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1.  Temperature Measurement in WTE Boilers Using Suction Pyrometers 
Sensors (Basel, Switzerland)  2013;13(11):15633-15655.
The temperature of the flue-gas in the post combustion zone of a waste to energy (WTE) plant has to be maintained within a fairly narrow range of values, the minimum of which is prescribed by the European Waste Directive 2000/76/CE, whereas the maximum value must be such as to ensure the preservation of the materials and the energy efficiency of the plant. A high degree of accuracy in measuring and controlling the aforementioned temperature is therefore required. In almost the totality of WTE plants this measurement process is carried out by using practical industrial thermometers, such as bare thermocouples and infrared radiation (IR) pyrometers, even if affected by different physical contributions which can make the gas temperature measurements incorrect. The objective of this paper is to analyze errors and uncertainties that can arise when using a bare thermocouple or an IR pyrometer in a WTE plant and to provide a method for the in situ calibration of these industrial sensors through the use of suction pyrometers. The paper describes principle of operation, design, and uncertainty contributions of suction pyrometers, it also provides the best estimation of the flue-gas temperature in the post combustion zone of a WTE plant and the estimation of its expanded uncertainty.
doi:10.3390/s131115633
PMCID: PMC3871099  PMID: 24248279
temperature measurement; waste-to-energy plants; uncertainty; suction pyrometers
2.  Searching for signatures of life on Mars: an Fe-isotope perspective 
Recent spacecraft and lander missions to Mars have reinforced previous interpretations that Mars was a wet and warm planet in the geological past. The role of liquid water in shaping many of the surface features on Mars has long been recognized. Since the presence of liquid water is essential for survival of life, conditions on early Mars might have been more favourable for the emergence and evolution of life. Until a sample return mission to Mars, one of the ways of studying the past environmental conditions on Mars is through chemical and isotopic studies of Martian meteorites. Over 35 individual meteorite samples, believed to have originated on Mars, are now available for lab-based studies. Fe is a key element that is present in both primary and secondary minerals in the Martian meteorites. Fe-isotope ratios can be fractionated by low-temperature processes which includes biological activity. Experimental investigations of Fe reduction and oxidation by bacteria have produced large fractionation in Fe-isotope ratios. Hence, it is considered likely that if there is/were any form of life present on Mars then it might be possible to detect its signature by Fe-isotope studies of Martian meteorites. In the present study, we have analysed a number of Martian meteorites for their bulk-Fe-isotope composition. In addition, a set of terrestrial analogue material has also been analysed to compare the results and draw inferences. So far, our studies have not found any measurable Fe-isotopic fractionation in bulk Martian meteorites that can be ascribed to any low-temperature process operative on Mars.
doi:10.1098/rstb.2006.1899
PMCID: PMC1664681  PMID: 17008212
Mars; Martian meteorites; SNC; terrestrial analogues; iron isotopes; life
3.  Medipix in space on-board the ISS 
Journal of Radiation Research  2014;55(Suppl 1):i62-i63.
On 16 October 2012, five active radiation detectors (referred to by NASA as Radiation Environment Monitors, or REMs) employing the Timepix version of the technology developed by the CERN-based Medipix2 Collaboration were deployed on-board the International Space Station (ISS) using simple USB interfaces to the existing ISS laptops for power, control and readout [ 1– 3]. These devices successfully demonstrated the capabilities of this technology by providing reliable dose and dose-equivalent information based on a track-by-track analysis. Figure 1 shows a sample comparison of the output from all five devices with respect to the on-board tissue equivalent proportional counter (TEPC) for both absorbed dose (top) and dose-equivalent (bottom) as defined in NCRP 142. The lower graph in each set is the TEPC. Several issues were identified and solutions to adjust for them have been included in the analysis. These include items such as the need to identify nuclear interactions in the silicon sensor layer, and to separate penetrating from stopping tracks. The wide effective range in fluence and particle type of this technology was also verified through the highest rates seen during the South Atlantic Anomaly passes and the heavy ions nominally seen in the Galactic Cosmic Rays. Corrections for detector response saturation effects were also successfully implemented as verified by reference to ground-based accelerator data taken at the Heavy-Ion Medical Accelerator Center (HIMAC) facility at the National Institute for Radiological Sciences in Japan, and at the NASA Space Radiation Laboratory (NSRL) at the Brookhaven National Laboratory in New York. Flight hardware has been produced that will be flown on the first launch of the new Orion spacecraft, and flight hardware development is ongoing to accommodate the next generation of this technology as a baseline for radiation monitoring and dosimetry on future operational manned missions. Fig 1.Five ISS REM units compared with ISS IVTEPC in absorbed dose (a) and dose-equivalent (b).
doi:10.1093/jrr/rrt197
PMCID: PMC3941488
4.  Persistence of Biomarker ATP and ATP-Generating Capability in Bacterial Cells and Spores Contaminating Spacecraft Materials under Earth Conditions and in a Simulated Martian Environment▿  
Applied and Environmental Microbiology  2008;74(16):5159-5167.
Most planetary protection research has concentrated on characterizing viable bioloads on spacecraft surfaces, developing techniques for bioload reduction prior to launch, and studying the effects of simulated martian environments on microbial survival. Little research has examined the persistence of biogenic signature molecules on spacecraft materials under simulated martian surface conditions. This study examined how endogenous adenosine-5′-triphosphate (ATP) would persist on aluminum coupons under simulated martian conditions of 7.1 mbar, full-spectrum simulated martian radiation calibrated to 4 W m−2 of UV-C (200 to 280 nm), −10°C, and a Mars gas mix of CO2 (95.54%), N2 (2.7%), Ar (1.6%), O2 (0.13%), and H2O (0.03%). Cell or spore viabilities of Acinetobacter radioresistens, Bacillus pumilus, and B. subtilis were measured in minutes to hours, while high levels of endogenous ATP were recovered after exposures of up to 21 days. The dominant factor responsible for temporal reductions in viability and loss of ATP was the simulated Mars surface radiation; low pressure, low temperature, and the Mars gas composition exhibited only slight effects. The normal burst of endogenous ATP detected during spore germination in B. pumilus and B. subtilis was reduced by 1 or 2 orders of magnitude following, respectively, 8- or 30-min exposures to simulated martian conditions. The results support the conclusion that endogenous ATP will persist for time periods that are likely to extend beyond the nominal lengths of most surface missions on Mars, and planetary protection protocols prior to launch may require additional rigor to further reduce the presence and abundance of biosignature molecules on spacecraft surfaces.
doi:10.1128/AEM.00891-08
PMCID: PMC2519281  PMID: 18567687
5.  The New Pelagic Operational Observatory of the Catalan Sea (OOCS) for the Multisensor Coordinated Measurement of Atmospheric and Oceanographic Conditions 
Sensors (Basel, Switzerland)  2011;11(12):11251-11272.
The new pelagic Operational Observatory of the Catalan Sea (OOCS) for the coordinated multisensor measurement of atmospheric and oceanographic conditions has been recently installed (2009) in the Catalan Sea (41°39′N, 2°54′E; Western Mediterranean) and continuously operated (with minor maintenance gaps) until today. This multiparametric platform is moored at 192 m depth, 9.3 km off Blanes harbour (Girona, Spain). It is composed of a buoy holding atmospheric sensors and a set of oceanographic sensors measuring the water conditions over the upper 100 m depth. The station is located close to the head of the Blanes submarine canyon where an important multispecies pelagic and demersal fishery gives the station ecological and economic relevance. The OOCS provides important records on atmospheric and oceanographic conditions, the latter through the measurement of hydrological and biogeochemical parameters, at depths with a time resolution never attained before for this area of the Mediterranean. Twenty four moored sensors and probes operating in a coordinated fashion provide important data on Essential Ocean Variables (EOVs; UNESCO) such as temperature, salinity, pressure, dissolved oxygen, chlorophyll fluorescence, and turbidity. In comparison with other pelagic observatories presently operating in other world areas, OOCS also measures photosynthetic available radiation (PAR) from above the sea surface and at different depths in the upper 50 m. Data are recorded each 30 min and transmitted in real-time to a ground station via GPRS. This time series is published and automatically updated at the frequency of data collection on the official OOCS website (http://www.ceab.csic.es/~oceans). Under development are embedded automated routines for the in situ data treatment and assimilation into numerical models, in order to provide a reliable local marine processing forecast. In this work, our goal is to detail the OOCS multisensor architecture in relation to the coordinated capability for the remote, continuous and prolonged monitoring of atmospheric and oceanographic conditions, including data communication and storage. Accordingly, time series of measurements for a number of biological parameters will be presented for the summer months of 2011. Marine hindcast outputs from the numerical models implemented for simulating the conditions over the study area are shown. The strong changes of atmospheric conditions recorded in the last years over the area have altered the marine conditions of living organisms, but the dimension of the impact remains unclear. The OOCS multisensor coordinated monitoring has been specifically designed to address this issue, thus contributing to better understand the present environmental fluctuations and to provide a sound basis for a more accurate marine forecast system.
doi:10.3390/s111211251
PMCID: PMC3251981  PMID: 22247664
pelagic observatory; oceanographic buoy; multisensor coordinated monitoring; PAR; operational oceanography; submarine canyons; numerical multiparametric modelling; ocean forecast; Western Mediterranean Sea
6.  Bacterial Growth at the High Concentrations of Magnesium Sulfate Found in Martian Soils 
Astrobiology  2012;12(2):98-106.
Abstract
The martian surface environment exhibits extremes of salinity, temperature, desiccation, and radiation that would make it difficult for terrestrial microbes to survive. Recent evidence suggests that martian soils contain high concentrations of MgSO4 minerals. Through warming of the soils, meltwater derived from subterranean ice-rich regolith may exist for an extended period of time and thus allow the propagation of terrestrial microbes and create significant bioburden at the near surface of Mars. The current report demonstrates that halotolerant bacteria from the Great Salt Plains (GSP) of Oklahoma are capable of growing at high concentrations of MgSO4 in the form of 2 M solutions of epsomite. The epsotolerance of isolates in the GSP bacterial collection was determined, with 35% growing at 2 M MgSO4. There was a complex physiological response to mixtures of MgSO4 and NaCl coupled with other environmental stressors. Growth also was measured at 1 M concentrations of other magnesium and sulfate salts. The complex responses may be partially explained by the pattern of chaotropicity observed for high-salt solutions as measured by agar gelation temperature. Select isolates could grow at the high salt concentrations and low temperatures found on Mars. Survival during repetitive freeze-thaw or drying-rewetting cycles was used as other measures of potential success on the martian surface. Our results indicate that terrestrial microbes might survive under the high-salt, low-temperature, anaerobic conditions on Mars and present significant potential for forward contamination. Stringent planetary protection requirements are needed for future life-detection missions to Mars. Key Words: Analogue—Mars—Planetary protection—Salts—Life in extreme environments. Astrobiology 12, 98–106.
doi:10.1089/ast.2011.0720
PMCID: PMC3277918  PMID: 22248384
7.  In situ methods for measuring thermal properties and heat flux on planetary bodies  
Planetary and Space Science  2011;59(8):639-660.
The thermo-mechanical properties of planetary surface and subsurface layers control to a high extent in which way a body interacts with its environment, in particular how it responds to solar irradiation and how it interacts with a potentially existing atmosphere. Furthermore, if the natural temperature profile over a certain depth can be measured in situ, this gives important information about the heat flux from the interior and thus about the thermal evolution of the body. Therefore, in most of the recent and planned planetary lander missions experiment packages for determining thermo-mechanical properties are part of the payload. Examples are the experiment MUPUS on Rosetta's comet lander Philae, the TECP instrument aboard NASA's Mars polar lander Phoenix, and the mole-type instrument HP3 currently developed for use on upcoming lunar and Mars missions. In this review we describe several methods applied for measuring thermal conductivity and heat flux and discuss the particular difficulties faced when these properties have to be measured in a low pressure and low temperature environment. We point out the abilities and disadvantages of the different instruments and outline the evaluation procedures necessary to extract reliable thermal conductivity and heat flux data from in situ measurements.
Highlights
► Numerical simulation of the thermal history of a planetary body. ► Development of robust thermal conductivity sensors for planetary applications. ► Measurement of the global heat flow of a planet or small planetary body.
doi:10.1016/j.pss.2011.03.004
PMCID: PMC3089965  PMID: 21760643
Thermal conductivity; Planetary surfaces; Lander missions
8.  Risk Maps of Lassa Fever in West Africa 
Background
Lassa fever is caused by a viral haemorrhagic arenavirus that affects two to three million people in West Africa, causing a mortality of between 5,000 and 10,000 each year. The natural reservoir of Lassa virus is the multi-mammate rat Mastomys natalensis, which lives in houses and surrounding fields. With the aim of gaining more information to control this disease, we here carry out a spatial analysis of Lassa fever data from human cases and infected rodent hosts covering the period 1965–2007. Information on contemporary environmental conditions (temperature, rainfall, vegetation) was derived from NASA Terra MODIS satellite sensor data and other sources and for elevation from the GTOPO30 surface for the region from Senegal to the Congo. All multi-temporal data were analysed using temporal Fourier techniques to generate images of means, amplitudes and phases which were used as the predictor variables in the models. In addition, meteorological rainfall data collected between 1951 and 1989 were used to generate a synoptic rainfall surface for the same region.
Methodology/Principal Findings
Three different analyses (models) are presented, one superimposing Lassa fever outbreaks on the mean rainfall surface (Model 1) and the other two using non-linear discriminant analytical techniques. Model 2 selected variables in a step-wise inclusive fashion, and Model 3 used an information-theoretic approach in which many different random combinations of 10 variables were fitted to the Lassa fever data. Three combinations of absence∶presence clusters were used in each of Models 2 and 3, the 2 absence∶1 presence cluster combination giving what appeared to be the best result. Model 1 showed that the recorded outbreaks of Lassa fever in human populations occurred in zones receiving between 1,500 and 3,000 mm rainfall annually. Rainfall, and to a much lesser extent temperature variables, were most strongly selected in both Models 2 and 3, and neither vegetation nor altitude seemed particularly important. Both Models 2 and 3 produced mean kappa values in excess of 0.91 (Model 2) or 0.86 (Model 3), making them ‘Excellent’.
Conclusion/Significance
The Lassa fever areas predicted by the models cover approximately 80% of each of Sierra Leone and Liberia, 50% of Guinea, 40% of Nigeria, 30% of each of Côte d'Ivoire, Togo and Benin, and 10% of Ghana.
Author Summary
Previous studies on the eco-epidemiology of Lassa fever in Guinea, West Africa, have shown that the reservoir is two to three times more infected by Lassa virus in the rainy season than in the dry season. None of the intrinsic variables of the murine population, such as abundance or reproduction, was able to explain this seasonal variation in prevalence. We therefore here investigate the importance of extrinsic environmental variables, partly influenced by the idea that in the case of nephropathia epidemica in Europe contamination of the environment, and therefore survival of the pathogen outside the host, appears to be an important factor in this disease's epidemiology. We therefore made an extensive review of the literature, gathering information about the geographical location of sites where Lassa fever has been certainly identified. Environmental data for these sites (rainfall, temperature, vegetation and altitude) were gathered from a variety of sources, both satellites and ground-based meteorological stations. Several statistical treatments were applied to produce Lassa ‘risk maps’. These maps all indicate a strong influence of rainfall, and a lesser influence of temperature in defining high risk areas. The area of greatest risk is located between Guinea and Cameroon.
doi:10.1371/journal.pntd.0000388
PMCID: PMC2644764  PMID: 19255625
9.  Assessment of Global Carbon Dioxide Concentration Using MODIS and GOSAT Data 
Sensors (Basel, Switzerland)  2012;12(12):16368-16389.
Carbon dioxide (CO2) is the most important greenhouse gas (GHG) in the atmosphere and is the greatest contributor to global warming. CO2 concentration data are usually obtained from ground observation stations or from a small number of satellites. Because of the limited number of observations and the short time series of satellite data, it is difficult to monitor CO2 concentrations on regional or global scales for a long time. The use of the remote sensing data such as the Advanced Very High Resolution Radiometer (AVHRR) or Moderate Resolution Imaging Spectroradiometer (MODIS) data can overcome these problems, particularly in areas with low densities of CO2 concentration watch stations. A model based on temperature (MOD11C3), vegetation cover (MOD13C2 and MOD15A2) and productivity (MOD17A2) of MODIS (which we have named the TVP model) was developed in the current study to assess CO2 concentrations on a global scale. We assumed that CO2 concentration from the Thermal And Near infrared Sensor for carbon Observation (TANSO) aboard the Greenhouse gases Observing SATellite (GOSAT) are the true values and we used these values to check the TVP model accuracy. The results indicate that the accuracy of the TVP model is different in different continents: the greatest Pearson’s correlation coefficient (R2) was 0.75 in Eurasia (RMSE = 1.16) and South America (RMSE = 1.17); the lowest R2 was 0.57 in Australia (RMSE = 0.73). Compared with the TANSO-observed CO2 concentration (XCO2), we found that the accuracy throughout the World is between −2.56∼3.14 ppm. Potential sources of TVP model uncertainties were also analyzed and identified.
doi:10.3390/s121216368
PMCID: PMC3571787  PMID: 23443383
MODIS; CO2 concentration; GOSAT TANSO; LST; NDVI/EVI; LAI/FPAR; GPP/NPP
10.  An instrument design for non-contact detection of biomolecules and minerals on Mars using fluorescence 
We discuss fluorescence as a method to detect polycyclic aromatic hydrocarbons and other organic molecules, as well as minerals on the surface of Mars. We present an instrument design that is adapted from the ChemCam instrument which is currently on the Mars Science Lander Rover Curiosity and thus most of the primary components are currently flight qualified for Mars surface operations, significantly reducing development costs. The major change compared to ChemCam is the frequency multipliers of the 1064 nm laser to wavelengths suitable for fluorescence excitation (266 nm, 355 nm, and 532 nm). We present fluorescence spectrum for a variety of organics and minerals relevant to the surface of Mars. Preliminary results show minerals already known on Mars, such as perchlorate, fluoresce strongest when excited by 355 nm. Also we demonstrate that polycyclic aromatic hydrocarbons, such as those present in Martian meteorites, are highly fluorescent at wavelengths in the ultraviolet (266 nm, 355 nm), but not as much in the visible (532 nm). We conclude that fluorescence can be an important method for Mars applications and standoff detection of organics and minerals. The instrument approach described in this paper builds on existing hardware and offers high scientific return for minimal cost for future missions.
doi:10.1186/1754-1611-8-16
PMCID: PMC4107600  PMID: 25057291
11.  Analysis, Modeling, and Simulation of the Accuracy of Continuous Glucose Sensors 
Background
Continuous glucose monitors (CGMs) collect a detailed time series of consecutive observations of the underlying process of glucose fluctuations. To some extent, however, the high temporal resolution of the data is accompanied by increased probability of error in any single data point. Due to both physiological and technical reasons, the structure of these errors is complex and their analysis is not straightforward. In this article, we describe some of the methods needed to obtain a description of the sensor error that is detailed enough for simulation.
Methods
Data were provided by Abbott Diabetes Care and included two data sets collected by the FreeStyle Navigator™ CGM: The first set consisted of 1032 time series of glucose readings from 136 patients with type 1 diabetes and parallel time series of reference blood glucose (BG) collected via self-monitoring at irregular intervals. The average duration of a time series was 5 days; the total number of sensor-reference data pairs was approximately 20,600. The second data set consisted of 56 time series of glucose readings from 28 patients with type 1 diabetes and a parallel time series of reference BG measured via the YSI 2300 Stat Plus™ analyzer every 15 minutes. The average duration of a time series was 2 days; the total number of sensor-reference data pairs was approximately 7000.
Results
Three sets of results are discussed: analysis of sensor errors with respect to the BG rate of change, mathematical modeling of sensor error patterns and distribution, and computer simulation of sensor errors: Sensor errors depend nonlinearly on the BG rate of change: Errors tend to be positive (high readings) when the BG rate of change is negative and negative (low readings) when the BG rate of change is positive, which is indicative of an underlying time delay. In addition, the sensor noise is non-white (non-Gaussian) and the consecutive sensor errors are highly interdependent.Thus, the modeling of sensor errors is based on a diffusion model of blood-to-interstitial glucose transport, which accounts for the time delay, and a time-series approach, which includes autoregressive moving average (ARMA) noise to account for the interdependence of consecutive sensor errors.Based on modeling, we have developed a computer simulator of sensor errors that includes both generic and sensor-specific error components. A χ2 test showed that no significant difference exists between the observed and the simulated distribution of sensor errors and the distribution of errors of the FreeStyle Navigator (p > .46).
Conclusions
CGM accuracy was modeled via diffusion and additive ARMA noise, which allowed for designing a computer simulator of sensor errors. The simulator, a component of a larger simulation platform approved by the Food and Drug Administration in January 2008 for pre-clinical testing of closed-loop strategies, has been successfully applied to in silico testing of closed-loop control algorithms, resulting in an investigational device exemption for closed-loop trials at the University of Virginia.
doi:10.1901/jaba.2008.2-853
PMCID: PMC2740661  PMID: 19750186
accuracy; continuous glucose monitoring; time series
12.  Analysis, Modeling, and Simulation of the Accuracy of Continuous Glucose Sensors 
Background
Continuous glucose monitors (CGMs) collect a detailed time series of consecutive observations of the underlying process of glucose fluctuations. To some extent, however, the high temporal resolution of the data is accompanied by increased probability of error in any single data point. Due to both physiological and technical reasons, the structure of these errors is complex and their analysis is not straightforward. In this article, we describe some of the methods needed to obtain a description of the sensor error that is detailed enough for simulation.
Methods
Data were provided by Abbott Diabetes Care and included two data sets collected by the FreeStyle Navigator™ CGM: The first set consisted of 1032 time series of glucose readings from 136 patients with type 1 diabetes and parallel time series of reference blood glucose (BG) collected via self-monitoring at irregular intervals. The average duration of a time series was 5 days; the total number of sensor-reference data pairs was approximately 20,600. The second data set consisted of 56 time series of glucose readings from 28 patients with type 1 diabetes and a parallel time series of reference BG measured via the YSI 2300 Stat Plus™ analyzer every 15 minutes. The average duration of a time series was 2 days; the total number of sensor-reference data pairs was approximately 7000.
Results
Three sets of results are discussed: analysis of sensor errors with respect to the BG rate of change, mathematical modeling of sensor error patterns and distribution, and computer simulation of sensor errors: Sensor errors depend nonlinearly on the BG rate of change: Errors tend to be positive (high readings) when the BG rate of change is negative and negative (low readings) when the BG rate of change is positive, which is indicative of an underlying time delay. In addition, the sensor noise is non-white (non-Gaussian) and the consecutive sensor errors are highly interdependent.Thus, the modeling of sensor errors is based on a diffusion model of blood-to-interstitial glucose transport, which accounts for the time delay, and a time-series approach, which includes autoregressive moving average (ARMA) noise to account for the interdependence of consecutive sensor errors.Based on modeling, we have developed a computer simulator of sensor errors that includes both generic and sensor-specific error components. A χ2 test showed that no significant difference exists between the observed and the simulated distribution of sensor errors and the distribution of errors of the FreeStyle Navigator (p > .46).
Conclusions
CGM accuracy was modeled via diffusion and additive ARMA noise, which allowed for designing a computer simulator of sensor errors. The simulator, a component of a larger simulation platform approved by the Food and Drug Administration in January 2008 for pre-clinical testing of closed-loop strategies, has been successfully applied to in silico testing of closed-loop control algorithms, resulting in an investigational device exemption for closed-loop trials at the University of Virginia.
PMCID: PMC2740661  PMID: 19750186
accuracy; continuous glucose monitoring; time series
13.  Modeling and Predicting Seasonal Influenza Transmission in Warm Regions Using Climatological Parameters 
PLoS ONE  2010;5(3):e9450.
Background
Influenza transmission is often associated with climatic factors. As the epidemic pattern varies geographically, the roles of climatic factors may not be unique. Previous in vivo studies revealed the direct effect of winter-like humidity on air-borne influenza transmission that dominates in regions with temperate climate, while influenza in the tropics is more effectively transmitted through direct contact.
Methodology/Principal Findings
Using time series model, we analyzed the role of climatic factors on the epidemiology of influenza transmission in two regions characterized by warm climate: Hong Kong (China) and Maricopa County (Arizona, USA). These two regions have comparable temperature but distinctly different rainfall. Specifically we employed Autoregressive Integrated Moving Average (ARIMA) model along with climatic parameters as measured from ground stations and NASA satellites. Our studies showed that including the climatic variables as input series result in models with better performance than the univariate model where the influenza cases depend only on its past values and error signal. The best model for Hong Kong influenza was obtained when Land Surface Temperature (LST), rainfall and relative humidity were included as input series. Meanwhile for Maricopa County we found that including either maximum atmospheric pressure or mean air temperature gave the most improvement in the model performances.
Conclusions/Significance
Our results showed that including the environmental variables generally increases the prediction capability. Therefore, for countries without advanced influenza surveillance systems, environmental variables can be used for estimating influenza transmission at present and in the near future.
doi:10.1371/journal.pone.0009450
PMCID: PMC2830480  PMID: 20209164
14.  The New Seafloor Observatory (OBSEA) for Remote and Long-Term Coastal Ecosystem Monitoring 
Sensors (Basel, Switzerland)  2011;11(6):5850-5872.
A suitable sampling technology to identify species and to estimate population dynamics based on individual counts at different temporal levels in relation to habitat variations is increasingly important for fishery management and biodiversity studies. In the past two decades, as interest in exploring the oceans for valuable resources and in protecting these resources from overexploitation have grown, the number of cabled (permanent) submarine multiparametric platforms with video stations has increased. Prior to the development of seafloor observatories, the majority of autonomous stations were battery powered and stored data locally. The recently installed low-cost, multiparametric, expandable, cabled coastal Seafloor Observatory (OBSEA), located 4 km off of Vilanova i la Gertrú, Barcelona, at a depth of 20 m, is directly connected to a ground station by a telecommunication cable; thus, it is not affected by the limitations associated with previous observation technologies. OBSEA is part of the European Multidisciplinary Seafloor Observatory (EMSO) infrastructure, and its activities are included among the Network of Excellence of the European Seas Observatory NETwork (ESONET). OBSEA enables remote, long-term, and continuous surveys of the local ecosystem by acquiring synchronous multiparametric habitat data and bio-data with the following sensors: Conductivity-Temperature-Depth (CTD) sensors for salinity, temperature, and pressure; Acoustic Doppler Current Profilers (ADCP) for current speed and direction, including a turbidity meter and a fluorometer (for the determination of chlorophyll concentration); a hydrophone; a seismometer; and finally, a video camera for automated image analysis in relation to species classification and tracking. Images can be monitored in real time, and all data can be stored for future studies. In this article, the various components of OBSEA are described, including its hardware (the sensors and the network of marine and land nodes), software (data acquisition, transmission, processing, and storage), and multiparametric measurement (habitat and bio-data time series) capabilities. A one-month multiparametric survey of habitat parameters was conducted during 2009 and 2010 to demonstrate these functions. An automated video image analysis protocol was also developed for fish counting in the water column, a method that can be used with cabled coastal observatories working with still images. Finally, bio-data time series were coupled with data from other oceanographic sensors to demonstrate the utility of OBSEA in studies of ecosystem dynamics.
doi:10.3390/s110605850
PMCID: PMC3231463  PMID: 22163931
OBSEA; cabled observatories; multidisciplinary observation; EMSO ESONET; remote ecosystem monitoring; automated video image analysis; fish community; activity rhythms
15.  Satellite Microwave Remote Sensing for Environmental Modeling of Mosquito Population Dynamics 
Remote sensing of environment  2012;125:147-156.
Environmental variability has important influences on mosquito life cycles and understanding the spatial and temporal patterns of mosquito populations is critical for mosquito control and vector-borne disease prevention. Meteorological data used for model-based predictions of mosquito abundance and life cycle dynamics are typically acquired from ground-based weather stations; however, data availability and completeness are often limited by sparse networks and resource availability. In contrast, environmental measurements from satellite remote sensing are more spatially continuous and can be retrieved automatically. This study compared environmental measurements from the NASA Advanced Microwave Scanning Radiometer on EOS (AMSR-E) and in situ weather station data to examine their ability to predict the abundance of two important mosquito species (Aedes vexans and Culex tarsalis) in Sioux Falls, South Dakota, USA from 2005 to 2010. The AMSR-E land parameters included daily surface water inundation fraction, surface air temperature, soil moisture, and microwave vegetation opacity. The AMSR-E derived models had better fits and higher forecasting accuracy than models based on weather station data despite the relatively coarse (25-km) spatial resolution of the satellite data. In the AMSR-E models, air temperature and surface water fraction were the best predictors of Aedes vexans, whereas air temperature and vegetation opacity were the best predictors of Cx. tarsalis abundance. The models were used to extrapolate spatial, seasonal, and interannual patterns of climatic suitability for mosquitoes across eastern South Dakota. Our findings demonstrate that environmental metrics derived from satellite passive microwave radiometry are suitable for predicting mosquito population dynamics and can potentially improve the effectiveness of mosquito-borne disease early warning systems.
doi:10.1016/j.rse.2012.07.018
PMCID: PMC3463408  PMID: 23049143
AMSR-E; Weather Station; West Nile Virus; Mosquito; Public Health
16.  Resistance of Bacterial Endospores to Outer Space for Planetary Protection Purposes—Experiment PROTECT of the EXPOSE-E Mission 
Astrobiology  2012;12(5):445-456.
Abstract
Spore-forming bacteria are of particular concern in the context of planetary protection because their tough endospores may withstand certain sterilization procedures as well as the harsh environments of outer space or planetary surfaces. To test their hardiness on a hypothetical mission to Mars, spores of Bacillus subtilis 168 and Bacillus pumilus SAFR-032 were exposed for 1.5 years to selected parameters of space in the experiment PROTECT during the EXPOSE-E mission on board the International Space Station. Mounted as dry layers on spacecraft-qualified aluminum coupons, the “trip to Mars” spores experienced space vacuum, cosmic and extraterrestrial solar radiation, and temperature fluctuations, whereas the “stay on Mars” spores were subjected to a simulated martian environment that included atmospheric pressure and composition, and UV and cosmic radiation. The survival of spores from both assays was determined after retrieval. It was clearly shown that solar extraterrestrial UV radiation (λ≥110 nm) as well as the martian UV spectrum (λ≥200 nm) was the most deleterious factor applied; in some samples only a few survivors were recovered from spores exposed in monolayers. Spores in multilayers survived better by several orders of magnitude. All other environmental parameters encountered by the “trip to Mars” or “stay on Mars” spores did little harm to the spores, which showed about 50% survival or more. The data demonstrate the high chance of survival of spores on a Mars mission, if protected against solar irradiation. These results will have implications for planetary protection considerations. Key Words: Planetary protection—Bacterial spores—Space experiment—Simulated Mars mission. Astrobiology 12, 445–456.
doi:10.1089/ast.2011.0737
PMCID: PMC3371261  PMID: 22680691
17.  Near-UV Transmittance of Basalt Dust as an Analog of the Martian Regolith: Implications for Sensor Calibration and Astrobiology 
Sensors (Basel, Switzerland)  2006;6(6):688-696.
The Martian regolith is exposed to solar irradiation in the near-UV (200-390 nm). Basalt is one of the main components of the dust on Mars surface. The near-UV irradiation of basalt dust on Mars is simulated experimentally in order to determine the transmittance as a function of the mass and thickness of the dust. This data can serve to quantify the absorption of dust deposited on sensors aiming to measure the UV intensity on Mars surface. The minimum thickness of the dust that corresponds to near-zero-transmittance in the near-UV is measured. Hypothetical Martian microorganisms living on the dusty regolith at deeper layers would be preserved from the damaging solar UV irradiation.
PMCID: PMC3874829
Ultraviolet: solar system; Mars surface; Methods: laboratory; basalt; Instrumentation: photometers; Astrobiology
18.  Fast Thermal Calibration of Low-Grade Inertial Sensors and Inertial Measurement Units 
Sensors (Basel, Switzerland)  2013;13(9):12192-12217.
The errors of low-cost inertial sensors, especially Micro-Electro Mechanical Systems (MEMS) ones, are highly dependent on environmental conditions such as the temperature. Thus, there is a need for the development of accurate and reliable thermal compensation models to reduce the impact of such thermal drift of the sensors. Since the conventional thermal calibration methods are typically time-consuming and costly, an efficient thermal calibration method to investigate the thermal drift of a full set of gyroscope and accelerometer errors (i.e., biases, scale factor errors and non-orthogonalities) over the entire temperature range in a few hours is proposed. The proposed method uses the idea of the Ramp method, which removes the time-consuming process of stabilizing the sensor temperature, and addresses its inherent problems with several improvements. We change the temperature linearly for a complete cycle and take a balanced strategy by making comprehensive use of the sensor measurements during both heating and cooling processes. Besides, an efficient 8-step rotate-and-static scheme is designed to further improve the calibration accuracy and efficiency. Real calibration tests showed that the proposed method is suitable for low-grade IMUs and for both lab and factory calibration due to its efficiency and sufficient accuracy.
doi:10.3390/s130912192
PMCID: PMC3821333  PMID: 24036581
MEMS inertial sensors; IMU; thermal calibration; turntable; temperature chamber
19.  A Passive Wireless Temperature Sensor for Harsh Environment Applications 
Sensors (Basel, Switzerland)  2008;8(12):7982-7995.
High temperature sensors capable of operating in harsh environments are needed in order to prevent disasters caused by structural or system functional failures due to increasing temperatures. Most existing temperature sensors do not satisfy the needs because they require either physical contact or a battery power supply for signal communication, and furthermore, neither of them can withstand high temperatures nor rotating applications. This paper presents a novel passive wireless temperature sensor, suitable for working in harsh environments for high temperature rotating component monitoring. A completely passive LC resonant telemetry scheme, relying on a frequency variation output, which has been applied successfully in pressure, humidity and chemical measurement, is integrated with a unique high-k temperature sensitive ceramic material, in order to measure the temperatures without contacts, active elements, or power supplies within the sensor. In this paper, the high temperature sensor design and performance analysis are conducted based on mechanical and electrical modeling, in order to maximize the sensing distance, the Q factor and the sensitivity. In the end, the sensor prototype is fabricated and calibrated successfully up to 235°C, so that the concept of temperature sensing through passive wireless communication is proved.
doi:10.3390/s8127982
PMCID: PMC3791002
High Temperature Sensor; Hash Environment Applications; Passive; Wireless
20.  Use of Finite Elements Analysis for a Weigh-in-Motion Sensor Design 
Sensors (Basel, Switzerland)  2012;12(6):6978-6994.
High speed weigh-in-motion (WIM) sensors are utilized as components of complex traffic monitoring and measurement systems. They should be able to determine the weights on wheels, axles and vehicle gross weights, and to help the classification of vehicles (depending on the number of axles). WIM sensors must meet the following main requirements: good accuracy, high endurance, low price and easy installation in the road structure. It is not advisable to use cheap materials in constructing these devices for lower prices, since the sensors are normally working in harsh environmental conditions such as temperatures between −40 °C and +70 °C, dust, temporary water immersion, shocks and vibrations. Consequently, less expensive manufacturing technologies are recommended. Because the installation cost in the road structure is high and proportional to the WIM sensor cross section (especially with its thickness), the device needs to be made as flat as possible. The WIM sensor model presented and analyzed in this paper uses a spring element equipped with strain gages. Using Finite Element Analysis (FEA), the authors have attempted to obtain a more sensitive, reliable, lower profile and overall cheaper elastic element for a new WIM sensor.
doi:10.3390/s120606978
PMCID: PMC3435961  PMID: 22969332
weigh in motion; WIM sensor; shear force sensors; optimization; sensitivity; durability
21.  Feasibility of Fiber Bragg Grating and Long-Period Fiber Grating Sensors under Different Environmental Conditions 
Sensors (Basel, Switzerland)  2010;10(11):10105-10127.
This paper presents the feasibility of utilizing fiber Bragg grating (FBG) and long-period fiber grating (LPFG) sensors for nondestructive evaluation (NDE) of infrastructures using Portland cement concretes and asphalt mixtures for temperature, strain, and liquid-level monitoring. The use of hybrid FBG and LPFG sensors is aimed at utilizing the advantages of two kinds of fiber grating to implement NDE for monitoring strains or displacements, temperatures, and water-levels of infrastructures such as bridges, pavements, or reservoirs for under different environmental conditions. Temperature fluctuation and stability tests were examined using FBG and LPFG sensors bonded on the surface of asphalt and concrete specimens. Random walk coefficient (RWC) and bias stability (BS) were used for the first time to indicate the stability performance of fiber grating sensors. The random walk coefficients of temperature variations between FBG (or LPFG) sensor and a thermocouple were found in the range of −0.7499 °C/ h to −1.3548 °C/ h. In addition, the bias stability for temperature variations, during the fluctuation and stability tests with FBG (or LPFG) sensors were within the range of 0.01 °C/h with a 15–18 h time cluster to 0.09 °C/h with a 3–4 h time cluster. This shows that the performance of FBG or LPFG sensors is comparable with that of conventional high-resolution thermocouple sensors under rugged conditions. The strain measurement for infrastructure materials was conducted using a packaged FBG sensor bonded on the surface of an asphalt specimen under indirect tensile loading conditions. A finite element modeling (FEM) was applied to compare experimental results of indirect tensile FBG strain measurements. For a comparative analysis between experiment and simulation, the FEM numerical results agreed with those from FBG strain measurements. The results of the liquid-level sensing tests show the LPFG-based sensor could discriminate five stationary liquid-levels and exhibits at least 1,050-mm liquid-level measurement capacity. Thus, the hybrid FBG and LPFG sensors reported here could benefit the NDE development and applications for infrastructure health monitoring such as strain, temperature and liquid-level measurements.
doi:10.3390/s101110105
PMCID: PMC3230987  PMID: 22163460
nondestructive evaluation (NDE); fiber Bragg grating (FBG); long-period fiber grating (LPFG); temperature, strain; liquid-level; finite element model; random walk coefficient; 07.60.Vg; 42.81.-i.; 07.05.-t
22.  Radiation-associated cardiovascular risks for future deep-space missions 
Journal of Radiation Research  2014;55(Suppl 1):i37-i39.
Background: During the future Moon and Mars missions, astronauts will be exposed to space radiation (IR) for extended time. The majority of space flight-associated risks identified for the cardiovascular (CV) system to date were determined shortly after low Earth orbit (LEO) short- and long-duration space flights that include: serious cardiac dysrhythmias, compromised orthostatic CV response and manifestation of previously asymptomatic CV disease. Further ground-based experiments using a surrogate model of microgravity supported the space flight data for significant cardiac remodeling due to prolonged exposure to microgravity. These symptoms were determined to be a consequence of adaptation to microgravity that could be ameliorated by a post-mission exercise program, and were not identified as risk factors that were causatively related to space IR. Long-term degenerative effects of cosmic IR during and after space flights on CV system are unknown.
It was suggested that due to GCR, each cell in an astronaut's body will be traversed by 1H every 3 days, helium (2He) nuclei every few weeks and high charge and energy (HZE) nuclei (e.g. 28Si, 56Fe) every few months. Despite the fact that only 1% of GCR is composed of ions heavier than helium, ∼41% of the IR dose-equivalent is predicted to be HZE particles with 13% being from 56Fe particles, only. During an exploration-class space mission to Mars, astronauts will not have access to comprehensive healthcare services for a period of at least 2–3 years. Since the majority of experienced astronauts are middle-aged (average age is 46, and the range is 33–58 years), they are at risk for developing serious CV events which could be life-threatening for the astronaut and mission-threatening for NASA. Therefore, it is important to evaluate the effects and potential CV risks caused by space IR. We hypothesized that: (i) low-dose space IR-induced biological responses may be long-lasting and are IR type-dependent; (ii) IR may increase CV risks in the aging heart (IR + AGING model) and affect the heart recovery after an adverse CV event, such as acute myocardial infarct (IR + AGING + AMI model).
Methods: Eight- to 9-month-old C57BL/6N male mice were IR once with proton (1H) 50 cGy, 1 GeV/n or iron (56Fe) 15 cGy, 1 GeV/n. We evaluated IR-induced biological tissue responses—underlying molecular mechanisms, calcium handling, signal transduction, gene expression and cardiac fibrosis. Cardiac function was assessed by echocardiography (ECHO) and hemodynamic measurements (HEMO) as detailed in Fig. 1. AMI was induced by ligation of left anterior descending coronary artery 1 and 3 months post-IR as detailed in Fig. 2.Fig. 1.Radiation + aging model. Fig. 2.Radiation + aging model + adverse CV event model.
Results: In the IR + AGING model, cardiac function was not different among the control and 1H-IR group, whereas left ventricular end-diastolic pressure (LVEDP) was significantly increased in 56Fe mice 1 and 3 months post-IR. There was a small but statistically significant (P < 0.04) improvement of ejection fraction % (EF%) in 1H-IR vs control mice. One month post-IR, compared with control, 1H- and 56Fe-IR hearts had a significant up-regulation of sarcolemmal Na+–Ca2+ exchanger (NCX) (∼200% P<0.007), sarco(endo)plasmic reticulum calcium-ATPase (SERCA2a, >200% increases, P < 0.02) and 400% decreases in p-p38 MAPK (P < 0.05), suggesting activation of compensatory mechanisms in [Ca2+]i handling in these hearts. By 3 months, compared with control, 1H- and 56Fe-IR hearts had 200–500% (P < 0.02) decreases in SERCA2a and more than 200% decreases in p-Creb-1 (P < 0.02), suggesting reduced capacity in intracellular [Ca2+]i handling. These data suggest that dysfunction in [Ca2+]i handling combined with LVEDP increase after 56Fe-IR may arise from the excessive demand on the heart due to prolonged activation of compensatory mechanisms that lead to changes in SERCA2a and p-Creb1 levels. This may represent a possible intracellular mechanism of heart failure in development in 56Fe-IR hearts.
In the IR + AGING + AMI model, no mortality was observed among three different groups 1 or 3 months post-IR and up to 28 days post-AMI. However, 1 month post-IR and 28 days post-AMI, the infarct size was significantly smaller in 56Fe-IR (p < 0.003) and 1H-IR (p = n.s.) vs control-IR mice, suggesting that at 1 month, 56Fe-IR primes the heart to recover better after AMI. In contrast, 3 months post AMI, 1H-AMI mice had a better cardiac functional recovery compared with control-AMI and 56Fe-AMI mice. The ejection fraction (EF%) was most decreased in 56Fe-AMI mice (56Fe-AMI vs 1H-AMI: 18 vs 48%, P < 0.007, ∼65–70% pre-AMI EF% for all groups). There was a 2- to 4-fold increase in LVEDP in 56Fe-AMI vs 1H-AMI (P < 0.04), suggesting that 56Fe-AMI hearts developed cardiac de-compensation. Western blots showed that 3 days post-AMI, compared with control- and 1H-IR-AMI mice, 56Fe-IR-AMI hearts had a 4- to 7-fold (P < 0.04) decreases in p-Akt (Thr308), p-Erk1/2 (P < 0.007) and ∼2-fold (P < 0.01) increase in phosphorylated ribosomal protein S6 kinase (p-S6k, a readout for mTORC1 pathway activation), suggesting decreased survival and angiogenesis signaling and decreased autophagy in these hearts. Seven days post-AMI, the levels of p-pErk1/2 were comparable between all three treatment conditions. However, in 56Fe-IR-AMI hearts, the p-Akt (Thr308) levels remained 4-fold decreased. Additionally, here was a 3-fold (P<0.05) decrease in p-S6k levels and >10-fold increase in p-p38 MAPK level in 56Fe vs control and 1H-IR-AMI hearts, suggesting continuous decreases in the survival, proliferation and angiogenesis signaling (p-Akt and p-S6k) and increase in the apoptotic signaling (p-p38 MAPK) up to Day 7 post-AMI in 56Fe-IR-AMI mice.
In summary, our results revealed that by 1 and 3 months post-IR in IR + AGING, 56Fe-IR but not 1H-IR mice had worse cardiac function. Further, a single 1H-IR 3 months prior to AMI improved, whereas 56Fe-IR worsened, recovery from AMI recovery. Our data in the IR + AGING and IR + AGING + AMI groups strongly suggest that low-dose HZE particle IR (56Fe) have long-lasting negative effect on heart homeostasis during normal aging, and present a significant CV risk for recovery after adverse CV event, such as AMI.
doi:10.1093/jrr/rrt202
PMCID: PMC3941505
HZE; iron; proton; low-dose; cardiovascular risks; Ca2+
23.  Design and Development of a Flexible Strain Sensor for Textile Structures Based on a Conductive Polymer Composite 
Sensors (Basel, Switzerland)  2007;7(4):473-492.
The aim of this work is to develop a smart flexible sensor adapted to textile structures, able to measure their strain deformations. The sensors are “smart” because of their capacity to adapt to the specific mechanical properties of textile structures that are lightweight, highly flexible, stretchable, elastic, etc. Because of these properties, textile structures are continuously in movement and easily deformed, even under very low stresses. It is therefore important that the integration of a sensor does not modify their general behavior. The material used for the sensor is based on a thermoplastic elastomer (Evoprene)/carbon black nanoparticle composite, and presents general mechanical properties strongly compatible with the textile substrate. Two preparation techniques are investigated: the conventional melt-mixing process, and the solvent process which is found to be more adapted for this particular application. The preparation procedure is fully described, namely the optimization of the process in terms of filler concentration in which the percolation theory aspects have to be considered. The sensor is then integrated on a thin, lightweight Nylon fabric, and the electromechanical characterization is performed to demonstrate the adaptability and the correct functioning of the sensor as a strain gauge on the fabric. A normalized relative resistance is defined in order to characterize the electrical response of the sensor. Finally, the influence of environmental factors, such as temperature and atmospheric humidity, on the sensor performance is investigated. The results show that the sensor's electrical resistance is particularly affected by humidity. This behavior is discussed in terms of the sensitivity of the carbon black filler particles to the presence of water.
PMCID: PMC3800360
carbon black; conductive polymer composite; flexible sensor; textile strain gauge
24.  Acute health impacts of airborne particles estimated from satellite remote sensing✩ 
Environment international  2012;51:150-159.
Satellite-based remote sensing provides a unique opportunity to monitor air quality from space at global, continental, national and regional scales. Most current research focused on developing empirical models using ground measurements of the ambient particulate. However, the application of satellite-based exposure assessment in environmental health is still limited, especially for acute effects, because the development of satellite PM2.5 model depends on the availability of ground measurements. We tested the hypothesis that MODIS AOD (aerosol optical depth) exposure estimates, obtained from NASA satellites, are directly associated with daily health outcomes. Three independent healthcare databases were used: unscheduled outpatient visits, hospital admissions, and mortality collected in Beijing metropolitan area, China during 2006. We use generalized linear models to compare the short-term effects of air pollution assessed by ground monitoring (PM10) with adjustment of absolute humidity (AH) and AH-calibrated AOD. Across all databases we found that both AH-calibrated AOD and PM10 (adjusted by AH) were consistently associated with elevated daily events on the current day and/or lag days for cardiovascular diseases, ischemic heart diseases, and COPD. The relative risks estimated by AH-calibrated AOD and PM10 (adjusted by AH) were similar. Additionally, compared to ground PM10, we found that AH-calibrated AOD had narrower confidence intervals for all models and was more robust in estimating the current day and lag day effects. Our preliminary findings suggested that, with proper adjustment of meteorological factors, satellite AOD can be used directly to estimate the acute health impacts of ambient particles without prior calibrating to the sparse ground monitoring networks.
doi:10.1016/j.envint.2012.10.011
PMCID: PMC3711510  PMID: 23220016
Absolute humidity; Aerosol optical depth; Environmental health; Particulate matter; Satellite remote sensing
25.  The Relationship of Sleep with Temperature and Metabolic Rate in a Hibernating Primate 
PLoS ONE  2013;8(9):e69914.
Study Objectives
It has long been suspected that sleep is important for regulating body temperature and metabolic-rate. Hibernation, a state of acute hypothermia and reduced metabolic-rate, offers a promising system for investigating those relationships. Prior studies in hibernating ground squirrels report that, although sleep occurs during hibernation, it manifests only as non-REM sleep, and only at relatively high temperatures. In our study, we report data on sleep during hibernation in a lemuriform primate, Cheirogaleus medius. As the only primate known to experience prolonged periods of hibernation and as an inhabitant of more temperate climates than ground squirrels, this animal serves as an alternative model for exploring sleep temperature/metabolism relationships that may be uniquely relevant to understanding human physiology.
Measurements and Results
We find that during hibernation, non-REM sleep is absent in Cheirogaleus. Rather, periods of REM sleep occur during periods of relatively high ambient temperature, a pattern opposite of that observed in ground squirrels. Like ground squirrels, however, EEG is marked by ultra-low voltage activity at relatively low metabolic-rates.
Conclusions
These findings confirm a sleep-temperature/metabolism link, though they also suggest that the relationship of sleep stage with temperature/metabolism is flexible and may differ across species or mammalian orders. The absence of non-REM sleep suggests that during hibernation in Cheirogaleus, like in the ground squirrel, the otherwise universal non-REM sleep homeostatic response is greatly curtailed or absent. Lastly, ultra-low voltage EEG appears to be a cross-species marker for extremely low metabolic-rate, and, as such, may be an attractive target for research on hibernation induction.
doi:10.1371/journal.pone.0069914
PMCID: PMC3762832  PMID: 24023713

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