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Dyspnea: Mechanisms, assessment, and management: A consensus statement

Wireless sensor network (WSN) has emerged as one of the most promising technologies for the future. This has been enabled by advances in technology and availability of small, inexpensive, and smart sensors resulting in cost effective and easily deployable WSNs. However, researchers must address a variety of challenges to facilitate the widespread deployment of WSN technology in real-world domains. In this survey, we give an overview of wireless sensor networks and their application domains including the challenges that should be addressed in order to push the technology further. Then we review the recent technologies and testbeds for WSNs. Finally, we identify several open research issues that need to be investigated in future.

Our survey is different from existing surveys in that we focus on recent developments in wireless sensor network technologies. We review the leading research projects, standards and technologies, and platforms. Moreover, we highlight a recent phenomenon in WSN research that is to explore synergy between sensor networks and other technologies and explain how this can help sensor networks achieve their full potential. This paper intends to help new researchers entering the domain of WSNs by providing a comprehensive survey on recent developments.

Wireless sensor networks: a survey on recent developments and potential synergies

An important open problem in the area of Traitor Tracing is designing a scheme with constant expansion of the size of keys (users' keys and the encryption key) and of the size of ciphertexts with respect to the size of the plaintext. This problem is known from the introduction of Traitor Tracing by Chor, Fiat and Naor. We refer to such schemes as traitor tracing with constant transmission rate. Here we present a general methodology and two protocol constructions that result in the first two public-key traitor tracing schemes with constant transmission rate in settings where plaintexts can be calibrated to be sufficiently large. Our starting point is the notion of copyrighted function which was presented by Naccache, Shamir and Stern. We first solve the open problem of discrete-log-based and public-key-based copyrighted function. Then, we observe the simple yet crucial relation between (public-key) copyrighted encryption and (public-key) traitor tracing, which we exploit by introducing a generic design paradigm for designing constant transmission rate traitor tracing schemes based on copyrighted encryption functions. Our first scheme achieves the same expansion efficiency as regular ElGamal encryption. The second scheme introduces only a slightly larger (constant) overhead, however, it additionally achieves efficient black-box traitor tracing (against any pirate construction).

Traitor Tracing with constant transmission rate

Background Opioids are commonly used to treat dyspnoea in palliative medicine but there has been no formal evaluation of the evidence for their effectiveness in the treatment of dyspnoea. A systematic review was therefore carried out to examine this. Methods The criteria for inclusion required that studies were double blind, randomised, placebo controlled trials of opioids for the treatment of dyspnoea secondary to any cause. The methods used to identify suitable studies included electronic searching of the literature, hand searching of the literature, and personal contact with relevant individuals and organisations. Random effects meta-analyses were performed on all included studies and on various subgroups (studies involving nebulised opioids or patients with chronic obstructive pulmonary disease (COPD)). Subgroups were compared using meta-regression. Some studies included in the systematic review could not be included in the meta-analysis because insufficient data were presented. Results Eighteen studies fulfilled the criteria for the review. The meta-analysis showed a statistically significant positive effect of opioids on the sensation of breathlessness (p=0.0008). Meta-regression indicated a greater effect for studies using oral or parenteral opioids than for studies using nebulised opioids (p=0.02). The subgroup analysis failed to show a positive effect of nebulised opioids on the sensation of breathlessness. The results of the subgroup analysis of the COPD studies were essentially similar to the results of the main analysis. Conclusion This review supports the continued use of oral and parenteral opioids to treat dyspnoea in patients with advanced disease. There are insufficient data from the meta-analysis to conclude whether nebulised opioids are effective, but the results from included studies that did not contribute to the meta-analysis suggest that they are no better than nebulised normal saline.

https://thorax.bmj.com/content/thoraxjnl/57/11/939.full.pdf

A systematic review of the use of opioids in the management of dyspnoea

We report the observation of a very large piezoresistive effect in both polycrystalline and homoepitaxial chemical‐vapor‐deposited diamond films. The gauge factor for polycrystalline p‐type diamond at 500 microstrains was found to be only 6 at room ambient, but increased rapidly with temperature, exceeding that of polycrystalline silicon (30) at 35 °C, and that of single‐crystal Si (120) at 50 °C. For strain and current flow in the [100] direction, the gauge factor of a (100)‐oriented homoepitaxial diamond film was found to be at least 550 at room temperature. Although the origins and unexpected temperature dependence of piezoresistive effect in diamond are not yet understood, these findings may suggest diamond‐based sensors with performance significantly superior to that of their Si counterparts.

/pdf/piezoresistivity-in-vapor-deposited-diamond-films-1sxd5y5nq5.pdf

Piezoresistivity in vapor-deposited diamond films

BACKGROUND--Inhaled nebulised morphine may reduce breathlessness in patients with lung disease, although the results of controlled trials are conflicting. A direct action of morphine on the lung has been postulated. This study aimed to investigate whether nebulised morphine reduced exercise-induced breathlessness in patients with chronic obstructive pulmonary disease (COPD) and to determine if this was a local pulmonary effect or occurred after systemic morphine absorption. METHODS--A double blind, randomised, crossover study was performed in 12 men with COPD to compare the effects of nebulised morphine (10 and 25 mg), equivalent intravenous doses (1 and 2.5 mg), and placebo. Breathlessness (visual analogue scale), ventilation, gas exchange, and exercise endurance were measured during graded bicycle exercise. RESULTS--None of the treatments altered breathlessness, ventilation, or gas exchange at rest or at any time during exercise, and exercise endurance was unaffected. At peak exercise mean (95% CI) changes from placebo in ventilation were -0.8 (-0.57 to 1.1) l/min and -0.4 (-2.8 to 2.0) l/min for the highest intravenous and nebulised doses, respectively. For breathlessness equivalent values were +2 (-5 to 9) and +1 (-9 to 11) mm. The study was of sufficient power that it is unlikely that a clinically important effect was missed. CONCLUSIONS--Nebulised morphine in these doses has no effect on exercise-induced breathlessness. These findings do not support the hypothesis that intrapulmonary opiates modulate the sensation of breathlessness in patients with COPD.

https://thorax.bmj.com/content/thoraxjnl/50/6/629.full.pdf

Lack of effect of inhaled morphine on exercise-induced breathlessness in chronic obstructive pulmonary disease.

Key distribution refers to the problem of establishing shared secrets on sensor nodes such that secret symmetric keys for communication privacy, integrity and authenticity can be generated. In a wireless sensor network, pre-distribution of secret keys is possibly the most practical approach to protect network communications but it is difficult due to the ad hoc nature, intermittent connectivity, and resource limitations of the sensor networks. In this paper, we propose a key distribution scheme based on random key pre-distribution for heterogeneous sensor network (HSN) to achieve better performance and security as compared to homogeneous network which suffer from high communication overhead, computation overhead, and/or high storage requirements. In a key generation process, instead of generating a large pool of random keys, a key pool is represented by a small number of generation keys. For a given generation key and publicly known seed value, a one-way hash function generates a key chain, and these key chains collectively make a key pool. Each sensor node is assigned a small number of randomly selected generation keys. The proposed scheme reduces the storage requirements while maintaining the same security strength.

/pdf/an-efficient-key-distribution-scheme-for-heterogeneous-1qd2ugbcsj.pdf

An efficient key distribution scheme for heterogeneous sensor networks

We have developed a self-healing key distribution scheme for secure multicast group communications for wireless sensor network environment. We present a strategy for securely distributing rekeying messages and specify techniques for joining and leaving a group. Access control in multicast system is usually achieved by encrypting the content using an encryption key, known as the group key (session key) that is only known by the group controller and all legitimate group members. In our scheme, all rekeying messages, except for unicast of an individual key, are transmitted without any encryption using one-way hash function and XOR operation. In our proposed scheme, nodes are capable of recovering lost session keys on their own, without requesting additional transmission from the group controller. The proposed scheme provides both backward and forward secrecy. We analyze the proposed scheme to verify that it satisfies the security and performance requirements for secure group communication.

/pdf/secure-group-communication-with-self-healing-and-rekeying-in-1e217cxx42.pdf

Secure group communication with self-healing and rekeying in wireless sensor networks

As typical wireless sensor networks (WSNs) have resource limitations, predistribution of secret keys is possibly the most practical approach for secure network communications. In this paper, we propose a key management scheme based on random key predistribution for heterogeneous wireless sensor networks (HSNs). As large-scale homogeneous networks suffer from high costs of communication, computation, and storage requirements, the HSNs are preferred because they provide better performance and security solutions for scalable applications in dynamic environments. We consider hierarchical HSN consisting of a small number high-end sensors and a large number of low-end sensors. To address storage overhead problem in the constraint sensor nodes, we incorporate a key generation process, where instead of generating a large pool of random keys, a key pool is represented by a small number of generation keys. For a given generation key and a publicly known seed value, a keyed-hash function generates a key chain; these key chains collectively make a key pool. As dynamic network topology is native to WSNs, the proposed scheme allows dynamic addition and removal of nodes. This paper also reports the implementation and the performance of the proposed scheme on Crossbow's MicaZ motes running TinyOS. The results indicate that the proposed scheme can be applied efficiently in resource-constrained sensor networks. We evaluate the computation and storage costs of two keyed-hash algorithms for key chain generation, HMAC-SHA1 and HMAC-MD5.

/pdf/scalable-and-efficient-key-management-for-heterogeneous-565itr8dnx.pdf

Ashraf Masood

Papers

Piezoresistivity in vapor-deposited diamond films

Lack of effect of inhaled morphine on exercise-induced breathlessness in chronic obstructive pulmonary disease.

An efficient key distribution scheme for heterogeneous sensor networks

Secure group communication with self-healing and rekeying in wireless sensor networks

Scalable and efficient key management for heterogeneous sensor networks