3,030 research outputs found
Development of Navigation Control Algorithm for AGV Using D* Search Algorithm
In this paper, we present a navigation control algorithm for Automatic Guided Vehicles (AGV) that move in industrial environments including static and moving obstacles using D* algorithm. This algorithm has ability to get paths planning in unknown, partially known and changing environments efficiently. To apply the D* search algorithm, the grid map represent the known environment is generated. By using the laser scanner LMS-151 and laser navigation sensor NAV-200, the grid map is updated according to the changing of environment and obstacles. When the AGV finds some new map information such as new unknown obstacles, it adds the information to its map and re-plans a new shortest path from its current coordinates to the given goal coordinates. It repeats the process until it reaches the goal coordinates. This algorithm is verified through simulation and experiment. The simulation and experimental results show that the algorithm can be used to move the AGV successfully to reach the goal position while it avoids unknown moving and static obstacles. [Keywords— navigation control algorithm; Automatic Guided Vehicles (AGV); D* search algorithm
Isobar of an ideal Bose gas within the grand canonical ensemble
We investigate the isobar of an ideal Bose gas confined in a cubic box within
the grand canonical ensemble, for a large yet finite number of particles, N.
After solving the equation of the spinodal curve, we derive precise formulae
for the supercooling and the superheating temperatures which reveal an N^{-1/3}
or N^{-1/4} power correction to the known Bose-Einstein condensation
temperature in the thermodynamic limit. Numerical computations confirm the
accuracy of our analytical approximation, and further show that the isobar
zigzags on the temperature-volume plane if N is greater than or equal to 14393.
In particular, for the Avogadro's number of particles, the volume expands
discretely about 10^5 times. Our results quantitatively agree with a previous
study on the canonical ensemble within 0.1% error.Comment: 6 pages, 2 figures; Reference added. Accepted for publication in
Phys. Rev.
UVB Induces HIF-1α-Dependent TSLP Expression via the JNK and ERK Pathways
Thymic stromal lymphopoietin (TSLP) may have a key role in the initiation and maintenance of allergic inflammatory diseases, including atopic dermatitis. The present study revealed that UVB radiation exposure could induce TSLP expression in human keratinocytes and a human skin equivalent model. In addition, we investigated the regulatory mechanism of UVB-induced TSLP expression in keratinocytes. TSLP expression was upregulated by transfection with pcDNA3–hypoxia-inducible factor (HIF)-1α (P402A and P564A), which stably expresses HIF-1α protein. UVB-induced TSLP induction in keratinocytes was suppressed in the treatment of mitogen-activated protein kinase inhibitors or small interfering RNAs against HIF-1α. The results of chromatin immunoprecipitation assays indicate the direct involvement of HIF-1α in UVB-mediated TSLP induction. Taken together, these findings indicate that UVB exposure may increase TSLP expression through a HIF-1α-dependent mechanism via the c-JUN N-terminal kinase and extracellular signal-regulated kinase pathways in human keratinocytes. Our data showed that UVB-induced TSLP might increase secretion of the T-helper type 2–attracting chemokine (c–c motif) ligand 17 by human dendritic cells. The present study suggests an important role of HIF-1α in UVB-mediated immune response in keratinocytes
Cdk5 Phosphorylates Dopamine D2 Receptor and Attenuates Downstream Signaling
The dopamine D2 receptor (DRD2) is a key receptor that mediates dopamine-associated brain functions such as mood, reward, and emotion. Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase whose function has been implicated in the brain reward circuit. In this study, we revealed that the serine 321 residue (S321) in the third intracellular loop of DRD2 (D2i3) is a novel regulatory site of Cdk5. Cdk5-dependent phosphorylation of S321 in the D2i3 was observed in in vitro and cell culture systems. We further observed that the phosphorylation of S321 impaired the agonist-stimulated surface expression of DRD2 and decreased G protein coupling to DRD2. Moreover, the downstream cAMP pathway was affected in the heterologous system and in primary neuronal cultures from p35 knockout embryos likely due to the reduced inhibitory activity of DRD2. These results indicate that Cdk5-mediated phosphorylation of S321 inhibits DRD2 function, providing a novel regulatory mechanism for dopamine signaling.X111111sciescopu
Ferritin-Templated Quantum-Dots for Quantum Logic Gates
Quantum logic gates (QLGs) or other logic systems are based on quantum-dots (QD) with a stringent requirement of size uniformity. The QD are widely known building units for QLGs. The size control of QD is a critical issue in quantum-dot fabrication. The work presented here offers a new method to develop quantum-dots using a bio-template, called ferritin, that ensures QD production in uniform size of nano-scale proportion. The bio-template for uniform yield of QD is based on a ferritin protein that allows reconstitution of core material through the reduction and chelation processes. One of the biggest challenges for developing QLG is the requirement of ordered and uniform size of QD for arrays on a substrate with nanometer precision. The QD development by bio-template includes the electrochemical/chemical reconsitution of ferritins with different core materials, such as iron, cobalt, manganese, platinum, and nickel. The other bio-template method used in our laboratory is dendrimers, precisely defined chemical structures. With ferritin-templated QD, we fabricated the heptagonshaped patterned array via direct nano manipulation of the ferritin molecules with a tip of atomic force microscope (AFM). We also designed various nanofabrication methods of QD arrays using a wide range manipulation techniques. The precise control of the ferritin-templated QD for a patterned arrangement are offered by various methods, such as a site-specific immobilization of thiolated ferritins through local oxidation using the AFM tip, ferritin arrays induced by gold nanoparticle manipulation, thiolated ferritin positioning by shaving method, etc. In the signal measurements, the current-voltage curve is obtained by measuring the current through the ferritin, between the tip and the substrate for potential sweeping or at constant potential. The measured resistance near zero bias was 1.8 teraohm for single holoferritin and 5.7 teraohm for single apoferritin, respectively
Existence of a critical point in the phase diagram of the ideal relativistic neutral Bose gas
We explore the phase transitions of the ideal relativistic neutral Bose gas
confined in a cubic box, without assuming the thermodynamic limit nor
continuous approximation. While the corresponding non-relativistic canonical
partition function is essentially a one-variable function depending on a
particular combination of temperature and volume, the relativistic canonical
partition function is genuinely a two-variable function of them. Based on an
exact expression of the canonical partition function, we performed numerical
computations for up to hundred thousand particles. We report that if the number
of particles is equal to or greater than a critical value, which amounts to
7616, the ideal relativistic neutral Bose gas features a spinodal curve with a
critical point. This enables us to depict the phase diagram of the ideal Bose
gas. The consequent phase transition is first-order below the critical pressure
or second-order at the critical pressure. The exponents corresponding to the
singularities are 1/2 and 2/3 respectively. We also verify the recently
observed `Widom line' in the supercritical region.Comment: 1+25 pages, 6 B/W figures: Comment on the Widom line added. Minor
improvement. Version to appear in `New Journal of Physics
Electromagnetic fields in a 3D cavity and in a waveguide with oscillating walls
We consider classical and quantum electromagnetic fields in a
three-dimensional (3D) cavity and in a waveguide with oscillating boundaries of
the frequency . The photons created by the parametric resonance are
distributed in the wave number space around along the axis of the
oscillation. When classical waves propagate along the waveguide in the one
direction, we observe the amplification of the original waves and another wave
generation in the opposite direction by the oscillation of side walls. This can
be understood as the classical counterpart of the photon production. In the
case of two opposite walls oscillating with the same frequency but with a phase
difference, the interferences are shown to occur due to the phase difference in
the photon numbers and in the intensity of the generated waves.Comment: 8 pages revTeX including 1 eps fi
Thermodynamic instability and first-order phase transition in an ideal Bose gas
We conduct a rigorous investigation into the thermodynamic instability of
ideal Bose gas confined in a cubic box, without assuming thermodynamic limit
nor continuous approximation. Based on the exact expression of canonical
partition function, we perform numerical computations up to the number of
particles one million. We report that if the number of particles is equal to or
greater than a certain critical value, which turns out to be 7616, the ideal
Bose gas subject to Dirichlet boundary condition reveals a thermodynamic
instability. Accordingly we demonstrate - for the first time - that, a system
consisting of finite number of particles can exhibit a discontinuous phase
transition featuring a genuine mathematical singularity, provided we keep not
volume but pressure constant. The specific number, 7616 can be regarded as a
characteristic number of 'cube' that is the geometric shape of the box.Comment: 1+21 pages; 3 figures (2 color and 1 B/W); Final version to appear in
Physical Review A. Title changed from the previous one, "7616: Critical
number of ideal Bose gas confined in a cubic box
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