Electrical performance of amorphous IGZO thin-film transistor on cellulose nanopaper substrate

Plastics are commonly used as substrates for flexible electronics today, but they cause significant impact to the environment. Paper has been considered as an alternative owing to their low cost, flexibility, biodegradability and recyclability. However, paper substrates are vulnerable to high temperature and/or wet processes. Therefore, most reported on-paper electronics were fabricated by using printing processes, transfer processes, and/or shadow-masking deposition techniques. In this work, amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) were demonstrated on cellulose nanopaper substrates via a photolithography-compatible direct-fabrication method. The paper substrate was formed by drop-casting suspension containing cellulose nanofibers and cellulose nanocrystals on a rigid carrier substrate. A buffer layer consisting of parylene, SiNx, SiO2 and Al2O3 was then deposited to protect the paper substrate against processing gases and chemicals. To avoid deterioration of the cellulose nanopaper substrate, a low-temperature process of £ 150°C was developed. Fig. 1(a) shows the micrograph of a-IGZO TFTs made on a cellulose nanopaper substrate. The channel width and length are 60 μm and 30 μm, respectively. Figs. 1(b), (c), and (d) illustrate the transfer characteristics, output characteristics and linear field-effect mobility as a function gate voltage of an a-IGZO TFT fabricated on a cellulose nanopaper substrate. The on-paper TFT exhibits a field-effect mobility mobility of 4.23 cm2V-1s-1, on/off current ratio of 2.17× 107, threshold voltage of 4.35 V and subthreshold swing of 0.695 V/dec. The result paves a way toward large-area-compatible and scalable flexible green electronics productions. Please click Download on the upper right corner to see the full abstract

Attribute-Based Encryption from Identity-Based Encryption

Ciphertext-policy attribute-based encryption (CP-ABE) is an access control mechanism where a data provider encrypts a secret message and then sends the ciphertext to the receivers according to the access policy which she/he decides. If the attributes of the receivers match the access policy, then they can decrypt the ciphertext. This paper shows a relation between ABE and identity-based encryption (IBE), and presents a bi-directional conversion between an access structure and identities. By the proposed conversion, the ABE scheme constructed from an IBE scheme will inherit the features, such as constant-size ciphertexts and anonymity, from the IBE scheme, and vice versa. It turns out that the proposed conversion also gives the first ABE achieving access structures with wildcard and constant-size ciphertexts/private keys

Fast Keyword Search over Encrypted Data with Short Ciphertext in Clouds

Nowadays, it is convenient for people to store their data on clouds. To protect the privacy, people tend to encrypt their data before uploading them to clouds. Due to the widespread use of cloud services, public key searchable encryption is necessary for users to search the encrypted files efficiently and correctly. However, the existing public key searchable encryption schemes supporting monotonic queries suffer from either infeasibility in keyword testing or inefficiency such as heavy computing cost of testing, large size of ciphertext or trapdoor, and so on. In this work, we first propose a novel and efficient anonymous key-policy attribute-based encryption (KP-ABE). Then by applying Shen et al.\u27s generic construction proposed to the proposed anonymous KP-ABE, we obtain an efficient and expressive public key searchable encryption, which to the best of our knowledge achieves the best performance in testing among the existing such schemes. Only 2 pairings is needed in testing. Besides, we also implement our scheme and others with Python for comparing the performance. From the implementation results, our scheme owns the best performance on testing, and the size of ciphertexts and trapdoors are smaller than most of the existing schemes

Analyzing Personal Happiness from Global Survey and Weather Data: A Geospatial Approach

Past studies have shown that personal subjective happiness is associated with various macro- and micro-level background factors, including environmental conditions, such as weather and the economic situation, and personal health behaviors, such as smoking and exercise. We contribute to this literature of happiness studies by using a geospatial approach to examine both macro and micro links to personal happiness. Our geospatial approach incorporates two major global datasets: representative national survey data from the International Social Survey Program (ISSP) and corresponding world weather data from the National Oceanic and Atmospheric Administration (NOAA). After processing and filtering 55,081 records of ISSP 2011 survey data from 32 countries, we extracted 5,420 records from China and 25,441 records from 28 other countries. Sensitivity analyses of different intervals for average weather variables showed that macro-level conditions, including temperature, wind speed, elevation, and GDP, are positively correlated with happiness. To distinguish the effects of weather conditions on happiness in different seasons, we also adopted climate zone and seasonal variables. The micro-level analysis indicated that better health status and eating more vegetables or fruits are highly associated with happiness. Never engaging in physical activity appears to make people less happy. The findings suggest that weather conditions, economic situations, and personal health behaviors are all correlated with levels of happiness

Arcula: A Secure Hierarchical Deterministic Wallet for Multi-asset Blockchains

This work presents Arcula, a new design for hierarchical deterministic wallets that brings identity-based addresses to the blockchain. Arcula is built on top of provably secure cryptographic primitives. It generates all its cryptographic secrets from a user-provided seed and enables the derivation of new public keys based on the identities of users, without requiring any secret information. Unlike other wallets, it achieves all these properties while being secure against privilege escalation. We formalize the security model of hierarchical deterministic wallets and prove that an attacker compromising an arbitrary number of users within an Arcula wallet cannot escalate his privileges and compromise users higher in the access hierarchy. Our design works out-of-the-box with any blockchain that enables the verification of signatures on arbitrary messages. We evaluate its usage in a real-world scenario on the Bitcoin Cash network

Cryptanalysis on Chang-Yang-Hwang Protected Password Change Protocol

Recently, Chang et al. proposed an authenticated key agreement and protected password change scheme. They claimed that their scheme is simple and efficient. However, in this letter we point out that their protected password change protocol is insecure under the denial-of-service attack and the dictionary attack in some situations

Online platform for applying space–time scan statistics for prospectively detecting emerging hot spots of dengue fever

Abstract Background Cases of dengue fever have increased in areas of Southeast Asia in recent years. Taiwan hit a record-high 42,856 cases in 2015, with the majority in southern Tainan and Kaohsiung Cities. Leveraging spatial statistics and geo-visualization techniques, we aim to design an online analytical tool for local public health workers to prospectively identify ongoing hot spots of dengue fever weekly at the village level. Methods A total of 57,516 confirmed cases of dengue fever in 2014 and 2015 were obtained from the Taiwan Centers for Disease Control (TCDC). Incorporating demographic information as covariates with cumulative cases (365 days) in a discrete Poisson model, we iteratively applied space–time scan statistics by SaTScan software to detect the currently active cluster of dengue fever (reported as relative risk) in each village of Tainan and Kaohsiung every week. A village with a relative risk >1 and p value <0.05 was identified as a dengue-epidemic area. Assuming an ongoing transmission might continuously spread for two consecutive weeks, we estimated the sensitivity and specificity for detecting outbreaks by comparing the scan-based classification (dengue-epidemic vs. dengue-free village) with the true cumulative case numbers from the TCDC’s surveillance statistics. Results Among the 1648 villages in Tainan and Kaohsiung, the overall sensitivity for detecting outbreaks increases as case numbers grow in a total of 92 weekly simulations. The specificity for detecting outbreaks behaves inversely, compared to the sensitivity. On average, the mean sensitivity and specificity of 2-week hot spot detection were 0.615 and 0.891 respectively (p value <0.001) for the covariate adjustment model, as the maximum spatial and temporal windows were specified as 50% of the total population at risk and 28 days. Dengue-epidemic villages were visualized and explored in an interactive map. Conclusions We designed an online analytical tool for front-line public health workers to prospectively detect ongoing dengue fever transmission on a weekly basis at the village level by using the routine surveillance data

Unified theory for Goos-H\"{a}nchen and Imbert-Fedorov effects

A unified theory is advanced to describe both the lateral Goos-H\"{a}nchen (GH) effect and the transverse Imbert-Fedorov (IF) effect, through representing the vector angular spectrum of a 3-dimensional light beam in terms of a 2-form angular spectrum consisting of its 2 orthogonal polarized components. From this theory, the quantization characteristics of the GH and IF displacements are obtained, and the Artmann formula for the GH displacement is derived. It is found that the eigenstates of the GH displacement are the 2 orthogonal linear polarizations in this 2-form representation, and the eigenstates of the IF displacement are the 2 orthogonal circular polarizations. The theoretical predictions are found to be in agreement with recent experimental results.Comment: 15 pages, 3 figure