A rainfall loading response recorded at 300 meters depth: implications for geological weighing lysimeters

Static pore water pressures in confined aquifers vary in response to ground surface loading changes, including precipitation and evaporation. Under certain hydrogeological conditions such aquifers can function as giant natural weighing lysimeters, referenced here as ‘geological weighing lysimeters’. The extent of the land area ‘weighed’ increases with aquifer depth and it is of interest to establish at what depth it is still possible to monitor surface water budgets. An 86 mm rainfall event produced a clear loading signal in a well in western Kansas at 300 m depth. The loading effect is quantitatively consistent with elastic deformation induced by the rainfall mass and suggests that geological weighing lysimeters could operate at considerably greater depths, thereby monitoring water budgets over a significant land area

Introduction, Passacaglia and Fugue by Healey Willan: A Transcription for Symphonic Band from the Organ

Thesis (M.M.)--Boston Universit

NASA systems autonomy demonstration project: Advanced automation demonstration of Space Station Freedom thermal control system

The NASA Systems Autonomy Demonstration Project (SADP) was initiated in response to Congressional interest in Space station automation technology demonstration. The SADP is a joint cooperative effort between Ames Research Center (ARC) and Johnson Space Center (JSC) to demonstrate advanced automation technology feasibility using the Space Station Freedom Thermal Control System (TCS) test bed. A model-based expert system and its operator interface were developed by knowledge engineers, AI researchers, and human factors researchers at ARC working with the domain experts and system integration engineers at JSC. Its target application is a prototype heat acquisition and transport subsystem of a space station TCS. The demonstration is scheduled to be conducted at JSC in August, 1989. The demonstration will consist of a detailed test of the ability of the Thermal Expert System to conduct real time normal operations (start-up, set point changes, shut-down) and to conduct fault detection, isolation, and recovery (FDIR) on the test article. The FDIR will be conducted by injecting ten component level failures that will manifest themselves as seven different system level faults. Here, the SADP goals, are described as well as the Thermal Control Expert System that has been developed for demonstration

Roadless space and logging in intact forest landscapes of the Congo Basin

Background: Forest degradation in tropical regions is often associated with roads built for selective logging. Forest areas that are not accessible by roads are considered valuable because they provide habitat that is not immediately impacted by major human activities. The protection of such Intact Forest Landscapes (IFL) is high on the biodiversity conservation agenda, leading to a motion of the Forest Stewardship Council (FSC) to better protect IFL in certified forest concessions. However, in many parts of Central Africa logging takes place at very low intensities and most roads are abandoned after few years of timber harvesting. Taking limited road persistence into account we asked: How did road networks in FSC certified concessions affect IFL? Methods: Intact forest landscapes can be conserved by retention of “roadless space”, a concept based on distance to the nearest road from any point. We used the Empty-Space Function, a general statistical tool from stochastic geometry, to calculate roadless space based on time series of LANDSAT images. We followed the spatial and temporal dynamics of logging roads in a part of the Congo Basin that has recently seen rapid expansion of road networks for selective logging. We compared the development of roadless space in certified and non-certified logging concessions inside and outside areas declared as being IFL in the year 2000. Results: The persistence of logging roads was limited over time, with only 12% of the overall network being permanently open. However, also taking only actively used roads into account, roadless space inside IFL has decreased rapidly due to expansion of logging into previously unlogged areas. Concessions that are now certified by FSC showed a slower rate of decrease before certification but after that their roadless space decreased to a level comparable to non-FSC concessions. The established concessions outside IFL showed a slight increase in roadless space due to forest recovery on abandoned roads. Conclusions: We recommend that forest management should make the preservation of large connected forest areas a top priority by effectively monitoring - and limiting – the occupation of space by roads that are accessible at the same time. Given the strong dynamics in road detectability, we challenge the static definition of intact forest landscapes based on a buffer around any road ever detected. Instead we suggest the empty space function as a viable alternative to calculate roadless space. (Texte intégral

A new tool to calculate roadless space in forest landscapes, applied in the Congo basin

New global strategies for road building require innovative tools to analyze linear patterns and their spatial distribution and to evaluate their environmental impacts. Roads not only present physical barriers to wildlife but also provide access for human and biological invasions. In tropical regions especially, forest degradation has been associated with roads built for selective logging into formerly intact forest landscapes. To quantify to what extent ecosystems are influenced by roads, it is important not only to know road length density but also their location in a landscape unit. The concept of roadless space is based on distance to the nearest road from any point. We present the computation of this distribution using the Empty-Space-Function, a general statistical mathematical tool based on stochastic geometry and random sets theory. We demonstrate the applicability of this well-defined probability function to calculate roadless space based on vector road data. In a Congo Basin case study we compared the temporal development of road networks inside different logging concessions over time. We hypothesized that roadless space decreases, even when the rate of wood volume harvest remains constant. Based on LANDSAT time series covering the last 29 years, we assessed accessible roads in relation with the river network and calculated the roadless space at different points in time. As expected, roadless space decreased continuously throughout most concessions, despite a drop in total annual harvest volume after 2008 and independent of forest certification schemes. We recommend that measures to reduce impacts of selective logging should not only be based on the extraction of timber, but should also include the total area impacted by roads. The Empty-Space-Function provides a rigorous mathematical description and a straightforward way to assess intact forest landscapes and is therefore highly applicable to road impact evaluation in conservation science

The effects of disease on optimal forest rotation : a generalisable analytical framework

This work is from the project titled Modelling economic impact and strategies to increase resilience against tree disease outbreaks. This is one of seven projects in the Tree Health and Plant Biosecurity Initiative (phase 2) funded by BBSRC, Defra, ESRC, Forestry Commission, NERC and Scottish Government.The arrival of novel pathogens and pests can have a devastating effect on the market values of forests. Calibrating management strategies/decisions to consider the effect of disease may help to reduce disease impacts on forests. Here, we use a novel generalisable, bioeconomic model framework, which combines an epidemiological compartmental model with a Faustmann optimal rotation length model, to explore the management decision of when to harvest a single rotation, even-aged, plantation forest under varying disease conditions. Sensitivity analysis of the rate of spread of infection and the effect of disease on the timber value reveals a key trade-off between waiting for the timber to grow and the infection spreading further. We show that the optimal rotation length, which maximises the net present value of the forest, is reduced when timber from infected trees has no value; but when the infection spreads quickly, and the value of timber from infected trees is non-zero, it can be optimal to wait until the disease-free optimal rotation length to harvest. Our original approach provides an exemplar framework showing how a bioeconomic model can be used to examine the effect of tree diseases on management strategies/decisions.Publisher PDFPeer reviewe

Impacts of logging roads on intact forest landscapes in the tropics

Road networks are growing globally, especially in tropical countries, allowing human access to remaining Intact Forest Landscapes (IFL) that are refuges for biodiversity and provide globally important ecosystem services. Selective logging is now widespread in tropical forests, acting as one of the main drivers of road network expansion, with logging roads often being considered door-openers and conduits for human impacts. The protection of road-free IFL is high on the biodiversity conservation agenda, a challenge for logging concessions certified by the Forest Stewardship Council (FSC). However, the impacts of logging roads can be highly variable depending on road use and management. In a logging-hot-spot of the Congo Basin, only 12% of all roads were permanently open, with all others becoming quickly revegetated and inaccessible. Taking limited road persistence into account, we analyzed how road networks in FSC certified concessions affected IFL. We followed the spatial and temporal dynamics of logging roads, comparing roadless space in certified and non-certified logging concessions inside and outside areas declared as IFL in the year 2000. We found that roadless space decreased rapidly in IFL, notwithstanding FSC certification, highlighting the urgent need for measures to safeguard ecological corridors between protected areas and remaining intact forests. Logging concession certification by FSC might play a key role in conserving forest connectivity by strategic road network planning. Forest management should make the preservation of large connected forest areas a top priority by effectively monitoring - and limiting - the occupation of space by roads that are accessible at the same time. Given the strong dynamics between the impacts of different types of roads, we challenge the static definition of IFL based on a buffer around any road ever detected. (Résumé d'auteur

Pronounced reproductive skew in a natural population of green swordtails, Xiphophorus helleri.

For many species in nature, a sire's progeny may be distributed among a few or many dams. This poses logistical challenges--typically much greater across males than across females--for assessing means and variances in mating success (number of mates) and reproductive success (number of progeny). Here we overcome these difficulties by exhaustively analyzing a population of green swordtail fish (Xiphophorus helleri) for genetic paternity (and maternity) using a suite of highly polymorphic microsatellite loci. Genetic analyses of 1476 progeny from 69 pregnant females and 158 candidate sires revealed pronounced skews in male reproductive success both within and among broods. These skews were statistically significant, greater than in females, and correlated in males but not in females with mating success. We also compare the standardized variances in swordtail reproductive success to the few such available estimates for other taxa, notably several mammal species with varied mating systems and degrees of sexual dimorphism. The comparison showed that the opportunity for selection on male X. helleri is among the highest yet reported in fishes, and it is intermediate compared to estimates available for mammals. This study is one of a few exhaustive genetic assessments of joint-sex parentage in a natural fish population, and results are relevant to the operation of sexual selection in this sexually dimorphic, high-fecundity species

The detection of cervical intraepithelial neoplasia by electrical impedance spectroscopy: The effects of acetic acid and tissue homogeneity

Objective. To evaluate the efficacy of an electrical impedance probe (Epitheliometer) in the diagnosis of high grade cervical intraepithelial neoplasia (CIN) in women referred with cervical smear abnormalities and to assess the effect of acetic acid (AA) and tissue boundaries on the measurements. Methods. A prospective observational study was undertaken in the colposcopy clinic. One hundred and sixty-five women, either with a clinical indication or abnormal cervical cytology, were recruited into the study. A pencil type probe was used to record impedance spectra from 12 points on the cervix before and after the application of 5% AA. Spectra were also recorded from tissue boundaries. Colposcopic examinations, including probe positioning, were video recorded to allow for correlations between histopathological diagnosis of colposcopically directed biopsies, colposcopic impression and the diagnosis based on impedance measurements. Results. Receiver operating characteristic (ROC) curves were derived. The areas under the curves (AUCs) to discriminate original squamous from high grade CIN were 0.80 (pre AA) and 0.79 (post AA). Comparison of these curves showed no significant difference, indicating that application of AA does not produce a large change in spectra. The probe Could distinguish tissue boundaries from homogeneous tissue points. Conclusion. The Epitheliometer has the potential to be used as an adjunct to colposcopy in the diagnosis of high grade CIN. It has the advantage of real time results, decreasing the need for diagnostic cervical biopsies, and facilitates a wider use of the 'see and treat' policy without the risk of overtreatment. (C) 2009 Elsevier Inc. All rights reserved