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Objectives A clear development process and scientifically validated clinical practice competencies in standard critical care nursing (SCCN) have not yet been developed in Japan. Thus, this study aimed to develop a consensus-based set of SCCN competencies to provide a framework for critical care nursing education, training and evaluation.Design Multistep, modified Delphi study (a systematic review, focus group interviews, a three-round web-based Delphi survey and an external validation process).Participants A systematic review of 23 studies, focus group interviews by 12 experts, a Delphi survey by 239 critical care experts (physicians, nurses and physical therapists) and an external validation by 5 experts (physicians and nurses).Results A systematic review identified 685 unique competencies. The focus group interviews resulted in the addition of 3 performance indicator items, a synthesis of 2 subdomains and 10 elements. Of the 239 participants, 218 (91.2%), 209 (98.9%) and 201 (96.2%) responded in rounds 1, 2 and 3 of the Delphi survey, respectively. After round 3, 57 items were below the consensus level and were removed in the final round. External validation process feedback was received from experts after two revisions to ensure that the final competencies were valid, applicable, useful and clear. The final set of competencies was classified into 6 domains, 26 subdomains, 99 elements and 525 performance indicators.Conclusions This study found a set of SCCN competencies after a multistep, modified Delphi study. The results of this study are robust, and the competency framework can be used in multiple areas to improve clinical practice, including the assessment, training and certification of standard critical care nurses.

Abstract The oral microbiome plays an important role in the human microbial community and in maintaining the health of an individual. Imbalances in the oral microbiome may contribute to oral and systemic diseases. The progression of periodontal disease is closely related to the growth of bacteria, such as Porphyromonas gingivalis, in the oral cavity. However, the pathogen growth mechanism specific to periodontal disease remains unknown. This study aimed to identify bacteria associated with periodontal health by focusing on hemolytic bacteria. Unstimulated saliva samples were collected from ten periodontitis patients and five healthy subjects to detect and identify the presence of hemolytic bacteria. The saliva of healthy subjects contained a higher proportion of G. haemolysans than saliva samples from patients with periodontitis. Growth inhibition assays indicated that the protein components contained in the culture supernatant of G. haemolysans directly suppressed the growth of P. gingivalis. This study shows that the presence of G. haemolysans in saliva is associated with periodontal health and that it inhibits the growth of P. gingivalis in vitro.

In this study, we experimentally investigated soot and NOx in a diffusion flame on a coaxial burner. By applying a dielectric-barrier-discharge (DBD) plasma, we tried to reduce these emissions. When the DBD plasma was exposed to the air flow, the height of the luminous flame slightly decreased. By considering the fact that the flame height without the DBD plasma is proportional to the fuel flow rate, the DBD plasma surely affects the soot concentration of the luminous flame. Based on the LII image, the soot region identified by the LII signal corresponds to the luminous flame zone. This soot distribution is similar even when the DBD plasma is activated, but the soot concentration of the luminous flame zone is reduced. As the air flow rate increases, the reduction of the integrated LII signal by the DBD plasma is smaller. This could be because the plasma is only active at the exit of the air flow, and the effect of the plasma is relatively weaker when the air flow rate increases. As for NOx emission, it is confirmed that the EINOx without plasma increases by increasing the air flow rate, showing that the thermal NOx could increase. Overall, when the plasma is activated, the EINOx always increases at any air flow rate. That is, the simultaneous reduction of soot and NOx cannot be achieved.

The correlation between BZ reaction and mixing state has been studied for decades, and the researchers are trying to apply it to chemical engineering. We observed a chemical wave pattern in the Belouzov-Zhabotinsky (BZ) reaction based on the inhomogeneity after mixing BZ and ferroin solutions with a mixing method named the rotation-and-stop method. A one-dimensional chemical wave appeared for large inhomogeneity in mixing. The frequency and wavenumber decreased with decreasing degree of inhomogeneity. In an almost perfectly mixed state, the wavenumber significantly reduced and approached the global oscillation. The degree of mixing could be efficiently determined by this reported method. Perfect mixing has never been realized in natural and biological systems. The results of this study can be applied to estimate the degree of mixing in a solution that is not being stirred after the mixing process.

Self-propelled objects, which exhibit characteristic features of motion, are proposed based on nonlinear science. At first, a self-propelled object with length like undulatory swimming is designed, i.e., the phase of oscillation at several points on the object is propagated in the opposite direction of motion. Second, the vertical oscillation of a camphor disk is created at an amphiphilic molecular layer developed on water. The proposed systems suggest that nonlinearity can enhance the autonomy of self-propelled objects as multidimensional motion.

Two novel amphiphiles, N-(3-nitrophenyl)stearamide (MANA) and N,N′-(4-nitro-1,3-phenylene)distearamide (OPANA), were synthesized by reacting nitroanilines with one or two equivalents of stearic acid. We investigated how the molecular structures of these compounds influenced the characteristics of a self-propelled camphor disk placed on a monolayer of the synthesized amphiphiles. Three types of motion were observed at different surface pressures (Π): continuous motion (Π < 4 mN m−1), deceleration (4 mN ≤ Π ≤ 20 mN m−1), and no motion (Π > 20 mN m−1). The speed of the motion of the camphor disks was inversely related to Π for both MANA and OPANA at the temperatures tested, when Π increased in the respective molecular layers under compression. The spectroscopic evidence from UV-Vis, NMR, and ESI-TOF-MS revealed that the dependence of the speed of the motion on Π originates from the intermolecular interactions that are present in the monolayers. This study suggests that it is possible to control the self-propelled motion by manipulating contributing factors at the molecular level.

Background and study aims We developed an e-learning program for endoscopic diagnosis of invasion depth of early gastric cancer (EGC) using a simple diagnostic criterion called non-extension sign, and the contribution of self-study quizzes to improvement of diagnostic accuracy was evaluated. Methods We conducted a prospective randomized controlled study that recruited endoscopists throughout Japan. After completing a pretest, the participants watched video lectures and undertook post-test 1. The participants were then randomly allocated to either the self-study or non-self-study group, and participants in the first group completed the self-study program that comprised 100-case quizzes. Finally, participants in both groups undertook post-test 2. The primary endpoint was the difference in post-test 2 scores between the groups. The perfect score for the tests was set as 100 points. Results A total of 423 endoscopists completed the pretest and were enrolled. Post-test 1 was completed by 415 endoscopists and 208 were allocated to the self-study group and 207 to the non-self-study group. Two hundred and four in the self-study group and 205 in the non-self-study group were included in the analysis. Video lectures improved the mean score of post-test 1 from 72 to 77 points. Participants who completed the self-study quizzes showed significantly better post-test 2 scores compared with the non-self-study group (80 vs. 76 points, respectively, P

Recent studies have shown that the behavior of calcium in the epidermis is closely related to the conditions of the skin, especially the differentiation of the epidermal keratinocytes and the permeability barrier function, and therefore a correct understanding of the calcium dynamics is important in explaining epidermal homeostasis. Here we report on experimental observations of in vitro calcium waves in keratinocytes induced by mechanical stimulation, and present a mathematical model that can describe the experimentally observed wave behavior that includes finite-range wave propagation and a ring-shaped pattern. A mechanism of the ring formation hypothesized by our model may be related to similar calcium propagation patterns observed during the wound healing process in the epidermis. We discuss a possible extension of our model that may serve as a tool for investigating the mechanisms of various skin diseases.

In 1952, Alan Turing accomplished a pioneering theoretical study to show that the coupling of nonlinear chemical reactions and diffusion leads to the instability of spatially homogeneous states. The activator and inhibitor are synthesized as intermediates of the reaction system in the Turing model. Turing found that spatially periodic stationary concentration patterns are spontaneously generated when the diffusion coefficient of the activator is lower than that of the inhibitor. The first experimental realization of the Turing pattern was achieved in 1990 in a chlorite-iodide-malonic acid (CIMA) reaction system. Iodide and chlorite anions act as the activator and inhibitor of this reaction system, respectively. Although there is no significant difference in the diffusion coefficient of iodide and chlorite anions, the Turing pattern was generated because starch was added to the gel reactor to enhance the color tone. This formed a complex with iodide to inhibit its diffusion to satisfy the condition for the Turing instability. Several examples were found after this finding. We focused on the high affinity of quaternary alkyl ammonium cations to iodide. The CIMA reaction was performed in an open gel reactor by adding a quaternary alkyl ammonium cationic surfactant. In addition, the polymer gel consists of the quaternary alkyl ammonium group as the side chain was utilized for the open gel reactor. The micelles of the surfactants and the polymer gels trapped iodide in their vicinity as a counter anion to lower the effective diffusivity to satisfy the condition for the Turing instability. [ABSTRACT FROM AUTHOR]

Chemical gardens formed from two metal salts (MCl2 or MSO4) have been investigated to understand the effects of mixing on the growth of precipitate tubes. The growth of tubes can be classified into three types, i.e., collaborative, inhibited, and individual growth, depending on the combination of the two metal salts. Characteristic features of tube growth are discussed in relation to the flow near the tip of the tube controlled by osmotic pressure and the solubility product, Ksp, for M(OH)2. The present study can be interpreted as an inanimate model system of symbiosis among different species, such as mixed cropping systems and survival among different kinds of microbial cells. [ABSTRACT FROM AUTHOR]

Attempts made to investigate the self-motion of a camphor grain on a linear water route are presented. The essential features of the self-motion were reproduced by numerical calculations in relation to the spatial distribution of the camphor layer at the air-water interface.

Research is presented describing the study of oxidant crystal and the effects of mercury on the crystal.

Abstract The diagnosis of coronary artery disease (CAD) with nonstress echocardiography remains challenging. Although the assessment of either early systolic lengthening (ESL) or postsystolic shortening (PSS) allows the sensitive detection of CAD, it is unclear whether the integrated analysis of ESL and PSS in addition to the peak systolic strain can improve the diagnostic accuracy. We investigated the incremental value of ESL and PSS in detecting left anterior descending artery (LAD) stenosis using nonstress speckle-tracking echocardiography. Fifty-nine patients with significant LAD stenosis but without visual wall motion abnormalities on echocardiography at rest (30 single-vessel stenosis, 29 multivessel stenosis) and 43 patients without significant stenosis of any vessel were enrolled. The peak systolic strain, the time to ESL (TESL), and the time to PSS (TPSS) were analyzed in all LAD segments, and the incremental values of the TESL and TPSS in detecting LAD stenosis and the diagnostic accuracy were evaluated. In the apical anterior segment, the peak systolic strain was significantly lower and TESL and TPSS were significantly longer in the single-vessel group than in the no stenosis group. In the single-vessel group, the addition of TESL and TPSS to the peak systolic strain significantly increased the model power in detecting stenosis, and the integrated analysis improved diagnostic accuracy compared with the peak systolic strain alone. In contrast, this incremental value was not demonstrated in the multivessel group. The integrated analysis of the peak systolic strain, ESL, and PSS may allow better screening of single-vessel LAD stenosis using nonstress speckle-tracking echocardiography.

We review our recent results on a simple droplet system consisting of droplets of a mixture of two liquids. Although the system is composed of simple chemicals, it is capable of exhibiting complex collective behaviors as a cluster dynamics. We propose a simple inhomogeneous force model to analyze the experimental observations and discuss the mechanisms of the dynamic ordering in our system. The relevance of the observations to hierarchical ordering generally observed in systems of active elements is also discussed. [ABSTRACT FROM AUTHOR]

As simple and easily controllable objects among various self-propelled particles, camphor floats on the water surface have been widely recognized. In this paper, we introduce characteristic behaviors and discuss the background mechanism of camphor floats on water, both in isolated and non-isolated conditions. In particular, we focus on: (i) the transition of dynamical characters through bifurcations exhibited by systems with small number of camphor floats and (ii) the emergence of a rich variety of complex dynamics observed in systems with large number camphor floats, and attempt to elucidate these phenomena through mathematical modeling as well as experimental analysis. Finally, we discuss the connection of the dynamics of camphor floats to that of a wider class of complex and sophisticated dynamics exhibited by various types of self-propelled particles. [ABSTRACT FROM AUTHOR]

Abstract Background Gastritis cystica polyposa (GCP) is a recently recognized entity histologically characterized by hyperplasia and cystic dilatation of the gastric glands spreading through the submucosal layer. Its symptoms include those affecting the upper gastrointestinal tract, such as upper abdominal pain, nausea, and anorexia, although some patients might be asymptomatic. GCP rarely causes severe hemorrhage. Recently, we encountered a GCP case that exhibited severe hemorrhage. Case presentation A 53 year-old man visited the emergency department complaining of hematemesis. He underwent distal gastrectomy and Billroth II reconstruction for duodenal ulcers 32 years ago. Upper gastrointestinal endoscopy detected bleeding from the reddened mucosa at the anastomosis; thus, tentative endoscopic hemostasis was conducted. Despite medical treatment with transfusion, melena with significant hemodynamic impairment persisted. He was treated again with endoscopic hemostasis and interventional radiology (IVR) but remained unresponsive to these procedures. He eventually underwent partial resection of the anastomosis site with Roux-en-Y reconstruction and finally achieved excellent postoperative recovery. Histopathological examination of the resected specimen suggested a GCP bleeding. Conclusions GCP can indeed cause severe hemorrhage. Hemorrhage caused by GCP may not respond to endoscopic hemostasis or IVR; therefore, surgical treatment should be decided without delay.

Abstract Aims Guidelines for the diagnosis and treatment of acute and chronic heart failure (HF) provided by the European Society of Cardiology state that echocardiography is recommended for the assessment of the myocardial structure and function of subjects with suspected HF including HF with reduced (HFrEF), mid‐range (HFmrEF), and preserved ejection fraction (HFpEF) as class I of recommendation and level C of evidence. However, the impact of timing of echocardiography on survival for hospitalized HF patients or the prevalence of echocardiography during their stay has not yet been fully investigated. Therefore, we designed and conducted a prospective multicentre study, Optimal Timing of Echocardiography for Heart Failure Inpatients in Japanese Institutions (OPTIMAL) study, to investigate and evaluate the prevalence of echocardiography during the in‐hospital stay of HF patients, and the impact of timing of echocardiography on their survival. Methods and results OPTIMAL was based on a nationwide, prospective, multicentre registry at 10 institutions in Japan endorsed by the Japanese Society of Echocardiography. A total of 601 patients hospitalized with HF were enrolled between August 2016 and July 2018 at the participating centres. Their mean age was 73.9 ± 13.0 years, left ventricular ejection fraction was 37.0% (26.0–50.0), and 256 patients (42.6%) were female. Admission echocardiography (admission echo) was categorized as either standard or point‐of‐care echocardiography performed within 3 days of admission, as was pre‐discharge echocardiography (pre‐discharge echo) within 3 days of discharge. The primary endpoint was defined as cardiovascular death over a median follow‐up period of 18.9 months (9.3–26.5 months). Admission echo was performed for 476 patients (79.2%) and pre‐discharge echo for 216 patients (35.9%). The primary endpoint of cardiovascular death occurred in 65 patients (10.8%). Kaplan–Meier curve findings indicated that survival of patients with pre‐discharge echo was significantly better than that of patients without it (log‐rank P

Self-motion of a camphor disk rotating inside a water chamber composed of two half-disks was investigated. The half-disks were joined along their diameter segments, and the distance between their midpoints (ds) was considered as the control parameter. Various types of camphor disk motions were observed depending on ds. When ds = 0, the chamber had a circular shape, so it was symmetric. A camphor disk showed either a clockwise (CW) or counterclockwise (CCW) rotation with the direction determined by its initial state. The symmetry of the chamber was broken for ds > 0. For moderate distances between the midpoints, a unidirectional orbital motion of the disk was observed. The preferred rotation direction was determined by the shape of the chamber, and it did not depend on the initial rotation direction. For yet larger ds, the unidirectional circular motion was no longer observed and the trajectory became irregular. A mathematical model coupling the camphor disk motion with the dynamics of the developed camphor molecular layer on water was constructed, and the numerical results were compared with the experimental results. The selection of motion type can be explained by considering the influence of camphor concentration on the disk trajectory through the surface tension gradient. [ABSTRACT FROM AUTHOR]

A new mode of collective motion was discovered in a system of camphor disks floating on the water surface in a circular chamber. The mode was induced by tuning the number of the disks. A single or few disks are known to continuously move on the water surface. Conversely, when many disks are present, motion comes to a stop and the disks form ordered spatial patterns by repulsive interaction. Here we found the third mode that emerged at an intermediate disk number, in which inactive and active motion phases alternated non-periodically. This new mode exhibited synchronization as the disk number increased. [ABSTRACT FROM AUTHOR]

We study the Arnold tongue of a nonlinear electrochemical oscillator entrained to an electrical periodic forcing. In our system, the width of the 1:3 entrainment region was broader than that of the 1:2 region. The 1:1 and 1:3 regions became monotonically broad when the conductance of the electrode cell was increased by the electrochemical redox reaction of Fe(CN)64−⇄ Fe(CN)63−+ e. In contrast, the 1:2 region changed nonmonotonically. In particular, the rate of change in the 1:2 region was greater than those of the 1:1 and 1:3 regions. These experimental results were qualitatively reproduced by the use of phase response curves of a corresponding mathematical model. We also discuss higher harmonics included in a limit cycle describing the isolated oscillator, dependence on the redox reaction, and hysteresis due to a bistability. [ABSTRACT FROM AUTHOR]

As a simple example of an autonomous motor, the characteristic features of self-motion coupled with the acid–base reaction were numerically and experimentally investigated at the air/aqueous interface. Oscillatory and uniform motion were categorized as a function of the reaction order by numerical computations using a mathematical model that incorporates both the distribution of the surface active layer developed from a material particle as the driving force and the kinetics of the acid–base reaction. The nature of the self-motion was experimentally observed for a boat adhered to a camphor derivative with a mono- or di-carboxylic acid on a phosphate aqueous phase as the base. [ABSTRACT FROM AUTHOR]

The photosensitive Belousov-Zhabotinsky (BZ) reaction was investigated on a circular ring, which was drawn using computer software and then projected on a film soaked with BZ solution using a liquid-crystal projector. Under the initial conditions, a chemical wave propagated with a constant velocity on the black ring under a bright background. When the background was rapidly changed to dark, coexistence of the oscillation on part of the ring and propagation of the chemical wave on the other part was observed. These experimental results are discussed in relation to the nature of the photosensitive BZ reaction and theoretically reproduced based on a reaction-diffusion system using the modified Oregonator model. [ABSTRACT FROM AUTHOR]

Control of the self-motion of a camphanic acid disk on water was investigated upon the addition of different kinds of surfactants (Triton X-100 and Brij58 as neutral surfactants, cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, and sodium dodecyl sulfate (SDS) as an anionic surfactant) to the water phase. With an increase in the concentration of surfactant, continuous motion changed to no motion via intermittent motion (repetition between motion and rest), and the concentration regions of these motions were different among these surfactants. Although the concentration regions of these motions were determined by the surface tension for neutral surfactants, they were different than those for CTAB and SDS. These characteristics of self-motion are discussed in relation to the surface tension, depending on the concentration of individual surfactants, and the hydrophilic effect of the surfactants. [ABSTRACT FROM AUTHOR]

The propagation of chemical waves in the photosensitive Belousov−Zhabotinsky (BZ) reaction was investigated using an excitable field composed of two rings in slight contact, which were drawn using computer software and then projected on a film soaked with BZ solution using a liquid-crystal projector. When the initial phase difference between the two chemical waves in the individual rings was smaller than a critical value, this initial value was maintained after collision of the chemical waves. However, when the initial phase difference was larger than this critical value, the phase difference converged to the same value after the second collision. The critical value increased with an increase in the thickness of the rings. These experimental results on the geometry of the excitable field are discussed in relation to the nature of chemical wave propagation. These results suggest that the photosensitive BZ reaction may be useful for creating spatiotemporal patterns that depend on the geometric arrangement of excitable fields. [ABSTRACT FROM AUTHOR]

As a simple autonomous motor, the self-motion of a camphanic acid disk on the aqueous phase with a neutral surfactant (Triton X-100) was investigated. Whereas only continuous motion was observed on water, intermittent motion (alternating between motion and rest) was observed upon addition of Triton X-100. Under the experimental conditions that gave intermittent motion, the surface tension of the aqueous phase changed periodically, synchronous with the contact angle around the camphanic acid disk. These characteristics of self-motion are discussed in relation to the surface tension depending on the concentration of camphanic acid with or without Triton X-100 as the driving force of the motion. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this study was to longitudinally assess left ventricular function and wall thickness in a hamster model of cardiomyopathy using 11.7-T magnetic resonance imaging (MRI). MRI were performed for six cardiomyopathic J2N-k hamsters and six J2N-n hamsters at 5, 10, 15, and 20 weeks of age. Echocardiography was also performed at 20 weeks. The ejection fraction (EF) at 15 and 20 weeks of age in J2N-k hamsters showed a significant decrease compared with those in controls. Conversely, the end-systolic and end-diastolic volumes in cardiomyopathic hamsters showed a significant increase compared with those in controls. Moreover, the heart walls of J2N-k hamsters at 15 and 20 weeks were thicker than those of controls at end-systole; however, there were no significant differences at end-diastole. Optical microscopy with Masson’s trichrome staining depicted no fibrosis in the control myocardium, although it showed interstitial fibrosis in the 20-week-old J2N-k cardiomyopathic myocardium. There were no differences in EF and the wall thickness observed on MRI and those observed on echocardiography. These results indicate the presence of systolic dysfunction in cardiomyopathic hamsters. Self-gated cine imaging based on 11.7-T MRI can be used for serial measurements of cardiac function and wall thickness in a cardiomyopathic model.

We developed a catalytic propelled motor using the fuel source glucose, without the addition of hydrogen peroxide (H2O2), in an aqueous phase. The motor was composed of a Pt foil and a filter paper with glucose oxidase (GOx). H2O2 was produced by the enzyme reaction of GOx and glucose around the motor. The speed and fluctuation of the motor increased with an increase in the concentration of glucose based on the enzyme reaction. [ABSTRACT FROM AUTHOR]

The transplantation of cardiac stem cell sheets (CSC sheets) is a promising therapeutic strategy for ischemic cardiomyopathy, although potential ischemia in the transplanted area remains a problem. Injected endothelial progenitor cells (EPCs) can reportedly induce angiogenesis in the injected area. We hypothesized that concomitant CSC sheet transplantation and EPC injection might show better therapeutic effects for chronic ischemic injury model than the transplantation of CSC sheets alone. Scaffold-free CSC sheets were generated from human c-kit-positive heart-derived cells. A porcine chronic ischemic injury model was generated by placing an ameroid constrictor around the left coronary artery for 4 weeks. The animals then underwent a sham operation, epicardial transplantation of CSC sheet over the ischemic area, intramyocardial injection of EPCs into the ischemic and peri-ischemic area, or CSC sheet transplantation plus EPC injection. The efficacy of each treatment was then assessed for 2 months. Speckle-tracking echocardiography was used to dissect the layer-specific regional systolic function by measuring the radial strain (RS). The epicardial RS in the ischemic area was similarly greater after treatment with the CSC-derived cell sheets alone (19 ± 5%) or in combination with EPC injection (20 ± 5%) compared with the EPC only (9 ± 4%) or sham (7 ± 1%) treatment. The endocardial RS in the ischemic area was greatest after the combined treatment (14 ± 1%), followed by EPC only (12 ± 1%), compared to the CSC only (11 ± 1%) and sham (9 ± 1%) treatments. Consistently, either epicardial CSC sheet implantation or intramyocardial EPC injection yielded increased capillary number and reduced cardiac fibrosis in the ischemic epicardium or endocardium, respectively. Concomitant EPC injection induced the migration of transplanted CSCs into the host myocardium, leading to further neovascularization and reduced fibrosis in the ischemic endocardium, compared to the CSC sole therapy. Transplantation of CSC sheets induced significant functional recovery of the ischemic epicardium, and concomitant EPC transplantation elicited transmural improvement in chronic ischemic injury.

Trajectory-pattern formation of a self-propelled oil droplet floating on the surface of a surfactant solution in a circular dish is studied both experimentally and by simulation. The Marangoni effect induced by the dissolution of oil in the solution drives the droplet's motion. The trajectories spontaneously organize into several patterns including circular, knot-forming, back-and-forth, and irregular ones. They are either global patterns, whose center corresponds to the dish center, or other local patterns. Our simple model consisting of three forces, the driving force, the viscous resistance, and the repulsion from the boundary, successfully reproduces the global trajectory patterns including the power spectrum of the droplet speed. [ABSTRACT FROM AUTHOR]

Mode selection and bifurcation of a synchronized motion involving two symmetric self-propelled objects in a periodic one-dimensional domain were investigated numerically and experimentally by using camphor disks placed on an annular water channel. Newton's equation of motion for each camphor disk, whose driving force was the difference in surface tension, and a reaction-diffusion equation for camphor molecules on water were used in the numerical calculations. Among various dynamical behaviors found numerically, four kinds of synchronized motions (reversal oscillation, stop-and-move rotation, equally spaced rotation, and clustered rotation) were also observed in experiments by changing the diameter of the water channel. The mode bifurcation of these motions, including their coexistence, were clarified numerically and analytically in terms of the number density of the disk. These results suggest that the present mathematical model and the analysis of the equations can be worthwhile in understanding the characteristic features of motion, e.g., synchronization, collective motion, and their mode bifurcation. [ABSTRACT FROM AUTHOR]

The response of a traveling pulse to a local external stimulus is considered numerically for a modified three-component Oregonator, which is a model system for the photosensitive Belousov-Zhabotinsky (BZ) reaction. The traveling pulse is traced and constantly stimulated, with the distance between the pulse and the stimulus being kept constant. We are interested in the minimal strength of the spatially localized stimulus in order to eliminate the pulse. The use of a stimulus of small width allows us to detect the point in the pulse most sensitive to the external stimulus, referred to as the "Achilles' heel" of the traveling pulse, at which minimal strength of stimulus causes a collapse of the pulse. Our findings are demonstrated experimentally as well with the photosensitive BZ reaction. [ABSTRACT FROM AUTHOR]