Subterranean Tunnels Research Articles

Crawling without wiggling: muscular mechanisms and kinematics of rectilinear locomotion in boa constrictors.

A central issue for understanding locomotion of vertebrates is how muscle activity and movements of their segmented axial structures are coordinated, and snakes have a longitudinal uniformity of body segments and diverse locomotor behaviors that are well suited for studying the neural control of rhythmic axial movements. Unlike all other major modes of snake locomotion, rectilinear locomotion does not involve axial bending, and the mechanisms of propulsion and modulating speed are not well understood. We integrated electromyograms and kinematics of boa constrictors to test Lissmann's decades-old hypotheses of activity of the costocutaneous superior (CCS) and inferior (CCI) muscles and the intrinsic cutaneous interscutalis (IS) muscle during rectilinear locomotion. The CCI was active during static contact with the ground as it shortened and pulled the axial skeleton forward relative to both the ventral skin and the ground during the propulsive phase. The CCS was active during sliding contact with the ground as it shortened and pulled the skin forward relative to both the skeleton and the ground during the recovery phase. The IS shortened the ventral skin, and subsequent isometric activity kept the skin stiff and shortened during most of static contact while overlapping extensively with CCI activity. The concentric activity of the CCI and CCS supported Lissmann's predictions. Contrary to Lissmann, the IS had prolonged isometric activity, and the time when it shortened was not consistent with providing propulsive force. Decoupling propulsion from axial bending in rectilinear locomotion may have facilitated economical locomotion of early snakes in subterranean tunnels.

Rare earth element enriched birnessite in water-bearing fractures, the Ytterby mine, Sweden

Characterization of a black substance exuding from fractured bedrock in a subterranean tunnel revealed a secondary manganese oxide mineralisation exceptionally enriched in rare earth elements (REE). Concentrations are among the highest observed in secondary ferromanganese precipitates in nature. The tunnel is located in the unsaturated zone at shallow depth in the former Ytterby mine, known for the discovery of yttrium, scandium, tantalum and five rare earth elements.Elemental analysis and X-ray diffraction of the black substance establish that the main component is a manganese oxide of the birnessite type. Minor fractions of calcite, other manganese oxides, feldspars, quartz and about 1% organic matter were also found, but no iron oxides were identified. The Ytterby birnessite contains REE, as well as calcium, magnesium and traces of other metals. The REE, which constitute 1% of the dry mass and 2% of the metal content, are firmly included in the mineral structure and are not released by leaching at pH 1.5 or higher. A strong preference for the trivalent REE over divalent and monovalent metals is indicated by concentration ratios of the substance to fracture water. The REE-enriched birnessite has the general formula Mx(Mn3+,Mn4+)2O4·(H2O)n with M = (0.37–0.41) Ca + 0.02 (REE + Y), 0.04 Mg and (0.02–0.03) other metals, and with [Mn3+]/[Mn4+] = 0.86–1.00.The influence of microorganisms on the accumulation of this REE enriched substance is demonstrated by electron paramagnetic resonance spectroscopy. Results show that it is composed of two or more manganese phases, one of which has a biogenic signature. In addition, the occurrence of C31 to C35 extended side chain hopanoids among the identified lipid biomarkers combined with the absence of ergosterol, a fungal lipid biomarker, indicate that the in-situ microbial community is bacterial rather than fungal.

Resource suitability modulating spatial co‐occurrence of soil‐forager termites (Blattodea: Termitoidea)

AbstractResource can regulate animal foraging range, which in turn determines the chances of species co‐occurrence. Here, we addressed the question of whether resource determines the co‐occurrence of soil‐forager termite species (i.e. those foraging in subterranean tunnels). Eight quadrats (4 × 4 m) were marked in seven sites of Brazilian Atlantic rainforests, giving a total area sampled of 896 m2. Inside each quadrat, we measured the co‐occurrence of soil forager species and the resource suitability (N:C ratio of the soil and litter biomass). The number of records of more than one soil‐forager termite species at a single foraging spot, relative to the total number of foraging spots detected in each forest, was taken as a surrogate for spatial co‐occurrence. We tested whether termite co‐occurrence was mediated by random or nonrandom processes. Data were subjected to linear regression to test how the termite species co‐occurrence responds to resources. We compared this method with a null model analysis. Soil‐forager termites comprised 885 records, 20 species and 14 genera. From those records, 29% indicated species co‐occurrence. Co‐occurrence was not random: occurred more frequently when resource suitability was very high or very low. This result suggests an optimised use of space by termite communities.

Measurement of the Earth tides with a MEMS gravimeter

The ability to measure tiny variations in the local gravitational acceleration allows, besides other applications, the detection of hidden hydrocarbon reserves, magma build-up before volcanic eruptions, and subterranean tunnels. Several technologies are available that achieve the sensitivities required for such applications (tens of microgal per hertz(1/2)): free-fall gravimeters, spring-based gravimeters, superconducting gravimeters, and atom interferometers. All of these devices can observe the Earth tides: the elastic deformation of the Earth's crust as a result of tidal forces. This is a universally predictable gravitational signal that requires both high sensitivity and high stability over timescales of several days to measure. All present gravimeters, however, have limitations of high cost (more than 100,000 US dollars) and high mass (more than 8 kilograms). Here we present a microelectromechanical system (MEMS) device with a sensitivity of 40 microgal per hertz(1/2) only a few cubic centimetres in size. We use it to measure the Earth tides, revealing the long-term stability of our instrument compared to any other MEMS device. MEMS accelerometers--found in most smart phones--can be mass-produced remarkably cheaply, but none are stable enough to be called a gravimeter. Our device has thus made the transition from accelerometer to gravimeter. The small size and low cost of this MEMS gravimeter suggests many applications in gravity mapping. For example, it could be mounted on a drone instead of low-flying aircraft for distributed land surveying and exploration, deployed to monitor volcanoes, or built into multi-pixel density-contrast imaging arrays.

AVALIAÇÃO DE RISCOS GEOLÓGICOS NO PLANEJAMENTO ENERGÉTICO EÓLICO NO RIO GRANDE DO NORTE, BRASIL

Wind power generation has a reputation for being environmentally friendly. However, beyond its clean and renewable aspects, the exploration fields can also be assessed in its relationship with the geographical space, as the risks involved in this activity can be identified in all project phases, going from its implementation to the final moment where the actual energy generation takes place. This article provides a description of the risks related to the physical environment of the wind power generation fields of Macambira I and II, Baixa do Feijao and Aventura, all located in the state of Rio Grande do Norte, Brazil. Although the research focuses on the physical context of the generation fields, it also indicates that social relationships are affected by it. Particularly, the geology mapping demonstrates that there are risks related to the presence of caves. This morphology can be seen on the Jandaira Formation limestone, which is marked by a subterranean tunnel network that occurs in plain terrains. Beyond the geotechnical aspect, which exposes the wind power towers to some risk, there are environmental concerns regarding the regional hidrogeology and the speleological patrimony, as well as the fossil layers that are present on the sedimentary formations. Furthermore, the regional seismic context can also offer risks to the installation of wind power generation towers.

Medieval Georgian Poliorcetica

In the medieval art of war siege constituted one of the principal forms of fight. Several basic techniques were used in taking a stronghold, such as assaulting the walls of the fortress, breaching the wall, digging a subterranean tunnel under the wall and enfeeblement of the garrison by lengthy siege. Bearing in mind various data, in the Middle Ages Georgians used the following technical means to capture fortresses: assault ladders, battering rams and other engines for breaching walls, ballistas, stone throwing engines and subterranean tunnels. In the article light is shed on the siege capabilities of the Georgian army of the period. Extensively discussed are the Georgian army’s stone throwing artillery, various types of stone hurling engines and the time of their spread in Georgia. Various techniques of capturing fortresses, applied by the Georgians are described. These include mounting the walls with ladder or various improvised means. The hazardous technique of directly assaulting the fortress without preliminary preparation or bringing up heavy siege engines is shown. The capturing of fortresses by means of underground tunnels isdiscussed separately. By the available evidence it is not apparent that Georgians made use of all the siege techniques known in the medieval world; however, it can be said that they were familiar with and used successfully the basic methods of siege warfare.

Detecting clandestine tunnels using near-surface seismic techniques

Geophysical detection of clandestine tunnels is a complex problem that has met with limited success. Multiple methods have been applied, spanning several decades, but a reliable solution has yet to be found. We evaluated shallow seismic data collected at a tunnel test site representative of geologic settings found along the southwestern U.S. border. Our results demonstrated the capability of using P-wave diffraction and surface-wave backscatter techniques to detect a purpose-built subterranean tunnel. Near-surface seismic data were also collected at multiple sites in Afghanistan to detect and locate subsurface anomalies, including data collected over the escape tunnel discovered in 2011 at the Sarposa Prison in Kandahar, Afghanistan, which allowed more than 480 prisoners to escape, and data from another shallow tunnel recently discovered at an undisclosed location. The final example from Afghanistan was the first time surface-based geophysical methods have detected a tunnel whose presence and location was not previously known. Seismic results directly led to the discovery of the tunnel. Interpreted tunnel locations for all examples were within less than 2 m of the actual location. Seismic surface-wave backscatter and body-wave diffraction methods showed promise for efficient data acquisition and processing for locating purposefully hidden tunnels within unconsolidated sediments.

Tunneling Performance Increases at Lower Temperatures for Solenopsis invicta (Buren) but not for Nylanderia fulva (Mayr)

Nylanderia fulva (Mayr), the tawny crazy ant, is an invasive pest established in Florida and several other Gulf Coast states. In their invasive ranges in the Southeastern USA, large N. fulva populations have reduced species abundance, even displacing another invasive ant, Solenopsis invicta (Buren). In North Florida, N. fulva populations survive winter temperatures that reach below freezing for extended periods. However, the shallow littoral debris used by N. fulva for nest construction offers little insulation to brood and reproductives when exposed to freezing temperatures. Field populations of N. fulva in North Florida were observed tunneling below ground, a previously undescribed behavior. Other invasive ants exhibit similar subterranean tunneling behavior as a means of thermoregulation. To test the hypothesis that N. fulva has the capacity to construct subterranean tunnels across a range of ecologically relevant temperatures, tunneling performance for N. fulva and S. invicta, another invasive ant that tunnels extensively, were compared at four temperatures (15.0, 18.0, 20.0, and 22.0 °C). Overall, N. fulva tunneled significantly less than S. invicta. Nylanderia fulva tunneled furthest at warmer temperatures whereas S. invicta tunneled furthest at cooler temperatures. However, N. fulva constructed subterranean tunnels at all temperatures evaluated. These data support the hypothesis that N. fulva is capable of tunneling in temperatures as low as 15.0 °C, confirming that this ant can also perform a behavior that is used by other ants for cold avoidance.

Biopores from mole crickets (Scapteriscus spp.) increase soil hydraulic conductivity and infiltration rates

Soil organisms can seasonally and temporally influence many factors of soil formation and structure. Burrowing insects create biopores resulting in preferential flow through the soil profile. Most insect species have one or more life stages in soil, however, social insects are the primary taxa studied in context of soil function and structures. Soil-inhabiting southern mole cricket, Scapteriscus borellii Giglio-Tos and tawny mole cricket, Scapteriscus vicinus Scudder (Orthoptera: Gryllotalpidae), create subterranean tunnels and likely alter soil infiltration and hydraulic conductivity. X-ray CT scans were used to generate three-dimensional images of tunnel characteristics of Scapteriscus mole cricket in different soils and for various life stages. One mole cricket was introduced to a polyvinyl chloride (PVC) cylindrical arena filled with soil and allowed to construct their tunnels for 7 days under controlled conditions in the greenhouse. X-ray CT scans produced high resolution, three-dimensional renderings of tunnel architecture. Greenhouse trials also compared the hydraulic conductivity of saturated soil (Ksat) infested with mole crickets to soil columns with earthworms. Additionally, infiltration and runoff rates were compared under field conditions in bermudagrass (Cynodon dactylon(L.)×Cynodon transvaalensis (Burtt-Davy)) in the presence and absence of mole crickets. Both species produce tunnels generally ≥2.5 times their body in width. Southern mole cricket tunnels produce twice as many tunnels branches near the surface compared to lower in the soil profile. Immature and adult mole crickets produce tunnels that are similarly constructed yet adults displace about three times the amount of soil during immatures. Mole crickets construct tunnels 64.1cm long with 208.8cm3 volume in loamy soils, which is about double the length and volume of tunnels in clay soils. The Ksat was similar when mole crickets or earthworms were present, but both were greater relative to arenas with no soil invertebrates. Under field conditions, plots in bermudagrass where mole crickets were active had 41% reduction in runoff and a 12% greater infiltration relative to un-infested turfgrass. Biopores created by mole crickets in turfgrass and pastures create preferential flow through soil that may increase the movement of water and solutes from the soil to groundwater. This work highlights the interconnections between biodiversity in soils and soil function, and the importance of expanding studies on soil invertebrates beyond the few candidate taxa already studied.

Cirque du Soleil and Its Roots in Illegitimate Circus

Cirque du Soleil and Its Roots in Illegitimate Circus

The location of subterranean voids using tensor gravity gradiometry

This paper discusses the use of signals from tensor gravity gradiometers to target compact, local, subterranean voids. Two generic types of gravitational source are analysed in detail, and compared: a cubical subterranean void, and a subterranean tunnel. A vectorial targeting method is shown to work well with both types of finite target, picking out the centre of mass of the cubical source, and the axis of the tunnel. Some unusual results are reported in connection with the apparent length of the tunnel target, and limitations on the information that may be gleaned from the gravity gradient signals arising from both types of target are discussed.

Inside the Sun Pyramid at Teotihuacan, Mexico: 2008—2011 Excavations and Preliminary Results

After more than a century of explorations at the Sun Pyramid in Teotihuacan, many uncertainties about the function, meaning, chronology, and use of the monument remain unresolved. Here we present preliminary results from excavations and mapping conducted by the Sun Pyramid Project to address some of these issues. We focus particularly on describing the architectural features excavated in the interior of the pyramid as well as the subterranean tunnel. This evidence is used to argue that the subterranean structure was artificially constructed for ritual activities, including the placement of royal burials and/or offerings in its interior. We define three stages in the construction sequence of the Sun Pyramid: (1) a Pre-Sun Pyramid phase, (2) the establishment of the main corpus of the monument, and, finally, (3) the adjoining of the adosada platform. In each phase, we discuss the presence of burials, offerings, or other features uncovered. Furthermore, we present the results of new ceramic and radiocarbon dates that transform our understanding about the construction of the ceremonial center, where the Sun Pyramid and the subterranean tunnel are dated to a later phase than previously thought, from A.D. 170—310 and A.D. 140—240, respectively.

Climbing, falling, and jamming during ant locomotion in confined environments.

Locomotion emerges from effective interactions of an individual with its environment. Principles of biological terrestrial locomotion have been discovered on unconfined vertical and horizontal substrates. However, a diversity of organisms construct, inhabit, and move within confined spaces. Such animals are faced with locomotor challenges including limited limb range of motion, crowding, and visual sensory deprivation. Little is known about how these organisms accomplish their locomotor tasks, and such environments challenge human-made devices. To gain insight into how animals move within confined spaces, we study the locomotion of the fire ant Solenopsis invicta, which constructs subterranean tunnel networks (nests). Laboratory experiments reveal that ants construct tunnels with diameter, D, comparable to body length, L = 3.5 ± 0.5 mm. Ants can move rapidly (> 9 bodylengths per s) within these environments; their tunnels allow for effective limb, body, and antennae interaction with walls, which facilitate rapid slip-recovery during ascending and descending climbs. To examine the limits of slip-recovery in artificial tunnels, we perform perturbations consisting of rapid downward accelerations of the tunnels, which induce falls. Below a critical tunnel diameter, Ds = 1.31 ± 0.02 L, falls are always arrested through rapid interaction of appendages and antennae with tunnel walls to jam the falls. Ds is comparable to the size of incipient nest tunnels (D = 1.06 ± 0.23 L), supporting our hypothesis that fire ants construct environments that simplify their control task when moving through the nest, likely without need for rapid nervous system intervention.

Performance Evaluation of Multi-Hop Communication Based on a Mobile Multi-Robot System in a Subterranean Laneway

For disaster exploration and surveillance application, this paper aims to present a novel application of a multi-robot agent based on WSN and to evaluate a multi-hop communication caused by the robotics correspondingly, which are used in the uncertain and unknown subterranean tunnel. A Primary-Scout Multi-Robot System (PS-MRS) was proposed. A chain topology in a subterranean environment was implemented using a trimmed ZigBee2006 protocol stack to build the multi-hop communication network. The ZigBee IC-CC2530 modular circuit was adapted by mounting it on the PS-MRS. A physical experiment based on the strategy of PS-MRS was used in this paper to evaluate the efficiency of multi-hop communication and to realize the delivery of data packets in an unknown and uncertain underground laboratory environment.

Population connectivity: dam migration mitigations and contemporary site fidelity in arctic char.

BackgroundAnimal feeding and spawning migrations may be limited by physical barriers and behavioral interactions. Dam constructions (e.g. hydropower) commonly include gateways for fish migrations to sustain ecological connectivity. Relative genetic impacts of fish passage devices versus natural processes (e.g. hybrid inferiority) are, however, rarely studied. We examined genetic (i.e. microsatellite) population connectivity of highly migrating lake-dwelling Arctic char (Salvelinus alpinus), introduced 20 generations ago, across and within two subalpine lakes separated by a dam with a subterranean tunnel and spill gates after 7 generations. Due to water flow regime, the time window for fish migration is highly restricted.ResultsChar populations, with similar genetic structuring and diversity observed across and within lakes, were admixed across the dam with fishways during feeding. For spawning, however, statistically significant, but very low population differentiation (θ; 0.002 - 0.013) was found in nine out of ten reproductive site comparisons, reflecting interactions between extensive migration (mean first generation (F0) = 10.8%) and initial site fidelity. Simulations indicated that genetic drift among relatively small effective populations (mean Ne = 62) may have caused the observed contemporary differentiation. Novel Bayesian analyses indicated mean contributions of 71% F0 population hybrids in spawning populations, of which 76% had maternal or paternal native origin.ConclusionsEcological connectivity between lakes separated by a dam has been retained through construction of fishways for feeding migration. Considerable survival and homing to ancestral spawning sites in hybrid progeny was documented. Population differentiation despite preceding admixture is likely caused by contemporary reduced reproductive fitness of population hybrids. The study documents the beginning stages of population divergence among spatial aggregations with recent common ancestry.

Semi-Deterministic Propagation Model for Subterranean Galleries and Tunnels

A three-dimensional, semi-deterministic model for wave propagation in subterranean galleries and tunnels is introduced. The model uses a combination of deterministic ray-launching techniques and a stochastic approach to provide efficient predictions that avoid complex calculations of electromagnetic phenomena while preserving the ability to consider reflection, absorption and penetration, as well as diffuse scattering. There is no need to provide a precise definition of the walls in terms of their material electrical parameters and roughness. The wall properties are efficiently described using just three probabilistic parameters that can be calibrated by measurements. Experimental data for three various subterranean scenarios were used to validate the model's functionality. The scenarios were chosen with regard to validating the model function for different frequencies, cross-sections, lengths and shapes.

New discoveries with geophysics in the Accademia of Hadrian's Villa near Tivoli (Rome)

Abstract. The Accademia Pilot Project concerns one of the lesser known buildings of Hadrian's Villa, the Accademia, which is still in private property and is not open to the public. One of the most significant and unique features of this building – and of the whole Villa – is a network of subterranean service corridors, which was seldom studied. For the first time we used Geophysics at Hadrian's Villa, to explore the subterranean tunnels of the Accademia and reconstruct their layout. The survey was done by archaeologist Anna Maria Marras for her Master thesis in Geo-technology (Marras, 2008) and gave very interesting results.

Size matters: mole (Talpa europaea) hills and nest‐site selection of the antFormica exsecta

Moles are fossorial mammals that can act both as zoogeomorphic agents and species diversity drivers. These popular animals regularly push heaps of earth from their subterranean tunnel systems to the surface. Thereby they rearrange and improve the local microtopography for ant nesting. Here we use a strongly molehill (Talpa europaea) mediated nest system of the unicolonial wood ant Formica (Coptoformica) exsecta to test for ecological factors influencing nest-site selection at the microhabitat scale. Our results show that the size of molehills plays an important role in the multifactorial process of the ant’s nest-site choice with solar insolation as a paramount factor. The ants clearly favored larger and better sun-exposed molehills, suggesting that the coaction of a zoogeomorphic modified microrelief and solar insolation can drive the spatial colonization of F. exsecta.

Effects of Urban Development on Ant Communities: Implications for Ecosystem Services and Management

Research that connects the effects of urbanization on biodiversity and ecosystem services is lacking. Ants perform multifarious ecological functions that stabilize ecosystems and contribute to a number of ecosystem services. We studied responses of ant communities to urbanization in the Lake Tahoe basin by sampling sites along a gradient of urban land development. We sampled ant communities, measured vegetation characteristics, quantified human activities, and evaluated ant-community responses by grouping ants into service-providing units (SPUs), defined as a group of organisms and their populations that perform specific ecosystem services, to provide an understanding of urbanization impacts on biodiversity and their delivery of ecosystem services. Species richness and abundance peaked at intermediate levels of urban development, as did the richness of 3 types of ant SPUs (aerators, decomposers, and compilers). With increasing land development aerator and decomposer ants significantly declined in abundance, whereas compiler ants significantly increased in abundance. Competing models demonstrated that precipitation was frequently among the strongest influences on ant community structure; however, urban development and human activities also had a strong, negative influence on ants, appearing in most models with DeltaAIC(c) < 2 for species richness and abundance patterns of SPUs and generalists. Response diversity was observed within SPUs, which suggests that the corresponding ecosystem services were maintained until development reached 30-40%. Our data provide evidence that ecosystem functions, such as water infiltration and soil productivity, may be diminished at sites subject to greater levels of urbanization and that conserving ant communities and the ecosystem services they provide could be an important target in land-use planning and conservation efforts.

Estrutura populacional e biologia reprodutiva de Parastacus defossus (Crustacea: Decapoda: Parastacidae)

Este trabalho descreve a estrutura populacional e aspectos da biologia reprodutiva de Parastacus defossus Faxon, 1898, uma espécie com hábito fossorial que passa sua vida no interior de galerias subterrâneas. Aproximadamente 30 exemplares foram coletados mensalmente, de janeiro de 2003 a agosto de 2005 na região do Lami, Município de Porto Alegre, Rio Grande do Sul, Brasil. Registrou-se o comprimento mínimo, máximo e médio da carapaça de machos, fêmeas, juvenis e animais com ootestículo. Analisou-se a distribuição de freqüência por classes de tamanho, a proporção sexual, o recrutamento e o período reprodutivo. Foram amostrados um total de 766 exemplares, 315 machos (41,12%), 278 fêmeas (36,30%), 166 juvenis (21,67%) e sete animais com ootestículo (0,91%). Machos e fêmeas estiveram presentes durante todos os meses de amostragem e em todas as classes de tamanho, sendo que a maior freqüência de indivíduos foi registrada nas classes de tamanho ente 24 a 30 mm. A maior freqüência de juvenis foi observada na primavera/2003 e verão/2005. Diferenças significativas no tamanho de machos e fêmeas foram registradas apenas nas classes de tamanho entre 26-30 mm. A proporção sexual no período amostral foi de 1:0,88 (x² = 2,3; p &gt; 0,05) e entre as classes de tamanho foram constatadas diferenças significativas nas classes de tamanho 26-28 mm (x² = 5,43; p &lt; 0,05) e 28-30 mm (x² = 4,77; p &lt; 0,05) de comprimento de carapaça, nas quais os machos foram mais freqüentes. Das 278 fêmeas coletadas, apenas 17 estavam ovígeras (6,11%), sendo a estação reprodutiva bem definida na primavera.