Regression Study of Odorant Chemical Space, Molecular Structural Diversity, and Natural Language Description.

Odor is analyzed on the human olfactometry systems in various steps. The mapping from chemical structures to olfactory perceptions of smell is an extremely challenging task. Scientists have been unable to find a measure to distinguish the perceptual similarity between odorants.

Order recognition by Schubert polynomials generated by optical near-field statistics via nanometre-scale photochromism.

Irregular spatial distribution of photon transmission through a photochromic crystal photoisomerized by a local optical near-field excitation was previously reported, which manifested complex branching processes via the interplay of material deformation and near-field photon transfer therein. Furthermore, by combining such naturally constructed complex photon transmission with a simple photon detection protocol, Schubert polynomials, the foundation of versatile permutation operations in mathematics, have been generated. In this study, we demonstrated an order recognition algorithm inspired by Schubert calculus using optical near-field statistics via nanometre-scale photochromism.

Scanning near-field optical spectroscopy and carrier transport based analysis in mesoscopic regions for two-dimensional semiconductors.

The measurements of photoexcited transport in mesoscopic regimes reveal the states and properties of mesoscopic systems. In this study, we focused on direct measurements of electromagnetic energy transports in the mesoscopic regions and constructed a scanning tunnelling microscope-assisted multi-probe scanning near-field optical microscope spectroscopy system. After producing an emission energy map through a single-probe measurement, two-probe measurement enables us to observe and analyse carrier transport characteristics.

Entangled and correlated photon mixed strategy for social decision making.

Collective decision making is important for maximizing total benefits while preserving equality among individuals in the competitive multi-armed bandit (CMAB) problem, wherein multiple players try to gain higher rewards from multiple slot machines. The CMAB problem represents an essential aspect of applications such as resource management in social infrastructure. In a previous study, we theoretically and experimentally demonstrated that entangled photons can physically resolve the difficulty of the CMAB problem.

Entangled N-photon states for fair and optimal social decision making.

Situations involving competition for resources among entities can be modeled by the competitive multi-armed bandit (CMAB) problem, which relates to social issues such as maximizing the total outcome and achieving the fairest resource repartition among individuals. In these respects, the intrinsic randomness and global properties of quantum states provide ideal tools for obtaining optimal solutions to this problem. Based on the previous study of the CMAB problem in the two-arm, two-player case, this paper presents the theoretical principles necessary to find polarization-entangled N-photon states that can optimize the total resource output while ensuring equality among players.

Generation of Schubert polynomial series via nanometre-scale photoisomerization in photochromic single crystal and double-probe optical near-field measurements.

Generation of irregular time series based on physical processes is indispensable in computing and artificial intelligence. In this report, we propose and demonstrate the generation of Schubert polynomials, which are the foundation of versatile permutations in mathematics, via optical near-field processes introduced in a photochromic crystal of diarylethene combined with a simple photon detection protocol. Optical near-field excitation on the surface of a photochromic single crystal yields a chain of local photoisomerization, forming a complex pattern on the opposite side of the crystal.

Entangled-photon decision maker.

The competitive multi-armed bandit (CMAB) problem is related to social issues such as maximizing total social benefits while preserving equality among individuals by overcoming conflicts between individual decisions, which could seriously decrease social benefits. The study described herein provides experimental evidence that entangled photons physically resolve the CMAB in the 2-arms 2-players case, maximizing the social rewards while ensuring equality. Moreover, we demonstrated that deception, or outperforming the other player by receiving a greater reward, cannot be accomplished in a polarization-entangled-photon-based system, while deception is achievable in systems based on classical polarization-correlated photons with fixed polarizations.

Unique Structural Relaxations and Molecular Conformations of Porphyra-334 at the Excited State.

Quantum chemistry based simulations were used to examine the excited state of porphyra-334, one of the fundamental mycosporine-like amino acids present in a wide variety of aqueous organisms. Our calculations reveal three characteristic aspects of porphyra-334 related to either its ground or excited state. Specifically, (i) the ground state (S) structure consists of a planar geometry in which three units can be identified, the central cyclohexene ring, the glycine branch, and the threonine branch, reflecting the π conjugation of the system; (ii) the first singlet excited state (S) shows a large oscillator strength and a typical ππ* excitation character; and (iii) upon relaxation at S, the originally ground state planar structure undergoes a relaxation to a nonplanar one, S, especially at the carbon-nitrogen (CN) groups linking the cyclohexene ring to the glycine or threonine arm.

Author Correction: Nanometre-scale pattern formation on the surface of a photochromic crystal by optical near-field induced photoisomerization.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Why is the environment important for decision making? Local reservoir model for choice-based learning.

Decision making based on behavioral and neural observations of living systems has been extensively studied in brain science, psychology, neuroeconomics, and other disciplines. Decision-making mechanisms have also been experimentally implemented in physical processes, such as single photons and chaotic lasers. The findings of these experiments suggest that there is a certain common basis in describing decision making, regardless of its physical realizations.

Nanometre-scale pattern formation on the surface of a photochromic crystal by optical near-field induced photoisomerization.

We observed nanometre-scale optical near-field induced photoisomerization on the surface of a photochromic diarylethene crystal via molecular structural changes using an optical near-field assisted atomic force microscope. A nanometre-scale concavity was formed on the sample surface due to locally induced photoisomerization. By using this optical near-field induced local photoisomerization, we succeeded in generating a pattern of alphabet characters on the surface of the diarylethene crystal below the optical wavelength scale.

Scalable photonic reinforcement learning by time-division multiplexing of laser chaos.

Reinforcement learning involves decision-making in dynamic and uncertain environments and constitutes a crucial element of artificial intelligence. In our previous work, we experimentally demonstrated that the ultrafast chaotic oscillatory dynamics of lasers can be used to efficiently solve the two-armed bandit problem, which requires decision-making concerning a class of difficult trade-offs called the exploration-exploitation dilemma. However, only two selections were employed in that research; hence, the scalability of the laser-chaos-based reinforcement learning should be clarified.

Factors necessary for independent walking in patients with thalamic hemorrhage.

Background: Thalamic hemorrhages cause motor paralysis, sensory impairment, and cognitive dysfunctions, all of which may significantly affect walking independence. We examined the factors related to independent walking in patients with thalamic hemorrhage who were admitted to a rehabilitation hospital.

Methods: We evaluated 128 patients with thalamic hemorrhage (75 men and 53 women; age range, 40-93 years) who were admitted to our rehabilitation hospital.

Aphasia Following Left Putaminal Hemorrhage at a Rehabilitation Hospital.

Objective: We aimed to clarify the relationship between aphasia and hematoma type/volume in patients with left putaminal hemorrhage admitted to a rehabilitation facility.

Methods: We evaluated the relationship between the presence, type, and severity of aphasia and hematoma type/volume in 92 patients with putaminal hemorrhage aged 29-83 years. Hematoma type and volume were evaluated on the basis of CT images obtained at stroke onset.

How seaweeds release the excess energy from sunlight to surrounding sea water.

We report an atomistic insight into the mechanism regulating the energy released by a porphyra-334 molecule, the ubiquitous photosensitive component of marine algae, in a liquid water environment upon an electron excitation. To quantify this rapidly occurring process, we resort to the Fourier analysis of the mass-weighted auto-correlation function, providing evidence for a remarkable dynamic change in the number of hydrogen bonds among water molecules and between the porphyra-334 and its surrounding hydrating water. Hydrogen bonds between the porphyra-334 and close by water molecules can act directly and rather easily to promote an efficient transfer of the excess kinetic energies of the porphyra-334 to the surrounding solvating water molecules via an activation of the collective modes identified as hydrogen-bond stretching modes in liquid water which eventually results in a disruption of the hydrogen bond network.

Random walk with chaotically driven bias.

We investigate two types of random walks with a fluctuating probability (bias) in which the random walker jumps to the right. One is a 'time-quenched framework' using bias time series such as periodic, quasi-periodic, and chaotic time series (chaotically driven bias). The other is a 'time-annealed framework' using the fluctuating bias generated by a stochastic process, which is not quenched in time.

Single-photon decision maker.

Decision making is critical in our daily lives and for society in general and is finding evermore practical applications in information and communication technologies. Herein, we demonstrate experimentally that single photons can be used to make decisions in uncertain, dynamically changing environments. Using a nitrogen-vacancy in a nanodiamond as a single-photon source, we demonstrate the decision-making capability by solving the multi-armed bandit problem.

Chaotic oscillation and random-number generation based on nanoscale optical-energy transfer.

By using nanoscale energy-transfer dynamics and density matrix formalism, we demonstrate theoretically and numerically that chaotic oscillation and random-number generation occur in a nanoscale system. The physical system consists of a pair of quantum dots (QDs), with one QD smaller than the other, between which energy transfers via optical near-field interactions. When the system is pumped by continuous-wave radiation and incorporates a timing delay between two energy transfers within the system, it emits optical pulses.

Optical near-field-mediated polarization asymmetry induced by two-layer nanostructures.

We demonstrate that a two-layer shape-engineered nanostructure exhibits asymmetric polarization conversion efficiency thanks to near-field interactions. We present a rigorous theoretical foundation based on an angular-spectrum representation of optical near-fields that takes account of the geometrical features of the proposed device architecture and gives results that agree well with electromagnetic numerical simulations. The principle used here exploits the unique intrinsic optical near-field processes associated with nanostructured matter, while eliminating the need for conventional scanning optical fiber probing tips, paving the way to novel nanophotonic devices and systems.

Amoeba-inspired nanoarchitectonic computing: solving intractable computational problems using nanoscale photoexcitation transfer dynamics.

Biologically inspired computing devices and architectures are expected to overcome the limitations of conventional technologies in terms of solving computationally demanding problems, adapting to complex environments, reducing energy consumption, and so on. We previously demonstrated that a primitive single-celled amoeba (a plasmodial slime mold), which exhibits complex spatiotemporal oscillatory dynamics and sophisticated computing capabilities, can be used to search for a solution to a very hard combinatorial optimization problem. We successfully extracted the essential spatiotemporal dynamics by which the amoeba solves the problem.

Analysis of renal cell carcinoma as a first step for developing mass spectrometry-based diagnostics.

Immediate diagnosis of human specimen is an essential prerequisites in medical routines. This study aimed to establish a novel cancer diagnostics system based on probe electrospray ionization-mass spectrometry (PESI-MS) combined with statistical data processing. PESI-MS uses a very fine acupuncture needle as a probe for sampling as well as for ionization.

Lower bound of energy dissipation in optical excitation transfer via optical near-field interactions.

We theoretically analyzed the lower bound of energy dissipation required for optical excitation transfer from smaller quantum dots to larger ones via optical near-field interactions. The coherent interaction between two quantum dots via optical near-fields results in unidirectional excitation transfer by an energy dissipation process occurring in the larger dot. We investigated the lower bound of this energy dissipation, or the intersublevel energy difference at the larger dot, when the excitation appearing in the larger dot originated from the excitation transfer via optical near-field interactions.

Characteristics of probe electrospray generated from a solid needle.

Probe electrospray ionization (PESI) has recently been developed, in which the electrospray was generated from a solid needle instead of by using a capillary. In this paper, the characteristics of probe electrospray ionization were studied based on the measurement of spray current, optical microscopy, and PESI mass spectrometry. In the experiment, the solid needle was moved up and down a vertical axis, and a small amount of sample was repeatedly loaded to the needle when the tip of the needle touched the surface of the liquid sample at the lowest position.

Application of probe electrospray to direct ambient analysis of biological samples.

Recently, we have developed probe electrospray ionization (PESI) that uses a solid needle. In this system, the probe needle moves up and down along the vertical axis by a motor-driven system. At the highest position of the probe needle, electrospray is generated by applying a high voltage.

Matrix-assisted laser desorption/ionization mass spectrometry using a visible laser.

Visible matrix-assisted laser desorption/ionization (VIS-MALDI) was performed using 2-amino-3-nitrophenol as matrix. The matrix is of near-neutral pH, and has an optical absorption band in the near-UV and visible region. A frequency-doubled Nd:YAG laser operated at 532 nm wavelength was used for matrix excitation and comparisons were made with a frequency-tripled Nd:YAG laser (355 nm).