In this paper, we study the existence of solutions for the semilinear equation , where A is a , , and is a nonlinear continuous function. Assuming that the Moore-Penrose inverse AT(AAT)-1?exists (A denotes the transpo...In this paper, we study the existence of solutions for the semilinear equation , where A is a , , and is a nonlinear continuous function. Assuming that the Moore-Penrose inverse AT(AAT)-1?exists (A denotes the transposed matrix of A) which is true whenever the determinant of the matrix AAT is different than zero, and the following condition on the nonlinear term satisfied . We prove that the semilinear equation has solutions for all. Moreover, these solutions can be found from the following fixed point relation .展开更多
Currently,artificial intelligence(AI),particularly computer vision(CV),has numerous applications in agriculture.In this field,the production and consumption of strawberries have experienced great growth in recent year...Currently,artificial intelligence(AI),particularly computer vision(CV),has numerous applications in agriculture.In this field,the production and consumption of strawberries have experienced great growth in recent years,which makes meeting the growing demand a challenge that producers must face.However,one of the main problems regarding the cultivation of this fruit is the high cost and long picking times.In response,automatic harvesting has surged as an option to address this difficulty,and fruit instance segmentation plays a crucial role in these types of systems.Fruit segmentation is related to the identification and separation of individual fruits within a crop,allowing a more efficient and accurate harvesting process.Although deep learning(DL)techniques have shown potential for this activity,the complexity of the models leads to difficulty in their implementation in real-time systems.For this reason,a model capable of performing adequately in real-time,while also having good precision is of great interest.With this motivation,this work presents a efficient Mask R-CNN model to perform instance segmentation in strawberry fruits.The efficiency of the model is assessed considering the amount of frames per second(FPS)it can process,its size in megabytes(MB)and its mean average precision(mAP)value.Two approaches are provided:The first one consists on the training of the model using the Detectron2 library,while the second one focuses on the training of the model using the NVIDIA TAO Toolkit.In both cases,NVIDIA TensorRT is used to optimize the models.The results show that the best Mask R-CNN model,without optimization,has a performance of 83.45 mAP,4 FPS,and 351 MB of size,which,after the TensorRT optimization,achieved 83.17 mAP,25.46 FPS,and only 48.2 MB of size.It represents a suitable model for implementation in real-time systems.展开更多
One of the primary goals of the space exploration community is to unambiguously detect past or present life outside of Earth.As such,a number of so-called life detection technologies,instruments,and approaches have be...One of the primary goals of the space exploration community is to unambiguously detect past or present life outside of Earth.As such,a number of so-called life detection technologies,instruments,and approaches have been applied as part of past,current,and future space missions.As astrobiology is a truly interdisciplinary field within the realm of space exploration with major contributions from physical and biological sciences(among others),recently there has been development of a number of relevant techniques from scientific fields that have yet to be fully applied to extraterrestrial life detection.As a culmination of the 2021 Blue Marble Space Institute of Science(BMSIS)Young Scientist Program(YSP),we present a number of techniques drawn from various fields(including,but not limited to,chemistry,materials science,biology,nanotechnology,medical science,astrophysics,and more)that either have been or have the potential to be applied to life detection research.These techniques broadly fall under three categories:instrumentation for in situ measurements of biosignatures within the solar system,calculations or observational techniques for remote measurements of exoplanet biosignatures,and technosignatures.We hope that this primer serves to inspire the field to consider applying more potential technologies from adjacent fields into any of these three categories of life detection.展开更多
Owing to their higher intrinsic electrical conductivity and chemical stability with respect to their oxide counterparts, nanostructured metal sulfides are expected to revive materials for resistive chemical sensor app...Owing to their higher intrinsic electrical conductivity and chemical stability with respect to their oxide counterparts, nanostructured metal sulfides are expected to revive materials for resistive chemical sensor applications. Herein, we explore the gas sensing behavior of WS2 nanowire-nanoflake hybrid materials and demonstrate their excellent sensitivity （0.043 ppm-1） as well as high selectivity towards H2S relative to CO, NH~, H2, and NO （with corresponding sensitivities of 0.002, 0.0074, 0.0002, and 0.0046 pprn-1, respectively）. Gas response measurements, complemented with the results of X-ray photoelectron spectroscopy analysis and first-principles calculations based on density functional theory, suggest that the intrinsic electronic properties of pristine WS2 alone are not sufficient to explain the observed high sensitivity towards H2S. A major role in this behavior is also played by O doping in the S sites of the WS2 lattice. The results of the present study open up new avenues for the use of transition metal disulfide nanomaterials as effective alternatives to metal oxides in future applications for industrial process control, security, and health and environmental safety.展开更多
In November 2015,El Salvador reported their first case of Zika virus(ZIKV)infection,an event followed by an explosive outbreak that generated over 6000 suspected cases in a period of two months.National agencies began...In November 2015,El Salvador reported their first case of Zika virus(ZIKV)infection,an event followed by an explosive outbreak that generated over 6000 suspected cases in a period of two months.National agencies began implementing control measures that included vector control and recommending an increased use of repellents.Further,in response to the alarming and growing number of microcephaly cases in Brazil,the importance of avoiding pregnancies for two years was stressed.In this paper,we explore the role of mobility within communities characterized by extreme poverty,crime and violence.Specifically,the role of short term mobility between two idealized interconnected highly distinct communities is explored in the context of ZIKV outbreaks.We make use of a Lagrangian modeling approach within a two-patch setting in order to highlight the possible effects that short-term mobility,within highly distinct environments,may have on the dynamics of ZIKV outbreak when the overall goal is to reduce the number of cases not just in the most affluent areas but everywhere.Outcomes depend on existing mobility patterns,levels of disease risk,and the ability of federal or state public health services to invest in resource limited areas,particularly in those where violence is systemic.The results of simulations in highly polarized and simplified scenarios are used to assess the role of mobility.It quickly became evident that matching observed patterns of ZIKV outbreaks could not be captured without incorporating increasing levels of heterogeneity.The number of distinct patches and variations on patch connectivity structure required to match ZIKV patterns could not be met within the highly aggregated model that is used in the simulations.展开更多
Aims The importance of quantifying carbon stocks in terrestrial ecosystems is crucial for determining climate change dynamics.However,the present regional assessments of carbon stocks in tropical grasslands are extrap...Aims The importance of quantifying carbon stocks in terrestrial ecosystems is crucial for determining climate change dynamics.However,the present regional assessments of carbon stocks in tropical grasslands are extrapolated to unsampled areas with a high degree of uncertainty and without considering the carbon and nitrogen composition of vegetation and soil along altitudinal ranges.This study aims to assess carbon and nitrogen concentrations in soil and vegetation,aboveground carbon stocks distribution and soil organic carbon stocks along an altitudinal range in the páramo region in the Ecuadorian Andes.Methods The vegetation inventory was conducted using 15×15 m sampling plots distributed in three altitudinal ranges.Based on the patterns exhibited by the dominant vegetation growth forms,biomass and soil were sampled to quantify the corresponding carbon and nitrogen concentrations.Subsequently,the aboveground live biomass along the páramo altitudinal range was estimated using allometric equations.Finally,soil and vegetation carbon stocks were estimated for the entire basin.Important Findings Altitudinal analysis supported a potential distribution of carbon and nitrogen concentrations in soil,litter and live tissues,where higher concentrations were found in the low altitudinal range mainly for tussocks and acaulescent rosettes.Cellulose in litter showed higher concentrations at low altitudinal ranges for acaulescent rosettes and cushions only.For the same growth forms,lignin patterns in litter were higher in high altitudinal ranges.Soil texture provided complementary information:high percentage of silt was highly correlated to high soil nitrogen and carbon concentration.Tussocks were found to be responsive to altitude with their,highest aboveground carbon stocks occurring at the low altitudinal range,but cushions and acaulescent rosettes responded differently.The established relationships among soil,vegetation and altitude shown in this study must be taken into account to estimate both aboveground and soil organic carbon stocks in páramo regions—such estimates will be considerably inaccurate if these relationships are ignored.展开更多
文摘In this paper, we study the existence of solutions for the semilinear equation , where A is a , , and is a nonlinear continuous function. Assuming that the Moore-Penrose inverse AT(AAT)-1?exists (A denotes the transposed matrix of A) which is true whenever the determinant of the matrix AAT is different than zero, and the following condition on the nonlinear term satisfied . We prove that the semilinear equation has solutions for all. Moreover, these solutions can be found from the following fixed point relation .
文摘Currently,artificial intelligence(AI),particularly computer vision(CV),has numerous applications in agriculture.In this field,the production and consumption of strawberries have experienced great growth in recent years,which makes meeting the growing demand a challenge that producers must face.However,one of the main problems regarding the cultivation of this fruit is the high cost and long picking times.In response,automatic harvesting has surged as an option to address this difficulty,and fruit instance segmentation plays a crucial role in these types of systems.Fruit segmentation is related to the identification and separation of individual fruits within a crop,allowing a more efficient and accurate harvesting process.Although deep learning(DL)techniques have shown potential for this activity,the complexity of the models leads to difficulty in their implementation in real-time systems.For this reason,a model capable of performing adequately in real-time,while also having good precision is of great interest.With this motivation,this work presents a efficient Mask R-CNN model to perform instance segmentation in strawberry fruits.The efficiency of the model is assessed considering the amount of frames per second(FPS)it can process,its size in megabytes(MB)and its mean average precision(mAP)value.Two approaches are provided:The first one consists on the training of the model using the Detectron2 library,while the second one focuses on the training of the model using the NVIDIA TAO Toolkit.In both cases,NVIDIA TensorRT is used to optimize the models.The results show that the best Mask R-CNN model,without optimization,has a performance of 83.45 mAP,4 FPS,and 351 MB of size,which,after the TensorRT optimization,achieved 83.17 mAP,25.46 FPS,and only 48.2 MB of size.It represents a suitable model for implementation in real-time systems.
基金the primary outcome of a summer research intern-ship with the Blue Marble Space Institute of Science(BMSIS)2021 Young Scientist Program(YSP)G.E.L.is partially funded through the NASA Shared Services Center grant“An Integrated Approach Towards Understanding Planetary Environments For The Origin And Detectability Of Life”(grant number 80NSSC18M0064)。
文摘One of the primary goals of the space exploration community is to unambiguously detect past or present life outside of Earth.As such,a number of so-called life detection technologies,instruments,and approaches have been applied as part of past,current,and future space missions.As astrobiology is a truly interdisciplinary field within the realm of space exploration with major contributions from physical and biological sciences(among others),recently there has been development of a number of relevant techniques from scientific fields that have yet to be fully applied to extraterrestrial life detection.As a culmination of the 2021 Blue Marble Space Institute of Science(BMSIS)Young Scientist Program(YSP),we present a number of techniques drawn from various fields(including,but not limited to,chemistry,materials science,biology,nanotechnology,medical science,astrophysics,and more)that either have been or have the potential to be applied to life detection research.These techniques broadly fall under three categories:instrumentation for in situ measurements of biosignatures within the solar system,calculations or observational techniques for remote measurements of exoplanet biosignatures,and technosignatures.We hope that this primer serves to inspire the field to consider applying more potential technologies from adjacent fields into any of these three categories of life detection.
文摘Owing to their higher intrinsic electrical conductivity and chemical stability with respect to their oxide counterparts, nanostructured metal sulfides are expected to revive materials for resistive chemical sensor applications. Herein, we explore the gas sensing behavior of WS2 nanowire-nanoflake hybrid materials and demonstrate their excellent sensitivity （0.043 ppm-1） as well as high selectivity towards H2S relative to CO, NH~, H2, and NO （with corresponding sensitivities of 0.002, 0.0074, 0.0002, and 0.0046 pprn-1, respectively）. Gas response measurements, complemented with the results of X-ray photoelectron spectroscopy analysis and first-principles calculations based on density functional theory, suggest that the intrinsic electronic properties of pristine WS2 alone are not sufficient to explain the observed high sensitivity towards H2S. A major role in this behavior is also played by O doping in the S sites of the WS2 lattice. The results of the present study open up new avenues for the use of transition metal disulfide nanomaterials as effective alternatives to metal oxides in future applications for industrial process control, security, and health and environmental safety.
基金This paper is dedicated to the inauguration of the Centro de Modelamiento Matematico Carlos Castillo-Chavez at Universidad Francisco Gavidia in San Salvador,El SalvadorThis project has been partially supported by grants from the National Science Foundation(DMS-1263374 and DUE-1101782),the National Security Agency(H98230-14-1-0157)the Office of the President of ASU,and the Office of the Provost of ASU.The views expressed are sole responsibility of the authors and not the funding agencies.
文摘In November 2015,El Salvador reported their first case of Zika virus(ZIKV)infection,an event followed by an explosive outbreak that generated over 6000 suspected cases in a period of two months.National agencies began implementing control measures that included vector control and recommending an increased use of repellents.Further,in response to the alarming and growing number of microcephaly cases in Brazil,the importance of avoiding pregnancies for two years was stressed.In this paper,we explore the role of mobility within communities characterized by extreme poverty,crime and violence.Specifically,the role of short term mobility between two idealized interconnected highly distinct communities is explored in the context of ZIKV outbreaks.We make use of a Lagrangian modeling approach within a two-patch setting in order to highlight the possible effects that short-term mobility,within highly distinct environments,may have on the dynamics of ZIKV outbreak when the overall goal is to reduce the number of cases not just in the most affluent areas but everywhere.Outcomes depend on existing mobility patterns,levels of disease risk,and the ability of federal or state public health services to invest in resource limited areas,particularly in those where violence is systemic.The results of simulations in highly polarized and simplified scenarios are used to assess the role of mobility.It quickly became evident that matching observed patterns of ZIKV outbreaks could not be captured without incorporating increasing levels of heterogeneity.The number of distinct patches and variations on patch connectivity structure required to match ZIKV patterns could not be met within the highly aggregated model that is used in the simulations.
基金Ecuador’s SENESCYT(Secretaría Nacional de Educación Superior,Ciencia,Tecnología e Innovación)Dutch Ministry of Foreign Affairs(DUPC Program at UNESCO-IHE).
文摘Aims The importance of quantifying carbon stocks in terrestrial ecosystems is crucial for determining climate change dynamics.However,the present regional assessments of carbon stocks in tropical grasslands are extrapolated to unsampled areas with a high degree of uncertainty and without considering the carbon and nitrogen composition of vegetation and soil along altitudinal ranges.This study aims to assess carbon and nitrogen concentrations in soil and vegetation,aboveground carbon stocks distribution and soil organic carbon stocks along an altitudinal range in the páramo region in the Ecuadorian Andes.Methods The vegetation inventory was conducted using 15×15 m sampling plots distributed in three altitudinal ranges.Based on the patterns exhibited by the dominant vegetation growth forms,biomass and soil were sampled to quantify the corresponding carbon and nitrogen concentrations.Subsequently,the aboveground live biomass along the páramo altitudinal range was estimated using allometric equations.Finally,soil and vegetation carbon stocks were estimated for the entire basin.Important Findings Altitudinal analysis supported a potential distribution of carbon and nitrogen concentrations in soil,litter and live tissues,where higher concentrations were found in the low altitudinal range mainly for tussocks and acaulescent rosettes.Cellulose in litter showed higher concentrations at low altitudinal ranges for acaulescent rosettes and cushions only.For the same growth forms,lignin patterns in litter were higher in high altitudinal ranges.Soil texture provided complementary information:high percentage of silt was highly correlated to high soil nitrogen and carbon concentration.Tussocks were found to be responsive to altitude with their,highest aboveground carbon stocks occurring at the low altitudinal range,but cushions and acaulescent rosettes responded differently.The established relationships among soil,vegetation and altitude shown in this study must be taken into account to estimate both aboveground and soil organic carbon stocks in páramo regions—such estimates will be considerably inaccurate if these relationships are ignored.
