Hasil untuk "Evolution"

T. Clutton‐Brock, B. Sheldon

J. Mckinnon, J. Staton, M. Bell et al.

A. Hendry, M. Kinnison

Douglas Grion Filho, Puragra Guhathakurta, Stanley M. Rinehart V et al.

The recent discovery that red supergiants in M31 and M33 contain a weak CN spectral absorption feature at ​​​​​​∼8000 Å prompted us to analyze a large CTIO 4 m Hydra spectral database of stars in the Large Magellanic Cloud (LMC). We find 751 confirmed weak CN stars in the LMC, present an overview of their spectral and photometric properties, and compare them with the weak CN stars in M31 and M33. We use a method for automatically identifying weak CN stars based on a spectral template and find that weak CN stars are almost exclusively short-lived massive stars in the core He-burning evolutionary phase. We derive a mean main-sequence age of 40 Myr for these stars through a Bayesian approach to isochrone fitting that is consistent across all three galaxies. We then examine possible evolutionary processes and atmospheric conditions that could lead to weak CN stars using a suite of low-resolution model spectra. We find a preferred range of values for T _eff and log g in O-rich stars that would result in the CN absorption and also speculate that this feature could arise due to the N enhancement expected in fast-rotating stars, though more targeted modeling is required.

Junpeng Zheng, Ruhao Zhao, Cong Zhang et al.

Generalized two-dimensional (2D) Airy beam is a kind of self-accelerating beam with variable initial angle between its two wings, manifested itself as an initial angle determined parabolic trajectory during the free-space propagation. However, the independent and flexible manipulation of both the transverse optical field and longitudinal trajectory of the generalized 2D Airy beam has not been achieved yet which limits its application in the various fields. Herein, we report on tailoring of the propagation properties of the generalized 2D Airy beam based on the catastrophe theory, where analytical expression of its propagation trajectory is derived. In order to clarify the relationship between the transverse optical field distribution and the longitudinal trajectory, we analytically put forward a generation vector, facilitating the tailoring of both longitudinal trajectory and transverse distribution of optical field simultaneously. Consequently, we can effectively generate the generalized 2D Airy beam and precisely manipulate the evolution of its peak intensity. Once the initial and terminal points of trajectory are determined in advance, we can flexibly tailor the trajectory of 2D Airy beam, with the help of corresponding generation vector. Meanwhile, when the longitudinal trajectory is fixed, we can flexibly rotate the transverse optical field distribution of the generalized 2D Airy beam and manipulate its initial angle. Experimental verifications of the manipulation capabilities for the longitudinal trajectory, initial angle, and the rotation of transverse optical field are provided to validate our theoretical results.

Vladislav Jakubu, Iveta Vrbova, Ibrahim Bitar et al.

Background: Aminopenicillins are recommended agents for non-invasive Haemophilus influenzae infections. One of the mechanisms of resistance to β-lactams is the alteration of the transpeptidase region of penicillin binding protein 3 (PBP3) which is caused by mutations in the ftsI gene. It was shown that exposure to beta-lactams has a stimulating effect on increase of prevalence of H. influenzae strains with the non-enzymatic mechanism of resistance. Objectives: The aim of our study was to compare the mutational potential of ampicillin and cefuroxime in H. influenzae strains, determination of minimum inhibitory concentration and the evolution of mutations over time, focusing on amino acid substitutions in PBP3. Methods: 30 days of serial passaging of strains in liquid broth containing increasing concentrations of ampicillin or cefuroxime was followed by whole-genome sequencing. Results: On average, cefuroxime increased the minimum inhibitory concentration more than ampicillin. The minimum inhibitory concentration was increased by a maximum of 32 fold. Substitutions in the PBP3 started to appear after 15 days of passaging. In PBP3, cefuroxime caused different substitutions than ampicillin. Conclusions: Our experiment observed differences in mutation selection by ampicillin and cefuroxime. Selection pressure of antibiotics in vitro generated substitutions that do not occur in clinical strains in the Czech Republic.

Guillermo A. Mena Marugán, Antonio Vicente-Becerril, Jesús Yébana Carrilero

We investigate the implications of different quantization approaches in Loop Quantum Cosmology for the primordial power spectrum of tensor modes. Specifically, we consider the hybrid and dressed metric approaches to derive the effective mass that governs the evolution of the tensor modes. Our study comprehensively examines the two resulting effective masses and how to estimate them in order to obtain approximated analytic solutions to the tensor perturbation equations. Since Loop Quantum Cosmology incorporates preinflationary effects in the dynamics of the perturbations, we do not have at our disposal a standard choice of privileged vacuum, like the Bunch–Davies state in quasi-de Sitter inflation. We then select the vacuum state by a recently proposed criterion which removes unwanted oscillations in the power spectrum and guarantees an asymptotic diagonalization of the Hamiltonian in the ultraviolet. This vacuum is usually called the NO-AHD (from the initials of Non-Oscillating with Asymptotic Hamiltonian Diagonalization) vacuum. Consequently, we compute the power spectrum by using our analytic approximations and by introducing a suitable numerical procedure, adopting in both cases an NO-AHD vacuum. With this information, we compare the different spectra obtained from the hybrid and the dressed metric approaches, as well as from the analytic and numerical procedures. In particular, this proves the remarkable accuracy of our approximations.

Catarina de Nazaré Pereira Pinheiro, Roosevelt de Lima Sardinha, Pablo Machado Barros et al.

Neural networks have been used in various computer vision applications, including noise removal. However, removing seismic noise via deep learning approaches faces a specific issue: the scarcity of labeled data. To address this difficulty, this work introduces an adaptation of the Noise2Self algorithm featuring a one-shot learning approach tailored for the seismic context. Essentially, the method leverages a single noisy image for training, utilizing a context-centered masking system and convolutional neural network (CNN) architectures, thus eliminating the dependence on previously labeled data. In tests with Gaussian noise, the method was competitive with established approaches such as Noise2Noise. Under real noise conditions, it demonstrated effective noise suppression removal for a smaller architecture. Therefore, our proposed method is a robust alternative for noise removal that is especially valuable in scenarios lacking sufficient data and labels. With a new approach to processing seismic images, particularly in terms of denoising, our method contributes to the ongoing evolution and enhancement of techniques in this field.

WANG Xiang, ZHANG Guicai, JIANG Ping et al.

The volume sweep coefficient is essential for evaluating the development effect and formulating development adjustment plans for oil fields. This paper aims to study the variation law of volume sweep coefficient in different stages of water injection development. From the perspective of the injection pore volume multiple， a calculation model is built of displacement efficiency and injection pore volume multiple， and a calculation method of volume sweep coefficient is proposed based on oil-water relative flow theory and reservoir engineering principle. In addition， three test areas of Shengli Oilfield are taken as examples for calculation and analysis. The results show that the relationship between the displacement efficiency and the injection pore volume multiple satisfies an exponential equation， and the relationship curve between the two is upward convex. As the injection pore volume multiple increases， the displacement efficiency gradually increases from the minimum displacement efficiency and approaches the maximum displacement efficiency. The displacement efficiency calculation model is verified， and the average relative error between the predicted and measured values is only 1.90%. During the water flooding development， the relationship curve between the volume sweep coefficient and the injection pore volume multiple shows an evolution trend of fast rising， slow rising， and near platform. The calculation results can guide the effect evaluation of development adjustment measures. At present， the volume sweep coefficient of the three test areas is about 90%. There is a large amount of remaining oil in the swept area. It is urgent to study the description and start-up method of the main remaining oil in the swept area.

Li Wang, Chengyuan Li, Long Wang et al.

The detection of split main sequences (MSs) associated with young clusters (≲600 Myr) has attracted a lot of attention. A prevailing scenario is that a bimodality of stellar rotation distribution drives the bifurcation of the MS. Nevertheless, the origin of the stellar rotation dichotomy remains unclear. Hypotheses involving tidally locked binaries or blue straggler stars (BSSs) have been proposed to explain the observed split MSs. This work examines if the long-term dynamical evolution of star clusters can produce the observed split MSs, through high-performance N -body simulation. For example, the young massive cluster NGC 1856 exhibits an apparent MS bifurcation. Our simulation reports that at the age of NGC 1856, tidally locked binaries are fully mixed with single stars. This is consistent with the observation that there is no significant spatial difference between blue MS and red MS stars. However, we find that only high-mass-ratio binaries can evolve to the tidally locked phase at the age of the NGC 1856. These tidally locked binaries will populate a much redder sequence than the MS of single stars rather than a blue MS, which is inconsistent with the hypothesis. The number of tidally locked binaries cannot account for the observation. Our simulation shows that BSSs produced by binary interactions do populate in the blue periphery as shown in a color–magnitude diagram, and their spatial distribution shows a similar pattern of single stars. However, the number of BSSs does not fit the observation.

Iia Chudayeva, Boris Dmitruk

The authors of the article analyze the reasons for the rapid development and implementation of artificial intelligence achievements, which opens up great opportunities for solving problems in many industries and is a reliable assistant to people in everyday life. The article analyses different approaches to the definition of "artificial intelligence", possible threats to humanity from its implementation, and focuses on the need to increase the responsibility of developers of programs, algorithms, systems and strengthen control over the work of users of equipment and devices with elements of artificial intelligence. People around the world have long been dependent on technical inventions and devices. The achievements of artificial intelligence provide people with convenience and comfortable conditions. The development of intelligent machines is an important area of scientific and technological progress. Artificial intelligence technologies contribute to solving many problems related to various areas of life, including the economy. Today, artificial intelligence is a global trend in technology development and innovation. Advances in computing power, the ability to collect and process huge amounts of information, and instant access to the latest algorithms are important prerequisites for the evolution of intelligent technologies. The development of sophisticated computers and robots poses risks to the world’s people. Without the use of artificial intelligence, the development of scientific and technological progress is impossible. Key words: artificial intelligence, the achievement of civilization, a threat to humanity, strengthening control over the operation of machines. Therefore, the development of intelligent machines and devices must continue, but with the warnings of global authorities who warn of the existing threat to humanity.

Violette Chiara, Sin‐Yeon Kim

Abstract Computer programs for video tracking of animal movement are evolving increasingly efficient, using complex algorithms or artificial intelligence systems. Despite the consequent progress in this field, researchers still face some fundamental problems in the use of such programs. For example, the best‐performing programs are often uneasy to use, and user‐friendly programs require source videos recorded under strict conditions (e.g. homogenous environments, constant lighting and high resolution), which may be difficult to meet in both laboratory and field studies. We present here AnimalTA, a new program that tracks and analyses animal movement in diverse environments. This program aims to be accessible to everyone, including those without knowledge of coding and image analysis. AnimalTA allows to process rapidly a high number of videos and manage multi‐arena tracking. It is adapted to follow the movement of targets in variable conditions, including heterogenous and complex environments, or in low‐quality videos. AnimalTA provides tools for editing videos and correcting problems caused by camera tremors, light changes or perspective deformation. AnimalTA also allows the user to easily correct tracking errors and repeat the tracking in a subsample of the video. The target's identity can be personalized to facilitate video analysis. The tracking results can be analysed in AnimalTA to obtain many different variables related to the trajectory of each target, such as average speed, total distance travelled, latency to reach defined areas, distance to a defined point, distance to other individuals, number of contacts with others, explored surface, among others. Users can set and control different parameters for these analyses and directly view the results.

Vivek S. Kale, Shilpa Patil Pillai

The present exposures of the (Mesoproterozoic to Neoproterozoic) Purana basins of Peninsular India occupy nearly 1.5 × 105 km2 area in the Indian subcontinent, with an equal area being concealed under younger cover or lost to ensuing erosion. These extensional basins evolved on the margins (& with basement) of the existing cratonic blocks during the ‘boring billion years’ of Earth history. They host nearly 0.8 million km3 of epicratonic compacted and lithified sediments derived by weathering and erosion of the adjoining cratonic blocks and deposited on their fringes.The volumetric contents of these basins and their temporal distribution are compiled. The relative distribution and secular variations of sediment contents from these basins appear to synchronise with global Proterozoic supercontinental assembly and dispersal cycles. A comparison of mass-transfer by the erosion of the provenance area and sedimentation in continent margin basins shows that the volumes preserved in the Purana basins are at least 2 magnitudes larger than what can be derived from adjoining cratonic areas within the Indian Subcontinent. Much wider continental masses as well as exhumation (aided by uplift) of km-scale magnitudes of the provenance areas are required to reconcile their volume. Possible linkages with other cratonic blocks within the contemporary supercontinental assemblies are required to resolve this discrepancy.

Yin Changchuan

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the current global COVID-19 pandemic, in which millions of lives have been lost. Understanding the zoonotic evolution of the coronavirus may provide insights for developing effective vaccines, monitoring the transmission trends, and preventing new zoonotic infections. Homopolymeric nucleotide repeats (HP), the most simple tandem repeats, are a ubiquitous feature of eukaryotic genomes. Yet the HP distributions and roles in coronavirus genome evolution are poorly investigated. In this study, we characterize the HP distributions and trends in the genomes of bat and human coronaviruses and SARS-CoV-2 variants. The results show that the SARS-CoV-2 genome is abundant in HPs, and has augmented HP contents during evolution. Especially, the disparity of HP poly-(A/T) and ploy-(C/G) of coronaviruses increases during the evolution in human hosts. The disparity of HP poly-(A/T) and ploy-(C/G) is correlated to host adaptation and the virulence level of the coronaviruses. Therefore, we propose that the HP disparity can be a quantitative measure for the zoonotic evolution levels of coronaviruses. Peculiarly, the HP disparity measure infers that SARS-CoV-2 Omicron variants have a high disparity of HP poly-(A/T) and ploy-(C/G), suggesting a high adaption to the human hosts.

Olívia Prado Schiavon, Márcia Ramos May, Andréa Torres Barros Batinga de Mendonça

Purpose – The study aims to understand how dynamic capabilities (DCs) contribute to business model innovation (BMI) in sustainable family farming. The agrifood sector has been seeking solutions for the development of agroecological markets. Thus, the authors have analyzed the challenges imposed to innovation and sustainability strategic management and the value proposition to sustain the business over the years. Design/methodology/approach – Considering the complexity of organizations and through an exploratory multiple case study of initiatives identified in the Organic Fair of Curitiba’s Passeio Público, it was possible to analyze the evolution of the business models (BMs) and the fair itself. Furthermore, it was possible to identify the DCs within the influence of agroecosystem elements on the innovation development. Findings – Analyzing each case individually, the authors understood the different dimensions of the evolution of BMs considering the organizational complexity. The authors conclude that the balance between organizational practices and changes in the environment, engagement and learning plays a significant role in the developing competitive advantage. The same applies to the patterns that precede the development of DCs and BMs. Originality/value – The article investigates innovation in agroecological BMs from a dynamic capability perspective. The agroecological BM is a subject that is still little discussed in the literature. In addition, the authors chose a context that includes socioenvironmental aspects and a few specificities of family farming in Brazil.

Hao Lu, Yunpeng Zhang, Peng Hao et al.

The accurate characterization and prediction of current–voltage (I–V) characteristics of photovoltaic (PV) modules under different weather conditions are essential for solar power forecasting and ensuring grid stability. This paper proposed a novel method based on the power-law model (PLM) for estimating PV module performance under different weather conditions without setting reference conditions. The effects of solar irradiance, ambient temperature, and module types are all fully considered. The dependence of shape parameters in PLM on irradiance and temperature are thoroughly investigated and the effect of the selection of reference conditions is eliminated by modifying a set of new transforming equations. The parameters of the new transforming equations can be extracted from experimental data by an optimization algorithm. Due to the advantages of PLM, the proposed method applies to any type of PV module and the I–V characteristics can be expressed explicitly without Lambert W-function or iterative solution. The effectiveness and accuracy proposed method are verified and tested on the large datasets of eighteen PV modules in three locations. Compared with existing methods, the proposed method shows higher accuracy and better performance in the estimation of I–V characteristics and maximum power under different weather conditions.

Wentian Yu, Chen Wang, Gengliang Wang et al.

In this study, the flocculation performance and kinetics of magnetic cationic polyacrylamide (MCPAM) microspheres, compared with cationic polyacrylamide (CPAM), were systematically investigated under different magnetic field strengths. Flocculation performance was observed by jar test experiment. The density of flocs was estimated by the determination of floc settlement velocity and image analysis. The frequency distribution of floc size was measured with a Malvern Mastersizer instrument. When the diatomite suspension was treated by MCPAM and CPAM, the residual diatomite turbidity was 16.28 NTU and 244.13 NTU, respectively. The maximum turbidity removal efficiency of MCPAM was about 99.65% under 1000 Gauss magnetic field, which was higher than that (94.75%) of CPAM. The synergy of gravitational and magnetic fields for MCPAM promoted the formation of larger flocs with higher growth rates compared with CPAM. The effective density range of flocs in the MCPAM flocculation was increased to 10–252 kg m−3. The kinetic constants were calculated by monitoring the frequency of floc collisions. The increase of kinetic constant (k) to 25.81 × 10−11 s−1 suggested that interaction of contact and collision between magnetic flocs was sufficient. According to the evolution of the size and density of flocs under the synergy of gravitational and magnetic fields, the magnetic flocculation rate equation dN/dt=−1/9μρ−ρlg+ρkmHdH/dXai2−aj2−ai2e9μt/2ai2ρ+aj2e9μt/2aj2ρai+aj2 was derived. The study of magnetic flocculation kinetics can provide theoretical support for magnetic flocculation and is critical for the analysis of solid-liquid separation processes.

João Filipe Riva Tonini, Diogo B. Provete, Natan M. Maciel et al.

Abstract Allometric constraint is a product of natural selection and physical laws, particularly with respect to body size and traits constrained by properties thereof, such as metabolism, longevity, and vocal frequency. Allometric relationships are often conserved across lineages, indicating that physical constraints dictate scaling patterns in deep time, despite substantial genetic and ecological divergence among organisms. In particular, acoustic allometry (sound frequency ~ body size) is conserved across frogs, in defiance of massive variation in both body size and frequency. Here, we ask how many instances of allometric escape have occurred across the frog tree of life using a Bayesian framework that estimates the location, number, and magnitude of shifts in the adaptive landscape of acoustic allometry. Moreover, we test whether ecology in terms of calling site could affect these relationships. We find that calling site has a major influence on acoustic allometry. Despite this, we identify only four major instances of allometric escape, potentially deriving from ecomorphological adaptations to new signal modalities. In these instances of allometric escape, the optima and strength of the scaling relationship are different than expected for most other frog species, representing new adaptive regimes of body size ~ call frequency. Allometric constraints on frog calls are highly conserved and have rarely allowed escape, despite frequent invasions of new adaptive regimes and dramatic ecomorphological divergence. Our results highlight the rare instances in which natural and sexual selection combined can overcome physical constraints on sound production.

J. A. Crowther

Leopoldo F. M. Machado, Andrew Currin, Neil Dixon

Abstract Background Transcription factor-based biosensors are useful tools for the detection of metabolites and industrially valuable molecules, and present many potential applications in biotechnology and biomedicine. However, the most common approach to develop biosensors relies on employing a limited set of naturally occurring allosteric transcription factors (aTFs). Therefore, altering the ligand specificity of aTFs towards the detection of new effectors is an important goal. Results Here, the PcaV repressor, a member of the MarR aTF family, was used to develop a biosensor for the detection of hydroxyl-substituted benzoic acids, including protocatechuic acid (PCA). The PCA biosensor was further subjected to directed evolution to alter its ligand specificity towards vanillin and other closely related aromatic aldehydes, to generate the Van2 biosensor. Ligand recognition of Van2 was explored in vitro using a range of biochemical and biophysical analyses, and extensive in vivo genetic-phenotypic analysis was performed to determine the role of each amino acid change upon biosensor performance. Conclusions This is the first study to report directed evolution of a member of the MarR aTF family, and demonstrates the plasticity of the PCA biosensor by altering its ligand specificity to generate a biosensor for aromatic aldehydes.