4,824 research outputs found
Run-Time Selection of Coordination Mechanisms in Multi-Agent Systems
This paper presents a framework that enables autonomous agents to dynamically select the mechanism they employ in order to coordinate their inter-related activities. Adopting this framework means coordination mechanisms move from the realm of being imposed upon the system at design time, to something that the agents select at run-time in order to fit their prevailing circumstances and their current coordination needs. Empirical analysis is used to evaluate the effect of various design alternatives for the agent's decision making mechanisms and for the coordination mechanisms themselves
Lipid-modulated assembly of magnetized iron-filled carbon nanotubes in millimeter-scale structures
Biomolecule-functionalized carbon nanotubes (CNTs) combine the molecular recognition properties of biomaterials with the electrical properties of nanoscale solid state transducers. Application of this hybrid material in bioelectronic devices requires the development of methods for the reproducible self-assembly of CNTs into higher-order structures in an aqueous environment. To this end, we have studied pattern formation of lipid-coated Fe-filled CNTs, with lengths in the 1–5 µm range, by controlled evaporation of aqueous CNT-lipid suspensions. Novel diffusion limited aggregation structures composed of end-to-end oriented nanotubes were observed by optical and atomic force microscopy. Significantly, the lateral dimension of assemblies of magnetized Fe-filled CNTs was in the millimeter range. Control experiments in the absence of lipids and without magnetization indicated that the formation of these long linear nanotube patterns is driven by a subtle interplay between radial flow forces in the evaporating droplet, lipid-modulated van der Waals forces, and magnetic dipole–dipole interactions. Keywords
Lipid Bodies: Inflammatory Organelles Implicated in Host-Trypanosoma cruzi Interplay during Innate Immune Responses
The flagellated protozoa Trypanosoma cruzi is the causal agent of Chagas' disease, a significant public health issue and still a major cause of morbidity and mortality in Latin America. Acute Chagas' disease elicits a strong inflammatory response. In order to control the parasite multiplication, cells of the monocytic lineage are highly mobilized. Monocyte differentiation leads to the formation of phagocytosing macrophages, which are strongly activated and direct host defense. A distinguishing feature of Chagas' disease-triggered macrophages is the presence of increased numbers of distinct cytoplasmic organelles termed lipid bodies or lipid droplets. These organelles are actively formed in response to the parasite and are sites for synthesis and storage of inflammatory mediators. This review covers current knowledge on lipid bodies elicited by the acute Chagas' disease within inflammatory macrophages and discusses the role of these organelles in inflammation. The increased knowledge of lipid bodies in pathogenic mechanisms of infections may not only contribute to the understanding of pathogen-host interactions but may also identify new targets for intervention
Fine Structure Discussion of Parity-Nonconserving Neutron Scattering at Epithermal Energies
The large magnitude and the sign correlation effect in the parity
non-conserving resonant scattering of epithermal neutrons from Th is
discussed in terms of a non-collective local doorway model. General
conclusions are drawn as to the probability of finding large parity violation
effects in other regions of the periodic table.Comment: 6 pages, Tex. CTP# 2296, to appear in Z. Phys.
Dissipative collisions in O + Al at E=116 MeV
The inclusive energy distributions of fragments (3Z7) emitted in
the reaction O + Al at 116 MeV have been measured in
the angular range = 15 - 115. A non-linear
optimisation procedure using multiple Gaussian distribution functions has been
proposed to extract the fusion-fission and deep inelastic components of the
fragment emission from the experimental data. The angular distributions of the
fragments, thus obtained, from the deep inelastic component are found to fall
off faster than those from the fusion-fission component, indicating shorter
life times of the emitting di-nuclear systems. The life times of the
intermediate di-nuclear configurations have been estimated using a diffractive
Regge-pole model. The life times thus extracted (
Sec.) are found to decrease with the increase in the fragment charge. Optimum
Q-values are also found to increase with increasing charge transfer i.e. with
the decrease in fragment charge.Comment: 9 pages, 4 figures, 1 tabl
Growth hormone response to growth hormone-releasing peptide-2 in growth hormone-deficient Little mice
OBJECTIVE: To investigate a possible direct, growth hormone-releasing, hormone-independent action of a growth hormone secretagogue, GHRP-2, in pituitary somatotroph cells in the presence of inactive growth hormonereleasing hormone receptors. MATERIALS AND METHODS: The responses of serum growth hormone to acutely injected growth hormone-releasing P-2 in lit/litmice, which represent a model of GH deficiency arising frommutated growth hormone-releasing hormonereceptors, were compared to those observed in the heterozygous (lit/+) littermates and wild-type (+/+) C57BL/6J mice. RESULTS: After the administration of 10 mcg of growth hormone-releasing P-2 to lit/lit mice, a growth hormone release of 9.3±1.5 ng/ml was observed compared with 1.04±1.15 ng/ml in controls (p<0.001). In comparison, an intermediate growth hormone release of 34.5±9.7 ng/ml and a higher growth hormone release of 163±46 ng/ml were induced in the lit/+ mice and wild-type mice, respectively. Thus, GHRP-2 stimulated growth hormone in the lit/lit mice, and the release of growth hormone in vivo may be only partially dependent on growth hormone-releasing hormone. Additionally, the plasma leptin and ghrelin levels were evaluated in the lit/lit mice under basal and stimulated conditions. CONCLUSIONS: Here, we have demonstrated that lit/lit mice, which harbor a germline mutation in the Growth hormone-releasing hormone gene, maintain a limited but statistically significant growth hormone elevation after exogenous stimulation with GHRP-2. The present data probably reflect a direct, growth hormone-independent effect on Growth hormone S (ghrelin) stimulation in the remaining pituitary somatotrophs of little mice that is mediated by growth hormone S-R 1a
Time Evolution of tunneling and decoherence: soluble model
Decoherence effects associated to the damping of a tunneling two-level system
are shown to dominate the tunneling probability at short times in strong
coupling regimes in the context of a soluble model. A general decomposition of
tunneling rates in dissipative and unitary parts is implemented. Master
equation treatments fail to describe the model system correctly when more than
a single relaxation time is involved
The RoPES project with HARPS and HARPS-N. I. A system of super-Earths orbiting the moderately active K-dwarf HD 176986
We report the discovery of a system of two super-Earths orbiting the
moderately active K-dwarf HD 176986. This work is part of the RoPES RV program
of G- and K-type stars, which combines radial velocities (RVs) from the HARPS
and HARPS-N spectrographs to search for short-period terrestrial planets. HD
176986 b and c are super-Earth planets with masses of 5.74 and 9.18
M, orbital periods of 6.49 and 16.82 days, and distances of 0.063
and 0.119 AU in orbits that are consistent with circular. The host star is a
K2.5 dwarf, and despite its modest level of chromospheric activity (log(R'hk) =
- 4.90 +- 0.04), it shows a complex activity pattern. Along with the discovery
of the planets, we study the magnetic cycle and rotation of the star. HD 176986
proves to be suitable for testing the available RV analysis technique and
further our understanding of stellar activity.Comment: 21 pages, 24 figures, 7 table
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