Temporal Differentiation Research Articles

Inflorescence preformation prior to winter: a surprisingly widespread strategy that drives phenology of temperate perennial herbs.

Organ preformation in overwintering buds of perennial plants has been known for almost two centuries. It is hypothesized to underlie fast growth and early flowering, but its frequency, phylogenetic distribution, and ecological relevance have never been systematically examined. We microscopically observed inflorescence preformation in overwintering buds (IPB) in the autumn. We studied a phylogenetically and ecologically representative set of 330 species of temperate perennial angiosperms and linked these observations with quantitative data on species' flowering phenology, genome size, and ecology. IPB was observed in 34% of species examined (in 14% species the stamens and/or pistils were already developed). IPB is fairly phylogenetically conserved and frequent in many genera (Alchemilla, Carex, Euphorbia, Geranium, Primula, Pulmonaria) or families (Ranunculaceae, Euphorbiaceae, Violaceae, Boraginaceae). It was found in species of any genome size, although it was almost universal in those with large genomes. Compared with non-IPB species, IPB species flowered 38d earlier on average and were more common in shaded and undisturbed habitats. IPB is a surprisingly widespread adaptation for early growth in predictable (undisturbed) conditions. It contributes to temporal niche differentiation and has important consequences for understanding plant phenology, genome size evolution, and phylogenetic structure of plant communities.

Physicochemical Differentiation of the Muskau Arch Pit Lakes in the Light of Long-Term Changes

Thirteen pit lakes of the Muskau Arch (Western Poland) were studied in the summer season of 2016. The lakes display great geomorphological and hydrochemical diversity. The aim of the study was to characterize temporal changes in the physicochemical conditions of the pit lakes over the last 30 years (1986–2016) and to determine the main factors influencing their evolution. All the lakes were characterized in terms of the same set of physicochemical parameters measured and used for comparative analysis with literature data from the years 1986 and 1992. The results showed significant temporal differentiation in terms of morphometric features and most of the physicochemical characteristics. pH, EC, Ca2+, Mg2+ and total Fe were among the most significantly differentiating parameters. A similar pattern of changes was found for most of the lakes, suggesting natural fluctuations. Despite the differences in values of thermal and oxygen profiles, there were also similarities in lake stratification. Additionally, meromictic conditions were found in 4 lakes. In some of the lakes a negative effect of neutralization and fertilization of the water was observed. Our results showed that the Muskau Arch lakes are subject to dynamic hydrogeological and hydrochemical changes. In addition to natural changes, human-caused transformations were among the key factors responsible for the differentiation of the physicochemical conditions.

Zoned strategy for water pollutant emissions of China based on spatial heterogeneity analysis.

A zoned strategy based on the spatial heterogeneity of water pollutant emissions is helpful for water environment management. With principal component analysis and clustering analysis, 31 provincial administrative regions (not including Hong Kong, Macao, and Taiwan regions) of China with emissions of 12 kinds of water quality indicators had been categorized into 4 zone type regions. Zone type-1 is the largest emissions of heavy metals, including mining-developed provinces of Hunan and Jiangxi. Zone type-2 is constituted of economically and agriculturally developed with large COD, NH4+-N, TP, and TN emissions, including Hebei, Jiangsu and Zhejiang, Anhui, Shandong, Henan, Hubei, Guangdong, and Sichuan. Zone type-3 only contains Shanxi with massive oil and volatile phenol emissions. Zone type-4 is the other 19 provinces with small discharges of water pollutants. Zone type-4 could be divided into three subclasses which are related to the location of these areas. With these cluster zones, the targeted water pollutant emissions strategy has been put forward in the paper. These methods and ideas of this paper can be further applied to the analysis of spatial and temporal differentiation of pollutant discharges in basins. With the zoning regions, more concrete water pollution prevention and control strategies can be set at a national level.

Seasonal variation of Drosophilidae communities in viticultural landscapes

Studies at the landscape scale are important to understand insect population and community dynamics. Despite numerous studies on the effects of landscape context on phytophagous insect communities, few studies were conducted on fruit flies and the seasonal variation in the effects of landscape context remains poorly explored. Here, we investigate how landscape composition affects Drosophilidae communities in vineyards and how these effects vary over time. To do this, we sampled Drosophilidae communities in 20 vineyards selected along a gradient of proportion cover of semi-natural habitats in the landscape over a whole year in southwestern France. We found an overall positive effect of increasing proportion of semi-natural habitats in the landscape on abundance of drosophilid species but not on the rarefied species richness. We also found strong seasonal changes in community composition with a major temporal differentiation between the two dominant species of the community, Drosophila subobscura and Drosophila suzukii. Our study revealed that the composition of the Drosophilidae communities in vineyards is strongly influenced by the proportion of semi-natural habitats and the time of year. Our results suggest that the variation in space and time of key resources such as host plants or overwintering habitats in the landscape is a key factor affecting community composition of Drosophilidae in crops.

Enhancing Urban Sustainable Indicators in a German City—Towards Human-Centered Measurements for Sustainable Urban Planning

This contribution demonstrates how more human-centered measurements for sustainable urban planning can be created by enlarging the traditional set of urban sustainability indicators. In many municipal reports, sustainable indicators concentrate on environmental issues, by collecting data at an aggregated spatial and temporal level using quantitative methods. Our approach aims to expand and improve the currently dominant quantitative–statistical methods by including perception geographical data (subjective indicators following the social indicator approach), namely additional indicators at spatial and temporal levels. Including small-scale city district levels and a temporal differentiation produces more process assessments and a better representation of everyday life. Based on a survey we conducted at district levels in the city of Karlsruhe, we cover three sustainability dimensions (ecological, social, economic) and analyze (1) how citizens are mobile in a sustainable way (bike use) and (2) how they perceive and react to heat events in the city. We argue for taking people’s perception and the spatiality and temporality of their daily activities better into account when further developing urban sustainability indicators and when aiming for a sustainable, human-centered urban development.

Numerical investigation on the flow and heat transfer characteristics of waxy crude oil during the tubular heating

In industrial practice, tubular heating is known as an effective technology to ensure the security storage of waxy crude oil in the tank. Insights of the thermal and flow behaviors during the tubular heating is a key aspect to optimize the strategy of this heating technology, in order to reduce the cost. In this study the physical and mathematical models representing the heat transfer and flow of waxy crude oil during tubular heating are established. The additional specific heat capacity and momentum source terms methods are employed to address the changing physical properties related to the paraffin crystallization and dissolution. The FVM, PISO and fully implicit first order temporal differentiation algorithms are used to perform the numerical simulation. Our outcomes show that the thermal process during tubular heating can be divided into four phases: ①Local thermal response phase, ②Thermal diffusion phase, ③Global thermal response phase, ④Elimination of gelled oil phase. The initial thermal influence range is inhibited by the thermal condition and solid-like gelled waxy crude oil formed after cooling. The plume flow takes great effects of transferring the heat from the tubes to crude oil and accelerating the phase transition, and finally facilitates the oil temperature uniform increasing in most parts of the tank. Whereas the gelled crude oils in the corner between the sidewall and base wall have the strongest solid-like character and lowest temperature. A low temperature layer keeps covering the base wall. At the top wall, the center region between the sidewall and center of the tank is long time occupied by gelled oil. The proportion of solid-like gelled crude oil keeps decreasing with a small slope value following a linear relationship with heating time. A pronounced phase change of waxy crude oil from the transition state into the pure liquid is observed. The minimum temperature value decreases in the initial heating period, and then steeply increases to an approximate plateau value. The fluctuations of the heating powers are observed indicating the transient thermal convections around the tubes. The heat loss power is lowest at the base wall and nearly unchanged. The heat loss power at top wall and sidewall are significantly influenced by heating tubes and depend on the wall temperature.

Spatial and temporal differentiation of COVID-19 epidemic spread in mainland China and its influencing factors

This paper uses the exploratory spatial data analysis and the geodetector method to analyze the spatial and temporal differentiation characteristics and the influencing factors of the COVID-19 (corona virus disease 2019) epidemic spread in mainland China based on the cumulative confirmed cases, average temperature, and socio-economic data. The results show that: (1) the epidemic spread rapidly from January 24 to February 20, 2020, and the distribution of the epidemic areas tended to be stable over time. The epidemic spread rate in Hubei province, in its surrounding, and in some economically developed cities was higher, while that in western part of China and in remote areas of central and eastern China was lower. (2) The global and local spatial correlation characteristics of the epidemic distribution present a positive correlation. Specifically, the global spatial correlation characteristics experienced a change process from agglomeration to decentralization. The local spatial correlation characteristics were mainly composed of the‘high-high’ and ‘low-low’ clustering types, and the situation of the contiguous layout was very significant. (3) The population inflow from Wuhan and the strength of economic connection were the main factors affecting the epidemic spread, together with the population distribution, transport accessibility, average temperature, and medical facilities, which affected the epidemic spread to varying degrees. (4) The detection factors interacted mainly through the mutual enhancement and nonlinear enhancement, and their influence on the epidemic spread rate exceeded that of single factors. Besides, each detection factor has an interval range that is conducive to the epidemic spread.

Exploring impacts of the Grain for Green program on Chinese economic growth

Research on effects of ecological restoration and afforestation and their links to land conservation and regional development have received global attention. The Chinese government has successively invested a substantial amount of funds in the Grain for Green Program (GGP) since the mid-1990s. The economic effects of the GGP on macroeconomic growth could be attributed to an increase in agricultural production and off-farm employment and follow-up industry development. Few studies have focused on economic effects of the GGP at the national level using long-term series of panel data in 31 provinces and cities across the country. This study analyzed the regional differentiation and temporal-spatial changes in the GGP and investigated economic impacts of the GGP at different scales. Results showed that the scale of the GGP varied significantly in the eastern, central and western regions and regional changes were characterized by temporal differentiation from 2000 to 2016. The GGP had a slightly negative impact on China’s economic growth, which presented an overall U-shape, changed with an increase in economic growth. Significant regional heterogeneities in economic growth and impacts of the GGP were observed in the eastern, central and western regions. In the current situation in China, the technical progress, adjustment of industrial structure and focus on human capital to promote the development of follow-up industries and farmers’ labor skills have demonstrated the role for improving economic growth and optimizing the GGP arrangement. It is crucial to achieve a synergy between ecosystem conservation and regional economic in China.

Full-wave analysis and design of optical fractional-order temporal differentiators based on ultra-compact microring resonator

Optical temporal differentiators (DIFFs) based on on-chip all-pass microring resonators (APMRRs) are the fundamental all-optical signal processing blocks for differentiation of the complex envelope of optical pulses. This paper presents, for the first time to our knowledge, an accurate full-wave analysis for the ultra-compact APMRR-based optical fractional-order temporal DIFFs. The intensity transmission and phase response of the APMRR, and normalized intensity in the output of the temporal DIFFs for ultra-fast optical pulses have been obtained numerically with a high accuracy compared with those of mathematical model. The critically coupled, under-coupled and over-coupled APMRRs have been modelled as mathematical DIFFs. Key factors such as inverse phase response behaviour of the over-coupling regime, time-delay and time-reversal characteristics, finite slope of the phase response in the under and over-coupling regimes, and dependence of the differentiation order to the input pulse full-width at half-maximum (FWHM) have been analysed in detail.

The process of moisture and temperature change of soil profile in Pisha sandstone area

The Pisha sandstone area in Ordos Plateau is a cross zone of water, wind and freeze-thaw erosion. Freeze-thaw erosion is one of the important erosion modes in this area, and soil moisture and temperature are the two key factors affecting it. In order to reveal the change process of soil moisture and temperature with time in the Pisha sandstone area, we took the small watershed of Erlaohugou in Huangfuchuan as the study area. Two sets of EM50 full-automatic collection systems were set up on a typical slope in the area, and the change process of moisture and temperature of the slope from March to September was continuously observed. The results showed that the changes of soil moisture and temperature in this area were greatly affected by seasons and climate. Soil moisture exhibited significant temporal and spatial differentiation, while soil temperature had significant temporal differentiation but not obvious spatial differentiation.

Syndromes of production in intercropping impact yield gains.

Intercropping, the simultaneous production of multiple crops on the same field, provides opportunities for the sustainable intensification of agriculture if it can provide a greater yield per unit land and fertilizer than sole crops. The worldwide absolute yield gain of intercropping as compared with sole crops has not been analysed. We therefore performed a global meta-analysis to quantify the effect of intercropping on the yield gain, exploring the effects of crop species combinations, temporal and spatial arrangements, and fertilizer input. We found that the absolute yield gains, compared with monocultures, were the greatest for mixtures of maize with short-grain cereals or legumes that had substantial temporal niche differentiation from maize, when grown with high nutrient inputs, and using multirow strips of each species. This approach, commonly practised in China, provided yield gains that were (in an absolute sense) about four times as large as those in another, low-input intercropping strategy, commonly practised outside China. The alternative intercropping strategy consisted of growing mixtures of short-stature crop species, often as full mixtures, with the same growing period and with low to moderate nutrient inputs. Both the low- and high-yield intercropping strategies saved 16-29% of the land and 19-36% of the fertilizer compared with monocultures grown under the same management as the intercrop. The two syndromes of production in intercropping uncovered by this meta-analysis show that intercropping offers opportunities for the sustainable intensification of both high- and low-input agriculture.

The evolutionary history of extinct and living lions

Lions are one of the world's most iconic megafauna, yet little is known about their temporal and spatial demographic history and population differentiation. We analyzed a genomic dataset of 20 specimens: two ca. 30,000-y-old cave lions (Panthera leo spelaea), 12 historic lions (Panthera leo leo/Panthera leo melanochaita) that lived between the 15th and 20th centuries outside the current geographic distribution of lions, and 6 present-day lions from Africa and India. We found that cave and modern lions shared an ancestor ca. 500,000 y ago and that the 2 lineages likely did not hybridize following their divergence. Within modern lions, we found 2 main lineages that diverged ca. 70,000 y ago, with clear evidence of subsequent gene flow. Our data also reveal a nearly complete absence of genetic diversity within Indian lions, probably due to well-documented extremely low effective population sizes in the recent past. Our results contribute toward the understanding of the evolutionary history of lions and complement conservation efforts to protect the diversity of this vulnerable species.

Dynamics of Plasmodium vivax populations in border areas of the Greater Mekong sub-region during malaria elimination

BackgroundCountries within the Greater Mekong Sub-region (GMS) of Southeast Asia have committed to eliminating malaria by 2030. Although the malaria situation has greatly improved, malaria transmission remains at international border regions. In some areas, Plasmodium vivax has become the predominant parasite. To gain a better understanding of transmission dynamics, knowledge on the changes of P. vivax populations after the scale-up of control interventions will guide more effective targeted control efforts.MethodsThis study investigated genetic diversity and population structures in 206 P. vivax clinical samples collected at two time points in two international border areas: the China-Myanmar border (CMB) (n = 50 in 2004 and n = 52 in 2016) and Thailand-Myanmar border (TMB) (n = 50 in 2012 and n = 54 in 2015). Parasites were genotyped using 10 microsatellite markers.ResultsDespite intensified control efforts, genetic diversity remained high (HE = 0.66–0.86) and was not significantly different among the four populations (P > 0.05). Specifically, HE slightly decreased from 0.76 in 2004 to 0.66 in 2016 at the CMB and increased from 0.80 in 2012 to 0.86 in 2015 at the TMB. The proportions of polyclonal infections varied significantly among the four populations (P < 0.05), and showed substantial decreases from 48.0% in 2004 to 23.7 at the CMB and from 40.0% in 2012 to 30.7% in 2015 at the TMB, with corresponding decreases in the multiplicity of infection. Consistent with the continuous decline of malaria incidence in the GMS over time, there were also increases in multilocus linkage disequilibrium, suggesting more fragmented and increasingly inbred parasite populations. There were considerable genetic differentiation and sub-division among the four tested populations. Temporal genetic differentiation was observed at each site (FST = 0.081 at the CMB and FST = 0.133 at the TMB). Various degrees of clustering were evident between the older parasite samples collected in 2004 at the CMB and the 2016 CMB and 2012 TMB populations, suggesting some of these parasites had shared ancestry. In contrast, the 2015 TMB population was genetically distinctive, which may reflect a process of population replacement. Whereas the effective population size (Ne) at the CMB showed a decrease from 4979 in 2004 to 3052 in 2016 with the infinite allele model, the Ne at the TMB experienced an increase from 6289 to 10,259.ConclusionsWith enhanced control efforts on malaria, P. vivax at the TMB and CMB showed considerable spatial and temporal differentiation, but the presence of large P. vivax reservoirs still sustained genetic diversity and transmission. These findings provide new insights into P. vivax transmission dynamics and population structure in these border areas of the GMS. Coordinated and integrated control efforts on both sides of international borders are essential to reach the goal of regional malaria elimination.

Weak population structure and recent demographic expansion of the monogenean parasite Kapentagyrus spp. infecting clupeid fishes of Lake Tanganyika, East Africa

Lake Tanganyika, East Africa, is the oldest and deepest African Great Lake and harbours one of the most diverse fish assemblages on earth. Two clupeid fishes, Limnothrissa miodon and Stolothrissa tanganicae, constitute a major part of the total fish catch, making them indispensable for local food security. Parasites have been proposed as indicators of stock structure in highly mobile pelagic hosts. We examined the monogeneans Kapentagyrus limnotrissae and Kapentagyrus tanganicanus (Dactylogyridae) infecting these clupeids to explore the parasites’ lake-wide population structure and patterns of demographic history. Samples were collected at seven sites distributed across three sub-basins of the lake. Intraspecific morphological variation of the monogeneans (n = 380) was analysed using morphometrics and geomorphometrics of sclerotised structures. Genetic population structure of both parasite species (n = 246) was assessed based on a 415 bp fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Overall, we observed a lack of clear geographical morphological differentiation in both parasites along a north–south axis. This lack of geographical population structure was also reflected by a large proportion of shared haplotypes, and a pattern of seemingly unrestricted gene flow between populations. Significant morphological and genetic differentiation between some populations might reflect temporal differentiation rather than geographical isolation. Overall, the shallow population structure of both species of Kapentagyrus reflects the near-panmictic population structure of both host species as previously reported. Morphological differences related to host species identity of K. tanganicanus were consistent with incipient speciation at the genetic level. Both parasite species experienced a recent demographic expansion, which might be linked to paleohydrological events. Finally, interspecific hybridisation was found in Kapentagyrus, representing the first case in dactylogyrid monogeneans.

Coping with a growing number of e-taxis in Greater Stockholm: A stated adaptation approach

The introduction of electric vehicles in taxi companies has shown that operating electric taxis can be profitable and useful already under current circumstances. However, a significant future increase of electric taxis within relatively short time could impose severe challenges to the system. In this paper, current charging patterns and demand for electric taxi rides were analysed to design future scenarios with a significantly higher number of electric taxis and changes in fast charging technology and pricing. A qualitative stated adaptation experiment was carried out among taxi drivers and carriers in order to explore important human factors for coping with changing driving and charging conditions in scenarios with significantly more electric taxis or potential policy changes. The main findings are that hired drivers and carriers react differently to temporal price differentiation. Hired drivers make more use of faster but more expensive charging infrastructure than carriers do. Speed and convenience of charging events seems to be more important for hired drivers than for carriers. An increasing number of electric taxis is likely to increase the strains on urban public charging infrastructure, thereby stimulating charging at home or at currently less popular charging infrastructure. Moreover, there is a risk that the already existing imbalance between carriers and hired drivers could escalate in the future.

Exploration profiles drive activity patterns and temporal niche specialization in a wild rodent

AbstractIndividual niche specialization can have important consequences for competition, fitness, and, ultimately, population dynamics and ecological speciation. The temporal window and the level of daily activity are niche components that may vary with sex, breeding season, food supply, population density, and predator’s circadian rhythm. More recently, ecologists emphasized that traits such as dispersal and space use could depend on personality differences. Boldness and exploration have been shown to correlate with variation in foraging patterns, habitat use, and home range. Here, we assessed the link between exploration, measured from repeated novel environment tests, activity patterns, and temporal niche specialization in wild eastern chipmunks (Tamias striatus). Intrinsic differences in exploration should drive daily activity patterns through differences in energy requirements, space use, or the speed to access resources. We used collar-mounted accelerometers to assess whether individual exploration profiles predicted: 1) daily overall dynamic body acceleration, reflecting overall activity levels; 2) mean activity duration and the rate of activity sequences, reflecting the structure of daily activity; and 3) patterns of dawn and dusk activity, reflecting temporal niche differentiation. Exploration and overall activity levels were weakly related. However, both dawn activity and rate of activity sequences increased with the speed of exploration. Overall, activity patterns varied according to temporal variability in food conditions. This study emphasizes the role of intrinsic behavioral differences in activity patterns in a wild animal population. Future studies will help us understand how yearly seasonality in reproduction, food abundance, and population density modulate personality-dependent foraging patterns and temporal niche specialization.

Regional and temporal differentiation of virulence phenotypes of Puccinia triticina from common wheat in Russia during the period 2001–2018

AbstractLeaf rust, caused by the fungus Puccinia triticina, is one of the most damaging rust diseases of wheat in Russia. Populations of P. triticina were monitored in seven regions of Russia from 2001 to 2018, with a total of 5,191 single urediniospore isolates from bread wheat (Triticum aestivum) being analysed. Populations have changed significantly in all regions since 2012, after 2 years of drought (2010–2011). Regional collections of P. triticina were also significantly different between the two periods 2001–2009 and 2012–2018, with changes along two geographic gradients from West Siberia to the north‐west and south‐west (North Caucasia) of the European part of Russia. All tested isolates were avirulent to resistance gene Lr9 in 2001–2009 but, since 2010, virulence to Lr9 has occurred and annually increased in the Asian part of Russia (Ural and West Siberia) due to deployment of cultivars with the Lr9 gene. Virulence to Lr2a and Lr15 was considerably lower in Dagestan (6%–33%) and all European regions (35%–67%) than in Asian regions (84%–96%). During 2001–2009, virulence on Lr1 was also lower in Dagestan (33%) and the European regions (50%–77%) than in Asia (91%–96%); however, by 2012–2018, nearly all isolates were virulent on Lr1. Remarkable changes were observed in frequencies of P. triticina races defined by their virulence/avirulence to Lr1 and Lr2a genes. We postulate the P. triticina population in Dagestan is specific to that area and pathogen populations in European and Asian parts of Russia are distinct.

Can plant phenology explain species coexistence: A case study in the subtropical evergreen broad-leaved forest of Gutianshan,Zhejiang, China

<p indent="0mm">Species coexistence has always been a major research focus in ecology. Classical coexistence theory indicates that plants can achieve species coexistence through spatial niche differentiation, thereby reducing the competition for resources among species. However, whether plants can also promote species coexistence through temporal niche differentiation (such as phenological differentiation) in the subtropical regions has yet to be tested. We take a subtropical evergreen broad-leaved forest in eastern China as an example. Using reproductive phenology data from 2012 to 2017 for 102 species in the Gutianshan 24 ha permanent plot,we analyzed the phenological differences between species with different functional groups. We found that both the first flowering and fruit time had large temporal niche differentiation. The first flowering had greater variation than the first fruiting time, and that the flowering duration varied less than the fruiting duration. There was no overlap between flowering phenology and fruiting phenology. The phenology of different functional groups differed among species, with the first flowering time significantly earlier in trees than shrubs, but the first fruiting time later in trees than shrubs. The first flowering time was significantly earlier for wind-pollinated trees than insect-pollinated trees, and the first flowering time was also significantly earlier for fleshy-fruit species than nonfleshy-fruit species. The results indicate that differences in plant phenology, which create temporal niches, can reduce resource competition among species and promote community coexistence. Considering species coexistence from the perspective of phenology can help us understand how temporal niches alleviate competition for resources.

Spatial and seasonal variations of organic corrosion inhibitors in the Pearl River, South China: Contributions of sewage discharge and urban rainfall runoff

While organic corrosion inhibitors are ubiquitous in aquatic environments, knowledge on their occurrence, sources and transport in urban surface water is still scarce. In this study, the spatial and seasonal variations of organic corrosion inhibitors and their potential sources were investigated in the Pearl River Delta (PRD), one of the most highly urbanized watersheds in China. A total of 8 compounds belonging to benzothiazole (BTH) and benzotriazole (BTR) groups respectively, were identified in the Pearl River. In addition, there were clear spatial and temporal differentiations in the concentration profiles. The dry season provided higher concentrations of BTH (213–1082 ng L−1) and BTR (112–1279 ng L−1) compared to the wet season (30–574 ng L−1 for BTH and 23–482 ng L−1for BTR), indicating a dominant process of dilution. Remarkably higher concentrations and similar composition features of targets were observed in the effluent samples from two sewage treatment plants (STPs). Our study indicated that rainfall runoff from urban traffic roads during wet season may also be an important contributor to the Pearl River water environment. The annual total mass loading of corrosion inhibitors from the main channel of the Pearl River is 53.2 tons and exhibited strong seasonal variation. Effluents discharge from STPs and urban rainfall runoff from traffic roads are main sources of corrosion inhibitors to the Pearl River.

Terahertz-frequency temporal differentiator enabled by a high-Q resonator.

Terahertz (THz) fundamental "building blocks" equivalent to those used in multi-functional electronic circuits are very helpful for actual applications in THz data-processing technology and communication. Here, we theoretically and experimentally demonstrate a THz temporal differentiator based on an on-chip high-quality (Q) factor resonator. The resonator is made of low-loss high-resistivity silicon material in a monolithic, integrated platform, which is carefully designed to operate near the critical coupling region. The experiment demonstrates that the device can perform the first-order time derivative of the input signal electric field complex envelope at 214.72 GHz. Our investigation provides an effective approach for terahertz pulse re-shaping and real-time differential computing units.