Chaotic Escape From an Open Vase-Shaped Cavity. II. Topological Theory

We present part II of a study of chaotic escape from an open two-dimensional vase-shaped cavity. A surface of section reveals that the chaotic dynamics is controlled by a homoclinic tangle, the union of stable and unstable manifolds attached to a hyperbolic fixed point. Furthermore, the surface of section rectifies escape-time graphs into sequences of escape segments; each sequence is called an epistrophe. Some of the escape segments (and therefore some of the epistrophes) are forced by the topology of the dynamics of the homoclinic tangle. These topologically forced structures can be predicted using the method called homotopic lobe dynamics (HLD). HLD takes a finite length of the unstable manifold and a judiciously altered topology and returns a set of symbolic dynamical equations that encode the folding and stretching of the unstable manifold. We present three applications of this method to three different lengths of the unstable manifold. Using each set of dynamical equations, we compute minimal sets of escape segments associated with the unstable manifold, and minimal sets associated with a burst of trajectories emanating from a point on the vase\u27s boundary. The topological theory predicts most of the early escape segments that are found in numerical computations

Magnetic Properties of Textured Nanocrystalline Mn-Zn Ferrite Thin Films Fabricated by Pulsed Laser Deposition.

MnxZn1-xFe2O4 nanoparticles were chemically synthesized by co- precipitating metal ions in alkaline aqueous solutions. The XRD peaks match up to spinel ferrites without any multi phase indication and clear visibility of ferrite FT-IR absorption bands confirm single phase spinal formation. Particle size derived from XRD data is authenticated by TEM micrographs. Thin films fabricated from this material on quartz substrate by pulse laser deposition were characterised using XRD. The XRD data revealed formation of spinel structure with a reasonable degree of texture. AFM analysis confirms nano granular film morphology with dimensions comparable to that of target grain. Magnetic data obtained from textured nanocrystalline Mn-Zn ferrite thin film measurements made known enhanced coercivity. The observed enhanced coercivity is explained with due consideration of film texture and surface disorder that originated from Mn concentration specific initial adsorption prior to nucleation, resulting in directional film growth

Chaotic Escape from an Open Vase-shaped Cavity. I. Numerical and Experimental Results

We present part I in a two-part study of an open chaotic cavity shaped as a vase. The vase possesses an unstable periodic orbit in its neck. Trajectories passing through this orbit escape without return. For our analysis, we consider a family of trajectories launched from a point on the vase boundary. We imagine a vertical array of detectors past the unstable periodic orbit and, for each escaping trajectory, record the propagation time and the vertical detector position. We find that the escape time exhibits a complicated recursive structure. This recursive structure is explored in part I of our study. We present an approximation to the Helmholtz equation for waves escaping the vase. By choosing a set of detector points, we interpolate trajectories connecting the source to the different detector points. We use these interpolated classical trajectories to construct the solution to the wave equation at a detector point. Finally, we construct a plot of the detector position versus the escape time and compare this graph to the results of an experiment using classical ultrasound waves. We find that generally the classical trajectories organize the escaping ultrasound waves

Adaptation of counters redundant bits with the provision of dual supply and modified clock gating to favour of low power in VLSI

750-757The utilization of usual supply voltage and clock for repetitive state transistors in digital circuits is a fundamental driver for high power utilization. Most significant bit states of the counter stay longer than the least significant bit states and it has some repetitive states. To limit the supply voltage and stop the clock for MSB Flip Flop (FF) transistor, our method uses Control Combinational Logic, Voltage selector and Modified Integrated Clock Gating blocks. The LSB transistor always have a supply voltage of 1.2V and succession of the clock, while MSB transistor gets just 480mV and the clock will be stopped by the this technique. Bring down the supply voltage and quit the clock for redundant states either 0 or 1 in MSB. Meantime supply 1.2V and clock for state changes over from one state to next state. The experimental simulation was done in 45nm CMOS technology using Cadence virtuoso indicates that this asynchronous counter achieves a power savings of 23.57% and the same modified technique when applied to the counters with transmission-gate FF, hybrid-latch FF and sense amplifier FF will have more than 40% power savings and the technique applied in some benchmark circuits will have more than 22% power savings than existing techniques

Adaptation of counters redundant bits with the provision of dual supply and modified clock gating to favour of low power in VLS

The utilization of usual supply voltage and clock for repetitive state transistors in digital circuits is a fundamental driver for high power utilization. Most significant bit states of the counter stay longer than the least significant bit states and it has some repetitive states. To limit the supply voltage and stop the clock for MSB Flip Flop (FF) transistor, our method uses Control Combinational Logic, Voltage selector and Modified Integrated Clock Gating blocks. The LSB transistor always have a supply voltage of 1.2V and succession of the clock, while MSB transistor gets just 480mV and the clock will be stopped by the this technique. Bring down the supply voltage and quit the clock for redundant states either 0 or 1 in MSB. Meantime supply 1.2V and clock for state changes over from one state to next state. The experimental simulation was done in 45nm CMOS technology using Cadence virtuoso indicates that this asynchronous counter achieves a power savings of 23.57% and the same modified technique when applied to the counters with transmission-gate FF, hybrid-latch FF and sense amplifier FF will have more than 40% power savings and the technique applied in some benchmark circuits will have more than 22% power savings than existing techniques

Eddy properties in the California Current System

Eddy detection and tracking algorithms are applied to both satellite altimetry and a high‐resolution (dx = 5 km) climatological model solution of the U.S. West Coast to study the properties of surface and undercurrent eddies in the California Current System. Eddy properties show remarkable similarity in space and time, and even somewhat in polarity. Summer and fall are the most active seasons for undercurrent eddy generation, while there is less seasonal variation at surface. Most of the eddies have radii in the range of 25–100 km, sea level anomaly amplitudes of 1–4 cm, and vorticity normalized by ƒ amplitudes of 0.025–0.2. Many of the eddies formed near the coast travel considerable distance westward with speeds about 2 km/day, consistent with the β effect. Anticyclones and cyclones show equatorward and poleward displacements, respectively. Long‐lived surface eddies show a cyclonic dominance. The subsurface California Undercurrent generates more long‐lived anticyclones than cyclones through instabilities and topographic/coastline effects. In contrast, surface eddies and subsurface cyclones have much more widely distributed birth sites. The majority of the identified eddies have lifetimes less than a season. Eddies extend to 800–1500 m depth and have distinctive vertical structures for cyclones and anticyclones. Eddies show high nonlinearity (rotation speed higher than propagation speed) and hence can be efficient in transporting materials offshore

SST–Wind Interaction in Coastal Upwelling: Oceanic Simulation with Empirical Coupling

Observations, primarily from satellites, have shown a statistical relationship between the surface wind stress and underlying sea surface temperature (SST) on intermediate space and time scales, in many regions inclusive of eastern boundary upwelling current systems. In this paper, this empirical SST–wind stress relationship is utilized to provide a simple representation of mesoscale air–sea coupling for an oceanic model forced by surface winds, namely, the Regional Oceanic Modeling System (ROMS). This model formulation is applied to an idealized upwelling problem with prevailing equatorward winds to determine the coupling consequences on flow, SST, stratification, and wind evolutions. The initially uniform wind field adjusts through coupling to a cross-shore profile with weaker nearshore winds, similar to realistic ones. The modified wind stress weakens the nearshore upwelling circulation and increases SST in the coastal zone. The SST-induced wind stress curl strengthens offshore upwelling through Ekman suction. The total curl-driven upwelling exceeds the coastal upwelling. The SST-induced changes in the nearshore wind stress field also strengthen and broaden the poleward undercurrent. The coupling also shows significant impact on the developing mesoscale eddies by damaging cyclonic eddies more than anticyclonic eddies, which leads to dominance by the latter. Dynamically, this is a consequence of cyclones with stronger SST gradients that induce stronger wind perturbations in this particular upwelling problem and that are therefore generally more susceptible to disruption than anticyclones at finite Rossby number. The net effect is a weakening of eddy kinetic energy

Insight on current advances in food science and technology for feeding the world population

While the world population is steadily increasing, the capacity of Earth to renew its resources is continuously declining. Consequently, the bioresources required for food production are diminishing and new approaches are needed to feed the current and future global population. In the last decades, scientists have developed novel strategies to reduce food loss and waste, improve food production, and find new ingredients, design and build new food structures, and introduce digitalization in the food system. In this work, we provide a general overview on circular economy, alternative technologies for food production such as cellular agriculture, and new sources of ingredients like microalgae, insects, and wood-derived fibers. We present a summary of the whole process of food design using creative problem-solving that fosters food innovation, and digitalization in the food sector such as artificial intelligence, augmented and virtual reality, and blockchain technology. Finally, we briefly discuss the effect of COVID-19 on the food system. This review has been written for a broad audience, covering a wide spectrum and giving insights on the most recent advances in the food science and technology area, presenting examples from both academic and industrial sides, in terms of concepts, technologies, and tools which will possibly help the world to achieve food security in the next 30 years.Peer reviewe

Activation of JNK Signaling Mediates Amyloid-ß-Dependent Cell Death

Alzheimer's disease (AD) is an age related progressive neurodegenerative disorder. One of the reasons for Alzheimer's neuropathology is the generation of large aggregates of Aß42 that are toxic in nature and induce oxidative stress, aberrant signaling and many other cellular alterations that trigger neuronal cell death. However, the exact mechanisms leading to cell death are not clearly understood.We employed a Drosophila eye model of AD to study how Aß42 causes cell death. Misexpression of higher levels of Aß42 in the differentiating photoreceptors of fly retina rapidly induced aberrant cellular phenotypes and cell death. We found that blocking caspase-dependent cell death initially blocked cell death but did not lead to a significant rescue in the adult eye. However, blocking the levels of c-Jun NH(2)-terminal kinase (JNK) signaling pathway significantly rescued the neurodegeneration phenotype of Aß42 misexpression both in eye imaginal disc as well as the adult eye. Misexpression of Aß42 induced transcriptional upregulation of puckered (puc), a downstream target and functional read out of JNK signaling. Moreover, a three-fold increase in phospho-Jun (activated Jun) protein levels was seen in Aß42 retina as compared to the wild-type retina. When we blocked both caspases and JNK signaling simultaneously in the fly retina, the rescue of the neurodegenerative phenotype is comparable to that caused by blocking JNK signaling pathway alone.Our data suggests that (i) accumulation of Aß42 plaques induces JNK signaling in neurons and (ii) induction of JNK contributes to Aß42 mediated cell death. Therefore, inappropriate JNK activation may indeed be relevant to the AD neuropathology, thus making JNK a key target for AD therapies