The aim of this work was to carry out monitoring of some elements considered toxic in sediments from Lerma River. An analytical method was optimized in our laboratory for quantification of nickel (Ni), cobalt (Co), ma...The aim of this work was to carry out monitoring of some elements considered toxic in sediments from Lerma River. An analytical method was optimized in our laboratory for quantification of nickel (Ni), cobalt (Co), manganese (Mn), arsenic (As), chromium (Cr) and lead (Pb) by using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Ten sediments were collected along the Lerma River at variable distances and at 20 cm depth. Samples were heated to 60°C to dryness, followed by separation of particle size using a 74-μ No. 200 mesh for homogeneity purposes. 0.2 g of sample underwent microwave-assisted acid digestion, followed by plate evaporation. The samples were dissolved in 10 mL with HNO3 at 5% v/v for ICP-OES analysis. A certified reference material (CRM 8704) was used to evaluate the method’s accuracy and precision. The method showed linearity, precision, accuracy, and limits of quantification and detection acceptable for protocol validation of analytical method. The average results obtained in recovery of CRM 8704 were ~90% and precision was below 7% for all elements. Levels concentration of As, Cr, Pb show high pollution in A1, A7 and A8 sites. Therefore, Co, Mn and Ni can be considered in this study as normal values. In conclusion, concentration levels of As, Cr, Pb in sediments were high according to US-EPA and NOM-147-SEMARNAT/SSA1-2004. The presence of these heavy metals in Lerma River could be due mainly for the emitted from industries, such as pharmaceutical, automotive, metal mechanics and tannery, and urban residual water. Finally, the method developed using ICP-OES has enabled monitoring of these elements in sediments from Lerma River, with possible applications in a routine analytical laboratory.展开更多
Realizing the full potential of ultrahigh-intensity lasers for particle and radiation generation will require multi-beam arrangements due to technology limitations.Here,we investigate how to optimize their coupling wi...Realizing the full potential of ultrahigh-intensity lasers for particle and radiation generation will require multi-beam arrangements due to technology limitations.Here,we investigate how to optimize their coupling with solid targets.Experimentally,we show that overlapping two intense lasers in a mirror-like configuration onto a solid with a large preplasma can greatly improve the generation of hot electrons at the target front and ion acceleration at the target backside.The underlying mechanisms are analyzed through multidimensional particle-in-cell simulations,revealing that the self-induced magnetic fields driven by the two laser beams at the target front are susceptible to reconnection,which is one possible mechanism to boost electron energization.In addition,the resistive magnetic field generated during the transport of the hot electrons in the target bulk tends to improve their collimation.Our simulations also indicate that such effects can be further enhanced by overlapping more than two laser beams.展开更多
In the present work, we investigate the inverse problem of reconstructing the parameter of an integro-differential parabolic equation, which comes from pollution problems in porous media, when the final observation is...In the present work, we investigate the inverse problem of reconstructing the parameter of an integro-differential parabolic equation, which comes from pollution problems in porous media, when the final observation is given. We use the optimal control framework to establish both the existence and necessary condition of the minimizer for the cost func- tional. Furthermore, we prove the stability and the local uniqueness of the minimizer. Some numerical results will be presented and discussed.展开更多
Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star formation.In particular,we have recently demonstrated the possib...Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star formation.In particular,we have recently demonstrated the possibility of simulating in the laboratory the process of the accretion of matter on young stars[G.Revet et al.,Sci.Adv.3,e1700982(2017)].The present paper focuses on x-ray spectroscopy methods that allow us to investigate the complex plasma hydrodynamics involved in such experiments.We demonstrate that we can infer the formation of a plasma shell,surrounding the accretion column at the location of impact with the stellar surface,and thus resolve the present discrepancies between mass accretion rates derived from x-ray and optical-radiation astronomical observations originating from the same object.In our experiments,the accretion column ismodeled by having a collimated narrow(1 mm diameter)plasma stream first propagate along the lines of a large-scale external magnetic field and then impact onto an obstacle,mimicking the high-density region of the stellar chromosphere.A combined approach using steady-state and quasi-stationarymodels was successfully applied tomeasure the parameters of the plasma all along its propagation,at the impact site,and in the structure surrounding the impact region.The formation of a hot plasma shell,surrounding the denser and colder core,formed by the incoming stream of matter is observed near the obstacle using x-ray spatially resolved spectroscopy.展开更多
The effects of the polarization potential serve to model spectra of alkaline atoms. These effects have been known for a long time and notably explained by the physicist Max Born (1926). The experimental knowledge of t...The effects of the polarization potential serve to model spectra of alkaline atoms. These effects have been known for a long time and notably explained by the physicist Max Born (1926). The experimental knowledge of these alkaline spectra enables us to specify the values of these quantum defects. A simple code is used to calculate two quantum defects for which <em>δ<sub>l</sub></em><sub> </sub>can be distinguished as: <em>δ<sub>s</sub></em> <em>l</em> = 0 and <em>δ<sub>p</sub></em> <em>l</em> = 1. On the theoretical part, it is possible to have an analytical expression for these quantum defects <em>δ<sub>l</sub></em>. A second code gives the correct wave functions modified by the quantum defects <em>δ<sub>l</sub></em> with the condition for the principal number: <em>n</em><sub><span style="white-space:nowrap;"><span style="white-space:nowrap;">*</span></span></sub> = <em>n</em> – <em>δ</em><sub><em>l</em></sub> ≥ 1. It is well known that <em>δ</em><sub><em>l</em></sub> → 0 when the kinetic momentum <em>l</em> ≥ 4, and for such momenta the spectra turns out to be hydrogenic. Modern software such as Mathematica, allows us to efficiently generate the polynomes defining wave functions with fractional quantum numbers. This leads to a good theoretical representation of these wave functions. To get numerically the quantum defects, a simple code is given to obtain these quantities when the levels assigned to a transition are known. Then, the quantum defects are inserted into the arguments of the correct modified wave functions for the outer electron of an atom or ion undergoing the short range polarization potential.展开更多
Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better...Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the star.Arguments are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.展开更多
This study represents a continuation of the Florida hotspot of tadpole abnormality found in the Southwest Florida suburban roadside drainage ditches in 2012 to determine if the adult frogs and toads frequenting the st...This study represents a continuation of the Florida hotspot of tadpole abnormality found in the Southwest Florida suburban roadside drainage ditches in 2012 to determine if the adult frogs and toads frequenting the study sites were anatomically abnormal.The gross examination of all organs included 397 adult anurans and 40 metamorphs representing five anuran species:Osteopilus septentrionalis(N=364),Rhinella marina(N=60),Lithobates sphenocephala(N=7),Anaxyrus terrestris(N=5)and Anaxyrus americanus(N=1).The gonads,liver,kidney and intestines were abnormal at a frequency of 87.4%.The few normal anurans(12.6%)were females and young male adults.We found a significant difference in organ abnormality type and f requency between sexes.Almost all f rog and toad males had testicular abnormality(92%)with only 6%with normal testes,whereas the female gonad abnormality was lower,at 41.6%.Hermaphroditism was found in both sexes at a frequency of 26.2%.The toads had a significantly higher frequency of hermaphroditism than the frogs.The toad hermaphroditism frequency was found to be 40%,whereas the frog hermaphroditism 23.3%.A hermaphrodite Cane toad male with a female phenotype coexisted with the normal male phenotype hermaphrodite.The fertility of 27 in situ pairs was assessed.The fertile testicular abnormal male and hermaphrodite pairs produced offspring with abnormal larval morphology.This information adds new evidence of the effect of chemicals on wild populations and the effect on non-target species which has always been underestimated.展开更多
Using a modified R-matrix code, the fine-structure-resolved partial photoionization cross sections of excited Na （Z = 11） are calculated within the Breit-Pauli approximation. Our calculated energy levels of Na＋ and...Using a modified R-matrix code, the fine-structure-resolved partial photoionization cross sections of excited Na （Z = 11） are calculated within the Breit-Pauli approximation. Our calculated energy levels of Na＋ and Na are in good agreement with the experimental values within 1% and the branching ratios of the J-resolved partial cross sections are consistent with the recent measurements within the experimental uncertainties. The agreements are impossible to be obtained without adequately taking into account the relativistic effects and the electron correlations together. Therefore, even for the intermediate-Z elements （e.g. Na with Z = 11）, the relativistic effects （mainly the spin-orbit interactions） should not be neglected.展开更多
Imaging studies with the Very Large Array（VLA） have revealed H I emission associated with the extended circumstellar shells of red giants. We analyze the spectral map obtained on Y CVn, a J-type carbon star on the A...Imaging studies with the Very Large Array（VLA） have revealed H I emission associated with the extended circumstellar shells of red giants. We analyze the spectral map obtained on Y CVn, a J-type carbon star on the Asymptotic Giant Branch. The H I line profiles can be interpreted with a model of a detached shell resulting from the interaction of a stellar outflow with the local interstellar medium.We reproduce the spectral map by introducing a distortion along a direction corresponding to the star＇s motion in space. We then use this fitting to simulate observations expected from the Five-hundred-meter Aperture Spherical radio Telescope（FAST）, and discuss its potential for improving our description of the outer regions of circumstellar shells.展开更多
By simple arguments, it is shown how alkaline types of atoms can be seen in dense molecular clouds depending on the average temperature of such regions of the Universe. This paper predicts infrared lines of such atoms...By simple arguments, it is shown how alkaline types of atoms can be seen in dense molecular clouds depending on the average temperature of such regions of the Universe. This paper predicts infrared lines of such atoms that could be seen in molecular clouds. The theory is developed in the first part and the predicted experimental results will follow. It results that the alkaline atoms modelized using the short-range polarization potential are found in quantum states <em>n</em><sub>*</sub> > 2.展开更多
This paper concerns the full interaction of a flux of photons onto any metal whose extraction potential is known. The photons are described with a full wavefunction, including all states of polarization, and the eject...This paper concerns the full interaction of a flux of photons onto any metal whose extraction potential is known. The photons are described with a full wavefunction, including all states of polarization, and the ejected electrons are considered with their two spin states. The purpose is to give a full theoretical description of the interaction of the photoelectric effect, known since a long time, it verifies that the electron of any peculiar metal can escape if a threshold is met. These wavelengths are accessible for many metals, the photoelectrons exist if the condition: . U<sub>0</sub> is the extraction potential given in eV, these are tabulated. The system wavefunction (electron + photon) a product of the electron free wave and of the photon, taken as , is defined, and the total Ψ(t) is truncated as required by the condition . It is possible to use any combination of polarization states for the photon, with at maximum a mixture of all possible polarizations, which is linear and right and left circular. The method applied takes into account the basic electron photon interaction, the free electron, which is the ejected electron, is described by a free wave, restricted to the first momenta. The quantum theory of the interaction needs to evaluate the integrals: , where r<sub>max</sub> is a cut-off parameter to insert to enable finite values of these integrals. The I is calculated on the variables r, θ, φ, and the r<sup>3</sup> concerns the radial volume multiplied by the r coming from the dipolar interaction. It follows that using the Fermi golden rule leads to an estimate of the probability of escape of an electron P<sub>ij</sub>, assuming that the normalisation factor of the A the electomagnetic vector is . The results for copper metal are given, the probabilty of escape, P<sub>ij</sub> has the correct dimension .展开更多
We present a phenomenological study of CO（1-0） and CO（2-1） emission from the circumstellar envelope （CSE） of the Asymptotic Giant Branch （AGB） star RS Cnc. It reveals departures from central symmetry that turn...We present a phenomenological study of CO（1-0） and CO（2-1） emission from the circumstellar envelope （CSE） of the Asymptotic Giant Branch （AGB） star RS Cnc. It reveals departures from central symmetry that turn out to be efficient tools for the exploration of some of the properties of the CSE. We use a wind model including a bipolar flow with a typical wind velocity of ～8 km s^-1 that decreases to ～2 km s^-1 near the equator. This wind model is used to describe Doppler velocity spectral maps obtained by merging data collected at the IRAM Plateau de Bure Interferometer and Pico Veleta single dish radio telescope. Parameters describing the wind morphology and kinematics are obtained, together with the radial dependence of the gas temperature in the domain of the CSE probed by the CO observations. Significant north-south central asymmetries are revealed by the analysis, which we quantify using a simple phenomenological description. The origin of such asymmetries is unclear.展开更多
The aim of this work was the assessment of the removal of air pollutants from mobile sources by commercial carbon nanotubes (CNTs). For this, the nanomaterial was characterized by different techniques: SEM, EDS, TEM, ...The aim of this work was the assessment of the removal of air pollutants from mobile sources by commercial carbon nanotubes (CNTs). For this, the nanomaterial was characterized by different techniques: SEM, EDS, TEM, XRD, BET, and Raman. Subsequently, the CNTs were packed in a stainless steel filters which was designed from different prototypes that were developed during the investigation. Tests were performed in the TO-913 Verificenter Macrover Auto SAQ. Inc. de CV. The results revealed that particle type sand CNTs loading had greater effects on the efficiencies than the membrane type sand pore sizes tested. When collecting NOx, the efficiencies were observed relatively lower, below 20% for loadings of 0.3 - 1.5 mg/cm2. The studied CNTs were multi-walled: two layers, show a nonlinear growth and morphology varied since they are of different diameters and longitudes, it was observed that half of the nanotubes were coated with amorphous carbon. The composition is mainly carbon and oxygen, iron is also present. The adsorption capacity of CNTs was significantly influenced by the different aspects, like model, brand, fuel, year and the conditions of each car. The removal efficiencies of CNTs filters were shown to range from 10% to 95% in average for the CNTs loadings of 0.2 - 1.6 mg/cm2. When collecting CO, CO2, NOx, HC, the efficiencies were shown to range from 5% to 60% given similar CNTs loadings used.展开更多
A survey for Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV) and White Spot Syndrome Virus (WSSV) was performed during two catching seasons of native shrimps in the Yucatan Coast in the Gulf of Mexico....A survey for Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV) and White Spot Syndrome Virus (WSSV) was performed during two catching seasons of native shrimps in the Yucatan Coast in the Gulf of Mexico. The mtDNA COI barcode identified two endemic species;the southern pink shrimp Penaeus notialis (Pérez Fantante, 1967) and the northern pink shrimp Penaeus brasiliensis (Latreille, 1987) (previously described as Farfantepenaeus brasiliensis). The prevalence of IHHNV was of 18.18% in 2016, and of 8.57% in 2017. All organisms tested negative for WSSV. This is the first identification of wild shrimps in the state of Yucatan Mexico by mtDNA COI barcode as well as the first identification of IHHNV in such species. The presence of IHHNV in wild shrimps populations has a potential of persisting in the coast of Yucatan with putative detrimental effect on local fisheries because once established in natural waters and hosts;such pathogens are almost impossible to eradicate.展开更多
We present the results of the first commissioning phase of the short-focal-length area of the Apollon laser facility(located in Saclay,France),which was performed with the first available laser beam(F2),scaled to a no...We present the results of the first commissioning phase of the short-focal-length area of the Apollon laser facility(located in Saclay,France),which was performed with the first available laser beam(F2),scaled to a nominal power of 1 PW.Under the conditions that were tested,this beam delivered on-target pulses of 10 J average energy and 24 fs duration.Several diagnostics were fielded to assess the performance of the facility.The on-target focal spot and its spatial stability,the temporal intensity profile prior to the main pulse,and the resulting density gradient formed at the irradiated side of solid targets have been thoroughly characterized,with the goal of helping users design future experiments.Emissions of energetic electrons,ions,and electromagnetic radiation were recorded,showing good laser-to-target coupling efficiency and an overall performance comparable to that of similar international facilities.This will be followed in 2022 by a further commissioning stage at the multipetawatt level.展开更多
The constraints on the number of neutrinos generations, g'1 coupling and Z?- Z′ mixing angle through the invisible width method, and in the framework of a U(1)B-L model are obtained. Based on the experimental val...The constraints on the number of neutrinos generations, g'1 coupling and Z?- Z′ mixing angle through the invisible width method, and in the framework of a U(1)B-L model are obtained. Based on the experimental value reported by the LEP for the rate , we obtained a bound on the g'1 coupling, . In addition, we derive 90% C.L. bounds on the Z?- Z′ mixing angle , improving the existing bounds by one order of magnitude.展开更多
Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of nonthermal particles and high-energy radiation.In the absence of particle collisions in the system,theory shows that t...Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of nonthermal particles and high-energy radiation.In the absence of particle collisions in the system,theory shows that the interaction of an expanding plasma with a pre-existing electromagnetic structure(as in our case)is able to induce energy dissipation and allow shock formation.Shock formation can alternatively take place when two plasmas interact,through microscopic instabilities inducing electromagnetic fields that are able in turn to mediate energy dissipation and shock formation.Using our platform in which we couple a rapidly expanding plasma induced by high-power lasers(JLF/Titan at LLNL and LULI2000)with high-strength magnetic fields,we have investigated the generation of a magnetized collisionless shock and the associated particle energization.We have characterized the shock as being collisionless and supercritical.We report here on measurements of the plasma density and temperature,the electromagnetic field structures,and the particle energization in the experiments,under various conditions of ambient plasma and magnetic field.We have also modeled the formation of the shocks using macroscopic hydrodynamic simulations and the associated particle acceleration using kinetic particle-in-cell simulations.As a companion paper to Yao et al.[Nat.Phys.17,1177–1182(2021)],here we show additional results of the experiments and simulations,providing more information to allow their reproduction and to demonstrate the robustness of our interpretation of the proton energization mechanism as being shock surfing acceleration.展开更多
Magnetized laser-produced plasmas are central to many studies in laboratory astrophysics,in inertial confinement fusion,and in industrial applications.Here,we present the results of large-scale three-dimensional magne...Magnetized laser-produced plasmas are central to many studies in laboratory astrophysics,in inertial confinement fusion,and in industrial applications.Here,we present the results of large-scale three-dimensional magnetohydrodynamic simulations of the dynamics of a laser-produced plasma expanding into a transverse magnetic field with a strength of tens of teslas.The simulations show the plasma being confined by the strong magnetic field into a slender slab structured by the magnetized Rayleigh–Taylor instability that develops at the plasma–vacuum interface.We find that when the initial velocity of the plume is perturbed,the slab can develop kink-like motions that disrupt its propagation.展开更多
The aim of this work was to obtain the physicochemical properties by SEM, XRD, FTIR analyses and the surface characteristics from carbonate outcrops cores such as pore diameter, surface area, porosity and permeability...The aim of this work was to obtain the physicochemical properties by SEM, XRD, FTIR analyses and the surface characteristics from carbonate outcrops cores such as pore diameter, surface area, porosity and permeability. The methods used to characterize them were Scanning Electron Microscopy, SEM;X Ray Diffraction, DRX;Fourier Transform Infrared Spectroscopy, FTIR. The porosity and permeability of natural vuggy fractured porous medium from core samples was determined obtained in the laboratory with conventional procedures. The cores have smooth and rough surfaces with porous with several sizes. Some crystals appear in preferential zones mainly composed by calcium, carbon and oxygen. Apparently into free spaces were found the organic materials, organic residues of crude oil. The cores have smooth and rough surfaces with porous with several sizes. Some crystals appear in preferential zones composed by calcium, carbon and oxygen. Apparently into free spaces were found the organic materials, organic residues of crude oil. The main inorganic compound in cores is calcite, (CaCO3). The porosity was for porous core 26% and for solid core 8.5%. The values obtained show that the cores have permeability where the fluid migrates through the particles at 2.23 × 10-4 cm/s.展开更多
Organic agriculture is increasingly used as an alternative to conventional agriculture due to its positive impact on the health of ecosystems and agroecosystems. However, the outcome of organic agriculture in terms of...Organic agriculture is increasingly used as an alternative to conventional agriculture due to its positive impact on the health of ecosystems and agroecosystems. However, the outcome of organic agriculture in terms of the production of various crops remains uncertain due to the influence of many variables, rising questions about its advantages over conventional agriculture. This study assessed the impacts of organic agricultural system on arbuscular mycorrhizal (AM) fungi diversity in soil and green tomato (Physalis ixocarpa Brot. ex Horn) crop production. A field experiment was conducted using a random block design with five repetitions of the following treatments: a) Control (no fertilization, NF);b) Vermicompost use (OTV);c) OTV with vermicompost leaching (OTH);and d) Inorganic fertilization (CST). Throughout the crop cycle, soil samples were analyzed chemically, the relative growth rate (RGR) of the plants was measured, and the colonization and diversity of AM fungi were quantified in roots and soil;finally, above-ground, root biomass, and fruit production were measured. Organic fertilization (OTV, OTH) increased (p p > 0.05). It is concluded that organic agriculture management is essential to promote a greater AM fungi diversity and fungi root colonization. Plant-AM fungi interaction increases growth rates and it allows a similar tomato production compared with conventional agriculture.展开更多
文摘The aim of this work was to carry out monitoring of some elements considered toxic in sediments from Lerma River. An analytical method was optimized in our laboratory for quantification of nickel (Ni), cobalt (Co), manganese (Mn), arsenic (As), chromium (Cr) and lead (Pb) by using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Ten sediments were collected along the Lerma River at variable distances and at 20 cm depth. Samples were heated to 60°C to dryness, followed by separation of particle size using a 74-μ No. 200 mesh for homogeneity purposes. 0.2 g of sample underwent microwave-assisted acid digestion, followed by plate evaporation. The samples were dissolved in 10 mL with HNO3 at 5% v/v for ICP-OES analysis. A certified reference material (CRM 8704) was used to evaluate the method’s accuracy and precision. The method showed linearity, precision, accuracy, and limits of quantification and detection acceptable for protocol validation of analytical method. The average results obtained in recovery of CRM 8704 were ~90% and precision was below 7% for all elements. Levels concentration of As, Cr, Pb show high pollution in A1, A7 and A8 sites. Therefore, Co, Mn and Ni can be considered in this study as normal values. In conclusion, concentration levels of As, Cr, Pb in sediments were high according to US-EPA and NOM-147-SEMARNAT/SSA1-2004. The presence of these heavy metals in Lerma River could be due mainly for the emitted from industries, such as pharmaceutical, automotive, metal mechanics and tannery, and urban residual water. Finally, the method developed using ICP-OES has enabled monitoring of these elements in sediments from Lerma River, with possible applications in a routine analytical laboratory.
基金supported by the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant Agreement No.787539)funding from EPRSC(Grant Nos.EP/E035728,EP/C003586,and EP/P010059/1)supported by the National Sciences and Engineering Research Council of Canada(NSERC)and Compute Canada(Job:pve-323-ac,PA).
文摘Realizing the full potential of ultrahigh-intensity lasers for particle and radiation generation will require multi-beam arrangements due to technology limitations.Here,we investigate how to optimize their coupling with solid targets.Experimentally,we show that overlapping two intense lasers in a mirror-like configuration onto a solid with a large preplasma can greatly improve the generation of hot electrons at the target front and ion acceleration at the target backside.The underlying mechanisms are analyzed through multidimensional particle-in-cell simulations,revealing that the self-induced magnetic fields driven by the two laser beams at the target front are susceptible to reconnection,which is one possible mechanism to boost electron energization.In addition,the resistive magnetic field generated during the transport of the hot electrons in the target bulk tends to improve their collimation.Our simulations also indicate that such effects can be further enhanced by overlapping more than two laser beams.
基金supported in part by the CNRST Morocco,the Volkswagen Foundation:Grant number I/79315Hydromed project
文摘In the present work, we investigate the inverse problem of reconstructing the parameter of an integro-differential parabolic equation, which comes from pollution problems in porous media, when the final observation is given. We use the optimal control framework to establish both the existence and necessary condition of the minimizer for the cost func- tional. Furthermore, we prove the stability and the local uniqueness of the minimizer. Some numerical results will be presented and discussed.
基金X-ray data measurement,modeling and analysis were made by the JIHT RAS team with financial support from the Russian Science Foundation(Project No.17-72-20272)The authors thank the entire staff of the ELFIE laser facility at LULI for their support during the experimental preparation and execution.This work was supported by ANR Blanc Grant No.12-BS09-025-01 SILAMPA and has received funding from the European Union’s Horizon 2020 research and innovation program through the European Research Council(ERC,Grant Agreement No.787539)Some work was done within the LABEX Plas@Par project,which is supported by Grant No.11-IDEX-0004-02 from Agence Nationale de la Recherche.The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase I,a project co-financed by the Romanian Government and European Union through the European Regional Development Fund.This work was performed under the auspices of the U.S.Department of Energy by Lawrence Livermore National Laboratory under Contract No.DE-AC52-07NA27344.
文摘Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star formation.In particular,we have recently demonstrated the possibility of simulating in the laboratory the process of the accretion of matter on young stars[G.Revet et al.,Sci.Adv.3,e1700982(2017)].The present paper focuses on x-ray spectroscopy methods that allow us to investigate the complex plasma hydrodynamics involved in such experiments.We demonstrate that we can infer the formation of a plasma shell,surrounding the accretion column at the location of impact with the stellar surface,and thus resolve the present discrepancies between mass accretion rates derived from x-ray and optical-radiation astronomical observations originating from the same object.In our experiments,the accretion column ismodeled by having a collimated narrow(1 mm diameter)plasma stream first propagate along the lines of a large-scale external magnetic field and then impact onto an obstacle,mimicking the high-density region of the stellar chromosphere.A combined approach using steady-state and quasi-stationarymodels was successfully applied tomeasure the parameters of the plasma all along its propagation,at the impact site,and in the structure surrounding the impact region.The formation of a hot plasma shell,surrounding the denser and colder core,formed by the incoming stream of matter is observed near the obstacle using x-ray spatially resolved spectroscopy.
文摘The effects of the polarization potential serve to model spectra of alkaline atoms. These effects have been known for a long time and notably explained by the physicist Max Born (1926). The experimental knowledge of these alkaline spectra enables us to specify the values of these quantum defects. A simple code is used to calculate two quantum defects for which <em>δ<sub>l</sub></em><sub> </sub>can be distinguished as: <em>δ<sub>s</sub></em> <em>l</em> = 0 and <em>δ<sub>p</sub></em> <em>l</em> = 1. On the theoretical part, it is possible to have an analytical expression for these quantum defects <em>δ<sub>l</sub></em>. A second code gives the correct wave functions modified by the quantum defects <em>δ<sub>l</sub></em> with the condition for the principal number: <em>n</em><sub><span style="white-space:nowrap;"><span style="white-space:nowrap;">*</span></span></sub> = <em>n</em> – <em>δ</em><sub><em>l</em></sub> ≥ 1. It is well known that <em>δ</em><sub><em>l</em></sub> → 0 when the kinetic momentum <em>l</em> ≥ 4, and for such momenta the spectra turns out to be hydrogenic. Modern software such as Mathematica, allows us to efficiently generate the polynomes defining wave functions with fractional quantum numbers. This leads to a good theoretical representation of these wave functions. To get numerically the quantum defects, a simple code is given to obtain these quantities when the levels assigned to a transition are known. Then, the quantum defects are inserted into the arguments of the correct modified wave functions for the outer electron of an atom or ion undergoing the short range polarization potential.
基金supported by the Programme National "Physique et Chimie du MilieuInterstellaire" (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNESfinancial support from VNSC/VAST+4 种基金the NAFOSTED funding agency under grant number 103.99–2015.39the World Laboratorythe Odon Vallet Foundationthe Rencontres du Viet Namfunded by Graduate University of Science and Technology undergrant number GUST.STS.DT 2017-VL01
文摘Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the star.Arguments are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.
文摘This study represents a continuation of the Florida hotspot of tadpole abnormality found in the Southwest Florida suburban roadside drainage ditches in 2012 to determine if the adult frogs and toads frequenting the study sites were anatomically abnormal.The gross examination of all organs included 397 adult anurans and 40 metamorphs representing five anuran species:Osteopilus septentrionalis(N=364),Rhinella marina(N=60),Lithobates sphenocephala(N=7),Anaxyrus terrestris(N=5)and Anaxyrus americanus(N=1).The gonads,liver,kidney and intestines were abnormal at a frequency of 87.4%.The few normal anurans(12.6%)were females and young male adults.We found a significant difference in organ abnormality type and f requency between sexes.Almost all f rog and toad males had testicular abnormality(92%)with only 6%with normal testes,whereas the female gonad abnormality was lower,at 41.6%.Hermaphroditism was found in both sexes at a frequency of 26.2%.The toads had a significantly higher frequency of hermaphroditism than the frogs.The toad hermaphroditism frequency was found to be 40%,whereas the frog hermaphroditism 23.3%.A hermaphrodite Cane toad male with a female phenotype coexisted with the normal male phenotype hermaphrodite.The fertility of 27 in situ pairs was assessed.The fertile testicular abnormal male and hermaphrodite pairs produced offspring with abnormal larval morphology.This information adds new evidence of the effect of chemicals on wild populations and the effect on non-target species which has always been underestimated.
基金Supported by This work is supported by the Ministry of Science and Technology and Ministry of Education of China, the Key Project of the Ministry of Education of China （N0 306020）, the National Natural Science Foundation of China, the National High- Tech ICF Committee in China and the Yin-He Super-computer Center, Institute of Applied Physics and Mathematics, Beijing, China, and the National Basic Research Programme of China under Grant No 2006CB921408.
文摘Using a modified R-matrix code, the fine-structure-resolved partial photoionization cross sections of excited Na （Z = 11） are calculated within the Breit-Pauli approximation. Our calculated energy levels of Na＋ and Na are in good agreement with the experimental values within 1% and the branching ratios of the J-resolved partial cross sections are consistent with the recent measurements within the experimental uncertainties. The agreements are impossible to be obtained without adequately taking into account the relativistic effects and the electron correlations together. Therefore, even for the intermediate-Z elements （e.g. Na with Z = 11）, the relativistic effects （mainly the spin-orbit interactions） should not be neglected.
基金the Vietnam National Satellite Centre(VNSC/VAST)the NAFOSTED funding agency+3 种基金the World Laboratorythe Odon Vallet Foundationthe Rencontres du Viet Namthe PCMI programme of the CNRS for financial support
文摘Imaging studies with the Very Large Array（VLA） have revealed H I emission associated with the extended circumstellar shells of red giants. We analyze the spectral map obtained on Y CVn, a J-type carbon star on the Asymptotic Giant Branch. The H I line profiles can be interpreted with a model of a detached shell resulting from the interaction of a stellar outflow with the local interstellar medium.We reproduce the spectral map by introducing a distortion along a direction corresponding to the star＇s motion in space. We then use this fitting to simulate observations expected from the Five-hundred-meter Aperture Spherical radio Telescope（FAST）, and discuss its potential for improving our description of the outer regions of circumstellar shells.
文摘By simple arguments, it is shown how alkaline types of atoms can be seen in dense molecular clouds depending on the average temperature of such regions of the Universe. This paper predicts infrared lines of such atoms that could be seen in molecular clouds. The theory is developed in the first part and the predicted experimental results will follow. It results that the alkaline atoms modelized using the short-range polarization potential are found in quantum states <em>n</em><sub>*</sub> > 2.
文摘This paper concerns the full interaction of a flux of photons onto any metal whose extraction potential is known. The photons are described with a full wavefunction, including all states of polarization, and the ejected electrons are considered with their two spin states. The purpose is to give a full theoretical description of the interaction of the photoelectric effect, known since a long time, it verifies that the electron of any peculiar metal can escape if a threshold is met. These wavelengths are accessible for many metals, the photoelectrons exist if the condition: . U<sub>0</sub> is the extraction potential given in eV, these are tabulated. The system wavefunction (electron + photon) a product of the electron free wave and of the photon, taken as , is defined, and the total Ψ(t) is truncated as required by the condition . It is possible to use any combination of polarization states for the photon, with at maximum a mixture of all possible polarizations, which is linear and right and left circular. The method applied takes into account the basic electron photon interaction, the free electron, which is the ejected electron, is described by a free wave, restricted to the first momenta. The quantum theory of the interaction needs to evaluate the integrals: , where r<sub>max</sub> is a cut-off parameter to insert to enable finite values of these integrals. The I is calculated on the variables r, θ, φ, and the r<sup>3</sup> concerns the radial volume multiplied by the r coming from the dipolar interaction. It follows that using the Fermi golden rule leads to an estimate of the probability of escape of an electron P<sub>ij</sub>, assuming that the normalisation factor of the A the electomagnetic vector is . The results for copper metal are given, the probabilty of escape, P<sub>ij</sub> has the correct dimension .
基金supported by INSU/CNRS(France),MPG(Germany)and IGN(Spain)
文摘We present a phenomenological study of CO（1-0） and CO（2-1） emission from the circumstellar envelope （CSE） of the Asymptotic Giant Branch （AGB） star RS Cnc. It reveals departures from central symmetry that turn out to be efficient tools for the exploration of some of the properties of the CSE. We use a wind model including a bipolar flow with a typical wind velocity of ～8 km s^-1 that decreases to ～2 km s^-1 near the equator. This wind model is used to describe Doppler velocity spectral maps obtained by merging data collected at the IRAM Plateau de Bure Interferometer and Pico Veleta single dish radio telescope. Parameters describing the wind morphology and kinematics are obtained, together with the radial dependence of the gas temperature in the domain of the CSE probed by the CO observations. Significant north-south central asymmetries are revealed by the analysis, which we quantify using a simple phenomenological description. The origin of such asymmetries is unclear.
文摘The aim of this work was the assessment of the removal of air pollutants from mobile sources by commercial carbon nanotubes (CNTs). For this, the nanomaterial was characterized by different techniques: SEM, EDS, TEM, XRD, BET, and Raman. Subsequently, the CNTs were packed in a stainless steel filters which was designed from different prototypes that were developed during the investigation. Tests were performed in the TO-913 Verificenter Macrover Auto SAQ. Inc. de CV. The results revealed that particle type sand CNTs loading had greater effects on the efficiencies than the membrane type sand pore sizes tested. When collecting NOx, the efficiencies were observed relatively lower, below 20% for loadings of 0.3 - 1.5 mg/cm2. The studied CNTs were multi-walled: two layers, show a nonlinear growth and morphology varied since they are of different diameters and longitudes, it was observed that half of the nanotubes were coated with amorphous carbon. The composition is mainly carbon and oxygen, iron is also present. The adsorption capacity of CNTs was significantly influenced by the different aspects, like model, brand, fuel, year and the conditions of each car. The removal efficiencies of CNTs filters were shown to range from 10% to 95% in average for the CNTs loadings of 0.2 - 1.6 mg/cm2. When collecting CO, CO2, NOx, HC, the efficiencies were shown to range from 5% to 60% given similar CNTs loadings used.
文摘A survey for Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV) and White Spot Syndrome Virus (WSSV) was performed during two catching seasons of native shrimps in the Yucatan Coast in the Gulf of Mexico. The mtDNA COI barcode identified two endemic species;the southern pink shrimp Penaeus notialis (Pérez Fantante, 1967) and the northern pink shrimp Penaeus brasiliensis (Latreille, 1987) (previously described as Farfantepenaeus brasiliensis). The prevalence of IHHNV was of 18.18% in 2016, and of 8.57% in 2017. All organisms tested negative for WSSV. This is the first identification of wild shrimps in the state of Yucatan Mexico by mtDNA COI barcode as well as the first identification of IHHNV in such species. The presence of IHHNV in wild shrimps populations has a potential of persisting in the coast of Yucatan with putative detrimental effect on local fisheries because once established in natural waters and hosts;such pathogens are almost impossible to eradicate.
基金The authors acknowledge the facility and the technical assistance of the national research infrastructureApollon.The authorswould also like to thank all teams of the laboratories that contributed to the success of the facility,i.e.,all of theCILEXconsortium,whichwas established to buildApollon.Thisworkwas supported by funding fromthe European Research Council(ERC)under the European Unions Horizon 2020 research and innovation program(Grant Agreement No.787539,Project GENESIS),and by Grant No.ANR-17-CE30-0026-Pinnacle from the Agence Nationale de la Recherche.We acknowledge,in the framework of ProjectGENESIS,the support provided by Extreme Light InfrastructureNuclear Physics(ELI-NP)Phase II,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund,and by the Project No.ELI-RO-2020-23,funded by IFA(Romania)to design,build,and test the neutron detectors used in this project,as well as parts of the OTR diagnostic.JIHT RAS team members are supported by the Ministry of Science and Higher Education of the Russian Federation(State Assignment No.075-00460-21-00)The study reported here was also funded by the Russian Foundation for Basic Research,Project No.20-02-00790.The work of the ENEA team members has been carried out within the framework of the EUROfusionConsortiumand has received funding from the Euratom research and training program 2014–2018 and 2019-2020 under grant agreement No.633053.
文摘We present the results of the first commissioning phase of the short-focal-length area of the Apollon laser facility(located in Saclay,France),which was performed with the first available laser beam(F2),scaled to a nominal power of 1 PW.Under the conditions that were tested,this beam delivered on-target pulses of 10 J average energy and 24 fs duration.Several diagnostics were fielded to assess the performance of the facility.The on-target focal spot and its spatial stability,the temporal intensity profile prior to the main pulse,and the resulting density gradient formed at the irradiated side of solid targets have been thoroughly characterized,with the goal of helping users design future experiments.Emissions of energetic electrons,ions,and electromagnetic radiation were recorded,showing good laser-to-target coupling efficiency and an overall performance comparable to that of similar international facilities.This will be followed in 2022 by a further commissioning stage at the multipetawatt level.
文摘The constraints on the number of neutrinos generations, g'1 coupling and Z?- Z′ mixing angle through the invisible width method, and in the framework of a U(1)B-L model are obtained. Based on the experimental value reported by the LEP for the rate , we obtained a bound on the g'1 coupling, . In addition, we derive 90% C.L. bounds on the Z?- Z′ mixing angle , improving the existing bounds by one order of magnitude.
基金supported by funding from the European Research Council(ERC)under the European Unions Horizon 2020 research and innovation program(Grant Agreement No.787539)The computational resources of this work were supported by the National Sciences and Engineering Research Council of Canada(NSERC)and Compute Canada(Job Grant No.pve-323-ac)+4 种基金Part of the experimental system is covered by a patent(No.1000183285,2013,INPI-France)The FLASH software used was developed,in part,by the DOE NNSA ASC-and the DOE Office of Science ASCR-supported Flash Center for Computational Science at the University of ChicagoWe thank J.L.Dubois for providing us EOS and opacities.The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase II,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund,and by the Project No.ELIRO-2020-23 funded by IFA(Romania)IHT RAS team members are supported by the Ministry of Science and Higher Education of the Russian Federation(State Assignment No.075-00460-21-00)The study reported here was funded by the Russian Foundation for Basic Research,Project No.19-32-60008.
文摘Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of nonthermal particles and high-energy radiation.In the absence of particle collisions in the system,theory shows that the interaction of an expanding plasma with a pre-existing electromagnetic structure(as in our case)is able to induce energy dissipation and allow shock formation.Shock formation can alternatively take place when two plasmas interact,through microscopic instabilities inducing electromagnetic fields that are able in turn to mediate energy dissipation and shock formation.Using our platform in which we couple a rapidly expanding plasma induced by high-power lasers(JLF/Titan at LLNL and LULI2000)with high-strength magnetic fields,we have investigated the generation of a magnetized collisionless shock and the associated particle energization.We have characterized the shock as being collisionless and supercritical.We report here on measurements of the plasma density and temperature,the electromagnetic field structures,and the particle energization in the experiments,under various conditions of ambient plasma and magnetic field.We have also modeled the formation of the shocks using macroscopic hydrodynamic simulations and the associated particle acceleration using kinetic particle-in-cell simulations.As a companion paper to Yao et al.[Nat.Phys.17,1177–1182(2021)],here we show additional results of the experiments and simulations,providing more information to allow their reproduction and to demonstrate the robustness of our interpretation of the proton energization mechanism as being shock surfing acceleration.
基金This work was supported by funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant Agreement No.787539)The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase II a project co-financed by the Romanian Government and European Union through the European Regional Development Fund+1 种基金the Project No.ELI-RO-2020-23 funded by IFA(Romania)This work was also granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip at Meso(Reference No.ANR-10-EQPX-29-01)of the program Investissements d’Avenir supervised by the National Agency for Research.
文摘Magnetized laser-produced plasmas are central to many studies in laboratory astrophysics,in inertial confinement fusion,and in industrial applications.Here,we present the results of large-scale three-dimensional magnetohydrodynamic simulations of the dynamics of a laser-produced plasma expanding into a transverse magnetic field with a strength of tens of teslas.The simulations show the plasma being confined by the strong magnetic field into a slender slab structured by the magnetized Rayleigh–Taylor instability that develops at the plasma–vacuum interface.We find that when the initial velocity of the plume is perturbed,the slab can develop kink-like motions that disrupt its propagation.
文摘The aim of this work was to obtain the physicochemical properties by SEM, XRD, FTIR analyses and the surface characteristics from carbonate outcrops cores such as pore diameter, surface area, porosity and permeability. The methods used to characterize them were Scanning Electron Microscopy, SEM;X Ray Diffraction, DRX;Fourier Transform Infrared Spectroscopy, FTIR. The porosity and permeability of natural vuggy fractured porous medium from core samples was determined obtained in the laboratory with conventional procedures. The cores have smooth and rough surfaces with porous with several sizes. Some crystals appear in preferential zones mainly composed by calcium, carbon and oxygen. Apparently into free spaces were found the organic materials, organic residues of crude oil. The cores have smooth and rough surfaces with porous with several sizes. Some crystals appear in preferential zones composed by calcium, carbon and oxygen. Apparently into free spaces were found the organic materials, organic residues of crude oil. The main inorganic compound in cores is calcite, (CaCO3). The porosity was for porous core 26% and for solid core 8.5%. The values obtained show that the cores have permeability where the fluid migrates through the particles at 2.23 × 10-4 cm/s.
文摘Organic agriculture is increasingly used as an alternative to conventional agriculture due to its positive impact on the health of ecosystems and agroecosystems. However, the outcome of organic agriculture in terms of the production of various crops remains uncertain due to the influence of many variables, rising questions about its advantages over conventional agriculture. This study assessed the impacts of organic agricultural system on arbuscular mycorrhizal (AM) fungi diversity in soil and green tomato (Physalis ixocarpa Brot. ex Horn) crop production. A field experiment was conducted using a random block design with five repetitions of the following treatments: a) Control (no fertilization, NF);b) Vermicompost use (OTV);c) OTV with vermicompost leaching (OTH);and d) Inorganic fertilization (CST). Throughout the crop cycle, soil samples were analyzed chemically, the relative growth rate (RGR) of the plants was measured, and the colonization and diversity of AM fungi were quantified in roots and soil;finally, above-ground, root biomass, and fruit production were measured. Organic fertilization (OTV, OTH) increased (p p > 0.05). It is concluded that organic agriculture management is essential to promote a greater AM fungi diversity and fungi root colonization. Plant-AM fungi interaction increases growth rates and it allows a similar tomato production compared with conventional agriculture.
