Practical scheme to share a secret key through a quantum channel with a 27.6% bit error rate

NASA Astrophysics Data System (ADS)

Chau, H. F.

2002-12-01

A secret key shared through quantum key distribution between two cooperative players is secure against any eavesdropping attack allowed by the laws of physics. Yet, such a key can be established only when the quantum channel error rate due to eavesdropping or imperfect apparatus is low. Here, a practical quantum key distribution scheme by making use of an adaptive privacy amplification procedure with two-way classical communication is reported. Then, it is proven that the scheme generates a secret key whenever the bit error rate of the quantum channel is less than 0.5-0.1(5)≈27.6%, thereby making it the most error resistant scheme known to date.

Device-independent secret-key-rate analysis for quantum repeaters

NASA Astrophysics Data System (ADS)

Holz, Timo; Kampermann, Hermann; Bruß, Dagmar

2018-01-01

The device-independent approach to quantum key distribution (QKD) aims to establish a secret key between two or more parties with untrusted devices, potentially under full control of a quantum adversary. The performance of a QKD protocol can be quantified by the secret key rate, which can be lower bounded via the violation of an appropriate Bell inequality in a setup with untrusted devices. We study secret key rates in the device-independent scenario for different quantum repeater setups and compare them to their device-dependent analogon. The quantum repeater setups under consideration are the original protocol by Briegel et al. [Phys. Rev. Lett. 81, 5932 (1998), 10.1103/PhysRevLett.81.5932] and the hybrid quantum repeater protocol by van Loock et al. [Phys. Rev. Lett. 96, 240501 (2006), 10.1103/PhysRevLett.96.240501]. For a given repeater scheme and a given QKD protocol, the secret key rate depends on a variety of parameters, such as the gate quality or the detector efficiency. We systematically analyze the impact of these parameters and suggest optimized strategies.

Key rate for calibration robust entanglement based BB84 quantum key distribution protocol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gittsovich, O.; Moroder, T.

2014-12-04

We apply the approach of verifying entanglement, which is based on the sole knowledge of the dimension of the underlying physical system to the entanglement based version of the BB84 quantum key distribution protocol. We show that the familiar one-way key rate formula holds already if one assumes the assumption that one of the parties is measuring a qubit and no further assumptions about the measurement are needed.

A Trustworthy Key Generation Prototype Based on DDR3 PUF for Wireless Sensor Networks

PubMed Central

Liu, Wenchao; Zhang, Zhenhua; Li, Miaoxin; Liu, Zhenglin

2014-01-01

Secret key leakage in wireless sensor networks (WSNs) is a high security risk especially when sensor nodes are deployed in hostile environment and physically accessible to attackers. With nowadays semi/fully-invasive attack techniques attackers can directly derive the cryptographic key from non-volatile memory (NVM) storage. Physically Unclonable Function (PUF) is a promising technology to resist node capture attacks, and it also provides a low cost and tamper-resistant key provisioning solution. In this paper, we designed a PUF based on double-data-rate SDRAM Type 3 (DDR3) memory by exploring its memory decay characteristics. We also described a prototype of 128-bit key generation based on DDR3 PUF with integrated fuzzy extractor. Due to the wide adoption of DDR3 memory in WSN, our proposed DDR3 PUF technology with high security levels and no required hardware changes is suitable for a wide range of WSN applications. PMID:24984058

Extending key sharing: how to generate a key tightly coupled to a network security policy

NASA Astrophysics Data System (ADS)

Kazantzidis, Matheos

2006-04-01

Current state of the art security policy technologies, besides the small scale limitation and largely manual nature of accompanied management methods, are lacking a) in real-timeliness of policy implementation and b) vulnerabilities and inflexibility stemming from the centralized policy decision making; even if, for example, a policy description or access control database is distributed, the actual decision is often a centralized action and forms a system single point of failure. In this paper we are presenting a new fundamental concept that allows implement a security policy by a systematic and efficient key distribution procedure. Specifically, we extend the polynomial Shamir key splitting. According to this, a global key is split into n parts, any k of which can re-construct the original key. In this paper we present a method that instead of having "any k parts" be able to re-construct the original key, the latter can only be reconstructed if keys are combined as any access control policy describes. This leads into an easily deployable key generation procedure that results a single key per entity that "knows" its role in the specific access control policy from which it was derived. The system is considered efficient as it may be used to avoid expensive PKI operations or pairwise key distributions as well as provides superior security due to its distributed nature, the fact that the key is tightly coupled to the policy, and that policy change may be implemented easier and faster.

High speed and adaptable error correction for megabit/s rate quantum key distribution.

PubMed

Dixon, A R; Sato, H

2014-12-02

Quantum Key Distribution is moving from its theoretical foundation of unconditional security to rapidly approaching real world installations. A significant part of this move is the orders of magnitude increases in the rate at which secure key bits are distributed. However, these advances have mostly been confined to the physical hardware stage of QKD, with software post-processing often being unable to support the high raw bit rates. In a complete implementation this leads to a bottleneck limiting the final secure key rate of the system unnecessarily. Here we report details of equally high rate error correction which is further adaptable to maximise the secure key rate under a range of different operating conditions. The error correction is implemented both in CPU and GPU using a bi-directional LDPC approach and can provide 90-94% of the ideal secure key rate over all fibre distances from 0-80 km.

High speed and adaptable error correction for megabit/s rate quantum key distribution

PubMed Central

Dixon, A. R.; Sato, H.

2014-01-01

Quantum Key Distribution is moving from its theoretical foundation of unconditional security to rapidly approaching real world installations. A significant part of this move is the orders of magnitude increases in the rate at which secure key bits are distributed. However, these advances have mostly been confined to the physical hardware stage of QKD, with software post-processing often being unable to support the high raw bit rates. In a complete implementation this leads to a bottleneck limiting the final secure key rate of the system unnecessarily. Here we report details of equally high rate error correction which is further adaptable to maximise the secure key rate under a range of different operating conditions. The error correction is implemented both in CPU and GPU using a bi-directional LDPC approach and can provide 90–94% of the ideal secure key rate over all fibre distances from 0–80 km. PMID:25450416

A New Three Dimensional Based Key Generation Technique in AVK

NASA Astrophysics Data System (ADS)

Banerjee, Subhasish; Dutta, Manash Pratim; Bhunia, Chandan Tilak

2017-08-01

In modern era, ensuring high order security becomes one and only objective of computer networks. From the last few decades, many researchers have given their contributions to achieve the secrecy over the communication channel. In achieving perfect security, Shannon had done the pioneer work on perfect secret theorem and illustrated that secrecy of the shared information can be maintained if the key becomes variable in nature instead of static one. In this regard, a key generation technique has been proposed where the key can be changed every time whenever a new block of data needs to be exchanged. In our scheme, the keys not only vary in bit sequences but also in size. The experimental study is also included in this article to prove the correctness and effectiveness of our proposed technique.

Distributed generation of shared RSA keys in mobile ad hoc networks

NASA Astrophysics Data System (ADS)

Liu, Yi-Liang; Huang, Qin; Shen, Ying

2005-12-01

Mobile Ad Hoc Networks is a totally new concept in which mobile nodes are able to communicate together over wireless links in an independent manner, independent of fixed physical infrastructure and centralized administrative infrastructure. However, the nature of Ad Hoc Networks makes them very vulnerable to security threats. Generation and distribution of shared keys for CA (Certification Authority) is challenging for security solution based on distributed PKI(Public-Key Infrastructure)/CA. The solutions that have been proposed in the literature and some related issues are discussed in this paper. The solution of a distributed generation of shared threshold RSA keys for CA is proposed in the present paper. During the process of creating an RSA private key share, every CA node only has its own private security. Distributed arithmetic is used to create the CA's private share locally, and that the requirement of centralized management institution is eliminated. Based on fully considering the Mobile Ad Hoc network's characteristic of self-organization, it avoids the security hidden trouble that comes by holding an all private security share of CA, with which the security and robustness of system is enhanced.

Long-distance entanglement-based quantum key distribution experiment using practical detectors.

PubMed

Takesue, Hiroki; Harada, Ken-Ichi; Tamaki, Kiyoshi; Fukuda, Hiroshi; Tsuchizawa, Tai; Watanabe, Toshifumi; Yamada, Koji; Itabashi, Sei-Ichi

2010-08-02

We report an entanglement-based quantum key distribution experiment that we performed over 100 km of optical fiber using a practical source and detectors. We used a silicon-based photon-pair source that generated high-purity time-bin entangled photons, and high-speed single photon detectors based on InGaAs/InP avalanche photodiodes with the sinusoidal gating technique. To calculate the secure key rate, we employed a security proof that validated the use of practical detectors. As a result, we confirmed the successful generation of sifted keys over 100 km of optical fiber with a key rate of 4.8 bit/s and an error rate of 9.1%, with which we can distill secure keys with a key rate of 0.15 bit/s.

Key Generation for Fast Inversion of the Paillier Encryption Function

NASA Astrophysics Data System (ADS)

Hirano, Takato; Tanaka, Keisuke

We study fast inversion of the Paillier encryption function. Especially, we focus only on key generation, and do not modify the Paillier encryption function. We propose three key generation algorithms based on the speeding-up techniques for the RSA encryption function. By using our algorithms, the size of the private CRT exponent is half of that of Paillier-CRT. The first algorithm employs the extended Euclidean algorithm. The second algorithm employs factoring algorithms, and can construct the private CRT exponent with low Hamming weight. The third algorithm is a variant of the second one, and has some advantage such as compression of the private CRT exponent and no requirement for factoring algorithms. We also propose the settings of the parameters for these algorithms and analyze the security of the Paillier encryption function by these algorithms against known attacks. Finally, we give experimental results of our algorithms.

Are dialysis adequacy indices independent of solute generation rate?

PubMed

Waniewski, Jacek; Debowska, Malgorzata; Lindholm, Bengt

2014-01-01

KT/V is by definition independent of solute generation rate. Alternative dialysis adequacy indices (DAIs) such as equivalent renal clearance (EKR), standard KT/V (stdKT/V), and solute removal index (SRI) are estimated as the ratio of solute mass removed to an average solute mass in the body or solute concentration in blood; both nominator and denominator in these formulas depend on the solute generation rate. Our objective was to investigate whether and under which conditions the alternative DAIs are independent of solute generation rate. By using general compartment modeling, we show that for the metabolically stable patient (in whom the solute generated during the dialysis cycle, typically, 1 week, is equal to the solute removed from the body), DAIs estimated for the dialysis cycle are in general independent of the average solute generation rate (although they may depend on the pattern of oscillations in the generation rate). However, the alternative adequacy parameters (such as EKR, stdKT/V, and SRI) may depend on solute generation rate for metabolically unstable patients.

Quantum key distribution in a multi-user network at gigahertz clock rates

NASA Astrophysics Data System (ADS)

Fernandez, Veronica; Gordon, Karen J.; Collins, Robert J.; Townsend, Paul D.; Cova, Sergio D.; Rech, Ivan; Buller, Gerald S.

2005-07-01

In recent years quantum information research has lead to the discovery of a number of remarkable new paradigms for information processing and communication. These developments include quantum cryptography schemes that offer unconditionally secure information transport guaranteed by quantum-mechanical laws. Such potentially disruptive security technologies could be of high strategic and economic value in the future. Two major issues confronting researchers in this field are the transmission range (typically <100km) and the key exchange rate, which can be as low as a few bits per second at long optical fiber distances. This paper describes further research of an approach to significantly enhance the key exchange rate in an optical fiber system at distances in the range of 1-20km. We will present results on a number of application scenarios, including point-to-point links and multi-user networks. Quantum key distribution systems have been developed, which use standard telecommunications optical fiber, and which are capable of operating at clock rates of up to 2GHz. They implement a polarization-encoded version of the B92 protocol and employ vertical-cavity surface-emitting lasers with emission wavelengths of 850 nm as weak coherent light sources, as well as silicon single-photon avalanche diodes as the single photon detectors. The point-to-point quantum key distribution system exhibited a quantum bit error rate of 1.4%, and an estimated net bit rate greater than 100,000 bits-1 for a 4.2 km transmission range.

Field trial of differential-phase-shift quantum key distribution using polarization independent frequency up-conversion detectors.

PubMed

Honjo, T; Yamamoto, S; Yamamoto, T; Kamada, H; Nishida, Y; Tadanaga, O; Asobe, M; Inoue, K

2007-11-26

We report a field trial of differential phase shift quantum key distribution (QKD) using polarization independent frequency up-conversion detectors. A frequency up-conversion detector is a promising device for achieving a high key generation rate when combined with a high clock rate QKD system. However, its polarization dependence prevents it from being applied to practical QKD systems. In this paper, we employ a modified polarization diversity configuration to eliminate the polarization dependence. Applying this method, we performed a long-term stability test using a 17.6-km installed fiber. We successfully demonstrated stable operation for 6 hours and achieved a sifted key generation rate of 120 kbps and an average quantum bit error rate of 3.14 %. The sifted key generation rate was not the estimated value but the effective value, which means that the sifted key was continuously generated at a rate of 120 kbps for 6 hours.

Quantum cryptography using coherent states: Randomized encryption and key generation

NASA Astrophysics Data System (ADS)

Corndorf, Eric

objectives of key generation and direct data-encryption, a new quantum cryptographic principle is demonstrated wherein keyed coherent-state signal sets are employed. Taking advantage of the fundamental and irreducible quantum-measurement noise of coherent states, these schemes do not require the users to measure the influence of an attacker. Experimental key-generation and data encryption schemes based on these techniques, which are compatible with today's WDM fiber-optic telecommunications infrastructure, are implemented and analyzed.

Key-Generation Algorithms for Linear Piece In Hand Matrix Method

NASA Astrophysics Data System (ADS)

Tadaki, Kohtaro; Tsujii, Shigeo

The linear Piece In Hand (PH, for short) matrix method with random variables was proposed in our former work. It is a general prescription which can be applicable to any type of multivariate public-key cryptosystems for the purpose of enhancing their security. Actually, we showed, in an experimental manner, that the linear PH matrix method with random variables can certainly enhance the security of HFE against the Gröbner basis attack, where HFE is one of the major variants of multivariate public-key cryptosystems. In 1998 Patarin, Goubin, and Courtois introduced the plus method as a general prescription which aims to enhance the security of any given MPKC, just like the linear PH matrix method with random variables. In this paper we prove the equivalence between the plus method and the primitive linear PH matrix method, which is introduced by our previous work to explain the notion of the PH matrix method in general in an illustrative manner and not for a practical use to enhance the security of any given MPKC. Based on this equivalence, we show that the linear PH matrix method with random variables has the substantial advantage over the plus method with respect to the security enhancement. In the linear PH matrix method with random variables, the three matrices, including the PH matrix, play a central role in the secret-key and public-key. In this paper, we clarify how to generate these matrices and thus present two probabilistic polynomial-time algorithms to generate these matrices. In particular, the second one has a concise form, and is obtained as a byproduct of the proof of the equivalence between the plus method and the primitive linear PH matrix method.

Bidirectional private key exchange using delay-coupled semiconductor lasers.

PubMed

Porte, Xavier; Soriano, Miguel C; Brunner, Daniel; Fischer, Ingo

2016-06-15

We experimentally demonstrate a key exchange cryptosystem based on the phenomenon of identical chaos synchronization. In our protocol, the private key is symmetrically generated by the two communicating partners. It is built up from the synchronized bits occurring between two current-modulated bidirectionally coupled semiconductor lasers with additional self-feedback. We analyze the security of the exchanged key and discuss the amplification of its privacy. We demonstrate private key generation rates up to 11  Mbit/s over a public channel.

Wind Turbine Contingency Control Through Generator De-Rating

NASA Technical Reports Server (NTRS)

Frost, Susan; Goebel, Kai; Balas, Mark

2013-01-01

Maximizing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. In that context, systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage to the turbine. Advanced contingency control is one way to enable autonomous decision-making by providing the mechanism to enable safe and efficient turbine operation. The work reported herein explores the integration of condition monitoring of wind turbines with contingency control to balance the trade-offs between maintaining system health and energy capture. The contingency control involves de-rating the generator operating point to achieve reduced loads on the wind turbine. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.

Physical Layer Secret-Key Generation Scheme for Transportation Security Sensor Network

PubMed Central

Yang, Bin; Zhang, Jianfeng

2017-01-01

Wireless Sensor Networks (WSNs) are widely used in different disciplines, including transportation systems, agriculture field environment monitoring, healthcare systems, and industrial monitoring. The security challenge of the wireless communication link between sensor nodes is critical in WSNs. In this paper, we propose a new physical layer secret-key generation scheme for transportation security sensor network. The scheme is based on the cooperation of all the sensor nodes, thus avoiding the key distribution process, which increases the security of the system. Different passive and active attack models are analyzed in this paper. We also prove that when the cooperative node number is large enough, even when the eavesdropper is equipped with multiple antennas, the secret-key is still secure. Numerical results are performed to show the efficiency of the proposed scheme. PMID:28657588

Physical Layer Secret-Key Generation Scheme for Transportation Security Sensor Network.

PubMed

Yang, Bin; Zhang, Jianfeng

2017-06-28

Wireless Sensor Networks (WSNs) are widely used in different disciplines, including transportation systems, agriculture field environment monitoring, healthcare systems, and industrial monitoring. The security challenge of the wireless communication link between sensor nodes is critical in WSNs. In this paper, we propose a new physical layer secret-key generation scheme for transportation security sensor network. The scheme is based on the cooperation of all the sensor nodes, thus avoiding the key distribution process, which increases the security of the system. Different passive and active attack models are analyzed in this paper. We also prove that when the cooperative node number is large enough, even when the eavesdropper is equipped with multiple antennas, the secret-key is still secure. Numerical results are performed to show the efficiency of the proposed scheme.

Experimental realization of equiangular three-state quantum key distribution

PubMed Central

Schiavon, Matteo; Vallone, Giuseppe; Villoresi, Paolo

2016-01-01

Quantum key distribution using three states in equiangular configuration combines a security threshold comparable with the one of the Bennett-Brassard 1984 protocol and a quantum bit error rate (QBER) estimation that does not need to reveal part of the key. We implement an entanglement-based version of the Renes 2004 protocol, using only passive optic elements in a linear scheme for the positive-operator valued measure (POVM), generating an asymptotic secure key rate of more than 10 kbit/s, with a mean QBER of 1.6%. We then demonstrate its security in the case of finite key and evaluate the key rate for both collective and general attacks. PMID:27465643

Secure Communication via Key Generation with Quantum Measurement Advantage in the Telecom Band

DTIC Science & Technology

2013-10-30

II: Summary of Project In this basic research program we proposed to investigate the use of keyed communication in quantum noise as a key generation...implement quantum limited detection in our running-code OCDMA experiment to demonstrate (a) quantum measurement advantage creation between two users, (b...neither is adequate against known-plaintext attacks. This is a serious security problem facing the whole field of quantum cryptography in regard to both

JPKWIC - General key word in context and subject index report generator

NASA Technical Reports Server (NTRS)

Jirka, R.; Kabashima, N.; Kelly, D.; Plesset, M.

1968-01-01

JPKWIC computer program is a general key word in context and subject index report generator specifically developed to help nonprogrammers and nontechnical personnel to use the computer to access files, libraries and mass documentation. This program is designed to produce a KWIC index, a subject index, an edit report, a summary report, and an exclusion list.

Key Themes in Mobile Learning: Prospects for Learner-Generated Learning through AR and VR

ERIC Educational Resources Information Center

Aguayo, Claudio; Cochrane, Thomas; Narayan, Vickel

2017-01-01

This paper summarises the findings from a literature review in mobile learning, developed as part of a 2-year six-institution project in New Zealand. Through the development of a key themes codebook, we address selected key themes with respect to their relevance to learner-generated learning through emerging technologies, with attention to mobile…

Critical side channel effects in random bit generation with multiple semiconductor lasers in a polarization-based quantum key distribution system.

PubMed

Ko, Heasin; Choi, Byung-Seok; Choe, Joong-Seon; Kim, Kap-Joong; Kim, Jong-Hoi; Youn, Chun Ju

2017-08-21

Most polarization-based BB84 quantum key distribution (QKD) systems utilize multiple lasers to generate one of four polarization quantum states randomly. However, random bit generation with multiple lasers can potentially open critical side channels that significantly endangers the security of QKD systems. In this paper, we show unnoticed side channels of temporal disparity and intensity fluctuation, which possibly exist in the operation of multiple semiconductor laser diodes. Experimental results show that the side channels can enormously degrade security performance of QKD systems. An important system issue for the improvement of quantum bit error rate (QBER) related with laser driving condition is further addressed with experimental results.

Experimental quantum key distribution at 1.3 gigabit-per-second secret-key rate over a 10 dB loss channel

NASA Astrophysics Data System (ADS)

Zhang, Zheshen; Chen, Changchen; Zhuang, Quntao; Wong, Franco N. C.; Shapiro, Jeffrey H.

2018-04-01

Quantum key distribution (QKD) enables unconditionally secure communication ensured by the laws of physics, opening a promising route to security infrastructure for the coming age of quantum computers. QKD’s demonstrated secret-key rates (SKRs), however, fall far short of the gigabit-per-second rates of classical communication, hindering QKD’s widespread deployment. QKD’s low SKRs are largely due to existing single-photon-based protocols’ vulnerability to channel loss. Floodlight QKD (FL-QKD) boosts SKR by transmitting many photons per encoding, while offering security against collective attacks. Here, we report an FL-QKD experiment operating at a 1.3 Gbit s‑1 SKR over a 10 dB loss channel. To the best of our knowledge, this is the first QKD demonstration that achieves a gigabit-per-second-class SKR, representing a critical advance toward high-rate QKD at metropolitan-area distances.

Finite-key analysis for quantum key distribution with weak coherent pulses based on Bernoulli sampling

NASA Astrophysics Data System (ADS)

Kawakami, Shun; Sasaki, Toshihiko; Koashi, Masato

2017-07-01

An essential step in quantum key distribution is the estimation of parameters related to the leaked amount of information, which is usually done by sampling of the communication data. When the data size is finite, the final key rate depends on how the estimation process handles statistical fluctuations. Many of the present security analyses are based on the method with simple random sampling, where hypergeometric distribution or its known bounds are used for the estimation. Here we propose a concise method based on Bernoulli sampling, which is related to binomial distribution. Our method is suitable for the Bennett-Brassard 1984 (BB84) protocol with weak coherent pulses [C. H. Bennett and G. Brassard, Proceedings of the IEEE Conference on Computers, Systems and Signal Processing (IEEE, New York, 1984), Vol. 175], reducing the number of estimated parameters to achieve a higher key generation rate compared to the method with simple random sampling. We also apply the method to prove the security of the differential-quadrature-phase-shift (DQPS) protocol in the finite-key regime. The result indicates that the advantage of the DQPS protocol over the phase-encoding BB84 protocol in terms of the key rate, which was previously confirmed in the asymptotic regime, persists in the finite-key regime.

Rectangular QPSK for generation of optical eight-ary phase-shift keying.

PubMed

Lu, Guo-Wei; Sakamoto, Takahide; Kawanishi, Tetsuya

2011-09-12

Quadrature phase-shift keying (QPSK) is usually generated using an in-phase/quadrature (IQ) modulator in a balanced driving-condition, showing a square-shape constellation in complex plane. This conventional QPSK is referred to as square QPSK (S-QPSK) in this paper. On the other hand, when an IQ modulator is driven in an un-balanced manner with different amplitudes in in-phase (I) and quadrature (Q) branches, a rectangular QPSK (R-QPSK) could be synthesized. The concept of R-QPSK is proposed for the first time and applied to optical eight-ary phase-shift keying (8PSK) transmitter. By cascading an S-QPSK and an R-QPSK, an optical 8PSK could be synthesized. The transmitter configuration is based on two cascaded IQ modulators, which also could be used to generate other advanced multi-level formats like quadrature amplitude modulation (QAM) when different driving and bias conditions are applied. Therefore, the proposed transmitter structure has potential to be deployed as a versatile transmitter for synthesis of several different multi-level modulation formats for the future dynamic optical networks. A 30-Gb/s optical 8PSK is experimentally demonstrated using the proposed solution.

Generation and detection of 80-Gbit/s return-to-zero differential phase-shift keying signals

NASA Astrophysics Data System (ADS)

Möller, Lothar; Su, Yikai; Xie, Chongjin; Liu, Xiang; Leuthold, Juerg; Gill, Douglas; Wei, Xing

2003-12-01

Nonlinear polarization rotation between a pump and a probe signal in a highly nonlinear fiber is used as a modulation process to generate 80-Gbit/s return-to-zero differential phase-shift keying signals. Its performance is analyzed and compared with a conventional on-off keying modulated signal.

Performance improvement of eight-state continuous-variable quantum key distribution with an optical amplifier

NASA Astrophysics Data System (ADS)

Guo, Ying; Li, Renjie; Liao, Qin; Zhou, Jian; Huang, Duan

2018-02-01

Discrete modulation is proven to be beneficial to improving the performance of continuous-variable quantum key distribution (CVQKD) in long-distance transmission. In this paper, we suggest a construct to improve the maximal generated secret key rate of discretely modulated eight-state CVQKD using an optical amplifier (OA) with a slight cost of transmission distance. In the proposed scheme, an optical amplifier is exploited to compensate imperfection of Bob's apparatus, so that the generated secret key rate of eight-state protocol is enhanced. Specifically, we investigate two types of optical amplifiers, phase-insensitive amplifier (PIA) and phase-sensitive amplifier (PSA), and thereby obtain approximately equivalent improved performance for eight-state CVQKD system when applying these two different amplifiers. Numeric simulation shows that the proposed scheme can well improve the generated secret key rate of eight-state CVQKD in both asymptotic limit and finite-size regime. We also show that the proposed scheme can achieve the relatively high-rate transmission at long-distance communication system.

Phase-Reference-Free Experiment of Measurement-Device-Independent Quantum Key Distribution

NASA Astrophysics Data System (ADS)

Wang, Chao; Song, Xiao-Tian; Yin, Zhen-Qiang; Wang, Shuang; Chen, Wei; Zhang, Chun-Mei; Guo, Guang-Can; Han, Zheng-Fu

2015-10-01

Measurement-device-independent quantum key distribution (MDI QKD) is a substantial step toward practical information-theoretic security for key sharing between remote legitimate users (Alice and Bob). As with other standard device-dependent quantum key distribution protocols, such as BB84, MDI QKD assumes that the reference frames have been shared between Alice and Bob. In practice, a nontrivial alignment procedure is often necessary, which requires system resources and may significantly reduce the secure key generation rate. Here, we propose a phase-coding reference-frame-independent MDI QKD scheme that requires no phase alignment between the interferometers of two distant legitimate parties. As a demonstration, a proof-of-principle experiment using Faraday-Michelson interferometers is presented. The experimental system worked at 1 MHz, and an average secure key rate of 8.309 bps was obtained at a fiber length of 20 km between Alice and Bob. The system can maintain a positive key generation rate without phase compensation under normal conditions. The results exhibit the feasibility of our system for use in mature MDI QKD devices and its value for network scenarios.

Energy metabolism, body composition, and urea generation rate in hemodialysis patients.

PubMed

Sridharan, Sivakumar; Vilar, Enric; Berdeprado, Jocelyn; Farrington, Ken

2013-10-01

Hemodialysis (HD) adequacy is currently assessed using normalized urea clearance (Kt/V), although scaling based on Watson volume (V) may disadvantage women and men with low body weight. Alternative scaling factors such as resting energy expenditure and high metabolic rate organ mass have been suggested. The relationship between such factors and uremic toxin generation has not been established. We aimed to study the relationship between body size, energy metabolism, and urea generation rate. A cross-sectional cohort of 166 HD patients was studied. Anthropometric measurements were carried on all. Resting energy expenditure was measured by indirect calorimetry, fat-free mass by bio-impedance and total energy expenditure by combining resting energy expenditure with a questionnaire-derived physical activity data. High metabolic rate organ mass was calculated using a published equation and urea generation rate using formal urea kinetic modeling. Metabolic factors including resting energy expenditure, total energy expenditure and fat-free mass correlated better with urea generation rate than did Watson volume. Total energy expenditure and fat-free mass (but not Watson Volume) were independent predictors of urea generation rate, the model explaining 42% of its variation. Small women (generation rate per kg than women with higher V. Similarly urea generation rate normalized to fat-free mass was significantly greater in small women than in all others (significant only in comparison to larger men). Exercise-related energy expenditure correlated significantly with urea generation rate. Energy metabolism, body composition and physical activity play important roles in small solute uremic toxin generation in HD patients and hence may impact on minimum dialysis requirements. Small women generate relatively more small solute toxins than other groups and thus may have a higher relative need for dialysis. © 2013 The Authors. Hemodialysis

Feasibility of satellite quantum key distribution

NASA Astrophysics Data System (ADS)

Bonato, C.; Tomaello, A.; Da Deppo, V.; Naletto, G.; Villoresi, P.

2009-04-01

In this paper, we present a novel analysis of the feasibility of quantum key distribution between a LEO satellite and a ground station. First of all, we study signal propagation through a turbulent atmosphere for uplinks and downlinks, discussing the contribution of beam spreading and beam wandering. Then we introduce a model for the background noise of the channel during night-time and day-time, calculating the signal-to-noise ratio for different configurations. We also discuss the expected error-rate due to imperfect polarization compensation in the channel. Finally, we calculate the expected key generation rate of a secure key for different configurations (uplink, downlink) and for different protocols (BB84 with and without decoy states, entanglement-based Ekert91 protocol).

Phase-encoded measurement device independent quantum key distribution without a shared reference frame

NASA Astrophysics Data System (ADS)

Zhuo-Dan, Zhu; Shang-Hong, Zhao; Chen, Dong; Ying, Sun

2018-07-01

In this paper, a phase-encoded measurement device independent quantum key distribution (MDI-QKD) protocol without a shared reference frame is presented, which can generate secure keys between two parties while the quantum channel or interferometer introduces an unknown and slowly time-varying phase. The corresponding secret key rate and single photons bit error rate is analysed, respectively, with single photons source (SPS) and weak coherent source (WCS), taking finite-key analysis into account. The numerical simulations show that the modified phase-encoded MDI-QKD protocol has apparent superiority both in maximal secure transmission distance and key generation rate while possessing the improved robustness and practical security in the high-speed case. Moreover, the rejection of the frame-calibrating part will intrinsically reduce the consumption of resources as well as the potential security flaws of practical MDI-QKD systems.

Entangled quantum key distribution over two free-space optical links.

PubMed

Erven, C; Couteau, C; Laflamme, R; Weihs, G

2008-10-13

We report on the first real-time implementation of a quantum key distribution (QKD) system using entangled photon pairs that are sent over two free-space optical telescope links. The entangled photon pairs are produced with a type-II spontaneous parametric down-conversion source placed in a central, potentially untrusted, location. The two free-space links cover a distance of 435 m and 1,325 m respectively, producing a total separation of 1,575 m. The system relies on passive polarization analysis units, GPS timing receivers for synchronization, and custom written software to perform the complete QKD protocol including error correction and privacy amplification. Over 6.5 hours during the night, we observed an average raw key generation rate of 565 bits/s, an average quantum bit error rate (QBER) of 4.92%, and an average secure key generation rate of 85 bits/s.

Room temperature single-photon detectors for high bit rate quantum key distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Comandar, L. C.; Patel, K. A.; Engineering Department, Cambridge University, 9 J J Thomson Ave., Cambridge CB3 0FA

We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.

Getting something out of nothing in the measurement-device-independent quantum key distribution

NASA Astrophysics Data System (ADS)

Tan, Yong-Gang; Cai, Qing-Yu; Yang, Hai-Feng; Hu, Yao-Hua

2015-11-01

Because of the monogamy of entanglement, the measurement-device-independent quantum key distribution is immune to the side-information leaking of the measurement devices. When the correlated measurement outcomes are generated from the dark counts, no entanglement is actually obtained. However, secure key bits can still be proven to be generated from these measurement outcomes. Especially, we will give numerical studies on the contributions of dark counts to the key generation rate in practical decoy state MDI-QKD where a signal source, a weaker decoy source and a vacuum decoy source are used by either legitimate key distributer.

Developing models for the prediction of hospital healthcare waste generation rate.

PubMed

Tesfahun, Esubalew; Kumie, Abera; Beyene, Abebe

2016-01-01

An increase in the number of health institutions, along with frequent use of disposable medical products, has contributed to the increase of healthcare waste generation rate. For proper handling of healthcare waste, it is crucial to predict the amount of waste generation beforehand. Predictive models can help to optimise healthcare waste management systems, set guidelines and evaluate the prevailing strategies for healthcare waste handling and disposal. However, there is no mathematical model developed for Ethiopian hospitals to predict healthcare waste generation rate. Therefore, the objective of this research was to develop models for the prediction of a healthcare waste generation rate. A longitudinal study design was used to generate long-term data on solid healthcare waste composition, generation rate and develop predictive models. The results revealed that the healthcare waste generation rate has a strong linear correlation with the number of inpatients (R(2) = 0.965), and a weak one with the number of outpatients (R(2) = 0.424). Statistical analysis was carried out to develop models for the prediction of the quantity of waste generated at each hospital (public, teaching and private). In these models, the number of inpatients and outpatients were revealed to be significant factors on the quantity of waste generated. The influence of the number of inpatients and outpatients treated varies at different hospitals. Therefore, different models were developed based on the types of hospitals. © The Author(s) 2015.

Next generation leadership: a profile of self-rated competencies among administrative resident and fellows.

PubMed

Helfand, Brad; Cherlin, Emily; Bradley, Elizabeth H

2005-01-01

Healthcare executives and program faculty have voiced concerns that early careerists lack needed competencies for future leadership in the increasingly complex healthcare industry. However, empirical studies of early careerists' competency levels are limited. We sought to describe administrative fellows' and residents' (n = 78, response rate 73.6%) self-rated competency in several key areas and assess how these ratings differed by individuals' gender, age, prior work experience, year of graduate training, and type of degree program. Respondents rated their competence particularly high (41.7% of respondents rated themselves "A") in the domain of interpersonal and emotional intelligence, which included being an effective team leader and member, coaching and developing others, self-awareness, and self-regulation. Lower ratings were in the domains of facilities management and in development and fundraising. Compared to males, females rated their competency in the financial skills domain lower (P-value = 0.04). Age, prior work experience, year of graduate training, and type of degree program were not significantly associated with self-rated competency in any area. These results provide early evidence that may help program faculty and preceptors consider pedagogical approaches that reflect students' vocalized needs and may help to design strategies that effectively cultivate next generation leadership.

A fast key generation method based on dynamic biometrics to secure wireless body sensor networks for p-health.

PubMed

Zhang, G H; Poon, Carmen C Y; Zhang, Y T

2010-01-01

Body sensor networks (BSNs) have emerged as a new technology for healthcare applications, but the security of communication in BSNs remains a formidable challenge yet to be resolved. The paper discusses the typical attacks faced by BSNs and proposes a fast biometric based approach to generate keys for ensuing confidentiality and authentication in BSN communications. The approach was tested on 900 segments of electrocardiogram. Each segment was 4 seconds long and used to generate a 128-bit key. The results of the study found that entropy of 96% of the keys were above 0.95 and 99% of the hamming distances calculated from any two keys were above 50 bits. Based on the randomness and distinctiveness of these keys, it is concluded that the fast biometric based approach has great potential to be used to secure communication in BSNs for health applications.

Metropolitan Quantum Key Distribution with Silicon Photonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bunandar, Darius; Lentine, Anthony; Lee, Catherine

Photonic integrated circuits provide a compact and stable platform for quantum photonics. Here we demonstrate a silicon photonics quantum key distribution (QKD) encoder in the first high-speed polarization-based QKD field tests. The systems reach composable secret key rates of 1.039 Mbps in a local test (on a 103.6-m fiber with a total emulated loss of 9.2 dB) and 157 kbps in an intercity metropolitan test (on a 43-km fiber with 16.4 dB loss). Our results represent the highest secret key generation rate for polarization-based QKD experiments at a standard telecom wavelength and demonstrate photonic integrated circuits as a promising, scalablemore » resource for future formation of metropolitan quantum-secure communications networks.« less

Metropolitan Quantum Key Distribution with Silicon Photonics

DOE PAGES

Bunandar, Darius; Lentine, Anthony; Lee, Catherine; ...

2018-04-06

Photonic integrated circuits provide a compact and stable platform for quantum photonics. Here we demonstrate a silicon photonics quantum key distribution (QKD) encoder in the first high-speed polarization-based QKD field tests. The systems reach composable secret key rates of 1.039 Mbps in a local test (on a 103.6-m fiber with a total emulated loss of 9.2 dB) and 157 kbps in an intercity metropolitan test (on a 43-km fiber with 16.4 dB loss). Our results represent the highest secret key generation rate for polarization-based QKD experiments at a standard telecom wavelength and demonstrate photonic integrated circuits as a promising, scalablemore » resource for future formation of metropolitan quantum-secure communications networks.« less

Metropolitan Quantum Key Distribution with Silicon Photonics

NASA Astrophysics Data System (ADS)

Bunandar, Darius; Lentine, Anthony; Lee, Catherine; Cai, Hong; Long, Christopher M.; Boynton, Nicholas; Martinez, Nicholas; DeRose, Christopher; Chen, Changchen; Grein, Matthew; Trotter, Douglas; Starbuck, Andrew; Pomerene, Andrew; Hamilton, Scott; Wong, Franco N. C.; Camacho, Ryan; Davids, Paul; Urayama, Junji; Englund, Dirk

2018-04-01

Photonic integrated circuits provide a compact and stable platform for quantum photonics. Here we demonstrate a silicon photonics quantum key distribution (QKD) encoder in the first high-speed polarization-based QKD field tests. The systems reach composable secret key rates of 1.039 Mbps in a local test (on a 103.6-m fiber with a total emulated loss of 9.2 dB) and 157 kbps in an intercity metropolitan test (on a 43-km fiber with 16.4 dB loss). Our results represent the highest secret key generation rate for polarization-based QKD experiments at a standard telecom wavelength and demonstrate photonic integrated circuits as a promising, scalable resource for future formation of metropolitan quantum-secure communications networks.

Fully device-independent conference key agreement

NASA Astrophysics Data System (ADS)

Ribeiro, Jérémy; Murta, Gláucia; Wehner, Stephanie

2018-02-01

We present a security analysis of conference key agreement (CKA) in the most adversarial model of device independence (DI). Our protocol can be implemented by any experimental setup that is capable of performing Bell tests [specifically, the Mermin-Ardehali-Belinskii-Klyshko (MABK) inequality], and security can in principle be obtained for any violation of the MABK inequality that detects genuine multipartite entanglement among the N parties involved in the protocol. As our main tool, we derive a direct physical connection between the N -partite MABK inequality and the Clauser-Horne-Shimony-Holt (CHSH) inequality, showing that certain violations of the MABK inequality correspond to a violation of the CHSH inequality between one of the parties and the other N -1 . We compare the asymptotic key rate for device-independent conference key agreement (DICKA) to the case where the parties use N -1 device-independent quantum key distribution protocols in order to generate a common key. We show that for some regime of noise the DICKA protocol leads to better rates.

Quantum key distribution with an unknown and untrusted source

NASA Astrophysics Data System (ADS)

Zhao, Yi; Qi, Bing; Lo, Hoi-Kwong

2008-05-01

The security of a standard bidirectional “plug-and-play” quantum key distribution (QKD) system has been an open question for a long time. This is mainly because its source is equivalently controlled by an eavesdropper, which means the source is unknown and untrusted. Qualitative discussion on this subject has been made previously. In this paper, we solve this question directly by presenting the quantitative security analysis on a general class of QKD protocols whose sources are unknown and untrusted. The securities of standard Bennett-Brassard 1984 protocol, weak+vacuum decoy state protocol, and one-decoy state protocol, with unknown and untrusted sources are rigorously proved. We derive rigorous lower bounds to the secure key generation rates of the above three protocols. Our numerical simulation results show that QKD with an untrusted source gives a key generation rate that is close to that with a trusted source.

Physical Cryptography: A New Approach to Key Generation and Direct Encryption

DTIC Science & Technology

2009-11-18

has been  further studied theoretically and P a g e  | 4    experimentally to only a limited extent. The second is quantum cryptography [3] based on...Std Z39-18 P a g e  | 2    Abstract: The security of key generation and direct encryption in quantum and physical cryptography have been...investigated. It is found that similar to the situation of conventional mathematics based cryptography , fundamental and meaningful security levels for either

Measurement of generation-dependent proliferation rates and death rates during mouse erythroid progenitor cell differentiation.

PubMed

Akbarian, Vahe; Wang, Weijia; Audet, Julie

2012-05-01

Herein, we describe an experimental and computational approach to perform quantitative carboxyfluorescein diacetate succinimidyl ester (CFSE) cell-division tracking in cultures of primary colony-forming unit-erythroid (CFU-E) cells, a hematopoietic progenitor cell type, which is an important target for the treatment of blood disorders and for the manufacture of red blood cells. CFSE labeling of CFU-Es isolated from mouse fetal livers was performed to examine the effects of stem cell factor (SCF) and erythropoietin (EPO) in culture. We used a dynamic model of proliferation based on the Smith-Martin representation of the cell cycle to extract proliferation rates and death rates from CFSE time-series. However, we found that to accurately represent the cell population dynamics in differentiation cultures of CFU-Es, it was necessary to develop a model with generation-specific rate parameters. The generation-specific rates of proliferation and death were extracted for six generations (G(0) -G(5) ) and they revealed that, although SCF alone or EPO alone supported similar total cell outputs in culture, stimulation with EPO resulted in significantly higher proliferation rates from G(2) to G(5) and higher death rates in G(2) , G(3) , and G(5) compared with SCF. In addition, proliferation rates tended to increase from G(1) to G(5) in cultures supplemented with EPO and EPO + SCF, while they remained lower and more constant across generations with SCF. The results are consistent with the notion that SCF promotes CFU-E self-renewal while EPO promotes CFU-E differentiation in culture. Copyright © 2012 International Society for Advancement of Cytometry.

100 km differential phase shift quantum key distribution experiment with low jitter up-conversion detectors

NASA Astrophysics Data System (ADS)

Diamanti, Eleni; Takesue, Hiroki; Langrock, Carsten; Fejer, M. M.; Yamamoto, Yoshihisa

2006-12-01

We present a quantum key distribution experiment in which keys that were secure against all individual eavesdropping attacks allowed by quantum mechanics were distributed over 100 km of optical fiber. We implemented the differential phase shift quantum key distribution protocol and used low timing jitter 1.55 µm single-photon detectors based on frequency up-conversion in periodically poled lithium niobate waveguides and silicon avalanche photodiodes. Based on the security analysis of the protocol against general individual attacks, we generated secure keys at a practical rate of 166 bit/s over 100 km of fiber. The use of the low jitter detectors also increased the sifted key generation rate to 2 Mbit/s over 10 km of fiber.

Making the decoy-state measurement-device-independent quantum key distribution practically useful

NASA Astrophysics Data System (ADS)

Zhou, Yi-Heng; Yu, Zong-Wen; Wang, Xiang-Bin

2016-04-01

The relatively low key rate seems to be the major barrier to its practical use for the decoy-state measurement-device-independent quantum key distribution (MDI-QKD). We present a four-intensity protocol for the decoy-state MDI-QKD that hugely raises the key rate, especially in the case in which the total data size is not large. Also, calculations show that our method makes it possible for secure private communication with fresh keys generated from MDI-QKD with a delay time of only a few seconds.

Implementation of continuous-variable quantum key distribution with discrete modulation

NASA Astrophysics Data System (ADS)

Hirano, Takuya; Ichikawa, Tsubasa; Matsubara, Takuto; Ono, Motoharu; Oguri, Yusuke; Namiki, Ryo; Kasai, Kenta; Matsumoto, Ryutaroh; Tsurumaru, Toyohiro

2017-06-01

We have developed a continuous-variable quantum key distribution (CV-QKD) system that employs discrete quadrature-amplitude modulation and homodyne detection of coherent states of light. We experimentally demonstrated automated secure key generation with a rate of 50 kbps when a quantum channel is a 10 km optical fibre. The CV-QKD system utilises a four-state and post-selection protocol and generates a secure key against the entangling cloner attack. We used a pulsed light source of 1550 nm wavelength with a repetition rate of 10 MHz. A commercially available balanced receiver is used to realise shot-noise-limited pulsed homodyne detection. We used a non-binary LDPC code for error correction (reverse reconciliation) and the Toeplitz matrix multiplication for privacy amplification. A graphical processing unit card is used to accelerate the software-based post-processing.

Quantum key distribution with an unknown and untrusted source

NASA Astrophysics Data System (ADS)

Zhao, Yi; Qi, Bing; Lo, Hoi-Kwong

2009-03-01

The security of a standard bi-directional ``plug & play'' quantum key distribution (QKD) system has been an open question for a long time. This is mainly because its source is equivalently controlled by an eavesdropper, which means the source is unknown and untrusted. Qualitative discussion on this subject has been made previously. In this paper, we present the first quantitative security analysis on a general class of QKD protocols whose sources are unknown and untrusted. The securities of standard BB84 protocol, weak+vacuum decoy state protocol, and one-decoy decoy state protocol, with unknown and untrusted sources are rigorously proved. We derive rigorous lower bounds to the secure key generation rates of the above three protocols. Our numerical simulation results show that QKD with an untrusted source gives a key generation rate that is close to that with a trusted source. Our work is published in [1]. [4pt] [1] Y. Zhao, B. Qi, and H.-K. Lo, Phys. Rev. A, 77:052327 (2008).

Analysis of municipal waste generation rate in Poland compared to selected European countries

NASA Astrophysics Data System (ADS)

Klojzy-Karczmarczyk, Beata; Makoudi, Said

2017-10-01

The generated municipal waste rates provided in the planning documents are a tool for forecasting the mass of waste generated in individual waste management regions. An important issue is the decisive separation of two concepts: waste generated and waste collected. The study includes analysis of the generation rate for Poland with division into urban and rural areas. The estimated and projected rate of municipal waste generation for Poland provided in subsequent editions of National Waste Management Plans (KPGO) changed since 2000 within wide range from about 300 to more than 500 kg per capita in an individual year (kg/pc/year). Currently, the National Waste Management Plan for the years 2017-2022 estimates municipal waste generation rate at approx. 270 kg/per capita/year with a projected increase to 330 kg/per capita/year in 2030. Most European countries adopt higher municipal waste generation rate, often exceeding 600 kg/per capita/year. The objective of the paper is therefore to analyze the causes of this difference in the declared values. The morphological composition of municipal waste stream in Poland and in selected European countries (e.g. France, Belgium, Switzerland) was analyzed. At present it is not possible to balance the value of the generation rate with the rate of waste collection in Poland. The conducted analyzes allow for determining a number of reasons for variation of the rate value in particular countries, mostly morphological composition of municipal waste, inclusion of household-like waste from infrastructure facilities or not and amount of waste collected in rural areas. The differences in the generation rates and provided possible reasons indicate the need to harmonize the methodology for estimating rates of municipal waste generation in various countries, including Poland.

High-capacity quantum key distribution via hyperentangled degrees of freedom

NASA Astrophysics Data System (ADS)

Simon, David S.; Sergienko, Alexander V.

2014-06-01

Quantum key distribution (QKD) has long been a promising area for the application of quantum effects in solving real-world problems. However, two major obstacles have stood in the way of its widespread application: low secure key generation rates and short achievable operating distances. In this paper, a new physical mechanism for dealing with the first of these problems is proposed: the interplay between different degrees of freedom in a hyperentangled system (parametric down-conversion) is used to increase the Hilbert space dimension available for key generation while maintaining security. Polarization-based Bell tests provide security checking, while orbital angular momentum (OAM) and total angular momentum (TAM) provide a higher key generation rate. Whether to measure TAM or OAM is decided randomly in each trial. The concurrent noncommutativity of TAM with OAM and polarization provides the physical basis for quantum security. TAM measurements link polarization to OAM, so that if the legitimate participants measure OAM while the eavesdropper measures TAM (or vice-versa), then polarization entanglement is lost, revealing the eavesdropper. In contrast to other OAM-based QKD methods, complex active switching between OAM bases is not required; instead, passive switching by beam splitters combined with much simpler active switching between polarization bases makes implementation at high OAM more practical.

Methods and apparatuses for self-generating fault-tolerant keys in spread-spectrum systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moradi, Hussein; Farhang, Behrouz; Subramanian, Vijayarangam

Self-generating fault-tolerant keys for use in spread-spectrum systems are disclosed. At a communication device, beacon signals are received from another communication device and impulse responses are determined from the beacon signals. The impulse responses are circularly shifted to place a largest sample at a predefined position. The impulse responses are converted to a set of frequency responses in a frequency domain. The frequency responses are shuffled with a predetermined shuffle scheme to develop a set of shuffled frequency responses. A set of phase differences is determined as a difference between an angle of the frequency response and an angle ofmore » the shuffled frequency response at each element of the corresponding sets. Each phase difference is quantized to develop a set of secret-key quantized phases and a set of spreading codes is developed wherein each spreading code includes a corresponding phase of the set of secret-key quantized phases.« less

Security of Distributed-Phase-Reference Quantum Key Distribution

NASA Astrophysics Data System (ADS)

Moroder, Tobias; Curty, Marcos; Lim, Charles Ci Wen; Thinh, Le Phuc; Zbinden, Hugo; Gisin, Nicolas

2012-12-01

Distributed-phase-reference quantum key distribution stands out for its easy implementation with present day technology. For many years, a full security proof of these schemes in a realistic setting has been elusive. We solve this long-standing problem and present a generic method to prove the security of such protocols against general attacks. To illustrate our result, we provide lower bounds on the key generation rate of a variant of the coherent-one-way quantum key distribution protocol. In contrast to standard predictions, it appears to scale quadratically with the system transmittance.

Securing quantum key distribution systems using fewer states

NASA Astrophysics Data System (ADS)

Islam, Nurul T.; Lim, Charles Ci Wen; Cahall, Clinton; Kim, Jungsang; Gauthier, Daniel J.

2018-04-01

Quantum key distribution (QKD) allows two remote users to establish a secret key in the presence of an eavesdropper. The users share quantum states prepared in two mutually unbiased bases: one to generate the key while the other monitors the presence of the eavesdropper. Here, we show that a general d -dimension QKD system can be secured by transmitting only a subset of the monitoring states. In particular, we find that there is no loss in the secure key rate when dropping one of the monitoring states. Furthermore, it is possible to use only a single monitoring state if the quantum bit error rates are low enough. We apply our formalism to an experimental d =4 time-phase QKD system, where only one monitoring state is transmitted, and obtain a secret key rate of 17.4 ±2.8 Mbits/s at a 4 dB channel loss and with a quantum bit error rate of 0.045 ±0.001 and 0.037 ±0.001 in time and phase bases, respectively, which is 58.4% of the secret key rate that can be achieved with the full setup. This ratio can be increased, potentially up to 100%, if the error rates in time and phase basis are reduced. Our results demonstrate that it is possible to substantially simplify the design of high-dimensional QKD systems, including those that use the spatial or temporal degrees of freedom of the photon, and still outperform qubit-based (d =2 ) protocols.

Construction and demolition waste generation rates for high-rise buildings in Malaysia.

PubMed

Mah, Chooi Mei; Fujiwara, Takeshi; Ho, Chin Siong

2016-12-01

Construction and demolition waste continues to sharply increase in step with the economic growth of less developed countries. Though the construction industry is large, it is composed of small firms with individual waste management practices, often leading to the deleterious environmental outcomes. Quantifying construction and demolition waste generation allows policy makers and stakeholders to understand the true internal and external costs of construction, providing a necessary foundation for waste management planning that may overcome deleterious environmental outcomes and may be both economically and environmentally optimal. This study offers a theoretical method for estimating the construction and demolition project waste generation rate by utilising available data, including waste disposal truck size and number, and waste volume and composition. This method is proposed as a less burdensome and more broadly applicable alternative, in contrast to waste estimation by on-site hand sorting and weighing. The developed method is applied to 11 projects across Malaysia as the case study. This study quantifies waste generation rate and illustrates the construction method in influencing the waste generation rate, estimating that the conventional construction method has a waste generation rate of 9.88 t 100 m -2 , the mixed-construction method has a waste generation rate of 3.29 t 100 m -2 , and demolition projects have a waste generation rate of 104.28 t 100 m -2 . © The Author(s) 2016.

Practical passive decoy state measurement-device-independent quantum key distribution with unstable sources.

PubMed

Liu, Li; Guo, Fen-Zhuo; Wen, Qiao-Yan

2017-09-12

Measurement-device-independent quantum key distribution (MDI-QKD) with the active decoy state method can remove all detector loopholes, and resist the imperfections of sources. But it may lead to side channel attacks and break the security of QKD system. In this paper, we apply the passive decoy state method to the MDI-QKD based on polarization encoding mode. Not only all attacks on detectors can be removed, but also the side channel attacks on sources can be overcome. We get that the MDI-QKD with our passive decoy state method can have a performance comparable to the protocol with the active decoy state method. To fit for the demand of practical application, we discuss intensity fluctuation in the security analysis of MDI-QKD protocol using passive decoy state method, and derive the key generation rate for our protocol with intensity fluctuation. It shows that intensity fluctuation has an adverse effect on the key generation rate which is non-negligible, especially in the case of small data size of total transmitting signals and long distance transmission. We give specific simulations on the relationship between intensity fluctuation and the key generation rate. Furthermore, the statistical fluctuation due to the finite length of data is also taken into account.

Adaptive spatial filtering for daytime satellite quantum key distribution

NASA Astrophysics Data System (ADS)

Gruneisen, Mark T.; Sickmiller, Brett A.; Flanagan, Michael B.; Black, James P.; Stoltenberg, Kurt E.; Duchane, Alexander W.

2014-11-01

The rate of secure key generation (SKG) in quantum key distribution (QKD) is adversely affected by optical noise and loss in the quantum channel. In a free-space atmospheric channel, the scattering of sunlight into the channel can lead to quantum bit error ratios (QBERs) sufficiently large to preclude SKG. Furthermore, atmospheric turbulence limits the degree to which spatial filtering can reduce sky noise without introducing signal losses. A system simulation quantifies the potential benefit of tracking and higher-order adaptive optics (AO) technologies to SKG rates in a daytime satellite engagement scenario. The simulations are performed assuming propagation from a low-Earth orbit (LEO) satellite to a terrestrial receiver that includes an AO system comprised of a Shack-Hartmann wave-front sensor (SHWFS) and a continuous-face-sheet deformable mirror (DM). The effects of atmospheric turbulence, tracking, and higher-order AO on the photon capture efficiency are simulated using statistical representations of turbulence and a time-domain waveoptics hardware emulator. Secure key generation rates are then calculated for the decoy state QKD protocol as a function of the receiver field of view (FOV) for various pointing angles. The results show that at FOVs smaller than previously considered, AO technologies can enhance SKG rates in daylight and even enable SKG where it would otherwise be prohibited as a consequence of either background optical noise or signal loss due to turbulence effects.

Quantum Key Distribution

NASA Astrophysics Data System (ADS)

Hughes, Richard

2004-05-01

Quantum key distribution (QKD) uses single-photon communications to generate the shared, secret random number sequences that are used to encrypt and decrypt secret communications. The unconditional security of QKD is based on the interplay between fundamental principles of quantum physics and information theory. An adversary can neither successfully tap the transmissions, nor evade detection (eavesdropping raises the key error rate above a threshold value). QKD could be particularly attractive for free-space optical communications, both ground-based and for satellites. I will describe a QKD experiment performed over multi-kilometer line-of-sight paths, which serves as a model for a satellite-to-ground key distribution system. The system uses single-photon polarization states, without active polarization switching, and for the first time implements the complete BB84 QKD protocol including, reconciliation, privacy amplification and the all-important authentication stage. It is capable of continuous operation throughout the day and night, achieving the self-sustaining production of error-free, shared, secret bits. I will also report on the results of satellite-to-ground QKD modeling.

Generation rate of carbon monoxide from CO2 arc welding.

PubMed

Ojima, Jun

2013-01-01

CO poisoning has been a serious industrial hazard in Japanese workplaces. Although incomplete combustion is the major cause of CO generation, there is a risk of CO poisoning during some welding operations. The aim of the present study was to evaluate the generation rate of CO from CO2 arc welding under controlled laboratory conditions and estimate the ventilation requirements for the prevention of CO poisoning. Bead on plate welding was carried out with an automatic welding robot on a rolled steel base metal under several conditions. The concentration of emitted CO from the welding was measured by a real-time CO monitor in a well-ventilated laboratory that was free from ambient CO contamination. The generation rate of CO was obtained from the three measurements-the flow rate of the welding exhaust gas, CO concentration in the exhaust gas and the arcing time. Then the ventilation requirement to prevent CO poisoning was calculated. The generation rate of CO was found to be 386-883 ml/min with a solid wire and 331-1,293 ml/min with a flux cored wire respectively. It was found that the CO concentration in a room would be maintained theoretically below the OSHA PEL (50 ppm) providing the ventilation rate in the room was 6.6-25.9 m3/min. The actual ventilation requirement was then estimated to be 6.6-259 m3/min considering incomplete mixing. In order to prevent CO poisoning, some countermeasures against gaseous emission as well as welding fumes should be taken eagerly.

Determination of LEDs degradation with entropy generation rate

NASA Astrophysics Data System (ADS)

Cuadras, Angel; Yao, Jiaqiang; Quilez, Marcos

2017-10-01

We propose a method to assess the degradation and aging of light emitting diodes (LEDs) based on irreversible entropy generation rate. We degraded several LEDs and monitored their entropy generation rate ( S ˙ ) in accelerated tests. We compared the thermoelectrical results with the optical light emission evolution during degradation. We find a good relationship between aging and S ˙ (t), because S ˙ is both related to device parameters and optical performance. We propose a threshold of S ˙ (t) as a reliable damage indicator of LED end-of-life that can avoid the need to perform optical measurements to assess optical aging. The method lays beyond the typical statistical laws for lifetime prediction provided by manufacturers. We tested different LED colors and electrical stresses to validate the electrical LED model and we analyzed the degradation mechanisms of the devices.

Compressed Secret Key Agreement:Maximizing Multivariate Mutual Information per Bit

NASA Astrophysics Data System (ADS)

Chan, Chung

2017-10-01

The multiterminal secret key agreement problem by public discussion is formulated with an additional source compression step where, prior to the public discussion phase, users independently compress their private sources to filter out strongly correlated components for generating a common secret key. The objective is to maximize the achievable key rate as a function of the joint entropy of the compressed sources. Since the maximum achievable key rate captures the total amount of information mutual to the compressed sources, an optimal compression scheme essentially maximizes the multivariate mutual information per bit of randomness of the private sources, and can therefore be viewed more generally as a dimension reduction technique. Single-letter lower and upper bounds on the maximum achievable key rate are derived for the general source model, and an explicit polynomial-time computable formula is obtained for the pairwise independent network model. In particular, the converse results and the upper bounds are obtained from those of the related secret key agreement problem with rate-limited discussion. A precise duality is shown for the two-user case with one-way discussion, and such duality is extended to obtain the desired converse results in the multi-user case. In addition to posing new challenges in information processing and dimension reduction, the compressed secret key agreement problem helps shed new light on resolving the difficult problem of secret key agreement with rate-limited discussion, by offering a more structured achieving scheme and some simpler conjectures to prove.

Generating the Local Oscillator "Locally" in Continuous-Variable Quantum Key Distribution Based on Coherent Detection

NASA Astrophysics Data System (ADS)

Qi, Bing; Lougovski, Pavel; Pooser, Raphael; Grice, Warren; Bobrek, Miljko

2015-10-01

Continuous-variable quantum key distribution (CV-QKD) protocols based on coherent detection have been studied extensively in both theory and experiment. In all the existing implementations of CV-QKD, both the quantum signal and the local oscillator (LO) are generated from the same laser and propagate through the insecure quantum channel. This arrangement may open security loopholes and limit the potential applications of CV-QKD. In this paper, we propose and demonstrate a pilot-aided feedforward data recovery scheme that enables reliable coherent detection using a "locally" generated LO. Using two independent commercial laser sources and a spool of 25-km optical fiber, we construct a coherent communication system. The variance of the phase noise introduced by the proposed scheme is measured to be 0.04 (rad2 ), which is small enough to enable secure key distribution. This technology also opens the door for other quantum communication protocols, such as the recently proposed measurement-device-independent CV-QKD, where independent light sources are employed by different users.

Efficient and universal quantum key distribution based on chaos and middleware

NASA Astrophysics Data System (ADS)

Jiang, Dong; Chen, Yuanyuan; Gu, Xuemei; Xie, Ling; Chen, Lijun

2017-01-01

Quantum key distribution (QKD) promises unconditionally secure communications, however, the low bit rate of QKD cannot meet the requirements of high-speed applications. Despite the many solutions that have been proposed in recent years, they are neither efficient to generate the secret keys nor compatible with other QKD systems. This paper, based on chaotic cryptography and middleware technology, proposes an efficient and universal QKD protocol that can be directly deployed on top of any existing QKD system without modifying the underlying QKD protocol and optical platform. It initially takes the bit string generated by the QKD system as input, periodically updates the chaotic system, and efficiently outputs the bit sequences. Theoretical analysis and simulation results demonstrate that our protocol can efficiently increase the bit rate of the QKD system as well as securely generate bit sequences with perfect statistical properties. Compared with the existing methods, our protocol is more efficient and universal, it can be rapidly deployed on the QKD system to increase the bit rate when the QKD system becomes the bottleneck of its communication system.

High-speed wavelength-division multiplexing quantum key distribution system.

PubMed

Yoshino, Ken-ichiro; Fujiwara, Mikio; Tanaka, Akihiro; Takahashi, Seigo; Nambu, Yoshihiro; Tomita, Akihisa; Miki, Shigehito; Yamashita, Taro; Wang, Zhen; Sasaki, Masahide; Tajima, Akio

2012-01-15

A high-speed quantum key distribution system was developed with the wavelength-division multiplexing (WDM) technique and dedicated key distillation hardware engines. Two interferometers for encoding and decoding are shared over eight wavelengths to reduce the system's size, cost, and control complexity. The key distillation engines can process a huge amount of data from the WDM channels by using a 1 Mbit block in real time. We demonstrated a three-channel WDM system that simultaneously uses avalanche photodiodes and superconducting single-photon detectors. We achieved 12 h continuous key generation with a secure key rate of 208 kilobits per second through a 45 km field fiber with 14.5 dB loss.

Free-Space Quantum Key Distribution using Polarization Entangled Photons

NASA Astrophysics Data System (ADS)

Kurtsiefer, Christian

2007-06-01

We report on a complete experimental implementation of a quantum key distribution protocol through a free space link using polarization-entangled photon pairs from a compact parametric down-conversion source [1]. Based on a BB84-equivalent protocol, we generated without interruption over 10 hours a secret key free-space optical link distance of 1.5 km with a rate up to 950 bits per second after error correction and privacy amplification. Our system is based on two time stamp units and relies on no specific hardware channel for coincidence identification besides an IP link. For that, initial clock synchronization with an accuracy of better than 2 ns is achieved, based on a conventional NTP protocol and a tiered cross correlation of time tags on both sides. Time tags are used to servo a local clock, allowing a streamed measurement on correctly identified photon pairs. Contrary to the majority of quantum key distribution systems, this approach does not require a trusted large-bandwidth random number generator, but integrates that into the physical key generation process. We discuss our current progress of implementing a key distribution via an atmospherical link during daylight conditions, and possible attack scenarios on a physical timing information side channel to a entanglement-based key distribution system. [1] I. Marcikic, A. Lamas-Linares, C. Kurtsiefer, Appl. Phys. Lett. 89, 101122 (2006).

Respiratory rate detection using a wearable electromagnetic generator.

PubMed

Padasdao, Bryson; Boric-Lubecke, Olga

2011-01-01

Wearable health and fitness monitoring systems are a promising new way of collecting physiological data without inconveniencing patients. Human energy harvesting may be used to power wearable sensors. In this paper, we explore this zero-net energy biosensor concept through sensing and harvesting of respiratory effort. An off the shelf servo motor operation in reverse was used to successfully obtain respiratory rate, while also demonstrating significant harvested power. These are the first reported respiratory rate sensing results using electromagnetic generators.

Channel analysis for single photon underwater free space quantum key distribution.

PubMed

Shi, Peng; Zhao, Shi-Cheng; Gu, Yong-Jian; Li, Wen-Dong

2015-03-01

We investigate the optical absorption and scattering properties of underwater media pertinent to our underwater free space quantum key distribution (QKD) channel model. With the vector radiative transfer theory and Monte Carlo method, we obtain the attenuation of photons, the fidelity of the scattered photons, the quantum bit error rate, and the sifted key generation rate of underwater quantum communication. It can be observed from our simulations that the most secure single photon underwater free space QKD is feasible in the clearest ocean water.

Passive measurement-device-independent quantum key distribution with orbital angular momentum and pulse position modulation

NASA Astrophysics Data System (ADS)

Wang, Lian; Zhou, Yuan-yuan; Zhou, Xue-jun; Chen, Xiao

2018-03-01

Based on the orbital angular momentum and pulse position modulation, we present a novel passive measurement-device-independent quantum key distribution (MDI-QKD) scheme with the two-mode source. Combining with the tight bounds of the yield and error rate of single-photon pairs given in our paper, we conduct performance analysis on the scheme with heralded single-photon source. The numerical simulations show that the performance of our scheme is significantly superior to the traditional MDI-QKD in the error rate, key generation rate and secure transmission distance, since the application of orbital angular momentum and pulse position modulation can exclude the basis-dependent flaw and increase the information content for each single photon. Moreover, the performance is improved with the rise of the frame length. Therefore, our scheme, without intensity modulation, avoids the source side channels and enhances the key generation rate. It has greatly utility value in the MDI-QKD setups.

An adaptation method to improve secret key rates of time-frequency QKD in atmospheric turbulence channels

NASA Astrophysics Data System (ADS)

Sun, Xiaole; Djordjevic, Ivan B.; Neifeld, Mark A.

2016-03-01

Free-space optical (FSO) channels can be characterized by random power fluctuations due to atmospheric turbulence, which is known as scintillation. Weak coherent source based FSO quantum key distribution (QKD) systems suffer from the scintillation effect because during the deep channel fading the expected detection rate drops, which then gives an eavesdropper opportunity to get additional information about protocol by performing photon number splitting (PNS) attack and blocking single-photon pulses without changing QBER. To overcome this problem, in this paper, we study a large-alphabet QKD protocol, which is achieved by using pulse-position modulation (PPM)-like approach that utilizes the time-frequency uncertainty relation of the weak coherent photon state, called here TF-PPM-QKD protocol. We first complete finite size analysis for TF-PPM-QKD protocol to give practical bounds against non-negligible statistical fluctuation due to finite resources in practical implementations. The impact of scintillation under strong atmospheric turbulence regime is studied then. To overcome the secure key rate performance degradation of TF-PPM-QKD caused by scintillation, we propose an adaptation method for compensating the scintillation impact. By changing source intensity according to the channel state information (CSI), obtained by classical channel, the adaptation method improves the performance of QKD system with respect to the secret key rate. The CSI of a time-varying channel can be predicted using stochastic models, such as autoregressive (AR) models. Based on the channel state predictions, we change the source intensity to the optimal value to achieve a higher secret key rate. We demonstrate that the improvement of the adaptation method is dependent on the prediction accuracy.

Generation of µW level plateau harmonics at high repetition rate.

PubMed

Hädrich, S; Krebs, M; Rothhardt, J; Carstens, H; Demmler, S; Limpert, J; Tünnermann, A

2011-09-26

The process of high harmonic generation allows for coherent transfer of infrared laser light to the extreme ultraviolet spectral range opening a variety of applications. The low conversion efficiency of this process calls for optimization or higher repetition rate intense ultrashort pulse lasers. Here we present state-of-the-art fiber laser systems for the generation of high harmonics up to 1 MHz repetition rate. We perform measurements of the average power with a calibrated spectrometer and achieved µW harmonics between 45 nm and 61 nm (H23-H17) at a repetition rate of 50 kHz. Additionally, we show the potential for few-cycle pulses at high average power and repetition rate that may enable water-window harmonics at unprecedented repetition rate. © 2011 Optical Society of America

Quantum key distribution with passive decoy state selection

NASA Astrophysics Data System (ADS)

Mauerer, Wolfgang; Silberhorn, Christine

2007-05-01

We propose a quantum key distribution scheme which closely matches the performance of a perfect single photon source. It nearly attains the physical upper bound in terms of key generation rate and maximally achievable distance. Our scheme relies on a practical setup based on a parametric downconversion source and present day, nonideal photon-number detection. Arbitrary experimental imperfections which lead to bit errors are included. We select decoy states by classical postprocessing. This allows one to improve the effective signal statistics and achievable distance.

Long-distance quantum key distribution with imperfect devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lo Piparo, Nicoló; Razavi, Mohsen

2014-12-04

Quantum key distribution over probabilistic quantum repeaters is addressed. We compare, under practical assumptions, two such schemes in terms of their secure key generation rate per memory, R{sub QKD}. The two schemes under investigation are the one proposed by Duan et al. in [Nat. 414, 413 (2001)] and that of Sangouard et al. proposed in [Phys. Rev. A 76, 050301 (2007)]. We consider various sources of imperfections in the latter protocol, such as a nonzero double-photon probability for the source, dark count per pulse, channel loss and inefficiencies in photodetectors and memories, to find the rate for different nesting levels.more » We determine the maximum value of the double-photon probability beyond which it is not possible to share a secret key anymore. We find the crossover distance for up to three nesting levels. We finally compare the two protocols.« less

Generating the local oscillator "locally" in continuous-variable quantum key distribution based on coherent detection

DOE PAGES

Qi, Bing; Lougovski, Pavel; Pooser, Raphael C.; ...

2015-10-21

Continuous-variable quantum key distribution (CV-QKD) protocols based on coherent detection have been studied extensively in both theory and experiment. In all the existing implementations of CV-QKD, both the quantum signal and the local oscillator (LO) are generated from the same laser and propagate through the insecure quantum channel. This arrangement may open security loopholes and limit the potential applications of CV-QKD. In our paper, we propose and demonstrate a pilot-aided feedforward data recovery scheme that enables reliable coherent detection using a “locally” generated LO. Using two independent commercial laser sources and a spool of 25-km optical fiber, we construct amore » coherent communication system. The variance of the phase noise introduced by the proposed scheme is measured to be 0.04 (rad 2), which is small enough to enable secure key distribution. This technology opens the door for other quantum communication protocols, such as the recently proposed measurement-device-independent CV-QKD, where independent light sources are employed by different users.« less

Ultra fast quantum key distribution over a 97 km installed telecom fiber with wavelength division multiplexing clock synchronization.

PubMed

Tanaka, Akihiro; Fujiwara, Mikio; Nam, Sae W; Nambu, Yoshihiro; Takahashi, Seigo; Maeda, Wakako; Yoshino, Ken-ichiro; Miki, Shigehito; Baek, Burm; Wang, Zhen; Tajima, Akio; Sasaki, Masahide; Tomita, Akihisa

2008-07-21

We demonstrated ultra fast BB84 quantum key distribution (QKD) transmission at 625 MHz clock rate through a 97 km field-installed fiber using practical clock synchronization based on wavelength-division multiplexing (WDM). We succeeded in over-one-hour stable key generation at a high sifted key rate of 2.4 kbps and a low quantum bit error rate (QBER) of 2.9%. The asymptotic secure key rate was estimated to be 0.78- 0.82 kbps from the transmission data with the decoy method of average photon numbers 0, 0.15, and 0.4 photons/pulse.

Landfill gas generation after mechanical biological treatment of municipal solid waste. Estimation of gas generation rate constants.

PubMed

Gioannis, G De; Muntoni, A; Cappai, G; Milia, S

2009-03-01

Mechanical biological treatment (MBT) of residual municipal solid waste (RMSW) was investigated with respect to landfill gas generation. Mechanically treated RMSW was sampled at a full-scale plant and aerobically stabilized for 8 and 15 weeks. Anaerobic tests were performed on the aerobically treated waste (MBTW) in order to estimate the gas generation rate constants (k,y(-1)), the potential gas generation capacity (L(o), Nl/kg) and the amount of gasifiable organic carbon. Experimental results show how MBT allowed for a reduction of the non-methanogenic phase and of the landfill gas generation potential by, respectively, 67% and 83% (8 weeks treatment), 82% and 91% (15 weeks treatment), compared to the raw waste. The amount of gasified organic carbon after 8 weeks and 15 weeks of treatment was equal to 11.01+/-1.25kgC/t(MBTW) and 4.54+/-0.87kgC/t(MBTW), respectively, that is 81% and 93% less than the amount gasified from the raw waste. The values of gas generation rate constants obtained for MBTW anaerobic degradation (0.0347-0.0803y(-1)) resemble those usually reported for the slowly and moderately degradable fractions of raw MSW. Simulations performed using a prediction model support the hypothesis that due to the low production rate, gas production from MBTW landfills is well-suited to a passive management strategy.

Fume generation rates for stainless steel, nickel and aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castner, H.R.

1996-12-01

This paper describes a study of the effects of pulsed welding current on fume produced during gas metal arc welding (GMAW) of stainless steel, nickel, and aluminum alloys. This is an extension of earlier studies of mild steel electrode wire. Reduction of welding fume is important because steady current GMAW of stainless steels and nickel alloys may produce fume that exceeds recommended worker exposure limits for some of the fume constituents. Fume generation from aluminum alloy ER5356 was studied because steady current welding with this alloy produces much higher fume generation rates than ER4043 alloy electrode wire. This work showsmore » that pulsed current can reduce GMAW fume generation rates for Er308L, ER310, and ER312 stainless steel, ERNiCr-3 nickel alloy, and ER5356 aluminum-magnesium alloy electrode wires.« less

Impact of socioeconomic status on municipal solid waste generation rate.

PubMed

Khan, D; Kumar, A; Samadder, S R

2016-03-01

The solid waste generation rate was expected to vary in different socioeconomic groups due to many environmental and social factors. This paper reports the assessment of solid waste generation based on different socioeconomic parameters like education, occupation, income of the family, number of family members etc. A questionnaire survey was conducted in the study area to identify the different socioeconomic groups that may affect the solid waste generation rate and composition. The average waste generated in the municipality is 0.41 kg/capita/day in which the maximum waste was found to be generated by lower middle socioeconomic group (LMSEG) with average waste generation of 0.46 kg/capita/day. Waste characterization indicated that there was no much difference in the composition of wastes among different socioeconomic groups except ash residue and plastic. Ash residue is found to increase as we move lower down the socioeconomic groups with maximum (31%) in lower socioeconomic group (LSEG). The study area is a coal based city hence application of coal and wood as fuel for cooking in the lower socioeconomic group is the reason for high amount of ash content. Plastic waste is maximum (15%) in higher socioeconomic group (HSEG) and minimum (1%) in LSEG. Food waste is a major component of generated waste in almost every socioeconomic group with maximum (38%) in case of HSEG and minimum (28%) in LSEG. This study provides new insights on the role of various socioeconomic parameters on generation of household wastes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Public-key quantum digital signature scheme with one-time pad private-key

NASA Astrophysics Data System (ADS)

Chen, Feng-Lin; Liu, Wan-Fang; Chen, Su-Gen; Wang, Zhi-Hua

2018-01-01

A quantum digital signature scheme is firstly proposed based on public-key quantum cryptosystem. In the scheme, the verification public-key is derived from the signer's identity information (such as e-mail) on the foundation of identity-based encryption, and the signature private-key is generated by one-time pad (OTP) protocol. The public-key and private-key pair belongs to classical bits, but the signature cipher belongs to quantum qubits. After the signer announces the public-key and generates the final quantum signature, each verifier can verify publicly whether the signature is valid or not with the public-key and quantum digital digest. Analysis results show that the proposed scheme satisfies non-repudiation and unforgeability. Information-theoretic security of the scheme is ensured by quantum indistinguishability mechanics and OTP protocol. Based on the public-key cryptosystem, the proposed scheme is easier to be realized compared with other quantum signature schemes under current technical conditions.

Generator replacement is associated with an increased rate of ICD lead alerts.

PubMed

Lovelock, Joshua D; Cruz, Cesar; Hoskins, Michael H; Jones, Paul; El-Chami, Mikhael F; Lloyd, Michael S; Leon, Angel; DeLurgio, David B; Langberg, Jonathan J

2014-10-01

Lead malfunction is an important cause of morbidity and mortality in patients with an implantable cardioverter-defibrillator (ICD). We have shown that the failure of recalled high-voltage leads significantly increases after ICD generator replacement. However, generator replacement has not been recognized as a predictor of lead failure in general. The purpose of this study is to assess the effect of ICD generator exchange on the rate of ICD lead alerts. A time-dependent Cox proportional hazards model was used to analyze a database of remotely monitored ICDs. The model assessed the impact of generator exchange on the rate of lead alerts after ICD generator replacement. The analysis included 60,219 patients followed for 37 ± 19 months. The 5-year lead survival was 99.3% (95% confidence interval 99.2%-99.4%). Of 60,219 patients, 7458 patients (12.9%) underwent ICD generator exchange without lead replacement. After generator replacement, the rate of lead alerts was more than 5-fold higher than in controls with leads of the same age without generator replacement (hazard ratio 5.19; 95% confidence interval 3.45-7.84). A large number of lead alerted within 3 months of generator replacement. Lead alerts were more common in patients with single- vs dual-chamber ICDs and in younger patients. Sex was not associated with lead alerts. Routine generator replacement is associated with a 5-fold higher risk of lead alert compared to age-matched leads without generator replacement. This suggests the need for intense surveillance after generator replacement and the development of techniques to minimize the risk of lead damage during generator replacement. Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Participation rate or informed choice? Rethinking the European key performance indicators for mammography screening.

PubMed

Strech, Daniel

2014-03-01

Despite the intensive controversies about the likelihood of benefits and harms of mammography screening almost all experts conclude that the choice to screen or not to screen needs to be made by the individual patient who is adequately informed. However, the "European guideline for quality assurance in breast cancer screening and diagnosis" specifies a participation rate of 70% as the key performance indicator for mammography screening. This paper argues that neither the existing evidence on benefits and harms, nor survey research with women, nor compliance rates in clinical trials, nor cost-effectiveness ratios justify participation rates as a reasonable performance indicator for preference-sensitive condition such as mammography screening. In contrast, an informed choice rate would be more reasonable. Further research needs to address the practical challenges in assessing informed choice rates. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Continuous operation of four-state continuous-variable quantum key distribution system

NASA Astrophysics Data System (ADS)

Matsubara, Takuto; Ono, Motoharu; Oguri, Yusuke; Ichikawa, Tsubasa; Hirano, Takuya; Kasai, Kenta; Matsumoto, Ryutaroh; Tsurumaru, Toyohiro

2016-10-01

We report on the development of continuous-variable quantum key distribution (CV-QKD) system that are based on discrete quadrature amplitude modulation (QAM) and homodyne detection of coherent states of light. We use a pulsed light source whose wavelength is 1550 nm and repetition rate is 10 MHz. The CV-QKD system can continuously generate secret key which is secure against entangling cloner attack. Key generation rate is 50 kbps when the quantum channel is a 10 km optical fiber. The CV-QKD system we have developed utilizes the four-state and post-selection protocol [T. Hirano, et al., Phys. Rev. A 68, 042331 (2003).]; Alice randomly sends one of four states {|+/-α⟩,|+/-𝑖α⟩}, and Bob randomly performs x- or p- measurement by homodyne detection. A commercially available balanced receiver is used to realize shot-noise-limited pulsed homodyne detection. GPU cards are used to accelerate the software-based post-processing. We use a non-binary LDPC code for error correction (reverse reconciliation) and the Toeplitz matrix multiplication for privacy amplification.

Finite key analysis for symmetric attacks in quantum key distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, Tim; Kampermann, Hermann; Kleinmann, Matthias

2006-10-15

We introduce a constructive method to calculate the achievable secret key rate for a generic class of quantum key distribution protocols, when only a finite number n of signals is given. Our approach is applicable to all scenarios in which the quantum state shared by Alice and Bob is known. In particular, we consider the six state protocol with symmetric eavesdropping attacks, and show that for a small number of signals, i.e., below n{approx}10{sup 4}, the finite key rate differs significantly from the asymptotic value for n{yields}{infinity}. However, for larger n, a good approximation of the asymptotic value is found.more » We also study secret key rates for protocols using higher-dimensional quantum systems.« less

Evaluating a Bilingual Text-Mining System with a Taxonomy of Key Words and Hierarchical Visualization for Understanding Learner-Generated Text

ERIC Educational Resources Information Center

Kong, Siu Cheung; Li, Ping; Song, Yanjie

2018-01-01

This study evaluated a bilingual text-mining system, which incorporated a bilingual taxonomy of key words and provided hierarchical visualization, for understanding learner-generated text in the learning management systems through automatic identification and counting of matching key words. A class of 27 in-service teachers studied a course…

A Model-Based Investigation of Charge-Generation According to the Relative Diffusional Growth Rate Theory

NASA Astrophysics Data System (ADS)

Glassmeier, F.; Arnold, L.; Lohmann, U.; Dietlicher, R.; Paukert, M.

2016-12-01

Our current understanding of charge generation in thunderclouds is based on collisional charge transfer between graupel and ice crystals in the presence of liquid water droplets as dominant mechanism. The physical process of charge transfer and the sign of net charge generated on graupel and ice crystals under different cloud conditions is not yet understood. The Relative-Diffusional-Growth-Rate (RDGR) theory (Baker et al. 1987) suggests that the particle with the faster diffusional radius growth is charged positively. In this contribution, we use simulations of idealized thunderclouds with two-moment warm and cold cloud microphysics to generate realistic combinations of RDGR-parameters. We find that these realistic parameter combinations result in a relationship between sign of charge, cloud temperature and effective water content that deviates from previous theoretical and laboratory studies. This deviation indicates that the RDGR theory is sensitive to correlations between parameters that occur in clouds but are not captured in studies that vary temperature and water content while keeping other parameters at fixed values. In addition, our results suggest that diffusional growth from the riming-related local water vapor field, a key component of the RDGR theory, is negligible for realistic parameter combinations. Nevertheless, we confirm that the RDGR theory results in positive or negative charging of particles under different cloud conditions. Under specific conditions, charge generation via the RDGR theory alone might thus be sufficient to explain tripolar charge structures in thunderclouds. In general, however, additional charge generation mechanisms and adaptations to the RDGR theory that consider riming other than via local vapor deposition seem necessary.

Quantum-key-distribution protocol with pseudorandom bases

NASA Astrophysics Data System (ADS)

Trushechkin, A. S.; Tregubov, P. A.; Kiktenko, E. O.; Kurochkin, Y. V.; Fedorov, A. K.

2018-01-01

Quantum key distribution (QKD) offers a way for establishing information-theoretical secure communications. An important part of QKD technology is a high-quality random number generator for the quantum-state preparation and for post-processing procedures. In this work, we consider a class of prepare-and-measure QKD protocols, utilizing additional pseudorandomness in the preparation of quantum states. We study one of such protocols and analyze its security against the intercept-resend attack. We demonstrate that, for single-photon sources, the considered protocol gives better secret key rates than the BB84 and the asymmetric BB84 protocols. However, the protocol strongly requires single-photon sources.

Quantum key distribution using continuous-variable non-Gaussian states

NASA Astrophysics Data System (ADS)

Borelli, L. F. M.; Aguiar, L. S.; Roversi, J. A.; Vidiella-Barranco, A.

2016-02-01

In this work, we present a quantum key distribution protocol using continuous-variable non-Gaussian states, homodyne detection and post-selection. The employed signal states are the photon added then subtracted coherent states (PASCS) in which one photon is added and subsequently one photon is subtracted from the field. We analyze the performance of our protocol, compared with a coherent state-based protocol, for two different attacks that could be carried out by the eavesdropper (Eve). We calculate the secret key rate transmission in a lossy line for a superior channel (beam-splitter) attack, and we show that we may increase the secret key generation rate by using the non-Gaussian PASCS rather than coherent states. We also consider the simultaneous quadrature measurement (intercept-resend) attack, and we show that the efficiency of Eve's attack is substantially reduced if PASCS are used as signal states.

Evolution of supersaturation of amorphous pharmaceuticals: the effect of rate of supersaturation generation.

PubMed

Sun, Dajun D; Lee, Ping I

2013-11-04

The combination of a rapidly dissolving and supersaturating "spring" with a precipitation retarding "parachute" has often been pursued as an effective formulation strategy for amorphous solid dispersions (ASDs) to enhance the rate and extent of oral absorption. However, the interplay between these two rate processes in achieving and maintaining supersaturation remains inadequately understood, and the effect of rate of supersaturation buildup on the overall time evolution of supersaturation during the dissolution of amorphous solids has not been explored. The objective of this study is to investigate the effect of supersaturation generation rate on the resulting kinetic solubility profiles of amorphous pharmaceuticals and to delineate the evolution of supersaturation from a mechanistic viewpoint. Experimental concentration-time curves under varying rates of supersaturation generation and recrystallization for model drugs, indomethacin (IND), naproxen (NAP) and piroxicam (PIR), were generated from infusing dissolved drug (e.g., in ethanol) into the dissolution medium and compared with that predicted from a comprehensive mechanistic model based on the classical nucleation theory taking into account both the particle growth and ripening processes. In the absence of any dissolved polymer to inhibit drug precipitation, both our experimental and predicted results show that the maximum achievable supersaturation (i.e., kinetic solubility) of the amorphous solids increases, the time to reach maximum decreases, and the rate of concentration decline in the de-supersaturation phase increases, with increasing rate of supersaturation generation (i.e., dissolution rate). Our mechanistic model also predicts the existence of an optimal supersaturation rate which maximizes the area under the curve (AUC) of the kinetic solubility concentration-time profile, which agrees well with experimental data. In the presence of a dissolved polymer from ASD dissolution, these observed trends

Optimal attacks on qubit-based Quantum Key Recycling

NASA Astrophysics Data System (ADS)

Leermakers, Daan; Škorić, Boris

2018-03-01

Quantum Key Recycling (QKR) is a quantum cryptographic primitive that allows one to reuse keys in an unconditionally secure way. By removing the need to repeatedly generate new keys, it improves communication efficiency. Škorić and de Vries recently proposed a QKR scheme based on 8-state encoding (four bases). It does not require quantum computers for encryption/decryption but only single-qubit operations. We provide a missing ingredient in the security analysis of this scheme in the case of noisy channels: accurate upper bounds on the required amount of privacy amplification. We determine optimal attacks against the message and against the key, for 8-state encoding as well as 4-state and 6-state conjugate coding. We provide results in terms of min-entropy loss as well as accessible (Shannon) information. We show that the Shannon entropy analysis for 8-state encoding reduces to the analysis of quantum key distribution, whereas 4-state and 6-state suffer from additional leaks that make them less effective. From the optimal attacks we compute the required amount of privacy amplification and hence the achievable communication rate (useful information per qubit) of qubit-based QKR. Overall, 8-state encoding yields the highest communication rates.

Preservation of a lower bound of quantum secret key rate in the presence of decoherence

NASA Astrophysics Data System (ADS)

Datta, Shounak; Goswami, Suchetana; Pramanik, Tanumoy; Majumdar, A. S.

2017-03-01

It is well known that the interaction of quantum systems with the environment reduces the inherent quantum correlations. Under special circumstances the effect of decoherence can be reversed, for example, the interaction modelled by an amplitude damping channel can boost the teleportation fidelity from the classical to the quantum region for a bipartite quantum state. Here, we first show that this phenomenon fails to preserve the quantum secret key rate derived under individual attack. We further show that the technique of weak measurement can be used to slow down the process of decoherence, thereby helping to preserve the quantum secret key rate when one or both systems are interacting with the environment via an amplitude damping channel. Most interestingly, in certain cases weak measurement with post-selection where one considers both success and failure of the technique is shown to be more useful than without it when both systems interact with the environment.

Generator exchange is associated with an increased rate of Sprint Fidelis lead failure.

PubMed

Lovelock, Joshua D; Patel, Ayesha; Mengistu, Andenet; Hoskins, Michael; El-Chami, Mikhael; Lloyd, Michael S; Leon, Angel; DeLurgio, David; Langberg, Jonathan J

2012-10-01

The Medtronic Sprint Fidelis defibrillator lead is at an increased risk for failure and was recalled in October 2007. Approximately 268,000 leads were implanted, and more than 100,000 patients still have active Fidelis leads. A number of studies have examined the rate and clinical predictors of lead failure, but none has addressed the effect of an implantable cardioverter-defibrillator generator exchange on subsequent lead failure. Although the manufacturer asserts that "Sprint Fidelis performance after device change-out is similar to lead performance without device change-out," published data are lacking. To assess the effect of implantable cardioverter-defibrillator generator exchange on the rate of Fidelis lead failure. A chart review was conducted in patients who underwent implantation of a Fidelis lead. Patients with a functioning Fidelis lead at generator exchange were compared with controls with leads implanted for a comparable amount of time not undergoing ICD replacement. A total of 1366 patients received a Fidelis lead prior to the recall, of which 479 were still actively followed. Seventy-two patients with a functioning lead underwent generator exchange without lead replacement. Following generator replacement, 15 leads failed. Sixty percent of the Fidelis leads failed within 3 months. Generator exchange increased the rate of lead failure compared with matched controls (20.8% vs 2.54%; P < .001). Generator exchange is associated with a higher than expected rate of Fidelis lead failure, often within 3 months. The risk-benefit ratio of Fidelis lead replacement at the time of generator exchange may be greater than appreciated. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Motor unit firing rate patterns during voluntary muscle force generation: a simulation study

NASA Astrophysics Data System (ADS)

Hu, Xiaogang; Rymer, William Z.; Suresh, Nina L.

2014-04-01

Objective. Muscle force is generated by a combination of motor unit (MU) recruitment and changes in the discharge rate of active MUs. There have been two basic MU recruitment and firing rate paradigms reported in the literature, which describe the control of the MUs during force generation. The first (termed the reverse ‘onion skin’ profile), exhibits lower firing rates for lower threshold units, with higher firing rates occurring in higher threshold units. The second (termed the ‘onion skin’ profile), exhibits an inverse arrangement, with lower threshold units reaching higher firing rates. Approach. Using a simulation of the MU activity in a hand muscle, this study examined the force generation capacity and the variability of the muscle force magnitude at different excitation levels of the MU pool under these two different MU control paradigms. We sought to determine which rate/recruitment scheme was more efficient for force generation, and which scheme gave rise to the lowest force variability. Main results. We found that the force output of both firing patterns leads to graded force output at low excitation levels, and that the force generation capacity of the two different paradigms diverged around 50% excitation. In the reverse ‘onion skin’ pattern, at 100% excitation, the force output reached up to 88% of maximum force, whereas for the ‘onion skin’ pattern, the force output only reached up to 54% of maximum force at 100% excitation. The force variability was lower at the low to moderate force levels under the ‘onion skin’ paradigm than with the reverse ‘onion skin’ firing patterns, but this effect was reversed at high force levels. Significance. This study captures the influence of MU recruitment and firing rate organization on muscle force properties, and our results suggest that the different firing organizations can be beneficial at different levels of voluntary muscle force generation and perhaps for different tasks.

Flexible-rate optical packet generation/detection and label swapping for optical label switching networks

NASA Astrophysics Data System (ADS)

Wu, Zhongying; Li, Juhao; Tian, Yu; Ge, Dawei; Zhu, Paikun; Chen, Yuanxiang; Chen, Zhangyuan; He, Yongqi

2017-03-01

In recent years, optical label switching (OLS) gains lots of attentions due to its intrinsic advantages to implement protocol, bit-rate, granularity and data format transparency packet switching. In this paper, we propose a novel scheme to realize flexible-rate optical packet switching for OLS networks. At the transmitter node, flexible-rate packet is generated by parallel modulating different combinations of optical carriers generated from the optical multi-carrier generator (OMCG), among which the low-speed optical label occupies one carrier. At the switching node, label is extracted and re-generated in label processing unit (LPU). The payloads are switched based on routing information and new label is added after switching. At the receiver node, another OMCG serves as local oscillators (LOs) for optical payloads coherent detection. The proposed scheme offers good flexibility for dynamic optical packet switching by adjusting the payload bandwidth and could also effectively reduce the number of lasers, modulators and receivers for packet generation/detection. We present proof-of-concept demonstrations of flexible-rate packet generation/detection and label swapping in 12.5 GHz grid. The influence of crosstalk for cascaded label swapping is also investigated.

The cosmic microwave background radiation power spectrum as a random bit generator for symmetric- and asymmetric-key cryptography.

PubMed

Lee, Jeffrey S; Cleaver, Gerald B

2017-10-01

In this note, the Cosmic Microwave Background (CMB) Radiation is shown to be capable of functioning as a Random Bit Generator, and constitutes an effectively infinite supply of truly random one-time pad values of arbitrary length. It is further argued that the CMB power spectrum potentially conforms to the FIPS 140-2 standard. Additionally, its applicability to the generation of a (n × n) random key matrix for a Vernam cipher is established.

Unconditional security of time-energy entanglement quantum key distribution using dual-basis interferometry.

PubMed

Zhang, Zheshen; Mower, Jacob; Englund, Dirk; Wong, Franco N C; Shapiro, Jeffrey H

2014-03-28

High-dimensional quantum key distribution (HDQKD) offers the possibility of high secure-key rate with high photon-information efficiency. We consider HDQKD based on the time-energy entanglement produced by spontaneous parametric down-conversion and show that it is secure against collective attacks. Its security rests upon visibility data-obtained from Franson and conjugate-Franson interferometers-that probe photon-pair frequency correlations and arrival-time correlations. From these measurements, an upper bound can be established on the eavesdropper's Holevo information by translating the Gaussian-state security analysis for continuous-variable quantum key distribution so that it applies to our protocol. We show that visibility data from just the Franson interferometer provides a weaker, but nonetheless useful, secure-key rate lower bound. To handle multiple-pair emissions, we incorporate the decoy-state approach into our protocol. Our results show that over a 200-km transmission distance in optical fiber, time-energy entanglement HDQKD could permit a 700-bit/sec secure-key rate and a photon information efficiency of 2 secure-key bits per photon coincidence in the key-generation phase using receivers with a 15% system efficiency.

The Generation Rate of Respirable Dust from Cutting Fiber Cement Siding Using Different Tools

PubMed Central

Qi, Chaolong; Echt, Alan; Gressel, Michael G

2017-01-01

This article describes the evaluation of the generation rate of respirable dust (GAPS, defined as the mass of respirable dust generated per unit linear length cut) from cutting fiber cement siding using different tools in a laboratory testing system. We used an aerodynamic particle sizer spectrometer (APS) to continuously monitor the real-time size distributions of the dust throughout cutting tests when using a variety of tools, and calculated the generation rate of respirable dust for each testing condition using the size distribution data. The test result verifies that power shears provided an almost dust-free operation with a GAPS of 0.006 gram meter−1 (g m−1) at the testing condition. For the same power saws, the cuts using saw blades with more teeth generated more respirable dusts. Using the same blade for all four miter saws tested in this study, a positive linear correlation was found between the saws’ blade rotating speed and its dust generation rate. In addition, a circular saw running at the highest blade rotating speed of 9068 RPM generated the greatest amount of dust. All the miter saws generated less dust in the ‘chopping mode’ than in the ‘chopping and sliding’ mode. For the tested saws, GAPS consistently decreased with the increases of the saw cutting feed rate and the number of board in the stack. All the test results point out that fewer cutting interactions between the saw blade’s teeth and the siding board for a unit linear length of cut tend to result in a lower generation rate of respirable dust. These results may help guide optimal operation in practice and future tool development aimed at minimizing dust generation while producing a satisfactory cut. PMID:28395343

The Generation Rate of Respirable Dust from Cutting Fiber Cement Siding Using Different Tools.

PubMed

Qi, Chaolong; Echt, Alan; Gressel, Michael G

2017-03-01

This article describes the evaluation of the generation rate of respirable dust (GAPS, defined as the mass of respirable dust generated per unit linear length cut) from cutting fiber cement siding using different tools in a laboratory testing system. We used an aerodynamic particle sizer spectrometer (APS) to continuously monitor the real-time size distributions of the dust throughout cutting tests when using a variety of tools, and calculated the generation rate of respirable dust for each testing condition using the size distribution data. The test result verifies that power shears provided an almost dust-free operation with a GAPS of 0.006 g m-1 at the testing condition. For the same power saws, the cuts using saw blades with more teeth generated more respirable dusts. Using the same blade for all four miter saws tested in this study, a positive linear correlation was found between the saws' blade rotating speed and its dust generation rate. In addition, a circular saw running at the highest blade rotating speed of 9068 rpm generated the greatest amount of dust. All the miter saws generated less dust in the 'chopping mode' than in the 'chopping and sliding' mode. For the tested saws, GAPS consistently decreased with the increases of the saw cutting feed rate and the number of board in the stack. All the test results point out that fewer cutting interactions between the saw blade's teeth and the siding board for a unit linear length of cut tend to result in a lower generation rate of respirable dust. These results may help guide optimal operation in practice and future tool development aimed at minimizing dust generation while producing a satisfactory cut. Published by Oxford University Press on behalf of The British Occupational Hygiene Society 2017.

FPGA based digital phase-coding quantum key distribution system

NASA Astrophysics Data System (ADS)

Lu, XiaoMing; Zhang, LiJun; Wang, YongGang; Chen, Wei; Huang, DaJun; Li, Deng; Wang, Shuang; He, DeYong; Yin, ZhenQiang; Zhou, Yu; Hui, Cong; Han, ZhengFu

2015-12-01

Quantum key distribution (QKD) is a technology with the potential capability to achieve information-theoretic security. Phasecoding is an important approach to develop practical QKD systems in fiber channel. In order to improve the phase-coding modulation rate, we proposed a new digital-modulation method in this paper and constructed a compact and robust prototype of QKD system using currently available components in our lab to demonstrate the effectiveness of the method. The system was deployed in laboratory environment over a 50 km fiber and continuously operated during 87 h without manual interaction. The quantum bit error rate (QBER) of the system was stable with an average value of 3.22% and the secure key generation rate is 8.91 kbps. Although the modulation rate of the photon in the demo system was only 200 MHz, which was limited by the Faraday-Michelson interferometer (FMI) structure, the proposed method and the field programmable gate array (FPGA) based electronics scheme have a great potential for high speed QKD systems with Giga-bits/second modulation rate.

No-signaling quantum key distribution: solution by linear programming

NASA Astrophysics Data System (ADS)

Hwang, Won-Young; Bae, Joonwoo; Killoran, Nathan

2015-02-01

We outline a straightforward approach for obtaining a secret key rate using only no-signaling constraints and linear programming. Assuming an individual attack, we consider all possible joint probabilities. Initially, we study only the case where Eve has binary outcomes, and we impose constraints due to the no-signaling principle and given measurement outcomes. Within the remaining space of joint probabilities, by using linear programming, we get bound on the probability of Eve correctly guessing Bob's bit. We then make use of an inequality that relates this guessing probability to the mutual information between Bob and a more general Eve, who is not binary-restricted. Putting our computed bound together with the Csiszár-Körner formula, we obtain a positive key generation rate. The optimal value of this rate agrees with known results, but was calculated in a more straightforward way, offering the potential of generalization to different scenarios.

Secure detection in quantum key distribution by real-time calibration of receiver

NASA Astrophysics Data System (ADS)

Marøy, Øystein; Makarov, Vadim; Skaar, Johannes

2017-12-01

The single-photon detectionefficiency of the detector unit is crucial for the security of common quantum key distribution protocols like Bennett-Brassard 1984 (BB84). A low value for the efficiency indicates a possible eavesdropping attack that exploits the photon receiver’s imperfections. We present a method for estimating the detection efficiency, and calculate the corresponding secure key generation rate. The estimation is done by testing gated detectors using a randomly activated photon source inside the receiver unit. This estimate gives a secure rate for any detector with non-unity single-photon detection efficiency, both inherit or due to blinding. By adding extra optical components to the receiver, we make sure that the key is extracted from photon states for which our estimate is valid. The result is a quantum key distribution scheme that is secure against any attack that exploits detector imperfections.

Security of six-state quantum key distribution protocol with threshold detectors

PubMed Central

Kato, Go; Tamaki, Kiyoshi

2016-01-01

The security of quantum key distribution (QKD) is established by a security proof, and the security proof puts some assumptions on the devices consisting of a QKD system. Among such assumptions, security proofs of the six-state protocol assume the use of photon number resolving (PNR) detector, and as a result the bit error rate threshold for secure key generation for the six-state protocol is higher than that for the BB84 protocol. Unfortunately, however, this type of detector is demanding in terms of technological level compared to the standard threshold detector, and removing the necessity of such a detector enhances the feasibility of the implementation of the six-state protocol. Here, we develop the security proof for the six-state protocol and show that we can use the threshold detector for the six-state protocol. Importantly, the bit error rate threshold for the key generation for the six-state protocol (12.611%) remains almost the same as the one (12.619%) that is derived from the existing security proofs assuming the use of PNR detectors. This clearly demonstrates feasibility of the six-state protocol with practical devices. PMID:27443610

Round-robin differential-phase-shift quantum key distribution with a passive decoy state method

PubMed Central

Liu, Li; Guo, Fen-Zhuo; Qin, Su-Juan; Wen, Qiao-Yan

2017-01-01

Recently, a new type of protocol named Round-robin differential-phase-shift quantum key distribution (RRDPS QKD) was proposed, where the security can be guaranteed without monitoring conventional signal disturbances. The active decoy state method can be used in this protocol to overcome the imperfections of the source. But, it may lead to side channel attacks and break the security of QKD systems. In this paper, we apply the passive decoy state method to the RRDPS QKD protocol. Not only can the more environment disturbance be tolerated, but in addition it can overcome side channel attacks on the sources. Importantly, we derive a new key generation rate formula for our RRDPS protocol using passive decoy states and enhance the key generation rate. We also compare the performance of our RRDPS QKD to that using the active decoy state method and the original RRDPS QKD without any decoy states. From numerical simulations, the performance improvement of the RRDPS QKD by our new method can be seen. PMID:28198808

WTP Waste Feed Qualification: Hydrogen Generation Rate Measurement Apparatus Testing Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stone, M. E.; Newell, J. D.; Smith, T. E.

The generation rate of hydrogen gas in the Hanford tank waste will be measured during the qualification of the staged tank waste for processing in the Hanford Tank Waste Treatment and Immobilization Plant. Based on a review of past practices in measurement of the hydrogen generation, an apparatus to perform this measurement has been designed and tested for use during waste feed qualification. The hydrogen generation rate measurement apparatus (HGRMA) described in this document utilized a 100 milliliter sample in a continuously-purged, continuously-stirred vessel, with measurement of hydrogen concentration in the vent gas. The vessel and lid had a combinedmore » 220 milliliters of headspace. The vent gas system included a small condenser to prevent excessive evaporative losses from the sample during the test, as well as a demister and filter to prevent particle migration from the sample to the gas chromatography system. The gas chromatograph was an on line automated instrument with a large-volume sample-injection system to allow measurement of very low hydrogen concentrations. This instrument automatically sampled the vent gas from the hydrogen generation rate measurement apparatus every five minutes and performed data regression in real time. The fabrication of the hydrogen generation rate measurement apparatus was in accordance with twenty three (23) design requirements documented in the conceptual design package, as well as seven (7) required developmental activities documented in the task plan associated with this work scope. The HGRMA was initially tested for proof of concept with physical simulants, and a remote demonstration of the system was performed in the Savannah River National Laboratory Shielded Cells Mockup Facility. Final verification testing was performed using non-radioactive simulants of the Hanford tank waste. Three different simulants were tested to bound the expected rheological properties expected during waste feed qualification testing

Distillation of secret-key from a class of compound memoryless quantum sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boche, H., E-mail: boche@tum.de; Janßen, G., E-mail: gisbert.janssen@tum.de

We consider secret-key distillation from tripartite compound classical-quantum-quantum (cqq) sources with free forward public communication under strong security criterion. We design protocols which are universally reliable and secure in this scenario. These are shown to achieve asymptotically optimal rates as long as a certain regularity condition is fulfilled by the set of its generating density matrices. We derive a multi-letter formula which describes the optimal forward secret-key capacity for all compound cqq sources being regular in this sense. We also determine the forward secret-key distillation capacity for situations where the legitimate sending party has perfect knowledge of his/her marginal statemore » deriving from the source statistics. In this case regularity conditions can be dropped. Our results show that the capacities with and without the mentioned kind of state knowledge are equal as long as the source is generated by a regular set of density matrices. We demonstrate that regularity of cqq sources is not only a technical but also an operational issue. For this reason, we give an example of a source which has zero secret-key distillation capacity without sender knowledge, while achieving positive rates is possible if sender marginal knowledge is provided.« less

Working memory dynamics bias the generation of beliefs: the influence of data presentation rate on hypothesis generation.

PubMed

Lange, Nicholas D; Thomas, Rick P; Buttaccio, Daniel R; Illingworth, David A; Davelaar, Eddy J

2013-02-01

Although temporal dynamics are inherent aspects of diagnostic tasks, few studies have investigated how various aspects of time course influence hypothesis generation. An experiment is reported that demonstrates that working memory dynamics operating during serial data acquisition bias hypothesis generation. The presentation rate (and order) of a sequence of serially presented symptoms was manipulated to be either fast (180 ms per symptom) or slow (1,500 ms per symptom) in a simulated medical diagnosis task. When the presentation rate was slow, participants chose the disease hypothesis consistent with the symptoms appearing later in the sequence. When the presentation rate was fast, however, participants chose the disease hypothesis consistent with the symptoms appearing earlier in the sequence, therefore representing a novel primacy effect. We predicted and account for this effect through competitive working memory dynamics governing information acquisition and the contribution of maintained information to the retrieval of hypotheses from long-term memory.

Latest generation, wide-angle, high-definition colonoscopes increase adenoma detection rate.

PubMed

Adler, Andreas; Aminalai, Alireza; Aschenbeck, Jens; Drossel, Rolf; Mayr, Michael; Scheel, Mathias; Schröder, Andreas; Yenerim, Timur; Wiedenmann, Bertram; Gauger, Ulrich; Roll, Stephanie; Rösch, Thomas

2012-02-01

Improvements to endoscopy imaging technologies might improve detection rates of colorectal cancer and patient outcomes. We compared the accuracy of the latest generation of endoscopes with older generation models in detection of colorectal adenomas. We compared data from 2 prospective screening colonoscopy studies (the Berlin Colonoscopy Project 6); each study lasted approximately 6 months and included the same 6 colonoscopists, who worked in private practice. Participants in group 1 (n = 1256) were all examined by using the latest generation of wide-angle, high-definition colonoscopes that were manufactured by the same company. Individuals in group 2 (n = 1400) were examined by endoscopists who used routine equipment (a mixture of endoscopes from different companies; none of those used to examine group 1). The adenoma detection rate was calculated on the basis of the number of all adenomas/number of all patients. There were no differences in patient parameters or withdrawal time between groups (8.0 vs 8.2 minutes). The adenoma detection rate was significantly higher in group 1 (0.33) than in group 2 (0.27; P = .01); a greater number of patients with least 1 adenoma were identified in group 1 (22.1%) than in group 2 (18.2%; P = .01). A higher percentage of high-grade dysplastic adenomas were detected in group 1 (1.19%) than in group 2 (0.57%), but this difference was not statistically significant (P = .06). The latest generation of wide-angle, high-definition colonoscopes improves rates of adenoma detection by 22%, compared with mixed, older technology endoscopes used in routine private practice. These findings might affect definitions of quality control parameters for colonoscopy screening for colorectal cancer. Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.

Results and evaluation of key comparison CCM.P-K12.1 for very low helium flow rates (leak rates)

NASA Astrophysics Data System (ADS)

Šetina, Janez; Vičar, Martin; Pražák, Dominik

2015-01-01

The Czech Metrology Institute (CMI) took part and failed to prove equivalence in the Key Comparison CCM.P-K12 of helium leak artefacts (leak rates) into vacuum. After identifying and eliminating the cause of the failure, the Institute of Metals and Technology (IMT) of Slovenia, a successful participant in CCM.P-K12, volunteered to serve as pilot and link in a following bilateral comparison of IMT and CMI that obtained designation CCM.P-K12.1 in June 2012. It was decided to perform the comparison with a glass permeation helium leak artefact at nominally 3.10-11 mol/s (7.4.10-7 mbar.L.s-1) at 23 °C. Both the laboratory standards took part in CCM.P-K12 and were considered as primary. The comparison measurements were performed in October 2012. CMI proved equivalence both with IMT and with the reference value of the key comparison CCM.P-K12. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Intake of key chronic disease-related nutrients among baby boomers.

PubMed

King, Dana E; Xiang, Jun; Brown, Alexander

2014-06-01

The dietary habits of baby boomers (people born between 1946 and 1964) undoubtedly will have a substantial impact on their future health; however, dietary information regarding the intake of key chronic disease-related nutrients is lacking for this generation. The objective of this study was to compare the dietary intake of key chronic disease-related nutrients of the baby boomer generation with the previous generation of middle-aged adults. National cross-sectional study comparison analyzing data from the National Health and Nutrition Examination Survey (NHANES) including NHANES III (1988-1994) and the NHANES for 2007-2010, focused on adult respondents ages 46 to 64 years who were not institutionalized at the time of each survey. The two cohorts were compared with regard to dietary intake of key nutritional components. The main outcome measures were intake of total calories, sodium, cholesterol, fat, fruits, vegetables, vitamin C, water, and fiber. The baby boomers' average daily intake of nutrients exceeded that of the previous generation of middle-aged adults for total calories (2118/1999), total fat (82/76 g), sodium (3513/3291 mg), and cholesterol (294/262 g; all P < 0.001). The intake of vitamin C (105/89 g), water (1208/1001 g), and vegetables (199/229 g) was less than that of the previous generation (P < 0.001), and the dietary intake of fruit and fiber was unchanged. In regression analyses, dietary changes remained significant after controlling for age, race, sex, and socioeconomic status (all P < 0.01). The study findings document higher dietary intake of key chronic disease-related nutrients along with reduced vegetable intake among baby boomers compared with the previous generation of middle-aged adults. These findings are indicative of a diet that may contribute to increased rates of chronic disease among individuals in this age group.

Intake of Key Chronic Disease–Related Nutrients among Baby Boomers

PubMed Central

King, Dana E.; Xiang, Jun; Brown, Alexander

2014-01-01

Objectives The dietary habits of baby boomers (people born between 1946 and 1964) undoubtedly will have a substantial impact on their future health; however, dietary information regarding the intake of key chronic disease–related nutrients is lacking for this generation. The objective of this study was to compare the dietary intake of key chronic disease–related nutrients of the baby boomer generation with the previous generation of middle-aged adults. Methods National cross-sectional study comparison analyzing data from the National Health and Nutrition Examination Survey (NHANES) including NHANES III (1988–1994) and the NHANES for 2007–2010, focused on adult respondents ages 46 to 64 years who were not institutionalized at the time of each survey. The two cohorts were compared with regard to dietary intake of key nutritional components. The main outcome measures were intake of total calories, sodium, cholesterol, fat, fruits, vegetables, vitamin C, water, and fiber. Results The baby boomers’ average daily intake of nutrients exceeded that of the previous generation of middle-aged adults for total calories (2118/1999), total fat (82/76 g), sodium (3513/3291 mg), and cholesterol (294/262 g; all P < 0.001). The intake of vitamin C (105/89 g), water (1208/1001 g), and vegetables (199/229 g) was less than that of the previous generation (P < 0.001), and the dietary intake of fruit and fiber was unchanged. In regression analyses, dietary changes remained significant after controlling for age, race, sex, and socioeconomic status (all P < 0.01). Conclusions The study findings document higher dietary intake of key chronic disease–related nutrients along with reduced vegetable intake among baby boomers compared with the previous generation of middle-aged adults. These findings are indicative of a diet that may contribute to increased rates of chronic disease among individuals in this age group. PMID:24945165

Trip generation rates, peaking characteristics, and vehicle mix characteristics of special West Virginia generators : executive summary.

DOT National Transportation Integrated Search

2000-02-01

For a number of land uses, published trip rates were not appropriate for application in West Virginia. There are a number of so-called special generators, which are either unique to West Virginia (i.e., regional jails) or have assumed increased impor...

Field demonstration of a continuous-variable quantum key distribution network.

PubMed

Huang, Duan; Huang, Peng; Li, Huasheng; Wang, Tao; Zhou, Yingming; Zeng, Guihua

2016-08-01

We report on what we believe is the first field implementation of a continuous-variable quantum key distribution (CV-QKD) network with point-to-point configuration. Four QKD nodes are deployed on standard communication infrastructures connected with commercial telecom optical fiber. Reliable key exchange is achieved in the wavelength-division-multiplexing CV-QKD network. The impact of a complex and volatile field environment on the excess noise is investigated, since excess noise controlling and reduction is arguably the major issue pertaining to distance and the secure key rate. We confirm the applicability and verify the maturity of the CV-QKD network in a metropolitan area, thus paving the way for a next-generation global secure communication network.

Fragment generation, survival, and attachment of Dictyota spp. at Conch Reef in the Florida Keys, USA

NASA Astrophysics Data System (ADS)

Herren, L. W.; Walters, L. J.; Beach, K. S.

2006-05-01

During the past decade, the relative abundance of the brown macroalgae Dictyota spp. has been high in the Florida Keys. Recent studies have shown that members of this genus successfully reproduce via vegetative fragmentation. To investigate the importance of fragmentation on the reef community, this study examined: (1) the degree of epiphytism on benthic organisms, (2) the rate of fragment production through fish foraging activities, (3) the likelihood of fragment entanglement, and (4) the fragment attachment and success rate. It was found that reef fish contributed substantially to the fragment pool; furthermore, most fish-produced fragments produced rhizoids and attached to sand grains within 24 h in the field. Fragments of Dictyota spp. most commonly became entangled around and then attached themselves to the green alga Halimeda tuna, and other Dictyota spp. These results suggest that vegetative fragmentation of Dictyota spp. plays an important role in the changing community structure on the Florida Keys reef tract.

An empirical model for prediction of household solid waste generation rate - A case study of Dhanbad, India.

PubMed

Kumar, Atul; Samadder, S R

2017-10-01

Accurate prediction of the quantity of household solid waste generation is very much essential for effective management of municipal solid waste (MSW). In actual practice, modelling methods are often found useful for precise prediction of MSW generation rate. In this study, two models have been proposed that established the relationships between the household solid waste generation rate and the socioeconomic parameters, such as household size, total family income, education, occupation and fuel used in the kitchen. Multiple linear regression technique was applied to develop the two models, one for the prediction of biodegradable MSW generation rate and the other for non-biodegradable MSW generation rate for individual households of the city Dhanbad, India. The results of the two models showed that the coefficient of determinations (R 2 ) were 0.782 for biodegradable waste generation rate and 0.676 for non-biodegradable waste generation rate using the selected independent variables. The accuracy tests of the developed models showed convincing results, as the predicted values were very close to the observed values. Validation of the developed models with a new set of data indicated a good fit for actual prediction purpose with predicted R 2 values of 0.76 and 0.64 for biodegradable and non-biodegradable MSW generation rate respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

System and method for determining an ammonia generation rate in a three-way catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Min; Perry, Kevin L; Kim, Chang H

A system according to the principles of the present disclosure includes a rate determination module, a storage level determination module, and an air/fuel ratio control module. The rate determination module determines an ammonia generation rate in a three-way catalyst based on a reaction efficiency and a reactant level. The storage level determination module determines an ammonia storage level in a selective catalytic reduction (SCR) catalyst positioned downstream from the three-way catalyst based on the ammonia generation rate. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the ammonia storage level.

76 FR 69720 - Northampton Generating Company, L.P.; Supplemental Notice That Initial Market-Based Rate Filing...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-09

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER12-281-000] Northampton Generating Company, L.P.; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... Northampton Generating Company, L.P.'s application for market-based rate authority, with an accompanying rate...

Geodesy - the key for constraining rates of magma supply, storage, and eruption

NASA Astrophysics Data System (ADS)

Poland, Michael; Anderson, Kyle

2016-04-01

Volcanology is an inherently interdisciplinary science that requires joint analysis of diverse physical and chemical datasets to infer subsurface processes from surface observations. Among the diversity of data that can be collected, however, geodetic data are critical for elucidating the main elements of a magmatic plumbing system because of their sensitivity to subsurface changes in volume and mass. In particular, geodesy plays a key role in determining rates of magma supply, storage, and eruption. For example, surface displacements are critical for estimating the volume changes and locations of subsurface magma storage zones, and remotely sensed radar data make it possible to place significant bounds on eruptive volumes. Combining these measurements with geochemical indicators of magma composition and volatile content enables modeling of magma fluxes throughout a volcano's plumbing system, from source to surface. We combined geodetic data (particularly InSAR) with prior geochemical constraints and measured gas emissions from Kīlauea Volcano, Hawai`i, to develop a probabilistic model that relates magma supply, storage, and eruption over time. We found that the magma supply rate to Kīlauea during 2006 was 35-100% greater than during 2000-2001, with coincident increased rates of subsurface magma storage and eruption at the surface. By 2012, this surge in supply had ended, and supply rates were below those of 2000-2001; magma storage and eruption rates were similarly reduced. These results demonstrate the connection between magma supply, storage, and eruption, and the overall importance of magma supply with respect to volcanic hazards at Kīlauea and similar volcanoes. Our model also confirms the importance of geodetic data in modeling these parameters - rates of storage and eruption are, in some cases, almost uniquely constrained by geodesy. Future modeling efforts along these lines should also seek to incorporate gravity data, to better determine magma

A new method for generating an invariant iris private key based on the fuzzy vault system.

PubMed

Lee, Youn Joo; Park, Kang Ryoung; Lee, Sung Joo; Bae, Kwanghyuk; Kim, Jaihie

2008-10-01

Cryptographic systems have been widely used in many information security applications. One main challenge that these systems have faced has been how to protect private keys from attackers. Recently, biometric cryptosystems have been introduced as a reliable way of concealing private keys by using biometric data. A fuzzy vault refers to a biometric cryptosystem that can be used to effectively protect private keys and to release them only when legitimate users enter their biometric data. In biometric systems, a critical problem is storing biometric templates in a database. However, fuzzy vault systems do not need to directly store these templates since they are combined with private keys by using cryptography. Previous fuzzy vault systems were designed by using fingerprint, face, and so on. However, there has been no attempt to implement a fuzzy vault system that used an iris. In biometric applications, it is widely known that an iris can discriminate between persons better than other biometric modalities. In this paper, we propose a reliable fuzzy vault system based on local iris features. We extracted multiple iris features from multiple local regions in a given iris image, and the exact values of the unordered set were then produced using the clustering method. To align the iris templates with the new input iris data, a shift-matching technique was applied. Experimental results showed that 128-bit private keys were securely and robustly generated by using any given iris data without requiring prealignment.

Trace chemical contaminant generation rates for spacecraft contamination control system design

NASA Technical Reports Server (NTRS)

Perry, J. L.

1995-01-01

A spacecraft presents a unique design challenge with respect to providing a comfortable environment in which people can live and work. All aspects of the spacecraft environmental design including the size of the habitable volume, its temperature, relative humidity, and composition must be considered to ensure the comfort and health of the occupants. The crew members and the materials selected for outfitting the spacecraft play an integral part in designing a habitable spacecraft because material offgassing and human metabolism are the primary sources for continuous trace chemical contaminant generation onboard a spacecraft. Since these contamination sources cannot be completely eliminated, active control processes must be designed and deployed onboard the spacecraft to ensure an acceptably clean cabin atmosphere. Knowledge of the expected rates at which contaminants are generated is very important to the design of these processes. Data from past spacecraft missions and human contaminant production studies have been analyzed to provide this knowledge. The resulting compilation of contaminants and generation rates serve as a firm basis for past, present, and future contamination control system designs for space and aeronautics applications.

Measurement-device-independent quantum key distribution for Scarani-Acin-Ribordy-Gisin 04 protocol

PubMed Central

Mizutani, Akihiro; Tamaki, Kiyoshi; Ikuta, Rikizo; Yamamoto, Takashi; Imoto, Nobuyuki

2014-01-01

The measurement-device-independent quantum key distribution (MDI QKD) was proposed to make BB84 completely free from any side-channel in detectors. Like in prepare & measure QKD, the use of other protocols in MDI setting would be advantageous in some practical situations. In this paper, we consider SARG04 protocol in MDI setting. The prepare & measure SARG04 is proven to be able to generate a key up to two-photon emission events. In MDI setting we show that the key generation is possible from the event with single or two-photon emission by a party and single-photon emission by the other party, but the two-photon emission event by both parties cannot contribute to the key generation. On the contrary to prepare & measure SARG04 protocol where the experimental setup is exactly the same as BB84, the measurement setup for SARG04 in MDI setting cannot be the same as that for BB84 since the measurement setup for BB84 in MDI setting induces too many bit errors. To overcome this problem, we propose two alternative experimental setups, and we simulate the resulting key rate. Our study highlights the requirements that MDI QKD poses on us regarding with the implementation of a variety of QKD protocols. PMID:24913431

Failure Pressure and Leak Rate of Steam Generator Tubes With Stress Corrosion Cracks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Majumdar, S.; Kasza, K.; Park, J.Y.

2002-07-01

This paper illustrates the use of an 'equivalent rectangular crack' approach to predict leak rates through laboratory generated stress corrosion cracks. A comparison between predicted and observed test data on rupture and leak rate from laboratory generated stress corrosion cracks are provided. Specimen flaws were sized by post-test fractography in addition to pre-test advanced eddy current technique. The test failure pressures and leak rates are shown to be closer to those predicted on the basis of fractography than on NDE. However, the predictions based on NDE results are encouraging, particularly because they have the potential to determine a more detailedmore » geometry of ligamentous cracks from which more accurate predictions of failure pressure and leak rate can be made in the future. (authors)« less

Estimation of construction and demolition waste using waste generation rates in Chennai, India.

PubMed

Ram, V G; Kalidindi, Satyanarayana N

2017-06-01

A large amount of construction and demolition waste is being generated owing to rapid urbanisation in Indian cities. A reliable estimate of construction and demolition waste generation is essential to create awareness about this stream of solid waste among the government bodies in India. However, the required data to estimate construction and demolition waste generation in India are unavailable or not explicitly documented. This study proposed an approach to estimate construction and demolition waste generation using waste generation rates and demonstrated it by estimating construction and demolition waste generation in Chennai city. The demolition waste generation rates of primary materials were determined through regression analysis using waste generation data from 45 case studies. Materials, such as wood, electrical wires, doors, windows and reinforcement steel, were found to be salvaged and sold on the secondary market. Concrete and masonry debris were dumped in either landfills or unauthorised places. The total quantity of construction and demolition debris generated in Chennai city in 2013 was estimated to be 1.14 million tonnes. The proportion of masonry debris was found to be 76% of the total quantity of demolition debris. Construction and demolition debris forms about 36% of the total solid waste generated in Chennai city. A gross underestimation of construction and demolition waste generation in some earlier studies in India has also been shown. The methodology proposed could be utilised by government bodies, policymakers and researchers to generate reliable estimates of construction and demolition waste in other developing countries facing similar challenges of limited data availability.

A novel edge based embedding in medical images based on unique key generated using sudoku puzzle design.

PubMed

Santhi, B; Dheeptha, B

2016-01-01

The field of telemedicine has gained immense momentum, owing to the need for transmitting patients' information securely. This paper puts forth a unique method for embedding data in medical images. It is based on edge based embedding and XOR coding. The algorithm proposes a novel key generation technique by utilizing the design of a sudoku puzzle to enhance the security of the transmitted message. The edge blocks of the cover image alone, are utilized to embed the payloads. The least significant bit of the pixel values are changed by XOR coding depending on the data to be embedded and the key generated. Hence the distortion in the stego image is minimized and the information is retrieved accurately. Data is embedded in the RGB planes of the cover image, thus increasing its embedding capacity. Several measures including peak signal noise ratio (PSNR), mean square error (MSE), universal image quality index (UIQI) and correlation coefficient (R) are the image quality measures that have been used to analyze the quality of the stego image. It is evident from the results that the proposed technique outperforms the former methodologies.

Integrated quantum key distribution sender unit for daily-life implementations

NASA Astrophysics Data System (ADS)

Mélen, Gwenaelle; Vogl, Tobias; Rau, Markus; Corrielli, Giacomo; Crespi, Andrea; Osellame, Roberto; Weinfurter, Harald

2016-03-01

Unlike currently implemented encryption schemes, Quantum Key Distribution provides a secure way of generating and distributing a key among two parties. Although a multitude of research platforms has been developed, the integration of QKD units within classical communication systems remains a tremendous challenge. The recently achieved maturity of integrated photonic technologies could be exploited to create miniature QKD add-ons that could extend the primary function of various existing systems such as mobile devices or optical stations. In this work we report on an integrated optics module enabling secure short-distance communication for, e.g., quantum access schemes. Using BB84-like protocols, Alice's mobile low-cost device can exchange secure key and information everywhere within a trusted node network. The new optics platform (35×20×8mm) compatible with current smartphone's technology generates NIR faint polarised laser pulses with 100MHz repetition rate. Fully automated beam tracking and live basis-alignment on Bob's side ensure user-friendly operation with a quantum link efficiency as high as 50% stable over a few seconds.

Double-dose, new-generation proton pump inhibitors do not improve Helicobacter pylori eradication rate.

PubMed

Choi, Hyo Sun; Park, Dong Il; Hwang, Sang Jun; Park, Jung Sik; Kim, Hong Joo; Cho, Yong Kyun; Sohn, Chong Il; Jeon, Woo Kyu; Kim, Byung Ik

2007-12-01

Up to present, omeprazole plus two antibiotics are used for Helicobacter pylori eradication therapy . Few studies have compared double-dose new-generation, proton pump inhibitors (PPI) with omeprazole. Therefore, we conducted a randomized, prospective study to evaluate differences in H. pylori eradication rates by PPI type. Between January 2006 and December 2006, 576 consecutive patients with proven H. pylori infection were enrolled prospectively. Four different PPIs [omeprazole 20 mg b.i.d. (old generation), or pantoprazole 40 mg b.i.d., rabeprazole 20 mg b.i.d., or esomeprazole 40 mg b.i.d. (new generation)] were added to clarithromycin (500 mg b.i.d.) and amoxicillin (1 g b.i.d.) for 1 week. By intention-to-treat analysis, no difference was found between the eradication rates of these four PPIs: 64.9% (omeprazole, n = 148), 69.3% (pantoprazole, n = 140), 69.3% (rabeprazole, n = 140), and 72.9% (esomoprazole, n = 148). When eradication rates were analyzed according to whether patients had an ulcer or not on a per-protocol basis, no difference was found between the eradication rates of the four PPIs. However, side-effects were more common in the esomeprazole-based triple therapy group than in the other groups (p < .05). No convincing evidence was obtained that double-dose new-generation PPIs have better H. pylori eradication rates and tolerability than omeprazole.

Deprivation index and dependency ratio are key determinants of emergency medical admission rates.

PubMed

Conway, Richard; Byrne, Declan; O'Riordan, Deirdre; Cournane, Seán; Coveney, Seamus; Silke, Bernard

2015-11-01

Patients from deprived backgrounds have a higher in-patient mortality following an emergency medical admission; there has been debate as to the extent to which deprivation and population structure influences hospital admission rate. All emergency medical admissions to an Irish hospital over a 12-year period (2002-2013) categorized by quintile of Deprivation Index and Dependency Ratio (proportion of population <15 or ≥ 65 years) from small area population statistics (SAPS), were evaluated against hospital admission rates. Univariate and multivariable risk estimates (Odds Ratios (OR) or Incidence Rate Ratios (IRR)) were calculated, using logistic or zero truncated Poisson regression as appropriate. 66,861 admissions in 36,214 patients occured during the study period. The Deprivation Index quintile independently predicted the admission rate/1000 population, Q1 9.4 (95%CI 9.2 to 9.7), Q2 16.8 (95%CI 16.6 to 17.0), Q3 33.8 (95%CI 33.5 to 34.1), Q4 29.6 (95%CI 29.3 to 29.8) and Q5 45.4 (95%CI 44.5 to 46.2). Similarly the population Dependency Ratio was an independent predictor of the admission rate with adjusted predicted rates of Q1 20.8 (95%CI 20.5 to 21.1), Q2 19.2 (95%CI 19.0 to 19.4), Q3 27.6 (95%CI 27.3 to 27.9), Q4 43.9 (95%CI 43.5 to 44.4) and Q5 34.4 (95%CI 34.1 to 34.7). A high concurrent Deprivation Index and Dependency Ratio were associated with very high admission rates. Deprivation Index and population Dependency Ratio are key determinants of the rate of emergency medical admissions. Copyright © 2015 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

Quantum dense key distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Degiovanni, I.P.; Ruo Berchera, I.; Castelletto, S.

2004-03-01

This paper proposes a protocol for quantum dense key distribution. This protocol embeds the benefits of a quantum dense coding and a quantum key distribution and is able to generate shared secret keys four times more efficiently than the Bennet-Brassard 1984 protocol. We hereinafter prove the security of this scheme against individual eavesdropping attacks, and we present preliminary experimental results, showing its feasibility.

Do First Generation Immigrant Adolescents Face Higher Rates of Bullying, Violence and Suicidal Behaviours Than Do Third Generation and Native Born?

PubMed

Pottie, Kevin; Dahal, Govinda; Georgiades, Katholiki; Premji, Kamila; Hassan, Ghayda

2015-10-01

We conducted a systematic review to examine first generation immigrant adolescents' likelihood of experiencing bullying, violence, and suicidal behaviours compared to their later-generation and native born counterparts, and to identify factors that may underlie these risks. Eighteen studies met full inclusion criteria. First generation immigrant adolescents experience higher rate of bullying and peer aggression compared to third generation and native counterparts. Refugee status and advanced parental age were associated with increased parent to child aggression among South East Asians. Family cohesion was associated with lower rates of violence. Suicidal ideation was lower across most immigrant adolescents' ethnicities, with the exception of Turkish and South Asian Surinamese female adolescents in the Netherlands. Bullying and peer aggression of immigrant children and adolescents and potential mitigating factors such as family cohesion warrant research and program attention by policymakers, teachers and parents.

High-speed polarization-encoded quantum key distribution based on silicon photonic integrated devices

NASA Astrophysics Data System (ADS)

Bunandar, Darius; Urayama, Junji; Boynton, Nicholas; Martinez, Nicholas; Derose, Christopher; Lentine, Anthony; Davids, Paul; Camacho, Ryan; Wong, Franco; Englund, Dirk

We present a compact polarization-encoded quantum key distribution (QKD) transmitter near a 1550-nm wavelength implemented on a CMOS-compatible silicon-on-insulator photonics platform. The transmitter generates arbitrary polarization qubits at gigahertz bandwidth with an extinction ratio better than 30 dB using high-speed carrier-depletion phase modulators. We demonstrate the performance of this device by generating secret keys at a rate of 1 Mbps in a complete QKD field test. Our work shows the potential of using advanced photonic integrated circuits to enable high-speed quantum-secure communications. This work was supported by the SECANT QKD Grand Challenge, the Samsung Global Research Outreach Program, and the Air Force Office of Scientific Research.

Parameter Estimation with Almost No Public Communication for Continuous-Variable Quantum Key Distribution

NASA Astrophysics Data System (ADS)

Lupo, Cosmo; Ottaviani, Carlo; Papanastasiou, Panagiotis; Pirandola, Stefano

2018-06-01

One crucial step in any quantum key distribution (QKD) scheme is parameter estimation. In a typical QKD protocol the users have to sacrifice part of their raw data to estimate the parameters of the communication channel as, for example, the error rate. This introduces a trade-off between the secret key rate and the accuracy of parameter estimation in the finite-size regime. Here we show that continuous-variable QKD is not subject to this constraint as the whole raw keys can be used for both parameter estimation and secret key generation, without compromising the security. First, we show that this property holds for measurement-device-independent (MDI) protocols, as a consequence of the fact that in a MDI protocol the correlations between Alice and Bob are postselected by the measurement performed by an untrusted relay. This result is then extended beyond the MDI framework by exploiting the fact that MDI protocols can simulate device-dependent one-way QKD with arbitrarily high precision.

Miniaturized video-rate epi-third-harmonic-generation fiber-microscope.

PubMed

Chia, Shih-Hsuan; Yu, Che-Hang; Lin, Chih-Han; Cheng, Nai-Chia; Liu, Tzu-Ming; Chan, Ming-Che; Chen, I-Hsiu; Sun, Chi-Kuang

2010-08-02

With a micro-electro-mechanical system (MEMS) mirror, we successfully developed a miniaturized epi-third-harmonic-generation (epi-THG) fiber-microscope with a video frame rate (31 Hz), which was designed for in vivo optical biopsy of human skin. With a large-mode-area (LMA) photonic crystal fiber (PCF) and a regular microscopic objective, the nonlinear distortion of the ultrafast pulses delivery could be much reduced while still achieving a 0.4 microm lateral resolution for epi-THG signals. In vivo real time virtual biopsy of the Asian skin with a video rate (31 Hz) and a sub-micron resolution was obtained. The result indicates that this miniaturized system was compact enough for the least invasive hand-held clinical use.

Hepatitis B birth dose vaccination rates among children in Beijing: A comparison of local residents and first and second generation migrants

PubMed Central

Chen, Ruohan; Li, Youwei; Wangen, Knut Reidar; Nicholas, Stephen; Maitland, Elizabeth; Wang, Jian

2016-01-01

ABSTRACT Providing hepatitis B vaccine to all neonates within 24 hours of birth (Timely Birth Dose, TBD) is the key preventative measure to control perinatal hepatitis B virus infection. Previous Chinese studies of TBD only differentiated between migrant and non-migrant (local-born generation-LG) children. Our study is the first to stratify migrants in Beijing into first generation migrants (FGM) and second generation migrants (SGM). Based on a questionnaire survey of 2682 people in 3 Beijing villages, we identified 283 children aged 0–15 years, from 246 households, who were eligible for a TBD. Multinomial logistic regression and statistical analyses were used to examine factors explaining TBD rates for LG, FGM and SGM children. Surprisingly, the TBD for LG Beijing children was not significantly different from migrant children. But after stratifying migrant children into FGM and SGM, revealed significant TBD differences were revealed across LG, FGM and SGM according to domicile (p-value < 0.001, OR = 3.24), first vaccination covered by government policy (p-value < 0.05, OR = 3.24), mother's knowledge of hepatitis B (p-value < 0.05, OR = 1.01) and the government's HBV policy environment (p-value < 0.05, OR = 2.338). Birthplace (p-value = 0.002, OR = 6.21) and better policy environments (p-value = 0.01, OR = 2.80) were associated with higher TBD rate for LG and SGM children. Compared with FGM children, SGM had a significantly poorer TBD rate (Fisher exact test of chi-square = 0.013). We identified SGM as a special risk group; proposed Hukou reform to improve SGM TBD; and called for Beijing health authorities to match TBD rates in other provinces, especially by improving practices by health authorities and knowledge of parents. PMID:27043864

Hepatitis B birth dose vaccination rates among children in Beijing: A comparison of local residents and first and second generation migrants.

PubMed

Chen, Ruohan; Li, Youwei; Wangen, Knut Reidar; Nicholas, Stephen; Maitland, Elizabeth; Wang, Jian

2016-05-03

Providing hepatitis B vaccine to all neonates within 24 hours of birth (Timely Birth Dose, TBD) is the key preventative measure to control perinatal hepatitis B virus infection. Previous Chinese studies of TBD only differentiated between migrant and non-migrant (local-born generation-LG) children. Our study is the first to stratify migrants in Beijing into first generation migrants (FGM) and second generation migrants (SGM). Based on a questionnaire survey of 2682 people in 3 Beijing villages, we identified 283 children aged 0-15 years, from 246 households, who were eligible for a TBD. Multinomial logistic regression and statistical analyses were used to examine factors explaining TBD rates for LG, FGM and SGM children. Surprisingly, the TBD for LG Beijing children was not significantly different from migrant children. But after stratifying migrant children into FGM and SGM, revealed significant TBD differences were revealed across LG, FGM and SGM according to domicile (p-value < 0.001, OR = 3.24), first vaccination covered by government policy (p-value < 0.05, OR = 3.24), mother's knowledge of hepatitis B (p-value < 0.05, OR = 1.01) and the government's HBV policy environment (p-value < 0.05, OR = 2.338). Birthplace (p-value = 0.002, OR = 6.21) and better policy environments (p-value = 0.01, OR = 2.80) were associated with higher TBD rate for LG and SGM children. Compared with FGM children, SGM had a significantly poorer TBD rate (Fisher exact test of chi-square = 0.013). We identified SGM as a special risk group; proposed Hukou reform to improve SGM TBD; and called for Beijing health authorities to match TBD rates in other provinces, especially by improving practices by health authorities and knowledge of parents.

Isothermal calorimeter for measurements of time-dependent heat generation rate in individual supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Munteshari, Obaidallah; Lau, Jonathan; Krishnan, Atindra; Dunn, Bruce; Pilon, Laurent

2018-01-01

Heat generation in electric double layer capacitors (EDLCs) may lead to temperature rise and reduce their lifetime and performance. This study aims to measure the time-dependent heat generation rate in individual carbon electrode of EDLCs under various charging conditions. First, the design, fabrication, and validation of an isothermal calorimeter are presented. The calorimeter consisted of two thermoelectric heat flux sensors connected to a data acquisition system, two identical and cold plates fed with a circulating coolant, and an electrochemical test section connected to a potentiostat/galvanostat system. The EDLC cells consisted of two identical activated carbon electrodes and a separator immersed in an electrolyte. Measurements were performed on three cells with different electrolytes under galvanostatic cycling for different current density and polarity. The measured time-averaged irreversible heat generation rate was in excellent agreement with predictions for Joule heating. The reversible heat generation rate in the positive electrode was exothermic during charging and endothermic during discharging. By contrast, the negative electrode featured both exothermic and endothermic heat generation during both charging and discharging. The results of this study can be used to validate existing thermal models, to develop thermal management strategies, and to gain insight into physicochemical phenomena taking place during operation.

77 FR 20817 - Diamond State Generation Partners, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-06

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER12-1383-000] Diamond State Generation Partners, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... Diamond State Generation Partners, LLC's application for market-based rate authority, with an accompanying...

Quantum key distribution with prepare-and-measure Bell test

PubMed Central

Tan, Yong-gang

2016-01-01

The prepare-and-measure quantum key distribution (QKD) has the merits of fast speed, high key generation rate, and easy implementation. However, the detector side channel attacks greatly undermine the security of the key bits. The eavesdropper, Eve, exploits the flaws of the detectors to obtain illegal information without violating quantum principles. It means that she can intervene in the communication without being detected. A prepare-and-measure Bell test protocol will be proposed. By randomly carrying out Bell test at the side of the information receiver, Bob, Eve’s illegal information gain within the detector side channel attack can be well bounded. This protocol does not require any improvement on the detectors used in available prepare-and-measure QKD. Though we only illustrate its application in the BB84 protocol, it is applicable for any prepare-and-measure QKD. PMID:27733771

Nonlinear detection for a high rate extended binary phase shift keying system.

PubMed

Chen, Xian-Qing; Wu, Le-Nan

2013-03-28

The algorithm and the results of a nonlinear detector using a machine learning technique called support vector machine (SVM) on an efficient modulation system with high data rate and low energy consumption is presented in this paper. Simulation results showed that the performance achieved by the SVM detector is comparable to that of a conventional threshold decision (TD) detector. The two detectors detect the received signals together with the special impacting filter (SIF) that can improve the energy utilization efficiency. However, unlike the TD detector, the SVM detector concentrates not only on reducing the BER of the detector, but also on providing accurate posterior probability estimates (PPEs), which can be used as soft-inputs of the LDPC decoder. The complexity of this detector is considered in this paper by using four features and simplifying the decision function. In addition, a bandwidth efficient transmission is analyzed with both SVM and TD detector. The SVM detector is more robust to sampling rate than TD detector. We find that the SVM is suitable for extended binary phase shift keying (EBPSK) signal detection and can provide accurate posterior probability for LDPC decoding.

Nonlinear Detection for a High Rate Extended Binary Phase Shift Keying System

PubMed Central

Chen, Xian-Qing; Wu, Le-Nan

2013-01-01

The algorithm and the results of a nonlinear detector using a machine learning technique called support vector machine (SVM) on an efficient modulation system with high data rate and low energy consumption is presented in this paper. Simulation results showed that the performance achieved by the SVM detector is comparable to that of a conventional threshold decision (TD) detector. The two detectors detect the received signals together with the special impacting filter (SIF) that can improve the energy utilization efficiency. However, unlike the TD detector, the SVM detector concentrates not only on reducing the BER of the detector, but also on providing accurate posterior probability estimates (PPEs), which can be used as soft-inputs of the LDPC decoder. The complexity of this detector is considered in this paper by using four features and simplifying the decision function. In addition, a bandwidth efficient transmission is analyzed with both SVM and TD detector. The SVM detector is more robust to sampling rate than TD detector. We find that the SVM is suitable for extended binary phase shift keying (EBPSK) signal detection and can provide accurate posterior probability for LDPC decoding. PMID:23539034

Status of rates and rate equations for thermal leptogenesis

NASA Astrophysics Data System (ADS)

Biondini, S.; Bödeker, D.; Brambilla, N.; Garny, M.; Ghiglieri, J.; Hohenegger, A.; Laine, M.; Mendizabal, S.; Millington, P.; Salvio, A.; Vairo, A.

2018-02-01

In many realizations of leptogenesis, heavy right-handed neutrinos play the main role in the generation of an imbalance between matter and antimatter in the early Universe. Hence, it is relevant to address quantitatively their dynamics in a hot and dense environment by taking into account the various thermal aspects of the problem at hand. The strong washout regime offers an interesting framework to carry out calculations systematically and reduce theoretical uncertainties. Indeed, any matter-antimatter asymmetry generated when the temperature of the hot plasma T exceeds the right-handed neutrino mass scale M is efficiently erased, and one can focus on the temperature window T ≪ M. We review recent progress in the thermal field theoretic derivation of the key ingredients for the leptogenesis mechanism: the right-handed neutrino production rate, the CP asymmetry in the heavy-neutrino decays and the washout rates. The derivation of evolution equations for the heavy-neutrino and lepton-asymmetry number densities, their rigorous formulation and applicability are also discussed.

Partially Key Distribution with Public Key Cryptosystem Based on Error Control Codes

NASA Astrophysics Data System (ADS)

Tavallaei, Saeed Ebadi; Falahati, Abolfazl

Due to the low level of security in public key cryptosystems based on number theory, fundamental difficulties such as "key escrow" in Public Key Infrastructure (PKI) and a secure channel in ID-based cryptography, a new key distribution cryptosystem based on Error Control Codes (ECC) is proposed . This idea is done by some modification on McEliece cryptosystem. The security of ECC cryptosystem obtains from the NP-Completeness of block codes decoding. The capability of generating public keys with variable lengths which is suitable for different applications will be provided by using ECC. It seems that usage of these cryptosystems because of decreasing in the security of cryptosystems based on number theory and increasing the lengths of their keys would be unavoidable in future.

60-GHz integrated-circuit high data rate quadriphase shift keying exciter and modulator

NASA Technical Reports Server (NTRS)

Grote, A.; Chang, K.

1984-01-01

An integrated-circuit quadriphase shift keying (QPSK) exciter and modulator have demonstrated excellent performance directly modulating a carrier frequency of 60 GHz with an output phase error of less than 3 degrees and maximum amplitude error of 0.5 dB. The circuit consists of a 60-GHz Gunn VCO phase-locked to a low-frequency reference source, a 4th subharmonic mixer, and a QPSK modlator packaged into a small volume of 1.8 x 2.5 x 0.35 in. The use of microstrip has the advantages of small size, light-weight, and low-cost fabrication. The unit has the potential for multigigabit data rate applications.

Experimental quantum key distribution with finite-key security analysis for noisy channels.

PubMed

Bacco, Davide; Canale, Matteo; Laurenti, Nicola; Vallone, Giuseppe; Villoresi, Paolo

2013-01-01

In quantum key distribution implementations, each session is typically chosen long enough so that the secret key rate approaches its asymptotic limit. However, this choice may be constrained by the physical scenario, as in the perspective use with satellites, where the passage of one terminal over the other is restricted to a few minutes. Here we demonstrate experimentally the extraction of secure keys leveraging an optimal design of the prepare-and-measure scheme, according to recent finite-key theoretical tight bounds. The experiment is performed in different channel conditions, and assuming two distinct attack models: individual attacks or general quantum attacks. The request on the number of exchanged qubits is then obtained as a function of the key size and of the ambient quantum bit error rate. The results indicate that viable conditions for effective symmetric, and even one-time-pad, cryptography are achievable.

Establishment of Local Trip Generation Rates or Equations for Mixed-Use Developments in Kansas

DOT National Transportation Integrated Search

2012-10-01

Currently, the trip generation rates and equations contained in the Institute of Transportation Engineers (ITE) : Trip Generation Manual, 8th Edition are based on the information collected at single-use, free-standing sites and cannot : be directly a...

A simple sub-nanosecond ultraviolet light pulse generator with high repetition rate and peak power.

PubMed

Binh, P H; Trong, V D; Renucci, P; Marie, X

2013-08-01

We present a simple ultraviolet sub-nanosecond pulse generator using commercial ultraviolet light-emitting diodes with peak emission wavelengths of 290 nm, 318 nm, 338 nm, and 405 nm. The generator is based on step recovery diode, short-circuited transmission line, and current-shaping circuit. The narrowest pulses achieved have 630 ps full width at half maximum at repetition rate of 80 MHz. Optical pulse power in the range of several hundreds of microwatts depends on the applied bias voltage. The bias voltage dependences of the output optical pulse width and peak power are analysed and discussed. Compared to commercial UV sub-nanosecond generators, the proposed generator can produce much higher pulse repetition rate and peak power.

Measurement-device-independent quantum key distribution.

PubMed

Lo, Hoi-Kwong; Curty, Marcos; Qi, Bing

2012-03-30

How to remove detector side channel attacks has been a notoriously hard problem in quantum cryptography. Here, we propose a simple solution to this problem--measurement-device-independent quantum key distribution (QKD). It not only removes all detector side channels, but also doubles the secure distance with conventional lasers. Our proposal can be implemented with standard optical components with low detection efficiency and highly lossy channels. In contrast to the previous solution of full device independent QKD, the realization of our idea does not require detectors of near unity detection efficiency in combination with a qubit amplifier (based on teleportation) or a quantum nondemolition measurement of the number of photons in a pulse. Furthermore, its key generation rate is many orders of magnitude higher than that based on full device independent QKD. The results show that long-distance quantum cryptography over say 200 km will remain secure even with seriously flawed detectors.

Seaworthy Quantum Key Distribution Design and Validation (SEAKEY)

DTIC Science & Technology

2014-07-25

link in a free- space channel through a marine environment (such as loss, noise and turbulence) and (2) parametrically calculating the secret key rate...width. Parametric calculations of the expected secret key rate As can be seen in Figure 6, the secret key rate of the BB84 protocol in the presence...Figure 9 shows the effect of various detriments on the secret -kay rate, for laser-decoy BB84. Figure 9: Effects of detriments on secret-key rate

Pacemaker implantation rate after transcatheter aortic valve implantation with early and new-generation devices: a systematic review.

PubMed

van Rosendael, Philippe J; Delgado, Victoria; Bax, Jeroen J

2018-06-01

The incidence of new-onset conduction abnormalities requiring permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation (TAVI) with new-generation prostheses remains debated. This systematic review analyses the incidence of PPI after TAVI with new-generation devices and evaluates the electrical, anatomical, and procedural factors associated with PPI. In addition, the incidence of PPI after TAVI with early generation prostheses was reviewed for comparison. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist, this systematic review screened original articles published between October 2010 and October 2017, reporting on the incidence of PPI after implantation of early and new-generation TAVI prostheses. Of the 1406 original articles identified in the first search for new-generation TAVI devices, 348 articles were examined for full text, and finally, 40 studies (n = 17 139) were included. The incidence of a PPI after the use of a new-generation TAVI prosthesis ranged between 2.3% and 36.1%. For balloon-expandable prostheses, the PPI rate remained low when using an early generation SAPIEN device (ranging between 2.3% and 28.2%), and with the new-generation SAPIEN 3 device, the PPI rate was between 4.0% and 24.0%. For self-expandable prostheses, the PPI rates were higher with the early generation CoreValve device (16.3-37.7%), and despite a reduction in PPI rates with the new Evolut R, the rates remained relatively higher (14.7-26.7%). When dividing the studies according to the highest (>26.0%) and the lowest (<12.1%) quintile of PPI rate, patients within the highest quintile were more frequently women when compared with the lowest quintile group (50.9% vs. 46.3%, P < 0.001). Pre-existent conduction abnormalities (electrical factor), calcification of the left ventricular outflow tract (anatomical factor), and balloon valvuloplasty and depth of implantation (procedural factors) were associated

Numerical approach for unstructured quantum key distribution

PubMed Central

Coles, Patrick J.; Metodiev, Eric M.; Lütkenhaus, Norbert

2016-01-01

Quantum key distribution (QKD) allows for communication with security guaranteed by quantum theory. The main theoretical problem in QKD is to calculate the secret key rate for a given protocol. Analytical formulas are known for protocols with symmetries, since symmetry simplifies the analysis. However, experimental imperfections break symmetries, hence the effect of imperfections on key rates is difficult to estimate. Furthermore, it is an interesting question whether (intentionally) asymmetric protocols could outperform symmetric ones. Here we develop a robust numerical approach for calculating the key rate for arbitrary discrete-variable QKD protocols. Ultimately this will allow researchers to study ‘unstructured' protocols, that is, those that lack symmetry. Our approach relies on transforming the key rate calculation to the dual optimization problem, which markedly reduces the number of parameters and hence the calculation time. We illustrate our method by investigating some unstructured protocols for which the key rate was previously unknown. PMID:27198739

Quantum Hash function and its application to privacy amplification in quantum key distribution, pseudo-random number generation and image encryption

NASA Astrophysics Data System (ADS)

Yang, Yu-Guang; Xu, Peng; Yang, Rui; Zhou, Yi-Hua; Shi, Wei-Min

2016-01-01

Quantum information and quantum computation have achieved a huge success during the last years. In this paper, we investigate the capability of quantum Hash function, which can be constructed by subtly modifying quantum walks, a famous quantum computation model. It is found that quantum Hash function can act as a hash function for the privacy amplification process of quantum key distribution systems with higher security. As a byproduct, quantum Hash function can also be used for pseudo-random number generation due to its inherent chaotic dynamics. Further we discuss the application of quantum Hash function to image encryption and propose a novel image encryption algorithm. Numerical simulations and performance comparisons show that quantum Hash function is eligible for privacy amplification in quantum key distribution, pseudo-random number generation and image encryption in terms of various hash tests and randomness tests. It extends the scope of application of quantum computation and quantum information.

Quantum Hash function and its application to privacy amplification in quantum key distribution, pseudo-random number generation and image encryption

PubMed Central

Yang, Yu-Guang; Xu, Peng; Yang, Rui; Zhou, Yi-Hua; Shi, Wei-Min

2016-01-01

Quantum information and quantum computation have achieved a huge success during the last years. In this paper, we investigate the capability of quantum Hash function, which can be constructed by subtly modifying quantum walks, a famous quantum computation model. It is found that quantum Hash function can act as a hash function for the privacy amplification process of quantum key distribution systems with higher security. As a byproduct, quantum Hash function can also be used for pseudo-random number generation due to its inherent chaotic dynamics. Further we discuss the application of quantum Hash function to image encryption and propose a novel image encryption algorithm. Numerical simulations and performance comparisons show that quantum Hash function is eligible for privacy amplification in quantum key distribution, pseudo-random number generation and image encryption in terms of various hash tests and randomness tests. It extends the scope of application of quantum computation and quantum information. PMID:26823196

Quantum Hash function and its application to privacy amplification in quantum key distribution, pseudo-random number generation and image encryption.

PubMed

Yang, Yu-Guang; Xu, Peng; Yang, Rui; Zhou, Yi-Hua; Shi, Wei-Min

2016-01-29

Quantum information and quantum computation have achieved a huge success during the last years. In this paper, we investigate the capability of quantum Hash function, which can be constructed by subtly modifying quantum walks, a famous quantum computation model. It is found that quantum Hash function can act as a hash function for the privacy amplification process of quantum key distribution systems with higher security. As a byproduct, quantum Hash function can also be used for pseudo-random number generation due to its inherent chaotic dynamics. Further we discuss the application of quantum Hash function to image encryption and propose a novel image encryption algorithm. Numerical simulations and performance comparisons show that quantum Hash function is eligible for privacy amplification in quantum key distribution, pseudo-random number generation and image encryption in terms of various hash tests and randomness tests. It extends the scope of application of quantum computation and quantum information.

Method for generating high-energy and high repetition rate laser pulses from CW amplifiers

DOEpatents

Zhang, Shukui

2013-06-18

A method for obtaining high-energy, high repetition rate laser pulses simultaneously using continuous wave (CW) amplifiers is described. The method provides for generating micro-joule level energy in pico-second laser pulses at Mega-hertz repetition rates.

Security proof of a three-state quantum-key-distribution protocol without rotational symmetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fung, C.-H.F.; Lo, H.-K.

2006-10-15

Standard security proofs of quantum-key-distribution (QKD) protocols often rely on symmetry arguments. In this paper, we prove the security of a three-state protocol that does not possess rotational symmetry. The three-state QKD protocol we consider involves three qubit states, where the first two states |0{sub z}> and |1{sub z}> can contribute to key generation, and the third state |+>=(|0{sub z}>+|1{sub z}>)/{radical}(2) is for channel estimation. This protocol has been proposed and implemented experimentally in some frequency-based QKD systems where the three states can be prepared easily. Thus, by founding on the security of this three-state protocol, we prove that thesemore » QKD schemes are, in fact, unconditionally secure against any attacks allowed by quantum mechanics. The main task in our proof is to upper bound the phase error rate of the qubits given the bit error rates observed. Unconditional security can then be proved not only for the ideal case of a single-photon source and perfect detectors, but also for the realistic case of a phase-randomized weak coherent light source and imperfect threshold detectors. Our result in the phase error rate upper bound is independent of the loss in the channel. Also, we compare the three-state protocol with the Bennett-Brassard 1984 (BB84) protocol. For the single-photon source case, our result proves that the BB84 protocol strictly tolerates a higher quantum bit error rate than the three-state protocol, while for the coherent-source case, the BB84 protocol achieves a higher key generation rate and secure distance than the three-state protocol when a decoy-state method is used.« less

Key parameters controlling the performance of catalytic motors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esplandiu, Maria J.; Afshar Farniya, Ali; Reguera, David, E-mail: dreguera@ub.edu

2016-03-28

The development of autonomous micro/nanomotors driven by self-generated chemical gradients is a topic of high interest given their potential impact in medicine and environmental remediation. Although impressive functionalities of these devices have been demonstrated, a detailed understanding of the propulsion mechanism is still lacking. In this work, we perform a comprehensive numerical analysis of the key parameters governing the actuation of bimetallic catalytic micropumps. We show that the fluid motion is driven by self-generated electro-osmosis where the electric field originates by a proton current rather than by a lateral charge asymmetry inside the double layer. Hence, the surface potential andmore » the electric field are the key parameters for setting the pumping strength and directionality. The proton flux that generates the electric field stems from the proton gradient induced by the electrochemical reactions taken place at the pump. Surprisingly the electric field and consequently the fluid flow are mainly controlled by the ionic strength and not by the conductivity of the solution, as one could have expected. We have also analyzed the influence of the chemical fuel concentration, electrochemical reaction rates, and size of the metallic structures for an optimized pump performance. Our findings cast light on the complex chemomechanical actuation of catalytic motors and provide important clues for the search, design, and optimization of novel catalytic actuators.« less

Key parameters controlling the performance of catalytic motors.

PubMed

Esplandiu, Maria J; Afshar Farniya, Ali; Reguera, David

2016-03-28

The development of autonomous micro/nanomotors driven by self-generated chemical gradients is a topic of high interest given their potential impact in medicine and environmental remediation. Although impressive functionalities of these devices have been demonstrated, a detailed understanding of the propulsion mechanism is still lacking. In this work, we perform a comprehensive numerical analysis of the key parameters governing the actuation of bimetallic catalytic micropumps. We show that the fluid motion is driven by self-generated electro-osmosis where the electric field originates by a proton current rather than by a lateral charge asymmetry inside the double layer. Hence, the surface potential and the electric field are the key parameters for setting the pumping strength and directionality. The proton flux that generates the electric field stems from the proton gradient induced by the electrochemical reactions taken place at the pump. Surprisingly the electric field and consequently the fluid flow are mainly controlled by the ionic strength and not by the conductivity of the solution, as one could have expected. We have also analyzed the influence of the chemical fuel concentration, electrochemical reaction rates, and size of the metallic structures for an optimized pump performance. Our findings cast light on the complex chemomechanical actuation of catalytic motors and provide important clues for the search, design, and optimization of novel catalytic actuators.

Generation time, life history and the substitution rate of neutral mutations.

PubMed

Lehtonen, Jussi; Lanfear, Robert

2014-11-01

Our understanding of molecular evolution is hampered by a lack of quantitative predictions about how life-history (LH) traits should correlate with substitution rates. Comparative studies have shown that neutral substitution rates vary substantially between species, and evidence shows that much of this diversity is associated with variation in LH traits. However, while these studies often agree, some unexplained and contradictory results have emerged. Explaining these results is difficult without a clear theoretical understanding of the problem. In this study, we derive predictions for the relationships between LH traits and substitution rates in iteroparous species by using demographic theory to relate commonly measured life-history traits to genetic generation time, and by implication to neutral substitution rates. This provides some surprisingly simple explanations for otherwise confusing patterns, such as the association between fecundity and substitution rates. The same framework can be applied to more complex life histories if full life-tables are available. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Secret Key Generation via a Modified Quantum Secret Sharing Protocol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith IV, Amos M; Evans, Philip G; Lawrie, Benjamin J

We present and experimentally show a novel protocol for distributing secret information between two and only two parties in a N-party single-qubit Quantum Secret Sharing (QSS) system. We demonstrate this new algorithm with N = 3 active parties over 6km of telecom. ber. Our experimental device is based on the Clavis2 Quantum Key Distribution (QKD) system built by ID Quantique but is generalizable to any implementation. We show that any two out of the N parties can build secret keys based on partial information from each other and with collaboration from the remaining N > 2 parties. This algorithm allowsmore » for the creation of two-party secret keys were standard QSS does not and signicantly reduces the number of resources needed to implement QKD on a highly connected network such as the electrical grid.« less

Performance of device-independent quantum key distribution

NASA Astrophysics Data System (ADS)

Cao, Zhu; Zhao, Qi; Ma, Xiongfeng

2016-07-01

Quantum key distribution provides information-theoretically-secure communication. In practice, device imperfections may jeopardise the system security. Device-independent quantum key distribution solves this problem by providing secure keys even when the quantum devices are untrusted and uncharacterized. Following a recent security proof of the device-independent quantum key distribution, we improve the key rate by tightening the parameter choice in the security proof. In practice where the system is lossy, we further improve the key rate by taking into account the loss position information. From our numerical simulation, our method can outperform existing results. Meanwhile, we outline clear experimental requirements for implementing device-independent quantum key distribution. The maximal tolerable error rate is 1.6%, the minimal required transmittance is 97.3%, and the minimal required visibility is 96.8 % .

Multiparty quantum key agreement with single particles

NASA Astrophysics Data System (ADS)

Liu, Bin; Gao, Fei; Huang, Wei; Wen, Qiao-yan

2013-04-01

Two conditions must be satisfied in a secure quantum key agreement (QKA) protocol: (1) outside eavesdroppers cannot gain the generated key without introducing any error; (2) the generated key cannot be determined by any non-trivial subset of the participants. That is, a secure QKA protocol can not only prevent the outside attackers from stealing the key, but also resist the attack from inside participants, i.e. some dishonest participants determine the key alone by illegal means. How to resist participant attack is an aporia in the design of QKA protocols, especially the multi-party ones. In this paper we present the first secure multiparty QKA protocol against both outside and participant attacks. Further more, we have proved its security in detail.

Quantum key distribution over a 72 dB channel loss using ultralow dark count superconducting single-photon detectors.

PubMed

Shibata, Hiroyuki; Honjo, Toshimori; Shimizu, Kaoru

2014-09-01

We report the first quantum key distribution (QKD) experiment over a 72 dB channel loss using superconducting nanowire single-photon detectors (SSPD, SNSPD) with the dark count rate (DCR) of 0.01 cps. The DCR of the SSPD, which is dominated by the blackbody radiation at room temperature, is blocked by introducing cold optical bandpass filter. We employ the differential phase shift QKD (DPS-QKD) scheme with a 1 GHz system clock rate. The quantum bit error rate (QBER) below 3% is achieved when the length of the dispersion shifted fiber (DSF) is 336 km (72 dB loss), which is low enough to generate secure keys.

Small Private Key PKS on an Embedded Microprocessor

PubMed Central

Seo, Hwajeong; Kim, Jihyun; Choi, Jongseok; Park, Taehwan; Liu, Zhe; Kim, Howon

2014-01-01

Multivariate quadratic ( ) cryptography requires the use of long public and private keys to ensure a sufficient security level, but this is not favorable to embedded systems, which have limited system resources. Recently, various approaches to cryptography using reduced public keys have been studied. As a result of this, at CHES2011 (Cryptographic Hardware and Embedded Systems, 2011), a small public key scheme, was proposed, and its feasible implementation on an embedded microprocessor was reported at CHES2012. However, the implementation of a small private key scheme was not reported. For efficient implementation, random number generators can contribute to reduce the key size, but the cost of using a random number generator is much more complex than computing on modern microprocessors. Therefore, no feasible results have been reported on embedded microprocessors. In this paper, we propose a feasible implementation on embedded microprocessors for a small private key scheme using a pseudo-random number generator and hash function based on a block-cipher exploiting a hardware Advanced Encryption Standard (AES) accelerator. To speed up the performance, we apply various implementation methods, including parallel computation, on-the-fly computation, optimized logarithm representation, vinegar monomials and assembly programming. The proposed method reduces the private key size by about 99.9% and boosts signature generation and verification by 5.78% and 12.19% than previous results in CHES2012. PMID:24651722

Small private key MQPKS on an embedded microprocessor.

PubMed

Seo, Hwajeong; Kim, Jihyun; Choi, Jongseok; Park, Taehwan; Liu, Zhe; Kim, Howon

2014-03-19

Multivariate quadratic (MQ) cryptography requires the use of long public and private keys to ensure a sufficient security level, but this is not favorable to embedded systems, which have limited system resources. Recently, various approaches to MQ cryptography using reduced public keys have been studied. As a result of this, at CHES2011 (Cryptographic Hardware and Embedded Systems, 2011), a small public key MQ scheme, was proposed, and its feasible implementation on an embedded microprocessor was reported at CHES2012. However, the implementation of a small private key MQ scheme was not reported. For efficient implementation, random number generators can contribute to reduce the key size, but the cost of using a random number generator is much more complex than computing MQ on modern microprocessors. Therefore, no feasible results have been reported on embedded microprocessors. In this paper, we propose a feasible implementation on embedded microprocessors for a small private key MQ scheme using a pseudo-random number generator and hash function based on a block-cipher exploiting a hardware Advanced Encryption Standard (AES) accelerator. To speed up the performance, we apply various implementation methods, including parallel computation, on-the-fly computation, optimized logarithm representation, vinegar monomials and assembly programming. The proposed method reduces the private key size by about 99.9% and boosts signature generation and verification by 5.78% and 12.19% than previous results in CHES2012.

The role of dose rate in radiation cancer risk: evaluating the effect of dose rate at the molecular, cellular and tissue levels using key events in critical pathways following exposure to low LET radiation

PubMed Central

Brooks, Antone L.; Hoel, David G.; Preston, R. Julian

2016-01-01

Abstract Purpose: This review evaluates the role of dose rate on cell and molecular responses. It focuses on the influence of dose rate on key events in critical pathways in the development of cancer. This approach is similar to that used by the U.S. EPA and others to evaluate risk from chemicals. It provides a mechanistic method to account for the influence of the dose rate from low-LET radiation, especially in the low-dose region on cancer risk assessment. Molecular, cellular, and tissues changes are observed in many key events and change as a function of dose rate. The magnitude and direction of change can be used to help establish an appropriate dose rate effectiveness factor (DREF). Conclusions: Extensive data on key events suggest that exposure to low dose-rates are less effective in producing changes than high dose rates. Most of these data at the molecular and cellular level support a large (2–30) DREF. In addition, some evidence suggests that doses delivered at a low dose rate decrease damage to levels below that observed in the controls. However, there are some data human and mechanistic data that support a dose-rate effectiveness factor of 1. In summary, a review of the available molecular, cellular and tissue data indicates that not only is dose rate an important variable in understanding radiation risk but it also supports the selection of a DREF greater than one as currently recommended by ICRP (2007) and BEIR VII (NRC/NAS 2006). PMID:27266588

Continuous high speed coherent one-way quantum key distribution.

PubMed

Stucki, Damien; Barreiro, Claudio; Fasel, Sylvain; Gautier, Jean-Daniel; Gay, Olivier; Gisin, Nicolas; Thew, Rob; Thoma, Yann; Trinkler, Patrick; Vannel, Fabien; Zbinden, Hugo

2009-08-03

Quantum key distribution (QKD) is the first commercial quantum technology operating at the level of single quanta and is a leading light for quantum-enabled photonic technologies. However, controlling these quantum optical systems in real world environments presents significant challenges. For the first time, we have brought together three key concepts for future QKD systems: a simple high-speed protocol; high performance detection; and integration both, at the component level and for standard fibre network connectivity. The QKD system is capable of continuous and autonomous operation, generating secret keys in real time. Laboratory and field tests were performed and comparisons made with robust InGaAs avalanche photodiodes and superconducting detectors. We report the first real world implementation of a fully functional QKD system over a 43 dB-loss (150 km) transmission line in the Swisscom fibre optic network where we obtained average real-time distribution rates over 3 hours of 2.5 bps.

An improved scheme on decoy-state method for measurement-device-independent quantum key distribution.

PubMed

Wang, Dong; Li, Mo; Guo, Guang-Can; Wang, Qin

2015-10-14

Quantum key distribution involving decoy-states is a significant application of quantum information. By using three-intensity decoy-states of single-photon-added coherent sources, we propose a practically realizable scheme on quantum key distribution which approaches very closely the ideal asymptotic case of an infinite number of decoy-states. We make a comparative study between this scheme and two other existing ones, i.e., two-intensity decoy-states with single-photon-added coherent sources, and three-intensity decoy-states with weak coherent sources. Through numerical analysis, we demonstrate the advantages of our scheme in secure transmission distance and the final key generation rate.

An improved scheme on decoy-state method for measurement-device-independent quantum key distribution

PubMed Central

Wang, Dong; Li, Mo; Guo, Guang-Can; Wang, Qin

2015-01-01

Quantum key distribution involving decoy-states is a significant application of quantum information. By using three-intensity decoy-states of single-photon-added coherent sources, we propose a practically realizable scheme on quantum key distribution which approaches very closely the ideal asymptotic case of an infinite number of decoy-states. We make a comparative study between this scheme and two other existing ones, i.e., two-intensity decoy-states with single-photon-added coherent sources, and three-intensity decoy-states with weak coherent sources. Through numerical analysis, we demonstrate the advantages of our scheme in secure transmission distance and the final key generation rate. PMID:26463580

Security of quantum key distribution with iterative sifting

NASA Astrophysics Data System (ADS)

Tamaki, Kiyoshi; Lo, Hoi-Kwong; Mizutani, Akihiro; Kato, Go; Lim, Charles Ci Wen; Azuma, Koji; Curty, Marcos

2018-01-01

Several quantum key distribution (QKD) protocols employ iterative sifting. After each quantum transmission round, Alice and Bob disclose part of their setting information (including their basis choices) for the detected signals. This quantum phase then ends when the basis dependent termination conditions are met, i.e., the numbers of detected signals per basis exceed certain pre-agreed threshold values. Recently, however, Pfister et al (2016 New J. Phys. 18 053001) showed that the basis dependent termination condition makes QKD insecure, especially in the finite key regime, and they suggested to disclose all the setting information after finishing the quantum phase. However, this protocol has two main drawbacks: it requires that Alice possesses a large memory, and she also needs to have some a priori knowledge about the transmission rate of the quantum channel. Here we solve these two problems by introducing a basis-independent termination condition to the iterative sifting in the finite key regime. The use of this condition, in combination with Azuma’s inequality, provides a precise estimation on the amount of privacy amplification that needs to be applied, thus leading to the security of QKD protocols, including the loss-tolerant protocol (Tamaki et al 2014 Phys. Rev. A 90 052314), with iterative sifting. Our analysis indicates that to announce the basis information after each quantum transmission round does not compromise the key generation rate of the loss-tolerant protocol. Our result allows the implementation of wider classes of classical post-processing techniques in QKD with quantified security.

DNA Cryptography and Deep Learning using Genetic Algorithm with NW algorithm for Key Generation.

PubMed

Kalsi, Shruti; Kaur, Harleen; Chang, Victor

2017-12-05

Cryptography is not only a science of applying complex mathematics and logic to design strong methods to hide data called as encryption, but also to retrieve the original data back, called decryption. The purpose of cryptography is to transmit a message between a sender and receiver such that an eavesdropper is unable to comprehend it. To accomplish this, not only we need a strong algorithm, but a strong key and a strong concept for encryption and decryption process. We have introduced a concept of DNA Deep Learning Cryptography which is defined as a technique of concealing data in terms of DNA sequence and deep learning. In the cryptographic technique, each alphabet of a letter is converted into a different combination of the four bases, namely; Adenine (A), Cytosine (C), Guanine (G) and Thymine (T), which make up the human deoxyribonucleic acid (DNA). Actual implementations with the DNA don't exceed laboratory level and are expensive. To bring DNA computing on a digital level, easy and effective algorithms are proposed in this paper. In proposed work we have introduced firstly, a method and its implementation for key generation based on the theory of natural selection using Genetic Algorithm with Needleman-Wunsch (NW) algorithm and Secondly, a method for implementation of encryption and decryption based on DNA computing using biological operations Transcription, Translation, DNA Sequencing and Deep Learning.

Free-space measurement-device-independent quantum-key-distribution protocol using decoy states with orbital angular momentum

NASA Astrophysics Data System (ADS)

Wang, Le; Zhao, Sheng-Mei; Gong, Long-Yan; Cheng, Wei-Wen

2015-12-01

In this paper, we propose a measurement-device-independent quantum-key-distribution (MDI-QKD) protocol using orbital angular momentum (OAM) in free space links, named the OAM-MDI-QKD protocol. In the proposed protocol, the OAM states of photons, instead of polarization states, are used as the information carriers to avoid the reference frame alignment, the decoy-state is adopted to overcome the security loophole caused by the weak coherent pulse source, and the high efficient OAM-sorter is adopted as the measurement tool for Charlie to obtain the output OAM state. Here, Charlie may be an untrusted third party. The results show that the authorized users, Alice and Bob, could distill a secret key with Charlie’s successful measurements, and the key generation performance is slightly better than that of the polarization-based MDI-QKD protocol in the two-dimensional OAM cases. Simultaneously, Alice and Bob can reduce the number of flipping the bits in the secure key distillation. It is indicated that a higher key generation rate performance could be obtained by a high dimensional OAM-MDI-QKD protocol because of the unlimited degree of freedom on OAM states. Moreover, the results show that the key generation rate and the transmission distance will decrease as the growth of the strength of atmospheric turbulence (AT) and the link attenuation. In addition, the decoy states used in the proposed protocol can get a considerable good performance without the need for an ideal source. Project supported by the National Natural Science Foundation of China (Grant Nos. 61271238 and 61475075), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20123223110003), the Natural Science Research Foundation for Universities of Jiangsu Province of China (Grant No. 11KJA510002), the Open Research Fund of Key Laboratory of Broadband Wireless Communication and Sensor Network Technology, Ministry of Education, China (Grant No. NYKL2015011), and the

Investigation of thermolytic hydrogen generation rate of tank farm simulated and actual waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martino, C.; Newell, D.; Woodham, W.

To support resolution of Potential Inadequacies in the Safety Analysis for the Savannah River Site (SRS) Tank Farm, Savannah River National Laboratory conducted research to determine the thermolytic hydrogen generation rate (HGR) with simulated and actual waste. Gas chromatography methods were developed and used with air-purged flow systems to quantify hydrogen generation from heated simulated and actual waste at rates applicable to the Tank Farm Documented Safety Analysis (DSA). Initial simulant tests with a simple salt solution plus sodium glycolate demonstrated the behavior of the test apparatus by replicating known HGR kinetics. Additional simulant tests with the simple salt solutionmore » excluding organics apart from contaminants provided measurement of the detection and quantification limits for the apparatus with respect to hydrogen generation. Testing included a measurement of HGR on actual SRS tank waste from Tank 38. A final series of measurements examined HGR for a simulant with the most common SRS Tank Farm organics at temperatures up to 140 °C. The following conclusions result from this testing.« less

Design keys for paper-based concentration gradient generators.

PubMed

Schaumburg, Federico; Urteaga, Raúl; Kler, Pablo A; Berli, Claudio L A

2018-08-03

The generation of concentration gradients is an essential operation for several analytical processes implemented on microfluidic paper-based analytical devices. The dynamic gradient formation is based on the transverse dispersion of chemical species across co-flowing streams. In paper channels, this transverse flux of molecules is dominated by mechanical dispersion, which is substantially different than molecular diffusion, which is the mechanism acting in conventional microchannels. Therefore, the design of gradient generators on paper requires strategies different from those used in traditional microfluidics. This work considers the foundations of transverse dispersion in porous substrates to investigate the optimal design of microfluidic paper-based concentration gradient generators (μPGGs) by computer simulations. A set of novel and versatile μPGGs were designed in the format of numerical prototypes, and virtual experiments were run to explore the ranges of operation and the overall performance of such devices. Then physical prototypes were fabricated and experimentally tested in our lab. Finally, some basic rules for the design of optimized μPGGs are proposed. Apart from improving the efficiency of mixers, diluters and μPGGs, the results of this investigation are relevant to attain highly controlled concentration fields on paper-based devices. Copyright © 2018 Elsevier B.V. All rights reserved.

Qualified nurses' rate new nursing graduates as lacking skills in key clinical areas.

PubMed

Missen, Karen; McKenna, Lisa; Beauchamp, Alison; Larkins, Jo-Ann

2016-08-01

The aim of this study was to explore perceptions of qualified nurses on the abilities of newly registered nursing graduates to perform a variety of clinical skills. Evidence from the literature suggests that undergraduate nursing programmes do not adequately prepare nursing students to be practice-ready on completion of their nursing courses. A descriptive quantitative design was used. Participants were recruited through the Australian Nursing and Midwifery Federation, Victorian branch. A brief explanation of the study and a link to the survey were promoted in their monthly e-newsletter. A total of 245 qualified nurses in the state of Victoria, Australia participated in this study. A survey tool of 51 clinical skills and open-ended questions was used, whereby participants were asked to rate new nursing graduates' abilities using a 5-point Likert scale. Overall participants rated new nursing graduates' abilities for undertaking clinical skills as good or very good in 35·3% of skills, 33·3% were rated as adequate and 31·4% rated as being performed poorly or very poorly. Of concern, essential clinical skills, such as critical thinking and problem solving, working independently and assessment procedures, were found to be poorly executed and affecting new registered nurses graduates' competence. The findings from this study can further serve as a reference for nursing education providers to enhance nursing curricula and work collaboratively with healthcare settings in preparing nurses to be competent, safe practitioners on completion of their studies. Identifying key areas in which new nursing graduates are not yet competent means that educational providers and educators from healthcare settings can focus on these skills in better preparing our nurses to be work ready. © 2016 John Wiley & Sons Ltd.

Identification and Characterization of Key Human Performance Issues and Research in the Next Generation Air Transportation System (NextGen)

NASA Technical Reports Server (NTRS)

Lee, Paul U.; Sheridan, Tom; Poage, james L.; Martin, Lynne Hazel; Jobe, Kimberly K.

2010-01-01

This report identifies key human-performance-related issues associated with Next Generation Air Transportation System (NextGen) research in the NASA NextGen-Airspace Project. Four Research Focus Areas (RFAs) in the NextGen-Airspace Project - namely Separation Assurance (SA), Airspace Super Density Operations (ASDO), Traffic Flow Management (TFM), and Dynamic Airspace Configuration (DAC) - were examined closely. In the course of the research, it was determined that the identified human performance issues needed to be analyzed in the context of NextGen operations rather than through basic human factors research. The main gaps in human factors research in NextGen were found in the need for accurate identification of key human-systems related issues within the context of specific NextGen concepts and better design of the operational requirements for those concepts. By focusing on human-system related issues for individual concepts, key human performance issues for the four RFAs were identified and described in this report. In addition, mixed equipage airspace with components of two RFAs were characterized to illustrate potential human performance issues that arise from the integration of multiple concepts.

Elevated mutation rates in the germ line of first- and second-generation offspring of irradiated male mice

PubMed Central

Barber, Ruth; Plumb, Mark A.; Boulton, Emma; Roux, Isabelle; Dubrova, Yuri E.

2002-01-01

Mutation rates at two expanded simple tandem repeat loci were studied in the germ line of first- and second-generation offspring of inbred male CBA/H, C57BL/6, and BALB/c mice exposed to either high linear energy transfer fission neutrons or low linear energy transfer x-rays. Paternal CBA/H exposure to either x-rays or fission neutrons resulted in increased mutation rates in the germ line of two subsequent generations. Comparable transgenerational effects were observed also in neutron-irradiated C57BL/6 and x-irradiated BALB/c mice. The levels of spontaneous mutation rates and radiation-induced transgenerational instability varied between strains (BALB/c>CBA/H>C57BL/6). Pre- and postmeiotic paternal exposure resulted in similar increases in mutation rate in the germ line of both generations of CBA/H mice, which together with our previous results suggests that radiation-induced expanded simple tandem repeat instability is manifested in diploid cells after fertilization. The remarkable finding that radiation-induced germ-line instability persists for at least two generations raises important issues of risk evaluation in humans. PMID:11997464

Establishment of Local Trip Generation Rates or Equations for Mixed-Use Developments in Kansas : Technical Summary

DOT National Transportation Integrated Search

2012-10-01

Currently, the trip generation rates and equations contained in the Institute of Transportation Engineers (ITE) Trip Generation Manual, 8th Edition are based on the information collected at single-use, free-standing sites and cannot be directly appli...

Sparse Representations-Based Super-Resolution of Key-Frames Extracted from Frames-Sequences Generated by a Visual Sensor Network

PubMed Central

Sajjad, Muhammad; Mehmood, Irfan; Baik, Sung Wook

2014-01-01

Visual sensor networks (VSNs) usually generate a low-resolution (LR) frame-sequence due to energy and processing constraints. These LR-frames are not very appropriate for use in certain surveillance applications. It is very important to enhance the resolution of the captured LR-frames using resolution enhancement schemes. In this paper, an effective framework for a super-resolution (SR) scheme is proposed that enhances the resolution of LR key-frames extracted from frame-sequences captured by visual-sensors. In a VSN, a visual processing hub (VPH) collects a huge amount of visual data from camera sensors. In the proposed framework, at the VPH, key-frames are extracted using our recent key-frame extraction technique and are streamed to the base station (BS) after compression. A novel effective SR scheme is applied at BS to produce a high-resolution (HR) output from the received key-frames. The proposed SR scheme uses optimized orthogonal matching pursuit (OOMP) for sparse-representation recovery in SR. OOMP does better in terms of detecting true sparsity than orthogonal matching pursuit (OMP). This property of the OOMP helps produce a HR image which is closer to the original image. The K-SVD dictionary learning procedure is incorporated for dictionary learning. Batch-OMP improves the dictionary learning process by removing the limitation in handling a large set of observed signals. Experimental results validate the effectiveness of the proposed scheme and show its superiority over other state-of-the-art schemes. PMID:24566632

Sparse representations-based super-resolution of key-frames extracted from frames-sequences generated by a visual sensor network.

PubMed

Sajjad, Muhammad; Mehmood, Irfan; Baik, Sung Wook

2014-02-21

Visual sensor networks (VSNs) usually generate a low-resolution (LR) frame-sequence due to energy and processing constraints. These LR-frames are not very appropriate for use in certain surveillance applications. It is very important to enhance the resolution of the captured LR-frames using resolution enhancement schemes. In this paper, an effective framework for a super-resolution (SR) scheme is proposed that enhances the resolution of LR key-frames extracted from frame-sequences captured by visual-sensors. In a VSN, a visual processing hub (VPH) collects a huge amount of visual data from camera sensors. In the proposed framework, at the VPH, key-frames are extracted using our recent key-frame extraction technique and are streamed to the base station (BS) after compression. A novel effective SR scheme is applied at BS to produce a high-resolution (HR) output from the received key-frames. The proposed SR scheme uses optimized orthogonal matching pursuit (OOMP) for sparse-representation recovery in SR. OOMP does better in terms of detecting true sparsity than orthogonal matching pursuit (OMP). This property of the OOMP helps produce a HR image which is closer to the original image. The K-SVD dictionary learning procedure is incorporated for dictionary learning. Batch-OMP improves the dictionary learning process by removing the limitation in handling a large set of observed signals. Experimental results validate the effectiveness of the proposed scheme and show its superiority over other state-of-the-art schemes.

Staff Preparation, Reward, and Support: Are Quality Rating and Improvement Systems Addressing All of the Key Ingredients Necessary for Change? Policy Report

ERIC Educational Resources Information Center

Austin, Lea J. E.; Whitebook, Marcy; Connors, Maia; Darrah, Rory

2011-01-01

Reflecting the growing momentum in support of quality rating and improvement systems (QRISs) as a key strategy to improve early care and education quality, significant amounts of public dollars have been devoted to their development and implementation. In this brief, the authors report on their investigation of both quality rating and improvement…

Nonlinear radiative heat flux and heat source/sink on entropy generation minimization rate

NASA Astrophysics Data System (ADS)

Hayat, T.; Khan, M. Waleed Ahmed; Khan, M. Ijaz; Alsaedi, A.

2018-06-01

Entropy generation minimization in nonlinear radiative mixed convective flow towards a variable thicked surface is addressed. Entropy generation for momentum and temperature is carried out. The source for this flow analysis is stretching velocity of sheet. Transformations are used to reduce system of partial differential equations into ordinary ones. Total entropy generation rate is determined. Series solutions for the zeroth and mth order deformation systems are computed. Domain of convergence for obtained solutions is identified. Velocity, temperature and concentration fields are plotted and interpreted. Entropy equation is studied through nonlinear mixed convection and radiative heat flux. Velocity and temperature gradients are discussed through graphs. Meaningful results are concluded in the final remarks.

Megahertz-Rate Semi-Device-Independent Quantum Random Number Generators Based on Unambiguous State Discrimination

NASA Astrophysics Data System (ADS)

Brask, Jonatan Bohr; Martin, Anthony; Esposito, William; Houlmann, Raphael; Bowles, Joseph; Zbinden, Hugo; Brunner, Nicolas

2017-05-01

An approach to quantum random number generation based on unambiguous quantum state discrimination is developed. We consider a prepare-and-measure protocol, where two nonorthogonal quantum states can be prepared, and a measurement device aims at unambiguously discriminating between them. Because the states are nonorthogonal, this necessarily leads to a minimal rate of inconclusive events whose occurrence must be genuinely random and which provide the randomness source that we exploit. Our protocol is semi-device-independent in the sense that the output entropy can be lower bounded based on experimental data and a few general assumptions about the setup alone. It is also practically relevant, which we demonstrate by realizing a simple optical implementation, achieving rates of 16.5 Mbits /s . Combining ease of implementation, a high rate, and a real-time entropy estimation, our protocol represents a promising approach intermediate between fully device-independent protocols and commercial quantum random number generators.

Single-pass high harmonic generation at high repetition rate and photon flux

NASA Astrophysics Data System (ADS)

Hädrich, Steffen; Rothhardt, Jan; Krebs, Manuel; Demmler, Stefan; Klenke, Arno; Tünnermann, Andreas; Limpert, Jens

2016-09-01

Sources of short wavelength radiation with femtosecond to attosecond pulse durations, such as synchrotrons or free electron lasers, have already made possible numerous, and will facilitate more, seminal studies aimed at understanding atomic and molecular processes on fundamental length and time scales. Table-top sources of coherent extreme ultraviolet to soft x-ray radiation enabled by high harmonic generation (HHG) of ultrashort pulse lasers have also gained significant attention in the last few years due to their enormous potential for addressing a plethora of applications, therefore constituting a complementary source to large-scale facilities (synchrotrons and free electron lasers). Ti:sapphire based laser systems have been the workhorses for HHG for decades, but are limited in repetition rate and average power. On the other hand, it has been widely recognized that fostering applications in fields such as photoelectron spectroscopy and microscopy, coincidence detection, coherent diffractive imaging and frequency metrology requires a high repetition rate and high photon flux HHG sources. In this article we will review recent developments in realizing the demanding requirement of producing a high photon flux and repetition rate at the same time. Particular emphasis will be put on suitable ultrashort pulse and high average power lasers, which directly drive harmonic generation without the need for external enhancement cavities. To this end we describe two complementary schemes that have been successfully employed for high power fiber lasers, i.e. optical parametric chirped pulse amplifiers and nonlinear pulse compression. Moreover, the issue of phase-matching in tight focusing geometries will be discussed and connected to recent experiments. We will highlight the latest results in fiber laser driven high harmonic generation that currently produce the highest photon flux of all existing sources. In addition, we demonstrate the first promising applications and

Common-signal-induced synchronization in photonic integrated circuits and its application to secure key distribution.

PubMed

Sasaki, Takuma; Kakesu, Izumi; Mitsui, Yusuke; Rontani, Damien; Uchida, Atsushi; Sunada, Satoshi; Yoshimura, Kazuyuki; Inubushi, Masanobu

2017-10-16

We experimentally achieve common-signal-induced synchronization in two photonic integrated circuits with short external cavities driven by a constant-amplitude random-phase light. The degree of synchronization can be controlled by changing the optical feedback phase of the two photonic integrated circuits. The change in the optical feedback phase leads to a significant redistribution of the spectral energy of optical and RF spectra, which is a unique characteristic of PICs with the short external cavity. The matching of the RF and optical spectra is necessary to achieve synchronization between the two PICs, and stable synchronization can be obtained over an hour in the presence of optical feedback. We succeed in generating information-theoretic secure keys and achieving the final key generation rate of 184 kb/s using the PICs.

Design of a liquid membrane target for high repetition rate neutron generation

NASA Astrophysics Data System (ADS)

Poole, Patrick; Andereck, C. David; Storm, Mike; Schumacher, Douglass

2013-10-01

Ultra-bright, pulsed, spatially-small sources of energetic neutrons have applications in radiography and non-destructive remote sensing. Neutrons can be generated by a process wherein ions accelerated from a laser-irradiated primary target subsequently bombard a converter material, causing neutron-producing nuclear reactions, such as 7Li(d,n)8Be. Deuterons from this process are suppressed by contamination that builds up on the rear of the solid primary target. To eliminate this issue we propose a self-replenishing liquid membrane target consisting of heavy water and deuterated surfactant, formed in-vacuum within a moveable wire frame. In addition to removing issues associated with solid target positioning and collateral damage, this apparatus provides flow rate and target thickness control, and allows for the high repetition rates required to generate desired neutron fluxes with a portable laser-based system. The apparatus design will be presented, as well as a novel interferometric method that measures the membrane thickness using tightly-focused light. This work was performed with support from DARPA.

Optimization and phase matching of fiber-laser-driven high-order harmonic generation at high repetition rate.

PubMed

Cabasse, Amélie; Machinet, Guillaume; Dubrouil, Antoine; Cormier, Eric; Constant, Eric

2012-11-15

High-repetition-rate sources are very attractive for high-order harmonic generation (HHG). However, due to their pulse characteristics (low energy, long duration), those systems require a tight focusing geometry to achieve the necessary intensity to generate harmonics. In this Letter, we investigate theoretically and experimentally the optimization of HHG in this geometry, to maximize the extreme UV (XUV) photon flux and improve the conversion efficiency. We analyze the influence of atomic gas media (Ar, Kr, or Xe), gas pressure, and interaction geometries (a gas jet and a finite and a semi-infinite gas cell). Numerical simulations allow us to define optimal conditions for HHG in this tight focusing regime and to observe the signature of on-axis phase matching. These conditions are implemented experimentally using a high-repetition-rate Yb-doped fiber laser system. We achieve optimization of emission with a recorded XUV photon flux of 4.5×10(12) photons/s generated in Xe at 100 kHz repetition rate.

System and method for key generation in security tokens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, Philip G.; Humble, Travis S.; Paul, Nathanael R.

Functional randomness in security tokens (FRIST) may achieve improved security in two-factor authentication hardware tokens by improving on the algorithms used to securely generate random data. A system and method in one embodiment according to the present invention may allow for security of a token based on storage cost and computational security. This approach may enable communication where security is no longer based solely on onetime pads (OTPs) generated from a single cryptographic function (e.g., SHA-256).

Hazardous medical waste generation rates of different categories of health-care facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komilis, Dimitrios, E-mail: dkomilis@env.duth.gr; Fouki, Anastassia; Papadopoulos, Dimitrios

Highlights: Black-Right-Pointing-Pointer We calculated hazardous medical waste generation rates (HMWGR) from 132 hospitals. Black-Right-Pointing-Pointer Based on a 22-month study period, HMWGR were highly skewed to the right. Black-Right-Pointing-Pointer The HMWGR varied from 0.00124 to 0.718 kg bed{sup -1} d{sup -1}. Black-Right-Pointing-Pointer A positive correlation existed between the HMWGR and the number of hospital beds. Black-Right-Pointing-Pointer We used non-parametric statistics to compare rates among hospital categories. - Abstract: Goal of this work was to calculate the hazardous medical waste unit generation rates (HMWUGR), in kg bed{sup -1} d{sup -1}, using data from 132 health-care facilities in Greece. The calculations were basedmore » on the weights of the hazardous medical wastes that were regularly transferred to the sole medical waste incinerator in Athens over a 22-month period during years 2009 and 2010. The 132 health-care facilities were grouped into public and private ones, and, also, into seven sub-categories, namely: birth, cancer treatment, general, military, pediatric, psychiatric and university hospitals. Results showed that there is a large variability in the HMWUGR, even among hospitals of the same category. Average total HMWUGR varied from 0.012 kg bed{sup -1} d{sup -1}, for the public psychiatric hospitals, to up to 0.72 kg bed{sup -1} d{sup -1}, for the public university hospitals. Within the private hospitals, average HMWUGR ranged from 0.0012 kg bed{sup -1} d{sup -1}, for the psychiatric clinics, to up to 0.49 kg bed{sup -1} d{sup -1}, for the birth clinics. Based on non-parametric statistics, HMWUGR were statistically similar for the birth and general hospitals, in both the public and private sector. The private birth and general hospitals generated statistically more wastes compared to the corresponding public hospitals. The infectious/toxic and toxic medical wastes appear to be 10% and 50% of the total hazardous medical

Generation rate and particle size distribution of wood dust by handheld sanding operation.

PubMed

Ojima, Jun

2016-11-29

The International Agency for Research on Cancer (IARC) and Japan Society for Occupational Health (JSOH) classified wood dust as a human carcinogen. Former studies have suggested that sanding with a portable sander is one of the processes that are liable to cause highest exposure to wood dust. However, the wood dust by sanding operation has not been investigated sufficiently. In this study, the generation rate and the particle size distribution of the wood dust produced by handheld sanding operation were observed by laboratory experiments. Beech and cypress were taken as typical hard and soft wood specimen respectively, and sanded with a portable sander. Three grades of sand paper (coarse, medium, fine) were attached to the sander in turn to be tested. The quantity of the wood dust produced by the sander was measured by weighing the specimen before and after the sanding and then the generation rate of the dust was calculated. Soft wood generated more dust than hard wood due to the difference in abrasion durability. A coarse sand paper produced more dust than a fine sand paper. The particles of less than 1 μm diameter were scarcely observed in the wood dust. When the specimens were sanded with a fine sand paper, the mass median aerodynamic diameters of beech dust and cypress dust were 9.0 μm and 9.8 μm, respectively. Respirable wood dust is able to be controlled by general ventilation with more than 0.7-4.2 m 3 /min ventilation rate.

Generation rate and particle size distribution of wood dust by handheld sanding operation

PubMed Central

Ojima, Jun

2016-01-01

Objectives: The International Agency for Research on Cancer (IARC) and Japan Society for Occupational Health (JSOH) classified wood dust as a human carcinogen. Former studies have suggested that sanding with a portable sander is one of the processes that are liable to cause highest exposure to wood dust. However, the wood dust by sanding operation has not been investigated sufficiently. In this study, the generation rate and the particle size distribution of the wood dust produced by handheld sanding operation were observed by laboratory experiments. Methods: Beech and cypress were taken as typical hard and soft wood specimen respectively, and sanded with a portable sander. Three grades of sand paper (coarse, medium, fine) were attached to the sander in turn to be tested. The quantity of the wood dust produced by the sander was measured by weighing the specimen before and after the sanding and then the generation rate of the dust was calculated. Results: Soft wood generated more dust than hard wood due to the difference in abrasion durability. A coarse sand paper produced more dust than a fine sand paper. The particles of less than 1 μm diameter were scarcely observed in the wood dust. When the specimens were sanded with a fine sand paper, the mass median aerodynamic diameters of beech dust and cypress dust were 9.0 μm and 9.8 μm, respectively. Conclusions: Respirable wood dust is able to be controlled by general ventilation with more than 0.7-4.2 m3/min ventilation rate. PMID:27725491

A 7.8 kV nanosecond pulse generator with a 500 Hz repetition rate

NASA Astrophysics Data System (ADS)

Lin, M.; Liao, H.; Liu, M.; Zhu, G.; Yang, Z.; Shi, P.; Lu, Q.; Sun, X.

2018-04-01

Pseudospark switches are widely used in pulsed power applications. In this paper, we present the design and performance of a 500 Hz repetition rate high-voltage pulse generator to drive TDI-series pseudospark switches. A high-voltage pulse is produced by discharging an 8 μF capacitor through a primary windings of a setup isolation transformer using a single metal-oxide-semiconductor field-effect transistor (MOSFET) as a control switch. In addition, a self-break spark gap is used to steepen the pulse front. The pulse generator can deliver a high-voltage pulse with a peak trigger voltage of 7.8 kV, a peak trigger current of 63 A, a full width at half maximum (FWHM) of ~30 ns, and a rise time of 5 ns to the trigger pin of the pseudospark switch. During burst mode operation, the generator achieved up to a 500 Hz repetition rate. Meanwhile, we also provide an AC heater power circuit for heating a H2 reservoir. This pulse generator can be used in circuits with TDI-series pseudospark switches with either a grounded cathode or with a cathode electrically floating operation. The details of the circuits and their implementation are described in the paper.

The Geology of the Florida Keys.

ERIC Educational Resources Information Center

Shinn, Eugene A.

1988-01-01

Describes some of the ancient geologic history of the Florida Keys from Key Largo to Key West including the effects of glaciers, sea level rise, reef distribution, spurs and grooves, backstepping and ecological zonation, growth rates and erosion. Predicts future changes in this area. (CW)

Estimating genotype error rates from high-coverage next-generation sequence data.

PubMed

Wall, Jeffrey D; Tang, Ling Fung; Zerbe, Brandon; Kvale, Mark N; Kwok, Pui-Yan; Schaefer, Catherine; Risch, Neil

2014-11-01

Exome and whole-genome sequencing studies are becoming increasingly common, but little is known about the accuracy of the genotype calls made by the commonly used platforms. Here we use replicate high-coverage sequencing of blood and saliva DNA samples from four European-American individuals to estimate lower bounds on the error rates of Complete Genomics and Illumina HiSeq whole-genome and whole-exome sequencing. Error rates for nonreference genotype calls range from 0.1% to 0.6%, depending on the platform and the depth of coverage. Additionally, we found (1) no difference in the error profiles or rates between blood and saliva samples; (2) Complete Genomics sequences had substantially higher error rates than Illumina sequences had; (3) error rates were higher (up to 6%) for rare or unique variants; (4) error rates generally declined with genotype quality (GQ) score, but in a nonlinear fashion for the Illumina data, likely due to loss of specificity of GQ scores greater than 60; and (5) error rates increased with increasing depth of coverage for the Illumina data. These findings, especially (3)-(5), suggest that caution should be taken in interpreting the results of next-generation sequencing-based association studies, and even more so in clinical application of this technology in the absence of validation by other more robust sequencing or genotyping methods. © 2014 Wall et al.; Published by Cold Spring Harbor Laboratory Press.

Application of spatial and non-spatial data analysis in determination of the factors that impact municipal solid waste generation rates in Turkey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keser, Saniye; Duzgun, Sebnem; Department of Geodetic and Geographic Information Technologies, Middle East Technical University, 06800 Ankara

Highlights: Black-Right-Pointing-Pointer Spatial autocorrelation exists in municipal solid waste generation rates for different provinces in Turkey. Black-Right-Pointing-Pointer Traditional non-spatial regression models may not provide sufficient information for better solid waste management. Black-Right-Pointing-Pointer Unemployment rate is a global variable that significantly impacts the waste generation rates in Turkey. Black-Right-Pointing-Pointer Significances of global parameters may diminish at local scale for some provinces. Black-Right-Pointing-Pointer GWR model can be used to create clusters of cities for solid waste management. - Abstract: In studies focusing on the factors that impact solid waste generation habits and rates, the potential spatial dependency in solid waste generation datamore » is not considered in relating the waste generation rates to its determinants. In this study, spatial dependency is taken into account in determination of the significant socio-economic and climatic factors that may be of importance for the municipal solid waste (MSW) generation rates in different provinces of Turkey. Simultaneous spatial autoregression (SAR) and geographically weighted regression (GWR) models are used for the spatial data analyses. Similar to ordinary least squares regression (OLSR), regression coefficients are global in SAR model. In other words, the effect of a given independent variable on a dependent variable is valid for the whole country. Unlike OLSR or SAR, GWR reveals the local impact of a given factor (or independent variable) on the waste generation rates of different provinces. Results show that provinces within closer neighborhoods have similar MSW generation rates. On the other hand, this spatial autocorrelation is not very high for the exploratory variables considered in the study. OLSR and SAR models have similar regression coefficients. GWR is useful to indicate the local determinants of MSW generation rates. GWR model can be

Four-amplitude shift keying-single sideband millimeter-wave signal generation with frequency sextupling based on optical phase modulation

NASA Astrophysics Data System (ADS)

Wu, Peng; Ma, Jianxin

2017-03-01

We have proposed and demonstrated a scheme to generate a frequency-sextupling amplitude shift keying (ASK)-single sideband optical millimeter (mm)-wave signal with high dispersion tolerance based on an optical phase modulator (PM) by ably using the-4th-order and +2nd-order sidebands of the optical modulation. The ASK radio frequency signal, superposed by a local oscillator with the same frequency, modulates the lightwave via an optical PM with proper voltage amplitudes, the +2nd-order sideband carries the ASK signal with a constant slope while the -4th-order sideband maintains constant amplitude. These two sidebands can be abstracted by a wavelength selective switch to form a dual-tone optical mm-wave with only one tone carrying the ASK signal. As only one tone bears the ASK signal while the other tone is unmodulated, the generated dual-tone optical mm-wave signal has high dispersion tolerance.

Source-Independent Quantum Random Number Generation

NASA Astrophysics Data System (ADS)

Cao, Zhu; Zhou, Hongyi; Yuan, Xiao; Ma, Xiongfeng

2016-01-01

Quantum random number generators can provide genuine randomness by appealing to the fundamental principles of quantum mechanics. In general, a physical generator contains two parts—a randomness source and its readout. The source is essential to the quality of the resulting random numbers; hence, it needs to be carefully calibrated and modeled to achieve information-theoretical provable randomness. However, in practice, the source is a complicated physical system, such as a light source or an atomic ensemble, and any deviations in the real-life implementation from the theoretical model may affect the randomness of the output. To close this gap, we propose a source-independent scheme for quantum random number generation in which output randomness can be certified, even when the source is uncharacterized and untrusted. In our randomness analysis, we make no assumptions about the dimension of the source. For instance, multiphoton emissions are allowed in optical implementations. Our analysis takes into account the finite-key effect with the composable security definition. In the limit of large data size, the length of the input random seed is exponentially small compared to that of the output random bit. In addition, by modifying a quantum key distribution system, we experimentally demonstrate our scheme and achieve a randomness generation rate of over 5 ×103 bit /s .

Cryptographic robustness of practical quantum cryptography: BB84 key distribution protocol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molotkov, S. N.

2008-07-15

In real fiber-optic quantum cryptography systems, the avalanche photodiodes are not perfect, the source of quantum states is not a single-photon one, and the communication channel is lossy. For these reasons, key distribution is impossible under certain conditions for the system parameters. A simple analysis is performed to find relations between the parameters of real cryptography systems and the length of the quantum channel that guarantee secure quantum key distribution when the eavesdropper's capabilities are limited only by fundamental laws of quantum mechanics while the devices employed by the legitimate users are based on current technologies. Critical values are determinedmore » for the rate of secure real-time key generation that can be reached under the current technology level. Calculations show that the upper bound on channel length can be as high as 300 km for imperfect photodetectors (avalanche photodiodes) with present-day quantum efficiency ({eta} {approx} 20%) and dark count probability (p{sub dark} {approx} 10{sup -7})« less

Cryptographic robustness of practical quantum cryptography: BB84 key distribution protocol

NASA Astrophysics Data System (ADS)

Molotkov, S. N.

2008-07-01

In real fiber-optic quantum cryptography systems, the avalanche photodiodes are not perfect, the source of quantum states is not a single-photon one, and the communication channel is lossy. For these reasons, key distribution is impossible under certain conditions for the system parameters. A simple analysis is performed to find relations between the parameters of real cryptography systems and the length of the quantum channel that guarantee secure quantum key distribution when the eavesdropper’s capabilities are limited only by fundamental laws of quantum mechanics while the devices employed by the legitimate users are based on current technologies. Critical values are determined for the rate of secure real-time key generation that can be reached under the current technology level. Calculations show that the upper bound on channel length can be as high as 300 km for imperfect photodetectors (avalanche photodiodes) with present-day quantum efficiency (η ≈ 20%) and dark count probability ( p dark ˜ 10-7).

Enhanced diffie-hellman algorithm for reliable key exchange

NASA Astrophysics Data System (ADS)

Aryan; Kumar, Chaithanya; Vincent, P. M. Durai Raj

2017-11-01

The Diffie -Hellman is one of the first public-key procedure and is a certain way of exchanging the cryptographic keys securely. This concept was introduced by Ralph Markel and it is named after Whitfield Diffie and Martin Hellman. Sender and Receiver make a common secret key in Diffie-Hellman algorithm and then they start communicating with each other over the public channel which is known to everyone. A number of internet services are secured by Diffie -Hellman. In Public key cryptosystem, the sender has to trust while receiving the public key of the receiver and vice-versa and this is the challenge of public key cryptosystem. Man-in-the-Middle attack is very much possible on the existing Diffie-Hellman algorithm. In man-in-the-middle attack, the attacker exists in the public channel, the attacker receives the public key of both sender and receiver and sends public keys to sender and receiver which is generated by his own. This is how man-in-the-middle attack is possible on Diffie-Hellman algorithm. Denial of service attack is another attack which is found common on Diffie-Hellman. In this attack, the attacker tries to stop the communication happening between sender and receiver and attacker can do this by deleting messages or by confusing the parties with miscommunication. Some more attacks like Insider attack, Outsider attack, etc are possible on Diffie-Hellman. To reduce the possibility of attacks on Diffie-Hellman algorithm, we have enhanced the Diffie-Hellman algorithm to a next level. In this paper, we are extending the Diffie -Hellman algorithm by using the concept of the Diffie -Hellman algorithm to get a stronger secret key and that secret key is further exchanged between the sender and the receiver so that for each message, a new secret shared key would be generated. The second secret key will be generated by taking primitive root of the first secret key.

Estimate Of The Decay Rate Constant of Hydrogen Sulfide Generation From Landfilled Drywall

EPA Science Inventory

Research was conducted to investigate the impact of particle size on H2S gas emissions and estimate a decay rate constant for H2S gas generation from the anaerobic decomposition of drywall. Three different particle sizes of regular drywall and one particle size of paperless drywa...

Experimental study on trace chemical contaminant generation rates of human metabolism in spacecraft crew module

NASA Astrophysics Data System (ADS)

Lihua, Guo; Xinxing, He; Guoxin, Xu; Xin, Qi

2012-12-01

Trace chemical contaminants generated by human metabolism is a major source of contamination in spacecraft crew module. In this research, types and generation rates of pollutants from human metabolism were determined in the Chinese diets. Expired air, skin gas, and sweat of 20 subjects were analyzed at different exercise states in a simulated module. The exercise states were designed according to the basic activities in the orbit of astronauts. Qualitative and quantitative analyses of contaminants generated by human metabolic were performed with gas chromatography/mass spectrometry, gas chromatography and UV spectrophotometer. Sixteen chemical compounds from metabolic sources were found. With the increase in physical load, the concentrations of chemical compounds from human skin and expired air correspondingly increased. The species and the offgassing rates of pollutants from human metabolism are different among the Chinese, Americans and the Russians due to differences in ethnicity and dietary customs. This research provides data to aid in the design, development and operation of China's long duration space mission.

Encryption key distribution via chaos synchronization

NASA Astrophysics Data System (ADS)

Keuninckx, Lars; Soriano, Miguel C.; Fischer, Ingo; Mirasso, Claudio R.; Nguimdo, Romain M.; van der Sande, Guy

2017-02-01

We present a novel encryption scheme, wherein an encryption key is generated by two distant complex nonlinear units, forced into synchronization by a chaotic driver. The concept is sufficiently generic to be implemented on either photonic, optoelectronic or electronic platforms. The method for generating the key bitstream from the chaotic signals is reconfigurable. Although derived from a deterministic process, the obtained bit series fulfill the randomness conditions as defined by the National Institute of Standards test suite. We demonstrate the feasibility of our concept on an electronic delay oscillator circuit and test the robustness against attacks using a state-of-the-art system identification method.

Encryption key distribution via chaos synchronization

PubMed Central

Keuninckx, Lars; Soriano, Miguel C.; Fischer, Ingo; Mirasso, Claudio R.; Nguimdo, Romain M.; Van der Sande, Guy

2017-01-01

We present a novel encryption scheme, wherein an encryption key is generated by two distant complex nonlinear units, forced into synchronization by a chaotic driver. The concept is sufficiently generic to be implemented on either photonic, optoelectronic or electronic platforms. The method for generating the key bitstream from the chaotic signals is reconfigurable. Although derived from a deterministic process, the obtained bit series fulfill the randomness conditions as defined by the National Institute of Standards test suite. We demonstrate the feasibility of our concept on an electronic delay oscillator circuit and test the robustness against attacks using a state-of-the-art system identification method. PMID:28233876

NEMA count-rate evaluation of the first and second generation of the Ecat Exact and Ecat Exact HR family of scanners

NASA Astrophysics Data System (ADS)

Eriksson, L.; Wienhard, K.; Eriksson, M.; Casey, M. E.; Knoess, C.; Bruckbauer, T.; Hamill, J.; Mulnix, T.; Vollmar, S.; Bendriem, B.; Heiss, W. D.; Nutt, R.

2002-06-01

The first and second generation of the Exact and Exact HR family of scanners has been evaluated in terms of noise equivalent count rate (NEC) and count-rate capabilities. The new National Electrical Manufacturers Association standard was used for the evaluation. In spite of improved electronics and improved count-rate capabilities, the peak NEC was found to be fairly constant between the generations. The results are discussed in terms of the different electronic solutions for the two generations and its implications on system dead time and NEC count-rate capability.

Broadly tunable, low timing jitter, high repetition rate optoelectronic comb generator

PubMed Central

Metcalf, A. J.; Quinlan, F.; Fortier, T. M.; Diddams, S. A.; Weiner, A. M.

2016-01-01

We investigate the low timing jitter properties of a tunable single-pass optoelectronic frequency comb generator. The scheme is flexible in that both the repetition rate and center frequency can be continuously tuned. When operated with 10 GHz comb spacing, the integrated residual pulse-to-pulse timing jitter is 11.35 fs (1 Hz to 10 MHz) with no feedback stabilization. The corresponding phase noise at 1 Hz offset from the photodetected 10 GHz carrier is −100 dBc/Hz. PMID:26865734

Academic Primer Series: Five Key Papers for Consulting Clinician Educators.

PubMed

Chan, Teresa M; Gottlieb, Michael; Quinn, Antonia; London, Kory; Conlon, Lauren W; Ankel, Felix

2017-02-01

Clinician educators are often asked to perform consultations for colleagues. Invitations to consult and advise others on local problems can help foster great collaborations between centers, and allows for an exchange of ideas between programs. In this article, the authors identify and summarize several key papers to assist emerging clinician educators with the consultation process. A consensus-building process was used to generate a list of key papers that describe the importance and significance of educational consulting, informed by social media sources. A three-round voting methodology, akin to a Delphi study, determined the most impactful papers from the larger list. Summaries of the five most highly rated papers on education consultation are presented in this paper. These papers were determined by a mixed group of junior and senior faculty members, who have summarized these papers with respect to their relevance for their peer groups. Five key papers on the educational consultation process are presented in this paper. These papers offer background and perspective to help junior faculty gain a grasp of consultation processes.

Counterfactual quantum key distribution with high efficiency

NASA Astrophysics Data System (ADS)

Sun, Ying; Wen, Qiao-Yan

2010-11-01

In a counterfactual quantum key distribution scheme, a secret key can be generated merely by transmitting the split vacuum pulses of single particles. We improve the efficiency of the first quantum key distribution scheme based on the counterfactual phenomenon. This scheme not only achieves the same security level as the original one but also has higher efficiency. We also analyze how to achieve the optimal efficiency under various conditions.

Counterfactual quantum key distribution with high efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun Ying; Beijing Electronic Science and Technology Institute, Beijing 100070; Wen Qiaoyan

2010-11-15

In a counterfactual quantum key distribution scheme, a secret key can be generated merely by transmitting the split vacuum pulses of single particles. We improve the efficiency of the first quantum key distribution scheme based on the counterfactual phenomenon. This scheme not only achieves the same security level as the original one but also has higher efficiency. We also analyze how to achieve the optimal efficiency under various conditions.

Effect of Finite Chemical Reaction Rates on Heat Transfer to the Walls of Combustion-Driven Supersonic MHD Generator Channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

DAILY, J. W. ..; RAEDER, J.; ZANKL, G.

1974-03-01

The effect of finite-rate homogeneous chemical reactions on the heat transfer rates to the walls of combustion-driven supersonic MHD generators was investigated. Experiments were performed on a 200 kW(e) combustion generator. The density of the heat flux to the wall was measured at various axial positions along both a circular cross section Hall-type channel and a diagonal wall channel with a rectangular cross section. From the results it was concluded that a substantial decrease in heat transfer rate to the walls of a combustion-driven supersonic MHD power generator was ob served which appears to occur because of chemical nonequilibrium inmore » the developing wall boundary layers. (LCL)« less

Bit-rate transparent DPSK demodulation scheme based on injection locking FP-LD

NASA Astrophysics Data System (ADS)

Feng, Hanlin; Xiao, Shilin; Yi, Lilin; Zhou, Zhao; Yang, Pei; Shi, Jie

2013-05-01

We propose and demonstrate a bit-rate transparent differential phase shift-keying (DPSK) demodulation scheme based on injection locking multiple-quantum-well (MQW) strained InGaAsP FP-LD. By utilizing frequency deviation generated by phase modulation and unstable injection locking state with Fabry-Perot laser diode (FP-LD), DPSK to polarization shift-keying (PolSK) and PolSK to intensity modulation (IM) format conversions are realized. We analyze bit error rate (BER) performance of this demodulation scheme. Experimental results show that different longitude modes, bit rates and seeding power have influences on demodulation performance. We achieve error free DPSK signal demodulation under various bit rates of 10 Gbit/s, 5 Gbit/s, 2.5 Gbit/s and 1.25 Gbit/s with the same demodulation setting.

Key role of integrin α(IIb)β (3) signaling to Syk kinase in tissue factor-induced thrombin generation.

PubMed

van der Meijden, Paola E J; Feijge, Marion A H; Swieringa, Frauke; Gilio, Karen; Nergiz-Unal, Reyhan; Hamulyák, Karly; Heemskerk, Johan W M

2012-10-01

The fibrin(ogen) receptor, integrin α(IIb)β(3), has a well-established role in platelet spreading, aggregation and clot retraction. How α(IIb)β(3) contributes to platelet-dependent coagulation is less well resolved. Here, we demonstrate that the potent suppressing effect of clinically used α(IIb)β(3) blockers on tissue factor-induced thrombin generation is linked to diminished platelet Ca(2+) responses and phosphatidylserine (PS) exposure. The same blockers suppress these responses in platelets stimulated with collagen and thrombin receptor agonists, whereas added fibrinogen potentiates these responses. In platelets spreading on fibrinogen, outside-in α(IIb)β(3) signaling similarly enhances thrombin-induced Ca(2+) rises and PS exposure. These responses are reduced in α(IIb)β(3)-deficient platelets from patients with Glanzmann's thrombasthenia. Furthermore, the contribution of α(IIb)β(3) to tissue factor-induced platelet Ca(2+) rises, PS exposure and thrombin generation in plasma are fully dependent on Syk kinase activity. Tyrosine phosphorylation analysis confirms a key role of Syk activation, which is largely but not exclusively dependent on α(IIb)β(3) activation. It is concluded that the majority of tissue factor-induced procoagulant activity of platelets relies on Syk activation and ensuing Ca(2+) signal generation, and furthermore that a considerable part of Syk activation relies on α(IIb)β(3) signaling. These results hence point to a novel role of Syk in integrin-dependent thrombin generation.

Bandwidth scalable, coherent transmitter based on the parallel synthesis of multiple spectral slices using optical arbitrary waveform generation.

PubMed

Geisler, David J; Fontaine, Nicolas K; Scott, Ryan P; He, Tingting; Paraschis, Loukas; Gerstel, Ori; Heritage, Jonathan P; Yoo, S J B

2011-04-25

We demonstrate an optical transmitter based on dynamic optical arbitrary waveform generation (OAWG) which is capable of creating high-bandwidth (THz) data waveforms in any modulation format using the parallel synthesis of multiple coherent spectral slices. As an initial demonstration, the transmitter uses only 5.5 GHz of electrical bandwidth and two 10-GHz-wide spectral slices to create 100-ns duration, 20-GHz optical waveforms in various modulation formats including differential phase-shift keying (DPSK), quaternary phase-shift keying (QPSK), and eight phase-shift keying (8PSK) with only changes in software. The experimentally generated waveforms showed clear eye openings and separated constellation points when measured using a real-time digital coherent receiver. Bit-error-rate (BER) performance analysis resulted in a BER < 9.8 × 10(-6) for DPSK and QPSK waveforms. Additionally, we experimentally demonstrate three-slice, 4-ns long waveforms that highlight the bandwidth scalable nature of the optical transmitter. The various generated waveforms show that the key transmitter properties (i.e., packet length, modulation format, data rate, and modulation filter shape) are software definable, and that the optical transmitter is capable of acting as a flexible bandwidth transmitter.

Estimating spread rates of non-native species: the gypsy moth as a case study

Treesearch

Patrick Tobin; Andrew M. Liebhold; E. Anderson Roberts; Laura M. Blackburn

2015-01-01

Estimating rates of spread and generating projections of future range expansion for invasive alien species is a key process in the development of management guidelines and policy. Critical needs to estimate spread rates include the availability of surveys to characterize the spatial distribution of an invading species and the application of analytical methods to...

Anti-islanding Protection of Distributed Generation Using Rate of Change of Impedance

NASA Astrophysics Data System (ADS)

Shah, Pragnesh; Bhalja, Bhavesh

2013-08-01

Distributed Generation (DG), which is interlinked with distribution system, has inevitable effect on distribution system. Integrating DG with the utility network demands an anti-islanding scheme to protect the system. Failure to trip islanded generators can lead to problems such as threats to personnel safety, out-of-phase reclosing, and degradation of power quality. In this article, a new method for anti-islanding protection based on impedance monitoring of distribution network is carried out in presence of DG. The impedance measured between two phases is used to derive the rate of change of impedance (dz/dt), and its peak values are used for final trip decision. Test data are generated using PSCAD/EMTDC software package and the performance of the proposed method is evaluated in MatLab software. The simulation results show the effectiveness of the proposed scheme as it is capable to detect islanding condition accurately. Subsequently, it is also observed that the proposed scheme does not mal-operate during other disturbances such as short circuit and switching event.

At least some errors are randomly generated (Freud was wrong)

NASA Technical Reports Server (NTRS)

Sellen, A. J.; Senders, J. W.

1986-01-01

An experiment was carried out to expose something about human error generating mechanisms. In the context of the experiment, an error was made when a subject pressed the wrong key on a computer keyboard or pressed no key at all in the time allotted. These might be considered, respectively, errors of substitution and errors of omission. Each of seven subjects saw a sequence of three digital numbers, made an easily learned binary judgement about each, and was to press the appropriate one of two keys. Each session consisted of 1,000 presentations of randomly permuted, fixed numbers broken into 10 blocks of 100. One of two keys should have been pressed within one second of the onset of each stimulus. These data were subjected to statistical analyses in order to probe the nature of the error generating mechanisms. Goodness of fit tests for a Poisson distribution for the number of errors per 50 trial interval and for an exponential distribution of the length of the intervals between errors were carried out. There is evidence for an endogenous mechanism that may best be described as a random error generator. Furthermore, an item analysis of the number of errors produced per stimulus suggests the existence of a second mechanism operating on task driven factors producing exogenous errors. Some errors, at least, are the result of constant probability generating mechanisms with error rate idiosyncratically determined for each subject.

Practical challenges in quantum key distribution

DOE PAGES

Diamanti, Eleni; Lo, Hoi -Kwong; Qi, Bing; ...

2016-11-08

Here, quantum key distribution (QKD) promises unconditional security in data communication and is currently being deployed in commercial applications. Nonetheless, before QKD can be widely adopted, it faces a number of important challenges such as secret key rate, distance, size, cost and practical security. Here, we survey those key challenges and the approaches that are currently being taken to address them.

Practical challenges in quantum key distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diamanti, Eleni; Lo, Hoi -Kwong; Qi, Bing

Here, quantum key distribution (QKD) promises unconditional security in data communication and is currently being deployed in commercial applications. Nonetheless, before QKD can be widely adopted, it faces a number of important challenges such as secret key rate, distance, size, cost and practical security. Here, we survey those key challenges and the approaches that are currently being taken to address them.

Effects of fire intensity on vital rates of an endemic herb of the Florida keys, USA

USGS Publications Warehouse

Liu, H.; Menges, E.S.; Snyder, J.R.; Koptur, S.; Ross, M.S.

2005-01-01

Fire intensity is one of the important components of a fire regime. However, relatively few studies have linked fire intensity with post-fire population vital rates. In this study, we explored the effects of fire intensity on population vital rates of Chamaecrista keyensis Pennell (Fabaceae) up to two years post-fire. C. keyensis is an endemic understory plant of pine rockland, a fire-dependent ecosystem of the Lower Florida Keys. We measured one fire intensity indicator, fire temperature reached by steel plates on the ground, during three prescribed fires at different sites. We followed marked individuals up to two years post-fire to derive annual survival, annual growth rate, percentage of fruiting plants, mean number of fruits per reproductive plant, and number of seedlings per census plot (1 m2) of C. keyensis. We found fire intensity had significant effects on reproduction in the first year post-fire only. More specifically, mean number of fruits and percentage of fruiting plants increased as fire intensity increased. Results from this study suggest that extremely low fire intensity caused by very short fire return intervals (e.g., less than three years) may not provide sufficient stimulation to reproduction to achieve the best post-fire recovery for C. keyensis.

Generating Fast and Accurate Compliance Reports for Various Data Rates

NASA Astrophysics Data System (ADS)

Penugonda, Srinath

As the demands on the industry data rates have increased there is a need for interoperable interfaces to function flawlessly. Added to this complexity, the number of I/O data lines are also increasing making it more time consuming to design and test. This in general leads to creating of compliance standards to which interfaces must adhere. The goal of this theses is to aid the Signal Integrity Engineers with a better and fast way of rendering a full picture of the interface compliance parameters. Three different interfaces at various data rates were chosen. They are: 25Gbps Very Short Reach (VSR) based on Optical Internetworking Forum (OIF), Mobile Industry Processer Interface (MIPI) particularly for camera based on MIPI Alliance organization upto 1.5Gbps and for a passive Universal Serial Bus (USB) Type-C cable based on USB organization particularly for generation-I with data rate of 10Gbps. After a full understanding of each of the interfaces, a complete end-to-end reports for each of the interfaces were developed with an easy to use user interface. A standard one-to-one comparison is done with commercially available software tools for the above mentioned interfaces. The tools were developed in MATLAB and Python. Data was usually obtained by probing at interconnect, from either an oscilloscope or vector network analyzer.

Observations of HF backscatter decay rates from HAARP generated FAI

NASA Astrophysics Data System (ADS)

Bristow, William; Hysell, David

2016-07-01

Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

Observations of HF backscatter decay rates from HAARP generated FAI

NASA Astrophysics Data System (ADS)

Bristow, W. A.; Hysell, D. L.

2016-12-01

Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

Polarization-modulated second harmonic generation ellipsometric microscopy at video rate.

PubMed

DeWalt, Emma L; Sullivan, Shane Z; Schmitt, Paul D; Muir, Ryan D; Simpson, Garth J

2014-08-19

Fast 8 MHz polarization modulation coupled with analytical modeling, fast beam-scanning, and synchronous digitization (SD) have enabled simultaneous nonlinear optical Stokes ellipsometry (NOSE) and polarized laser transmittance imaging with image acquisition rates up to video rate. In contrast to polarimetry, in which the polarization state of the exiting beam is recorded, NOSE enables recovery of the complex-valued Jones tensor of the sample that describes all polarization-dependent observables of the measurement. Every video-rate scan produces a set of 30 images (10 for each detector with three detectors operating in parallel), each of which corresponds to a different polarization-dependent result. Linear fitting of this image set contracts it down to a set of five parameters for each detector in second harmonic generation (SHG) and three parameters for the transmittance of the incident beam. These parameters can in turn be used to recover the Jones tensor elements of the sample. Following validation of the approach using z-cut quartz, NOSE microscopy was performed for microcrystals of both naproxen and glucose isomerase. When weighted by the measurement time, NOSE microscopy was found to provide a substantial (>7 decades) improvement in the signal-to-noise ratio relative to our previous measurements based on the rotation of optical elements and a 3-fold improvement relative to previous single-point NOSE approaches.

Higher Rate of Tuberculosis in Second Generation Migrants Compared to Native Residents in a Metropolitan Setting in Western Europe

PubMed Central

Marx, Florian M.; Fiebig, Lena; Hauer, Barbara; Brodhun, Bonita; Glaser-Paschke, Gisela; Haas, Walter

2015-01-01

Background In Western Europe, migrants constitute an important risk group for tuberculosis, but little is known about successive generations of migrants. We aimed to characterize migration among tuberculosis cases in Berlin and to estimate annual rates of tuberculosis in two subsequent migrant generations. We hypothesized that second generation migrants born in Germany are at higher risk of tuberculosis compared to native (non-migrant) residents. Methods A prospective cross-sectional study was conducted. All tuberculosis cases reported to health authorities in Berlin between 11/2010 and 10/2011 were eligible. Interviews were conducted using a structured questionnaire including demographic data, migration history of patients and their parents, and language use. Tuberculosis rates were estimated using 2011 census data. Results Of 314 tuberculosis cases reported, 154 (49.0%) participated. Of these, 81 (52.6%) were first-, 14 (9.1%) were second generation migrants, and 59 (38.3%) were native residents. The tuberculosis rate per 100,000 individuals was 28.3 (95CI: 24.0–32.6) in first-, 10.2 (95%CI: 6.1–16.6) in second generation migrants, and 4.6 (95%CI: 3.7–5.6) in native residents. When combining information from the standard notification variables country of birth and citizenship, the sensitivity to detect second generation migration was 28.6%. Conclusions There is a higher rate of tuberculosis among second generation migrants compared to native residents in Berlin. This may be explained by presumably frequent contact and transmission within migrant populations. Second generation migration is insufficiently captured by the surveillance variables country of birth and citizenship. Surveillance systems in Western Europe should allow for quantifying the tuberculosis burden in this important risk group. PMID:26061733

Experimental demonstration of subcarrier multiplexed quantum key distribution system.

PubMed

Mora, José; Ruiz-Alba, Antonio; Amaya, Waldimar; Martínez, Alfonso; García-Muñoz, Víctor; Calvo, David; Capmany, José

2012-06-01

We provide, to our knowledge, the first experimental demonstration of the feasibility of sending several parallel keys by exploiting the technique of subcarrier multiplexing (SCM) widely employed in microwave photonics. This approach brings several advantages such as high spectral efficiency compatible with the actual secure key rates, the sharing of the optical fainted pulse by all the quantum multiplexed channels reducing the system complexity, and the possibility of upgrading with wavelength division multiplexing in a two-tier scheme, to increase the number of parallel keys. Two independent quantum SCM channels featuring a sifted key rate of 10 Kb/s/channel over a link with quantum bit error rate <2% is reported.

Efficient neutron generation from solid-nanoparticle explosions driven by DPSSL-pumped high-repetition rate femtosecond laser pulse

NASA Astrophysics Data System (ADS)

Watari, T.; Matsukado, K.; Sekine, T.; Takeuchi, Y.; Hatano, Y.; Yoshimura, R.; Satoh, N.; Nishihara, K.; Takagi, M.; Kawashima, T.

2016-03-01

We propose novel neutron source using high-intensity laser based on the cluster fusion scheme. We developed DPSSL-pumped high-repetition-rate 20-TW laser system and solid nanoparticle target for neutron generation demonstration. In our neutron generation experiment, high-energy deuterons were generated from coulomb explosion of CD solid- nanoparticles and neutrons were generated by DD fusion reaction. Efficient and stable neutron generation was obtained by irradiating an intense femtosecond laser pulse of >2×1018 W/cm2. A yield of ∼105 neutrons per shot was stably observed during 0.1-1 Hz continuous operation.

Calcification rates of the massive coral Siderastrea siderea and crustose coralline algae along the Florida Keys (USA) outer-reef tract

USGS Publications Warehouse

Kuffner, I.B.; Hickey, T.D.; Morrison, J.M.

2013-01-01

Coral reefs are degrading on a global scale, and rates of reef-organism calcification are predicted to decline due to ocean warming and acidification. Systematic measurements of calcification over space and time are necessary to detect change resulting from environmental stressors. We established a network of calcification monitoring stations at four managed reefs along the outer Florida Keys Reef Tract (FKRT) from Miami to the Dry Tortugas. Eighty colonies (in two sequential sets of 40) of the reef-building coral, Siderastrea siderea, were transplanted to fixed apparatus that allowed repetitive detachment for buoyant weighing every 6 months. Algal-recruitment tiles were also deployed during each weighing interval to measure net calcification of the crustose coralline algal (CCA) community. Coral-calcification rates were an order of magnitude greater than those of CCA. Rates of coral calcification were seasonal (summer calcification was 53% greater than winter), and corals in the Dry Tortugas calcified 48% faster than those at the other three sites. Linear extension rates were also highest in the Dry Tortugas, whereas percent area of the coral skeletons excavated by bioeroding fauna was lowest. The spatial patterns in net coral calcification revealed here correlate well with Holocene reef thickness along the FKRT and, in part, support the “inimical waters hypothesis” proposed by Ginsburg, Hudson, and Shinn almost 50 yrs ago to explain reef development in this region. Due to the homogeneity in coral-calcification rates among the three main Keys sites, we recommend refinement of this hypothesis and suggest that water-quality variables (e.g., carbonate mineral saturation state, dissolved and particulate organic matter, light attenuation) be monitored alongside calcification in future studies. Our results demonstrate that our calcification monitoring network presents a feasible and worthwhile approach to quantifying potential impacts of ocean acidification

Calcification rates of the massive coral Siderastrea siderea and crustose coralline algae along the Florida Keys (USA) outer-reef tract

NASA Astrophysics Data System (ADS)

Kuffner, I. B.; Hickey, T. D.; Morrison, J. M.

2013-12-01

Coral reefs are degrading on a global scale, and rates of reef-organism calcification are predicted to decline due to ocean warming and acidification. Systematic measurements of calcification over space and time are necessary to detect change resulting from environmental stressors. We established a network of calcification monitoring stations at four managed reefs along the outer Florida Keys Reef Tract (FKRT) from Miami to the Dry Tortugas. Eighty colonies (in two sequential sets of 40) of the reef-building coral, Siderastrea siderea, were transplanted to fixed apparatus that allowed repetitive detachment for buoyant weighing every 6 months. Algal-recruitment tiles were also deployed during each weighing interval to measure net calcification of the crustose coralline algal (CCA) community. Coral-calcification rates were an order of magnitude greater than those of CCA. Rates of coral calcification were seasonal (summer calcification was 53 % greater than winter), and corals in the Dry Tortugas calcified 48 % faster than those at the other three sites. Linear extension rates were also highest in the Dry Tortugas, whereas percent area of the coral skeletons excavated by bioeroding fauna was lowest. The spatial patterns in net coral calcification revealed here correlate well with Holocene reef thickness along the FKRT and, in part, support the "inimical waters hypothesis" proposed by Ginsburg, Hudson, and Shinn almost 50 yrs ago to explain reef development in this region. Due to the homogeneity in coral-calcification rates among the three main Keys sites, we recommend refinement of this hypothesis and suggest that water-quality variables (e.g., carbonate mineral saturation state, dissolved and particulate organic matter, light attenuation) be monitored alongside calcification in future studies. Our results demonstrate that our calcification monitoring network presents a feasible and worthwhile approach to quantifying potential impacts of ocean acidification, warming

The F-16 Onboard Oxygen Generating System: Performance Evaluation and Man Rating

DTIC Science & Technology

1983-08-01

OXYGEN GENERATING , YSTEM: PERFORMANCE EVALUATION AND MAN RATING Thomas C. Horch , Captain, USAF Richard L. Miller, Ph.D. John B. Bomar, Jr...C. Horch , Capt, USAF; R. L. Miller, 8. CONTRACT OR GRANT NUMBER(i) Ph.D.; J. B. Bomar, Jr., Lt Col, IJSAF, BSC; J. B. Tedor, Maj, USAF, BSC; R. D...limitation (as of 1983); however, the information may no longer need protection since it is 14 years. At the time of its publication, Capt Thomas Horch

Bit error rate tester using fast parallel generation of linear recurring sequences

DOEpatents

Pierson, Lyndon G.; Witzke, Edward L.; Maestas, Joseph H.

2003-05-06

A fast method for generating linear recurring sequences by parallel linear recurring sequence generators (LRSGs) with a feedback circuit optimized to balance minimum propagation delay against maximal sequence period. Parallel generation of linear recurring sequences requires decimating the sequence (creating small contiguous sections of the sequence in each LRSG). A companion matrix form is selected depending on whether the LFSR is right-shifting or left-shifting. The companion matrix is completed by selecting a primitive irreducible polynomial with 1's most closely grouped in a corner of the companion matrix. A decimation matrix is created by raising the companion matrix to the (n*k).sup.th power, where k is the number of parallel LRSGs and n is the number of bits to be generated at a time by each LRSG. Companion matrices with 1's closely grouped in a corner will yield sparse decimation matrices. A feedback circuit comprised of XOR logic gates implements the decimation matrix in hardware. Sparse decimation matrices can be implemented with minimum number of XOR gates, and therefore a minimum propagation delay through the feedback circuit. The LRSG of the invention is particularly well suited to use as a bit error rate tester on high speed communication lines because it permits the receiver to synchronize to the transmitted pattern within 2n bits.

Pulse Generator Exchange Does Not Accelerate the Rate of Electrical Failure in a Recalled Small Caliber ICD Lead.

PubMed

Lovelock, Joshua D; Premkumar, Ajay; Levy, Mathew R; Mengistu, Andenet; Hoskins, Michael H; El-Chami, Mikhael F; Lloyd, Michael S; Leon, Angel R; Langberg, Jonathan J; Delurgio, David B

2015-12-01

St. Jude Riata/Riata ST defibrillator leads (St. Jude Medical, Sylmar, CA, USA) were recalled by the Food and Drug Administration in 2011 for an increased rate of failure. More than 227,000 leads were implanted and at least 79,000 patients still have active Riata leads. Studies have examined clinical predictors of lead failure in Riata leads, but none have addressed the effect of implantable cardioverter defibrillator (ICD) generator exchange on lead failure. The purpose of this study is to assess the effect of ICD generator exchange on the rate of electrical failure in the Riata lead at 1 year. A retrospective chart review was conducted in patients who underwent implantation of a Riata/Riata ST lead at one center. Patients with a functioning Riata lead (with/without externalized conductor) at the time of ICD exchange were compared to controls with Riata leads implanted for a comparable amount of time who did not undergo generator replacement. Riata leads were implanted in 1,042 patients prior to the recall and 153 of these patients underwent generator exchange without lead replacement. Conductor externalization was noted in 21.5% of Riata leads in the ICD exchange cohort, which was not different from the control group (19.2%; P = 0.32). Two leads failed in the first year after generator replacement (1.5%) which did not significantly differ from the control group (2.0%; P = 0.57). At change-out, 54% received a commanded shock (18.6 ± 0.9 J) that did not result in any change in the high-voltage lead impedance (46.1 ± 1.1 ohms). Conductor externalization was seen frequently in our cohort of patients. ICD generator exchange did not accelerate the rate of Riata lead failure at 1 year. Although both the control and the change-out cohorts failed at a rate much greater than nonrecalled leads, generator exchange did not appear to add to the problem. ©2015 Wiley Periodicals, Inc.

Is population structure sufficient to generate area-level inequalities in influenza rates? An examination using agent-based models.

PubMed

Kumar, Supriya; Piper, Kaitlin; Galloway, David D; Hadler, James L; Grefenstette, John J

2015-09-23

In New Haven County, CT (NHC), influenza hospitalization rates have been shown to increase with census tract poverty in multiple influenza seasons. Though multiple factors have been hypothesized to cause these inequalities, including population structure, differential vaccine uptake, and differential access to healthcare, the impact of each in generating observed inequalities remains unknown. We can design interventions targeting factors with the greatest explanatory power if we quantify the proportion of observed inequalities that hypothesized factors are able to generate. Here, we ask if population structure is sufficient to generate the observed area-level inequalities in NHC. To our knowledge, this is the first use of simulation models to examine the causes of differential poverty-related influenza rates. Using agent-based models with a census-informed, realistic representation of household size, age-structure, population density in NHC census tracts, and contact rates in workplaces, schools, households, and neighborhoods, we measured poverty-related differential influenza attack rates over the course of an epidemic with a 23 % overall clinical attack rate. We examined the role of asthma prevalence rates as well as individual contact rates and infection susceptibility in generating observed area-level influenza inequalities. Simulated attack rates (AR) among adults increased with census tract poverty level (F = 30.5; P < 0.001) in an epidemic caused by a virus similar to A (H1N1) pdm09. We detected a steeper, earlier influenza rate increase in high-poverty census tracts-a finding that we corroborate with a temporal analysis of NHC surveillance data during the 2009 H1N1 pandemic. The ratio of the simulated adult AR in the highest- to lowest-poverty tracts was 33 % of the ratio observed in surveillance data. Increasing individual contact rates in the neighborhood did not increase simulated area-level inequalities. When we modified individual

Electron-hole pairs generation rate estimation irradiated by isotope Nickel-63 in silicone using GEANT4

NASA Astrophysics Data System (ADS)

Kovalev, I. V.; Sidorov, V. G.; Zelenkov, P. V.; Khoroshko, A. Y.; Lelekov, A. T.

2015-10-01

To optimize parameters of beta-electrical converter of isotope Nickel-63 radiation, model of the distribution of EHP generation rate in semiconductor must be derived. By using Monte-Carlo methods in GEANT4 system with ultra-low energy electron physics models this distribution in silicon calculated and approximated with Gauss function. Maximal efficient isotope layer thickness and maximal energy efficiency of EHP generation were estimated.

Automated secured cost effective key refreshing technique to enhance WiMAX privacy key management

NASA Astrophysics Data System (ADS)

Sridevi, B.; Sivaranjani, S.; Rajaram, S.

2013-01-01

In all walks of life the way of communication is transformed by the rapid growth of wireless communication and its pervasive use. A wireless network which is fixed and richer in bandwidth is specified as IEEE 802.16, promoted and launched by an industrial forum is termed as Worldwide Interoperability for Microwave Access (WiMAX). This technology enables seamless delivery of wireless broadband service for fixed and/or mobile users. The obscurity is the long delay which occurs during the handoff management in every network. Mobile WiMAX employs an authenticated key management protocol as a part of handoff management in which the Base Station (BS) controls the distribution of keying material to the Mobile Station (MS). The protocol employed is Privacy Key Management Version 2- Extensible Authentication Protocol (PKMV2-EAP) which is responsible for the normal and periodical authorization of MSs, reauthorization as well as key refreshing. Authorization key (AK) and Traffic Encryption key (TEK) plays a vital role in key exchange. When the lifetime of key expires, MS has to request for a new key to BS which in turn leads to repetition of authorization, authentication as well as key exchange. To avoid service interruption during reauthorization , two active keys are transmitted at the same time by BS to MS. The consequences of existing work are hefty amount of bandwidth utilization, time consumption and large storage. It is also endured by Man in the Middle attack and Impersonation due to lack of security in key exchange. This paper designs an automatic mutual refreshing of keys to minimize bandwidth utilization, key storage and time consumption by proposing Previous key and Iteration based Key Refreshing Function (PKIBKRF). By integrating PKIBKRF in key generation, the simulation results indicate that 21.8% of the bandwidth and storage of keys are reduced and PKMV2 mutual authentication time is reduced by 66.67%. The proposed work is simulated with Qualnet model and

Disparities in self-rated health across generations and through the life course.

PubMed

Link, Bruce G; Susser, Ezra S; Factor-Litvak, Pam; March, Dana; Kezios, Katrina L; Lovasi, Gina S; Rundle, Andrew G; Suglia, Shakira F; Fader, Kim M; Andrews, Howard F; Johnson, Eileen; Cirillo, Piera M; Cohn, Barbara A

2017-02-01

Extensive evidence leads us to expect that health disparities by race and socioeconomic status found in one generation might be reproduced in the next. To the extent that this occurs it is important to assess life course processes responsible for the reproduction. Prospective evidence concerning such life course processes is hard to come by as it requires long-term follow-up of individuals from childhood through adult life. We present data from the Child Health and Development Disparities study that provides evidence relevant to this issue with respect to self-rated health. Mothers and offspring recruited in California's Bay Area between 1959 and 1967 were assessed during pregnancy with follow-up exams of offspring along with in-person interviews with mothers (at offspring ages 5, 9-11, 15-17) and offspring (at ages 15-17, ∼50). Available data allow us to assess the importance of three potential life course pathways in the reproduction of inequalities in self-rated health - socioeconomic pathways, cognitive pathways and pathways involving emerging health itself. As expected we found that race and SES disparities in SRH are reproduced across generations. They are evident in mothers, not strong or significant in offspring at 15-17, but present once again in offspring at age ∼50. Concerning potential pathways, we found that indicators of child health were related to adult SRH and played some role in accounting for race but not SES disparities in adult SRH. Cognitive abilities were unrelated to adult SRH with childhood SES controlled. Childhood SES was associated with adult SRH independent of other childhood factors and is reduced to non-significance only when offspring college attainment is controlled. Race and SES disparities in self-reported health in one generation are re-expressed in the next with strongest support for SES pathways in this transmission. Copyright © 2016 Elsevier Ltd. All rights reserved.

Disparities in self-rated health across generations and through the life course

PubMed Central

Link, Bruce G.; Susser, Ezra S.; Factor-Litvak, Pam; March, Dana; Kezios, Katrina L.; Lovasi, Gina S.; Rundle, Andrew G.; Suglia, Shakira F.; Fader, Kim M.; Andrews, Howard F.; Johnson, Eileen; Cirillo, Piera M.; Cohn, Barbara A.

2017-01-01

Extensive evidence leads us to expect that health disparities by race and socioeconomic status found in one generation might be reproduced in the next. To the extent that this occurs it is important to assess life course processes responsible for the reproduction. Prospective evidence concerning such life course processes is hard to come by as it requires long-term follow-up of individuals from childhood through adult life. We present data from the Child Health and Development Disparities study that provides evidence relevant to this issue with respect to self-rated health. Mothers and offspring recruited in California's Bay Area between 1959 and 1967 were assessed during pregnancy with follow-up exams of offspring along with in-person interviews with mothers (at offspring ages 5, 9–11, 15–17) and offspring (at ages 15–17, ~50). Available data allow us to assess the importance of three potential life course pathways in the reproduction of inequalities in self-rated health – socioeconomic pathways, cognitive pathways and pathways involving emerging health itself. As expected we found that race and SES disparities in SRH are reproduced across generations. They are evident in mothers, not strong or significant in offspring at 15–17, but present once again in offspring at age ~50. Concerning potential pathways, we found that indicators of child health were related to adult SRH and played some role in accounting for race but not SES disparities in adult SRH. Cognitive abilities were unrelated to adult SRH with childhood SES controlled. Childhood SES was associated with adult SRH independent of other childhood factors and is reduced to non-significance only when offspring college attainment is controlled. Race and SES disparities in self-reported health in one generation are re-expressed in the next with strongest support for SES pathways in this transmission. PMID:27987434

High-speed continuous-variable quantum key distribution without sending a local oscillator.

PubMed

Huang, Duan; Huang, Peng; Lin, Dakai; Wang, Chao; Zeng, Guihua

2015-08-15

We report a 100-MHz continuous-variable quantum key distribution (CV-QKD) experiment over a 25-km fiber channel without sending a local oscillator (LO). We use a "locally" generated LO and implement with a 1-GHz shot-noise-limited homodyne detector to achieve high-speed quantum measurement, and we propose a secure phase compensation scheme to maintain a low level of excess noise. These make high-bit-rate CV-QKD significantly simpler for larger transmission distances compared with previous schemes in which both LO and quantum signals are transmitted through the insecure quantum channel.

Oxygen Mass Flow Rate Generated for Monitoring Hydrogen Peroxide Stability

NASA Technical Reports Server (NTRS)

Ross, H. Richard

2002-01-01

Recent interest in propellants with non-toxic reaction products has led to a resurgence of interest in hydrogen peroxide for various propellant applications. Because peroxide is sensitive to contaminants, material interactions, stability and storage issues, monitoring decomposition rates is important. Stennis Space Center (SSC) uses thermocouples to monitor bulk fluid temperature (heat evolution) to determine reaction rates. Unfortunately, large temperature rises are required to offset the heat lost into the surrounding fluid. Also, tank penetration to accomodate a thermocouple can entail modification of a tank or line and act as a source of contamination. The paper evaluates a method for monitoring oxygen evolution as a means to determine peroxide stability. Oxygen generation is not only directly related to peroxide decomposition, but occurs immediately. Measuring peroxide temperature to monitor peroxide stability has significant limitations. The bulk decomposition of 1% / week in a large volume tank can produce in excess of 30 cc / min. This oxygen flow rate corresponds to an equivalent temperature rise of approximately 14 millidegrees C, which is difficult to measure reliably. Thus, if heat transfer were included, there would be no temperature rise. Temperature changes from the surrounding environment and heat lost to the peroxide will also mask potential problems. The use of oxygen flow measurements provides an ultra sensitive technique for monitoring reaction events and will provide an earlier indication of an abnormal decomposition when compared to measuring temperature rise.

Limitations on quantum key repeaters.

PubMed

Bäuml, Stefan; Christandl, Matthias; Horodecki, Karol; Winter, Andreas

2015-04-23

A major application of quantum communication is the distribution of entangled particles for use in quantum key distribution. Owing to noise in the communication line, quantum key distribution is, in practice, limited to a distance of a few hundred kilometres, and can only be extended to longer distances by use of a quantum repeater, a device that performs entanglement distillation and quantum teleportation. The existence of noisy entangled states that are undistillable but nevertheless useful for quantum key distribution raises the question of the feasibility of a quantum key repeater, which would work beyond the limits of entanglement distillation, hence possibly tolerating higher noise levels than existing protocols. Here we exhibit fundamental limits on such a device in the form of bounds on the rate at which it may extract secure key. As a consequence, we give examples of states suitable for quantum key distribution but unsuitable for the most general quantum key repeater protocol.

Coherent one-way quantum key distribution

NASA Astrophysics Data System (ADS)

Stucki, Damien; Fasel, Sylvain; Gisin, Nicolas; Thoma, Yann; Zbinden, Hugo

2007-05-01

Quantum Key Distribution (QKD) consists in the exchange of a secrete key between two distant points [1]. Even if quantum key distribution systems exist and commercial systems are reaching the market [2], there are still improvements to be made: simplify the construction of the system; increase the secret key rate. To this end, we present a new protocol for QKD tailored to work with weak coherent pulses and at high bit rates [3]. The advantages of this system are that the setup is experimentally simple and it is tolerant to reduced interference visibility and to photon number splitting attacks, thus resulting in a high efficiency in terms of distilled secret bits per qubit. After having successfully tested the feasibility of the system [3], we are currently developing a fully integrated and automated prototype within the SECOQC project [4]. We present the latest results using the prototype. We also discuss the issue of the photon detection, which still remains the bottleneck for QKD.

Conversion and matched filter approximations for serial minimum-shift keyed modulation

NASA Technical Reports Server (NTRS)

Ziemer, R. E.; Ryan, C. R.; Stilwell, J. H.

1982-01-01

Serial minimum-shift keyed (MSK) modulation, a technique for generating and detecting MSK using series filtering, is ideally suited for high data rate applications provided the required conversion and matched filters can be closely approximated. Low-pass implementations of these filters as parallel inphase- and quadrature-mixer structures are characterized in this paper in terms of signal-to-noise ratio (SNR) degradation from ideal and envelope deviation. Several hardware implementation techniques utilizing microwave devices or lumped elements are presented. Optimization of parameter values results in realizations whose SNR degradation is less than 0.5 dB at error probabilities of .000001.

Concurrent Phosphorus Recovery and Energy Generation in Mediator-Less Dual Chamber Microbial Fuel Cells: Mechanisms and Influencing Factors

PubMed Central

Almatouq, Abdullah; Babatunde, Akintunde O.

2016-01-01

This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD), pH, oxidation reduction potential (ORP) and aeration flow rate showed that a maximum 38% P recovery was achieved; and this corresponds to 1.5 g/L, pH > 8, −550 ± 10 mV and 50 mL/min respectively, for COD, pHcathode, ORP and cathode aeration flow rate. More importantly, COD and aeration flow rate were shown to be the key influencing factors for the P recovery and energy generation. Results further show that the maximum P recovery corresponds to 72 mW/m2 power density. However, the energy generated at maximum P recovery was not the optimum; this shows that whilst P recovery and energy generation can be concurrently achieved in a microbial fuel cell, neither can be at the optimal value. PMID:27043584

Concurrent Phosphorus Recovery and Energy Generation in Mediator-Less Dual Chamber Microbial Fuel Cells: Mechanisms and Influencing Factors.

PubMed

Almatouq, Abdullah; Babatunde, Akintunde O

2016-03-29

This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD), pH, oxidation reduction potential (ORP) and aeration flow rate showed that a maximum 38% P recovery was achieved; and this corresponds to 1.5 g/L, pH > 8, -550 ± 10 mV and 50 mL/min respectively, for COD, pH(cathode), ORP and cathode aeration flow rate. More importantly, COD and aeration flow rate were shown to be the key influencing factors for the P recovery and energy generation. Results further show that the maximum P recovery corresponds to 72 mW/m² power density. However, the energy generated at maximum P recovery was not the optimum; this shows that whilst P recovery and energy generation can be concurrently achieved in a microbial fuel cell, neither can be at the optimal value.

Nanobubbles: An Effective Way to Study Gas-Generating Catalysis on a Single Nanoparticle.

PubMed

Li, Shuping; Du, Ying; He, Ting; Shen, Yangbin; Bai, Chuang; Ning, Fandi; Hu, Xin; Wang, Wenhui; Xi, Shaobo; Zhou, Xiaochun

2017-10-11

Gas-generating catalysis is important to many energy-related research fields, such as photocatalytic water splitting, water electrolysis, etc. The technique of single-nanoparticle catalysis is an effective way to search for highly active nanocatalysts and elucidate the reaction mechanism. However, gas-generating catalysis remains difficult to investigate at the single-nanoparticle level because product gases, such as H 2 and O 2 , are difficult to detect on an individual nanoparticle. Here, we successfully find that nanobubbles can be used to study the gas-generating catalysis, i.e., H 2 generation from formic acid dehydrogenation on a single Pd-Ag nanoplate, with a high time resolution (50 ms) via dark-field microscopy. The research reveals that the nanobubble evolution process includes nucleation time and lifetime. The nucleation rate of nanobubbles is proportional to the catalytic activity of a single nanocatalyst. The relationship between the catalytic activity and the nucleation rate is quantitatively described by a mathematical model, which shows that an onset reaction rate (r onset ) exists for the generation of nanobubbles on a single Pd-Ag nanoplate. The research also reveals that a Pd-Ag nanoplate with larger size usually has a higher activity. However, some large-sized ones still have low activities, indicating the size of the Pd-Ag nanoplate is not the only key factor for the activity. Notablely, further research shows that Pd content is the key factor for the activity of single Pd-Ag nanoplates with similar size. The methodology and knowledge acquired from this research are also applicable to other important gas-generating catalysis reactions at the single-nanoparticle level.

Security of quantum key distribution with multiphoton components

PubMed Central

Yin, Hua-Lei; Fu, Yao; Mao, Yingqiu; Chen, Zeng-Bing

2016-01-01

Most qubit-based quantum key distribution (QKD) protocols extract the secure key merely from single-photon component of the attenuated lasers. However, with the Scarani-Acin-Ribordy-Gisin 2004 (SARG04) QKD protocol, the unconditionally secure key can be extracted from the two-photon component by modifying the classical post-processing procedure in the BB84 protocol. Employing the merits of SARG04 QKD protocol and six-state preparation, one can extract secure key from the components of single photon up to four photons. In this paper, we provide the exact relations between the secure key rate and the bit error rate in a six-state SARG04 protocol with single-photon, two-photon, three-photon, and four-photon sources. By restricting the mutual information between the phase error and bit error, we obtain a higher secure bit error rate threshold of the multiphoton components than previous works. Besides, we compare the performances of the six-state SARG04 with other prepare-and-measure QKD protocols using decoy states. PMID:27383014

Key on demand (KoD) for software-defined optical networks secured by quantum key distribution (QKD).

PubMed

Cao, Yuan; Zhao, Yongli; Colman-Meixner, Carlos; Yu, Xiaosong; Zhang, Jie

2017-10-30

Software-defined optical networking (SDON) will become the next generation optical network architecture. However, the optical layer and control layer of SDON are vulnerable to cyberattacks. While, data encryption is an effective method to minimize the negative effects of cyberattacks, secure key interchange is its major challenge which can be addressed by the quantum key distribution (QKD) technique. Hence, in this paper we discuss the integration of QKD with WDM optical networks to secure the SDON architecture by introducing a novel key on demand (KoD) scheme which is enabled by a novel routing, wavelength and key assignment (RWKA) algorithm. The QKD over SDON with KoD model follows two steps to provide security: i) quantum key pools (QKPs) construction for securing the control channels (CChs) and data channels (DChs); ii) the KoD scheme uses RWKA algorithm to allocate and update secret keys for different security requirements. To test our model, we define a security probability index which measures the security gain in CChs and DChs. Simulation results indicate that the security performance of CChs and DChs can be enhanced by provisioning sufficient secret keys in QKPs and performing key-updating considering potential cyberattacks. Also, KoD is beneficial to achieve a positive balance between security requirements and key resource usage.

Efficient generation of twin photons at telecom wavelengths with 2.5 GHz repetition-rate-tunable comb laser.

PubMed

Jin, Rui-Bo; Shimizu, Ryosuke; Morohashi, Isao; Wakui, Kentaro; Takeoka, Masahiro; Izumi, Shuro; Sakamoto, Takahide; Fujiwara, Mikio; Yamashita, Taro; Miki, Shigehito; Terai, Hirotaka; Wang, Zhen; Sasaki, Masahide

2014-12-19

Efficient generation and detection of indistinguishable twin photons are at the core of quantum information and communications technology (Q-ICT). These photons are conventionally generated by spontaneous parametric down conversion (SPDC), which is a probabilistic process, and hence occurs at a limited rate, which restricts wider applications of Q-ICT. To increase the rate, one had to excite SPDC by higher pump power, while it inevitably produced more unwanted multi-photon components, harmfully degrading quantum interference visibility. Here we solve this problem by using recently developed 10 GHz repetition-rate-tunable comb laser, combined with a group-velocity-matched nonlinear crystal, and superconducting nanowire single photon detectors. They operate at telecom wavelengths more efficiently with less noises than conventional schemes, those typically operate at visible and near infrared wavelengths generated by a 76 MHz Ti Sapphire laser and detected by Si detectors. We could show high interference visibilities, which are free from the pump-power induced degradation. Our laser, nonlinear crystal, and detectors constitute a powerful tool box, which will pave a way to implementing quantum photonics circuits with variety of good and low-cost telecom components, and will eventually realize scalable Q-ICT in optical infra-structures.

Synchronization of random bit generators based on coupled chaotic lasers and application to cryptography.

PubMed

Kanter, Ido; Butkovski, Maria; Peleg, Yitzhak; Zigzag, Meital; Aviad, Yaara; Reidler, Igor; Rosenbluh, Michael; Kinzel, Wolfgang

2010-08-16

Random bit generators (RBGs) constitute an important tool in cryptography, stochastic simulations and secure communications. The later in particular has some difficult requirements: high generation rate of unpredictable bit strings and secure key-exchange protocols over public channels. Deterministic algorithms generate pseudo-random number sequences at high rates, however, their unpredictability is limited by the very nature of their deterministic origin. Recently, physical RBGs based on chaotic semiconductor lasers were shown to exceed Gbit/s rates. Whether secure synchronization of two high rate physical RBGs is possible remains an open question. Here we propose a method, whereby two fast RBGs based on mutually coupled chaotic lasers, are synchronized. Using information theoretic analysis we demonstrate security against a powerful computational eavesdropper, capable of noiseless amplification, where all parameters are publicly known. The method is also extended to secure synchronization of a small network of three RBGs.

Decoy-state quantum key distribution with a leaky source

NASA Astrophysics Data System (ADS)

Tamaki, Kiyoshi; Curty, Marcos; Lucamarini, Marco

2016-06-01

In recent years, there has been a great effort to prove the security of quantum key distribution (QKD) with a minimum number of assumptions. Besides its intrinsic theoretical interest, this would allow for larger tolerance against device imperfections in the actual implementations. However, even in this device-independent scenario, one assumption seems unavoidable, that is, the presence of a protected space devoid of any unwanted information leakage in which the legitimate parties can privately generate, process and store their classical data. In this paper we relax this unrealistic and hardly feasible assumption and introduce a general formalism to tackle the information leakage problem in most of existing QKD systems. More specifically, we prove the security of optical QKD systems using phase and intensity modulators in their transmitters, which leak the setting information in an arbitrary manner. We apply our security proof to cases of practical interest and show key rates similar to those obtained in a perfectly shielded environment. Our work constitutes a fundamental step forward in guaranteeing implementation security of quantum communication systems.

Three-party authenticated key agreements for optimal communication

PubMed Central

Lee, Tian-Fu; Hwang, Tzonelih

2017-01-01

Authenticated key agreements enable users to determine session keys, and to securely communicate with others over an insecure channel via the session keys. This study investigates the lower bounds on communications for three-party authenticated key agreements and considers whether or not the sub-keys for generating a session key can be revealed in the channel. Since two clients do not share any common secret key, they require the help of the server to authenticate their identities and exchange confidential and authenticated information over insecure networks. However, if the session key security is based on asymmetric cryptosystems, then revealing the sub-keys cannot compromise the session key. The clients can directly exchange the sub-keys and reduce the transmissions. In addition, authenticated key agreements were developed by using the derived results of the lower bounds on communications. Compared with related approaches, the proposed protocols had fewer transmissions and realized the lower bounds on communications. PMID:28355253

Continuous variable quantum key distribution: finite-key analysis of composable security against coherent attacks.

PubMed

Furrer, F; Franz, T; Berta, M; Leverrier, A; Scholz, V B; Tomamichel, M; Werner, R F

2012-09-07

We provide a security analysis for continuous variable quantum key distribution protocols based on the transmission of two-mode squeezed vacuum states measured via homodyne detection. We employ a version of the entropic uncertainty relation for smooth entropies to give a lower bound on the number of secret bits which can be extracted from a finite number of runs of the protocol. This bound is valid under general coherent attacks, and gives rise to keys which are composably secure. For comparison, we also give a lower bound valid under the assumption of collective attacks. For both scenarios, we find positive key rates using experimental parameters reachable today.

Secure image retrieval with multiple keys

NASA Astrophysics Data System (ADS)

Liang, Haihua; Zhang, Xinpeng; Wei, Qiuhan; Cheng, Hang

2018-03-01

This article proposes a secure image retrieval scheme under a multiuser scenario. In this scheme, the owner first encrypts and uploads images and their corresponding features to the cloud; then, the user submits the encrypted feature of the query image to the cloud; next, the cloud compares the encrypted features and returns encrypted images with similar content to the user. To find the nearest neighbor in the encrypted features, an encryption with multiple keys is proposed, in which the query feature of each user is encrypted by his/her own key. To improve the key security and space utilization, global optimization and Gaussian distribution are, respectively, employed to generate multiple keys. The experiments show that the proposed encryption can provide effective and secure image retrieval for each user and ensure confidentiality of the query feature of each user.

Generation of tunable, high repetition rate optical frequency combs using on-chip silicon modulators

NASA Astrophysics Data System (ADS)

Nagarjun, K. P.; Jeyaselvan, Vadivukarassi; Selvaraja, Shankar Kumar; Supradeepa, V. R.

2018-04-01

We experimentally demonstrate tunable, highly-stable frequency combs with high repetition-rates using a single, charge injection based silicon PN modulator. In this work, we demonstrate combs in the C-band with over 8 lines in a 20-dB bandwidth. We demonstrate continuous tuning of the center frequency in the C-band and tuning of the repetition-rate from 7.5GHz to 12.5GHz. We also demonstrate through simulations the potential for bandwidth scaling using an optimized silicon PIN modulator. We find that, the time varying free carrier absorption due to carrier injection, an undesirable effect in data modulators, assists here in enhancing flatness in the generated combs.

Next-generation genome-scale models for metabolic engineering.

PubMed

King, Zachary A; Lloyd, Colton J; Feist, Adam M; Palsson, Bernhard O

2015-12-01

Constraint-based reconstruction and analysis (COBRA) methods have become widely used tools for metabolic engineering in both academic and industrial laboratories. By employing a genome-scale in silico representation of the metabolic network of a host organism, COBRA methods can be used to predict optimal genetic modifications that improve the rate and yield of chemical production. A new generation of COBRA models and methods is now being developed--encompassing many biological processes and simulation strategies-and next-generation models enable new types of predictions. Here, three key examples of applying COBRA methods to strain optimization are presented and discussed. Then, an outlook is provided on the next generation of COBRA models and the new types of predictions they will enable for systems metabolic engineering. Copyright © 2014 Elsevier Ltd. All rights reserved.

A generating function approach to HIV transmission with dynamic contact rates

DOE PAGES

Romero-Severson, Ethan O.; Meadors, Grant D.; Volz, Erik M.

2014-04-24

The basic reproduction number, R 0, is often defined as the average number of infections generated by a newly infected individual in a fully susceptible population. The interpretation, meaning, and derivation of R 0 are controversial. However, in the context of mean field models, R 0 demarcates the epidemic threshold below which the infected population approaches zero in the limit of time. In this manner, R 0 has been proposed as a method for understanding the relative impact of public health interventions with respect to disease eliminations from a theoretical perspective. The use of R 0 is made more complexmore » by both the strong dependency of R 0 on the model form and the stochastic nature of transmission. A common assumption in models of HIV transmission that have closed form expressions for R 0 is that a single individual’s behavior is constant over time. For this research, we derive expressions for both R 0 and probability of an epidemic in a finite population under the assumption that people periodically change their sexual behavior over time. We illustrate the use of generating functions as a general framework to model the effects of potentially complex assumptions on the number of transmissions generated by a newly infected person in a susceptible population. In conclusion, we find that the relationship between the probability of an epidemic and R 0 is not straightforward, but, that as the rate of change in sexual behavior increases both R 0 and the probability of an epidemic also decrease.« less

A generating function approach to HIV transmission with dynamic contact rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romero-Severson, Ethan O.; Meadors, Grant D.; Volz, Erik M.

The basic reproduction number, R 0, is often defined as the average number of infections generated by a newly infected individual in a fully susceptible population. The interpretation, meaning, and derivation of R 0 are controversial. However, in the context of mean field models, R 0 demarcates the epidemic threshold below which the infected population approaches zero in the limit of time. In this manner, R 0 has been proposed as a method for understanding the relative impact of public health interventions with respect to disease eliminations from a theoretical perspective. The use of R 0 is made more complexmore » by both the strong dependency of R 0 on the model form and the stochastic nature of transmission. A common assumption in models of HIV transmission that have closed form expressions for R 0 is that a single individual’s behavior is constant over time. For this research, we derive expressions for both R 0 and probability of an epidemic in a finite population under the assumption that people periodically change their sexual behavior over time. We illustrate the use of generating functions as a general framework to model the effects of potentially complex assumptions on the number of transmissions generated by a newly infected person in a susceptible population. In conclusion, we find that the relationship between the probability of an epidemic and R 0 is not straightforward, but, that as the rate of change in sexual behavior increases both R 0 and the probability of an epidemic also decrease.« less

Mining consumer reviews to generate ratings of different product attributes while producing feature-based review-summary

NASA Astrophysics Data System (ADS)

Kangale, Akshay; Krishna Kumar, S.; Arshad Naeem, Mohd; Williams, Mark; Tiwari, M. K.

2016-10-01

With the massive growth of the internet, product reviews increasingly serve as an important source of information for customers to make choices online. Customers depend on these reviews to understand users' experience, and manufacturers rely on this user-generated content to capture user sentiments about their product. Therefore, it is in the best interest of both customers and manufacturers to have a portal where they can read a complete comprehensive summary of these reviews in minimum time. With this in mind, we arrived at our first objective which is to generate a feature-based review-summary. Our second objective is to develop a predictive model to know the next week's product sales based on numerical review ratings and textual features embedded in the reviews. When it comes to product features, every user has different priorities for different features. To capture this aspect of decision-making, we have designed a new mechanism to generate a numerical rating for every feature of the product individually. The data have been collected from a well-known commercial website for two different products. The validation of the model is carried out using a crowd-sourcing technique.

Satellite-to-ground quantum key distribution.

PubMed

Liao, Sheng-Kai; Cai, Wen-Qi; Liu, Wei-Yue; Zhang, Liang; Li, Yang; Ren, Ji-Gang; Yin, Juan; Shen, Qi; Cao, Yuan; Li, Zheng-Ping; Li, Feng-Zhi; Chen, Xia-Wei; Sun, Li-Hua; Jia, Jian-Jun; Wu, Jin-Cai; Jiang, Xiao-Jun; Wang, Jian-Feng; Huang, Yong-Mei; Wang, Qiang; Zhou, Yi-Lin; Deng, Lei; Xi, Tao; Ma, Lu; Hu, Tai; Zhang, Qiang; Chen, Yu-Ao; Liu, Nai-Le; Wang, Xiang-Bin; Zhu, Zhen-Cai; Lu, Chao-Yang; Shu, Rong; Peng, Cheng-Zhi; Wang, Jian-Yu; Pan, Jian-Wei

2017-09-07

Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD-a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.

Method for encryption and transmission of digital keying data

DOEpatents

Mniszewski, Susan M.; Springer, Edward A.; Brenner, David P.

1988-01-01

A method for the encryption, transmission, and subsequent decryption of digital keying data. The method utilizes the Data Encryption Standard and is implemented by means of a pair of apparatus, each of which is selectable to operate as either a master unit or remote unit. Each unit contains a set of key encryption keys which are indexed by a common indexing system. The master unit operates upon command from the remote unit to generate a data encryption key and encrypt the data encryption key using a preselected key encryption key. The encrypted data encryption key and an index designator are then downloaded to the remote unit, where the data encryption key is decrypted for subsequent use in the encryption and transmission data. Downloading of the encrypted data encryption key enables frequent change of keys without requiring manual entry or storage of keys at the remote unit.

Towards an automated intelligence product generation capability

NASA Astrophysics Data System (ADS)

Smith, Alison M.; Hawes, Timothy W.; Nolan, James J.

2015-05-01

Creating intelligence information products is a time consuming and difficult process for analysts faced with identifying key pieces of information relevant to a complex set of information requirements. Complicating matters, these key pieces of information exist in multiple modalities scattered across data stores, buried in huge volumes of data. This results in the current predicament analysts find themselves; information retrieval and management consumes huge amounts of time that could be better spent performing analysis. The persistent growth in data accumulation rates will only increase the amount of time spent on these tasks without a significant advance in automated solutions for information product generation. We present a product generation tool, Automated PrOduct Generation and Enrichment (APOGEE), which aims to automate the information product creation process in order to shift the bulk of the analysts' effort from data discovery and management to analysis. APOGEE discovers relevant text, imagery, video, and audio for inclusion in information products using semantic and statistical models of unstructured content. APOGEEs mixed-initiative interface, supported by highly responsive backend mechanisms, allows analysts to dynamically control the product generation process ensuring a maximally relevant result. The combination of these capabilities results in significant reductions in the time it takes analysts to produce information products while helping to increase the overall coverage. Through evaluation with a domain expert, APOGEE has been shown the potential to cut down the time for product generation by 20x. The result is a flexible end-to-end system that can be rapidly deployed in new operational settings.

Side-channel-free quantum key distribution.

PubMed

Braunstein, Samuel L; Pirandola, Stefano

2012-03-30

Quantum key distribution (QKD) offers the promise of absolutely secure communications. However, proofs of absolute security often assume perfect implementation from theory to experiment. Thus, existing systems may be prone to insidious side-channel attacks that rely on flaws in experimental implementation. Here we replace all real channels with virtual channels in a QKD protocol, making the relevant detectors and settings inside private spaces inaccessible while simultaneously acting as a Hilbert space filter to eliminate side-channel attacks. By using a quantum memory we find that we are able to bound the secret-key rate below by the entanglement-distillation rate computed over the distributed states.

Quantum key distribution with delayed privacy amplification and its application to the security proof of a two-way deterministic protocol

NASA Astrophysics Data System (ADS)

Fung, Chi-Hang Fred; Ma, Xiongfeng; Chau, H. F.; Cai, Qing-Yu

2012-03-01

Privacy amplification (PA) is an essential postprocessing step in quantum key distribution (QKD) for removing any information an eavesdropper may have on the final secret key. In this paper, we consider delaying PA of the final key after its use in one-time pad encryption and prove its security. We prove that the security and the key generation rate are not affected by delaying PA. Delaying PA has two applications: it serves as a tool for significantly simplifying the security proof of QKD with a two-way quantum channel, and also it is useful in QKD networks with trusted relays. To illustrate the power of the delayed PA idea, we use it to prove the security of a qubit-based two-way deterministic QKD protocol which uses four states and four encoding operations.

Practical issues in quantum-key-distribution postprocessing

NASA Astrophysics Data System (ADS)

Fung, Chi-Hang Fred; Ma, Xiongfeng; Chau, H. F.

2010-01-01

Quantum key distribution (QKD) is a secure key generation method between two distant parties by wisely exploiting properties of quantum mechanics. In QKD, experimental measurement outcomes on quantum states are transformed by the two parties to a secret key. This transformation is composed of many logical steps (as guided by security proofs), which together will ultimately determine the length of the final secret key and its security. We detail the procedure for performing such classical postprocessing taking into account practical concerns (including the finite-size effect and authentication and encryption for classical communications). This procedure is directly applicable to realistic QKD experiments and thus serves as a recipe that specifies what postprocessing operations are needed and what the security level is for certain lengths of the keys. Our result is applicable to the BB84 protocol with a single or entangled photon source.

Assessment of the health care waste generation rates and its management system in hospitals of Addis Ababa, Ethiopia, 2011

PubMed Central

2013-01-01

Background Healthcare waste management options are varying in Ethiopia. One of the first critical steps in the process of developing a reliable waste management plan requires a widespread understanding of the amount and the management system. This study aimed to assess the health care waste generation rate and its management system in some selected hospitals located in Addis Ababa, Ethiopia. Methods Six hospitals in Addis Ababa, (three private and three public), were selected using simple random sampling method for this work. Data was recorded by using an appropriately designed questionnaire, which was completed for the period of two months. The calculations were based on the weights of the health care wastes that were regularly generated in the selected hospitals over a one week period during the year 2011. Average generation indexes were determined in relation to certain important factors, like the type of hospitals (public vs private). Results The median waste generation rate was found to be varied from 0.361- 0.669 kg/patient/day, comprised of 58.69% non-hazardous and 41.31% hazardous wastes. The amount of waste generated was increased as the number of patients flow increased (rs=1). Public hospitals generated high proportion of total health care wastes (59.22%) in comparison with private hospitals (40.48%). The median waste generation rate was significantly vary between hospitals with Kruskal-Wallis test (X2=30.65, p=0.0001). The amount of waste was positively correlated with the number of patients (p < 0.05). The waste separation and treatment practices were very poor. Other alternatives for waste treatment rather than incineration such as a locally made autoclave should be evaluated and implemented. Conclusion These findings revealed that the management of health care waste at hospitals in Addis Ababa city was poor. PMID:23311573

Generation rates and chemical compositions of waste streams in a typical crewed space habitat

NASA Technical Reports Server (NTRS)

Wydeven, Theodore; Golub, Morton A.

1990-01-01

A judicious compilation of generation rates and chemical compositions of potential waste feed streams in a typical crewed space habitat was made in connection with the waste-management aspect of NASA's Physical/Chemical Closed-Loop Life Support Program. Waste composition definitions are needed for the design of waste-processing technologies involved in closing major life support functions in future long-duration human space missions. Tables of data for the constituents and chemical formulas of the following waste streams are presented and discussed: human urine, feces, hygiene (laundry and shower) water, cleansing agents, trash, humidity condensate, dried sweat, and trace contaminants. Tables of data on dust generation and pH values of the different waste streams are also presented and discussed.

Investigation of the rates of surface and bulk ROS-generating reactions using indigo dye as an indicator

NASA Astrophysics Data System (ADS)

Anderson, Carly; Clark, Douglas; Graves, David

2014-10-01

We present evidence for the existence of two distinct processes that contribute to the generation of reactive oxygen and nitrogen species (RONS) in liquids exposed to cold atmospheric plasma (CAP) in air. At the plasma-liquid interface, there exists a fast surface reaction zone where RONS from the gas phase interact with species in the liquid. RONS can also be produced by ``slow'' chemical reactions in the bulk liquid, even long after plasma exposure. To separate the effects of these processes, we used indigo dye as an indicator of ROS production; specifically generation of hydroxyl radical. The rate of indigo decolorization while in direct contact with CAP is compared with the expected rate of hydroxyl radical generation at the liquid surface. When added to aqueous solutions after CAP exposure, indigo dye reacts on a time scale consistent with the production of peroxynitrous acid, ONOOH, which is known to decompose to hydroxyl radical below a pH of 6.8. In this study, the CAP used was a air corona discharge plasma run in a positive streamer mode.

Long-distance practical quantum key distribution by entanglement swapping.

PubMed

Scherer, Artur; Sanders, Barry C; Tittel, Wolfgang

2011-02-14

We develop a model for practical, entanglement-based long-distance quantum key distribution employing entanglement swapping as a key building block. Relying only on existing off-the-shelf technology, we show how to optimize resources so as to maximize secret key distribution rates. The tools comprise lossy transmission links, such as telecom optical fibers or free space, parametric down-conversion sources of entangled photon pairs, and threshold detectors that are inefficient and have dark counts. Our analysis provides the optimal trade-off between detector efficiency and dark counts, which are usually competing, as well as the optimal source brightness that maximizes the secret key rate for specified distances (i.e. loss) between sender and receiver.

Dual Key Speech Encryption Algorithm Based Underdetermined BSS

PubMed Central

Zhao, Huan; Chen, Zuo; Zhang, Xixiang

2014-01-01

When the number of the mixed signals is less than that of the source signals, the underdetermined blind source separation (BSS) is a significant difficult problem. Due to the fact that the great amount data of speech communications and real-time communication has been required, we utilize the intractability of the underdetermined BSS problem to present a dual key speech encryption method. The original speech is mixed with dual key signals which consist of random key signals (one-time pad) generated by secret seed and chaotic signals generated from chaotic system. In the decryption process, approximate calculation is used to recover the original speech signals. The proposed algorithm for speech signals encryption can resist traditional attacks against the encryption system, and owing to approximate calculation, decryption becomes faster and more accurate. It is demonstrated that the proposed method has high level of security and can recover the original signals quickly and efficiently yet maintaining excellent audio quality. PMID:24955430

Experimental study on discretely modulated continuous-variable quantum key distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen Yong; Zou Hongxin; Chen Pingxing

2010-08-15

We present a discretely modulated continuous-variable quantum key distribution system in free space by using strong coherent states. The amplitude noise in the laser source is suppressed to the shot-noise limit by using a mode cleaner combined with a frequency shift technique. Also, it is proven that the phase noise in the source has no impact on the final secret key rate. In order to increase the encoding rate, we use broadband homodyne detectors and the no-switching protocol. In a realistic model, we establish a secret key rate of 46.8 kbits/s against collective attacks at an encoding rate of 10more » MHz for a 90% channel loss when the modulation variance is optimal.« less

78 FR 56690 - All Dams Generation, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-13

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-2318-000] All Dams Generation, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding, of All Dams...

Measurement-Device-Independent Quantum Key Distribution over 200 km

NASA Astrophysics Data System (ADS)

Tang, Yan-Lin; Yin, Hua-Lei; Chen, Si-Jing; Liu, Yang; Zhang, Wei-Jun; Jiang, Xiao; Zhang, Lu; Wang, Jian; You, Li-Xing; Guan, Jian-Yu; Yang, Dong-Xu; Wang, Zhen; Liang, Hao; Zhang, Zhen; Zhou, Nan; Ma, Xiongfeng; Chen, Teng-Yun; Zhang, Qiang; Pan, Jian-Wei

2014-11-01

Measurement-device-independent quantum key distribution (MDIQKD) protocol is immune to all attacks on detection and guarantees the information-theoretical security even with imperfect single-photon detectors. Recently, several proof-of-principle demonstrations of MDIQKD have been achieved. Those experiments, although novel, are implemented through limited distance with a key rate less than 0.1 bit /s . Here, by developing a 75 MHz clock rate fully automatic and highly stable system and superconducting nanowire single-photon detectors with detection efficiencies of more than 40%, we extend the secure transmission distance of MDIQKD to 200 km and achieve a secure key rate 3 orders of magnitude higher. These results pave the way towards a quantum network with measurement-device-independent security.

Adaptive real time selection for quantum key distribution in lossy and turbulent free-space channels

NASA Astrophysics Data System (ADS)

Vallone, Giuseppe; Marangon, Davide G.; Canale, Matteo; Savorgnan, Ilaria; Bacco, Davide; Barbieri, Mauro; Calimani, Simon; Barbieri, Cesare; Laurenti, Nicola; Villoresi, Paolo

2015-04-01

The unconditional security in the creation of cryptographic keys obtained by quantum key distribution (QKD) protocols will induce a quantum leap in free-space communication privacy in the same way that we are beginning to realize secure optical fiber connections. However, free-space channels, in particular those with long links and the presence of atmospheric turbulence, are affected by losses, fluctuating transmissivity, and background light that impair the conditions for secure QKD. Here we introduce a method to contrast the atmospheric turbulence in QKD experiments. Our adaptive real time selection (ARTS) technique at the receiver is based on the selection of the intervals with higher channel transmissivity. We demonstrate, using data from the Canary Island 143-km free-space link, that conditions with unacceptable average quantum bit error rate which would prevent the generation of a secure key can be used once parsed according to the instantaneous scintillation using the ARTS technique.

Measurements of Flow Rate and Trajectory of Aircraft Tire-Generated Water Spray

NASA Technical Reports Server (NTRS)

Daugherty, Robert H.; Stubbs, Sandy M.

1987-01-01

An experimental investigation was conducted at the NASA Langley Research Center to measure the flow rate and trajectory of water spray generated by an aircraft tire operating on a flooded runway. Tests were conducted in the Hydrodynamics Research Facility and made use of a partial airframe and a nose tire from a general aviation aircraft. Nose tires from a commercial transport aircraft were also used. The effects of forward speed, tire load, and water depth on water spray patterns were evaluated by measuring the amount and location of water captured by an array of tubes mounted behind the test tire. Water ejected from the side of the tire footprint had the most significant potential for ingestion into engine inlets. A lateral wake created on the water surface by the rolling tire can dominate the shape of the spray pattern as the distance aft of the tire is increased. Forward speed increased flow rates and moved the spray pattern inboard. Increased tire load caused the spray to become less dense. Near the tire, increased water depths caused flow rates to increase. Tests using a fuselage and partial wing along with the nose gear showed that for certain configurations, wing aerodynamics can cause a concentration of spray above the wing.

KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sawake, Shota; Tajima, Noriaki; Mortimer, Jenny C.

Humans are unable to synthesize L-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels,more » leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity.« less

KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis.

PubMed

Sawake, Shota; Tajima, Noriaki; Mortimer, Jenny C; Lao, Jeemeng; Ishikawa, Toshiki; Yu, Xiaolan; Yamanashi, Yukiko; Yoshimi, Yoshihisa; Kawai-Yamada, Maki; Dupree, Paul; Tsumuraya, Yoichi; Kotake, Toshihisa

2015-12-01

Humans are unable to synthesize l-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels, leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity. © 2015 American Society of Plant Biologists. All rights reserved.

KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis

PubMed Central

Sawake, Shota; Tajima, Noriaki; Lao, Jeemeng; Ishikawa, Toshiki; Yu, Xiaolan; Yamanashi, Yukiko; Yoshimi, Yoshihisa; Kawai-Yamada, Maki

2015-01-01

Humans are unable to synthesize l-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels, leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity. PMID:26672069

Generation of plasma X-ray sources via high repetition rate femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Baguckis, Artūras; Plukis, Artūras; Reklaitis, Jonas; Remeikis, Vidmantas; Giniūnas, Linas; Vengris, Mikas

2017-12-01

In this study, we present the development and characterization of Cu plasma X-ray source driven by 20 W average power high repetition rate femtosecond laser in ambient atmosphere environment. The peak Cu- Kα photon flux of 2.3 × 109 photons/s into full solid angle is demonstrated (with a process conversion efficiency of 10-7), using pulses with peak intensity of 4.65 × 1014 W/cm2. Such Cu- Kα flux is significantly larger than others found in comparable experiments, performed in air environment. The effects of resonance plasma absorption process, when optimized, are shown to increase measured flux by the factor of 2-3. The relationship between X-ray photon flux and plasma-driving pulse repetition rate is quasi-linear, suggesting that fluxes could further be increased to 1010 photons/s using even higher average powers of driving radiation. These results suggest that to fully utilize the potential of high repetition rate laser sources, novel target material delivery systems (for example, jet-based ones) are required. On the other hand, this study demonstrates that high energy lasers currently used for plasma X-ray sources can be conveniently and efficiently replaced by high average power and repetition rate laser radiation, as a way to increase the brightness of the generated X-rays.

Random Number Generation and Executive Functions in Parkinson's Disease: An Event-Related Brain Potential Study.

PubMed

Münte, Thomas F; Joppich, Gregor; Däuper, Jan; Schrader, Christoph; Dengler, Reinhard; Heldmann, Marcus

2015-01-01

The generation of random sequences is considered to tax executive functions and has been reported to be impaired in Parkinson's disease (PD) previously. To assess the neurophysiological markers of random number generation in PD. Event-related potentials (ERP) were recorded in 12 PD patients and 12 age-matched normal controls (NC) while either engaging in random number generation (RNG) by pressing the number keys on a computer keyboard in a random sequence or in ordered number generation (ONG) necessitating key presses in the canonical order. Key presses were paced by an external auditory stimulus at a rate of 1 tone every 1800 ms. As a secondary task subjects had to monitor the tone-sequence for a particular target tone to which the number "0" key had to be pressed. This target tone occurred randomly and infrequently, thus creating a secondary oddball task. Behaviorally, PD patients showed an increased tendency to count in steps of one as well as a tendency towards repetition avoidance. Electrophysiologically, the amplitude of the P3 component of the ERP to the target tone of the secondary task was reduced during RNG in PD but not in NC. The behavioral findings indicate less random behavior in PD while the ERP findings suggest that this impairment comes about, because attentional resources are depleted in PD.

BEAM DYNAMICS STUDIES OF A HIGH-REPETITION RATE LINAC-DRIVER FOR A 4TH GENERATION LIGHT SOURCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ventturini, M.; Corlett, J.; Emma, P.

2012-05-18

We present recent progress toward the design of a super-conducting linac driver for a high-repetition rate FEL-based soft x-ray light source. The machine is designed to accept beams generated by the APEX photo-cathode gun operating with MHz-range repetition rate and deliver them to an array of SASE and seeded FEL beamlines. We review the current baseline design and report results of beam dynamics studies.

Gaussian Mixture Model of Heart Rate Variability

PubMed Central

Costa, Tommaso; Boccignone, Giuseppe; Ferraro, Mario

2012-01-01

Heart rate variability (HRV) is an important measure of sympathetic and parasympathetic functions of the autonomic nervous system and a key indicator of cardiovascular condition. This paper proposes a novel method to investigate HRV, namely by modelling it as a linear combination of Gaussians. Results show that three Gaussians are enough to describe the stationary statistics of heart variability and to provide a straightforward interpretation of the HRV power spectrum. Comparisons have been made also with synthetic data generated from different physiologically based models showing the plausibility of the Gaussian mixture parameters. PMID:22666386

Strain rate and shear stress at the grain scale generated during near equilibrium antigorite dehydration

NASA Astrophysics Data System (ADS)

Padrón-Navarta, José Alberto; Tommasi, Andréa; Garrido, Carlos J.; Mainprice, David; Clément, Maxime

2016-04-01

Dehydration reactions are an outstanding case of mineral replacement reactions because they produce a significant transient fluid-filled porosity. Because fluids are present, these reactions occur by interface-coupled dissolution-precipitation. Under poorly drained conditions corresponding to foliated metamorphic rocks, they generate fluid pressure gradients that evolve in time and space eventually controlling fluid migration [1]. Despite the general agreement on this fact, we still lack of a precise knowledge of the complex coupling between the stresses generated during the reaction and the timescales for mineral growth and how they ultimate control the rate of fluid migration. Constraining these rates is challenge because the timescales of the feedback between fluid flow and mineral growth rates at near equilibrium are beyond the current experimental capabilities. For instance, numerical simulations suggest that the draining times of a dehydration front by compaction are in the order of 10-100 ky [1] difficult to translate into experimental strain rates. On the other hand, the natural record of dehydration reaction might potentially provide unique constrains on this feedback, but we need to identify microstructures related to compaction and quantify them. Features interpreted as due to compaction have been identified in a microstructural study [2] of the first stages of the antigorite dehydration at high-pressure conditions in Cerro del Almirez, Spain (ca. 1.6-1.9 GPa and 630-710 ° C). Compaction features can be mostly observed in the metamorphic enstatite in the form of (1) gradual crystallographic misorientation (up to 16°) of prismatic crystals due to buckling, (3) localized orthoenstatite(Pbca)/low clinoenstatite (P21/c) inversion (confirmed optically and by means of Electron Backscattered Diffraction) and (4) brittle fracturing of prismatic enstatite wrapped by plastically deformed chlorite. The coexistence of enstatite buckling and clinoenstatite lamellae

Secure polarization-independent subcarrier quantum key distribution in optical fiber channel using BB84 protocol with a strong reference.

PubMed

Gleim, A V; Egorov, V I; Nazarov, Yu V; Smirnov, S V; Chistyakov, V V; Bannik, O I; Anisimov, A A; Kynev, S M; Ivanova, A E; Collins, R J; Kozlov, S A; Buller, G S

2016-02-08

A quantum key distribution system based on the subcarrier wave modulation method has been demonstrated which employs the BB84 protocol with a strong reference to generate secure bits at a rate of 16.5 kbit/s with an error of 0.5% over an optical channel of 10 dB loss, and 18 bits/s with an error of 0.75% over 25 dB of channel loss. To the best of our knowledge, these results represent the highest channel loss reported for secure quantum key distribution using the subcarrier wave approach. A passive unidirectional scheme has been used to compensate for the polarization dependence of the phase modulators in the receiver module, which resulted in a high visibility of 98.8%. The system is thus fully insensitive to polarization fluctuations and robust to environmental changes, making the approach promising for use in optical telecommunication networks. Further improvements in secure key rate and transmission distance can be achieved by implementing the decoy states protocol or by optimizing the mean photon number used in line with experimental parameters.

Efficient generation of twin photons at telecom wavelengths with 2.5 GHz repetition-rate-tunable comb laser

PubMed Central

Jin, Rui-Bo; Shimizu, Ryosuke; Morohashi, Isao; Wakui, Kentaro; Takeoka, Masahiro; Izumi, Shuro; Sakamoto, Takahide; Fujiwara, Mikio; Yamashita, Taro; Miki, Shigehito; Terai, Hirotaka; Wang, Zhen; Sasaki, Masahide

2014-01-01

Efficient generation and detection of indistinguishable twin photons are at the core of quantum information and communications technology (Q-ICT). These photons are conventionally generated by spontaneous parametric down conversion (SPDC), which is a probabilistic process, and hence occurs at a limited rate, which restricts wider applications of Q-ICT. To increase the rate, one had to excite SPDC by higher pump power, while it inevitably produced more unwanted multi-photon components, harmfully degrading quantum interference visibility. Here we solve this problem by using recently developed 10 GHz repetition-rate-tunable comb laser, combined with a group-velocity-matched nonlinear crystal, and superconducting nanowire single photon detectors. They operate at telecom wavelengths more efficiently with less noises than conventional schemes, those typically operate at visible and near infrared wavelengths generated by a 76 MHz Ti Sapphire laser and detected by Si detectors. We could show high interference visibilities, which are free from the pump-power induced degradation. Our laser, nonlinear crystal, and detectors constitute a powerful tool box, which will pave a way to implementing quantum photonics circuits with variety of good and low-cost telecom components, and will eventually realize scalable Q-ICT in optical infra-structures. PMID:25524646

Efficient bit sifting scheme of post-processing in quantum key distribution

NASA Astrophysics Data System (ADS)

Li, Qiong; Le, Dan; Wu, Xianyan; Niu, Xiamu; Guo, Hong

2015-10-01

Bit sifting is an important step in the post-processing of quantum key distribution (QKD). Its function is to sift out the undetected original keys. The communication traffic of bit sifting has essential impact on the net secure key rate of a practical QKD system. In this paper, an efficient bit sifting scheme is presented, of which the core is a lossless source coding algorithm. Both theoretical analysis and experimental results demonstrate that the performance of the scheme is approaching the Shannon limit. The proposed scheme can greatly decrease the communication traffic of the post-processing of a QKD system, which means the proposed scheme can decrease the secure key consumption for classical channel authentication and increase the net secure key rate of the QKD system, as demonstrated by analyzing the improvement on the net secure key rate. Meanwhile, some recommendations on the application of the proposed scheme to some representative practical QKD systems are also provided.

Parameter optimization in biased decoy-state quantum key distribution with both source errors and statistical fluctuations

NASA Astrophysics Data System (ADS)

Zhu, Jian-Rong; Li, Jian; Zhang, Chun-Mei; Wang, Qin

2017-10-01

The decoy-state method has been widely used in commercial quantum key distribution (QKD) systems. In view of the practical decoy-state QKD with both source errors and statistical fluctuations, we propose a universal model of full parameter optimization in biased decoy-state QKD with phase-randomized sources. Besides, we adopt this model to carry out simulations of two widely used sources: weak coherent source (WCS) and heralded single-photon source (HSPS). Results show that full parameter optimization can significantly improve not only the secure transmission distance but also the final key generation rate. And when taking source errors and statistical fluctuations into account, the performance of decoy-state QKD using HSPS suffered less than that of decoy-state QKD using WCS.

A low-complexity Reed-Solomon decoder using new key equation solver

NASA Astrophysics Data System (ADS)

Xie, Jun; Yuan, Songxin; Tu, Xiaodong; Zhang, Chongfu

2006-09-01

This paper presents a low-complexity parallel Reed-Solomon (RS) (255,239) decoder architecture using a novel pipelined variable stages recursive Modified Euclidean (ME) algorithm for optical communication. The pipelined four-parallel syndrome generator is proposed. The time multiplexing and resource sharing schemes are used in the novel recursive ME algorithm to reduce the logic gate count. The new key equation solver can be shared by two decoder macro. A new Chien search cell which doesn't need initialization is proposed in the paper. The proposed decoder can be used for 2.5Gb/s data rates device. The decoder is implemented in Altera' Stratixll device. The resource utilization is reduced about 40% comparing to the conventional method.

Backup key generation model for one-time password security protocol

NASA Astrophysics Data System (ADS)

Jeyanthi, N.; Kundu, Sourav

2017-11-01

The use of one-time password (OTP) has ushered new life into the existing authentication protocols used by the software industry. It introduced a second layer of security to the traditional username-password authentication, thus coining the term, two-factor authentication. One of the drawbacks of this protocol is the unreliability of the hardware token at the time of authentication. This paper proposes a simple backup key model that can be associated with the real world applications’user database, which would allow a user to circumvent the second authentication stage, in the event of unavailability of the hardware token.

Individual-level social capital and self-rated health in Japan: an application of the Resource Generator.

PubMed

Kobayashi, Tomoko; Kawachi, Ichiro; Iwase, Toshihide; Suzuki, Etsuji; Takao, Soshi

2013-05-01

Despite accumulating evidence of associations between social capital and health in public health research, a criticism of the field has been that researchers have exclusively focused on concepts of social cohesion to the exclusion of individual-level approaches. In the present study, we evaluated the association between social capital measured by the Resource Generator (an individual-level assessment of access to social capital) and self-rated health among Japanese population in a cross-sectional study. A postal survey of 4000 randomly selected residents in Okayama City (western Japan) was conducted in February 2009. We divided the overall scores from the Resource Generator Japan scale into quartiles. Odds ratios (ORs) and 95% confidence intervals (CIs) for self-rated health were calculated separately by sex. Individuals with the highest quartile of scores had significantly lower odds of poor health compared to the lowest group after covariate adjustment among both men and women (men; OR: 0.45, 95% CI: 0.24-0.86, women; OR: 0.44, 95% CI: 0.25-0.79, respectively) and there were also significant dose-response relationships. In the sub-domains of Resource Generator Japan scale, a differential pattern was observed by sex. Women showed a clear dose-response relationship with health across all four sub-scales (domestic resources, expert advice, personal skills, and problem solving resources). In contrast, only the domain of expert advice exhibited a strong association with men's health. Among both men and women individual-level social capital measured by the Resource Generator was related to reduced odds of poor health even after taking into account individual confounders. Although we cannot exclude reverse causation due to the cross-sectional design, our study adds to the accumulating evidence of the potential utility of the Resource Generator for evaluating the relationship between individual-level access to social capital and health. Copyright © 2013 Elsevier Ltd

Species-specific responses to climate change and community composition determine future calcification rates of Florida Keys reefs.

PubMed

Okazaki, Remy R; Towle, Erica K; van Hooidonk, Ruben; Mor, Carolina; Winter, Rivah N; Piggot, Alan M; Cunning, Ross; Baker, Andrew C; Klaus, James S; Swart, Peter K; Langdon, Chris

2017-03-01

Anthropogenic climate change compromises reef growth as a result of increasing temperatures and ocean acidification. Scleractinian corals vary in their sensitivity to these variables, suggesting species composition will influence how reef communities respond to future climate change. Because data are lacking for many species, most studies that model future reef growth rely on uniform scleractinian calcification sensitivities to temperature and ocean acidification. To address this knowledge gap, calcification of twelve common and understudied Caribbean coral species was measured for two months under crossed temperatures (27, 30.3 °C) and CO 2 partial pressures (pCO 2 ) (400, 900, 1300 μatm). Mixed-effects models of calcification for each species were then used to project community-level scleractinian calcification using Florida Keys reef composition data and IPCC AR5 ensemble climate model data. Three of the four most abundant species, Orbicella faveolata, Montastraea cavernosa, and Porites astreoides, had negative calcification responses to both elevated temperature and pCO 2 . In the business-as-usual CO 2 emissions scenario, reefs with high abundances of these species had projected end-of-century declines in scleractinian calcification of >50% relative to present-day rates. Siderastrea siderea, the other most common species, was insensitive to both temperature and pCO 2 within the levels tested here. Reefs dominated by this species had the most stable end-of-century growth. Under more optimistic scenarios of reduced CO 2 emissions, calcification rates throughout the Florida Keys declined <20% by 2100. Under the most extreme emissions scenario, projected declines were highly variable among reefs, ranging 10-100%. Without considering bleaching, reef growth will likely decline on most reefs, especially where resistant species like S. siderea are not already dominant. This study demonstrates how species composition influences reef community responses to climate

Memory for melody and key in childhood.

PubMed

Schellenberg, E Glenn; Poon, Jaimie; Weiss, Michael W

2017-01-01

After only two exposures to previously unfamiliar melodies, adults remember the tunes for over a week and the key for over a day. Here, we examined the development of long-term memory for melody and key. Listeners in three age groups (7- to 8-year-olds, 9- to 11-year-olds, and adults) heard two presentations of each of 12 unfamiliar melodies. After a 10-min delay, they heard the same 12 old melodies intermixed with 12 new melodies. Half of the old melodies were transposed up or down by six semitones from initial exposure. Listeners rated how well they recognized the melodies from the exposure phase. Recognition was better for old than for new melodies, for adults compared to children, and for older compared to younger children. Recognition ratings were also higher for old melodies presented in the same key at test as exposure, and the detrimental effect of the transposition affected all age groups similarly. Although memory for melody improves with age and exposure to music, implicit memory for key appears to be adult-like by 7 years of age.

Newborn Survival Case Study in Rwanda - Bottleneck Analysis and Projections in Key Maternal and Child Mortality Rates Using Lives Saved Tool (LiST).

PubMed

Khurmi, Manpreet Singh; Sayinzoga, Felix; Berhe, Atakilt; Bucyana, Tatien; Mwali, Assumpta Kayinamura; Manzi, Emmanuel; Muthu, Maharajan

2017-01-01

The Newborn Survival Case study in Rwanda provides an analysis of the newborn health and survival situation in the country. It reviews evidence-based interventions and coverage levels already implemented in the country; identifies key issues and bottlenecks in service delivery and uptake of services by community/beneficiaries, and provides key recommendations aimed at faster reduction in newborn mortality rate. This study utilized mixed method research including qualitative and quantitative analyses of various maternal and newborn health programs implemented in the country. This included interviewing key stakeholders at each level, field visits and also interviewing beneficiaries for assessment of uptake of services. Monitoring systems such as Health Management Information Systems (HMIS), maternal and newborn death audits were reviewed and data analyzed to aid these analyses. Policies, protocols, various guidelines and tools for monitoring are already in place however, implementation of these remains a challenge e.g. infection control practices to reduce deaths due to sepsis. Although existing staff are quite knowledgeable and are highly motivated, however, shortage of health personnel especially doctors in an issue. New facilities are being operationalized e.g. at Gisenyi, however, the existing facilities needs expansion. It is essential to implement high impact evidence based interventions but coverage levels need to be significantly high in order to achieve higher reduction in newborn mortality rate. Equity approach should be considered in planning so that the services are better implemented and the poor and needy can get the benefits of public health programs.

Photonic chirped radio-frequency generator with ultra-fast sweeping rate and ultra-wide sweeping range.

PubMed

Wun, Jhih-Min; Wei, Chia-Chien; Chen, Jyehong; Goh, Chee Seong; Set, S Y; Shi, Jin-Wei

2013-05-06

A high-performance photonic sweeping-frequency (chirped) radio-frequency (RF) generator has been demonstrated. By use of a novel wavelength sweeping distributed-feedback (DFB) laser, which is operated based on the linewidth enhancement effect, a fixed wavelength narrow-linewidth DFB laser, and a wideband (dc to 50 GHz) photodiode module for the hetero-dyne beating RF signal generation, a very clear chirped RF waveform can be captured by a fast real-time scope. A very-high frequency sweeping rate (10.3 GHz/μs) with an ultra-wide RF frequency sweeping range (~40 GHz) have been demonstrated. The high-repeatability (~97%) in sweeping frequency has been verified by analyzing tens of repetitive chirped waveforms.

Programmable rate modem utilizing digital signal processing techniques

NASA Technical Reports Server (NTRS)

Bunya, George K.; Wallace, Robert L.

1989-01-01

The engineering development study to follow was written to address the need for a Programmable Rate Digital Satellite Modem capable of supporting both burst and continuous transmission modes with either binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK) modulation. The preferred implementation technique is an all digital one which utilizes as much digital signal processing (DSP) as possible. Here design tradeoffs in each portion of the modulator and demodulator subsystem are outlined, and viable circuit approaches which are easily repeatable, have low implementation losses and have low production costs are identified. The research involved for this study was divided into nine technical papers, each addressing a significant region of concern in a variable rate modem design. Trivial portions and basic support logic designs surrounding the nine major modem blocks were omitted. In brief, the nine topic areas were: (1) Transmit Data Filtering; (2) Transmit Clock Generation; (3) Carrier Synthesizer; (4) Receive AGC; (5) Receive Data Filtering; (6) RF Oscillator Phase Noise; (7) Receive Carrier Selectivity; (8) Carrier Recovery; and (9) Timing Recovery.

Secure SCADA communication by using a modified key management scheme.

PubMed

Rezai, Abdalhossein; Keshavarzi, Parviz; Moravej, Zahra

2013-07-01

This paper presents and evaluates a new cryptographic key management scheme which increases the efficiency and security of the Supervisory Control And Data Acquisition (SCADA) communication. In the proposed key management scheme, two key update phases are used: session key update and master key update. In the session key update phase, session keys are generated in the master station. In the master key update phase, the Elliptic Curve Diffie-Hellman (ECDH) protocol is used. The Poisson process is also used to model the Security Index (SI) and Quality of Service (QoS). Our analysis shows that the proposed key management not only supports the required speed in the MODBUS implementation but also has several advantages compared to other key management schemes for secure communication in SCADA networks. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

On the probability of exceeding allowable leak rates through degraded steam generator tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cizelj, L.; Sorsek, I.; Riesch-Oppermann, H.

1997-02-01

This paper discusses some possible ways of predicting the behavior of the total leak rate through the damaged steam generator tubes. This failure mode is of special concern in cases where most through-wall defects may remain In operation. A particular example is the application of alternate (bobbin coil voltage) plugging criterion to Outside Diameter Stress Corrosion Cracking at the tube support plate intersections. It is the authors aim to discuss some possible modeling options that could be applied to solve the problem formulated as: Estimate the probability that the sum of all individual leak rates through degraded tubes exceeds themore » predefined acceptable value. The probabilistic approach is of course aiming at reliable and computationaly bearable estimate of the failure probability. A closed form solution is given for a special case of exponentially distributed individual leak rates. Also, some possibilities for the use of computationaly efficient First and Second Order Reliability Methods (FORM and SORM) are discussed. The first numerical example compares the results of approximate methods with closed form results. SORM in particular shows acceptable agreement. The second numerical example considers a realistic case of NPP in Krsko, Slovenia.« less

Frequency-doubled microwave waveforms generation using a dual-polarization quadrature phase shift keying modulator driven by a single frequency radio frequency signal

NASA Astrophysics Data System (ADS)

Zhu, Zihang; Zhao, Shanghong; Li, Xuan; Qu, Kun; Lin, Tao

2018-01-01

A photonic approach to generate frequency-doubled microwave waveforms using an integrated dual-polarization quadrature phase shift keying (DP-QPSK) modulator driven by a sinusoidal radio frequency (RF) signal is proposed. By adjusting the dc bias points of the DP-QPSK modulator, the obtained second-order and six-order harmonics are in phase while the fourth-order harmonics are complementary when the orthogonal polarized outputs of the modulator are photodetected. After properly setting the modulation indices of the modulator, the amplitude of the second-order harmonic is 9 times of that of the six-order harmonic, indicating a frequency-doubled triangular waveform is generated. If a broadband 90° microwave phase shifter is attached after the photodetector (PD) to introduce a 90° phase shift, a frequency-doubled square waveform can be obtained after adjusting the amplitude of the second-order harmonic 3 times of that of the six-order harmonic. The proposal is first theoretically analyzed and then validated by simulation. Simulation results show that a 10 GHz triangular and square waveform sequences are successfully generated from a 5 GHz sinusoidal RF drive signal.

Rate-loss analysis of an efficient quantum repeater architecture

NASA Astrophysics Data System (ADS)

Guha, Saikat; Krovi, Hari; Fuchs, Christopher A.; Dutton, Zachary; Slater, Joshua A.; Simon, Christoph; Tittel, Wolfgang

2015-08-01

We analyze an entanglement-based quantum key distribution (QKD) architecture that uses a linear chain of quantum repeaters employing photon-pair sources, spectral-multiplexing, linear-optic Bell-state measurements, multimode quantum memories, and classical-only error correction. Assuming perfect sources, we find an exact expression for the secret-key rate, and an analytical description of how errors propagate through the repeater chain, as a function of various loss-and-noise parameters of the devices. We show via an explicit analytical calculation, which separately addresses the effects of the principle nonidealities, that this scheme achieves a secret-key rate that surpasses the Takeoka-Guha-Wilde bound—a recently found fundamental limit to the rate-vs-loss scaling achievable by any QKD protocol over a direct optical link—thereby providing one of the first rigorous proofs of the efficacy of a repeater protocol. We explicitly calculate the end-to-end shared noisy quantum state generated by the repeater chain, which could be useful for analyzing the performance of other non-QKD quantum protocols that require establishing long-distance entanglement. We evaluate that shared state's fidelity and the achievable entanglement-distillation rate, as a function of the number of repeater nodes, total range, and various loss-and-noise parameters of the system. We extend our theoretical analysis to encompass sources with nonzero two-pair-emission probability, using an efficient exact numerical evaluation of the quantum state propagation and measurements. We expect our results to spur formal rate-loss analysis of other repeater protocols and also to provide useful abstractions to seed analyses of quantum networks of complex topologies.

Bryophytes for Beginners: The Usability of a Printed Dichotomous Key versus a Multi-Access Computer-Based Key for Bryophyte Identification

ERIC Educational Resources Information Center

Stagg, Bethan C.; Donkin, Maria E.; Smith, Alison M.

2015-01-01

Bryophytes are a rewarding study group in field biology and the UK bryophyte flora has international importance to biodiversity conservation. We designed an identification key to common woodland moss species and compared the usability of two formats, web-based multi-access and printed dichotomous key, with undergraduate students. The rate of…

Design and implementation of an optical Gaussian noise generator

NASA Astrophysics Data System (ADS)

Za~O, Leonardo; Loss, Gustavo; Coelho, Rosângela

2009-08-01

A design of a fast and accurate optical Gaussian noise generator is proposed and demonstrated. The noise sample generation is based on the Box-Muller algorithm. The functions implementation was performed on a high-speed Altera Stratix EP1S25 field-programmable gate array (FPGA) development kit. It enabled the generation of 150 million 16-bit noise samples per second. The Gaussian noise generator required only 7.4% of the FPGA logic elements, 1.2% of the RAM memory, 0.04% of the ROM memory, and a laser source. The optical pulses were generated by a laser source externally modulated by the data bit samples using the frequency-shift keying technique. The accuracy of the noise samples was evaluated for different sequences size and confidence intervals. The noise sample pattern was validated by the Bhattacharyya distance (Bd) and the autocorrelation function. The results showed that the proposed design of the optical Gaussian noise generator is very promising to evaluate the performance of optical communications channels with very low bit-error-rate values.

Minimal-post-processing 320-Gbps true random bit generation using physical white chaos.

PubMed

Wang, Anbang; Wang, Longsheng; Li, Pu; Wang, Yuncai

2017-02-20

Chaotic external-cavity semiconductor laser (ECL) is a promising entropy source for generation of high-speed physical random bits or digital keys. The rate and randomness is unfortunately limited by laser relaxation oscillation and external-cavity resonance, and is usually improved by complicated post processing. Here, we propose using a physical broadband white chaos generated by optical heterodyning of two ECLs as entropy source to construct high-speed random bit generation (RBG) with minimal post processing. The optical heterodyne chaos not only has a white spectrum without signature of relaxation oscillation and external-cavity resonance but also has a symmetric amplitude distribution. Thus, after quantization with a multi-bit analog-digital-convertor (ADC), random bits can be obtained by extracting several least significant bits (LSBs) without any other processing. In experiments, a white chaos with a 3-dB bandwidth of 16.7 GHz is generated. Its entropy rate is estimated as 16 Gbps by single-bit quantization which means a spectrum efficiency of 96%. With quantization using an 8-bit ADC, 320-Gbps physical RBG is achieved by directly extracting 4 LSBs at 80-GHz sampling rate.

Hazardous medical waste generation rates of different categories of health-care facilities.

PubMed

Komilis, Dimitrios; Fouki, Anastassia; Papadopoulos, Dimitrios

2012-07-01

Goal of this work was to calculate the hazardous medical waste unit generation rates (HMWUGR), in kg bed(-1)d(-1), using data from 132 health-care facilities in Greece. The calculations were based on the weights of the hazardous medical wastes that were regularly transferred to the sole medical waste incinerator in Athens over a 22-month period during years 2009 and 2010. The 132 health-care facilities were grouped into public and private ones, and, also, into seven sub-categories, namely: birth, cancer treatment, general, military, pediatric, psychiatric and university hospitals. Results showed that there is a large variability in the HMWUGR, even among hospitals of the same category. Average total HMWUGR varied from 0.012 kg bed(-1)d(-1), for the public psychiatric hospitals, to up to 0.72 kg bed(-1)d(-1), for the public university hospitals. Within the private hospitals, average HMWUGR ranged from 0.0012 kg bed(-1)d(-1), for the psychiatric clinics, to up to 0.49 kg bed(-1)d(-1), for the birth clinics. Based on non-parametric statistics, HMWUGR were statistically similar for the birth and general hospitals, in both the public and private sector. The private birth and general hospitals generated statistically more wastes compared to the corresponding public hospitals. The infectious/toxic and toxic medical wastes appear to be 10% and 50% of the total hazardous medical wastes generated by the public cancer treatment and university hospitals, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

The tropical Pacific as a key pacemaker of the variable rates of global warming

NASA Astrophysics Data System (ADS)

Kosaka, Yu; Xie, Shang-Ping

2016-09-01

Global mean surface temperature change over the past 120 years resembles a rising staircase: the overall warming trend was interrupted by the mid-twentieth-century big hiatus and the warming slowdown since about 1998. The Interdecadal Pacific Oscillation has been implicated in modulations of global mean surface temperatures, but which part of the mode drives the variability in warming rates is unclear. Here we present a successful simulation of the global warming staircase since 1900 with a global ocean-atmosphere coupled model where tropical Pacific sea surface temperatures are forced to follow the observed evolution. Without prescribed tropical Pacific variability, the same model, on average, produces a continual warming trend that accelerates after the 1960s. We identify four events where the tropical Pacific decadal cooling markedly slowed down the warming trend. Matching the observed spatial and seasonal fingerprints we identify the tropical Pacific as a key pacemaker of the warming staircase, with radiative forcing driving the overall warming trend. Specifically, tropical Pacific variability amplifies the first warming epoch of the 1910s-1940s and determines the timing when the big hiatus starts and ends. Our method of removing internal variability from the observed record can be used for real-time monitoring of anthropogenic warming.

Finite-key security analysis of quantum key distribution with imperfect light sources

DOE PAGES

Mizutani, Akihiro; Curty, Marcos; Lim, Charles Ci Wen; ...

2015-09-09

In recent years, the gap between theory and practice in quantum key distribution (QKD) has been significantly narrowed, particularly for QKD systems with arbitrarily flawed optical receivers. The status for QKD systems with imperfect light sources is however less satisfactory, in the sense that the resulting secure key rates are often overly dependent on the quality of state preparation. This is especially the case when the channel loss is high. Very recently, to overcome this limitation, Tamaki et al proposed a QKD protocol based on the so-called 'rejected data analysis', and showed that its security in the limit of infinitelymore » long keys is almost independent of any encoding flaw in the qubit space, being this protocol compatible with the decoy state method. Here, as a step towards practical QKD, we show that a similar conclusion is reached in the finite-key regime, even when the intensity of the light source is unstable. More concretely, we derive security bounds for a wide class of realistic light sources and show that the bounds are also efficient in the presence of high channel loss. Our results strongly suggest the feasibility of long distance provably secure communication with imperfect light sources.« less

Quadrature-quadrature phase-shift keying

NASA Astrophysics Data System (ADS)

Saha, Debabrata; Birdsall, Theodore G.

1989-05-01

Quadrature-quadrature phase-shift keying (Q2PSK) is a spectrally efficient modulation scheme which utilizes available signal space dimensions in a more efficient way than two-dimensional schemes such as QPSK and MSK (minimum-shift keying). It uses two data shaping pulses and two carriers, which are pairwise quadrature in phase, to create a four-dimensional signal space and increases the transmission rate by a factor of two over QPSK and MSK. However, the bit error rate performance depends on the choice of pulse pair. With simple sinusoidal and cosinusoidal data pulses, the Eb/N0 requirement for Pb(E) = 10 to the -5 is approximately 1.6 dB higher than that of MSK. Without additional constraints, Q2PSK does not maintain constant envelope. However, a simple block coding provides a constant envelope. This coded signal substantially outperforms MSKS and TFM (time-frequency multiplexing) in bandwidth efficiency. Like MSK, Q2PSK also has self-clocking and self-synchronizing ability. An optimum class of pulse shapes for use in Q2PSK-format is presented. One suboptimum realization achieves the Nyquist rate of 2 bits/s/Hz using binary detection.

Coseismic Damage Generation in Fault Zones by Successive High Strain Rate Loading Experiments

NASA Astrophysics Data System (ADS)

Aben, F. M.; Doan, M. L.; Renard, F.; Toussaint, R.; Reuschlé, T.; Gratier, J. P.

2014-12-01

Damage zones of active faults control both resistance to rupture and transport properties of the fault. Hence, knowing the rock damage's origin is important to constrain its properties. Here we study experimentally the damage generated by a succession of dynamic loadings, a process mimicking the stress history of a rock sample located next to an active fault. A propagating rupture generates high frequency stress perturbations next to its tip. This dynamic loading creates pervasive damage (pulverization), as multiple fractures initiate and grow simultaneously. Previous single loading experiments have shown a strain rate threshold for pulverization. Here, we focus on conditions below this threshold and the dynamic peak stress to constrain: 1) if there is dynamic fracturing at these conditions and 2) if successive loadings (cumulative seismic events) result in pervasive fracturing, effectively reducing the pulverization threshold to milder conditions. Monzonite samples were dynamically loaded (strain rate > 50 s-1) several times below the dynamic peak strength, using a Split Hopkinson Pressure Bar apparatus. Several quasi-static experiments were conducted as well (strain rate < 10-5-s). Samples loaded up to stresses above the quasi-static uniaxial compressive strength (qsUCS) systematically fragmented or pulverized after four successive loadings. We measured several damage proxies (P-wave velocity, porosity), that show a systematic increase in damage with each load. In addition, micro-computed tomography acquisition on several damage samples revealed the growth of a pervasive fracture network between ensuing loadings. Samples loaded dynamically below the qsUCS failed along one fracture after a variable amount of loadings and damage proxies do not show any a systematic trend. Our conclusions is that milder dynamic loading conditions, below the dynamic peak strength, result in pervasive dynamic fracturing. Also, successive loadings effectively lower the pulverization

Patients' Data Management System Protected by Identity-Based Authentication and Key Exchange.

PubMed

Rivero-García, Alexandra; Santos-González, Iván; Hernández-Goya, Candelaria; Caballero-Gil, Pino; Yung, Moti

2017-03-31

A secure and distributed framework for the management of patients' information in emergency and hospitalization services is proposed here in order to seek improvements in efficiency and security in this important area. In particular, confidentiality protection, mutual authentication, and automatic identification of patients are provided. The proposed system is based on two types of devices: Near Field Communication (NFC) wristbands assigned to patients, and mobile devices assigned to medical staff. Two other main elements of the system are an intermediate server to manage the involved data, and a second server with a private key generator to define the information required to protect communications. An identity-based authentication and key exchange scheme is essential to provide confidential communication and mutual authentication between the medical staff and the private key generator through an intermediate server. The identification of patients is carried out through a keyed-hash message authentication code. Thanks to the combination of the aforementioned tools, a secure alternative mobile health (mHealth) scheme for managing patients' data is defined for emergency and hospitalization services. Different parts of the proposed system have been implemented, including mobile application, intermediate server, private key generator and communication channels. Apart from that, several simulations have been performed, and, compared with the current system, significant improvements in efficiency have been observed.

Experimental Measurement-Device-Independent Quantum Key Distribution

NASA Astrophysics Data System (ADS)

Liu, Yang; Chen, Teng-Yun; Wang, Liu-Jun; Liang, Hao; Shentu, Guo-Liang; Wang, Jian; Cui, Ke; Yin, Hua-Lei; Liu, Nai-Le; Li, Li; Ma, Xiongfeng; Pelc, Jason S.; Fejer, M. M.; Peng, Cheng-Zhi; Zhang, Qiang; Pan, Jian-Wei

2013-09-01

Quantum key distribution is proven to offer unconditional security in communication between two remote users with ideal source and detection. Unfortunately, ideal devices never exist in practice and device imperfections have become the targets of various attacks. By developing up-conversion single-photon detectors with high efficiency and low noise, we faithfully demonstrate the measurement-device-independent quantum-key-distribution protocol, which is immune to all hacking strategies on detection. Meanwhile, we employ the decoy-state method to defend attacks on a nonideal source. By assuming a trusted source scenario, our practical system, which generates more than a 25 kbit secure key over a 50 km fiber link, serves as a stepping stone in the quest for unconditionally secure communications with realistic devices.

Experimental measurement-device-independent quantum key distribution.

PubMed

Liu, Yang; Chen, Teng-Yun; Wang, Liu-Jun; Liang, Hao; Shentu, Guo-Liang; Wang, Jian; Cui, Ke; Yin, Hua-Lei; Liu, Nai-Le; Li, Li; Ma, Xiongfeng; Pelc, Jason S; Fejer, M M; Peng, Cheng-Zhi; Zhang, Qiang; Pan, Jian-Wei

2013-09-27

Quantum key distribution is proven to offer unconditional security in communication between two remote users with ideal source and detection. Unfortunately, ideal devices never exist in practice and device imperfections have become the targets of various attacks. By developing up-conversion single-photon detectors with high efficiency and low noise, we faithfully demonstrate the measurement-device-independent quantum-key-distribution protocol, which is immune to all hacking strategies on detection. Meanwhile, we employ the decoy-state method to defend attacks on a nonideal source. By assuming a trusted source scenario, our practical system, which generates more than a 25 kbit secure key over a 50 km fiber link, serves as a stepping stone in the quest for unconditionally secure communications with realistic devices.

Memory for melody and key in childhood

PubMed Central

Poon, Jaimie; Weiss, Michael W.

2017-01-01

After only two exposures to previously unfamiliar melodies, adults remember the tunes for over a week and the key for over a day. Here, we examined the development of long-term memory for melody and key. Listeners in three age groups (7- to 8-year-olds, 9- to 11-year-olds, and adults) heard two presentations of each of 12 unfamiliar melodies. After a 10-min delay, they heard the same 12 old melodies intermixed with 12 new melodies. Half of the old melodies were transposed up or down by six semitones from initial exposure. Listeners rated how well they recognized the melodies from the exposure phase. Recognition was better for old than for new melodies, for adults compared to children, and for older compared to younger children. Recognition ratings were also higher for old melodies presented in the same key at test as exposure, and the detrimental effect of the transposition affected all age groups similarly. Although memory for melody improves with age and exposure to music, implicit memory for key appears to be adult-like by 7 years of age. PMID:29077726

Summary on several key techniques in 3D geological modeling.

PubMed

Mei, Gang

2014-01-01

Several key techniques in 3D geological modeling including planar mesh generation, spatial interpolation, and surface intersection are summarized in this paper. Note that these techniques are generic and widely used in various applications but play a key role in 3D geological modeling. There are two essential procedures in 3D geological modeling: the first is the simulation of geological interfaces using geometric surfaces and the second is the building of geological objects by means of various geometric computations such as the intersection of surfaces. Discrete geometric surfaces that represent geological interfaces can be generated by creating planar meshes first and then spatially interpolating; those surfaces intersect and then form volumes that represent three-dimensional geological objects such as rock bodies. In this paper, the most commonly used algorithms of the key techniques in 3D geological modeling are summarized.

Summary on Several Key Techniques in 3D Geological Modeling

PubMed Central

2014-01-01

Several key techniques in 3D geological modeling including planar mesh generation, spatial interpolation, and surface intersection are summarized in this paper. Note that these techniques are generic and widely used in various applications but play a key role in 3D geological modeling. There are two essential procedures in 3D geological modeling: the first is the simulation of geological interfaces using geometric surfaces and the second is the building of geological objects by means of various geometric computations such as the intersection of surfaces. Discrete geometric surfaces that represent geological interfaces can be generated by creating planar meshes first and then spatially interpolating; those surfaces intersect and then form volumes that represent three-dimensional geological objects such as rock bodies. In this paper, the most commonly used algorithms of the key techniques in 3D geological modeling are summarized. PMID:24772029

Generation of hazardous methyl azide and its application to synthesis of a key-intermediate of picarbutrazox, a new potent pesticide in flow.

PubMed

Ichinari, Daisuke; Nagaki, Aiichiro; Yoshida, Jun-Ichi

2017-12-01

Generation and reactions of methyl azide (MeN 3 ) were successfully performed by using a flow reactor system, demonstrating that the flow method serves as a safe method for handling hazardous explosive methyl azide. The reaction of NaN 3 and Me 2 SO 4 in a flow reactor gave a MeN 3 solution, which was used for Huisgen reaction with benzoyl cyanide in a flow reactor after minimal washing. The resulting 1-methyl-5-benzoyltetrazole serves as a key intermediate of picarbutrazox (IX), a new potent pesticide. Copyright © 2017. Published by Elsevier Ltd.

Quantum key distribution using gaussian-modulated coherent states

NASA Astrophysics Data System (ADS)

Grosshans, Frédéric; Van Assche, Gilles; Wenger, Jérôme; Brouri, Rosa; Cerf, Nicolas J.; Grangier, Philippe

2003-01-01

Quantum continuous variables are being explored as an alternative means to implement quantum key distribution, which is usually based on single photon counting. The former approach is potentially advantageous because it should enable higher key distribution rates. Here we propose and experimentally demonstrate a quantum key distribution protocol based on the transmission of gaussian-modulated coherent states (consisting of laser pulses containing a few hundred photons) and shot-noise-limited homodyne detection; squeezed or entangled beams are not required. Complete secret key extraction is achieved using a reverse reconciliation technique followed by privacy amplification. The reverse reconciliation technique is in principle secure for any value of the line transmission, against gaussian individual attacks based on entanglement and quantum memories. Our table-top experiment yields a net key transmission rate of about 1.7 megabits per second for a loss-free line, and 75 kilobits per second for a line with losses of 3.1dB. We anticipate that the scheme should remain effective for lines with higher losses, particularly because the present limitations are essentially technical, so that significant margin for improvement is available on both the hardware and software.

The Efficacy of Key Performance Indicators in Ontario Universities as Perceived by Key Informants

ERIC Educational Resources Information Center

Chan, Vivian

2015-01-01

The Ontario Ministry of Education and Training's Task Force on University Accountability first proposed key performance indicators (KPIs) for colleges and universities in Ontario in the early 1990s. The three main KPIs for Ontario universities are the rates of (1) graduation, (2) employment, and (3) Ontario Student Assistance Program loan default.…

Impact-generated Tsunamis: An Over-rated Hazard

NASA Technical Reports Server (NTRS)

Melosh, H. J.

2003-01-01

A number of authors have suggested that oceanic waves (tsunami) created by the impact of relatively small asteroids into the Earth's oceans might cause widespread devastation to coastal cities. If correct, this suggests that asteroids > 100 m in diameter may pose a serious hazard to humanity and could require a substantial expansion of the current efforts to identify earth-crossing asteroids > 1 km in diameter. The debate on this hazard was recently altered by the release of a document previously inaccessible to the scientific community. In 1968 the US Office of Naval Research commissioned a summary of several decades of research into the hazard proposed by waves generated by nuclear explosions in the ocean. Authored by tsunami expert William Van Dorn, this 173-page report entitled Handbook of Explosion-Generated Water Waves affords new insight into the process of impact wave formation, propagation, and run up onto the shoreline.

Experimental quantum key distribution with simulated ground-to-satellite photon losses and processing limitations

NASA Astrophysics Data System (ADS)

Bourgoin, Jean-Philippe; Gigov, Nikolay; Higgins, Brendon L.; Yan, Zhizhong; Meyer-Scott, Evan; Khandani, Amir K.; Lütkenhaus, Norbert; Jennewein, Thomas

2015-11-01

Quantum key distribution (QKD) has the potential to improve communications security by offering cryptographic keys whose security relies on the fundamental properties of quantum physics. The use of a trusted quantum receiver on an orbiting satellite is the most practical near-term solution to the challenge of achieving long-distance (global-scale) QKD, currently limited to a few hundred kilometers on the ground. This scenario presents unique challenges, such as high photon losses and restricted classical data transmission and processing power due to the limitations of a typical satellite platform. Here we demonstrate the feasibility of such a system by implementing a QKD protocol, with optical transmission and full post-processing, in the high-loss regime using minimized computing hardware at the receiver. Employing weak coherent pulses with decoy states, we demonstrate the production of secure key bits at up to 56.5 dB of photon loss. We further illustrate the feasibility of a satellite uplink by generating a secure key while experimentally emulating the varying losses predicted for realistic low-Earth-orbit satellite passes at 600 km altitude. With a 76 MHz source and including finite-size analysis, we extract 3374 bits of a secure key from the best pass. We also illustrate the potential benefit of combining multiple passes together: while one suboptimal "upper-quartile" pass produces no finite-sized key with our source, the combination of three such passes allows us to extract 165 bits of a secure key. Alternatively, we find that by increasing the signal rate to 300 MHz it would be possible to extract 21 570 bits of a secure finite-sized key in just a single upper-quartile pass.

High-Speed Large-Alphabet Quantum Key Distribution Using Photonic Integrated Circuits

DTIC Science & Technology

2014-01-28

polarizing beam splitter, TDC: time-to-digital converter. Extra&loss& photon/bin frame size QSER secure bpp ECC secure&key&rate& none& 0.0031 64 14...to-digital converter. photon/frame frame size QSER secure bpp ECC secure&key& rate& 1.3 16 9.5 % 2.9 layered LDPC 7.3&Mbps& Figure 24: Operating

Kinetic coupling of phosphate release, force generation and rate-limiting steps in the cross-bridge cycle.

PubMed

Stehle, Robert; Tesi, Chiara

2017-08-01

A basic goal in muscle research is to understand how the cyclic ATPase activity of cross-bridges is converted into mechanical force. A direct approach to study the chemo-mechanical coupling between P i release and the force-generating step is provided by the kinetics of force response induced by a rapid change in [P i ]. Classical studies on fibres using caged-P i discovered that rapid increases in [P i ] induce fast force decays dependent on final [P i ] whose kinetics were interpreted to probe a fast force-generating step prior to P i release. However, this hypothesis was called into question by studies on skeletal and cardiac myofibrils subjected to P i jumps in both directions (increases and decreases in [P i ]) which revealed that rapid decreases in [P i ] trigger force rises with slow kinetics, similar to those of calcium-induced force development and mechanically-induced force redevelopment at the same [P i ]. A possible explanation for this discrepancy came from imaging of individual sarcomeres in cardiac myofibrils, showing that the fast force decay upon increase in [P i ] results from so-called sarcomere 'give'. The slow force rise upon decrease in [P i ] was found to better reflect overall sarcomeres cross-bridge kinetics and its [P i ] dependence, suggesting that the force generation coupled to P i release cannot be separated from the rate-limiting transition. The reasons for the different conclusions achieved in fibre and myofibril studies are re-examined as the recent findings on cardiac myofibrils have fundamental consequences for the coupling between P i release, rate-limiting steps and force generation. The implications from P i -induced force kinetics of myofibrils are discussed in combination with historical and recent models of the cross-bridge cycle.

Adaptive spatial filtering of daytime sky noise in a satellite quantum key distribution downlink receiver

NASA Astrophysics Data System (ADS)

Gruneisen, Mark T.; Sickmiller, Brett A.; Flanagan, Michael B.; Black, James P.; Stoltenberg, Kurt E.; Duchane, Alexander W.

2016-02-01

Spatial filtering is an important technique for reducing sky background noise in a satellite quantum key distribution downlink receiver. Atmospheric turbulence limits the extent to which spatial filtering can reduce sky noise without introducing signal losses. Using atmospheric propagation and compensation simulations, the potential benefit of adaptive optics (AO) to secure key generation (SKG) is quantified. Simulations are performed assuming optical propagation from a low-Earth-orbit satellite to a terrestrial receiver that includes AO. Higher-order AO correction is modeled assuming a Shack-Hartmann wavefront sensor and a continuous-face-sheet deformable mirror. The effects of atmospheric turbulence, tracking, and higher-order AO on the photon capture efficiency are simulated using statistical representations of turbulence and a time-domain wave-optics hardware emulator. SKG rates are calculated for a decoy-state protocol as a function of the receiver field of view for various strengths of turbulence, sky radiances, and pointing angles. The results show that at fields of view smaller than those discussed by others, AO technologies can enhance SKG rates in daylight and enable SKG where it would otherwise be prohibited as a consequence of background optical noise and signal loss due to propagation and turbulence effects.

Variable speed generator technology options for wind turbine generators

NASA Technical Reports Server (NTRS)

Lipo, T. A.

1995-01-01

The electrical system options for variable speed operation of a wind turbine generator are treated in this paper. The key operating characteristics of each system are discussed and the major advantages and disadvantages of each are identified

Simple 2.5 GHz time-bin quantum key distribution

NASA Astrophysics Data System (ADS)

Boaron, Alberto; Korzh, Boris; Houlmann, Raphael; Boso, Gianluca; Rusca, Davide; Gray, Stuart; Li, Ming-Jun; Nolan, Daniel; Martin, Anthony; Zbinden, Hugo

2018-04-01

We present a 2.5 GHz quantum key distribution setup with the emphasis on a simple experimental realization. It features a three-state time-bin protocol based on a pulsed diode laser and a single intensity modulator. Implementing an efficient one-decoy scheme and finite-key analysis, we achieve record breaking secret key rates of 1.5 kbps over 200 km of standard optical fibers.

Self-referenced continuous-variable quantum key distribution protocol

DOE PAGES

Soh, Daniel Beom Soo; Sarovar, Mohan; Brif, Constantin; ...

2015-10-21

We introduce a new continuous-variable quantum key distribution (CV-QKD) protocol, self-referenced CV-QKD, that eliminates the need for transmission of a high-power local oscillator between the communicating parties. In this protocol, each signal pulse is accompanied by a reference pulse (or a pair of twin reference pulses), used to align Alice’s and Bob’s measurement bases. The method of phase estimation and compensation based on the reference pulse measurement can be viewed as a quantum analog of intradyne detection used in classical coherent communication, which extracts the phase information from the modulated signal. We present a proof-of-principle, fiber-based experimental demonstration of themore » protocol and quantify the expected secret key rates by expressing them in terms of experimental parameters. Our analysis of the secret key rate fully takes into account the inherent uncertainty associated with the quantum nature of the reference pulse(s) and quantifies the limit at which the theoretical key rate approaches that of the respective conventional protocol that requires local oscillator transmission. The self-referenced protocol greatly simplifies the hardware required for CV-QKD, especially for potential integrated photonics implementations of transmitters and receivers, with minimum sacrifice of performance. Furthermore, it provides a pathway towards scalable integrated CV-QKD transceivers, a vital step towards large-scale QKD networks.« less

Self-referenced continuous-variable quantum key distribution protocol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soh, Daniel Beom Soo; Sarovar, Mohan; Brif, Constantin

We introduce a new continuous-variable quantum key distribution (CV-QKD) protocol, self-referenced CV-QKD, that eliminates the need for transmission of a high-power local oscillator between the communicating parties. In this protocol, each signal pulse is accompanied by a reference pulse (or a pair of twin reference pulses), used to align Alice’s and Bob’s measurement bases. The method of phase estimation and compensation based on the reference pulse measurement can be viewed as a quantum analog of intradyne detection used in classical coherent communication, which extracts the phase information from the modulated signal. We present a proof-of-principle, fiber-based experimental demonstration of themore » protocol and quantify the expected secret key rates by expressing them in terms of experimental parameters. Our analysis of the secret key rate fully takes into account the inherent uncertainty associated with the quantum nature of the reference pulse(s) and quantifies the limit at which the theoretical key rate approaches that of the respective conventional protocol that requires local oscillator transmission. The self-referenced protocol greatly simplifies the hardware required for CV-QKD, especially for potential integrated photonics implementations of transmitters and receivers, with minimum sacrifice of performance. Furthermore, it provides a pathway towards scalable integrated CV-QKD transceivers, a vital step towards large-scale QKD networks.« less

Self-Referenced Continuous-Variable Quantum Key Distribution Protocol

NASA Astrophysics Data System (ADS)

Soh, Daniel B. S.; Brif, Constantin; Coles, Patrick J.; Lütkenhaus, Norbert; Camacho, Ryan M.; Urayama, Junji; Sarovar, Mohan

2015-10-01

We introduce a new continuous-variable quantum key distribution (CV-QKD) protocol, self-referenced CV-QKD, that eliminates the need for transmission of a high-power local oscillator between the communicating parties. In this protocol, each signal pulse is accompanied by a reference pulse (or a pair of twin reference pulses), used to align Alice's and Bob's measurement bases. The method of phase estimation and compensation based on the reference pulse measurement can be viewed as a quantum analog of intradyne detection used in classical coherent communication, which extracts the phase information from the modulated signal. We present a proof-of-principle, fiber-based experimental demonstration of the protocol and quantify the expected secret key rates by expressing them in terms of experimental parameters. Our analysis of the secret key rate fully takes into account the inherent uncertainty associated with the quantum nature of the reference pulse(s) and quantifies the limit at which the theoretical key rate approaches that of the respective conventional protocol that requires local oscillator transmission. The self-referenced protocol greatly simplifies the hardware required for CV-QKD, especially for potential integrated photonics implementations of transmitters and receivers, with minimum sacrifice of performance. As such, it provides a pathway towards scalable integrated CV-QKD transceivers, a vital step towards large-scale QKD networks.

A pilot study to determine medical laser generated air contaminant emission rates for a simulated surgical procedure.

PubMed

Lippert, Julia F; Lacey, Steven E; Lopez, Ramon; Franke, John; Conroy, Lorraine; Breskey, John; Esmen, Nurtan; Liu, Li

2014-01-01

The U.S. Occupational Safety and Health Administration (OSHA) estimates that half a million health-care workers are exposed to laser surgical smoke each year. The purpose of this study was to establish a methodology to (1) estimate emission rates of laser-generated air contaminants (LGACs) using an emission chamber, and to (2) perform a screening study to differentiate the effects of three laser operational parameters. An emission chamber was designed, fabricated, and assessed for performance to estimate the emission rates of gases and particles associated with LGACs during a simulated surgical procedure. Two medical lasers (Holmium Yttrium Aluminum Garnet [Ho:YAG] and carbon dioxide [CO2]) were set to a range of plausible medical laser operational parameters in a simulated surgery to pyrolyze porcine skin generating plume in the emission chamber. Power, pulse repetition frequency (PRF), and beam diameter were evaluated to determine the effect of each operational parameter on emission rate using a fractional factorial design. The plume was sampled for particulate matter and seven gas phase combustion byproduct contaminants (benzene, ethylbenzene, toluene, formaldehyde, hydrogen cyanide, carbon dioxide, and carbon monoxide): the gas phase emission results are presented here. Most of the measured concentrations of gas phase contaminants were below their limit of detection (LOD), but detectable measurements enabled us to determine laser operation parameter influence on CO2 emissions. Confined to the experimental conditions of this screening study, results indicated that beam diameter was statistically significantly influential and power was marginally statistically significant to emission rates of CO2 when using the Ho:YAG laser but not with the carbon dioxide laser; PRF was not influential vis-a-vis emission rates of these gas phase contaminants.

Seaworthy Quantum Key Distribution Design and Validation (SEAKEY)

DTIC Science & Technology

2016-03-10

Contractor Address: 10 Moulton Street, Cambridge, MA 02138 Title of the Project: Seaworthy Quantum Key Distribution Design and Validation (SEAKEY...Technologies Kathryn Carson Program Manager Quantum Information Processing 2 | P a g e Approved for public release; distribution is...we have continued work calculating the key rates achievable parametrically with receiver performance. In addition, we describe the initial designs

Time Delay Measurements of Key Generation Process on Smart Cards

DTIC Science & Technology

2015-03-01

random number generator is available (Chatterjee & Gupta, 2009). The ECC algorithm will grow in usage as information becomes more and more secure. Figure...Worldwide Mobile Enterprise Security Software 2012–2016 Forecast and Analysis), mobile identity and access management is expected to grow by 27.6 percent...iPad, tablets) as well as 80000 BlackBerry phones. The mobility plan itself will be deployed in three phases over 2014, with the first phase

Patients’ Data Management System Protected by Identity-Based Authentication and Key Exchange

PubMed Central

Rivero-García, Alexandra; Santos-González, Iván; Hernández-Goya, Candelaria; Caballero-Gil, Pino; Yung, Moti

2017-01-01

A secure and distributed framework for the management of patients’ information in emergency and hospitalization services is proposed here in order to seek improvements in efficiency and security in this important area. In particular, confidentiality protection, mutual authentication, and automatic identification of patients are provided. The proposed system is based on two types of devices: Near Field Communication (NFC) wristbands assigned to patients, and mobile devices assigned to medical staff. Two other main elements of the system are an intermediate server to manage the involved data, and a second server with a private key generator to define the information required to protect communications. An identity-based authentication and key exchange scheme is essential to provide confidential communication and mutual authentication between the medical staff and the private key generator through an intermediate server. The identification of patients is carried out through a keyed-hash message authentication code. Thanks to the combination of the aforementioned tools, a secure alternative mobile health (mHealth) scheme for managing patients’ data is defined for emergency and hospitalization services. Different parts of the proposed system have been implemented, including mobile application, intermediate server, private key generator and communication channels. Apart from that, several simulations have been performed, and, compared with the current system, significant improvements in efficiency have been observed. PMID:28362328

Operational and Strategic Implementation of Dynamic Line Rating for Optimized Wind Energy Generation Integration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gentle, Jake Paul

2016-12-01

One primary goal of rendering today’s transmission grid “smarter” is to optimize and better manage its power transfer capacity in real time. Power transfer capacity is affected by three main elements: stability, voltage limits, and thermal ratings. All three are critical, but thermal ratings represent the greatest opportunity to quickly, reliably and economically utilize the grid’s true capacity. With the “Smarter Grid”, new solutions have been sought to give operators a better grasp on real time conditions, allowing them to manage and extend the usefulness of existing transmission infrastructure in a safe and reliable manner. The objective of the INLmore » Wind Program is to provide industry a Dynamic Line Rating (DLR) solution that is state of the art as measured by cost, accuracy and dependability, to enable human operators to make informed decisions and take appropriate actions without human or system overloading and impacting the reliability of the grid. In addition to mitigating transmission line congestion to better integrate wind, DLR also offers the opportunity to improve the grid with optimized utilization of transmission lines to relieve congestion in general. As wind-generated energy has become a bigger part of the nation’s energy portfolio, researchers have learned that wind not only turns turbine blades to generate electricity, but can cool transmission lines and increase transfer capabilities significantly, sometimes up to 60 percent. INL’s DLR development supports EERE and The Wind Energy Technology Office’s goals by informing system planners and grid operators of available transmission capacity, beyond typical Static Line Ratings (SLR). SLRs are based on a fixed set of conservative environmental conditions to establish a limit on the amount of current lines can safely carry without overheating. Using commercially available weather monitors mounted on industry informed custom brackets developed by INL in combination with

A comparison of the rates of hydrocarbon generation from Lodgepole, False Bakken, and Bakken formation petroleum source rocks, Williston Basin, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarvie, D.M.; Elsinger, R.J.; Inden, R.F.

1996-06-01

Recent successes in the Lodgepole Waulsortian Mound play have resulted in the reevaluation of the Williston Basin petroleum systems. It has been postulated that hydrocarbons were generated from organic-rich Bakken Formation source rocks in the Williston Basin. However, Canadian geoscientists have indicated that the Lodgepole Formation is responsible for oil entrapped in Lodgepole Formation and other Madison traps in portions of the Canadian Williston Basin. Furthermore, geoscientists in the U.S. have recently shown oils from mid-Madison conventional reservoirs in the U.S. Williston Basin were not derived from Bakken Formation source rocks. Kinetic data showing the rate of hydrocarbon formation frommore » petroleum source rocks were measured on source rocks from the Lodgepole, False Bakken, and Bakken Formations. These results show a wide range of values in the rate of hydrocarbon generation. Oil prone facies within the Lodgepole Formation tend to generate hydrocarbons earlier than the oil prone facies in the Bakken Formation and mixed oil/gas prone and gas prone facies in the Lodgepole Formation. A comparison of these source rocks using a geological model of hydrocarbon generation reveals differences in the timing of generation and the required level of maturity to generate significant amounts of hydrocarbons.« less

Impact of the High Flux Isotope Reactor HEU to LEU Fuel Conversion on Cold Source Nuclear Heat Generation Rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandler, David

2014-03-01

Under the sponsorship of the US Department of Energy National Nuclear Security Administration, staff members at the Oak Ridge National Laboratory have been conducting studies to determine whether the High Flux Isotope Reactor (HFIR) can be converted from high enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. As part of these ongoing studies, an assessment of the impact that the HEU to LEU fuel conversion has on the nuclear heat generation rates in regions of the HFIR cold source system and its moderator vessel was performed and is documented in this report. Silicon production rates in the coldmore » source aluminum regions and few-group neutron fluxes in the cold source moderator were also estimated. Neutronics calculations were performed with the Monte Carlo N-Particle code to determine the nuclear heat generation rates in regions of the HFIR cold source and its vessel for the HEU core operating at a full reactor power (FP) of 85 MW(t) and the reference LEU core operating at an FP of 100 MW(t). Calculations were performed with beginning-of-cycle (BOC) and end-of-cycle (EOC) conditions to bound typical irradiation conditions. Average specific BOC heat generation rates of 12.76 and 12.92 W/g, respectively, were calculated for the hemispherical region of the cold source liquid hydrogen (LH2) for the HEU and LEU cores, and EOC heat generation rates of 13.25 and 12.86 W/g, respectively, were calculated for the HEU and LEU cores. Thus, the greatest heat generation rates were calculated for the EOC HEU core, and it is concluded that the conversion from HEU to LEU fuel and the resulting increase of FP from 85 MW to 100 MW will not impact the ability of the heat removal equipment to remove the heat deposited in the cold source system. Silicon production rates in the cold source aluminum regions are estimated to be about 12.0% greater at BOC and 2.7% greater at EOC for the LEU core in comparison to the HEU core. Silicon is aluminum s major transmutation

An Efficient Biometric-Based Algorithm Using Heart Rate Variability for Securing Body Sensor Networks.

PubMed

Pirbhulal, Sandeep; Zhang, Heye; Mukhopadhyay, Subhas Chandra; Li, Chunyue; Wang, Yumei; Li, Guanglin; Wu, Wanqing; Zhang, Yuan-Ting

2015-06-26

Body Sensor Network (BSN) is a network of several associated sensor nodes on, inside or around the human body to monitor vital signals, such as, Electroencephalogram (EEG), Photoplethysmography (PPG), Electrocardiogram (ECG), etc. Each sensor node in BSN delivers major information; therefore, it is very significant to provide data confidentiality and security. All existing approaches to secure BSN are based on complex cryptographic key generation procedures, which not only demands high resource utilization and computation time, but also consumes large amount of energy, power and memory during data transmission. However, it is indispensable to put forward energy efficient and computationally less complex authentication technique for BSN. In this paper, a novel biometric-based algorithm is proposed, which utilizes Heart Rate Variability (HRV) for simple key generation process to secure BSN. Our proposed algorithm is compared with three data authentication techniques, namely Physiological Signal based Key Agreement (PSKA), Data Encryption Standard (DES) and Rivest Shamir Adleman (RSA). Simulation is performed in Matlab and results suggest that proposed algorithm is quite efficient in terms of transmission time utilization, average remaining energy and total power consumption.

Cross-sectional comparison of first-generation antipsychotic long-acting injections vs risperidone long-acting injection: patient-rated attitudes, satisfaction and tolerability

PubMed Central

Singh, Sourabh Moti; Haddad, Peter M.; Husain, Nusrat; Heaney, Eamonn; Tomenson, Barbara; Chaudhry, Imran B.

2016-01-01

Objectives: The objective of this study was to compare patients’ attitudes and satisfaction with medication and patient-rated tolerability between those prescribed a first-generation antipsychotic long-acting injection (FGA-LAI) and those prescribed risperidone long-acting injection (RLAI). Method: A cross-sectional study of a representative sample of outpatients prescribed an FGA-LAI or RLAI for a minimum of 6 months and attending a depot clinic. Attitudes to medication were assessed by the Drug Attitude Inventory (DAI-30), tolerability was measured by the Liverpool University Neuroleptic Side Effect Rating Scale (LUNSERS) and satisfaction with antipsychotic medication was assessed by the Satisfaction with Antipsychotic Medication (SWAM) scale. Results: The RLAI (n = 28) and FGA-LAI (n = 39) groups did not differ in terms of mean age, sex, diagnosis and ethnicity. All individual LAIs were prescribed within British National Formulary limits. The most commonly prescribed FGA-LAI was flupentixol decanoate (n = 22). There was no significant difference between the RLAI and FGA-LAI groups in terms of mean total scores on the DAI-30, LUNSERS and SWAM or the tolerability subscales of the LUNSERS or the two subscales (treatment acceptability and medication insight) of the SWAM. In both LAI groups there was a low level of side effects (LUNSERS) and a generally positive attitude (DAI-30) and reasonable satisfaction (SWAM) with medication. Conclusions: Patients treated with FGA-LAI and RLAI for at least 6 months did not differ in terms of patient-rated tolerability, attitudes and satisfaction with medication. The current design cannot determine whether differences would have been evident earlier on during treatment. These results should be regarded as preliminary and are subject to prescribing bias. Randomized studies avoid prescribing bias and are a superior way to compare specific LAIs. Ideally randomized studies should include patient-rated outcome measures including

Evaluating the use of key performance indicators to evidence the patient experience.

PubMed

McCance, Tanya; Hastings, Jack; Dowler, Hilda

2015-11-01

To test eight person-centred key performance indicators and the feasibility of an appropriate measurement framework as an approach to evidencing the patient experience. The value of measuring the quality of patient care is undisputed in the international literature, however, the type of measures that can be used to generate data that is meaningful for practice continues to be debated. This paper offers a different perspective to the 'measurement' of the nursing and midwifery contribution to the patient experience. Fourth generation evaluation was the methodological approach used to evaluate the implementation of the key performance indicators and measurement framework across three participating organisations involving nine practice settings. Data were collected by repeated use of claims, concerns and issues with staff working across nine participating sites (n = 18) and the senior executives from the three partner organisations (n = 12). Data were collected during the facilitated sessions with stakeholders and analysed in conjunction with the data generated from the measurement framework. The data reveal the inherent value placed on the evidence generated from the implementation of the key performance indicators as reflected in the following themes: measuring what matters; evidencing the patient experience; engaging staff; a focus for improving practice; and articulating and demonstrating the positive contribution of nursing and midwifery. The implementation of the key performance indicators and the measurement framework has been effective in generating evidence that demonstrates the patient experience. The nature of the data generated not only privileges the patient voice but also offers feedback to nurses and midwives that can inform the development of person-centred cultures. The use of these indicators will produce evidence of patient experience that can be used by nurse and midwives to celebrate and further inform person-centred practice. © 2015 John

Measurement-device-independent quantum key distribution with multiple crystal heralded source with post-selection

NASA Astrophysics Data System (ADS)

Chen, Dong; Shang-Hong, Zhao; MengYi, Deng

2018-03-01

The multiple crystal heralded source with post-selection (MHPS), originally introduced to improve the single-photon character of the heralded source, has specific applications for quantum information protocols. In this paper, by combining decoy-state measurement-device-independent quantum key distribution (MDI-QKD) with spontaneous parametric downconversion process, we present a modified MDI-QKD scheme with MHPS where two architectures are proposed corresponding to symmetric scheme and asymmetric scheme. The symmetric scheme, which linked by photon switches in a log-tree structure, is adopted to overcome the limitation of the current low efficiency of m-to-1 optical switches. The asymmetric scheme, which shows a chained structure, is used to cope with the scalability issue with increase in the number of crystals suffered in symmetric scheme. The numerical simulations show that our modified scheme has apparent advances both in transmission distance and key generation rate compared to the original MDI-QKD with weak coherent source and traditional heralded source with post-selection. Furthermore, the recent advances in integrated photonics suggest that if built into a single chip, the MHPS might be a practical alternative source in quantum key distribution tasks requiring single photons to work.

Real-time fast physical random number generator with a photonic integrated circuit.

PubMed

Ugajin, Kazusa; Terashima, Yuta; Iwakawa, Kento; Uchida, Atsushi; Harayama, Takahisa; Yoshimura, Kazuyuki; Inubushi, Masanobu

2017-03-20

Random number generators are essential for applications in information security and numerical simulations. Most optical-chaos-based random number generators produce random bit sequences by offline post-processing with large optical components. We demonstrate a real-time hardware implementation of a fast physical random number generator with a photonic integrated circuit and a field programmable gate array (FPGA) electronic board. We generate 1-Tbit random bit sequences and evaluate their statistical randomness using NIST Special Publication 800-22 and TestU01. All of the BigCrush tests in TestU01 are passed using 410-Gbit random bit sequences. A maximum real-time generation rate of 21.1 Gb/s is achieved for random bit sequences in binary format stored in a computer, which can be directly used for applications involving secret keys in cryptography and random seeds in large-scale numerical simulations.

Joint DoD versus Navy Specific Lead Generation Advertising: Comparison of Conversion Rates to Quality Enlistments and Marginal Costs.

DTIC Science & Technology

1984-09-01

7D-Rt46 982 JOINT DOD VERSUS NAVY SPECIFIC LEAD GENERATION j/j ADVERTISING : COMPARISON OF..(U) J B FUGUR SCHOOL OF N BUSINESS DURHAM NC R C MOREY...REPORT I PEPIO0 COV9cO JOINT DOD VERSUS NAVY SPECIFIC LEAD GENERATION Technical Report ADVERTISING : Comparison of Conversion Rates to (0 Quality...block number) . Upper-Mental, High School Degree, enlistment contracts, national leads, Z Joint DOD advertising , Service Specific Advertising , conversion

A fiber-based quasi-continuous-wave quantum key distribution system

PubMed Central

Shen, Yong; Chen, Yan; Zou, Hongxin; Yuan, Jianmin

2014-01-01

We report a fiber-based quasi-continuous-wave (CW) quantum key distribution (QKD) system with continuous variables (CV). This system employs coherent light pulses and time multiplexing to maximally reduce cross talk in the fiber. No-switching detection scheme is adopted to optimize the repetition rate. Information is encoded on the sideband of the pulsed coherent light to fully exploit the continuous wave nature of laser field. With this configuration, high secret key rate can be achieved. For the 50 MHz detected bandwidth in our experiment, when the multidimensional reconciliation protocol is applied, a secret key rate of 187 kb/s can be achieved over 50 km of optical fiber against collective attacks, which have been shown to be asymptotically optimal. Moreover, recently studied loopholes have been fixed in our system. PMID:24691409

Solid-state YVO4/Nd:YVO4/KTP green laser system for the generation of subnanosecond pulses with adjustable kilohertz repetition rate.

PubMed

Zhang, Haijuan; Zhao, Shengzhi; Yang, Kejian; Li, Guiqiu; Li, Dechun; Zhao, Jia; Wang, Yonggang

2013-09-20

A solid-state green laser generating subnanosecond pulses with adjustable kilohertz repetition rate is presented. This pulse laser system is composed of a Q-switched and mode-locked YVO(4)/Nd:YVO(4)/KTP laser simultaneously modulated by an electro-optic (EO) modulator and a central semiconductor saturable absorption mirror. Because the repetition rate of the Q-switched envelope in this laser depends on the modulation frequency of the EO modulator, so long as the pulsewidth of the Q-switched envelope is shorter than the cavity roundtrip transmit time, i.e., the time interval of two neighboring mode-locking pulses, only one mode-locking pulse exists underneath a Q-switched envelope, resulting in the generation of subnanosecond pulses with kilohertz repetition rate. The experimental results show that the pulsewidth of subnanosecond pulses decreases with increasing pump power and the shortest pulse generated at 1 kHz was 450 ps with pulse energy as high as 252 μJ, corresponding to a peak power of 560 kW. In addition, this laser was confirmed to have high stability, and the pulse repetition rate could be freely adjusted from 1 to 4 kHz.

Experience and Its Generation

ERIC Educational Resources Information Center

Youqing, Chen

2006-01-01

Experience is an activity that arouses emotions and generates meanings based on vivid sensation and profound comprehension. It is emotional, meaningful, and personal, playing a key role in the course of forming and developing one's qualities. The psychological process of experience generation consists of such links as sensing things, arousing…

Integrating quantum key distribution with classical communications in backbone fiber network.

PubMed

Mao, Yingqiu; Wang, Bi-Xiao; Zhao, Chunxu; Wang, Guangquan; Wang, Ruichun; Wang, Honghai; Zhou, Fei; Nie, Jimin; Chen, Qing; Zhao, Yong; Zhang, Qiang; Zhang, Jun; Chen, Teng-Yun; Pan, Jian-Wei

2018-03-05

Quantum key distribution (QKD) provides information-theoretic security based on the laws of quantum mechanics. The desire to reduce costs and increase robustness in real-world applications has motivated the study of coexistence between QKD and intense classical data traffic in a single fiber. Previous works on coexistence in metropolitan areas have used wavelength-division multiplexing, however, coexistence in backbone fiber networks remains a great experimental challenge, as Tbps data of up to 20 dBm optical power is transferred, and much more noise is generated for QKD. Here we present for the first time, to the best of our knowledge, the integration of QKD with a commercial backbone network of 3.6 Tbps classical data at 21 dBm launch power over 66 km fiber. With 20 GHz pass-band filtering and large effective core area fibers, real-time secure key rates can reach 4.5 kbps and 5.1 kbps for co-propagation and counter-propagation at the maximum launch power, respectively. This demonstrates feasibility and represents an important step towards building a quantum network that coexists with the current backbone fiber infrastructure of classical communications.

Hydrogen-based power generation from bioethanol steam reforming

NASA Astrophysics Data System (ADS)

Tasnadi-Asztalos, Zs.; Cormos, C. C.; Agachi, P. S.

2015-12-01

This paper is evaluating two power generation concepts based on hydrogen produced from bioethanol steam reforming at industrial scale without and with carbon capture. The power generation from bioethanol conversion is based on two important steps: hydrogen production from bioethanol catalytic steam reforming and electricity generation using a hydrogen-fuelled gas turbine. As carbon capture method to be assessed in hydrogen-based power generation from bioethanol steam reforming, the gas-liquid absorption using methyl-di-ethanol-amine (MDEA) was used. Bioethanol is a renewable energy carrier mainly produced from biomass fermentation. Steam reforming of bioethanol (SRE) provides a promising method for hydrogen and power production from renewable resources. SRE is performed at high temperatures (e.g. 800-900°C) to reduce the reforming by-products (e.g. ethane, ethene). The power generation from hydrogen was done with M701G2 gas turbine (334 MW net power output). Hydrogen was obtained through catalytic steam reforming of bioethanol without and with carbon capture. For the evaluated plant concepts the following key performance indicators were assessed: fuel consumption, gross and net power outputs, net electrical efficiency, ancillary consumptions, carbon capture rate, specific CO2 emission etc. As the results show, the power generation based on bioethanol conversion has high energy efficiency and low carbon footprint.

Macranthoidin B Modulates Key Metabolic Pathways to Enhance ROS Generation and Induce Cytotoxicity and Apoptosis in Colorectal Cancer.

PubMed

Fan, Xing; Rao, Jun; Zhang, Ziwei; Li, Dengfeng; Cui, Wenhao; Zhang, Jun; Wang, Hua; Tou, Fangfang; Zheng, Zhi; Shen, Qiang

2018-01-01

Induction of oxidative stress and reactive oxygen species (ROS) mediated-apoptosis have been utilized as effective strategies in anticancer therapy. Macranthoidin B (MB) is a potent inducer of ROS-mediated apoptosis in cancer, but its mechanism of action is poorly understood. Superoxide production with MB exposure in colorectal cancer (CRC) cells was measured using lucigenin chemiluminescence and real-time PCR. MB's inhibitory effect on proliferation and viability of CRC cells was determined by proliferation assays. MB's effect on apoptosis of CRC cells was determined by Western blotting and annexin V-FITC/PI staining. MB's effect on the growth of CRC xenografts in mice was assessed. An established metabolomics profiling platform combining ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS) with gas chromatography-mass spectrometry (GC-MS) was performed to determine MB's effect on total metabolite variation in CRC cells. We found that MB increases ROS generation via modulating key metabolic pathways. Using metabolomics profiling platform combining LC-MS with GC-MS, a total of 236 metabolites were identified in HCT-116 cells in which 31 metabolites were determined to be significantly regulated (p ≤ 0.05) after MB exposure. A number of key metabolites revealed by metabolomics analysis include glucose, fructose, citrate, arginine, phenylalanine, and S-adenosylhomocysteine (SAH), suggesting specific modulation of metabolism on carbohydrates, amino acids and peptides, lipids, nucleotide, cofactors and vitamins in HCT-116 CRC cells with MB treatment highly associated with apoptosis triggered by enhanced ROS and activated caspase-3. Our results demonstrate that MB represses CRC cell proliferation by inducing ROS-mediated apoptosis. © 2018 The Author(s). Published by S. Karger AG, Basel.

Crystal structure of norcoclaurine-6-O-methyltransferase, a key rate-limiting step in the synthesis of benzylisoquinoline alkaloids.

PubMed

Robin, Adeline Y; Giustini, Cécile; Graindorge, Matthieu; Matringe, Michel; Dumas, Renaud

2016-09-01

Growing pharmaceutical interest in benzylisoquinoline alkaloids (BIA) coupled with their chemical complexity make metabolic engineering of microbes to create alternative platforms of production an increasingly attractive proposition. However, precise knowledge of rate-limiting enzymes and negative feedback inhibition by end-products of BIA metabolism is of paramount importance for this emerging field of synthetic biology. In this work we report the structural characterization of (S)-norcoclaurine-6-O-methyltransferase (6OMT), a key rate-limiting step enzyme involved in the synthesis of reticuline, the final intermediate to be shared between the different end-products of BIA metabolism, such as morphine, papaverine, berberine and sanguinarine. Four different crystal structures of the enzyme from Thalictrum flavum (Tf 6OMT) were solved: the apoenzyme, the complex with S-adenosyl-l-homocysteine (SAH), the complexe with SAH and the substrate and the complex with SAH and a feedback inhibitor, sanguinarine. The Tf 6OMT structural study provides a molecular understanding of its substrate specificity, active site structure and reaction mechanism. This study also clarifies the inhibition of Tf 6OMT by previously suggested feedback inhibitors. It reveals its high and time-dependent sensitivity toward sanguinarine. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

RSA Key Development Using Fingerprint Image on Text Message

NASA Astrophysics Data System (ADS)

Rahman, Sayuti; Triana, Indah; Khairani, Sumi; Yasir, Amru; Sundari, Siti

2017-12-01

Along with the development of technology today, humans are very facilitated in accessing information and Communicate with various media, including through the Internet network . Messages are sent by media such as text are not necessarily guaranteed security. it is often found someone that wants to send a secret message to the recipient, but the messages can be known by irresponsible people. So the sender feels dissappointed because the secret message that should be known only to the recipient only becomes known by the irresponsible people . It is necessary to do security the message by using the RSA algorithm, Using fingerprint image to generate RSA key.This is a solution to enrich the security of a message,it is needed to process images firstly before generating RSA keys with feature extraction.

Incompleteness and limit of security theory of quantum key distribution

NASA Astrophysics Data System (ADS)

Hirota, Osamu; Murakami, Dan; Kato, Kentaro; Futami, Fumio

2012-10-01

It is claimed in the many papers that a trace distance: d guarantees the universal composition security in quantum key distribution (QKD) like BB84 protocol. In this introduction paper, at first, it is explicitly explained what is the main misconception in the claim of the unconditional security for QKD theory. In general terms, the cause of the misunderstanding on the security claim is the Lemma in the paper of Renner. It suggests that the generation of the perfect random key is assured by the probability (1-d), and its failure probability is d. Thus, it concludes that the generated key provides the perfect random key sequence when the protocol is success. So the QKD provides perfect secrecy to the one time pad. This is the reason for the composition claim. However, the quantity of the trace distance (or variational distance) is not the probability for such an event. If d is not small enough, always the generated key sequence is not uniform. Now one needs the reconstruction of the evaluation of the trace distance if one wants to use it. One should first go back to the indistinguishability theory in the computational complexity based, and to clarify the meaning of the value of the variational distance. In addition, the same analysis for the information theoretic case is necessary. The recent serial papers by H.P.Yuen have given the answer on such questions. In this paper, we show more concise description of Yuen's theory, and clarify that the upper bound theories for the trace distance by Tomamichel et al and Hayashi et al are constructed by the wrong reasoning of Renner and it is unsuitable as the security analysis. Finally, we introduce a new macroscopic quantum communication to replace Q-bit QKD.

Metabolic rate associates with, but does not generate covariation between, behaviours in western stutter-trilling crickets, Gryllus integer.

PubMed

Krams, Indrikis A; Niemelä, Petri T; Trakimas, Giedrius; Krams, Ronalds; Burghardt, Gordon M; Krama, Tatjana; Kuusik, Aare; Mänd, Marika; Rantala, Markus J; Mänd, Raivo; Kekäläinen, Jukka; Sirkka, Ilkka; Luoto, Severi; Kortet, Raine

2017-03-29

The causes and consequences of among-individual variation and covariation in behaviours are of substantial interest to behavioural ecology, but the proximate mechanisms underpinning this (co)variation are still unclear. Previous research suggests metabolic rate as a potential proximate mechanism to explain behavioural covariation. We measured the resting metabolic rate (RMR), boldness and exploration in western stutter-trilling crickets, Gryllus integer , selected differentially for short and fast development over two generations. After applying mixed-effects models to reveal the sign of the covariation, we applied structural equation models to an individual-level covariance matrix to examine whether the RMR generates covariation between the measured behaviours. All traits showed among-individual variation and covariation: RMR and boldness were positively correlated, RMR and exploration were negatively correlated, and boldness and exploration were negatively correlated. However, the RMR was not a causal factor generating covariation between boldness and exploration. Instead, the covariation between all three traits was explained by another, unmeasured mechanism. The selection lines differed from each other in all measured traits and significantly affected the covariance matrix structure between the traits, suggesting that there is a genetic component in the trait integration. Our results emphasize that interpretations made solely from the correlation matrix might be misleading. © 2017 The Author(s).

Metabolic rate associates with, but does not generate covariation between, behaviours in western stutter-trilling crickets, Gryllus integer

PubMed Central

Trakimas, Giedrius; Krams, Ronalds; Burghardt, Gordon M.; Krama, Tatjana; Kuusik, Aare; Mänd, Marika; Rantala, Markus J.; Mänd, Raivo; Sirkka, Ilkka; Luoto, Severi; Kortet, Raine

2017-01-01

The causes and consequences of among-individual variation and covariation in behaviours are of substantial interest to behavioural ecology, but the proximate mechanisms underpinning this (co)variation are still unclear. Previous research suggests metabolic rate as a potential proximate mechanism to explain behavioural covariation. We measured the resting metabolic rate (RMR), boldness and exploration in western stutter-trilling crickets, Gryllus integer, selected differentially for short and fast development over two generations. After applying mixed-effects models to reveal the sign of the covariation, we applied structural equation models to an individual-level covariance matrix to examine whether the RMR generates covariation between the measured behaviours. All traits showed among-individual variation and covariation: RMR and boldness were positively correlated, RMR and exploration were negatively correlated, and boldness and exploration were negatively correlated. However, the RMR was not a causal factor generating covariation between boldness and exploration. Instead, the covariation between all three traits was explained by another, unmeasured mechanism. The selection lines differed from each other in all measured traits and significantly affected the covariance matrix structure between the traits, suggesting that there is a genetic component in the trait integration. Our results emphasize that interpretations made solely from the correlation matrix might be misleading. PMID:28330918

CNES developments of key detection technologies to prepare next generation focal planes for high resolution Earth observation

NASA Astrophysics Data System (ADS)

Materne, A.; Virmontois, C.; Bardoux, A.; Gimenez, T.; Biffi, J. M.; Laubier, D.; Delvit, J. M.

2014-10-01

This paper describes the activities managed by CNES (French National Space Agency) for the development of focal planes for next generation of optical high resolution Earth observation satellites, in low sun-synchronous orbit. CNES has launched a new programme named OTOS, to increase the level of readiness (TRL) of several key technologies for high resolution Earth observation satellites. The OTOS programme includes several actions in the field of detection and focal planes: a new generation of CCD and CMOS image sensors, updated analog front-end electronics and analog-to-digital converters. The main features that must be achieved on focal planes for high resolution Earth Observation, are: readout speed, signal to noise ratio at low light level, anti-blooming efficiency, geometric stability, MTF and line of sight stability. The next steps targeted are presented in comparison to the in-flight measured performance of the PLEIADES satellites launched in 2011 and 2012. The high resolution panchromatic channel is still based upon Backside illuminated (BSI) CCDs operated in Time Delay Integration (TDI). For the multispectral channel, the main evolution consists in moving to TDI mode and the competition is open with the concurrent development of a CCD solution versus a CMOS solution. New CCDs will be based upon several process blocks under evaluation on the e2v 6 inches BSI wafer manufacturing line. The OTOS strategy for CMOS image sensors investigates on one hand custom TDI solutions within a similar approach to CCDs, and, on the other hand, investigates ways to take advantage of existing performance of off-the-shelf 2D arrays CMOS image sensors. We present the characterization results obtained from test vehicles designed for custom TDI operation on several CIS technologies and results obtained before and after radiation on snapshot 2D arrays from the CMOSIS CMV family.

How do Supervising Clinicians of a University Hospital and Associated Teaching Hospitals Rate the Relevance of the Key Competencies within the CanMEDS Roles Framework in Respect to Teaching in Clinical Clerkships?

PubMed

Jilg, Stefanie; Möltner, Andreas; Berberat, Pascal; Fischer, Martin R; Breckwoldt, Jan

2015-01-01

In German-speaking countries, the physicians' roles framework of the "Canadian Medical Education Directives for Specialists" (CanMEDS) is increasingly used to conceptualize postgraduate medical education. It is however unclear, whether it may also be applied to the final year of undergraduate education within clinical clerkships, called "Practical Year" (PY). Therefore, the aim of this study was to explore how clinically active physicians at a university hospital and at associated teaching hospitals judge the relevance of the seven CanMEDS roles (and their (role-defining) key competencies) in respect to their clinical work and as learning content for PY training. Furthermore, these physicians were asked whether the key competencies were actually taught during PY training. 124 physicians from internal medicine and surgery rated the relevance of the 28 key competencies of the CanMEDS framework using a questionnaire. For each competency, following three aspects were rated: "relevance for your personal daily work", "importance for teaching during PY", and "implementation into actual PY teaching". In respect to the main study objective, all questionnaires could be included into analysis. All seven CanMEDS roles were rated as relevant for personal daily work, and also as important for teaching during PY. Furthermore, all roles were stated to be taught during actual PY training. The roles "Communicator", "Medical Expert", and "Collaborator" were rated as significantly more important than the other roles, for all three sub-questions. No differences were found between the two disciplines internal medicine and surgery, nor between the university hospital and associated teaching hospitals. Participating physicians rated all key competencies of the CanMEDS model to be relevant for their personal daily work, and for teaching during PY. These findings support the suitability of the CanMEDS framework as a conceptual element of PY training.

How do Supervising Clinicians of a University Hospital and Associated Teaching Hospitals Rate the Relevance of the Key Competencies within the CanMEDS Roles Framework in Respect to Teaching in Clinical Clerkships?

PubMed Central

Jilg, Stefanie; Möltner, Andreas; Berberat, Pascal; Fischer, Martin R.; Breckwoldt, Jan

2015-01-01

Background and aim: In German-speaking countries, the physicians’ roles framework of the “Canadian Medical Education Directives for Specialists” (CanMEDS) is increasingly used to conceptualize postgraduate medical education. It is however unclear, whether it may also be applied to the final year of undergraduate education within clinical clerkships, called “Practical Year” (PY). Therefore, the aim of this study was to explore how clinically active physicians at a university hospital and at associated teaching hospitals judge the relevance of the seven CanMEDS roles (and their (role-defining) key competencies) in respect to their clinical work and as learning content for PY training. Furthermore, these physicians were asked whether the key competencies were actually taught during PY training. Methods: 124 physicians from internal medicine and surgery rated the relevance of the 28 key competencies of the CanMEDS framework using a questionnaire. For each competency, following three aspects were rated: “relevance for your personal daily work”, “importance for teaching during PY”, and “implementation into actual PY teaching”. Results: In respect to the main study objective, all questionnaires could be included into analysis. All seven CanMEDS roles were rated as relevant for personal daily work, and also as important for teaching during PY. Furthermore, all roles were stated to be taught during actual PY training. The roles “Communicator”, “Medical Expert”, and “Collaborator” were rated as significantly more important than the other roles, for all three sub-questions. No differences were found between the two disciplines internal medicine and surgery, nor between the university hospital and associated teaching hospitals. Conclusion: Participating physicians rated all key competencies of the CanMEDS model to be relevant for their personal daily work, and for teaching during PY. These findings support the suitability of the Can

Improved symbol rate identification method for on-off keying and advanced modulation format signals based on asynchronous delayed sampling

NASA Astrophysics Data System (ADS)

Cui, Sheng; Jin, Shang; Xia, Wenjuan; Ke, Changjian; Liu, Deming

2015-11-01

Symbol rate identification (SRI) based on asynchronous delayed sampling is accurate, cost-effective and robust to impairments. For on-off keying (OOK) signals the symbol rate can be derived from the periodicity of the second-order autocorrelation function (ACF2) of the delay tap samples. But it is found that when applied this method to advanced modulation format signals with auxiliary amplitude modulation (AAM), incorrect results may be produced because AAM has significant impact on ACF2 periodicity, which makes the symbol period harder or even unable to be correctly identified. In this paper it is demonstrated that for these signals the first order autocorrelation function (ACF1) has stronger periodicity and can be used to replace ACF2 to produce more accurate and robust results. Utilizing the characteristics of the ACFs, an improved SRI method is proposed to accommodate both OOK and advanced modulation formant signals in a transparent manner. Furthermore it is proposed that by minimizing the peak to average ratio (PAPR) of the delay tap samples with an additional tunable dispersion compensator (TDC) the limited dispersion tolerance can be expanded to desired values.

Tag Content Access Control with Identity-based Key Exchange

NASA Astrophysics Data System (ADS)

Yan, Liang; Rong, Chunming

2010-09-01

Radio Frequency Identification (RFID) technology that used to identify objects and users has been applied to many applications such retail and supply chain recently. How to prevent tag content from unauthorized readout is a core problem of RFID privacy issues. Hash-lock access control protocol can make tag to release its content only to reader who knows the secret key shared between them. However, in order to get this shared secret key required by this protocol, reader needs to communicate with a back end database. In this paper, we propose to use identity-based secret key exchange approach to generate the secret key required for hash-lock access control protocol. With this approach, not only back end database connection is not needed anymore, but also tag cloning problem can be eliminated at the same time.

Implementation of a multi-variable regression analysis in the assessment of the generation rate and composition of hospital solid waste for the design of a sustainable management system in developing countries.

PubMed

Al-Khatib, Issam A; Abu Fkhidah, Ismail; Khatib, Jumana I; Kontogianni, Stamatia

2016-03-01

Forecasting of hospital solid waste generation is a critical challenge for future planning. The composition and generation rate of hospital solid waste in hospital units was the field where the proposed methodology of the present article was applied in order to validate the results and secure the outcomes of the management plan in national hospitals. A set of three multiple-variable regression models has been derived for estimating the daily total hospital waste, general hospital waste, and total hazardous waste as a function of number of inpatients, number of total patients, and number of beds. The application of several key indicators and validation procedures indicates the high significance and reliability of the developed models in predicting the hospital solid waste of any hospital. Methodology data were drawn from existent scientific literature. Also, useful raw data were retrieved from international organisations and the investigated hospitals' personnel. The primal generation outcomes are compared with other local hospitals and also with hospitals from other countries. The main outcome, which is the developed model results, are presented and analysed thoroughly. The goal is this model to act as leverage in the discussions among governmental authorities on the implementation of a national plan for safe hospital waste management in Palestine. © The Author(s) 2016.

Transportation: The Key to Unlocking the Final Frontier

NASA Technical Reports Server (NTRS)

Sackheim, Robert L.; Saucier, Sidney (Technical Monitor)

2000-01-01

For this future generations in this new millennium, only two new frontiers remain to be explored and developed by humans: Under the oceans, seas and lakes (about 80 percent of the Earth) and The vast reaches of near and outer space. We are slowly running out of resources while this planet's population is exploding. We must establish new, highly reliable and low-cost ways to colonize under the seas and to get people permanently off "Spaceship Planet Earth". We must establish new colonies permanently in space because it is vital to the ultimate survival of the human race. Reliable and affordable space transportation for routine human travel into space and the planets is once again the key to developing this last great frontier. This talk will now focus on what NASA is now doing to initiate the process in earnest. Space transportation is the key, and once again will only meet the needs with new generations of competent, talented, and innovative mechanical engineers.

Three-particle hyper-entanglement: teleportation and quantum key distribution

NASA Astrophysics Data System (ADS)

Perumangatt, Chithrabhanu; Abdul Rahim, Aadhi; Salla, Gangi Reddy; Prabhakar, Shashi; Samanta, Goutam Kumar; Paul, Goutam; Singh, Ravindra Pratap

2015-10-01

We present a scheme to generate three-particle hyper-entanglement utilizing polarization and orbital angular momentum (OAM) of photons. We show that the generated state can be used to teleport a two-qubit state described by the polarization and the OAM. The proposed quantum system has also been used to describe a new efficient quantum key distribution (QKD) protocol. We give a sketch of the experimental arrangement to realize the proposed teleportation and the QKD.

Parallel sort with a ranged, partitioned key-value store in a high perfomance computing environment

DOEpatents

Bent, John M.; Faibish, Sorin; Grider, Gary; Torres, Aaron; Poole, Stephen W.

2016-01-26

Improved sorting techniques are provided that perform a parallel sort using a ranged, partitioned key-value store in a high performance computing (HPC) environment. A plurality of input data files comprising unsorted key-value data in a partitioned key-value store are sorted. The partitioned key-value store comprises a range server for each of a plurality of ranges. Each input data file has an associated reader thread. Each reader thread reads the unsorted key-value data in the corresponding input data file and performs a local sort of the unsorted key-value data to generate sorted key-value data. A plurality of sorted, ranged subsets of each of the sorted key-value data are generated based on the plurality of ranges. Each sorted, ranged subset corresponds to a given one of the ranges and is provided to one of the range servers corresponding to the range of the sorted, ranged subset. Each range server sorts the received sorted, ranged subsets and provides a sorted range. A plurality of the sorted ranges are concatenated to obtain a globally sorted result.

"I got caught up in the game": generational influences on contraceptive decision making in African-American women.

PubMed

Harris, Allyssa L

2013-03-01

Reproductive health disparities are a significant issue for African-American adolescents. This study was designed to explore the cross-generational influences on adolescent sexuality in a cohort of daughters/granddaughters of U.S. born African-American women. Data were generated through interviews with triads of African-American women: grandmothers, and their daughters and granddaughters, to gain insight into the phenomena of early sexual debut, high rates of unintended pregnancies, HIV/AIDS, and other sexually transmitted infections from a cross-generational perspective. Six themes emerged from the data: southern influences; a worldview of relationships; communication-key to preparedness; seeking information from mom; "I got caught up in the game"; and contraceptive use and beliefs. In this sample, mothers' and grandmothers' culture, values, and beliefs significantly influenced the adolescents' sexual and reproductive decision making. Clinicians' knowledge of African-American culture, beliefs, and family values is key when providing guidance about contraception to these young women. ©2012 The Author(s) Journal compilation ©2012 American Association of Nurse Practitioners.

Quantum key distribution session with 16-dimensional photonic states.

PubMed

Etcheverry, S; Cañas, G; Gómez, E S; Nogueira, W A T; Saavedra, C; Xavier, G B; Lima, G

2013-01-01

The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this problem by using individual quantum systems to generate correlated bits between remote parties, that can be used to extract a secret key. QKD with D-dimensional quantum channels provides security advantages that grow with increasing D. However, the vast majority of QKD implementations has been restricted to two dimensions. Here we demonstrate the feasibility of using higher dimensions for real-world quantum cryptography by performing, for the first time, a fully automated QKD session based on the BB84 protocol with 16-dimensional quantum states. Information is encoded in the single-photon transverse momentum and the required states are dynamically generated with programmable spatial light modulators. Our setup paves the way for future developments in the field of experimental high-dimensional QKD.

Quantum key distribution session with 16-dimensional photonic states

NASA Astrophysics Data System (ADS)

Etcheverry, S.; Cañas, G.; Gómez, E. S.; Nogueira, W. A. T.; Saavedra, C.; Xavier, G. B.; Lima, G.

2013-07-01

The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this problem by using individual quantum systems to generate correlated bits between remote parties, that can be used to extract a secret key. QKD with D-dimensional quantum channels provides security advantages that grow with increasing D. However, the vast majority of QKD implementations has been restricted to two dimensions. Here we demonstrate the feasibility of using higher dimensions for real-world quantum cryptography by performing, for the first time, a fully automated QKD session based on the BB84 protocol with 16-dimensional quantum states. Information is encoded in the single-photon transverse momentum and the required states are dynamically generated with programmable spatial light modulators. Our setup paves the way for future developments in the field of experimental high-dimensional QKD.

Lagrange Point Missions: the Key to Next-Generation Integrated Earth Observations. DSCOVR Innovation

NASA Astrophysics Data System (ADS)

Valero, F. P. J.

2016-12-01

From L-1 DSCOVR is capable of new, unique observations potentially conducive to a deeper scientific understanding of the Earth sciences. At L-1 and L-2 the net gravitational pull of the Earth and Sun equals the centripetal force required to orbit the Sun with the same period as the Earth. Satellites at or near L-1 and L-2 keep the same position relative to the Sun and the Earth. DSCOVR does not orbit the Earth but the Sun in synchronism with Earth, acts like a planetoid (orbits the Sun in the ecliptic plane) while acquiring integrated plus spatially and time resolved scientific data as Earth rotates around its axis. Because of the planet's axial tilt relative to the ecliptic plane, the Polar Regions are visible during local summer from L-1 and local winter from L-2 (Fig. 1). DSCOVR's synoptic and continuous observations solve most of the temporal and spatial limitations associated with low Earth (LEO) and Geostationary (GEO) orbits. Two observatories, one at L-1 (daytime) and one at L-2 (nighttime), would acquire minute-by-minute climate quality data for essentially every point on Earth. The integration of L-1, L-2, LEO, and GEO satellites plus the Moon offers new scientific tools and enriched data sets for Earth sciences. Lagrange points observatories are key to next-generation integrated Earth observations. For example, DSCOVR at L-1 views the Earth plus the Moon (a reference) and simultaneously, at one time or another, all LEO and GEO satellites. The L-1 and L-2 satellites would be the link between the Moon, LEO and GEO satellites while providing the data needed to build an integrated Earth observational system. The above properties are the bases for DSCOVR's innovation and scientific approach that systematically observes climate drivers (radiation, aerosols, ozone, clouds, water vapor, vegetation) from L-1 in a way not possible but synergistic with other satellites. Next step: more capable L-1 plus L-2 satellites. The way of the future.

Synchronous-digitization for Video Rate Polarization Modulated Beam Scanning Second Harmonic Generation Microscopy.

PubMed

Sullivan, Shane Z; DeWalt, Emma L; Schmitt, Paul D; Muir, Ryan M; Simpson, Garth J

2015-03-09

Fast beam-scanning non-linear optical microscopy, coupled with fast (8 MHz) polarization modulation and analytical modeling have enabled simultaneous nonlinear optical Stokes ellipsometry (NOSE) and linear Stokes ellipsometry imaging at video rate (15 Hz). NOSE enables recovery of the complex-valued Jones tensor that describes the polarization-dependent observables, in contrast to polarimetry, in which the polarization stated of the exciting beam is recorded. Each data acquisition consists of 30 images (10 for each detector, with three detectors operating in parallel), each of which corresponds to polarization-dependent results. Processing of this image set by linear fitting contracts down each set of 10 images to a set of 5 parameters for each detector in second harmonic generation (SHG) and three parameters for the transmittance of the fundamental laser beam. Using these parameters, it is possible to recover the Jones tensor elements of the sample at video rate. Video rate imaging is enabled by performing synchronous digitization (SD), in which a PCIe digital oscilloscope card is synchronized to the laser (the laser is the master clock.) Fast polarization modulation was achieved by modulating an electro-optic modulator synchronously with the laser and digitizer, with a simple sine-wave at 1/10th the period of the laser, producing a repeating pattern of 10 polarization states. This approach was validated using Z-cut quartz, and NOSE microscopy was performed for micro-crystals of naproxen.

Synchronous-digitization for video rate polarization modulated beam scanning second harmonic generation microscopy

NASA Astrophysics Data System (ADS)

Sullivan, Shane Z.; DeWalt, Emma L.; Schmitt, Paul D.; Muir, Ryan D.; Simpson, Garth J.

2015-03-01

Fast beam-scanning non-linear optical microscopy, coupled with fast (8 MHz) polarization modulation and analytical modeling have enabled simultaneous nonlinear optical Stokes ellipsometry (NOSE) and linear Stokes ellipsometry imaging at video rate (15 Hz). NOSE enables recovery of the complex-valued Jones tensor that describes the polarization-dependent observables, in contrast to polarimetry, in which the polarization stated of the exciting beam is recorded. Each data acquisition consists of 30 images (10 for each detector, with three detectors operating in parallel), each of which corresponds to polarization-dependent results. Processing of this image set by linear fitting contracts down each set of 10 images to a set of 5 parameters for each detector in second harmonic generation (SHG) and three parameters for the transmittance of the fundamental laser beam. Using these parameters, it is possible to recover the Jones tensor elements of the sample at video rate. Video rate imaging is enabled by performing synchronous digitization (SD), in which a PCIe digital oscilloscope card is synchronized to the laser (the laser is the master clock.) Fast polarization modulation was achieved by modulating an electro-optic modulator synchronously with the laser and digitizer, with a simple sine-wave at 1/10th the period of the laser, producing a repeating pattern of 10 polarization states. This approach was validated using Z-cut quartz, and NOSE microscopy was performed for micro-crystals of naproxen.

Polarization-basis tracking scheme for quantum key distribution using revealed sifted key bits.

PubMed

Ding, Yu-Yang; Chen, Wei; Chen, Hua; Wang, Chao; Li, Ya-Ping; Wang, Shuang; Yin, Zhen-Qiang; Guo, Guang-Can; Han, Zheng-Fu

2017-03-15

The calibration of the polarization basis between the transmitter and receiver is an important task in quantum key distribution. A continuously working polarization-basis tracking scheme (PBTS) will effectively promote the efficiency of the system and reduce the potential security risk when switching between the transmission and calibration modes. Here, we proposed a single-photon level continuously working PBTS using only sifted key bits revealed during an error correction procedure, without introducing additional reference light or interrupting the transmission of quantum signals. We applied the scheme to a polarization-encoding BB84 QKD system in a 50 km fiber channel, and obtained an average quantum bit error rate (QBER) of 2.32% and a standard derivation of 0.87% during 24 h of continuous operation. The stable and relatively low QBER validates the effectiveness of the scheme.

An FPGA design of generalized low-density parity-check codes for rate-adaptive optical transport networks

NASA Astrophysics Data System (ADS)

Zou, Ding; Djordjevic, Ivan B.

2016-02-01

Forward error correction (FEC) is as one of the key technologies enabling the next-generation high-speed fiber optical communications. In this paper, we propose a rate-adaptive scheme using a class of generalized low-density parity-check (GLDPC) codes with a Hamming code as local code. We show that with the proposed unified GLDPC decoder architecture, a variable net coding gains (NCGs) can be achieved with no error floor at BER down to 10-15, making it a viable solution in the next-generation high-speed fiber optical communications.

Scram signal generator

DOEpatents

Johanson, Edward W.; Simms, Richard

1981-01-01

A scram signal generating circuit for nuclear reactor installations monitors a flow signal representing the flow rate of the liquid sodium coolant which is circulated through the reactor, and initiates reactor shutdown for a rapid variation in the flow signal, indicative of fuel motion. The scram signal generating circuit includes a long-term drift compensation circuit which processes the flow signal and generates an output signal representing the flow rate of the coolant. The output signal remains substantially unchanged for small variations in the flow signal, attributable to long term drift in the flow rate, but a rapid change in the flow signal, indicative of a fast flow variation, causes a corresponding change in the output signal. A comparator circuit compares the output signal with a reference signal, representing a given percentage of the steady state flow rate of the coolant, and generates a scram signal to initiate reactor shutdown when the output signal equals the reference signal.

Scram signal generator

DOEpatents

Johanson, E.W.; Simms, R.

A scram signal generating circuit for nuclear reactor installations monitors a flow signal representing the flow rate of the liquid sodium coolant which is circulated through the reactor, and initiates reactor shutdown for a rapid variation in the flow signal, indicative of fuel motion. The scram signal generating circuit includes a long-term drift compensation circuit which processes the flow signal and generates an output signal representing the flow rate of the coolant. The output signal remains substantially unchanged for small variations in the flow signal, attributable to long term drift in the flow rate, but a rapid change in the flow signal, indicative of a fast flow variation, causes a corresponding change in the output signal. A comparator circuit compares the output signal with a reference signal, representing a given percentage of the steady state flow rate of the coolant, and generates a scram signal to initiate reactor shutdown when the output signal equals the reference signal.

[Long-term effect of iodine deficiency on growth and food utilization rate in second filial generation rats].

PubMed

Muyeseer, Ainiwaer; Zhang, G X; Wang, J; Liu, Y; Meng, X H; Liu, Q

2017-02-06

Objective: To study the effect of iodine deficiency on body weight, food consumption, and food utilization rate of second filial generation Wistar rats. Methods: According to the food pattern of a high-iodine deficient population, two types of low-iodine food have been produced using the main crops grown in this area (iodine levels of 50 and 20 μg/kg, respectively). Wistar rats were randomly divided into three groups, normal iodine group (NI group), low-iodine group one (LI group) and low-iodine group two (LII group), using the random number table method and fed diets containing 300, 50, and 20 μg/kg of iodine, respectively. Parental generation rats were fed until they reached reproductive age; first filial generation rats were allocated to the same diet as their mothers. After 3 months of feeding, first filial generation rats gave birth to second filial generation rats; second filial generation rats were allocated to the same diet as their mothers. After feeding for 90, 180, and 270 days, rats were sacrificed. One-way analysis of variance was used to analyze body weight, food intake, and food utilization rate data collected during the time of feeding and blood iodine hormone level, which was determined after sacrifice. Results: The LI and LII groups generally demonstrated decreased activity, slow reaction, and growth retardation compared with the NI group. After 270 days, the urine iodine levels of the LI and LII groups were 1.7 and 0.2 μg/L, respectively, which were significantly lower than the NI group (255.2 μg/L) ( P< 0.001). Additionally, the weight of female rats in the LI and LII groups were (288.1±10.5) and (275.7±2.7) g, respectively, which was significantly lower than that of the NI group ((311.0±2.3) g) ( P< 0.001). The weight of male rats were (446.0±4.6) and (451.8±19.1) g, respectively, which were significantly lower than that of the NI group ((517.2±7.8) g) ( P< 0.001). In the LI and LII groups, food intake of female and male rats after

Iris recognition based on key image feature extraction.

PubMed

Ren, X; Tian, Q; Zhang, J; Wu, S; Zeng, Y

2008-01-01

In iris recognition, feature extraction can be influenced by factors such as illumination and contrast, and thus the features extracted may be unreliable, which can cause a high rate of false results in iris pattern recognition. In order to obtain stable features, an algorithm was proposed in this paper to extract key features of a pattern from multiple images. The proposed algorithm built an iris feature template by extracting key features and performed iris identity enrolment. Simulation results showed that the selected key features have high recognition accuracy on the CASIA Iris Set, where both contrast and illumination variance exist.

RSA-Based Password-Authenticated Key Exchange, Revisited

NASA Astrophysics Data System (ADS)

Shin, Seonghan; Kobara, Kazukuni; Imai, Hideki

The RSA-based Password-Authenticated Key Exchange (PAKE) protocols have been proposed to realize both mutual authentication and generation of secure session keys where a client is sharing his/her password only with a server and the latter should generate its RSA public/private key pair (e, n), (d, n) every time due to the lack of PKI (Public-Key Infrastructures). One of the ways to avoid a special kind of off-line (so called e-residue) attacks in the RSA-based PAKE protocols is to deploy a challenge/response method by which a client verifies the relative primality of e and φ(n) interactively with a server. However, this kind of RSA-based PAKE protocols did not give any proof of the underlying challenge/response method and therefore could not specify the exact complexity of their protocols since there exists another security parameter, needed in the challenge/response method. In this paper, we first present an RSA-based PAKE (RSA-PAKE) protocol that can deploy two different challenge/response methods (denoted by Challenge/Response Method1 and Challenge/Response Method2). The main contributions of this work include: (1) Based on the number theory, we prove that the Challenge/Response Method1 and the Challenge/Response Method2 are secure against e-residue attacks for any odd prime e (2) With the security parameter for the on-line attacks, we show that the RSA-PAKE protocol is provably secure in the random oracle model where all of the off-line attacks are not more efficient than on-line dictionary attacks; and (3) By considering the Hamming weight of e and its complexity in the. RSA-PAKE protocol, we search for primes to be recommended for a practical use. We also compare the RSA-PAKE protocol with the previous ones mainly in terms of computation and communication complexities.

Genome Alignment Spanning Major Poaceae Lineages Reveals Heterogeneous Evolutionary Rates and Alters Inferred Dates for Key Evolutionary Events.

PubMed

Wang, Xiyin; Wang, Jingpeng; Jin, Dianchuan; Guo, Hui; Lee, Tae-Ho; Liu, Tao; Paterson, Andrew H

2015-06-01

Multiple comparisons among genomes can clarify their evolution, speciation, and functional innovations. To date, the genome sequences of eight grasses representing the most economically important Poaceae (grass) clades have been published, and their genomic-level comparison is an essential foundation for evolutionary, functional, and translational research. Using a formal and conservative approach, we aligned these genomes. Direct comparison of paralogous gene pairs all duplicated simultaneously reveal striking variation in evolutionary rates among whole genomes, with nucleotide substitution slowest in rice and up to 48% faster in other grasses, adding a new dimension to the value of rice as a grass model. We reconstructed ancestral genome contents for major evolutionary nodes, potentially contributing to understanding the divergence and speciation of grasses. Recent fossil evidence suggests revisions of the estimated dates of key evolutionary events, implying that the pan-grass polyploidization occurred ∼96 million years ago and could not be related to the Cretaceous-Tertiary mass extinction as previously inferred. Adjusted dating to reflect both updated fossil evidence and lineage-specific evolutionary rates suggested that maize subgenome divergence and maize-sorghum divergence were virtually simultaneous, a coincidence that would be explained if polyploidization directly contributed to speciation. This work lays a solid foundation for Poaceae translational genomics. Copyright © 2015 The Author. Published by Elsevier Inc. All rights reserved.

A hybrid-type quantum random number generator

NASA Astrophysics Data System (ADS)

Hai-Qiang, Ma; Wu, Zhu; Ke-Jin, Wei; Rui-Xue, Li; Hong-Wei, Liu

2016-05-01

This paper proposes a well-performing hybrid-type truly quantum random number generator based on the time interval between two independent single-photon detection signals, which is practical and intuitive, and generates the initial random number sources from a combination of multiple existing random number sources. A time-to-amplitude converter and multichannel analyzer are used for qualitative analysis to demonstrate that each and every step is random. Furthermore, a carefully designed data acquisition system is used to obtain a high-quality random sequence. Our scheme is simple and proves that the random number bit rate can be dramatically increased to satisfy practical requirements. Project supported by the National Natural Science Foundation of China (Grant Nos. 61178010 and 11374042), the Fund of State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), China, and the Fundamental Research Funds for the Central Universities of China (Grant No. bupt2014TS01).

Finite-key security analyses on passive decoy-state QKD protocols with different unstable sources.

PubMed

Song, Ting-Ting; Qin, Su-Juan; Wen, Qiao-Yan; Wang, Yu-Kun; Jia, Heng-Yue

2015-10-16

In quantum communication, passive decoy-state QKD protocols can eliminate many side channels, but the protocols without any finite-key analyses are not suitable for in practice. The finite-key securities of passive decoy-state (PDS) QKD protocols with two different unstable sources, type-II parametric down-convention (PDC) and phase randomized weak coherent pulses (WCPs), are analyzed in our paper. According to the PDS QKD protocols, we establish an optimizing programming respectively and obtain the lower bounds of finite-key rates. Under some reasonable values of quantum setup parameters, the lower bounds of finite-key rates are simulated. The simulation results show that at different transmission distances, the affections of different fluctuations on key rates are different. Moreover, the PDS QKD protocol with an unstable PDC source can resist more intensity fluctuations and more statistical fluctuation.

Finite-key security analyses on passive decoy-state QKD protocols with different unstable sources

PubMed Central

Song, Ting-Ting; Qin, Su-Juan; Wen, Qiao-Yan; Wang, Yu-Kun; Jia, Heng-Yue

2015-01-01

In quantum communication, passive decoy-state QKD protocols can eliminate many side channels, but the protocols without any finite-key analyses are not suitable for in practice. The finite-key securities of passive decoy-state (PDS) QKD protocols with two different unstable sources, type-II parametric down-convention (PDC) and phase randomized weak coherent pulses (WCPs), are analyzed in our paper. According to the PDS QKD protocols, we establish an optimizing programming respectively and obtain the lower bounds of finite-key rates. Under some reasonable values of quantum setup parameters, the lower bounds of finite-key rates are simulated. The simulation results show that at different transmission distances, the affections of different fluctuations on key rates are different. Moreover, the PDS QKD protocol with an unstable PDC source can resist more intensity fluctuations and more statistical fluctuation. PMID:26471947

Coal and Coal/Biomass-Based Power Generation

EPA Science Inventory

For Frank Princiotta's book, Global Climate Change--The Technology Challenge Coal is a key, growing component in power generation globally. It generates 50% of U.S. electricity, and criteria emissions from coal-based power generation are being reduced. However, CO2 emissions m...

Pulsed laser-based optical frequency comb generator for high capacity wavelength division multiplexed passive optical network supporting 1.2 Tbps

NASA Astrophysics Data System (ADS)

Ullah, Rahat; Liu, Bo; Zhang, Qi; Saad Khan, Muhammad; Ahmad, Ibrar; Ali, Amjad; Khan, Razaullah; Tian, Qinghua; Yan, Cheng; Xin, Xiangjun

2016-09-01

An architecture for flattened and broad spectrum multicarriers is presented by generating 60 comb lines from pulsed laser driven by user-defined bit stream in cascade with three modulators. The proposed scheme is a cost-effective architecture for optical line terminal (OLT) in wavelength division multiplexed passive optical network (WDM-PON) system. The optical frequency comb generator consists of a pulsed laser in cascade with a phase modulator and two Mach-Zehnder modulators driven by an RF source incorporating no phase shifter, filter, or electrical amplifier. Optical frequency comb generation is deployed in the simulation environment at OLT in WDM-PON system supports 1.2-Tbps data rate. With 10-GHz frequency spacing, each frequency tone carries data signal of 20 Gbps-based differential quadrature phase shift keying (DQPSK) in downlink transmission. We adopt DQPSK-based modulation technique in the downlink transmission because it supports 2 bits per symbol, which increases the data rate in WDM-PON system. Furthermore, DQPSK format is tolerant to different types of dispersions and has a high spectral efficiency with less complex configurations. Part of the downlink power is utilized in the uplink transmission; the uplink transmission is based on intensity modulated on-off keying. Minimum power penalties have been observed with excellent eye diagrams and other transmission performances at specified bit error rates.

Could larger diameter of 4th generation ceramic bearing decrease the rate of dislocation after THA?

PubMed

Lee, Young-Kyun; Ha, Yong-Chan; Jo, Woo-Lam; Kim, Tae-Young; Jung, Woon-Hwa; Koo, Kyung-Hoi

2016-05-01

Fourth generation (Delta) ceramic bearing was developed to reduce dislocation after total hip arthroplasty (THA) by increasing the head diameter. We tested a hypothesis that 32/36 mm Delta ceramic bearing decreases the dislocation rate. We also evaluated ceramic-related complications and early outcome of this thin liner-on-large head ceramic bearing. We performed a prospective study on patients who underwent THA with use of 32/36 mm Delta ceramic bearing. The dislocation rate was compared with the historical dislocation rate of third generation 28 mm ceramic bearing. We also evaluated ceramic fracture, squeak, short-term results and survival. Follow-up period was minimum 2 years. Between April 2010 and February 2012, we enrolled 250 consecutive patients (278 hips). All patients received cementless prostheses. Four patients (4 hips) who received metal shells ≤ 46 mm and 28 mm heads were excluded. Three patients died and 2 patients were lost within 2 years. The remaining 241 patients (269 hips) were followed for 24-46 months. There were 142 men (161 hips) and 99 women (108 hips) with a mean age of 53.7 years (range, 17-75 years) at the index operation. Dislocation occurred in three hips (1.1%). An old age was a risk factor for dislocation. Ceramic fracture and squeaking did not occur in any patient. Mean Harris hip score was 90.3 points at the latest follow-up. All acetabular and femoral components had bone-ingrowth stability. No hip had detectable wear or osteolysis. The survival was 99.3% in the best case scenario and 97.8% in the worst at 48 months. Total hip arthroplasty with use of 32/36 mm Delta ceramic bearing showed lower incidence of hip dislocation compared with 28 mm third generation ceramic bearing. A caution should be paid to prevent a fall in senile patients even though a large head is used. The short-term results of THA with this type of ceramic articulation are encouraging and we did not find any ceramic-related complications. Copyright �

An Efficient Biometric-Based Algorithm Using Heart Rate Variability for Securing Body Sensor Networks

PubMed Central

Pirbhulal, Sandeep; Zhang, Heye; Mukhopadhyay, Subhas Chandra; Li, Chunyue; Wang, Yumei; Li, Guanglin; Wu, Wanqing; Zhang, Yuan-Ting

2015-01-01

Body Sensor Network (BSN) is a network of several associated sensor nodes on, inside or around the human body to monitor vital signals, such as, Electroencephalogram (EEG), Photoplethysmography (PPG), Electrocardiogram (ECG), etc. Each sensor node in BSN delivers major information; therefore, it is very significant to provide data confidentiality and security. All existing approaches to secure BSN are based on complex cryptographic key generation procedures, which not only demands high resource utilization and computation time, but also consumes large amount of energy, power and memory during data transmission. However, it is indispensable to put forward energy efficient and computationally less complex authentication technique for BSN. In this paper, a novel biometric-based algorithm is proposed, which utilizes Heart Rate Variability (HRV) for simple key generation process to secure BSN. Our proposed algorithm is compared with three data authentication techniques, namely Physiological Signal based Key Agreement (PSKA), Data Encryption Standard (DES) and Rivest Shamir Adleman (RSA). Simulation is performed in Matlab and results suggest that proposed algorithm is quite efficient in terms of transmission time utilization, average remaining energy and total power consumption. PMID:26131666

Two-key concurrent responding: response-reinforcement dependencies and blackouts1

PubMed Central

Herbert, Emily W.

1970-01-01

Two-key concurrent responding was maintained for three pigeons by a single variable-interval 1-minute schedule of reinforcement in conjunction with a random number generator that assigned feeder operations between keys with equal probability. The duration of blackouts was varied between keys when each response initiated a blackout, and grain arranged by the variable-interval schedule was automatically presented after a blackout (Exp. I). In Exp. II every key peck, except for those that produced grain, initiated a blackout, and grain was dependent upon a response following a blackout. For each pigeon in Exp. I and for one pigeon in Exp. II, the relative frequency of responding on a key approximated, i.e., matched, the relative reciprocal of the duration of the blackout interval on that key. In a third experiment, blackouts scheduled on a variable-interval were of equal duration on the two keys. For one key, grain automatically followed each blackout; for the other key, grain was dependent upon a response and never followed a blackout. The relative frequency of responding on the former key, i.e., the delay key, better approximated the negative exponential function obtained by Chung (1965) than the matching function predicted by Chung and Herrnstein (1967). PMID:16811458

Impact of problem-based, active learning on graduation rates for 10 generations of Dutch medical students.

PubMed

Schmidt, Henk G; Cohen-Schotanus, Janke; Arends, Lidia R

2009-03-01

We aimed to study the effects of active-learning curricula on graduation rates of students and on the length of time needed to graduate. Graduation rates for 10 generations of students enrolling in the eight Dutch medical schools between 1989 and 1998 were analysed. In addition, time needed to graduate was recorded. Three of the eight schools had curricula emphasising active learning, small-group instruction and limited numbers of lectures; the other five had conventional curricula to varying degrees. Overall, the active-learning curricula graduated on average 8% more students per year, and these students graduated on average 5 months earlier than their colleagues from conventional curricula. Four hypotheses potentially explaining the effect of active learning on graduation rate and study duration were considered: (i) active-learning curricula promote the social and academic integration of students; (ii) active-learning curricula attract brighter students; (iii) active-learning curricula retain more poor students, and (iv) the active engagement of students with their study required by active-learning curricula induces better academic performance and, hence, lower dropout rates. The first three hypotheses had to be rejected. It was concluded that the better-learning hypothesis provides the most parsimonious account for the data.

Vibrational sum-frequency generation spectroscopy of lipid bilayers at repetition rates up to 100 kHz

NASA Astrophysics Data System (ADS)

Yesudas, Freeda; Mero, Mark; Kneipp, Janina; Heiner, Zsuzsanna

2018-03-01

Broadband vibrational sum-frequency generation (BB-VSFG) spectroscopy has become a well-established surface analytical tool capable of identifying the orientation and structure of molecular layers. A straightforward way to boost the sensitivity of the technique could be to increase the laser repetition rate beyond that of standard BB-VSFG spectrometers, which rely on Ti:sapphire lasers operating at repetition rates of 1-5 kHz. Nevertheless, possible thermally induced artifacts in the vibrational spectra due to higher laser average powers are unexplored. Here, we discuss laser power induced temperature accumulation effects that distort the BB-VSFG spectra of 1,2-diacyl-sn-glycero-3-phosphocholine at an interface between two transparent phases at repetition rates of 5, 10, 50, and 100 kHz at constant pulse energy. No heat-induced distortions were found in the spectra, suggesting that the increase in the laser repetition rate provides a feasible route to an improved signal-to-noise ratio or shorter data acquisition times in BB-VSFG spectroscopy for thin films on transparent substrates. The results have implications for future BB-VSFG spectrometers pushing the detection limit for molecular layers with low surface coverage.

Continuous-variable quantum key distribution protocols over noisy channels.

PubMed

García-Patrón, Raúl; Cerf, Nicolas J

2009-04-03

A continuous-variable quantum key distribution protocol based on squeezed states and heterodyne detection is introduced and shown to attain higher secret key rates over a noisy line than any other one-way Gaussian protocol. This increased resistance to channel noise can be understood as resulting from purposely adding noise to the signal that is converted into the secret key. This notion of noise-enhanced tolerance to noise also provides a better physical insight into the poorly understood discrepancies between the previously defined families of Gaussian protocols.

Key-value store with internal key-value storage interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bent, John M.; Faibish, Sorin; Ting, Dennis P. J.

A key-value store is provided having one or more key-value storage interfaces. A key-value store on at least one compute node comprises a memory for storing a plurality of key-value pairs; and an abstract storage interface comprising a software interface module that communicates with at least one persistent storage device providing a key-value interface for persistent storage of one or more of the plurality of key-value pairs, wherein the software interface module provides the one or more key-value pairs to the at least one persistent storage device in a key-value format. The abstract storage interface optionally processes one or moremore » batch operations on the plurality of key-value pairs. A distributed embodiment for a partitioned key-value store is also provided.« less

Hydrogen-based power generation from bioethanol steam reforming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tasnadi-Asztalos, Zs., E-mail: tazsolt@chem.ubbcluj.ro; Cormos, C. C., E-mail: cormos@chem.ubbcluj.ro; Agachi, P. S.

This paper is evaluating two power generation concepts based on hydrogen produced from bioethanol steam reforming at industrial scale without and with carbon capture. The power generation from bioethanol conversion is based on two important steps: hydrogen production from bioethanol catalytic steam reforming and electricity generation using a hydrogen-fuelled gas turbine. As carbon capture method to be assessed in hydrogen-based power generation from bioethanol steam reforming, the gas-liquid absorption using methyl-di-ethanol-amine (MDEA) was used. Bioethanol is a renewable energy carrier mainly produced from biomass fermentation. Steam reforming of bioethanol (SRE) provides a promising method for hydrogen and power production frommore » renewable resources. SRE is performed at high temperatures (e.g. 800-900°C) to reduce the reforming by-products (e.g. ethane, ethene). The power generation from hydrogen was done with M701G2 gas turbine (334 MW net power output). Hydrogen was obtained through catalytic steam reforming of bioethanol without and with carbon capture. For the evaluated plant concepts the following key performance indicators were assessed: fuel consumption, gross and net power outputs, net electrical efficiency, ancillary consumptions, carbon capture rate, specific CO{sub 2} emission etc. As the results show, the power generation based on bioethanol conversion has high energy efficiency and low carbon footprint.« less

Temperature modulates dengue virus epidemic growth rates through its effects on reproduction numbers and generation intervals

PubMed Central

Oidtman, Rachel J.; Huber, John H.; Kraemer, Moritz U. G.; Brady, Oliver J.; Johansson, Michael A.; Perkins, T. Alex

2017-01-01

Epidemic growth rate, r, provides a more complete description of the potential for epidemics than the more commonly studied basic reproduction number, R0, yet the former has never been described as a function of temperature for dengue virus or other pathogens with temperature-sensitive transmission. The need to understand the drivers of epidemics of these pathogens is acute, with arthropod-borne virus epidemics becoming increasingly problematic. We addressed this need by developing temperature-dependent descriptions of the two components of r—R0 and the generation interval—to obtain a temperature-dependent description of r. Our results show that the generation interval is highly sensitive to temperature, decreasing twofold between 25 and 35°C and suggesting that dengue virus epidemics may accelerate as temperatures increase, not only because of more infections per generation but also because of faster generations. Under the empirical temperature relationships that we considered, we found that r peaked at a temperature threshold that was robust to uncertainty in model parameters that do not depend on temperature. Although the precise value of this temperature threshold could be refined following future studies of empirical temperature relationships, the framework we present for identifying such temperature thresholds offers a new way to classify regions in which dengue virus epidemic intensity could either increase or decrease under future climate change. PMID:28723920

Temperature modulates dengue virus epidemic growth rates through its effects on reproduction numbers and generation intervals.

NASA Astrophysics Data System (ADS)

Siraj, A. S.; Oidtman, R. J.; Huber, J. H.; Kraemer, M. U.; Brady, O. J.; Johansson, M. A.; Perkins, T. A.

2017-12-01

Epidemic growth rate, r, provides a more complete description of the potential for epidemics than the more commonly studied basic reproduction number, R0, yet the former has never been described as a function of temperature for dengue virus or other pathogens with temperature-sensitive transmission. The need to understand the drivers of epidemics of these pathogens is acute, with arthropod-borne virus epidemics becoming increasingly problematic. We addressed this need by developing temperature-dependent descriptions of the two components of r—R0 and the generation interval—to obtain a temperature-dependent description of r. Our results show that the generation interval is highly sensitive to temperature, decreasing twofold between 25 and 35 °C and suggesting that dengue virus epidemics may accelerate as temperatures increase, not only because of more infections per generation but also because of faster generations. Under the empirical temperature relationships that we considered, we found that r peaked at a temperature threshold that was robust to uncertainty in model parameters that do not depend on temperature. Although the precise value of this temperature threshold could be refined following future studies of empirical temperature relationships, the framework we present for identifying such temperature thresholds offers a new way to classify regions in which dengue virus epidemic intensity could either increase or decrease under future climate change.

Cue generation and memory construction in direct and generative autobiographical memory retrieval.

PubMed

Harris, Celia B; O'Connor, Akira R; Sutton, John

2015-05-01

Theories of autobiographical memory emphasise effortful, generative search processes in memory retrieval. However recent research suggests that memories are often retrieved directly, without effortful search. We investigated whether direct and generative retrieval differed in the characteristics of memories recalled, or only in terms of retrieval latency. Participants recalled autobiographical memories in response to cue words. For each memory, they reported whether it was retrieved directly or generatively, rated its visuo-spatial perspective, and judged its accompanying recollective experience. Our results indicated that direct retrieval was commonly reported and was faster than generative retrieval, replicating recent findings. The characteristics of directly retrieved memories differed from generatively retrieved memories: directly retrieved memories had higher field perspective ratings and lower observer perspective ratings. However, retrieval mode did not influence recollective experience. We discuss our findings in terms of cue generation and content construction, and the implication for reconstructive models of autobiographical memory. Copyright © 2015 Elsevier Inc. All rights reserved.

Analysis of counterfactual quantum key distribution using error-correcting theory

NASA Astrophysics Data System (ADS)

Li, Yan-Bing

2014-10-01

Counterfactual quantum key distribution is an interesting direction in quantum cryptography and has been realized by some researchers. However, it has been pointed that its insecure in information theory when it is used over a high lossy channel. In this paper, we retry its security from a error-correcting theory point of view. The analysis indicates that the security flaw comes from the reason that the error rate in the users' raw key pair is as high as that under the Eve's attack when the loss rate exceeds 50 %.

Quantum key distribution session with 16-dimensional photonic states

PubMed Central

Etcheverry, S.; Cañas, G.; Gómez, E. S.; Nogueira, W. A. T.; Saavedra, C.; Xavier, G. B.; Lima, G.

2013-01-01

The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this problem by using individual quantum systems to generate correlated bits between remote parties, that can be used to extract a secret key. QKD with D-dimensional quantum channels provides security advantages that grow with increasing D. However, the vast majority of QKD implementations has been restricted to two dimensions. Here we demonstrate the feasibility of using higher dimensions for real-world quantum cryptography by performing, for the first time, a fully automated QKD session based on the BB84 protocol with 16-dimensional quantum states. Information is encoded in the single-photon transverse momentum and the required states are dynamically generated with programmable spatial light modulators. Our setup paves the way for future developments in the field of experimental high-dimensional QKD. PMID:23897033

Burning rate of solid wood measured in a heat release rate calorimeter

Treesearch

H. C. Tran; R. H. White

1992-01-01

Burning rate is a key factor in modeling fire growth and fire endurance of wood structures. This study investigated the burning rate of selected wood materials as determined by heat release, mass loss and charring rates. Thick samples of redwood, southern pine, red oak and basswood were tested in a heat release rate calorimeter. Results on ignitability and average beat...

An Improved EKG-Based Key Agreement Scheme for Body Area Networks

NASA Astrophysics Data System (ADS)

Ali, Aftab; Khan, Farrukh Aslam

Body area networks (BANs) play an important role in mobile health monitoring such as, monitoring the health of patients in a hospital or physical status of soldiers in a battlefield. By securing the BAN, we actually secure the lives of soldiers or patients. This work presents an electrocardiogram (EKG) based key agreement scheme using discrete wavelet transform (DWT) for the sake of generating a common key in a body area network. The use of EKG brings plug-and-play capability in BANs; i.e., the sensors are just placed on the human body and a secure communication is started among these sensors. The process is made secure by using the iris or fingerprints to lock and then unlock the blocks during exchange between the communicating sensors. The locking and unlocking is done through watermarking. When a watermark is added at the sender side, the block is locked and when it is removed at the receiver side, the block is unlocked. By using iris or fingerprints, the security of the technique improves and its plug-and-play capability is not affected. The analysis is done by using real 2-lead EKG data sampled at a rate of 125 Hz taken from MIT PhysioBank database.

A three-lead, programmable, and microcontroller-based electrocardiogram generator with frequency domain characteristics of heart rate variability.

PubMed

Wei, Ying-Chieh; Wei, Ying-Yu; Chang, Kai-Hsiung; Young, Ming-Shing

2012-04-01

The objective of this study is to design and develop a programmable electrocardiogram (ECG) generator with frequency domain characteristics of heart rate variability (HRV) which can be used to test the efficiency of ECG algorithms and to calibrate and maintain ECG equipment. We simplified and modified the three coupled ordinary differential equations in McSharry's model to a single differential equation to obtain the ECG signal. This system not only allows the signal amplitude, heart rate, QRS-complex slopes, and P- and T-wave position parameters to be adjusted, but can also be used to adjust the very low frequency, low frequency, and high frequency components of HRV frequency domain characteristics. The system can be tuned to function with HRV or not. When the HRV function is on, the average heart rate can be set to a value ranging from 20 to 122 beats per minute (BPM) with an adjustable variation of 1 BPM. When the HRV function is off, the heart rate can be set to a value ranging from 20 to 139 BPM with an adjustable variation of 1 BPM. The amplitude of the ECG signal can be set from 0.0 to 330 mV at a resolution of 0.005 mV. These parameters can be adjusted either via input through a keyboard or through a graphical user interface (GUI) control panel that was developed using LABVIEW. The GUI control panel depicts a preview of the ECG signal such that the user can adjust the parameters to establish a desired ECG morphology. A complete set of parameters can be stored in the flash memory of the system via a USB 2.0 interface. Our system can generate three different types of synthetic ECG signals for testing the efficiency of an ECG algorithm or calibrating and maintaining ECG equipment. © 2012 American Institute of Physics

A three-lead, programmable, and microcontroller-based electrocardiogram generator with frequency domain characteristics of heart rate variability

NASA Astrophysics Data System (ADS)

Wei, Ying-Chieh; Wei, Ying-Yu; Chang, Kai-Hsiung; Young, Ming-Shing

2012-04-01

The objective of this study is to design and develop a programmable electrocardiogram (ECG) generator with frequency domain characteristics of heart rate variability (HRV) which can be used to test the efficiency of ECG algorithms and to calibrate and maintain ECG equipment. We simplified and modified the three coupled ordinary differential equations in McSharry's model to a single differential equation to obtain the ECG signal. This system not only allows the signal amplitude, heart rate, QRS-complex slopes, and P- and T-wave position parameters to be adjusted, but can also be used to adjust the very low frequency, low frequency, and high frequency components of HRV frequency domain characteristics. The system can be tuned to function with HRV or not. When the HRV function is on, the average heart rate can be set to a value ranging from 20 to 122 beats per minute (BPM) with an adjustable variation of 1 BPM. When the HRV function is off, the heart rate can be set to a value ranging from 20 to 139 BPM with an adjustable variation of 1 BPM. The amplitude of the ECG signal can be set from 0.0 to 330 mV at a resolution of 0.005 mV. These parameters can be adjusted either via input through a keyboard or through a graphical user interface (GUI) control panel that was developed using LABVIEW. The GUI control panel depicts a preview of the ECG signal such that the user can adjust the parameters to establish a desired ECG morphology. A complete set of parameters can be stored in the flash memory of the system via a USB 2.0 interface. Our system can generate three different types of synthetic ECG signals for testing the efficiency of an ECG algorithm or calibrating and maintaining ECG equipment.

On-site SiH4 generator using hydrogen plasma generated in slit-type narrow gap

NASA Astrophysics Data System (ADS)

Takei, Norihisa; Shinoda, Fumiya; Kakiuchi, Hiroaki; Yasutake, Kiyoshi; Ohmi, Hiromasa

2018-06-01

We have been developing an on-site silane (SiH4) generator based on use of the chemical etching reaction between solid silicon (Si) and the high-density H atoms that are generated in high-pressure H2 plasma. In this study, we have developed a slit-type plasma source for high-efficiency SiH4 generation. High-density H2 plasma was generated in a narrow slit-type discharge gap using a 2.45 GHz microwave power supply. The plasma’s optical emission intensity distribution along the slit was measured and the resulting distribution was reflected by both the electric power distribution and the hydrogen gas flow. Because the Si etching rate strongly affects the SiH4 generation rate, the Si etching behavior was investigated with respect to variations in the experimental parameters. The weight etch rate increased monotonically with increasing input microwave power. However, the weight etch rate decreased with increasing H2 pressure and an increasing plasma gap. This reduction in the etch rate appears to be related to shrinkage of the plasma generation area because increased input power is required to maintain a constant plasma area with increasing H2 pressure and the increasing plasma gap. Additionally, the weight etch rate also increases with increasing H2 flow rate. The SiH4 generation rate of the slit-type plasma source was also evaluated using gas-phase Fourier transform infrared absorption spectroscopy and the material utilization efficiencies of both Si and the H2 gas for SiH4 gas formation were discussed. The main etch product was determined to be SiH4 and the developed plasma source achieved a SiH4 generation rate of 10 sccm (standard cubic centimeters per minute) at an input power of 900 W. In addition, the Si utilization efficiency exceeded 60%.

One Step Quantum Key Distribution Based on EPR Entanglement.

PubMed

Li, Jian; Li, Na; Li, Lei-Lei; Wang, Tao

2016-06-30

A novel quantum key distribution protocol is presented, based on entanglement and dense coding and allowing asymptotically secure key distribution. Considering the storage time limit of quantum bits, a grouping quantum key distribution protocol is proposed, which overcomes the vulnerability of first protocol and improves the maneuverability. Moreover, a security analysis is given and a simple type of eavesdropper's attack would introduce at least an error rate of 46.875%. Compared with the "Ping-pong" protocol involving two steps, the proposed protocol does not need to store the qubit and only involves one step.

The Combined Application of Impinger System and Permeation Tube for the Generation of Volatile Organic Compound Standard Gas Mixtures at Varying Diluent Flow Rates

PubMed Central

Kim, Ki-Hyun; Susaya, Janice; Cho, Jinwoo; Parker, David

2012-01-01

Commercial standard gas generators are often complex and expensive devices. The objective of this research was to assess the performance of a simplified glass impinger system for standard gas generation from a permeation tube (PT) device. The performance of the impinger standard gas generation system was assessed for four aromatic VOCs (benzene, toluene, ethylbenzene, and m-xylene; BTEX) at varying flow rates (FR) of 50 to 800 mL·min−1. Because actual permeation rate (APR) values deviated from those computed by the manufacturer's formula (MPR), new empirical relationships were developed to derive the predicted PR (PPR) of the target components. Experimental results corrected by such a formula indicate that the compatibility between the APR and MPR generally increased with low FR, while the reproducibility was generally reduced with decreasing flow rate. Although compatibility between different PRs is at a relatively small and narrow FR range, the use of correction formula is recommendable for the accurate use of PT. PMID:23112641

Florida Keys

NASA Image and Video Library

2002-12-13

The Florida Keys are a chain of islands, islets and reefs extending from Virginia Key to the Dry Tortugas for about 309 kilometers (192 miles). The keys are chiefly limestone and coral formations. The larger islands of the group are Key West (with its airport), Key Largo, Sugarloaf Key, and Boca Chica Key. A causeway extends from the mainland to Key West. This image was acquired on October 28, 2001, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. http://photojournal.jpl.nasa.gov/catalog/PIA03890

Eavesdropping on counterfactual quantum key distribution with finite resources

NASA Astrophysics Data System (ADS)

Liu, Xingtong; Zhang, Bo; Wang, Jian; Tang, Chaojing; Zhao, Jingjing; Zhang, Sheng

2014-08-01

A striking scheme called "counterfactual quantum cryptography" gives a conceptually new approach to accomplish the task of key distribution. It allows two legitimate parties to share a secret even though a particle carrying secret information is not, in fact, transmitted through the quantum channel. Since an eavesdropper cannot directly access the entire quantum system of each signal particle, the protocol seems to provide practical security advantages. However, here we propose an eavesdropping method which works on the scheme in a finite key scenario. We show that, for practical systems only generating a finite number of keys, the eavesdropping can obtain all of the secret information without being detected. We also present a improved protocol as a countermeasure against this attack.

Building a better methane generation model: Validating models with methane recovery rates from 35 Canadian landfills.

PubMed

Thompson, Shirley; Sawyer, Jennifer; Bonam, Rathan; Valdivia, J E

2009-07-01

The German EPER, TNO, Belgium, LandGEM, and Scholl Canyon models for estimating methane production were compared to methane recovery rates for 35 Canadian landfills, assuming that 20% of emissions were not recovered. Two different fractions of degradable organic carbon (DOC(f)) were applied in all models. Most models performed better when the DOC(f) was 0.5 compared to 0.77. The Belgium, Scholl Canyon, and LandGEM version 2.01 models produced the best results of the existing models with respective mean absolute errors compared to methane generation rates (recovery rates + 20%) of 91%, 71%, and 89% at 0.50 DOC(f) and 171%, 115%, and 81% at 0.77 DOC(f). The Scholl Canyon model typically overestimated methane recovery rates and the LandGEM version 2.01 model, which modifies the Scholl Canyon model by dividing waste by 10, consistently underestimated methane recovery rates; this comparison suggested that modifying the divisor for waste in the Scholl Canyon model between one and ten could improve its accuracy. At 0.50 DOC(f) and 0.77 DOC(f) the modified model had the lowest absolute mean error when divided by 1.5 yielding 63 +/- 45% and 2.3 yielding 57 +/- 47%, respectively. These modified models reduced error and variability substantially and both have a strong correlation of r = 0.92.

Fully device-independent quantum key distribution.

PubMed

Vazirani, Umesh; Vidick, Thomas

2014-10-03

Quantum cryptography promises levels of security that are impossible to replicate in a classical world. Can this security be guaranteed even when the quantum devices on which the protocol relies are untrusted? This central question dates back to the early 1990s when the challenge of achieving device-independent quantum key distribution was first formulated. We answer this challenge by rigorously proving the device-independent security of a slight variant of Ekert's original entanglement-based protocol against the most general (coherent) attacks. The resulting protocol is robust: While assuming only that the devices can be modeled by the laws of quantum mechanics and are spatially isolated from each other and from any adversary's laboratory, it achieves a linear key rate and tolerates a constant noise rate in the devices. In particular, the devices may have quantum memory and share arbitrary quantum correlations with the eavesdropper. The proof of security is based on a new quantitative understanding of the monogamous nature of quantum correlations in the context of a multiparty protocol.

Fully Device-Independent Quantum Key Distribution

NASA Astrophysics Data System (ADS)

Vazirani, Umesh; Vidick, Thomas

2014-10-01

Quantum cryptography promises levels of security that are impossible to replicate in a classical world. Can this security be guaranteed even when the quantum devices on which the protocol relies are untrusted? This central question dates back to the early 1990s when the challenge of achieving device-independent quantum key distribution was first formulated. We answer this challenge by rigorously proving the device-independent security of a slight variant of Ekert's original entanglement-based protocol against the most general (coherent) attacks. The resulting protocol is robust: While assuming only that the devices can be modeled by the laws of quantum mechanics and are spatially isolated from each other and from any adversary's laboratory, it achieves a linear key rate and tolerates a constant noise rate in the devices. In particular, the devices may have quantum memory and share arbitrary quantum correlations with the eavesdropper. The proof of security is based on a new quantitative understanding of the monogamous nature of quantum correlations in the context of a multiparty protocol.

The high-rate data challenge: computing for the CBM experiment

NASA Astrophysics Data System (ADS)

Friese, V.; CBM Collaboration

2017-10-01

The Compressed Baryonic Matter experiment (CBM) is a next-generation heavy-ion experiment to be operated at the FAIR facility, currently under construction in Darmstadt, Germany. A key feature of CBM is very high interaction rate, exceeding those of contemporary nuclear collision experiments by several orders of magnitude. Such interaction rates forbid a conventional, hardware-triggered readout; instead, experiment data will be freely streaming from self-triggered front-end electronics. In order to reduce the huge raw data volume to a recordable rate, data will be selected exclusively on CPU, which necessitates partial event reconstruction in real-time. Consequently, the traditional segregation of online and offline software vanishes; an integrated on- and offline data processing concept is called for. In this paper, we will report on concepts and developments for computing for CBM as well as on the status of preparations for its first physics run.

Calculation of key reduction for B92 QKD protocol

NASA Astrophysics Data System (ADS)

Mehic, Miralem; Partila, Pavol; Tovarek, Jaromir; Voznak, Miroslav

2015-05-01

It is well known that Quantum Key Distribution (QKD) can be used with the highest level of security for distribution of the secret key, which is further used for symmetrical encryption. B92 is one of the oldest QKD protocols. It uses only two non-orthogonal states, each one coding for one bit-value. It is much faster and simpler when compared to its predecessors, but with the idealized maximum efficiencies of 25% over the quantum channel. B92 consists of several phases in which initial key is significantly reduced: secret key exchange, extraction of the raw key (sifting), error rate estimation, key reconciliation and privacy amplification. QKD communication is performed over two channels: the quantum channel and the classical public channel. In order to prevent a man-in-the-middle attack and modification of messages on the public channel, authentication of exchanged values must be performed. We used Wegman-Carter authentication because it describes an upper bound for needed symmetric authentication key. We explained the reduction of the initial key in each of QKD phases.