Growth Collapse Research Articles

Molding the acoustic cavity–analyzing the influence of toroidal vortex development on acoustic multi-bubble macrostructures under different ultrasonic horn tip diameters

The acoustic cavity structure typically experiences a sequence of transfigurations during its sinusoidal growth–collapse cycle. However, upon examining the cavity structure in aqueous bodies, it appears that the growth structure attained falls between two geometrical structures, namely, mushroom-like structure (MBS) and cone-like bubble structure (CBS), based on the actuated ultrasonic horn tip diameter. With the recurring observations of the emergence of proximal toroidal vortices, the present investigation conducts a numerical analysis exploring the vortex development under 3, 6, 13, 16, and 19 mm horn tips to establish a potential correlation between the vortex and the cavity structure. The study presents a computational fluid dynamic investigation to capture the nature of the vortex evolution, in terms of size and position, and its respective cavitation development. The first indicator of potential correlation was the equivalency of the vortex expansion–contraction frequency and the cavity's sub-harmonic frequency. It has been found that the cavity structure is molded into MBS by the presence of a symmetric locomotive vortex structure that extends up to 1.5 times the horn tip diameter. Meanwhile, CBS is observed to take shape in the presence of an eccentric locomotive vortex that attains a size within 0.2–0.6 times the horn tip diameter. The significance of the vortex size and position is also observed in the cavity's collapse, as the vortex appears to govern the ability of the cavity impinging jet to initialize the collapse phase.

Abrupt height growth setbacks show overbrowsing of tree saplings, which can be reduced by raising deer harvest

Intensive ungulate browsing significantly impacts forests worldwide. However, it is usually not single browsing events that lead to sapling mortality, but the little-researched interactions of browsed saplings with their biotic and abiotic environment. (I) Our objective was to assess the impact of ungulate browsing on the growth of young saplings relative to other environmental factors by utilizing their height increment as a sensitive measure of vitality to indicate their status. (II) Furthermore, we aimed to identify factors affecting ungulate browsing at our study sites, assessed as browsing probabilities, and identify effective mitigation measures for browsing impact. We analyzed an extensive sapling dataset of 248 wildlife exclosures, which were erected in 2016 in beech dominated forests across Germany and assessed annually until 2020. (I) Browsing probability and light availability were the most influential parameters for selectively browsed, admixed tree species (e.g., sycamore maple). Height increment showed abrupt setbacks, which caused a permanent collapse of growth when browsing exceeded a certain level. However, light availability enhanced height increment. (II) An increase in deer harvest reduced the browsing probability of selectively browsed species considerably. We conclude that the growth-inhibiting effect of ungulate browsing is a multifactorial phenomenon, which can be mitigated by silvicultural management and efficient hunting strategies.

Coupled relationships between overburden stress and ultra-deep sandstone brittle deformation properties based on in situ CT scanning

For low poroisty (tight) sandstone of the Cretaceous Bashijiqike Formation, Kuqa Depression foreland thrust belt (Tarim Basin), samples from an ultra-deep setting (ca.7–8 km depth) and from outcrop locations were collected to analyze and compare brittle deformation in triaxial tests to infer mechanical behavior. Core samples sustained protracted burial whereas outcrop samples were deeply buried then experienced late uplift and exposure. Fracture-pore changes during loading in situ uniaxial compression documented with 3D X-ray imaging show that loading results in extensive development of fractures and enhanced pore connectivity that elevates permeability from 1mD to 10mD through local tensile fracture zones and high-permeability layers. The collapse of 60% pores and 70% reduction of connected pores may lead to locally compacted low-permeability zones. These characteristics are also reflected in the high heterogeneity of ultra-deep reservoir properties—the alternating development of dense and sparse zones of fractures. Research lead to the inference that under burial and tectonic loading conditions sandstones experience concurrent collapse of pores and growth of fractures, and reservoir structure changes from pore-dominated to fracture-dominated. Under deep conditions, the reservoir rock is subjected to plastic-brittle strain, increasing porosity and permeability followed by, under ultra-deep conditions, porosity decreasing markedly and permeability increasing significantly.

CMOS-compatible electro-optical SRAM cavity device based on negative differential resistance

The impending collapse of Moore-like growth of computational power has spurred the development of alternative computing architectures, such as optical or electro-optical computing. However, many of the current demonstrations in literature are not compatible with the dominant complementary metal-oxide semiconductor (CMOS) technology used in large-scale manufacturing today. Here, inspired by the famous Esaki diode demonstrating negative differential resistance (NDR), we show a fully CMOS-compatible electro-optical memory device, based on a new type of NDR diode. This new diode is based on a horizontal PN junction in silicon with a unique layout providing the NDR feature, and we show how it can easily be implemented into a photonic micro-ring resonator to enable a bistable device with a fully optical readout in the telecom regime. Our result is an important stepping stone on the way to new nonlinear electro-optic and neuromorphic computing structures based on this new NDR diode.

Characteristics of cavitation evolution through a butterfly valve under transient regulation

As the key control equipment for the transmission of the fluid medium, butterfly valves are widely used in transmission systems of media in the energy, chemical industry, metallurgy, aerospace engineering, and other fields, playing an important role in the stability and reliability of system operation. When the flow cross section suddenly changes, the pressure rapidly decreases the downstream, leading to cavitation in butterfly valves. Cavitation causes serious erosion and damage in the valve core and pipeline surface, resulting in leakage and noise problems in butterfly valves, which seriously affects the regulation performance and lifetime of butterfly valves. In this study, numerical analyses are conducted to investigate cavitation evolution at the transient regulation of a butterfly plate through a butterfly valve model. Moreover, the effects of the valve opening degree and rotating speed on the cavitation volume and distribution, rate of cavitation volume change, growth–collapse rate of cavitation, and correlation between cavitation and vortex in the opening and closing processes of butterfly valves are investigated. Due to the influence of transient regulation and flow hysteresis, the characteristic parameters and evolution of cavitation exhibit different behaviors in the opening and closing processes of butterfly valves.

What Turns a Blessing into a Curse? The Political Economy of Natural Resource Wealth (Invited Lecture)

I review the relationship between natural resource endowment type and economic growth in developing countries. Certain types of natural resources, such as oil and minerals, tend to exhibit concentrated production and revenue patterns, while revenue flows from other resources such as agriculture are more diffuse. Most developing countries that export products from the first group have been prone to growth failure in recent times. The most important channels are political economy mechanisms, where there are negative relationships between natural resource rents and institutional development. An explicit model of growth collapse with micro-foundations in rent-seeking contests that have increasing returns in rent-seeking outlays is presented.

The limits of metabolic heredity in protocells.

The universal core of metabolism could have emerged from thermodynamically favoured prebiotic pathways at the origin of life. Starting with H2 and CO2, the synthesis of amino acids and mixed fatty acids, which self-assemble into protocells, is favoured under warm anoxic conditions. Here, we address whether it is possible for protocells to evolve greater metabolic complexity, through positive feedbacks involving nucleotide catalysis. Using mathematical simulations to model metabolic heredity in protocells, based on branch points in protometabolic flux, we show that nucleotide catalysis can indeed promote protocell growth. This outcome only occurs when nucleotides directly catalyse CO2 fixation. Strong nucleotide catalysis of other pathways (e.g. fatty acids and amino acids) generally unbalances metabolism and slows down protocell growth, and when there is competition between catalytic functions cell growth collapses. Autocatalysis of nucleotide synthesis can promote growth but only if nucleotides also catalyse CO2 fixation; autocatalysis alone leads to the accumulation of nucleotides at the expense of CO2 fixation and protocell growth rate. Our findings offer a new framework for the emergence of greater metabolic complexity, in which nucleotides catalyse broad-spectrum processes such as CO2 fixation, hydrogenation and phosphorylation important to the emergence of genetic heredity at the origin of life.

Regulating desolvation and homogenized ion flux towards highly reversible dendrite-free zinc anode

Aqueous zinc ion batteries (AZIBs) are potential in the energy storage field, however, there are inherent disadvantages that seriously hinder their development, including the dissolution and structural collapse of cathode materials, Zn-dendrite growth, and side reactions at the anode interface. The cycling life and coulombic efficiency suffer from the latter two disadvantages, thus, many artificial interface layers have been prepared to address these issues. Herein, an organic molecule with four thiophene substitution groups, 1,3,5,9-Tetrathiophenylpyrene (TTP), was designed as an artificial layer to suppress dendrites and achieve uniform zinc deposition. This strategy prolonged the lifespan of symmetrical cells with an extremely small polarization voltage of 51 mV at 0.885 mA cm−2. In particular, the strong interaction between TTP and Zn atoms not only promoted the Zn desolvation but also modulated the Zn2+ transport. Ultimately, Zn-dendrite, hydrogen evolution reaction (HER), and side reactions were significantly inhibited. The full cells constructed with V2O5 delivered long-term cycling stability over 6500 cycles with a capacity retention of 80 % after 1250 cycles at 5 A g-1 and excellent rate performance. More importantly, the sulfur-containing functional groups in the organic materials were successfully utilized to resolve the issues of Zn anodes, demonstrating the promising prospects of this strategy.

Matrix calculations for moments of Markov processes

AbstractMatryoshka dolls, the traditional Russian nesting figurines, are known worldwide for each doll’s encapsulation of a sequence of smaller dolls. In this paper, we exploit the structure of a new sequence of nested matrices we callmatryoshkan matricesin order to compute the moments of the one-dimensional polynomial processes, a large class of Markov processes. We characterize the salient properties of matryoshkan matrices that allow us to compute these moments in closed form at a specific time without computing the entire path of the process. This simplifies the computation of the polynomial process moments significantly. Through our method, we derive explicit expressions for both transient and steady-state moments of this class of Markov processes. We demonstrate the applicability of this method through explicit examples such as shot noise processes, growth–collapse processes, ephemerally self-exciting processes, and affine stochastic differential equations from the finance literature. We also show that we can derive explicit expressions for the self-exciting Hawkes process, for which finding closed-form moment expressions has been an open problem since their introduction in 1971. In general, our techniques can be used for any Markov process for which the infinitesimal generator of an arbitrary polynomial is itself a polynomial of equal or lower order.

Unified approach for solving exit problems for additive-increase and multiplicative-decrease processes

AbstractWe analyse an additive-increase and multiplicative-decrease (also known as growth–collapse) process that grows linearly in time and that, at Poisson epochs, experiences downward jumps that are (deterministically) proportional to its present position. For this process, and also for its reflected versions, we consider one- and two-sided exit problems that concern the identification of the laws of exit times from fixed intervals and half-lines. All proofs are based on a unified first-step analysis approach at the first jump epoch, which allows us to give explicit, yet involved, formulas for their Laplace transforms. All eight Laplace transforms can be described in terms of two so-called scale functions associated with the upward one-sided exit time and with the upward two-sided exit time. All other Laplace transforms can be obtained from the above scale functions by taking limits, derivatives, integrals, and combinations of these.

Moments of Markovian growth–collapse processes

AbstractWe apply general moment identities for Poisson stochastic integrals with random integrands to the computation of the moments of Markovian growth–collapse processes. This extends existing formulas for mean and variance available in the literature to closed-form moment expressions of all orders. In comparison with other methods based on differential equations, our approach yields explicit summations in terms of the time parameter. We also treat the case of the associated embedded chain, and provide recursive codes in Maple and Mathematica for the computation of moments and cumulants of any order with arbitrary cut-off moment sequences and jump size functions.

The anatomy of the corona crisis through the lens of the labor market adjustment

The paper analyzes the main changes in the Russian labor market during the economic crisis caused by the COVID-19 pandemic. In previous crisis episodes, the Russian labor market reacted to downturns in a non-standard way — not so much by employment decline and unemployment surge as by wage cuts and reduction in working hours. The discussion focuses on the question whether this algorithm has been preserved under conditions of the corona crisis. The empirical basis is provided by microdata from the Russian Longitudinal Monitoring Survey (RLMS—HSE) for 2020. The paper describes the main mechanisms of labor market adjustment (wage cuts, part-time transfers, involuntary furloughs, telecommuting and others), analyzes the scale and dynamics of their use, assesses their differentiation by sociodemographic groups and types of enterprises. For each form of crisis adjustment both descriptive and econometric analysis is carried out. The Russian experience is compared with reaction to the corona crisis by other labor markets. It is shown that, like other countries, Russia managed to avoid a collapse of employment and explosive growth in unemployment mainly due to active utilization of two key instruments — various types of part-time employment and telecommuting. This allows us to conclude that the specific “Russian” labor market model has once again confirmed its ability to effectively accommodate even the strongest economic shocks.

Minimal volume entropy of free-by-cyclic groups and 2-dimensional right-angled Artin groups

Let G be a free-by-cyclic group or a 2-dimensional right-angled Artin group. We provide an algebraic and a geometric characterization for when each aspherical simplicial complex with fundamental group isomorphic to G has minimal volume entropy equal to 0. In the nonvanishing case, we provide a positive lower bound to the minimal volume entropy of an aspherical simplicial complex of minimal dimension for these two classes of groups. Our results rely upon a criterion for the vanishing of the minimal volume entropy for 2-dimensional groups with uniform uniform exponential growth. This criterion is shown by analyzing the fiber \(\pi _1\)-growth collapse and non-collapsing assumptions of Babenko–Sabourau (Minimal volume entropy and fiber growth, arXiv:2102.04551, 2020).

Investigating the Impact of COVID-19 Outbreak On Canada’S Government Treasury Bills

SARS-Cov-2 was first recorded in Wuhan, a town in the Hubei Province of China with a population of 11 million in December 2019, following a clear-cut outbreak of non-pneumonia. More than 200 countries and territories have now spread the virus around the globe, and the World Health Organization (WHO) identified it as a pandemic on 11 March 2020. On the economic front, COVID-19 contributed to a partial or absolute lockout in more than 200 nations.This has undermined the global supply chain and has contributed to a major decline in both economic growth and the values of financial assets. Canada is one of the countries afflicted by the outbreak with 731 000 cases and 18 622 deaths as of 21 January 2020. Vaccines have recently been created, but the surge of infection continues to escalate every day. On the socio-economic front, COVID-19 led more than 200 countries to a partial or absolute lockdown, interrupted global supply chains and led to a collapse in both economic growth and financial asset prices.The impact of COVID-19 is unclear because the public health crisis is still unfolding. There is limited amount of studies concerning this topic, because the crisis is still unfolding. The objective of this study is to investigate the impact of COVID-19 on Canada’s Treasury Bills. The author uses extreme bound analysis for market interpretation and sourced data from Bank of Canada and Our World in Data COVID-19, from January 1 to December 31 2020. The result of the study show that, Stringency Index have an impact on Canada’s 6-month Treasury bill auction average yield (V80691304) because of the robust relationship between them. Furthermore, 3 months Treasury bill auction average yields (V80691303) has positive correlation with 6months Treasury bill auction average yields (V80691304), 1-year Treasury bills auction average yields (V80691305), 3 months Treasury bills (V80691344), 6 months Treasury bills (V80691345), 1 year Treasury bills (V80691346) and a negative correlation with Government Stringency index (SI). Furthermore, 6months Treasury bill auction average yields (V80691304) has positive correlation with 3 months Treasury bill auction average yields (V80691303), 1-year Treasury bills auction average yields (V80691305), 1 month Treasury bills (V80691342), 3 months Treasury bills (V80691344), 6 months Treasury bills (V80691345), 1 year Treasury bills (V80691346) and a negative correlation with Government Stringency index (SI). Again, 1-year Treasury bills auction average yields (V80691305) has positive correlation with 3 months Treasury bill auction average yields (V80691303), 6months Treasury bill auction average yields (V80691304), 1 month Treasury bills (V80691342), 3 months Treasury bills (V80691344), 6 months Treasury bills (V80691345), 1 year Treasury bills (V80691346) and a negative correlation with Government Stringency index (SI).

Pōniuā‘ena: A Luminous z = 7.5 Quasar Hosting a 1.5 Billion Solar Mass Black Hole

Abstract We report the discovery of a luminous quasar, J1007+2115 at z = 7.515 (“Pōniuā‘ena”), from our wide-field reionization-era quasar survey. J1007+2115 is the second quasar now known at z > 7.5, deep into the reionization epoch. The quasar is powered by a (1.5 ± 0.2) × 109 M ⊙ supermassive black hole (SMBH), based on its broad Mg ii emission-line profile from Gemini and Keck near-IR spectroscopy. The SMBH in J1007+2115 is twice as massive as that in quasar J1342+0928 at z = 7.54, the current quasar redshift record holder. The existence of such a massive SMBH just 700 million years after the Big Bang significantly challenges models of the earliest SMBH growth. Model assumptions of Eddington-limited accretion and a radiative efficiency of 0.1 require a seed black hole of ≳104 M ⊙ at z = 30. This requirement suggests either a massive black hole seed as a result of direct collapse or earlier periods of rapid black hole growth with hyper-Eddington accretion and/or a low radiative efficiency. We measure the damping wing signature imprinted by neutral hydrogen absorption in the intergalactic medium (IGM) on J1007+2115's Lyα line profile, and find that it is weaker than that of J1342+0928 and two other z ≳ 7 quasars. We estimate an IGM volume-averaged neutral fraction . This range of values suggests a patchy reionization history toward different IGM sightlines. We detect the 158 μm [C ii] emission line in J1007+2115 with the Atacama Large Millimeter/submillimeter Array; this line centroid yields a systemic redshift of z = 7.5149 ± 0.0004 and indicates a star formation rate of ∼210 M ☉ yr−1 in its host galaxy.

Synergistic action of indole acetic acid with homobrassinolide in easing the NaCl-induced toxicity in Solanum melongena L. seedlings

In the current work, the influence of indole-3-acetic acid (IAA; 10–5 M) and 28-homobrassinolide (HBL; 10–8 M) alone or in combination was explored in Solanum melongena L. seedlings treated with sodium chloride (NaCl). The NaCl at different concentrations (5 mM and 15 mM) reduced growth attributes, photosynthetic pigments as well as photosynthesis, and enhanced the dark respiratory rate, and these effects were accompanied with Na+ and reactive oxygen species (ROS) accumulation in leaf tissues. Moreover, NaCl reduced the proficiency of PS II with the increasing doses of selected stress which is apparent from the declined values of Fv/Fm (Phi_P0), Ѱ0 (Psi_0), ϕE0 (Phi_E0) and PIABS, and augmented values of energy fluxes: ABS/RC, ET0/RC, TR0/RC and DI0/RC. The NaCl treatment caused substantial reduction in nitrate and nitrite contents, activities of nitrate reductase, nitrite reductase, glutamine synthetase and glutamate synthase, and increased ammonium content and glutamate dehydrogenase activity. Enhanced level of ROS, i.e. superoxide radical (O2•−) and hydrogen peroxide (H2O2) under NaCl stress amplified the lipid peroxidation product malondialdehyde (MDA), in spite of considerable upsurge in performance of superoxide dismutase, peroxidase, catalase, glutathione-S-transferase enzymes and amount of non-protein thiol, cysteine and proline. Exogenous supplementation of IAA and HBL considerably assuaged the NaCl-induced collapse in growth attributes by manipulating the structural and functional features of photosynthetic apparatus. The ameliorating effect of IAA and HBL, in combination, was due to (1) substantial decrease in Na+ accumulation, (2) improvement in PS II efficiency and nitrogen metabolism and (3) reduced oxidative damage in S. melongena L. due to stimulatory response of antioxidants that keeps the level of oxidants under limit in the seedlings. Thus, the overall results campaigned that IAA and HBL act synergistically to overcome the toxic effects that NaCl had on S. melongena L. seedlings.

Seeding Public Goods Is Essential for Maintaining Cooperation in Pseudomonas aeruginosa.

Quorum sensing in Pseudomonas aeruginosa controls the production of costly public goods such as exoproteases. This cooperative behavior is susceptible to social cheating by mutants that do not invest in the exoprotease production but assimilate the amino acids and peptides derived by the hydrolysis of proteins in the extracellular media. In sequential cultures with protein as the sole carbon source, these social cheaters are readily selected and often reach equilibrium with the exoprotease producers. Nevertheless, an excess of cheaters causes the collapse of population growth. In this work, using the reference strain PA14 and a clinical isolate from a burn patient, we demonstrate that the initial amount of public goods (exoprotease) that comes with the inoculum in each sequential culture is essential for maintaining population growth and that eliminating the exoprotease in the inoculum leads to rapid population collapse. Therefore, our results suggest that sequential washes should be combined with public good inhibitors to more effectively combat P. aeruginosa infections.

Quantitative Identification of Middle-Income Trap

In this research, the growth collapse experienced by 119 economic entities in the world from 1950 to 2010 is quantitatively analyzed. And the objective existence of the middle-income trap is proved from a statistical perspective. On this basis, the existing identification methods of middle-income trap are evaluated and revised. In addition, the late-developing economic entities that have been caught in the middle-income trap in history and the duration of the trap are identified, thus providing several policy references and guidance to step-over the middle-income trap.

Method of encapsulating silver nanodots using porous glass and its application in Q-switched all solid-state laser.

Here, we report on a packaging method for silver nanodots (SNDs) by using high-silicate porous glass. Millions of nanopores, which are randomly distributed in porous glass, are used as cells for SND nucleation and growth during the initial chemical-reduction process. Then, the sample is annealed at a high-temperature in a reducing atmosphere to impel the further SND growth and nanopore collapse. The compact SND-embedded transparent glass is synthesized in the end. Morphology characterization shows that the SNDs that are encapsulated in the sample have a uniform size of 1.5 to 4.5 nm. Both the sample's saturable and reverse saturable absorptions are observed under the irradiation of 100 fs laser pulses at 800 nm. Saturable absorption's threshhold is characterized to be 1.4 × 1011 W/cm2, which is much lower than what was ever reported. Furthermore, the SNDs-embedded silica as a saturable absorber (SA) has been demonstrated in the Q-switched Nd:YVO4 laser. The pulse duration as short as 53 nanoseconds is obtained. To our knowledge, it is the first time that SNDs are used as a SA in the passively Q-switched all solid-state laser.

Democracy Versus Dictatorship? The Political Determinants of Growth Episodes

Abstract Whether democracy causes economic growth has been a matter of theoretical and empirical debate. We argue that looking at the average effect of democracy on long-run growth ignores the heterogeneity of growth experiences among authoritarian regimes relative to democratic regimes. Furthermore, the emphasis on long-run growth is not compatible with the stylized facts of economic growth in developing countries, which is characterized by frequent shifts in growth regimes from stagnant or declining growth to accelerations in growth and back again to decelerating growth. We examine the political determinants of the magnitude of growth in accelerations and deceleration episodes for 125 countries for 1950–2010. We find that the effect of the political regime on growth is asymmetric across accelerations and decelerations and that democracies do not necessarily outperform autocracies in a growth acceleration episode, though they are likely to prevent large growth collapses. We also highlight the importance of the type of autocracy in understanding the effects of regime type on growth.