Exact Relationships Research Articles

A comparative study of linear and step forcing temperature profiles in horizontal convection (a) (a)Contribution to the Focus Issue Turbulent Thermal Convection edited by Mahendra Verma and Jörg Schumacher.

We present a numerical study of horizontal convection using both step and linear forcing profiles as the imposed surface thermal driving, the former of which is commonly used in many studies but the latter is closer to the real ocean. Our investigation focuses on how forcing profiles can affect the theoretical and experimental results previously obtained based on the step forcing profile. We show that both types of forcing profiles exhibit similar behaviors in terms of global heat transfer (Nu), mean flow strength (Re), and boundary layer thickness. However, these two forcing profiles show significant differences for some other physical quantities, such as the generation rate of available potential energy G APE and global thermal dissipation rate, for which exact relationships with Nu can be derived for the step forcing profile but not for linear forcing. We show that a relationship between Nu and G APE can be developed for linear forcing by defining an effective forcing area, and such area is found to be approximately constant. We further derive an approximate relationship between Nu and the global thermal dissipation rate for linear forcing by assuming that the boundary heat flux is proportional to the local temperature deviation from the mean, which works best under the condition of moderate plume emissions. Differences are also found for the viscous dissipation rate; however, these differences diminish for sufficiently high Ra. Though step forcing is obviously less appropriate for modeling ocean circulations, we show that most differences arising from the forcing profile difference can be reconciled. Considering its convenience in experiment control and theoretical analysis, step forcing is a good configuration for most problems, but one should also be aware of the differences between step and other forcing types in quantities like the global thermal dissipation rate when extrapolating the results to more general situations.

Osmolyte-Induced Effects on the Hydration Behavior and the Osmotic Second Virial Coefficients of Alkyl-Substituted Urea Derivatives: Critical Assessment of Their Structure-Making/Breaking Behavior.

We analyzed the hydration behavior of alkyl-substituted urea osmolytes in terms of their deviation from Lewis-Randall solution ideality and characterized their structure-making/breaking tendency according to a proposed solvation formalism that provides a rigorous cause-effect connection between the system microstructure and its solution thermodynamic nonidealities. After a brief introduction of the rationale behind the use of Lewis-Randall over alternative solution ideality references, we (i) assessed the effect of the nature and type of alkyl substitution on the osmolyte-induced perturbation of the solution microstructure as a function of composition, (ii) analyzed their microstructural responses to changes in temperature and pressure, and (iii) demonstrated the structure-breaking nature of urea and the magnifying behavior of its alkyl-substituted osmolytes, whose trend follows the increasingly positive deviation of the osmolyte solutions from Lewis-Randall ideality. Then, we discussed the falsifiability of a pair of frequently used conjectured structure-making/breaking criteria, supported by the derived exact relationships between the structure-making/breaking parameter, the solution thermodynamic nonideality, and the osmotic second virial coefficient of the aqueous osmolytes. Finally, we provided an outlook on how the proposed approach could guide the quest for a truly (microstructural to free energy) causative explanation for the denaturation mechanism of proteins.

Metallic Ratios : The Mathematical Relationships between different Metallic Means

This paper introduces the precise mathematical relationships between different Metallic Ratios. Certain distinctive mathematical correlations are found to exist between various Metallic Means. This work presents the empirical formulae those provide the exact mathematical relationships between different Metallic Ratios.

A new phylogenetic hypothesis of Tanystropheidae (Diapsida, Archosauromorpha) and other "protorosaurs", and its implications for the early evolution of stem archosaurs.

The historical clade “Protorosauria” represents an important group of archosauromorph reptiles that had a wide geographic distribution between the Late Permian and Late Triassic. “Protorosaurs” are characterized by their long necks, which are epitomized in the genus Tanystropheus and in Dinocephalosaurus orientalis. Recent phylogenetic analyses have indicated that “Protorosauria” is a polyphyletic clade, but the exact relationships of the various “protorosaur” taxa within the archosauromorph lineage is currently uncertain. Several taxa, although represented by relatively complete material, have previously not been assessed phylogenetically. We present a new phylogenetic hypothesis that comprises a wide range of archosauromorphs, including the most exhaustive sample of “protorosaurs” to date and several “protorosaur” taxa from the eastern Tethys margin that have not been included in any previous analysis. The polyphyly of “Protorosauria” is confirmed and therefore we suggest the usage of this term should be abandoned. Tanystropheidae is recovered as a monophyletic group and the Chinese taxa Dinocephalosaurus orientalis and Pectodens zhenyuensis form a new archosauromorph clade, Dinocephalosauridae, which is closely related to Tanystropheidae. The well-known crocopod and former “protorosaur” Prolacerta broomi is considerably less closely related to Archosauriformes than was previously considered.

The influence of the equation of state on the cellular structure of gaseous detonations

The propagation of multidimensional gaseous detonations at elevated pressures was investigated numerically. Initial conditions at which deviations from ideal gas are expected (i.e., p0 > 2 MPa) were used to assess whether real gas effects influence their multi-cellular structure. The simplest equation of state that accounts for real gas effects was selected, Noble–Abel, and compared with the results obtained using perfect gas. Approximate and exact relationships are provided for the von-Neumann and Chapman–Jouguet states, as well as sound speeds, for both equations of state. Results show that real gas effects alter the multi-cellular structure of gaseous detonations at elevated pressures. Moreover, neglecting these effects renders a more irregular structure than that obtained when real gas effects are reinstated. The source of the perceived instabilities was identified as a Mach bifurcation due to jetting and their growth was related to a shear layer triple point interaction, giving birth to new triple points. The more unstable structure seems to arise from an effective change in the isentropic coefficient that is not included in the perfect gas formulation.

Toxic Effect of Metal-Based Nanomaterials on Representatives of Marine Ecosystems: A Review

The review summarizes the recent data on the toxic effect that engineered metal nanoparticles (NPs) and their oxides (Ag, Au, Cu, CuO, zero-valent iron, TiO2, and ZnO) exert on marine organisms of various taxonomic groups. Toxicity is considered with due regard of the size effects and physicochemical properties of NPs. Available data indicate that metallic NPs may adversely affect algae, bacteria, mollusks, worms, arthropods, echinoderms, chordates, etc. Toxic effects vary from reproductive disorders to death. Only scarce data are available on the NP effect on marine vertebrates (e.g., marine fish). The factors that affect the NP toxicity in an aqueous environment include the physicochemical properties of NPs, species specificities of the test organism, and parameters of the aqueous environment (in particular, salinity, temperature and pH). Exact relationships between the factors and NP toxicity are still poorly understood. In particular, there is no consensus on how salinity affects the NP toxicity in an aqueous environment. Putative mechanisms of NP toxicity include oxidative stress, impaired cell membrane integrity, inflammatory processes with consequent cell dysfunction, DNA damage, and genetic mutations. NPs easily persist within organisms and consequently have a high potential to accumulate in marine food chains. Lack of standardized techniques to detect metallic and metal oxide NPs and weak or absent relevant legislation complicate toxicology studies in marine ecosystems. The above circumstances make it necessary to further evaluate the safety of metallic NPs for marine organisms and especially vertebrates, to study the distant effects associated with NP transition and accumulation in marine food chains, and to unify the respective research protocols. The exact role of environmental factors in modulating NP toxicity and the mechanisms of NP toxicity are also important issues to address in future studies.

Fish without Tail Fins-Exploring the Function of Tail Morphology of the First Vertebrates.

We use a series of hydrodynamic experiments on abstracted models to explore whether primitive vertebrates may have swum under various conditions without a clearly-differentiated tail fin. Cambrian vertebrates had post-anal stubby tails, some had single dorsal and ventral fins, but none had yet evolved a clearly differentiated caudal fin typical of post-Cambrian fishes, and must have relied on their long and flexible laterally-compressed bodies for locomotion, i.e., by bending their bodies side-to-side in order to propagate waves from head to tail. We approach this problem experimentally based on an abstracted model of Metaspriggina walcotti from the 506-million-year old Burgess Shale by using oscillating thin flexible plates while varying the tail fin geometry from rectangular to uniform, and finally to a no tail-fin condition. Despite a missing tail fin, this study supports the observation that the abstracted Metaspriggina model can generate a strong propulsive force in cruise conditions, both away from, and near the sea bed (in ground effect). However, when the abstracted Metaspriggina model moves in ground effect, a weaker performance is observed, indicating that Metaspriggina may not necessarily have been optimized for swimming near the sea bed. When considering acceleration from rest, we find that the Metaspriggina model's performance is not significantly different from other morphological models (abstracted truncate tail and abstracted heterocercal tail). Statistical analysis shows that morphological parameters, swimming modes, and ground effect all play significant roles in thrust performance. While the exact relationships of Cambrian vertebrates are still debated, as agnathans, they share some general characteristics with modern cyclostomes, in particular an elongate body akin to lampreys. Lampreys, as anguilliform swimmers, are considered to be some of the most efficient swimmers using a particular type of suction thrust induced by the traveling body wave as it travels from head to tail. Our current experiments suggest that Metaspriggina's ability in acceleration from rest, through possibly a similar type of suction thrust, which is defined as the ability to generate low pressure on upstream facing sections of the body, might have evolved early in response to increasing predator pressure during the Cambrian Explosion.

Drivers of energy consumption in Kuwaiti buildings: Insights from a hybrid statistical and building performance simulation approach

Understanding and quantifying the drivers of energy consumption in buildings is an essential step to identify inefficiencies and guide energy conservation efforts and policies. While such efforts are common in western countries, they remain limited in the Middle East and North Africa (MENA) region, particularly in the State of Kuwait. This article presents the first systematic assessment of the drivers of energy consumption in Kuwaiti commercial and residential buildings. It presents a unique hybrid study approach combining data collected from 463 buildings with Building Performance Simulation (BPS) developed and validated to mimic the performance of archetype (i.e., typical) Kuwaiti buildings. Results identify the built-up area and the thermostat cooling setpoints as the main determinants of electric consumption, quantifying the exact relationships between these variables. For instance, a simple 2 °C increase in the thermostat cooling setpoint can lead to a more than 10% reduction in total energy use. Other parameters that are typically known to affect building performance, such as the type of Air Conditioning (AC) systems installed, did not show statistically significant effects. The findings helped derive important recommendations for the Kuwaiti authorities, covering the educational, technological, and policy-related dimensions of the challenges facing the building sector.

ANALYSIS OF EMITTER COUPLED MULTIVIBRATORS

The purpose of this investigation is to develop a systematic nonlinear analysis of the circuit in Figure 1, as yet not available in the literature, obtaining an exact formula for the oscillation frequency. Then, we find the condition for the circuit to behave as a relaxation oscillator, or as a nearly sinusoidal oscillator, analyzing the circuit behavior around the equilibrium point through a circuit model accounting for the transistor intrinsic capacitances. A nonlinear analysis of the popular emitter-coupled multivibrator is performed, which is based on the classical discontinuity theory. Exact relationships for calculating its waveform are obtained. Then, we investigate the circuit dynamic behavior showing that at very high frequencies the circuit exhibits a completely different behavior, similar to an LC second-order nearly sinusoidal oscillator. Conditions allowing us to predict one or the other behavior are found.

What Microeconomic Fundamentals Drive Global Oil Prices During 1986-2020?

The global financial crisis of 2007-2009 caused major economic disturbances in the oil market. In this paper we consider five variables describing the microeconomics of supply of, and demand for oil and evaluate their importance before, during and after the global financial crisis. We consider five dissimilar regimes during the period of January 1986 to the end of 2020: two regimes prior to the global financial crisis, the regime during the crisis and two regimes after the crisis. The main hypothesis tested is that oil fundamentals of supply and demand remain important even as the five regimes are dissimilar. We build five boosted and over-fitted neural networks to capture the exact relationships between spot oil prices and oil data related to those prices. This analysis shows that, while the inputs into an accurate neural network can remain the same, the impact of each variable can change considerably during different regimes.

Influence of the Ecological State of the Environment on COVID-19 Distributions

The article analyzes the impact of the ecological state of the environment on the spread of COVID-19 in Ukraine and the world. As of June 1, 2020, 24,012 diseases with COVID-19 were registered in Ukraine, 718 people died. According to the Ministry of Health of Ukraine, there is a gradual increase in the incidence of COVID-19. According to the Ministry of Health of Ukraine, this is due to non-compliance by people with such quarantine measures as the rules of personal protection and social distance. However, finding out the exact causal relationships requires detailed research. Although COVID-19 is thought to be mainly spread by airborne droplets and through infected surfaces or direct personal contact from person to person, high levels of urban air pollution, weather, and specific climatic conditions appear to have a significant impact on increasing levels confirmed COVID-19. Since solid particles with a diameter of less than 2.5 are a very significant concomitant indicator and a prerequisite for the number of confirmed cases of COVID-19 and hospitalizations. It is estimated that the incidence of COVID-19 will increase by almost 100 percent when the concentration of air pollution increases by 20 percent. The results of the research are relevant for the formation of recommendations to public authorities to improve the state environmental policy in terms of modernization of monitoring systems for drinking water quality, water bodies, soils, air. Generalizations will be useful in the implementation of European standards in the field of environmental protection, analytical report for parliamentary hearings, recommendations for the regions of Ukraine to reduce emissions of pollutants into the air and watercourses, compliance with environmental safety requirements to combat the spread of viral infections. As a result of optimization of the environmental monitoring network (air, water, soils, sediments) it will be possible for all competent authorities to make more informed management decisions based on data on the state of the environment. And specific vector recommendations for improving the geo-ecological state of the environment (air quality, reservoirs, soils) in the regions of Ukraine, taking into account the specifics of the ecological state of each region will help combat the spread of viruses and infections, will have a positive impact on public health.

The formation and evolution of macrozone in Ti-6242S alloy during thermo-mechanical processing

In this study, the formation and evolution of macrozone (sharp textured region) in Ti-6242S alloy during thermo-mechanical processing were investigated. In the meantime, the macrozones relating to the evolution behavior of primary α (αp) and β grains were found in obtained bimodal microstructures. As αp grains dissolving in β matrix, the texture intensity of α phase gradually increased, and the macrozones always formed. There existed an abnormal trend between the texture intensity of α phase and the content of αp grains. Because the reason should be notified that, with the heat treatment temperature increasing, the αp grains with small φ tend to be retained. Herein, the parameter φ describes the deviation degree from exact Burgers orientation relationships (BOR, β∆JβBOR) between αp and β grains. Moreover, as the content of αp decreasing, the inhibition effect of αp on the growth of secondary α (αs) colonies weakened, and then increased the area of αs colonies. Under large pre-deformation and heat treatment, the BORs between many αp and their neighboring β grains were destroyed due to the rotation of αp grains. And it was worth noting that β phase was mainly composed of recrystallized grains with high-angle boundaries. These led to a significant decrease in the degree of variant selection (DVS) of αs colonies during β → αs transformation, thus reducing the development of α texture.

New remains of Lophiaspis maurettei (Mammalia, Perissodactyla) from the early Eocene of France and the implications for the origin of the Lophiodontidae

ABSTRACT The Lophiodontidae are endemic perissodactyls from Europe that flourished during the Eocene. Despite their preponderance in the European fossil record, their exact origin and relationships within the perissodactyls remain unknown due to the rare and fragmentary material in the early Ypresian, the time of their earliest radiation. Lophiaspis maurettei is the oldest and earliest diverging lophiodontid known to date but is unfortunately poorly known. We describe here the results of new excavations of the type locality of Palette. Important new material including complete skulls, mandibles, post-cranial elements and juvenile specimens lead us to revise Lophiaspis maurettei from Palette and other localities and to describe novel morphology for this species. According to an original phylogenetic analysis, based on a revised matrix of dental, cranio-mandibular and postcranial characters, Ls. maurettei is an early diverging lophiodontid morphologically close to Protomoropus and Paleomoropus, two basal chalicotheres, known from Asia and North America, respectively. Our resulting topology does not support the previously proposed inclusion of the lophiodontids within the Ceratomorpha and supports a position within the suborder Ancylopoda, close to some Eomoropidae representatives. These results imply that Ls. maurettei was restricted to Southern Europe during the early Eocene, which would be compatible with an Asian origin for lophiodontids in accordance with the evolutionary history of other perissodactyls and placental mammals.

Culicidae evolutionary history focusing on the Culicinae subfamily based on mitochondrial phylogenomics

Mosquitoes are insects of medical importance due their role as vectors of different pathogens to humans. There is a lack of information about the evolutionary history and phylogenetic positioning of the majority of mosquito species. Here we characterized the mitogenomes of mosquito species through low-coverage whole genome sequencing and data mining. A total of 37 draft mitogenomes of different species were assembled from which 16 are newly-sequenced species. We datamined additional 49 mosquito mitogenomes, and together with our 37 mitogenomes, we reconstructed the evolutionary history of 86 species including representatives from 15 genera and 7 tribes. Our results showed that most of the species clustered in clades with other members of their own genus with exception of Aedes genus which was paraphyletic. We confirmed the monophyletic status of the Mansoniini tribe including both Coquillettidia and Mansonia genus. The Aedeomyiini and Uranotaeniini were consistently recovered as basal to other tribes in the subfamily Culicinae, although the exact relationships among these tribes differed between analyses. These results demonstrate that low-coverage sequencing is effective to recover mitogenomes, establish phylogenetic knowledge and hence generate basic fundamental information that will help in the understanding of the role of these species as pathogen vectors.

Modern models of trophic meta-communities.

Dispersal and foodweb dynamics have long been studied in separate models. However, over the past decades, it has become abundantly clear that there are intricate interactions between local dynamics and spatial patterns. Trophic meta-communities, i.e. meta-foodwebs, are very complex systems that exhibit complex and often counterintuitive dynamics. Over the past decade, a broad range of modelling approaches have been used to study these systems. In this paper, we review these approaches and the insights that they have revealed. We focus particularly on recent papers that study trophic interactions in spatially extensive settings and highlight the common themes that emerged in different models. There is overwhelming evidence that dispersal (and particularly intermediate levels of dispersal) benefits the maintenance of biodiversity in several different ways. Moreover, some insights have been gained into the effect of different habitat topologies, but these results also show that the exact relationships are much more complex than previously thought, highlighting the need for further research in this area.This article is part of the theme issue ‘Integrative research perspectives on marine conservation’.

Extreme value theory for constrained physical systems.

We investigate extreme value theory for physical systems with a global conservation law which describes renewal processes, mass transport models, and long-range interacting spin models. As shown previously, a special feature is that the distribution of the extreme value exhibits a nonanalytical point in the middle of the support. We expose exact relationships between constrained extreme value theory and well-known quantities of the underlying stochastic dynamics, all valid beyond the midpoint in general, i.e., even far from the thermodynamic limit. For example, for renewal processes the distribution of the maximum time between two renewal events is exactly related to the mean number of these events. In the thermodynamic limit, we show how our theory is suitable to describe typical and rare events which deviate from classical extreme value theory. For example, for the renewal process we unravel dual scaling of the extreme value distribution, pointing out two types of limiting laws: a normalizable scaling function for the typical statistics and a non-normalized state describing the rare events.

Prenatal PFAS Exposure Influences Infant Lean and Fat Mass

Background: Previous studies have shown maternal exposure to Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) during pregnancy to be associated with birthweight and infant body composition. Childhood obesity rates among Hispanic and African American populations continue to rise and understanding the role of modifiable chemical exposures may reduce the burden of childhood obesity. Methods: Maternal blood samples collected at a mean of 18.8±9.0 weeks gestation from 34 predominantly Hispanic (76.5%) pregnant mothers (mean age 29.5±6.4 years) from the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) cohort were assayed for levels of 14 PFAS. Infant body composition was measured at 1-2 months (52.9% female, mean age 37.9±6.9 days old) by novel technology using quantitative nuclear magnetic resonance (QMR) to assess infant fat and lean mass. Associations between prenatal PFAS levels and infant body composition were assessed by multiple linear regression. Results: Of the PFAS measured, Perfluorooctanesulfonic acid (PFOS, mean 1.3±0.9 ng/mL), Perfluorooctanoic acid (PFOA, mean 0.2±0.3 ng/ml), Perfluorononanoic acid (PFNA, mean 0.08±0.11 ng/mL), Perfluorodecanoic acid (PFDA, mean 0.05±0.04ng/mL), and Perfluorohexanoic acid (PFHXA, mean 1.1±0.6ng/mL) were detected above the limit of detection in more than 50% of samples. These chemicals were all significantly correlated to each other (R=0.51-0.80). After controlling for gestational age at time of blood collection and child age at scan, infant fat mass (mean 1.5±0.3 kg) was significantly inversely associated with PFHXS (β= -0.1, p=0.04) while infant lean mass (mean 2.9±0.4 kg) was significantly positively associated with PFOS (β= 0.2, p=0.02). Conclusion: In this subset of largely Hispanic mother child pairs, maternal exposure to PFHXS in pregnancy was inversely related to infant fat mass while PFOS was positively associated with infant lean mass. Although there is evidence for PFAS influencing newborn body composition, the exact relationships with infant and child body composition and growth over time remain unclear.

Suicide and Schizophrenia: an Interplay of Factors.

The main purpose of this review is to elucidate the interplay of various factors in the relationship between suicide and schizophrenia. Suicide and schizophrenia have been interlinked as a symptom, factor in recovery and prognosis, outcome measure and response to psychotic symptoms in patients with schizophrenia. Many biomarkers have been identified in relation to the two phenomena. The analysis of the papers of the last 5years (2015-2019) and till date has revealed studies looking at outcomes in relation to suicide, biological markers to determine the protection from and occurrence of suicide in schizophrenia and demographic factors that play a role in the occurrence of suicide in patients with schizophrenia. Suicide is a common occurrence in patients with schizophrenia and must be studied further in diverse populations of the disorder to help determine exact relationships between these two variables that will aid in clinical recovery, better outcome and improve prognosis.

Extrapolation and interpolation strategies for efficiently estimating structural observables as a function of temperature and density.

Thermodynamic extrapolation has previously been used to predict arbitrary structural observables in molecular simulations at temperatures (or relative chemical potentials in open-system mixtures) different from those at which the simulation was performed. This greatly reduces the computational cost in mapping out phase and structural transitions. In this work, we explore the limitations and accuracy of thermodynamic extrapolation applied to water, where qualitative shifts from anomalous to simple-fluid-like behavior are manifested through shifts in the liquid structure that occur as a function of both temperature and density. We present formulas for extrapolating in volume for canonical ensembles and demonstrate that linear extrapolations of water's structural properties are only accurate over a limited density range. On the other hand, linear extrapolation in temperature can be accurate across the entire liquid state. We contrast these extrapolations with classical perturbation theory techniques, which are more conservative and slowly converging. Indeed, we show that such behavior is expected by demonstrating exact relationships between extrapolation of free energies and well-known techniques to predict free energy differences. An ideal gas in an external field is also studied to more clearly explain these results for a toy system with fully analytical solutions. We also present a recursive interpolation strategy for predicting arbitrary structural properties of molecular fluids over a predefined range of state conditions, demonstrating its success in mapping qualitative shifts in water structure with density.

Changing to improve? Organizational change and change-oriented leadership in hospitals

PurposeThis paper aims to fill gaps in one’s knowledge of the impact of organizational change on two outcomes relevant to hospital service quality (performance obstacles and physician job satisfaction) and in one’s knowledge of the role of middle manager change-oriented leadership in relation to the same outcomes. Further, the authors aim to identify how physician participation in decision-making is impacted by organizational change and change-oriented leadership, as well as how it mediates the relationships between these two variables, performance obstacles and job satisfaction.Design/methodology/approachThe study adopted a cross-sectional survey design including data from Norwegian hospital physicians (N = 556). A hypothetical model was developed based on existing theory, confirmatory factor analysis was carried out in order to ensure the validity of measurement concepts, and the structural model was estimated using structural equation modelling.FindingsThe organizational changes in question were positively related to performance obstacles both directly and indirectly through participation in decision-making. Organizational change was also negatively related to job satisfaction, both directly and indirectly. Change-oriented leadership was negatively related to performance obstacles, but only indirectly through participation in decision-making, whereas it was positively related to job satisfaction both directly and indirectly.Originality/valueThe authors developed a theoretical model based on existing theory, but to their knowledge no other studies have tested these exact relationships within one model. These findings offer insights relevant to current and ongoing developments in the healthcare field and to the question of how hospitals may deal with continuous changes in ways that could contribute positively towards outcomes relevant to service quality.