The Transition to Agriculture: Climate Reversals, Population Density, and Technical Change

Until about 13,000 years ago all humans obtained their food through hunting and gathering, but thereafter people in some parts of the world began a transition to agriculture. Recent data strongly implicate climate change as the driving force behind the agricultural transition in southwest Asia. We propose a model of this process in which population and technology respond endogenously to climate. The key idea is that after a lengthy period of favorable environmental conditions during which regional population grew significantly, an abrupt climate reversal forced people to take refuge at a few ecologically favored sites. The resulting spike in local population density reduced the marginal product of labor in foraging and made agriculture attractive. Once agriculture was initiated, rapid technological progress through artificial selection on plant characteristics led to domesticated varieties. Farming became a permanent part of the regional economy when this productivity growth was combined with climate recoveryorigins of agriculture, foraging, hunting and gathering, climate change, population density, technical change, domestication, archaeology, anthropology, economic prehistory

Personnel/Human Resources Management Issues Between 1927-1981: A Replication

This study represents a historical analysis of personnel/human resource topics/issues of the last 55 years. The contents of 6,412 articles published in two journals are categorized and examined Issues that have either dominated the journals or have been neglected are identified, and the importance and origination of these issues are clarified by placing them in a historical context Methodological issues of this analysis are discusse

Crowdboard: Augmenting in-person idea generation with real-time crowds

Online crowds can help infuse creativity into the design process, but traditional strategies for leveraging them, such as large-scale ideation platforms, require time and organizational effort in order to obtain results. We propose a new method for crowd-based ideation that simplifies the process by having smaller crowds join in-person ideators during synchronous creative sessions. Our system Crowdboard allows online crowds to provide real-time creative input during early-stage design activities, such as brainstorming or concept mapping. The system enables in-person ideators to develop ideas on a physical or digital whiteboard which is augmented with real-time creative input from online participants who see and hear a live broadcast of the meeting. We validate Crowdboard via two user studies in which dyads of in-person ideators brainstormed with the help of crowd ideators. Our studies suggest that Crowdboard can effectively enhance ongoing brainstorming sessions, but also revealed key challenges for how to better facilitate interactions among in-person and crowd ideator

Physiology, development, and disease modeling in the Drosophila excretory system

The insect excretory system contains two organ systems acting in concert: the Malpighian tubules and the hindgut perform essential roles in excretion and ionic and osmotic homeostasis. For over 350 years, these two organs have fascinated biologists as a model of organ structure and function. As part of a recent surge in interest, research on the Malpighian tubules and hindgut of Drosophila have uncovered important paradigms of organ physiology and development. Further, many human disease processes can be modeled in these organs. Here, focusing on discoveries in the past 10 years, we provide an overview of the anatomy and physiology of the Drosophila excretory system. We describe the major developmental events that build these organs during embryogenesis, remodel them during metamorphosis, and repair them following injury. Finally, we highlight the use of the Malpighian tubules and hindgut as accessible models of human disease biology. The Malpighian tubule is a particularly excellent model to study rapid fluid transport, neuroendocrine control of renal function, and modeling of numerous human renal conditions such as kidney stones, while the hindgut provides an outstanding model for processes such as the role of cell chirality in development, nonstem cell–based injury repair, cancer-promoting processes, and communication between the intestine and nervous system

Theory of High-Tc Superconductivity: Accurate Predictions of Tc

The superconducting transition temperatures of high-Tc compounds based on copper, iron, ruthenium and certain organic molecules are discovered to be dependent on bond lengths, ionic valences, and Coulomb coupling between electronic bands in adjacent, spatially separated layers [1]. Optimal transition temperature, denoted as T_c0, is given by the universal expression $k_BT_c0 = e^2 \Lambda / \ell\zeta$; $\ell$ is the spacing between interacting charges within the layers, \zeta is the distance between interacting layers and \Lambda is a universal constant, equal to about twice the reduced electron Compton wavelength (suggesting that Compton scattering plays a role in pairing). Non-optimum compounds in which sample degradation is evident typically exhibit Tc < T_c0. For the 31+ optimum compounds tested, the theoretical and experimental T_c0 agree statistically to within +/- 1.4 K. The elemental high Tc building block comprises two adjacent and spatially separated charge layers; the factor e^2/\zeta arises from Coulomb forces between them. The theoretical charge structure representing a room-temperature superconductor is also presented.Comment: 7 pages 5 references, 6 figures 1 tabl

The Coulomb Sum and Proton-Proton Correlations in Few-Body Nuclei

In simple models of the nuclear charge operator, measurements of the Coulomb sum and the charge form factor of a nucleus directly determine the proton-proton correlations. We examine experimental results obtained for few-body nuclei at Bates and Saclay using models of the charge operator that include both one- and two-body terms. Previous analyses using one-body terms only have failed to reproduce experimental results. However, we find that the same operators which have been used to successfully describe the charge form factors also produce substantial agreement with measurements of the Coulomb sum.Comment: 11 pages, Revtex version 3.0 with 3 Postscript figures appended, ANL preprint PHY-7473-TH-9

The Athenian Calendar of Sacrifices: A New Fragment from the Athenian Agora

Presented here is the editio princeps of a new fragment of the late-5th-century b.c. Athenian calendar of sacrifices. The fragment, Agora 17577, was discovered during excavations conducted in the Athenian Agora by the American School of Classical Studies. Inscribed on both faces (Face A: 403-399 b.c., Face B: 410-404 b.c.), it is associated with, but does not join, the group of fragments of Athenian legal inscriptions often referred to as the Law Code of Nikomachos. The text provides important additional evidence for the form of the calendar and the manner of its publication, and casts new light on broader issues of Athenian cult and topography