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Human knowing and perceived complexity: implications for systems practice
Complexity has been understood in different ways since its (re) introduction into scientific discourse. Therefore, instead of proposing a definition of complexity, we group the existing explanations about it into two distinct categories: descriptive and perceived complexity. The main features of these categories are described and how they arise as the result of the adoption of contrasting epistemologies is discussed. These categories together with their implications for our doing in the world are explored under the rubric of the 'epistemological problem of complexity'. The practical significance of the issues we address, especially as they relate to building capacity for systems practice, understood as a way of managing in situations of complexity, is also of concern. "Even when the individual trees are highly interesting and picturesque, it has use to see what the forest looks like in the large" (Rescher, 199S; xvii)
Application of the Two-Scale Model to the HERMES Data on Nuclear Attenuation
The Two-Scale Model and its improved version were used to perform the fit to
the HERMES data for (the virtual photon energy) and z (the fraction of
carried by hadron) dependencies of nuclear multiplicity ratios for
and mesons electro-produced on two nuclear targets (N
and Kr). The quantitative criterium was used for the first
time to analyse the results of the model fit to the nuclear multiplicity ratios
data. The two-parameter's fit gives satisfactory agreement with the HERMES
data. Best values of the parameters were then used to calculate the - and
- dependencies of nuclear attenuation for , K, K and
produced on Kr target, and also make a predictions for ,
z and the Q (the photon virtuality) - dependencies of nuclear attenuation
data for those identified hadrons and nuclea, that will be published by HERMES
The Value of STEM as an Educational Tool for Enhancing Cognitive Development
STEM is an acronym for Science, Technology, Engineering, and Math. The focus of STEM education is to provide a holistic approach through hands-on, problem-based learning where students are able to take what they learn in the classroom and apply it to real world problems.https://digital.sandiego.edu/npi-sdclimate/1034/thumbnail.jp
Uncertainty and Risk in Financial Markets
This paper considers a general equilibrium model in which the=20 distinction between un-certainty and risk is formalized by assuming agents= =20 have incomplete preferences over state-contingent consumption bundles, as=20 in Bewley (1986). Without completeness, individual decision making depends= =20 on a set of probability distributions over the state space. A bundle is=20 preferred to another if and only if it has larger expected utility for all= =20 probabilities in this set. When preferences are complete this set is a=20 singleton, and the model reduces to standard expected utility. In this=20 setting, we characterize Pareto optima and equilibria, and show that the=20 presence of uncertainty generates robust indeterminacies in equilibrium=20 prices and allocations for any speci=AFcation of initial endowments. We=20 derive comparative statics results linking the degree of uncertainty with=20 changes in equilibria. Despite the presence of robust indeterminacies, we=20 show that equilibrium prices and allocations vary continuously with=20 underlying fundamentals. Equilibria in a standard risk economy are thus=20 robust to adding small degrees of uncertainty. Finally, we give conditions= =20 under which some assets are not traded due to uncertainty aversion.
High-contrast dark resonance on the D2 - line of 87Rb in a vapor cell with different directions of the pump - probe waves
We propose a novel method enabling to create a high-contrast dark resonance
in the 87Rb vapor D2-line. The method is based on an optical pumping of atoms
into the working states by a two-frequency, linearly-polarized laser radiation
propagating perpendicularly to the probe field. This new scheme is compared to
the traditional scheme involving the circularly-polarized probe beam only, and
significant improvement of the dark resonance parameters is found. Qualitative
considerations are confirmed by numerical calculations.Comment: 7 pages, 4 figure
On different -systems in nonextensive thermostatistics
It is known that the nonextensive statistics was originally formulated for
the systems composed of subsystems having same . In this paper, the
existence of composite system with different subsystems is investigated by
fitting the power law degree distribution of air networks with -exponential
distribution. Then a possible extension the nonextensive statistics to
different systems is provided on the basis of an entropy nonadditivity rule
and an unnormalized expectation of energy.Comment: 17 pages, 4 figures, will be published in Euro. Phys. J. B (2006
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV
We report the first measurement of charged particle elliptic flow in Pb-Pb
collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron
Collider. The measurement is performed in the central pseudorapidity region
(||<0.8) and transverse momentum range 0.2< < 5.0 GeV/. The
elliptic flow signal v, measured using the 4-particle correlation method,
averaged over transverse momentum and pseudorapidity is 0.087 0.002
(stat) 0.004 (syst) in the 40-50% centrality class. The differential
elliptic flow v reaches a maximum of 0.2 near = 3
GeV/. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow
increases by about 30%. Some hydrodynamic model predictions which include
viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/389
Strange particle production in proton-proton collisions at TeV with ALICE at the LHC
The production of mesons containing strange quarks (K, ) and both
singly and doubly strange baryons (, Anti-, and
+Anti-) are measured at central rapidity in pp collisions at
= 0.9 TeV with the ALICE experiment at the LHC. The results are
obtained from the analysis of about 250 k minimum bias events recorded in 2009.
Measurements of yields (dN/dy) and transverse momentum spectra at central
rapidities for inelastic pp collisions are presented. For mesons, we report
yields () of 0.184 0.002 stat. 0.006 syst. for K and
0.021 0.004 stat. 0.003 syst. for . For baryons, we find
= 0.048 0.001 stat. 0.004 syst. for , 0.047
0.002 stat. 0.005 syst. for Anti- and 0.0101 0.0020 stat.
0.0009 syst. for +Anti-. The results are also compared with
predictions for identified particle spectra from QCD-inspired models and
provide a baseline for comparisons with both future pp measurements at higher
energies and heavy-ion collisions.Comment: 33 pages, 21 captioned figures, 10 tables, authors from page 28,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/387
Dihadron fragmentation: in vacuum and in matter
Two particle correlations within a single jet produced in deeply inelastic
scattering (DIS) off a large nucleus as well as in heavy-ion collisions are
explored. This is performed within the framework of the medium modified
dihadron fragmentation functions. The modification occurs due to gluon
bremsstrahlung induced by multiple scattering. The modified fragmentation
functions for dihadrons are found to follow closely that of single hadrons
leading to a weak nuclear suppression of their ratios as measured by HERMES in
DIS experiments. Meanwhile, a moderate medium enhancement of the near-side
correlation of two high hadrons is found in central heavy-ion collisions,
partially due to trigger bias caused by the competition between parton energy
loss and the initial Cronin effect.Comment: 4 pages, 2 figures, LATEX, talk given at Hard Probes 200
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