Conservative Elements Research Articles

A GENERAL FRAMEWORK FOR MINIMIZING ENERGY CONSUMPTION OF SERIES ELASTIC ACTUATORS WITH REGENERATION.

The use of actuators with inherent compliance, such as series elastic actuators (SEAs), has become traditional for robotic systems working in close contact with humans. SEAs can reduce the energy consumption for a given task compared to rigid actuators, but this reduction is highly dependent on the design of the SEA's elastic element. This design is often based on natural dynamics or a parameterized optimization, but both approaches have limitations. The natural dynamics approach cannot consider actuator constraints or arbitrary reference trajectories, and a parameterized elastic element can only be optimized within the given parameter space. In this work, we propose a solution to these limitations by formulating the design of the SEA's elastic element as a non-parametric convex optimization problem, which yields a globally optimal conservative elastic element while respecting actuator constraints. Convexity is proven for the case of an arbitrary periodic reference trajectory with a SEA capable of energy regeneration. We discuss the optimization results for the tasks defined by the human ankle motion during level-ground walking and the natural motion of a single mass-spring system with a nonlinear spring. For all these tasks, the designed SEA reduces energy consumption and satisfies the actuator's constraints.

Salinization and arsenic contamination of surface water in southwest Bangladesh

To identify the causes of salinization and arsenic contamination of surface water on an embanked island (i.e., polder) in the tidal delta plain of SW Bangladesh we collected and analyzed water samples in the dry (May) and wet (October) seasons in 2012–2013. Samples were collected from rice paddies (wet season), saltwater ponds used for brine shrimp aquaculture (dry season), freshwater ponds and tidal channels (both wet and dry season), and rainwater collectors. Continuous measurements of salinity from March 2012 to February 2013 show that tidal channel water increases from ~0.15 ppt in the wet season up to ~20 ppt in the dry season. On the polder, surface water exceeds the World Health Organization drinking water guideline of 10 μg As/L in 78% of shrimp ponds and 27% of rice paddies, raising concerns that produced shrimp and rice could have unsafe levels of As. Drinking water sources also often have unsafe As levels, with 83% of tubewell and 43% of freshwater pond samples having >10 μg As/L. Water compositions and field observations are consistent with shrimp pond water being sourced from tidal channels during the dry season, rather than the locally saline groundwater from tubewells. Irrigation water for rice paddies is also obtained from the tidal channels, but during the wet season when surface waters are fresh. Salts become concentrated in irrigation water through evaporation, with average salinity increasing from 0.43 ppt in the tidal channel source to 0.91 ppt in the rice paddies. Our observations suggest that the practice of seasonally alternating rice and shrimp farming in a field has a negligible effect on rice paddy water salinity. Also, shrimp ponds do not significantly affect the salinity of adjacent surface water bodies or subjacent groundwater because impermeable shallow surface deposits of silt and clay mostly isolate surface water bodies from each other and from the shallow groundwater aquifer. Bivariate plots of conservative element concentrations show that all surface water types lie on mixing lines between dry season tidal channel water and rainwater, i.e., all are related by varying degrees of salinization. High As concentrations in dry season tidal channel water and shrimp ponds likely result from groundwater exfiltration and upstream irrigation in the dry season. Arsenic is transferred from tidal channels to rice paddies through irrigation. Including groundwater samples from the same area (Ayers et al. in Geochem Trans 17:1–22, 2016), principal components analysis and correlation analysis reveal that salinization explains most variation in surface water compositions, whereas progressive reduction of buried surface water by dissolved organic carbon is responsible for the nonconservative behavior of S, Fe, and As and changes in Eh and alkalinity of groundwater.

Julius Caesar across borders: The ethos of the American republic

In order to endow the newborn American state with legitimacy, the founders of the country sought a connection to the ancient Roman republican past. William Shakespeare's Julius Caesar has an honoured place in the creation of that American democratic ethos. While performances during the colonial and post-revolutionary periods may have been rare, this play was frequently taught at that time, usually in excerpted format. While Shakespeare's text is ambiguous ideologically, balanced between libertarian and conservative monarchical elements, these excerpts constructed an unabashedly republican drama whose purpose was to advocate for democracy, infusing the patriotic ethos of the republic into American youth and immigrants.

The 1917 Russian Revolution and Eastern Orthodox Christian Utopianism

ABSTRACT This article attempts to open an alternative perspective in thinking about the role Eastern Orthodox Christianity played in the 1917 Russian revolution by challenging the prevailing paradigm that it was a conservative cultural element resisting social change. Weber claimed that Calvinism managed to turn a particular conception of the world into a corresponding practical norm that aided the development of capitalism. This article proposes a similar thesis regarding the Russian revolution, but utilizing as its theoretical framework Gramsci's ideas on cultural hegemony and Bloch's view about the role of utopian thinking. It argues that Orthodox Christianity was the source of hegemonic cultural values and as such was the familiar semantic background against which the majority of Russians interpreted, accepted, and fought for the socialist ideals of the revolution. In constructing its argument the article provides a critique and a corrective of Gramsci's understanding of cultural hegemony in Russia, analyzes the Orthodox idea of podvig as an enduring perpetual push from the immanent and the imminent of the historical toward the transcendent and the eternal of the utopian divine, and finally, discusses the implications of podvig's theological connotations as a cultural value and a “subjective force” in sustaining the revolutionary efforts.

Ice fish otoliths record dynamics of advancing and retreating sea ice in Antarctica

AbstractTrace element concentrations within fish otoliths act as biological tags and environmental chronometers within aquatic environments. Linking patterns in elemental concentrations within ice fish otoliths to sea ice dynamics allows us to better understand the chemical dynamics of ice‐covered environments. Here laser ablation inductively coupled plasma mass spectrometry was used to measure the concentrations of conservative and bioactive trace elements in yearly otolith bands of two benthic ice fishes and one cryopelagic ice fish collected from sites along the gradient in sea ice persistence in McMurdo Sound, Antarctica. We used a 12‐yr time series of satellite images to define summertime extent of ice cover from 2002 to 2014. Elemental concentrations of Sr and Li were higher in the otoliths of the cryopelagic species, while Mn concentrations were higher in the otoliths of benthic species, reflecting differences in species' association with sea ice melt and formation. Multivariate dispersion of individual elemental concentrations was greater within the cryopelagic species, indicative of their more transient residence among sites. Key bioactive and conservative elements differed among years with contrasting sea ice dynamics for both cryopelagic and benthic ice fish species. These differences were likely due to sea ice formation concentrating trace metals from the water column and incorporating resuspended sediments, dust, or glacial meltwater with high metal content. Our results provide strong evidence for the effectiveness of trace element concentration profiles in otoliths as environmental recorders of the dynamics of sea ice conditions, and for the role of ice fish as environmental sentinels in Antarctica.

Effect of mesoscopic conservative phenomena in the dynamics of chemical reactions at the macroscopic scale

This paper studies the influence of conservative phenomena at the mesoscopic scale that affect the behavior of macroscopic variables in chemical reactions, generally understood as purely dissipative processes and whose mathematical formulation is usually derived using macroscopic variables. It is shown that conservative phenomena at the mesoscopic scale can affect the entropy production by transiently “pulling away” the system from the thermodynamic equilibrium. Two case studies are presented to illustrate this fact: the first one is an isolated system with a single reaction including two different scenarios, a purely dissipative reaction; and a second one that considers the influence of conservative elements at the mesoscopic scale. The second case generalizes the results to multiple reactions.

Nationwide Surveillance of Clinical Carbapenem-resistant Enterobacteriaceae (CRE) Strains in China

The increasing incidence of carbapenem-resistant Enterobacteriaceae (CRE) - mediated hospital infections in China prompted a need to investigate the genetic basis of emergence of such strains. A nationwide survey was conducted in China covering a total of 1105 CRE strains collected from 25 geographical locales with results showing that acquisition of two carbapenemase genes, blaKPC-2 and blaNDM, was responsible for phenotypic resistance in 90% of the CRE strains tested (58% and 32% respectively), among which several major strain types, such as ST11 of K. pneumoniae and ST131/ST167 of E. coli, were identified, suggesting that dissemination of specific resistant clones is mainly responsible for emergence of new CRE strains. Prevalence of the fosA3 gene which mediates fosfomycin resistance, was high, while the colistin resistance determinant mcr-1 was rarely present in these isolates. Consistently, the majority of the blaNDM-bearing plasmids recoverable from the test strains belonged to IncX3, which contained a common core structure, blaNDM-blaMBL-trpF. Likewise, the core structure of ISKpn27-blaKPC-2-ISKpn2 was observed among plasmids harboring the blaKPC-2 gene, although they were genetically more divergent. In conclusion, the increasing prevalence of CRE strains in China is attributed to dissemination of conservative mobile elements carrying blaNDM or blaKPC-2 on conjugative and non-conjugative plasmids.

A conservative stable finite element method for Stokes flow and nearly incompressible linear elasticity on rectangular grid

In this paper, we discuss finite element methods for the incompressible Stokes problem and the nearly incompressible linear elasticity problem. Specifically, we present a finite element pair for the incompressible Stokes problem, which satisfies the discrete inf–sup condition and the discrete Korn’s inequality, and moreover, which is element-wise conservative. The pair provides a locking-free method for the nearly incompressible linear elasticity problem without reduced integration.

Transnational connectivity, cultural interaction and selective adaptation: English Corinthians and amateur football in the Netherlands, c.1906–39

ABSTRACTThe Corinthians were synonymous with gentlemanly amateurism in English association football. They visited the Netherlands in 1906, 1922, 1923, 1924 and 1933, bringing not just a particular way of playing the game but their own socially-exclusive version of amateurism. This had significant appeal in the Netherlands, where soccer had been taken up in the late nineteenth century by middle-class young men for whom English sport signified modernity. In 1906 the Corinthians supplied a convenient model for those seeking to raise standards and improve the quality of the national team. Later, in the 1920s, as soccer became more popular and its social base widened, the tourists were welcomed by socially conservative elements associated with pre-1900 clubs who were anxious to maintain their status and influence despite being outnumbered by the newer volksclubs. Corinthian-style amateurism had many adherents in the Netherlands and the tours prompted the formation of the Swallows (1907) and the Netherlands Corinthians (1922). These clubs, however, were not simply imitators but adapted the original English model for their own purposes.

Authoritarianism, jihadist ideology, and renewal of the religious discourse in Egypt

ABSTRACTCalls for renewing the religious discourse, which have become part of the Egyptian arena after the events of September 11, 2001, reflect a desire to challenge the threat posed by the jihadist ideology and the propagation of Islamophobic approaches. Such calls are not only a religious issue. Renewing the religious discourse is perceived by concerned intellectuals and activists as an important issue revolving around Egypt’s identity and as a requisite for democracy. However, the transition from declarations to a concrete program that deals with epistemological issues and with empirical problems has yet to occur. Furthermore, liberal calls have been met with criticism, marginalized, and even perceived as apostasy. This article examines the discussion and the initiatives that have come up in the last two decades, maintaining that the failure to renew the religious discourse is due not only to the resistance of conservative elements. Rather, this failure is an inseparable part of the political discourse and its limitations, manifested in the alliance between the regime and the religious establishment, which support each other.

Water balance modelling of a uranium mill effluent management system

A water balance model was developed to forecast the management strategy of a uranium mill effluent system, located in northern Saskatchewan, Canada. Mining and milling operations, such as pit dewatering or treated effluent release, can potentially influence the hydrology and the water quality downstream of the operations. This study presents the methodology used to predict water volumes and water quality discharging downstream in surface water bodies. A compartment model representing the three subsequent lakes included in the management system was set up using the software GoldSim®. The water balance allows predicting lake volumes at the daily time step. A mass balance model developed for conservative elements was also developed and allows validating the proportions of inputs and outputs issued from the water balance model. This model was then used as predictive tool to evaluate the impact of different scenarios of effluents management on volumes and chemistry of surface water for short and longer time periods. An additional significant benefit of this model is that it can be used as an input for geochemical modelling to predict the concentrations of all constituents of concern in the receiving surface water.

Soil water migration in the unsaturated zone of semiarid region in China from isotope evidence

Abstract. Soil water is an important driving force of the ecosystems, especially in the semiarid hill and gully region of the northwestern Loess Plateau in China. The mechanism of soil water migration in the reconstruction and restoration of Loess Plateau is a key scientific problem that must be solved. Isotopic tracers can provide valuable information associated with complex hydrological problems, difficult to obtain using other methods. In this study, the oxygen and hydrogen isotopes are used as tracers to investigate the migration processes of soil water in the unsaturated zone in an arid region of China's Loess Plateau. Samples of precipitation, soil water, plant xylems and plant roots are collected and analysed. The conservative elements deuterium (D) and oxygen (18O) are used as tracers to identify variable source and mixing processes. The mixing model is used to quantify the contribution of each end member and calculate mixing amounts. The results show that the isotopic composition of precipitation in the Anjiagou River basin is affected by isotopic fractionation due to evaporation. The isotopic compositions of soil waters are plotted between or near the local meteoric water lines, indicating that soil waters are recharged by precipitation. The soil water migration is dominated by piston-type flow in the study area and rarely preferential flow. Water migration exhibited a transformation pathway from precipitation to soil water to plant water. δ18O and δD are enriched in the shallow (< 20 cm depth) soil water in most soil profiles due to evaporation. The isotopic composition of xylem water is close to that of soil water at the depth of 40–60 cm. These values reflect soil water signatures associated with Caragana korshinskii Kom. uptake at the depth of 40–60 cm. Soil water from the surface soil layer (20–40 cm) comprised 6–12 % of plant xylem water, while soil water at the depth of 40–60 cm is the largest component of plant xylem water (ranging from 60 to 66 %), soil water below 60 cm depth comprised 8–14 % of plant xylem water and only 5–8 % is derived directly from precipitation. This study investigates the migration process of soil water, identifies the source of plant water and finally provides a scientific basis for identification of model structures and parameters. It can provide a scientific basis for ecological water demand, ecological restoration, and management of water resources.

A multi-element sediment record of hydrological and environmental changes from Lake Erie since 1800

Concentrations of aluminum, arsenic, barium, beryllium, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel, potassium, selenium, sodium, tin, titanium, vanadium, and zinc were measured in a surface sediment core from the Sandusky basin of Lake Erie to detail the history of hydrological and environmental changes back to 1800. The results from hierarchical cluster and principal component analyses revealed four elemental groups. All the trace elements clustering with aluminum, iron, and manganese in Group I were enriched due to increased inputs from anthropogenic sources. The two conservative elements sodium and potassium clustering in Group II showed patterns of changes like those of water-level fluctuations. The two carbonate elements calcium and magnesium clustering in Group III showed intriguing but complex carbonate biogeochemistry associated with biogenic production, organic acid-induced dissolution and dilution by organic and aluminosilicate materials. The terrigenous element titanium in Group IV experienced two stages of depletion from increased organic fluxes in the 1820s and 1950s. Following the enactments of stringent regulations in the early 1970s, many of these elemental inputs have reduced considerably. But the concurrent reductions in the Sandusky basin were much slower than previously thought. Large increases in inputs from local storages (internal loading) were required to account for the slow reductions. The increased internal loading was caused by augmented organic materials from accelerated eutrophication which facilitated the transfer, transport, and cycling of many trace metals. This work has implications in ongoing research efforts to tackle the eutrophication problem because the complex ecosystem including the internal loading has changed considerably over the past two centuries.

Lead isotope distribution and enrichment factors in soil profiles around an abandoned Pb-smelter plant

Todos os Santos (all Saints) Bay area on Brazil’s east coast is known for one of the most significant cases of lead contamination in the country owing to the past activities of a Pb-smelter plant. This work was carried out to assess the concentration and sources of Pb based on Pb isotopes and enrichment factor of soil profiles surrounding Todos os Santos Bay in order to understand the expansion of contamination and to help the establishment of Pb regulatory standards for the region. Forty-four samples were collected from soil genetic horizons of six pedons that represent the range of dominant soil properties and geologic materials in the region. Concentrations of Pb and the isotopes 204Pb, 206Pb, 207Pb, and 208Pb were determined on an inductively coupled plasma (quadrupole) mass spectrometry. The soil enrichment factor was calculated using Al and Fe as conservative index elements. Average Pb concentration (15.87 mg kg−1) in uppermost horizons (from all six pedons) is slightly higher than soil background concentrations commonly reported in Brazil. Samples feature a wide range of Pb isotope ratios, ranging from 36.71 to 47.38 for 208Pb/204Pb, 15.00 to 15.65 for 207Pb/204Pb, 16.86 to 20.59 for 206Pb/204Pb, and 1.10 to 1.31 for 206Pb/207Pb. For the enrichment factor calculations, only Fe demonstrated a good agreement with Pb isotopic ratios. Both Pb isotopic composition and enrichment factor were useful tools to distinguishing natural and anthropogenic influence on the Pb soil concentrations.

Aquatic environmental changes and anthropogenic activities reflected by the sedimentary records of the Shima River, Southern China

Reconstructing historical sedimentary records is essential for better understanding the effects of anthropogenic activities on river environments. We used lead-210 to date riverine sediment core from the Shima River in China. We obtained a sedimentary history of 34 years (1982–2015) for core S2, which had a length of 34 cm. The sedimentation rate of 0.304–2.04 cm y−1 was controlled by both flood events and anthropogenic activities. The conservative element content depth profiles remained relatively constant, suggestive of a relatively stable sediment provenance; therefore, the increase in the sedimentation rate over time was mainly the result of domestic and industrial wastewater effluent and the construction of a rubber dam at the middle and lower reach of the Shima River. From 1982 to 2015, the nutrient and trace metal depth profiles could be divided in three periods based on their trends. From 1982 to 1993, the vertical profiles of nutrients (organic carbon, total phosphorus, and total nitrogen) and three trace metals (nickel, zinc, and manganese) were relatively stable; however, the gradual decrease in copper and cadmium was likely associated with a reduction in agricultural chemical application. From 1993 to 2003, a population explosion and rapid industrialization were responsible for an increase in the input of pollutants into the Shima River, which was partly attenuated by water from the Dong River, leading to a gradual increase in nutrient and trace metal contents. Finally, from 2003 to 2015, the Shima River stopped being used as a source of water due to its deteriorating water quality. The relatively lower velocity of the water flow after the recovery of its flow direction and the reconstruction of the rubber dam in 2009 provided advantageous sedimentary conditions, promoting nutrient accumulation and significant trace metal enrichment.

Size-resolved Pb distribution in the Athabasca River shows snowmelt in the bituminous sands region an insignificant source of dissolved Pb

Lead (Pb) is a metal of special importance because of its long history of commercial and industrial use, global atmospheric contamination accelerated by the use of gasoline additives, and health effects, with children being especially vulnerable. Global atmospheric Pb pollution reached its zenith in the 1970’s, but subsequent impacts on freshwater aquatic systems are poorly understood. Employing metal-free sampling and handling protocols, we show that snowmelt from the Athabasca bituminous sands region is an insignificant source of dissolved Pb to the Athabasca River (AR). Total Pb in the AR is low, and almost entirely in particulate form. Lead in the suspended solids in the AR exactly follows thorium (Th), a conservative lithophile element, and a linear regression of Pb against Th (Pb = 1.6 × Th + 0.0; R2 = 0.99) yields a slope identical to the Pb/Th ratio in the Upper Continental Crust. In the “dissolved” fraction, the Pb/Th ratio is equivalent to that of deep, open ocean seawater; and dominated by colloidal forms. Taken together, these results show that the efforts of recent decades to reduce anthropogenic Pb to the environment have been successful: Pb loading to the river can now be explained predominantly by natural processes, namely erosion plus chemical weathering.

Pedagogy, modernity and nationalism in the Caucasus in the age of reaction, 1880–1905

ABSTRACTThe head of the Caucasus Educational District (CED), K.P. Yanovskiy, epitomized the liberal minded reformers in the Russian Empire who saw the reform of pedagogy – introducing modern sciences, languages, critical thinking and emphasis on the individual – as a means to bring modernity and civilization while respecting ethnic, linguistic and religious diversity. The CED became a sort of refuge for liberal reformers among educational administrators, beyond the grasp of conservative elements in St. Petersburg. Yet under their administration, language education policies for local nationalities in the Caucasus shifted from encouraging local languages to demanding instruction in Russian, and Yanovskiy and his colleagues in the CED came to be viewed in the narratives of nationalists as instruments of russification and assimilation. Using archival sources and other contemporary materials, this article examines the intersection of reform and nationalism in the question of language pedagogy in schools in the Caucasus at a time of state-directed centralization in the Russian Empire and seeks to understand the often complex motives behind the changes in policy and their unintended consequences.

Mixed Volume Element-Characteristic Fractional Step Difference Method for Contamination from Nuclear Waste Disposal

A nonlinear system with boundary-initial value conditions of convection–diffusion partial differential equations is presented to describe incompressible nuclear waste disposal contamination in porous media. The flow pressure is determined by an elliptic equation, the concentrations of brine and radionuclide are formulated by convection–diffusion equations, and the transport of temperature is defined by a heat equation. The pressure appears in convection–diffusion equations and heat equation in the form of Darcy velocity and controls the physical processes. The fluid pressure and velocity are solved by the conservative mixed volume element and the computation accuracy of Darcy velocity is improved one order. A combination method of the mixed volume element and the approximation of characteristics is applied to solve the brine and heat, where the diffusion is discretized by a mixed volume element method and the convection is treated by the method of characteristics. The characteristics can confirm strong computation stability at sharp fronts and it can avoid numerical dispersion and nonphysical oscillation. Larger time-steps along the characteristics are shown to result in smaller time-truncation errors than those resulting from standard methods. The mixed volume element method has the property of conservation on each element and it can obtain numerical solutions of the brine and adjoint vectors. The radionuclide is solved by a coupled method of characteristics and fractional step difference. The computational work is reduced greatly by decomposing a three-dimensional problem into three successive one-dimensional problems and using the algorithm of speedup. Using numerical analysis of priori estimates of differential equations, we demonstrate an optimal second order estimate in $$l^2$$ norm. Numerical data are appropriate with the scheme and it is shown that the method is a powerful tool to solve the well-known problems in porous media.

Policymaking in a ‘Christian nation’: women’s and LGBT+ rights in The Bahamas’ 2016 referendum

ABSTRACTIn 2014, a gender equality referendum was announced in The Bahamas. Four bills were presented in an attempt to neutralise transference of citizenship under the constitution and add sex to the prohibited grounds of discrimination. Dates were announced and postponed several times while the appointed Constitutional Commission conducted its educational campaign. In 2016, a new date was finally announced, and the campaign against gender equality grew in strength and number of supporters, led by religious leaders. Where misogyny failed, homophobia and xenophobia scared and angered the majority, and it became clear that the bills would fail in referendum. The No Campaign run by religious leaders, in churches and public spaces, was one that depended on fear, conservative leanings, and fundamentalist interpretations of The Bible. This article focuses on the experience of the gender equality campaign, focusing on the voice and role of the LGBT+ community, opposing legal authorities, and combating the harmful ideas put forth by fundamentalist and conservative elements in the Christian church over a two-year period.

Оценкa реaлизaции демокрaтических норм для нaционaльного строительствa в Кaзaхстaне

Being located in the center of Eurasia, Kazakhstan has long been at the intersection of ancient civilizations of world and at the crossroads of major transport arteries. Thus it has been a site for a negotiation of social and economic, cultural and ideological relations between East and West, North and South, between Europe and Asia. At different stages in history, Kazakhstan has been home to many nations with distinctive cultural histories which have, in turn, been absorbed into modern Kazakhstan. In the pre-1991 period, the first and foremost issue that the Central Asian countries confronted was the issue of nation-building. The experience was that the Central Asian elite belonged to the most conservative and hardline element of the Soviet political establishment, which strongly resisted Mikhail Gorbachev’s policy of Glasnost (openness) and democratization. Even during the Perestroika period, the Central Asian leaders perceived the emergence of various opposition parties and groups in their Republics as a direct challenge to their position and power. They were preoccupied with the idea of preventing «unproductive and damaging reforms» and of consolidating their power without democratization and radical changes in political and state institutions. This, did not stop the discussion of possible «models of development» for the Central Asian Republics (CARs), which dominated the intellectual discourse in the region throughout the 1990s. It was especially intensive in Kazakhstan, Kyrgyzstan and Uzbekistan on the eve of the dissolution of the Soviet Union and during the very first stage of independence. A number of developmental models were floated around – the Turkish secular political model versus the Iranian theocratic model, the Chinese model of gradual economic reform versus Russia’s shock therapy model etc- to mention a few. Let us consider how today is evaluated the implementation of the Democratic norms for Nation-Building in KazakhstanKey words: Central Asia, democracy, norms and values, national construction, models of the choice of development.