Showing papers by "Ensenada Center for Scientific Research and Higher Education published in 2014"

Changes in extremes and hydroclimatic regimes in the CREMA ensemble projections

Abstract: We analyze changes of four extreme hydroclimatic indices in the RCP8.5 projections of the Phase I CREMA experiment, which includes 21st century projections over 5 CORDEX domains (Africa, Central America, South America, South Asia, Mediterranean) with the ICTP regional model RegCM4 driven by three CMIP5 global models. The indices are: Heat Wave Day Index (HWD), Maximum Consecutive Dry Day index (CDD), fraction of precipitation above the 95th intensity percentile (R95) and Hydroclimatic Intensity index (HY-INT). Comparison with coarse (GPCP) and high (TRMM) resolution daily precipitation data for the present day conditions shows that the precipitation intensity distributions from the GCMs are close to the GPCP data, while the RegCM4 ones are closer to TRMM, illustrating the added value of the increased resolution of the regional model. All global and regional model simulations project predominant increases in HWD, CDD, R95 and HY-INT, implying a regime shift towards more intense, less frequent rain events and increasing risk of heat wave, drought and flood with global warming. However, the magnitudes of the changes are generally larger in the global than the regional models, likely because of the relatively low “climate sensitivity” of the RegCM4, especially when using the CLM land surface scheme. In addition, pronounced regional differences in the change signals are found. The data from these simulations are available for use in impact assessment studies.

Ultrastructural analysis of Candida albicans when exposed to silver nanoparticles.

Abstract: Candida albicans is the most common fungal pathogen in humans, and recently some studies have reported the antifungal activity of silver nanoparticles (AgNPs) against some Candida species. However, ultrastructural analyses on the interaction of AgNPs with these microorganisms have not been reported. In this work we evaluated the effect of AgNPs on C. albicans, and the minimum inhibitory concentration (MIC) was found to have a fungicidal effect. The IC50 was also determined, and the use of AgNPs with fluconazole (FLC), a fungistatic drug, reduced cell proliferation. In order to understand how AgNPs interact with living cells, the ultrastructural distribution of AgNPs in this fungus was determined. Transmission electron microscopy (TEM) analysis revealed a high accumulation of AgNPs outside the cells but also smaller nanoparticles (NPs) localized throughout the cytoplasm. Energy dispersive spectroscopy (EDS) analysis confirmed the presence of intracellular silver. From our results it is assumed that AgNPs used in this study do not penetrate the cell, but instead release silver ions that infiltrate into the cell leading to the formation of NPs through reduction by organic compounds present in the cell wall and cytoplasm.

Hot spots, hot moments, and spatio-temporal controls on soil CO2 efflux in a water-limited ecosystem

Abstract: Soil CO2 efflux is the primary source of CO2 emissions from terrestrial ecosystems to the atmosphere. The rates of this flux vary in time and space producing hot moments (sudden temporal high fluxes) and hot spots (spatially defined high fluxes), but these high reaction rates are rarely studied in conjunction with each other. We studied temporal and spatial variation of soil CO2 efflux in a water-limited Mediterranean ecosystem in Baja California, Mexico. Soil CO2 efflux increased 522% during a hot moment after rewetting of soils following dry summer months. Monthly precipitation was the primary driver of the seasonal trend of soil CO2 efflux (including the hot moment) and through changes in soil volumetric water content (VWC) it influenced the relationship between CO2 efflux and soil temperature. Geostatistical analyses showed that the spatial dependence of soil CO2 efflux changed between two contrasting seasons (dry and wet). During the dry season high soil VWC was associated with high soil CO2 efflux, and during the wet season the emergence of a hot spot of soil CO2 efflux was associated with higher root biomass and leaf area index. These results suggest that sampling designs should accommodate for changes in spatial dependence of measured variables. The spatio-temporal relationships identified in this study are arguably different from temperate ecosystems where the majority of soil CO2 efflux research has been done. This study provides evidence of the complexity of the mechanisms controlling the spatio-temporal variability of soil CO2 efflux in water-limited ecosystems.

Seasonal overturning circulation in the Red Sea: 2. Winter circulation

Abstract: Author Posting. ©0American Geophysical Union, 2014. This article is posted here by permission of [American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 2263–2289, doi:10.1002/2013JC009331.

Algal and Microbial Exopolysaccharides: New Insights as Biosurfactants and Bioemulsifiers

Abstract: Currently, efforts are being made to utilize more natural biological systems as alternatives as a way to replace fossil forms of carbon. There is a growing concern at global level to have nontoxic, nonhazardous surface-active agents; contrary to synthetic surfactants, their biological counterparts or biosurfactants play a primary function, facilitating microbial presence in environments dominated by hydrophilic-hydrophobic interfaces. Algal and microbial biosurfactants/bioemulsifiers from marine and deep-sea environments are attracting major interest due to their structural and functional diversity as molecules actives of surface and an alternative biomass to replace fossil forms of carbon. Algal and microbial surfactants are lipid in nature and classified as glycolipids, phospholipids, lipopeptides, natural lipids, fatty acids, and lipopolysaccharides. These metabolic bioactive products are applicable in a number of industries and processes, viz., food processing, pharmacology, and bioremediation of oil-polluted environments. This chapter presents an update of the progress and potentialities of the principal producers of exopolysaccharide (EPS)-type biosurfactants and bioemulsifiers, viz., macro- and microalgae (cyanobacteria and diatoms) and bacteria from marine and extreme environments. Particular interest is centered into new sources and applications, viz., marine and deep-sea environments and promissory uses of these EPSs as biosurfactants/emulsifiers and other polymeric roles. The enormous benefits of these molecules encourage their discovery, exploitation, and development of new microbial EPSs that could possess novel industrial importance and corresponding innovations.

Wireless Sensing of Complex Dielectric Permittivity of Liquids Based on the RFID

Abstract: A wireless sensing system for the evaluation of the complex dielectric permittivity of solvent liquids is presented. Two sensing tags are proposed for testing of the samples. The first tag is based on a cavity resonator and the second makes use of the epsilon-near-zero effect. Both circuits are designed over the planar substrate-integrated-waveguide (SIW) technology, and operate at 4 GHz. A quartz capillary tube is used for the liquid measurements where only a small amount of sample volume is required. With the addition of planar antennas at the input and output of the sensors, the complete system is implemented for wireless sensing of the materials following the RF identification scheme. The cavity perturbation technique for SIW structures is applied for the dielectric liquid characterization. The proposed sensing tags and system have high potentials for low-cost wireless measurements and real-time monitoring applications.

Tell me your apps and I will tell you your mood: correlation of apps usage with bipolar disorder state

Abstract: Bipolar Disorder is a disease that is manifested with cycling periods of polar episodes, namely mania and depression. Depressive episodes are manifested through disturbed mood, psychomotor retardation, behaviour change, decrease in energy levels and length of sleep. Manic episodes are manifested through elevated mood, psychomotor acceleration and increase in intensity of social interactions. In this paper we report results of a clinical trial with bipolar patients that amongst other aspects, investigated whether changes in general behaviour of patients due to onset of a bipolar episode, can be captured through the analysis of smartphone usage. We have analysed changes in smartphone usage, specifically app usage and how these changes correlate with the self-reported patient state. We also used psychiatric evaluation scores provided by the clinic to understand correlation of the patient smartphone behaviour before the psychiatric evaluation and after the psychiatric evaluation. The results show that patients have strong correlation of patterns of app usage with different aspects of their self-reported state including mood, sleep and irritability. While, on the other hand, the patients' application usage shows discernable changes in the period before and after psychiatric evaluation.

SensoryPaint: a multimodal sensory intervention for children with neurodevelopmental disorders

Abstract: Multimodal and natural user interfaces offer an innovative approach to sensory integration therapies. We designed and developed SensoryPaint, a multimodal system that allows users to paint on a large display using physical objects, body-based interactions, and interactive audio. We evaluated the impact of SensoryPaint through two user studies: a lab-based study of 15 children with neurodevelopmental disorders in which they used the system for up to one hour, and a deployment study with four children with autism, during which the system was integrated into existing daily sensory therapy sessions. Our results demonstrate that a multimodal large display, using whole body interactions combined with tangible interactions and interactive audio feedback, balances children's attention between their own bodies and sensory stimuli, augments existing therapies, and promotes socialization. These results offer implications for the design of other ubicomp systems for children with neurodevelopmental disorders and for their integration into therapeutic interventions.

Optimization of legacy lidar data sets for measuring near‐field earthquake displacements

Abstract: Airborne lidar (light detection and ranging) topography, acquired before and after an earthquake, can provide an estimate of the coseismic surface displacement field by differencing the preevent and postevent lidar point clouds. However, estimated displacements can be contaminated by the presence of large systematic errors in either of the point clouds. We present three-dimensional displacements obtained by differencing airborne lidar point clouds collected before and after the El Mayor–Cucapah earthquake, a Mw 7.2 earthquake that occurred in 2010. The original surface displacement estimates contained large, periodic artifacts caused by systematic errors in the preevent lidar data. Reprocessing the preevent data, detailed herein, removed a majority of these systematic errors that were largely due to misalignment between the scanning mirror and the outgoing laser beam. The methodology presented can be applied to other legacy airborne laser scanning data sets in order to improve change estimates from temporally spaced lidar acquisitions.

Correlating the Arperos Basin from Guanajuato, central Mexico, to Santo Tomás, southern Mexico: Implications for the paleogeography and origin of the Guerrero terrane

Abstract: The Guerrero terrane has been interpreted either as a Mesozoic Pacific multi-arc system accreted to North America, or as a detached slice of the North American continental margin, which was rifted during backarc spreading and subsequently accreted back to the continental mainland. In order to test these two scenarios, we present here a petrologic study of metasandstones from the Santo Tomas area, southern Mexico. Our data document that the Guerrero terrane suture belt contains the remnants of the Tithonian–Cenomanian Arperos Basin. This basin displays a marked provenance asymmetry. Its eastern margin is composed of metasedimentary rocks derived from sources in the North American continental mainland, whereas its western margin consists of a metasedimentary succession derived from volcanic sources of the Guerrero terrane. Sedimentation in the Arperos Basin was coeval with the emplacement of Tithonian–Barremian felsic dikes and lava flows with volcanogenic massive sulfide deposits and Aptian–Cenomanian intraplate-like and mid-ocean ridge basalts. This suggests that the Arperos Basin evolved progressively from continentally to oceanic floored during the Early Cretaceous and that a mature oceanic crust was generated only ca. 15 Ma before the accretion of the Guerrero terrane, which took place in the late Cenomanian. On the basis of this evidence, we favor a North American origin for the Guerrero terrane, which is then considered to represent a west-facing North American arc that was rifted from the continental mainland during backarc spreading and subsequently accreted back to nuclear Mexico.

Aerobic oxidation of benzyl alcohol in methanol solutions over Au nanoparticles: Mg(OH)2 vs MgO as the support

Abstract: Magnesium oxide and magnesium hydroxide materials containing supported gold nanoparticles (NPs), Au/Mg(OH) 2 and Au/MgO, were prepared from the commercial MgO through the deposition–precipitation (DP) method and characterized by XRD, XPS, HRTEM, FTIR spectroscopy and N 2 adsorption techniques. It was found that the starting MgO support was fully transformed into the Mg(OH) 2 phase during the DP procedure. A nearly complete dehydration of the magnesium hydroxide and formation of Au/MgO was achieved through the reductive treatment at 500 °C, whereas the treatment at 350 °C still resulted in the Au/Mg(OH) 2 material. The FTIR analysis showed a much higher ability of the Au/MgO surface to adsorb both benzyl alcohol and benzaldehyde (ca. 10 and 3 times, respectively), as compared to Au/Mg(OH) 2 . Probably for this reason, the Au/MgO catalyst exhibited ca. 50% higher catalytic activity in the aerobic oxidation/oxidative methoxylation of benzyl alcohol in the methanol solutions with respect to the amount of surface gold atoms as compared to the Au/Mg(OH) 2 catalyst, in spite of a larger size of the Au NPs. In addition, the thermal treatment of the catalyst at 500 °C to dehydrate the support allowed to suppress the undesired side reaction between benzyl alcohol and primarily formed benzaldehyde to give benzyl benzoate.

Assessment of RegCM4 simulated inter-annual variability and daily-scale statistics of temperature and precipitation over Mexico

Abstract: The skill of a regional climate model (RegCM4) in capturing the mean patterns, interannual variability and extreme statistics of daily-scale temperature and precipitation events over Mexico is assessed through a comparison of observations and a 27-year long simulation driven by reanalyses of observations covering the Central America CORDEX domain. The analysis also includes the simulation of tropical cyclones. It is found that RegCM4 reproduces adequately the mean spatial patterns of seasonal precipitation and temperature, along with the associated interannual variability characteristics. The main model bias is an overestimation of precipitation in mountainous regions. The 5 and 95 percentiles of daily temperature, as well as the maximum dry spell length are realistically simulated. The simulated distribution of precipitation events as well as the 95 percentile of precipitation shows a wet bias in topographically complex regions. Based on a simple detection method, the model produces realistic tropical cyclone distributions even at its relatively coarse resolution (dx = 50 km), although the number of cyclone days is underestimated over the Pacific and somewhat overestimated over the Atlantic and Caribbean basins. Overall, it is assessed that the performance of RegCM4 over Mexico is of sufficient quality to study not only mean precipitation and temperature patterns, but also higher order climate statistics.

Understanding harmful algae in stratified systems: Review of progress and future directions

Abstract: The Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) program of the Scientific Committee on Oceanic Research (SCOR) and the Intergovernmental Oceanographic Commission (IOC) of UNESCO, was created in 1999 to foster research on the ecological and oceanographic mechanisms underlying the population dynamics of harmful algal blooms (HABs). The ultimate goal of this research is to develop observational systems and models that will eventually enable the prediction of HABs and thereby minimize their impact on marine ecosystems, human health and economic activities. In August of 2012, a workshop was held under the umbrella of the GEOHAB program at the Monterey Bay Aquarium Research Institute (MBARI). The over arching goal of this workshop was to review the current understanding of the processes governing the structure and dynamics of HABs in stratified systems, and to identify how best to couple physical/chemical and biological measurements at appropriate spatial and temporal scales to quantify the dynamics of HABs in these systems, paying particular attention to thin layers. This contribution provides a review of recent progress in the field of HAB research in stratified systems including thin layers, and identifies the gaps in knowledge that our scientific community should strive to understand in the next decade. (C) 2013 Elsevier Ltd. All rights reserved.

CDC-42 and RAC-1 regulate opposite chemotropisms in Neurospora crassa.

Abstract: Cell polarization and fusion are crucial developmental processes that occur in response to intracellular and extracellular signals. Asexual spores (conidia) of the mold Neurospora crassa differentiate two types of polarized cell protrusions, germ tubes and conidial anastomosis tubes (CATs), which exhibit negative and positive chemotropism, respectively. We provide the first evidence that shared and separate functions of the Rho-type GTPases CDC-42 and RAC-1 regulate these opposite chemotropisms. We demonstrate that RAC-1 is essential for CAT formation and cell fusion, whereas CDC-42 is necessary and sufficient for normal germ tube development. Cdc42-Rac-interactive-binding (CRIB) reporters were constructed to exclusively label locally activated GTP-bound GTPases. Time course analyses showed that repositioning of these activated GTPase clusters within germ tube and CAT tip apices controls directional growth in the absence of a tip-localized vesicle supply center (Spitzenkorper). We propose a model in which the local assembly of a plasma-membrane-associated GTPase-PAK-MAPK signaling platform regulates chemoattractant perception and secretion in order to synchronize oscillatory cell-cell communication and directional CAT tip growth.

Artificial Neural Network Model of SOS-MOSFETs Based on Dynamic Large-Signal Measurements

Abstract: A measurement-based quasi-static nonlinear field-effect transistor (FET) model relying on an artificial neural network (ANN) approach and using real-time active load-pull (RTALP) measurement data for the model extraction is presented for an SOS-MOSFET. The efficient phase sweeping of the RTALP drastically reduces the number of large-signal measurements needed for the model development and verification while maintaining the same intrinsic voltage coverage as in conventional passive or active load-pull systems. Memory effects associated with the parasitic bipolar junction transistor (BJT) in the SOS-MOSFET are accounted for by using a physical circuit topology together with the simultaneous ANN extraction of: 1) the intrinsic FET current-voltage characteristics; 2) the intrinsic charges of the FET; and 3) the BJT dc characteristics, all from the same modulated large-signal RF data. The verification of the model using load-lines, output power, power efficiency, and load-pull, which is performed using two additional independent RTALP measurements, demonstrates that a reasonably accurate large-signal RF device model accounting for memory effects can be extracted from a single 10.5-ms RTALP measurement with a physically based ANN model.

Inhibition of pathogenic Vibrio by the microalgae Isochrysis galbana

Abstract: Vibrio alginolyticus, Vibrio campbellii, and Vibrio harveyi were inhibited by Isochrysis galbana in batch cultures. I. galbana reduced the V. alginolyticus, V. campbellii, and V. harveyi counts to undetectable levels in 2, 4, and 7 days ( 82 %) of I. galbana during the stationary growth phase were estearidonic (24.3 %), oleic (15.7 %), myristic (13.8 %), docosahexaenoic (11.0 %), palmitic (10.3 %), and α-linolenic (7.2 %) acids. These results demonstrate that I. galbana synthesizes antibacterial fatty acids that inhibit the growth of pathogenic bacteria such as V. alginolyticus, V. campbellii, and V. harveyi.

Surface circulation in the Gulf of California in summer from surface drifters and satellite images (2004–2006)

Abstract: Surface drifters released in the Gulf of California between June 2004 and August 2006 are used to describe the surface circulation in late spring and summer. In the June to September mean, there was a poleward coastal current on the shelf and slope of the mainland side of the Gulf, with mean speed ∼0.3 m/s; it reached the northern Gulf and joined the cyclonic circulation typical of this zone in summer. In the western half of the southern Gulf, the drifters presented recirculating currents that are due to mesoscale eddies that appear to dominate the surface circulation in summer. In June 2004, the coastal current presented an enhancement event with mean speed around 0.60 m/s and maximum ∼0.80 m/s. It took ∼20 days for a particular drifter to travel the 1000 km from the Gulf entrance to the head. This strengthening of the coastal current was apparent in chlorophyll a and SST satellite images, the drifters following closely the intrusion of warm, chlorophyll-poor surface water from outside the Gulf. The drifters and the satellite images suggest that the current-enhancement event lasted less than a month. This mesoscale event was linked with a mesoscale remote forcing in the tropical Pacific coast and with a mesoscale local forcing of the wind. These events seem to occur every year, and are probably important in carrying organisms and properties from the entrance to the whole length of the Gulf.

Pulling apart the Mid to Late Cenozoic magmatic record of the Gulf of California: is there a Comondú Arc?

Abstract: The composition of the lithosphere can be fundamentally altered by long-lived subduction processes such that subduction-modified lithosphere can survive for 100's Myrs. Incorrect petrotectonic interpretations result when spatial-temporal-compositional trends of, and source contributions to, magmatism are not properly considered. Western Mexico has had protracted Cenozoic magmatism developed mostly in-board of active oceanic plate subduction beneath western North America. A broad range of igneous compositions from basalt to high-silica rhyolite were erupted with intermediate to silicic compositions in particular, showing calc-alkaline and other typical subduction-related geochemical signatures. A major Oligocene rhyolitic ignimbrite “flare-up” (>300,000 km3) switched to a bimodal volcanic phase in the Early Miocene (~100,000 km3), associated with distributed extension and opening of numerous grabens. Extension became more focussed ~18 Ma resulting in localised volcanic activity along the future site of the Gulf of California. This localised volcanism (known as the Comondu “arc”) was dominantly effusive and andesite-dacite in composition. Past tectonic interpretations of Comondu-age volcanism may have been incorrect as these regional temporal-compositional changes are alternatively interpreted as a result of increased mixing of mantle-derived basaltic and crust-derived rhyolitic magmas in an active rift environment rather than fluid flux melting of the mantle wedge above the subducting Guadalupe Plate.

Limits to the sensitivity of living benthic foraminifera to pore water carbon isotope anomalies in methane vent environments

Abstract: Episodic 13C depletions in the carbon isotopic composition of benthic foraminiferal tests preserved in the stratigraphic record have been interpreted as an active incorporation of methane-derived carbon. Understanding the extent to which these isotope excursions reflect basin-wide fluxes of methane carbon to bottom waters versus a local supply of methane carbon within the sediments in which benthic foraminifera live, or a postmortem diagenetic imprint is critical to the interpretation of δ13C paleoceanographic proxies. Here we evaluate the impact of chemical gradients measured in pore waters adjacent to active methane vents on carbon assimilation by living benthic foraminifera and show that those living near methane vents do not assimilate the distinctly 13C depleted methane-derived dissolved inorganic carbon into their tests from the pore water in which they were found. Our observations can be explained by the recently articulated physiological limits imposed on deep-sea fauna by low-oxygen and high-pCO2 environments. Understanding the importance of the different processes involved in the observed disequilibrium between the carbon isotopic composition of the benthic forams and the pore waters where they were found has important implications on the reliability of carbon isotopic composition of benthic foraminifera for paleoceanographic reconstructions. In particular, the observation on the inhospitability of these environments for benthic foraminifera at least for reproduction and growth raises the issue on the overprint either in the late adult stages of foraminifera that grew in a different neighboring environment or during early diagenesis in these geochemically active environments.

On the boundary control of coupled reaction-diffusion equations having the same diffusivity parameters

Abstract: We consider the problem of boundary stabilization for a system of n coupled parabolic linear PDEs. Particularly, we design a state feedback law with actuation on only one end of the domain and prove exponential stability of the closed-loop system with an arbitrarily fast convergence rate. The backstepping method is used for controller design, and the transformation kernel matrix is derived in explicit form of series of matrix Bessel functions by using the method of successive approximations to solve the corresponding PDE. Thus, the proposed control law becomes available in explicit form. Simulation results support the effectiveness of the suggested design.

Smart objects to support the discrimination training of children with autism

Abstract: Teachers spend considerable amount of time keeping students with autism "on task" giving away prompts and rewards and maintaining a detailed record of students' progress during the object discrimination training. We hypothesize that tangible computing, in particular smart objects, could help teachers cope with the problems faced during the object discrimination training of students with autism. In this paper, we describe design principles for smart objects to support the object discrimination training and present several example prototypes. First, we present the design and implementation of "Things that think" (T3), a smart device that converts traditional objects into smart objects that promote interactivity with a playful and engaging interaction, and are capable of the automatic recording of students' progress. Then, we present four T3 smart objects assembled in a board. The results of a 7-week deployment study of the use of such smart objects in three classrooms of students with autism (n = 25, 7 teachers and 18 students with autism) demonstrate T3 smart objects reduce the workload of teachers, ease the record-keeping and increase its reliability, and reduce students' behavioral problems while improving their cognitive efficacy. We close discussing directions for future work.

Anxiety detection using wearable monitoring

Abstract: Social Anxiety Disorder (SAD) might be confused with shyness. However, experiencing anxiety can have profound short and long-term implications. During an anxiety span, the subject suffers from blushing, sweating or trembling. Social activities are harder to accomplish and the subject might tend to avoid them. Although there are tested methods to treat SAD such as Exposure Therapy (ET) and Pharmacotherapy, patients do not treat themselves or suspend treatment due economic, time or space barriers. Wearable computing technologies can be used to constantyly monitor user context offering the possibility to detect anxiety spans. In this work we used Google Glass and the Zephyr HxM Bluetooth band to monitor Spontaneous Blink Rate (SBR) and Heart Rate (HR) respectively. We conducted an experiment that involved 8 subjects in two groups: Mild SAD and No SAD. The experiment consisted on an induced anxiety situation where each participant gave a 10 minutes speech in front of 2 professors. We found higher average heart rates after induced anxiety spans on the mild SAD group. However, we found no evidence of increased SBR as an anxiety indicator. These results indicate that wearable devices can be used to detect anxiety.

Hybrid Sparse Linear Array Synthesis Applied to Phased Antenna Arrays

Abstract: In this letter, a new hybrid technique to synthesize sparse linear arrays is proposed. This technique is based on the combination of two methods. As a first method, a deterministic synthesis algorithm is used to resolve the nonuniform amplitude excitations and the antenna element locations. Then, the second method is an iterative optimization scheme that computes the phase of the excitation currents. This approach is proven valid to properly match diverse beam patterns (narrow-beam, flat-top, and square-cosecant) with sparse linear arrays. Three numerical experiments are reported that show the performance of the proposed technique and compare it to other outstanding methods available in the literature.