3,800 research outputs found
The origins of intensive marine fishing in medieval Europe: the English evidence
The catastrophic impact of fishing pressure on species such as cod and herring is well documented. However, the antiquity of their intensive exploitation has not been established. Systematic catch statistics are only available for ca. 100 years, but large-scale fishing industries existed in medieval Europe and the expansion of cod fishing from the fourteenth century (first in Iceland, then in Newfoundland) played an important role in the European colonization of the Northwest Atlantic. History has demonstrated the scale of these late medieval and post-medieval fisheries, but only archaeology can illuminate earlier practices. Zooarchaeological evidence shows that the clearest changes in marine fishing in England between AD 600 and 1600 occurred rapidly around AD 1000 and involved large increases in catches of herring and cod. Surprisingly, this revolution predated the documented post-medieval expansion of England's sea fisheries and coincided with the Medieval Warm Period-when natural herring and cod productivity was probably low in the North Sea. This counterintuitive discovery can be explained by the concurrent rise of urbanism and human impacts on freshwater ecosystems. The search for 'pristine' baselines regarding marine ecosystems will thus need to employ medieval palaeoecological proxies in addition to recent fisheries data and early modern historical records
AlN-based piezoelectric micropower generator for low ambient vibration energy harvesting
AbstractIn this paper a resonant micropower generator based on the transverse piezoelectric effect is presented. The generator consists of a large silicon mass attached to an polysilicon cantilever covered with an AlN thinfilm as piezoelectric material. To maximize the power density of the generator, a parametric study by means of analytical modeling and FEM simulation has been performed. Different optimized generators with resonance frequencies in the range from 100Hz up to 1kHz have been designed and fabricated, using dedicated MEMS technology processes. First unpackaged prototypes showed a quality factor of about 500 under atmospheric pressure and were able to generate an electrical output power of up to 1.9μW at an external acceleration of 1.6 m/s2
A European Turn in Early American History? A Discussion of Evan Haefeli's Accidental Pluralism: America and the Religious Politics of English Expansion, 1497-1662
From the nineteenth century onwards, Americans have naturalized their colonial origins into a consensual nationalist history, emphasizing America’s perceived role as a refuge for the persecuted, while smoothing out a myriad of complexities in the process. Evan Haefeli attempts to overturn the assumptions underpinning this narrative and is convinced that many important aspects of early America need to be understood within a broader European context. In Accidental Pluralism, he argues that the collapse of religious unity in England lies at the root of the emergence of pluralism in colonial America, in which he includes Canada and the Caribbean. Relationships among states, churches, and publics were contested from the earliest decades of colonization and created a pluralistic religious landscape that no one had anticipated. The four reviewers are fulsome in their praise, calling it an impressive, important, powerful, and sweeping book that few scholars could have written. The reviewers also raise questions, for instance by problematizing the incorporation of the colonial American dimension into early British history, criticizing the validity of the chosen end date, and questioning his definitions of diversity, pluralism, and religious toleration. In his response Evan Haefeli takes the opportunity to reflect on what drove him to write the book and to organize it in this way. He acknowledges that connecting early American history with its broader European context was more difficult than it should have been, as the dominant questions in the two historiographies are an ocean apart. While the argument of the book is aimed at early Americanists, Haefeli is grateful that the reviewers situate the story he tells within the broader early modern European history of toleration
Studies of multiplicity in relativistic heavy-ion collisions
In this talk I'll review the present status of charged particle multiplicity
measurements from heavy-ion collisions. The characteristic features of
multiplicity distributions obtained in Au+Au collisions will be discussed in
terms of collision centrality and energy and compared to those of p+p
collisions. Multiplicity measurements of d+Au collisions at 200 GeV
nucleon-nucleon center-of-mass energy will also be discussed. The results will
be compared to various theoretical models and simple scaling properties of the
data will be identified.Comment: "Focus on Multiplicity" Internationsl Workshop on Particle
Multiplicity in Relativistic Heavy Ion Collisions, Bari, Italy, June 17-19,
2003, 16 pages, 15 figure
Jet Energy Density in Hadron-Hadron Collisions at High Energies
The average particle multiplicity density dN/deta is the dynamical quantity
which reflects some regularities of particle production in low-pT range. The
quantity is an important ingredient of z-scaling. Experimental results on
charged particle density are available for pp, pA and AA collisions while
experimental properties of the jet density are still an open question. The goal
of this work is to find the variable which will reflect the main features of
the jet production in low transverse energy range and play the role of the
scale factor for the scaling function psi(z) and variable z in data
z-presentation. The appropriate candidate is the variable we called "scaled jet
energy density". Scaled jet energy density is the probability to have a jet
with defined ET in defined xT and pseudorapidity regions. The PYTHIA6.2 Monte
Carlo generator is used for calculation of scaled jet energy density in
proton-proton collisions over a high energy range (sqrt s = 200-14000 GeV) and
at eta = 0. The properties of the new variable are discussed and sensitivity to
"physical scenarios" applied in the standard Monte Carlo generator is noted.
The results of scaled jet energy density at LHC energies are presented and
compared with predictions based on z-scaling.Comment: 11 pages, LaTeX, 8 figures, Presented at the XVII International
Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics
& Quantum Chromodynamics", Dubna, Russia, September 27 - October 2, 200
Global Observations from PHOBOS
Particle production in Au+Au collisions has been measured in the PHOBOS
experiment at RHIC for a range of collision energies. Three empirical
observations have emerged from this dataset which require theoretical
examination. First, there is clear evidence of limiting fragmentation. Namely,
particle production in central Au+Au collisions, when expressed as
(), becomes energy independent at high energy for a
broad region of around . This energy-independent region grows
with energy, allowing only a limited region (if any) of longitudinal
boost-invariance. Second, there is a striking similarity between particle
production in e+e- and Au+Au collisions (scaled by the number of participating
nucleon pairs). Both the total number of produced particles and the
longitudinal distribution of produced particles are approximately the same in
e+e- and in scaled Au+Au. This observation was not predicted and has not been
explained. Finally, particle production has been found to scale approximately
with the number of participating nucleon pairs for . This scaling
occurs both for the total multiplicity and for high \pT particles (3 <\pT<
4.5 GeV/c).Comment: QM2002 plenary talk, 10 pages, 11 figure
Charged particle densities from Au+Au collisions at sqrt{s_{NN}}=130 GeV
We present charged particle densities as a function of pseudorapidity and
collision centrality for the 197Au+197Au reaction at sqrt{s_{NN}}=130 GeV. An
integral charged particle multiplicity of 3860+/-300 is found for the 5% most
central events within the pseudorapidity range -4.7 <= eta <= 4.7. At
mid-rapidity an enhancement in the particle yields per participant nucleon pair
is observed for central events. Near to the beam rapidity, a scaling of the
particle yields consistent with the ``limiting fragmentation'' picture is
observed. Our results are compared to other recent experimental and theoretical
discussions of charged particle densities in ultra-relativistic heavy-ion
collisions.Comment: 14 pages, 4 figures; to be published in Phys. Lett.
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