East-west Axis Research Articles

The Effects of Atmospheric Attenuation on Cosmic Ray Muons: How is Surface Level Cosmic Ray Muon Flux Affected by Atmospheric Attenuation?

Cosmic rays are high-energy astronomical particles originating from various sources across the universe. After undergoing nuclear reactions in the upper atmosphere, the primary form they take on the Earth’s surface is in the form of muons. Here, we sought to understand how surface-level cosmic-ray muon flux is affected by atmospheric attenuation by measuring the variation in relative muon-flux rate relative to zenith angle, testing the hypothesis that muons follow an exponential attenuation model. Using a QuarkNet cosmic ray muon detector (CRMD), we collected relative muon-flux data while varying the rotational orientation of the CRMD with respect to the magnetic east-west axis. We then calculated a sensitivity function for the detector with respect to muon entry angle. We parameterized a relative muon angular-density function based on the model of exponential attenuation through the Earth’s atmosphere. Then, we convolved these functions and fitted parameters to experimental data using least-squares regression. The attenuation model predicts an attenuation length of 6.3 km. This result implies that only a maximum of 24% of muons can reach the Earth’s surface, due to both decay and atmospheric interactions. The agreement between data and model (χ2=0.351) provides evidence of exponential muon attenuation through the atmosphere.

Study and construction of the Setif Tramway. An urban project approach?

The Setif Tramway project is a significant urban project, mobilizing, strategic and innovative, which has upset the urban dynamics of the city, by its insertion on its primary East-West axis, representing its backbone.
 This paper aims the apprehension of this project as a city project, through its development process, to understand its approach, and to identify a new posture which speaks of a management system, where the process of “Pluralization” responds to strategic orientations which aim at complementarity between the strategy of political actors and the needs of citizen actors. The aim is to speak about the design and development phase of the Setif tram project. Allowing researchers to develop a roadmap for their projects and helping decision-makers to pilot and manage such operations.

The Head of Fannia pusio (Fanniidae: Diptera) as A Novel Source of Morphometric Data for Assessing of Variation Along Geographic and Biological Lines.

Fannia Robineau-Desvoidy, 1830 is the most diverse genus in the family Fanniidae (Diptera), with 288 species, many of which are include many of sanitary, economic and legal interest. The morphological homogeneity within the genus often makes species determination difficult. The best option for correct identification is to combine molecular and morphological analyses. The variation in the shape of a selection of body characters can be assessed by Geometric Morphometrics using the head as an innovative structure. Sex must be accounted for as a key covariate in this kind of study, since Fannia, as many other Diptera, has a sexually dimorphic head structure, with holoptic males and dicoptic females. Firstly, we analysed a set of Fannia sp. specimens sampled across the Iberian Peninsula (2012-2015), of which Fannia pusio (Wiedemann, 1830) was found to be the most abundant species. Our analyses provide significant morphological information. Fannia pusio exhibits clear intraspecific morphometric variation along an Iberian-wide East-West axis. A similar pattern emerged when comparing a laboratory-bred colony and wild samples.

Povertyopolis: Beyond the East-West Binary in the Late-Nineteenth-Century London Literary Imagination

By siting social problems in the eastern half of the capital city, many writers (both fiction writers and those who purported to be reporting fact) in the final years of the nineteenth century collectively and separately assisted in the emergence of an imaginary London cityscape whose east-west axis (placing poverty physically apart from wealth) served to diminish the true nature of these problems. This crude binary of east versus west failed to represent the systemic, pervasive, pan-London (and in fact, pan-global) ill-effects of advanced capitalism. The east-west polarity acted to confuse and blur the full effects and meanings of how the unregulated labour and housing markets impacted on working-class Londoners wherever they lived in the city. It falsified actual, lived experience and needed to be jettisoned so that a more complex and meaningful picture of metropolitan life could emerge. The true process of ‘immiseration’ should no longer, these writers believed, be occluded by this mythopoeic East — which had become a lazy shorthand for a complex set of problems. In this article, I seek to return to the record the opposition to the east-west binary that, as PJ Keating observed, 1 had emerged in the early 1880s. This opposition was presented by fiction writers including George Gissing, Margaret Harkness and Richard Whiteing; philanthropist and campaigner for working-class girls Maude Stanley; and social investigators Robert Valpy and Arthur Sherwell. Each argued against the polarised vision of London’s socio-economic topography offered by most popular novelists and journalists in the late nineteenth and early twentieth centuries, by which the poor East was presented in contrast to the wealthy West.

Картографический атлас распространения 45 фармакогенетических маркеров в народонаселении России и сопредельных стран

The lack of information about the frequency of pharmacogenetic markers in Russia impedes the adoption of personalized treatment algorithms originally developed for West European populations. The aim of this paper was to study the distribution of some clinically significant pharmacogenetic markers across Russia. A total of 45 pharmacogenetic markers were selected from a few population genetic datasets, including ADME, drug target and hemostasis-controlling genes. The total number of donors genotyped for these markers was 2,197. The frequencies of these markers were determined for 50 different populations, comprised of 137 ethnic and subethnic groups. A comprehensive pharmacogenetic atlas was created, i.e. a systematic collection of gene geographic maps of frequency variation for 45 pharmacogenetic DNA markers in Russia and its neighbor states. The maps revealed 3 patterns of geographic variation. Clinal variation (a gradient change in frequency along the East-West axis) is observed in the pharmacogenetic markers that follow the main pattern of variation for North Eurasia (13% of the maps). Uniform distribution singles out a group of markers that occur at average frequency in most Russian regions (27% of the maps). Focal variation is observed in the markers that are specific to a certain group of populations and are absent in other regions (60% of the maps). The atlas reveals that the average frequency of the marker and its frequency in individual populations do not indicate the type of its distribution in Russia: a gene geographic map is needed to uncover the pattern of its variation.

Spatial and temporal shift in the factors affecting the population dynamics of Calanus copepods in the North Sea.

The swap in abundance between two Calanus species in the North Sea during the 1980s constitutes a quintessential example of regime shift, with important ecosystemic and economic repercussions because these copepods constitute a major component of the diet of larval and juvenile cods. It is hypothesized that this transition was driven by gradual changes in primary productivity, the North Atlantic Oscillation (NAO) and sea surface temperatures (SST), and yet how these factors contribute to the population dynamics of these two species and the overall regime shift remains unclear. Here, we combine a highly resolved and spatially structured longitudinal dataset with population dynamics theory-based models to obtain a thorough and more detailed description of populations' responses to the regime shift observed in the North Sea. Our analyses highlight that this transition exhibits a clear spatial structure and involved a decoupling between the dynamics of Calanus finmarchicus and the NAO in western regions and between Calanus helgolandicus and SST in the eastern regions of the North Sea. Consequently, the observed switch in abundance between these species reflects the interaction between species-specific attributes, a well-defined spatial structure with a marked east-west axis and a decoupling between the ecological drivers and Calanus population dynamics following the shift. Succinctly, we suspect that higher water temperatures have favored C. helgolandicus and resulted in restrictive conditions for C. finmarchicus, eventually overshadowing the effects of NAO detected in historical records. Overall, our study illustrates how population dynamics theory can be successfully employed to disentangle the complex and multifactorial nature of a regime shift in response to gradually changing environmental conditions.

Avaliação dos efeitos microclimáticos de diferentes zonas climáticas locais em cidade de clima temperado

O clima urbano é influenciado por características morfológicas e de uso e ocupação do solo. Aspectos como grau de verticalização, presença de vegetação e adensamento urbano influenciam diretamente sobre variáveis climáticas, gerando microclimas diferenciados na área urbana. Em relação ao conforto ambiental humano, a possibilidade de se prever fenômenos do clima urbano orienta decisões projetuais arquitetônicas e urbanísticas. Esta pesquisa teve por objetivo analisar diferenças térmicas intraurbanas a partir de dados meteorológicos coletados em estações amadoras participantes da rede Weather Underground, localizadas em diferentes zonas climáticas locais (Local Climate Zones - LCZs) em Londres, Inglaterra. Utilizaram-se dados meteorológicos de dez estações distribuídas nos eixos leste-oeste e norte-sul. Avaliou-se se as variações nos microclimas são significativas o bastante para suprir a demanda de energia para aquecimento e resfriamento de edificações, por meio do somatório de graus-hora de aquecimento e resfriamento para cada ponto. Pela análise do perfil longitudinal das temperaturas, a pesquisa constatou a formação de ilhas de calor nos locais com maior intensidade de uso e ocupação e menor cobrimento vegetal. Com relação à demanda por climatização artificial, notaram-se diferenças consideráveis em função da LCZ de cada ponto.

Effect of Solar Tilt Angles on Photovoltaic Module Performance: A Behavioral Optimization Approach

In the present study, performance analyses of a solar module are made through the optimal variation of solar tilt angle, pertaining to the maximum generation of solar energy. The work has been carried out for a particular location at Tripura, in India, considering three different cases on an annual basis. An intelligent behavioural based algorithm, known as artificial bee algorithm (ABC), has been implemented for finding the optimal orientation of solar angle in analysing the performance. The result shows marginal differences are obtained in producing yearly maximum solar energy for different orientations of the PV module. It has been observed that the maximum average solar energy is obtained for the case where continuous adjustment is made by rotating the plane about the horizontal east-west axis within 20° to 30° tilt angle. The computed maximum and minimum of the monthly average efficiency is 10.9% and 8.7%, respectively. Further, a comparative study has been performed in generating average solar energy through optimal tilt angle by the implementation of Perturb & Observe method (P&O). The monthly average solar power computed by P&O method resulted better in a range of 2% to 15% in comparison to that obtained by ABC. While on the other hand, the efficiency computed by ABC algorithm was 15% to 19% better than that evaluated by P&O method for all the cases studied in the present work.

Tracking the marine migration routes of South Pacific silver eels.

Three catadromous Pacific eels (2 Anguilla marmorata, 1 A. megastoma) from the Archipelago of Vanuatu were tagged with pop-up satellite archival transmitters and their migration tracks towards their presumed spawning area approximately 870 km northeast of the point of release were reconstructed in order to evaluate their movements in relation to oceanographic conditions. We used the timing of diel vertical migrations to derive the eels' positions. Two A. marmorata exhibited steep-angled turns resulting in a zig-zag migration path along the east-west axis, while one A. megastoma took a relatively straight course towards the presumed spawning area. They migrated with a speed over ground of 21-23 km day-1. In this region, the eastward flow of the South Equatorial Counter Current (SECC, ∼ 5-10°S) separates the westward flowing South Equatorial Current (SEC; ∼0-5°S and 10-18°S) into two branches. During shallower nighttime migration depths around 150 m eels crossed a variable flow field through the southern branch of the westward SEC with westward propagating mesoscale eddies and the eastward SECC, but stayed south of the stronger northern branch of SEC possibly increasing retention time of larvae within this area. The eels headed towards a tongue of high-salinity Subtropical Underwater (STUW) that may have provided cues for orientation. The eels did not move beyond a salinity front of 35.9-36.0 at a depth of 100-200 m, which may have provided cues for orientation towards the spawning area. These 3 tracks may represent the movements of mature silver eels all the way to where they spawn.

Intraseasonal variability of the equatorial Pacific Ocean and its relationship with ENSO based on Self-Organizing Maps analysis

We investigated the intraseasonal variability of equatorial Pacific subsurface temperature and its relationship with El Nino-Southern Oscillation (ENSO) using Self-Organizing Maps (SOM) analysis. Variation in intraseasonal subsurface temperature is mainly found along the thermocline. The SOM patterns concentrate in basin-wide seesaw or sandwich structures along an east-west axis. Both the seesaw and sandwich SOM patterns oscillate with periods of 55 to 90 days, with the sequence of them showing features of equatorial intraseasonal Kelvin wave, and have marked interannual variations in their occurrence frequencies. Further examination shows that the interannual variability of the SOM patterns is closely related to ENSO; and maxima in composite interannual variability of the SOM patterns are located in the central Pacific during CP El Nino and in the eastern Pacific during EP El Nino. These results imply that some of the ENSO forcing is manifested through changes in the occurrence frequency of intraseasonal patterns, in which the change of the intraseasonal Kelvin wave plays an important role.

Influence of Paleolithic range contraction, admixture and long-distance dispersal on genetic gradients of modern humans in Asia.

Cavalli-Sforza and coauthors originally explored the genetic variation of modern humans throughout the world and observed an overall east-west genetic gradient in Asia. However, the specific environmental and population genetics processes causing this gradient were not formally investigated and promoted discussion in recent studies. Here we studied the influence of diverse environmental and population genetics processes on Asian genetic gradients and identified which could have produced the observed gradient. To do so, we performed extensive spatially-explicit computer simulations of genetic data under the following scenarios: (a) variable levels of admixture between Paleolithic and Neolithic populations, (b) migration through long-distance dispersal (LDD), (c) Paleolithic range contraction induced by the last glacial maximum (LGM), and (d) Neolithic range expansions from one or two geographic origins (the Fertile Crescent and the Yangzi and Yellow River Basins). Next, we estimated genetic gradients from the simulated data and we found that they were sensible to the analysed processes, especially to the range contraction induced by LGM and to the number of Neolithic expansions. Some scenarios were compatible with the observed east-west genetic gradient, such as the Paleolithic expansion with a range contraction induced by the LGM or two Neolithic range expansions from both the east and the west. In general, LDD increased the variance of genetic gradients among simulations. We interpreted the obtained gradients as a consequence of both allele surfing caused by range expansions and isolation by distance along the vast east-west geographic axis of this continent.

The Optimum Performance of Building Integrated Photovoltaic (BIPV) Windows Under a Semi-Arid Climate in Algerian Office Buildings

Recently, Building Integrated Photovoltaic (BIPV) windows have become an alternative energy solution to achieve a zero-energy building (ZEB) and provide visual comfort. In Algeria, some problems arise due to the high energy consumption levels of the building sector. Large amounts of this energy are lost through the external envelope façade, because of the poorness of the window’s design. Therefore, this research aimed to investigate the optimum BIPV window performance for overall energy consumption (OEC) in terms of energy output, heating and cooling load, and artificial lighting to ensure visual comfort and energy savings in typical office buildings under a semi-arid climate. Field measurements of the tested office were carried out during a critical period. The data have been validated and used to develop a model for an OEC simulation. Extensive simulations using graphical optimization methods are applied to the base-model, as well as nine commercially-available BIPV modules with different Window Wall Ratios (WWRs), cardinal orientations, and tilt angles. The results of the investigation from the site measurements show a significant amount of energy output compared to the energy demand. This study revealed that the optimum BIPV window design includes double-glazing PV modules (A) with medium WWR and 20% VLT in the southern façade and 30% VLT toward the east–west axis. The maximum energy savings that can be achieved are 60% toward the south orientation by double-glazing PV module (D). On the other hand, the PV modules significantly minimize the glare index compared to the base-model. The data extracted from the simulation established that the energy output percentages in a 3D model can be used by architects and designers in early stages. In the end, the adoption of optimum BIPV windows shows a significant enough improvement in their overall energy savings and visual comfort to consider them essential under a semi-arid climate.

Paths for colonization or exodus? New insights from the brown bear (Ursus arctos) population of the Cantabrian Mountains.

Over the centuries, the geographical distribution of brown bear (Ursus arctos) across the Iberian Peninsula has been decreasing, with the species currently confined to North Iberia. The Cantabrian brown bear population is one of the smallest in Europe and is structured into two subpopulations, positioned along an east-west axis. Given the current critically endangered status of this population, it is essential to have a clear picture of its within-population genetic patterns and processes. We use a set of three molecular markers (mitochondrial DNA, autosomal microsatellites and sex markers) to clarify the genetic origins and assess the migration patterns and gene flow of the Cantabrian brown bear population. Our results reveal the presence of two different mitochondrial (matrilineal) haplotypes in the Cantabrian population, both belonging to European brown bear clade 1a. The two haplotypes are geographically structured between Eastern (haplotype CanE) and Western Cantabrian (haplotype CanW) subpopulations, which is consistent with the genetic structure previously identified using nuclear markers. Additionally, we show that CanE is closer to the historical Pyrenean (Pyr) haplotype than to CanW. Despite strong structuring at the levels of mtDNA and nuclear loci, there is evidence of bidirectional gene flow and admixture among subpopulations. Gene flow is asymmetrical and significantly more intense from the Eastern to the Western Cantabrian subpopulation. In fact, we only detected first generation male migrants from the Eastern to the Western Cantabrian subpopulation. These results suggest more intense migration from the smaller and more vulnerable Eastern Cantabrian subpopulation towards the larger and more stable Western Cantabrian subpopulation. These new insights are relevant for assessments of on-going conservation measures, namely the role of dispersal corridors and enhanced connectivity. We discuss the importance of complementary conservation measures, such as human-wildlife conflict mitigation and habitat improvement, for the conservation of a viable Cantabrian brown bear population.

A low-cost dual-axis solar tracking system based on digital logic design: Design and implementation

Nowadays, photovoltaic (PV) systems have been being installed rapidly all over the world. However, the installations typically employ a fixed flat-plate system, using pre-specified angles acquired by geographical positioning. Hence, the power generated by PV systems decreases significantly, according to the variation of solar irradiation in the progress of a day and the seasons in a year. In order to increase the solar power generation, this paper proposes the design and implementation of a low-cost automatic dual-axis solar tracker system. The tracking system is designed as a closed-loop control based active tracking system, employing Light Dependent Resistor (LDR) sensors as the inputs of the system. The tracking strategy utilizes a digital logic design of the sensors’ participation implemented in a pseudo-azimuthal system to simply rotate around the primary (north-south) axis and the secondary (east-west) axis. In the experiment, the proposed tracking system and the fixed flat-plate system were evaluated for the comparative study. The experimental results show that the proposed tracking system increased the efficiency of electrical energy by averagely 44.89%, using the proposed system compared with the fixed flat-plate system. Finally, the cost analysis is provided for the proposed tracking system.

Energy, environment and sustainable development of the belt and road initiative: The Chinese scenario and Western contributions

Abstract The Belt and Road Initiative has tremendously increased the interaction of China with the countries involved, pushing forward the integration and comparative phase, based on the main factors affecting the energy, environmental and development scenarios. The indicators of this process are strictly related to the environmental sustainability of projects and infrastructural initiatives which entail aspects regarding climate change, environmental impact, transport management, urbanization and effective utilization of energy. Through this osmotic program, which the Chinese government said in 2013 would be executed from east to west, the contributions Western countries may make to maximize the common efforts are foreseeably very important for the success of the whole BRI and, indirectly, for the harmonization of the very rapid Chinese growth. China held the first position in 2014 for electricity generation (5388 billion kwh/h) and coal production (4.27 billion short tons/year), as well as the second position for petroleum consumption. On the other hand, carbon dioxide emissions were 1.8 times those of the USA in 2015, and transport, urbanization and energy intensity still struggle to attain optimal levels. The quality of productive sectors, research and universities is still low in the world ranking, despite the huge efforts of the Chinese, due to a still slow and cumbersome internationalization process. This article aims to integrate the numerous excellent studies published in the last few years on sustainable development and energy effectiveness within the BRI (Table 1 provides some specific references), by carrying out a systematic analysis of the Chinese energy, environmental and sustainable landscape from a Western perspective, breaking the main areas of the Chinese scenario down into its components and identifying those where the contributions of Western countries can support the gaps coverage. In this respect, the change of viewpoint provided by this study may be beneficial to properly balance the BRI perspective along the east-west axis.

Ancient Rus Cemetery at the Kopyrev Kinets

The article is devoted to archaeological research of the ancient Rus cemetery at the Kopyrev kinets in Kyiv, which functioned from the second half of X to the first half of XIII centuries. In recent years, during its research, at Kudriavska, 24-A and Artema, 12 streets, among numerous archaeological objects, a significant number of burials of different chronological periods were discovered. The largest number of burials was discovered in 1989 and 2016—2018 at Kudriavska st., 24-A. It was also established that this cemetery functioned during several chronological periods. From the second half of X c. there was a burial ground with inhumations, sometimes with accompanying equipment, which disappears with the appearance at this place in the XI — beginning of XII c. of industrial and residential facilities, and in XII — the first half of XIII c. here again appears a burial ground with burials according to the Christian rite. Perhaps the burial of the second chronological period is associated with the functioning of the XII—XIII c. church, which was nearby. It is likely that the restoration of graves at the cemetery after the decline of the housing and crafts district is associated with the expansion of the churchyard. During the excavation of the cemetery from 1989 to 2018, 134 burials were investigated, 11 of which had accompanying inventory. The grave pits had a rectangular shape, almost all were elongated along the west-east axis (most with a slight deviation to the south), and the deceased in them laid with the heads to the west. The general position of the skeletons, the position of the skull and hands were typical for the traditional postures of the dead buried at the orthodox cemetery. Also, during the research, a small number of empty burial pits were found, which may have been dug in advance and not used for their intended purpose. As for those found at Artema st., 12, three burials, judging by the distance between them, perhaps had burial mounds. After analyzing the location of the grave pits and their contents, it was determined that the cemetery had from six to eight rows of burials, and its total area was approximately 2.88 ha.

Trees as a Shading System for Streets on the East–West Axis: Computer Simulations for the Selected Geometrical Proportions of Building Developments in Humid Continental Climate

The study is aimed at investigating the possibilities for solar protection provided to the street canyon located on the E–W axis and with the following profiles: shallow (height/width (H/W) = 0.2, 0.6, and 1) and deep (H/W = 2) by two rows of trees located at a distance of 3 m away from southern and northern façades. The research was based on numerical simulation analyses conducted in the Rhinoceros® program, with the application of the Ladybug Tools environmental plugin for a street set in the city of Płock (52° 32′50″N 19°42′00″E) for the day characterized with the highest total intensity of insolation within the year, 7 June, between 8:00 a.m. and 5:00 p.m. The research yielded no differences in terms of shading the surface of the southern façade of streets with low, medium, and high building developments. However, slight differences (40 m²) were noted for the model with highrise building developments (h = 60 m) characterized with a deep section (H/W = 2). The simulation also revealed that the H/W ratio parameter only slightly (0.88%–1.93%) affected the share trees have in shading the street floor, except in the case of very shallow profiles (H/W = 0.2).

Nalanda

Nalanda, in eastern India's Bihar state, was once the most important Buddhist monastery in the world. The six excavated temples there are oriented approximately to the cardinal directions, but their east–west axes are tilted more than 4° south of east. Other key Buddhist temples within the same cultural milieu (Bodhgaya, Vikramasila, Somapura, and Samye) are similarly oriented a few degrees south of east. As M. B. Rajani and Viraj Kumar argue in Nalanda: A Tale in the Twist, this demands an explanation, because a method to orient structures to within 0.5° of the cardinal directions was known in the region for several centuries prior to the construction of these temples. Rajani and Kumar identify a temporal pattern in the orientation of Nalanda's temples; hypothesize that each temple was aligned with the rise of a specific star (Spica or Beta Librae), with the temporal pattern being a consequence of axial precession; propose a simple, unified explanation for the few exceptions to the pattern; and use this hypothesis to propose an approximate construction date for each temple based on its orientation.

Spatial quantitative analysis of the potential driving factors of land surface temperature in different “Centers” of polycentric cities: A case study in Tianjin, China

Revealing the dominant driving factors of land surface temperature (LST) plays an important role in mitigating the urban heat island (UHI) effect. Numerous international metropolises are developing polycentric forms under the process of suburbanization in conjunction with rapid urbanization, generating new UHI spatial patterns in internal urban areas. To comprehensively understand the effects of multi-factors on the thermal environment, our study examined a typical polycentric city, Tianjin. According to the concept of polycentrism, this study focused on three types of city “centers”: major city core, new district core and industrial park. Eleven potential driving factors of LST were explored from four layers, and the geo-detector model was applied to rank the explanatory degree of these factors on LST. Three different city centers of the polycentric city showed varied UHI spatial pattern characteristics, and their response to the effect of natural factors and social factors on LST were quite diverse. Heat island areas were distributed homogeneously in the major city core; the UHI pattern on the east-west axis was unbalanced in the new district core due to the unsaturated urban space and dynamic planning policies; in industrial park, production areas were segregated by green belts with clear boundaries. For the whole city and the major city core, the imperviousness factor had the highest explanatory rate for LST, followed by the greenness factor. In contrast to the results of previous studies, the wetness factors had a greater impact on LST in the new district core and industrial park, second only to the greenness factor. Furthermore, selected factors exhibited bilinear or nonlinear enhanced relationships in their interactions. The driving laws of LST in different city centers were summarized with an explorative case study, aimed at providing theoretical basis and practical guidance for optimizing urban thermal environment planning, especially for highly urbanized polycentric cities.

Successional trophic complexity and biogeographical structure of eukaryotic communities in waterworks' rapid sand filters.

As groundwater-fed waterworks clean their raw inlet water with sand filters, a variety of pro- and eukaryotic microbial communities develop on these filters. While several studies have targeted the prokaryotic sand filter communities, little is known about the eukaryotic communities, despite the obvious need for knowledge of microorganisms that get in contact with human drinking water. With a new general eukaryotic primer set (18S, V1-V3 region), we performed FLX-454 sequencing of material from 21 waterworks' sand filters varying in age (3-40 years) and geographical location on a 250 km east-west axis in Denmark, and put the data in context of their previously published prokaryotic communities. We find that filters vary highly in trophic complexity depending on age, from simple systems with bacteria and protozoa (3-6 years) to complex, mature systems with nematodes, rotifers and turbellarians as apex predators (40 years). Unlike the bacterial communities, the eukaryotic communities display a clear distance-decay relationship that predominates over environmental variations, indicating that the underlying aquifers feeding the filters harbor distinct eukaryotic communities with limited dispersal in between. Our findings have implications for waterworks' filter management, and offer a window down to the largely unexplored eukaryotic microbiology of groundwater aquifers.