The effects of magnitude rounding and of the presence of noise in the rounded magnitudes on the estimation of the Gutenberg-Richter b-value are explored, and the ways to correct for these effects are proposed. For typ...The effects of magnitude rounding and of the presence of noise in the rounded magnitudes on the estimation of the Gutenberg-Richter b-value are explored, and the ways to correct for these effects are proposed. For typical values, b = 1 and rounding interval △M = 0.1, the rounding error is approximately -10^-3 and it can be corrected to a negligible approximately -10^-5. For the same typical values, the effect of noise can be larger, depending on the characteristics of the noise distribution; for normally distributed noise with standard deviation σ = 0.1, the correct b-value may be underestimated by a factor - 0.97.展开更多
To describe the annual cycle of Sargassum horneri in Mexican waters, we selected two sites differing in their degree of wave exposure and sediment type: Rincón de Ballenas (RB), and Rancho Packard (RP). From June...To describe the annual cycle of Sargassum horneri in Mexican waters, we selected two sites differing in their degree of wave exposure and sediment type: Rincón de Ballenas (RB), and Rancho Packard (RP). From June 2009 to April 2010 we followed the seasonal changes in S. horneri density and biomass along two intertidal transects per site. The effects of this non-indigenous species on the local macroalgae community were assessed by comparing their species composition, density, biomass, species richness, and diversity index in quadrats with and without S. horneri. There were significant differences in S. horneri density and biomass between sites (P < 0.001). At RB the invasive alga density average was 2 ± 0.94 individual m-2, with a mean biomass of 4 ± 0.95 g DW m-2. At RP, S. horneri density average was 10 ± 0.96 individual m-2, and mean biomass of 102 ± 0.97 g DW m-2. At RB, the invasive alga promoted a significant reduction in the four selected structural variables, and the corticated macrophytes and the foliose functional forms were severely reduced. At RP, there were only marginally significant effects (P = 0.06) of S. horneri presence on the local macroalgae community, and higher density, biomass, and diversity values were found when S. horneri was present. Most of the functional forms were found, even if the invasive alga was present. At both locations, the highest biomass corresponded to the articulated calcareous functional form. These contrasting results could be due to the fact that the native macroalgae community has already been altered by the early invasion of S. muticum, with the most resilient species and functional forms remaining in place. One of the most important changes we noticed is the severe reduction of the canopy forming species at both sites.展开更多
This work gives an introduction to the R package NORRRM whose main purpose is to calculate the CIPW Norm. Although there are many softwares and spreadsheets available to estimate the standard mineral assemblages in ig...This work gives an introduction to the R package NORRRM whose main purpose is to calculate the CIPW Norm. Although there are many softwares and spreadsheets available to estimate the standard mineral assemblages in igneous rocks, this package has the following advantages: a) it has the ability to be run on any operating computer systems (BSD, GNU/Linux, Mac OS X<sup>®</sup>, Windows<sup>®</sup>);b) an input argument allows choose different procedures to set the Fe-oxidation ratio;c) the options to use whole-rock major as well as minor oxides and trace elements in the computation;d) the output data yields highly consistent results achieving absolute match between the sum of the input weights of oxides recalculated on an anhydrous basis and the sum of the weights of estimated normative minerals and;e) the functions are written in R language and released under terms that guarantee users the freedom to study, adapt, modify, and distribute the software.展开更多
The search for reliable and eco-friendly methods for the production of nanoscale materials is an important aspect of nanotechnology. Silver nanoparticles (AgNPs) are of special interest because of their antimicrobial ...The search for reliable and eco-friendly methods for the production of nanoscale materials is an important aspect of nanotechnology. Silver nanoparticles (AgNPs) are of special interest because of their antimicrobial properties, especially those of small size. In this work, AgNPs were produced under different conditions of temperature and pH using the extract from the fungus Neurospora crassa as reducing agent. Mainly quasi-spherical particles were obtained at all incubation conditions. However, optimum conditions to produce small sizes in the range of 2 - 9 nm were at 4°C and pH 3, also particles of 2 - 22 nm were obtained at 25°C with unmodified pH (6.5) and pH 10. Nevertheless, only particles synthesized at 25°C and pH 10 maintained the same size range after storage of 10 months. In summary, optimal incubation conditions for the synthesis of silver nanoparticles of small size range are reported. This improves the storage time of particles without losing its original size and without going into aggregation or agglomeration.展开更多
The thermoregulatory behavior of sea hare Aplysia californica was determined in a horizontal thermal gradient;with a preferred temperature (PT) of 18.3°C for the day cycle and 20.8°C for the night cycle. The...The thermoregulatory behavior of sea hare Aplysia californica was determined in a horizontal thermal gradient;with a preferred temperature (PT) of 18.3°C for the day cycle and 20.8°C for the night cycle. The displacement velocity demonstrated an initial rate of 30 cm·hˉ1 and gradually the velocity diminished to 18 cm·hˉ1 with several fluctuations mainly at 02:00 am. Critical Temperature Maxima (CTMax refers to the temperature point where at least 50% of the experimental group have a loss of attachment) was measured at three acclimation temperatures (16°C, 19°C and 22°C). At the lowest acclimation temperature (16°C), 50% of the experimental group had an attachment loss at CTMax 32.7°C, and in a higher acclimation temperature (22°C) CTMax was 36.2°C. The Oxygen Consumption Rate (OCR) was closely correlated to acclimation temperature, and at 16°C and 19°C sea hare had a relatively stable metabolic rate, with OCR increasing to 9 mg O2 hˉ1·kgˉ1 w.w. in a higher acclimation temperature.展开更多
Tsunamis in Mexico are a real threat, still unknown to many, mainly by people living in or visiting the coast. The Tsunami Warning Center in Mexico recently created （September 19, 2011） monitors earthquakes and sea ...Tsunamis in Mexico are a real threat, still unknown to many, mainly by people living in or visiting the coast. The Tsunami Warning Center in Mexico recently created （September 19, 2011） monitors earthquakes and sea level change caused by these same. Sea level on the west coast of the Mexican Pacific was analyzed after the occurrence of local, regional and distant earthquakes, in order to determine the existence of an anomaly due to the quake itself. Variations in sea level due to local registered earthquakes Mw 6.0 to 7.4 range was from 0.10 to 0.30 m; for regional earthquakes of Mw 7.3 and 8.2 were 0.12 and 0.22 m respectively and to the distant earthquake of Mw 8.0 recorded in Solomon Islands, the change in sea level of the maximum recorded was 0.20 m in Manzanillo, Colima. It is important to know that earthquakes whether local, regional or distant whose magnitudes are in the range specified here, did not present a risk to the Mexican coast, but do not rely, having to monitor variations in sea level that earthquakes can produce and be aware that you may perhaps occur as a tsunami in Indonesia in 2004 or Japan in 2011.展开更多
Formulation of control objectives is a key issue in automatic control systems design. Although at first sight the desired goal （control objective） of a control system seems to be a trivial and obvious matter, for...Formulation of control objectives is a key issue in automatic control systems design. Although at first sight the desired goal （control objective） of a control system seems to be a trivial and obvious matter, for effectiveness of some high level robotic tasks, unusual exotic control objectives may be required. This paper presents a review of some exotic control objectives useful in robotics, such as velocity field control objective and range control objective. The paper also proposes a novel confinement control objective. The usefulness of these exotic control objectives may appear in safe robot-human interaction and self-protection of robots against collisions.展开更多
This paper presents a study of amorphous SiO<sub>x</sub> thin films by means of Variable Angle Spectroscopic Ellipsometry (VASE) technique. Tauc Lorentz, Lorentz and Cauchy models have been used to obtain ...This paper presents a study of amorphous SiO<sub>x</sub> thin films by means of Variable Angle Spectroscopic Ellipsometry (VASE) technique. Tauc Lorentz, Lorentz and Cauchy models have been used to obtain physical thickness and complex refractive index (n and k) from experimental data. In order to obtain a wide range to x stoichiometry values, the films were prepared by vacuum thermal evaporation of SiO on glass substrates, under different and controlled deposition conditions.展开更多
Periodicity is common in natural processes, however, extraction tools are typically difficult and cumbersome to use. Here we report a computational method developed in MATLAB through a function called Periods with the...Periodicity is common in natural processes, however, extraction tools are typically difficult and cumbersome to use. Here we report a computational method developed in MATLAB through a function called Periods with the aim to find the main harmonic components of time series data. This function is designed to obtain the period, amplitude and lag phase of the main harmonic components in a time series (Periods and lag phase components can be related to climate, social or economic events). It is based on methods of periodic regression with cyclic descent and includes statistical significance testing. The proposed method is very easy to use. Furthermore, it does not require full understanding of time series theory, nor require many inputs from the user. However, it is sufficiently flexible to undertake more complex tasks such as forecasting. Additionally, based on previous knowledge, specific periods can be included or excluded easily. The output results are organized into two groups. One contains the parameters of the adjusted model and their F statistics. The other consists of the harmonic parameters that best fit the original series according to their importance and the summarized statistics of the comparisons between successive models in the cyclic descent process. Periods is tested with both, simulated and actual sunspot and Multivariate ENSO Index data to show its performance and accuracy.展开更多
Variability of the optical properties of the northern Gulf of California (México) were analyzed for the first time based on six cruises performed from spring to summer (March to September) between 2008 and 2013. ...Variability of the optical properties of the northern Gulf of California (México) were analyzed for the first time based on six cruises performed from spring to summer (March to September) between 2008 and 2013. The changes observed in the absorption by three seawater components (phytoplankton, detritus and chromophoric dissolved organic matter or CDOM) were analyzed in relation to changes in bio-optical regions and composition of the phytoplankton community (determined based on phytoplankton pigments). Two regions with unique bio-optical characteristics were identified separated by a narrow transition zone: the Upper Gulf of California (UGC) and Northern Gulf of California (NGC). Despite the temporal changes in their spatial distribution they maintained particular characteristic. UGC is characterized by an average Chla of 1.78 mg/m3, the dominance of microphytoplankton (diatoms and dinoflagellates) and a stronger contribution of detritus to total light absorption. NGC is characterized by an average Chla of 0.7 mg/m3 and the predominance of picophytoplankton, characterized by the dominance of zeaxanthin (marker pigment for cyanobacteria) and/or chlorophyll b (marker pigment for green algae), along with a co-dominium by CDOM and phytoplankton to light absorption. Results indicate that Case II waters can be very different when evaluating the individual contribution by phytoplankton, detritus and CDOM to total light absorption what has to be considered for the selection of bio-optical models for each specific region what can also help to a better definition of the related uncertainties.展开更多
The occurrence of massif-type anorthosite intrusions is a widespread Proterozoic phenomenon.They are usually associated with gabbroic,charnockitic,and granitic rocks,comprising the so-called anorthositemangerite-charn...The occurrence of massif-type anorthosite intrusions is a widespread Proterozoic phenomenon.They are usually associated with gabbroic,charnockitic,and granitic rocks,comprising the so-called anorthositemangerite-charnockite-granite(AMCG)suite.Although these rocks have been extensively studied worldwide,several aspects concerning their formation remain unsettled.Among them,the magma source and the tectonic setting are the most important.To evaluate these issues,we first compiled geochemical and isotopic data of Proterozoic anorthosite massifs and AMCG suites worldwide and stored it in a database named datAMCG.This plethora of data allows us to make some important interpretations.We argue that the wide-ranging multi-isotopic composition of this group of rocks reflects varying proportions of juvenile mantle-derived melts and crustal components.We interpret that the precursor magmas of most massive anorthosite bodies and associated mafic rocks have a mantle-dominated origin.However,we highlight that a crustal component is indispensable to generate these lithologies.Adding variable amounts of this material during succeeding multi-stage assimilation-fractional crystallization(AFC)processes gives these intrusions their typical mantle-crustal hybrid isotopic traits.In contrast,a crustaldominant origin with a complementary mantle component is interpreted for most MCG rocks.In summary,the isotopic information in datAMCG indicates that both sources are necessary to generate AMCG rocks.Therefore,we suggest that hybridized magmas with different mantle-crust proportions originate these rocks.This interpretation might offer a more nuanced and accurate depiction of this phenomenon in future work instead of choosing a single-sourced model as in the past decades.Finally,tectonomagmatic diagrams suggest that the rocks under study were likely generated in a tectonic environment that transitioned between collision and post-collisional extension,sometimes involving subduction-modified mantle sources.This interpretation is supported by geological and geochronological information from most complexes,thus challenging the Andean-type margins as an ideal tectonic setting.展开更多
Glider-based microstructure observations combined with ship-based conductivity-temperature-depth profiles were collected on the western part of the Gulf of Mexico(GoM),within the steep continental slope region in Nove...Glider-based microstructure observations combined with ship-based conductivity-temperature-depth profiles were collected on the western part of the Gulf of Mexico(GoM),within the steep continental slope region in November 2017.Dynamical processes associated with bathymetry were observed,and enhanced mixing along the continental slope was detected,with diffusivity values as high as 10^(-3) m^(2)/s.Recent studies proposed a conceptual model of deep GoM circulation where deep water entering the GoM sinks and fills the deep GoM through the Yucatan Channel.We hypothesize that to retain mass balance,this continuously supplied deep water has to upwell and create intermediate water,which forms the outflow of the GoM,ventilating the deep GoM on time scales of~100 years.The western GoM has areas with steep continental slopes,where enhanced mixing likely results in the transformation and upwelling of deep water.展开更多
We present a new design of a plasmonic Luneburg lens made from a gradient-index metasurface that was constructed with an array of nanometer-sized holes in a dielectric thin film. The fabricated structure consists of a...We present a new design of a plasmonic Luneburg lens made from a gradient-index metasurface that was constructed with an array of nanometer-sized holes in a dielectric thin film. The fabricated structure consists of a planar lens with a diameter of 8.7 μm composed of a rectangular array of holes with a periodicity of 300 nm. The experimental characterization includes leakage-radiation microscopy imaging in the direction and frequency space. The former allows for characterization of the point spread function and phase distribution,whereas the latter grants access to qualitative measurements of the effective mode indices inside the plasmonic lens. The experimental results presented here are in good agreement with the expected average performance predicted by the numerical calculations. Nevertheless, the robustness of the characterization techniques presented here is also exploited to determine deviations from the design parameters.展开更多
The optical theorem,which is a consequence of the energy conservation in scattering processes,directly relates the forward scattering amplitude to the extinction cross-section of the object.Originally derived for plan...The optical theorem,which is a consequence of the energy conservation in scattering processes,directly relates the forward scattering amplitude to the extinction cross-section of the object.Originally derived for planar scalar waves,it neglects the complex structure of the focused beams and the vectorial nature of the electromagnetic field.On the other hand,radially or azimuthally polarized fields and various vortex beams,essential in modern photonic technologies,possess a prominent vectorial field structure.Here,we experimentally demonstrate a complete violation of the commonly used form of the optical theorem for radially polarized beams at both visible and microwave frequencies.We show that a plasmonic particle illuminated by such a beam exhibits strong extinction,while the scattering in the forward direction is zero.The generalized formulation of the optical theorem provides agreement with the observed results.The reported effect is vital for the understanding and design of the interaction of complex vector beams carrying longitudinal field components with subwavelength objects important in imaging,communications,nanoparticle manipulation,and detection,as well as metrology.展开更多
Objective:To examine the immune responses of Litopenaeus vannamei after different treatments with a hot water extract of Macrocystis pyrifera(M.pyrifera)and a subsequent challenge with Vibrio campbellii(V.campbellii)....Objective:To examine the immune responses of Litopenaeus vannamei after different treatments with a hot water extract of Macrocystis pyrifera(M.pyrifera)and a subsequent challenge with Vibrio campbellii(V.campbellii).Methods:A total of 184 adult white shrimp that were infected with V.campbellii(1×10^(6) CFU/shrimp)were immunostimulate by the hot-water extract from M.pyrifera via either injection(10μg)or immersion(350 mg/L),the experimental controls were injected with either saline solution or V.campbellii(1×10^(6) CFU/shrimp).The bacterial DNA depuration rate,antimicrobial activity and total hemocyte count were evaluated in hemolymph samples at 2,6,12,24,48 and 72 h post-infection.Results:Injected shrimp(10μg M.pyrifera extract)demonstrated the best clearance of bacterial infection,with 82%survival at 72 h post-infection(cellular response).Hemolymph from the immersed organisms had the best antimicrobial activity against Escherichia coli growth;specifically,the most efficient antimicrobial activity was observed at 24 h post-infection.Both types of immunostimulated shrimp had similar total hemocyte counts at 24 h post-infection(1.63-1.59 million/mL);however,after 72 h,injected shrimp had higher total hemocyte counts than immersed animals(2.59 v.s.0.56 million/mL).Conclusions:The injection of the M.pyrifera hot-water extract facilitated a more efficient response to V.campbellii infection due to the stimulation of the hemocytes of the shrimp.In other words,the cellular immune response was more efficient to eliminate bacterial infection than the humoral response in shrimp.展开更多
Nearly 80%of the seafloor extension has not been covered by high-resolution bathymetry,impeding direct observation of seamounts.Nevertheless,lists of seamount location and height at a global scale have been produced u...Nearly 80%of the seafloor extension has not been covered by high-resolution bathymetry,impeding direct observation of seamounts.Nevertheless,lists of seamount location and height at a global scale have been produced using different techniques.In this work four of such databases(publicly available)are compared with each other to assess their differences.Results identify large differences among databases that could have exerted strong influences on models of seamount production and associated geodynamic processes.Despite those differences,it is shown that all databases allow the identification of seamount lines both along the present-day Mid Ocean Ridge(MOR)system and on intraplate settings.Notably,those seamount lines do not coincide with the so-called hotspot tracks that commonly were defined by selectively focusing attention on the larger seamounts.Examination of all the databases also shows that distinction based only on seamount size between seamounts produced at Mid-Ocean Ridge(MOR)environments from those associated with mantle-plum fed-hotspot activity has been overestimated.This,combined with the fact that most seamount lines defined by the available databases can be traced back to past locations of MOR indicates that most of the present-day intraplate linear arrays of seamounts,which include some large seamounts,were not produced by the action of underlying mantle anomalies envisaged in the form of mantle plumes.The evidence presented here calls for a reassessment of the form in which volcanic and tectonic activities are conceptually related to each other.展开更多
In this Letter,a Gabor superlens with variable focus is presen ted.This configuration uses tunable liquid lenses in the third microlens array of the Gabor superlens.By applying voltage,the radius of curvature of the m...In this Letter,a Gabor superlens with variable focus is presen ted.This configuration uses tunable liquid lenses in the third microlens array of the Gabor superlens.By applying voltage,the radius of curvature of the microtunable doublet arrays changes,and the Gabor conditions are fulfilled at different focal planes.As a consequence,the magnification of the image at the focal planes changes,and a zoom effect is observed.The marginal depth plane for this system goes from 0.86 to 0.89 mm.The optical simulation,calculations,and results of the simulated optical system performance are presented.展开更多
基金partially funded by UNAMDGAPA postdoctoral scholarship(VH Márquez-Ramírez)CONACYT grant 222795UNAM-DGAPA-PAPIIT grant IN108115
文摘The effects of magnitude rounding and of the presence of noise in the rounded magnitudes on the estimation of the Gutenberg-Richter b-value are explored, and the ways to correct for these effects are proposed. For typical values, b = 1 and rounding interval △M = 0.1, the rounding error is approximately -10^-3 and it can be corrected to a negligible approximately -10^-5. For the same typical values, the effect of noise can be larger, depending on the characteristics of the noise distribution; for normally distributed noise with standard deviation σ = 0.1, the correct b-value may be underestimated by a factor - 0.97.
文摘To describe the annual cycle of Sargassum horneri in Mexican waters, we selected two sites differing in their degree of wave exposure and sediment type: Rincón de Ballenas (RB), and Rancho Packard (RP). From June 2009 to April 2010 we followed the seasonal changes in S. horneri density and biomass along two intertidal transects per site. The effects of this non-indigenous species on the local macroalgae community were assessed by comparing their species composition, density, biomass, species richness, and diversity index in quadrats with and without S. horneri. There were significant differences in S. horneri density and biomass between sites (P < 0.001). At RB the invasive alga density average was 2 ± 0.94 individual m-2, with a mean biomass of 4 ± 0.95 g DW m-2. At RP, S. horneri density average was 10 ± 0.96 individual m-2, and mean biomass of 102 ± 0.97 g DW m-2. At RB, the invasive alga promoted a significant reduction in the four selected structural variables, and the corticated macrophytes and the foliose functional forms were severely reduced. At RP, there were only marginally significant effects (P = 0.06) of S. horneri presence on the local macroalgae community, and higher density, biomass, and diversity values were found when S. horneri was present. Most of the functional forms were found, even if the invasive alga was present. At both locations, the highest biomass corresponded to the articulated calcareous functional form. These contrasting results could be due to the fact that the native macroalgae community has already been altered by the early invasion of S. muticum, with the most resilient species and functional forms remaining in place. One of the most important changes we noticed is the severe reduction of the canopy forming species at both sites.
文摘This work gives an introduction to the R package NORRRM whose main purpose is to calculate the CIPW Norm. Although there are many softwares and spreadsheets available to estimate the standard mineral assemblages in igneous rocks, this package has the following advantages: a) it has the ability to be run on any operating computer systems (BSD, GNU/Linux, Mac OS X<sup>®</sup>, Windows<sup>®</sup>);b) an input argument allows choose different procedures to set the Fe-oxidation ratio;c) the options to use whole-rock major as well as minor oxides and trace elements in the computation;d) the output data yields highly consistent results achieving absolute match between the sum of the input weights of oxides recalculated on an anhydrous basis and the sum of the weights of estimated normative minerals and;e) the functions are written in R language and released under terms that guarantee users the freedom to study, adapt, modify, and distribute the software.
文摘The search for reliable and eco-friendly methods for the production of nanoscale materials is an important aspect of nanotechnology. Silver nanoparticles (AgNPs) are of special interest because of their antimicrobial properties, especially those of small size. In this work, AgNPs were produced under different conditions of temperature and pH using the extract from the fungus Neurospora crassa as reducing agent. Mainly quasi-spherical particles were obtained at all incubation conditions. However, optimum conditions to produce small sizes in the range of 2 - 9 nm were at 4°C and pH 3, also particles of 2 - 22 nm were obtained at 25°C with unmodified pH (6.5) and pH 10. Nevertheless, only particles synthesized at 25°C and pH 10 maintained the same size range after storage of 10 months. In summary, optimal incubation conditions for the synthesis of silver nanoparticles of small size range are reported. This improves the storage time of particles without losing its original size and without going into aggregation or agglomeration.
文摘The thermoregulatory behavior of sea hare Aplysia californica was determined in a horizontal thermal gradient;with a preferred temperature (PT) of 18.3°C for the day cycle and 20.8°C for the night cycle. The displacement velocity demonstrated an initial rate of 30 cm·hˉ1 and gradually the velocity diminished to 18 cm·hˉ1 with several fluctuations mainly at 02:00 am. Critical Temperature Maxima (CTMax refers to the temperature point where at least 50% of the experimental group have a loss of attachment) was measured at three acclimation temperatures (16°C, 19°C and 22°C). At the lowest acclimation temperature (16°C), 50% of the experimental group had an attachment loss at CTMax 32.7°C, and in a higher acclimation temperature (22°C) CTMax was 36.2°C. The Oxygen Consumption Rate (OCR) was closely correlated to acclimation temperature, and at 16°C and 19°C sea hare had a relatively stable metabolic rate, with OCR increasing to 9 mg O2 hˉ1·kgˉ1 w.w. in a higher acclimation temperature.
文摘Tsunamis in Mexico are a real threat, still unknown to many, mainly by people living in or visiting the coast. The Tsunami Warning Center in Mexico recently created （September 19, 2011） monitors earthquakes and sea level change caused by these same. Sea level on the west coast of the Mexican Pacific was analyzed after the occurrence of local, regional and distant earthquakes, in order to determine the existence of an anomaly due to the quake itself. Variations in sea level due to local registered earthquakes Mw 6.0 to 7.4 range was from 0.10 to 0.30 m; for regional earthquakes of Mw 7.3 and 8.2 were 0.12 and 0.22 m respectively and to the distant earthquake of Mw 8.0 recorded in Solomon Islands, the change in sea level of the maximum recorded was 0.20 m in Manzanillo, Colima. It is important to know that earthquakes whether local, regional or distant whose magnitudes are in the range specified here, did not present a risk to the Mexican coast, but do not rely, having to monitor variations in sea level that earthquakes can produce and be aware that you may perhaps occur as a tsunami in Indonesia in 2004 or Japan in 2011.
文摘Formulation of control objectives is a key issue in automatic control systems design. Although at first sight the desired goal （control objective） of a control system seems to be a trivial and obvious matter, for effectiveness of some high level robotic tasks, unusual exotic control objectives may be required. This paper presents a review of some exotic control objectives useful in robotics, such as velocity field control objective and range control objective. The paper also proposes a novel confinement control objective. The usefulness of these exotic control objectives may appear in safe robot-human interaction and self-protection of robots against collisions.
文摘This paper presents a study of amorphous SiO<sub>x</sub> thin films by means of Variable Angle Spectroscopic Ellipsometry (VASE) technique. Tauc Lorentz, Lorentz and Cauchy models have been used to obtain physical thickness and complex refractive index (n and k) from experimental data. In order to obtain a wide range to x stoichiometry values, the films were prepared by vacuum thermal evaporation of SiO on glass substrates, under different and controlled deposition conditions.
文摘Periodicity is common in natural processes, however, extraction tools are typically difficult and cumbersome to use. Here we report a computational method developed in MATLAB through a function called Periods with the aim to find the main harmonic components of time series data. This function is designed to obtain the period, amplitude and lag phase of the main harmonic components in a time series (Periods and lag phase components can be related to climate, social or economic events). It is based on methods of periodic regression with cyclic descent and includes statistical significance testing. The proposed method is very easy to use. Furthermore, it does not require full understanding of time series theory, nor require many inputs from the user. However, it is sufficiently flexible to undertake more complex tasks such as forecasting. Additionally, based on previous knowledge, specific periods can be included or excluded easily. The output results are organized into two groups. One contains the parameters of the adjusted model and their F statistics. The other consists of the harmonic parameters that best fit the original series according to their importance and the summarized statistics of the comparisons between successive models in the cyclic descent process. Periods is tested with both, simulated and actual sunspot and Multivariate ENSO Index data to show its performance and accuracy.
基金supported by CONACyT(Mexican Council of Science)through a PhD scholarship(No.384224)funded by projects SIMAC-CONACYT,SIMAC-2000107017+1 种基金CICESE:Ecological monitoring of the Upper Gulf of California”(PANGAS-Packard Foundation)IPN-CICIMAR:SIP 1721,20160514-CONACYT:236864.
文摘Variability of the optical properties of the northern Gulf of California (México) were analyzed for the first time based on six cruises performed from spring to summer (March to September) between 2008 and 2013. The changes observed in the absorption by three seawater components (phytoplankton, detritus and chromophoric dissolved organic matter or CDOM) were analyzed in relation to changes in bio-optical regions and composition of the phytoplankton community (determined based on phytoplankton pigments). Two regions with unique bio-optical characteristics were identified separated by a narrow transition zone: the Upper Gulf of California (UGC) and Northern Gulf of California (NGC). Despite the temporal changes in their spatial distribution they maintained particular characteristic. UGC is characterized by an average Chla of 1.78 mg/m3, the dominance of microphytoplankton (diatoms and dinoflagellates) and a stronger contribution of detritus to total light absorption. NGC is characterized by an average Chla of 0.7 mg/m3 and the predominance of picophytoplankton, characterized by the dominance of zeaxanthin (marker pigment for cyanobacteria) and/or chlorophyll b (marker pigment for green algae), along with a co-dominium by CDOM and phytoplankton to light absorption. Results indicate that Case II waters can be very different when evaluating the individual contribution by phytoplankton, detritus and CDOM to total light absorption what has to be considered for the selection of bio-optical models for each specific region what can also help to a better definition of the related uncertainties.
基金LAEP thanks the Consejo Nacional de Humanidades,Ciencias y Tecnologías(CONAHCYT)for granting him a Ph.D.scholarship.Special thanks to Victor Chashchin,Jean-Clair Duchesne,and Mike Hamilton for sharing valuable articles and published data during the development of datAMCG.This paper contributes to the Conacyt Ciencia de Frontera grant 7351 funded to LAS.HLH is funded by the National Natural Science Foundation of China(Grant No.42272227)。
文摘The occurrence of massif-type anorthosite intrusions is a widespread Proterozoic phenomenon.They are usually associated with gabbroic,charnockitic,and granitic rocks,comprising the so-called anorthositemangerite-charnockite-granite(AMCG)suite.Although these rocks have been extensively studied worldwide,several aspects concerning their formation remain unsettled.Among them,the magma source and the tectonic setting are the most important.To evaluate these issues,we first compiled geochemical and isotopic data of Proterozoic anorthosite massifs and AMCG suites worldwide and stored it in a database named datAMCG.This plethora of data allows us to make some important interpretations.We argue that the wide-ranging multi-isotopic composition of this group of rocks reflects varying proportions of juvenile mantle-derived melts and crustal components.We interpret that the precursor magmas of most massive anorthosite bodies and associated mafic rocks have a mantle-dominated origin.However,we highlight that a crustal component is indispensable to generate these lithologies.Adding variable amounts of this material during succeeding multi-stage assimilation-fractional crystallization(AFC)processes gives these intrusions their typical mantle-crustal hybrid isotopic traits.In contrast,a crustaldominant origin with a complementary mantle component is interpreted for most MCG rocks.In summary,the isotopic information in datAMCG indicates that both sources are necessary to generate AMCG rocks.Therefore,we suggest that hybridized magmas with different mantle-crust proportions originate these rocks.This interpretation might offer a more nuanced and accurate depiction of this phenomenon in future work instead of choosing a single-sourced model as in the past decades.Finally,tectonomagmatic diagrams suggest that the rocks under study were likely generated in a tectonic environment that transitioned between collision and post-collisional extension,sometimes involving subduction-modified mantle sources.This interpretation is supported by geological and geochronological information from most complexes,thus challenging the Andean-type margins as an ideal tectonic setting.
基金funded by the SENER-CONACYT Hydrocarbon Fund project N020,144(Mexico).
文摘Glider-based microstructure observations combined with ship-based conductivity-temperature-depth profiles were collected on the western part of the Gulf of Mexico(GoM),within the steep continental slope region in November 2017.Dynamical processes associated with bathymetry were observed,and enhanced mixing along the continental slope was detected,with diffusivity values as high as 10^(-3) m^(2)/s.Recent studies proposed a conceptual model of deep GoM circulation where deep water entering the GoM sinks and fills the deep GoM through the Yucatan Channel.We hypothesize that to retain mass balance,this continuously supplied deep water has to upwell and create intermediate water,which forms the outflow of the GoM,ventilating the deep GoM on time scales of~100 years.The western GoM has areas with steep continental slopes,where enhanced mixing likely results in the transformation and upwelling of deep water.
基金Consejo Nacional de Ciencia y Tecnologia(250719,252621,2417,461).
文摘We present a new design of a plasmonic Luneburg lens made from a gradient-index metasurface that was constructed with an array of nanometer-sized holes in a dielectric thin film. The fabricated structure consists of a planar lens with a diameter of 8.7 μm composed of a rectangular array of holes with a periodicity of 300 nm. The experimental characterization includes leakage-radiation microscopy imaging in the direction and frequency space. The former allows for characterization of the point spread function and phase distribution,whereas the latter grants access to qualitative measurements of the effective mode indices inside the plasmonic lens. The experimental results presented here are in good agreement with the expected average performance predicted by the numerical calculations. Nevertheless, the robustness of the characterization techniques presented here is also exploited to determine deviations from the design parameters.
基金supported in part by EPSRC(UK)and ERC(project 789340)the support by a TAU Rector Grant and the German-Israeli Foundation(GIF,grant number 2399)support from the Royal Society and the Wolfson Foundation.
文摘The optical theorem,which is a consequence of the energy conservation in scattering processes,directly relates the forward scattering amplitude to the extinction cross-section of the object.Originally derived for planar scalar waves,it neglects the complex structure of the focused beams and the vectorial nature of the electromagnetic field.On the other hand,radially or azimuthally polarized fields and various vortex beams,essential in modern photonic technologies,possess a prominent vectorial field structure.Here,we experimentally demonstrate a complete violation of the commonly used form of the optical theorem for radially polarized beams at both visible and microwave frequencies.We show that a plasmonic particle illuminated by such a beam exhibits strong extinction,while the scattering in the forward direction is zero.The generalized formulation of the optical theorem provides agreement with the observed results.The reported effect is vital for the understanding and design of the interaction of complex vector beams carrying longitudinal field components with subwavelength objects important in imaging,communications,nanoparticle manipulation,and detection,as well as metrology.
基金Supported by FOMIX-BC No.682210 to Center for Scientific Research and Higher Education of Ensenada(CICESE).
文摘Objective:To examine the immune responses of Litopenaeus vannamei after different treatments with a hot water extract of Macrocystis pyrifera(M.pyrifera)and a subsequent challenge with Vibrio campbellii(V.campbellii).Methods:A total of 184 adult white shrimp that were infected with V.campbellii(1×10^(6) CFU/shrimp)were immunostimulate by the hot-water extract from M.pyrifera via either injection(10μg)or immersion(350 mg/L),the experimental controls were injected with either saline solution or V.campbellii(1×10^(6) CFU/shrimp).The bacterial DNA depuration rate,antimicrobial activity and total hemocyte count were evaluated in hemolymph samples at 2,6,12,24,48 and 72 h post-infection.Results:Injected shrimp(10μg M.pyrifera extract)demonstrated the best clearance of bacterial infection,with 82%survival at 72 h post-infection(cellular response).Hemolymph from the immersed organisms had the best antimicrobial activity against Escherichia coli growth;specifically,the most efficient antimicrobial activity was observed at 24 h post-infection.Both types of immunostimulated shrimp had similar total hemocyte counts at 24 h post-infection(1.63-1.59 million/mL);however,after 72 h,injected shrimp had higher total hemocyte counts than immersed animals(2.59 v.s.0.56 million/mL).Conclusions:The injection of the M.pyrifera hot-water extract facilitated a more efficient response to V.campbellii infection due to the stimulation of the hemocytes of the shrimp.In other words,the cellular immune response was more efficient to eliminate bacterial infection than the humoral response in shrimp.
基金Funding for this work was provided by CONACYT Grant No.A1-S-23107。
文摘Nearly 80%of the seafloor extension has not been covered by high-resolution bathymetry,impeding direct observation of seamounts.Nevertheless,lists of seamount location and height at a global scale have been produced using different techniques.In this work four of such databases(publicly available)are compared with each other to assess their differences.Results identify large differences among databases that could have exerted strong influences on models of seamount production and associated geodynamic processes.Despite those differences,it is shown that all databases allow the identification of seamount lines both along the present-day Mid Ocean Ridge(MOR)system and on intraplate settings.Notably,those seamount lines do not coincide with the so-called hotspot tracks that commonly were defined by selectively focusing attention on the larger seamounts.Examination of all the databases also shows that distinction based only on seamount size between seamounts produced at Mid-Ocean Ridge(MOR)environments from those associated with mantle-plum fed-hotspot activity has been overestimated.This,combined with the fact that most seamount lines defined by the available databases can be traced back to past locations of MOR indicates that most of the present-day intraplate linear arrays of seamounts,which include some large seamounts,were not produced by the action of underlying mantle anomalies envisaged in the form of mantle plumes.The evidence presented here calls for a reassessment of the form in which volcanic and tectonic activities are conceptually related to each other.
文摘In this Letter,a Gabor superlens with variable focus is presen ted.This configuration uses tunable liquid lenses in the third microlens array of the Gabor superlens.By applying voltage,the radius of curvature of the microtunable doublet arrays changes,and the Gabor conditions are fulfilled at different focal planes.As a consequence,the magnification of the image at the focal planes changes,and a zoom effect is observed.The marginal depth plane for this system goes from 0.86 to 0.89 mm.The optical simulation,calculations,and results of the simulated optical system performance are presented.
