The need for river management and stream restoration practices to integrate hydrogeomorphology

There is growing support amongst scientists worldwide about the need for a shift in river management approaches to include hydrogeomorphic processes. However, the degree to which these concepts are transferred to governmental agencies and practitioners varies widely. In Quebec, for example, many stream restoration projects are based on the (incorrect) assumption that river mobility and its inevitable consequences (bank erosion of meanders, presence of woody debris in the channel) are problematic for salmonids. This paper presents examples drawn from current guidelines on stream restoration for fish habitat in Quebec to demonstrate the need to improve the knowledge exchange among scientists and decision makers about the positive impact of river mobility and large wood dynamics on biodiversity. Our observations reveal that existing guidelines for stream restoration in Quebec need to be revised to better integrate hydrogeomorphic concepts and to no longer assume that maintaining rivers in a static state is beneficial for fish. Adopting the “freedom space for rivers” approach would likely result in improved habitat as it combines natural processes related to mobility, flooding, and riparian wetland connectivity to determine the minimal space around rivers where development should not be allowed, thus allowing river processes to be restored.     

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.     

Spatial distribution of US employment in an urban efficiency wage setting

We analyze whether efficiency wages operate in urban labor markets, within the framework proposed by Ross and Zenou, in which shirking at work and leisure are assumed to be substitutes. We use unique data from the American Time Use Survey (ATUS) that allow us to analyze the relationships between leisure, shirking, commuting, employment, and earnings. We confirm that shirking and leisure are substitutes, and present an estimate of this relationship, representing the only empirical test of the relationship between a worker's time endowment and shirking at work. Our findings point to the existence of efficiency wages in labor markets.     

C. Douglas Dillon,President Kennedy's Economic Envoy*

This article focuses on President John F. Kennedy's Secretary of the Treasury, C. Douglas Dillon and contends that he played an important part in sustaining the political cooperation that underpinned the Bretton-Woods system during one of its first crisis points. Rather than focusing solely on structural, economic trends, the article suggests that individual actors mattered as well. As a bipartisan figure that was well regarded in Europe, Dillon was able to act effectively as an envoy to the private sector, principally Wall Street, and to France, which both threatened the stability of the dollar. The article explores Dillon's role in shaping Kennedy's economic policies in a more conservative direction than his successor, Lyndon B. Johnson, and in his external efforts to garner support for the Democratic administration.     

Fluvial spatial taphonomy: a new method for the study of post-depositional processes

Traditional taphonomic analyses do not consider the emergent properties resulting from the relationship of variables. Several of these emergent properties are expressed spatially. Here, we present a spatial taphonomic approach to the understanding of post-depositional processes affecting experimental assemblages modified by fluvial currents. Spatial statistical methods are a great tool to understand how different taphonomic variables relate at a spatial scale. The results of the application of this method to bone assemblages affected by low- and high-energy flows show the loss or modification of most of the original spatial taphonomic relationships. It also shows the degree of bone loss according to element, anatomical section and bone structure, and shape types. Anisotropy is identified in both experimental contexts. These results add new criteria to assess the impact of water flows in bone assemblages and contribute to define the properties of lag assemblages.     

Microwear study of quartzite artefacts: preliminary results from the Middle Pleistocene site of Payre (South-eastern France)

Preliminary functional results obtained from the quartzite assemblage of the Early Middle Palaeolithic site of Payre (South-eastern France) are presented. In an area rich in flint, hominins at Payre also collected quartzite in their local environment, specifically along the Rhône River banks. Although the Payre lithic assemblage is largely composed of flint, quartzite was introduced in the site mainly as large cutting tools knapped outside. This fact pointed out an apparently highly differential treatment of the raw material types available in the region. A major concern is to understand the reason why. Is there any functional reason for the introduction of those artefacts, perhaps to perform specific activities related to the toughness of quartzite? Or is there any functional differentiation among the various raw materials? Use-wear analysis is a useful tool for better understanding human technological choices and strategies of lithic raw material management. Before attempting to extensively apply use-wear analysis on the quartzite assemblage, we analysed a limited sample to evaluate the general surface preservation. A specific experimental programme with the same local quartzite was carried out in order to provide a reliable comparative reference for interpreting use-wear evidence on archaeological implements. Methodological difficulties related to use-wear analysis applied to quartzite artefacts are also discussed. Both Optical light microscopy (OLM) and Scanning Electron Microscopy (SEM) were employed in this study; however, interpretations were elaborated considering principally SEM micro-graphs.The analysis of the archaeological material showed a good state of preservation of the surfaces with a low incidence of post-depositional alterations. The documented use-wear allowed us to identify the active edges, the kinematics and, more rarely, the worked material. Chopping activities were documented on two large artefacts suggesting a specific utility of those tools.     

Early Islamic pigments at Nishapur,north-eastern Iran: studies on the painted fragments preserved at The Metropolitan Museum of Art

Pigments appearing on ninth–twelfth-century AD-carved stucco, wall painting, and terracotta friezes excavated at Nishapur in north-eastern Iran were investigated by optical reflectance spectroscopy, micro X-ray fluorescence spectrometry (μ-XRF), X-ray diffractometry (XRD), micro-Raman spectroscopy (μ-Raman), and scanning electron microscopy (SEM). Many of the pigments identified including vermilion, red lead, hematite, limonite, carbon black, atacamite, calcite, and gypsum have been identified in previous studies of pigments used in later Islamic periods. However, a series of unusual pigments such as wulfenite, pyromorphite, phoenicochroite, and jarosite were also found in the present study. The association of kaolinite and alunite with limonite and other Fe-bearing yellow pigments points to a local provenance for these pigments. In addition, the presence of orpiment in the vermilion may be indicative that the vermilion was artificially manufactured. These findings suggest that pigment use and manufacturing during the ninth to eleventh centuries in Nishapur was still in a trial-and-error stage and the palette known from the twelfth century onwards had not yet been systematized.     

Compound-specific amino acid isotopic proxies for distinguishing between terrestrial and aquatic resource consumption

Compound-specific amino acid carbon-isotope compositions have shown particular promise for elucidating dietary behaviors in complex environmental contexts, and may also be able to mitigate the effect of many of the limitations inherent to palaeodietary reconstructions. Here, we investigate the efficacy of compound-specific amino acid isotopic proxies in characterizing the consumption of different dietary protein sources using amino acid carbon-isotope compositions for humans and fauna from Rössberga (Early to Middle Neolithic), Köpingsvik (Mesolithic and Middle Neolithic), and Visby (Medieval Period), Sweden. We also assess the explanatory capabilities of an isotopic mixing model when used with essential amino acid carbon-isotope compositions of humans and local fauna. All three isotopic proxies distinguished among humans from the three sites consistently and informatively, and were able to enhance the broad interpretations made using bulk isotopic compositions. The mixing model palaeodietary reconstruction revealed considerable diversity in relative protein source contributions among individuals at both Köpingsvik and Visby. Comparing the mixing model for bulk carbon- and nitrogen-isotope compositions to the model for essential amino acid isotopic compositions further demonstrated the likelihood of underestimation and overestimation of marine protein consumption for both aquatic-dominant and mixed marine-terrestrial diets when using bulk isotopic compositions.