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The recommended treatment strategy for stage 3 bisphosphonate-related osteonecrosis of the jaw (BRONJ) is currently rigid plate fixation without bone reconstruction. However, a recent systematic review indicated the utility of microsurgical reconstruction after resection of BRONJ. Several types of flaps have been described but their applications are controversial. Here we present a detailed reconstruction plan for obtaining better outcomes in patients with maxillary and mandibular BRONJ. Given that progressive maxillary BRONJ is often invasive to the skin, including the eyelid, leading to functional loss such as leakage of discharge and ectropion, several revision surgeries are needed to increase the volume in the defect after the free flap transfer. For progressive mandibular BRONJ, hemi-mandibulectomy to subtotal mandibulectomy with an adequate margin from the necrotic bone is necessary, followed by a well-designed fibular free flap.

In the present study, we have elucidated the behavior of a suspension composed of magnetic disk-like particles that flow in a Hagen-Poiseuille flow in a gradient magnetic field and the trapping characteristics of the magnetic particles by means of multi-pairs of magnetic poles. Brownian dynamics simulations were performed in order to clarify the dependence of the trapping characteristics on a variety of factors such as the magnetic interaction between particles, the strength of a non-uniform magnetic field, the strength of the flow field and the separation distance between two pairs of magnetic poles. The main results obtained here are summarized as follows. An increase in the magnetic field strength improves the trapping characteristics of disk-like particles if the influence of an applied magnetic field is sufficiently more dominant than that of a flow field and also that of the magnetic particle-particle interaction. In the case of a strong magnetic particle-particle interaction, thin chain-like clusters are formed from an anchored particle trapped around a magnetic pole. Moreover, if the separation distance between the two poles is sufficiently near, an arch-type cluster is formed between the magnetic poles, and is located in a vicinity area nearer to the wall surface due to the influence of a flow field. For the case of a small aspect ratio rp=3, in the situation that the particle volumetric fraction is constant, an arch-type cluster formed between the magnetic poles can remain trapped in the vicinity of the wall surface even under the influence of the strong flow field. Hence, we understand that the use of disk-like particles with a small aspect ratio may be able to improve the trapping performance of particles.

Abstract Spinocerebellar ataxia (SCA) type 17-digenic TBP/STUB1 disease (SCA17-DI) has been recently segregated from SCA17, caused by digenic inheritance of two gene mutations – intermediate polyglutamine-encoding CAG/CAA repeat expansions (polyQ) in TBP (TBP 41 − 49) and STUB1 heterozygosity – the former being associated with SCA17, and the latter with SCA48 and SCAR16 (autosomal recessive). In SCA17, most patients carry intermediate TBP 41 − 49 alleles but show incomplete penetrance, and the missing heritability can be explained by a new entity whereby TBP 41 − 49 requires the STUB1 variant to be symptomatic. The STUB1 gene encodes the chaperone-associated E3 ubiquitin ligase (CHIP) involved in ubiquitin-mediated proteasomal control of protein homeostasis. However, reports of the neuropathology are limited and role of STUB1 mutations in SCA17-DI remain unknown. Here we report the clinicopathologic features of identical twin siblings, one of whom was autopsied and was found to carry an intermediate allele (41 and 38 CAG/CAA repeats) in TBP and a heterozygous missense mutation in STUB1 (p.P243L). These patients developed autosomal recessive Huntington’s disease-like symptoms. Brain MRI showed diffuse atrophy of the cerebellum and T2WI revealed hyperintense lesions in the basal ganglia and periventricular deep white matter. The brain histopathology of the patient shared features characteristic of SCA17, such as degeneration of the cerebellar cortex and caudate nucleus, and presence of 1C2-positive neurons. Here we show that mutant CHIP fails to generate the polyubiquitin chain due to disrupted folding of the entire U box domain, thereby affecting the E3 activity of CHIP. When encountering patients with cerebellar ataxia, especially those with Huntington’s disease-like symptoms, genetic testing for STUB1 as well as TBP should be conducted for diagnosis of SCA17-DI, even in cases of sporadic or autosomal recessive inheritance.

Abstract Background Each direct oral anticoagulant (DOAC) has different dose reduction criteria. Here, we evaluated the differences in the doses of three anti‐Xa DOACs and clinical events based on the dose reduction criteria in patients with atrial fibrillation (AF). Methods Consecutive AF patients prescribed with anti‐Xa DOACs [rivaroxaban (Riva), apixaban (Apix), and edoxaban (Edox)] between April 2011 and May 2016 were retrospectively evaluated. The incidences of thromboembolic and bleeding events were evaluated by the end of December 2020, focusing on the dose proportion. Results A total of 786 patients (72 ± 10 years old, 66.9% male) were enrolled in this study [Riva (n = 337), Apix (n = 239), and Edox (n = 210)]. The proportion of reduced dose prescriptions was significantly greater for Edox (79.2%) than Riva (38.7%) or Apix (31.9%). A Kaplan–Meier analysis showed that the incidence of minor bleeding was significantly higher in the Apix than other groups (p

Abstract Urodele amphibians, Pleurodeles waltl and Ambystoma mexicanum, have organ-level regeneration capability, such as limb regeneration. Multipotent cells are induced by an endogenous mechanism in amphibian limb regeneration. It is well known that dermal fibroblasts receive regenerative signals and turn into multipotent cells, called blastema cells. However, the induction mechanism of the blastema cells from matured dermal cells was unknown. We previously found that BMP2, FGF2, and FGF8 (B2FF) could play sufficient roles in blastema induction in urodele amphibians. Here, we show that B2FF treatment can induce dermis-derived cells that can participate in multiple cell lineage in limb regeneration. We first established a newt dermis-derived cell line and confirmed that B2FF treatment on the newt cells provided plasticity in cellular differentiation in limb regeneration. To clarify the factors that can provide the plasticity in differentiation, we performed the interspecies comparative analysis between newt cells and mouse cells and found the Pde4b gene was upregulated by B2FF treatment only in the newt cells. Blocking PDE4B signaling by a chemical PDE4 inhibitor suppressed dermis-to-cartilage transformation and the mosaic knockout animals showed consistent results. Our results are a valuable insight into how dermal fibroblasts acquire multipotency during the early phase of limb regeneration via an endogenous program in amphibian limb regeneration.

Background: Carcinoma cuniculatum (CC) is a rare subtype of squamous cell carcinoma that is difficult to diagnose owing to the lack of cellar atypia and/or associated oral epithelial dysplasia. The prognosis is good given proper resection, but it often has a poor prognosis with recurrence. We present the case of a 78-year-old man who visited our department with an ulcer around the implant in tooth 35. With Nikolsky’s phenomenon in the gingiva, a detailed examination revealed pemphigus vulgaris. Steroid administration remarkably improved the oral symptoms but caused osteomyelitis and rapid bone destruction, leading to pathological fracture. After multiple biopsies, mandibular segment resection was performed with a diagnosis of mandibular osteomyelitis, and no malignant findings were found. Four months later, the wound reopened, a white keratinized lesion appeared, and a biopsy revealed CC. Unresectable tumor infiltration was already observed, but the patient died of aspiration pneumonia 15 months after diagnosis. Conclusions: It took 20 months to make a definitive diagnosis of CC in this case. Pemphigus vulgaris may have made the diagnosis particularly difficult. Since other CCs are often diagnosed with osteomyelitis or odontogenic keratocyst preoperatively, we recommend keeping in mind the possibility of CC in refractory cases.

In the present study, we have addressed a dispersion composed of magnetic cubic particles in an alternating magnetic field to investigate the time change in the local internal structure of particle aggregates by means of quasi-two-dimensional Brownian dynamics simulations. An alternating magnetic field is applied along the x-direction. In the situation of a relatively weak magnetic field, if the magnetic particle-particle interaction strength is small, single particles remain in the system. The magnetic moments of single particles follow the change in the switched direction of the alternating magnetic field. As the magnetic particle-particle interaction strength is increased, particles aggregate to form closely-packed structures with a perfect face-to-face configuration. Since the orientation of the magnetic moments of constituent particles is strongly restricted due to the influence of the magnetic particle-particle interaction between neighboring particles, they do not follow the change in the alternating magnetic field direction. As the magnetic particle-field interaction strength is increased, closely-packed structures tend to collapse, and loosely-packed structures are formed in the system. As the magnetic particle-field interaction strength is further increased, the magnetic moments of constituent particles are restricted to the direction of the alternating magnetic field. Therefore, the aggregates with an offset face-to-face configuration are formed along the magnetic field direction. If the alternating magnetic field switches from the positive x-direction to the negative x-direction, the aggregates with an offset face-to-face configuration collapse temporarily because the magnetic moments reorient in the switched direction of the alternating magnetic field. After that, the orientation of the magnetic moments is strongly restricted to the switched magnetic field direction, and aggregates with an offset face-to-face configuration are re-formed in the system.

A 47-year-old right-handed man was admitted to our hospital for rehabilitation after right basal ganglion hematoma. On day 57, he noticed a supernumerary motor phantom limb (SPL) involving his right arm, originating at the level of the elbow. The most notable finding of his SPL was the motor characteristic. When the subject had the intention to move the upper paralyzed limb simultaneously with the trainer’s facilitating action, he said “there is another arm.” The intention to move the paralyzed arm alone or passive movement of the paralyzed arm did not induce the SPL. He showed a severe left sensorimotor impairment and mild hemineglect, but no neglect syndromes of the body (e.g., asomatognosia, somatoparaphrenia, personification and misoplegia, or anosognosia) were observed. Brain MRI demonstrated a hematoma in the right temporal lobe subcortex, subfrontal cortex, putamen, internal capsule, and thalamus. Single-photon emission computed tomography images showed more widespread hypoperfusion in the right hemisphere in comparison to the lesions on MRI. However, the premotor cortex was preserved. Our case is different from Staub’s case in that SPL was not induced by the intention to move the paralyzed limb alone; rather, it was induced when the patient intended to move the paralyzed limb with a trainer’s simultaneous facilitating action. The SPL may reflect that an abnormal closed-loop function of the thalamocortical system underlies the phantom phenomenon. However, despite the severe motor and sensory impairment, the afferent pathway from the periphery to the premotor cortex may have been partially preserved, and this may have been related to the induction of SPL.

Abstract The presence of nerves is an important factor in successful organ regeneration in amphibians. The Mexican salamander, Ambystoma mexicanum, is able to regenerate limbs, tail, and gills when nerves are present. However, the nerve-dependency of tooth regeneration has not been evaluated. Here, we reevaluated tooth regeneration processes in axolotls using a three-dimensional reconstitution method called CoMBI and found that tooth regeneration is nerve-dependent although the dentary bone is independent of nerve presence. The induction and invagination of the dental lamina were delayed by denervation. Exogenous Fgf2, Fgf8, and Bmp7 expression could induce tooth placodes even in the denervated mandible. Our results suggest that the role of nerves is conserved and that Fgf+Bmp signals play key roles in axolotl organ-level regeneration. The presence of nerves is an important factor in successful organ regeneration in amphibians. The Mexican salamander, Ambystoma mexicanum, is able to regenerate limbs, tail, and gills when nerves are present. However, the nervedependency of tooth regeneration has not been evaluated. Here, we reevaluated tooth regeneration processes in axolotls using a three-dimensional reconstitution method called CoMBI and found that tooth regeneration is nerve-dependent although the dentary bone is independent of nerve presence. The induction and invagination of the dental lamina were delayed by denervation. Exogenous Fgf2, Fgf8, and Bmp7 expression could induce tooth placodes even in the denervated mandible. Our results suggest that the role of nerves is conserved and that Fgf+Bmp signals play key roles in axolotl organ-level regeneration.

In the present study, we have attempted to investigate a feasibility of exhibiting a significant trapping performance by means of multi-pairs of magnetic poles. We here focus on the two representative types of configurations using two pairs of magnetic poles. That is, the first is a vertical configuration of two pairs of magnetic poles, where each pair of magnetic poles is arranged perpendicular to the flow direction, and the second is a parallel configuration, where each pair of magnetic poles is arranged along the wall surface of a circular cylinder. As in the previous study for one pair of magnetic poles, we have here investigated the behavior of magnetic rod-like particles in a Hagen-Poiseuille flow, by means of Brownian dynamics, in the above-mentioned two pairs of magnetic poles, which induce magnetic forces to function to trap magnetic particles around the magnetic poles. In the case of the vertical arrangement of the two pairs of magnetic poles, a largely-packed aggregate is trapped between the first pair of magnetic poles, and this trapping characteristic is reproduced between the second pair of magnetic poles. In this case, these large clusters are mainly formed in the center area of the cylinder perpendicular to the flow direction. In contrast, for the case of the parallel arrangement, a largely-packed cluster is formed between a pair of magnetic poles and located along the wall surface. Different from the previous arrangement of magnetic poles, this largely-packed cluster may sufficiently survive and be trapped between the poles by shifting the position nearer to the wall surface. From these results, we suggest that the parallel arrangement of magnetic poles gives rise to a better trapping performance.

In the present study, we have addressed a suspension composed of magnetic cubic particles in a rotating magnetic field by means of quasi-two-dimensional Brownian dynamics simulations in order to investigate the dependence of the regime change on a variety of factors such as the magnetic particle-particle interaction strength, the magnetic particle-field interaction strength and the frequency of the rotating magnetic field. If the magnetic particle-particle interaction strength is relatively small, single particles remain without aggregating to form specific clusters, and the magnetic moments of single particles tend to rotate with the rotating magnetic field. If the magnetic particle-particle interaction strength is predominant, the particles aggregate to form closely-packed face-to-face structures, and the magnetic moments of constituent particles cannot follow a change in the rotating magnetic field. As the magnetic field strength is increased, closely-packed structures start to be transformed into aggregate structures with an offset face-to-face configuration. An increase in the frequency of the rotating magnetic field induces a significant regime change in the aggregate structures. Under the rotating magnetic field with low frequency, the particles aggregate to form elongated clusters with an offset face-to-face configuration along the magnetic field direction, and the cluster itself rotates to follow the change in a rotating magnetic field. From these results, we conclude that a regime change in the aggregate structure of cubic particle in a rotating magnetic field may be induced by various factors such as the magnetic particle-particle interaction strength, the magnetic particle-field interaction strength, and the frequency of the magnetic field.

Background Recent clinical trials have demonstrated the possible pleiotropic effects of SGLT2 (sodium–glucose cotransporter 2) inhibitors in clinical cardiovascular diseases. Atrial electrical and structural remodeling is important as an atrial fibrillation (AF) substrate. Methods and Results The present study assessed the effect of canagliflozin (CAN), an SGLT2 inhibitor, on atrial remodeling in a canine AF model. The study included 12 beagle dogs, with 10 receiving continuous rapid atrial pacing and 2 acting as the nonpacing group. The 10 dogs that received continuous rapid atrial pacing for 3 weeks were subdivided as follows: pacing control group (n=5) and pacing+CAN (3 mg/kg per day) group (n=5). The atrial effective refractory period, conduction velocity, and AF inducibility were evaluated weekly through atrial epicardial wires. After the protocol, atrial tissues were sampled for histological examination. The degree of reactive oxygen species expression was evaluated by dihydroethidium staining. The atrial effective refractory period reduction was smaller (P=0.06) and the degree of conduction velocity decrease was smaller in the pacing+CAN group compared with the pacing control group (P=0.009). The AF inducibility gradually increased in the pacing control group, but such an increase was suppressed in the pacing+CAN group (P=0.011). The pacing control group exhibited interstitial fibrosis and enhanced oxidative stress, which were suppressed in the pacing+CAN group. Conclusions CAN and possibly other SGLT2 inhibitors might be useful for preventing AF and suppressing the promotion of atrial remodeling as an AF substrate.

We report a clinical case of a patient with hereditary angioedema (HAE, Type III) in which, by implementing careful preoperative preparations to prevent the occurrence of edema, good course was achieved without the prophylactic administration of C1-inhibitor (C1–INH). We recommended the prophylactic administration of Berinert P, a human plasma-derived C1–INH formulation; however, due to the risk of developing a viral infection, both the patient and her mother refused to receive Berinert P. In cases where C1–INH cannot be administered as a prophylactic measure, it is essential to make sufficient preparations, including urgent tracheotomy, to prevent sudden occurrence of edema, with the cooperation of the anesthesiologist.

In the present study, we have treated a suspension composed of magnetic cubic particles in a simple shear flow situation in order to investigate the dependence of the magnetorheological properties on the aggregate structures by means of Brownian dynamics simulations. An external magnetic field is applied in the direction normal to the simple shear flow. The main results obtained here are summarized in the following. In a weak applied magnetic field, the cubic particles aggregate to form the closely-packed clusters if the magnetic particle-particle interaction strength is sufficiently large. The closely-packed clusters are transformed into chain-like clusters with increasing magnetic field strength. These chain-like clusters tend to incline in the flow field direction from the magnetic field direction. Since the chain-like clusters give rise to a large resistance to the flow field, the net viscosity of the suspension is increased. As the magnetic field strength is further increased, wall-like structures along the magnetic field direction are formed in the system. In this situation, the force to accelerate the flow field arises due to the characteristic of the particle arrangement within the wall-like clusters, which induces a decrease in the net viscosity. From these results, we conclude that the magnetorheological effect depends on the internal structures of the aggregates formed in the system. Moreover, we suggest that a cubic hematite particle dispersion may have negative magnetorheological characteristics under the certain conditions.

Abstract Background Intercalary pattern formation is an important regulatory step in amphibian limb regeneration. Amphibian limb regeneration is composed of multiple steps, including wounding, blastema formation, and intercalary pattern formation. Attempts have been made to transfer insights from regeneration-competent animals to regeneration-incompetent animalsat each step in the regeneration process. In the present study, we focused on the intercalary mechanism in chick limb buds. In amphibian limb regeneration, a proximodistal axis is organized as soon as a regenerating blastema is induced. Intermediate structures are subsequently induced (intercalated) between the established proximal and distal identities. Intercalary tissues are derived from proximal tissues. Fgf signaling mediates the intercalary response in amphibian limb regeneration. Results We attempted to transfer insights into intercalary regeneration from amphibian models to the chick limb bud. The zeugopodial part was dissected out, and the distal and proximal parts were conjunct at st. 24. Delivering ectopic Fgf2 + Fgf8 between the distal and proximal parts resulted in induction of zeugopodial elements. Examination of HoxA11 expression, apoptosis, and cell proliferation provides insights to compare with those in the intercalary mechanism of amphibian limb regeneration. Furthermore, the cellular contribution was investigated in both the chicken intercalary response and that of axolotl limb regeneration. Conclusions We developed new insights into cellular contribution in amphibian intercalary regeneration, and found consistency between axolotl and chicken intercalary responses. Our findings demonstrate that the same principal of limb regeneration functions between regeneration-competent and -incompetent animals. In this context, we propose the feasibility of the induction of the regeneration response in amniotes.

Background: Cardiac troponin T (cTnT) has been reported to be associated with cardiac mortality. In the present study, we evaluated the role of routine assessment of cTnT as a predictor of future cardiac death in patients with left ventricular (LV) dysfunction. Methods: Patients who were eligible for prophylactic implantable cardioverter defibrillator (ICD) were included from cardiac catheterization database. Inclusion criteria were patients with LV ejection fraction of ≤ 35% and with New York Heart Association (NYHA) ≥class II. Exclusion criteria were patients with acute coronary syndrome, ICD for secondary prevention, NYHA class IV, and lack of data. The final study patients were divided into the following three groups in accordance with two quartile points of serum cTnT levels: low cTnT, intermediate cTnT, and high cTnT groups. The primary endpoint of this study was cardiac death. Results: A total of 70 patients were included (mean age, 62±13 years; male individuals, 56; ischemic, 36; and non-ischemic, 34). During the observation period of 2.2 years, cardiac death was observed in 17 patients (fatal arrhythmic event, 9; heart failure, 7; myocardial infarction, 1). In the Kaplan–Meier analysis, the high cTnT group showed the highest risk among all the groups (p

Background: Catheter ablation of premature ventricular complexes (PVCs) has been used as a curative therapy in many cases. Intracardiac ultrasound with a magnetic sensor probe has recently become available for catheter ablation. In this study, we assessed a new mapping method, contraction mapping, for determining the optimal ablation sites using intracardiac ultrasound and M-mode. This study sought to assess the accuracy of the new mapping method using intracardiac echocardiography. Methods: Eighteen patients (10 males and eight females; mean age, 63±12 years) with 104 mapping points diagnosed as idiopathic PVCs were included in this study. At the mapping points, the time interval from the onset of the QRS to the onset of the contraction (QRS-c-time) and the local activation time were measured using M-mode with an intracardiac echo probe and using the conventional method. The correlation between the QRS-c-time and local activation time were studied. Results: The QRS-c-time was significantly correlated with the local activation time (activation time=−66.8+0.882 * QRS-c-time, R2=0.728, p

A seventy year-old male was referred to our hospital to undergo radiofrequency catheter ablation (RFCA) for drug-refractory paroxysmal atrial fibrillation (AF). Pre-operative three-dimensional computed tomography revealed a unique left atrial (LA) roof vein. Electrophysiological findings showed expansion of the myocardial sleeve and local firing in the LA roof vein. We performed isolation of this arrhythmogenic abnormal vein concomitant with general pulmonary vein isolation in this case, and AF did not recur after the procedure.

A 54-year-old female showed amorphagnosia without ahylognosia and tactile agnosia 40 days after the onset of right cerebral infarction. Her basic somatosensory functions were normal. The appreciation of substance qualities (hylognosia) was preserved, but the patient’s inability to recognize the size and shape (morphagnosia) was confined to 2- and 3-dimensional shapes (amorphagnosia) in the left hand. However, the patient’s ability to recognize real daily objects was well preserved. Brain MRI after admission showed ischemic lesions confined to the right pre- and postcentral gyri and the medial frontal cortex on DWI and FLAIR images. An analysis of SPECT images revealed that the most decreased areas were localized to the pre- and postcentral gyri, superior and inferior parietal lobules, supramarginal gyrus, and angular gyrus. Considering the previous reported cases, the responsible lesion for the impaired perception of hylognosia and morphagnosia may not necessarily be confined to the right hemisphere. To date, 5 reports (6 cases) of tactile agnosia have been published; 4 cases presented with both ahylognosia and amorphagnosia, while 1 presented with only amorphagnosia, and another showed amorphagnosia and mild ahylognosia. Our case is the first to present with only amorphagnosia without tactile agnosia. The mechanism for the well-preserved recognition of real objects may depend on the preserved hylognosia. Of note, there have been no reports showing only ahylognosia without amorphagnosia. Further studies are necessary to clarify whether or not patients with preserved hylognosia or morphagnosia retain the ability to perceive real objects.

In the present study, we propose a new repulsive layer model in order to establish Brownian dynamics simulations for cube-like particles, although various repulsive layer models have been proposed by other researchers. In order to verify the validity of Brownian dynamics simulations with this repulsive interaction model, we address a suspension composed cubic hematite particles in an equilibrium situation. The results obtained here are summarized in the following. In the case of the ordinary model by Donaldson et al., the accuracy and the CPU time of simulations are significantly dependent on the number Nsph of spherical particles filling up one side of cube-like particle. As the value of Nsph is increased, the simulation time becomes more prohibitive although we can expect to obtain more accurate results. From the comparison in respect to the results of the orientational correlation function, we understood that the model with Nsph=3 exhibits quite different results in comparison with Monte Carlo results. This is because the corners and sides of the cubic particles cannot be modeled with sufficient accuracy in the case of Nsph=3. On the other hand, the model with larger values of Nsph tends to give rise to better agreement with Monte Carlo results. We may therefore conclude that the model of Nsph=5 or Nsph=7 should be used in order to obtain simulation results with sufficient accuracy if using their repulsive moled. In the case of our model, the simulation time corresponds to their model of Nsph=3, and the accuracy of simulation results is very similar to that for the models of Nsph=5 and Nsph=7. If considering the simulation time and the accuracy of the simulation results, we may conclude that our model has more significant advantage to the ordinary models in simulations for a suspension of magnetic cube-like particles.

We have developed a simple assessment method for the overlap between spheroidal particles, which is indispensable for performing particle-based simulations of a colloidal suspension. In the present assessment method, the position giving rise to the deepest overlap point between the steric layers of two spheroidal particles is evaluated by using the inscribed sphere of the spheroid that is moved on the major axis line for scanning the surface-to-surface distance of these two spheroids in an effective manner. Moreover, we have developed an evaluation method for the interaction energy due to the overlap of the steric layers covering spheroidal particles. This is based on a sphere-connected particle model, but some modifications are introduced in order to express an appropriate repulsive interaction energy at the deepest overlapping position. Then we have investigated phase change problems in a magnetic spheroidal particle suspension in a two-dimension system by means of Monte Carlo simulations where both the above-mentioned assessment method and the evaluation method for the repulsive interaction energy are combined. In the case of no external magnetic field, as the area fraction is decreased from a large value where chcain-like clusters are formed in the whole area of the system, this internal strucuture changes into raft-like one in a narrow range of the area fraction. Raft-like clusters are preferred in a weak applied magnetic field, but an increase in the field strength induces the phase change from raft-like into chain-like structure.

In the present study, we have analyzed the flow field around a cube in a Stokes flow regime in order to estimate the diffusion coefficients of cube-like particles that are required for performing Brownian dynamics simulations of a cubic particle suspension. The main results obtained here are summarized as follows. In the situation of a uniform flow field with a Reynolds number sufficiently smaller than unity, the force acts on the cube only in the flow field direction, and the torque does not act on the cube. Therefore, the uniform flow does not induce the rotational motion of the cube. In the situation of a rotational flow field with a sufficiently low Reynolds number, the torque acts on the cube only in the direction of angular velocity of the rotational flow field, and the force does not act on the cube. This implies that the translational motion of the cube is not induced due to the rotational flow field. These characteristics are in good agreement with those for the case of spheres in a Stokes flow situation. From these results, we may conclude that the diffusion coefficients of the cube-like particles can be expressed by applying a correction factor to those of the spherical particles. Moreover, we understand that the translational and the rotational motion of a cube are not coupled in the condition of the flow filed with a low Reynolds number sufficiently smaller than unity. Furthermore, in Brownian dynamics simulations, the equations of translational and rotational motion of cube-like particles can be treated in the same way as the spherical particles by applying the correction factor.

Ventricular capture management is an automatic pacing threshold adjustment algorithm that automatically measures pacing threshold through detection of the evoked response after a pacing stimulus. Although it is principally designed to save device battery under the maintenance of the patient׳s safety, we experienced a rare case with serious pacing failure due to a weakness of this algorithm. This pacing failure might be explained by a large variation in the ventricular pacing threshold depending on the atrioventricular interval and daily variation of pacing threshold and concomitant steroid use in this patient. Keywords: Automatic pacing threshold adjustment algorithm, Pacing failure

We have addressed a suspension composed of magnetic cubic particles, which have a magnetic dipole moment at the particle center magnetized along the diagonal direction of the cube, in order to elucidate the physical phenomenon of the attachment characteristics and the aggregation structure of these particles, by means of Monte Carlo simulations. The cubic particles are negatively charged and confined between the two parallel walls one of which is positively charged (i.e., electrode) and the other is connected to the ground. The main results obtained here are summarized as follows. In the case of no external magnetic field, if the magnetic interaction is sufficiently strong for the formation of stable chain-like clusters, then longer chain-like clusters are formed between the two parallel walls and these clusters are more significantly located along the surface of the electrode as the electric interaction strength is increased. In the case of the electric particle-wall interaction being stronger than the magnetic interaction, almost all constituent cubic particles of chain-like clusters more significantly attach to the surface of the electrode in a face-to-face contact manner between the face of the cube and the wall. To the contrary, if the magnetic interaction is stronger than the electric interaction, the chain-like clusters are formed in the space of the two parallel walls from the end particle attached to the electrode wall. In the case of an external magnetic field applied along the surface of the electrode wall, the chain-like clusters are formed and extended from the surface to the space of the two parallel walls with the end of the particle of the clusters attached to the electrode wall.

In the previous study, we investigated the adsorption phenomenon where the adsorption agent or spherical particles adsorb turbidity-causing (TC) particles in the sedimentation process in the gravitational field by means of Brownian dynamics simulations. These results may certainly contribute to the development of a technology for improving the visibility in small lakes and ponds. We here extend the previous study to an adsorption agent of non-spherical particles where the particle rotational Brownian motion is significantly expected to contribute to the adsorption performance in addition to the translational Brownian motion. Hence, we have employed the modelling of adsorption particles as large spherocylinder particles and TC particles as small spherical particles with a sub-micron size in order to perform Brownian dynamics simulations. For the case of a large aspect ratio rp =15, in the situation that the particle volumetric fraction is constant, the adsorption rate is much better than spherical particles by 75% improvement, and therefore it is seen that the rotational Brownian motion of the rod-like particles gives rise to a much more significant adsorption performance. From these results, we understand that the use of rod-like particles with a large aspect ratio as adsorption agents can adsorb TC substances much more efficiently in comparison with spherical particles.

We have elucidated the aggregation phenomena in a suspension composed of spherical magnetic particles in an alternating magnetic field by means of Brownian dynamics method. The relationship between aggregate structures and heating phenomena has been discussed using the hysteresis loops of the magnetic field-magnetization curves, which were obtained from Brownian dynamics simulations. A large heating effect is inevitably necessary in applying a magnetic particle suspension to magnetic hyperthermia treatment in the medical engineering field. We here focus on the Brownian relaxation mode of magnetic moments of particles as the factor inducing the heating effect. The main results obtained here are summarized as follows. In the situation where stable chain-like clusters are formed in the field direction, the magnetic particle-particle interaction induces a significant delay for the magnetic moments inclining in the alternating magnetic field direction. These chain-like clusters respond to a change in the magnetic field without collapse and reformation of the clusters, by the magnetic moment of each constituent particle rotating to incline in the field direction. These behaviors of chain-like clusters in an alternating magnetic field exhibit a hysteresis loop with large area in the magnetic filed-magnetization curve, which gives rise to a significantly large heating effect. On the other hand, in the situation where large clusters are formed but these clusters do not strongly tend to incline in the field direction, the area of the hysteresis loop becomes small and therefore a large heating effect cannot be obtained.

In the present study we have performed lattice Boltzmann simulations of an electro-conjugate fluid in order to elucidate the mechanism for inducing a strong microjet between positive and negative electrodes in the situation of a high external electric field. It has been assumed that charges are injected from the surface of a positive electrode where electric fields are significantly concentrated. The mechanism due to these injected charges has mainly been assessed as an essential factor for the occurrence of a strong microjet. In the present numerical simulations, the lattice Boltzmann equations and the basic equation for charge densities have simultaneously been solved for obtaining the flow field and the charge density distribution, respectively. The main results obtained here are summarized as follows. A strong microjet is possibly generated between the positive and the ground electrodes in the situation where Coulomb forces are much more dominant than viscous forces. A microjet starts to occur at the position of the injected charges, grows along with the fluid flow, collides with the ground electrode, and flows away from the electrode in an oblique direction relative to the center line connected between the electrodes. The flow rate induced due to the occurrence of a strong microjet increases approximately in proportion to the increasing external electric field strength. From good agreement with the corresponding experimental result in regard to the velocity vectors of a microjet, we may conclude that the mechanism for inducing a strong microjet in an electro-conjugate fluid is the interaction between the injected charges from the positive electrode and a high external electric field.

In order to apply the multi-particle collision dynamics (MPCD) method to a magnetic particle suspension, we have elucidated the dependence of the translational and rotational Brownian motion of magnetic particles on the MPCD parameters that characterize the MPCD simulation method. We here consider a three-dimensional system composed of magnetic spherical particles in thermodynamic equilibrium. The diffuse reflection model has been employed for treating the interactions between fluid and magnetic particles. In the diffuse reflection model, the interactions between fluid and magnetic particles are transferred into the translational motion more strongly than into the rotational motion of magnetic particles. The employment of relatively small simulation time steps gives rise to a satisfactory level of the translational Brownian motion. The activation level of the Brownian motion is almost independent of both the size of the unit collision cell and the number of fluid particles per cell. Larger values of the maximum rotation angle induce stronger translational and rotational Brownian motion, but in the present magnetic particle suspension the range of θmax≲π/2 seems to be reasonable. We may conclude that the MPCD method with the simple diffuse reflection model is a feasible simulation technique as the first approximation for analyzing the behavior of magnetic particles in a suspension. If more accurate solutions regarding the aggregate structures of magnetic particles are required, the introduction of the scaling coefficient regarding the interactions between fluid and magnetic particles can yield more accurate and physically reasonable aggregate structures in both a qualitative and quantitative meanings.

We have investigated a regime change in the aggregate structures of a suspension composed of magnetic cubic particles in thermodynamic equilibrium, by means of Monte Carlo simulations. In concrete, we have addressed the dependence of the regime change on a variety of factors such as the magnetic field strength and the magnetic particle-particle interaction strength. The orientational distribution function and order parameters have been focused on for quantitatively discussing these characteristics. The main results obtained here are summarized as follows. If the magnetic interaction strength is sufficiently large for cluster formation, closely-packed clusters are formed under the combination and expansion of a cluster unit composed of 8 particles. A regime change in the internal structure of aggregates appears in a narrow range of the magnetic interaction strength, which is clearly exhibited by the order parameter employed here. A closely-packed configuration can be clearly characterized by the orientational distribution function; 8 high peaks appear in the orientational space in the case of the closely-packed structure. As the magnetic field is increased, the closely-packed clusters are collapsed and transformed into wall-like clusters along the magnetic field direction. This is because the magnetic moment of each particle has a strong tendency to incline in the magnetic field direction in the situation of a strong magnetic field.

In the present study, we focus on a ferromagnetic rod-like particle suspension to discuss the dependence of the magneto-rheological properties on the regime of aggregates of the magnetic rod-like particles. To do so, we here adopted Brownian dynamics simulations in a simple shear flow situation, in order to investigate this dependence in various situations. The main results obtained here are summarized as follows. In a weak applied magnetic field, the particles tend to aggregate to form raft-like clusters if the magnetic particle-particle interaction is sufficiently larger than thermal motion. As the magnetic field is increased, these raft-like clusters change into chain-like clusters and finally grow into wall-like clusters along the magnetic field direction. These wall-like clusters give rise to much larger resistance to the flow field than single-moving particles (and also than chain-like clusters). Moreover, the wall-like and thick chain-like clusters become more resistant than raft-like clusters, which leads to larger values of the net viscosity. From the present results, we conclude that the viscosity due to magnetic properties of rod-like particles exhibits complex dependence on the regime of particle aggregate structures such as raft-like, chain-like and wall-like clusters, which is strongly influenced by the magnetic field strength, the magnetic particle-particle interaction strength and the shear rate.