Landscape change in central Latvia since the Iron Age: multi-proxy analysis of the vegetation impact of conflict, colonization and economic expansion during the last 2000 years

This study represents the first detailed multi-proxy palaeoenvironmental investigation associated with a Late Iron Age lake-dwelling site in the eastern Baltic. The main objective was to reconstruct the environmental and vegetation dynamics associated with the establishment of the lake-dwelling and land-use during the last 2,000 years. A lacustrine sediment core located adjacent to a Late Iron Age lake-dwelling, medieval castle and Post-medieval manor was sampled in Lake Āraiši. The core was dated using spheroidal fly-ash particles and radiocarbon dating, and analysed in terms of pollen, non-pollen palynomorphs, diatoms, loss-on-ignition, magnetic susceptibility and element geochemistry. Associations between pollen and other proxies were statistically tested. During ad 1–700, the vicinity of Lake Āraiši was covered by forests and human activities were only small-scale with the first appearance of cereal pollen (Triticum and Secale cereale) after ad 400. The most significant changes in vegetation and environment occurred with the establishment of the lake-dwelling around ad 780 when the immediate surroundings of the lake were cleared for agriculture, and within the lake there were increased nutrient levels. The highest accumulation rates of coprophilous fungi coincide with the occupation of the lake-dwelling from ad 780–1050, indicating that parts of the dwelling functioned as byres for livestock. The conquest of tribal lands during the crusades resulted in changes to the ownership, administration and organisation of the land, but our results indicate that the form and type of agriculture and land-use continued much as it had during the preceding Late Iron Age.

The human-resource management practice of retail branding: an ethnography within Oxfam trading division

Purpose – While the charity retail literature emphasizes the richness of human resource practices among charity retailers, it rarely makes the link between these practices and their interest for establishing charity retailers' brands. Simultaneously, while the retail branding literature increasingly emphasizes the central role of human resource practices for retail branding, it rarely explains how retailers should conduct such practices. The purpose of this study is to test the recent model proposed by Burt and Sparks in 2002 (the “fifth generation of retail branding”) which proposes that a retail brand depends on the alignment between a retailer's substance (vision and culture) and its perceived image by customers. Design/methodology/approach – The research is based on an ethnographic study conducted within the Oxfam Trading Division, GB from October to December 2002. Findings – The study supports the Burt and Spark's model and makes explicit the practice of human resource for branding. The study demonstrates that it was the alignment between the vision of Oxfam's top management and its new customer‐oriented culture, two elements of its core substance mediated to customers by store employees, which has enabled an improved customers' perception of the brand. The study also seeks to elaborate upon the Burt and Spark's model by specifying an ascending feedback loop starting from customers' perception of Oxfam brand and enabling the creation of a suitable culture and vision again mediated by store employees. Research limitations/implications – New research should explore whether and how retailers create synergies between human resource and marketing functions to sustain their brand image. Practical implications – If the adoption of business practices by charity retailers is often discussed, this study highlights that commercial retailers could usefully transfer human resource best practices from leading charity retailers to develop their retail brand. Originality/value – The paper is of value to commercial retailers.

Causal relationships vs. emergent patterns in the global controls of fire frequency

Global controls on month-by-month fractional burnt area (2000–2005) were investigated by fitting a generalised linear model (GLM) to Global Fire Emissions Database (GFED) data, with 11 predictor variables representing vegetation, climate, land use and potential ignition sources. Burnt area is shown to increase with annual net primary production (NPP), number of dry days, maximum temperature, grazing-land area, grass/shrub cover and diurnal temperature range, and to decrease with soil moisture, cropland area and population density. Lightning showed an apparent (weak) negative influence, but this disappeared when pure seasonal-cycle effects were taken into account. The model predicts observed geographic and seasonal patterns, as well as the emergent relationships seen when burnt area is plotted against each variable separately. Unimodal relationships with mean annual temperature and precipitation, population density and gross domestic product (GDP) are reproduced too, and are thus shown to be secondary consequences of correlations between different controls (e.g. high NPP with high precipitation; low NPP with low population density and GDP). These findings have major implications for the design of global fire models, as several assumptions in current models – most notably, the widely assumed dependence of fire frequency on ignition rates – are evidently incorrect.

Structural stability of the synthetic thermoelectric ternary and nickel-substituted tetrahedrite phases

The purity and structural stability of the high thermoelectric performance Cu12Sb4S13 and Cu10.4Ni1.6Sb4S13 tetrahedrite phases, synthesized by solid–liquid–vapor reaction and Spark Plasma Sintering, were studied at high temperature by Rietveld refinement using high resolution X-ray powder diffraction data, DSC/TG measurements and high resolution transmission electron microscopy. In a complementary study, the crystal structure of Cu10.5Ni1.5Sb4S13 as a function of temperature was investigated by powder neutron diffraction. The temperature dependence of the structural stability of ternary Cu12Sb4S13 is markedly different to that of the nickel-substituted phases, providing clear evidence for the significant and beneficial role of nickel substitution on both sample purity and stability of the tetrahedrite phase. Moreover, kinetic effects on the phase stability/decomposition have been identified and discussed in order to determine the maximum operating temperature for thermoelectric applications. The thermoelectric properties of these compounds have been determined for high density samples (>98%) prepared by Spark Plasma Sintering and therefore can be used as reference values for tetrahedrite samples. The maximum ZT of 0.8 was found for Cu10.4Ni1.6Sb4S13 at 700 K.

Palaeoenvironmental evidence for the impact of the crusades on the local and regional environment of medieval (13th–16th century) northern Latvia, eastern Baltic

This paper evaluates the impact of the crusades on the landscape and environment of northern Latvia between the 13th–16th centuries (medieval Livonia). The crusades replaced tribal societies in the eastern Baltic with a religious state (Ordenstaat) run by the military orders and their allies, accompanied by significant social, cultural and economic developments. These changes have previously received little consideration in palaeoenvironmental studies of past land use in the eastern Baltic region, but are fundamental to understanding the development and expansion of a European Christian identity. Sediment cores from Lake Trikāta, located adjacent to a medieval castle and settlement, were studied using pollen, macrofossils, loss-on-ignition and magnetic susceptibility. Our results show that despite continuous agricultural land use from 500 BC, the local landscape was still densely wooded until the start of the crusades in AD 1198 when a diversified pattern of pasture, meadow and arable land use was established. Colonisation followed the crusades, although in Livonia this occurred on a much smaller scale than in the rest of the Ordenstaat; Trikāta is atypical showing significant impact following the crusades with many other palaeoenvironmental studies only revealing more limited impact from the 14th century and later. Subsequent wars and changes in political control in the post-medieval period had little apparent effect on agricultural land use.

Thermoelectric materials: a new rapid synthesis process for non-toxic and high-performance tetrahedrite compounds

The feasibility to synthesize, in large quantity, pure and non-toxic tetrahedrite compounds using high-energy mechanical-alloying from only elemental precursors is reported in the present paper for the first time. Our processing technique allows a better control of the final product composition and leads to high thermoelectric performances (ZT of 0.75 at 700 K), comparable to that reported on sealed tube synthesis samples. Combined with spark plasma sintering, the production of highly pure and dense samples is achieved in a very short time, at least 8 times shorter than in conventional liquid-solid-vapor synthesis process. The process described in this paper is a promising way to produce high performance tetrahedrite materials for cost-effective and large-scale thermoelectric applications.

Thermoelectric properties of TiS2 mechanically alloyed compounds

Bulk polycrystalline samples in the series Ti1−xNbxS2 (0 ≤ x ≤ 0.075) were prepared using mechanical alloying synthesis and spark plasma sintering. X-ray diffraction analysis coupled with high resolution transmission electron microscopy indicates the formation of trigonal TiS2 by high energy ball-milling. The as-synthesized particles consist of pseudo-ordered TiS2 domains of around 20–50 nm, joined by bent atomic planes. This bottom-up approach leads, after spark plasma sintering, to homogeneous solid solutions, with a niobium solubility limit of x = 0.075. Microstructural observations evidence the formation of small crystallites in the bulk compounds with a high density of stacking faults. The large grain boundary concentration coupled with the presence of planar defects, leads to a substantial decrease in the thermal conductivity to 1.8 W/mK at 700 K. This enables the figure of merit to reach ZT = 0.3 at 700 K for x = 0.05, despite the lower electron mobility in mechanically alloyed samples due to small crystallite/grain size and structural defects.

Up-scaled synthesis process of sulphur-based thermoelectric materials

The scale up of Spark Plasma Sintering (SPS) for the consolidation of large square monoliths (50 × 50 × 3 mm3) of thermoelectric material is demonstrated and the properties of the fabricated samples compared with those from laboratory scale SPS. The SPS processing of n-type TiS2 and p-type Cu10.4Ni1.6Sb4S13 produces highly dense compacts of phase pure material. Electrical and thermal transport property measurements reveal that the thermoelectric performance of the consolidated n- and p-type materials is comparable with that of material processed using laboratory scale SPS, with ZT values that approach 0.8 and 0.35 at 700 K for Cu10.4Ni1.6Sb4S13 and TiS2, respectively. Mechanical properties of the consolidated materials shows that large-scale SPS processing produces highly homogeneous materials with hardness and elastic moduli that deviate little from values obtained on materials processed on the laboratory scale.