Modelled dispersal patterns for wood and grass charcoal are different: implications for paleofire reconstruction

Sedimentary charcoal records provide useful perspectives on the long-term controls and behavior of fire in the Earth system. However, a comprehensive understanding of the nuances, biases, and limitations of charcoal as a fire proxy is necessary for reliable paleofire interpretations. Here, we use a charcoal dispersal model to answer the following questions: (1) How does the dispersal of wood and grass charcoal particles differ? (2) Do traditional conceptual models of charcoal dispersal reliably characterize grass charcoal dispersal? We find that small differences in shape (L:W) and density of grass and wood charcoal can cause substantial differences in particle dispersal and source area. Whereas the modelled dispersal of wood charcoal shows a localized deposition signal which decays with distance, grass charcoal shows more diffuse deposition lacking a localized center (for both >125 µm and >60 µm). Although paleofire research has typically not distinguished between fuel types, we show that the dispersal of charcoal derived from different fuels is unlikely to be uniform. Because differences in localization, production, and preservation could bias aggregate charcoal accumulation, caution should be taken when interpreting wood and grass-derived charcoal particles preserved in the same record. Additionally, we propose an alternative, dual background conceptual model of grass charcoal dispersal, as the traditional, two-component (peak and background) conceptual model does not accurately characterize the modelled dispersal of grass charcoal. Lastly, this mismatch of conceptualizations of dispersal mechanics implies that grass charcoal may not fit the criteria necessary for peak analysis techniques

Comparative investigation of the pathogenicity of three Mycobacterium tuberculosis mutants defective in the synthesis of p-hydroxybenzoic acid derivatives.

p-Hydroxybenzoic acid derivatives (p-HBADs) are glycoconjugates secreted by all Mycobacterium tuberculosis isolates whose contribution to pathogenicity remains to be determined. The pathogenicity of three transposon mutants of M. tuberculosis deficient in the biosynthesis of some or all forms of p-HBADs was studied. Whilst the mutants grew similarly to the wild-type strain in macrophages and C57BL/6 mice, two of the mutants induced a more severe and diffuse inflammation in the lungs. The lack of production of some or all forms of p-HBADs in these two mutants also correlated with an increased secretion of the pro-inflammatory cytokines tumour-necrosis factor α, interleukin 6 and interleukin 12 in vivo. We propose that the loss of production of p-HBADs by tubercle bacilli results in their diminished ability to suppress the pro-inflammatory response to infection and that this ultimately provokes extensive pulmonary lesions in the C57BL/6 model of tuberculosis infection

Warehouse management system

Práca sa zaoberá návrhom a implementáciou na mieru šitého systému pre podporu správy skladového hospodárstva malého podniku s ohľadom na požiadavky konkrétneho zadávateľa. Systém zprehľadní správu skladových zásob a zjednoduší proces naskladnenia parsovaním dát z elektronickej podoby faktúr. Za cieľ si práca súčasne kľadie i overenie funkčnosti systému programovými testami i testami použiteľnosti.Aim of the thesis is to design and implement a web application as a warehouse management system according to the requirements of a company the system is built for. Besides providing greater clarity of used resources, system also simplifies the process of stocking by parsing contents of provided pdf invoices. Focus has also been placed on verification of the proper implementation of the system by means of unit and usability testing

Holocene Climatic Changes in the Alaskan Arctic as Inferred from Oxygen-Isotopic Analysis

Reconstructions of Holocene climate in the Alaskan Arctic allow for better understanding of how the region may respond to future climate changes. However, long-term records from the region are scarce. We conducted lithological and isotopic analyses at Wahoo Lake (69º 4.612, -146º 55.676) to infer Holocene climate variability in northern Alaska. Isotopic composition of modern water from this large, open-basin lake in the northern foothills of the Brooks Range suggests that winter precipitation dominates inputs to the lake. Isotopic composition of Pisidium exhibits large variations throughout the past 11,800 years, with δ18O values ranging between 11.6 and 14.2‰ (VSMOW) and δ13C between -2.3 and -7.1‰ (VPDB). Loss-on-ignition (LOI) shows high carbonate content (8.1-50.9%) in the subbasin sediments between 11.8-6.3 kcal BP, transitioning to lower carbonate (1.3-25.3%) and increased organic content (11.7-65.2%) between 6.3-1.4 kcal BP. High carbonate and elevated δ18O values (13.0-14.0‰) from 11.5-8.5 kcal BP likely reflect lower lake level and possibly evaporative enrichment of lake water, suggesting warm, dry summers during the early Holocene. The disappearance of Pisidium, paired with a decrease in calcite deposition at ~6.5 kcal BP, suggests increasing lake-level in the mid-Holocene, which is supported by a basal date of 5.3 kcal BP from a core of the shallow shelf of the lake. This increase coincided with lake-level increases in interior Alaska and likely resulted from enhanced regional effective moisture. The shelf sediments exhibit a marked increase in carbonate content at ~3.5 kcal BP and δ18O values generally rose from 12.4‰ at 3.5 kcal BP to 13.2‰ at 2.0 kcal BP (range = 11.6-14.2‰), suggesting increasing annual temperatures during this period. After 2.0 kcal BP, δ18O values fluctuate between 11.9-13.3‰, but generally decline until 1.0 kcal BP, suggesting dramatic temperature fluctuations in the late Holocene. These Holocene variations in δ18O values at Wahoo Lake generally correspond to fluctuations in total solar irradiance, suggesting that solar variability may have played an important role in Holocene climate change of the Alaskan Arctic. Understanding the role of solar irradiance on natural variability of climate in this region provides a framework for evaluating climatic response and sensitivity to anthropogenic forcing.Ope

Paleoenvironment and Archaeology Provide Cautionary Tales for Climate Policymakers

Federal climate policy in the United States is still in its infancy and is in large part characterized by efforts to reach a consensus on the very existence and causality of climate change. This has stemmed from a sociopolitical rift within the country, with the objectivity and usefulness of science attacked by detractors. Scientists who are most qualified to defend their methods and provide information to policymakers rarely have an institutional incentive to share this knowledge, but should be encouraged to communicate their findings to the public, especially those who receive public funding. By not doing so, they are effectively 1) keeping data and their interpretations within the academy alone, despite their importance to the public welfare, 2) losing public support through inactivity, and 3) potentially harming the future availability of research support in what has rapidly become a politically polarized funding atmosphere. Archaeologists and geoscientists in particular, as repositories of past ecological knowledge established through one method (Western academic) of empirical examination, are well positioned to broadcast to the public a variety of societal responses to long-term environmental change as well as the repercussions of political reorganization in the wake of resource shortage-induced societal collapse. This paper summarizes a few promising public outreach engagements on environment and climate change, and suggests further venues for institutional change at the university level. As an example of how multi-causal socio-ecological processes can be concisely packaged for consumption by the public and policymakers without oversimplifying data, we present a synthesis of regional case studies from the New and Old Worlds. Case studies are connected through anthropological processes of cooperation versus exclusion, subsistence shifts, sociopolitical (re)organization and hierarchy, violence, and disease in a preliminary attempt a) to identify the emotional and anecdotal psychology of our own society when it comes to the chang5Brett Kaufman, Christopher S. Kelly and Richard S. Vachula ing global environment, b) to discuss the issue of scalar differences between ancient and modern ecology, and c) to call on academics to introspectively alter our own attitudes and systems of incentives at the university level

Beringia and the peopling of the Western Hemisphere

Did Beringian environments represent an ecological barrier to humans until less than 15 000 years ago or was access to the Americas controlled by the spatial–temporal distribution of North American ice sheets? Beringian environments varied with respect to climate and biota, especially in the two major areas of exposed continental shelf. The East Siberian Arctic Shelf (‘Great Arctic Plain’ (GAP)) supported a dry steppe-tundra biome inhabited by a diverse large-mammal community, while the southern Bering-Chukchi Platform (‘Bering Land Bridge’ (BLB)) supported mesic tundra and probably a lower large-mammal biomass. A human population with west Eurasian roots occupied the GAP before the Last Glacial Maximum (LGM) and may have accessed mid-latitude North America via an interior ice-free corridor. Re-opening of the corridor less than 14 000 years ago indicates that the primary ancestors of living First Peoples, who already had spread widely in the Americas at this time, probably dispersed from the NW Pacific coast. A genetic ‘arctic signal’ in non-arctic First Peoples suggests that their parent population inhabited the GAP during the LGM, before their split from the former. We infer a shift from GAP terrestrial to a subarctic maritime economy on the southern BLB coast before dispersal in the Americas from the NW Pacific coast

MOTC: An Interactive Aid for Multidimensional Hypothesis Generatio

The paper reports on conceptual development in the areas of database mining and knowledge discovery in databases (KDD). Our efforts have also led to a prototype implementation, called MOTC, for exploring hypothesis space in large and complex data sets. Our KDD conceptual development rests on two main principles. First, we use the crosstab representation for working with qualitative data. This is by now standard in on-line analytical processing (OLAP) applications, and we reaffirm it with additional reasons. Second, and innovatively, we use prediction analysis as a measure of goodness for hypotheses. Prediction analysis is an established statistical technique for analysis of associations among qualitative variables. It generalizes and subsumes a large number of other such measures of association, depending on specific assumptions the user is willing to make. As such, it provides a very useful framework for exploring hypothesis space in a KDD context. The paper illustrates these points with an extensive discussion of MOTC

Charcoal morphologies and morphometrics of a Eurasian grass-dominated system for robust interpretation of past fuel and fire type

Recent developments in morphological and morphometric analyses of charcoal particles have improved our ability to discern characteristics of burnt plant fuel and interpret fire-type changes. However, burning experiments linking known plants to these metrics are limited, particularly in open ecosystems. This study presents novel analyses of laboratory-produced charcoal of 22 plant species from the steppe regions of Eurasia (Romania and Russia), along with selected samples from three Holocene charcoal and pollen records from the same areas. We characterise charcoal production, morphologies and morphometrics in these grass-dominated environments, thereby enabling more robust interpretations of fuel sources and fire types for palaeofire research. Our experiments demonstrate that fire temperature can introduce biases in charcoal produced among species. Grass charcoal production was significantly lower and decreased more strongly with fire temperature compared to forbs. This suggests an underrepresentation of terrestrial graminoids in sedimentary charcoal assemblages. Morphometric analyses revealed that graminoid charcoal particles were more elongated (length-to-width ratio L/W=4) and narrower (width-to-length ratio W/L=0.38) than forbs (L/W=3.1 and W/L=0.42, respectively), in agreement with a global compilation for graminoids (L/W=4.3 for grass 5.4 grass and wetland graminoids) and forbs (L/W=2.9). However, overlapping L/W values present a challenge for establishing cut-off values for fuel type identification in charcoal assemblages with mixed fuel sources. Based on our analyses and compiled datasets from experimental burns, L/W values above 3.0 may indicate predominantly herbaceous morphologies in temperate grassland-dominated ecosystems, though values are likely to be higher for grass than forb-dominated grasslands. Notably, terrestrial grasses exhibit shorter aspect ratios (L/W=4.3) than wetland graminoids (L/W=6.4), highlighting that the aspect ratio needs tailoring to the specific environment of its application, i.e. wetland vs. terrestrial ecosystems. The long forms of graminoid charcoal particles also suggest their potential for atmospheric longer-distance transport compared to more spherical particles, meaning they likely provide insights into regional fire history. An important finding is that charcoal of herbaceous plants closely corresponded to the pollen record, highlighting a solid link between the dominant vegetation and fuel burnt in grassland-dominated environments. However, the relationship between woody charcoal and tree pollen may be more complex, as tree pollen can travel atmospherically longer distances compared to woody charcoal. Our results also highlight the complex interplay between local vegetation and charcoal composition with human fire use that needs to be considered when interpreting charcoal morphological records. A critical takeaway from this study is the importance of not assuming the universality of previous research findings and instead employing experimental approaches to characterise charcoal particles in new ecosystems prior to the application of these techniques. Furthermore, this study also highlights recommendations for further research in new geographical areas and proposes methodological adjustments to enhance the usefulness of charcoal analysis in fire research.</p

A global database of Holocene paleotemperature records

A comprehensive database of paleoclimate records is needed to place recent warming into the longer-term context of natural climate variability. We present a global compilation of quality-controlled, published, temperature-sensitive proxy records extending back 12,000 years through the Holocene. Data were compiled from 679 sites where time series cover at least 4000 years, are resolved at sub-millennial scale (median spacing of 400 years or finer) and have at least one age control point every 3000 years, with cut-off values slackened in data-sparse regions. The data derive from lake sediment (51%), marine sediment (31%), peat (11%), glacier ice (3%), and other natural archives. The database contains 1319 records, including 157 from the Southern Hemisphere. The multi-proxy database comprises paleotemperature time series based on ecological assemblages, as well as biophysical and geochemical indicators that reflect mean annual or seasonal temperatures, as encoded in the database. This database can be used to reconstruct the spatiotemporal evolution of Holocene temperature at global to regional scales, and is publicly available in Linked Paleo Data (LiPD) format.Fil: Kaufman, Darrell. Northern Arizona University.; Estados UnidosFil: McKay, Nicholas. Northern Arizona University.; Estados UnidosFil: Routson, Cody. Northern Arizona University.; Estados UnidosFil: Erb, Michael. Northern Arizona University.; Estados UnidosFil: Davis, Basil. University Of Lausanne; SuizaFil: Heiri, Oliver. University Of Basel; SuizaFil: Jaccard, Samuel. University Of Bern; SuizaFil: Tierney, Jessica. University of Arizona; Estados UnidosFil: Dätwyler, Christoph. University Of Bern; SuizaFil: Axford, Yarrow. Northwestern University; Estados UnidosFil: Brussel, Thomas. University of Utah; Estados UnidosFil: Cartapanis, Olivier. University Of Bern; SuizaFil: Chase, Brian. Universite de Montpellier; FranciaFil: Dawson, Andria. Mount Royal University; CanadáFil: de Vernal, Anne. Université du Québec a Montreal; CanadáFil: Engels, Stefan. University of London; Reino UnidoFil: Jonkers, Lukas. University Of Bremen; AlemaniaFil: Marsicek, Jeremiah. University of Wisconsin-Madison; Estados UnidosFil: Moffa Sánchez, Paola. University of Durham; Reino UnidoFil: Morrill, Carrie. University of Colorado; Estados UnidosFil: Orsi, Anais. Université Paris-Saclay; FranciaFil: Rehfeld, Kira. Heidelberg University; AlemaniaFil: Saunders, Krystyna. Australian Nuclear Science And Technology Organisation; AustraliaFil: Sommer, Philipp. University Of Lausanne; SuizaFil: Thomas, Elizabeth. University At Buffalo; Estados UnidosFil: Tonello, Marcela Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Tóth, Mónika. Balaton Limnological Institute; HungríaFil: Vachula, Richard. Brown University; Estados UnidosFil: Andreev, Andrei. Alfred Wegener Institut Helmholtz Centre for Polar and Marine Research; AlemaniaFil: Bertrand, Sebastien. Ghent University; BélgicaFil: Massaferro, Julieta. Administración de Parques Nacionales. Parque Nacional "Nahuel Huapi"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin