A Comprehensive Approach to User Delegation and Anonymity within Decentralized Identifiers for IoT.

Decentralized Identifiers have recently expanded into Internet of Things devices and are crucial in securing users' digital identities and data. However, Decentralized Identifiers face challenges in scenarios necessitating authority delegation and anonymity, such as when dealing with legal guardianship for minors, device loss or damage, and specific medical contexts involving patient information. This paper aims to strengthen data sovereignty within the Decentralized Identifier system by implementing a secure authority delegation and anonymity scheme. It suggests optimizing verifiable presentations by utilizing a sequential aggregate signature, a Non-Interactive Zero-Knowledge Proof, and a Merkle tree to prevent against linkage and Sybil attacks while facilitating delegation. This strategy mitigates security risks related to delegation and anonymity, efficiently reduces the computational and verification efforts for signatures, and reduces the size of verifiable presentations by about 1.2 to 2 times.

Secure Encapsulation Schemes Using Key Recovery System in IoMT Environments.

Recently, as Internet of Things systems have been introduced to facilitate diagnosis and treatment in healthcare and medical environments, there are many issues concerning threats to these systems' security. For instance, if a key used for encryption is lost or corrupted, then ciphertexts produced with this key cannot be decrypted any more. Hence, this paper presents two schemes for key recovery systems that can recover the lost or the corrupted keys of an Internet of Medical Things. In our proposal, when the key used for the ciphertext is needed, this key is obtained from a Key Recovery Field present in the cyphertext. Thus, the recovered key will allow decrypting the ciphertext. However, there are threats to this proposal, including the case of the Key Recovery Field being forged or altered by a malicious user and the possibility of collusion among participating entities (Medical Institution, Key Recovery Auditor, and Key Recovery Center) which can interpret the Key Recovery Field and abuse their authority to gain access to the data. To prevent these threats, two schemes are proposed. The first one enhances the security of a multi-agent key recovery system by providing the Key Recovery Field with efficient integrity and non-repudiation functions, and the second one provides a proxy re-encryption function resistant to collusion attacks against the key recovery system.

Epidemic Vulnerability Index for Effective Vaccine Distribution against Pandemic.

COVID-19 vaccine distribution route directly impacts the community's mortality and infection rate. Therefore, optimal vaccination dissemination would appreciably lower the death and infection rates. This paper proposes the Epidemic Vulnerability Index (EVI) that quantitatively evaluates the subject's potential risk. Our primary aim for the suggested index is to diminish both infection rate and death rate efficiently. EVI was accordingly designed with clinical factors determining the mortality and social factors incorporating the infection rate. Through statistical COVID-19 patient dataset analysis and social network analysis with an agent-based model that is analogous to a real-world system, we define and experimentally validate the capability of EVI. Our experiments consist of nine vaccination distribution scenarios, including existing indexes which estimate the risk and stochastically proliferate the contagion and vaccine in a 300,000 agent-based graph network. We compared the outcome and variation of the three metrics in the experiments: infection case, death case, and death rate. Through this assessment, vaccination by the descending order of EVI has shown to have a significant outcome with an average of 5.0% lower infection cases, 9.4% lower death cases, and 3.5% lower death rate than other vaccine distribution routes.

Ruptured and unruptured aneurysms of the accessory anterior cerebral artery combined with a blood blister-like aneurysm of the anterior communicating artery.

Anterior communicating artery (Acom) complex and anterior cerebral artery (ACA) are the frequent sites of arterial anomalies. Aneurysms associated with triplicate ACA are rare. Blood blister-like aneurysm (BBA) of the Acom is also very rare. This report presents these two rare types of aneurysms in a 63-year old man who presented with subarchnoid hemorrhage secondary to accessory ACA aneurysmal rupture. During surgery, a BBA of the Acom was also found. Both the aneurysms were treated simultaneously. The BBA bled intraprocedurally but was repaired successfully by neck reconstruction and clipping with the preservation of the parent and the branching arteries. The ruptured accessory ACA aneurysm was clipped together with the artery which had multiple aneurysms distally. For the treatment of a complex aneurysm like this, accurate understanding of the anatomic variations, proper imaging study and extremely careful technique are essential.

Clinical practice guidelines for the medical and surgical management of primary intracerebral hemorrhage in Korea.

The purpose of this clinical practice guideline (CPG) is to provide current and comprehensive recommendations for the medical and surgical management of primary intracerebral hemorrhage (ICH). Since the release of the first Korean CPGs for stroke, evidence has been accumulated in the management of ICH, such as intracranial pressure control and minimally invasive surgery, and it needs to be reflected in the updated version. The Quality Control Committee at the Korean Society of cerebrovascular Surgeons and the Writing Group at the Clinical Research Center for Stroke (CRCS) systematically reviewed relevant literature and major published guidelines between June 2007 and June 2013. Based on the published evidence, recommendations were synthesized, and the level of evidence and the grade of the recommendation were determined using the methods adapted from CRCS. A draft guideline was scrutinized by expert peer reviewers and also discussed at an expert consensus meeting until final agreement was achieved. CPGs based on scientific evidence are presented for the medical and surgical management of patients presenting with primary ICH. This CPG describes the current pertinent recommendations and suggests Korean recommendations for the medical and surgical management of a patient with primary ICH.

Endovascular Treatment of Wide-necked Cerebral Aneurysms with an Acute Angle Branch Incorporated into the Sac: Novel methods of Branch Access in 8 Aneurysms.

PURPOSE: The optimal management of geometrically complex aneurysms remains challenging. The aim of this retrospective study was to evaluate the safety and feasibility of branch-selective technique (BT) in wide-necked aneurysms with an acute angle branch incorporated into the sac. MATERIALS AND METHODS: Eight consecutive patients harboring wide-necked cerebral aneurysms with an incorporated, acute angle branch (mean, 30.4°) underwent coiling over an 18-month period. Dome-to-neck ratio ranged from 0.9 to 1.8 (mean, 1.2). Every procedure utilized BT, i.e., stent- or catheter-assisted coiling through the incorporated branch. RESULTS: Technical success was achieved in all cases. With the aim to avoid the risk of aneurysmal rupture during struggling intraaneurysmal wire navigation, a 'looping method' and retrograde approach of a preshaped 0.014' microcatheter (C or J) was used for branch access in five cases and a 'looping method' and antegrade approach in one case. In the remaining one, just the C-preshape was enough to directly enter the branch without intraaneurysmal wire navigation. Overall, stent-assisted coiling was performed in seven cases, while catheter-assisted coiling was undertaken in one. The only complication was thrombotic posterior inferior cerebellar artery occlusion in one case, which was recanalized after tirofiban infusion. New neurological deficits were not identified in any cases. CONCLUSION: BT seems safe and feasible for wide-necked aneurysms with an acute angle branch incorporated into the sac. The looping method may offer safe access to the incorporated, acute angle branch and should be considered for replacement of the fearful intra-aneurysmal wire navigation.

Bilateral Approach for Stent-assisted Coiling of Posterior Inferior Cerebellar Artery Aneurysms - Two Cases.

Aneurysms of the posterior inferior cerebellar artery (PICA) are rarely encountered. In particular, due to frequent anatomic complexity and the presence of nearby critical structures, PICA origin aneurysms are difficult to treat. However, recent reports of anecdotal cases using advanced endovascular instruments and skills have made the results of endovascular treatment rather outstanding. PICA preservation is the key to a successful endovascular treatment, based on the premise that a PICA origin aneurysm is well occluded. To secure PICA flow, stenting into the PICA would be the best method, however, it is nearly impossible technically via the ipsilateral vertebral artery (VA) if the PICA arose at an acute angle from the sac. In such a case, a bilateral approach for stent-assisted coiling can be a creative method for achievement of two goals of both aneurysm occlusion and PICA preservation: ipsilateral approach for coil delivery and contralateral cross-over approach for stent delivery via a retrograde smooth path into the PICA.

Comparative clinical results of vertebroplasty using jamshidi® needle and bone void filler for acute vertebral compression fractures.

OBJECTIVE: Percutaneous vertebroplasty (PVP) is an effective treatment modality for management of osteoporotic compression fracture. However physicians sometimes have problems of high pressure in cement delivery and cement leakage when using Jamshidi® needle (JN). Bone void filler (BVF) has larger lumen which may possibly diminish these problems. This study aims to compare the radiologic and clinical outcome of JN and BVF for PVP. METHODS: One hundred twenty-eight patients were treated with PVP for osteoporotic vertebral compression fracture (VCF) where 46 patients underwent PVP with JN needle and 82 patients with BVF. Radiologic outcome such as kyphotic angle and vertebral body height (VBH) and clinical outcome such as visual analog scale (VAS) scores were measured after treatment in both groups. RESULTS: In JN PVP group, mean of 3.26 cc of polymethylmethacrylate (PMMA) were injected and 4.07 cc in BVF PVP group (p<0.001). For radiologic outcome, no significant difference in kyphotic angle reduction was observed between two groups. Cement leakage developed in 6 patients using JN PVP group and 2 patients using BVF group (p=0.025). No significant difference in improvement of VAS score was observed between JN and BVF PVP groups (p=0.43). CONCLUSION: For the treatment of osteoporotic VCF, usage of BVF for PVP may increase injected volume of cement, easily control the depth and direction of PMMA which may reduce cement leakage. However, improvement of VAS score did not show difference between two groups. Usage of BVF for PVP may be an alternative to JN PVP in selected cases.

Cerebral hemorrhage after endovascular treatment of bilateral traumatic carotid cavernous fistulae with covered stents.

Bilateral traumatic carotid-cavernous fistulae (TCCFs) is rarely encountered neurovascular disease. For treatment of TCCF, detachable balloons have been widely used. Nowadays, transarterial and/or transvenous coil embolization with placement of covered stents is adopted as another treatment method. We experienced a patient with a bilateral TCCFs who was successfully treated with covered stents. However, cerebral hemorrhage occurred in the bed of previous infarction one day after treatment. Hyperperfusion syndrome was considered as a possible cause of the hemorrhage, so that barbiturate coma therapy was started and progression of hemorrhage was stopped. We emphasize that cerebral hyperperfusion hemorrhage can occur even after successful endovascular treatment of TCCF.

A comparative result of ventriculoperitoneal shunt, focusing mainly on gravity-assisted valve and programmable valve.

OBJECTIVE: Despite rapid evolution of shunt devices, the complication rates remain high. The most common causes are turning from obstruction, infection, and overdrainage into mainly underdrainage. We investigated the incidence of complications in a consecutive series of hydrocephalic patients. METHODS: From January 2002 to December 2009, 111 patients underwent ventriculoperitoneal (VP) shunting at our hospital. We documented shunt failures and complications according to valve type, primary disease, and number of revisions. RESULTS: Overall shunt survival time was 268 weeks. Mean survival time of gravity-assisted valve (GAV) was 222 weeks versus 286 weeks for other shunts. Survival time of programmable valves (264 weeks) was longer than that of pressure-controlled valves (186 weeks). The most common cause for shunt revision was underdrainage (13 valves). The revision rate due to underdrainage in patients with GAV (7 of 10 patients) was higher than that for other valve types. Of 7 patients requiring revision for GAV underdrainage, 6 patients were bedridden. The overall infection rate was 3.6%, which was lower than reported series. Seven patients demonstrating overdrainage had cranial defects when operations were performed (41%), and overdrainage was improved in 5 patients after cranioplasty. CONCLUSION: Although none of the differences was statistically significant, some of the observations were especially notable. If a candidate for VP shunting is bedridden, GAV may not be indicated because it could lead to underdrainage. Careful procedure and perioperative management can reduce infection rate. Cranioplasty performed prior to VP shunting may be beneficial.