Anthropogenic land subsidence in the Perth Basin: Challenges for its retrospective geodetic detection

Recent-past subsidence of parts of the Perth Basin has most probably been caused by increased groundwater extraction for domestic and agricultural use. However, no dedicated geodetic monitoring programs were established when the increased extraction began in around 2000, thus setting a challenge to retrospectively quantify and map the subsidence. Differential levelling is likely to be less effective as only a few repeat traverses cover the areas thought to be subsiding. Repeat gravimetry is totally ineffective because of microseismic vibrations propagating through the Perth Basin. Repeat episodic GPS (Global Positioning System) is also likely to be less effective because of the few station occupations over several days or weeks and the inherent weakness of GPS for height determination. However, from a continuously operating GPS receiver at Gnangara and nearby artesian monitoring boreholes, we show that the rate of land subsidence has slowed from about -6 mm/yr to about -2 mm/yr since the reduction of groundwater extraction from the Yarragadee Aquifer in around 2005. A promising technique is InSAR (interferometric synthetic aperture radar) because it can map large areas, but the lack of historical radar imagery over the period of increased subsidence is a hindrance

Seismic risk of critical facilities in the Dominican Republic: case study of school buildings

Abstract The island of Hispaniola, shared by the Dominican Republic and Haiti, is located in a subduction zone between the North America plate and the Caribbean plate. In addition, there are 13 geological faults in the interior of the island, some of which have shown the potential to generate earthquakes of magnitude 7.5 and higher. Thus, the whole island is considered to be a high seismic risk region. In the past 100 years, several earthquakes have affected both parts of the island. In the case of the Dominican Republic, two earthquakes stand out: a magnitude 8.1 earthquake on August 4, 1946, north of the Samaná Province, which caused a tsunami, soil liquefaction, and the loss of about 100 lives, and a magnitude 6.5 earthquake on September 22, 2003, in the city of Puerto Plata, which caused significant damage for infrastructures. Among the observed effects, the partial and total collapse of several school buildings had a remarkable impact on local communities. In addition to the high seismic risk, a large part of the national infrastructure may exhibit high vulnerability to earthquakes because the seismic regulations had been the same for 32 years, namely from 1979 to 2011. During these three decades, thousands of structures were built nationwide, including essential facilities such as hospitals and schools. Considering that the current student population in public schools in the Dominican Republic is over 2 million, with the majority attending buildings that were designed with the 1979 seismic code and which proved to be highly vulnerable during the Puerto Plata earthquake, it is vital to take measures that reduce the risk and minimize potential earthquake damage to school buildings. In this context, the Technological Institute of Santo Domingo (INTEC) has undertaken recently a project with the main objective to assess the seismic vulnerability of 22 schools located in the San Cristóbal Province, in the south of the Dominican Republic. The latter schools were all built prior to the adoption of the current updated seismic code. This paper presents the results of the assessment of the Fernando Cabral Ortega School. Although only the results of a single RC building are presented, the response of such structure can be considered representative of a portfolio of existing schools in Dominican Republic

Turbulent flow through random vegetation on a rough bed

River vegetation radically modifies the flow field and turbulence characteristics. To analyze the vegetation effects on the flow, most scientific studies are based on laboratory tests or numerical simulations with vegetation stems on smooth beds. Nevertheless, in this manner, the effects of bed sediments are neglected. The aim of this paper is to experimentally investigate the effects of bed sediments in a vegetated channel and, in consideration of that, comparative experiments of velocity measures, performed with an Acoustic Doppler Velocimeter (ADV) profiler, were carried out in a laboratory flume with different uniform bed sediment sizes and the same pattern of randomly arranged emergent rigid vegetation. To better comprehend the time-averaged flow conditions, the time-averaged velocity was explored. Subsequently, the analysis was focused on the energetic characteristics of the flow field with the determination of the Turbulent Kinetic Energy (TKE) and its components, as well as of the energy spectra of the velocity components immediately downstream of a vegetation element. The results show that both the vegetation and bed roughness surface deeply affect the turbulence characteristics. Furthermore, it was revealed that the roughness influence becomes predominant as the grain size becomes larger

Optical response of a misaligned and suspended Fabry-Perot cavity

The response to a probe laser beam of a suspended, misaligned and detuned optical cavity is examined. A five degree of freedom model of the fluctuations of the longitudinal and transverse mirror coordinates is presented. Classical and quantum mechanical effects of radiation pressure are studied with the help of the optical stiffness coefficients and the signals provided by an FM sideband technique and a quadrant detector, for generic values of the product $\varpi \tau$ of the fluctuation frequency times the cavity round trip. A simplified version is presented for the case of small misalignments. Mechanical stability, mirror position entanglement and ponderomotive squeezing are accommodated in this model. Numerical plots refer to cavities under test at the so-called Pisa LF facility.Comment: 14 pages (4 figures) submitted to Phys. Rev.

The influence of building materials on the residual action of BHC

A atividade residual dos vapores do inseticida BHC de vários materiais de construção em câmaras com controle de umidade, no laboratório, foram significativamente diferentes entre si. Ninfas do primeiro estágio de Dipetalogaster maximus, criados em laboratório, foram expostas a vapores de BHC liberados da superfície tratada dos materiais de construção trazidos de Mambaí, Goiás.Residual insecticide activity of BHC vapors from various building materials in controlled humidity chambers in the laboratory were significantly different. Laboratory-reared, first instar nymphs of Dipetalogaster maximus were exposed to vapors of BHC which were being released from the treated surfaces of building materials taken from Mambaí, Goiás

Produção de seis híbridos de sorgo com capim-sudão avaliados em três cortes e em duas épocas de semeadura.

Foram avaliados quatro híbridos experimentais e duas cultivares comerciais de Sorghum bicolor cv bicolor X Sorghum bicolor cv sudanense quanto à produção de matéria verde (MV), matéria seca (MS) e matéria seca digestível (MSD), altura das plantas e população por hectare. Os híbridos foram semeados em duas épocas e submetidos a três cortes sucessivos. Foi empregado o delineamento experimental de blocos ao acaso, com parcelas subdivididas, e a comparação de médias foi efetuada pelo teste de SNK, a 5% de probabilidade. O híbrido ATF 53 x CMSXS 912 apresentou valores médios de produção de MV, MS e MSD superiores aos demais, nas duas épocas de semeadura, sem diferir da testemunha AG2501-C. Os valores médios da 2ª época foram superiores aos da 1ª época quanto às produções de MV, MS e altura das plantas

Assessment of spatio-temporal variability of faecal pollution along coastal waters during and after rainfall events.

More than 80% of wastewaters are discharged into rivers or seas, with a negative impact on water quality along the coast due to the presence of potential pathogens of faecal origin. Escherichia coli and enterococci are important indicators to assess, monitor, and predict microbial water quality in natural ecosystems. During rainfall events, the amount of wastewater delivered to rivers and coastal systems is increased dramatically. This study implements measures capable of monitoring the pathways of wastewater discharge to rivers and the transport of faecal bacteria to the coastal area during and following extreme rainfall events. Spatio-temporal variability of faecal microorganisms and their relationship with environmental variables and sewage outflow in an area located in the western Adriatic coast (Fano, Italy) was monitored. The daily monitoring during the rainy events was carried out for two summer seasons, for a total of five sampling periods. These results highlight that faecal microbial contaminations were related to rainy events with a high flow of wastewater, with recovery times for the microbiological indicators varying between 24 and 72 h and influenced by a dynamic dispersion. The positive correlation between ammonium and faecal bacteria at the Arzilla River and the consequences in seawater can provide a theoretical basis for controlling ammonium levels in rivers as a proxy to monitor the potential risk of bathing waters pathogen pollution

Parallaxes of southern extremely cool objects III : 118 L and T dwarfs

We present new results from the Parallaxes of Southern Extremely Cool dwarfs program to measure parallaxes, proper motions and multiepoch photometry of L and early T dwarfs. The observations were made on 108 nights over the course of 8 yr using the Wide Field Imager on the ESO 2.2m telescope. We present 118 new parallaxes of L and T dwarfs of which 52 have no published values and 24 of the 66 published values are preliminary estimates from this program. The parallax precision varies from 1.0 to 15.5mas with a median of 3.8mas. We find evidence for two objects with long term photometric variation and 24 new moving group candidates. We cross-match our sample to published photometric catalogues and find standard magnitudes in up to 16 pass-bands from which we build spectral energy distributions and H-R diagrams. This allows us to confirm the theoretically anticipated minimum in radius between stars and brown dwarfs across the hydrogen burning minimum mass. We find the minimum occurs between L2 and L6 and verify the predicted steep dependence of radius in the hydrogen burning regime and the gentle rise into the degenerate brown dwarf regime. We find a relatively young age of ~2 Gyr from the kinematics of our sample.Peer reviewedFinal Accepted Versio