Solving the potential field local minimum problem using internal agent states

We propose a new, extended artificial potential field method, which uses dynamic internal agent states. The internal states are modelled as a dynamical system of coupled first order differential equations that manipulate the potential field in which the agent is situated. The internal state dynamics are forced by the interaction of the agent with the external environment. Local equilibria in the potential field are then manipulated by the internal states and transformed from stable equilibria to unstable equilibria, allowiong escape from local minima in the potential field. This new methodology successfully solves reactive path planning problems, such as a complex maze with multiple local minima, which cannot be solved using conventional static potential fields

Swarm robot social potential fields with internal agent dynamics

Swarm robotics is a new and promising approach to the design and control of multiagent robotic systems. In this paper we use a model for a second order non-linear system of self-propelled agents interacting via pair-wise attractive and repulsive potentials. We propose a new potential field method using dynamic agent internal states to successfully solve a reactive path-planning problem. The path planning problem cannot be solved using static potential fields due to local minima formation, but can be solved by allowing the agent internal states to manipulate the potential field. Simulation results demonstrate the ability of a single agent to perform reactive problem solving effectively, as well as the ability of a swarm of agents to perform problem solving using the collective behaviour of the entire swarm

Wall following to escape local minima for swarms of agents using internal states and emergent behaviour

Natural examples of emergent behaviour, in groups due to interactions among the group's individuals, are numerous. Our aim, in this paper, is to use complex emergent behaviour among agents that interact via pair-wise attractive and repulsive potentials, to solve the local minima problem in the artificial potential based navigation method. We present a modified potential field based path planning algorithm, which uses agent internal states and swarm emergent behaviour to enhance group performance. The algorithm is used successfully to solve a reactive path-planning problem that cannot be solved using conventional static potential fields due to local minima formation. Simulation results demonstrate the ability of a swarm of agents to perform problem solving using the dynamic internal states of the agents along with emergent behaviour of the entire group

On the AA-spectrum for AA-bounded operator on von-Neumann algebra

Let $\mathfrak{M}$ be a von Neumann algebra and let $A$ be a nonzero positive element of $\mathfrak{M}$. By $\sigma_A(T)$ and $r_A(T)$ we denote the $A$-spectrum and the $A$-spectral radius of $T\in\mathfrak{M}^A$, respectively. In this paper, we show that $\sigma(PTP, P\mathfrak{M} P)\subseteq \sigma_A(T)$. Sufficient conditions for the equality $\sigma_A(T)=\sigma(PTP, P\mathfrak{M} P)$ to be true are presented. Also, we show that $\sigma_A(T)$ is finite for any $T\in\mathfrak{M}^A$ if and only if $A$ is in the socle of $\mathfrak{M}$. Next , we consider the relationship between elements $S$ and $T\in\mathfrak{M}^A$ that satisfy one of the following two conditions: (1) $\sigma_A(SX)=\sigma_A(TX)$ for all $X\in\mathfrak{M}^A$, (2) $r_A(SX)= r_A(TX)$ for all $X\in\mathfrak{M}^A$. Finally, a Gleason-Kahane-\.Zelazko's theorem for the $A$-spectrum is derived.% Finally, we introduce and study the notion of the $A$-approximate point spectrum for element of $X\in\mathfrak{M}^A$

HARNESSING THE ANTIOXIDANT PROPERTY OF CERIUM AND YTTRIUM OXIDE NANOPARTICLES TO ENHANCE MESENCHYMAL STEM CELL PROLIFERATION

Objective: This work was designed to explore if cerium oxide (CeO2) and yttrium oxide (Y2O3) nanoparticles as antioxidant agents could potentiate the proliferation of mesenchymal stem cells (MSCs) derived from human dental pulp (hDPSCs).Methods: Nanoparticles were characterized by transmission electron microscopy, particle size and zeta potential, X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscope (SEM) along with energy-dispersive X-ray spectrometry. Furthermore, MSCs were isolated from human dental pulp, propagated and characterized by flow cytometry. Thereafter, the proliferative impact of the suggested nanoparticles on hDPSCs was investigated by 3-(4,5)-dimethylthiazol)-2,5-diphenyl tetrazolium bromide assay.Results: Different sizes (14.09–26.50 nm and 18.80–31.31 nm) for CeO2 and Y2O3 respectively, morphology, charges, and proliferative efficacy in hDPSCs were recorded for both nanoparticles.Conclusion: Generally speaking, the tested nanoparticles heightened the proliferative response of hDPSCs with the most prominent effect exerted by 15 μg/ml of CeO2 and 5 μg/ml of Y2O3. It is reasonable to assume that the antioxidant property of CeO2 and Y2O3 be involved in strengthening the proliferation process of hDPSCs

Influence of Plant Growth Regulators on Somatic Embryogenesis Induction in Seriphidium herba-album

Seriphidium herba-album (syn. Artemisia herba-alba) is a medicinal, aromatic, greenish-silver herb. It is used widely in folk medicine for treatment of diarrhea, abdominal cramps and in the healing of external wounds. It's also used for the treatment of diabetes mellitus, neurological disorders as epilepsy, Alzheimer's disease, depression and jaundice. In this study we assessed the protocol for callus induction, maturation of somatic embryogenesis, frequency of germination and conversion into plantlets for leaf explants of Seriphidium herba-album using different concentrations of PGRs. Highest induction frequencies of embryogenic calli occurred after 35 days on MS medium supplemented with 1.5 mg L-1 2,4-D and 0.5 mg L-1 BAP. Optimum MS medium for higher frequency of matured somatic embryos was recorded using 5.0 mg L-1 BAP and 0.5 mg L-1 NAA and somatic embryos also induced young in vitro grown plantlets when cultured in the medium containing GA3 and kinetin. Hence, attempts to induce direct somatic embryogenesis have been achieved up to embryo regeneration and maturation

Sorting by reversals, block interchanges, tandem duplications, and deletions

<p>Abstract</p> <p>Background</p> <p>Finding sequences of evolutionary operations that transform one genome into another is a classic problem in comparative genomics. While most of the genome rearrangement algorithms assume that there is exactly one copy of each gene in both genomes, this does not reflect the biological reality very well – most of the studied genomes contain duplicated gene content, which has to be removed before applying those algorithms. However, dealing with unequal gene content is a very challenging task, and only few algorithms allow operations like duplications and deletions. Almost all of these algorithms restrict these operations to have a fixed size.</p> <p>Results</p> <p>In this paper, we present a heuristic algorithm to sort an ancestral genome (with unique gene content) into a genome of a descendant (with arbitrary gene content) by reversals, block interchanges, tandem duplications, and deletions, where tandem duplications and deletions are of arbitrary size.</p> <p>Conclusion</p> <p>Experimental results show that our algorithm finds sorting sequences that are close to an optimal sorting sequence when the ancestor and the descendant are closely related. The quality of the results decreases when the genomes get more diverged or the genome size increases. Nevertheless, the calculated distances give a good approximation of the true evolutionary distances.</p

Human Transgene-Free Amniotic-Fluid-Derived Induced Pluripotent Stem Cells for Autologous Cell Therapy

The establishment of a reliable prenatal source of autologous, transgene-free progenitor cells has enormous potential in the development of regenerative-medicine-based therapies for infants born with devastating birth defects. Here, we show that a largely CD117-negative population of human amniotic fluid mesenchymal stromal cells (AF-MSCs) obtained from fetuses with or without prenatally diagnosed anomalies are readily abundant and have limited baseline differentiation potential when compared with bone-marrow-derived MSCs and other somatic cell types. Nonetheless, the AF-MSCs could be easily reprogrammed into induced pluripotent stem cells (iPSCs) using nonintegrating Sendai viral vectors encoding for OCT4, SOX2, KLF4, and cMYC. The iPSCs were virtually indistinguishable from human embryonic stem cells in multiple assays and could be used to generate a relatively homogeneous population of neural progenitors, expressing PAX6, SOX2, SOX3, Musashi-1, and PSA-NCAM, for potential use in neurologic diseases. Further, these neural progenitors showed engraftment potential in vivo and were capable of differentiating into mature neurons and astrocytes in vitro. This study demonstrates the usefulness of AF-MSCs as an excellent source for the generation of human transgene-free iPSCs ideally suited for autologous perinatal regenerative medicine applications.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140204/1/scd.2014.0110.pd

Development and reproduction of three predatory mites (Acari: Laelapidae and Rhodacaridae) on eggs of Ephestia kuehniella (Lepidoptera: Pyralidae)

The laelapid mites Cosmolaelaps keni and Laelaspis astronomicus beside the rhodacarid mite Protogamasellopsis denticus are biological control agents and being native predators in Egypt. In order to raise active population of above species, the biology and demographic parameters, of the three tested species were observed under laboratory conditions with eggs of Ephestia kuhniella. All predatory species were developed and reproduced with E. kuhniella eggs. The mean developmental and oviposistion periods of L. astronomicus females were the longest from the other tested species. The mean longevity of C. keni was longer than that of P. denticus. Cosmolaelaps keni consumed more E. kuhniella eggs during the oviposition and adult longevity periods than other species did. Protogamasellopsis denticus fed on E. kuhniella food gave the most rate of oviposition as shown by the maximum fertility, net reproductive rate and gross reproductive rate. Laelaspis astronomicus preying on E. kuhniella eggs gave the longest generation time, lowest rate of fecundity and all life table parameters compared to other tested species; therefore E. kuhniella eggs was appropriate for the oviposition of P. denticus and C. keni rather than L. astronomicus. This study is the first to report that E. kuhniella eggs were an acceptable factitious food for P. denticus, L. astronomicus and C. keni