ZAC: Efficient Zero-Knowledge Dynamic Universal Accumulator and Application to Zero-Knowledge Elementary Database

—Zero-knowledge universal accumulator generates the succinct commitment to a set and produces the short (non) membership proof (universal) without leaking information about the set (zero-knowledge). In order to further support a generic set and zero-knowledge, existing techniques generally combine the zero-knowledge universal accumulator with other protocols, such as digital signatures and hashes to primes, which incur high overhead and may not be suitable for real-world use. It is desirable to commit a set of membership concealing the information with the optimal complexity. We devise ZAC, a new zero-knowledge Dynamic Universal Accumulator by taking the existing cryptographic primitives into account to produce a new efficient accumulator. Our underlying building blocks are Bloom Filter and vector commitment scheme in [19], utilizing the binary expression and aggregation to achieve efficiency, generic set support, zero-knowledge and universal properties. As a result, our scheme is improved in terms of proof size and proof time, also comparable to the RSA-based set accumulator in [8] in the verifying complexity. With 128 bit security, our proof size is 48 bytes while theirs is 1310 bytes and the running time of elliptic curve-based methods is faster than RSA-based counterpart. ZAC is proved to be complete, ϵ-sound and zero-knowledge. Extensively, based on ZAC as building block, we construct a new Zero-Knowledge Elementary Database (ZKEDB), which consumes 5 times less storage space, O(log N) less bandwidth, and O(log N) more efficient in proving and verification than the state-of-art work in [13] (where N is the domain space size). ZKEDB is proved to be complete, ϵ-sound and zero-knowledge. ZKEDB supports a new type of select top ℓ query, and can be extended to non-elementary databases

Study protocol: Early neurological deterioration in patients with minor stroke, frequency, predictors, and outcomes in Vietnam single-centre study

Early neurological deterioration (END) is progressive neurological deterioration with an increase in NIHSS score of 2 points or more in the first 72 hours from the onset of acute ischemic stroke. END increases the risk of poor clinical outcomes at day 90 of ischemic stroke. We will study the frequency, predictors, and outcomes of patients with END in a case-control study at a comprehensive stroke centre in Vietnam. of the design is a descriptive observational study, longitudinal follow-up of patients with minor stroke hospitalized at the Stroke Center of Bach Mai Hospital from December 1, 2023, to December 1, 2024. Minor stroke patients characterized by NIHSS score ≤ 5 hospitalized within 24 hours of symptom onset will be recruited. The estimated END rate is about 30%, relative accuracy ε = 0.11, 95% reliability, expected 5% of patients lost data or follow-up, and an estimated sample size of 779 patients. This study will help determine the END rate in patients with minor stroke and related factors, thereby building a prognostic model for END. Our study determined the END rate in patients with minor stroke in Vietnam and also proposed risk factors for minor stroke management and treatment

Cyanide detoxification efficiency of injection and soak of hydroxocobalamin, sodium nitrite and sodium thiosulfate for sea water ornamental fish

The Oceanographic Museum offers interesting exhibits of several marine lives for tourist sightseeing and entertainment. These sea water ornamental fish are all caught in the wild. However, its health can be affected by cyanide poisoning during human fishing. Depending on the level of cyanide poisoning, fish can die after one and two weeks that caused economic damages for the museum. The present study is concerned with results of cyanide detoxification by using direct injection into cinnamon clownfish or soak of hydroxocobalamin, sodium nitrite and sodium thiosulfate with the aim of improving the health, survival and life time for fish, contributing to increasing economic efficiency for the Oceanographic Museum

NICKEL-BASED MULTIWALLED CARBON NANOTUBE COMPOSITE COATINGS

Carbon nanotubes (CNTs) have been widely known as nanomaterials with excellent mechanical properties. Previous studies reported that the tensile strength of multi-walled carbon nanotubes (MWCNTs) was up to 63 GPa and single-walled carbon nanotubes (SWCNTs) could reach 150 GPa while the highest tensile strength of the steel was found to be about 1.8 GPa. SWCNTs could have Young’s modulus up to 1000 GPa that was much greater than the value of 209 GPa of steel. Therefore, there is a great potential to utilize CNTs as reinforced materials for composites in general and Ni electrodeposition coating in particular to improve hardness, durability, corrosion, and other physical and mechanical properties. This paper presents results of preparing and examining characteristics of the Nickel electrodeposition coatings containing MWCNTs (Ni-MWCNTs). The Ni-MWCNTs composite coatings deposited on a steel plate with the area of 0.4 dm2 using bipolar pulses at 470 Hz and 50oC in a 5-liter bath. Amount of CNTs varying from 1 g/l to 3 g/l was dispersed into the solution by using surfactants and ultrasonic vibration. CNTs used in the study was MWCNTs diameters in the range from 20 to 90 nanometers and few micrometers in length. The SEM, EDS, hardness and adhesion tests were conducted to analyze the properties of the electrodeposition coatings. The obtained results indicated that the hardness and adhesion of the Ni-CNTs coating were 1.5 and 1.46 times, respectively, higher than those of the Ni coating. In addition, adhesion of the Ni-CNTs coating was significantly improved

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Contributions to functional encryption and its applications

Access control plays an important role in many information systems. Embedding policy-based access control into modern encryption schemes is an interesting but challenging task that has been intensively studied by the cryptographic research community in recent years. Furthermore, most of encryption schemes require not only the guarantee of security, but also the efficiency in terms of computational and communication cost when producing ciphertext and secret key. In this thesis, we study Functional Encryption comprising its subclasses such as Attribute Based Encryption, Hidden Vector Encryption, and Inner Product Encryption. We boost the advantage of these encryption schemes by improving their performance, which is critical for real applications. We also consider the user anonymity in these encryption systems in order to protect user privacy, which is very important nowadays. This thesis has five major contributions. First, we construct two Attribute Based Encryption schemes for achieving the constant ciphertext size and hidden ciphertext policy. Second, by combining Attribute Based Encryption and Broadcast Encryption, we construct Attribute Based Broadcast Encryption schemes with short ciphertext and short decryption key. Third, We also explore the anonymity of Attribute Based Broadcast Encryption supporting multi-gate access structures. Fourth, we propose two ciphertext policy hidden vector encryption schemes with constant-size ciphertext, and attribute hiding. Both of our proposed schemes achieve the efficiency and exibility. Finally, we construct a new type of fuzzy public key encryption, called Edit Distance-based Encryption, based on the Edit Distance which is a very useful tool to measure the similarity between two strings. In our constructions, we define the access policy by applying the Boolean AND Gates Access Structure with positive, negative attributes including wildcard; OR- AND Gates with positive, negative attributes. We also develop techniques to bridge Attribute Based Encryption, Attribute Based Broadcast Encryption with Inner Product Encryption, and then use the latter to achieve the goal of hidden access policy. All of our proposed schemes are proven secure under standard assumptions

Hidden ciphertext policy attribute-based encryption under standard assumptions

We propose two new ciphertext policy attribute-based encryption (CP-ABE) schemes where the access policy is defined by AND-gate with wildcard. In the first scheme, we present a new technique that uses only one group element to represent an attribute, while the existing ABE schemes of the same type need to use three different group elements to represent an attribute for the three possible values (namely, positive, negative, and wildcard). Our new technique leads to a new CP-ABE scheme with constant ciphertext size, which, however, cannot hide the access policy used for encryption. The main contribution of this paper is to propose a new CP-ABE scheme with the property of hidden access policy by extending the technique we used in the construction of our first scheme. In particular, we show a way to bridge ABE based on AND-gate with wildcard with inner product encryption and then use the latter to achieve the goal of hidden access policy. We prove that our second scheme is secure under the standard decisional linear and decisional bilinear Diffie-Hellman assumptions