Partial Extinction Research Articles

LF-DBS of the Ventral Striatum Shortens Persistence for Morphine Place Preference and Modulates BDNF Expression in the Hippocampus

BackgroundDeep brain stimulation (DBS) of the ventral capsule/ventral striatum (VC/VS) represents a promising therapy for treatment-refractory patients with substance-use disorders. We previously found that low-frequency (LF) DBS aimed to the VC/VS during extinction training strengthens the extinction memory for morphine seeking under a partial extinction protocol. Objectives/HypothesisIn this study, animals were tested in a full extinction protocol to determine whether LF-DBS applied during extinction facilitates extinction while preventing drug reinstatement, and study the molecular mechanisms underlying the effects of LF-DBS, Methods/ResultsWe used a full extinction CPP paradigm combined with LF-DBS to assess behavior. Western blots for the pro-extinction molecule, brain-derived neurotrophic factor (BDNF) were then performed in corticomesolimbic regions of the brain. Lastly, to determine whether changes in BDNF expression elicited by LF-DBS were specific to the VS/NAc afferents from the hippocampus, amygdala, and medial prefrontal cortex, we performed BDNF-like immunohistochemistry, combined with the retrograde tracer cholera toxin B (CtB). ResultsWe showed a significant reduction in the number of days required to fully extinguish morphine CPP in animals exposed to LF-DBS during extinction training accompanied by a significant increase in BDNF expression in the hippocampus. However, LF-DBS applied during extinction did not prevent drug reinstatement. Lastly, no changes in BDNF/CtB double-labeled cells were found in VS/NAc projecting cells after one-day exposure to LF-DBS. Conclusion(s)These data suggest that LF-DBS can facilitate extinction of morphine CPP by decreasing drug seeking through potential synaptic plasticity changes in the hippocampus to strengthen extinction memories.

Lean Blowout Proximity Sensing in a Low Emission Liquid-Fueled Combustor

ABSTRACT Advanced aircraft engine combustor designs, intended for achieving low NOx emissions, necessitate lean combustion with small operating margins above the LBO boundary, posing a high risk of exhibiting lean blowout (LBO) problems. Employing active LBO controllers receiving input from LBO proximity sensors can allow for narrower margins, thereby yielding multiple performance gains. Although several previous studies investigated LBO proximity sensing, they predominantly focused on premixed gas-fueled combustors. The application of proximity sensing approaches to liquid-fueled combustor designs, relevant to aircraft engines have not received adequate attention. Therefore, this study investigates LBO proximity sensing in a low emission lean direct injection (LDI) liquid-fueled combustor design developed by NASA. The combustor operates at atmospheric pressure with preheated air. The proximity sensing is examined by analyzing both OH* and CH* chemiluminescence signals, with a focus on assessing their relative performances. The signal analysis approaches include spectral, partial extinction event (LBO precursor) detection, signal RMS, and the CH*/OH* ratio, with an emphasis on the first two methods. Both steady-state and transient operating conditions have been examined. The combustor did not exhibit large-scale flame partial extinction and re-ignition events near LBO, as commonly observed in gas-fueled combustors. However, an increase in flame unsteadiness and partial extinction events with very subtle signatures in optical signals, have been observed. Low-pass filtering has been observed to considerably enhance the precursor signatures enabling their improved detection. With a reduction in LBO margin, an increase in signal low-frequency power, RMS, and precursor event occurrence rate have been observed, which were utilized for providing LBO proximity measures. A key finding from this study is that CH* signals provide significantly superior performance compared to OH* for the proximity sensing in all the approaches, and the potential reasons are discussed.

Extinction Chains Reveal Intermediate Phases Between the Safety and Collapse in Mutualistic Ecosystems

Ecosystems are undergoing unprecedented persistent deterioration due to unsustainable anthropogenic human activities, such as overfishing and deforestation, and the effects of such damage on ecological stability are uncertain. Despite recent advances in experimental and theoretical studies on regime shifts and tipping points, theoretical tools for understanding the extinction chain, which is the sequence of species extinctions resulting from overexploitation, are still lacking, especially for large-scale nonlinear networked systems. In this study, we developed a mathematical tool to predict regime shifts and extinction chains in ecosystems under multiple exploitation situations and verified it in 26 real-world mutualistic networks of various sizes and densities. We discovered five phases during the exploitation process: safe, partial extinction, bistable, tristable, and collapse, which enabled the optimal design of restoration strategies for degraded or collapsed systems. We validated our approach using a 20-year dataset from an eelgrass restoration project. Counterintuitively, we also found a specific region in the diagram spanning exploitation rates and competition intensities, where exploiting more species helps increase biodiversity. Our computational tool provides insights into harvesting, fishing, exploitation, or deforestation plans while conserving or restoring the biodiversity of mutualistic ecosystems.

Mode shape-dependent thermoacoustic interactions between a lean-premixed primary flame and an axially-staged transverse reacting jet

Axial fuel staging enables elevation of the turbine inlet temperature in advanced heavy-duty gas turbine combustors to ∼2000 K, ultimately to achieve more than 65% combined cycle efficiency, while limiting excessive nitrogen oxide production. While previous investigations have identified transverse jet-flow-dependent nitrogen oxides emission trends and the topological properties of reacting shear layers in vitiated crossflow environments, there exists a critical gap in the understanding of axial-fuel-staging-induced combustion instabilities. The present study therefore investigates the link between first- and second-stage flame dynamics in a lean-premixed combustor. We demonstrate that the second-stage jet-in-vitiated-crossflow flame is preferentially coupled to higher order acoustic modes than the upstream primary flame with the same characteristic nozzle dimension. The first- and second-stage-driven acoustic modes (two different timescales) are mutually incompatible, and the ensuing selective excitation is critically dependent on the position of the secondary injector relative to the mode shape. When the second-stage flame is located near a pressure node, or a velocity antinode, the transverse jet-stabilized flame is influenced by the primary flame-driven crossflow velocity oscillations, and exhibits conspicuous flapping motions in the crossflow direction accompanied by periodic partial extinction at the windward and leeward-side flame elements. If the second-stage flame is situated near a pressure antinode, on the other hand, the secondary jet flame's dynamics are governed by a combination of jet merging-induced flame surface destruction and the growth of non-axisymmetric coherent structures. In this case, high-intensity pressure oscillations are sustained by the local heat release fluctuations generated solely from the transverse reacting jets, whereas the upstream primary flame remains nearly unperturbed, or decoupled from the underlying feedback processes. This experimental observation is remarkable, and reflects previously unknown properties originating from the complex interactions between the two axially-staged lean-premixed flames.

Transmission of hydrogen detonation across a curtain of dilute inert particles

Transmission of hydrogen detonation wave (DW) in an inert particle curtain is simulated using the EulerianLagrangian approach. A detailed chemical mechanism is used to predict the detonative combustion of a stoichiometric hydrogen-air mixture and parametric studies are conducted based on a two-dimensional computational domain. A detonation map of propagation and extinction corresponding to various particle sizes, concentrations, and curtain thicknesses is plotted. It is shown that the critical curtain thickness decreases considerably when the particle concentration is less than the critical value. The effects of curtain thickness on the trajectories of peak pressure, shock front speed, and heat release rate are examined. Three propagation modes of the DW in particle curtain are found: detonation transmission, partial extinction and detonation re-initiation, as well as detonation extinction. The first two modes are analyzed with the evolutions of shock frontal structures and chemical explosive mode. The chemical explosive mode analysis confirms that a detonation re-initiation event is caused by a re-initiation point with high pressure and explosive propensity, resulting from transverse shock focusing. The influence of particle dimeter/concentration, and curtain thickness on the DW are also examined with peak pressure trajectories, shock speed, and interphase exchange rates of energy and momentum. In addition, small variations of the curtain thickness will affect the short-term behaviors of detonation development, but the long-term DW behaviors are negligibly affected. Furthermore, the evolutions of curtain morphologies are analyzed by the particle velocity, volume fraction, Stokes drag and Archimedes force. This analysis confirms the importance of drag force in influencing the curtain morphologies. Different curtain evolution regimes are found: quasi-stationary regime, shrinkage regime, constant-thickness regime, and expansion regime. Finally, the influences of the curtain thickness on the characteristic time of curtain evolutions are studied. It is found that all characteristic time become smaller when the curtain thickness increases.

Multimodal distribution of transient time of predator extinction in a three-species food chain.

The transient dynamics capture the time history in the behavior of a system before reaching an attractor. This paper deals with the statistics of transient dynamics in a classic tri-trophic food chain with bistability. The species of the food chain model either coexist or undergo a partial extinction with predator death after a transient time depending upon the initial population density. The distribution of transient time to predator extinction shows interesting patterns of inhomogeneity and anisotropy in the basin of the predator-free state. More precisely, the distribution shows a multimodal character when the initial points are located near a basin boundary and a unimodal character when chosen from a location far away from the boundary. The distribution is also anisotropic because the number of modes depends on the direction of the local of initial points. We define two new metrics, viz., homogeneity index and local isotropic index, to characterize the distinctive features of the distribution. We explain the origin of such multimodal distributions and try to present their ecological implications.

Study on partial discharge characteristics of C6F12O mixed gas

The greenhouse effect of SF6 increasingly limits its application in various gas insulated equipment. C6F12O combines the advantages of insulation resistance, safety and environmental protection. When mixed with buffer gas, C6F12O is considered to have potential application prospects in medium and low voltage equipment. In this paper, about the partial discharge characteristics of the mixed gas, an experimental study was carried out. The partial discharge initiation voltage and discharge extinction voltage of mixed gas under power frequency voltage are measured and compared with the breakdown voltage. The results show that the breakdown voltage is greatly improved after adding C6F12O, with the increase of mixing ratio, the partial discharge initiation voltage and extinction voltage of mixed gas gradually increase, and the effect of gas pressure on high mixing ratio is obvious. The difference between the partial discharge inception voltage and the breakdown voltage is larger than that of pure N2. The research in this paper can provide an important reference for the application, operation and protection of C6F12O mixed gas in medium and low voltage equipment.

Host diversification is concurrent with linear motif evolution in a Mastadenovirus hub protein

Over one hundred Mastadenovirus types infect seven orders of mammals. Virus-host coevolution may involve cospeciation, duplication, host switch and partial extinction events. We reconstruct Mastadenovirus diversification, finding that while cospeciation is dominant, the other three events are also common in Mastadenovirus evolution. Linear motifs are fast-evolving protein functional elements and key mediators of virus-host interactions, thus likely to partake in adaptive viral evolution. We study the evolution of eleven linear motifs in the Mastadenovirus E1A protein, a hub of virus-host protein–protein interactions, in the context of host diversification. The reconstruction of linear motif gain and loss events shows fast linear motif turnover, corresponding a virus-host protein–protein interaction turnover orders of magnitude faster than in model host proteomes. Evolution of E1A linear motifs is coupled, indicating functional coordination at the protein scale, yet presents motif-specific patterns suggestive of convergent evolution. We report a pervasive association between Mastadenovirus host diversification events and the evolution of E1A linear motifs. Eight of 17 host switches associate with the gain of one linear motif and the loss of four different linear motifs, while five of nine partial extinctions associate with the loss of one linear motif. The specific changes in E1A linear motifs during a host switch or a partial extinction suggest that changes in the host molecular environment lead to modulation of the interactions with the retinoblastoma protein and host transcriptional regulators. Altogether, changes in the linear motif repertoire of a viral hub protein are associated with adaptive evolution events during Mastadenovirus evolution.

Morphology-based phylogeny of oval palm and flower beetles (Coleoptera: Mycteridae: Eurypinae), with descriptions of new genera and species from Australia

Abstract Mycteridae are a small group of Tenebrionoidea, comprising three subfamilies and over 180 species. Eurypinae are the most species-rich subfamily, with diverse external morphology of adults at both generic and species levels. To date, no study of mycterid systematics using phylogenetic approaches has been conducted. In this paper, we reconstruct a phylogeny of eurypine beetles based on morphological characters, covering most described genera. This is the first attempt to investigate the evolution and relationships of Mycteridae. The phylogenetic positions of several systematically enigmatic genera can thus be hypothesized based on the topology. Recent molecular phylogenetic frameworks and fossil records reveal that most eurypine lineages probably evolved during the Late Mesozoic to Early Cenozoic. Our results also indicate that the fauna of the current regions of the world and Early Cenozoic Europe consist(ed) of various eurypine lineages, supporting the previously proposed hypothesis that Eurypinae were once widely distributed, but underwent a subsequent partial extinction. Two new genera and three new species are described from Australia, based on comparative anatomy and cladistic analysis, namely Austroconomorphus slipinskii gen. et sp. nov., Austrophaeogala lawrencei gen. et sp. nov. and Austrophaeogala ovipennis sp. nov. We demonstrate that the phylogenetic diversity of Mycteridae in Australia is greater than previously suspected.

Insight into flickering/shedding in buoyant droplet-diffusion flame during interaction with vortex

The interaction of incident vortex with buoyant diffusion flame of a pendant fuel droplet (n-dodecane) is investigated in the present study. The flame stretching/shedding events occur depending on vortex strengths, which are characterized using vortex Reynolds number (Rev). Different flame response regimes have been identified for different vortex strengths. The velocity scale associated with the vortices is higher when compared to natural convection velocity leading to forward extinction, followed by flame lift-off. The flame lift-off increases with Rev, and partial extinction occurs at very high Rev. In all the cases, the flame oscillates/sheds during the vortex interaction, which causes a momentary increase in the flame heat release rate. As the vortex moves past the flame, the oscillations dampen gradually, and the flame regains the natural buoyant behavior. The high-velocity scales imposed during vortex interaction make the flow momentum-dominant, resulting in a low Richardson number (Ri). Since, the flickering frequency scaling valid for Ri>>1 is not obeyed, a new scaling has been proposed to incorporate the vortex momentum effect by using vortex circulation instead of gravity. Only a portion of the incident vortex circulation contributes to the shedding as some of it is lost to forward extinction and lift-off events. Thus, the reduced vortex velocity scale is used to estimate the critical circulation. The flame shedding height calculated using new scaling in the critical circulation equation agrees with experimental observations.

Dynamic properties for a stochastic food chain model

In this paper, Lyapunov exponents of ergodic invariant measures are used to study dynamic properties for a stochastic food chain model, which consists of two competing predators and one prey. Ayala’s experimental result, or rather, competitive coexistence is showed to be possible in this random case. Furthermore, the considered stochastic model have five points of dynamical bifurcation, which happen to be the thresholds (between survival and extinction) of the system or each species. In addition, the necessity of introducing environmental noise is verified by the fact that environmental driving force can drive the system towards extinction from partial extinction or coexistence. Moreover, all the theoretical results are well verified by numerical simulations. It is worth mentioning that we make a first attempt at using meshing method and statistical data to test Lyapunov exponents for two-dimensional boundary measures, and this is an innovation in the numerical methods.

Archeologický a památkový potenciál zaniklého osídlení v pohraničí. Komparativní studie vývoje sídelních struktur po roce 1945

The topic of the presented paper finds itself on the border of archaeology, historiography and heritage studies. We compare the circumstances of the complete or partial extinction of settlements in the former Czechoslovak borderland after 1945 in connection with the events that followed the end of World War II. The comparison concerns two areas that lie at opposite e nds of today‘s Czech Republic. The comparison is based on three North Bohemian settlements: Hohenwald (High, Vysoký), Hoffnungstahl (Valley of Hope, Údolí Naděje) and Strickerhäuser (Clearings, Mýtiny) located near the border with Poland. We compare them with villages in the Gratzener Berglands (Novohradské Mountains, Novohradské hory) in the very south of Bohemia near the border with Austria.

Effects of optogenetic photoexcitation of infralimbic cortex inputs to the basolateral amygdala on conditioned fear and extinction

Deficiencies in the ability to extinguish fear is a hallmark of Trauma- and stressor-related disorders, Anxiety disorders, and certain other neuropsychiatric conditions. Hence, a greater understanding of the brain mechanisms involved in the inhibition of fear is of significant translational relevance. Previous studies in rodents have shown that glutamatergic projections from the infralimbic prefrontal cortex (IL) to basolateral amygdala (BLA) play a crucial instructional role in the formation of extinction memories, and also indicate that variation in the strength of this input correlates with extinction efficacy. To further examine the relationship between the IL→BLA pathway and extinction we expressed three different titers of the excitatory opsin, channelrhodopsin (ChR2), in IL neurons and photostimulated their projections in the BLA during partial extinction training. The behavioral effects of photoexcitation differed across the titer groups: the low titer had no effect, the medium titer selectively facilitated extinction memory formation, and the high titer produced both an acute suppression of fear and a decrease in fear during (light-free) extinction retrieval. We discuss various possible explanations for these titer-specific effects, including the possibility of IL-mediated inhibition of BLA fear-encoding neurons under conditions of sufficiently strong photoexcitation. These findings further support the role of IL→BLA pathway in regulating fear and highlight the importance of methodological factors in optogenetic studies of neural circuits underling behavior.

The probabilities of extinction in a branching random walk on a strip

AbstractWe consider a class of multitype Galton–Watson branching processes with a countably infinite type set $\mathcal{X}_d$ whose mean progeny matrices have a block lower Hessenberg form. For these processes, we study the probabilities $\textbf{\textit{q}}(A)$ of extinction in sets of types $A\subseteq \mathcal{X}_d$ . We compare $\textbf{\textit{q}}(A)$ with the global extinction probability $\textbf{\textit{q}} = \textbf{\textit{q}}(\mathcal{X}_d)$ , that is, the probability that the population eventually becomes empty, and with the partial extinction probability $\tilde{\textbf{\textit{q}}}$ , that is, the probability that all types eventually disappear from the population. After deriving partial and global extinction criteria, we develop conditions for $\textbf{\textit{q}} < \textbf{\textit{q}}(A) < \tilde{\textbf{\textit{q}}}$ . We then present an iterative method to compute the vector $\textbf{\textit{q}}(A)$ for any set A. Finally, we investigate the location of the vectors $\textbf{\textit{q}}(A)$ in the set of fixed points of the progeny generating vector.

Dynamic self-tuning, flickering and shedding in buoyant droplet diffusion flames under acoustic excitation

We report the mechanism of acoustic-flame coupling for buoyant diffusion flame in droplets. The flame under acoustic excitation exhibits differential varicose and sinuous modes including partial extinction and pinch offs at certain shedding heights. Contrary to traditional buoyant flames, the diameter (d) regression of a droplet results in self-tuning of the instability modes with progression in burning times. In essence, we show that a droplet exhibits multi frequency response with advent of new oscillations modes at different points of the burning lifetime. The acoustic perturbations modulate the flame surface or heat release only at lower frequency bands by feeding energy into the natural vortical stability modes of a buoyant plume. Interestingly, we unearth that a flame is naturally unstable at all frequencies lower than g/d. Acoustic pumping at any such frequency (<g/d) corresponds to a unique convective length scale h such that fflame=g/h. We therefore establish that the flame exhibits multiple convective length scales throughout the burning cycle. We subsequently established that the shedding length scale of the droplet flame shortens by more than 25% with increase in acoustic pressure. We theoretically proved that using critical circulation argument, one can uniquely determine the shedding length scale at any acoustic loading. However, it is interesting to note that while the acoustic pressure amplitude is crucial for determining the convective length at which a flame rolls up, the frequency of excitation has no role to play. In other words, the velocity field introduced by the acoustic pressure is responsible for the shedding of the flame. The acoustic perturbations also lead to bulk oscillation of the flame surface near the forward stagnation zone. This is attributed to the acoustic induced velocity that leads to transient shifting of the stoichiometric surface.

Zonation of Lithuanian Silurian graptolites and other faunal groups

The Baltic Silurian Basin, Lithuanian Depression and other structures are shown in the map, with marked by isopachs (contour lines of equal thickness) of the Silurian beds with graptolites and fauna of other groups. The Silurian facies vary greatly in the Depression – from clayey open-sea deep shelf to carbonaceous ones of shallow shelf, and low-energy lagoon facies. The history of investigations on East Baltic area graptolites begins from 1953–1958, when 15 graptolite zones were singled out, and proceeds to 35 zones defined now. Peculiarities in the graptolite scale from C. cyphus to N. lochkovensis inclusive are discussed. Transgressions and regressions of the Silurian marine basin, as well as shorter transgressions with wedges and graptolites of clayey facies shifted towards basin shores and regressions with partial extinction of graptolites are elucidated. During these investigations the graptolite scale has been detailed and added with new zones. Graptolite evolution in the zones has been analysed. Stages of graptolite evolution are analysed in relation to the following bioevents: Stačiūnai, Likėnai, Valgu, Ireviken, Mulde, Linde, Lau, Klev and Šilalė. Finally, two tables present graptolite zone correlation with conodont, vertebrate and ostracod zones revealing a highly detailed stratigraphy of the Lithuanian Silurian.

Extinction in lower Hessenberg branching processes with countably many types

We consider a class of branching processes with countably many types which we refer to as Lower Hessenberg branching processes. These are multitype Galton–Watson processes with typeset $\mathcal{X}=\{0,1,2,\ldots\}$, in which individuals of type $i$ may give birth to offspring of type $j\leq i+1$ only. For this class of processes, we study the set $S$ of fixed points of the progeny generating function. In particular, we highlight the existence of a continuum of fixed points whose minimum is the global extinction probability vector $\boldsymbol{q}$ and whose maximum is the partial extinction probability vector $\boldsymbol{\tilde{q}}$. In the case where $\boldsymbol{\tilde{q}}=\boldsymbol{1}$, we derive a global extinction criterion which holds under second moment conditions, and when $\boldsymbol{\tilde{q}}<\boldsymbol{1}$ we develop necessary and sufficient conditions for $\boldsymbol{q}=\boldsymbol{\tilde{q}}$. We also correct a result in the literature on a sequence of finite extinction probability vectors that converge to the infinite vector $\boldsymbol{\tilde{q}}$.

Dynamic Behaviors of a Competitive System with Beddington-DeAngelis Functional Response

This article studies a competitive system with Beddington-DeAngelis functional response and establishes sufficient conditions on permanence, partial extinction, and the existence of a unique almost periodic solution for the system. The results supplement and generalize the main conclusions in recent literature. Numerical simulations have been presented to validate the analytical results.

Da “cidade integrada” à “favela como oportunidade”: empreendedorismo, política e “pacificação” no Rio de Janeiro

Resumo A intervenção federal na área da segurança pública no estado do Rio de Janeiro, iniciada em fevereiro de 2018, e o anúncio da extinção de parte do Programa de Polícia Pacificadora levantaram a questão sobre o que muda e o que permanece no cenário das favelas cariocas após dez anos de “pacificação”. Este artigo procura responder a tal indagação, jogando luz sobre uma dimensão desse processo: a produção de uma nova sociabilidade nesses territórios, onde o empreendedorismo se apresentou como elemento fundamental. A partir de etnografia realizada em favelas com UPP e do acompanhamento de projetos públicos e privados executados à época, analisamos o impacto dessa produção sobre o tecido associativo dessas localidades.

Attractivity of saturated equilibria for Lotka-Volterra systems with infinite delays and feedback controls

In this paper, we apply a Lyapunov functional approach to Lotka-Volterra systems with infinite delays and feedback controls and establish that the feedback controls have no influence on the attractivity properties of a saturated equilibrium. This improves previous results by the authors and others, where, while feedback controls were used mostly to change the position of a unique saturated equilibrium, additional conditions involving the controls had to be assumed in order to preserve its global attractivity. The situation of partial extinction is further analysed, for which the original system is reduced to a lower dimensional one which maintains its global dynamics features.