Combining Robustness with Efficiency in?the?Estimation of the Variogram

In the present paper, we propose a new method for the estimation of the variogram, which combines robustness with efficiency under intrinsic stationary geostatistical processes. The method starts by using a robust estimator to obtain discrete estimates of the variogram and control atypical observations that may exist. When the number of points used in the fit of a model is the same as the number of parameters, ordinary least squares and generalized least squares are asymptotically equivalent. Therefore, the next step is to fit the variogram by ordinary least squares, using just a few discrete estimates. The procedure is then repeated several times with different subsets of points and this produces a sequence of variogram estimates. The final estimate is the median of the multiple estimates of the variogram parameters. The suggested estimator will be called multiple variograms estimator. This procedure assures a global robust estimator, which is more efficient than other robust proposals. Under the assumed dependence structure, we prove that the multiple variograms estimator is consistent and asymptotically normally distributed. A simulation study confirms that the new method has several advantages when compared with other current methods.     

Revisiting Multi-Gaussian Kriging with the Nataf Transformation or the Bayes’ Rule for the Estimation of Spatial Distributions

A multivariate probability transformation between random variables, known as the Nataf transformation, is shown to be the appropriate transformation for multi-Gaussian kriging. It assumes a diagonal Jacobian matrix for the transformation of the random variables between the original space and the Gaussian space. This allows writing the probability transformation between the local conditional probability density function in the original space and the local conditional Gaussian probability density function in the Gaussian space as a ratio equal to the ratio of their respective marginal distributions. Under stationarity, the marginal distribution in the original space is modeled from the data histogram. The stationary marginal standard Gaussian distribution is obtained from the normal scores of the data and the local conditional Gaussian distribution is modeled from the kriging mean and kriging variance of the normal scores of the data. The equality of ratios of distributions has the same form as the Bayes’ rule and the assumption of stationarity of the data histogram can be re-interpreted as the gathering of the prior distribution. Multi-Gaussian kriging can be re-interpreted as an updating of the data histogram by a Gaussian likelihood. The Bayes’ rule allows for an even more general interpretation of spatial estimation in terms of equality for the ratio of the conditional distribution over the marginal distribution in the original data uncertainty space with the same ratio for a model of uncertainty with a distribution that can be modeled using the mean and variance from direct kriging of the original data values. It is based on the principle of conservation of probability ratio and no transformation is required. The local conditional distribution has a variance that is data dependent. When used in sequential simulation mode, it reproduces histogram and variogram of the data, thus providing a new approach for direct simulation in the original value space.     

What is the ‘Just Transition’?

The ‘just transition’ is a concept receiving more attention in the literature to-date. This critical review discusses this and how there are overlaps with literature on energy, environmental and climate justice. Within the separate energy, environment and climate change scholar communities, there is too much distortion of what the ‘transition’ means and what ‘justice’ means, and they all should be understood within the just transition concept. To increase public understanding and public acceptance of a just transition, these research communities need to unite rather than continue alone.     

Secondary aspects of the harnessing of the Rh?ne (not considering the question of energy)

Since a 1921 law the harnessing of the Rhône River from Lyon to the Mediterranean has been directed by a national company composed of the public sector (fromthe valley) as well as of various consumers or distributors of current such as the SNCF or the EDF. This company, the National Company of the Rhône (CNR), was a precursor to the establishment of the TVA in the United States, although it did not begin operations until aftetr the TVA due to prolonged technical negotiations and to the difficulties involved in locating financial support in a period of economic crisis. Even though the utilization of hydraulic power constitutes the prime aim of the CNR, it has also focused on navigation, irration and other agricultural uses from the outset.This article will not further discuss the hydro-electric stations on the Rhône which usually supply more than 22% of French hydro-electric output from thirteen stations now in operation (total power is 2,350 MW and annual average output is 13,000 GWh). This paper will treat the question of the nature and importance of the side effects of the harnessing of the Rhône apart from its essential energy function.     

Geodiversity,palaeodiversity or biodiversity: where is the place of palaeobiology and an understanding of taphonomy?

While some authors view biodiversity as an integral part of an over-arching geodiversity, most would see them as separate constructs. If that is the case, then the life–death interface marks the critical boundary between those that study organisms in life and the palaeontologists who try to interpret fossils in terms of their palaeobiology. The interface between life and the fossil record is characterised by the processes of taphonomy and, when fossils are collected, care must be taken to ensure that vital taphonomic information is not lost. This does not appear to be highlighted in the various fossil collecting codes and the avoidance of the loss of taphonomic information during collection should be a key feature of collecting policies and geoconservation in general.     

How Alpine or Himalayan are the Central Andes?

 Although non-collisional mountain belts, such as the Andes, and collisional mountain belts, such as the Alps and the Himalayas–Tibet, have been regarded as fundamentally different, the Central Andes share several features with the Himalayas–Tibet. The most important of these are extremely thickened (≥70 km) continental crustal roots supporting high plateaus and mountain fronts characterized by large basement thrusts. The main prerequisite for very thick crustal roots and extreme mountainous topography appears to be large-scale underthrusting of continental crust of normal thickness, irrespective of whether the crustal thrusts are antithetic with respect to subduction as in the Andes, or synthetic with respect to preceding subduction of oceanic lithosphere as in the Himalayas. In both cases sole thrusts near the base of the continental crust nucleated in thermally anomalous zones of the hinterland and then propagated across ramps into shallower detachments located within thick sedimentary or metasedimentary cover rocks. In contrast to the Central Andes and the Himalayas, the Alps are characterized by intracrustal detachment which allowed both the subduction of lower crust and a stacking of relatively thin upper crustal slivers, which make up a narrow mountain chain with a more subdued topography. Received: 10 August 1998 / Accepted: 1 March 1999     

What is responsible for development of the Asian–Pacific transition zone: The geodynamics of oceanic plates or the Asian continent?

The main unusual feature of tectogenesis of the Asian–Pacific transition zone in the Mesozoic–Cenozoic consists in the formation of left-lateral strike-slip faults, which form the East Asian global shear zone with paragenesis of its constituent variously oriented fault systems. Paragenetic analysis has revealed that continental blocks of the Asian–Pacific transition zone were displaced along systems of transit left-lateral strike-slip faults of the East Asian global shear zone by hundreds of kilometers in the southerly to southwesterly direction due to tectonic activity of the Asian continent, which drifted southwestward. This process was accompanied by the formation of compression and extension structures. Otherwise, it is difficult to explain the structuring of the overhanging margin of the continent by subduction of oceanic lithospheric plates in the northerly to northwesterly direction opposite relative to the displacement of the continental crust as is usually thought.     

What is the deepest part of the Vostok ice core telling us?

This review paper is mainly concerned with a geochemical investigation of the deepest part of the Vostok ice core between 3310 m, the depth at which the palaeoenvironmental record present in the ice above is lost, and the bottom of the core about 130 m above subglacial Lake Vostok. Two sections constitute this part of the core.The upper section (3310–3539 m depth) still consists of ice of meteoric origin but subjected to widespread complex deformation. This deformation is analysed in light of a δD–deuterium excess diagram and information on microparticles, crystal sizes and chemical elements distributions in that part of the core. Such ice deformation occurred when the ice was still grounded upstream from Vostok station in a region with subfreezing temperatures.The lower section from 3539 m to the bottom of the core at 3623 m depth is lake ice formed by freezing of subglacial Lake Vostok waters. This is indicated by the isotopic properties (δD, δ¹⁸O and deuterium excess), by electrical conductivity measurements (ECM), crystallography and gas content of the ice. These ice core data together with data on ionic chemistry favour an origin of the lake ice by frazil ice generation in a supercooled (below pressure melting point) water plume existing in the lake followed by accretion and consolidation by subsequent freezing of the host water.The helium profile of this deepest part of the Vostok core is quite unusual and surprising. It has important implications for the interactions between the ice sheet and the lake. Two constrasting scenarios can be satisfactorily constructed so that the lake residence time is not well constrained.     

Is Lognormal Kriging Suitable for Local Estimation?

Lognormal kriging was developed early in geostatistics to take account of the often seen skewed distribution of the experimental mining data. Intuitively, taking the distribution of the data into account should lead to a better local estimate than that which would have been obtained when it is ignored. In practice however, the results obtained are sometimes disappointing. This paper tries to explain why this is so from the behavior of the lognormal kriging estimator. The estimator is shown to respect certain unbiasedness properties when considering the whole working field using the regression curve and its confidence interval for both simple or ordinary kriging. When examined locally, however, the estimator presents a behavior that is neither expected nor intuitive. These results lead to the question: is the theoretically correct lognormal kriging estimator suited to the practical problem of local estimation?     

Variogram or Semivariogram? Variance or Semivariance? Allan Variance or Introducing a New Term?

There is a confusing situation in geostatistical literature: Some authors write variogram, and some authors write semivariogram. Based on a formula for the empirical variance that relates to pairwise differences, it is shown that the values depicted in a variogram are entire variances of observations at a given spatial separation (lag). Therefore, they should not be called semivariances, and the term semivariogram should also be avoided. To name a variogram value, we suggest the use of the term gammavariance instead of the misleading semivariance.     

On and Off the North China Craton: Where is the Archaean Keel?

Geophysical data indicate that the lithosphere beneath the NorthChina Craton (NCC) is     

Indicators of the Anthropocene: is there a case for conservation?

The Earth's atmosphere, biosphere and lithosphere are increasingly being modified by human activity. Given this anthropogenic influence on the natural environment, the case for recognizing an Anthropocene Epoch has recently been made and there is ongoing debate as to whether, and how, to formally characterize and define such an epoch. As a contribution to this debate, this article explores whether or not the landscapes, deposits, landforms and key marker horizons that may be used to characterize and define an Anthropocene Epoch could, and should, be identified and conserved in the same manner as other parts of the geological succession. Anthropogenic features pose a conservation challenge, however, as they often cross cut existing conservation frameworks which tend to focus on the natural, historic or cultural environment. Developing a coherent approach to the conservation of the indicators of an Anthropocene Epoch would, therefore, require an integrated system of describing, auditing and designating features for conservation. A major benefit of such an approach would be the opportunities for interdisciplinary collaboration between the wide range of researchers interested or involved in studying and conserving the record of anthropogenic activity.     

The monsoon system: Land–sea breeze or the ITCZ?

For well over 300 years, the monsoon has been considered to be a gigantic land–sea breeze driven by the land–ocean contrast in surface temperature. In this paper, this hypothesis and its implications for the variability of the monsoon are discussed and it is shown that the observations of monsoon variability do not support this popular theory of the monsoon. An alternative hypothesis (whose origins can be traced to Blanford’s (1886) remarkably perceptive analysis) in which the basic system responsible for the Indian summer monsoon is considered to be the Intertropical Convergence Zone (ITCZ) or the equatorial trough, is then examined and shown to be consistent with the observations. The implications of considering the monsoon as a manifestation of the seasonal migration of the ITCZ for the variability of the Indian summer monsoon and for identification of the monsoonal regions of the world are briefly discussed.     

Gold in Egypt: Does the future get worse or better?

Within the Eastern Desert of Egypt, there are more than a hundred vein-type gold deposits and occurrences. Gold was mined in the Dynastic and Roman periods of the Egyptian history and most of the attention was focused entirely on the near-surface high grade parts of these veins. Currently, besides the more problematic sulfide-rich quartz veins, which generally occur in the lower levels of the worked out auriferous quartz veins, some targets including wall-rock alteration, listwaenite, dumps and tailings of ancient mines, by-product gold hosted in volcanogenic massive sulfide deposits and gold-bearing Algoma-type BIF, as well as alluvial gold constitute the new targets for gold in the Eastern Desert of Egypt. In most of these targets, gold displays a bimodal distribution; occurring both as free-milling gold and in the form of sub-microscopic or “invisible” gold in refractory sulfides and sulfoarsenides such as pyrite, chalcopyrite, arsenopyrite, gersdorffite and pentlandite minerals.Characterizing gold in an ore is important in extraction metallurgy. Free-milling gold can be efficiently recovered by crushing, grinding and cyanidation without additional processing. In refractory ores, on the other hand, conventional milling can liberate the sulfides from the gangue allowing a low content of concentrate to be produced by a process such as flotation. However, direct leaching of the concentrate results in poor gold extractions as the cyanide lixiviant is unable to contact the gold locked within the refractory host. Oxidative pretreatment is required for such ores and the methods available for oxidation are roasting (calcination), pressure oxidation, and bacterial oxidation; all oxidize the refractory minerals in the ore to render the gold amenable to cyanidation. While such oxidative methods are capable of achieving reasonable recoveries, they increase the capital and operating costs. An alternative, applicable to the liberation of gold from the refractory host, is to continue the grinding process to reduce the particle size of the host mineral thereby exposing a part of the gold surface for contact with the cyanide solution. A benefit of this technique is that the environmental aspects of the oxidation reaction products are avoided, however the ultra fine grinding also adds more operating costs.Metallurgical studies carried out on some gold deposits, dumps and tailings of ancient gold mines in Egypt, proved that these ores are amenable to percolation leaching (concentration of KCN varies between 0.5 and 1 g/L) for the (− 10 mm) grain size, and consequently heap leaching is a successful technique as the results of these laboratory scale column tests show. In most of these studies, a marked improvement in the percent of gold recovery was gained when the crushed ore is agglomerated by the addition of water, lime and/or cement particularly in ores containing significant quantities of clay minerals and clay-forming minerals (e.g. sericite and muscovite), and by addition of kerosene which passivates the adsorption surfaces on the graphite.Placer gold is recovered by gravity methods utilizing the large difference in specific gravity between gold and commonly associated minerals such as quartz and feldspar. The equipments range from a simple pan to more complex devices used in gold recovery plants and dredges.Modern studies in Egypt point to the presence of different targets of gold; diverse in their gold content, mode of occurrence of gold and the metallurgical treatments required for extracting gold. With the advance of modern techniques such as Electron Microprobe Analyses (EMPA), laser Ablation Microprobe Inductively Coupled Plasma Mass Spectroscopy (LAM-ICP-MS), gold ores in Egypt should be re-characterized precisely to know the specifications of these ores and consequently predict the metallurgical regime required, and with the high world gold price, it has become necessary to take into consideration the presence of refractory gold ores as one of these targets in Egypt. Generally speaking, laboratory experiments conducted on gold processing in Egypt are encouraging to some extent; however the gold extraction rates of the free milling ores with conventional cyanidation and refractory ores with direct and pretreatment techniques can be improved by modifying the conditions of extraction to be consistent with the results obtained from the re-characterization stage. Otherwise any target for gold and whatsoever the mode of occurrence of gold in this target (i.e. free-milling and/or refractory) could be recovered directly by heap leaching technique and we should accept less than ideal gold recovery for any target when weighed against the capital expenditure required for processes such as roasting, and the continuous grinding processes which might improve recoveries by only a small percentage.     

How resilient is the labour market against natural disaster? Evaluating the effects from the 2010 earthquake in Chile

Natural disasters are one of the main channels through which ecological and socio-economic systems interact. In particular, the severe impacts of earthquakes could disrupt activities in the labour market. However, the literature barely researched the long-term effects of such events. To investigate this issue, this article is concentrated in Chile that is subject to recurring seismic movements. The 27 February 2010 Bío-Bío Chile earthquake (M_w 8.8) was the second strongest in the history of the country. This natural disaster can be used to evaluate the response of the labour market to an exogenous shock. Besides, the capacity for resilience in the labour market is crucial for people who rely on their job. This document analyses the impacts of the 2010 Bío-Bío earthquake and tsunami on Chilean labour market outcomes, in particular, the quality of employment. With this objective, different data are combined for analysing the effect in the short and long term. Also, distinct econometric techniques and exogenous measurements of seismic acceleration are used. The evidence shows that these catastrophes harmed the labour market in the short term. However, in the long term, the government’s reconstruction efforts and other factors could have attenuated the adverse effects over some variables in the most affected zones.

     

The smoke is rising but where is the fire? Exploring effective online map design for wildfire warnings

The current study sought to offer guidance for developing effective web-based mapping tools for wildfire warnings by identifying (1) the important content for facilitating individuals’ decision-making, and (2) the optimal interface design for ensuring usability and ease of information access. A map-based warning tool was prototyped in the Australian context, followed by a usability and effectiveness evaluation through individual interviews and verbal protocol analysis to assess participants’ interaction with the mapping interface and information in response to the simulated warning scenario. The results demonstrated variations in participants’ approaches to wildfire warning response, revealing varied information needs. Specifically, most participants relied on their own assessment of the prospective threat, requiring specific wildfire-related information before eliciting a response. In contrast, the decision of a minority of the participants was motivated by response guidance from agencies, and accurate wildfire information was less important for their response. Imperative information for both types of residents therefore needs to be highlighted in a map-based warning tool to cater to a wide audience. Furthermore, a number of heuristics were identified for designing effective interactive functions to facilitate the control of, and access to, the various maps and textual information presented on the map-based warning interface.