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Attribute-based encryption (ABE) is a promising technique for fine-grained access control of encrypted data in a cloud storage, however, decryption involved in the ABEs is usually too expensive for resource-constrained front-end users, which greatly hinders its practical popularity. In order to reduce the decryption overhead for a user to recover the plaintext, Green et al. suggested to outsource the majority of the decryption work without revealing actually data or private keys. To ensure the third-party service honestly computes the outsourced work, Lai et al. provided a requirement of verifiability to the decryption of ABE, but their scheme doubled the size of the underlying ABE ciphertext and the computation costs. Roughly speaking, their main idea is to use a parallel encryption technique, while one of the encryption components is used for the verification purpose. Hence, the bandwidth and the computation cost are doubled. In this paper, we investigate the same problem. In particular, we propose a more efficient and generic construction of ABE with verifiable outsourced decryption based on an attributebased key encapsulation mechanism, a symmetric-key encryption scheme and a commitment scheme. Then, we prove the security and the verification soundness of our constructed ABE scheme in the standard model. Finally, we instantiate our scheme with concrete building blocks. Compared with Lai et al.'s scheme, our scheme reduces the bandwidth and the computation costs almost by half. IndexTerms-Attribute-based encryption, outsourced decryption, verifiability, access control.

The neurocognitive basis of the effect of long-term high altitude exposure on voluntary attention is unclear. Using event related potentials, the high altitude group (people born in low altitude but who had lived at high altitude for 3 years) and the low altitude group (living in low altitude only) were investigated using a voluntary spatial attention discrimination task under high and low perceptual load conditions. The high altitude group responded slower than the low altitude group, while bilateral N1 activity was found only in the high altitude group. The P3 amplitude was smaller in the high altitude compared to the low altitude group only under high perceptual load. These results suggest that long-term exposure to high altitudes causes hemispheric compensation during discrimination processes at early processing stages and reduces attentional resources at late processing stages. In addition, the effect of altitude during the late stage is affected by perceptual load. More than 140 million people live permanently at high altitudes (.2,500 m above sea level) in North, Central, and South America, East Africa, and Asia 1 . As of 2006, approximately 12 million people live permanently on the Qinghai-Tibetan Plateau, and 71.14% of them live between 2,500 to 4,500 m. In addition, hundreds of thousands of people travel from lowland China to the Tibetan plateau every year; about 6 million Han lowland immigrants now live there permanently 2,3 . The largest and most important impact of living in a high altitude is hypoxia, which is caused by a reduction of oxygen in the air, and affects cognition. Sustained exposure to high altitude leads to cognitive decrement, such as impairment in attention, memory, judgment, and emotion 4 . Research has demonstrated that cognitive impairment due to altitude starts at 2,500 m above sea level [5][6][7] , because brain vulnerability to hypoxia increases beginning at 2,500 m 8 . Spatial attention may be particularly affected by high altitude exposure. First, the attentional impairment caused by exposure to high altitudes has been found in behavioral tests of visual attention (e.g., the digit symbol substitution test and visual search task) 9,10 , with slowed reaction times at higher altitudes. Second, previous studies have provided neuroimaging and electrophysiological evidence of the impact of high altitude exposure on the human brain [11][12][13] . In the neuroimaging study, brain areas related to attention processing-including the occipital lobe, parietal lobe, sensory-perceptual regions and frontoparietal attentional networks-were found to be affected by high altitude exposure 13,14 . In the electrophysiological study, the parietal distributed P3, which is crucially involved in maintaining attention, was the event-related potential (ERP) component most significantly affected by hypoxia 11,15 . Specifically, smaller and later P3 component responses have been reported for participants at high altitude than in those at the low altitudes, suggesting that cognitive abilities are sensitiv...

As cloud computing becomes prevalent, more and more sensitive data is being centralized into the cloud by users. To maintain the confidentiality of sensitive user data against untrusted servers, the data should be encrypted before they are uploaded. However, this raises a new challenge for performing search over the encrypted data efficiently. Although the existing searchable encryption schemes allow a user to search the encrypted data with confidentiality, these solutions cannot support the verifiability of searching result. We argue that a cloud server may be selfish in order to save its computation ability or bandwidth. For example, it may execute only a fraction of the search and returns part of the searching result. In this paper, we propose a new verifiable fuzzy keyword search scheme based on the symbol-tree which not only supports the fuzzy keyword search, but also enjoys the verifiability of the searching result. Through rigorous security and efficiency analysis, we show that our proposed scheme is secure under the proposed model, while correctly and efficiently realizing the verifiable fuzzy keyword search. The extensive experimental results demonstrate the efficiency of the proposed scheme.

Abstract. Attribute-Based Encryption (ABE) is one of the promising cryptographic primitives for fine-grained access control of shared outsourced data in cloud computing. However, before ABE can be deployed in data outsourcing systems, it has to provide efficient enforcement of authorization policies and policy updates. However, in order to tackle this issue, efficient and secure attribute and user revocation should be supported in original ABE scheme, which is still a challenge in existing work. In this paper, we propose a new ciphertext-policy ABE (CP-ABE) construction with efficient attribute and user revocation. Besides, an efficient access control mechanism is given based on the CP-ABE construction with an outsourcing computation service provider.

The present work focuses on the hydrodynamics variation and mass transfer characteristics of Taylor flow along long serpentine microchannels with a square cross-section. The volumetric mass transfer coefficient (k L a) is regarded as the transient change value to characterize the gas-liquid mass transfer process of CO 2 in water. All experimental data of Taylor bubble are obtained from 1,000 continuously captured images. An online high-speed imaging method and the unit cell model are adopted in this study. The effects of gas and liquid flow rates, together with microchannel geometry are investigated on Taylor bubble characteristics in terms of length, velocity and the mass transfer performance. Taylor bubble length shrinks and subsequently plateaus out along the flow direction from the T-junction, resulting in the decrease in Taylor bubble velocity. k L a in a unit cell gradually decreases along the serpentine microchannel, and increases as the channel cross-sectional area decreases. As the gas flow rate increases under a given liquid flow rate, a critical point is found for the evolution of k L a and k L

To investigate the effects of high-altitude exposure on response inhibition, event-related potential (ERP) components N2 and P3 were measured in Go/NoGo task. The participants included an ‘immigrant’ high-altitude group (who had lived at high altitude for three years but born at low altitude) and a low-altitude group (living in low altitude only). Although the behavioural data showed no significant differences between the two groups, a delayed latency of NoGo-N2 was found in the high-altitude group compared to the low-altitude group. Moreover, larger N2 and smaller P3 amplitudes were found in the high-altitude group compared to the low-altitude group, for both the Go and NoGo conditions. These findings suggest that high-altitude exposure affects response inhibition with regard to processing speed during the conflict monitoring stage. In addition, high altitude generally increases the neural activity in the matching step of information processing and attentional resources. These results may provide some insights into the neurocognitive basis of the effects on high-altitude exposure on response inhibition.

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