Two-stage Series Research Articles

Future projections of temperature-related excess out-of-hospital cardiac arrest under climate change scenarios in Japan

BackgroundRecent studies have reported associations between global climate change and mortality. However, future projections of temperature-related out-of-hospital cardiac arrest (OHCA) have not been thoroughly evaluated. Thus, we aimed to project temperature-related morbidity for OHCA concomitant with climate change. MethodsWe collected national registry data on all OHCA cases reported in 2005–2015 from all 47 Japanese prefectures. We used a two-stage time series analysis to estimate temperature-OHCA relationships. Time series of current and future daily mean temperature variations were constructed according to four climate change scenarios of representative concentration pathways (RCPs) using five general circulation models. We projected excess morbidity for heat and cold and the net change in 1990–2099 for each climate change scenario using the assumption of no adaptation or population changes. ResultsDuring the study period, 739,717 OHCAs of presumed cardiac origin were reported. Net decreases in temperature-related excess morbidity were observed under higher emission scenarios. The net change in 2090–2099 compared with 2010–2019 was −0.8% (95% empirical confidence interval [eCI]: −1.9, 0.1) for a mild emission scenario (RCP2.6), −2.6% (95% eCI: −4.4, −0.8) for a stabilization scenario (RCP4.5), −3.4% (95% eCI: −5.7, −1.0) for a stabilization scenario (RCP6.0), and − 4.2% (95% eCI: −8.3, −0.1) for an extreme emission scenario (RCP8.5). ConclusionsOur study indicates that Japan is projected to experience a substantial net reduction in OHCAs in higher-emission scenarios. The decrease in risk is limited to a specific morbidity cause, and a broader assessment within climate change scenarios should consider other direct and indirect impacts.

Combination of two-stage series evaporation with non-isothermal phase change of organic Rankine cycle to enhance flue gas heat recovery from gas turbine

Nowadays, gas turbines (GTs) are increasingly used in China, with a relatively low performance. Organic Rankine cycle (ORC) is promising to recover the flue gas heat recovery from GT. To efficiently enhance the heat recovery, two-stage series evaporation is combined with non-isothermal phase change of non-azeotropic mixtures. Thus, two-stage series organic Rankine cycle (TSORC) with six non-azeotropic mixtures, composed of R245fa and hydrocarbons, as the working fluids are investigated. The cycle performances of TSORC with non-azeotropic mixtures are compared with those of the ORC with pure working fluid. Moreover, a case study was conducted to illustrate the performance enhancement by TSORC with the non-azeotropic mixture for fuel gas waste heat from C200HP. The results show that the net power output, thermal and exergy efficiencies of the TSORC are superior to those of the ORC at the same mass fraction, especially for the net power output. Comparing with the stand-alone gas turbine of C200HP, the TSORC with cyclohexane/R245fa[0.8/0.2] increases the efficiency of C200HP system by 35.48%, and the power generation efficiency of the C200HP-TSORC system achieves 44.71%. The TSORC with non-azeotropic mixtures as the working fluids is advisable and can be popularized in engineering applications.

Numerical simulation of gas-solid two-phase flow in a two-stage series riser using the filtered model

In order to study the hydrodynamics characteristics of gas-solid two-phase flow in the two-stage series riser, a filtered two-fluid model considering filter size, filtered solids volume fraction and slip velocity is used. Comparing to simulated results from different drag models including the filtered model, Gidaspow model and Wen-Yu model, the results from the filtered model are in better agreement with the experimental data of Zhu et al. Also, the details comparison of flow behaviors of particles between the two-stage series riser and typical riser are conducted. The enlarged section in the bottom for a two-stage series riser can strengthen the back-mixing of particles and gas-solid interaction. Simulation results reveal that the solids volume fraction displays the typical S-type distribution with an increase of solids mass rate, but the gap is declined along the bed height. The distributions of solids volume fraction, axial velocity and residence time are investigated by analyzing the simulated results at the different geometry of enlarged zone at the bottom of a two-stage series riser.

Thermodynamic and economic evaluation of the organic Rankine cycle (ORC) and two-stage series organic Rankine cycle (TSORC) for flue gas heat recovery

The flue gas heat can be recovered by organic Rankine cycle (ORC) or two-stage series organic Rankine cycle (TSORC), but their comprehensive performance should be compared in detail. In this paper, ORC and TSORC are compared from thermodynamic and economic points of view. The technical indicators include the net output power, efficiency, thermal conductance, volumetric flow ratio, and the economic indicators the electricity production cost (EPC), payback period (PBP) and rate of return on investment (ROROI). The results show that the TSORC can recover more heat in the low-pressure stage from the heat source so as to decrease the irreversible loss between the heat source and the working fluid in contrast with ORC, thereby enhancing the net output power and exergetic efficiency but decreasing the thermal efficiency. However, from the economic point of view, the TSORC declines the EPC, PBP and ROROI due to that the increased investment is higher than the earnings as a result of the installation of the second-stage evaporation. A higher flue gas temperature from 200 °C to 300 °C tends to enhance the tech-economic performance of the TSORC. As the manufacturing cost goes down over time, the TSORC will further improve its economic performance in the future.

The Study on Numerical Simulation and Experiments of Four Product Hydrocyclone with Double Vortex Finders

A hydrocyclone is an instrument that can effectively separate multi-phase mixtures of particles with different densities or sizes based on centrifugal sedimentation principles. However, conventional hydrocyclones lead to two products only, resulting in an over-wide particle size range that does not meet the requirements of subsequent operations. In this article, a two-stage series, a four product hydrocyclone is proposed. The first stage hydrocyclone is designed to be a coaxial double overflow pipe: under the effect of separation, fine particles are discharged from the internal overflow pipe, while medium-size particles are discharged from external overflow pipe before entering the second stage hydrocyclone for fine sedimentation. In other words, one-stage grading leads to four products, including the first stage underflow, the first stage overflow, the second stage underflow, and the second stage overflow. The effects of structural parameters and operational parameters on flow field distribution in hydrocyclone were investigated via a study of flow field distribution in multi-product hydrocyclones using numerical simulations. The application of four product hydrocyclone in iron recovery shows that the grade and recovery of iron concentrate exceed 65.08% and 86.14%, respectively. This study provides references for understanding the flow field distribution in hydrocyclones and development of multi-product grading instrument in terms of both theory and industrial applications.

Poly-generation energy system driven by associated geothermal water for oilfield in high water cut stage: A theoretical study

Onshore oilfields are also geothermal fields. In order to reduce cost of geothermal wells and simultaneously improve the energy efficiency of geo-plants, a poly-generation energy system driven by associated geothermal water was established for oilfield in high water cut stage. The system consists of four parts: the power generation subsystem, the absorption chiller subsystem, the oil gathering and transportation heat tracing (OGTHT) subsystem and the radiant heating subsystem, and it realizes the combined cooling, heat, power generation, and oil recovery (CCHPOR), with the associated geothermal water ranging from 373.15 K to 423.15 K. The impact of the heat source temperature and the evaporation temperature on system performance was analyzed. The results show that the performances including net power output, thermal efficiency, exergy efficiency, of the TSORC (two-stage series organic Rankine cycle) are better than those of the ORC, and the total energy efficiency of the CCHPOR reaches 75%. Moreover, the CCHPOR system can prolong the effective life of oil wells, especially for those in high water cut stage, which can be adopted in engineering applications.

Quantifying excess deaths related to heatwaves under climate change scenarios: A multicountry time series modelling study.

BackgroundHeatwaves are a critical public health problem. There will be an increase in the frequency and severity of heatwaves under changing climate. However, evidence about the impacts of climate change on heatwave-related mortality at a global scale is limited.Methods and findingsWe collected historical daily time series of mean temperature and mortality for all causes or nonexternal causes, in periods ranging from January 1, 1984, to December 31, 2015, in 412 communities within 20 countries/regions. We estimated heatwave–mortality associations through a two-stage time series design. Current and future daily mean temperature series were projected under four scenarios of greenhouse gas emissions from 1971–2099, with five general circulation models. We projected excess mortality in relation to heatwaves in the future under each scenario of greenhouse gas emissions, with two assumptions for adaptation (no adaptation and hypothetical adaptation) and three scenarios of population change (high variant, median variant, and low variant). Results show that, if there is no adaptation, heatwave-related excess mortality is expected to increase the most in tropical and subtropical countries/regions (close to the equator), while European countries and the United States will have smaller percent increases in heatwave-related excess mortality. The higher the population variant and the greenhouse gas emissions, the higher the increase of heatwave-related excess mortality in the future. The changes in 2031–2080 compared with 1971–2020 range from approximately 2,000% in Colombia to 150% in Moldova under the highest emission scenario and high-variant population scenario, without any adaptation. If we considered hypothetical adaptation to future climate, under high-variant population scenario and all scenarios of greenhouse gas emissions, the heatwave-related excess mortality is expected to still increase across all the countries/regions except Moldova and Japan. However, the increase would be much smaller than the no adaptation scenario. The simple assumptions with respect to adaptation as follows: no adaptation and hypothetical adaptation results in some uncertainties of projections.ConclusionsThis study provides a comprehensive characterisation of future heatwave-related excess mortality across various regions and under alternative scenarios of greenhouse gas emissions, different assumptions of adaptation, and different scenarios of population change. The projections can help decision makers in planning adaptation and mitigation strategies for climate change.

Dominance at the divisional efficiencies level in network DEA: The case of two-stage processes

We introduce in this paper the notion of dominance in the divisional efficiencies space in Network Data Envelopment Analysis. We argue that, irrespectively of the method used, a successful efficiency evaluation protocol should satisfy the dominance property at the divisional efficiencies level. In particular, there should not exist any other feasible solution in the assessment model, suboptimal in terms of the optimality criterion, that provides stage efficiencies scores at least as high as the assessed ones and higher for at least one stage. Then, we investigate the dominance property in different methods for two-stage series processes of various complexity. We prove that the additive efficiency decomposition method and the relational model provide non-dominated divisional efficiencies when they are applied to elementary two-stage processes, where nothing but the external inputs to the first stage enters the system and nothing but the external outputs of the second stage leaves the system. For more complex two-stage structures, however, we provide examples showing that these models do not comply with the dominance requirement at the divisional efficiencies level and lead to controversial results. Finally, we revisit some characteristic NDEA methods for which dominance is an inherent property.

Parametric Optimisation of Torsional Vibration Dampers for Vehicle Power Transmission System Considering Damping Effect and Lightweight Design

To reduce the torsional vibration of vehicle power transmission system (VPTS), a torsional vibration model with multiple degrees of freedom (MDOF) of VPTS was established. The scheme of equipping torsional vibration dampers (TVDs) on the driveshaft was employed by the calculation of the forced vibration and the free vibration of the VPTS. The energy method was used to optimize the parameters of single-stage, two-stage parallel and two-stage series TVDs based on the principle that balances the damping effect and lightweight design. On the basis of this, the parameters of the models incorporating TVD and elastic couplings were optimized. Results showed that the proposed method can ensure the damping effects of TVD and realize the lightweight design.

Adaptation to Heat and Cold in the Context of a Changing Climate: A Multi-Country Analysis

Background/Aim: The net impact of global warming will depend on the extent to which adaptation overcomes the effect of gradual changes in temperature. Disentangling the two processes is critical to provide accurate projections of future temperature-related impacts under climate change scenarios. We present evidence from a multi-country investigation that assessed temporal trends in mortality attributed to both heat and cold, and adaptation. Methods: We collected data from 305 locations in 10 countries between 1985 and 2012. Temporal trends in country-specific attributable mortality fractions (AF) for heat/cold (temperatures above/below minimum mortality temperature) were estimated using a two-stage time series design with time-varying distributed lag non-linear models and multivariate meta-analysis. To disentangle the contribution of adaptation from changes in attributable mortality due to gradual increases in temperature, we compared yearly AF with those predicted assuming either temperature distribution or exposure-response relationships as constant across the study period, respectively. Results: Heat-AF decreased in all countries except Australia and United Kingdom, from 0.45-1.39% in the first to 0.15-0.93% in the last 5-year periods, respectively. Different patterns were found for cold, with ranges from 5.56-15.43% to 2.17-8.54%, showing either decreasing (Japan, Spain, Australia, Ireland), increasing (US), or stable trends (Canada, South Korea, United Kingdom). We found inconsistent patterns in Brazil and Switzerland and a null heat-impact in Ireland. Long-term trends were mostly captured by temporal variation in exposure-response associations (interpreted as adaptation), while year-to-year fluctuations were driven by changes in temperature distribution. Conclusions: Our findings indicate that heat-mortality impacts decreased in most countries consistent with previous studies, whereas cold-mortality exhibited heterogeneous trends. In addition, the pace of adaptation has been faster than the observed warming, suggesting there is scope for the implementation of effective public health policies under climate change. Further investigations should focus on identification of the factors responsible for these adaptation trends.

Modeling Future Projections of Temperature-Related Excess Morbidity Due to Infectious Gastroenteritis Under Climate Change Conditions in Japan

Background: Climate change has marked implications for the burden of infectious diseases. We examined temperature-infectious gastroenteritis associations throughout Japan and projected temperature-related morbidity concomitant with climate change for the 2090s. Methods: Daily time series of average temperature and morbidity for infectious gastroenteritis cases in 2005-2015 were collated from the 47 Japanese prefectures. A two-stage time series analysis was adopted to estimate temperature-infectious gastroenteritis relationships. Time series of present and future daily average temperature fluctuations were projected for the four climate change scenarios of representative concentration pathways (RCPs) according to five general circulation models. Excess morbidity for high and low temperatures and the net change in 1990-2099 were projected for each climate change scenario by assuming the absence of adaptation and population alterations. Findings: In 2005-2015, 11,529,833 infectious gastroenteritis cases were reported. There were net reductions in temperature-induced excess morbidity under higher emission scenarios. The net change in 2090-2099 compared to 2010-2019 was -0.3% (95% empirical confidence interval [eCI]: -1.5-0.7) for RCP2.6, -2.4% (95% eCI: -4.7--0.5) for RCP4.5, -3.5% (95% eCI: -6.7-0.1) for RCP6.0, and -6.7% (95% eCI: -11.5--2.9) for RCP8.5. Spatial heterogeneity in the temperature-morbidity relationship was observed among prefectures (Cochran Q test, p<0.001; I2=96.1%). Interpretation: Japan may experience a net reduction in temperature-related excess morbidity due to infectious gastroenteritis in higher emission scenarios. Further projections of specific pathogen-induced infectious gastroenteritis due to climate change are warranted. Funding Statement: This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers 15K08714, 16H05247, and 18K11666; and the Medical Research Council UK (Grant ID: MR/M022625/1). Declaration of Interests: The authors have declared that no competing interests exist. Ethics Approval Statement: The contents of this study were approved by the Ethics Committee of the Kyushu University Graduate School of Medical Sciences. Given that this was a retrospective observational study that used national surveillance data and the enrolled subjects were deidentified, there was no need to acquire informed consent.

Future Projections of Temperature-Related Excess Out-of-Hospital Cardiac Arrest Under Climate Change Scenarios in Japan

Background: Recent studies have reported associations between global climate change and mortality. However, future projections of temperature-related out-of-hospital cardiac arrest (OHCA) have not been thoroughly evaluated. Thus, we aimed to project temperature-related morbidity for OHCA concomitant with climate change. Methods: We collected national registry data on all OHCA cases reported in 2005–2015 from all 47 Japanese prefectures. We used a two-stage time series analysis to estimate temperature-OHCA relationships. Time series of current and future daily mean temperature variations were constructed according to four climate change scenarios of representative concentration pathways (RCPs) using five general circulation models. We projected excess morbidity for heat and cold and the net change in 1990–2099 for each climate change scenario using the assumption of no adaptation or population changes. Findings: During the study period, 739,717 OHCAs of presumed cardiac origin were reported. Net decreases in temperature-related excess morbidity were observed under higher emission scenarios. The net change in 2090–2099 compared with 2010–2019 was -0.8% (95% empirical confidence interval [eCI]: -1.9–0.1) for RCP2.6, -2.6% (95% eCI: -4.4–-0.8) for RCP4.5, -3.4% (95% eCI: -5.7–-1.0) for RCP6.0, and -4.2% (95% eCI: -8.3–-0.1) for RCP8.5. Interpretation: Our study indicates that Japan is projected to experience a substantial net reduction in OHCAs in higher-emission scenarios. The decrease in risk is limited to a specific morbidity cause, and a broader assessment within climate change scenarios should consider other direct and indirect impacts. Funding Statement: The Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers 15K08714, 16H05247, and 18K11666; the Medical Research Council UK (Grant ID: MR/M022625/1). Declaration of Interests: We declare no competing interests. Ethics Approval Statement: This study was approved by the Ethics Committee of the Kyushu University Graduate School of Medical Sciences. Written informed consent was not required because of the retrospective observational nature of this study, which used national registry data, and the fact that enrolled subjects were deidentified by the Fire and Disaster Management Agency (FDMA).

Hierarchical network systems: An application to high-technology industry in China

In real world situations, there is a hierarchical structure exists in a specific organization and each component has its network process. However, such hierarchical network system has not been well studied in previous literature, and misleading results often are produced. The current paper discusses a data envelopment analysis (DEA) modelling technique for a network structure where a hierarchical system consists of components having two-stage series processes. An additive network DEA is proposed to evaluate the performance of this type of network structure. The overall and divisional efficiencies of the system and each component can be derived, and the relationship between system efficiency, divisional efficiency and the ones of components is discussed. The newly developed additive network DEA is nonlinear and cannot be converted into a linear program. A semidefinite programming (SDP) approach is developed for effectively solving this model and the global solution can be guaranteed. Another linear multiplicative network DEA also developed for this hierarchical system. The two newly developed models are illustrated with a case of the performance evaluation of high-technology industry in China.

Projections of temperature-related excess mortality under climate change scenarios

SummaryBackgroundClimate change can directly affect human health by varying exposure to non-optimal outdoor temperature. However, evidence on this direct impact at a global scale is limited, mainly due to issues in modelling and projecting complex and highly heterogeneous epidemiological relationships across different populations and climates.MethodsWe collected observed daily time series of mean temperature and mortality counts for all causes or non-external causes only, in periods ranging from Jan 1, 1984, to Dec 31, 2015, from various locations across the globe through the Multi-Country Multi-City Collaborative Research Network. We estimated temperature–mortality relationships through a two-stage time series design. We generated current and future daily mean temperature series under four scenarios of climate change, determined by varying trajectories of greenhouse gas emissions, using five general circulation models. We projected excess mortality for cold and heat and their net change in 1990–2099 under each scenario of climate change, assuming no adaptation or population changes.FindingsOur dataset comprised 451 locations in 23 countries across nine regions of the world, including 85 879 895 deaths. Results indicate, on average, a net increase in temperature-related excess mortality under high-emission scenarios, although with important geographical differences. In temperate areas such as northern Europe, east Asia, and Australia, the less intense warming and large decrease in cold-related excess would induce a null or marginally negative net effect, with the net change in 2090–99 compared with 2010–19 ranging from −1·2% (empirical 95% CI −3·6 to 1·4) in Australia to −0·1% (−2·1 to 1·6) in east Asia under the highest emission scenario, although the decreasing trends would reverse during the course of the century. Conversely, warmer regions, such as the central and southern parts of America or Europe, and especially southeast Asia, would experience a sharp surge in heat-related impacts and extremely large net increases, with the net change at the end of the century ranging from 3·0% (−3·0 to 9·3) in Central America to 12·7% (−4·7 to 28·1) in southeast Asia under the highest emission scenario. Most of the health effects directly due to temperature increase could be avoided under scenarios involving mitigation strategies to limit emissions and further warming of the planet.InterpretationThis study shows the negative health impacts of climate change that, under high-emission scenarios, would disproportionately affect warmer and poorer regions of the world. Comparison with lower emission scenarios emphasises the importance of mitigation policies for limiting global warming and reducing the associated health risks.FundingUK Medical Research Council.

A new method for optimizing the parameters of torsional vibration dampers

Torsional vibration dampers (TVDs) are essential components for reducing the torsional vibration of a vehicle power transmission system (VPTS). This paper presents a new parameter optimization method for designing TVDs. The method combines the modal inertia and energy methods by adjusting the modal inertia method using an adjustment factor that is optimized using the energy method. The optimization of TVD parameters seeks to minimize the maximum torsional elastic potential energy of the rear axle near the resonance speed, so that the design variables can be optimized by a manual search process. The proposed method is employed to optimize the parameters of single-stage, two-stage parallel, and two-stage series TVDs coupled to a model VPTS. The damping effects of TVDs optimized by the modal inertia method, the energy method, and the proposed method were compared and analyzed, and the calculation efficiencies of the methods were evaluated. Results show that the proposed method provides better damping effects than the modal inertia method, and also provides far better computing efficiency than the energy method.

Feasibility Study of a Moving Centerline Exponentially Weighted Moving Average Control Chart to Detect Real Warning for Daily Output QA in Proton

The purpose of this study is to verify the usefulness of moving centerline exponentially weighted moving average (MCEWMA) chart, as compared an autoregressive integrated moving average (ARIMA) two-stage time series model, and MCEWMA chart approach, specific to detect the small variation detection in the daily output QA process. A total of 180 individual observations were taken on each of daily output measurements over a period of time in defined daily interval. The conventional control chart recommended for individual observation is primarily based on the assumption that the process data are independent and normally distributed. If the data set is correlated, conventional control charts can cause a substantial increase in the false alarm rate. For this reason, QA observations were analyzed using the autocorrelation function to find appropriate time series models. An ARIMA time series model and an MCEWMA variable control chart were both applied to identical output QA data. An autocorrelation function plot for daily output data at lag 1 and 2 result in r1=0.51 and r2=0.44, respectively. This is certainly large enough to severely distort control chart performance. In the ARIMA and MCEWMA control charts, 2 points fell out of the limits. This was the same result as the two-stage time series modeling and the special control chart, MCEWMA approach. Both indicate the output QA process is reasonably stable, with out-of-control signals where an assignable cause may be present. In the ARIMA model, applying control charts to several process variables and developing an explicit time series model for each variable of interest is potentially time-consuming. However, MCEWMA chart is simple and easy to implement with comparable results. The MCEWMA charts can detect meaningful, small shifts for individual data responses that are autocorrelated. This case study confirms the suitability of MCEWMA which is recommended as an alternative to the time series model and residual special control chart approach.

A two-stage series diode for intense large-area moderate pulsed X rays production.

This paper presents a method for moderate pulsed X rays produced by a series diode, which can be driven by high voltage pulse to generate intense large-area uniform sub-100-keV X rays. A two stage series diode was designed for Flash-II accelerator and experimentally investigated. A compact support system of floating converter/cathode was invented, the extra cathode is floating electrically and mechanically, by withdrawing three support pins several milliseconds before a diode electrical pulse. A double ring cathode was developed to improve the surface electric field and emission stability. The cathode radii and diode separation gap were optimized to enhance the uniformity of X rays and coincidence of the two diode voltages based on the simulation and theoretical calculation. The experimental results show that the two stage series diode can work stably under 700 kV and 300 kA, the average energy of X rays is 86 keV, and the dose is about 296 rad(Si) over 615 cm2 area with uniformity 2:1 at 5 cm from the last converter. Compared with the single diode, the average X rays' energy reduces from 132 keV to 88 keV, and the proportion of sub-100-keV photons increases from 39% to 69%.

Quantifying characteristic growth dynamics in a semi-arid grassland ecosystem by predicting short-term NDVI phenology from daily rainfall: a simple four parameter coupled-reservoir model

Predicting impacts on phenology of the magnitude and seasonal timing of rainfall pulses in water-limited grassland ecosystems concerns ecologists, climate scientists, hydrologists, and a variety of stakeholders. This report describes a simple, effective procedure to emulate the seasonal response of grassland biomass, represented by the satellite-based normalized difference vegetation index (NDVI), to daily rainfall. The application is a straightforward adaptation of a staged linear reservoir that simulates the pulse-like entry of rainwater into the soil and its redistribution as soil moisture, the uptake of water by plant roots, short-term biomass development, followed by the subsequent transpiration of water through foliage. The algorithm precludes the need for detailed, site specific information on soil moisture dynamics, plant species, and the local hydroclimate, while providing a direct link between discrete rainfall events and consequential biomass responses throughout the growing season. We applied the algorithm using rainfall data from the Central Plains Experimental Range to predict vegetation growth dynamics in the semi-arid shortgrass steppe of North America. The mean annual rainfall is 342 mm, which is strongly bifurcated into a dominantly ‘wet’ season, where during the three wettest months (May, June and July) the mean monthly rainfall is approximately 55 mm month−1; and a ‘dry’ season, where during the three driest months (December, January and February), the mean monthly rainfall is approximately 7 mm month−1. NDVI data from the Moderate Resolution Imaging Spectroradiometer (MODIS) MOD13Q1 16 day, 250 m × 250 m product were used as a proxy for grassland phenology for the period-of-record 2000–2013. Allowing for temporal changes in basic parameters of the response function over the growing season, the predicted response of the model tracks the observed NDVI metric with correlation coefficients exceeding 0.92. A two-stage series reservoir is preferred, whereby the characteristic time for transfer of a rainfall event to the peak response of NDVI decreases from 24 days (early growing season) to 12 days (late growing season), while the efficiency of a given volume of rainfall to produce a correspondingly similar amount of aboveground biomass decreases by a factor of 40% from April to October. Behaviours of the characteristic time of greenup and loss of rainfall efficiency with progression of the growing season are consistent with physiological traits of cool-season C3 grasses versus warm-season C4 grasses, and with prior research suggesting that early season production by C3 grasses is more responsive to a given amount of precipitation than mid-summer growth of C4 shortgrasses. Our model explains >90% of seasonal biomass dynamics. We ascribe a systematic underprediction of observed early season greenup following drought years to a lagged or ‘legacy’ effect, as soil inorganic nitrogen, accumulated during drought, becomes available for future plant uptake.

Photonic circuit for high order USB and LSB separation for remote heterodyning: analysis and simulation

A novel photonic integrated circuit is proposed that, using an RF source, generates at its output ports the same magnitude but opposite sign high order single optical side bands of a suppressed optical carrier. A single stage parallel Mach-Zehnder Modulator (MZM) and a two-stage series parallel MZM architecture are described and their relative merits discussed. A transfer matrix method is used to describe the operation of the circuits. The theoretical analysis is validated by computer simulation. As an illustration of a prospective application, it is shown how the circuit may be used as a key element of an optical transmission system to transport radio signals over fibre for wireless access; generating remotely a mm-wave carrier modulated by digital IQ data. A detailed calculation of symbol error rate is presented to characterise the system performance. The circuit may be fabricated in any integration platform offering a suitable phase modulator circuit element such as LiNbO(3), Silicon, and III-V or hybrid technology.

Temporal Variation In Heat-Mortality Associations: A Multi-Country Study

Introduction: Recent investigations have reported a decline in the heat-related mortality risk during the last decades. However, these studies are frequently based on modelling approaches that do not fully characterize the complex temperature-mortality relationship, and are limited to single cities or countries. In this contribution, we investigate the issue using a multi-country data set and flexible modelling techniques. Methods: We collected daily time series data of temperature and all-cause mortality for 272 locations in 7 countries, with a total 20,203,690 deaths occurring in summer months between 1985 and 2012. The analysis is based on two-stage time series models. The heat-mortality relationship was estimated in each location with time-varying distributed lag non-linear models, based on a bivariate spline to model the exposure-lag-response over lag 0-10. The temporal variation was expressed through an interaction between the bivariate spline variables and calendar time. The overall cumulative exposure-response curves predicted for the years 1993 and 2006 were pooled by country through multivariate meta-analysis. Results: Several countries show a significant attenuation in mortality risk due to heat. Time-varying relative risks for the 99th percentile vs the temperature of minimum mortality decrease from 1993 to 2006 in Japan (1.16 to 1.06), Spain (1.56 to 1.37) and the USA (1.12 to 1.02). Estimates from Australia and South Korea are unclear due to lack of statistical power, while no variation seems to occur in the UK (1.16 to 1.17). In the USA, there is evidence of a stronger attenuation for moderate compared to more extreme heat. Conclusions: The mortality risk associated to high ambient temperature has decreased substantially in most of the countries during the last decades. While in some populations the risk is almost completely abated for moderate heat, an excess persists for more extreme temperatures in all the countries at the end of the study period.