1,509 research outputs found
Positive Design: Using Design Thinking as a Creative Process for Enhancing Project Outcomes
This PDW brings together scholars and practitioners working on creativity, design thinking and strategy to explore, debate, and illustrate the ways in which design thinking is being used as a creative process to positively impact people as the beneficiaries and stakeholders of projects. The PDW is the first of a series of PDWs to be proposed at AOM over the next three years seeking to bring the design thinking and positive organizational scholarship communities together to advance knowledge, theorizing and research on how design thinking can impact projects to improve society and have a positive and sustainable impact on people, planet and profit. The workshop will be an interactive, design thinking led session and will produce micro-projects to advance the ‘positive design’ cause within the academy. This session will also be supported by the Project Management Institute (PMI) and will seek to broaden and build networks across AOM, SMS and PMI to advance creative approaches to project design with a focus on beneficiaries and stakeholders
A k-shell decomposition method for weighted networks
We present a generalized method for calculating the k-shell structure of
weighted networks. The method takes into account both the weight and the degree
of a network, in such a way that in the absence of weights we resume the shell
structure obtained by the classic k-shell decomposition. In the presence of
weights, we show that the method is able to partition the network in a more
refined way, without the need of any arbitrary threshold on the weight values.
Furthermore, by simulating spreading processes using the
susceptible-infectious-recovered model in four different weighted real-world
networks, we show that the weighted k-shell decomposition method ranks the
nodes more accurately, by placing nodes with higher spreading potential into
shells closer to the core. In addition, we demonstrate our new method on a real
economic network and show that the core calculated using the weighted k-shell
method is more meaningful from an economic perspective when compared with the
unweighted one.Comment: 17 pages, 6 figure
Critical conductance of two-dimensional chiral systems with random magnetic flux
The zero temperature transport properties of two-dimensional lattice systems
with static random magnetic flux per plaquette and zero mean are investigated
numerically. We study the two-terminal conductance and its dependence on
energy, sample size, and magnetic flux strength. The influence of boundary
conditions and of the oddness of the number of sites in the transverse
direction is also studied. We confirm the existence of a critical chiral state
in the middle of the energy band and calculate the critical exponent nu=0.35
+/- 0.03 for the divergence of the localization length. The sample averaged
scale independent critical conductance _c turns out to be a function of the
amplitude of the flux fluctuations whereas the variance of the respective
conductance distributions appears to be universal. All electronic states
outside of the band center are found to be localized.Comment: to appear in Phys. Rev.
Transverse momentum dependent distribution functions in a covariant parton model approach with quark orbital motion
Transverse parton momentum dependent distribution functions (TMDs) of the
nucleon are studied in a covariant model, which describes the intrinsic motion
of partons in terms of a covariant momentum distribution. The consistency of
the approach is demonstrated, and model relations among TMDs are studied. As a
byproduct it is shown how the approach allows to formulate the non-relativistic
limit.Comment: 16 page
Statistical Mechanics of Canonical-Dissipative Systems and Applications to Swarm Dynamics
We develop the theory of canonical-dissipative systems, based on the
assumption that both the conservative and the dissipative elements of the
dynamics are determined by invariants of motion. In this case, known solutions
for conservative systems can be used for an extension of the dynamics, which
also includes elements such as the take-up/dissipation of energy. This way, a
rather complex dynamics can be mapped to an analytically tractable model, while
still covering important features of non-equilibrium systems. In our paper,
this approach is used to derive a rather general swarm model that considers (a)
the energetic conditions of swarming, i.e. for active motion, (b) interactions
between the particles based on global couplings. We derive analytical
expressions for the non-equilibrium velocity distribution and the mean squared
displacement of the swarm. Further, we investigate the influence of different
global couplings on the overall behavior of the swarm by means of
particle-based computer simulations and compare them with the analytical
estimations.Comment: 14 pages incl. 13 figures. v2: misprints in Eq. (40) corrected, ref.
updated. For related work see also:
http://summa.physik.hu-berlin.de/~frank/active.htm
Semiquantitative Assessment of Bowel Habits and Its Relation with Calcium Metabolism after Gastric Bypass Surgery: A Retrospective Study
Background. Calcium malabsorption after bariatric surgery may be harmful to skeletal health and demands for optimal skeletal management. Methods. 103 Patients were evaluated retrospectively at 12 months after surgery. The evaluation included a questionnaire about stool frequency and consistency and laboratory assessments. Results. 103 Patients, 27 males and 76 females, were included in the study. 83 Patients had an alimentary limb of 100 cm and 20 patients one of 150 cm. At 12 months after surgery, 77.7% reported changes of bowel habits, albumin adjusted calcium levels were normal in all but 2 patients, and PTH levels were increased in 35%. Correlations between semiquantified bowel scores (fecal scores) and data from the laboratory demonstrated increasing PTH values along with more frequent and softer/watery stools (RR 30.5, CI 6.2–149.2, P < .001). There was a trend for higher PTH levels in patients with an alimentary limb of 150 cm. Normal PTH levels were more frequently found in case of calcium and vitamin D3 use (RR 14.3, CI 3.6–56.5, P < .001). Conclusion. This study demonstrates interrelationships between semi-quantified fecal scores, PTH levels, and the compliance of taking calcium/vitamin D3 suppletion. However, prospective randomized studies are necessary to show causal relationships
Anomalous Normal-State Properties of High-T Superconductors -- Intrinsic Properties of Strongly Correlated Electron Systems?
A systematic study of optical and transport properties of the Hubbard model,
based on Metzner and Vollhardt's dynamical mean-field approximation, is
reviewed. This model shows interesting anomalous properties that are, in our
opinion, ubiquitous to single-band strongly correlated systems (for all spatial
dimensions greater than one), and also compare qualitatively with many
anomalous transport features of the high-T cuprates. This anomalous
behavior of the normal-state properties is traced to a ``collective single-band
Kondo effect,'' in which a quasiparticle resonance forms at the Fermi level as
the temperature is lowered, ultimately yielding a strongly renormalized Fermi
liquid at zero temperature.Comment: 27 pages, latex, 13 figures, Invited for publication in Advances in
Physic
Hokupa'a-Gemini Discovery of Two Ultracool Companions to the Young Star HD 130948
We report the discovery of two faint ultracool companions to the nearby
(d~17.9 pc) young G2V star HD 130948 (HR 5534, HIP 72567) using the Hokupa'a
adaptive optics instrument mounted on the Gemini North 8-meter telescope. Both
objects have the same common proper motion as the primary star as seen over a 7
month baseline and have near-IR photometric colors that are consistent with an
early-L classification. Near-IR spectra taken with the NIRSPEC AO instrument on
the Keck II telescope reveal K I lines, FeH, and water bandheads. Based on
these spectra, we determine that both objects have spectral type dL2 with an
uncertainty of 2 spectral subclasses. The position of the new companions on the
H-R diagram in comparison with theoretical models is consistent with the young
age of the primary star (<0.8 Gyr) estimated on the basis of X-ray activity,
lithium abundance and fast rotation. HD 130948 B and C likely constitute a pair
of young contracting brown dwarfs with an orbital period of about 10 years, and
will yield dynamical masses for L dwarfs in the near future.Comment: 10 pages, 3 figures, (13 total pages
Evolutionary History and Novel Biotic Interactions Determine Plant Responses to Elevated CO2 and Nitrogen Fertilization
A major frontier in global change research is predicting how multiple agents of global change will alter plant productivity, a critical component of the carbon cycle. Recent research has shown that plant responses to climate change are phylogenetically conserved such that species within some lineages are more productive than those within other lineages in changing environments. However, it remains unclear how phylogenetic patterns in plant responses to changing abiotic conditions may be altered by another agent of global change, the introduction of non-native species. Using a system of 28 native Tasmanian Eucalyptus species belonging to two subgenera, Symphyomyrtus and Eucalyptus, we hypothesized that productivity responses to abiotic agents of global change (elevated CO2 and increased soil N) are unique to lineages, but that novel interactions with a nonnative species mediate these responses. We tested this hypothesis by examining productivity of 1) native species monocultures and 2) mixtures of native species with an introduced hardwood plantation species, Eucalyptus nitens, to experimentally manipulated soil N and atmospheric CO2. Consistent with past research, we found that N limits productivity overall, especially in elevated CO2 conditions. However, monocultures of species within the Symphyomyrtus subgenus showed the strongest response to N (gained 127% more total biomass) in elevated CO2 conditions, whereas those within the Eucalyptus subgenus did not respond to N. Root:shoot ratio (an indicator of resource use) was on average greater in species pairs containing Symphyomyrtus species, suggesting that functional traits important for resource uptake are phylogenetically conserved and explaining the phylogenetic pattern in plant response to changing environmental conditions. Yet, native species mixtures with E. nitens exhibited responses to CO2 and N that differed from those of monocultures, supporting our hypothesis and highlighting that both plant evolutionary history and introduced species will shape community productivity in a changing world
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