Two-site CCD observations and spectroscopy of HD 207331: A new δ Scuti variable in Cygnus

The results of an observational campaign on the new δ Scuti pulsator HD 207331 are reported. The star was observed photometrically from August 26 to September 2, 2009 from the Observatorio San Pedro Mártir (0.84-m telescope, Mexico) and the Observatorio del Teide (0.80-m telescope, Spain). An overall run of 53.8 h of useful data was collected from the two sites. Four oscillation frequencies for HD 207331 have been found above a 99% confidence level. These results confirm the multiperiodic pulsation nature of the star suggested in previous observations with sparse data. Spectroscopic observations carried out in 2009 allowed us to derive its spectral type and luminosity class as well as to estimate its rotation rate. A simple comparison with models is performed.     

Using helicopter electromagnetic data to predict groundwater quality in fractured crystalline bedrock in a semi-arid region, Northeast Brazil

Geostatistical modeling, using airborne and borehole electromagnetic data, was used to estimate electrical conductivity in groundwater within fractured paragneisses and migmatites in a semi-arid climate in northeastern Brazil. Despite the geologic heterogeneity of crystalline aquifers, the use of high resolution helicopter electromagnetic (HEM) data enabled the characterization of groundwater electrical conductivity where data from drilled wells were insufficient. The tacit assumption is that HEM measurements can be used to relate rock electrical conductivity to groundwater electrical conductivity. In this study, the HEM data were used as an external drift variable in non-stationary estimation and stochastic simulation to identify the variability of groundwater electrical conductivity. Validation tests, comparing predicted values for groundwater conductivity with measurements in new wells, confirmed the success of these models in locating fresh groundwater sources in crystalline bedrock.     

State of knowledge of coastal aquifer management in South America

A comparative analysis of the existing hydrogeological and management information from 15 coastal aquifers in South America was performed in order to obtain insight into common features of the sub-continent coastal zones. Some knowledge from other areas has been incorporated. There is a very variable degree of knowledge and management practice, ranging from almost no data and no action (the most common case), to sound conceptual models about aquifer behaviour and comprehensive management actions such as relocation of abstractions, pumping brackish groundwater, and aquifer vulnerability mapping. Some common features are: intensive groundwater exploitation; lack of characterization studies to support resource planning and management; lack of monitoring networks; and the need for raising awareness within society and its involvement in resource planning and management action programmes. Quality and quantity problems arising in heavily populated areas associated with coastal aquifers in South America point to unsustainable groundwater development. The sustainable use of those aquifers must rely on adequate evaluation of aquifer characteristics and monitoring.     

Measuring the speed of gravity at short distances: Sensitivity estimate

An experimental set up was proposed to determine the speed of gravitational signals traveling in air or in some other medium. It involves two vibrating masses—the emitters, which will be the sources of periodic tidal gravitational signals—and one sapphire-made mass that will act as a detector, positioned between the two emitters. The detector is planned to be suspended in vacuum and cooled down to 4.2 K, and its vibrational amplitude should be measured by a microwave signal (with ultra-low phase-noise) that is expected to resonate with the whispering gallery modes inside the detector. The mechanical and electrical quality factors of sapphire are quite high, yielding a very narrow detection band that reduces the detector sensitivity while amplifying the phase difference of the emitters' signals. The frequencies of the normal modes of the detector were previously determined using a finite element program. In this work, these frequencies are applied to the calculation of a first estimate of the sensitivity of the experiment.     

40Ar–39Ar geochronology across Archean and Paleoproterozoic terranes from southeastern Guiana Shield (north of Amazonian Craton,Brazil): Evidence for contrasting cooling histories

A ⁴⁰Ar/³⁹Ar geochronological study was performed on amphibole and biotite from some representative units of distinct tectonic domains of the southeastern Guiana Shield, north of the Amazonian Craton, the Amapá Block and the Carecuru Domain. In the Amapá Block, an Archean continental block involved in the Transamazonian orogenesis (2.26–1.95 Ga), the investigated minerals, from rocks of the Archean high-grade basement assemblage, give only Paleoproterozoic ages, indicating their complete resetting during the Transamazonian orogenic event. Amphibole ages vary from 2087 ± 3 to 2047 ± 20 Ma, and biotite ages spread mainly between 2079 ± 18 and 2033 ± 13 Ma. In the Carecuru Domain, in which the geodynamic evolution is related to Paleoproterozoic magmatic arc setting during the Transamazonian event, calc-alkaline granitoids yield amphibole age of 2074 ± 17 Ma, and biotite ages of 1928 ± 19 Ma and 1833 ± 13 Ma.These data reinforce the importance of the Transamazonian orogenic cycle in the investigated area, and indicate that the rocks were not significantly affected by post-Transamazonian events. When coupled with available U–Th–Pb monazite and Pb–Pb zircon geochronological records and petro-structural observations, the new ⁴⁰Ar/³⁹Ar data delineate contrasting cooling and exhumation histories for the tectonic domains. In the Amapá Block, the data suggest nearly vertical T–t paths that reflect fast cooling rates, which indicate tectonically controlled exhumation, related to collisional stages of the Transamazonian event, between 2.10 and 2.08 Ga. Conversely, in the Carecuru Domain, low cooling rates suggest that the arc-related granitoids underwent slow and monotonous cooling since their emplacement until reaching the biotite isotopic closure temperature.     

Stochastic micromechanical model of the deterioration of asphalt mixtures subject to moisture diffusion processes

The deleterious effect of moisture in the microstructure of asphalt mixtures, usually referred to as moisture damage, has been recognized as a main cause of early deterioration of asphalt pavements. The initiation and evolution of moisture‐related deterioration is strongly influenced by the internal air void structure of asphalt mixtures. Despite its importance, the majority of works conducted on the micromechanical modeling of asphalt mixtures overlook the role of the air void structure, mainly because of its high complexity and variability. This paper explores the influence of air void variability on the performance of asphalt mixtures subjected to moisture diffusion processes. A stochastic modeling technique based on random field theory was used to generate internal distributions of physical and mechanical properties of the asphalt matrix of the mixture that depend on probable air voids distributions. The analysis was conducted by means of a coupled numerical micromechanical model of moisture damage. The results showed that the variability and distribution of air voids are decisive in determining the moisture‐dependent performance of asphalt mixtures. Furthermore, it was also shown that a stochastic characterization of the diverse air void configurations is a feasible and useful approach to better represent and understand mechanically related deterioration processes in asphalt mixtures. Copyright © 2010 John Wiley & Sons, Ltd.     

Efforts to reduce sea turtle bycatch in the shrimp fishery in Northeastern Brazil through a co-management process

The neritic waters of the state of Sergipe in Northeastern Brazil is adjacent to the main nesting area of the olive ridley sea turtles (Lepidochelys olivacea) in the Western Atlantic Ocean and an important area for shrimp trawl fishery. To address the problem of incidental mortality of sea turtles captured during trawling and reduce the risk of overexploitation of shrimp stocks, Projeto TAMAR/ICMBio, a Brazilian sea turtle conservation program, has adopted two main strategies: (1) the implementation of a marine monitoring program and (2) active participation in local forums. This paper describes the conflicts among stakeholders, the arrangements and established mechanisms of negotiation aimed to protect sea turtles and shrimp grounds, and strategies to reduce conflicts between user groups. The analysis of this co-management process highlights the importance of stakeholder participation in resource management decision-making through a cooperative process, the role assumed by non-governmental organizations as mediators, and the factors that influence this system. The key factors and actions learnt from the current study include clear identification of the conflicts, identification of stakeholders – both local and external, and local leaders, encouragement of actors and leaders to participate, support and strengthening of local groups, legitimization of the discussion forums through involvement with government, formalization of decisions taken through legislation, and monitoring of the management efficacy.     

松辽盆地周围沸石矿成矿构造动力学环境

松辽盆地周围沸石资源丰富 ,矿床类型多样 ,是中国东部环太平洋沸石成矿带的重要组成部分。研究区NE—NNE向深大断裂带控制着中生代火山岩和沸石矿带的空间展布 ,而不同方向深大断裂带的交接复合地段则决定了沸石矿田和主要矿床的空间定位。燕山中晚期以挤压-剪切 (左行 )为主的构造动力学机制控制了富碱高钾火山岩的发育 ,为沸石矿源岩的形成期 ;喜山期的构造反转以拉张 -剪切 (右行 )为主的构造动力学机制及其相伴的岩浆热事件 ,导致区域地热异常、地下流体增温和沸石矿化作用的快速进行。研究区中生代火山岩系中沸石矿床的主成矿期为喜山期 (6 4 5～ 5 5 0Ma)。     

Trials for the construction of a cement solidified retaining structure in a domestic landfill site using deep soil mixing

This paper describes the trials undertaken within a domestic landfill site to assess the feasibility of constructing a cement solidified retaining structure using deep soil mixing. The trials consisted of individual columns extending to the full depth of the landfill, each using different concrete mixes and mixing auger configurations to assess the most successful combinations to achieve full depth, followed by the construction of two trial blocks incorporating several different concrete mixes. The trial blocks were constructed to evaluate the most effective concrete and auger combinations required to construct the retaining structure which if built would be approximately 150 m in length, 15 m deep and 10 m wide.

Grout cube strength has been measured during column installation and post construction the columns were exhumed and core samples taken for laboratory analysis of compressive strength, permeability, freeze/thaw and long-term immersion tests.

The trials have met with only moderate success and indicate that a combination of depth and a difficult substrate as is likely to be encountered in older landfills will severely hinder the process of column installation. No amount of previous characterisation can determine the conditions likely to be encountered at a particular location in such a heterogeneous material.

It is suggested that the calculation of likely success rate for column installation and construction of a large retaining structure can be based on the failure rate of cable percussion boreholes during site investigation. If the failure is greater than 15% the technique is unlikely to be viable.