BACKGROUND Liver cancer is the fifth most common cancer and the second cause of cancerrelated deaths worldwide.Transarterial chemoembolization(TACE)is the best treatment of intermediate hepatocellular carcinoma(HCC).D...BACKGROUND Liver cancer is the fifth most common cancer and the second cause of cancerrelated deaths worldwide.Transarterial chemoembolization(TACE)is the best treatment of intermediate hepatocellular carcinoma(HCC).Doxorubicin is the most commonly used drug despite a low level of evidence.AIM To compare the objective response rate of idarubicin-based TACE(Ida-TACE)against doxorubicin-based TACE(Dox-TACE)in intermediate stage HCC.METHODS Between January 2012 and December 2014,all patients treated with TACE at our academic hospital were screened.Inclusion criteria were patients with Child-Pugh score A or B,a performance status below or equal to 1,and no prior TACE.Either lipiodol TACE or drug-eluting beads TACE could be performed with 10 mg of idarubicin or 50 mg of doxorubicin.Each patient treated with idarubicin was matched with two doxorubicin-treated patients.The TACE response was assessed by independent radiologists according to the mRECIST criteria.RESULTS Sixty patients were treated with doxorubicin and thirty with idarubicin.There were 93%and 87%of cirrhotic patients and 87%and 70%of Child-Pugh A in the doxorubicin and idarubicin groups,respectively.The median number of HCC per patient was two in both groups with 31%and 26%of single nodules in doxorubicin and idarubicin groups,respectively.Objective response rate after first TACE was 76.7%and 73.3%(P=0.797)with 41.7%and 40.0%complete response in doxorubicin and idarubicin groups,respectively.Progression-free survival was 7.7 mo in both groups,and liver transplant-free survival was 24.9 mo and 21.9 mo in doxorubicin and idarubicin groups,respectively.Safety profiles were similar in both groups,with grade 3-4 adverse events in 35%of Dox-TACE and 43%of Ida-TACEs.CONCLUSION Ida-TACE and Dox-TACE showed comparable results in terms of efficacy and safety.Ida-TACE may represent an interesting alternative to Dox-TACE in the management of patients with intermediate stage HCC.展开更多
Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of th...Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of the seismic wave velocity induced by changes in the groundwater level. Here we compare the seismic measurements with actual piezometric data acquired on the Crépieux-Charmy (Lyon, France) groundwater exploitation field. We show the excellent correspondance between variations in the groundwater level and seismic velocity variations. We present hereafter the time and space monitoring of an hydraulic dome formed to prevent biological and chemical pollutions to enter the exploitation field. The horizontal resolution is solely limited by the number of seismic stations used, and is about 30 m in the present study. The vertical resolution of seismic measurement is impaired by spurious artifacts linked to the intermittent sources of noise. In average, the sensitivity of the seismic velocity change corresponds to a 50 cm change of waterlevel. This study confirms the possibility of groundwater monitoring in an industrial context with ambient seismic noise.展开更多
Energy demand is increasing while we are facing a depletion of fossils fuels, the main source of energy production in the world. These last years, photovoltaic (PV) system technologies are growing rapidly among altern...Energy demand is increasing while we are facing a depletion of fossils fuels, the main source of energy production in the world. These last years, photovoltaic (PV) system technologies are growing rapidly among alternative sources of energy to contribute to mitigation of climate change. However, PV system efficiency researches operating under West African weather conditions are nascent. The first objective of this study is to investigate the sensitivity of common monocrystalline PV efficiency to local meteorological parameters (temperature, humidity, solar radiation) in two contrasted cities over West Africa: Niamey (Niger) in a Sahelian arid area and Abidjan (Cote d’Ivoire) in atropical humid area. The second objective is to quantify the effect of dust accumulation on PV efficiency in Niamey (Niger). The preliminary results show that PV efficiency is more sensitive to high temperature change especially under Niamey climate conditions (warmer than Abidjan) where high ambient temperatures above 33°C lead to an important decrease of PV efficiency. Increase of relative humidity induces a decrease of PV efficiency in both areas (Niamey and Abidjan). A power loss up to 12.46% is observed in Niamey after 21 days of dust accumulation.展开更多
Cold stress is one of the major abiotic stress factors affecting rice growth and development,leading to significant yield loss in the context of global climate change.Exploring natural variants that confer cold resist...Cold stress is one of the major abiotic stress factors affecting rice growth and development,leading to significant yield loss in the context of global climate change.Exploring natural variants that confer cold resistance and the underlying molecular mechanism responsible for this is the major strategy to breed cold-tolerant rice varieties.Here,we show that natural variations of a SIMILAR to RCD ONE(SRO)gene,OsSRO1c,confer cold tolerance in rice at both seedling and booting stages.Our in vivo and in vitro experiments demonstrated that OsSRO1c possesses intrinsic liquid–liquid phase-separation ability and recruits OsDREB2B,an AP2/ERF transcription factor that functions as a positive regulator of cold stress,into its biomolecular condensates in the nucleus,resulting in elevated transcriptional activity of OsDREB2B.We found that the OsSRO1c-OsDREB2B complex directly responds to low temperature through dynamic phase transitions and regulates key cold-response genes,including COLD1.Furthermore,we showed that introgression of an elite haplotype of OsSRO1c into a cold-susceptible indica rice could significantly increase its cold resistance.Collectively,our work reveals a novel cold-tolerance regulatory module in rice and provides promising genetic targets for molecular breeding of cold-tolerant rice varieties.展开更多
Background:The wetlands used for some agricultural activities constitute productive breeding sites for many mosquito species.Thus,the agricultural use of insecticide targeting other pests may select for insecticide re...Background:The wetlands used for some agricultural activities constitute productive breeding sites for many mosquito species.Thus,the agricultural use of insecticide targeting other pests may select for insecticide resistance in malaria mosquitoes.The purpose of this study is to clarify some knowledge gaps on the role of agrochemicals in the development of insecticide resistance in malaria vectors is of utmost importance for vector control.Methods:Using the CDC bottle test and the log-probit analysis,we investigated for the first time the resistance levels ofAnopheles coluzzii mosquitoes to neonicotinoids,insecticides used exclusively for crop protection in C?te d’Ivoire.The study was conducted in two agricultural regions(Tiassale and Gagnoa)and one non-agricultural region(Vitre)between June and August 2017 using clothianidin,acetamiprid and imidacloprid.Results:Mosquito populations from Tiassale and Gagnoa(agricultural settings)were determined to be resistant to acetamiprid with mortality rates being<85%at 24 h post-exposure.In Vitre(non-agricultural area)however,the mosquito population was susceptible to acetamiprid.In all three localities,mosquito populations were resistant to imidacloprid(mortality rates were 60%in Vitre,37%in Tiassale,and 13%in Gagnoa)and completely susceptible to clothianidin(100%mortality).An.coluzzii represented 100%of mosquito collected in Gagnoa,86%in Tiassale and 96%in Vitre.Conclusions:This study provides strong evidence that agricultural use of insecticides can cause insecticide resistance in malaria vector populations.Insecticide resistance driven by agrochemical usage should be considered when vector control strategies are developed.展开更多
Natural illumination conditions are highly variable and because of their sessile life style, plants are forced to acclimate to them at the cellular and molecular level. Changes in light intensity or quality induce cha...Natural illumination conditions are highly variable and because of their sessile life style, plants are forced to acclimate to them at the cellular and molecular level. Changes in light intensity or quality induce changes in the reduction/oxidation (redox) state of the photosynthetic electron chain that acts as a trigger for compen- satory acclimation responses comprising functional and structural adjustments of photosynthesis and metabolism. Such responses include redox-controlled changes in plant gene expression in the nucleus and organelles. Here we describe a strategy for the identification of early redox-regulated genes (ERGs) in the nucleus of the model organism Arabidopsis thaliana that respond significantly 30 or 60 min after the generation of a reduction signal in the photosynthetic electron transport chain. By comparing the response of wild-type plants with that of the acclimation mutant stn7, we could specifically identify ERGs. The results reveal a significant impact of chloroplast redox signals on distinct nuclear gene groups including genes for the mitochondrial electron transport chain, tetrapyrrole biosynthesis, carbohydrate metabolism, and signaling lipid synthesis. These expression profiles are clearly different from those observed in response to the reduction of photosynthetic electron transport by high light treatments. Thus, the ERGs identified are unique to redox imbalances in photosynthetic electron transport and were then used for analyzing potential redox-responsive cis-elements, trans-factors, and chromosomal regulatory hot spots. The data identify a novel redox-responsive element and indicate extensive redox control at transcriptional and chromosomal levels that point to an unprecedented impact of redox signals on epigenetic processes.展开更多
Light emission of europium(Eu^(3+))ions placed in the vicinity of optically resonant nanoantennas is usually controlled by tailoring the local density of photon states(LDOS).We show that the polarization and shape of ...Light emission of europium(Eu^(3+))ions placed in the vicinity of optically resonant nanoantennas is usually controlled by tailoring the local density of photon states(LDOS).We show that the polarization and shape of the excitation beam can also be used to manipulate light emission,as azimuthally or radially polarized cylindrical vector beam offers to spatially shape the electric and magnetic fields,in addition to the effect of silicon nanorings(Si-NRs)used as nanoantennas.The photoluminescence(PL)mappings of the Eu^(3+)transitions and the Si phonon mappings are strongly dependent of both the excitation beam and the Si-NR dimensions.The experimental results of Raman scattering and photoluminescence are confirmed by numerical simulations of the near-field intensity in the Si nanoantenna and in the Eu^(3+)-doped film,respectively.The branching ratios obtained from the experimental PL maps also reveal a redistribution of the electric and magnetic emission channels.Our results show that it could be possible to spatially control both electric and magnetic dipolar emission of Eu^(3+)ions by switching the laser beam polarization,hence the near field at the excitation wavelength,and the electric and magnetic LDOS at the emission wavelength.This paves the way for optimized geometries taking advantage of both excitation and emission processes.展开更多
Optical parametric amplification(OPA)represents a powerful solution to achieve broadband amplification in wavelength ranges beyond the scope of conventional gain media,for generating high-power optical pulses,optical ...Optical parametric amplification(OPA)represents a powerful solution to achieve broadband amplification in wavelength ranges beyond the scope of conventional gain media,for generating high-power optical pulses,optical microcombs,entangled photon pairs and a wide range of other applications.Here,we demonstrate optical parametric amplifiers based on silicon nitride(Si3N4)waveguides integrated with two-dimensional(2D)layered graphene oxide(GO)films.We achieve precise control over the thickness,length,and position of the GO films using a transfer-free,layer-by-layer coating method combined with accurate window opening in the chip cladding using photolithography.Detailed OPA measurements with a pulsed pump for the fabricated devices with different GO film thicknesses and lengths show a maximum parametric gain of~24.0 dB,representing a~12.2 dB improvement relative to the device without GO.We perform a theoretical analysis of the device performance,achieving good agreement with experiment and showing that there is substantial room for further improvement.This work represents the first demonstration of integrating 2D materials on chips to enhance the OPA performance,providing a new way of achieving high performance photonic integrated OPA by incorporating 2D materials.展开更多
Voltage-controlled conductance and switching induced by single molecules or atoms are ideally studied in scanning tunneling microscope (STM) tunnel junctions. While the objects under consideration are mostly used in...Voltage-controlled conductance and switching induced by single molecules or atoms are ideally studied in scanning tunneling microscope (STM) tunnel junctions. While the objects under consideration are mostly used in their original form, little is known of the possibilities of in situ adjustments of their properties. Here, we evidence properties of a tunnel junction made of a Ce atom/cluster built by atomic manipulation on Au(111) at a temperature of 4.6 K in the presence of H2. The conductance through the object is characterized by a switching voltage corresponding to an opening or closing of an inelastic electron tunneling conductance channel at 50 mV for a Ce atom and 140 mV for a Ce cluster and by charging. We demonstrate that the electronic properties of an STM junction can be engineered in a simple way by in situ guiding of the H2 pinning at an atomic cluster.展开更多
Asymptotic expansions of the voltage potential in terms of the "radius" of a diametrically small(or several diametrically small) material inhomogeneity(ies) are by now quite well-known. Such asymptotic expan...Asymptotic expansions of the voltage potential in terms of the "radius" of a diametrically small(or several diametrically small) material inhomogeneity(ies) are by now quite well-known. Such asymptotic expansions for diametrically small inhomogeneities are uniform with respect to the conductivity of the inhomogeneities.In contrast, thin inhomogeneities, whose limit set is a smooth, codimension 1 manifold,σ, are examples of inhomogeneities for which the convergence to the background potential,or the standard expansion cannot be valid uniformly with respect to the conductivity, a, of the inhomogeneity. Indeed, by taking a close to 0 or to infinity, one obtains either a nearly homogeneous Neumann condition or nearly constant Dirichlet condition at the boundary of the inhomogeneity, and this difference in boundary condition is retained in the limit.The purpose of this paper is to find a "simple" replacement for the background potential, with the following properties:(1) This replacement may be(simply) calculated from the limiting domain Ω\σ, the boundary data on the boundary of Ω, and the right-hand side.(2) This replacement depends on the thickness of the inhomogeneity and the conductivity,a, through its boundary conditions on σ.(3) The difference between this replacement and the true voltage potential converges to 0 uniformly in a, as the inhomogeneity thickness tends to 0.展开更多
This paper concerns the reconstruction of a scalar coefficient of a second-order elliptic equation in divergence form posed on a bounded domain from internal data.This problem finds applications in multi-wave imaging,...This paper concerns the reconstruction of a scalar coefficient of a second-order elliptic equation in divergence form posed on a bounded domain from internal data.This problem finds applications in multi-wave imaging,greedy methods to approximate parameter-dependent elliptic problems,and image treatment with partial differential equations.We first show that the inverse problem for smooth coefficients can be rewritten as a linear transport equation.Assuming that the coefficient is known near the boundary,we study the well-posedness of associated transport equation as well as its numerical resolution using discontinuous Galerkin method.We propose a regularized transport equation that allow us to derive rigorous convergence rates of the numerical method in terms of the order of the polynomial approximation as well as the regularization parameter.We finally provide numerical examples for the inversion assuming a lower regularity of the coefficient,and using synthetic data.展开更多
With the aim of studying the effect of water dynamics on the properties of biological systems, in this paper, we present a quasi-elastic neutron scattering study on three different types of living cells, differing bot...With the aim of studying the effect of water dynamics on the properties of biological systems, in this paper, we present a quasi-elastic neutron scattering study on three different types of living cells, differing both in their morphological and tumor properties. The measured scattering signal, which essentially originates from hydrogen atoms present in the investigated systems, has been analyzed using a global fitting strategy using an optimized theoretical model that considers various classes of hydrogen atoms and allows disentangling diffusive and rotational motions. The approach has been carefully validated by checking the reliability of the calculation of parameters and their 99% confidence intervals. We demonstrate that quasi-elastic neutron scattering is a suitable experimental technique to characterize the dynamics of intracellular water in the angstrom/picosecond space/time scale and to investigate the effect of water dynamics on cellular biodiversity.展开更多
Metallic bowtie-shaped nanostructures are very interesting objects in optics,due to their capability of localizing and enhancing electromagnetic fields in the vicinity of their central neck.In this article,we investig...Metallic bowtie-shaped nanostructures are very interesting objects in optics,due to their capability of localizing and enhancing electromagnetic fields in the vicinity of their central neck.In this article,we investigate the electrostatic plasmonic resonances of two-dimensional bowtie-shaped domains by looking at the spectrum of their Poincare variational operator.In particular,we show that the latter only consists of essential spectrum and fills the whole interval[0,1].This behavior is very different from what occurs in the counterpart situation of a bowtie domain with only close-totouching wings,a case where the essential spectrum of the Poincare variational operator is reduced to an interval oess strictly containing in[0,1].We provide an explanation for this difference by showing that the spectrum of the Poincare variational operator of bowtie-shaped domains with close-to-touching wings has eigenvalues which densify and eventually fill the remaining parts of[0,1]\σess as the distance between the two wings tends to zero.展开更多
文摘BACKGROUND Liver cancer is the fifth most common cancer and the second cause of cancerrelated deaths worldwide.Transarterial chemoembolization(TACE)is the best treatment of intermediate hepatocellular carcinoma(HCC).Doxorubicin is the most commonly used drug despite a low level of evidence.AIM To compare the objective response rate of idarubicin-based TACE(Ida-TACE)against doxorubicin-based TACE(Dox-TACE)in intermediate stage HCC.METHODS Between January 2012 and December 2014,all patients treated with TACE at our academic hospital were screened.Inclusion criteria were patients with Child-Pugh score A or B,a performance status below or equal to 1,and no prior TACE.Either lipiodol TACE or drug-eluting beads TACE could be performed with 10 mg of idarubicin or 50 mg of doxorubicin.Each patient treated with idarubicin was matched with two doxorubicin-treated patients.The TACE response was assessed by independent radiologists according to the mRECIST criteria.RESULTS Sixty patients were treated with doxorubicin and thirty with idarubicin.There were 93%and 87%of cirrhotic patients and 87%and 70%of Child-Pugh A in the doxorubicin and idarubicin groups,respectively.The median number of HCC per patient was two in both groups with 31%and 26%of single nodules in doxorubicin and idarubicin groups,respectively.Objective response rate after first TACE was 76.7%and 73.3%(P=0.797)with 41.7%and 40.0%complete response in doxorubicin and idarubicin groups,respectively.Progression-free survival was 7.7 mo in both groups,and liver transplant-free survival was 24.9 mo and 21.9 mo in doxorubicin and idarubicin groups,respectively.Safety profiles were similar in both groups,with grade 3-4 adverse events in 35%of Dox-TACE and 43%of Ida-TACEs.CONCLUSION Ida-TACE and Dox-TACE showed comparable results in terms of efficacy and safety.Ida-TACE may represent an interesting alternative to Dox-TACE in the management of patients with intermediate stage HCC.
文摘Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of the seismic wave velocity induced by changes in the groundwater level. Here we compare the seismic measurements with actual piezometric data acquired on the Crépieux-Charmy (Lyon, France) groundwater exploitation field. We show the excellent correspondance between variations in the groundwater level and seismic velocity variations. We present hereafter the time and space monitoring of an hydraulic dome formed to prevent biological and chemical pollutions to enter the exploitation field. The horizontal resolution is solely limited by the number of seismic stations used, and is about 30 m in the present study. The vertical resolution of seismic measurement is impaired by spurious artifacts linked to the intermittent sources of noise. In average, the sensitivity of the seismic velocity change corresponds to a 50 cm change of waterlevel. This study confirms the possibility of groundwater monitoring in an industrial context with ambient seismic noise.
文摘Energy demand is increasing while we are facing a depletion of fossils fuels, the main source of energy production in the world. These last years, photovoltaic (PV) system technologies are growing rapidly among alternative sources of energy to contribute to mitigation of climate change. However, PV system efficiency researches operating under West African weather conditions are nascent. The first objective of this study is to investigate the sensitivity of common monocrystalline PV efficiency to local meteorological parameters (temperature, humidity, solar radiation) in two contrasted cities over West Africa: Niamey (Niger) in a Sahelian arid area and Abidjan (Cote d’Ivoire) in atropical humid area. The second objective is to quantify the effect of dust accumulation on PV efficiency in Niamey (Niger). The preliminary results show that PV efficiency is more sensitive to high temperature change especially under Niamey climate conditions (warmer than Abidjan) where high ambient temperatures above 33°C lead to an important decrease of PV efficiency. Increase of relative humidity induces a decrease of PV efficiency in both areas (Niamey and Abidjan). A power loss up to 12.46% is observed in Niamey after 21 days of dust accumulation.
基金supported by grants from the National Key Research and Development Program of China(2022YFF1001604)distinguished young scholar grant from the Department of Science and Technology of Hubei Province(2023AFA095)+1 种基金Fundamental Research Fund of Central Universities(2662023PY002 and 2662022SKYJ003)The computations in this paper were run on the bioinformatics computing platform of the National Key Laboratory of Crop Genetic Improvement,Huazhong Agricultural University.
文摘Cold stress is one of the major abiotic stress factors affecting rice growth and development,leading to significant yield loss in the context of global climate change.Exploring natural variants that confer cold resistance and the underlying molecular mechanism responsible for this is the major strategy to breed cold-tolerant rice varieties.Here,we show that natural variations of a SIMILAR to RCD ONE(SRO)gene,OsSRO1c,confer cold tolerance in rice at both seedling and booting stages.Our in vivo and in vitro experiments demonstrated that OsSRO1c possesses intrinsic liquid–liquid phase-separation ability and recruits OsDREB2B,an AP2/ERF transcription factor that functions as a positive regulator of cold stress,into its biomolecular condensates in the nucleus,resulting in elevated transcriptional activity of OsDREB2B.We found that the OsSRO1c-OsDREB2B complex directly responds to low temperature through dynamic phase transitions and regulates key cold-response genes,including COLD1.Furthermore,we showed that introgression of an elite haplotype of OsSRO1c into a cold-susceptible indica rice could significantly increase its cold resistance.Collectively,our work reveals a novel cold-tolerance regulatory module in rice and provides promising genetic targets for molecular breeding of cold-tolerant rice varieties.
文摘Background:The wetlands used for some agricultural activities constitute productive breeding sites for many mosquito species.Thus,the agricultural use of insecticide targeting other pests may select for insecticide resistance in malaria mosquitoes.The purpose of this study is to clarify some knowledge gaps on the role of agrochemicals in the development of insecticide resistance in malaria vectors is of utmost importance for vector control.Methods:Using the CDC bottle test and the log-probit analysis,we investigated for the first time the resistance levels ofAnopheles coluzzii mosquitoes to neonicotinoids,insecticides used exclusively for crop protection in C?te d’Ivoire.The study was conducted in two agricultural regions(Tiassale and Gagnoa)and one non-agricultural region(Vitre)between June and August 2017 using clothianidin,acetamiprid and imidacloprid.Results:Mosquito populations from Tiassale and Gagnoa(agricultural settings)were determined to be resistant to acetamiprid with mortality rates being<85%at 24 h post-exposure.In Vitre(non-agricultural area)however,the mosquito population was susceptible to acetamiprid.In all three localities,mosquito populations were resistant to imidacloprid(mortality rates were 60%in Vitre,37%in Tiassale,and 13%in Gagnoa)and completely susceptible to clothianidin(100%mortality).An.coluzzii represented 100%of mosquito collected in Gagnoa,86%in Tiassale and 96%in Vitre.Conclusions:This study provides strong evidence that agricultural use of insecticides can cause insecticide resistance in malaria vector populations.Insecticide resistance driven by agrochemical usage should be considered when vector control strategies are developed.
文摘Natural illumination conditions are highly variable and because of their sessile life style, plants are forced to acclimate to them at the cellular and molecular level. Changes in light intensity or quality induce changes in the reduction/oxidation (redox) state of the photosynthetic electron chain that acts as a trigger for compen- satory acclimation responses comprising functional and structural adjustments of photosynthesis and metabolism. Such responses include redox-controlled changes in plant gene expression in the nucleus and organelles. Here we describe a strategy for the identification of early redox-regulated genes (ERGs) in the nucleus of the model organism Arabidopsis thaliana that respond significantly 30 or 60 min after the generation of a reduction signal in the photosynthetic electron transport chain. By comparing the response of wild-type plants with that of the acclimation mutant stn7, we could specifically identify ERGs. The results reveal a significant impact of chloroplast redox signals on distinct nuclear gene groups including genes for the mitochondrial electron transport chain, tetrapyrrole biosynthesis, carbohydrate metabolism, and signaling lipid synthesis. These expression profiles are clearly different from those observed in response to the reduction of photosynthetic electron transport by high light treatments. Thus, the ERGs identified are unique to redox imbalances in photosynthetic electron transport and were then used for analyzing potential redox-responsive cis-elements, trans-factors, and chromosomal regulatory hot spots. The data identify a novel redox-responsive element and indicate extensive redox control at transcriptional and chromosomal levels that point to an unprecedented impact of redox signals on epigenetic processes.
基金We acknowledge funding from Agence Nationale de la Recherche under project HiLight(ANR-19-CE24-0020-01)support by the Toulouse computing facility HPC CALMIP(grants p12167 and p19042)the LAAS-CNRS micro and nanotechnologies platform,a member of the French RENATECH network.ICB is partner of the French Investissements d’Avenir program EUR-EIPHI(17-EURE-0002).
文摘Light emission of europium(Eu^(3+))ions placed in the vicinity of optically resonant nanoantennas is usually controlled by tailoring the local density of photon states(LDOS).We show that the polarization and shape of the excitation beam can also be used to manipulate light emission,as azimuthally or radially polarized cylindrical vector beam offers to spatially shape the electric and magnetic fields,in addition to the effect of silicon nanorings(Si-NRs)used as nanoantennas.The photoluminescence(PL)mappings of the Eu^(3+)transitions and the Si phonon mappings are strongly dependent of both the excitation beam and the Si-NR dimensions.The experimental results of Raman scattering and photoluminescence are confirmed by numerical simulations of the near-field intensity in the Si nanoantenna and in the Eu^(3+)-doped film,respectively.The branching ratios obtained from the experimental PL maps also reveal a redistribution of the electric and magnetic emission channels.Our results show that it could be possible to spatially control both electric and magnetic dipolar emission of Eu^(3+)ions by switching the laser beam polarization,hence the near field at the excitation wavelength,and the electric and magnetic LDOS at the emission wavelength.This paves the way for optimized geometries taking advantage of both excitation and emission processes.
基金supported by the Australian Research Council Centre of Excellence Project in Optical Microcombs for Breakthrough Science(No.CE230100006)the Australian Research Council Discovery Projects Programs(DP190103186,FT210100806)+5 种基金Linkage Program(LP210200345)the Swinburne ECR-SUPRA program,the Industrial Transformation Training Centers scheme(Grant No.IC180100005)the Beijing Natural Science Foundation(No.Z180007)the Agence Nationale de la Recherche(ANR)(Grant No.MIRSiCOMB,ANR-17-CE24-0028)the H2020 European Research Council(ERC)(Grant No.GRAPHICS,648546)supported by the International Associated Laboratory in Photonics between France and Australia(LIA ALPhFA).
文摘Optical parametric amplification(OPA)represents a powerful solution to achieve broadband amplification in wavelength ranges beyond the scope of conventional gain media,for generating high-power optical pulses,optical microcombs,entangled photon pairs and a wide range of other applications.Here,we demonstrate optical parametric amplifiers based on silicon nitride(Si3N4)waveguides integrated with two-dimensional(2D)layered graphene oxide(GO)films.We achieve precise control over the thickness,length,and position of the GO films using a transfer-free,layer-by-layer coating method combined with accurate window opening in the chip cladding using photolithography.Detailed OPA measurements with a pulsed pump for the fabricated devices with different GO film thicknesses and lengths show a maximum parametric gain of~24.0 dB,representing a~12.2 dB improvement relative to the device without GO.We perform a theoretical analysis of the device performance,achieving good agreement with experiment and showing that there is substantial room for further improvement.This work represents the first demonstration of integrating 2D materials on chips to enhance the OPA performance,providing a new way of achieving high performance photonic integrated OPA by incorporating 2D materials.
文摘Voltage-controlled conductance and switching induced by single molecules or atoms are ideally studied in scanning tunneling microscope (STM) tunnel junctions. While the objects under consideration are mostly used in their original form, little is known of the possibilities of in situ adjustments of their properties. Here, we evidence properties of a tunnel junction made of a Ce atom/cluster built by atomic manipulation on Au(111) at a temperature of 4.6 K in the presence of H2. The conductance through the object is characterized by a switching voltage corresponding to an opening or closing of an inelastic electron tunneling conductance channel at 50 mV for a Ce atom and 140 mV for a Ce cluster and by charging. We demonstrate that the electronic properties of an STM junction can be engineered in a simple way by in situ guiding of the H2 pinning at an atomic cluster.
基金partially supported by NSF grant DMS-12-11330 while CD was a postdoctoral visitor at Rutgers University and by the NSF IR/D program while MSV served at the National Science Foundation
文摘Asymptotic expansions of the voltage potential in terms of the "radius" of a diametrically small(or several diametrically small) material inhomogeneity(ies) are by now quite well-known. Such asymptotic expansions for diametrically small inhomogeneities are uniform with respect to the conductivity of the inhomogeneities.In contrast, thin inhomogeneities, whose limit set is a smooth, codimension 1 manifold,σ, are examples of inhomogeneities for which the convergence to the background potential,or the standard expansion cannot be valid uniformly with respect to the conductivity, a, of the inhomogeneity. Indeed, by taking a close to 0 or to infinity, one obtains either a nearly homogeneous Neumann condition or nearly constant Dirichlet condition at the boundary of the inhomogeneity, and this difference in boundary condition is retained in the limit.The purpose of this paper is to find a "simple" replacement for the background potential, with the following properties:(1) This replacement may be(simply) calculated from the limiting domain Ω\σ, the boundary data on the boundary of Ω, and the right-hand side.(2) This replacement depends on the thickness of the inhomogeneity and the conductivity,a, through its boundary conditions on σ.(3) The difference between this replacement and the true voltage potential converges to 0 uniformly in a, as the inhomogeneity thickness tends to 0.
基金ANR-17-CE40-0029 of the French National Research Agency ANR(project MultiOnde).
文摘This paper concerns the reconstruction of a scalar coefficient of a second-order elliptic equation in divergence form posed on a bounded domain from internal data.This problem finds applications in multi-wave imaging,greedy methods to approximate parameter-dependent elliptic problems,and image treatment with partial differential equations.We first show that the inverse problem for smooth coefficients can be rewritten as a linear transport equation.Assuming that the coefficient is known near the boundary,we study the well-posedness of associated transport equation as well as its numerical resolution using discontinuous Galerkin method.We propose a regularized transport equation that allow us to derive rigorous convergence rates of the numerical method in terms of the order of the polynomial approximation as well as the regularization parameter.We finally provide numerical examples for the inversion assuming a lower regularity of the coefficient,and using synthetic data.
文摘With the aim of studying the effect of water dynamics on the properties of biological systems, in this paper, we present a quasi-elastic neutron scattering study on three different types of living cells, differing both in their morphological and tumor properties. The measured scattering signal, which essentially originates from hydrogen atoms present in the investigated systems, has been analyzed using a global fitting strategy using an optimized theoretical model that considers various classes of hydrogen atoms and allows disentangling diffusive and rotational motions. The approach has been carefully validated by checking the reliability of the calculation of parameters and their 99% confidence intervals. We demonstrate that quasi-elastic neutron scattering is a suitable experimental technique to characterize the dynamics of intracellular water in the angstrom/picosecond space/time scale and to investigate the effect of water dynamics on cellular biodiversity.
基金partially supported by Hong Kong RGC grant ECS 26301016startup fund R9355 from HKUST+1 种基金partially supported by the AGIR-HOMONIM grant from Université Grenoble-Alpesby the Labex PERSYVAL-Lab (ANR-11-LABX-0025-01)
文摘Metallic bowtie-shaped nanostructures are very interesting objects in optics,due to their capability of localizing and enhancing electromagnetic fields in the vicinity of their central neck.In this article,we investigate the electrostatic plasmonic resonances of two-dimensional bowtie-shaped domains by looking at the spectrum of their Poincare variational operator.In particular,we show that the latter only consists of essential spectrum and fills the whole interval[0,1].This behavior is very different from what occurs in the counterpart situation of a bowtie domain with only close-totouching wings,a case where the essential spectrum of the Poincare variational operator is reduced to an interval oess strictly containing in[0,1].We provide an explanation for this difference by showing that the spectrum of the Poincare variational operator of bowtie-shaped domains with close-to-touching wings has eigenvalues which densify and eventually fill the remaining parts of[0,1]\σess as the distance between the two wings tends to zero.