Estimation of Anisotropic,Time-Varying Spatial Spillovers of Fine Particulate Matter Due to Wind Direction

This paper investigates the effect of daily wind direction and speed on the spatio-temporal distribution of particulate matter, . Interdependencies between the values of different monitoring sites are characterized by incorporating time-varying anisotropic spatial weighting matrices. These weights are parameterized with respect to wind direction, speed and a range that marks the bandwidth of admissible deviations between wind direction and bearing. The empirical analysis is based on daily values recorded by monitoring sites located across the eastern United States in 2015 as well as several meteorological regressors. More precisely, we propose a space-time dynamic panel data model with different spatial autoregressive, temporal and exogenous dependencies. All model parameters are estimated by the quasi-maximum likelihood approach. The estimation procedure, including the identification of the range and spatial parameters, is verified by Monte Carlo simulations. We show that part of the spatial dependency of values is explained by wind direction.     

On the Performance of the Subtour Elimination Constraints Approach for the p‐Regions Problem: A Computational Study

The p‐regions is a mixed integer programming (MIP) model for the exhaustive clustering of a set of n geographic areas into p spatially contiguous regions while minimizing measures of intraregional heterogeneity. This is an NP‐hard problem that requires a constant research of strategies to increase the size of instances that can be solved using exact optimization techniques. In this article, we explore the benefits of an iterative process that begins by solving the relaxed version of the p‐regions that removes the constraints that guarantee the spatial contiguity of the regions. Then, additional constraints are incorporated iteratively to solve spatial discontinuities in the regions. In particular we explore the relationship between the level of spatial autocorrelation of the aggregation variable and the benefits obtained from this iterative process. The results show that high levels of spatial autocorrelation reduce computational times because the spatial patterns tend to create spatially contiguous regions. However, we found that the greatest benefits are obtained in two situations: (1) when ; and (2) when the parameter p is close to the number of clusters in the spatial pattern of the aggregation variable.     

Boron isotope geochemistry of Na‐bicarbonate,Na‐chloride,and Ca‐chloride waters from the Northern Apennine Foredeep basin: other pieces of the sedimentary basin puzzle

The boron stable isotope ratio δ¹¹B of 12 water samples representative of three chemical facies (fresh Na‐bicarbonate, brackish Na‐chloride, saline, and brine Ca‐chloride) has been analyzed. Interpretation of the δ¹¹B data, along with the chemical compositions, reveals that Na‐carbonate waters from the Northern Apennine are of meteoric origin, with boron contributions from clay desorption and mixing with seawater‐derived fluids of Na‐chloride or Ca‐chloride compositions. The comparison of our new results with the literature data on other sedimentary basins of Mediterranean, and worldwide, confirms the contribution of Na‐bicarbonate waters to the genesis of mud volcano fluids. The Na‐chloride sample of Salvarola (SAL), which may represent the end‐member of the mud volcanoes, and the Ca‐chloride brine water from Salsomaggiore (SM) indicate boron release from clays compatible with the diagenetic process. The empirical equation: relating boron concentration and the stable isotope composition of the fluids observed in this study and the literature is proposed to trace the effect of diagenesis in sedimentary basins. A geothermometer associated to the diagenetic equation is also proposed: The application of this equation to obtain reservoir temperatures from δ¹¹B compositions of waters should be carefully evaluated against the results obtained from other chemical and isotopic geothermometers from other basins around the world.     

Isotopic Evidence for Diet Among Historic Bedouin of Khirbat al‐Mudayna,Jordan

Interpreting the behaviours of nomadic groups from the archaeological record is particularly challenging owing to the ephemeral remains produced by their lifestyle. As such, human burials – even from isolated contexts – provide a wealth of information about these transient groups. Stable carbon and nitrogen isotope analysis of a series of human skeletal remains (n = 22) from isolated burials were utilized to reconstruct the diet of historic (ca. 13^th–19^th century CE) Bedouin from the Khirbat al‐Mudayna vicinity in modern‐day Jordan. Carbon isotope values ranging from −17.7 to −12.5‰ point to variable dietary contributions from both C₃‐ and C₄‐based foods, while corresponding faunal δ¹³C ratios ( = −19.0 ± 1.7‰, 1σ) exhibit depletion in ¹³C characteristic of a predominantly C₃ diet. While mean human δ¹⁵N values ( = 12.7 ± 1.9‰, 1σ) may suggest that the majority of protein consumed by these nomads came from animal and not plant sources, elevated δ¹⁵N ratios in some fauna may be indicative of ¹⁵N‐enriched soils as reported in some arid desert environments. Considerable variability in both δ¹³C and δ¹⁵N values also points to differences in individual life histories and subsistence economies over time. Despite a lack of temporal cohesion, these data illustrate the information that can be gleaned from the isolated interments of nomadic or semi‐nomadic individuals. Copyright © 2015 John Wiley & Sons, Ltd.