Energetic constraints

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Biparental incubation scheduling : no experimental evidence for major energetic constraints

Biparental incubation scheduling : no experimental evidence for major energetic constraints

Incubation is energetically demanding, but it is debated whether these demands constrain incubation-scheduling (i.e., the length, con- stancy, and timing of incubation bouts) in cases where both parents incubate. Using 2 methods, we experimentally reduced the ener- getic demands of incubation in the semipalmated sandpiper, a biparental shorebird breeding in the harsh conditions of the high Arctic. First, we decreased the demands of incubation for 1 parent only by exchanging 1 of the 4 eggs for an artificial egg that heated up when the focal bird incubated. Second, we reanalyzed the data from the only published experimental study that has explicitly tested ener- getic constraints on incubation-scheduling in a biparentally incubating species (Cresswell et al. 2003). In this experiment, the energetic demands of incubation were decreased for both parents by insulating the nest cup. We expected that the treated birds, in both experi- ments, would change the length of their incubation bouts, if biparental incubation-scheduling is energetically constrained. However, we found no evidence that heating or insulation of the nest affected the length of incubation bouts: the combined effect of both experi- ments was an increase in bout length of 3.6 min (95% CI: −33 to 40), which is equivalent to a 0.5% increase in the length of the average incubation bout. These results demonstrate that the observed biparental incubation-scheduling in semipalmated sandpipers is not primarily driven by energetic constraints and therefore by the state of the incubating bird, implying that we still do not understand the factors driving biparental incubation-scheduling.

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The multi-scale structure of atmospheric energetic constraints on globally averaged precipitation

The multi-scale structure of atmospheric energetic constraints on globally averaged precipitation

Recently, Nogueira (2019) analyzed satellite-based obser- vational datasets, a long global climate model (GCM) sim- ulation, and reanalysis products and found a tight corre- lation ( ∼ 0.8) between anomaly (deseasonalized) time se- ries of globally averaged precipitable water vapor and sur- face temperature, which emerged at timescales larger than ∼ 1–2 years. In contrast, at smaller timescales the corre- lation decreased rapidly towards negligible values (< 0.3). In other words, the Clausius–Clapeyron relationship is the dominant mechanism of atmospheric moisture anomalies at multiyear timescales, but not at sub-yearly timescales. Nogueira (2019) also found that the magnitude of the cor- relations between anomaly time series for globally averaged precipitation and surface temperature was negligible at sub- yearly timescales, while at multiyear timescales the results showed large spread amongst different datasets, ranging be- tween negligible (< 0.3) and strong ( ∼ 0.8) correlation val- ues. Building on this previous study, here the multi-scale analysis of the mechanisms governing global precipitation variability was extended, including the energetic constraints on precipitation represented in Eq. (2). The paper is orga- nized as follows: Sect. 2 describes the considered datasets and the multi-scale analysis framework; the results of multi- scale correlation analysis of precipitation variability are pre- sented and discussed in Sect. 3; and in Sect. 4 the validity of the linear sensitivity correlations derived from the multi- scale analysis is demonstrated by employing a simple lin- ear model to reconstruct globally averaged precipitation time series from energetic constraints. At sub-yearly timescales, at which the correlations break down, it is shown in Sect. 5 how the monthly statistics can be reproduced by employing a stochastic downscaling algorithm based on scale-invariant symmetries of precipitation. Finally, the main conclusions are summarized and discussed in Sect. 6.

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Energetic constraints on electric signalling in wave type weakly electric fishes

Energetic constraints on electric signalling in wave type weakly electric fishes

The goal of this study was to explore the energetic costs of electrical signalling by identifying potential trade-offs between EOD (frequency and amplitude) and oxygen uptake during hypoxia stress in two wave-type gymnotiform fishes thought to differ in low oxygen tolerance. Apteronotus leptorhynchus (Ellis 1912) is typically found in well-oxygenated whitewater systems in South America and is thought to be relatively intolerant of hypoxia (Crampton, 1998; Crampton and Albert, 2006). This species has an electric organ that is derived from nerve cells (Kirschbaum and Schwassmann, 2008) and that produces baseline EOD frequencies of 800 to 1000Hz in males and 600 to 800Hz in females. It is thought that individual A. leptorhynchus do not modulate EOD frequency or amplitude in response to environmental changes (except temperature) (see Dunlap et al., 2000), even though they use frequency modulations in a communication context (Hagedorn and Heiligenberg, 1985; Zakon et al., 2002). In contrast, Eigenmannia virescens (Valenciennes 1836) is found in both high- and low-oxygen systems such as várzea (floodplains), and whitewater and blackwater systems of South America, and appears to be more hypoxia tolerant than A. leptorhynchus, both in its natural habitat and under experimental conditions (Crampton, 1998; Julian et al., 2003; Kirschbaum and Schwassmann, 2008). The electric organ of E. virescens is derived from muscle tissue and produces a lower EOD frequency compared with A. leptorhynchus, ranging from approximately 250 to 600Hz (Hopkins, 1974). Males tend to have lower EOD frequencies than females, although there is a large degree of overlap (Hopkins, 1974; Hagedorn and Heiligenberg, 1985). Eigenmannia virescens are also

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Getting fat or getting help? How female mammals cope with energetic constraints on reproduction

Getting fat or getting help? How female mammals cope with energetic constraints on reproduction

faster when the father was present, which may indirectly benefit females when young are weaned earlier [59]. In females of a facultatively cooperative breeding bird species, the splendid fairy-wren (Malurus splendens), the presence of helpers has been shown to increase survival of the breed- ing females and reduce the time for these females to renest after a brood [60]. Lastly, in another facultative cooperative breeder, the western bluebird (Sialia mexicana), the pres- ence of helpers allowed the breeding female to lower her feeding rate, while nestlings still received more feeds at nests with helpers compared to nests without helpers present [60]. In sum, there is ample empirical evidence that distributing the costs of reproduction over two or more in- dividuals yields an energetic benefit for mothers or off- spring. We do not distinguish between the two, as a net fitness effect can be obtained by either.

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Energetics and genetics across the prokaryote-eukaryote divide

Energetics and genetics across the prokaryote-eukaryote divide

A final point on phagocytosis: prokaryotes compete among themselves, ultimately on the basis of replication speed, albeit under a wide range of conditions, permitting large variations in cell size and metabolic versatility. Regardless of this variation, replication speed depends in large part on ATP availability (to the point that initiation of replication depends on the ATP/ADP ratio), which is in general optimal in quite small cells, with high surface- area-to-volume ratio, hence the typically small size of bacteria. Phagocytosis, once it has evolved, breaks this loop, as success no longer depends on replication speed – a phagocyte can simply eat the opposition, and the faster they replicate the more it has to eat. Thus, once phagocy- tosis has evolved, the terms of the deal change. Energy per gene becomes relatively unimportant, as large cells simply sequester their dinner and digest it later, even using com- paratively inefficient processes such as fermentation. Thus the key point of this paper is that prokaryotes are con- strained in genome size and morphological complexity by their energetics, to the point that they cannot evolve com- plex traits such as phagocytosis de novo. Mitochondria eliminated these energetic constraints, allowing the free accumulation of potentially massive amounts of DNA in a central nucleus, the genetic raw material needed for the evolution of larger size and morphological complexity. Having eliminated this barrier, complex traits such as phagocytosis could evolve–could evolve, I emphasize that the energetics are permissive, not prescriptive–which ulti- mately meant that lifestyle became much more important than energy-per-gene as the major determinant of genome size in eukaryotes.

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Control Theoretic Analysis of Human Brain Networks

Control Theoretic Analysis of Human Brain Networks

In this paper, we address the question of how large-scale brain circuitry and distinct en- ergetic constraints produce whole-brain patterns of activity. We build our approach on a maximum entropy model of brain dynamics that is explicitly informed by estimates of white matter microstructure derived from deterministic tractography algorithms. The model al- lows us to study minimal energy states, which we observe to be composed of co-activity in local spatially-contiguous sets of brain regions reminiscent of cognitive systems. These systems are differentially active, and activity patterns are significantly correlated with the observed activation rate measured in a separate resting state fMRI data set. Finally, we exercise this model to ask how cognitive systems utilize the minimal energy presumably available to them. We find that the energy utilized within and between cognitive systems distinguishes 4 classes of energy utilization dynamics, corresponding to sensorimotor, default mode, attention, and cognitive control functions. These results suggest that diverse cog- nitive systems are optimized for differential contributions to integrated versus segregated function via distinct patterns of energy utilization. More generally, the results highlight the importance of considering energetic constraints in linking structural connectivity to observed dynamics of neural activity.

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Coherency for the critical condition of DDT and SDT in energetic materials

Coherency for the critical condition of DDT and SDT in energetic materials

With the development of the rocket’s boosting technology, propellant in the ratio of explosive is increased to enhance the boosting efficiency which makes the distinguish between the solid explosive and propellant disappearing. So they are called generally high energetically dense materials or energetic material. Deflagration and detonation are two important properties for energetic materials. Consideration for reliability, the energetic materials should detonate reliably when it is used for warhead and deflagrate reliably when it is used for propeller. Concern the relative safety of energetic materials, it should not detonate when production, transportation, shortage, or even ignition by accident. So the investigation of the properties, mechanism, critical condition and threshold value of the shock to detonation transition (SDT) [1-3]. and deflagration to detonation transition (DDT) [4],are important to design, production and application.

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A multiobjective TPM Strategic Release Planning model and its application on a CRM project

A multiobjective TPM Strategic Release Planning model and its application on a CRM project

In our previous paper [7], we have proposed a new S-TRPM approach for TPM release planning that considers the customer satisfaction and TPM constraints from a strategic perspective. Thereafter, we have studied the applicability of our model within a CRM project case that was managed with a TPM contract [8]. This CRM project, which was called “ABC project”, is a large-complex project that generates huge volume of change requests and requires at least one release per month. Application of the ad-hoc RP approach

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Deep dielectric charging of regolith within the Moon's permanently shadowed regions

Deep dielectric charging of regolith within the Moon's permanently shadowed regions

Abstract Energetic charged particles, such as galactic cosmic rays (GCRs) and solar energetic particles (SEPs), can penetrate deep within the lunar surface, resulting in deep dielectric charging. This charging process depends on the GCR and SEP currents, as well as on the regolith’s electrical conductivity and permittivity. In permanently shadowed regions (PSRs) near the lunar poles, the discharging timescales are on the order of a lunation (∼20 days). We present the first predictions for deep dielectric charging of lunar regolith. To estimate the resulting subsurface electric fields, we develop a data-driven, one-dimensional, time-dependent model. For model inputs, we use GCR data from the Cosmic Ray Telescope for the Effects of Radiation on board the Lunar Reconnaissance Orbiter and SEP data from the Electron, Proton, and Alpha Monitor on the Advanced Composition Explorer. We find that during the recent solar minimum, GCRs create persistent electric fields up to ∼700 V/m. We also find that large SEP events create transient but strong electric fields ( ≥ 10 6 V/m) that may induce dielectric breakdown. Such breakdown would likely result

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Solar Energetic Particles (SEP) and Galactic Cosmic Rays (GCR) as tracers of solar wind conditions near Saturn:event lists and applications

Solar Energetic Particles (SEP) and Galactic Cosmic Rays (GCR) as tracers of solar wind conditions near Saturn:event lists and applications

Please cite this article as: E. Roussos, C.M. Jackman, M.F. Thomsen, W.S. Kurth, S.V. Badman, C. Paranicas, P. Kollmann, N. Krupp, R. Buˇc´ık, D.G. Mitchell, S.M. Krimigis, D.C. Hamilton, A. Radioti, Solar Energetic Particles (SEP) and Galactic Cosmic Rays (GCR) as tracers of solar wind conditions near Saturn: event lists and applications, Icarus (2017), doi: 10.1016/j.icarus.2017.08.040

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An Economic-Ecological Transdisciplinary Approach on the Binomial Relationship between Energetic Sustainability and the Environment

An Economic-Ecological Transdisciplinary Approach on the Binomial Relationship between Energetic Sustainability and the Environment

to be the main catalyst in developing higher technologies and innovation as well as higher responsibility for a rational consumption of goods and resources and environment protection, in so named (3+1) R paradigm (reduce, reuse, recycle, recombine) [16,26]. The consumerism with its "consume more energy in order to be more complex“, known as "chemical imperialism", in which the chemicals harvested are stored matter-energy, is a false economic progress concept which cannot grow the level of complexity, so, it is necessary to rethink the socio-economic development strategies, in the context of the circular economy in the knowledge based society/economy [16,27,30-32], as a final goal of the advanced knowledge represented through the hetero-hierarchic levels of the semiophysical synergistic signification pattern, synergy (1+1>2) and signification (1 - 1 ≠ 0) [28]. Considering the chains of energy production, transportation and processing, with electric energy as a final link, the supplementation of the system of known and general accepted concepts is required – the principle of thermal equilibrium, the principle of conservation (non-creation energy) and the principle of entropy with a new conceptual frame, that of eco-energy, as sum and synthesis of what energy means for human life and for the planet [9,10,24]. Therefore, a new, original concept should be introduced, the eco-energetic efficiency e of an energetic system, alongside with its final electrical energy product, with its energetic efficiency η, and the ecological coefficient τ of the system was also introduced. From this perspective, the paper is focused on the analysis of some known energetic chains that have as final product electrical energy [14,33]. In order to better understand the issue of energy-environment relationship, a new modular approach of this relationship is suggested. In most cases, one part of the processed energy does not reach the consumer, or it bears a large load on ecological costs (emission of CO 2 , CO, NO x , SO 2 , HC, dioxine, thermal pollution, noise pollution, population

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Reducing gravity takes the bounce out of running

Reducing gravity takes the bounce out of running

A simple explanation posits that the behaviour is energetically beneficial. To explore the energetic consequences of choosing to run with lower leaps in reduced gravity, we first considered the impulsive model of running, following Rashevsky (1948) and Bekker (1962), which treats a human runner as a point mass body bouncing off rigid vertical limbs (Fig. 1). Stance is treated as an inelastic, impulsive collision with the ground. In reality, stance occurs in finite time, and elastic mechanisms exist. However, the inelastic approximation is remarkably productive in explaining gait choice (Ruina et al., 2005). When we use the term ‘ energetic cost of collisions ’ , we are generally referring to non-recoverable energy loss during stance resulting from some interaction of the centre of mass with the ground (Bertram and Hasaneini, 2013). Such losses may arise from damping, active negative work or discontinuous velocity profiles. In any case, modelling these interactions as an inelastic collision provides a simple estimation of the net cost.

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Energetic-Ion-Driven Global Instabilities Observed in the Large Helical Device and Their Effects on Energetic Ion Confinement

Energetic-Ion-Driven Global Instabilities Observed in the Large Helical Device and Their Effects on Energetic Ion Confinement

slowing down time is much longer than the energy confine- ment time of bulk plasma; that is, the beam beta is much higher than the bulk plasma beta. Extremely large potential fluctuations in the GAM and the radial profile were mea- sured by a heavy-ion beam probe technique [48, 49]. The possibility of bulk ion heating by GAM bursts is under dis- cussion [50]. Note that the energy transfer from energetic particles to waves is proportional to (ω∂ f /∂W + n∂ f /∂P ϕ ) in a tokamak plasma, where ω, n, f , W, and P ϕ are the mode angular frequency, toroidal mode number, energetic particle distribution function, particle energy, and canon- ical angular momentum, respectively [51, 52]. The first term, ω∂ f /∂W, is related to the gradient or anisotropy of the distribution function in velocity space, and the second is the driving term due to the radial gradient of the ener- getic particle density. Accordingly, the modes with n = 0, such as the energetic-ion-driven GAM, are destabilized by the gradient in velocity space. The destabilization mecha- nism can also be applied to helical/stellarator plasmas, but only for well-circulating particles in 3D plasmas with large N, where P ϕ is approximately conserved [52]. This con- dition is roughly satisfied for energetic ions produced by tangential NBI in LHD plasmas.

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On the Relatedness and Nestedness of Constraints

On the Relatedness and Nestedness of Constraints

Task constraints are usually defined as those specified by the task to be performed(e.g., ball size and shape, spe- cific goals to be achieved, boundary lines, playing field length, number of opponents and teammates involved, situational characteristics of opponents such as players’ relative position, and approach speed) [29]. They are re- lated to the task goal, the environmental information, and the instructions and rules. Rules and instructions can simply constrain the task (e.g., say what is forbidden) or specify the response dynamics (e.g., prescribe the ac- tion solution or the pattern of coordination). For in- stance, a referee can award a penalty kick and signal the kick but does not impose the task solutions, i.e., actions (direction of the kick, type of shoot, etc.). In contrast, a competition rule may require the performance of a set of gymnastics skills. Thus, task constraints can be di- vided into specific, when they specify the movement form or action to be performed, and non-specific, when they do not specify it [5].

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Rotationally driven magnetic reconnection in Saturn's dayside

Rotationally driven magnetic reconnection in Saturn's dayside

the noon sector of giant planetary magnetospheres 6 . However, so far dayside magnetic reconnection has only been identified at the magnetopause. Here we report the direct evidence of near-noon reconnection within Saturn’s magnetodisc using measurements from the Cassini spacecraft. The measured energetic electrons and ions, ranging from tens to hundreds of keV, and the estimated energy flux of ~2.6 mW/m 2 within the reconnection region are sufficient to power aurorae. We suggest that dayside magnetodisc reconnection can explain bursty phenomena in the dayside magnetospheres of giant planets, which can potentially advance our understanding of quasi-periodic injections of relativistic electrons 6

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Nonlinear Hybrid Simulations of Energetic Particle Modes in Realistic Tokamak Flux Surface Geometry

Nonlinear Hybrid Simulations of Energetic Particle Modes in Realistic Tokamak Flux Surface Geometry

with non-circular flux surfaces remains to be determined. Such a stabilization may result from changes in continuum damping, field line connection length, drift orbit trajecto- ries, or the coupling between field line curvature and ener- getic ion pressure tensor, through which the kinetic com- pression enters the MHD equations. Here, the field line connection length is similar in both cases and the linear mode frequency is a factor of 2-3 below the ellipticity- induced gap, so we expect continuum damping to be simi- lar in both cases and focus our attention on the kinetic en- ergetic ion compression and pressure-curvature coupling. Preliminary measurements of the energetic ion pressure field indicate that the ratio of pressure perturbations (nor- malized by mode amplitude) between shaped and circular cases lies in the range 0.6 to 0.9, indicating that the kinetic compression is indeed weaker in the shaped case. In ad- dition, shaping-induced changes in the pressure-curvature coupling may a ff ect EPMs in a similar way as MHD bal- looning modes (e.g., see Fig. 5 in Ref. [8]). Further study with additional diagnostics are required to explain the dif- ferent growth rates in the circular and shaped case.

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Energetic cost of communication

Energetic cost of communication

produced and initial melanin synthesis during feather production entails little energetic expense compared with activity. By contrast, the physical activity and acoustic or electric signal production entail significant energetic expense, presumably paid for through other metabolic savings. In addition, SMRs of every male B. gauderio we tested exceeded those of every female, despite the presumed trade-off (Fig.6). Androgens increase signal power in B. gauderio (Allee et al., 2009), and also reduce immunocompetence in a variety of vertebrates (Cutolo et al., 2002; Deviche and Cortez, 2005). Thus, males with the strongest signals could be obtaining the energy needed to boost signal power by reallocating energy away from immune function or other ‘discretionary’ functions (Wedekind and Folstad, 1994).

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Cyclotron amplification of whistler mode waves: a parametric study relevant to discrete VLF emissions in the earth's magnetosphere

Cyclotron amplification of whistler mode waves: a parametric study relevant to discrete VLF emissions in the earth's magnetosphere

studies by making a detailed comparison of the amplification rates for both smooth and step-like distribution functions, for similar values of parameters such as energetic electron number density, energy, and transverse (pitch angle) aniso- tropy. In particular, we show that choosing the parameters according to recent observations of triggered VLF emissions [Bell et al., 2000] yields a sufficient amplification rate to explain these triggered emissions for the step-like distribu- tion function, whereas that is impossible if a smooth distri- bution with the same parameters is assumed.

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Energetic Extended Edge Finding Filtering Algorithm for Cumulative Resource Constraints

Energetic Extended Edge Finding Filtering Algorithm for Cumulative Resource Constraints

To our knowledge, the word “energetic edge-finder” was firstly used in [3] where the author incorporates the en- ergy-based deduction rule to edge-finder algorithm for disjunctive (unary) resource. The idea of hybridization of the edge-finding rule and the energetic reasoning for cumulative resource was suggested in [4]. Indeed, in [4], Mercier and Van Hentenryck propose a two phase edge-finding algorithm where in the first phase, the po- tential adjustment values are computed. They found that many of these potential update values are unused and can be used inside an energetic-based second phase. After this suggestion, many filtering algorithms, hybridization of edge-finding rule and energetic reasoning have been proposed [5,6]. In [6], the authors use in the first phase, the edge-finding algorithm of [7,8] to compute the poten- tial update values and identify the corresponding time bounds of task intervals which provide the maximum update values. To each task, the time bounds used in the second phase is either the task intervals of maximum density or the task intervals of minimum slack. The re- sulting algorithm runs in   2

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Effect of diet quality and ambient temperature on the use of torpor by two species of neotropical nectar feeding bats

Effect of diet quality and ambient temperature on the use of torpor by two species of neotropical nectar feeding bats

present physiological constraints that limit their energy intake, especially when they feed on sugar concentrations below 15% (Levey and Martínez del Rio, 1999; Martínez del Rio et al., 2001; Ayala-Berdon et al., 2008). Studies performed with glossophaginid bats have found large differences in their capacity to acquire energy when the sugar concentration in their diets varies (Ramírez P et al., 2005; Ayala-Berdon et al., 2008; Ayala-Berdon and Schondube, 2011). While the nectar-feeding bats Leptonycteris nivalis and Choeronycteris mexicana are capable to achieve compensatory feeding, and have an energy intake independent of sugar concentration (Ayala-Berdon and Schondube, 2011; Ayala- Berdon et al., 2013), other species like G. soricina and L. yerbabuenae exhibit limited energy intake when they face a reduction in the energetic content of their food (Ramírez P et al., 2005; Ayala-Berdon et al., 2008). Previous studies have shown that disaccharidase activity, monosaccharide absorption/transport rates and gut size are the main mechanisms controlling the total energy intake in nectar-feeding birds and glossophaginid bats (Martínez del Rio, 1990; Hernández and Martínez del Rio, 1992; Ayala-Berdon et al., 2008, 2013). In the case of our study species, the activity of the disaccharidase sucrase and monosaccharide absorption/ transport rates are paired (Ayala-Berdon et al., 2008; Herrera M and Mancina G, 2008); as a consequence, when these bats feed on sucrose, the activity of the enzyme is the mechanism that determines the upper limit of their energy intake (Martínez del Rio and Stevens, 1989; Ayala-Berdon et al., 2008, 2009).

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