393 research outputs found
Lithics of the North African Middle Stone Age: assumptions, evidence and future directions
North Africa features some of the earliest manifestations of the Middle Stone Age (MSA) and fossils of our species, Homo sapiens, as well as early examples of complex culture and the long distance transfer of exotic raw materials. As they are elsewhere, lithics (i.e., stone tools) present by far the most abundant source of information on this cultural period. Given the importance of North Africa in human origins, understanding the character and distribution of MSA lithics is therefore crucial, as they shed light on early human behaviour and culture. However, the lithics of the North African MSA are poorly understood, and their technological variability is frequently obfuscated by regionally specific nomenclatures, often repeated without criticism, and diverse methods of analysis that are often incompatible. Characterising dynamic technological innovations as well as apparent technological stasis remains challenging, and many narratives have not been tested quantitatively. This significantly problematizes hypotheses of human evolution and dispersals invoking these data that extend beyond North Africa. This paper therefore presents a description of the lithics of the North African MSA, including their technological characteristics, chronology, spatial distribution and associated research traditions. A range of interpretations concerning early H. sapiens demography in North Africa are then re-evaluated in the light of this review, and the role and power of lithic data to contribute to such debates is critically assessed
From the Mendeleev periodic table to particle physics and back to the periodic table
We briefly describe in this paper the passage from Mendeleev's chemistry
(1869) to atomic physics (in the 1900's), nuclear physics (in the 1932's) and
particle physics (from 1953 to 2006). We show how the consideration of
symmetries, largely used in physics since the end of the 1920's, gave rise to a
new format of the periodic table in the 1970's. More specifically, this paper
is concerned with the application of the group SO(4,2)xSU(2) to the periodic
table of chemical elements. It is shown how the Madelung rule of the atomic
shell model can be used for setting up a periodic table that can be further
rationalized via the group SO(4,2)xSU(2) and some of its subgroups. Qualitative
results are obtained from this nonstandard table.Comment: 15 pages; accepted for publication in Foundations of Chemistry
(special issue to commemorate the one hundredth anniversary of the death of
Mendeleev who died in 1907); version 2: 16 pages; some sentences added;
acknowledgment and references added; misprints correcte
Frequency-encoded linear cluster states with coherent Raman photons
Entangled multi-qubit states are an essential resource for quantum
information and computation. Solid-state emitters can mediate interactions
between subsequently emitted photons via their spin, thus offering a route
towards generating entangled multi-photon states. However, existing schemes
typically rely on the incoherent emission of single photons and suffer from
severe practical limitations, for self-assembled quantum dots most notably the
limited spin coherence time due to Overhauser magnetic field fluctuations. We
here propose an alternative approach of employing spin-flip Raman scattering
events of self-assembled quantum dots in Voigt geometry. We argue that weakly
driven hole spins constitute a promising platform for the practical generation
of frequency-entangled photonic cluster states
Propranolol, infantile haemangiomas, and serendipity : new use for an old drug
Capillary haemangiomas are benign lesions that may occur anywhere on the skin, may grow rapidly in the first two years of life and may impair vital organs. Propranolol has been recently discovered to shrink these lesions effectively. We report the first such patient treated in Malta with this drug.peer-reviewe
Bibliography on philosophy of chemistry
The term philosophy of chemistry is here construed broadly to include some publications from the history of chemistry and chemical education. Of course this initial selection of material has inevitably been biased by the interests of the author.
This bibliography supersedes that of van Brakel and Vermeeren (1981), although no attempt has been made to include every single one of their entries, especially in languages other than English. Also, readers interested particularly in articles in German may wish to consult the bibliography by Dittus and Mayer which also contains some material not included here (Dittus and Mayer, 1992).
The aim is to maintain an up-to-date version of this bibliography and to publish a revised version in due course. Suggestions for further inclusions should be sent to the author
Tropical forests in the deep human past
Since Darwin, studies of human evolution have tended to give primacy to open ‘savannah’ environments as the ecological cradle of our lineage, with dense tropical forests cast as hostile, unfavourable frontiers. These perceptions continue to shape both the geographical context of fieldwork as well as dominant narratives concerning hominin evolution. This paradigm persists despite new, ground-breaking research highlighting the role of tropical forests in the human story. For example, novel research in Africa's rainforests has uncovered archaeological sites dating back into the Pleistocene; genetic studies have revealed very deep human roots in Central and West Africa and in the tropics of Asia and the Pacific; an unprecedented number of coexistent hominin species have now been documented, including Homo erectus, the ‘Hobbit’ (Homo floresiensis), Homo luzonensis, Denisovans, and Homo sapiens. Some of the earliest members of our own species to reach South Asia, Southeast Asia, Oceania and the tropical Americas have shown an unexpected rapidity in their adaptation to even some of the more ‘extreme’ tropical settings. This includes the early human manipulation of species and even habitats. This volume builds on these currently disparate threads and, for the first time, draws together a group of interdisciplinary, agenda-setting papers that firmly places a broader spectrum of tropical environments at the heart of the deep human past1. The tropics: a frontier for the deep human past 2. African tropical forests 3. Southeast Asian and pacific forests 4. Neotropical forests 5. Synthesi
Archaeological sites and palaeoenvironments of Pleistocene West Africa
African paleoanthropological studies typically focus on regions of the continent such as Eastern, Southern and Northern Africa, which hold the highest density of Pleistocene archaeological sites. Nevertheless, lesser known areas such as West Africa also feature a high number of sites. Here, we present a high-resolution map synthesising all well contextualised Pleistocene archaeological sites present in Sub-Saharan West Africa. A detailed elevation and ecoregional map was developed and correlated with palaeoanthropological sites. This map is supplemented with 1,000- and 2000-year interval climate reconstructions over the last 120,000 years for three subregions of high archaeological interest. The presented archaeological sites were compiled by reviewing published literature, and selected based on: (1) documented archaeological stratification or >10 characteristic artefacts, (2) published coordinates, and (3) published chronometric ages or relative dating. The data presented here elucidates the current state of knowledge of Pleistocene West Africa, highlighting the regional potential for human evolutionary studies.1. Introduction 2. Data and methods 3. Map description 4. Discussio
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