•Morphodynamics of alternate bars under unsteady discharge is investigated.•repeated specific hydrographs lead to an equilibrium of alternate bars.•This equilibrium state causes non-time dependent ...wavelength and migration periods.•Under this state, the migration period becomes identical to the hydrograph cycle.•Relation between hydrodynamics and bar growth controls this state.
Discharge unsteadiness plays a key role in the dynamics of alternate bars, however, how migrating alternate bars determine their shape under unsteady discharge conditions, especially in the long-term, is still unclear. In this study, we numerically investigate long-term behaviors of migrating alternate bars subject to repeated hydrographs. For this, the same discharge variation but different hydrograph cycles were tested. The results show that even under unsteady flow conditions, specific combinations of hydrograph cycles and discharge variations result in an equilibrium state of migrating alternate bars (i.e., non-time dependent wavelength and migration period). This may be a unique feature of the alternate bar morphodynamics, since dynamic equilibrium state arising from steady discharge counterparts is time-dependent feature. Meanwhile, it is observed that when the discharge changes abruptly, the response of alternate bar morphodynamics changes along the time. Within a limited period, the response of alternate bars is not strong enough to destroy the original wavelength, suggesting that the hydrograph cycle that achieves this equilibrium state must be moderately long such that the timescale of the hydrograph is similar but slightly smaller than the bar growth.
In recent years, the frequency of torrential rains has increased due to abnormal weather conditions. Torrential rains have caused extensive flooding damage in many areas. As delays in evacuation can ...pose a threat to life, a quick search for safe evacuation routes has become more important than ever before. In this study, we constructed a new system for searching evacuation routes that incorporates a function that varies the weight of each road in the route search depending on the distance from the flooded area D and the distance that the flood area extends in 10 min D′ (i.e., the flood’s inundation speed). We conducted multiple hypothetical flood simulations with different locations of levee breaches and shelters in the study site (Obihiro City, Japan). Then, we compared the results with the conventional system that does not include the proposed function. The results showed that the system proposed in this study increased the number of successful evacuees by up to 2.16 times compared to the conventional system. In our system, the weight function is set to the Cd power of D/D′; increasing the model parameter Cd selects a route that detours more of the flooded area. The model parameter Cd that maximizes the number of successful evacuees is roughly constant, regardless of the locations of the levee breaches or shelters in the study site.
Objective This study analyzed the clinical and laboratory parameters that might influence the clinical outcomes of patients with type 2 diabetes who develop diabetic ketoacidosis (DKA), which has not ...been well investigated. Methods We reviewed the clinical and laboratory data of 158 patients who were hospitalized due to DKA between January 2006 and June 2019 and compared the data of patients stratified by the type of diabetes. In addition, the patients with type 2 diabetes were subdivided according to age, and their clinical and laboratory findings were evaluated. Results Patients with type 2 diabetes had a longer symptom duration associated with DKA, higher body mass index (BMI), and higher C-peptide levels than those with type 1 diabetes (p<0.05). Among patients with type 2 diabetes, elderly patients (≥65 years old) had a longer duration of diabetes, higher frequency of DKA onset under diabetes treatment, higher effective osmolarity, lower BMI, and lower urinary C-peptide levels than nonelderly patients (<65 years old) (p<0.05). A correlation analysis showed that age was significantly negatively correlated with the index of insulin secretory capacity. Conclusion Patients with DKA and type 2 diabetes had a higher BMI and insulin secretion capacity than those with type 1 diabetes. However, elderly patients with type 2 diabetes, unlike younger patients, were characterized by a lean body, impaired insulin secretion, and more frequent DKA development while undergoing treatment for diabetes.
An 80-year-old man presented at our hospital with renal failure. He had been treated with edoxaban, an oral direct factor Xa inhibitor, for deep vein thrombosis for 10 months prior to admission. ...Although the pulses in his bilateral pedal arteries were palpable, cyanosis was present in the bilateral toes. Laboratory data indicated azotemia and eosinophilia. A skin biopsy confirmed a diagnosis of cholesterol crystal embolism (CCE). Because no invasive vascular procedure was performed, we assumed that CCE was related to edoxaban. To the best of our knowledge, this is the first case report suggesting CCE induced by an Xa inhibitor.
Purpose
A novel cranial phantom was developed to simulate the relationships among factors such as blood perfusion, water diffusion, and biomechanics in intracranial tissue.
Methods
The cranial ...phantom consisted of a high‐density polypropylene filter (mimicking brain parenchyma) with intra‐ and extrafilter spaces (mimicking cerebral artery and vein, respectively), and a capacitor space (mimicking the cerebrospinal fluid space). Pulsatile and steady flow with different flow rates were applied to the cranial phantom using a programmable pump. On 3.0‐T MRI, the measurements of the internal pressure in the phantom, apparent diffusion coefficient (ADC) with monoexponential analysis in the filter, and total simulated cerebral blood flow (tSCBF) into the phantom were synchronized with the pulsatile flow. We obtained their maximum changes during the pulsation period (ΔP, ΔADC, and ΔtSCBF, respectively). Then, the compliance index (CI) was calculated by dividing the volume change (ΔV) by the ΔP in the phantom. Moreover, the same measurements were repeated after the compliance of the phantom was reduced by increasing the water volume in the capacitor space. Under steady flow conditions, we determined the regional SCBF (rSCBF) and perfusion‐related and restricted diffusion coefficients (D* and D, respectively) with biexponential analysis in the filter.
Results
The internal pressure, ADC, and tSCBF varied over the pulsation period depending on the input flow. Moreover, the ΔP, ΔADC, ΔtSCBF, and rSCBF increased with the input flow rate. Compared to the high compliance condition, in the low compliance condition, the ΔP and ΔADC were higher by factors of 2.5 and 1.3, respectively, and the CI was smaller by a factor of 2.7, whereas the ΔV was almost unchanged. The D* was strongly affected by the input flow.
Conclusion
Our original phantom models the relationships among the blood perfusion, water diffusion, and biomechanics of the intracranial tissue, potentially facilitating the validation of novel MRI techniques and optimization of imaging parameters.
To suppress olefinic signals and enable simultaneous and quantitative estimation of multiple functional parameters associated with water and lipid, we investigated a modified method using chemical ...shift displacement and recovery-based separation of lipid tissue (SPLIT) involving acquisitions with different inversion times (TIs), echo times (TEs), and b-values.
Single-shot diffusion echo-planar imaging (SSD-EPI) with multiple b-values (0–3000 s/mm2) was performed without fat suppression to separate water and lipid images using the chemical shift displacement of lipid signals in the phase-encoding direction. An inversion pulse (TI = 292 ms) was applied to SSD-EPI to remove olefinic signals. Consecutively, SSD-EPI (b = 0 s/mm2) was performed with TI = 0 ms and TE = 31.8 ms for T1 and T2 measurements, respectively. Under these conditions, transverse water and lipid images at the maximum diameter of the right calf were obtained in six healthy subjects. T1, T2, and the apparent diffusion coefficients (ADC) were then calculated for the tibialis anterior (TA), gastrocnemius (GM), and soleus (SL) muscles, tibialis bone marrow (TB), and subcutaneous fat (SF). Perfusion-related (D*) and restricted diffusion coefficients (D) were calculated for the muscles. Lastly, the lipid fractions (LF) of the muscles were determined after T1 and T2 corrections.
The modified SPLIT method facilitated sufficient separation of water and lipid images of the calf, and the inversion pulse with TI of 292 ms effectively suppressed olefinic signals. All quantitative parameters obtained with the modified SPLIT method were found to be in general agreement with those previously reported in the literature.
The modified SPLIT technique enabled sufficient suppression of olefinic signals and simultaneous acquisition of quantitative parameters including diffusion, perfusion, T1 and T2 relaxation times, and LF.
•The aim of the study was to investigate a modified method using chemical shift displacement and recovery-based separation of lipid tissue (SPLIT).•The modified SPLIT method involves acquisitions with different inversion times, echo times, and b-values.•Residual olefinic signals can be suppressed using an inversion pulse (inversion time = 292 ms).•This method can provide quantitative parameters including diffusion, perfusion, T1 and T2 relaxation times.
BACKGROUND A non-infectious inflammatory reaction against replaced aortic graft for aortic dissection often manifests as fever, malaise, and peri-graft effusion. It usually lasts less than 1 month ...and subsides spontaneously without immunosuppressive treatment. CASE REPORT A 49-year-old man underwent ascending aorta and total arch replacement for acute thoracic aortic dissection. He had fever, malaise, nausea, and elevated serum C-reactive protein for 1 month postoperatively. Pathological examination of the aorta revealed no aortitis, and repeated blood cultures were negative. We also noted periaortic graft fluid collection, and a small amount of pleural and pericardial effusions. We suspected post-pericardiotomy syndrome. Colchicine and prednisolone were administered, with an excellent clinical response. Three weeks after discontinuation of a 7-week prednisolone treatment, the same symptoms recurred and gradually worsened. Prednisolone was restarted 6 months after the first surgery, with good clinical response. Thereafter, he developed left-sided weakness and dysarthria, being diagnosed as ischemic stroke. Contrast-enhanced computed tomography revealed fluid collection with contrast leak around the aortic grafts, suggesting peel dehiscence, and thrombus formation in anastomotic pseudoaneurysm. He underwent surgical repair. He was diagnosed with non-infectious periaortitis, likely due to an immune reaction to the grafts, based on an excellent clinical response to immunosuppressive therapy. CONCLUSIONS We report a case of non-infectious periaortitis around a thoracic aortic graft, probably with an immune-mediated mechanism, requiring immunosuppressive treatment. When fever persists after aortic graft replacement surgery, non-infectious periaortitis should be considered and immunosuppressive treatment should be considered to prevent critical complications of anastomotic pseudoaneurysm and graft dehiscence.
PDF
