Weathering Climate Change in Archaeology: Conceptual Challenges and an East African Case Study

Research on the social dimensions of climate change is increasingly focused on people's experiences, values and relations to the environment as a means to understand how people interpret and adapt to changes. However, a particular challenge has been making seemingly temporally and geographically distant climate change more immediate and local so as to prompt behavioural change. Environmental humanists, anthropologists and historians have tried to address the challenge through analysis of the experiences, philosophies and memories of weather. Archaeology, commonly preoccupied by hard science approaches to climate change, has largely been absent from this conversation. Nevertheless, with its insights into material outcomes of human experiences and relations, it can become integral to the discussion of ‘weathering’ climate change and historicizing weather. Here, drawing on the subtleties of responses by Ilchamus communities in Kenya and using a mix of historical and archaeological sources, we highlight their experiences of weather since the end of the Little Ice Age and explore the potential of building archaeologies of weather.Early Stage Researcher on the Marie Curie Skłodowska Innovative Training Networks Resilience in East African Landscapes (REAL) project, funded by a grant from the European Commission's 7th Framework Programme (Grant no. 606879

Ethnogenesis and surplus food production: communitas and identity building among nineteenth- and early twentieth-century Ilchamus, Lake Baringo, Kenya

© 2017 Informa UK Limited, trading as Taylor & Francis Group. Most archaeological discussions of surplus production tend to focus either on its role in the emergence and maintenance of social complexity (whether among hunter-gatherers, farming communities or incipient states) or on the enabling properties of surplus as a basis for technological advances and aesthetic elaboration. Here, we offer a rather different perspective on surplus as an initiator of communitas and driver of ethnogenesis following a period of intense socio-ecological stress, environmental degradation and localized demographic decline during the nineteenth century. The particular case study concerns the Maa-language-speaking Ilchamus community who currently occupy areas around the southern end of Lake Baringo in the Central Rift Valley, Kenya. Drawing on a combination of new archaeological evidence, oral accounts and archival sources, the paper details the processes whereby destitute groups were drawn together into acts of surplus food production, initially of grain via the implementation of a system of irrigated agriculture and subsequently of cattle through the mobilization of kinship and related ties. In so doing, disparate older identities were abandoned or transformed and a different, unifying ethnicity–Ilchamus–emerged based on a new moral economy of shared prosperity.European Commission Marie Curie IT

Ultrafast electronic response of Ag(111) and Cu(111) surfaces: From early excitonic transients to saturated image potential

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).We investigate the evolution of attosecond to femtosecond screening and emergent potentials that govern the dynamics and energetics of electrons and holes excited in the various stages of multiphoton photoemission processes and control the photoelectron yield in recently reported experiments [X. Cui, C. Wang, A. Argondizzo, S. Garrett-Roe, B. Gumhalter, and H. Petek, Nat. Phys. 10, 505 (2014)1745-247310.1038/nphys2981]. The study is focused on the dynamical screening of holes created in preexistent quasi-two-dimensional Shockley state bands on Ag(111) and Cu(111) surfaces and of electrons excited to the intermediate and emerging screened states. Using the formalism of self-consistent electronic response, we analyze first the effects of screening on the dynamics of photoexcited electrons and holes and then of the Coulomb correlated photoexcited pair. Special attention is paid to the correlated primary electron-hole states, which commence as transient surface excitons and develop in the course of screening into uncorrelated electrons and holes propagating in the image potential and surface state bands, respectively. The obtained results enable to establish a consistent picture of transient electron dynamics at Ag(111) and Cu(111) surfaces that are becoming accessible by the time-, energy-, and momentum-resolved pump-probe multiphoton photoelectron spectroscopies.V.M.S. acknowledges partial support from the Basque Departamento de Educacion, UPV/EHU (Grant No. IT-756-13) and the Spanish Ministry od Economy and Competitiveness MINECO (Grant No. FIS2013-48286-C2-1-P). N.D. acknowledges the support of the Unity Through Knowledge Fund (UKF B1). H.P. was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Office of Basic Energy Sciences of the U.S. Department of Energy through Grant DE-FG02-09ER 16056.Peer Reviewe

Lifetime of d-holes at Cu surfaces: Theory and experiment

We have investigated the hole dynamics at copper surfaces by high-resolution angle-resolved photoemission experiments and many-body quasiparticle GW calculations. Large deviations from a free-electron-like picture are observed both in the magnitude and the energy dependence of the lifetimes, with a clear indication that holes exhibit longer lifetimes than electrons with the same excitation energy. Our calculations show that the small overlap of d- and sp-states below the Fermi level is responsible for the observed enhancement. Although there is qualitative good agreement of our theoretical predictions and the measured lifetimes, there still exist some discrepancies pointing to the need of a better description of the actual band structure of the solid.Comment: 15 pages, 7 figures, 1 table, to appear in Phys. Rev.

Causes of lawn and ornamental plants degradation at the Patriotic War Memorial Cemetery in Vukovar

Provedena istraživanja imala su za cilj utvrditi razloge propadanja travnjaka i ukrasnog bilja na Memorijalnom groblju žrtava Domovinskog rata u Vukovaru. U tu svrhu otvorena su tri reprezentativna pedološka profila iz kojih su uzeti uzorci tla za fizikalne i kemijske analize te sedam prosječnih uzoraka tla u kojima su određena kemijska svojstva tla te biljno hranidbeni kapacitet tla. Određivanje fizikalnih i kemijskih svojstava tla obavljeno je u Zavodu za ishranu bilja Agronomskog fakulteta Sveučilišta u Zagrebu standardnim analitičkim metodama. Na temelju provedenih istraživanja fizikalno-kemijskih svojstava tla utvrđeni su značajni propusti u pripremi tla i uzgojnog supstrata za biljke. To se prvenstveno odnosi na slabu dreniranost tla što uzrokuje površinsko stagniranje oborinskih i drugih voda, zbog pojave nepropusnog sloja tla i zbijenost tla u vrijeme sušnog razdoblja. Također su utvrđena vrlo nepovoljna fizikalna i kemijska svojstva tla (visoka pH vrijednost), a relativno niski biljno-hranidbeni kapacitet tla. Zbog vrlo slabe propusnosti tla, potrebno je postaviti sustav cijevne drenaže koji će omogućiti odvođenje suvišne vode u pojedinim razdobljima godine. Unošenjem većih količina organske tvari (treseta cca 4-5 L/m2 i zrelog stajskog gnojiva cca 4-5 kg/m2) i pijeska te dobrim miješanjem s postojećim tlom, povećat će se propusnost, kapacitet tla za zrak i vodu i stabilnost strukture, a umanjit će se specifična masa tla volumna i zbijenost tla. Povoljna pH reakcija tla za određenu kulturu može se postići unošenjem različitih količina treseta odgo-varajuće pH vrijednosti. Osnovnom gnojidbom s većim količinama mineralnih gnojiva, poglavito fosfornih, povećava se fond pristupačnih hraniva u tlu.The aim of the research was to find the reasons for lawn and ornamental plants degradation at the Patriotic War Memorial Cemetery in Vukovar. For this purpose, three representative pedological profiles were opened, from which soil samples were taken for physical and chemical analyses. Seven average soil samples were also taken for determining soil chemical properties and the plant nutrition capacity. Physical and chemical properties of the soil were analyzed in the Department of Plant Nutrition, Faculty of Agriculture, University of Zagreb, by standard analytical methods. Analyses of the soil physical and chemical properties revealed considerable oversights in the soil and substrate preparation for cultivation. This primarily applies to poor soil drainage, which caused surface retention of precipitation and other waters because of the formation of a soil layer impervious to water and compactness during the dry period. Excessively high soil reaction (pH value) was also recorded as well as a relatively low plant nutrition capacity. Due to very poor soil permeability, a pipe drainage system should be installed to enable draining of surplus water that appears in some parts of the year. Higher amounts of organic matter (cca 4-5 L/m2 peat and ca 4-5 kg/m2 ripe manure) and sand well mixed with the existing soil will increase the soil permeability, air capacity and structure stability. Specific soil volume and compactness will also be reduced. Acid Lithuanian peat will lower the pH value, while higher mineral fertilizer (mainly phosphorus) rates will raise the levels of available nutrients in soil

Spectral properties of Cs and Ba on Cu(111) at very low coverage: Two-photon photoemission spectroscopy and electronic structure theory

The adsorption of Cs and Ba on Cu(111) is investigated by means of one- and two-photon photoemission experiments and theoretically by first-principles calculations. The spectral properties of these systems, induced by both surface and adatom states, are studied at submonolayer coverage through angle-resolved measurements. A coverage-dependent analysis is also exploited in the assignment of the observed electronic states. The comparison with ab initio calculations allows identification of all the spectral features induced by Cs and Ba chemisorption. The theoretical analysis concerns the limiting single adatom case, treated in an embedding approach with a one-dimensional potential for the surface. The agreement between the calculated density of states and the experimental spectra confirms that the model substrate retains all the relevant physics entering in the adsorption process. The differences between the electronic structures of Cs and Ba on the Cu(111) surface can be attributed to the group-dependent screening of the core potentials as manifested by the ionic radii and ionization potentials (alkali vs alkaline earth)

Hole dynamics in noble metals

We present a detailed analysis of hole dynamics in noble metals (Cu and Au), by means of first-principles many-body calculations. While holes in a free-electron gas are known to live shorter than electrons with the same excitation energy, our results indicate that d-holes in noble metals exhibit longer inelastic lifetimes than excited sp-electrons, in agreement with experiment. The density of states available for d-hole decay is larger than that for the decay of excited electrons; however, the small overlap between d- and sp-states below the Fermi level increases the d-hole lifetime. The impact of d-hole dynamics on electron-hole correlation effects, which are of relevance in the analysis of time-resolved two-photon photoemission experiments, is also addressed.Comment: 4 pages, 2 figures, to appear in Phys. Rev. Let

Ultrafast Spin Dynamics in Nickel

The spin dynamics in Ni is studied by an exact diagonalization method on the ultrafast time scale. It is shown that the femtosecond relaxation of the magneto-optical response results from exchange interaction and spin-orbit coupling. Each of the two mechanisms affects the relaxation process differently. We find that the intrinsic spin dynamics occurs during about 10 fs while extrinsic effects such as laser-pulse duration and spectral width can slow down the observed dynamics considerably. Thus, our theory indicates that there is still room to accelerate the spin dynamics in experiments.Comment: 4 pages, Latex, 4 postscript figure

Kvalitativna procjena eliminacije TCP-a i TAMORF-a iz organizma štakora metodom GC-MS

Nerve agents are highly toxic organophosphorus (OP) compounds. They inhibit acetylcholinesterase (AChE), an enzyme that hydrolyses acetycholine (ACh) in the nervous system. Pathophysiological changes caused by OP poisonings are primarily the consequence of surplus ACh on cholinergic receptors and in the central nervous system. Standard treatment of OP poisoning includes combined administration of carbamates, atropine, oximes and anticonvulsants. In order to improve therapy, new compounds have been synthesised and tested. Tenocyclidine (TCP) and its adamantane derivative 1-[2-(2-thienyl)-2-adamantyl] morpholine (TAMORF) have shown interesting properties against soman poisoning. In this study, we developed a qualitative GC-MS method to measure elimination of TCP and TAMORF through rat urine in order to learn more about the mechanisms through which TCP protects an organism from OP poisoning and to determine the duration of this protective effect. GC-MS showed that six hours after treatment with TCP, rat urine contained only its metabolite 1-thienylcyclohexene, while urine of rats treated with TAMORF contained both TAMORF and its metabolites.Živčani bojni otrovi po strukturi su organofosforni (OP) spojevi, čija je zajednička značajka ireverzibilna inhibicija acetilkolinesteraze (AChE), enzima koji hidrolizira acetilkolin (ACh) u živčanom sustavu. Patofi ziološka zbivanja koja nastaju pri otrovanju OP-spojevima primarno su posljedica akumuliranog ACh na kolinergičkim receptorima i u središnjem živčanom sustavu. Još uvijek nesavršen, standardni tretman liječenja otrovanja OP-spojevima uključuje kombiniranu primjenu estera karbamata, atropina, oksima i antikonvulziva. Kako bi se unaprijedila uobičajena terapija, osobito kod otrovanja somanom, ispituju se antidotski učinci mnogih spojeva. Tenociklidin (TCP) i njegov adamantanski derivat TAMORF pokazali su zanimljiva svojstva pomoćne terapije pri otrovanju somanom. Kako bi se proširile dosadašnje spoznaje o načinu na koji tenociklidini štite organizam od trovanja OP-spojevima te također o trajanju njihova antidotskog učinka, u ovom radu razvijena je GC-MS-metoda za praćenje eliminacije TCP-a i TAMORF-a iz organizma. Rezultati GC-MS-analize pokazali su da šest sati nakon tretiranja štakora TCP-om mokraće sadržavaju metabolit TCP-a 1-tienilcikloheksen, dok šest sati nakon tretiranja štakora TAMORF-om mokraće sadržavaju i TAMORF i njegove metabolite. Drugim riječima, šest sati nakon tretmana TCP se potpuno metabolizira, dok se TAMORF metabolizira djelomično, a djelomično ostaje nepromijenjen

Historical Ecologies of Pastoralist Overgrazing in Kenya: Long-Term Perspectives on Cause and Effect

The spectre of ‘overgrazing’ looms large in historical and political narratives of ecological degradation in savannah ecosystems. While pastoral exploitation is a conspicuous driver of landscape variability and modification, assumptions that such change is inevitable or necessarily negative deserve to be continuously evaluated and challenged. With reference to three case studies from Kenya – the Laikipia Plateau, the Lake Baringo basin, and the Amboseli ecosystem – we argue that the impacts of pastoralism are contingent on the diachronic interactions of locally specific environmental, political, and cultural conditions. The impacts of the compression of rangelands and restrictions on herd mobility driven by misguided conservation and economic policies are emphasised over outdated notions of pastoralist inefficiency. We review the application of ‘overgrazing’ in interpretations of the archaeological record and assess its relevance for how we interpret past socio-environmental dynamics. Any discussion of overgrazing, or any form of human-environment interaction, must acknowledge spatio-temporal context and account for historical variability in landscape ontogenies