Triggering Regime Research Articles

SAINT (Small Aperture Imaging Network Telescope)—A Wide-Field Telescope Complex for Detecting and Studying Optical Transients at Times from Milliseconds to Years

In this paper, we present a project of a multi-channel wide-field optical sky monitoring system with high temporal resolution—Small Aperture Imaging Network Telescope (SAINT)— mostly built from off-the-shelf components and aimed towards searching and studying optical transient phenomena on the shortest time scales. The instrument consists of twelve channels each containing 30 cm (F/1.5) GENON Max objectives mounted on separate ASA DDM100 mounts with pointing speeds up to 50 deg/s. Each channel is equipped with a 4128 × 4104 pixel Andor Balor sCMOS detector and a set of photometric griz filters and linear polarizers. At the heart of every channel is a custom-built reducer-collimator module allowing rapid switching of an effective focal length of the telescope—due to it the system is capable of operating in either wide-field survey or narrow-field follow-up modes. In the first case, the field of view of the instrument is 470 square degrees (39 sq.deg. for a single channel) and the detection limits (5σ level at 5500 Å) are 12.5, 16.5, 19, 21 with exposure times of 20 ms, 1 s, 30 s and 20 min, correspondingly. In the second, follow-up (e.g., upon detection of a transient of interest by either a real-time detection pipeline, or upon receiving an external trigger) regime, all telescopes are oriented towards the single target, and SAINT becomes an equivalent to a monolithic 1-meter telescope, with the field of view reduced to 11′ × 11′, and the exposure times decreased down to 0.6 ms (1684 frames per second). Different channels may then have different filters installed, thus allowing a detailed study—acquiring both color and polarization information—of a target object with the highest possible temporal resolution. The telescopes are located in two pavilions with sliding roofs and are controlled by a cluster of 25 computers that both govern their operation and acquire and store up to 800 terabytes of data every night, also performing its real-time processing using a dedicated fast image subtraction pipeline. Long-term storage of the data will require a petabyte class storage. The operation of SAINT will allow acquiring an unprecedented amount of data on various classes of astrophysical phenomena, from near-Earth to extragalactic ones, while its multi-channel design and the use of commercially available components allows easy expansion of its scale, and thus performance and detection capabilities.

Comparison of dual-trigger and human chorionic gonadotropin-only trigger among polycystic ovary syndrome couples who underwent controlled ovarian stimulation and intrauterine insemination: A retrospective cohort study.

The dual-trigger regime, consisting of gonadotrophin releasing hormone agonist and human chorionic gonadotropin (HCG), has been shown to offer advantage over the HCG-only trigger regime. However, little is known about the influence of dual-trigger or HCG-only trigger regime on the reproductive outcome of polycystic ovary syndrome (PCOS) couples undergoing controlled ovarian stimulation (COS) and intrauterine insemination (IUI). A total of 404 cycles of COS and IUI treatments from couples with PCOS were enrolled, and divided, according to the regime of trigger, into dual-trigger group (n = 109, 0.1-0.2 mg gonadotrophin releasing hormone agonist plus 6000 IU HCG) and HCG-only group (n = 295, 10,000 IU HCG or 250 μg recombinant HCG). Baseline characteristics of the 2 groups were comparable (all P > .05). In dual-trigger group, live birth rate, clinical pregnancy rate and β -HCG positive rate were all higher as compared to the HCG-only group (20.18% vs 18.98%, 25.69% vs 23.39% and 28.44% vs 25.08% respectively), despite the differences failed to achieve statistical significances (all P > .05). Moreover, early miscarriage rate and multiple pregnancy rate of the dual-trigger group were lower than those of the HCG-only group (17.86% vs 18.84% and 3.57% vs 7.25% respectively), although no statistical significances were found (all P > .05). Additionally, logistic regression analysis revealed that age contributed significantly to the live birth of couples with PCOS ( P = .043, OR = 0.900). Dual-trigger regime for oocyte maturation seems to associate with beneficial improvements in reproductive outcomes of PCOS couples undergoing COS and IUI. Instead of HCG-only trigger, dual-trigger regime might be an alternative option in COS and IUI cycles for couples with PCOS.

Detrital supply suppresses deforestation to maintain healthy kelp forest ecosystems.

Herbivores can reach extraordinary abundances in many ecosystems. When herbivore abundance is high, heavy grazing can severely defoliate primary producers and, in some cases, even drive ecosystem to undergo regime shifts from a high productivity state to a denuded, low productivity state. While the phenomenon of herbivore-driven regime shifts is well documented, we only partially understand the mechanisms underlying these events. Here, we combine herbivory experiments with 21 years of long-term monitoring data of kelp forest ecosystems to test the hypothesis that herbivores drive regime shifts when herbivory exceeds primary production. To test this hypothesis, we quantified how the foraging habits of an important group of marine herbivores-sea urchins-change with increases in sea urchin biomass and trigger regime shifts to a foundation species, giant kelp (Macrocystis pyrifera). Using experiments, we quantified how the grazing capacity of urchins increases as urchin biomass increases, then we combined these estimates of urchin grazing capacity with estimates of kelp production to predict when and where urchin grazing capacity exceeded kelp production. When grazing capacity exceeded kelp production, sea urchins caused a 50-fold reduction in giant kelp biomass. Our findings support the hypothesis that the balance between herbivory and production underlies herbivore-driven regime shifts in Southern California kelp forests and provides insight into when and where urchins are likely to force regime shifts in kelp forest ecosystems.

Study of the Stability of Triggering of a Controlled Multigap Spark Switch for Capacitive Energy Storage with Charging Voltage up to 100 kV and Energy Release Time on the Order of 100 ns

Results are presented of a study of the stability of triggering of a six-channel seven-gap spark switch intended for switching a capacitive energy storage with a charging voltage of up to 100 kV and energy release time on the order of 100 ns. The working medium of the spark switch is air at atmospheric pressure. In the controlled triggering regime, we measured the breakdown delay time of all of the discharge gaps relative to the arrival of the voltage trigger pulse and calculated the mean square deviation of the delay time (jitter) under variation of the charging voltage and growth rate of the voltage trigger pulse. Jitter less than 1 ns was obtained for a charging voltage of 90–100 kV and a growth rate of the voltage trigger pulse ~650 kV/μs. When the growth rate of the trigger pulse is decreased, the jitter of the spark switch grows significantly. Thus, for a charging voltage of 100 kV and a trigger voltage pulse with growth rate ~200 kV/μs the jitter exceeds 20 ns, and for a voltage trigger pulse with growth rate ~100 kV/μs the jitter exceeds 30 ns. To reduce the jitter when using trigger pulses with low growth rate, blade electrodes were inserted into the spark switch, ensuring ignition of a corona discharge in the gaps during charging of the capacitive storage. It has been shown that for a growth rate of the trigger pulse of 100–200 kV/μs the corona discharge reduces the jitter by 2–3 times.

Dynamics of Mesoscale Eddies Interacting With a Western Boundary Current Flowing by a Gap

AbstractThe propagation of cyclonic and anticyclonic mesoscale eddies through a wide meridional gap with a crossing western boundary current (WBC) is studied using a 1.5‐layer quasi‐geostrophic ocean circulation model. The results of the numerical experiments suggest that a steady, leaping WBC blocks nearly completely all eddies from propagating westward through the gap. In comparison, both cyclonic and anticyclonic eddies propagate westward nearly uninterrupted through the gap if the WBC is in a penetrating state. Interactions of mesoscale eddies with a critical‐state WBC trigger regime transitions of the WBC between leaping and penetrating states, resulting in dramatic changes of the circulation west of the gap. The radiation of the circulation plumes from the gap into the western basin due to the WBC regime transition is found to be independent of the size and the initial location of the perturbing eddy in the eastern basin, provided that the WBC path shift is induced successfully by the eddy.

On the Stochastic Sensitivity and Noise-Induced Transitions of a Kaldor-Type Business Cycle Model

In the paper, we consider a Kaldor-type model of the business cycle with external additive and internal parametric disturbances. We study analytically and numerically the probability properties of stochastically forced equilibria and limit cycles via stochastic sensitivity function technique. In particular, we discuss the effects of additive and parametric noises on the economic variables and we detect some stochastic bifurcations such as a P-bifurcation, i.e a phenomenon of noise-induced transition from monostability to bistability. This stochastic bistability causes a new trigger regime in economic dynamics.

Transformative Environmental Governance

Transformative governance is an approach to environmental governance that has the capacity to respond to, manage, and trigger regime shifts in coupled social-ecological systems (SESs) at multiple scales. The goal of transformative governance is to actively shift degraded SESs to alternative, more desirable, or more functional regimes by altering the structures and processes that define the system. Transformative governance is rooted in ecological theories to explain cross-scale dynamics in complex systems, as well as social theories of change, innovation, and technological transformation. Similar to adaptive governance, transformative governance involves a broad set of governance components, but requires additional capacity to foster new social-ecological regimes including increased risk tolerance, significant systemic investment, and restructured economies and power relations. Transformative governance has the potential to actively respond to regime shifts triggered by climate change, and thus future research should focus on identifying system drivers and leading indicators associated with social-ecological thresholds.

Triggering regime change: A comparative analysis of the performance of innovation platforms that attempted to change the institutional context for nine agricultural domains in West Africa

The article synthesises the experiences of innovation platforms (IPs) that engaged in open-ended experimental action to improve the institutional context for smallholder farm development in West Africa. The IPs sought change at the level of the institutional regime covering an entire agricultural domain (such as cocoa, cotton, oil palm or water management). Their purpose was therefore not to ‘roll out’ farm-level technologies across rural communities. The IPs's outcomes were documented and analysed throughout by means of theory-based process tracing in each of seven of the nine domains in which regime change was attempted. The evidence shows that by means of exploratory scoping and diagnosis, socio-technical and institutional experimentation, and guided facilitation IPs can remove, by-pass, or modify domain-specific institutional constraints and/or create new institutional conditions that allow smallholders to capture opportunity. The article describes the 5-year, €4.5 million research programme in Benin, Ghana and Mali, covering theory, design, methods and results. It is the sequel to Hounkonnou et al. in AGSY 108 (2012): 74–83.

Nano-optical observation of cascade switching in a parallel superconducting nanowire single photon detector

The device physics of parallel-wire superconducting nanowire single photon detectors is based on a cascade process. Using nano-optical techniques and a parallel wire device with spatially separate pixels, we explicitly demonstrate the single- and multi-photon triggering regimes. We develop a model for describing efficiency of a detector operating in the arm-trigger regime. We investigate the timing response of the detector when illuminating a single pixel and two pixels. We see a change in the active area of the detector between the two regimes and find the two-pixel trigger regime to have a faster timing response than the one-pixel regime.

Models of active Brownian motors based on internal oscillations

We analyze the dynamics of driven translations or rotations based on models with internal oscillations. In particular we discuss several new mechanisms of motors driven by chemical energy. First we study the simple depot model and give analytical solutions including efficiency and stochastic effects. Then we introduce internal oscillations based on inertia including variable friction functions. Further we replace inertia by delay effects and study motors in trigger regime. As possible applications we consider a model of ATP-driven motors operating on angle and elasticity variables. We develop a model of F1-ATPase motors with three β-subunits which drive the rotation of the central γ-shaft.

Trigger regime of the functioning of the synaptic channel

It has been shown using the linear model describing the dynamics of biochemical reactions occurring in a synapse that, as periodic step-like impulses pass through a synaptic channel, it operates in the triggering regime. The transmission of an impulse through the channel is associated with the change of the stationary point of the corresponding dynamic system compared with the unexcited state of the synapse. As a result, the system periodically evolves between two stable stationary states.

Optical and gamma superradiance

Experiments on the observation of optical superradiance in a LaF3:Pr3+ crystal are described. The multipulse regime of excitation of optical superradiance in both two- and multilevel systems is theoretically investigated. It is demonstrated that this regime is the generalization of the triggering regime of superradiance excitation. The developed formalism is used for the description of gamma superradiance.

Epigenes: design and construction of new hereditary units

A plasmid digene construction designed before [Tchuraev, R.N. (1982) J. Gen. Biol. 43, 79–87] has been realised, including feedback by repressing proteins with given trigger regime of gene functioning. Experimental tests of the expected epigene properties of the obtained pECPI recombinant plasmid involving lacI and cI 857 regulatory genes have shown a phenomenon of steady inheritance of two alternative epigenotypes lacI 1cI 0 and lacI 0cI 1 , as well as an external toggle switch through metabolitic and temperature signals from one inherited functional state of the cyclic digene system into another. Thus, we have constructed a hereditary unit of a specific kind, namely, a two-component stationary epigene with preset properties.

Triggering regime of oil-filled trigatron dischargers

A comparative analysis made in [1, 2] of different types of regulable high-voltage dischargers with liquid insulation showed that trigatrons are currently the most promising for use in high-voltage pulse-operated devices due to their simplicity and reliability. Two basic mechanisms of discharge initiation can be realized in trigatrons — initiation by intensification of the field in the region of the control electrode [2, 3], and triggering by a spark in the ignition gap [4, 5]. The first type of trigatron has been studied sufficiently only for short voltage periods [3, 6, 7], so it is used mainly in switching the pulse-shaping lines of powerful nanosecond pulse generators with “rapid” (0.5–1.5 μsec) charging [8, 9]. Almost no use is now made of the second type of trigatron switch in high-voltage pulse technology due to its unsatisfactory time characteristics. Here we report results of a study of the time characteristics of both types of oil-filled trigatrons operating in a regime whereby they form the leading edge of rectangular voltage pulses with amplitudes up to 800 kV and durations of 1–100 μsec. The goal is to find the optimum conditions for triggering of trigatron dischargers with liquid insulation in the region of microsecond voltage discharges. Experiments were conducted on the unit in [10]. The test discharger was placed in a cylindrical chamber 45 cm in diameter and 27 cm in length. The high-voltage electrode of the discharger was in the form of a cylinder 20 cm in diameter positioned coaxially inside the chamber. The 10-mm-diameter ground electrode was positioned radially in a branch pipe 8 cm long. The control electrode was placed in a 2-cm-diameter hole in the center of the ground electrode. The chamber with the test discharge was filled with transformer oil with a breakdown voltage of about 50 kV. The oil was not replaced or cleaned during the experiment. We did not find that contamination of the oil by discharge products had any effect on the time characteristics of either type of discharger. The results were analyzed by the least squares method, with 50 measurements to a point (it was found that time lag of the discharger triggering conforms approximately to a normal distribution law for both types of discharger).