Low-Asymmetry Interface for Multiuser VR Experiences with Both HMD and Non-HMD Users.

We propose a low-asymmetry interface to improve the presence of non-head-mounted-display (non-HMD) users in shared virtual reality (VR) experiences with HMD users. The low-asymmetry interface ensures that the HMD and non-HMD users' perception of the VR environment is almost similar. That is, the point-of-view asymmetry and behavior asymmetry between HMD and non-HMD users are reduced. Our system comprises a portable mobile device as a visual display to provide a changing PoV for the non-HMD user and a walking simulator as an in-place walking detection sensor to enable the same level of realistic and unrestricted physical-walking-based locomotion for all users. Because this allows non-HMD users to experience the same level of visualization and free movement as HMD users, both of them can engage as the main actors in movement scenarios. Our user study revealed that the low-asymmetry interface enables non-HMD users to feel a presence similar to that of the HMD users when performing equivalent locomotion tasks in a virtual environment. Furthermore, our system can enable one HMD user and multiple non-HMD users to participate together in a virtual world; moreover, our experiments show that the non-HMD user satisfaction increases with the number of non-HMD participants owing to increased presence and enjoyment.

Full-band TDM-OPDMA for OBI-reduced simultaneous multiple access in a single-wavelength optical access network.

Simultaneous multiple access (MA) within a single wavelength can increase the data rate and split ratio in a passive optical network while optical beat interference (OBI) becomes serious in the uplink. Previous techniques to reduce OBI were limited by their complexity and lack of extendibility; as well, bandwidth allocation among MA signals is needed for single photo diode (PD) detection. We proposed and experimentally demonstrated full-band optical pulse division multiplexing-based MA (OPDMA) in an optical access network, which can effectively reduce OBI with extendibility and fully utilize frequency resources of optical modulator without bandwidth allocation in a single-wavelength MA.

Laboratory measurement of apixaban using anti-factor Xa assays in acute ischemic stroke patients with non-valvular atrial fibrillation.

Apixaban is effective and safe for preventing stroke, and its usage has increased exponentially in recent years. However, data concerning the therapeutic range of apixaban is limited. This study determined the trough and peak levels of apixaban-specific anti-factor Xa activity (AFXaA) in acute ischemic stroke patients with non-valvular atrial fibrillation (NVAF) in Korea. The study included 85 patients who received apixaban. Blood samples were taken to measure the trough and peak levels of AFXaA using a chromogenic anti-factor assay, as well as prothrombin time (PT) and activated partial thromboplastin time (aPTT). We also reviewed complications such as major bleeding of patients treated with apixaban. In patients given a 5.0-mg apixaban dose, the median trough and peak levels of AFXaA were 104.5 and 202.0 ng/mL. In patients given a 2.5-mg apixaban dose, the median trough and peak AFXaA levels were 76.0 and 151.0 ng/mL. The PT showed a positive correlation with increased AFXaA activity at both levels (Trough R = 0.486, Peak R = 0.592), but the aPTT had no relationship with AFXaA activity at both levels (Trough R = 0.181, Peak R = 0.129). Two cases with intracranial bleeding belonged to the highest AFXaA quartile (Trough, p = 0.176; Peak, p = 0.053). In conclusion, we determined the trough and peak levels of AFXaA in patients with NVAF while being treated with the apixaban in Korea. Our results could be used as a starting point when setting the reference ranges for laboratories using anti-Xa assay. Large-scale studies are needed to establish the reference range for AFXaA in patients with NVAF.

Optical pulse division multiplexing-based OBI reduction for single wavelength uplink multiple access in IM/DD OFDMA-PON.

Orthogonal frequency division multiple access-based passive optical network (OFDMA-PON) is considered as a strong candidate for next-generation optical access network. In intensity modulation/direct detection system, OFDMA-PON downlink transmission is relatively stable, but critical issues exist in uplink multiple access. Because of different optical paths, optical beat interference (OBI) and timing offset effect are generated, which seriously disturb signal detection. We propose optical pulse division multiplexing-based OBI reduction. By considering both the spectrum broadening effect and the time domain near orthogonality, OBI could be reduced. We demonstrate that the spectral efficiency can be improved from 0.37 to 3.8 bit/s/Hz in 1-GHz signal bandwidth.

Cystatin C, a novel indicator of renal function, reflects severity of cerebral microbleeds.

BACKGROUND: Chronic renal insufficiency, diagnosed using creatinine based estimated glomerular filtration rate (GFR) or microalbumiuria, has been associated with the presence of cerebral microbleeds (CMBs). Cystatin C has been shown to be a more sensitive renal indicator than conventional renal markers. Under the assumption that similar pathologic mechanisms of the small vessel exist in the brain and kidney, we hypothesized that the levels of cystatin C may delineate the relationship between CMBs and renal insufficiency by detecting subclinical kidney dysfunction, which may be underestimated by other indicators, and thus reflect the severity of CMBs more accurately. METHODS: Data was prospectively collected for 683 patients with ischemic stroke. The severity of CMBs was categorized by the number of lesions. Patients were divided into quartiles of cystatin C, estimated GFR and microalbumin/creatinine ratios. Ordinal logistic regression analysis was used to examine the association of each renal indicator with CMBs. RESULTS: In models including both quartiles of cystatin C and estimated GFR, only cystatin C quartiles were significant (the highest vs. the lowest, adjusted OR, 1.88; 95% CI 1.05-3.38; p = 0.03) in contrast to estimated GFR (the highest vs. the lowest, adjusted OR, 1.28; 95% CI 0.38-4.36; p = 0.70). A model including both quartiles of cystatin C and microalbumin/creatinine ratio also showed that only cystatin C quartiles was associated with CMBs (the highest vs. the lowest, adjusted OR, 2.06; 95% CI 1.07-3.94; p = 0.03). These associations were also observed in the logistic models using log transformed-cystatin C, albumin/creatinine ratio and estimated GFR as continuous variables. Cystatin C was a significant indicator of deep or infratenorial CMBs, but not strictly lobar CMBs. In addition, cystatin C showed the greatest significance in c-statistics for the presence of CMBs (AUC = 0.73 ± 0.03; 95% CI 0.66-0.76; p = 0.02). CONCLUSION: Cystatin C may be the most sensitive indicator of CMB severity among the renal disease markers.

Microguidewire protection of wide-necked aneurysms incorporating orifices of tortuous acute-angled vessels: a novel approach.

INTRODUCTION: Protective/remodeling techniques for treating wide-necked intracranial aneurysms are constantly sought. However, their utility may be limited in lesions that incorporate the orifice of acute-angled efferent branch vessels. Furthermore, passage of a protective microcatheter may be challenging if a small branch is extremely tortuous. This study was conducted to explore a novel method of treating wide-necked aneurysms, utilizing microguidewire protection. METHODS: A microcatheter is first passed into parent artery (proximal to aneurysm) to position a microguidewire proximally in the involved branch. A second microcatheter is then inserted into aneurysmal sac. Advancement of the first microcatheter forces the microguidewire to shift, thus covering aneurysmal neck. A framing coil may then be placed within aneurysmal sac, under microguidewire protection. After completing initial coil insertion, easing of tension on the microcatheter allows separation of protective microguidewire and frame coil, confirming stability of the initial coil. RESULTS: This technique was applied to 11 intracranial saccular aneurysms of M1 segment (n=6), middle cerebral artery bifurcation (n=4), and anterior communicating artery (n=1) with success, combining stent protection in two patients. Coil embolization was thus facilitated, resulting in excellent outcomes for all patients. No morbidity or mortality was directly related to microguidewire protection. CONCLUSION: Our small study suggests that microguidewire protection may be a safe alternative, if traditional remodeling or protective options are infeasible due to intrinsic vascular properties. This technique is particularly suited for treatment of wide-necked aneurysms where passage of protective microcatheters into involved branches is not achievable.

Endovascular treatment for superior cerebellar artery aneurysms: morphological features, technique, and outcome.

INTRODUCTION: Superior cerebellar artery (SCA) aneurysms have distinctive morphologic configurations and vascular origins. Herein, we have analyzed the angioarchitectural characteristics of SCA aneurysms and outcomes achieved through endovascular treatment. METHODS: Data accruing prospectively from January, 2002 to September, 2013 yielded 53 SCA aneurysms in 53 patients. Each lesion was classified as either basilar artery (BA), BA-SCA, or SCA type, according to the nature of incorporated vasculature. Clinical and morphologic outcomes were assessed, with emphasis on technical aspects of treatment. RESULTS: Angles formed by SCA and posterior cerebral artery were obtuse (124.8 ± 29.1°) on sides ipsilateral to aneurysms, differing significantly from contralateral counterparts (44.8 ± 22.0°) (p<0.001). The most common type of aneurysm was BA-SCA (54.7 %), followed by SCA (28.3 %) and BA (17.0 %), and BA type aneurysms were the largest in size. Steam-shaped S-configured microcatheters (n=19, 67.9 %) facilitated aneurysm selection for approach via contralateral vertebral artery (n=28), whereas pre-shaped 45/90/J microcatheters (n=21, 84.0 %) primarily were used for ipsilateral vertebral artery approach (n=25). Single-microcatheter technique (52.8 %) was most often applied, followed by double-microcatheter (34.0 %), stent-assisted (9.4 %), and microcatheter-protection techniques (3.8 %). Aneurysmal occlusion was satisfactorily achieved in 45 lesions (82.1 %), with no procedure-related morbidity and mortality. In follow-up monitoring of 46 patients for a mean period of 25.8 ± 24.4 months, only a single instance of major recanalization (2.2 %) occurred. CONCLUSION: Coil embolization of SCA aneurysms is a safe and effective treatment modality, enabling individualized procedural strategies to accommodate distinctive angio-anatomic configurations.

Coil embolization in precommunicating (A1) segment aneurysms of anterior cerebral artery.

INTRODUCTION: Precommunicating (A1) segment aneurysms of the anterior cerebral artery are rare and often pose technical challenges for coil embolization due to their distinctive configurations. Clinical and radiologic outcomes of treating such aneurysms through endovascular coil embolization are presented herein. METHODS: Data accruing prospectively from May 2002 to August 2013 yielded 48 patients harboring 50 A1 segment aneurysms, each classified as proximal, middle, or distal by location. Clinical outcome of the patients and morphological outcome of the aneurysms were assessed, with emphasis on technical aspects of treatment. RESULTS: The aneurysms studied occupied either proximal (n = 39), middle (n = 6), or distal (n = 5). Proximal aneurysms were largely directed posteriorly (80 %), and most (97 %) were devoid of branches. Middle and distal aneurysms were associated with the medial lenticulostriate artery, cortical branches, or fenestrations. The preshaped "S" and steam-shaped "S" microcatheters facilitated aneurysm selection in 60 % of lesions. Single-microcatheter technique was most commonly applied for coil embolization (62 %), followed by balloon protection (16 %). Successful aneurysmal occlusion could be achieved in 76 % of the patients, with no procedure-related morbidity and mortality. At final follow-up (mean interval, 29.9 months), stable aneurysmal occlusion was sustained in 93 % of the patients (40/43). CONCLUSION: A1 segment aneurysms are amenable to safe and efficacious endovascular coil embolization by adjusting procedural strategy to accommodate distinctive anatomic configurations.

The Rescue on Reperfusion Damage in Cerebral Infarction by Nelonemdaz (RODIN) Trial: Protocol for a Double-Blinded Clinical Trial of Nelonemdaz in Patients with Hyperacute Ischemic Stroke and Endovascular Thrombectomy.

BACKGROUND AND PURPOSE: Nelonemdaz (Neu2000) has both selective antagonism against 2B subunit of N-methyl-D-aspartate receptor and antioxidant activity. This drug provides sufficient evidence of neuroprotection in acute cerebral ischemia/reperfusion models. This phase III trial aims to determine this effect in patients. DESIGN: The Rescue on Reperfusion Damage in Cerebral Infarction by Nelonemdaz is a multicenter, double-blinded clinical trial. A total of 496 patients will be randomly assigned into the nelonemdaz (a total of 5,250 mg divided by 10 times for 5 days) and placebo groups. Patients will be included if they have an acute ischemic stroke (National Institutes of Health Stroke Scale score ≥8) caused by intracranial large vessel occlusion in the anterior circulation (Alberta Stroke Program Early CT Score ≥4), and if they are expected to undergo endovascular thrombectomy within 12 hours after stroke onset. ENDPOINTS: The primary endpoint is a favorable shift in the modified Rankin Scale (mRS) score at 90 days after the first dose of drug. The data will be analyzed by the Cochran-Mantel-Haenszel shift test. The secondary endpoints include functional independence (mRS 0-2) at 35 and 90 days, the favorable shift of mRS at 35 days, the proportion of mRS 0 at 35 and 90 days, and the occurrence rates of symptomatic intracranial hemorrhage within 7 days. CONCLUSION: This trial will clarify the efficacy and safety of nelonemdaz in patients with acute ischemic stroke and endovascular thrombectomy. This study has been registered at ClinicalTrials. gov (NCT05041010).

Optimal use of antithrombotic agents in ischemic stroke with atrial fibrillation and large artery atherosclerosis.

BACKGROUND: Optimal antithrombotic regimens to prevent recurrent stroke in patients with ischemic stroke due to atrial fibrillation (AF) and atherosclerotic large-vessel stenosis remain unknown. AIMS: This study aimed to evaluate the effect of multiple antithrombotic therapies on outcomes at 1 year after ischemic stroke due to two or more causes. METHODS: We identified 862 patients with ischemic stroke due to AF and large artery atherosclerosis from the linked data. These patients were categorized into three groups according to antithrombotic therapies at discharge: (1) antiplatelets, (2) oral anticoagulants (OAC), and (3) antiplatelets plus OAC. The study outcomes were recurrent ischemic stroke, composite outcomes for cardiovascular events, and major bleeding after 1 year. Inverse probability of treatment weighting (IPTW) was used to balance the three groups using propensity scores. RESULTS: Among 862 patients, 169 (19.6%) were treated with antiplatelets, 405 (47.0%) were treated with OAC, and 288 (33.4%) were treated with antiplatelets and OAC. After applying IPTW, only OAC had a significant beneficial effect on the 1-year composite outcome (hazard ratio (HR): 0.37, 95% confidence interval (CI): 0.23-0.60, p < 0.001) and death (HR: 0.35, 95% CI: (0.19-0.63), p < 0.001). The combination of antiplatelet agents and OAC group had an increased risk of major bleeding complications (HR: 5.27, 95% CI: (1.31-21.16), p = 0.019). However, there was no significant difference in 1-year recurrent stroke events among the three groups. CONCLUSION: This study demonstrated that OAC monotherapy was associated with lower risks of composite outcome and death in patients at 1 year after ischemic stroke due to AF and atherosclerotic stenosis. In addition, the combination of an antiplatelet and OAC had a high risk of major bleeding.

Morphological Adaptation after Bilateral Lung Transplantation in a Patient with Kartagener Syndrome: A Case Report.

Kartagener syndrome (KS) is a rare disease with an incidence of 1 in 20,000 to 30,000 births. There is no cure for KS, and conservative medical treatments are used to relieve symptoms and prevent disease progression. Lung transplantation (LT) is the only treatment option for end-stage KS. Since patients with KS have anatomical abnormalities such as situs inversus totalis, which often require surgery to correct, most reports are related to surgical techniques. Reports about morphological adaptations and changes in transplanted lung structure after LT in patients with KS are rare. We performed LT in a patient with KS and observed morphological adaptation of the lungs for 6 months on chest computed tomography using a quantitative evaluation tool (Chest Image Platform; Harvard University Disability Resources, Cambridge, MA, USA).

Control of Femoral Cannulation with a ProGlide Pre-Closure Device during Cardiac Surgery: Is It Reliable?

BACKGROUND: The use of ProGlide as a percutaneous vascular closure device in cardiac surgery remains inconclusive. This study investigated the clinical outcomes of using Pro- Glide in the percutaneous cannulation of femoral vessels in adult cardiac surgery. METHODS: From September 2017 to July 2018, 131 consecutive patients underwent femoral vessel cannulation during cardiac surgery. The ProGlide (Abbott Vascular Inc., Santa Clara, CA, USA) with percutaneous cannulation was used in 118 patients (mean age, 55.7±15.5 years). The accessibility of femoral cannulation was evaluated through preoperative computed tomography. For cannulation, sonography was routinely used. The postoperative ankle-brachial index (ABI) was used to evaluate femoral artery stenosis. RESULTS: Of the 118 patients, 112 (94.9%) and 6 (5.1%) underwent minimally invasive cardiac surgery and median sternotomy, respectively. Most femoral cannulations were performed on the right side (98.3%) using 15F to 19F arterial cannulas. The technical success rate of cannulation with ProGlide was 99.2%, with no delayed bleeding or cannulation site-related complications during hospitalization. During follow-up, only 1 patient showed femoral artery stenosis with claudication and was treated with interventional balloon angioplasty. The postoperative ABI revealed no significant difference in functional stenosis between the cannulation and non-cannulation sides (n=86; cannulation vs. non-cannulation, 1.2±0.1 vs. 1.1±0). CONCLUSION: Percutaneous femoral cannulation with ProGlide was safe and feasible in adult cardiac surgery. This technique may be a good alternative option in patients requiring femoral vessel cannulation for cardiac surgery.

Persistent fifth aortic arch associated with aortic coarctation: a case of surgical correction without artificial material.

BACKGROUND: Persistent fifth aortic arch (PFAA) is a rare anomaly often associated with aortic coarctation or interruption, and various surgical techniques for this anomaly have been reported. Herein, we show a case of an infant with PFAA and severe aortic coarctation. CASE PRESENTATION: A 41-day-old female infant was admitted for sustained fever. Initially, the patient was diagnosed with bacterial meningitis, and echocardiography showed PFAA with severe aortic coarctation. Because the patient presented progressive oliguria and metabolic acidosis, she was transferred for emergency cardiac surgical intervention. The aortic arch was reconstructed using end-to-side anastomosis between the fifth aortic arch and the descending aorta without any artificial conduit or patching material. CONCLUSIONS: PFAA with aortic coarctation can be repaired by various surgical methods. Among them, our surgical approach is easy and effective, has growth potential, and an additional surgery is not needed.

Cardiac myxoma misdiagnosed as infective endocarditis: a case of Carney complex.

BACKGROUND: Infective endocarditis and cardiac myxoma have common features including fever, systemic embolism and intra-cardiac masses. For this reason, these diseases are often misdiagnosed one for another despite proper imaging studies. Herein, we report a case of suspected infective endocarditis in a patient with acute stroke, fever and a mass adjacent to the mitral valve. CASE PRESENTATION: A 24-year-old male patient presented with recurrent fever and stroke. In view of a history of Cushing syndrome and a mobile mass in the left atrium, infective endocarditis was highly suspected. He was transferred for emergency cardiac surgical intervention. During surgery, intraoperative transesophageal echocardiography revealed a 7 cm mass attached to the interatrial septum. The mass was excised through right mini-thoracotomy and pathological examination confirmed the presence of a myxoma. Based on the above clinical findings and genetic analysis, the diagnosis of Carney complex was confirmed. CONCLUSIONS: Infective endocarditis and cardiac myxoma have common features and can be misdiagnosed. If a young patient presenting with embolic stroke had a history of an endocrine neoplasm, Carney complex should be considered in the differential diagnosis of infective endocarditis.

Endovascular therapy of acute ischemic stroke related to tandem occlusion: comparison of occlusion and severe stenosis of the proximal cervical internal carotid artery.

METHODS: We retrospectively reviewed 42 patients with acute ischemic stroke who underwent endovascular treatment for tandem lesions between January 2011 and April 2017. After dividing the patients into two groups according to lesion type of the proximal cervical ICA (complete occlusion and severe stenosis), we analyzed demographic data, angiographic findings and clinical outcomes. A modified Rankin Scale score ≤2 was defined as a favorable clinical outcome. RESULTS: Of 42 patients, 27 patients (64.3%) had complete occlusion of the cervical ICA, and the remaining 15 had high-grade stenosis. Successful stenting was performed in all patients with favorable clinical outcomes (27/42, 64.3%). Successful reperfusion score (thrombolysis in cerebral infarction ≥2b) was 78.6%; occlusion group (18/27, 66.7%) vs stenosis group (15/15, 100%) of cases. Mean modified Rankin Scale score at 90 days was 2.36 ± 1.83. The rate of favorable clinical outcome was higher in stenosis group (11/15, 73.3%) than that of occlusion group (16/27, 59.3%) with no statistically significant difference (p = 0.506). CONCLUSION: Acute endovascular treatment of carotid artery tandem lesions is a technically feasible and clinically effective intervention regardless of the lesion type in proximal cervical ICA. ADVANCES IN KNOWLEDGE: Our study supports the results of previous studies in which endovascular therapy has a favorable clinical outcome in carotid artery tandem occlusion.

Intracranial Venous Reflux Caused by Occlusion of the Brachiocephalic Vein Mimicking Dural Arteriovenous Fistula.

BACKGROUND: High signal intensity of cerebral venous sinuses on magnetic resonance angiography (MRA) indicates high flow of shunt from arterial blood, suggesting dural arteriovenous fistula (dAVF). Herein, we describe the cases of 2 patients with intracranial venous reflux caused by brachiocephalic vein occlusion (BVO) mimicking dAVF on MRA. CASE DESCRIPTION: Case 1 was a 71-year-old woman who had received arteriovenous graft (AVG) surgery for hemodialysis and presented with headache. MRA depicted high signal intensities in the left jugular vein, inferior petrosal sinus, and ophthalmic vein suggesting intracranial dAVF. However, cerebral angiography revealed intracranial venous reflux through the jugular vein caused by BVO. After balloon angioplasty with stenting for BVO, normal venous drainage was restored and her symptoms resolved. Case 2 was a 62-year-old woman who had received AVG for hemodialysis and was hospitalized due to seizure. MRA revealed high signal intensities of the left transverse-sigmoid sinus and jugular vein, and it was suspected that they were associated with BVO. She did not receive immediate intervention because of her septic condition. The patient ultimately died of fatal intracranial hemorrhage and subarachnoid hemorrhage. CONCLUSIONS: Central venous occlusion may occur in patients with end-stage renal disease who are receiving AVG for hemodialysis. Intracranial venous reflux resulting from BVO can induce various neurologic disorders including intracranial venous hypertension or hemorrhage. Prompt recognition and implementation of endovascular treatment can be beneficial in cases of symptomatic central venous occlusion.

Effects of Carotid Calcification on Restenosis After Carotid Artery Stenting: A Follow-Up Study with Computed Tomography Angiography.

BACKGROUND: Carotid Doppler sonography has been used routinely in the screening for restenosis after carotid artery stenting (CAS) by applying the criteria of flow velocity; however, computed tomography angiography (CTA) enables us to detect restenosis directly and has some advantages that help to overcome the limitations of Carotid Doppler sonography. We aimed to investigate the incidence of restenosis with CTA and to identify factors related to restenosis after CAS. METHODS: We conducted a retrospective study of 225 patients (235 arteries, mean age of 71.9 ± 7.7 years) who had undergone CTA of the neck for the evaluation of restenosis after CAS between July 2002 and June 2012. We assessed the cumulative incidence of restenosis (>50%) and the predictors of restenosis after CAS. RESULTS: During 1064.4 patient-years of follow-up (mean 4.5 years; range 1-9.7 years), the incidence of restenosis was 10.2% (24/235). The cumulative rate of freedom from restenosis was 94.1%, 88.8%, and 86.7% at 1, 3, and 5 years, respectively. The statistically significant factors associated with restenosis after CAS were residual stenosis (adjusted odds ratio 1.07, 95% confidence interval 1.03-1.11, P < 0.01) and high-grade (>50%) calcification (adjusted odds ratio 6.04, 95% confidence interval 1.29-28.36, P = 0.02) on multivariate analysis. CONCLUSIONS: This study revealed that carotid arteries with high-grade calcification were prone to develop restenosis after CAS. Regular follow-up should be performed for the monitoring of restenosis after CAS in patients with highly calcified carotid plaques.

Efficient Representation of Detailed Foam Waves by Incorporating Projective Space.

We propose an efficient framework to realistically simulate foam effects in which 3D water particles from a base water solver are first projected onto 2D screen space in order to reduce computational complexity of finding foam particles. Because foam effects are often created primarily in fast and complicated water flows, we analyze acceleration and curvature values to identify the areas exhibiting such flow patterns. Identified foam particles are emitted in 3D simulation space, and each foam particle is advected by its classified type based on its velocity, thereby capturing the essential characteristics of foam wave motions (e.g., floating waves or scattering bubbles). In addition, we provide an intuitive and flexible mechanism (e.g., user sketch or image) to customize parameters and control the appearance of foam effects while minimizing the occurrence of popping artifacts. Experiments convincingly demonstrate that the proposed approach is efficient and easy to use while delivering high-quality results.

When Bitcoin encounters information in an online forum: Using text mining to analyse user opinions and predict value fluctuation.

Bitcoin is an online currency that is used worldwide to make online payments. It has consequently become an investment vehicle in itself and is traded in a way similar to other open currencies. The ability to predict the price fluctuation of Bitcoin would therefore facilitate future investment and payment decisions. In order to predict the price fluctuation of Bitcoin, we analyse the comments posted in the Bitcoin online forum. Unlike most research on Bitcoin-related online forums, which is limited to simple sentiment analysis and does not pay sufficient attention to note-worthy user comments, our approach involved extracting keywords from Bitcoin-related user comments posted on the online forum with the aim of analytically predicting the price and extent of transaction fluctuation of the currency. The effectiveness of the proposed method is validated based on Bitcoin online forum data ranging over a period of 2.8 years from December 2013 to September 2016.

The Difficulties and Risks of Y-Stent-Assisted Coiling: A Comparison of First and Second Stenting Procedures.

OBJECTIVE: Y-stent-assisted coiling (YSAC) requires multiple device accesses for double stenting. The purpose of this study was to test the hypothesis that second stenting procedures are riskier than first stenting procedures. METHODS: We retrospectively reviewed the medical records of 19 patients with 20 aneurysms undergoing YSAC. Difficulty was determined for each device when the difficulty number was >1. Procedure-based and device-based difficulties were compared between 2 stenting procedures. For second stenting procedures, stent-delivery-catheter difficulties (SDs) in passing through the struts of the first stent were assessed for 3 catheter types, 2 delivery methods, and 3 first-stent types. RESULTS: All YSACs were successful. Difficulties occurred more frequently with second stenting procedures than with first stenting procedures (procedure-based difficulties, 4 [20%] vs. 7 [35%], P = 0.29; device-based difficulties, 4 [9%] vs. 8 [18%], P = 0.19). In second stenting procedures, SDs occurred in 4 (20%) procedures and caused the midportion of the first stent to be bent into aneurysms in 2 of the procedures. Failures following difficulties were observed in only 2 (10%) second stenting procedures, necessitating other methods to complete procedures: 1 of the procedures had SD-related thrombosis leading to morbidity at discharge (modified Rankin Scale score 2). SDs were found only with 1 catheter type (4 of 15; PROWLER SELECT Plus) and 1 delivery method (4 of 15; direct over-the-wire) and not with the other catheter types (Rebar-18 or Excelsior 1018) and the other method (catheter-exchange). SDs were found most frequently with the use of the CODMAN ENTERPRISE stent in first stenting procedures (50%). CONCLUSIONS: In YSAC, second stenting procedures seem riskier than first stenting procedures, particularly when SDs occur. A proper device or delivery method may reduce the risks.