8,402 research outputs found
Scale-freeness for networks as a degenerate ground state: A Hamiltonian formulation
The origin of scale-free degree distributions in the context of networks is
addressed through an analogous non-network model in which the node degree
corresponds to the number of balls in a box and the rewiring of links to balls
moving between the boxes. A statistical mechanical formulation is presented and
the corresponding Hamiltonian is derived. The energy, the entropy, as well as
the degree distribution and its fluctuations are investigated at various
temperatures. The scale-free distribution is shown to correspond to the
degenerate ground state, which has small fluctuations in the degree
distribution and yet a large entropy. We suggest an implication of our results
from the viewpoint of the stability in evolution of networks.Comment: 7 pages, 3 figures. To appear in Europhysics lette
Lessons for Ukraine: how the international radiation therapy community can respond and support both now and in the future
Focusing in Asynchronous Games
Game semantics provides an interactive point of view on proofs, which enables
one to describe precisely their dynamical behavior during cut elimination, by
considering formulas as games on which proofs induce strategies. We are
specifically interested here in relating two such semantics of linear logic, of
very different flavor, which both take in account concurrent features of the
proofs: asynchronous games and concurrent games. Interestingly, we show that
associating a concurrent strategy to an asynchronous strategy can be seen as a
semantical counterpart of the focusing property of linear logic
Kinematic mental simulations in abduction and deduction
We present a theory, and its computer implementation, of how mental simulations underlie the abductions of informal algorithms and deductions from these algorithms. Three experiments tested the theory’s predictions, using an environment of a single railway track and a siding. This environment is akin to a universal Turing machine, but it is simple enough for nonprogrammers to use. Participants solved problems that required use of the siding to rearrange the order of cars in a train (experiment 1). Participants abduced and described in their own words algorithms that solved such problems for trains of any length, and, as the use of simulation predicts, they favored “while-loops” over “for-loops” in their descriptions (experiment 2). Given descriptions of loops of procedures, participants deduced the consequences for given trains of six cars, doing so without access to the railway environment (experiment 3). As the theory predicts, difficulty in rearranging trains depends on the numbers of moves and cars to be moved, whereas in formulating an algorithm and deducing its consequences, it depends on the Kolmogorov complexity of the algorithm. Overall, the results corroborated the use of a kinematic mental model in creating and testing informal algorithms and showed that individuals differ reliably in the ability to carry out these tasks
Cognitively-inspired Agent-based Service Composition for Mobile & Pervasive Computing
Automatic service composition in mobile and pervasive computing faces many
challenges due to the complex and highly dynamic nature of the environment.
Common approaches consider service composition as a decision problem whose
solution is usually addressed from optimization perspectives which are not
feasible in practice due to the intractability of the problem, limited
computational resources of smart devices, service host's mobility, and time
constraints to tailor composition plans. Thus, our main contribution is the
development of a cognitively-inspired agent-based service composition model
focused on bounded rationality rather than optimality, which allows the system
to compensate for limited resources by selectively filtering out continuous
streams of data. Our approach exhibits features such as distributedness,
modularity, emergent global functionality, and robustness, which endow it with
capabilities to perform decentralized service composition by orchestrating
manifold service providers and conflicting goals from multiple users. The
evaluation of our approach shows promising results when compared against
state-of-the-art service composition models.Comment: This paper will appear on AIMS'19 (International Conference on
Artificial Intelligence and Mobile Services) on June 2
Artificial Brains and Hybrid Minds
The paper develops two related thought experiments exploring variations on an ‘animat’ theme. Animats are hybrid devices with both artificial and biological components. Traditionally, ‘components’ have been construed in concrete terms, as physical parts or constituent material structures. Many fascinating issues arise within this context of hybrid physical organization. However, within the context of functional/computational theories of mentality, demarcations based purely on material structure are unduly narrow. It is abstract functional structure which does the key work in characterizing the respective ‘components’ of thinking systems, while the ‘stuff’ of material implementation is of secondary importance. Thus the paper extends the received animat paradigm, and investigates some intriguing consequences of expanding the conception of bio-machine hybrids to include abstract functional and semantic structure. In particular, the thought experiments consider cases of mind-machine merger where there is no physical Brain-Machine Interface: indeed, the material human body and brain have been removed from the picture altogether. The first experiment illustrates some intrinsic theoretical difficulties in attempting to replicate the human mind in an alternative material medium, while the second reveals some deep conceptual problems in attempting to create a form of truly Artificial General Intelligence
Repeated Restraint and Sampling Results in Reduced Corticosterone Levels in Developing and Adult Captive American Kestrels (Falco sparverius)
Presents a study which evaluated the effects of repeated restraint on the ability of postnatally developing chicks and adults to respond to a repeated standardized stressor of capture and handling in a semialtricial raptorial species, the American kestrel. Blood sampling and general procedure; Corticosterone radioimmunoassay analysis; Corticosterone levels in postnatally developing chicks and adults
Repeated Restraint and Sampling Results in Reduced Corticosterone Levels in Developing and Adult Captive American Kestrels (Falco sparverius)
Dense Molecular Gas In A Young Cluster Around MWC 1080 -- Rule Of The Massive Star
We present CS , CO , and CO , observations with the 10-element Berkeley Illinois Maryland Association
(BIMA) Array toward the young cluster around the Be star MWC 1080. These
observations reveal a biconical outflow cavity with size 0.3 and 0.05 pc
for the semimajor and semiminor axis and 45\arcdeg position angle.
These transitions trace the dense gas, which is likely the swept-up gas of the
outflow cavity, rather than the remaining natal gas or the outflow gas. The gas
is clumpy; thirty-two clumps are identified. The identified clumps are
approximately gravitationally bound and consistent with a standard isothermal
sphere density, which suggests that they are likely collapsing protostellar
cores. The gas kinematics suggests that there exists velocity gradients
implying effects from the inclination of the cavity and MWC 1080. The
kinematics of dense gas has also been affected by either outflows or stellar
winds from MWC 1080, and lower-mass clumps are possibly under stronger effects
from MWC 1080 than higher-mass clumps. In addition, low-mass cluster members
tend to be formed in the denser and more turbulent cores, compared to isolated
low-mass star-forming cores. This results from contributions of nearby forming
massive stars, such as outflows or stellar winds. Therefore, we conclude that
in clusters like the MWC 1080 system, effects from massive stars dominate the
star-forming environment in both the kinematics and dynamics of the natal cloud
and the formation of low-mass cluster members. This study provides insights
into the effects of MWC 1080 on its natal cloud, and suggests a different
low-mass star forming environment in clusters compared to isolated star
formation.Comment: 42 pages, 5 tables, and 13 figures, accepted for publication in Ap
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