. By recursively expanding the three-stage Clos network, we obtain a quasi-output-buffered switch with only 2 × 2 switches. Such a switch is called a packet-pair switch in this paper as it always transmits packets in pairs. By computer simulations, we show that packet-pair switches have better delay performance than most load-balanced switches with comparable construction complexity.

Padded Frames: A Novel Algorithm for Stable Scheduling in Load-Balanced Switches

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The load-balanced Birkhoff-von Neumann switching architecture consists of two stages: a load balancer and a deterministic input-queued crossbar switch. The advantages of this architecture are its simplicity and scalability, while its main drawback is the possible out-of-sequence reception of packets belonging to the same flow. Several solutions have been proposed to overcome this problem; among the most promising are the Uniform Frame Spreading (UFS) and the Full Ordered Frames First (FOFF) algorithms. In this paper, we present a new algorithm called Padded Frames (PF), which eliminates the packet reordering problem, achieves 100% throughput, and improves the delay performance of previously known algorithms. </para>

Promoting cooperation by local contribution under stochastic win-stay-lose-shift mechanism

We introduce a stochastic win-stay-lose-shift (WSLS) mechanism into evolutionary Prisoner’s Dilemma on small-world networks. At each time step, after playing with all its immediate neighbors, each individual gets a score to evaluate its performance in the game. The score is a linear combination of an individual’s total payoff (i.e., individual gain from the group) and local contribution to its neighbors (i.e., individual donation to the group). If one’s actual score is not larger than its desired score aspiration, it switches current strategy to the opposite one with the probability depending on the difference between the two scores. Under this stochastic WSLS regime, we assume that each focal individual gains its fixed score aspiration under the condition of full cooperation in its neighborhood, and find that cooperation is significantly enhanced under some certain parameters of the model by studying the evolution of cooperation. We also explore the influences of different values of learning rate and intensity of deterministic switch on the evolution of cooperation. Simulation results show that cooperation level monotonically increases with the relative weight of the local contribution to the score. For much low intensity of deterministic switch, cooperation is to a large extent independent of learning rate, and full cooperation can be reached when relative weight is not less than 0.5. Otherwise, cooperation level is affected by the value of learning rate. Besides, we find that the cooperation level is not sensitive to the topological parameters. To explain these simulation results, we provide corresponding analytical results based on mean-field approximation, and find out that simulation results are in close agreement with the analytical ones. Our work may be helpful in understanding the cooperative behavior in social systems based on this stochastic WSLS mechanism.

CONTROLLING CIOQ SWITCHES WITH PRIORITY QUEUING AND IN MULTISTAGE INTERCONNECTION NETWORKS

Combined input and output queued (CIOQ) architectures with a moderate fabric speedupS &gt; 1 have come to play a major role in the design of high performance switches. In this paper we study CIOQ switches in two settings. The first is a setting of a single CIOQ switch with Priority Queuing (PQ) buffers, which provide better Quality of Service (QoS) guarantees by decreasing the delay experienced by mission-critical and real-time traffic. The second is a setting of a Multistage Interconnection Network (MIN), where each Switching Element (SE) is a CIOQ switch. In the first setting, we consider the case of traffic with packets having variable values. The goal of the switch policy is to maximize the total value of packets sent out of the switch. We present a switch policy that is 6-competitive for any speedup. In the second setting, we study a MIN architecture in which each internal buffer is further divided into virtual buffers, one per each MIN output port reachable from that buffer. We consider the case of traffic with unit value packets, and the goal of the policy managing the MIN is to maximize the total number of packets sent out of the MIN. We give a local memoryless switch policy that uses back pressure and achieves a competitive ratio of (4h + 1), where h is the number of stages of the MIN. The proposed policy is simple and can be efficiently implemented at high speeds. We also demonstrate a lower bound of h/2 on the competitive ratio of any local work-conserving deterministic memoryless switch policy. We further show that without back pressure, no online local work-conserving deterministic switch policy can break the competitive ratio of [Formula: see text], where N is the size of the MIN and k is the size of an SE.

Cooperation in Networked Prisoner's Dilemma with Individual Learning Feedback

Abstract We introduce a modified learning updating mechanism into the evolutionary Prisoner's Dilemma on Newman-Watts (NW) networks. During the evolutionary process, each individual updates its strategy according to individual deterministic switch in combination with a feedback between its score aspiration and actual score. And individual's score is a linear combination of individual's total payoff and local contribution to its neighbors. We study the cooperation level of the system under this learning feedback mechanism, and find that the cooperation level increases as the relative weight of the local contribution to the score increases. In addition, we focus on the influences of learning rate and intensity of deterministic switch in the strategy updating rule on cooperation. Simulations show that for much low intensity of deterministic switch, cooperation is independent of learning rate to a large extent, and full cooperation can be reached when relative weight is not less than 0***.5. Otherwise, cooperation depends on the value of learning rate. Besides, the cooperation level is not sensitive to topological parameters of NW networks. To explain these simulation results, we provide corresponding analytical results of mean-field approximation, and find that simulation results are in good agreement with analytical ones. Our work may shed some light on the maintenance of cooperative behavior in social systems with individual learning feedback.

시간 결정성을 보장하는 실시간 태스크 스케줄링

오늘날의 내장형 시스템은 군사 무기체계, 로봇, 인공위성 등과 같이 전통적인 내장형 시스템에서 휴대폰, 디지털 캠코더, PMP, MP3플레이어와 같은 보다 복잡한 응용프로그램 구동을 필요로 하는 휴대용 시스템으로 그 영역을 넓혀가고 있다. 이런 내장형 실시간 시스템은 내장형 시스템의 한정된 자원을 효율적으로 관리하고 시간적 논리적 정확성을 보장하기 위해 실시간 운영체제를 사용한다. 실시간 운영체제의 서비스를 통해 응용프로그래머는 응용프로그램을 구성하는 각 태스크가 시간 결정성에 위배되지 않도록 응용프로그램을 구현할 수 있다. 더욱이, 실시간 운영체제는 시간 결정성 보장을 위해 스케줄링과 문맥교환에 사용되는 시간을 예측할 수 있어야 한다. 본 논문에서는 추가적인 메모리 오버헤드 없이 22r 레벨의 우선순위를 갖는 시스템에서 고정 상수 시간 내에 가장 높은 우선순위를 갖는 태스크를 결정할 수 있는 알고리즘에 대해 기술한다. In recent years, embedded systems have been expanding their application domains from traditional applications (such as defense, robots, and artificial satellites) to portable devices which execute more complicated applications such as cellular phones, digital camcoders, PMPs, and MP3 players. So as to manage restricted hardware resources efficiently and to guarantee both temporal and logical correctness, every embedded system use a real-time operating system (RTOS). Only when the RTOS makes kernel services deterministic in time by specifying how long each service call will take to execute, application programers can write predictable applications. Moreover, so as for an RTOS to be deterministic, its scheduling and context switch overhead should also be predictable. In this paper, we present the complete generalized algorithm to determine the highest priority in the ready list with 22r levels of priorities in a constant time without additional memory overhead.

A mesoscale cellular automaton model for curvature-driven grain growth

A two-dimensional mesoscale cellular automaton algorithm is developed to simulate curvature-driven grain growth during materials processing. In the present model, a deterministic switch rule for the grain growth is adopted, and thus the kinetics of the grain growth can be simulated quantitatively. In addition, the grain-boundary energy is dependent on the misorientation between neighboring grains. At mesoscale, the simulations show that each grain displays a unique growth behavior. The growth behavior of individual grains can be categorized into four types: (1) grains with monotonically increasing equivalent diameters, (2) grains that first grow and then begin to shrink, (3) grains with almost constant diameters, and (4) grains that decrease in size. Furthermore, an oscillation grain-growth behavior is observed in the present mesoscale cellular automaton simulations. This simulated individual grain-growth behavior has not been reported in the literature.

Energy Aware Computing through Probabilistic Switching: A Study of Limits

The main result in this paper establishes the energy savings derived by using probabilistic AND as well as NOT gates constructed from an idealized switch that produces a probabilistic bit (PBIT). A probabilistic switch produces the desired value as an output that is 0 or 1 with probability p, represented as a PBIT, and, hence, can produce the wrong output value with a probability of (1-p). In contrast with a probabilistic switch, a conventional deterministic switch produces a BIT whose value is always correct. Our switch-based gate constructions are a particular case of a systematic methodology developed for building energy-aware networks for computing, using PBITS. Interesting examples of such networks include AND, OR, and NOT gates (or, as functions, Boolean conjunction, disjunction, and negation, respectively). To quantify the energy savings, novel measures of "technology independent" energy complexity are also introduced - these measures parallel conventional machine-independent notions of computational complexity such as the algorithm's running time and space. Networks of switches can be related to Turing machines and to Boolean circuits, both of which are widely known and well-understood models of computation. Our gate and network constructions lend substance to the following thesis (established for the first time by K.V. Palem): the mathematical technique referred to as randomization yielding probabilistic algorithms results in energy savings through a physical interpretation based on statistical thermodynamics and, hence, can serve as a basis for energy-aware computing. While the estimates of the energy saved through PBIT-based probabilistic computing switches and networks developed rely on the constructs and thermodynamic models due to Boltzmann, Gibbs, and Planck, this work has also led to the innovation of probabilistic CMOS-based devices and computing frameworks. Thus, for completeness, the relationship between the physical models on which this work is based and the electrical domain of CMOS-based switching is discussed.

Self-Consistent Proteomic Field Theory of Stochastic Gene Switches

We present a self-consistent field approximation approach to the problem of the genetic switch composed of two mutually repressing/activating genes. The protein and DNA state dynamics are treated stochastically and on an equal footing. In this approach the mean influence of the proteomic cloud created by one gene on the action of another is self-consistently computed. Within this approximation a broad range of stochastic genetic switches may be solved exactly in terms of finding the probability distribution and its moments. A much larger class of problems, such as genetic networks and cascades, also remain exactly solvable with this approximation. We discuss, in depth, certain specific types of basic switches used by biological systems and compare their behavior to the expectation for a deterministic switch.