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Sample records for insecure quantum channel

  1. Insecurity of quantum secure computations

    Science.gov (United States)

    Lo, Hoi-Kwong

    1997-08-01

    It had been widely claimed that quantum mechanics can protect private information during public decision in, for example, the so-called two-party secure computation. If this were the case, quantum smart-cards, storing confidential information accessible only to a proper reader, could prevent fake teller machines from learning the PIN (personal identification number) from the customers' input. Although such optimism has been challenged by the recent surprising discovery of the insecurity of the so-called quantum bit commitment, the security of quantum two-party computation itself remains unaddressed. Here I answer this question directly by showing that all one-sided two-party computations (which allow only one of the two parties to learn the result) are necessarily insecure. As corollaries to my results, quantum one-way oblivious password identification and the so-called quantum one-out-of-two oblivious transfer are impossible. I also construct a class of functions that cannot be computed securely in any two-sided two-party computation. Nevertheless, quantum cryptography remains useful in key distribution and can still provide partial security in ``quantum money'' proposed by Wiesner.

  2. Comment on 'Quantum string seal is insecure'

    International Nuclear Information System (INIS)

    He Guangping

    2007-01-01

    An attack strategy was recently proposed by Chau [Phys. Rev. A 75, 012327 (2007)], which was claimed to be able to break all quantum string seal protocols. Here it will be shown that the attack cannot obtain nontrivial information and escape the detection simultaneously in a class of quantum string seal, including the one proposed by He [Int. J. Quantum Inf. 4, 677 (2006)]. Thus it is insufficient to conclude that all quantum string seals are insecure

  3. Insecurity of imperfect quantum bit seal

    International Nuclear Information System (INIS)

    Chau, H.F.

    2006-01-01

    Quantum bit seal is a way to encode a classical bit quantum mechanically so that everyone can obtain non-zero information on the value of the bit. Moreover, such an attempt should have a high chance of being detected by an authorized verifier. Surely, a reader looks for a way to get the maximum amount of information on the sealed bit and at the same time to minimize her chance of being caught. And a verifier picks a sealing scheme that maximizes his chance of detecting any measurement of the sealed bit. Here, I report a strategy that passes all measurement detection procedures at least half of the time for all quantum bit sealing schemes. This strategy also minimizes a reader's chance of being caught under a certain scheme. In this way, I extend the result of Bechmann-Pasquinucci et al. by proving that quantum seal is insecure in the case of imperfect sealed bit recovery

  4. Quantum Correlations Evolution Asymmetry in Quantum Channels

    International Nuclear Information System (INIS)

    Li Meng; Huang Yun-Feng; Guo Guang-Can

    2017-01-01

    It was demonstrated that the entanglement evolution of a specially designed quantum state in the bistochastic channel is asymmetric. In this work, we generalize the study of the quantum correlations, including entanglement and quantum discord, evolution asymmetry to various quantum channels. We found that the asymmetry of entanglement and quantum discord only occurs in some special quantum channels, and the behavior of the entanglement evolution may be quite different from the behavior of the quantum discord evolution. To quantum entanglement, in some channels it decreases monotonously with the increase of the quantum channel intensity. In some other channels, when we increase the intensity of the quantum channel, it decreases at first, then keeps zero for some time, and then rises up. To quantum discord, the evolution becomes more complex and you may find that it evolutes unsmoothly at some points. These results illustrate the strong dependence of the quantum correlations evolution on the property of the quantum channels. (paper)

  5. Entanglement-distillation attack on continuous-variable quantum key distribution in a turbulent atmospheric channel

    Science.gov (United States)

    Guo, Ying; Xie, Cailang; Liao, Qin; Zhao, Wei; Zeng, Guihua; Huang, Duan

    2017-08-01

    The survival of Gaussian quantum states in a turbulent atmospheric channel is of crucial importance in free-space continuous-variable (CV) quantum key distribution (QKD), in which the transmission coefficient will fluctuate in time, thus resulting in non-Gaussian quantum states. Different from quantum hacking of the imperfections of practical devices, here we propose a different type of attack by exploiting the security loopholes that occur in a real lossy channel. Under a turbulent atmospheric environment, the Gaussian states are inevitably afflicted by decoherence, which would cause a degradation of the transmitted entanglement. Therefore, an eavesdropper can perform an intercept-resend attack by applying an entanglement-distillation operation on the transmitted non-Gaussian mixed states, which allows the eavesdropper to bias the estimation of the parameters and renders the final keys shared between the legitimate parties insecure. Our proposal highlights the practical CV QKD vulnerabilities with free-space quantum channels, including the satellite-to-earth links, ground-to-ground links, and a link from moving objects to ground stations.

  6. Expected number of quantum channels in quantum networks

    Science.gov (United States)

    Chen, Xi; Wang, He-Ming; Ji, Dan-Tong; Mu, Liang-Zhu; Fan, Heng

    2015-07-01

    Quantum communication between nodes in quantum networks plays an important role in quantum information processing. Here, we proposed the use of the expected number of quantum channels as a measure of the efficiency of quantum communication for quantum networks. This measure quantified the amount of quantum information that can be teleported between nodes in a quantum network, which differs from classical case in that the quantum channels will be consumed if teleportation is performed. We further demonstrated that the expected number of quantum channels represents local correlations depicted by effective circles. Significantly, capacity of quantum communication of quantum networks quantified by ENQC is independent of distance for the communicating nodes, if the effective circles of communication nodes are not overlapped. The expected number of quantum channels can be enhanced through transformations of the lattice configurations of quantum networks via entanglement swapping. Our results can shed lights on the study of quantum communication in quantum networks.

  7. Reply to 'Comment on 'Quantum string seal is insecure''

    International Nuclear Information System (INIS)

    Chau, H. F.

    2007-01-01

    In Phys. Rev. A 76, 056301 (2007), He claimed that the proof in my earlier paper [Phys. Rev. A 75, 012327 (2007)] is insufficient to conclude the insecurity of all quantum string seals because my measurement strategy cannot obtain nontrivial information on the sealed string and escape detection at the same time. Here, I clarify that our disagreement comes from our adoption of two different criteria on the minimum amount of information a quantum string seal can reveal to members of the public. I also point out that He did not follow my measurement strategy correctly

  8. Reliable quantum communication over a quantum relay channel

    Energy Technology Data Exchange (ETDEWEB)

    Gyongyosi, Laszlo, E-mail: gyongyosi@hit.bme.hu [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117, Hungary and Information Systems Research Group, Mathematics and Natural Sciences, Hungarian Ac (Hungary); Imre, Sandor [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117 (Hungary)

    2014-12-04

    We show that reliable quantum communication over an unreliable quantum relay channels is possible. The coding scheme combines the results on the superadditivity of quantum channels and the efficient quantum coding approaches.

  9. Insecurity of position-based quantum-cryptography protocols against entanglement attacks

    International Nuclear Information System (INIS)

    Lau, Hoi-Kwan; Lo, Hoi-Kwong

    2011-01-01

    Recently, position-based quantum cryptography has been claimed to be unconditionally secure. On the contrary, here we show that the existing proposals for position-based quantum cryptography are, in fact, insecure if entanglement is shared among two adversaries. Specifically, we demonstrate how the adversaries can incorporate ideas of quantum teleportation and quantum secret sharing to compromise the security with certainty. The common flaw to all current protocols is that the Pauli operators always map a codeword to a codeword (up to an irrelevant overall phase). We propose a modified scheme lacking this property in which the same cheating strategy used to undermine the previous protocols can succeed with a rate of at most 85%. We prove the modified protocol is secure when the shared quantum resource between the adversaries is a two- or three-level system.

  10. Information transfer through quantum channels

    International Nuclear Information System (INIS)

    Kretschmann, D.

    2007-01-01

    This PhD thesis represents work done between Aug. 2003 and Dec. 2006 in Reinhard F. Werner's quantum information theory group at Technische Universitaet Braunschweig, and Artur Ekert's Centre for Quantum Computation at the University of Cambridge. My thesis falls into the field of abstract quantum information theory. This work investigates both fundamental properties of quantum channels and their asymptotic capacities for classical as well as quantum information transfer. Stinespring's theorem is the basic structure theorem for quantum channels. It implies that every quantum channel can be represented as a unitary evolution on an enlarged system. In Ch. 3 we present a continuity theorem for Stinespring's representation: two quantum channels are similar if and only if it is possible to find unitary implementations that are likewise similar, with dimension-independent norm bounds. The continuity theorem allows to derive a formulation of the information-disturbance tradeoff in terms of quantum channels, and a continuity estimate for the no-broadcasting principle. In Ch. 4 we then apply the continuity theorem to give a strengthened no-go proof for quantum bit commitment, an important cryptographic primitive. This result also provides a natural characterization of those protocols that fall outside the standard setting of unconditional security, and thus may allow secure bit commitment. We present a new such protocol whose security relies on decoherence in the receiver's lab. Ch. 5 reviews the capacities of quantum channels for the transfer of both classical and quantum information, and investigates several variations in the notion of channel capacity. Memory effects are then investigated in detail in Ch. 6. We advertise a model which is sufficiently general to encompass all causal automata: every quantum process in which the outputs up to any given time t do not depend on the inputs at times t'>t can be represented as a concatenated memory channel. We then explain how

  11. Information transfer through quantum channels

    Energy Technology Data Exchange (ETDEWEB)

    Kretschmann, D.

    2007-03-12

    This PhD thesis represents work done between Aug. 2003 and Dec. 2006 in Reinhard F. Werner's quantum information theory group at Technische Universitaet Braunschweig, and Artur Ekert's Centre for Quantum Computation at the University of Cambridge. My thesis falls into the field of abstract quantum information theory. This work investigates both fundamental properties of quantum channels and their asymptotic capacities for classical as well as quantum information transfer. Stinespring's theorem is the basic structure theorem for quantum channels. It implies that every quantum channel can be represented as a unitary evolution on an enlarged system. In Ch. 3 we present a continuity theorem for Stinespring's representation: two quantum channels are similar if and only if it is possible to find unitary implementations that are likewise similar, with dimension-independent norm bounds. The continuity theorem allows to derive a formulation of the information-disturbance tradeoff in terms of quantum channels, and a continuity estimate for the no-broadcasting principle. In Ch. 4 we then apply the continuity theorem to give a strengthened no-go proof for quantum bit commitment, an important cryptographic primitive. This result also provides a natural characterization of those protocols that fall outside the standard setting of unconditional security, and thus may allow secure bit commitment. We present a new such protocol whose security relies on decoherence in the receiver's lab. Ch. 5 reviews the capacities of quantum channels for the transfer of both classical and quantum information, and investigates several variations in the notion of channel capacity. Memory effects are then investigated in detail in Ch. 6. We advertise a model which is sufficiently general to encompass all causal automata: every quantum process in which the outputs up to any given time t do not depend on the inputs at times t'>t can be represented as a concatenated memory

  12. Channel Simulation in Quantum Metrology

    Directory of Open Access Journals (Sweden)

    Laurenza Riccardo

    2018-04-01

    Full Text Available In this review we discuss how channel simulation can be used to simplify the most general protocols of quantum parameter estimation, where unlimited entanglement and adaptive joint operations may be employed. Whenever the unknown parameter encoded in a quantum channel is completely transferred in an environmental program state simulating the channel, the optimal adaptive estimation cannot beat the standard quantum limit. In this setting, we elucidate the crucial role of quantum teleportation as a primitive operation which allows one to completely reduce adaptive protocols over suitable teleportation-covariant channels and derive matching upper and lower bounds for parameter estimation. For these channels,wemay express the quantum Cramér Rao bound directly in terms of their Choi matrices. Our review considers both discrete- and continuous-variable systems, also presenting some new results for bosonic Gaussian channels using an alternative sub-optimal simulation. It is an open problem to design simulations for quantum channels that achieve the Heisenberg limit.

  13. Local quantum channels preserving classical correlations

    International Nuclear Information System (INIS)

    Guo Zhihua; Cao Huaixin

    2013-01-01

    The aim of this paper is to discuss local quantum channels that preserve classical correlations. First, we give two equivalent characterizations of classical correlated states. Then we obtain the relationships among classical correlation-preserving local quantum channels, commutativity-preserving local quantum channels and commutativity-preserving quantum channels on each subsystem. Furthermore, for a two-qubit system, we show the general form of classical correlation-preserving local quantum channels. (paper)

  14. Efficient universal quantum channel simulation in IBM's cloud quantum computer

    Science.gov (United States)

    Wei, Shi-Jie; Xin, Tao; Long, Gui-Lu

    2018-07-01

    The study of quantum channels is an important field and promises a wide range of applications, because any physical process can be represented as a quantum channel that transforms an initial state into a final state. Inspired by the method of performing non-unitary operators by the linear combination of unitary operations, we proposed a quantum algorithm for the simulation of the universal single-qubit channel, described by a convex combination of "quasi-extreme" channels corresponding to four Kraus operators, and is scalable to arbitrary higher dimension. We demonstrated the whole algorithm experimentally using the universal IBM cloud-based quantum computer and studied the properties of different qubit quantum channels. We illustrated the quantum capacity of the general qubit quantum channels, which quantifies the amount of quantum information that can be protected. The behavior of quantum capacity in different channels revealed which types of noise processes can support information transmission, and which types are too destructive to protect information. There was a general agreement between the theoretical predictions and the experiments, which strongly supports our method. By realizing the arbitrary qubit channel, this work provides a universally- accepted way to explore various properties of quantum channels and novel prospect for quantum communication.

  15. Multiplicative properties of quantum channels

    Science.gov (United States)

    Rahaman, Mizanur

    2017-08-01

    In this paper, we study the multiplicative behaviour of quantum channels, mathematically described by trace preserving, completely positive maps on matrix algebras. It turns out that the multiplicative domain of a unital quantum channel has a close connection to its spectral properties. A structure theorem (theorem 2.5), which reveals the automorphic property of an arbitrary unital quantum channel on a subalgebra, is presented. Various classes of quantum channels (irreducible, primitive, etc) are then analysed in terms of this stabilising subalgebra. The notion of the multiplicative index of a unital quantum channel is introduced, which measures the number of times a unital channel needs to be composed with itself for the multiplicative algebra to stabilise. We show that the maps that have trivial multiplicative domains are dense in completely bounded norm topology in the set of all unital completely positive maps. Some applications in quantum information theory are discussed.

  16. Quantum Communication Scheme Using Non-symmetric Quantum Channel

    International Nuclear Information System (INIS)

    Cao Haijing; Chen Zhonghua; Song Heshan

    2008-01-01

    A theoretical quantum communication scheme based on entanglement swapping and superdense coding is proposed with a 3-dimensional Bell state and 2-dimensional Bell state function as quantum channel. quantum key distribution and quantum secure direct communication can be simultaneously accomplished in the scheme. The scheme is secure and has high source capacity. At last, we generalize the quantum communication scheme to d-dimensional quantum channel

  17. Quantum capacity under adversarial quantum noise: arbitrarily varying quantum channels

    OpenAIRE

    Ahlswede, Rudolf; Bjelakovic, Igor; Boche, Holger; Noetzel, Janis

    2010-01-01

    We investigate entanglement transmission over an unknown channel in the presence of a third party (called the adversary), which is enabled to choose the channel from a given set of memoryless but non-stationary channels without informing the legitimate sender and receiver about the particular choice that he made. This channel model is called arbitrarily varying quantum channel (AVQC). We derive a quantum version of Ahlswede's dichotomy for classical arbitrarily varying channels. This includes...

  18. Quantum-correlation breaking channels, quantum conditional probability and Perron-Frobenius theory

    Science.gov (United States)

    Chruściński, Dariusz

    2013-03-01

    Using the quantum analog of conditional probability and classical Bayes theorem we discuss some aspects of particular entanglement breaking channels: quantum-classical and classical-classical channels. Applying the quantum analog of Perron-Frobenius theorem we generalize the recent result of Korbicz et al. (2012) [8] on full and spectrum broadcasting from quantum-classical channels to arbitrary quantum channels.

  19. Quantum steganography with noisy quantum channels

    International Nuclear Information System (INIS)

    Shaw, Bilal A.; Brun, Todd A.

    2011-01-01

    Steganography is the technique of hiding secret information by embedding it in a seemingly ''innocent'' message. We present protocols for hiding quantum information by disguising it as noise in a codeword of a quantum error-correcting code. The sender (Alice) swaps quantum information into the codeword and applies a random choice of unitary operation, drawing on a secret random key she shares with the receiver (Bob). Using the key, Bob can retrieve the information, but an eavesdropper (Eve) with the power to monitor the channel, but without the secret key, cannot distinguish the message from channel noise. We consider two types of protocols: one in which the hidden quantum information is stored locally in the codeword, and another in which it is embedded in the space of error syndromes. We analyze how difficult it is for Eve to detect the presence of secret messages, and estimate rates of steganographic communication and secret key consumption for specific protocols and examples of error channels. We consider both the case where there is no actual noise in the channel (so that all errors in the codeword result from the deliberate actions of Alice), and the case where the channel is noisy and not controlled by Alice and Bob.

  20. Quantum capacity of Pauli channels with memory

    International Nuclear Information System (INIS)

    Huang Peng; He Guangqiang; Lu Yuan; Zeng Guihua

    2011-01-01

    The amount of coherent quantum information that can be reliably transmitted down the memory Pauli channels with Markovian correlated noise is investigated. Two methods for evaluating the quantum capacity of the memory Pauli channels are proposed to try to trace the memory effect on the transmissions of quantum information. We show that the evaluation of quantum capacity can be reduced to the calculation of the initial memory state of each successive transmission. Furthermore, we derive quantum capacities of the memory phase flip channel, bit flip channel and bit-phase flip channel. Also, a lower bound of the quantum capacity of the memory depolarizing channel is obtained. An increase of the degree of memory of the channels has a positive effect on the increase of their quantum capacities.

  1. Quantum channels and their entropic characteristics

    International Nuclear Information System (INIS)

    Holevo, A S; Giovannetti, V

    2012-01-01

    One of the major achievements of the recently emerged quantum information theory is the introduction and thorough investigation of the notion of a quantum channel which is a basic building block of any data-transmitting or data-processing system. This development resulted in an elaborated structural theory and was accompanied by the discovery of a whole spectrum of entropic quantities, notably the channel capacities, characterizing information-processing performance of the channels. This paper gives a survey of the main properties of quantum channels and of their entropic characterization, with a variety of examples for finite-dimensional quantum systems. We also touch upon the 'continuous-variables' case, which provides an arena for quantum Gaussian systems. Most of the practical realizations of quantum information processing were implemented in such systems, in particular based on principles of quantum optics. Several important entropic quantities are introduced and used to describe the basic channel capacity formulae. The remarkable role of specific quantum correlations—entanglement—as a novel communication resource is stressed.

  2. Proof of the insecurity of quantum secret sharing based on the Smolin bound entangled states

    International Nuclear Information System (INIS)

    Ya-Fei, Yu; Zhi-Ming, Zhang

    2009-01-01

    This paper reconsiders carefully the possibility of using the Smolin bound entangled states as the carrier for sharing quantum secret. It finds that the process of quantum secret sharing based on Smolin states has insecurity though the Smolin state was reported to violate maximally the two-setting Bell-inequality. The general proof is given. (general)

  3. A linearization of quantum channels

    Science.gov (United States)

    Crowder, Tanner

    2015-06-01

    Because the quantum channels form a compact, convex set, we can express any quantum channel as a convex combination of extremal channels. We give a Euclidean representation for the channels whose inverses are also valid channels; these are a subset of the extreme points. They form a compact, connected Lie group, and we calculate its Lie algebra. Lastly, we calculate a maximal torus for the group and provide a constructive approach to decomposing any invertible channel into a product of elementary channels.

  4. Coherifying quantum channels

    Science.gov (United States)

    Korzekwa, Kamil; Czachórski, Stanisław; Puchała, Zbigniew; Życzkowski, Karol

    2018-04-01

    Is it always possible to explain random stochastic transitions between states of a finite-dimensional system as arising from the deterministic quantum evolution of the system? If not, then what is the minimal amount of randomness required by quantum theory to explain a given stochastic process? Here, we address this problem by studying possible coherifications of a quantum channel Φ, i.e., we look for channels {{{Φ }}}{ \\mathcal C } that induce the same classical transitions T, but are ‘more coherent’. To quantify the coherence of a channel Φ we measure the coherence of the corresponding Jamiołkowski state J Φ. We show that the classical transition matrix T can be coherified to reversible unitary dynamics if and only if T is unistochastic. Otherwise the Jamiołkowski state {J}{{Φ }}{ \\mathcal C } of the optimally coherified channel is mixed, and the dynamics must necessarily be irreversible. To assess the extent to which an optimal process {{{Φ }}}{ \\mathcal C } is indeterministic we find explicit bounds on the entropy and purity of {J}{{Φ }}{ \\mathcal C }, and relate the latter to the unitarity of {{{Φ }}}{ \\mathcal C }. We also find optimal coherifications for several classes of channels, including all one-qubit channels. Finally, we provide a non-optimal coherification procedure that works for an arbitrary channel Φ and reduces its rank (the minimal number of required Kraus operators) from {d}2 to d.

  5. Trade-off capacities of the quantum Hadamard channels

    International Nuclear Information System (INIS)

    Bradler, Kamil; Hayden, Patrick; Touchette, Dave; Wilde, Mark M.

    2010-01-01

    Coding theorems in quantum Shannon theory express the ultimate rates at which a sender can transmit information over a noisy quantum channel. More often than not, the known formulas expressing these transmission rates are intractable, requiring an optimization over an infinite number of uses of the channel. Researchers have rarely found quantum channels with a tractable classical or quantum capacity, but when such a finding occurs, it demonstrates a complete understanding of that channel's capabilities for transmitting classical or quantum information. Here we show that the three-dimensional capacity region for entanglement-assisted transmission of classical and quantum information is tractable for the Hadamard class of channels. Examples of Hadamard channels include generalized dephasing channels, cloning channels, and the Unruh channel. The generalized dephasing channels and the cloning channels are natural processes that occur in quantum systems through the loss of quantum coherence or stimulated emission, respectively. The Unruh channel is a noisy process that occurs in relativistic quantum information theory as a result of the Unruh effect and bears a strong relationship to the cloning channels. We give exact formulas for the entanglement-assisted classical and quantum communication capacity regions of these channels. The coding strategy for each of these examples is superior to a naieve time-sharing strategy, and we introduce a measure to determine this improvement.

  6. Quantum Capacity under Adversarial Quantum Noise: Arbitrarily Varying Quantum Channels

    Science.gov (United States)

    Ahlswede, Rudolf; Bjelaković, Igor; Boche, Holger; Nötzel, Janis

    2013-01-01

    We investigate entanglement transmission over an unknown channel in the presence of a third party (called the adversary), which is enabled to choose the channel from a given set of memoryless but non-stationary channels without informing the legitimate sender and receiver about the particular choice that he made. This channel model is called an arbitrarily varying quantum channel (AVQC). We derive a quantum version of Ahlswede's dichotomy for classical arbitrarily varying channels. This includes a regularized formula for the common randomness-assisted capacity for entanglement transmission of an AVQC. Quite surprisingly and in contrast to the classical analog of the problem involving the maximal and average error probability, we find that the capacity for entanglement transmission of an AVQC always equals its strong subspace transmission capacity. These results are accompanied by different notions of symmetrizability (zero-capacity conditions) as well as by conditions for an AVQC to have a capacity described by a single-letter formula. In the final part of the paper the capacity of the erasure-AVQC is computed and some light shed on the connection between AVQCs and zero-error capacities. Additionally, we show by entirely elementary and operational arguments motivated by the theory of AVQCs that the quantum, classical, and entanglement-assisted zero-error capacities of quantum channels are generically zero and are discontinuous at every positivity point.

  7. Quantum communication under channel uncertainty

    International Nuclear Information System (INIS)

    Noetzel, Janis Christian Gregor

    2012-01-01

    This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

  8. Quantum-correlation breaking channels, quantum conditional probability and Perron–Frobenius theory

    International Nuclear Information System (INIS)

    Chruściński, Dariusz

    2013-01-01

    Using the quantum analog of conditional probability and classical Bayes theorem we discuss some aspects of particular entanglement breaking channels: quantum–classical and classical–classical channels. Applying the quantum analog of Perron–Frobenius theorem we generalize the recent result of Korbicz et al. (2012) [8] on full and spectrum broadcasting from quantum–classical channels to arbitrary quantum channels.

  9. Quantum-capacity-approaching codes for the detected-jump channel

    International Nuclear Information System (INIS)

    Grassl, Markus; Wei Zhaohui; Ji Zhengfeng; Zeng Bei

    2010-01-01

    The quantum-channel capacity gives the ultimate limit for the rate at which quantum data can be reliably transmitted through a noisy quantum channel. Degradable quantum channels are among the few channels whose quantum capacities are known. Given the quantum capacity of a degradable channel, it remains challenging to find a practical coding scheme which approaches capacity. Here we discuss code designs for the detected-jump channel, a degradable channel with practical relevance describing the physics of spontaneous decay of atoms with detected photon emission. We show that this channel can be used to simulate a binary classical channel with both erasures and bit flips. The capacity of the simulated classical channel gives a lower bound on the quantum capacity of the detected-jump channel. When the jump probability is small, it almost equals the quantum capacity. Hence using a classical capacity-approaching code for the simulated classical channel yields a quantum code which approaches the quantum capacity of the detected-jump channel.

  10. Quantum channels with a finite memory

    International Nuclear Information System (INIS)

    Bowen, Garry; Mancini, Stefano

    2004-01-01

    In this paper we study quantum communication channels with correlated noise effects, i.e., quantum channels with memory. We derive a model for correlated noise channels that includes a channel memory state. We examine the case where the memory is finite, and derive bounds on the classical and quantum capacities. For the entanglement-assisted and unassisted classical capacities it is shown that these bounds are attainable for certain classes of channel. Also, we show that the structure of any finite-memory state is unimportant in the asymptotic limit, and specifically, for a perfect finite-memory channel where no information is lost to the environment, achieving the upper bound implies that the channel is asymptotically noiseless

  11. Quantum communication under channel uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Noetzel, Janis Christian Gregor

    2012-09-06

    This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

  12. Disguising quantum channels by mixing and channel distance trade-off

    International Nuclear Information System (INIS)

    Fung, Chi-Hang Fred; Chau, H F

    2014-01-01

    We consider the reverse problem of the distinguishability of two quantum channels, which we call the disguising problem. Given two quantum channels, the goal here is to make the two channels identical by mixing with some other channels with minimal mixing probabilities. This quantifies how much one channel can disguise as the other. In addition, the possibility to trade-off between the two mixing probabilities allows one channel to be more preserved (less mixed) at the expense of the other. We derive lower- and upper-bounds of the trade-off curve and apply them to a few example channels. Optimal trade-off is obtained in one example. We relate the disguising problem and the distinguishability problem by showing that the former can lower and upper bound the diamond norm. We also show that the disguising problem gives an upper-bound on the key generation rate in quantum cryptography. (paper)

  13. Strictly contractive quantum channels and physically realizable quantum computers

    International Nuclear Information System (INIS)

    Raginsky, Maxim

    2002-01-01

    We study the robustness of quantum computers under the influence of errors modeled by strictly contractive channels. A channel T is defined to be strictly contractive if, for any pair of density operators ρ, σ in its domain, parallel Tρ-Tσ parallel 1 ≤k parallel ρ-σ parallel 1 for some 0≤k 1 denotes the trace norm). In other words, strictly contractive channels render the states of the computer less distinguishable in the sense of quantum detection theory. Starting from the premise that all experimental procedures can be carried out with finite precision, we argue that there exists a physically meaningful connection between strictly contractive channels and errors in physically realizable quantum computers. We show that, in the absence of error correction, sensitivity of quantum memories and computers to strictly contractive errors grows exponentially with storage time and computation time, respectively, and depends only on the constant k and the measurement precision. We prove that strict contractivity rules out the possibility of perfect error correction, and give an argument that approximate error correction, which covers previous work on fault-tolerant quantum computation as a special case, is possible

  14. Nonadditivity of quantum capacities of quantum multiple-access channels and the butterfly network

    International Nuclear Information System (INIS)

    Huang Peng; He Guangqiang; Zhu Jun; Zeng Guihua

    2011-01-01

    Multipartite quantum information transmission without additional classical resources is investigated. We show purely quantum superadditivity of quantum capacity regions of quantum memoryless multiple-access (MA) channels, which are not entanglement breaking. Also, we find that the superadditivity holds when the MA channel extends to the quantum butterfly network, which can achieve quantum network coding. The present widespread effects for the channels which enable entanglement distribution have not been revealed for multipartite scenarios.

  15. Topics in quantum cryptography, quantum error correction, and channel simulation

    Science.gov (United States)

    Luo, Zhicheng

    In this thesis, we mainly investigate four different topics: efficiently implementable codes for quantum key expansion [51], quantum error-correcting codes based on privacy amplification [48], private classical capacity of quantum channels [44], and classical channel simulation with quantum side information [49, 50]. For the first topic, we propose an efficiently implementable quantum key expansion protocol, capable of increasing the size of a pre-shared secret key by a constant factor. Previously, the Shor-Preskill proof [64] of the security of the Bennett-Brassard 1984 (BB84) [6] quantum key distribution protocol relied on the theoretical existence of good classical error-correcting codes with the "dual-containing" property. But the explicit and efficiently decodable construction of such codes is unknown. We show that we can lift the dual-containing constraint by employing the non-dual-containing codes with excellent performance and efficient decoding algorithms. For the second topic, we propose a construction of Calderbank-Shor-Steane (CSS) [19, 68] quantum error-correcting codes, which are originally based on pairs of mutually dual-containing classical codes, by combining a classical code with a two-universal hash function. We show, using the results of Renner and Koenig [57], that the communication rates of such codes approach the hashing bound on tensor powers of Pauli channels in the limit of large block-length. For the third topic, we prove a regularized formula for the secret key assisted capacity region of a quantum channel for transmitting private classical information. This result parallels the work of Devetak on entanglement assisted quantum communication capacity. This formula provides a new family protocol, the private father protocol, under the resource inequality framework that includes the private classical communication without the assisted secret keys as a child protocol. For the fourth topic, we study and solve the problem of classical channel

  16. Volume of the space of qubit-qubit channels and state transformations under random quantum channels

    OpenAIRE

    Lovas, Attila; Andai, Attila

    2017-01-01

    The simplest building blocks for quantum computations are the qubit-qubit quantum channels. In this paper, we analyze the structure of these channels via their Choi representation. The restriction of a quantum channel to the space of classical states (i.e. probability distributions) is called the underlying classical channel. The structure of quantum channels over a fixed classical channel is studied, the volume of general and unital qubit channels with respect to the Lebesgue measure is comp...

  17. Spin chain model for correlated quantum channels

    Energy Technology Data Exchange (ETDEWEB)

    Rossini, Davide [International School for Advanced Studies SISSA/ISAS, via Beirut 2-4, I-34014 Trieste (Italy); Giovannetti, Vittorio; Montangero, Simone [NEST-CNR-INFM and Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy)], E-mail: monta@sns.it

    2008-11-15

    We analyze the quality of the quantum information transmission along a correlated quantum channel by studying the average fidelity between input and output states and the average output purity, giving bounds for the entropy of the channel. Noise correlations in the channel are modeled by the coupling of each channel use with an element of a one-dimensional interacting quantum spin chain. Criticality of the environment chain is seen to emerge in the changes of the fidelity and of the purity.

  18. Quantum and Private Capacities of Low-Noise Channels

    Science.gov (United States)

    Leditzky, Felix; Leung, Debbie; Smith, Graeme

    2018-04-01

    We determine both the quantum and the private capacities of low-noise quantum channels to leading orders in the channel's distance to the perfect channel. It has been an open problem for more than 20 yr to determine the capacities of some of these low-noise channels such as the depolarizing channel. We also show that both capacities are equal to the single-letter coherent information of the channel, again to leading orders. We thus find that, in the low-noise regime, superadditivity and degenerate codes have a negligible benefit for the quantum capacity, and shielding does not improve the private capacity beyond the quantum capacity, in stark contrast to the situation when noisier channels are considered.

  19. Belief propagation decoding of quantum channels by passing quantum messages

    International Nuclear Information System (INIS)

    Renes, Joseph M

    2017-01-01

    The belief propagation (BP) algorithm is a powerful tool in a wide range of disciplines from statistical physics to machine learning to computational biology, and is ubiquitous in decoding classical error-correcting codes. The algorithm works by passing messages between nodes of the factor graph associated with the code and enables efficient decoding of the channel, in some cases even up to the Shannon capacity. Here we construct the first BP algorithm which passes quantum messages on the factor graph and is capable of decoding the classical–quantum channel with pure state outputs. This gives explicit decoding circuits whose number of gates is quadratic in the code length. We also show that this decoder can be modified to work with polar codes for the pure state channel and as part of a decoder for transmitting quantum information over the amplitude damping channel. These represent the first explicit capacity-achieving decoders for non-Pauli channels. (fast track communication)

  20. Belief propagation decoding of quantum channels by passing quantum messages

    Science.gov (United States)

    Renes, Joseph M.

    2017-07-01

    The belief propagation (BP) algorithm is a powerful tool in a wide range of disciplines from statistical physics to machine learning to computational biology, and is ubiquitous in decoding classical error-correcting codes. The algorithm works by passing messages between nodes of the factor graph associated with the code and enables efficient decoding of the channel, in some cases even up to the Shannon capacity. Here we construct the first BP algorithm which passes quantum messages on the factor graph and is capable of decoding the classical-quantum channel with pure state outputs. This gives explicit decoding circuits whose number of gates is quadratic in the code length. We also show that this decoder can be modified to work with polar codes for the pure state channel and as part of a decoder for transmitting quantum information over the amplitude damping channel. These represent the first explicit capacity-achieving decoders for non-Pauli channels.

  1. On unified-entropy characterization of quantum channels

    International Nuclear Information System (INIS)

    Rastegin, A E

    2012-01-01

    We consider properties of quantum channels with the use of unified entropies. Extremal unravelings of quantum channel with respect to these entropies are examined. The concept of map entropy is extended in terms of the unified entropies. The map (q, s)-entropy is naturally defined as the unified (q, s)-entropy of a rescaled dynamical matrix of given quantum channel. Inequalities of Fannes type are obtained for introduced entropies in terms of both the trace and Frobenius norms of difference between corresponding dynamical matrices. Additivity properties of introduced map entropies are discussed. The known inequality of Lindblad with the entropy exchange is generalized to many of the unified entropies. For the tensor product of a pair of quantum channels, we derive a two-sided estimate on the output entropy of a maximally entangled input state. (paper)

  2. Quantum privacy and Schur product channels

    Science.gov (United States)

    Levick, Jeremy; Kribs, David W.; Pereira, Rajesh

    2017-12-01

    We investigate the quantum privacy properties of an important class of quantum channels, by making use of a connection with Schur product matrix operations and associated correlation matrix structures. For channels implemented by mutually commuting unitaries, which cannot privatise qubits encoded directly into subspaces, we nevertheless identify private algebras and subsystems that can be privatised by the channels. We also obtain further results by combining our analysis with tools from the theory of quasi-orthogonal operator algebras and graph theory.

  3. Chaos in quantum channels

    Energy Technology Data Exchange (ETDEWEB)

    Hosur, Pavan; Qi, Xiao-Liang [Department of Physics, Stanford University,476 Lomita Mall, Stanford, California 94305 (United States); Roberts, Daniel A. [Center for Theoretical Physics and Department of Physics, Massachusetts Institute of Technology,77 Massachusetts Ave, Cambridge, Massachusetts 02139 (United States); Yoshida, Beni [Perimeter Institute for Theoretical Physics,31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); Walter Burke Institute for Theoretical Physics, California Institute of Technology,1200 E California Blvd, Pasadena CA 91125 (United States)

    2016-02-01

    We study chaos and scrambling in unitary channels by considering their entanglement properties as states. Using out-of-time-order correlation functions to diagnose chaos, we characterize the ability of a channel to process quantum information. We show that the generic decay of such correlators implies that any input subsystem must have near vanishing mutual information with almost all partitions of the output. Additionally, we propose the negativity of the tripartite information of the channel as a general diagnostic of scrambling. This measures the delocalization of information and is closely related to the decay of out-of-time-order correlators. We back up our results with numerics in two non-integrable models and analytic results in a perfect tensor network model of chaotic time evolution. These results show that the butterfly effect in quantum systems implies the information-theoretic definition of scrambling.

  4. Reversibility conditions for quantum channels and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Shirokov, M E [Steklov Mathematical Institute of the Russian Academy of Sciences (Russian Federation)

    2013-08-31

    Conditions for a quantum channel (noncommutative Markov operator) to be reversible with respect to complete families of quantum states with bounded rank are obtained. A description of all quantum channels reversible with respect to a given (orthogonal or nonorthogonal) complete family of pure states is given. Some applications in quantum information theory are considered. Bibliography: 20 titles.

  5. Coherent eavesdropping attacks in tomographic quantum cryptography: Nonequivalence of quantum and classical key distillation

    International Nuclear Information System (INIS)

    Kaszlikowski, Dagomir; Lim, J.Y.; Englert, Berthold-Georg; Kwek, L.C.

    2005-01-01

    The security of a cryptographic key that is generated by communication through a noisy quantum channel relies on the ability to distill a shorter secure key sequence from a longer insecure one. We show that - for protocols that use quantum channels of any dimension and completely characterize them by state tomography - the noise threshold for classical advantage distillation of a specific kind is substantially lower than the threshold for quantum entanglement distillation if the eavesdropper can perform powerful coherent attacks. In marked contrast, earlier investigations had shown that the thresholds are identical for incoherent attacks on the same classical distillation scheme. It remains an open question whether other schemes for classical advantage distillation have higher thresholds for coherent eavesdropping attacks

  6. Quasi-superactivation for the classical capacity of quantum channels

    Energy Technology Data Exchange (ETDEWEB)

    Gyongyosi, Laszlo, E-mail: gyongyosi@hit.bme.hu [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117, Hungary and Information Systems Research Group, Mathematics and Natural Sciences, Hungarian Ac (Hungary); Imre, Sandor [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117 (Hungary)

    2014-12-04

    The superactivation effect has its roots in the extreme violation of additivity of the channel capacity and enables to reliably transmit quantum information over zero-capacity quantum channels. In this work we demonstrate a similar effect for the classical capacity of a quantum channel which previously was thought to be impossible.

  7. Almost all quantum channels are equidistant

    Science.gov (United States)

    Nechita, Ion; Puchała, Zbigniew; Pawela, Łukasz; Życzkowski, Karol

    2018-05-01

    In this work, we analyze properties of generic quantum channels in the case of large system size. We use random matrix theory and free probability to show that the distance between two independent random channels converges to a constant value as the dimension of the system grows larger. As a measure of the distance we use the diamond norm. In the case of a flat Hilbert-Schmidt distribution on quantum channels, we obtain that the distance converges to 1/2 +2/π , giving also an estimate for the maximum success probability for distinguishing the channels. We also consider the problem of distinguishing two random unitary rotations.

  8. Steganography on quantum pixel images using Shannon entropy

    Science.gov (United States)

    Laurel, Carlos Ortega; Dong, Shi-Hai; Cruz-Irisson, M.

    2016-07-01

    This paper presents a steganographical algorithm based on least significant bit (LSB) from the most significant bit information (MSBI) and the equivalence of a bit pixel image to a quantum pixel image, which permits to make the information communicate secretly onto quantum pixel images for its secure transmission through insecure channels. This algorithm offers higher security since it exploits the Shannon entropy for an image.

  9. Quantum Enigma Machines and the Locking Capacity of a Quantum Channel

    Directory of Open Access Journals (Sweden)

    Saikat Guha

    2014-01-01

    Full Text Available The locking effect is a phenomenon that is unique to quantum information theory and represents one of the strongest separations between the classical and quantum theories of information. The Fawzi-Hayden-Sen locking protocol harnesses this effect in a cryptographic context, whereby one party can encode n bits into n qubits while using only a constant-size secret key. The encoded message is then secure against any measurement that an eavesdropper could perform in an attempt to recover the message, but the protocol does not necessarily meet the composability requirements needed in quantum key distribution applications. In any case, the locking effect represents an extreme violation of Shannon’s classical theorem, which states that information-theoretic security holds in the classical case if and only if the secret key is the same size as the message. Given this intriguing phenomenon, it is of practical interest to study the effect in the presence of noise, which can occur in the systems of both the legitimate receiver and the eavesdropper. This paper formally defines the locking capacity of a quantum channel as the maximum amount of locked information that can be reliably transmitted to a legitimate receiver by exploiting many independent uses of a quantum channel and an amount of secret key sublinear in the number of channel uses. We provide general operational bounds on the locking capacity in terms of other well-known capacities from quantum Shannon theory. We also study the important case of bosonic channels, finding limitations on these channels’ locking capacity when coherent-state encodings are employed and particular locking protocols for these channels that might be physically implementable.

  10. Quantum Interference and Selectivity through Biological Ion Channels.

    Science.gov (United States)

    Salari, Vahid; Naeij, Hamidreza; Shafiee, Afshin

    2017-01-30

    The mechanism of selectivity in ion channels is still an open question in biology for more than half a century. Here, we suggest that quantum interference can be a solution to explain the selectivity mechanism in ion channels since interference happens between similar ions through the same size of ion channels. In this paper, we simulate two neighboring ion channels on a cell membrane with the famous double-slit experiment in physics to investigate whether there is any possibility of matter-wave interference of ions via movement through ion channels. Our obtained decoherence timescales indicate that the quantum states of ions can only survive for short times, i.e. ≈100 picoseconds in each channel and ≈17-53 picoseconds outside the channels, giving the result that the quantum interference of ions seems unlikely due to environmental decoherence. However, we discuss our results and raise few points, which increase the possibility of interference.

  11. Multi-server blind quantum computation over collective-noise channels

    Science.gov (United States)

    Xiao, Min; Liu, Lin; Song, Xiuli

    2018-03-01

    Blind quantum computation (BQC) enables ordinary clients to securely outsource their computation task to costly quantum servers. Besides two essential properties, namely correctness and blindness, practical BQC protocols also should make clients as classical as possible and tolerate faults from nonideal quantum channel. In this paper, using logical Bell states as quantum resource, we propose multi-server BQC protocols over collective-dephasing noise channel and collective-rotation noise channel, respectively. The proposed protocols permit completely or almost classical client, meet the correctness and blindness requirements of BQC protocol, and are typically practical BQC protocols.

  12. Quantum incompatibility of channels with general outcome operator algebras

    Science.gov (United States)

    Kuramochi, Yui

    2018-04-01

    A pair of quantum channels is said to be incompatible if they cannot be realized as marginals of a single channel. This paper addresses the general structure of the incompatibility of completely positive channels with a fixed quantum input space and with general outcome operator algebras. We define a compatibility relation for such channels by identifying the composite outcome space as the maximal (projective) C*-tensor product of outcome algebras. We show theorems that characterize this compatibility relation in terms of the concatenation and conjugation of channels, generalizing the recent result for channels with quantum outcome spaces. These results are applied to the positive operator valued measures (POVMs) by identifying each of them with the corresponding quantum-classical (QC) channel. We also give a characterization of the maximality of a POVM with respect to the post-processing preorder in terms of the conjugate channel of the QC channel. We consider another definition of compatibility of normal channels by identifying the composite outcome space with the normal tensor product of the outcome von Neumann algebras. We prove that for a given normal channel, the class of normally compatible channels is upper bounded by a special class of channels called tensor conjugate channels. We show the inequivalence of the C*- and normal compatibility relations for QC channels, which originates from the possibility and impossibility of copying operations for commutative von Neumann algebras in C*- and normal compatibility relations, respectively.

  13. Nonthermal Quantum Channels as a Thermodynamical Resource

    Science.gov (United States)

    Navascués, Miguel; García-Pintos, Luis Pedro

    2015-07-01

    Quantum thermodynamics can be understood as a resource theory, whereby thermal states are free and the only allowed operations are unitary transformations commuting with the total Hamiltonian of the system. Previous literature on the subject has just focused on transformations between different state resources, overlooking the fact that quantum operations which do not commute with the total energy also constitute a potentially valuable resource. In this Letter, given a number of nonthermal quantum channels, we study the problem of how to integrate them in a thermal engine so as to distill a maximum amount of work. We find that, in the limit of asymptotically many uses of each channel, the distillable work is an additive function of the considered channels, computable for both finite dimensional quantum operations and bosonic channels. We apply our results to bound the amount of distillable work due to the natural nonthermal processes postulated in the Ghirardi-Rimini-Weber (GRW) collapse model. We find that, although GRW theory predicts the possibility of extracting work from the vacuum at no cost, the power which a collapse engine could, in principle, generate is extremely low.

  14. Single-electron quantum tomography in quantum Hall edge channels

    International Nuclear Information System (INIS)

    Grenier, Ch; Degiovanni, P; Herve, R; Bocquillon, E; Parmentier, F D; Placais, B; Berroir, J M; Feve, G

    2011-01-01

    We propose a quantum tomography protocol to measure single-electron coherence in quantum Hall edge channels, and therefore access for the first time the wavefunction of single-electron excitations propagating in ballistic quantum conductors. Its implementation would open the way to quantitative studies of single-electron decoherence and would provide a quantitative tool for analyzing single- to few-electron sources. We show how this protocol could be implemented using ultrahigh-sensitivity noise measurement schemes.

  15. Capacity of a quantum memory channel correlated by matrix product states

    Science.gov (United States)

    Mulherkar, Jaideep; Sunitha, V.

    2018-04-01

    We study the capacity of a quantum channel where channel acts like controlled phase gate with the control being provided by a one-dimensional quantum spin chain environment. Due to the correlations in the spin chain, we get a quantum channel with memory. We derive formulas for the quantum capacity of this channel when the spin state is a matrix product state. Particularly, we derive exact formulas for the capacity of the quantum memory channel when the environment state is the ground state of the AKLT model and the Majumdar-Ghosh model. We find that the behavior of the capacity for the range of the parameters is analytic.

  16. Towards Holography via Quantum Source-Channel Codes

    Science.gov (United States)

    Pastawski, Fernando; Eisert, Jens; Wilming, Henrik

    2017-07-01

    While originally motivated by quantum computation, quantum error correction (QEC) is currently providing valuable insights into many-body quantum physics, such as topological phases of matter. Furthermore, mounting evidence originating from holography research (AdS/CFT) indicates that QEC should also be pertinent for conformal field theories. With this motivation in mind, we introduce quantum source-channel codes, which combine features of lossy compression and approximate quantum error correction, both of which are predicted in holography. Through a recent construction for approximate recovery maps, we derive guarantees on its erasure decoding performance from calculations of an entropic quantity called conditional mutual information. As an example, we consider Gibbs states of the transverse field Ising model at criticality and provide evidence that they exhibit nontrivial protection from local erasure. This gives rise to the first concrete interpretation of a bona fide conformal field theory as a quantum error correcting code. We argue that quantum source-channel codes are of independent interest beyond holography.

  17. On S-mixing entropy of quantum channels

    Science.gov (United States)

    Mukhamedov, Farrukh; Watanabe, Noboru

    2018-06-01

    In this paper, an S-mixing entropy of quantum channels is introduced as a generalization of Ohya's S-mixing entropy. We investigate several properties of the introduced entropy. Moreover, certain relations between the S-mixing entropy and the existing map and output entropies of quantum channels are investigated as well. These relations allowed us to find certain connections between separable states and the introduced entropy. Hence, there is a sufficient condition to detect entangled states. Moreover, several properties of the introduced entropy are investigated. Besides, entropies of qubit and phase-damping channels are calculated.

  18. Quantum Channels With Memory

    International Nuclear Information System (INIS)

    Rybar, T.

    2012-01-01

    Quantum memory channels represent a very general, yet simple and comprehensible model for causal processes. As such they have attracted considerable research interest, mostly aimed on their transfer capabilities and structure properties. Most notably it was shown that memory channels can be implemented via physically naturally motivated collision models. We also define the concept of repeatable channels and show that only unital channels can be implemented repeat ably with pure memory channels. In the special case of qubit channels we also show that every unital qubit channel has a repeatable implementation. We also briefly explore the possibilities of stroboscopical simulation of channels and show that all random unitary channels can be stroboscopically simulated. Particularly in qubit case, all indivisible qubit channels are also random unitary, hence for qubit all indivisible channels can be stroboscopically simulated. Memory channels also naturally capture the framework of correlated experiments. We develop methods to gather and interpret data obtained in such setting and in detail examine the two qubit case. We also show that for control unitary interactions the measured data will never contradict a simple unitary evolution. Thus no memory effects can be spotted then. (author)

  19. Relativistic quantum channel of communication through field quanta

    International Nuclear Information System (INIS)

    Cliche, M.; Kempf, A.

    2010-01-01

    Setups in which a system Alice emits field quanta that a system Bob receives are prototypical for wireless communication and have been extensively studied. In the most basic setup, Alice and Bob are modeled as Unruh-DeWitt detectors for scalar quanta, and the only noise in their communication is due to quantum fluctuations. For this basic setup, we construct the corresponding information-theoretic quantum channel. We calculate the classical channel capacity as a function of the spacetime separation, and we confirm that the classical as well as the quantum channel capacity are strictly zero for spacelike separations. We show that this channel can be used to entangle Alice and Bob instantaneously. Alice and Bob are shown to extract this entanglement from the vacuum through a Casimir-Polder effect.

  20. Moderate Deviation Analysis for Classical Communication over Quantum Channels

    Science.gov (United States)

    Chubb, Christopher T.; Tan, Vincent Y. F.; Tomamichel, Marco

    2017-11-01

    We analyse families of codes for classical data transmission over quantum channels that have both a vanishing probability of error and a code rate approaching capacity as the code length increases. To characterise the fundamental tradeoff between decoding error, code rate and code length for such codes we introduce a quantum generalisation of the moderate deviation analysis proposed by Altŭg and Wagner as well as Polyanskiy and Verdú. We derive such a tradeoff for classical-quantum (as well as image-additive) channels in terms of the channel capacity and the channel dispersion, giving further evidence that the latter quantity characterises the necessary backoff from capacity when transmitting finite blocks of classical data. To derive these results we also study asymmetric binary quantum hypothesis testing in the moderate deviations regime. Due to the central importance of the latter task, we expect that our techniques will find further applications in the analysis of other quantum information processing tasks.

  1. Quantum Privacy Amplification and the Security of Quantum Cryptography over Noisy Channels

    International Nuclear Information System (INIS)

    Deutsch, D.; Ekert, A.; Jozsa, R.; Macchiavello, C.; Popescu, S.; Sanpera, A.

    1996-01-01

    Existing quantum cryptographic schemes are not, as they stand, operable in the presence of noise on the quantum communication channel. Although they become operable if they are supplemented by classical privacy-amplification techniques, the resulting schemes are difficult to analyze and have not been proved secure. We introduce the concept of quantum privacy amplification and a cryptographic scheme incorporating it which is provably secure over a noisy channel. The scheme uses an open-quote open-quote entanglement purification close-quote close-quote procedure which, because it requires only a few quantum controlled-not and single-qubit operations, could be implemented using technology that is currently being developed. copyright 1996 The American Physical Society

  2. Channel's Concurrence and Quantum Teleportation

    Institute of Scientific and Technical Information of China (English)

    LING Yin-Sheng

    2005-01-01

    Concurrence can measure the entanglement property of a system. If the channel is a pure state, positive concurrence state can afford the good performance in the teleportation process. If the channel ia a mixed state, positive concurrence state cannot assure the good performance in the teleportation. The conditions of the positive concurrence and the quantum teleportation in the Heisenberg spin ring is derived.

  3. Quantum effects for particles channeling in a bent crystal

    Energy Technology Data Exchange (ETDEWEB)

    Feranchuk, Ilya, E-mail: iferanchuk@gmail.com [Atomic Molecular and Optical Physics Research Group, Ton Duc Thang University, 19 Nguyen Huu Tho Str., Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, 19 Nguyen Huu Tho Str., Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Belarusian State University, 4 Nezavisimosty Ave., 220030 Minsk (Belarus); San, Nguyen Quang [Belarusian State University, 4 Nezavisimosty Ave., 220030 Minsk (Belarus)

    2016-09-15

    Quantum mechanical theory for channeling of the relativistic charged particles in the bent crystals is considered in the paper. Quantum effects of under-barrier tunneling are essential when the radius of the curvature is closed to its critical value. In this case the wave functions of the quasi-stationary states corresponding to the particles captured in a channel are presented in the analytical form. The efficiency of channeling of the particles and their angular distribution at the exit crystal surface are calculated. Characteristic experimental parameters for observation the quantum effects are estimated.

  4. Channel capacities versus entanglement measures in multiparty quantum states

    International Nuclear Information System (INIS)

    Sen, Aditi; Sen, Ujjwal

    2010-01-01

    For quantum states of two subsystems, highly entangled states have a higher capacity of transmitting classical as well as quantum information, and vice versa. We show that this is no more the case in general: Quantum capacities of multiaccess channels, motivated by communication in quantum networks, do not have any relation with genuine multiparty entanglement measures. Importantly, the statement is demonstrated for arbitrary multipartite entanglement measures. Along with revealing the structural richness of multiaccess channels, this gives us a tool to classify multiparty quantum states from the perspective of its usefulness in quantum networks, which cannot be visualized by any genuine multiparty entanglement measure.

  5. Adaptive recurrence quantum entanglement distillation for two-Kraus-operator channels

    Science.gov (United States)

    Ruan, Liangzhong; Dai, Wenhan; Win, Moe Z.

    2018-05-01

    Quantum entanglement serves as a valuable resource for many important quantum operations. A pair of entangled qubits can be shared between two agents by first preparing a maximally entangled qubit pair at one agent, and then sending one of the qubits to the other agent through a quantum channel. In this process, the deterioration of entanglement is inevitable since the noise inherent in the channel contaminates the qubit. To address this challenge, various quantum entanglement distillation (QED) algorithms have been developed. Among them, recurrence algorithms have advantages in terms of implementability and robustness. However, the efficiency of recurrence QED algorithms has not been investigated thoroughly in the literature. This paper puts forth two recurrence QED algorithms that adapt to the quantum channel to tackle the efficiency issue. The proposed algorithms have guaranteed convergence for quantum channels with two Kraus operators, which include phase-damping and amplitude-damping channels. Analytical results show that the convergence speed of these algorithms is improved from linear to quadratic and one of the algorithms achieves the optimal speed. Numerical results confirm that the proposed algorithms significantly improve the efficiency of QED.

  6. Quantum Dialogue by Using Non-Symmetric Quantum Channel

    International Nuclear Information System (INIS)

    Zhan Youbang; Zhang Lingling; Zhang Qunyong; Wang Yuwu

    2010-01-01

    A protocol for quantum dialogue is proposed to exchange directly the communicator's secret messages by using a three-dimensional Bell state and a two-dimensional Bell state as quantum channel with quantum superdence coding, local collective unitary operations, and entanglement swapping. In this protocol, during the process of transmission of particles, the transmitted particles do not carry any secret messages and are transmitted only one time. The protocol has higher source capacity than protocols using symmetric two-dimensional states. The security is ensured by the unitary operations randomly performed on all checking groups before the particle sequence is transmitted and the application of entanglement swapping. (general)

  7. Probabilistic Teleportation of Arbitrary Two-Qubit Quantum State via Non-Symmetric Quantum Channel

    Directory of Open Access Journals (Sweden)

    Kan Wang

    2018-03-01

    Full Text Available Quantum teleportation has significant meaning in quantum information. In particular, entangled states can also be used for perfectly teleporting the quantum state with some probability. This is more practical and efficient in practice. In this paper, we propose schemes to use non-symmetric quantum channel combinations for probabilistic teleportation of an arbitrary two-qubit quantum state from sender to receiver. The non-symmetric quantum channel is composed of a two-qubit partially entangled state and a three-qubit partially entangled state, where partially entangled Greenberger–Horne–Zeilinger (GHZ state and W state are considered, respectively. All schemes are presented in detail and the unitary operations required are given in concise formulas. Methods are provided for reducing classical communication cost and combining operations to simplify the manipulation. Moreover, our schemes are flexible and applicable in different situations.

  8. Design of quaternary logic circuit using quantum dot gate-quantum dot channel FET (QDG-QDCFET)

    Science.gov (United States)

    Karmakar, Supriya

    2014-10-01

    This paper presents the implementation of quaternary logic circuits based on quantum dot gate-quantum dot channel field effect transistor (QDG-QDCFET). The super lattice structure in the quantum dot channel region of QDG-QDCFET and the electron tunnelling from inversion channel to the quantum dot layer in the gate region of a QDG-QDCFET change the threshold voltage of this device which produces two intermediate states between its ON and OFF states. This property of QDG-QDCFET is used to implement multi-valued logic for future multi-valued logic circuit. This paper presents the design of basic quaternary logic operation such as inverter, AND and OR operation based on QDG-QDCFET.

  9. Speeding up transmissions of unknown quantum information along Ising-type quantum channels

    International Nuclear Information System (INIS)

    Guo W J; Wei L F

    2017-01-01

    Quantum teleportation with entanglement channels and a series of two-qubit SWAP gates between the nearest-neighbor qubits are usually utilized to achieve the transfers of unknown quantum state from the sender to the distant receiver. In this paper, by simplifying the usual SWAP gates we propose an approach to speed up the transmissions of unknown quantum information, specifically including the single-qubit unknown state and two-qubit unknown entangled ones, by a series of entangling and disentangling operations between the remote qubits with distant interactions. The generic proposal is demonstrated specifically with experimentally-existing Ising-type quantum channels without transverse interaction; liquid NMR-molecules driven by global radio frequency electromagnetic pulses and capacitively-coupled Josephson circuits driven by local microwave pulses. The proposal should be particularly useful to set up the connections between the distant qubits in a chip of quantum computing. (paper)

  10. Quantum capacity of dephasing channels with memory

    International Nuclear Information System (INIS)

    D'Arrigo, A; Benenti, G; Falci, G

    2007-01-01

    We show that the amount of coherent quantum information that can be reliably transmitted down a dephasing channel with memory is maximized by separable input states. In particular, we model the channel as a Markov chain or a multimode environment of oscillators. While in the first model, the maximization is achieved for the maximally mixed input state, in the latter it is convenient to exploit the presence of a decoherence-protected subspace generated by memory effects. We explicitly compute the quantum channel capacity for the first model while numerical simulations suggest a lower bound for the latter. In both cases memory effects enhance the coherent information. We present results valid for arbitrary input size

  11. Quantum dot conjugates in a sub-micrometer fluidic channel

    Science.gov (United States)

    Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

    2010-04-13

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  12. Quantum dot conjugates in a sub-micrometer fluidic channel

    Science.gov (United States)

    Stavis, Samuel M [Ithaca, NY; Edel, Joshua B [Brookline, MA; Samiee, Kevan T [Ithaca, NY; Craighead, Harold G [Ithaca, NY

    2008-07-29

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  13. Faithful qubit transmission in a quantum communication network with heterogeneous channels

    Science.gov (United States)

    Chen, Na; Zhang, Lin Xi; Pei, Chang Xing

    2018-04-01

    Quantum communication networks enable long-distance qubit transmission and distributed quantum computation. In this paper, a quantum communication network with heterogeneous quantum channels is constructed. A faithful qubit transmission scheme is presented. Detailed calculations and performance analyses show that even in a low-quality quantum channel with serious decoherence, only modest number of locally prepared target qubits are required to achieve near-deterministic qubit transmission.

  14. Conclusive identification of quantum channels via monogamy of quantum correlations

    International Nuclear Information System (INIS)

    Kumar, Asutosh; Singha Roy, Sudipto; Pal, Amit Kumar; Prabhu, R.; Sen, Aditi; Sen, Ujjwal

    2016-01-01

    We investigate the action of global noise and local channels, namely, amplitude-damping, phase-damping, and depolarizing channels, on monogamy of quantum correlations, such as negativity and quantum discord, in three-qubit systems. We discuss the monotonic and non-monotonic variation, and robustness of the monogamy scores. By using monogamy scores, we propose a two-step protocol to conclusively identify the noise applied to the quantum system, by using generalized Greenberger–Horne–Zeilinger and generalized W states as resource states. We discuss a possible generalization of the results to higher number of parties. - Highlights: • Monogamy score monotonically decays with noise for generalized GHZ state as input. • Non-monotonically decaying monogamy score with noise for generalized W state as input. • Characterizing the dynamics of monogamy score. • Dynamics terminal quantifying robustness of monogamy score against noise. • Conclusively identifying the type of noise using monogamy score.

  15. Conclusive identification of quantum channels via monogamy of quantum correlations

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Asutosh; Singha Roy, Sudipto; Pal, Amit Kumar [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Prabhu, R. [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Department of Physics, Indian Institute of Technology Patna, Bihta 801103, Bihar (India); Sen, Aditi, E-mail: aditi@hri.res.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Sen, Ujjwal [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India)

    2016-10-23

    We investigate the action of global noise and local channels, namely, amplitude-damping, phase-damping, and depolarizing channels, on monogamy of quantum correlations, such as negativity and quantum discord, in three-qubit systems. We discuss the monotonic and non-monotonic variation, and robustness of the monogamy scores. By using monogamy scores, we propose a two-step protocol to conclusively identify the noise applied to the quantum system, by using generalized Greenberger–Horne–Zeilinger and generalized W states as resource states. We discuss a possible generalization of the results to higher number of parties. - Highlights: • Monogamy score monotonically decays with noise for generalized GHZ state as input. • Non-monotonically decaying monogamy score with noise for generalized W state as input. • Characterizing the dynamics of monogamy score. • Dynamics terminal quantifying robustness of monogamy score against noise. • Conclusively identifying the type of noise using monogamy score.

  16. Probabilistic Teleportation via Quantum Channel with Partial Information

    Directory of Open Access Journals (Sweden)

    Desheng Liu

    2015-06-01

    Full Text Available Two novel schemes are proposed to teleport an unknown two-level quantum state probabilistically when the sender and the receiver only have partial information about the quantum channel, respectively. This is distinct from the fact that either the sender or the receiver has entire information about the quantum channel in previous schemes for probabilistic teleportation. Theoretical analysis proves that these schemes are straightforward, efficient and cost-saving. The concrete realization procedures of our schemes are presented in detail, and the result shows that our proposals could extend the application range of probabilistic teleportation.

  17. Capacity estimation and verification of quantum channels with arbitrarily correlated errors.

    Science.gov (United States)

    Pfister, Corsin; Rol, M Adriaan; Mantri, Atul; Tomamichel, Marco; Wehner, Stephanie

    2018-01-02

    The central figure of merit for quantum memories and quantum communication devices is their capacity to store and transmit quantum information. Here, we present a protocol that estimates a lower bound on a channel's quantum capacity, even when there are arbitrarily correlated errors. One application of these protocols is to test the performance of quantum repeaters for transmitting quantum information. Our protocol is easy to implement and comes in two versions. The first estimates the one-shot quantum capacity by preparing and measuring in two different bases, where all involved qubits are used as test qubits. The second verifies on-the-fly that a channel's one-shot quantum capacity exceeds a minimal tolerated value while storing or communicating data. We discuss the performance using simple examples, such as the dephasing channel for which our method is asymptotically optimal. Finally, we apply our method to a superconducting qubit in experiment.

  18. Entanglement fidelity of the standard quantum teleportation channel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang; Ye, Ming-Yong, E-mail: myye@fjnu.edu.cn; Lin, Xiu-Min

    2013-09-16

    We consider the standard quantum teleportation protocol where a general bipartite state is used as entanglement resource. We use the entanglement fidelity to describe how well the standard quantum teleportation channel transmits quantum entanglement and give a simple expression for the entanglement fidelity when it is averaged on all input states.

  19. Assessing the performance of quantum repeaters for all phase-insensitive Gaussian bosonic channels

    International Nuclear Information System (INIS)

    Goodenough, K; Elkouss, D; Wehner, S

    2016-01-01

    One of the most sought-after goals in experimental quantum communication is the implementation of a quantum repeater. The performance of quantum repeaters can be assessed by comparing the attained rate with the quantum and private capacity of direct transmission, assisted by unlimited classical two-way communication. However, these quantities are hard to compute, motivating the search for upper bounds. Takeoka, Guha and Wilde found the squashed entanglement of a quantum channel to be an upper bound on both these capacities. In general it is still hard to find the exact value of the squashed entanglement of a quantum channel, but clever sub-optimal squashing channels allow one to upper bound this quantity, and thus also the corresponding capacities. Here, we exploit this idea to obtain bounds for any phase-insensitive Gaussian bosonic channel. This bound allows one to benchmark the implementation of quantum repeaters for a large class of channels used to model communication across fibers. In particular, our bound is applicable to the realistic scenario when there is a restriction on the mean photon number on the input. Furthermore, we show that the squashed entanglement of a channel is convex in the set of channels, and we use a connection between the squashed entanglement of a quantum channel and its entanglement assisted classical capacity. Building on this connection, we obtain the exact squashed entanglement and two-way assisted capacities of the d -dimensional erasure channel and bounds on the amplitude-damping channel and all qubit Pauli channels. In particular, our bound improves on the previous best known squashed entanglement upper bound of the depolarizing channel. (paper)

  20. Measurement-device-independent quantum digital signatures

    Science.gov (United States)

    Puthoor, Ittoop Vergheese; Amiri, Ryan; Wallden, Petros; Curty, Marcos; Andersson, Erika

    2016-08-01

    Digital signatures play an important role in software distribution, modern communication, and financial transactions, where it is important to detect forgery and tampering. Signatures are a cryptographic technique for validating the authenticity and integrity of messages, software, or digital documents. The security of currently used classical schemes relies on computational assumptions. Quantum digital signatures (QDS), on the other hand, provide information-theoretic security based on the laws of quantum physics. Recent work on QDS Amiri et al., Phys. Rev. A 93, 032325 (2016);, 10.1103/PhysRevA.93.032325 Yin, Fu, and Zeng-Bing, Phys. Rev. A 93, 032316 (2016), 10.1103/PhysRevA.93.032316 shows that such schemes do not require trusted quantum channels and are unconditionally secure against general coherent attacks. However, in practical QDS, just as in quantum key distribution (QKD), the detectors can be subjected to side-channel attacks, which can make the actual implementations insecure. Motivated by the idea of measurement-device-independent quantum key distribution (MDI-QKD), we present a measurement-device-independent QDS (MDI-QDS) scheme, which is secure against all detector side-channel attacks. Based on the rapid development of practical MDI-QKD, our MDI-QDS protocol could also be experimentally implemented, since it requires a similar experimental setup.

  1. Quantum systems, channels, information. A mathematical introduction

    Energy Technology Data Exchange (ETDEWEB)

    Holevo, Alexander S.

    2012-07-01

    The subject of this book is theory of quantum system presented from information science perspective. The central role is played by the concept of quantum channel and its entropic and information characteristics. Quantum information theory gives a key to understanding elusive phenomena of quantum world and provides a background for development of experimental techniques that enable measuring and manipulation of individual quantum systems. This is important for the new efficient applications such as quantum computing, communication and cryptography. Research in the field of quantum informatics, including quantum information theory, is in progress in leading scientific centers throughout the world. This book gives an accessible, albeit mathematically rigorous and self-contained introduction to quantum information theory, starting from primary structures and leading to fundamental results and to exiting open problems.

  2. Hidden Quantum Processes, Quantum Ion Channels, and 1/ f θ-Type Noise.

    Science.gov (United States)

    Paris, Alan; Vosoughi, Azadeh; Berman, Stephen A; Atia, George

    2018-03-22

    In this letter, we perform a complete and in-depth analysis of Lorentzian noises, such as those arising from [Formula: see text] and [Formula: see text] channel kinetics, in order to identify the source of [Formula: see text]-type noise in neurological membranes. We prove that the autocovariance of Lorentzian noise depends solely on the eigenvalues (time constants) of the kinetic matrix but that the Lorentzian weighting coefficients depend entirely on the eigenvectors of this matrix. We then show that there are rotations of the kinetic eigenvectors that send any initial weights to any target weights without altering the time constants. In particular, we show there are target weights for which the resulting Lorenztian noise has an approximately [Formula: see text]-type spectrum. We justify these kinetic rotations by introducing a quantum mechanical formulation of membrane stochastics, hidden quantum activated-measurement models, and prove that these quantum models are probabilistically indistinguishable from the classical hidden Markov models typically used for ion channel stochastics. The quantum dividend obtained by replacing classical with quantum membranes is that rotations of the Lorentzian weights become simple readjustments of the quantum state without any change to the laboratory-determined kinetic and conductance parameters. Moreover, the quantum formalism allows us to model the activation energy of a membrane, and we show that maximizing entropy under constrained activation energy yields the previous [Formula: see text]-type Lorentzian weights, in which the spectral exponent [Formula: see text] is a Lagrange multiplier for the energy constraint. Thus, we provide a plausible neurophysical mechanism by which channel and membrane kinetics can give rise to [Formula: see text]-type noise (something that has been occasionally denied in the literature), as well as a realistic and experimentally testable explanation for the numerical values of the spectral

  3. The Time Division Multi-Channel Communication Model and the Correlative Protocol Based on Quantum Time Division Multi-Channel Communication

    International Nuclear Information System (INIS)

    Liu Xiao-Hui; Pei Chang-Xing; Nie Min

    2010-01-01

    Based on the classical time division multi-channel communication theory, we present a scheme of quantum time-division multi-channel communication (QTDMC). Moreover, the model of quantum time division switch (QTDS) and correlative protocol of QTDMC are proposed. The quantum bit error rate (QBER) is analyzed and the QBER simulation test is performed. The scheme shows that the QTDS can carry out multi-user communication through quantum channel, the QBER can also reach the reliability requirement of communication, and the protocol of QTDMC has high practicability and transplantable. The scheme of QTDS may play an important role in the establishment of quantum communication in a large scale in the future. (general)

  4. Conditions for uniqueness of product representations for separable quantum channels and separable quantum states

    International Nuclear Information System (INIS)

    Cohen, Scott M.

    2014-01-01

    We give a sufficient condition that an operator sum representation of a separable quantum channel in terms of product operators is the unique product representation for that channel, and then provide examples of such channels for any number of parties. This result has implications for efforts to determine whether or not a given separable channel can be exactly implemented by local operations and classical communication. By the Choi-Jamiolkowski isomorphism, it also translates to a condition for the uniqueness of product state ensembles representing a given quantum state. These ideas follow from considerations concerning whether or not a subspace spanned by a given set of product operators contains at least one additional product operator

  5. Quantum-state transfer through long-range correlated disordered channels

    Science.gov (United States)

    Almeida, Guilherme M. A.; de Moura, Francisco A. B. F.; Lyra, Marcelo L.

    2018-05-01

    We study quantum-state transfer in XX spin-1/2 chains where both communicating spins are weakly coupled to a channel featuring disordered on-site magnetic fields. Fluctuations are modeled by long-range correlated sequences with self-similar profile obeying a power-law spectrum. We show that the channel is able to perform almost perfect quantum-state transmissions even in the presence of significant amounts of disorder provided the degree of those correlations is strong enough, with the cost of having long transfer times and unavoidable timing errors. Still, we show that the lack of mirror symmetry in the channel does not affect much the likelihood of having high-quality outcomes. Our results suggest that coexistence between localized and delocalized states can diminish effects of static perturbations in solid-state devices for quantum communication.

  6. Oscillatory magnetoconductance of quantum double-well channels

    International Nuclear Information System (INIS)

    Rojo, A.G.; Kumar, N.; Balseiro, C.A.

    1988-07-01

    The recently observed flux-periodic interference effect between parallel quantum double-well channels is theoretically studied in a discrete model that takes into account tunneling between channels. We obtain oscillatory magnetoconductance with small modulations which is attributable to the tunneling. Our treatment includes the effect of evanescent modes. (author). 7 refs, 2 figs

  7. Quantum entanglement enhances the capacity of bosonic channels with memory

    International Nuclear Information System (INIS)

    Cerf, Nicolas J.; Clavareau, Julien; Macchiavello, Chiara; Roland, Jeremie

    2005-01-01

    The bosonic quantum channels have recently attracted a growing interest, motivated by the hope that they open a tractable approach to the generally hard problem of evaluating quantum channel capacities. These studies, however, have always been restricted to memoryless channels. Here, it is shown that the classical capacity of a bosonic Gaussian channel with memory can be significantly enhanced if entangled symbols are used instead of product symbols. For example, the capacity of a photonic channel with 70%-correlated thermal noise of one-third the shot noise is enhanced by about 11% when using 3.8-dB entangled light with a modulation variance equal to the shot noise

  8. Robust Quantum Secure Direct Communication over Collective Rotating Channel

    International Nuclear Information System (INIS)

    Qin Sujuan; Gao Fei; Wen Qiaoyan; Zhu Fuchen

    2010-01-01

    A quantum secure direct communication protocol over a collective rotating channel is proposed. The protocol encodes logical bits in noiseless subspaces, and so it can function over a quantum channel subjected to an arbitrary degree of collective rotating noise. Although entangled states are used, both the sender and receiver are only required to perform single-particle product measurement or Pauli operations. The protocol is feasible with present-day technique. (general)

  9. Multimode Interference: Identifying Channels and Ridges in Quantum Probability Distributions

    OpenAIRE

    O'Connell, Ross C.; Loinaz, Will

    2004-01-01

    The multimode interference technique is a simple way to study the interference patterns found in many quantum probability distributions. We demonstrate that this analysis not only explains the existence of so-called "quantum carpets," but can explain the spatial distribution of channels and ridges in the carpets. With an understanding of the factors that govern these channels and ridges we have a limited ability to produce a particular pattern of channels and ridges by carefully choosing the ...

  10. Protecting Quantum Correlation from Correlated Amplitude Damping Channel

    Science.gov (United States)

    Huang, Zhiming; Zhang, Cai

    2017-08-01

    In this work, we investigate the dynamics of quantum correlation measured by measurement-induced nonlocality (MIN) and local quantum uncertainty (LQU) in correlated amplitude damping (CAD) channel. We find that the memory parameter brings different influences on MIN and LQU. In addition, we propose a scheme to protect quantum correlation by executing prior weak measurement (WM) and post-measurement reversal (MR). However, better protection of quantum correlation by the scheme implies a lower success probability (SP).

  11. Eavesdropping on the Bostroem-Filbinger Communication Protocol in Noisy Quantum Channel

    OpenAIRE

    Cai, Qing-yu

    2004-01-01

    We show an eavesdropping scheme on Bostr\\UNICODE{0xf6}m-Felbinger communication protocol (called ping-pong protocol) [Phys. Rev. Lett. 89, 187902 (2002)] in an ideal quantum channel. A measurement attack can be perfectly used to eavesdrop Alice's information instead of a most general quantum operation attack. In a noisy quantum channel, the direct communication is forbidden. We present a quantum key distribution protocol based on the ping-pong protocol, which can be used in a low noisy quantu...

  12. Quantum Fisher information of the Greenberg-Horne-Zeilinger state in decoherence channels

    International Nuclear Information System (INIS)

    Ma Jian; Huang Yixiao; Wang Xiaoguang; Sun, C. P.

    2011-01-01

    Quantum Fisher information of a parameter characterizes the sensitivity of the state with respect to changes of the parameter. In this article, we study the quantum Fisher information of a state with respect to SU(2) rotations under three decoherence channels: the amplitude-damping, phase-damping, and depolarizing channels. The initial state is chosen to be a Greenberg-Horne-Zeilinger state of which the phase sensitivity can achieve the Heisenberg limit. By using the Kraus operator representation, the quantum Fisher information is obtained analytically. We observe the decay and sudden change of the quantum Fisher information in all three channels.

  13. Quantum Fisher information of the Greenberg-Horne-Zeilinger state in decoherence channels

    Energy Technology Data Exchange (ETDEWEB)

    Ma Jian; Huang Yixiao; Wang Xiaoguang [Zhejiang Institute of Modern Physics, Department of Physics, Zhejiang University, Hangzhou 310027 (China); Sun, C. P. [Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-08-15

    Quantum Fisher information of a parameter characterizes the sensitivity of the state with respect to changes of the parameter. In this article, we study the quantum Fisher information of a state with respect to SU(2) rotations under three decoherence channels: the amplitude-damping, phase-damping, and depolarizing channels. The initial state is chosen to be a Greenberg-Horne-Zeilinger state of which the phase sensitivity can achieve the Heisenberg limit. By using the Kraus operator representation, the quantum Fisher information is obtained analytically. We observe the decay and sudden change of the quantum Fisher information in all three channels.

  14. Perfect controlled joint remote state preparation independent of entanglement degree of the quantum channel

    International Nuclear Information System (INIS)

    An, Nguyen Ba; Bich, Cao Thi

    2014-01-01

    We construct a quantum circuit to produce a task-oriented partially entangled state and use it as the quantum channel for controlled joint remote state preparation. Unlike most previous works, where the parameters of the quantum channel are given to the receiver who can accomplish the task only probabilistically by consuming auxiliary resource, operation and measurement, here we give them to the supervisor. Thanks to the knowledge of the task-oriented quantum channel parameters, the supervisor can carry out proper complete projective measurement, which, combined with the feed-forward technique adapted by the preparers, not only much economizes (simplifies) the receiver's resource (operation) but also yields unit total success probability. Notably, such apparent perfection does not depend on the entanglement degree of the shared quantum channel. Our protocol is within the reach of current quantum technologies. - Highlights: • Controlled joint remote state preparation is considered. • Quantum circuit is proposed to produce task-oriented partially entangled channel. • The quantum channel parameter is given to the supervisor (not to the receiver). • Unit success probability without additional resource/operations/measurement. • Perfection is achieved regardless of the shared entanglement degree

  15. Quantum teleportation and entanglement distribution over 100-kilometre free-space channels.

    Science.gov (United States)

    Yin, Juan; Ren, Ji-Gang; Lu, He; Cao, Yuan; Yong, Hai-Lin; Wu, Yu-Ping; Liu, Chang; Liao, Sheng-Kai; Zhou, Fei; Jiang, Yan; Cai, Xin-Dong; Xu, Ping; Pan, Ge-Sheng; Jia, Jian-Jun; Huang, Yong-Mei; Yin, Hao; Wang, Jian-Yu; Chen, Yu-Ao; Peng, Cheng-Zhi; Pan, Jian-Wei

    2012-08-09

    Transferring an unknown quantum state over arbitrary distances is essential for large-scale quantum communication and distributed quantum networks. It can be achieved with the help of long-distance quantum teleportation and entanglement distribution. The latter is also important for fundamental tests of the laws of quantum mechanics. Although quantum teleportation and entanglement distribution over moderate distances have been realized using optical fibre links, the huge photon loss and decoherence in fibres necessitate the use of quantum repeaters for larger distances. However, the practical realization of quantum repeaters remains experimentally challenging. Free-space channels, first used for quantum key distribution, offer a more promising approach because photon loss and decoherence are almost negligible in the atmosphere. Furthermore, by using satellites, ultra-long-distance quantum communication and tests of quantum foundations could be achieved on a global scale. Previous experiments have achieved free-space distribution of entangled photon pairs over distances of 600 metres (ref. 14) and 13 kilometres (ref. 15), and transfer of triggered single photons over a 144-kilometre one-link free-space channel. Most recently, following a modified scheme, free-space quantum teleportation over 16 kilometres was demonstrated with a single pair of entangled photons. Here we report quantum teleportation of independent qubits over a 97-kilometre one-link free-space channel with multi-photon entanglement. An average fidelity of 80.4 ± 0.9 per cent is achieved for six distinct states. Furthermore, we demonstrate entanglement distribution over a two-link channel, in which the entangled photons are separated by 101.8 kilometres. Violation of the Clauser-Horne-Shimony-Holt inequality is observed without the locality loophole. Besides being of fundamental interest, our results represent an important step towards a global quantum network. Moreover, the high

  16. Long quantum channels for high-quality entanglement transfer

    International Nuclear Information System (INIS)

    Banchi, L; Apollaro, T J G; Cuccoli, A; Verrucchi, P; Vaia, R

    2011-01-01

    High-quality quantum-state and entanglement transfer can be achieved in an unmodulated spin bus operating in the ballistic regime, which occurs when the endpoint qubits A and B are nonperturbatively coupled to the chain by a suitable exchange interaction j 0 . Indeed, the transition amplitude characterizing the transfer quality exhibits a maximum for a finite optimal value j opt 0 (N), where N is the channel length. We show that j opt 0 (N) scales as N -1/6 for large N and that it ensures a high-quality entanglement transfer even in the limit of arbitrarily long channels, almost independently of the channel initialization. For instance, for any chain length the average quantum-state transmission fidelity exceeds 90% and decreases very little in a broad neighbourhood of j opt 0 (N). We emphasize that, taking the reverse point of view, should j 0 be experimentally constrained, high-quality transfer can still be obtained by adjusting the channel length to its optimal value. (paper)

  17. Asymmetric information capacities of reciprocal pairs of quantum channels

    Science.gov (United States)

    Rosati, Matteo; Giovannetti, Vittorio

    2018-05-01

    Reciprocal pairs of quantum channels are defined as completely positive transformations which admit a rigid, distance-preserving, yet not completely positive transformation that allows one to reproduce the outcome of one from the corresponding outcome of the other. From a classical perspective these transmission lines should exhibit the same communication efficiency. This is no longer the case in the quantum setting: explicit asymmetric behaviors are reported studying the classical communication capacities of reciprocal pairs of depolarizing and Weyl-covariant channels.

  18. Probing the quantumness of channels with mixed states

    International Nuclear Information System (INIS)

    Haeseler, Hauke; Luetkenhaus, Norbert

    2009-01-01

    We present an alternative approach to the derivation of benchmarks for quantum channels, such as memory or teleportation channels. Using the concept of effective entanglement and the verification thereof, a testing procedure is derived which demands very few experimental resources. The procedure is generalized by allowing for mixed test states. By constructing optimized measure and reprepare channels, the benchmarks are found to be very tight in the considered experimental regimes.

  19. Quantum Stackelberg Duopoly Game in Depolarizing Channel

    International Nuclear Information System (INIS)

    Zhu Xia; Kuang Leman

    2008-01-01

    In this paper, we investigate the quantum Stackelberg duopoly (QSD) game in the noise environment with the depolarizing channel expressed by the Kraus-operator representation. It is found that the presence of the damping in the depolarizing channel always leads to the decrease of the quantities of the moves and payoffs of the two players in the QSD game. It is indicated that under certain conditions the first-mover advantage in the QSD game can be weakened due to the presence of the damping in the depolarizing channel.

  20. Quantum finite-depth memory channels: Case study

    International Nuclear Information System (INIS)

    Rybar, Tomas; Ziman, Mario

    2009-01-01

    We analyze the depth of the memory of quantum memory channels generated by a fixed unitary transformation describing the interaction between the principal system and internal degrees of freedom of the process device. We investigate the simplest case of a qubit memory channel with a two-level memory system. In particular, we explicitly characterize all interactions for which the memory depth is finite. We show that the memory effects are either infinite, or they disappear after at most two uses of the channel. Memory channels of finite depth can be to some extent controlled and manipulated by so-called reset sequences. We show that actions separated by the sequences of inputs of the length of the memory depth are independent and constitute memoryless channels.

  1. Teleportation is necessary for faithful quantum state transfer through noisy channels of maximal rank

    International Nuclear Information System (INIS)

    Romano, Raffaele; Loock, Peter van

    2010-01-01

    Quantum teleportation enables deterministic and faithful transmission of quantum states, provided a maximally entangled state is preshared between sender and receiver, and a one-way classical channel is available. Here, we prove that these resources are not only sufficient, but also necessary, for deterministically and faithfully sending quantum states through any fixed noisy channel of maximal rank, when a single use of the cannel is admitted. In other words, for this family of channels, there are no other protocols, based on different (and possibly cheaper) sets of resources, capable of replacing quantum teleportation.

  2. Gaussian Error Correction of Quantum States in a Correlated Noisy Channel

    DEFF Research Database (Denmark)

    Lassen, Mikael Østergaard; Berni, Adriano; Madsen, Lars Skovgaard

    2013-01-01

    Noise is the main obstacle for the realization of fault-tolerant quantum information processing and secure communication over long distances. In this work, we propose a communication protocol relying on simple linear optics that optimally protects quantum states from non-Markovian or correlated...... noise. We implement the protocol experimentally and demonstrate the near-ideal protection of coherent and entangled states in an extremely noisy channel. Since all real-life channels are exhibiting pronounced non-Markovian behavior, the proposed protocol will have immediate implications in improving...... the performance of various quantum information protocols....

  3. Effect of quantum noise on deterministic remote state preparation of an arbitrary two-particle state via various quantum entangled channels

    Science.gov (United States)

    Qu, Zhiguo; Wu, Shengyao; Wang, Mingming; Sun, Le; Wang, Xiaojun

    2017-12-01

    As one of important research branches of quantum communication, deterministic remote state preparation (DRSP) plays a significant role in quantum network. Quantum noises are prevalent in quantum communication, and it can seriously affect the safety and reliability of quantum communication system. In this paper, we study the effect of quantum noise on deterministic remote state preparation of an arbitrary two-particle state via different quantum channels including the χ state, Brown state and GHZ state. Firstly, the output states and fidelities of three DRSP algorithms via different quantum entangled channels in four noisy environments, including amplitude-damping, phase-damping, bit-flip and depolarizing noise, are presented, respectively. And then, the effects of noises on three kinds of preparation algorithms in the same noisy environment are discussed. In final, the theoretical analysis proves that the effect of noise in the process of quantum state preparation is only related to the noise type and the size of noise factor and independent of the different entangled quantum channels. Furthermore, another important conclusion is given that the effect of noise is also independent of how to distribute intermediate particles for implementing DRSP through quantum measurement during the concrete preparation process. These conclusions will be very helpful for improving the efficiency and safety of quantum communication in a noisy environment.

  4. Characterization of Unruh channel in the context of open quantum systems

    International Nuclear Information System (INIS)

    Banerjee, Subhashish; Alok, Ashutosh Kumar; Omkar, S.; Srikanth, R.

    2017-01-01

    In this work, we study an important facet of field theories in curved spacetime, viz. the Unruh effect, by making use of ideas of statistical mechanics and quantum foundations. Aspects of decoherence and dissipation, natural artifacts of open quantum systems, along with foundational issues such as the trade-off between coherence and mixing as well as various aspects of quantum correlations are investigated in detail for the Unruh effect. We show how the Unruh effect can be quantified mathematically by the Choi matrix approach. We study how environmentally induced decoherence modifies the effect of the Unruh channel. The differing effects of a dissipative or non-dissipative environment are noted. Further, useful parameters characterizing channel performance such as gate and channel fidelity are applied here to the Unruh channel, both with and without external influences. Squeezing, which is known to play an important role in the context of particle creation, is shown to be a useful resource in a number of scenarios.

  5. Teleportation with an Arbitrary Mixed Resource as a Trace-Preserving Quantum Channel

    Institute of Scientific and Technical Information of China (English)

    Sergio Albeverio; FEI Shao-Ming; YANG Wen-Li

    2002-01-01

    General conditions are given in order to perform a perfect teleportation process in the case where theHilbert spaces involved have different dimensions. An explicit expression is obtained for the quantum channel associatedwith the standard teleportation protocol To with an arbitrary mixed state resource. The transmission fidelity of thecorresponding quantum channel is given.

  6. Analysis of a convenient information bound for general quantum channels

    International Nuclear Information System (INIS)

    O'Loan, C J

    2007-01-01

    Open questions from Sarovar and Milburn (2006 J. Phys. A: Math. Gen. 39 8487) are answered. Sarovar and Milburn derived a convenient upper bound for the Fisher information of a one-parameter quantum channel. They showed that for quasi-classical models their bound is achievable and they gave a necessary and sufficient condition for positive operator-valued measures (POVMs) attaining this bound. They asked (i) whether their bound is attainable more generally (ii) whether explicit expressions for optimal POVMs can be derived from the attainability condition. We show that the symmetric logarithmic derivative (SLD) quantum information is less than or equal to the SM bound, i.e., H(θ) ≤ C Y (θ) and we find conditions for equality. As the Fisher information is less than or equal to the SLD quantum information, i.e., F M (θ) ≤ H(θ), we can deduce when equality holds in F M (θ) ≤ C Y (θ). Equality does not hold for all channels. As a consequence, the attainability condition cannot be used to test for optimal POVMs for all channels. These results are extended to multi-parameter channels

  7. Modeling satellite-Earth quantum channel downlinks with adaptive-optics coupling to single-mode fibers

    Science.gov (United States)

    Gruneisen, Mark T.; Flanagan, Michael B.; Sickmiller, Brett A.

    2017-12-01

    The efficient coupling of photons from a free-space quantum channel into a single-mode optical fiber (SMF) has important implications for quantum network concepts involving SMF interfaces to quantum detectors, atomic systems, integrated photonics, and direct coupling to a fiber network. Propagation through atmospheric turbulence, however, leads to wavefront errors that degrade mode matching with SMFs. In a free-space quantum channel, this leads to photon losses in proportion to the severity of the aberration. This is particularly problematic for satellite-Earth quantum channels, where atmospheric turbulence can lead to significant wavefront errors. This report considers propagation from low-Earth orbit to a terrestrial ground station and evaluates the efficiency with which photons couple either through a circular field stop or into an SMF situated in the focal plane of the optical receiver. The effects of atmospheric turbulence on the quantum channel are calculated numerically and quantified through the quantum bit error rate and secure key generation rates in a decoy-state BB84 protocol. Numerical simulations include the statistical nature of Kolmogorov turbulence, sky radiance, and an adaptive-optics system under closed-loop control.

  8. Postselection technique for quantum channels with applications to quantum cryptography.

    Science.gov (United States)

    Christandl, Matthias; König, Robert; Renner, Renato

    2009-01-16

    We propose a general method for studying properties of quantum channels acting on an n-partite system, whose action is invariant under permutations of the subsystems. Our main result is that, in order to prove that a certain property holds for an arbitrary input, it is sufficient to consider the case where the input is a particular de Finetti-type state, i.e., a state which consists of n identical and independent copies of an (unknown) state on a single subsystem. Our technique can be applied to the analysis of information-theoretic problems. For example, in quantum cryptography, we get a simple proof for the fact that security of a discrete-variable quantum key distribution protocol against collective attacks implies security of the protocol against the most general attacks. The resulting security bounds are tighter than previously known bounds obtained with help of the exponential de Finetti theorem.

  9. The coding theorem for a class of quantum channels with long-term memory

    International Nuclear Information System (INIS)

    Datta, Nilanjana; Dorlas, Tony C

    2007-01-01

    In this paper, we consider the transmission of classical information through a class of quantum channels with long-term memory, which are convex combinations of memoryless channels. Hence, the memory of such channels can be considered to be given by a Markov chain which is aperiodic but not irreducible. We prove the coding theorem and weak converse for this class of channels. The main techniques that we employ are a quantum version of Feinstein's fundamental lemma (Feinstein A 1954 IRE Trans. PGIT 4 2-22, Khinchin A I 1957 Mathematical Foundations of Information Theory: II. On the Fundamental Theorems of Information Theory (New York: Dover) chapter IV) and a generalization of Helstrom's theorem (Helstrom C W 1976 Quantum detection and estimation theory Mathematics in Science and Engineering vol 123 (London: Academic))

  10. Occam’s Quantum Strop: Synchronizing and Compressing Classical Cryptic Processes via a Quantum Channel

    Science.gov (United States)

    Mahoney, John R.; Aghamohammadi, Cina; Crutchfield, James P.

    2016-02-01

    A stochastic process’ statistical complexity stands out as a fundamental property: the minimum information required to synchronize one process generator to another. How much information is required, though, when synchronizing over a quantum channel? Recent work demonstrated that representing causal similarity as quantum state-indistinguishability provides a quantum advantage. We generalize this to synchronization and offer a sequence of constructions that exploit extended causal structures, finding substantial increase of the quantum advantage. We demonstrate that maximum compression is determined by the process’ cryptic order-a classical, topological property closely allied to Markov order, itself a measure of historical dependence. We introduce an efficient algorithm that computes the quantum advantage and close noting that the advantage comes at a cost-one trades off prediction for generation complexity.

  11. Quantum Channeling Effects for 1 MeV Positrons

    International Nuclear Information System (INIS)

    Haakenaasen, R.; Vestergaard Hau, L.; Golovchenko, J.A.; Palathingal, J.C.; Peng, J.P.; Asoka-Kumar, P.; Lynn, K.G.

    1995-01-01

    A high resolution angular study of positrons transmitted through a thin single crystal of Si clearly reveals a detailed fine structure due to strong quantum channeling effects. The beam transmitted in the forward direction displays many features associated with dynamical diffraction effects and long coherence lengths. Calculations are presented showing that in flight annihilation of channeled positrons can serve as a solid state probe of electron and spin densities in thin crystals

  12. Study on the security of discrete-variable quantum key distribution over non-Markovian channels

    International Nuclear Information System (INIS)

    Huang Peng; Zhu Jun; He Guangqiang; Zeng Guihua

    2012-01-01

    The dynamic of the secret key rate of the discrete-variable quantum key distribution (QKD) protocol over the non-Markovian quantum channel is investigated. In particular, we calculate the secret key rate for the six-state protocol over non-Markovian depolarizing channels with coloured noise and Markovian depolarizing channels with Gaussian white noise, respectively. We find that the secure secret key rate for the non-Markovian depolarizing channel will be larger than the Markovian one under the same conditions even when their upper bounds of tolerable quantum bit error rate are equal. This indicates that this coloured noise in the non-Markovian depolarizing channel can enhance the security of communication. Moreover, we show that the secret key rate fluctuates near the secure point when the coupling strength of the system with the environment is high. The results demonstrate that the non-Markovian effects of the transmission channel can have a positive impact on the security of discrete-variable QKD. (paper)

  13. Quantum correlation versus Bell-inequality violation under the amplitude damping channel

    Energy Technology Data Exchange (ETDEWEB)

    Ma, WenChao; Xu, Shuai; Shi, Jiadong; Ye, Liu, E-mail: yeliu@ahu.edu.cn

    2015-11-06

    We investigate the quantum correlations including quantum discord and entanglement under the amplitude damping channel. Our analysis results indicate that although the entanglement of initial state is degraded due to decoherence, the distribution trend of entanglement is not to be affected. Moreover, we find that the survival time for entanglement is much longer than for the Bell inequality violation, i.e., as time goes on the Bell inequality violation of final state may be not satisfied while the final state still remains entangled. Especially, although quantum entanglement and quantum discord all decrease under the amplitude damping channel, quantum discord (QD) is reduced significantly slower than entanglement. Therefore, the quantum discord is more robust against amplitude damping in comparison to entanglement measures. Furthermore, we also find that there are mixed states having quantum discord higher than that for pure states for a given degree of Bell's inequality violation. This means that the manipulation of nonclassical correlations via a pure state can result in a larger loss of quantum discord than that via a mixed state. - Highlights: • Entanglement distribution trend is not be affected by the decoherent. • The survival time for entanglement is much longer than for the Bell inequality violation. • The quantum discord is more robust against amplitude damping in comparison entanglement measures.

  14. Multiparty-controlled teleportation of an arbitrary m-qudit state with a pure entangled quantum channel

    International Nuclear Information System (INIS)

    Zhou, Ping; Li, Xi-Han; Deng, Fu-Guo; Zhou, Hong-Yu

    2007-01-01

    We present a general scheme for multiparty-controlled teleportation of an arbitrary m-qudit (d-dimensional quantum system) state by using non-maximally entangled states as the quantum channel. The sender performs m generalized Bell-state measurements on her 2m particles, the controllers take some single-particle measurements with the measuring basis X d and the receiver only needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if he cooperates with all the controllers. All the parties can use some decoy photons to set up their quantum channel securely, which will forbid a dishonest party to eavesdrop freely. This scheme is optimal as the probability that the receiver obtains the originally unknown m-qudit state equals the entanglement of the quantum channel

  15. Efficient Quantum Information Transfer Through a Uniform Channel

    Directory of Open Access Journals (Sweden)

    Paola Verrucchi

    2011-06-01

    Full Text Available Effective quantum-state and entanglement transfer can be obtained by inducing a coherent dynamics in quantum wires with homogeneous intrawire interactions. This goal is accomplished by optimally tuning the coupling between the wire endpoints and the two qubits there attached. A general procedure to determine such value is devised, and scaling laws between the optimal coupling and the length of the wire are found. The procedure is implemented in the case of a wire consisting of a spin-1/2 XY chain: results for the time dependence of the quantities which characterize quantum-state and entanglement transfer are found of extremely good quality also for very long wires. The present approach does not require engineered intrawire interactions nor a specific initial pulse shaping, and can be applied to a vast class of quantum channels.

  16. Position-based coding and convex splitting for private communication over quantum channels

    Science.gov (United States)

    Wilde, Mark M.

    2017-10-01

    The classical-input quantum-output (cq) wiretap channel is a communication model involving a classical sender X, a legitimate quantum receiver B, and a quantum eavesdropper E. The goal of a private communication protocol that uses such a channel is for the sender X to transmit a message in such a way that the legitimate receiver B can decode it reliably, while the eavesdropper E learns essentially nothing about which message was transmitted. The ɛ -one-shot private capacity of a cq wiretap channel is equal to the maximum number of bits that can be transmitted over the channel, such that the privacy error is no larger than ɛ \\in (0,1). The present paper provides a lower bound on the ɛ -one-shot private classical capacity, by exploiting the recently developed techniques of Anshu, Devabathini, Jain, and Warsi, called position-based coding and convex splitting. The lower bound is equal to a difference of the hypothesis testing mutual information between X and B and the "alternate" smooth max-information between X and E. The one-shot lower bound then leads to a non-trivial lower bound on the second-order coding rate for private classical communication over a memoryless cq wiretap channel.

  17. Fault-tolerant controlled quantum secure direct communication over a collective quantum noise channel

    International Nuclear Information System (INIS)

    Yang, Chun-Wei; Hwang, Tzonelih; Tsai, Chia-Wei

    2014-01-01

    This work proposes controlled quantum secure direct communication (CQSDC) over an ideal channel. Based on the proposed CQSDC, two fault-tolerant CQSDC protocols that are robust under two kinds of collective noises, collective-dephasing noise and collective-rotation noise, respectively, are constructed. Due to the use of quantum entanglement of the Bell state (or logical Bell state) as well as dense coding, the proposed protocols provide easier implementation as well as better qubit efficiency than other CQSDC protocols. Furthermore, the proposed protocols are also free from correlation-elicitation attack and other well-known attacks. (paper)

  18. Competition between abstraction and exchange channels in H + HCN reaction: Full-dimensional quantum dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Bin; Guo, Hua, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2013-12-14

    Dynamics of the title reaction is investigated on an ab initio based potential energy surface using a full-dimensional quantum wave packet method within the centrifugal sudden approximation. It is shown that the reaction between H and HCN leads to both the hydrogen exchange and hydrogen abstraction channels. The exchange channel has a lower threshold and larger cross section than the abstraction channel. It also has more oscillations due apparently to quantum resonances. Both channels are affected by long-lived resonances supported by potential wells. Comparison with experimental cross sections indicates underestimation of the abstraction barrier height.

  19. Fault-Tolerate Three-Party Quantum Secret Sharing over a Collective-Noise Channel

    International Nuclear Information System (INIS)

    Li Chun-Yan; Li Yan-Song

    2011-01-01

    We present a fault-tolerate three-party quantum secret sharing (QSS) scheme over a collective-noise channel. Decoherence-free subspaces are used to tolerate two noise modes, a collective-dephasing channel and a collective-rotating channel, respectively. In this scheme, the boss uses two physical qubits to construct a logical qubit which acts as a quantum channel to transmit one bit information to her two agents. The agents can get the information of the private key established by the boss only if they collaborate. The boss Alice encodes information with two unitary operations. Only single-photon measurements are required to rebuilt Alice's information and detect the security by the agents Bob and Charlie, not Bell-state measurements. Moreover, Almost all of the photons are used to distribute information, and its success efficiency approaches 100% in theory. (general)

  20. Entangled state teleportation through a couple of quantum channels composed of XXZ dimers in an Ising- XXZ diamond chain

    Science.gov (United States)

    Rojas, M.; de Souza, S. M.; Rojas, Onofre

    2017-02-01

    The quantum teleportation plays an important role in quantum information process, in this sense, the quantum entanglement properties involving an infinite chain structure is quite remarkable because real materials could be well represented by an infinite chain. We study the teleportation of an entangled state through a couple of quantum channels, composed by Heisenberg dimers in an infinite Ising-Heisenberg diamond chain, the couple of chains are considered sufficiently far away from each other to be ignored the any interaction between them. To teleporting a couple of qubits through the quantum channel, we need to find the average density operator for Heisenberg spin dimers, which will be used as quantum channels. Assuming the input state as a pure state, we can apply the concept of fidelity as a useful measurement of teleportation performance of a quantum channel. Using the standard teleportation protocol, we have derived an analytical expression for the output concurrence, fidelity, and average fidelity. We study in detail the effects of coupling parameters, external magnetic field and temperature dependence of quantum teleportation. Finally, we explore the relations between entanglement of the quantum channel, the output entanglement and the average fidelity of the system. Through a kind of phase diagram as a function of Ising-Heisenberg diamond chain model parameters, we illustrate where the quantum teleportation will succeed and a region where the quantum teleportation could fail.

  1. The Security Analysis of Two-Step Quantum Direct Communication Protocol in Collective-Rotation Noise Channel

    International Nuclear Information System (INIS)

    Li Jian; Sun Feng-Qi; Pan Ze-Shi; Nie Jin-Rui; Chen Yan-Hua; Yuan Kai-Guo

    2015-01-01

    To analyze the security of two-step quantum direct communication protocol (QDCP) by using Einstein–Podolsky–Rosen pair proposed by Deng et al. [Phys. Rev. A 68 (2003) 042317] in collective-rotation noise channel, an excellent model of noise analysis is proposed. In the security analysis, the method of the entropy theory is introduced, and is compared with QDCP, an error rate point Q 0 (M : (Q 0 , 1.0)) is given. In different noise levels, if Eve wants to obtain the same amount of information, the error rate Q is distinguishable. The larger the noise level ϵ is, the larger the error rate Q is. When the noise level ϵ is lower than 11%, the high error rate is 0.153 without eavesdropping. Lastly, the security of the proposed protocol is discussed. It turns out that the quantum channel will be safe when Q < 0.153. Similarly, if error rate Q > 0.153 = Q 0 , eavesdropping information I > 1, which means that there exist eavesdroppers in the quantum channel, and the quantum channel will not be safe anymore. (paper)

  2. Quantum Dot-Based Luminescent Oxygen Channeling Assay for Potential Application in Homogeneous Bioassays.

    Science.gov (United States)

    Zhuang, Si-Hui; Guo, Xin-Xin; Wu, Ying-Song; Chen, Zhen-Hua; Chen, Yao; Ren, Zhi-Qi; Liu, Tian-Cai

    2016-01-01

    The unique photoproperties of quantum dots are promising for potential application in bioassays. In the present study, quantum dots were applied to a luminescent oxygen channeling assay. The reaction system developed in this study was based on interaction of biotin with streptavidin. Carboxyl-modified polystyrene microspheres doped with quantum dots were biotinylated and used as acceptors. Photosensitizer-doped carboxyl-modified polystyrene microspheres were conjugated with streptavidin and used as donors. The results indicated that the singlet oxygen that was released from the donor beads diffused into the acceptor beads. The acceptor beads were then exited via thioxene, and were subsequently fluoresced. To avoid generating false positives, a high concentration (0.01 mg/mL) of quantum dots is required for application in homogeneous immunoassays. Compared to a conventional luminescent oxygen channeling assay, this quantum dots-based technique requires less time, and would be easier to automate and miniaturize because it requires no washing to remove excess labels.

  3. Quantum key distribution with several intercept-resend attacks via a depolarizing channel

    International Nuclear Information System (INIS)

    Dehmani, Mustapha; Errahmani, Mohamed; Ez-Zahraouy, Hamid; Benyoussef, Abdelilah

    2012-01-01

    The disturbance effect of a depolarizing channel on the security of the quantum key distribution of the four-state BB84 protocol, with multiple sequential intercept-resend attacks of many eavesdroppers, has been studied. The quantum bit error rate and the mutual information are computed for an arbitrary number N of eavesdroppers. It is found that the quantum error rate decreases with increasing the depolarizing parameter p characterizing the noise of the channel. For p tr of p below which the information is secure and otherwise the information is not secure. The value of p tr decreases with increasing the number of attacks. In contrast, for p ⩾ 0.165, the information is not secure independently of the number of eavesdroppers. Phase diagrams corresponding to the secure—unsecure information are also established. (paper)

  4. Applications of Classical and Quantum Mechanical Channeling in Condensed Matter Physics

    Science.gov (United States)

    Haakenaasen, Randi

    1995-01-01

    The first part of this work involves ion channeling measurements on the high temperature superconductor rm YBa_{2}Cu_{3}O _{7-delta}(YBCO). The experiments were motivated by several previous reports of anomalous behavior in the displacements of the Cu and O atoms in the vicinity of the critical temperature rm(T _{c}) in several high temperature superconductors. Our measurements were complimentary to previous experiments in that we used thin film YBCO (as opposed to bulk single crystals) and focused on a small region around rm T_{c}. We mapped out the channeling parameters chi _{min} and Psi_ {1/2} in a 30 K region around rm T_{c} in 1-2 K steps in thin film YBCO(001) on MgO. Neither of our measurements showed any discontinuities in chi _{min} or Psi_ {1/2} near the superconducting phase transition, and we therefore have no reason to expect anything but a smooth increase in atomic vibrations in this region. We conclude that any anomalous behavior in atomic displacements deduced from previous channeling experiments is not essential to superconductivity. In the second part of the work positrons were used to study quantum mechanical channeling effects. We clearly observed and quantitatively accounted for quantum interference effects, including Bragg diffraction, in the forward transmission of channeled MeV positrons through a single crystal. Experimental scans across the (100), (110), and (111) planes in Si showed excellent agreement with theoretical dynamical diffraction calculations, giving us confidence that we can accurately predict the spatial and momentum distributions of channeled positrons. New experiments are envisioned in which the channeling effect is combined with 2 quantum annihilation in flight measurements to determine valence electron and magnetic spin distributions in a crystal. Since the channeling effect focuses the positrons to the interstices of the crystal, the annihilation rate will reflect the valence electron density. Furthermore, the

  5. A Novel Approach to Achieve the Perfect Security through AVK over Insecure Communication Channel

    Science.gov (United States)

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

    2017-04-01

    To enhance the security level of the cryptosystem in shared encrypted data over the insecure channel; Automatic variable key (AVK) is a perfect mechanism as being experimented by many researchers. In AVK, after establishment of the secret key (through some IKE protocols, like IKEv2 or 2 PAKA or 3 PAKA, etc), the successive keys are generated that are variable in nature from session to session by using time variant key technique. In this work, it is shown that how AVK can provide higher security than fixed key from well-known plaintext attack (for example, brute force attack) and ciphertext only attack (for example, frequency attack etc) due to randomness of keys. In order to improve the level of randomness among the key set, a new method is proposed to generate keys where the randomness are achieved not only in terms of change in bits sequence but also flexible in size as well. Randomness of the key set is also compared with other related time variant key mechanisms to prove superiority.

  6. Approximate method for treating dispersion in one-way quantum channels

    International Nuclear Information System (INIS)

    Stace, T. M.; Wiseman, H. M.

    2006-01-01

    Coupling the output of a source quantum system into a target quantum system is easily treated by cascaded systems theory if the intervening quantum channel is dispersionless. However, dispersion may be important in some transfer protocols, especially in solid-state systems. In this paper we show how to generalize cascaded systems theory to treat such dispersion, provided it is not too strong. We show that the technique also works for fermionic systems with a low flux, and can be extended to treat fermionic systems with large flux. To test our theory, we calculate the effect of dispersion on the fidelity of a simple protocol of quantum state transfer. We find good agreement with an approximate analytical theory that had been previously developed for this example

  7. Quantum deterministic key distribution protocols based on the authenticated entanglement channel

    International Nuclear Information System (INIS)

    Zhou Nanrun; Wang Lijun; Ding Jie; Gong Lihua

    2010-01-01

    Based on the quantum entanglement channel, two secure quantum deterministic key distribution (QDKD) protocols are proposed. Unlike quantum random key distribution (QRKD) protocols, the proposed QDKD protocols can distribute the deterministic key securely, which is of significant importance in the field of key management. The security of the proposed QDKD protocols is analyzed in detail using information theory. It is shown that the proposed QDKD protocols can safely and effectively hand over the deterministic key to the specific receiver and their physical implementation is feasible with current technology.

  8. Quantum deterministic key distribution protocols based on the authenticated entanglement channel

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Nanrun; Wang Lijun; Ding Jie; Gong Lihua [Department of Electronic Information Engineering, Nanchang University, Nanchang 330031 (China)], E-mail: znr21@163.com, E-mail: znr21@hotmail.com

    2010-04-15

    Based on the quantum entanglement channel, two secure quantum deterministic key distribution (QDKD) protocols are proposed. Unlike quantum random key distribution (QRKD) protocols, the proposed QDKD protocols can distribute the deterministic key securely, which is of significant importance in the field of key management. The security of the proposed QDKD protocols is analyzed in detail using information theory. It is shown that the proposed QDKD protocols can safely and effectively hand over the deterministic key to the specific receiver and their physical implementation is feasible with current technology.

  9. Constructions of secure entanglement channels assisted by quantum dots inside single-sided optical cavities

    Science.gov (United States)

    Heo, Jino; Kang, Min-Sung; Hong, Chang-Ho; Choi, Seong-Gon; Hong, Jong-Phil

    2017-08-01

    We propose quantum information processing schemes to generate and swap entangled states based on the interactions between flying photons and quantum dots (QDs) confined within optical cavities for quantum communication. To produce and distribute entangled states (Bell and Greenberger-Horne-Zeilinger [GHZ] states) between the photonic qubits of flying photons of consumers (Alice and Bob) and electron-spin qubits of a provider (trust center, or TC), the TC employs the interactions of the QD-cavity system, which is composed of a charged QD (negatively charged exciton) inside a single-sided cavity. Subsequently, the TC constructs an entanglement channel (Bell state and 4-qubit GHZ state) to link one consumer with another through entanglement swapping, which can be realized to exploit a probe photon with interactions of the QD-cavity systems and single-qubit measurements without Bell state measurement, for quantum communication between consumers. Consequently, the TC, which has quantum nodes (QD-cavity systems), can accomplish constructing the entanglement channel (authenticated channel) between two separated consumers from the distributions of entangled states and entanglement swapping. Furthermore, our schemes using QD-cavity systems, which are feasible with a certain probability of success and high fidelity, can be experimentally implemented with technology currently in use.

  10. Relevance of quantum mechanics on some aspects of ion channel function

    OpenAIRE

    Roy, Sisir; Llinás, Rodolfo

    2009-01-01

    Mathematical modeling of ionic diffusion along K ion channels indicates that such diffusion is oscillatory, at the weak non-Markovian limit. This finding leads us to derive a Schrödinger–Langevin equation for this kind of system within the framework of stochastic quantization. The Planck’s constant is shown to be relevant to the Lagrangian action at the level of a single ion channel. This sheds new light on the issue of applicability of quantum formalism to ion channel dynamics and to the phy...

  11. Non-Bell-pair quantum channel for teleporting an arbitrary two-qubit state

    International Nuclear Information System (INIS)

    Zha Xinwei; Song Haiyang

    2007-01-01

    Recently, Yeo and Chua [Y. Yeo, W.K. Chua, Phys. Rev. Lett. 96 (2006) 060502] gave a protocol for faithfully teleporting an arbitrary two-qubit state via a genuine four-qubit entangled state, which is not reducible to a pair of Bell state. Here, we present a 'transformation operator' to give a criterion for faithful teleportation of an arbitrary two-qubit state via a four-qubit entangled state. The theoretical explanations of some quantum channels are given in term of transformation operators. The relation between the transformation operators and the Bell base measurement is also obtained. Furthermore, a new four-qubit entangled state quantum channel is presented

  12. Gaussian capacity of the quantum bosonic memory channel with additive correlated Gaussian noise

    International Nuclear Information System (INIS)

    Schaefer, Joachim; Karpov, Evgueni; Cerf, Nicolas J.

    2011-01-01

    We present an algorithm for calculation of the Gaussian classical capacity of a quantum bosonic memory channel with additive Gaussian noise. The algorithm, restricted to Gaussian input states, is applicable to all channels with noise correlations obeying certain conditions and works in the full input energy domain, beyond previous treatments of this problem. As an illustration, we study the optimal input states and capacity of a quantum memory channel with Gauss-Markov noise [J. Schaefer, Phys. Rev. A 80, 062313 (2009)]. We evaluate the enhancement of the transmission rate when using these optimal entangled input states by comparison with a product coherent-state encoding and find out that such a simple coherent-state encoding achieves not less than 90% of the capacity.

  13. Entanglement-enhanced communication over a quantum channel with correlated noise

    International Nuclear Information System (INIS)

    Banaszek, K.; Dragan, A.; Wasilewski, W.; Radzewicz, C.

    2005-01-01

    We present an experimental demonstration of entanglement enhanced classical capacity of a quantum channel with correlated noise. The channel is modelled by a fiber optic link exhibiting random birefringence that fluctuates on a time scale much longer than the temporal separation between consecutive uses of the channel. In this setting, it can be shown theoretically that introducing entanglement between two photons travelling down the fiber allows one to encode reliably one bit of information into their polarization degree of freedom. When no quantum correlations between two separate uses of the channel are allowed, this capacity is reduced by a factor of more than three. To demonstrate experimentally this effect, we generated polarization-entangled pairs of photons in either a singlet or a triplet state, corresponding to the two values of a classical bit. The pairs were then launched into a single-mode fiber submitted to random mechanical movements, scrambling the polarization state of the travelling light. At the output of the fiber, the photon pairs were detected using the Braunstein-Mann Bell state analyzer that allowed us to discriminate unambiguously the input singlet state against the triplet one despite polarization scrambling. To contrast this with the separable case, we also generated disentangled photon pairs and encoded information into their relative polarization. As predicted theoretically, after scrambling only partial information about the input state was retrieved. (author)

  14. Opportunistic quantum network coding based on quantum teleportation

    Science.gov (United States)

    Shang, Tao; Du, Gang; Liu, Jian-wei

    2016-04-01

    It seems impossible to endow opportunistic characteristic to quantum network on the basis that quantum channel cannot be overheard without disturbance. In this paper, we propose an opportunistic quantum network coding scheme by taking full advantage of channel characteristic of quantum teleportation. Concretely, it utilizes quantum channel for secure transmission of quantum states and can detect eavesdroppers by means of quantum channel verification. What is more, it utilizes classical channel for both opportunistic listening to neighbor states and opportunistic coding by broadcasting measurement outcome. Analysis results show that our scheme can reduce the times of transmissions over classical channels for relay nodes and can effectively defend against classical passive attack and quantum active attack.

  15. Aggregating quantum repeaters for the quantum internet

    Science.gov (United States)

    Azuma, Koji; Kato, Go

    2017-09-01

    The quantum internet holds promise for accomplishing quantum teleportation and unconditionally secure communication freely between arbitrary clients all over the globe, as well as the simulation of quantum many-body systems. For such a quantum internet protocol, a general fundamental upper bound on the obtainable entanglement or secret key has been derived [K. Azuma, A. Mizutani, and H.-K. Lo, Nat. Commun. 7, 13523 (2016), 10.1038/ncomms13523]. Here we consider its converse problem. In particular, we present a universal protocol constructible from any given quantum network, which is based on running quantum repeater schemes in parallel over the network. For arbitrary lossy optical channel networks, our protocol has no scaling gap with the upper bound, even based on existing quantum repeater schemes. In an asymptotic limit, our protocol works as an optimal entanglement or secret-key distribution over any quantum network composed of practical channels such as erasure channels, dephasing channels, bosonic quantum amplifier channels, and lossy optical channels.

  16. Quantum Bit Commitment and the Reality of the Quantum State

    Science.gov (United States)

    Srikanth, R.

    2018-01-01

    Quantum bit commitment is insecure in the standard non-relativistic quantum cryptographic framework, essentially because Alice can exploit quantum steering to defer making her commitment. Two assumptions in this framework are that: (a) Alice knows the ensembles of evidence E corresponding to either commitment; and (b) system E is quantum rather than classical. Here, we show how relaxing assumption (a) or (b) can render her malicious steering operation indeterminable or inexistent, respectively. Finally, we present a secure protocol that relaxes both assumptions in a quantum teleportation setting. Without appeal to an ontological framework, we argue that the protocol's security entails the reality of the quantum state, provided retrocausality is excluded.

  17. Reducing Employment Insecurity

    Directory of Open Access Journals (Sweden)

    Florence Lebert

    2016-10-01

    Full Text Available The perception of job insecurity is known to be a stressful condition for employees. Less is known about employment insecurity and the ways employees and their families deal with it. This study investigates whether participation in further training is a strategy that employees adopt to reduce perceived employment insecurity. As participation in further training is often costly and time-consuming, we assume that the family context is of importance for the decision to take part in further training. To take account of possible self-selection, we apply a propensity score matching procedure on longitudinal data from the Swiss Household Panel (2004-2013. Three main findings can be emphasized: first, participation in further training is not a strategy adopted particularly by employees who perceive high employment insecurity as they are less likely to train than their secure counterparts. Second, even though further training is not a strategy that is actively adopted, employees who train subsequently report lower levels of perceived employment insecurity. Third, the family context indeed influences the likelihood to train: partnered employees are more likely to train and preschool-aged children act as a constraint on women’s but enhance men’s participation in further training. Yet, in the context of high perceived employment insecurity, children generally reduce their parents’ likelihood to train as the parents may turn to other strategies that reduce perceived employment insecurity.

  18. A decoupling approach to classical data transmission over quantum channels

    DEFF Research Database (Denmark)

    Dupont-Dupuis, Fréderic; Szehr, Oleg; Tomamichel, Marco

    2014-01-01

    be solved this way, one of the most basic coding problems remains impervious to a direct application of this method, sending classical information through a quantum channel. We will show that this problem can, in fact, be solved using decoupling ideas, specifically by proving a dequantizing theorem, which...

  19. Quantum channels irreducibly covariant with respect to the finite group generated by the Weyl operators

    Science.gov (United States)

    Siudzińska, Katarzyna; Chruściński, Dariusz

    2018-03-01

    In matrix algebras, we introduce a class of linear maps that are irreducibly covariant with respect to the finite group generated by the Weyl operators. In particular, we analyze the irreducibly covariant quantum channels, that is, the completely positive and trace-preserving linear maps. Interestingly, imposing additional symmetries leads to the so-called generalized Pauli channels, which were recently considered in the context of the non-Markovian quantum evolution. Finally, we provide examples of irreducibly covariant positive but not necessarily completely positive maps.

  20. Efficient quantum entanglement distribution over an arbitrary collective-noise channel

    Science.gov (United States)

    Sheng, Yu-Bo; Deng, Fu-Guo

    2010-04-01

    We present an efficient quantum entanglement distribution over an arbitrary collective-noise channel. The basic idea in the present scheme is that two parties in quantum communication first transmit the entangled states in the frequency degree of freedom which suffers little from the noise in an optical fiber. After the two parties share the photon pairs, they add some operations and equipments to transfer the frequency entanglement of pairs into the polarization entanglement with the success probability of 100%. Finally, they can get maximally entangled polarization states with polarization independent wavelength division multiplexers and quantum frequency up-conversion which can erase distinguishability for frequency. Compared with conventional entanglement purification protocols, the present scheme works in a deterministic way in principle. Surprisingly, the collective noise leads to an additional advantage.

  1. Information-theoretic treatment of tripartite systems and quantum channels

    International Nuclear Information System (INIS)

    Coles, Patrick J.; Yu Li; Gheorghiu, Vlad; Griffiths, Robert B.

    2011-01-01

    A Holevo measure is used to discuss how much information about a given positive operator valued measure (POVM) on system a is present in another system b, and how this influences the presence or absence of information about a different POVM on a in a third system c. The main goal is to extend information theorems for mutually unbiased bases or general bases to arbitrary POVMs, and especially to generalize ''all-or-nothing'' theorems about information located in tripartite systems to the case of partial information, in the form of quantitative inequalities. Some of the inequalities can be viewed as entropic uncertainty relations that apply in the presence of quantum side information, as in recent work by Berta et al. [Nature Physics 6, 659 (2010)]. All of the results also apply to quantum channels: For example, if E accurately transmits certain POVMs, the complementary channel F will necessarily be noisy for certain other POVMs. While the inequalities are valid for mixed states of tripartite systems, restricting to pure states leads to the basis invariance of the difference between the information about a contained in b and c.

  2. High-dimensional quantum channel estimation using classical light

    CSIR Research Space (South Africa)

    Mabena, Chemist M

    2017-11-01

    Full Text Available stream_source_info Mabena_20007_2017.pdf.txt stream_content_type text/plain stream_size 960 Content-Encoding UTF-8 stream_name Mabena_20007_2017.pdf.txt Content-Type text/plain; charset=UTF-8 PHYSICAL REVIEW A 96, 053860... (2017) High-dimensional quantum channel estimation using classical light Chemist M. Mabena CSIR National Laser Centre, P.O. Box 395, Pretoria 0001, South Africa and School of Physics, University of the Witwatersrand, Johannesburg 2000, South...

  3. Food insecurity: A concept analysis

    Science.gov (United States)

    Schroeder, Krista; Smaldone, Arlene

    2015-01-01

    Aim To report an analysis of the concept of food insecurity, in order to 1) propose a theoretical model of food insecurity useful to nursing and 2) discuss its implications for nursing practice, nursing research, and health promotion. Background Forty eight million Americans are food insecure. As food insecurity is associated with multiple negative health effects, nursing intervention is warranted. Design Concept Analysis Data sources A literature search was conducted in May 2014 in Scopus and MEDLINE using the exploded term “food insecur*.” No year limit was placed. Government websites and popular media were searched to ensure a full understanding of the concept. Review Methods Iterative analysis, using the Walker and Avant method Results Food insecurity is defined by uncertain ability or inability to procure food, inability to procure enough food, being unable to live a healthy life, and feeling unsatisfied. A proposed theoretical model of food insecurity, adapted from the Socio-Ecological Model, identifies three layers of food insecurity (individual, community, society), with potential for nursing impact at each level. Conclusion Nurses must work to fight food insecurity. There exists a potential for nursing impact that is currently unrealized. Nursing impact can be guided by a new conceptual model, Food Insecurity within the Nursing Paradigm. PMID:25612146

  4. Limitation on the amount of accessible information in a quantum channel

    International Nuclear Information System (INIS)

    Schumacher, B.; Westmoreland, M.; Wootters, W.K.

    1996-01-01

    We prove a new result limiting the amount of accessible information in a quantum channel. This generalizes Kholevo close-quote s theorem and implies it as a simple corollary. Our proof uses the strong subadditivity of the von Neumann entropy functional S(ρ) and a specific physical analysis of the measurement process. The result presented here has application in information obtained from open-quote open-quote weak close-quote close-quote measurements, such as those sometimes considered in quantum cryptography. copyright 1996 The American Physical Society

  5. Nonadditivity of quantum and classical capacities for entanglement breaking multiple-access channels and the butterfly network

    International Nuclear Information System (INIS)

    Grudka, Andrzej; Horodecki, Pawel

    2010-01-01

    We analyze quantum network primitives which are entanglement breaking. We show superadditivity of quantum and classical capacity regions for quantum multiple-access channels and the quantum butterfly network. Since the effects are especially visible at high noise they suggest that quantum information effects may be particularly helpful in the case of the networks with occasional high noise rates. The present effects provide a qualitative borderline between superadditivities of bipartite and multipartite systems.

  6. Water insecurity in a syndemic context: Understanding the psycho-emotional stress of water insecurity in Lesotho, Africa.

    Science.gov (United States)

    Workman, Cassandra L; Ureksoy, Heather

    2017-04-01

    Syndemics occur when populations experience synergistic and multiplicative effects of co-occurring epidemics. Proponents of syndemic theory highlight the importance of understanding the social context in which diseases spread and cogently argue that there are biocultural effects of external stresses such as food insecurity and water insecurity. Thus, a holistic understanding of disease or social vulnerability must incorporate an examination of the emotional and social effects of these phenomena. This paper is a response to the call for a renewed focus on measuring the psycho-emotional and psychosocial effects of food insecurity and water insecurity. Using a mixed-method approach of qualitative interviews and quantitative assessment, including a household demographic, illness, and water insecurity scale, the Household Food Insecurity Access Scale, and the Hopkins Symptoms Checklist-25, this research explored the psycho-emotional effects of water insecurity, food insecurity, and household illness on women and men residing in three low-land districts in Lesotho (n = 75). Conducted between February and November of 2011, this exploratory study first examined the complicated interaction of water insecurity, food insecurity and illness to understand and quantify the relationship between these co-occurring stresses in the context of HIV/AIDS. Second, it sought to separate the role of water insecurity in predicting psycho-emotional stress from other factors, such as food insecurity and household illness. When asked directly about water, qualitative research revealed water availability, access, usage amount, and perceived water cleanliness as important dimensions of water insecurity, creating stress in respondents' daily lives. Qualitative and quantitative data show that water insecurity, food insecurity and changing household demographics, likely resulting from the HIV/AIDS epidemic, are all associated with increased anxiety and depression, and support the conclusion that

  7. Continuous-variable quantum teleportation of even and odd coherent states through varied gain channels

    Institute of Scientific and Technical Information of China (English)

    Li Ying; Zhang Jing; Zhang Jun-Xiang; Zhang Tian-Cai

    2006-01-01

    This paper has investigated quantum teleportation of even and odd coherent states in terms of the EPR entanglement states for continuous variables. It discusses the relationship between the fidelity and the entanglement of EPR states, which is characterized by the degree of squeezing and the gain of classical channels. It shows that the quality of teleporting quantum states also depends on the characteristics of the states themselves. The properties of teleporting even and odd coherent states at different intensities are investigated. The difference of teleporting two such kinds of quantum states are analysed based on the quantum distance function.

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

    International Nuclear Information System (INIS)

    Chau, H.F.

    2002-01-01

    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

  9. Channel-coupling theory of covalent bonding in H2: A further application of arrangement-channel quantum mechanics

    International Nuclear Information System (INIS)

    Levin, F.S.; Krueger, H.

    1977-01-01

    The dissociation energy D/sub e/ and the equilibrium proton-proton separation R/sub eq/ of H 2 are calculated using the methods of arrangement-channel quantum mechanics. This theory is the channel component version of the channel-coupling array approach to many-body scattering, applied to bound-state problems. In the approximation used herein, the wave function is identical to that of the classic Heitler-London-Sugiura valence-bond calculation, which gave D/sub e/ = 3.14 eV and R/sub eq/ = 1.65a 0 , values accurate to 34% and 17.8%, respectively. The present method yields D/sub e/ = 4.437 eV and R/sub eq/ approx. = 1.42a 0 , accurate to 6.5% and 1%, respectively. Some implications of these results are discussed

  10. Signatures of a Nonthermal Metastable State in Copropagating Quantum Hall Edge Channels

    Science.gov (United States)

    Itoh, Kosuke; Nakazawa, Ryo; Ota, Tomoaki; Hashisaka, Masayuki; Muraki, Koji; Fujisawa, Toshimasa

    2018-05-01

    A Tomonaga-Luttinger (TL) liquid is known as an integrable system, in which a nonequilibrium many-body state survives without relaxing to a thermalized state. This intriguing characteristic is tested experimentally in copropagating quantum Hall edge channels at bulk filling factor ν =2 . The unidirectional transport allows us to investigate the time evolution by measuring the spatial evolution of the electronic states. The initial state is prepared with a biased quantum point contact, and its spatial evolution is measured with a quantum-dot energy spectrometer. We find strong evidence for a nonthermal metastable state in agreement with the TL theory before the system relaxes to thermal equilibrium with coupling to the environment.

  11. Optical transmission modules for multi-channel superconducting quantum interference device readouts

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin-Mok, E-mail: jmkim@kriss.re.kr; Kwon, Hyukchan; Yu, Kwon-kyu; Lee, Yong-Ho; Kim, Kiwoong [Brain Cognition Measurement Center, Korea Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of)

    2013-12-15

    We developed an optical transmission module consisting of 16-channel analog-to-digital converter (ADC), digital-noise filter, and one-line serial transmitter, which transferred Superconducting Quantum Interference Device (SQUID) readout data to a computer by a single optical cable. A 16-channel ADC sent out SQUID readouts data with 32-bit serial data of 8-bit channel and 24-bit voltage data at a sample rate of 1.5 kSample/s. A digital-noise filter suppressed digital noises generated by digital clocks to obtain SQUID modulation as large as possible. One-line serial transmitter reformed 32-bit serial data to the modulated data that contained data and clock, and sent them through a single optical cable. When the optical transmission modules were applied to 152-channel SQUID magnetoencephalography system, this system maintained a field noise level of 3 fT/√Hz @ 100 Hz.

  12. Food insecurity and eating disorder pathology.

    Science.gov (United States)

    Becker, Carolyn Black; Middlemass, Keesha; Taylor, Brigitte; Johnson, Clara; Gomez, Francesca

    2017-09-01

    The primary aim of this study was to investigate eating disorder (ED) pathology in those living with food insecurity. A secondary aim was to investigate whether any-reason dietary restraint, weight self-stigma, and worry increased as level of food insecurity increased. Participants (N = 503) seeking food from food pantries completed questionnaires assessing level of food insecurity, demographics, ED pathology, dietary restraint, weight self-stigma, and worry. Consistent with hypotheses, participants with the highest level of food insecurity (i.e., adults who reported having hungry children in their household) also endorsed significantly higher levels of binge eating, overall ED pathology, any-reason dietary restraint, weight self-stigma, and worry compared to participants with lower levels of food insecurity. Contrary to hypotheses, compensatory behaviors also increased as level of food insecurity worsened. Overall, 17% of those in the child hunger food insecurity group reported clinically significant ED pathology. This is the first study to assess the full spectrum of ED pathology in a low-income, marginalized population with food insecurity. Given that food insecurity is a global concern, results from this study suggest that greater attention to the association between ED pathology and food insecurity is warranted by researchers around the world. © 2017 Wiley Periodicals, Inc.

  13. Food insecurity, hunger, and undernutrition

    Science.gov (United States)

    Food insecurity, hunger, and undernutrition are viewed as a continuum, with food insecurity resulting in hunger and ultimately, if sufficiently severe and/or of sufficient duration, in undernutrition. Food insecurity indicates inadequate access to food for whatever reason, hunger is the immediate ph...

  14. Shot Noise Suppression in a Quantum Point Contact with Short Channel Length

    International Nuclear Information System (INIS)

    Jeong, Heejun

    2015-01-01

    An experimental study on the current shot noise of a quantum point contact with short channel length is reported. The experimentally measured maximum energy level spacing between the ground and the first excited state of the device reached up to 7.5 meV, probably due to the hard wall confinement by using shallow electron gas and sharp point contact geometry. The two-dimensional non-equilibrium shot noise contour map shows noise suppression characteristics in a wide range of bias voltage. Fano factor analysis indicates spin-polarized transport through a short quantum point contact. (paper)

  15. Eavesdropping on the "Ping-Pong" Quantum Communication Protocol Freely in a Noise Channel

    OpenAIRE

    Deng, Fu-Guo; Li, Xi-Han; Li, Chun-Yan; Zhou, Ping; Zhou, Hong-Yu

    2005-01-01

    We introduce an attack scheme for eavesdropping the ping-pong quantum communication protocol proposed by Bostr$\\ddot{o}$m and Felbinger [Phys. Rev. Lett. \\textbf{89}, 187902 (2002)] freely in a noise channel. The vicious eavesdropper, Eve, intercepts and measures the travel photon transmitted between the sender and the receiver. Then she replaces the quantum signal with a multi-photon signal in a same state, and measures the photons return with the measuring basis with which Eve prepares the ...

  16. Quantum capacity of quantum black holes

    Science.gov (United States)

    Adami, Chris; Bradler, Kamil

    2014-03-01

    The fate of quantum entanglement interacting with a black hole has been an enduring mystery, not the least because standard curved space field theory does not address the interaction of black holes with matter. We discuss an effective Hamiltonian of matter interacting with a black hole that has a precise analogue in quantum optics and correctly reproduces both spontaneous and stimulated Hawking radiation with grey-body factors. We calculate the quantum capacity of this channel in the limit of perfect absorption, as well as in the limit of a perfectly reflecting black hole (a white hole). We find that the white hole is an optimal quantum cloner, and is isomorphic to the Unruh channel with positive quantum capacity. The complementary channel (across the horizon) is entanglement-breaking with zero capacity, avoiding a violation of the quantum no-cloning theorem. The black hole channel on the contrary has vanishing capacity, while its complement has positive capacity instead. Thus, quantum states can be reconstructed faithfully behind the black hole horizon, but not outside. This work sheds new light on black hole complementarity because it shows that black holes can both reflect and absorb quantum states without violating the no-cloning theorem, and makes quantum firewalls obsolete.

  17. Many-body physics and the capacity of quantum channels with memory

    International Nuclear Information System (INIS)

    Plenio, M B; Virmani, S

    2008-01-01

    In most studies of the capacity of quantum channels, it is assumed that the errors in the use of each channel are independent. However, recent work has begun to investigate the effects of memory or correlations in the error, and has led to suggestions that there can be interesting non-analytic behaviour in the capacity of such channels. In a previous paper, we pursued this issue by connecting the study of channel capacities under correlated error to the study of critical behaviour in many-body physics. This connection enables the use of techniques from many-body physics to either completely solve or understand qualitatively a number of interesting models of correlated error with analogous behaviour to associated many-body systems. However, in order for this approach to work rigorously, there are a number of technical properties that need to be established for the lattice systems being considered. In this paper, we discuss these properties in detail, and establish them for some classes of many-body system

  18. Recent findings concerning childhood food insecurity.

    Science.gov (United States)

    Kursmark, Meredith; Weitzman, Michael

    2009-05-01

    Food insecurity is a relatively new measure of household and child malnutrition. This paper reviews recent studies that have examined aspects of its etiology and adverse child health and development. Smoking by adults in children's homes has recently been found to be highly associated with childhood food insecurity. Much recent research has also examined the relationship between food insecurity and childhood obesity, and thus far, whereas suggestive, results are conflicting. Some studies have found that parenting practices and parental depression are factors that link household food insecurity with childhood obesity. Other health outcomes recently shown to be associated with food insecurity include undernutrition, decreased mental proficiency, increased developmental risk, adverse pregnancy outcomes, and poor health status. Most of the studies of food insecurity to date have come from the USA. There is, however, absolutely no reason to believe that this measure, and the negative child health outcomes associated with it, does not apply to other developed nations. Similarly, it is likely that children and families living in developing countries suffer a greater prevalence and severity of food insecurity and its negative consequences. Childhood food insecurity has numerous significant negative effects on childhood health and development, may be associated with obesity, and occurs much more often in impoverished homes with adult smokers.

  19. A Mathematica package for calculation of planar channeling radiation spectra of relativistic electrons channeled in a diamond-structure single crystal (quantum approach)

    Science.gov (United States)

    Azadegan, B.

    2013-03-01

    The presented Mathematica code is an efficient tool for simulation of planar channeling radiation spectra of relativistic electrons channeled along major crystallographic planes of a diamond-structure single crystal. The program is based on the quantum theory of channeling radiation which has been successfully applied to study planar channeling at electron energies between 10 and 100 MeV. Continuum potentials for different planes of diamond, silicon and germanium single crystals are calculated using the Doyle-Turner approximation to the atomic scattering factor and taking thermal vibrations of the crystal atoms into account. Numerical methods are applied to solve the one-dimensional Schrödinger equation. The code is designed to calculate the electron wave functions, transverse electron states in the planar continuum potential, transition energies, line widths of channeling radiation and depth dependencies of the population of quantum states. Finally the spectral distribution of spontaneously emitted channeling radiation is obtained. The simulation of radiation spectra considerably facilitates the interpretation of experimental data. Catalog identifier: AEOH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 446 No. of bytes in distributed program, including test data, etc.: 209805 Distribution format: tar.gz Programming language: Mathematica. Computer: Platforms on which Mathematica is available. Operating system: Operating systems on which Mathematica is available. RAM: 1 MB Classification: 7.10. Nature of problem: Planar channeling radiation is emitted by relativistic charged particles during traversing a single crystal in direction parallel to a crystallographic plane. Channeling is modeled as the motion

  20. Insecure attachment and college-age alcohol use disorders. A case report.

    Science.gov (United States)

    Kotov, Kimberly M

    2006-01-01

    Teens and young adults with insecure attachment may be remarkably susceptible to alcohol and substance use disorders. Particularly in the separation process of leaving-home and entering college, an underlying insecure attachment may manifest through symptoms of alcohol or drug abuse; as these young adults engage in what is perceived to be adult drinking behavior, they become too "attached" to the alcohol as a substitute for earlier, sporadically-available objects (usually parents). That is, they enact a similar relationship to this drug that they may have learned to have with an insecure parent: too close at times, but ultimately fostering guilt, dependence and destructive action. Fear of abandonment, rejection and negative judgment may be intensified in this age group as they struggle at the cusp of independence, but these issues are particularly relevant for insecurely attached teens. In this report, attachment theory is briefly described and applied to the assessment and treatment of a college freshman diagnosed with an alcohol use disorder. By engaging the patient in evaluating her actions and motives through the attachment model, the therapy helps her to channel help-seeking behavior appropriately, to establish expectations for consistency and reliability from significant people in her life and to feel safer without turning to alcohol as a crutch. An argument is made for the general application of attachment theory to alcohol and drug use disorders in this significant phase of young adult development.

  1. Subjective employment insecurity around the world

    OpenAIRE

    Francis Green

    2009-01-01

    I consider the concept of employment insecurity and provide new evidence for 1997 and 2005 for many countries with widely differing institutional contexts and at varying stages of development. There are no grounds for accepting that workplaces were going through a sea-change in employment insecurity. Workers in transitional economies and developing economies worried the most about insecurity. Perceived insecurity tended to be greater for women, for less-educated and for older workers. However...

  2. Unconstrained Capacities of Quantum Key Distribution and Entanglement Distillation for Pure-Loss Bosonic Broadcast Channels.

    Science.gov (United States)

    Takeoka, Masahiro; Seshadreesan, Kaushik P; Wilde, Mark M

    2017-10-13

    We consider quantum key distribution (QKD) and entanglement distribution using a single-sender multiple-receiver pure-loss bosonic broadcast channel. We determine the unconstrained capacity region for the distillation of bipartite entanglement and secret key between the sender and each receiver, whenever they are allowed arbitrary public classical communication. A practical implication of our result is that the capacity region demonstrated drastically improves upon rates achievable using a naive time-sharing strategy, which has been employed in previously demonstrated network QKD systems. We show a simple example of a broadcast QKD protocol overcoming the limit of the point-to-point strategy. Our result is thus an important step toward opening a new framework of network channel-based quantum communication technology.

  3. Unconstrained Capacities of Quantum Key Distribution and Entanglement Distillation for Pure-Loss Bosonic Broadcast Channels

    Science.gov (United States)

    Takeoka, Masahiro; Seshadreesan, Kaushik P.; Wilde, Mark M.

    2017-10-01

    We consider quantum key distribution (QKD) and entanglement distribution using a single-sender multiple-receiver pure-loss bosonic broadcast channel. We determine the unconstrained capacity region for the distillation of bipartite entanglement and secret key between the sender and each receiver, whenever they are allowed arbitrary public classical communication. A practical implication of our result is that the capacity region demonstrated drastically improves upon rates achievable using a naive time-sharing strategy, which has been employed in previously demonstrated network QKD systems. We show a simple example of a broadcast QKD protocol overcoming the limit of the point-to-point strategy. Our result is thus an important step toward opening a new framework of network channel-based quantum communication technology.

  4. Two-channel spin-chain communication line and simple quantum gates

    Science.gov (United States)

    Stolze, J.; Zenchuk, A. I.

    2017-08-01

    We consider the remote creation of a mixed state in a one-qubit receiver connected to two two-qubit senders via different channels. Channels are assumed to be chains of spins (qubits) with nearest-neighbor interactions, no external fields are being applied. The problem of sharing the creatable region of the receiver's state-space between two senders is considered for a communication line with the receiver located asymmetrically with respect to these senders (asymmetric communication line). An example of a quantum register realizing simple functions is constructed on the basis of a symmetric communication line. In that setup, the initial states of the two senders serve as input and control signals, respectively, while the state of the receiver at a proper time instant is considered as the output signal.

  5. Household food insecurity and child health.

    Science.gov (United States)

    Schmeer, Kammi K; Piperata, Barbara A

    2017-04-01

    Food insecurity, the lack of consistent access to sufficient quality and quantity of food, affects an estimated 800 million people around the world. Although household food insecurity is generally associated with poor child nutrition and health in the USA, we know less about household food insecurity and child health in developing countries. Particularly lacking is research assessing how associations between household food insecurity and children's health outcomes may differ by child age and among children beyond age 5 years in low-income settings. We use data from a population-based sample of households with children ages 3-11 years (N = 431) in León, Nicaragua to consider how household food insecurity is associated with three measures of child health: illness, anaemia and low height-for-age. Our results provide new evidence that even mild household food insecurity is detrimental to children's health; and that child age conditions the associations between household food insecurity and child health. We find that food insecurity is especially harmful to health during early childhood, but continues to have significant associations with health into middle childhood (up to ages 7-8 years). We discuss the potential implications of these results for future child health research and policies in low-income countries. © 2016 John Wiley & Sons Ltd. © 2016 John Wiley & Sons Ltd.

  6. Food insecurity and migraine in Canada.

    Science.gov (United States)

    Dooley, Joseph M; Gordon, Kevin E; Kuhle, Stefan

    2016-09-01

    The aim of this study was to examine the prevalence of household food insecurity in individuals reporting migraine within a large population-based sample of Canadians. The Canadian Community Health Survey (CCHS) uses a stratified cluster sample design to obtain information on Canadians ≥12 years of age. Data on household food insecurity were assessed for individuals who reported having migraine or not, providing a current point prevalence. This was assessed for stability in two CCHS datasets from four and eight years earlier. Factors associated with food insecurity among those reporting migraine were examined and a logistic regression model of food insecurity was developed. We also examined whether food insecurity was associated with other reported chronic health conditions. Of 48,645 eligible survey respondents, 4614 reported having migraine (weighted point prevalence 10.2%). Food insecurity was reported by 14.8% who reported migraine compared with 6.8% of those not reporting migraine, giving an odds ratio of 2.4 (95% confidence interval 2.0-2.8%). This risk estimate was stable over the previous eight years. The higher risk for food insecurity was not unique to migraine and was seen with some, but not all, chronic health conditions reported in the CCHS. Food insecurity is more frequent among individuals reporting migraine in Canada. © International Headache Society 2015.

  7. McDonaldization and Job Insecurity

    OpenAIRE

    Emeka W. Dumbili

    2013-01-01

    The article examines how and why the McDonaldization of banking system in Nigeria engenders job insecurity. This is imperative because it provides an explicit revelation of the root causes of job insecurity in the sector that other scholars have totally omitted. No Nigerian scholar has applied the thesis in relation to job insecurity, which is the major problem in Nigeria’s banking industry. The article based on the an...

  8. Security, insecurity and health.

    Science.gov (United States)

    Coupland, Robin

    2007-03-01

    An examination of the nexus of security, insecurity and health shows that security is a prerequisite for health. The many and varied ways that armed violence--including threats of armed violence--can affect people's health can be documented by formal studies; however, valuable data also exist in other reports, such as media reports. The health community needs to recognize that people's insecurity is a massive global health issue. The foreign policies of donor governments should incorporate recognition that documentation, analysis and publication of data describing the impact of insecurity on people's health can lead to the creation of policies to enhance people's security.

  9. Quantum tagging: Authenticating location via quantum information and relativistic signaling constraints

    Energy Technology Data Exchange (ETDEWEB)

    Kent, Adrian; Munro, William J.; Spiller, Timothy P. [Centre for Quantum Information and Foundations, DAMTP, University of Cambridge, Cambridge, United Kingdom and Perimeter Institute for Theoretical Physics, Waterloo, Ontario (Canada); NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan); Quantum Information Science, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2011-07-15

    We define the task of quantum tagging, that is, authenticating the classical location of a classical tagging device by sending and receiving quantum signals from suitably located distant sites, in an environment controlled by an adversary whose quantum information processing and transmitting power is unbounded. We define simple security models for this task and briefly discuss alternatives. We illustrate the pitfalls of naive quantum cryptographic reasoning in this context by describing several protocols which at first sight appear unconditionally secure but which, as we show, can in fact be broken by teleportation-based attacks. We also describe some protocols which cannot be broken by these specific attacks, but do not prove they are unconditionally secure. We review the history of quantum tagging protocols, and show that protocols previously proposed by Malaney and Chandran et al. are provably insecure.

  10. Health effects of job insecurity

    OpenAIRE

    Green, F.

    2015-01-01

    Research has shown that job insecurity affects both mental and physical health, though the effects are lower when employees are easily re-employable. The detrimental effects of job insecurity can also be partly mitigated by employers allowing greater employee participation in workplace decision-making in order to ensure fair procedures. But as job insecurity is felt by many more people than just the unemployed, the negative health effects during recessions are multiplied and extend through th...

  11. Continuous-variable quantum key distribution in uniform fast-fading channels

    Science.gov (United States)

    Papanastasiou, Panagiotis; Weedbrook, Christian; Pirandola, Stefano

    2018-03-01

    We investigate the performance of several continuous-variable quantum key distribution protocols in the presence of uniform fading channels. These are lossy channels whose transmissivity changes according to a uniform probability distribution. We assume the worst-case scenario where an eavesdropper induces a fast-fading process, where she chooses the instantaneous transmissivity while the remote parties may only detect the mean statistical effect. We analyze coherent-state protocols in various configurations, including the one-way switching protocol in reverse reconciliation, the measurement-device-independent protocol in the symmetric configuration, and its extension to a three-party network. We show that, regardless of the advantage given to the eavesdropper (control of the fading), these protocols can still achieve high rates under realistic attacks, within reasonable values for the variance of the probability distribution associated with the fading process.

  12. Gender Disparities in the Food Insecurity-Overweight and Food Insecurity-Obesity Paradox among Low-Income Older Adults.

    Science.gov (United States)

    Hernandez, Daphne C; Reesor, Layton; Murillo, Rosenda

    2017-07-01

    Obesity and obesity-related comorbidities are increasing among older adults. Food insecurity is a nutrition-related factor that coexists with obesity among low-income individuals. The majority of the research on the food insecurity-obesity paradox has been conducted on low-income mothers and children, with research lacking on large diverse samples of older adults. The purpose of this study was to assess gender disparities in the association between food insecurity and overweight and obesity among low-income older adults. Cross-sectional 2011 and 2012 National Health Interview Survey data were used. Food insecurity status was determined by ≥3 affirmative responses on the 10-item US Department of Agriculture Food Security Scale (FSS). Body mass index (BMI) was calculated as outlined by the Centers for Disease Control and Prevention based on self-reported height and weight. Adults included were low-income (≤1.99 federal poverty level [FPL]), older (aged ≥60 years), with a normal BMI (18.5) or greater who had complete data on FSS, BMI, and the following covariates: age, race or ethnicity, marital status, income, nativity status, physical activity, poor health status, health insurance coverage, problems paying medical bills or for medicine, and region of residency (N=5,506). Multivariate logistic regression models were stratified by gender to estimate the association between food insecurity and higher weight status. All models included covariates. In covariate-adjusted models, compared with low-income, food secure men, low-income, food-insecure men had 42% and 41% lower odds of being overweight and overweight or obese, respectively. Despite the high prevalence rate of obesity among low-income, food-insecure women, food insecurity was not significantly related to overweight, obesity, or overweight or obesity for older adult women in adjusted models. Food insecurity-overweight and -obesity paradox appears not to be present in older men. However, food insecurity and

  13. Job insecurity and health.

    Science.gov (United States)

    McDonough, P

    2000-01-01

    As employers respond to new competitive pressures of global capitalism through layoffs and the casualization of labor, job insecurity affects a growing number of workers. It appears to harm mental health, but less is known about its effects on physical health and health behaviors and the mechanisms through which it may act. The prevailing individual-centered conceptualization of job insecurity as the perception of a threat to job continuity precludes systematic investigation of the social patterning of its health effects. Analysis of data from a 1994 Canadian national probability sample of adults determined that high levels of job insecurity lowered self-rated health and increased distress and the use of medications, but had no impact on heavy drinking. The findings support one possible mechanism of action whereby job insecurity reduces feelings of control over one's environment and opportunities for positive self-evaluation; these psychological experiences, in turn, have deleterious health consequences. There is little evidence of social patterning of this relationship by gender, education, household income, age, marital status, and social support at work.

  14. Cryptanalysis of an Improved Flexible Ping-Pong Protocol in Perfect and Imperfect Quantum Channels

    International Nuclear Information System (INIS)

    Bin-Bin, Zhang; Da-Qing, Wang; Shan-Shan, Huang; Yu, Liu

    2009-01-01

    We recently proposed a flexible quantum secure direct communication protocol [Chin. Phys. Lett. 23 (2006) 3152]. By analyzing its security in the perfect channel from the aspect of quantum information theory, we find that an eavesdropper is capable of stealing all the information without being detected. Two typical attacks are presented to illustrate this point. A solution to this loophole is also suggested and we show its powerfulness against the most general individual attack in the ideal case. We also discuss the security in the imperfect case when there is noise and loss

  15. Security bound of continuous-variable quantum key distribution with noisy coherent states and channel

    International Nuclear Information System (INIS)

    Shen Yong; Yang Jian; Guo Hong

    2009-01-01

    Security of a continuous-variable quantum key distribution protocol based on noisy coherent states and channel is analysed. Assuming that the noise of coherent states is induced by Fred, a neutral party relative to others, we prove that the prepare-and-measurement scheme (P and M) and entanglement-based scheme (E-B) are equivalent. Then, we show that this protocol is secure against Gaussian collective attacks even if the channel is lossy and noisy, and, further, a lower bound to the secure key rate is derived.

  16. Security bound of continuous-variable quantum key distribution with noisy coherent states and channel

    Energy Technology Data Exchange (ETDEWEB)

    Shen Yong; Yang Jian; Guo Hong, E-mail: hongguo@pku.edu.c [CREAM Group, State Key Laboratory of Advanced Optical Communication Systems and Networks (Peking University) and Institute of Quantum Electronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)

    2009-12-14

    Security of a continuous-variable quantum key distribution protocol based on noisy coherent states and channel is analysed. Assuming that the noise of coherent states is induced by Fred, a neutral party relative to others, we prove that the prepare-and-measurement scheme (P and M) and entanglement-based scheme (E-B) are equivalent. Then, we show that this protocol is secure against Gaussian collective attacks even if the channel is lossy and noisy, and, further, a lower bound to the secure key rate is derived.

  17. Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Gumbs, Godfrey [Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Abranyos, Yonatan [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Pepper, Michael; Kumar, Sanjeev [Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE (United Kingdom); London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom)

    2015-11-15

    For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.

  18. Security of quantum key distribution with a laser reference coherent state, resistant to loss in the communication channel

    International Nuclear Information System (INIS)

    Molotkov, S N; Potapova, T A

    2015-01-01

    The problem of quantum key distribution security in channels with large losses is still open. Quasi-single-photon sources of quantum states with losses in the quantum communication channel open up the possibility of attacking with unambiguous state discrimination (USD) measurements, resulting in a loss of privacy. In this letter, the problem is solved by counting the classic reference pulses. Conservation of the number of counts of intense coherent pulses makes it impossible to conduct USD measurements. Moreover, the losses in the communication channel are considered to be unknown in advance and are subject to change throughout the series parcels. Unlike other protocols, differential phase shift (Inoue et al 2002 Phys. Rev. Lett. 89 037902, Inoue et al 2003 Phys. Rev. A 68 022317, Takesue et al 2007 Nat. Photon. 1 343, Wen et al 2009 Phys. Rev. Lett. 103 170503) and coherent one way (Stucki et al 2005 Appl. Phys. Lett. 87 194108, Branciard et al 2005 Appl. Phys. Lett. 87 194108, Branciard et al 2008 New J. Phys. 10 013031, Stucki et al 2008 Opt. Express 17 13326), the simplicity of the protocol makes it possible to carry out a complete analysis of its security. (letter)

  19. Food insecurity in Denmark

    DEFF Research Database (Denmark)

    Lund, Thomas Bøker; Holm, Lotte; Tetens, Inge

    2018-01-01

    .001) and higher risk of psychological distress (women: adj.RR 2.42 P Obesity was more prevalent in low/very low food secure women (RR 2.44 P Food insecurity in Denmark is associated with adverse factors...... such as unhealthy diet, obesity, life satisfaction, and psychological distress. It is important to widen food insecurity research to non-liberal welfare states since low/very low food security is negatively associated with unhealthy eating and other health indicators, even in a social-democratic welfare state.......Background: Food insecurity and its consequences have not received much attention in the Nordic, social-democratic welfare states. This study reports the prevalence of low and very low food security in Denmark, identifies its socio-demographic determinants and examines its associations with eating...

  20. Suppression of the four-wave-mixing background noise in a quantum memory retrieval process by channel blocking

    Science.gov (United States)

    Zhang, Kai; Guo, Jinxian; Chen, L. Q.; Yuan, Chunhua; Ou, Z. Y.; Zhang, Weiping

    2014-09-01

    In a quantum memory scheme with the Raman process, the read process encounters noise from four-wave mixing (FWM), which can destroy the nonclassical properties of the generated quantum fields. Here we demonstrate experimentally that the noise from FWM can be greatly suppressed by simply reducing the FWM transition channels with a circularly polarized read beam while at the same time retaining relatively high retrieval efficiency.

  1. Homelessness and Housing Insecurity Among Former Prisoners

    Directory of Open Access Journals (Sweden)

    Claire W. Herbert

    2015-11-01

    Full Text Available The United States has experienced dramatic increases in both incarceration rates and the population of insecurely housed or homeless persons since the 1980s. These marginalized populations have strong overlaps, with many people being poor, minority, and from an urban area. That a relationship between homelessness, housing insecurity, and incarceration exists is clear, but the extent and nature of this relationship is not yet adequately understood. We use longitudinal, administrative data on Michigan parolees released in 2003 to examine returning prisoners’ experiences with housing insecurity and homelessness. Our analysis finds relatively low rates of outright homelessness among former prisoners, but very high rates of housing insecurity, much of which is linked to features of community supervision, such as intermediate sanctions, returns to prison, and absconding. We identify risk factors for housing insecurity, including mental illness, substance use, prior incarceration, and homelessness, as well as protective “buffers” against insecurity and homelessness, including earnings and social supports.

  2. Characterization of Eag1 channel lateral mobility in rat hippocampal cultures by single-particle-tracking with quantum dots.

    Directory of Open Access Journals (Sweden)

    David Gómez-Varela

    2010-01-01

    Full Text Available Voltage-gated ion channels are main players involved in fast synaptic events. However, only slow intracellular mechanisms have so far been described for controlling their localization as real-time visualization of endogenous voltage-gated channels at high temporal and spatial resolution has not been achieved yet. Using a specific extracellular antibody and quantum dots we reveal and characterize lateral mobility as a faster mechanism to dynamically control the number of endogenous ether-a-go-go (Eag1 ion channels inside synapses. We visualize Eag1 entering and leaving synapses by lateral diffusion in the plasma membrane of rat hippocampal neurons. Mathematical analysis of their trajectories revealed how the motion of Eag1 gets restricted when the channels diffuse into the synapse, suggesting molecular interactions between Eag1 and synaptic components. In contrast, Eag1 channels switch to Brownian movement when they exit synapses and diffuse into extrasynaptic membranes. Furthermore, we demonstrate that the mobility of Eag1 channels is specifically regulated inside synapses by actin filaments, microtubules and electrical activity. In summary, using single-particle-tracking techniques with quantum dots nanocrystals, our study shows for the first time the lateral diffusion of an endogenous voltage-gated ion channel in neurons. The location-dependent constraints imposed by cytoskeletal elements together with the regulatory role of electrical activity strongly suggest a pivotal role for the mobility of voltage-gated ion channels in synaptic activity.

  3. Probabilistic teleportation of an arbitrary GHZ-class state with a pure entangled two-particle quantum channel and its application in quantum state sharing

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents a scheme for probabilistic teleportation of an arbitrary GHZ-class state with a pure entangled two-particle quantum channel. The sender Alice first teleports the coefficients of the unknown state to the receiver Bob, and then Bob reconstructs the state with an auxiliary particle and some unitary operations if the teleportation succeeds. This scheme has the advantage of transmitting much less particles for teleporting an arbitrary GHZ-class state than others. Moreover, it discusses the application of this scheme in quantum state sharing.

  4. Eigenvalue and Entropy Statistics for Products of Conjugate Random Quantum Channels

    Directory of Open Access Journals (Sweden)

    Benoît Collins

    2010-06-01

    Full Text Available Using the graphical calculus and integration techniques introduced by the authors, we study the statistical properties of outputs of products of random quantum channels for entangled inputs. In particular, we revisit and generalize models of relevance for the recent counterexamples to the minimum output entropy additivity problems. Our main result is a classification of regimes for which the von Neumann entropy is lower on average than the elementary bounds that can be obtained with linear algebra techniques.

  5. On superactivation of one-shot quantum zero-error capacity and the related property of quantum measurements

    DEFF Research Database (Denmark)

    Shirokov, M. E.; Shulman, Tatiana

    2014-01-01

    We give a detailed description of a low-dimensional quantum channel (input dimension 4, Choi rank 3) demonstrating the symmetric form of superactivation of one-shot quantum zero-error capacity. This property means appearance of a noiseless (perfectly reversible) subchannel in the tensor square...... of a channel having no noiseless subchannels. Then we describe a quantum channel with an arbitrary given level of symmetric superactivation (including the infinite value). We also show that superactivation of one-shot quantum zero-error capacity of a channel can be reformulated in terms of quantum measurement...

  6. McDonaldization and Job Insecurity

    Directory of Open Access Journals (Sweden)

    Emeka W. Dumbili

    2013-06-01

    Full Text Available The article examines how and why the McDonaldization of banking system in Nigeria engenders job insecurity. This is imperative because it provides an explicit revelation of the root causes of job insecurity in the sector that other scholars have totally omitted. No Nigerian scholar has applied the thesis in relation to job insecurity, which is the major problem in Nigeria’s banking industry. The article based on the analysis of secondary data and observations, therefore, draws on McDonaldization thesis to examine the upsurge of rationalization in the sector since consolidation exercise began in 2005. The article argues that the sector’s rising rationalization and ensuing efficiency, calculability, predictability, and control are necessary. However, these have inevitably engendered job insecurity and its adverse consequences. Based on the critical analyses of available evidence, the article concludes that the best option is to commence resistance of the McDonaldization processes, especially those that replace human with nonhuman technology or make customers unpaid workers.

  7. Optimal dynamics for quantum-state and entanglement transfer through homogeneous quantum systems

    International Nuclear Information System (INIS)

    Banchi, L.; Apollaro, T. J. G.; Cuccoli, A.; Vaia, R.; Verrucchi, P.

    2010-01-01

    The capability of faithfully transmit quantum states and entanglement through quantum channels is one of the key requirements for the development of quantum devices. Different solutions have been proposed to accomplish such a challenging task, which, however, require either an ad hoc engineering of the internal interactions of the physical system acting as the channel or specific initialization procedures. Here we show that optimal dynamics for efficient quantum-state and entanglement transfer can be attained in generic quantum systems with homogeneous interactions by tuning the coupling between the system and the two attached qubits. We devise a general procedure to determine the optimal coupling, and we explicitly implement it in the case of a channel consisting of a spin-(1/2)XY chain. The quality of quantum-state and entanglement transfer is found to be very good and, remarkably, almost independent of the channel length.

  8. Transient, but not persistent, adult food insecurity influences toddler development.

    Science.gov (United States)

    Hernandez, Daphne C; Jacknowitz, Alison

    2009-08-01

    In this study, we examined characteristics associated with experiencing persistent and transitional adult food insecurity and how persistent and transitional adult food insecurity influences toddler cognitive and motor development, along with toddler's weight and health status. Using the first 2 waves of the Early Childhood Longitudinal Study-Birth Cohort, 4 mutually exclusive variables capturing persistent and transitional adult food insecurity were created to capture those adults that experience adult food insecurity in the following: both waves, in 1 wave (at 9 or 24 mo after birth), and never experience food insecurity. We used logistic regression models to estimate characteristics associated with the likelihood of experiencing persistent and transitional adult food insecurity. Ordinary least squares regression models were used to estimate how persistent and transitional adult food insecurity influences toddler development. Similar factors influenced one's likelihood of experiencing adult transitional and persistent food insecurity; individuals who experienced any food insecurity were more economically disadvantaged. Thus, outreach efforts do not need to vary by duration of food insecurity. Whereas negative effects of food insecurity on school-aged children are found in the literature, it appears toddlers are buffered from the effects of persistent adult food insecurity. Our findings suggest that toddlers residing with a temporarily food-insecure adult compared with a never food-insecure adult experienced immediate, but small, negative effects on their development. Hence, outreach and assistance may lessen immediate impacts of food insecurity on toddler development.

  9. Robust Multiparty Quantum Secret Key Sharing Over Two Collective-Noise Channels via Three-Photon Mixed States

    International Nuclear Information System (INIS)

    Wang Zhangyin; Yuan Hao; Gao Gan; Shi Shouhua

    2006-01-01

    We present a robust (n,n)-threshold scheme for multiparty quantum secret sharing of key over two collective-noise channels (i.e., the collective dephasing channel and the collective rotating channel) via three-photon mixed states. In our scheme, only if all the sharers collaborate together can they establish a joint key with the message sender and extract the secret message from the sender's encrypted message. This scheme can be implemented using only a Bell singlet, a one-qubit state and polarization identification of single photon, so it is completely feasible according to the present-day technique.

  10. The Over-Barrier Resonant States and Multi-Channel Scattering in Multiple Quantum Wells

    Directory of Open Access Journals (Sweden)

    A Polupanov

    2016-09-01

    Full Text Available We demonstrate an explicit numerical method for accurate calculation of the scattering matrix and its poles, and apply this method to describe the multi-channel scattering in the multiple quantum-wells structures. The S-matrix is continued analytically to the unphysical region of complex energy values. Results of calculations show that there exist one or more S-matrix poles, corresponding to the over-barrier resonant states critical for the effect of the absolute reflection of holes in the energy range where only the heavy ones may propagate over barriers in a structure. Light- and heavy-hole states are described by the Luttinger Hamiltonian matrix. In contrast to the single quantum-well case, at some parameters of a multiple quantum-wells structure the number of S-matrix poles may exceed that of the absolute reflection peaks, and at different values of parameters the absolute reflection peak corresponds to different resonant states. The imaginary parts of the S-matrix poles and hence the lifetimes of resonant states as well as the widths of resonant peaks of absolute reflection depend drastically on the quantum-well potential depth. In the case of shallow quantum wells there is in fact a long-living over-barrier resonant hole state.

  11. Characterization of encapsulated quantum dots via electron channeling contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Deitz, Julia I.; McComb, David W. [Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Carnevale, Santino D. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); De Graef, Marc [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Grassman, Tyler J., E-mail: grassman.5@osu.edu [Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2016-08-08

    A method for characterization of encapsulated epitaxial quantum dots (QD) in plan-view geometry using electron channeling contrast imaging (ECCI) is presented. The efficacy of the method, which requires minimal sample preparation, is demonstrated with proof-of-concept data from encapsulated (sub-surface) epitaxial InAs QDs within a GaAs matrix. Imaging of the QDs under multiple diffraction conditions is presented, establishing that ECCI can provide effectively identical visualization capabilities as conventional two-beam transmission electron microscopy. This method facilitates rapid, non-destructive characterization of sub-surface QDs giving immediate access to valuable nanostructural information.

  12. Spin magneto-transport in a Rashba-Dresselhaus quantum channel with single and double finger gates

    Science.gov (United States)

    Tang, Chi-Shung; Keng, Jia-An; Abdullah, Nzar Rauf; Gudmundsson, Vidar

    2017-05-01

    We address spin-resolved electronic transport properties in a Rashba-Dresselhaus quantum channel in the presence of an in-plane magnetic field. The strong Rashba-Dresselhaus effect induces an asymmetric spin-splitting energy spectrum with a spin-orbit-Zeeman gap. This asymmetric fact in energy spectrum may result in various quantum dynamic features in conductance due to the presence of finger gates. This asymmetric spin-splitting energy spectrum results in a bound state in continuum for electrons within ultralow energy regime with binding energies in order of 10-1 meV.

  13. Quantum coding with finite resources

    Science.gov (United States)

    Tomamichel, Marco; Berta, Mario; Renes, Joseph M.

    2016-01-01

    The quantum capacity of a memoryless channel determines the maximal rate at which we can communicate reliably over asymptotically many uses of the channel. Here we illustrate that this asymptotic characterization is insufficient in practical scenarios where decoherence severely limits our ability to manipulate large quantum systems in the encoder and decoder. In practical settings, we should instead focus on the optimal trade-off between three parameters: the rate of the code, the size of the quantum devices at the encoder and decoder, and the fidelity of the transmission. We find approximate and exact characterizations of this trade-off for various channels of interest, including dephasing, depolarizing and erasure channels. In each case, the trade-off is parameterized by the capacity and a second channel parameter, the quantum channel dispersion. In the process, we develop several bounds that are valid for general quantum channels and can be computed for small instances. PMID:27156995

  14. Universal core model for multiple-gate field-effect transistors with short channel and quantum mechanical effects

    Science.gov (United States)

    Shin, Yong Hyeon; Bae, Min Soo; Park, Chuntaek; Park, Joung Won; Park, Hyunwoo; Lee, Yong Ju; Yun, Ilgu

    2018-06-01

    A universal core model for multiple-gate (MG) field-effect transistors (FETs) with short channel effects (SCEs) and quantum mechanical effects (QMEs) is proposed. By using a Young’s approximation based solution for one-dimensional Poisson’s equations the total inversion charge density (Q inv ) in the channel is modeled for double-gate (DG) and surrounding-gate SG (SG) FETs, following which a universal charge model is derived based on the similarity of the solutions, including for quadruple-gate (QG) FETs. For triple-gate (TG) FETs, the average of DG and QG FETs are used. A SCEs model is also proposed considering the potential difference between the channel’s surface and center. Finally, a QMEs model for MG FETs is developed using the quantum correction compact model. The proposed universal core model is validated on commercially available three-dimensional ATLAS numerical simulations.

  15. Propagation of superconducting coherence via chiral quantum-Hall edge channels.

    Science.gov (United States)

    Park, Geon-Hyoung; Kim, Minsoo; Watanabe, Kenji; Taniguchi, Takashi; Lee, Hu-Jong

    2017-09-08

    Recently, there has been significant interest in superconducting coherence via chiral quantum-Hall (QH) edge channels at an interface between a two-dimensional normal conductor and a superconductor (N-S) in a strong transverse magnetic field. In the field range where the superconductivity and the QH state coexist, the coherent confinement of electron- and hole-like quasiparticles by the interplay of Andreev reflection and the QH effect leads to the formation of Andreev edge states (AES) along the N-S interface. Here, we report the electrical conductance characteristics via the AES formed in graphene-superconductor hybrid systems in a three-terminal configuration. This measurement configuration, involving the QH edge states outside a graphene-S interface, allows the detection of the longitudinal and QH conductance separately, excluding the bulk contribution. Convincing evidence for the superconducting coherence and its propagation via the chiral QH edge channels is provided by the conductance enhancement on both the upstream and the downstream sides of the superconducting electrode as well as in bias spectroscopy results below the superconducting critical temperature. Propagation of superconducting coherence via QH edge states was more evident as more edge channels participate in the Andreev process for high filling factors with reduced valley-mixing scattering.

  16. Food insecurity and child behavior problems in fragile families.

    Science.gov (United States)

    King, Christian

    2018-02-01

    Food insecurity remains a persistent problem in the United States. Several studies have shown that food insecurity is associated with child externalizing and internalizing behavior problems. However, some potential methodological limitations remain. For example, most studies use a household measure of food insecurity while there is evidence that children, especially younger ones, tend to be shielded by their parents from experiencing food insecurity. In addition, the mechanisms through which food insecurity affects children are not well understood. This study uses longitudinal data from the Fragile Families and Child Wellbeing Study to address these limitations. Fixed-effects models show that the association is even larger using a measure of child food insecurity instead of a household one. Correlated-random effects models show a large difference in child behavior problems between food secure and food insecure children due to unobserved heterogeneity. In addition, the association between child food insecurity and child externalizing behaviors remains largely unexplained while food insecurity among adults explains almost all the variation in the association with child internalizing behaviors. Food insecure children and parents are at risk of micronutrient deficiencies, which may lead to behavior problems in young children. These findings underscore the need for greater focus on reducing the risk of food insecurity, especially for children in fragile families, in order to reduce behavior problems and improve their educational attainment. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. CUSTOMER-PERCEIVED INSECURITY OF ONLINE SHOPPING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Matea Matic

    2014-01-01

    Full Text Available Customer-perceived insecurity of online shopping environment has become one of the major obstacles to the growth of electronic commerce. The main purpose of this study was to examine the influence of insecurity of Internet usage towards online purchase decision as well as consumers’ attitudes and intentions towards online purchasing. The data was collected through survey questionnaire using the purposive sample of 253 Croatian students from the University of Dubrovnik. Research results indicate a significant relationship between the insecurity of Internet usage and online purchase decision. Additionally, a significant relationship was found between the insecurity of Internet usage and consumers’ attitudes and intentions towards online purchasing. The overall analysis reveals that consumers have positive attitudes and intentions towards online purchasing whilst insecurity towards online purchasing lowers when online purchases are made more frequently.

  18. Association Between Insecure Attachment and ADHD

    DEFF Research Database (Denmark)

    Storebø, Ole Jakob; Rasmussen, Pernille Darling; Simonsen, Erik

    2016-01-01

    OBJECTIVE: Psychological theories have postulated an association between insecure attachment and ADHD. The objective of this study is to investigate possible association between insecure attachment and ADHD in children and adults. METHOD: Review of literature was performed using the Psyc......INFO, Medline, and EMBASE databases. RESULTS: Twenty-nine studies were included in the review. Overall, the studies showed that parental attachment problems and environmental mediating factors were significantly associated with childhood ADHD. Adults with ADHD had a much higher incidence of insecure attachment...... styles than reported in the general population. CONCLUSION: There seems to be a clear association between ADHD and insecure attachment. It is likely that early intervention in the form of parent training and pharmacological treatment may prevent development of attachment problems. But such studies have...

  19. Entanglement of Gaussian states and the applicability to quantum key distribution over fading channels

    International Nuclear Information System (INIS)

    Usenko, Vladyslav C; Filip, Radim; Heim, Bettina; Peuntinger, Christian; Wittmann, Christoffer; Marquardt, Christoph; Leuchs, Gerd

    2012-01-01

    Entanglement properties of Gaussian states of light as well as the security of continuous variable quantum key distribution with Gaussian states in free-space fading channels are studied. These qualities are shown to be sensitive to the statistical properties of the transmittance distribution in the cases when entanglement is strong or when channel excess noise is present. Fading, i.e. transmission fluctuations, caused by beam wandering due to atmospheric turbulence, is a frequent challenge in free-space communication. We introduce a method of fading discrimination and subsequent post-selection of the corresponding sub-states and show that it can improve the entanglement resource and restore the security of the key distribution over a realistic fading link. Furthermore, the optimal post-selection strategy in combination with an optimized entangled resource is shown to drastically increase the protocol's robustness to excess noise, which is confirmed for experimentally measured fading channel characteristics. The stability of the result against finite data ensemble size and imperfect channel estimation is also addressed. (paper)

  20. Food Insecurity among Homeless Adults with Mental Illness.

    Directory of Open Access Journals (Sweden)

    Milad Parpouchi

    Full Text Available The prevalence of food insecurity and food insufficiency is high among homeless people. We investigated the prevalence and correlates of food insecurity among a cohort of homeless adults with mental illness in Vancouver, British Columbia, Canada.Data collected from baseline questionnaires in the Vancouver At Home study were analysed to calculate the prevalence of food insecurity within the sample (n = 421. A modified version of the U.S. Department of Agriculture's Adult Food Security Survey Module was used to ascertain food insecurity. Univariable and multivariable logistic regression were used to examine potential correlates of food insecurity.The prevalence of food insecurity was 64%. In the multivariable model, food insecurity was significantly associated with age (adjusted odds ratio [aOR] = 0.97; 95% CI: 0.95-0.99, less than high school completion (aOR = 0.57; 95% CI: 0.35-0.93, needing health care but not receiving it (aOR = 1.65; 95% CI: 1.00-2.72, subjective mental health (aOR = 0.97; 95% CI: 0.96-0.99, having spent over $500 for drugs and alcohol in the past month (aOR = 2.25; 95% CI: 1.16-4.36, HIV/AIDS (aOR = 4.20; 95% CI: 1.36-12.96, heart disease (aOR = 0.39; 95% CI: 0.16-0.97 and having gone to a drop-in centre, community meal centre or program/food bank (aOR = 1.65; 95% CI: 1.01-2.68.The prevalence of food insecurity was extremely high in a cohort with longstanding homelessness and serious mental illness. Younger age, needing health care but not receiving it, poorer subjective mental health, having spent over $500 for drugs and alcohol in the past month, HIV/AIDS and having gone to a drop-in centre, community meal centre or program/food bank each increased odds of food insecurity, while less than high school completion and heart disease each decreased odds of food insecurity. Interventions to reduce food insecurity in this population are urgently needed.

  1. Relation between household food insecurity and breastfeeding in Canada.

    Science.gov (United States)

    Orr, Sarah K; Dachner, Naomi; Frank, Lesley; Tarasuk, Valerie

    2018-03-19

    Qualitative studies have suggested that food insecurity adversely affects infant feeding practices. We aimed to determine how household food insecurity relates to breastfeeding initiation, duration of exclusive breastfeeding and vitamin D supplementation of breastfed infants in Canada. We studied 10 450 women who had completed the Maternal Experiences - Breastfeeding Module and the Household Food Security Survey Module of the Canadian Community Health Survey (2005-2014) and who had given birth in the year of or year before their interview. We used multivariable Cox proportional hazards models and logistic regression to examine the relation between food insecurity and infant feeding practices, adjusting for sociodemographic characteristics, maternal mood disorders and diabetes mellitus. Overall, 17% of the women reported household food insecurity, of whom 8.6% had moderate food insecurity and 2.9% had severe food insecurity (weighted percentages). After adjustment for sociodemographic factors, women with food insecurity were no less likely than others to initiate breastfeeding or provide vitamin D supplementation to their infants. Half of the women with food insecurity ceased exclusive breastfeeding by 2 months, whereas most of those with food security persisted with breastfeeding for 4 months or more. Relative to women with food security, those with marginal, moderate and severe food insecurity had significantly lower odds of exclusive breastfeeding to 4 months, but only women with moderate food insecurity had lower odds of exclusive breastfeeding to 6 months, independent of sociodemographic characteristics (odds ratio 0.60, 95% confidence interval 0.39-0.92). Adjustment for maternal mood disorder or diabetes slightly attenuated these relationships. Mothers caring for infants in food-insecure households attempted to follow infant feeding recommendations, but were less able than women with food security to sustain exclusive breastfeeding. Our findings highlight the

  2. Relations between Formal Linguistic Insecurity and the Perception of Linguistic Insecurity: A Quantitative Study in an Educational Environment at the Valencian Community (Spain)

    Science.gov (United States)

    Baldaqui Escandell, Josep M.

    2011-01-01

    What is the relationship between the awareness of linguistic prestige and the security or insecurity in the use of minoritised languages? Is formal linguistic insecurity (as initially described by Labov) the same as the speakers' perception of linguistic insecurity? Which are the variables related to the various types of linguistic insecurity in…

  3. Toward prethreshold gate-based quantum simulation of chemical dynamics: using potential energy surfaces to simulate few-channel molecular collisions

    Science.gov (United States)

    Sornborger, Andrew T.; Stancil, Phillip; Geller, Michael R.

    2018-05-01

    One of the most promising applications of an error-corrected universal quantum computer is the efficient simulation of complex quantum systems such as large molecular systems. In this application, one is interested in both the electronic structure such as the ground state energy and dynamical properties such as the scattering cross section and chemical reaction rates. However, most theoretical work and experimental demonstrations have focused on the quantum computation of energies and energy surfaces. In this work, we attempt to make the prethreshold (not error-corrected) quantum simulation of dynamical properties practical as well. We show that the use of precomputed potential energy surfaces and couplings enables the gate-based simulation of few-channel but otherwise realistic molecular collisions. Our approach is based on the widely used Born-Oppenheimer approximation for the structure problem coupled with a semiclassical method for the dynamics. In the latter the electrons are treated quantum mechanically but the nuclei are classical, which restricts the collisions to high energy or temperature (typically above ≈ 10 eV). By using operator splitting techniques optimized for the resulting time-dependent Hamiltonian simulation problem, we give several physically realistic collision examples, with 3-8 channels and circuit depths < 1000.

  4. Smoking Predicts Food Insecurity Severity among Persons Living with HIV.

    Science.gov (United States)

    Kim-Mozeleski, Jin E; Tsoh, Janice Y; Ramirez-Forcier, Joseph; Andrews, Brett; Weiser, Sheri D; Carrico, Adam W

    2018-02-28

    Food insecurity is a key social and health issue among persons living with HIV (PLHIV). Food insecurity oftentimes co-occurs with substance use, but little is known about the relationship between tobacco use and food insecurity particularly among PLHIV. In this study, we prospectively examined the association of cigarette smoking with food insecurity in a cohort of 108 individuals seeking vocational rehabilitation services. Over the 12-month study period, smokers at baseline reported consistently higher levels of food insecurity compared to non-smokers. Smoking remained an independent risk factor for greater food insecurity, controlling for sociodemographic characteristics and known confounders (e.g., substance use, depression). Food insecurity is a key structural and socioeconomic barrier that may partially explain HIV-related health disparities observed among smokers. Further research is needed to characterize the bio-behavioral mechanisms linking smoking and food insecurity as well as test whether smoking cessation can reduce food insecurity in PLHIV who smoke.

  5. Implications of reflected appraisals of interpersonal insecurity for suspicion and power.

    Science.gov (United States)

    Lemay, Edward P; Dudley, Kari L

    2009-12-01

    In three studies, the authors tested a model positing that chronically insecure individuals often believe that their relationship partners view them as highly insecure. In turn, because of expectations regarding the social consequences of expressing insecurities, these reflected appraisals of insecurity are thought to predict suspicion of partners' authenticity and feelings of powerlessness within relationships. Results supported these predictions. Self-esteem, attachment anxiety, neuroticism, proclivity for anger, and proclivity for hurt feelings predicted reflected appraisals of insecurity independently of whether partners detected insecurity. In turn, chronically insecure participants were suspicious of their partners' authenticity and felt powerless in their relationships partly because they believed they were viewed as insecure. This research suggests that beliefs that one is perceived as insecure, even when they are misguided, can partially explain interpersonal cognitions associated with actually being insecure.

  6. Quantum Secure Direct Communication Using W State

    International Nuclear Information System (INIS)

    Dong Li; Xiu Xiaoming; Gao Yajun; Chi Feng

    2008-01-01

    A theoretical scheme of quantum secure direct communication using teleportation is proposed. In the scheme, the sender needs to prepare a class of three-particle W states to use as quantum channel. The two communicators may communicate after they test the security of the quantum channel. The security of the protocol is ensured by quantum entanglement and quantum no-cloning theorem. The receiver can obtain the secret message determinately if the quantum channel is secure

  7. Association between food insecurity and food intake.

    Science.gov (United States)

    Araújo, Melissa Luciana de; Mendonça, Raquel de Deus; Lopes Filho, José Divino; Lopes, Aline Cristine Souza

    2018-03-28

    We aim to identify the prevalence of food insecurity and to ascertain the association between food insecurity and food intake. A cross-sectional survey. The study included users of a primary healthcare service in Belo Horizonte, Brazil, from 2013 to 2014. Socioeconomic, health, and food intake data were gathered using a questionnaire and the Brazilian Food Insecurity Scale. Individuals 20 years old or older (n = 2817). The prevalence of food insecurity among families with individuals under 18 years was 41.0%, and 26.4% in other households. After adjusting for potential confounders, the households in food insecurity with members under 18 years old, the consumption of fruits and vegetables (RP = 0.70, 95%IC: 0.58-0.84), and fruits (RP = 0.74, 95%IC: 0.59-0.93) was lower; and consumption of beans was higher (RP = 1.49, 95%IC: 1.06-2.09) compared to those with food security. In households without members under 18 years old, the consumption of fruits and vegetables (RP = 0.68, 95%IC: 0.58-0.79), fruits (RP = 0.61, 95%IC: 0.50-0.74), and beans (RP = 0.78, 95%IC: 0.63-0.97) was lower; and the consumption of tubers (RP = 1.36, 95%IC: 1.03-1.79) was higher. However, the state of food insecurity did not affect the consumption of ultra-processed foods, independently of age, sex, marital status, educational level, and employed status. Food insecurity negatively affected the fruit and vegetable consumption in both types of families tested. The consumption of beans was higher in households with children and adolescents, and the consumption of tubers was higher in households without children and adolescents. However, food insecurity did not change the intake of ultraprocessed foods. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Quantum reading capacity

    International Nuclear Information System (INIS)

    Pirandola, Stefano; Braunstein, Samuel L; Lupo, Cosmo; Mancini, Stefano; Giovannetti, Vittorio

    2011-01-01

    The readout of a classical memory can be modelled as a problem of quantum channel discrimination, where a decoder retrieves information by distinguishing the different quantum channels encoded in each cell of the memory (Pirandola 2011 Phys. Rev. Lett. 106 090504). In the case of optical memories, such as CDs and DVDs, this discrimination involves lossy bosonic channels and can be remarkably boosted by the use of nonclassical light (quantum reading). Here we generalize these concepts by extending the model of memory from single-cell to multi-cell encoding. In general, information is stored in a block of cells by using a channel-codeword, i.e. a sequence of channels chosen according to a classical code. Correspondingly, the readout of data is realized by a process of ‘parallel’ channel discrimination, where the entire block of cells is probed simultaneously and decoded via an optimal collective measurement. In the limit of a large block we define the quantum reading capacity of the memory, quantifying the maximum number of readable bits per cell. This notion of capacity is nontrivial when we suitably constrain the physical resources of the decoder. For optical memories (encoding bosonic channels), such a constraint is energetic and corresponds to fixing the mean total number of photons per cell. In this case, we are able to prove a separation between the quantum reading capacity and the maximum information rate achievable by classical transmitters, i.e. arbitrary classical mixtures of coherent states. In fact, we can easily construct nonclassical transmitters that are able to outperform any classical transmitter, thus showing that the advantages of quantum reading persist in the optimal multi-cell scenario. (paper)

  9. Counterfactual quantum cryptography.

    Science.gov (United States)

    Noh, Tae-Gon

    2009-12-04

    Quantum cryptography allows one to distribute a secret key between two remote parties using the fundamental principles of quantum mechanics. The well-known established paradigm for the quantum key distribution relies on the actual transmission of signal particle through a quantum channel. In this Letter, we show that the task of a secret key distribution can be accomplished even though a particle carrying secret information is not in fact transmitted through the quantum channel. The proposed protocols can be implemented with current technologies and provide practical security advantages by eliminating the possibility that an eavesdropper can directly access the entire quantum system of each signal particle.

  10. Experiences with "Acute" Food Insecurity among College Students

    Science.gov (United States)

    Wood, J. Luke; Harris, Frank, III

    2018-01-01

    This study sought to understand which racial/ethnic student groups experience food insecurity and the extent to which other external insecurities and challenges are predictive of acute food insecurity. Data were derived from the Community College Success Measure (CCSM), an institutional needs assessment tool used by colleges to examine challenges…

  11. The validity of quantum-classical multi-channel diffusion equations describing interlevel transitions in the condensed phase. The adiabatic representation

    CERN Document Server

    Basilevsky, M V

    2002-01-01

    We develop an approach for derivation of quantum-classical relaxation equations for a two-channel problem. The treatment is based on the adiabatic channel wavefunctions and the system-bath coupling is modelled as a bilinear interaction in momentum representation. In the quantum-classical limit we obtain Liouville equations with the relaxation operator containing diffusion terms diagonal in Liouvillian space and the off-diagonal part which is responsible for thermal interlevel transitions. The high-frequency interlevel quantum beats are fully taken into account in this relaxation term. In the framework of the present formulation and as a consequence of the momentum-dependent interaction the Smoluchovsky diffusion limit can be reached without invoking Fokker-Planck equations as an intermediate step. The inherent property of equations so obtained is that the partial rates of interlevel transitions obey the principle of detailed balance. This result could not be gained in earlier treatments of the two-level diffu...

  12. Conditional quantum entropy power inequality for d-level quantum systems

    Science.gov (United States)

    Jeong, Kabgyun; Lee, Soojoon; Jeong, Hyunseok

    2018-04-01

    We propose an extension of the quantum entropy power inequality for finite dimensional quantum systems, and prove a conditional quantum entropy power inequality by using the majorization relation as well as the concavity of entropic functions also given by Audenaert et al (2016 J. Math. Phys. 57 052202). Here, we make particular use of the fact that a specific local measurement after a partial swap operation (or partial swap quantum channel) acting only on finite dimensional bipartite subsystems does not affect the majorization relation for the conditional output states when a separable ancillary subsystem is involved. We expect our conditional quantum entropy power inequality to be useful, and applicable in bounding and analyzing several capacity problems for quantum channels.

  13. Multi-party Semi-quantum Key Agreement with Delegating Quantum Computation

    Science.gov (United States)

    Liu, Wen-Jie; Chen, Zhen-Yu; Ji, Sai; Wang, Hai-Bin; Zhang, Jun

    2017-10-01

    A multi-party semi-quantum key agreement (SQKA) protocol based on delegating quantum computation (DQC) model is proposed by taking Bell states as quantum resources. In the proposed protocol, the participants only need the ability of accessing quantum channel and preparing single photons {|0〉, |1〉, |+〉, |-〉}, while the complicated quantum operations, such as the unitary operations and Bell measurement, will be delegated to the remote quantum center. Compared with previous quantum key agreement protocols, this client-server model is more feasible in the early days of the emergence of quantum computers. In order to prevent the attacks from outside eavesdroppers, inner participants and quantum center, two single photon sequences are randomly inserted into Bell states: the first sequence is used to perform the quantum channel detection, while the second is applied to disorder the positions of message qubits, which guarantees the security of the protocol.

  14. Noisy non-transitive quantum games

    International Nuclear Information System (INIS)

    Ramzan, M; Khan, Salman; Khan, M Khalid

    2010-01-01

    We study the effect of quantum noise in 3 x 3 entangled quantum games. By taking into account different noisy quantum channels, we analyze how a two-player, three-strategy Rock-Scissor-Paper game is influenced by the quantum noise. We consider the winning non-transitive strategies R, S and P such that R beats S, S beats P and P beats R. The game behaves as a noiseless game for the maximum value of the quantum noise. It is seen that Alice's payoff is heavily influenced by the depolarizing noise as compared to the amplitude damping noise. A depolarizing channel causes a monotonic decrease in players' payoffs as we increase the amount of quantum noise. In the case of the amplitude damping channel, Alice's payoff function reaches its minimum for α = 0.5 and is symmetrical. This means that larger values of quantum noise influence the game weakly. On the other hand, the phase damping channel does not influence the game. Furthermore, the Nash equilibrium and non-transitive character of the game are not affected under the influence of quantum noise.

  15. Food Insecurity, CKD, and Subsequent ESRD in US Adults.

    Science.gov (United States)

    Banerjee, Tanushree; Crews, Deidra C; Wesson, Donald E; Dharmarajan, Sai; Saran, Rajiv; Ríos Burrows, Nilka; Saydah, Sharon; Powe, Neil R

    2017-07-01

    Poor access to food among low-income adults has been recognized as a risk factor for chronic kidney disease (CKD), but there are no data for the impact of food insecurity on progression to end-stage renal disease (ESRD). We hypothesized that food insecurity would be independently associated with risk for ESRD among persons with and without earlier stages of CKD. Longitudinal cohort study. 2,320 adults (aged ≥ 20 years) with CKD and 10,448 adults with no CKD enrolled in NHANES III (1988-1994) with household income ≤ 400% of the federal poverty level linked to the Medicare ESRD Registry for a median follow-up of 12 years. Food insecurity, defined as an affirmative response to the food-insecurity screening question. Development of ESRD. Demographics, income, diabetes, hypertension, estimated glomerular filtration rate, and albuminuria. Dietary acid load was estimated from 24-hour dietary recall. We used a Fine-Gray competing-risk model to estimate the relative hazard (RH) for ESRD associated with food insecurity after adjusting for covariates. 4.5% of adults with CKD were food insecure. Food-insecure individuals were more likely to be younger and have diabetes (29.9%), hypertension (73.9%), or albuminuria (90.4%) as compared with their counterparts (Pinsecure group was 51.2 mEq/d versus 55.6 mEq/d, respectively (P=0.05). Food-insecure adults were more likely to develop ESRD (RH, 1.38; 95% CI, 1.08-3.10) compared with food-secure adults after adjustment for demographics, income, diabetes, hypertension, estimated glomerular filtration rate, and albuminuria. In the non-CKD group, 5.7% were food insecure. We did not find a significant association between food insecurity and ESRD (RH, 0.77; 95% CI, 0.40-1.49). Use of single 24-hour diet recall; lack of laboratory follow-up data and measure of changes in food insecurity over time; follow-up of cohort ended 10 years ago. Among adults with CKD, food insecurity was independently associated with a higher likelihood of

  16. Food Insecurity and Obesity: Exploring the Role of Social Support.

    Science.gov (United States)

    Ashe, Karen M; Lapane, Kate L

    2018-05-01

    Women are disproportionately affected by both obesity and food insecurity. Food insecurity occurs when there is limited ability to acquire adequate foods. It is unknown whether social support can reduce the effect of food insecurity on increased obesity. This study seeks to determine whether social support modifies the relationship between food insecurity and obesity. We conducted a cross-sectional study in a nationally representative sample of 4672 women aged ≥40 years using National Health and Nutrition Examination Survey (2003-2008). Individual food insecurity was assessed based on the U.S. Department of Agriculture 18-item validated household food security scale. Women were categorized as fully food secure (0 affirmative responses) or food insecure (1-10 affirmative responses). Obesity was defined as body mass index ≥30 kg/m 2 . Outcomes were analyzed by multivariable logistic regression. Fourteen percent were food insecure. Women with food insecurity had 1.4 the odds of obesity as those who were fully food secure, adjusting for race/ethnicity and health status (95% confidence interval [CI] 1.22-1.62). Food-insecure women were 80% less likely to report strong social support than women who were fully food secure (95% CI 0.11-0.36). Social support as measured in this study did not modify the association between food insecurity and obesity. Women reporting food insecurity reported lower levels of social support and were more likely to experience obesity. Interventions to reduce obesity in women who are food insecure must consider the limited resources available to these women.

  17. Expanding the Scales and Domains of (in)Security

    DEFF Research Database (Denmark)

    Gough, Katherine V.; Chigunta, Francis; Langevang, Thilde

    2016-01-01

    Most research on issues of (in)security has tended to have a military/safety angle and focus on global/national scales linked to spectacular events. This paper addresses the overlooked insecurity realities of urban dwellers in the global South through a focus on more persistent and enduring forms...... and education. Although the youth unemployment situation is often viewed as a serious threat to human security, we show how the lack of stable employment in itself is a manifestation of insecurity......Most research on issues of (in)security has tended to have a military/safety angle and focus on global/national scales linked to spectacular events. This paper addresses the overlooked insecurity realities of urban dwellers in the global South through a focus on more persistent and enduring forms...

  18. Electron quantum optics as quantum signal processing

    OpenAIRE

    Roussel, B.; Cabart, C.; Fève, G.; Thibierge, E.; Degiovanni, P.

    2016-01-01

    The recent developments of electron quantum optics in quantum Hall edge channels have given us new ways to probe the behavior of electrons in quantum conductors. It has brought new quantities called electronic coherences under the spotlight. In this paper, we explore the relations between electron quantum optics and signal processing through a global review of the various methods for accessing single- and two-electron coherences in electron quantum optics. We interpret electron quantum optics...

  19. Addressing Food Insecurity in Family Medicine and Medical Education.

    Science.gov (United States)

    Smith, Sunny; Malinak, David; Chang, Jinnie; Schultz, Amanda; Brownell, Kristin

    2017-11-01

    Food insecurity is associated with poor health outcomes, yet is not routinely addressed in health care. This study was conducted to determine if education regarding food insecurity as a health issue could modify knowledge, attitudes, and clinical behavior. Educational sessions on food insecurity and its impact on health were conducted in 2015 at three different family medicine residency programs and one medical school. A pre/post survey was given immediately before and after this session. Attendees were encouraged to identify and implement individual and system-based changes to integrate food insecurity screening and referrals into their clinical practices. Participants completed follow-up surveys approximately 1 year later, and the authors obtained systems-level data from electronic health records and databases. Pre/post means (SD) were compared using t-tests. The numbers of patients screened and referred were calculated. Eighty-five participants completed the pre/post survey during the educational sessions (51 medical students, 29 residents, 5 faculty). Self-reported knowledge of food insecurity, resources, and willingness to discuss with patients increased (Pinsecurity during clinical visits and referrals to food resources. Over 1,600 patients were screened for food insecurity as a result of systems-based changes. Educational interventions focused on the role of food insecurity in health can produce improvements in knowledge and attitudes toward addressing food insecurity, increase discussions with patients about food insecurity, and result in measurable patient and systems-level changes.

  20. Fundamental limits of repeaterless quantum communications

    Science.gov (United States)

    Pirandola, Stefano; Laurenza, Riccardo; Ottaviani, Carlo; Banchi, Leonardo

    2017-01-01

    Quantum communications promises reliable transmission of quantum information, efficient distribution of entanglement and generation of completely secure keys. For all these tasks, we need to determine the optimal point-to-point rates that are achievable by two remote parties at the ends of a quantum channel, without restrictions on their local operations and classical communication, which can be unlimited and two-way. These two-way assisted capacities represent the ultimate rates that are reachable without quantum repeaters. Here, by constructing an upper bound based on the relative entropy of entanglement and devising a dimension-independent technique dubbed ‘teleportation stretching', we establish these capacities for many fundamental channels, namely bosonic lossy channels, quantum-limited amplifiers, dephasing and erasure channels in arbitrary dimension. In particular, we exactly determine the fundamental rate-loss tradeoff affecting any protocol of quantum key distribution. Our findings set the limits of point-to-point quantum communications and provide precise and general benchmarks for quantum repeaters. PMID:28443624

  1. Quantum biological information theory

    CERN Document Server

    Djordjevic, Ivan B

    2016-01-01

    This book is a self-contained, tutorial-based introduction to quantum information theory and quantum biology. It serves as a single-source reference to the topic for researchers in bioengineering, communications engineering, electrical engineering, applied mathematics, biology, computer science, and physics. The book provides all the essential principles of the quantum biological information theory required to describe the quantum information transfer from DNA to proteins, the sources of genetic noise and genetic errors as well as their effects. Integrates quantum information and quantum biology concepts; Assumes only knowledge of basic concepts of vector algebra at undergraduate level; Provides a thorough introduction to basic concepts of quantum information processing, quantum information theory, and quantum biology; Includes in-depth discussion of the quantum biological channel modelling, quantum biological channel capacity calculation, quantum models of aging, quantum models of evolution, quantum models o...

  2. Multi-channel conduction in redox-based resistive switch modelled using quantum point contact theory

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, E., E-mail: enrique.miranda@uab.cat; Suñé, J. [Departament d' Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallés, Barcelona (Spain); Mehonic, A.; Kenyon, A. J. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2013-11-25

    A simple analytic model for the electron transport through filamentary-type structures in Si-rich silica (SiO{sub x})-based resistive switches is proposed. The model is based on a mesoscopic description and is able to account for the linear and nonlinear components of conductance that arise from both fully and partially formed conductive channels spanning the dielectric film. Channels are represented by arrays of identical scatterers whose number and quantum transmission properties determine the current magnitude in the low and high resistance states. We show that the proposed model not only reproduces the experimental current-voltage (I-V) characteristics but also the normalized differential conductance (dln(I)/dln(V)-V) curves of devices under test.

  3. Job insecurity and health: a study of 16 European countries.

    Science.gov (United States)

    László, Krisztina D; Pikhart, Hynek; Kopp, Mária S; Bobak, Martin; Pajak, Andrzej; Malyutina, Sofia; Salavecz, Gyöngyvér; Marmot, Michael

    2010-03-01

    Although the number of insecure jobs has increased considerably over the recent decades, relatively little is known about the health consequences of job insecurity, their international pattern, and factors that may modify them. In this paper, we investigated the association between job insecurity and self-rated health, and whether the relationship differs by country or individual-level characteristics. Cross-sectional data from 3 population-based studies on job insecurity, self-rated health, demographic, socioeconomic, work-related and behavioural factors and lifetime chronic diseases in 23,245 working subjects aged 45-70 years from 16 European countries were analysed using logistic regression and meta-analysis. In fully adjusted models, job insecurity was significantly associated with an increased risk of poor health in the Czech Republic, Denmark, Germany, Greece, Hungary, Israel, the Netherlands, Poland and Russia, with odds ratios ranging between 1.3 and 2.0. Similar, but not significant, associations were observed in Austria, France, Italy, Spain and Switzerland. We found no effect of job insecurity in Belgium and Sweden. In the pooled data, the odds ratio of poor health by job insecurity was 1.39. The association between job insecurity and health did not differ significantly by age, sex, education, and marital status. Persons with insecure jobs were at an increased risk of poor health in most of the countries included in the analysis. Given these results and trends towards increasing frequency of insecure jobs, attention needs to be paid to the public health consequences of job insecurity. Copyright 2009 Elsevier Ltd. All rights reserved.

  4. Quantum information to the home

    International Nuclear Information System (INIS)

    Choi, Iris; Young, Robert J; Townsend, Paul D

    2011-01-01

    Information encoded on individual quanta will play an important role in our future lives, much as classically encoded digital information does today. Combining quantum information carried by single photons with classical signals encoded on strong laser pulses in modern fibre-to-the-home (FTTH) networks is a significant challenge, the solution to which will facilitate the global distribution of quantum information to the home and with it a quantum internet. In real-world networks, spontaneous Raman scattering in the optical fibre would induce crosstalk between the high-power classical channels and a single-photon quantum channel, such that the latter is unable to operate. Here, we show that the integration of quantum and classical information on an FTTH network is possible by performing quantum key distribution (QKD) on a network while simultaneously transferring realistic levels of classical data. Our novel scheme involves synchronously interleaving a channel of quantum data with the Raman scattered photons from a classical channel, exploiting the periodic minima in the instantaneous crosstalk and thereby enabling secure QKD to be performed.

  5. Quantum information to the home

    Science.gov (United States)

    Choi, Iris; Young, Robert J.; Townsend, Paul D.

    2011-06-01

    Information encoded on individual quanta will play an important role in our future lives, much as classically encoded digital information does today. Combining quantum information carried by single photons with classical signals encoded on strong laser pulses in modern fibre-to-the-home (FTTH) networks is a significant challenge, the solution to which will facilitate the global distribution of quantum information to the home and with it a quantum internet [1]. In real-world networks, spontaneous Raman scattering in the optical fibre would induce crosstalk between the high-power classical channels and a single-photon quantum channel, such that the latter is unable to operate. Here, we show that the integration of quantum and classical information on an FTTH network is possible by performing quantum key distribution (QKD) on a network while simultaneously transferring realistic levels of classical data. Our novel scheme involves synchronously interleaving a channel of quantum data with the Raman scattered photons from a classical channel, exploiting the periodic minima in the instantaneous crosstalk and thereby enabling secure QKD to be performed.

  6. Quantum information to the home

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Iris; Young, Robert J; Townsend, Paul D, E-mail: paul.townsend@tyndall.ie [Photonic Systems Group, Tyndall National Institute and Department of Physics, University College Cork, Cork (Ireland)

    2011-06-15

    Information encoded on individual quanta will play an important role in our future lives, much as classically encoded digital information does today. Combining quantum information carried by single photons with classical signals encoded on strong laser pulses in modern fibre-to-the-home (FTTH) networks is a significant challenge, the solution to which will facilitate the global distribution of quantum information to the home and with it a quantum internet. In real-world networks, spontaneous Raman scattering in the optical fibre would induce crosstalk between the high-power classical channels and a single-photon quantum channel, such that the latter is unable to operate. Here, we show that the integration of quantum and classical information on an FTTH network is possible by performing quantum key distribution (QKD) on a network while simultaneously transferring realistic levels of classical data. Our novel scheme involves synchronously interleaving a channel of quantum data with the Raman scattered photons from a classical channel, exploiting the periodic minima in the instantaneous crosstalk and thereby enabling secure QKD to be performed.

  7. Enhancement-mode two-channel triple quantum dot from an undoped Si/Si0.8Ge0.2 quantum well hetero-structure.

    Energy Technology Data Exchange (ETDEWEB)

    Studenikin, S. A.; Gaudreau, L.; Kataoka, K.; Austing, D. G.; Lu, Tzu-Ming; Luhman, Dwight; Bethke, Donald Thomas; Wanke, Michael; Lilly, Michael; Carroll, Malcolm S.; Sachrajda, A. S.

    2017-12-01

    We demonstrate coupled triple dot operation and charge sensing capability for the recently introduced quantum dot technology employing undoped Si/Si0.8Ge0.2 hetero-structures which also incorporate a single metal-gate layer to simplify fabrication [T. M. Lu et al., Appl. Phys. Lett. 109, 093102 (2016)]. Si/SiGe hetero-structures with a Ge concentration of 20% rather than the more usual 30% typically encountered offer higher electron mobility. The devices consist of two in-plane parallel electron channels that host a double dot in one channel and a single dot in the other channel. In a device where the channels are sufficiently close a triple dot in a triangular configuration is induced leading to regions in the charge stability diagram where three addition lines of different slope approach each other and anti-cross. In a device where the channels are further apart the single dot charge-senses the double dot with relative change of ~2% in the sensor current. We also highlight temporal drifting and metastability of the Coulomb oscillations. These effects are induced if the temperature environment of the device is not kept constant and arise from non-equilibrium charge redistribution and subsequent slow recovery.

  8. Food Insecurity as a Student Issue

    Science.gov (United States)

    Cady, Clare L.

    2014-01-01

    Food insecurity is a threat to student success on college campuses in the United States. It has the potential to impact academics, wellness, and behavior--all factors that have bearing on student retention and graduation rates. This article reviews the literature on food insecurity among college students, utilizing research on hunger and…

  9. Insecurity, social dynamic and obesity

    DEFF Research Database (Denmark)

    Ditlevsen, Kia

    Increasing attention is being paid to the link between insecurity and obesity. The link is, however, still mainly described on national level as causal connections between social security and prevalence of obesity. This is the claim presented by Offer and colleges in their book Insecurity...... or individual level. In this manner, the connection also remains out of reach and hard to act upon. In the cross disciplinary field of obesity research, where biomedical world views and large scale quantitative analyzes are dominating, the sociology of health and illness have an important role to play......, Inequality and obesity where market liberal states are shown to have higher levels of insecurity compared to welfare states, such as the Nordic countries. This connection remains rather abstract: why and how this connection works are unanswered questions, especially when moving from state level to social...

  10. Adaptive estimation and discrimination of Holevo-Werner channels

    Directory of Open Access Journals (Sweden)

    Cope Thomas P. W.

    2017-12-01

    Full Text Available The class of quantum states known as Werner states have several interesting properties, which often serve to illuminate unusual properties of quantum information. Closely related to these states are the Holevo- Werner channels whose Choi matrices are Werner states. Exploiting the fact that these channels are teleportation covariant, and therefore simulable by teleportation, we compute the ultimate precision in the adaptive estimation of their channel-defining parameter. Similarly, we bound the minimum error probability affecting the adaptive discrimination of any two of these channels. In this case, we prove an analytical formula for the quantum Chernoff bound which also has a direct counterpart for the class of depolarizing channels. Our work exploits previous methods established in [Pirandola and Lupo, PRL 118, 100502 (2017] to set the metrological limits associated with this interesting class of quantum channels at any finite dimension.

  11. Noisy non-transitive quantum games

    Energy Technology Data Exchange (ETDEWEB)

    Ramzan, M; Khan, Salman; Khan, M Khalid, E-mail: mramzan@phys.qau.edu.p [Department of Physics Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2010-07-02

    We study the effect of quantum noise in 3 x 3 entangled quantum games. By taking into account different noisy quantum channels, we analyze how a two-player, three-strategy Rock-Scissor-Paper game is influenced by the quantum noise. We consider the winning non-transitive strategies R, S and P such that R beats S, S beats P and P beats R. The game behaves as a noiseless game for the maximum value of the quantum noise. It is seen that Alice's payoff is heavily influenced by the depolarizing noise as compared to the amplitude damping noise. A depolarizing channel causes a monotonic decrease in players' payoffs as we increase the amount of quantum noise. In the case of the amplitude damping channel, Alice's payoff function reaches its minimum for {alpha} = 0.5 and is symmetrical. This means that larger values of quantum noise influence the game weakly. On the other hand, the phase damping channel does not influence the game. Furthermore, the Nash equilibrium and non-transitive character of the game are not affected under the influence of quantum noise.

  12. Relativistic quantum cryptography

    International Nuclear Information System (INIS)

    Radchenko, I V; Kravtsov, K S; Kulik, S P; Molotkov, S N

    2014-01-01

    Quantum key distribution (QKD) is a concept of secret key exchange supported by fundamentals of quantum physics. Its perfect realization offers unconditional key security, however, known practical schemes are potentially vulnerable if the quantum channel loss exceeds a certain realization-specific bound. This discrepancy is caused by the fact that any practical photon source has a non-zero probability of emitting two or more photons at a time, while theory needs exactly one. We report an essentially different QKD scheme based on both quantum physics and theory of relativity. It works flawlessly with practical photon sources at arbitrary large channel loss. Our scheme is naturally tailored for free-space optical channels, and may be used in ground-to-satellite communications, where losses are prohibitively large and unpredictable for conventional QKD. (letters)

  13. Quantum conductance in silicon quantum wires

    CERN Document Server

    Bagraev, N T; Klyachkin, L E; Malyarenko, A M; Gehlhoff, W; Ivanov, V K; Shelykh, I A

    2002-01-01

    The results of investigations of electron and hole quantum conductance staircase in silicon quantum wires are presented. The characteristics of self-ordering quantum wells of n- and p-types, which from on the silicon (100) surface in the nonequilibrium boron diffusion process, are analyzed. The results of investigations of the quantum conductance as the function of temperature, carrier concentration and modulation degree of silicon quantum wires are given. It is found out, that the quantum conductance of the one-dimensional channels is observed, for the first time, at an elevated temperature (T >= 77 K)

  14. Positivity, discontinuity, finite resources, and nonzero error for arbitrarily varying quantum channels

    International Nuclear Information System (INIS)

    Boche, H.; Nötzel, J.

    2014-01-01

    This work is motivated by a quite general question: Under which circumstances are the capacities of information transmission systems continuous? The research is explicitly carried out on finite arbitrarily varying quantum channels (AVQCs). We give an explicit example that answers the recent question whether the transmission of messages over AVQCs can benefit from assistance by distribution of randomness between the legitimate sender and receiver in the affirmative. The specific class of channels introduced in that example is then extended to show that the unassisted capacity does have discontinuity points, while it is known that the randomness-assisted capacity is always continuous in the channel. We characterize the discontinuity points and prove that the unassisted capacity is always continuous around its positivity points. After having established shared randomness as an important resource, we quantify the interplay between the distribution of finite amounts of randomness between the legitimate sender and receiver, the (nonzero) probability of a decoding error with respect to the average error criterion and the number of messages that can be sent over a finite number of channel uses. We relate our results to the entanglement transmission capacities of finite AVQCs, where the role of shared randomness is not yet well understood, and give a new sufficient criterion for the entanglement transmission capacity with randomness assistance to vanish

  15. Chronic disease burden predicts food insecurity among older adults.

    Science.gov (United States)

    Jih, Jane; Stijacic-Cenzer, Irena; Seligman, Hilary K; Boscardin, W John; Nguyen, Tung T; Ritchie, Christine S

    2018-06-01

    Increased out-of-pocket health-care expenditures may exert budget pressure on low-income households that leads to food insecurity. The objective of the present study was to examine whether older adults with higher chronic disease burden are at increased risk of food insecurity. Secondary analysis of the 2013 Health and Retirement Study (HRS) Health Care and Nutrition Study (HCNS) linked to the 2012 nationally representative HRS. USA. Respondents of the 2013 HRS HCNS with household incomes insecurity was 27·8 %. Compared with those having 0-1 conditions, respondents with MCC were significantly more likely to report food insecurity, with the adjusted odds ratio for those with 2-4 conditions being 2·12 (95 % CI 1·45, 3·09) and for those with ≥5 conditions being 3·64 (95 % CI 2·47, 5·37). A heavy chronic disease burden likely exerts substantial pressure on the household budgets of older adults, creating an increased risk for food insecurity. Given the high prevalence of food insecurity among older adults, screening those with MCC for food insecurity in the clinical setting may be warranted in order to refer to community food resources.

  16. Quantum signature scheme based on a quantum search algorithm

    International Nuclear Information System (INIS)

    Yoon, Chun Seok; Kang, Min Sung; Lim, Jong In; Yang, Hyung Jin

    2015-01-01

    We present a quantum signature scheme based on a two-qubit quantum search algorithm. For secure transmission of signatures, we use a quantum search algorithm that has not been used in previous quantum signature schemes. A two-step protocol secures the quantum channel, and a trusted center guarantees non-repudiation that is similar to other quantum signature schemes. We discuss the security of our protocol. (paper)

  17. Food Insecurity and Chronic Disease123

    Science.gov (United States)

    Laraia, Barbara A.

    2013-01-01

    Household food insecurity has been previously hypothesized to promote dependence on inexpensive, highly palatable foods that are energy dense. Such dependence, and the cyclical nature of having enough food in the beginning of the month followed by food scarcity at the end of the month, could lead to weight gain over a short period of time. Such dependence on energy-dense foods and weight gain may play a direct role in the development of chronic conditions. Other compounding factors that result from exposure to household food insecurity have been well described, including pathways by which stress promotes visceral fat accumulation and chronic disease. This symposium review paper summarizes the literature on the link between food insecurity and the following: 1) diet, 2) weight gain, and 3) chronic disease, especially among women. This paper also proposes a framework for considering how the lived experience of household food insecurity may potentiate the development of chronic disease by activating the stress response among individuals at critical developmental periods in a food-impoverished environment. PMID:23493536

  18. Employment insecurity and employees' health in Denmark.

    Science.gov (United States)

    Cottini, Elena; Ghinetti, Paolo

    2018-02-01

    We use register data for Denmark (IDA) merged with the Danish Work Environment Cohort Survey (1995, 2000, and 2005) to estimate the effect of perceived employment insecurity on perceived health for a sample of Danish employees. We consider two health measures from the SF-36 Health Survey Instrument: a vitality scale for general well-being and a mental health scale. We first analyse a summary measure of employment insecurity. Instrumental variables-fixed effects estimates that use firm workforce changes as a source of exogenous variation show that 1 additional dimension of insecurity causes a shift from the median to the 25th percentile in the mental health scale and to the 30th in that of energy/vitality. It also increases by about 6 percentage points the probability to develop severe mental health problems. Looking at single insecurity dimensions by naïve fixed effects, uncertainty associated with the current job is important for mental health. Employability has a sizeable relationship with health and is the only insecurity dimension that matters for the energy and vitality scale. Danish employees who fear involuntary firm internal mobility experience worse mental health. Copyright © 2017 John Wiley & Sons, Ltd.

  19. The capacity of black holes to transmit quantum information

    International Nuclear Information System (INIS)

    Brádler, Kamil; Adami, Christoph

    2014-01-01

    We study the properties of the quantum information transmission channel that emerges from the quantum dynamics of particles interacting with a black hole horizon. We calculate the quantum channel capacity in two limiting cases where a single-letter capacity is known to exist: the limit of perfectly reflecting and perfectly absorbing black holes. We find that the perfectly reflecting black hole channel is closely related to the Unruh channel and that its capacity is non-vanishing, allowing for the perfect reconstruction of quantum information outside of the black hole horizon. We also find that the complementary channel (transmitting entanglement behind the horizon) is entanglement-breaking in this case, with vanishing capacity. We then calculate the quantum capacity of the black hole channel in the limit of a perfectly absorbing black hole and find that this capacity vanishes, while the capacity of the complementary channel is non-vanishing instead. Rather than inviting a new crisis for quantum physics, this finding instead is in accordance with the quantum no-cloning theorem, because it guarantees that there are no space-like surfaces that contain both the sender’s quantum state and the receiver’s reconstructed quantum state

  20. The capacity of black holes to transmit quantum information

    Energy Technology Data Exchange (ETDEWEB)

    Brádler, Kamil [Department of Astronomy and Physics, Saint Mary’s University,Halifax, Nova Scotia, B3H 3C3 (Canada); Adami, Christoph [Department of Physics and Astronomy, Michigan State University,East Lansing, MI 48824 (United States)

    2014-05-21

    We study the properties of the quantum information transmission channel that emerges from the quantum dynamics of particles interacting with a black hole horizon. We calculate the quantum channel capacity in two limiting cases where a single-letter capacity is known to exist: the limit of perfectly reflecting and perfectly absorbing black holes. We find that the perfectly reflecting black hole channel is closely related to the Unruh channel and that its capacity is non-vanishing, allowing for the perfect reconstruction of quantum information outside of the black hole horizon. We also find that the complementary channel (transmitting entanglement behind the horizon) is entanglement-breaking in this case, with vanishing capacity. We then calculate the quantum capacity of the black hole channel in the limit of a perfectly absorbing black hole and find that this capacity vanishes, while the capacity of the complementary channel is non-vanishing instead. Rather than inviting a new crisis for quantum physics, this finding instead is in accordance with the quantum no-cloning theorem, because it guarantees that there are no space-like surfaces that contain both the sender’s quantum state and the receiver’s reconstructed quantum state.

  1. Quantum hacking of two-way continuous-variable quantum key distribution using Trojan-horse attack

    International Nuclear Information System (INIS)

    Ma Hong-Xin; Bao Wan-Su; Li Hong-Wei; Chou Chun

    2016-01-01

    We present a Trojan-horse attack on the practical two-way continuous-variable quantum key distribution system. Our attack mainly focuses on the imperfection of the practical system that the modulator has a redundancy of modulation pulse-width, which leaves a loophole for the eavesdropper inserting a Trojan-horse pulse. Utilizing the unique characteristics of two-way continuous-variable quantum key distribution that Alice only takes modulation operation on the received mode without any measurement, this attack allows the eavesdropper to render all of the final keys shared between the legitimate parties insecure without being detected. After analyzing the feasibility of the attack, the corresponding countermeasures are put forward. (paper)

  2. U.S. Food Insecurity Status: Toward a Refined Definition

    Science.gov (United States)

    Coleman-Jensen, Alisha Judith

    2010-01-01

    United States Department of Agriculture defines food insecure as answering affirmatively to three or more food insecurity questions describing a household's ability to acquire enough food. Households indicating low levels of food insecurity (one or two affirmative responses) are considered food secure. This paper compares the characteristics of…

  3. Asymmetric quantum cloning machines

    International Nuclear Information System (INIS)

    Cerf, N.J.

    1998-01-01

    A family of asymmetric cloning machines for quantum bits and N-dimensional quantum states is introduced. These machines produce two approximate copies of a single quantum state that emerge from two distinct channels. In particular, an asymmetric Pauli cloning machine is defined that makes two imperfect copies of a quantum bit, while the overall input-to-output operation for each copy is a Pauli channel. A no-cloning inequality is derived, characterizing the impossibility of copying imposed by quantum mechanics. If p and p ' are the probabilities of the depolarizing channels associated with the two outputs, the domain in (√p,√p ' )-space located inside a particular ellipse representing close-to-perfect cloning is forbidden. This ellipse tends to a circle when copying an N-dimensional state with N→∞, which has a simple semi-classical interpretation. The symmetric Pauli cloning machines are then used to provide an upper bound on the quantum capacity of the Pauli channel of probabilities p x , p y and p z . The capacity is proven to be vanishing if (√p x , √p y , √p z ) lies outside an ellipsoid whose pole coincides with the depolarizing channel that underlies the universal cloning machine. Finally, the tradeoff between the quality of the two copies is shown to result from a complementarity akin to Heisenberg uncertainty principle. (author)

  4. Laser damage helps the eavesdropper in quantum cryptography.

    Science.gov (United States)

    Bugge, Audun Nystad; Sauge, Sebastien; Ghazali, Aina Mardhiyah M; Skaar, Johannes; Lydersen, Lars; Makarov, Vadim

    2014-02-21

    We propose a class of attacks on quantum key distribution (QKD) systems where an eavesdropper actively engineers new loopholes by using damaging laser illumination to permanently change properties of system components. This can turn a perfect QKD system into a completely insecure system. A proof-of-principle experiment performed on an avalanche photodiode-based detector shows that laser damage can be used to create loopholes. After ∼1  W illumination, the detectors' dark count rate reduces 2-5 times, permanently improving single-photon counting performance. After ∼1.5  W, the detectors switch permanently into the linear photodetection mode and become completely insecure for QKD applications.

  5. Insecurity and national economic development implications for ...

    African Journals Online (AJOL)

    Insecurity and national economic development implications for Nigeria's vision 20: 2020. ... International Journal of Development and Management Review ... These social menace trigger off a worrisome sense of insecurity that challenge Nigeria's efforts towards national economic development and consequently its vision ...

  6. Algorithmic complexity of quantum capacity

    Science.gov (United States)

    Oskouei, Samad Khabbazi; Mancini, Stefano

    2018-04-01

    We analyze the notion of quantum capacity from the perspective of algorithmic (descriptive) complexity. To this end, we resort to the concept of semi-computability in order to describe quantum states and quantum channel maps. We introduce algorithmic entropies (like algorithmic quantum coherent information) and derive relevant properties for them. Then we show that quantum capacity based on semi-computable concept equals the entropy rate of algorithmic coherent information, which in turn equals the standard quantum capacity. Thanks to this, we finally prove that the quantum capacity, for a given semi-computable channel, is limit computable.

  7. A model of quantum communication device for quantum hashing

    International Nuclear Information System (INIS)

    Vasiliev, A

    2016-01-01

    In this paper we consider a model of quantum communications between classical computers aided with quantum processors, connected by a classical and a quantum channel. This type of communications implying both classical and quantum messages with moderate use of quantum processing is implicitly used in many quantum protocols, such as quantum key distribution or quantum digital signature. We show that using the model of a quantum processor on multiatomic ensembles in the common QED cavity we can speed up quantum hashing, which can be the basis of quantum digital signature and other communication protocols. (paper)

  8. Predictors and consequences of job insecurity: Comparison of Slovakia and Estonia

    Directory of Open Access Journals (Sweden)

    Lucia Ištoňová

    2016-03-01

    Full Text Available Job insecurity is a significant current social issue in many European countries. Slovakia and Estonia significantly differ in the prevalence of job insecurity. The main aim of the present study was to compare Slovakia and Estonia in regard to job insecurity by looking at socio-demographic, job and organisational predictors and individual and social consequences based on ESS round five data. The secondary aim was to examine relationships between job insecurity and its predictors as well as job insecurity and its consequences. The analysis covered employed people with unlimited or limited contracts, working 40-50 hours per week, within the age range of 20-60. The results suggested significant differences in the predictors of job insecurity for Slovakia and Estonia. However, the individual, social and economic consequences of job insecurity were similar for both countries. This study contributes to an enhanced understanding of job insecurity predictors and consequences in the European region.

  9. Insecure attachment and anxiety in student athletes.

    Science.gov (United States)

    Han, D H; Kim, S M; Zaichkowsky, L

    2013-06-01

    The main purpose of our research was to examine attachment type and competition anxiety in high school student athletes and general high school students. We recruited 465 student athletes and 543 general students to participate in our study. The Revised Korean version of the Experiences in Close Relationships Scale (K-ECRS) and the Competitive State Anxiety Inventory-2 (CSAI-2) were given to all students. In χ2 tests, athletes showed attachment types in the following order of prevalence: fearful, dismissive, and preoccupied, compared to the fearful, preoccupied, and dismissive order observed in general students. In parametric, independent t-tests, athletes reported significantly higher cognitive anxiety scores, relative to general students. Further, athletes with insecure attachment compared to those with secure attachment reported higher cognitive anxiety scores and self-confidence scores. In both the athletes with insecure attachment and general students with insecure attachment groups, the K-ECRS anxiety subscale was significantly correlated with CSAI-2 total score. In post hoc analysis in the athletes with insecure attachment group, the K-ECRS anxiety subscale was also significantly correlated with the CSAI-2 cognitive anxiety subscale. These results suggest that anxious athletes with an insecure attachment style tend to exaggerate threats from both external and internal sources, which negatively affect their performances.

  10. Quantum reverse hypercontractivity

    Energy Technology Data Exchange (ETDEWEB)

    Cubitt, Toby [Department of Computer Science, University College London, London, United Kingdom and Centre for Quantum Information and Foundations, DAMTP, University of Cambridge, Cambridge (United Kingdom); Kastoryano, Michael [NBIA, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen (Denmark); Montanaro, Ashley [School of Mathematics, University of Bristol, Bristol (United Kingdom); Temme, Kristan [Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125 (United States)

    2015-10-15

    We develop reverse versions of hypercontractive inequalities for quantum channels. By generalizing classical techniques, we prove a reverse hypercontractive inequality for tensor products of qubit depolarizing channels. We apply this to obtain a rapid mixing result for depolarizing noise applied to large subspaces and to prove bounds on a quantum generalization of non-interactive correlation distillation.

  11. Practical quantum digital signature

    Science.gov (United States)

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

    2016-03-01

    Guaranteeing nonrepudiation, unforgeability as well as transferability of a signature is one of the most vital safeguards in today's e-commerce era. Based on fundamental laws of quantum physics, quantum digital signature (QDS) aims to provide information-theoretic security for this cryptographic task. However, up to date, the previously proposed QDS protocols are impractical due to various challenging problems and most importantly, the requirement of authenticated (secure) quantum channels between participants. Here, we present the first quantum digital signature protocol that removes the assumption of authenticated quantum channels while remaining secure against the collective attacks. Besides, our QDS protocol can be practically implemented over more than 100 km under current mature technology as used in quantum key distribution.

  12. Prosocial Behavior and Subjective Insecurity in Violent Contexts: Field Experiments

    OpenAIRE

    V?lez, Mar?a Alejandra; Trujillo, Carlos Andres; Moros, Lina; Forero, Clemente

    2016-01-01

    Subjective insecurity is a key determinant of different forms of prosocial behavior. In Study 1, we used field experiments with farmers in Colombian villages exposed to different levels of violence to investigate how individual perceptions of insecurity affect cooperation, trust, reciprocity and altruism. To do so, we developed a cognitive-affective measure of subjective insecurity. We found that subjective insecurity has a negative effect on cooperation but influences trust and altruism posi...

  13. Household capacities, vulnerabilities and food insecurity: Shifts in food insecurity in urban and rural Ethiopia during the 2008 food crisis

    Science.gov (United States)

    Hadley, Craig; Linzer, Drew A.; Belachew, Tefera; Mariam, Abebe Gebre; Tessema, Fasil; Lindstrom, David

    2014-01-01

    The global food crisis of 2008 led to renewed interest in global food insecurity and how macro-level food prices impact household and individual level wellbeing. There is debate over the extent to which food price increases in 2008 eroded food security, the extent to which this effect was distributed across rural and urban locales, and the extent to which rural farmers might have benefited. Ethiopia’s food prices increased particularly dramatically between 2005 and 2008 and here we ask whether there was a concomitant increase in household food insecurity, whether this decline was distributed equally across rural, urban, and semi-urban locales, and to what extent pre-crisis household capacities and vulnerabilities impacted 2008 household food insecurity levels. Data are drawn from a random sample of 2610 households in Southwest Ethiopia surveyed 2005/6 and again in mid to late 2008. Results show broad deterioration of household food insecurity relative to baseline but declines were most pronounced in the rural areas. Wealthier households and those that were relatively more food secure in 2005/6 tended to be more food secure in 2008, net of other factors, and these effects were most pronounced in urban areas. External shocks, such as a job loss or loss of crops, experienced by households were also associated with worse food insecurity in 2008 but few other household variables were associated with 2008 food insecurity. Our results also showed that rural farmers tended to produce small amounts for sale on markets, and thus were not able to enjoy the potential benefits that come from greater crop prices. We conclude that poverty, and not urban/rural difference, is the important variable for understanding the risk of food insecurity during a food crisis and that many rural farmers are too poor to take advantage of rapid rises in food prices. PMID:21996022

  14. Household capacities, vulnerabilities and food insecurity: shifts in food insecurity in urban and rural Ethiopia during the 2008 food crisis.

    Science.gov (United States)

    Hadley, Craig; Linzer, Drew A; Belachew, Tefera; Mariam, Abebe Gebre; Tessema, Fasil; Lindstrom, David

    2011-11-01

    The global food crisis of 2008 led to renewed interest in global food insecurity and how macro-level food prices impact household and individual level wellbeing. There is debate over the extent to which food price increases in 2008 eroded food security, the extent to which this effect was distributed across rural and urban locales, and the extent to which rural farmers might have benefited. Ethiopia's food prices increased particularly dramatically between 2005 and 2008 and here we ask whether there was a concomitant increase in household food insecurity, whether this decline was distributed equally across rural, urban, and semi-urban locales, and to what extent pre-crisis household capacities and vulnerabilities impacted 2008 household food insecurity levels. Data are drawn from a random sample of 2610 households in Southwest Ethiopia surveyed 2005/6 and again in mid to late 2008. Results show broad deterioration of household food insecurity relative to baseline but declines were most pronounced in the rural areas. Wealthier households and those that were relatively more food secure in 2005/6 tended to be more food secure in 2008, net of other factors, and these effects were most pronounced in urban areas. External shocks, such as a job loss or loss of crops, experienced by households were also associated with worse food insecurity in 2008 but few other household variables were associated with 2008 food insecurity. Our results also showed that rural farmers tended to produce small amounts for sale on markets, and thus were not able to enjoy the potential benefits that come from greater crop prices. We conclude that poverty, and not urban/rural difference, is the important variable for understanding the risk of food insecurity during a food crisis and that many rural farmers are too poor to take advantage of rapid rises in food prices. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Economic Insecurity and Intimate Partner and Sexual Violence Victimization.

    Science.gov (United States)

    Breiding, Matthew J; Basile, Kathleen C; Klevens, Joanne; Smith, Sharon G

    2017-10-01

    Previous research has consistently found that low SES is associated with higher levels of both intimate partner violence (IPV) and sexual violence (SV) victimization. Though associated with poverty, two indicators of economic insecurity, food and housing insecurity, have been identified as conceptually distinct social determinants of health. This study examined the relationship between food and housing insecurity experienced in the preceding 12 months and IPV and SV victimization experienced in the preceding 12 months, after controlling for SES and other demographic variables. Data were from the 2010 National Intimate Partner and Sexual Violence Survey, a nationally representative telephone survey of U.S. adults. In 2016, multivariate logistic regression modeling was used to examine the association between food and housing insecurity and multiple forms of IPV and SV victimization. Robust associations were found between food and housing insecurity experienced in the preceding 12 months and IPV and SV experienced in the preceding 12 months, for women and men, even after controlling for age, family income, race/ethnicity, education, and marital status. Food and housing insecurity may be important considerations for the prevention of SV and IPV or the reductions of their consequences, although future research is needed to disentangle the direction of the association. Strategies aimed at buffering economic insecurity may reduce vulnerability to IPV and SV victimization. Copyright © 2017. Published by Elsevier Inc.

  16. All-photonic quantum repeaters

    Science.gov (United States)

    Azuma, Koji; Tamaki, Kiyoshi; Lo, Hoi-Kwong

    2015-01-01

    Quantum communication holds promise for unconditionally secure transmission of secret messages and faithful transfer of unknown quantum states. Photons appear to be the medium of choice for quantum communication. Owing to photon losses, robust quantum communication over long lossy channels requires quantum repeaters. It is widely believed that a necessary and highly demanding requirement for quantum repeaters is the existence of matter quantum memories. Here we show that such a requirement is, in fact, unnecessary by introducing the concept of all-photonic quantum repeaters based on flying qubits. In particular, we present a protocol based on photonic cluster-state machine guns and a loss-tolerant measurement equipped with local high-speed active feedforwards. We show that, with such all-photonic quantum repeaters, the communication efficiency scales polynomially with the channel distance. Our result paves a new route towards quantum repeaters with efficient single-photon sources rather than matter quantum memories. PMID:25873153

  17. Food insecurity, depression, and social support in HIV-infected Hispanic individuals.

    Science.gov (United States)

    Kapulsky, Leonid; Tang, Alice M; Forrester, Janet E

    2015-04-01

    Previous research has identified an association between food insecurity and depression in a variety of world regions in both healthy and HIV-infected individuals. We examined this association in 183 HIV-infected Hispanic adults from the greater Boston area. We measured depression with the Burnam depression screen and food insecurity with the Radimer/Cornell Questionnaire. Dietary intake was assessed with an adapted version of the Block Food Frequency Questionnaire. Logistic regression models were created with depression as the outcome variable and food insecurity as the main predictor. In bivariate analyses, food insecurity was significantly associated with depression [odds ratio (OR) 2.5; 95% confidence interval (CI) 1.1, 5.5; p = 0.03]. When we accounted for social support, food insecurity was no longer significant. We found no differences in the quality or quantity of dietary intake between the food insecure and food secure groups. Our findings highlight the importance of social support in the association between food insecurity and depression. Food insecurity may reflect social support more than actual dietary intake in this population.

  18. Seasonal prevalence and determinants of food insecurity in Iqaluit, Nunavut

    Directory of Open Access Journals (Sweden)

    Yang Guo

    2015-08-01

    Full Text Available Background: Food insecurity is an ongoing problem in the Canadian Arctic. Although most studies have focused on smaller communities, little is known about food insecurity in larger centres. Objectives: This study aimed to estimate the prevalence of food insecurity during 2 different seasons in Iqaluit, the territorial capital of Nunavut, as well as identify associated risk factors. Designs: A modified United States Department of Agriculture Food Security Survey was applied to 532 randomly selected households in September 2012 and 523 in May 2013. Chi-square tests and multivariable logistic regression were used to examine potential associations between food security and 9 risk factors identified in the literature. Results: In September 2012, 28.7% of surveyed households in Iqaluit were food insecure, a rate 3 times higher than the national average, but lower than smaller Inuit communities in Nunavut. Prevalence of food insecurity in September 2012 was not significantly different in May 2013 (27.2%. When aggregating results from Inuit households from both seasons (May and September, food insecurity was associated with poor quality housing and reliance on income support (p<0.01. Unemployment and younger age of the person in charge of food preparation were also significantly associated with food insecurity. In contrast to previous research among Arctic communities, gender and consumption of country food were not positively associated with food security. These results are consistent with research describing high food insecurity across the Canadian Arctic. Conclusion: The factors associated with food insecurity in Iqaluit differed from those identified in smaller communities, suggesting that experiences with, and processes of, food insecurity may differ between small communities and larger commercial centres. These results suggest that country food consumption, traditional knowledge and sharing networks may play a less important role in larger Inuit

  19. Questionnaire-based Prevalence of Food Insecurity in Iran: A Review Article.

    Science.gov (United States)

    Daneshi-Maskooni, Milad; Shab-Bidar, Sakineh; Badri-Fariman, Mahtab; Aubi, Erfan; Mohammadi, Younes; Jafarnejad, Sadegh; Djafarian, Kurosh

    2017-11-01

    Data on the questionnaire-based prevalence of food insecurity are needed to develop food and nutrition security studies and policies. The present study aimed to assess the questionnaire-based prevalence of food insecurity in Iran. A systematic search of cross-sectional studies were conducted on databases including PubMed, Google Scholar, Scopus, Magiran, Iranmedex, SID and Medlib up to 29 Oct 2015. Estimation of food insecurity prevalence was according to the instruments including 9-items-HFIAS, 18 and 6-items USDA (US-HFSSM) and Radimer/Cernel food security questionnaires. Pooled effect was estimated using random-effect model and heterogeneity was assessed by Cochran's Q and I 2 tests. Thirteen articles included in the study based on screening and assessment of eligibility. The questionnaire-based prevalence of food insecurity was 49.2% (CI95%: 43.8-54.6). The according to sub-groups analysis, the food insecurity without and with hunger was 29.6% (CI95%: 25.7-33.6) and 19.2% (CI95%: 16-22.3), respectively. The about half of the population were food insecure. The food insecurity without hunger was more than the food insecurity with hunger. An ongoing food insecurity assessment system is needed to support evidence-informed policy and to plan interventions to increase the food security in different areas.

  20. Preparation of freezing quantum state for quantum coherence

    Science.gov (United States)

    Yang, Lian-Wu; Man, Zhong-Xiao; Zhang, Ying-Jie; Han, Feng; Du, Shao-jiang; Xia, Yun-Jie

    2018-06-01

    We provide a method to prepare the freezing quantum state for quantum coherence via unitary operations. The initial product state consists of the control qubit and target qubit; when it satisfies certain conditions, the initial product state converts into the particular Bell diagonal state under the unitary operations, which have the property of freezing of quantum coherence under quantum channels. We calculate the frozen quantum coherence and corresponding quantum correlations, and find that the quantities are determined by the control qubit only when the freezing phenomena occur.

  1. One way quantum repeaters with quantum Reed-Solomon codes

    OpenAIRE

    Muralidharan, Sreraman; Zou, Chang-Ling; Li, Linshu; Jiang, Liang

    2018-01-01

    We show that quantum Reed-Solomon codes constructed from classical Reed-Solomon codes can approach the capacity on the quantum erasure channel of $d$-level systems for large dimension $d$. We study the performance of one-way quantum repeaters with these codes and obtain a significant improvement in key generation rate compared to previously investigated encoding schemes with quantum parity codes and quantum polynomial codes. We also compare the three generation of quantum repeaters using quan...

  2. Job Insecurity and Innovative Work Behaviour: A Psychological Contract Perspective

    Directory of Open Access Journals (Sweden)

    Wendy Niesen

    2018-01-01

    Full Text Available Innovation is considered to be of crucial importance for organisational survival and growth, and in this respect employees play a leading role, as they are the ones who develop innovative ideas. At the same time, the struggle for organisational survival and growth gives rise to perceptions of job insecurity. To date, few studies have explored how employees’ innovative work behaviour (IWB is influenced by the perceived threat of job loss (i.e. job insecurity. As both job insecurity and IWB are increasingly salient in light of organisational change and competition, the present study examines the relationship between job insecurity and IWB, as well as the role of psychological contract breach in explaining this relationship. We hypothesized a negative relation between job insecurity and innovative work behaviour, with psychological contract breach as a mediator in this relationship. Participants were 190 employees from an industrial organisation that had faced restructuring and downsizing for several years. Contrary to our predictions, no direct association was found between job insecurity and the two sub-dimensions of innovative work behaviour (i.e., idea generation and idea implementation. Indirect relationships, however, were found between job insecurity and the two types of IWB through psychological contract breach. Surprisingly, psychological contract breach was positively related to idea generation and idea implementation. These findings shed new light on the relationship between job insecurity and IWB.

  3. Food insecurity and malnutrition in Chinese elementary school students.

    Science.gov (United States)

    Shen, Xiuhua; Gao, Xiang; Tang, Wenjing; Mao, Xuanxia; Huang, Jingyan; Cai, Wei

    2015-09-28

    It has been shown that food insecurity is associated with poor diet quality and unfavourable health outcomes. However, little is known about the potential effects of food insecurity on the overall malnutrition status among children. In this study, we investigated the prevalence of food insecurity among 1583 elementary school students, aged 6-14 years, living in Chinese rural areas and examined its association with four malnutrition signs, including rickets sequelae, anaemia, stunting and wasting. Information on food security was collected via questionnaires. Rickets sequelae were assessed by an experienced paediatrician during the interview. Anaemia was determined by the WHO Hb thresholds adjusted by the local altitude. Weight and height were measured during the interview. Stunting and wasting were then evaluated according to WHO child growth standards (2007). We examined the association between food insecurity and the number of malnutrition signs (total number = 4), and the likelihood of having severe malnutrition (presence of 3+ signs), after adjusting for potential confounders, such as age, social-economic status and dietary intakes. During the previous 12 months, the overall prevalence of food insecurity was 6.1% in the entire studied population and 16.3% in participants with severe malnutrition. Participants with food insecurity had a slightly higher number of malnutrition signs (1.14 v. 0.96; P=0.043) relative to those who were food secure, after adjusting for potential confounders. Food insecurity was also associated with increased likelihood of having severe malnutrition (adjusted OR 3.08; 95% CI 1.47, 6.46; P=0.003). In conclusion, food insecurity is significantly associated with malnutrition among Chinese children in this community.

  4. Food Insecurity and Vulnerability in Latin America and the Caribbean

    OpenAIRE

    Gordillo, Gustavo; Winters, Paul C.; Corral, Leonardo

    2000-01-01

    This paper examines how Latin American and Caribbean (LAC) nations have proceeded in addressing the issues of food insecurity and vulnerability in response to the 1996 Rome Declaration on World Food Security. The data suggests that while the food insecurity situation has improved in LAC over the past few years, many nations are worse off in terms of food insecurity than they were at the beginning of the 1990s. Nations that reduced food insecurity tend to be those who have effectively reduced ...

  5. Activation of zero-error classical capacity in low-dimensional quantum systems

    Science.gov (United States)

    Park, Jeonghoon; Heo, Jun

    2018-06-01

    Channel capacities of quantum channels can be nonadditive even if one of two quantum channels has no channel capacity. We call this phenomenon activation of the channel capacity. In this paper, we show that when we use a quantum channel on a qubit system, only a noiseless qubit channel can generate the activation of the zero-error classical capacity. In particular, we show that the zero-error classical capacity of two quantum channels on qubit systems cannot be activated. Furthermore, we present a class of examples showing the activation of the zero-error classical capacity in low-dimensional systems.

  6. Aspects of multistation quantum information broadcasting

    International Nuclear Information System (INIS)

    Demianowicz, Maciej; Horodecki, Pawel

    2010-01-01

    We study quantum information transmission over multiparty quantum channel. In particular, we show an equivalence of different capacity notions and provide a multiletter characterization of a capacity region for a general quantum channel with k senders and m receivers. We point out natural generalizations to the case of two-way classical communication capacity.

  7. Prosocial Behavior and Subjective Insecurity in Violent Contexts: Field Experiments

    Science.gov (United States)

    Vélez, María Alejandra; Trujillo, Carlos Andres; Moros, Lina; Forero, Clemente

    2016-01-01

    Subjective insecurity is a key determinant of different forms of prosocial behavior. In Study 1, we used field experiments with farmers in Colombian villages exposed to different levels of violence to investigate how individual perceptions of insecurity affect cooperation, trust, reciprocity and altruism. To do so, we developed a cognitive-affective measure of subjective insecurity. We found that subjective insecurity has a negative effect on cooperation but influences trust and altruism positively. In Study 2, carried out three years after Study 1, we repeated the initial design with additional measures of victimization. Our goal was to relate subjective insecurity with actual victimization. The findings of Study 2 support the initial results, and are robust and consistent for cooperative behavior and trust when including victimization as a mediator. Different indicators of victimization are positively correlated with subjective insecurity and an aggregate index of victimization has a negative effect on cooperation but exerts a positive influence on trust. PMID:27472437

  8. Prosocial Behavior and Subjective Insecurity in Violent Contexts: Field Experiments.

    Directory of Open Access Journals (Sweden)

    María Alejandra Vélez

    Full Text Available Subjective insecurity is a key determinant of different forms of prosocial behavior. In Study 1, we used field experiments with farmers in Colombian villages exposed to different levels of violence to investigate how individual perceptions of insecurity affect cooperation, trust, reciprocity and altruism. To do so, we developed a cognitive-affective measure of subjective insecurity. We found that subjective insecurity has a negative effect on cooperation but influences trust and altruism positively. In Study 2, carried out three years after Study 1, we repeated the initial design with additional measures of victimization. Our goal was to relate subjective insecurity with actual victimization. The findings of Study 2 support the initial results, and are robust and consistent for cooperative behavior and trust when including victimization as a mediator. Different indicators of victimization are positively correlated with subjective insecurity and an aggregate index of victimization has a negative effect on cooperation but exerts a positive influence on trust.

  9. Prosocial Behavior and Subjective Insecurity in Violent Contexts: Field Experiments.

    Science.gov (United States)

    Vélez, María Alejandra; Trujillo, Carlos Andres; Moros, Lina; Forero, Clemente

    2016-01-01

    Subjective insecurity is a key determinant of different forms of prosocial behavior. In Study 1, we used field experiments with farmers in Colombian villages exposed to different levels of violence to investigate how individual perceptions of insecurity affect cooperation, trust, reciprocity and altruism. To do so, we developed a cognitive-affective measure of subjective insecurity. We found that subjective insecurity has a negative effect on cooperation but influences trust and altruism positively. In Study 2, carried out three years after Study 1, we repeated the initial design with additional measures of victimization. Our goal was to relate subjective insecurity with actual victimization. The findings of Study 2 support the initial results, and are robust and consistent for cooperative behavior and trust when including victimization as a mediator. Different indicators of victimization are positively correlated with subjective insecurity and an aggregate index of victimization has a negative effect on cooperation but exerts a positive influence on trust.

  10. The dynamics of attachment insecurity and paranoid thoughts:An experience sampling study

    OpenAIRE

    Sitko, Katarzyna; Varese, Filippo; Sellwood, William; Hammond, Amy; Bentall, Richard

    2016-01-01

    It has been proposed that insecure attachment can have adverse effects on the course of psychosis once symptoms have emerged. There is longitudinal evidence that increased insecure attachment is associated with increased severity of psychotic symptoms. The present study examined whether in the flow of daily life attachment insecurity fluctuates, whether elevated stress precedes the occurrence of attachment insecurity, and whether elevated attachment insecurity precedes the occurrence of paran...

  11. The importance of career insecurity for turnover intentions in the Dutch military

    NARCIS (Netherlands)

    van Eetveldt, M.W.; van de Ven, N.; van den Tooren, M.; Versteeg, R.C.

    2013-01-01

    The effects of two dimensions of job insecurity (job loss insecurity and career insecurity) on turnover intentions were tested in a sample from the Dutch armed forces (N = 3,580) after a major downsizing operation was announced. Results suggested that especially perceptions of career insecurity

  12. Food Insecurity in Older Adults in an Integrated Health Care System.

    Science.gov (United States)

    Steiner, John F; Stenmark, Sandra H; Sterrett, Andrew T; Paolino, Andrea R; Stiefel, Matthew; Gozansky, Wendolyn S; Zeng, Chan

    2018-05-01

    To estimate food insecurity prevalence and develop a statistical prediction model for food insecurity. Retrospective cohort study. Kaiser Permanente Colorado. Adult members who completed a pre-Medicare Annual Wellness Visit survey. Food insecurity was assessed using a single screening question. Sociodemographic and clinical characteristics from electronic health records and self-reported characteristics from the survey were used to develop the prediction model. Of 130,208 older adult members between January 2012 and December 2015, 50,097 (38.5%) completed food insecurity screening, 2,859 of whom (5.7% of respondents) reported food insecurity. The prevalence of food insecurity was 10.0% or greater among individuals who were black or Hispanic, had less than high school education, had Medicaid insurance, were extremely obese, had poor health status or quality of life, had depression or anxiety, had impairments in specific activities of daily living, had other nutritional risk factors, or were socially isolated (all pinsecurity and those without and 14.3% of individuals in the highest quintile of risk reported food insecurity. Food insecurity is prevalent even in older adults with private-sector healthcare coverage. Specific individual characteristics, and a model based on those characteristics, can identify older adults at higher risk of food insecurity. System-level interventions will be necessary to connect older adults with community-based food resources. © 2018, Copyright the Authors Journal compilation © 2018, The American Geriatrics Society.

  13. Teleportations of Mixed States and Multipartite Quantum States

    Institute of Scientific and Technical Information of China (English)

    YU Chang-Shui; WANG Ya-Hong; SONG He-Shan

    2007-01-01

    In this paper, we propose a protocol to deterministically teleport an unknown mixed state of qubit by utilizing a maximally bipartite entangled state of qubits as quantum channel. Ifa non-maximally entangled bipartite pure state is employed as quantum channel, the unknown mixed quantum state of qubit can be teleported with 1 - √1 - C2 probability, where C is the concurrence of the quantum channel. The protocol can also be generalized to teleport a mixed state of qudit or a multipartite mixed state. More important purpose is that, on the basis of the protocol, the teleportation of an arbitrary multipartite (pure or mixed) quantum state can be decomposed into the teleportation of each subsystem by employing separate entangled states as quantum channels. In the case of deterministic teleportation,Bob only needs to perform unitary transformations on his single particles in order to recover the initial teleported multipartite quantum state.

  14. Relativistic quantum cryptography

    International Nuclear Information System (INIS)

    Molotkov, S. N.

    2011-01-01

    A new protocol of quantum key distribution is proposed to transmit keys through free space. Along with quantum-mechanical restrictions on the discernibility of nonorthogonal quantum states, the protocol uses additional restrictions imposed by special relativity theory. Unlike all existing quantum key distribution protocols, this protocol ensures key secrecy for a not strictly one-photon source of quantum states and an arbitrary length of a quantum communication channel.

  15. [Food insecurity is associated with obesity in adult women of Mexico].

    Science.gov (United States)

    Morales-Ruán, Ma Del Carmen; Méndez-Gómez Humarán, Ignacio; Shamah-Levy, Teresa; Valderrama-Álvarez, Zaira; Melgar-Quiñónez, Hugo

    2014-01-01

    To describe the association of food insecurity (FI) and obesity in adults in Mexico. Cross-sectional design. We included adults' data from the health and nutrition national survey 2012 (Ensanut 2012). Measures of weight and height were obtained and BMI was calculated. The level of household food insecurity was measured through the Latin American Scale of Food Security (ELCSA). Linear and logistic regression models were adjusted. 70.6% of the population had some level of food insecurity, 42.6% mild insecurity, 17.7% moderate insecurity and 10.3% severe insecurity. Adults with mild FI had higher probability of obesity (OR: 1.66; 95%CI 1.11-2.50). Women were slightly more likely to be obese (OR: 1.78; 95%CI 1.01-3.12). Mild FI is associated with obesity, particularly among women.

  16. One-way quantum repeaters with quantum Reed-Solomon codes

    Science.gov (United States)

    Muralidharan, Sreraman; Zou, Chang-Ling; Li, Linshu; Jiang, Liang

    2018-05-01

    We show that quantum Reed-Solomon codes constructed from classical Reed-Solomon codes can approach the capacity on the quantum erasure channel of d -level systems for large dimension d . We study the performance of one-way quantum repeaters with these codes and obtain a significant improvement in key generation rate compared to previously investigated encoding schemes with quantum parity codes and quantum polynomial codes. We also compare the three generations of quantum repeaters using quantum Reed-Solomon codes and identify parameter regimes where each generation performs the best.

  17. The relationship between job insecurity and burnout

    Directory of Open Access Journals (Sweden)

    N Tilakdharee

    2010-09-01

    Full Text Available Organisational survival has necessitated more flexible practices (short-term contracts and outsourcing and, the need for an effective workforce that is able to work continuously under immense pressure.  Whilst the former has raised feelings of job insecurity, the latter has resulted in burnout.  This study aims to assess levels of job insecurity and burnout amongst 87 employees in a training and development environment, relationships between these two key dimensions and the impact of biographical variables.  Data, collected using the Job Insecurity Questionnaire (JIQ and the Oldenburg Burnout Inventory (OLBI, reflects a significant relationship between these dimensions.  The study provides recommendations for reducing their catastrophic individual and organisational consequences.

  18. Comparative study of donor-induced quantum dots in Si nano-channels by single-electron transport characterization and Kelvin probe force microscopy

    International Nuclear Information System (INIS)

    Tyszka, K.; Moraru, D.; Samanta, A.; Mizuno, T.; Tabe, M.; Jabłoński, R.

    2015-01-01

    We comparatively study donor-induced quantum dots in Si nanoscale-channel transistors for a wide range of doping concentration by analysis of single-electron tunneling transport and surface potential measured by Kelvin probe force microscopy (KPFM). By correlating KPFM observations of donor-induced potential landscapes with simulations based on Thomas-Fermi approximation, it is demonstrated that single-electron tunneling transport at lowest gate voltages (for smallest coverage of screening electrons) is governed most frequently by only one dominant quantum dot, regardless of doping concentration. Doping concentration, however, primarily affects the internal structure of the quantum dot. At low concentrations, individual donors form most of the quantum dots, i.e., “donor-atom” quantum dots. In contrast, at high concentrations above metal-insulator transition, closely placed donors instead of individual donors form more complex quantum dots, i.e., “donor-cluster” quantum dots. The potential depth of these “donor-cluster” quantum dots is significantly reduced by increasing gate voltage (increasing coverage of screening electrons), leading to the occurrence of multiple competing quantum dots

  19. The Impact of Job Insecurity on Marital and Family Relationships.

    Science.gov (United States)

    Larson, Jeffry H.; And Others

    1994-01-01

    Examined relationship between perceived stress resulting from job insecurity and marital and family functioning. Data from 111 married couples in which at least 1 spouse was working in insecure job environment showed that job insecurity stress was related in systematic way to marital and family dysfunction and number of family problems reported.…

  20. Quantum teleportation of propagating quantum microwaves

    Energy Technology Data Exchange (ETDEWEB)

    Di Candia, R.; Felicetti, S.; Sanz, M. [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); Fedorov, K.G.; Menzel, E.P. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Technische Universitaet Muenchen, Physik-Department, Garching (Germany); Zhong, L.; Deppe, F.; Gross, R. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Technische Universitaet Muenchen, Physik-Department, Garching (Germany); Nanosystems Initiative Munich (NIM), Muenchen (Germany); Marx, A. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Solano, E. [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); Basque Foundation for Science, IKERBASQUE, Bilbao (Spain)

    2015-12-15

    Propagating quantum microwaves have been proposed and successfully implemented to generate entanglement, thereby establishing a promising platform for the realisation of a quantum communication channel. However, the implementation of quantum teleportation with photons in the microwave regime is still absent. At the same time, recent developments in the field show that this key protocol could be feasible with current technology, which would pave the way to boost the field of microwave quantum communication. Here, we discuss the feasibility of a possible implementation of microwave quantum teleportation in a realistic scenario with losses. Furthermore, we propose how to implement quantum repeaters in the microwave regime without using photodetection, a key prerequisite to achieve long distance entanglement distribution. (orig.)

  1. Quantum teleportation of propagating quantum microwaves

    International Nuclear Information System (INIS)

    Di Candia, R.; Felicetti, S.; Sanz, M.; Fedorov, K.G.; Menzel, E.P.; Zhong, L.; Deppe, F.; Gross, R.; Marx, A.; Solano, E.

    2015-01-01

    Propagating quantum microwaves have been proposed and successfully implemented to generate entanglement, thereby establishing a promising platform for the realisation of a quantum communication channel. However, the implementation of quantum teleportation with photons in the microwave regime is still absent. At the same time, recent developments in the field show that this key protocol could be feasible with current technology, which would pave the way to boost the field of microwave quantum communication. Here, we discuss the feasibility of a possible implementation of microwave quantum teleportation in a realistic scenario with losses. Furthermore, we propose how to implement quantum repeaters in the microwave regime without using photodetection, a key prerequisite to achieve long distance entanglement distribution. (orig.)

  2. Attachment insecurity and perceived importance of relational features

    NARCIS (Netherlands)

    Ren, D.; Arriaga, X.B.; Mahan, E.R.

    2017-01-01

    Chronic attachment insecurity can affect the outlook people have on relationships. This research examines how attachment insecurity relates to perceived importance of various features in a romantic relationship (e.g., intimacy, independence). Consistent with predictions, the results from Studies 1–3

  3. Food Insecurity, Self-Rated Health, and Obesity among College Students

    Science.gov (United States)

    Knol, Linda L.; Robb, Cliff A.; McKinley, Erin M.; Wood, Mary

    2017-01-01

    Background: The prevalence of food insecurity among college students ranges from 14% to 59%. Most of the research to date has examined the determinants of food insecurity. Purpose: The purpose of this study was to examine the relationships between food insecurity and self-rated health and obesity among college students living off campus. Methods:…

  4. A cross-country analysis of climate shocks and smallholder food insecurity.

    Science.gov (United States)

    Niles, Meredith T; Salerno, Jonathan D

    2018-01-01

    Future climate changes will affect smallholder farmers in the developing world, posing threats to household food security. Nevertheless, there remains limited comparable evidence across multiple countries and regions regarding the global extent of climate shocks affecting smallholder food security. We examine data from 5,299 household surveys across 15 countries in Latin America, Africa and South Asia to assess the extent of climate shocks and their association with food insecurity, as well as what strategies may help buffer against climate shocks. We find that 71% of households reported experiencing a climate shock in the previous five years. Fifty-four percent reported experiencing food insecurity during one or more months annually. A multilevel statistical model estimated factors correlated with food insecurity as well as factors correlated with food insecurity among households that had experienced a climate shock. Households that reported experiencing a climate shock were 1.73 times more likely to be food insecure. As well, larger and poorer households were associated with higher odds of food insecurity while using pesticides, keeping large livestock, and being more educated are associated with lower odds of food insecurity. Among households that had experienced a climate shock, additional factors are correlated with lower odds of food insecurity when compared to otherwise similar households: use of fertilizers, pesticides, veterinary medicines, large livestock, and household assets. Together, these results demonstrate the extent of existing climate shocks affecting smallholder farmers and how interventions may potentially support adaptation and reduce food insecurity.

  5. A cross-country analysis of climate shocks and smallholder food insecurity.

    Directory of Open Access Journals (Sweden)

    Meredith T Niles

    Full Text Available Future climate changes will affect smallholder farmers in the developing world, posing threats to household food security. Nevertheless, there remains limited comparable evidence across multiple countries and regions regarding the global extent of climate shocks affecting smallholder food security. We examine data from 5,299 household surveys across 15 countries in Latin America, Africa and South Asia to assess the extent of climate shocks and their association with food insecurity, as well as what strategies may help buffer against climate shocks. We find that 71% of households reported experiencing a climate shock in the previous five years. Fifty-four percent reported experiencing food insecurity during one or more months annually. A multilevel statistical model estimated factors correlated with food insecurity as well as factors correlated with food insecurity among households that had experienced a climate shock. Households that reported experiencing a climate shock were 1.73 times more likely to be food insecure. As well, larger and poorer households were associated with higher odds of food insecurity while using pesticides, keeping large livestock, and being more educated are associated with lower odds of food insecurity. Among households that had experienced a climate shock, additional factors are correlated with lower odds of food insecurity when compared to otherwise similar households: use of fertilizers, pesticides, veterinary medicines, large livestock, and household assets. Together, these results demonstrate the extent of existing climate shocks affecting smallholder farmers and how interventions may potentially support adaptation and reduce food insecurity.

  6. Job insecurity and risk of diabetes

    DEFF Research Database (Denmark)

    Ferrie, Jane E.; Virtanen, Marianna; Jokela, Markus

    2016-01-01

    participating in the Individual-Participant-Data Meta-analysis in Working Populations Consortium. We calculated study-specific estimates of the association between job insecurity reported at baseline and incident diabetes over the follow-up period. We pooled the estimates in a meta-analysis to produce a summary...... risk estimate. Results: The 19 studies involved 140 825 participants from Australia, Europe and the United States, with a mean follow-up of 9.4 years and 3954 incident cases of diabetes. In the preliminary analysis adjusted for age and sex, high job insecurity was associated with an increased risk...... of incident diabetes compared with low job insecurity (adjusted odds ratio [OR] 1.19, 95% confidence interval [CI] 1.09–1.30). In the multivariable-adjusted analysis restricted to 15 studies with baseline data for all covariates (age, sex, socioeconomic status, obesity, physical activity, alcohol and smoking...

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

    Science.gov (United States)

    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.

  8. RBS cross-section of MeV ions channeling in crystals from quantum theory

    International Nuclear Information System (INIS)

    Den Besten, J.L.; Jamieson, D.N.; Spizzirri, P.G.; Allen, L.J.

    1999-01-01

    We present an alternative approach to describing Rutherford Backscattered (RBS) angular yield scans. The Bloch wave method to formulate the cross-section is a fundamental approach originating from Schrodinger's equation. This quantum formulation is often used when describing various aspects of electron diffraction including Backscattering, EDX and TEM but has seen little application to the very short wavelength regime of MeV ions. It offers several significant advantages. Great freedom is given to crystal properties and structure in the theory allowing a fundamental insight into the channeling phenomena and hence the crystal itself. We have calculated both planar and axial channeling scans and these maps are shown to be in good agreement to their experimental counterparts. There is excellent correlation between the theoretical and experimental results for both χ min and Ψ 1/2 . Further investigation is required into the area of absorption or dechanneling. This phenomenon requires different mechanisms for electron and ion scattering differ greatly

  9. An application of dichotomous and polytomous Rasch models for scoring energy insecurity

    International Nuclear Information System (INIS)

    Murray, Anthony G.; Mills, Bradford F.

    2012-01-01

    Household food security in the United States has been extensively researched and a number of indexes have been generated. However, household energy security has been largely ignored even though low-income households spend almost equal income shares on food and energy. This paper uses Rasch models and household responses to energy security questions in the 2005 Residential Energy Consumption Survey to generate an energy insecurity index that is consistent with those found in the food insecurity literature. The analysis yields several important findings for the generation of policy relevant household energy insecurity indexes. Questions that indicate reduction of basic expenditures, such as food, clothing, and shelter, are easiest for households to affirm implying low exposure to energy insecurity. Conversely, questions that concern households leaving the residence due to extreme temperatures consistently imply high exposure to energy insecurity. Households that score in the top decile of the energy insecurity index are more likely to be headed by single-females, be younger, and have a Black household head. Rasch models also identify flaws within survey. Particularly, the scope of the questions is quite broad and a refinement of the survey questions to focus on specific attributes of energy insecurity would likely improve future energy security indexes. - Highlights: ► A novel household energy insecurity index is generated for low-income U.S. families. ► Severely energy insecure households have unique characteristics. ► Energy insecure households are more likely to participate in LIHEAP. ► RECS survey questions should be modified for an improved energy insecurity index.

  10. Map the Meal Gap: Exploring Food Insecurity at the Local Level

    OpenAIRE

    Craig Gundersen; Emily Engelhard; Elaine Waxman

    2014-01-01

    The burgeoning food insecurity literature in the United States has provided a portrait of the causes and consequences of food insecurity. One underexplored aspect is the spatial diversity in food insecurity across the United States. In response, Feeding America has been releasing annual county-level food insecurity estimates since 2010. In this article, we describe the methods underlying these estimates, followed by answers to the following: What are the state-level determinants of food insec...

  11. Consequences of insecurity in emergency telephone consultations: an experimental study in medical students.

    Science.gov (United States)

    Barth, J; Ahrens, R; Schaufelberger, M

    2014-01-01

    Handling emergency telephone consultations (ETCs) is a challenging and very important task for doctors. The aims of the study were to document insecurity in medical students during ETCs and to identify the reasons for that insecurity. We hypothesised that insecurity is associated with advising more urgent action (e.g. advice to call for an ambulance) in ETCs. We used ETCs with simulated patients (SPs), with each student randomly allocated two of four possible cases. After the training, 137 students reported on any insecurity that they had in the various ETC phases. We analysed the reasons for insecurity using descriptive statistics. The association between the students' advice that urgent action was needed and their insecurity was analysed with Spearman rank correlation. Overall, 95% of the students felt insecure in at least one phase of their ETC. History taking was the phase in which students felt most insecure (63.1%), followed by the phase of analysing the information given by the patient (44.9%). Perceived insecurity was associated with more urgent advice in one case scenario (abdominal pain; correlation r = 0.46; p ETC decision-making. ETC training in medical schools, with a focus on structured history taking and formulating discriminating questions, might help decrease insecurity in ETCs. Medical education should also teach management of insecurity.

  12. Quantumness-generating capability of quantum dynamics

    Science.gov (United States)

    Li, Nan; Luo, Shunlong; Mao, Yuanyuan

    2018-04-01

    We study quantumness-generating capability of quantum dynamics, where quantumness refers to the noncommutativity between the initial state and the evolving state. In terms of the commutator of the square roots of the initial state and the evolving state, we define a measure to quantify the quantumness-generating capability of quantum dynamics with respect to initial states. Quantumness-generating capability is absent in classical dynamics and hence is a fundamental characteristic of quantum dynamics. For qubit systems, we present an analytical form for this measure, by virtue of which we analyze several prototypical dynamics such as unitary dynamics, phase damping dynamics, amplitude damping dynamics, and random unitary dynamics (Pauli channels). Necessary and sufficient conditions for the monotonicity of quantumness-generating capability are also identified. Finally, we compare these conditions for the monotonicity of quantumness-generating capability with those for various Markovianities and illustrate that quantumness-generating capability and quantum Markovianity are closely related, although they capture different aspects of quantum dynamics.

  13. Insecurity, polio vaccination rates, and polio incidence in northwest Pakistan.

    Science.gov (United States)

    Verma, Amol A; Jimenez, Marcia P; Tangermann, Rudolf H; Subramanian, S V; Razak, Fahad

    2018-02-13

    Pakistan is one of three countries in which endemic transmission of poliovirus has never been stopped. Insecurity is often cited but poorly studied as a barrier to eradicating polio. We analyzed routinely collected health data from 32 districts of northwest Pakistan and constructed an index of insecurity based on journalistic reports of the monthly number of deaths and injuries resulting from conflict-related security incidents. The primary outcomes were the monthly incidence of paralytic polio cases within each district between 2007 and 2014 and the polio vaccination percentage from 666 district-level vaccination campaigns between 2007 and 2009, targeting ∼5.7 million children. Multilevel Poisson regression controlling for time and district fixed effects was used to model the association between insecurity, vaccinator access, vaccination rates, and polio incidence. The number of children inaccessible to vaccinators was 19.7% greater (95% CI: 19.2-20.2%), and vaccination rates were 5.3% lower (95% CI: 5.2-5.3%) in "high-insecurity" campaigns compared with "secure" campaigns. The unadjusted mean vaccination rate was 96.3% (SD = 8.6) in secure campaigns and 88.3% (SD = 19.2) in high-insecurity campaigns. Polio incidence was 73.0% greater (95% CI: 30-131%) during high-insecurity months (unadjusted mean = 0.13 cases per million people, SD = 0.71) compared with secure months (unadjusted mean = 1.23 cases per million people, SD = 4.28). Thus, insecurity was associated with reduced vaccinator access, reduced polio vaccination, and increased polio incidence in northwest Pakistan. These findings demonstrate that insecurity is an important obstacle to global polio eradication.

  14. Blind Quantum Signature with Blind Quantum Computation

    Science.gov (United States)

    Li, Wei; Shi, Ronghua; Guo, Ying

    2017-04-01

    Blind quantum computation allows a client without quantum abilities to interact with a quantum server to perform a unconditional secure computing protocol, while protecting client's privacy. Motivated by confidentiality of blind quantum computation, a blind quantum signature scheme is designed with laconic structure. Different from the traditional signature schemes, the signing and verifying operations are performed through measurement-based quantum computation. Inputs of blind quantum computation are securely controlled with multi-qubit entangled states. The unique signature of the transmitted message is generated by the signer without leaking information in imperfect channels. Whereas, the receiver can verify the validity of the signature using the quantum matching algorithm. The security is guaranteed by entanglement of quantum system for blind quantum computation. It provides a potential practical application for e-commerce in the cloud computing and first-generation quantum computation.

  15. Study on the dissociative recombination of HeH+ by multi-channel quantum defect theory

    Directory of Open Access Journals (Sweden)

    Takagi Hidekazu

    2015-01-01

    Full Text Available The dissociative recombination of HeH+ is studied using multi-channel quantum defect theory. We investigated how the partial waves of incident electrons affect the DR cross section. The DR cross section depends on the position of the center of partial wave expansion for the adiabatic S-matrix of electron scattering. When the Rydberg states correlate with the Rydberg states of the hydrogen atom at large internuclear distances, the center should be on the hydrogen atom for a better convergence of the expansion.

  16. Some conservative estimates in quantum cryptography

    International Nuclear Information System (INIS)

    Molotkov, S. N.

    2006-01-01

    Relationship is established between the security of the BB84 quantum key distribution protocol and the forward and converse coding theorems for quantum communication channels. The upper bound Q c ∼ 11% on the bit error rate compatible with secure key distribution is determined by solving the transcendental equation H(Q c )=C-bar(ρ)/2, where ρ is the density matrix of the input ensemble, C-bar(ρ) is the classical capacity of a noiseless quantum channel, and H(Q) is the capacity of a classical binary symmetric channel with error rate Q

  17. The dynamics of attachment insecurity and paranoid thoughts: An experience sampling study.

    Science.gov (United States)

    Sitko, Katarzyna; Varese, Filippo; Sellwood, William; Hammond, Amy; Bentall, Richard

    2016-12-30

    It has been proposed that insecure attachment can have adverse effects on the course of psychosis once symptoms have emerged. There is longitudinal evidence that increased insecure attachment is associated with increased severity of psychotic symptoms. The present study examined whether in the flow of daily life attachment insecurity fluctuates, whether elevated stress precedes the occurrence of attachment insecurity, and whether elevated attachment insecurity precedes the occurrence of paranoia. Twenty clinical participants with a psychosis-spectrum diagnosis and twenty controls were studied over six consecutive days using the experience sampling method (ESM). The findings revealed that fluctuations in attachment insecurity were significantly higher in the clinical group, that elevated stress predicted a subsequent increase in attachment insecurity, and that elevated attachment insecurity predicted a subsequent increase in paranoia; this effect was not observed in auditory hallucinations once co-occurring symptoms were controlled for. Finally, although previous ESM studies have shown that low self-esteem precedes the occurrence of paranoia, attachment insecurity continued to predict paranoia even when self-esteem was controlled for. The findings suggest that attachment security may be associated with a lower risk of paranoia, and that psychological interventions should address attachment beliefs and work towards establishing a sense of attachment security. Copyright © 2016. Published by Elsevier Ireland Ltd.

  18. Food insecurity and physical activity insecurity among rural Oregon families

    Directory of Open Access Journals (Sweden)

    Katherine B. Gunter

    2017-12-01

    Full Text Available Among rural families, rates of both child obesity and household food insecurity (FI are higher compared to non-rural families. These disparities result from a complex interplay of social and environmental conditions that influence behavior. The Transtheoretical Model suggests individual readiness to change underlies success in modifying obesity-preventing behaviors; however, whether an association between readiness to change obesity-related behaviors and FI status among rural families exists is unknown. We examined the association between readiness to change family-level nutrition and physical activity (PA behaviors that predict child obesity and family FI status within a sample of rural families to better understand these relationships. Families (n=144 were recruited from six rural Oregon communities in 2013. Families completed a FI screener and the Family Stage of Change Survey (FSOC, a measure of readiness to change family-level nutrition and PA behaviors associated with obesity. Demographic differences by FI status were explored, and regression was applied to examine relationships between FI and FSOC scores, adjusting for relevant covariates. Among FI families (40.2%, more were non-white (77.8% vs. 22.2%; p=0.036 and had lower adult education (30.4% vs. 11.8% with >high school degree; p=0.015 compared to non-FI families. After adjusting for education, race, ethnicity, and eligibility for federal meal programs, readiness to provide opportunities for PA was lower among FI families (p=0.002. These data highlight a need to further investigate how food insecurity and low readiness to provide PA opportunities, i.e. “physical activity insecurity” may be contributing to the higher obesity rates observed among rural children and families. Keywords: Food insecurity, Physical activity, Rural, Childhood obesity

  19. Food Insecurity Increases the Odds of Obesity Among Young Hispanic Children.

    Science.gov (United States)

    Papas, Mia A; Trabulsi, Jillian C; Dahl, Alicia; Dominick, Gregory

    2016-10-01

    Obesity is a growing public health concern and is more prevalent among low-income and minority populations. Food insecurity may increase the odds of obesity in children. We investigated the association between food insecurity and obesity among low-income, Hispanic, mother-child dyads (n = 74). The United States Department of Agriculture 18-item Household Food Security Survey was used to determine food security status. The majority of households were food insecure (74 %) and one-third (30 %) of children were obese. Food insecurity increased the odds of childhood obesity (OR 10.2; 95 % CI 1.2, 85.5) with stronger associations found within households where mothers were also overweight/obese compared to normal weight (p-for interaction food insecurity and childhood obesity were high among this low-income Hispanic sample. Future studies should elucidate the mechanisms through which food insecurity impacts childhood obesity.

  20. Food insecurity in households in informal settlements in urban South Africa.

    Science.gov (United States)

    Naicker, N; Mathee, A; Teare, J

    2015-04-01

    Food insecurity in the urban poor is a major public health challenge. The Health, Environment and Development study assessed trends in food insecurity and food consumption over a period of 7 years in an informal settlement in Johannesburg, South Africa (SA). Annual cross-sectional surveys were conducted in the informal settlement (Hospital Hill). The degree of household food insecurity decreased significantly from 2006 (85%) to 2012 (70%). There was a spike in 2009 (91%), possibly owing to global food price increases. Childhood food insecurity followed the same trend as household food insecurity. During the first 3 study years, consumption of protein, vegetables and fruit decreased by 10-20%, but had returned to previous levels by 2012. In this study, although declining, food insecurity remains unacceptably high. Hunger relief and poverty alleviation need to be more aggressively implemented in order to improve the quality of life in poor urban communities in SA.

  1. Food insecurity and adult overweight/obesity: Gender and race/ethnic disparities.

    Science.gov (United States)

    Hernandez, Daphne C; Reesor, Layton M; Murillo, Rosenda

    2017-10-01

    The majority of the food insecurity-obesity research has indicated a positive association among women, especially minority women. Less research has been conducted on men, and the findings are inconsistent. The aim was to assess whether gender and race/ethnic disparities exists between the food insecurity and overweight/obesity relationship among adults ages 18-59. We used the cross-sectional 2011 and 2012 National Health Interview Survey data (N = 19,990). Three or more affirmative responses on the 10-item USDA Food Security Scale indicated food insecure experiences. Self-reported height and weight were used to calculate body mass index according to the Centers for Disease Control and Prevention. Multivariate logistic regression models were stratified by gender and race/ethnicity to estimate the association between food insecurity and overweight/obesity controlling for several demographic characteristics. Adults on average were 36 years of age (51% female; 56% white, 27% Hispanic, and 17% black), 27% were food insecure, and 65% were overweight/obese. Food insecurity was most prevalent among blacks and Hispanics, regardless of gender. A greater percentage of food insecure women were overweight/obese compared to food secure women among all race/ethnicity groups; while similar proportions of white, black, and Hispanic men were overweight/obese irrespective of their food security status. In covariate-adjusted models, food insecurity was associated with a 41% and 29% higher odds of being overweight/obese among white and Hispanic women, respectively. Food insecurity was not related to overweight/obesity among black women nor among white, black, and Hispanic men. The complex relationship between food insecurity and obesity suggests a need to investigate potential behavioral and physiological mechanisms, and moderators of this relationship. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Ground-to-satellite quantum teleportation.

    Science.gov (United States)

    Ren, Ji-Gang; Xu, Ping; Yong, Hai-Lin; Zhang, Liang; Liao, Sheng-Kai; Yin, Juan; Liu, Wei-Yue; Cai, Wen-Qi; Yang, Meng; Li, Li; Yang, Kui-Xing; Han, Xuan; Yao, Yong-Qiang; Li, Ji; Wu, Hai-Yan; Wan, Song; Liu, Lei; Liu, Ding-Quan; Kuang, Yao-Wu; He, Zhi-Ping; Shang, Peng; Guo, Cheng; Zheng, Ru-Hua; Tian, Kai; Zhu, Zhen-Cai; Liu, Nai-Le; Lu, Chao-Yang; Shu, Rong; Chen, Yu-Ao; Peng, Cheng-Zhi; Wang, Jian-Yu; Pan, Jian-Wei

    2017-09-07

    An arbitrary unknown quantum state cannot be measured precisely or replicated perfectly. However, quantum teleportation enables unknown quantum states to be transferred reliably from one object to another over long distances, without physical travelling of the object itself. Long-distance teleportation is a fundamental element of protocols such as large-scale quantum networks and distributed quantum computation. But the distances over which transmission was achieved in previous teleportation experiments, which used optical fibres and terrestrial free-space channels, were limited to about 100 kilometres, owing to the photon loss of these channels. To realize a global-scale 'quantum internet' the range of quantum teleportation needs to be greatly extended. A promising way of doing so involves using satellite platforms and space-based links, which can connect two remote points on Earth with greatly reduced channel loss because most of the propagation path of the photons is in empty space. Here we report quantum teleportation of independent single-photon qubits from a ground observatory to a low-Earth-orbit satellite, through an uplink channel, over distances of up to 1,400 kilometres. To optimize the efficiency of the link and to counter the atmospheric turbulence in the uplink, we use a compact ultra-bright source of entangled photons, a narrow beam divergence and high-bandwidth and high-accuracy acquiring, pointing and tracking. We demonstrate successful quantum teleportation of six input states in mutually unbiased bases with an average fidelity of 0.80 ± 0.01, well above the optimal state-estimation fidelity on a single copy of a qubit (the classical limit). Our demonstration of a ground-to-satellite uplink for reliable and ultra-long-distance quantum teleportation is an essential step towards a global-scale quantum internet.

  3. Conceptualizing and contextualizing food insecurity among Greenlandic children

    DEFF Research Database (Denmark)

    Niclasen, B.; Molcho, M.; Arnfjord, S.

    2013-01-01

    OBJECTIVE: To review the context of food insecurity in Greenlandic children, to review and compare the outcomes related to food insecurity in Greenlandic children, in other Arctic child populations and in other western societies, and to explore the measure used by the Health Behaviour in School-a...

  4. Decoherence-full subsystems and the cryptographic power of a private shared reference frame

    International Nuclear Information System (INIS)

    Bartlett, Stephen D.; Rudolph, Terry; Spekkens, Robert W.

    2004-01-01

    We show that private shared reference frames can be used to perform private quantum and private classical communication over a public quantum channel. Such frames constitute a type of private shared correlation, distinct from private classical keys or shared entanglement, useful for cryptography. We present optimally efficient schemes for private quantum and classical communication given a finite number of qubits transmitted over an insecure channel and given a private shared Cartesian frame and/or a private shared reference ordering of the qubits. We show that in this context, it is useful to introduce the concept of a decoherence-full subsystem, wherein every state is mapped to the completely mixed state under the action of the decoherence

  5. Food insecurity and obesity in New York City primary care clinics.

    Science.gov (United States)

    Karnik, Arati; Foster, Byron Alexander; Mayer, Victoria; Pratomo, Vanessa; McKee, Diane; Maher, Stacia; Campos, Giselle; Anderson, Matthew

    2011-07-01

    Hunger continues to be a problem in New York City; paradoxically, the city also has disproportionally high rates of diabetes and obesity. Some research suggests that food insecurity leads to obesity. We undertook a cross-sectional "card study" in which doctors working at 8 New York City area primary care practices administered a brief, anonymous survey to patients they saw during clinic sessions. The survey included a 2-question food insecurity screen and questions about enrollment in nutrition assistance programs. Height and weight were also measured at the visit. Cards were completed for 558 patients (65.1% female; 74.7% adults; 78.5% conducted in English). Fifty-five percent of patients were receiving some form of food assistance. More than half of patients (51.7%) reported some degree of food insecurity. Of adult participants, 21.8% had normal weight, 29.1% were overweight, and 48.2% were obese. Food insecurity was significantly associated with increasing body mass index in women not receiving food assistance. There was no significant association between body mass index and food insecurity in children. In an urban population, overweight and obesity are very common as is food insecurity. We found an association between food insecurity and obesity only among women not receiving food assistance suggesting a possible protective role for food assistance. Providers should consider food insecurity in similar populations when trying to address obesity.

  6. Food insecurity and the metabolic syndrome among women from low income communities in Malaysia.

    Science.gov (United States)

    Shariff, Zalilah Mohd; Sulaiman, Norhasmah; Jalil, Rohana Abdul; Yen, Wong Chee; Yaw, Yong Heng; Taib, Mohd Nasir Mohd; Kandiah, Mirnalini; Lin, Khor Geok

    2014-01-01

    This cross-sectional study examined the relationship between household food insecurity and the metabolic syndrome (MetS) among reproductive-aged women (n=625) in low income communities. The Radimer/Cornell Hunger and Food Insecurity instrument was utilized to assess food insecurity. Anthropometry, diet diversity, blood pressure and fasting venous blood for lipid and glucose profile were also obtained. MetS was defined as having at least 3 risk factors and is in accordance with the Harmonized criteria. The prevalence of food insecurity and MetS was 78.4% (household food insecure, 26.7%; individual food insecure, 25.3%; child hunger, 26.4%) and 25.6%, respectively. While more food secure than food insecure women had elevated glucose (food secure, 54.8% vs food insecure, 37.3-46.1%), total cholesterol (food secure, 54.1% vs food insecure, 32.1-40.7%) and LDL-cholesterol (food secure, 63.7% vs food insecure, 40.6-48.7%), the percentage of women with overweight/ obesity, abdominal obesity, hypertension, high triglyceride, low HDL-cholesterol and MetS did not vary significantly by food insecurity status. However, after controlling for demographic and socioeconomic covariates, women in food insecure households were less likely to have MetS (individual food insecure and child hunger) (phealthy food choices and nutrition education that could reduce the risk of diet-related chronic diseases.

  7. Optimal processing of reversible quantum channels

    Energy Technology Data Exchange (ETDEWEB)

    Bisio, Alessandro, E-mail: alessandro.bisio@unipv.it [QUIT Group, Dipartimento di Fisica, INFN Sezione di Pavia, via Bassi 6, 27100 Pavia (Italy); D' Ariano, Giacomo Mauro; Perinotti, Paolo [QUIT Group, Dipartimento di Fisica, INFN Sezione di Pavia, via Bassi 6, 27100 Pavia (Italy); Sedlák, Michal [Department of Optics, Palacký University, 17. Listopadu 1192/12, CZ-771 46 Olomouc (Czech Republic); Institute of Physics, Slovak Academy of Sciences, Dúbravská Cesta 9, 845 11 Bratislava (Slovakia)

    2014-05-01

    We consider the general problem of the optimal transformation of N uses of (possibly different) unitary channels to a single use of another unitary channel in any finite dimension. We show how the optimal transformation can be fully parallelized, consisting in a preprocessing channel followed by a parallel action of all the N unitaries and a final postprocessing channel. Our techniques allow to achieve an exponential reduction in the number of the free parameters of the optimization problem making it amenable to an efficient numerical treatment. Finally, we apply our general results to find the analytical solution for special cases of interest like the cloning of qubit phase gates.

  8. Operator-sum representation for bosonic Gaussian channels

    International Nuclear Information System (INIS)

    Ivan, J. Solomon; Sabapathy, Krishna Kumar; Simon, R.

    2011-01-01

    Operator-sum or Kraus representations for single-mode bosonic Gaussian channels are developed, and several of their consequences explored. The fact that the two-mode metaplectic operators acting as unitary purification of these channels do not, in their canonical form, mix the position and momentum variables is exploited to present a procedure which applies uniformly to all families in the Holevo classification. In this procedure the Kraus operators of every quantum-limited Gaussian channel can be simply read off from the matrix elements of a corresponding metaplectic operator. Kraus operators are employed to bring out, in the Fock basis, the manner in which the antilinear, unphysical matrix transposition map when accompanied by injection of a threshold classical noise becomes a physical channel, denoted D(κ) in the Holevo classification. The matrix transposition channels D(κ), D(κ -1 ) turn out to be a dual pair in the sense that their Kraus operators are related by the adjoint operation. The amplifier channel with amplification factor κ and the beam-splitter channel with attenuation factor κ -1 turn out to be mutually dual in the same sense. The action of the quantum-limited attenuator and amplifier channels as simply scaling maps on suitable quasiprobabilities in phase space is examined in the Kraus picture. Consideration of cumulants is used to examine the issue of fixed points. The semigroup property of the amplifier and attenuator families leads in both cases to a Zeno-like effect arising as a consequence of interrupted evolution. In the cases of entanglement-breaking channels a description in terms of rank 1 Kraus operators is shown to emerge quite simply. In contradistinction, it is shown that there is not even one finite rank operator in the entire linear span of Kraus operators of the quantum-limited amplifier or attenuator families, an assertion far stronger than the statement that these are not entanglement breaking channels. A characterization of

  9. Charge-transfer channel in quantum dot-graphene hybrid materials

    Science.gov (United States)

    Cao, Shuo; Wang, Jingang; Ma, Fengcai; Sun, Mengtao

    2018-04-01

    The energy band theory of a classical semiconductor can qualitatively explain the charge-transfer process in low-dimensional hybrid colloidal quantum dot (QD)-graphene (GR) materials; however, the definite charge-transfer channels are not clear. Using density functional theory (DFT) and time-dependent DFT, we simulate the hybrid QD-GR nanostructure, and by constructing its orbital interaction diagram, we show the quantitative coupling characteristics of the molecular orbitals (MOs) of the hybrid structure. The main MOs are derived from the fragment MOs (FOs) of GR, and the Cd13Se13 QD FOs merge with the GR FOs in a certain proportion to afford the hybrid system. Upon photoexcitation, electrons in the GR FOs jump to the QD FOs, leaving holes in the GR FOs, and the definite charge-transfer channels can be found by analyzing the complex MOs coupling. The excited electrons and remaining holes can also be localized in the GR or the QD or transfer between the QD and GR with different absorption energies. The charge-transfer process for the selected excited states of the hybrid QD-GR structure are testified by the charge difference density isosurface. The natural transition orbitals, charge-transfer length analysis and 2D site representation of the transition density matrix also verify the electron-hole delocalization, localization, or coherence chacracteristics of the selected excited states. Therefore, our research enhances understanding of the coupling mechanism of low-dimensional hybrid materials and will aid in the design and manipulation of hybrid photoelectric devices for practical application in many fields.

  10. The impact of a school food aid program on household food insecurity

    Science.gov (United States)

    Petralias, Athanassios; Papadimitriou, Eleni; Riza, Elena; Karagas, Margaret R.; Zagouras, Alexia B.A.

    2016-01-01

    Background: We had a unique opportunity to establish the extent of food insecurity and the potential impact of a large-scale school-based nutritional program, in low-socioeconomic status districts of Greece, during the current economic crisis. Methods: Around 162 schools with 25 349 students participated during the 2012–2013 school year. Each student received a daily healthy meal designed by nutrition specialists. Food insecurity levels, measured using the Food Security Survey Module were assessed at baseline and after a 1–8-month intervention period. Pre–post intervention responses were matched at an individual level. Results: Around 64.2% of children’s households experienced food insecurity at baseline. This percentage decreased to 59.1% post-intervention, P insecurity score diminished by 6.5%, P insecurity score increased by 6.3% (OR = 1.06, 95% CI: 1.02–1.11). Those experiencing food insecurity with hunger at baseline were more likely to improve food insecurity score than those who did not (OR = 3.51, 95%CI: 2.92–4.21). Conclusion: Children and families residing in low socioeconomic areas of Greece, experience high levels of food insecurity. Our findings suggest that participation in a school-based food aid program may reduce food insecurity for children and their families in a developed country in times of economic hardship. PMID:26873860

  11. Implementation of generalized quantum measurements: Superadditive quantum coding, accessible information extraction, and classical capacity limit

    International Nuclear Information System (INIS)

    Takeoka, Masahiro; Fujiwara, Mikio; Mizuno, Jun; Sasaki, Masahide

    2004-01-01

    Quantum-information theory predicts that when the transmission resource is doubled in quantum channels, the amount of information transmitted can be increased more than twice by quantum-channel coding technique, whereas the increase is at most twice in classical information theory. This remarkable feature, the superadditive quantum-coding gain, can be implemented by appropriate choices of code words and corresponding quantum decoding which requires a collective quantum measurement. Recently, an experimental demonstration was reported [M. Fujiwara et al., Phys. Rev. Lett. 90, 167906 (2003)]. The purpose of this paper is to describe our experiment in detail. Particularly, a design strategy of quantum-collective decoding in physical quantum circuits is emphasized. We also address the practical implication of the gain on communication performance by introducing the quantum-classical hybrid coding scheme. We show how the superadditive quantum-coding gain, even in a small code length, can boost the communication performance of conventional coding techniques

  12. Informal assistance to urban families and the risk of household food insecurity.

    Science.gov (United States)

    King, Christian

    2017-09-01

    Food insecurity is a persistent social problem affecting one out of eight households in the United States. While evidence shows that public assistance programs (formal assistance) are effective in reducing food insecurity, there is more limited evidence documenting how informal support, through social capital, affects food insecurity. To examine the role of informal support (through instrumental social support, social cohesion, social control, and social participation) on food insecurity transitions using longitudinal data of a sample of disadvantaged urban mothers from the Fragile Families and Child Wellbeing Study. In addition, the study examines whether these associations vary by participation in the Supplemental Nutrition Assistance Program (SNAP) using interaction terms. The sample includes 2481 mothers of children between ages three and five. The analysis uses unadjusted and adjusted logistic regressions. Interaction terms are included to examine formal and informal support. In addition, the analysis uses structural equation modeling to examine direct and indirect associations of the informal support variables on food insecurity. Social support and social cohesion reduce the risk of food insecurity, reduce the risk of remaining food insecure, and reduce the risk of becoming food insecure. Social control has an indirect effect on food insecurity, which is mainly through social cohesion. Social participation also has an indirect effect through social support and social cohesion. SNAP participation for mothers with little to no informal support did not reduce the risk of food insecurity. Instead of focusing on improving the food access of households, interventions should be expanded to the neighborhood level. Building social capital for low-income residents would increase the cohesiveness of their neighborhoods and their access to social support, which would increase the availability of resources to prevent or overcome food insecurity and other hardships

  13. Persistent household food insecurity, HIV, and maternal stress in peri-urban Ghana.

    Science.gov (United States)

    Garcia, Jonathan; Hromi-Fiedler, Amber; Mazur, Robert E; Marquis, Grace; Sellen, Daniel; Lartey, Anna; Pérez-Escamilla, Rafael

    2013-03-11

    The mental health of caregivers has been shown to be important for improving HIV prevention and treatment. Household food insecurity affects hundreds of millions of individuals in Sub-Saharan Africa, a region that experiences a disproportionate burden of the HIV pandemic. Both maternal HIV diagnosis and household food insecurity may be linked with maternal stress. This in turn may lead to unhealthy coping behaviors. We examined the independent associations of HIV, persistent household food insecurity and the synergistic effect of both on maternal stress. Ghanaian women recruited prenatally from hospitals offering voluntary counseling and testing (VCT) were followed for 12 months after childbirth (N = 232). A locally adapted 7-item version of the US Household Food Security Survey Module was applied at four time points postpartum. We dichotomized participant households as being persistently food insecure (i.e., food insecure at each time point) or not (i.e., food secure at any time point). We dichotomized participant women as not perceiving vs. perceiving stress at 12 months postpartum in reference to the median sample score on the 4-item Cohen's stress scale. Binary multivariate logistic regression models were used to assess the independent and interactive effects of maternal HIV and persistent household food insecurity on maternal stress. The proportion of HIV-positive women that lived in severe food insecure households increased over time. By contrast, the HIV-negative group living in severely food insecure households experienced a steady decline across time. HIV-infection (AOR = 2.31, 95% CI 1.29-4.12) and persistent household food insecurity (AOR = 3.55, 95% CI 1.13-11.13) were independently associated with maternal stress in a multivariate model. Being both HIV-positive and persistently food insecure strongly and synergistically increased the risk for maternal perceived stress (AOR = 15.35, 95% CI 1.90-124.14). In agreement with syndemic theory

  14. Ab initio R-matrix/Multi-channel Quantum Defect Theory applied to Molecular Core Excitation and Ionization

    International Nuclear Information System (INIS)

    Hiyama, M.; Kosugi, N.

    2004-01-01

    Full text: Ab initio R-matrix/MQDT approach, which is a combination of ab initio R-matrix techniques and the multi channel quantum defect theory (MQDT), has recently been developed by one of the present authors (MH) and Child, to successfully obtain the potential energy curves of Rydberg states converging to not only the lowest but also the higher ionized states. This approach is also applied to estimate the valence state interaction with Rydberg and continuum (ionization) channels. Very recently we have made an original ab initio polyatomic R-matrix/MQDT program package, GSCF4R based on Gaussian type basis functions for the bound and continuum states, to extensively study molecular excitation and ionization in the X-ray region as well as in the VUV region. We are going to report the results for core excitation and ionization of diatomic molecules such as NO and O 2 to show that the R-matrix/MQDT method is indispensable to describe the core-to-Rydberg states with the higher quantum number and the continuum states. These results lead us to the conclusion that the close-coupling approximation augmented with the correlation term within the R-matrix/MQDT formalism is powerful to calculate the Rydberg-valence mixing and the interchannel coupling between several core-ionized states

  15. Quantum communication, reference frames, and gauge theory

    International Nuclear Information System (INIS)

    Enk, S. J. van

    2006-01-01

    We consider quantum communication in the case that the communicating parties not only do not share a reference frame but use imperfect quantum communication channels, in that each channel applies some fixed but unknown unitary rotation to each qubit. We discuss similarities and differences between reference frames within that quantum communication model and gauge fields in gauge theory. We generalize the concept of refbits and analyze various quantum communication protocols within the communication model

  16. Food insecurity among Cambodian refugee women two decades post resettlement.

    Science.gov (United States)

    Peterman, Jerusha Nelson; Wilde, Parke E; Silka, Linda; Bermudez, Odilia I; Rogers, Beatrice Lorge

    2013-04-01

    Resettled refugees have high rates of chronic disease, which may be partially due to persistent food insecurity. This study describes food experiences on arrival in the U.S. and current food security status and examines characteristics related to food insecurity in a well-established refugee community. Focus groups and a survey assessed food security status and personal characteristics of Cambodian women in Lowell, MA, USA. Multivariate logistic regression was used to examine relationships with food insecurity. Current rates of food insecurity are high. In multivariate models, food insecurity was positively associated with being depressed and being widowed, and negatively associated with higher income and acculturation. Early arrivers (1980s) had difficulty in the U.S. food system on arrival, while later arrivers (1990s-2000s) did not. Refugee agencies should consider strategically devoting resources to ensure successful early transition to the U.S. food environment and long-term food security of refugees.

  17. Information geometry of Gaussian channels

    International Nuclear Information System (INIS)

    Monras, Alex; Illuminati, Fabrizio

    2010-01-01

    We define a local Riemannian metric tensor in the manifold of Gaussian channels and the distance that it induces. We adopt an information-geometric approach and define a metric derived from the Bures-Fisher metric for quantum states. The resulting metric inherits several desirable properties from the Bures-Fisher metric and is operationally motivated by distinguishability considerations: It serves as an upper bound to the attainable quantum Fisher information for the channel parameters using Gaussian states, under generic constraints on the physically available resources. Our approach naturally includes the use of entangled Gaussian probe states. We prove that the metric enjoys some desirable properties like stability and covariance. As a by-product, we also obtain some general results in Gaussian channel estimation that are the continuous-variable analogs of previously known results in finite dimensions. We prove that optimal probe states are always pure and bounded in the number of ancillary modes, even in the presence of constraints on the reduced state input in the channel. This has experimental and computational implications. It limits the complexity of optimal experimental setups for channel estimation and reduces the computational requirements for the evaluation of the metric: Indeed, we construct a converging algorithm for its computation. We provide explicit formulas for computing the multiparametric quantum Fisher information for dissipative channels probed with arbitrary Gaussian states and provide the optimal observables for the estimation of the channel parameters (e.g., bath couplings, squeezing, and temperature).

  18. Quantum secret sharing based on quantum error-correcting codes

    International Nuclear Information System (INIS)

    Zhang Zu-Rong; Liu Wei-Tao; Li Cheng-Zu

    2011-01-01

    Quantum secret sharing(QSS) is a procedure of sharing classical information or quantum information by using quantum states. This paper presents how to use a [2k − 1, 1, k] quantum error-correcting code (QECC) to implement a quantum (k, 2k − 1) threshold scheme. It also takes advantage of classical enhancement of the [2k − 1, 1, k] QECC to establish a QSS scheme which can share classical information and quantum information simultaneously. Because information is encoded into QECC, these schemes can prevent intercept-resend attacks and be implemented on some noisy channels. (general)

  19. Food insecurity and women's roles in the African region.

    Science.gov (United States)

    Zimet, J E

    1997-01-01

    Food insecurity is most severe in the African continent, with 200 million of the 800 million people suffering from food insecurity found in sub-Saharan Africa. The main causes of food insecurity in Africa are natural disasters and conflict. Since African women are often the main food producers, income earners and guardians of family health and nutrition at the rural level, they play a key role in dealing with the continent's food insecurity problem. During the Women's Conference in Kenya in 1985, women were encouraged to play a central role in the development and production of food and agriculture, while governments were asked to provide women with access to land, child care facilities, and education. If given the right tools and support from the government and community, women could become vital players in eliminating world hunger.

  20. Comment on "Modified quantum-speed-limit bounds for open quantum dynamics in quantum channels"

    Science.gov (United States)

    Mirkin, Nicolás; Toscano, Fabricio; Wisniacki, Diego A.

    2018-04-01

    In a recent paper [Phys. Rev. A 95, 052118 (2017), 10.1103/PhysRevA.95.052118], the authors claim that our criticism, in Phys. Rev. A 94, 052125 (2016), 10.1103/PhysRevA.94.052125, to some quantum speed limit bounds for open quantum dynamics that appeared recently in literature are invalid. According to the authors, the problem with our analysis would be generated by an artifact of the finite-precision numerical calculations. We analytically show here that it is not possible to have any inconsistency associated with the numerical precision of calculations. Therefore, our criticism of the quantum speed limit bounds continues to be valid.

  1. Food insecurity is associated with obesity among US adults in 12 states.

    Science.gov (United States)

    Pan, Liping; Sherry, Bettylou; Njai, Rashid; Blanck, Heidi M

    2012-09-01

    A redesigned food insecurity question that measured food stress was included in the 2009 Behavioral Risk Factor Surveillance System in the Social Context optional module. The objective of our study was to examine the association between food stress and obesity using this question as a surrogate for food insecurity. Our analytic sample included 66,553 adults from 12 states. Food insecurity was determined by response (always/usually/sometimes) to the question, "How often in the past 12 months would you say you were worried or stressed about having enough money to buy nutritious meals?" T tests were used to compare prevalence differences between groups, and logistic regression was used to examine the association between food insecurity and obesity. Among the 12 states, the prevalence of obesity was 27.1% overall, 25.2% among food secure adults, and 35.1% among food insecure adults. Food insecure adults had 32% increased odds of being obese compared to food secure adults. Compared with food secure adults, food insecure adults had significantly higher prevalence of obesity in the following population subgroups: adults ages ≥30 years, women, non-Hispanic whites, non-Hispanic blacks, adults with some college education or a college degree, a household income of food insecure adults were obese. Food insecurity was associated with obesity in the overall population and most population subgroups. These findings are consistent with previous research and highlight the importance of increasing access to affordable healthy foods for all adults. Published by Elsevier Inc.

  2. Concatenated quantum codes

    Energy Technology Data Exchange (ETDEWEB)

    Knill, E.; Laflamme, R.

    1996-07-01

    One main problem for the future of practial quantum computing is to stabilize the computation against unwanted interactions with the environment and imperfections in the applied operations. Existing proposals for quantum memories and quantum channels require gates with asymptotically zero error to store or transmit an input quantum state for arbitrarily long times or distances with fixed error. This report gives a method which has the property that to store or transmit a qubit with maximum error {epsilon} requires gates with errors at most {ital c}{epsilon} and storage or channel elements with error at most {epsilon}, independent of how long we wish to store the state or how far we wish to transmit it. The method relies on using concatenated quantum codes and hierarchically implemented recovery operations. The overhead of the method is polynomial in the time of storage or the distance of the transmission. Rigorous and heuristic lower bounds for the constant {ital c} are given.

  3. Job Insecurity as a Social Psychological Phenomenon

    Directory of Open Access Journals (Sweden)

    Chuykova T.S.

    2015-12-01

    Full Text Available The paper addresses a relatively new phenomenon of job insecurity. It provides an analysis of the various interpretations of the phenomenon given by Russian and foreign researchers, focuses on its social economical determinants and consequences for individuals and organizations. The paper concludes with an outline of some possible ways of overcoming the negative consequences of job insecurity — as for individuals, as for organizations, as for the society as a whole.

  4. Homelessness and Housing Insecurity Among Former Prisoners.

    OpenAIRE

    Herbert, CW; Morenoff, JD; Harding, DJ

    2015-01-01

    The United States has experienced dramatic increases in both incarceration rates and the population of insecurely housed or homeless persons since the 1980s. These marginalized populations have strong overlaps, with many people being poor, minority, and from an urban area. That a relationship between homelessness, housing insecurity, and incarceration exists is clear, but the extent and nature of this relationship is not yet adequately understood. We use longitudinal, administrative data on M...

  5. Continuous variable quantum key distribution with modulated entangled states

    DEFF Research Database (Denmark)

    Madsen, Lars S; Usenko, Vladyslav C.; Lassen, Mikael

    2012-01-01

    Quantum key distribution enables two remote parties to grow a shared key, which they can use for unconditionally secure communication over a certain distance. The maximal distance depends on the loss and the excess noise of the connecting quantum channel. Several quantum key distribution schemes...... based on coherent states and continuous variable measurements are resilient to high loss in the channel, but are strongly affected by small amounts of channel excess noise. Here we propose and experimentally address a continuous variable quantum key distribution protocol that uses modulated fragile...... entangled states of light to greatly enhance the robustness to channel noise. We experimentally demonstrate that the resulting quantum key distribution protocol can tolerate more noise than the benchmark set by the ideal continuous variable coherent state protocol. Our scheme represents a very promising...

  6. DETERMINANTS OF HOUSING INSECURITY IN A LOW INCOMESOUTH AFRICAN TOWNSHIP

    Directory of Open Access Journals (Sweden)

    N.P Mncayi

    2017-07-01

    Full Text Available The campaign to end povertyby 2030,as advocated by the World Bank,has multifacetedcomponents. Food security and abject poverty have received more attention;however,little attention has been focused on housing insecurity. This is important,especially giventhe fact that it iswidely acknowledged that housing satiates an essential human need forphysical security, dignity and prosperity,among other things. Housing, for some time,has been observed as crucial to individual and family functioning. As indicated byorganisations such as the United Nations Habitat, the importance of appropriate housingis explained by the fact that safe housing is seen as a basic need among other needs suchas food, all of which are regarded as central components of the security of ordinaryhouseholds, particularly in developing countries. In 2015, more than 1.5 billionpeopleinthe world were living in housing that was unsafe and inadequate, while in the meantime,millions experienced eviction from their homes every year, with at least 100 millionpeople becoming homeless on any given day.Therefore, it ispertinent to understand whatdetermines housing insecurity. The studyaims toinvestigatefactors thatdetermineshousing insecurity. Using data collected from Sharpeville and Bophelong, two lowincome townships in South Africa that are particularlyvulnerable to housing insecurity,the study employs amultinomiallogisticregression to investigate the effects of head ofhousehold and the general household characteristics on housing insecurity. Theresults ofthe regression analysis show that income, gender, number of people in the household andthe amount paid to bond or rent are significant predictors of housing insecurity.Contentious issues like access to land and job opportunities are areas of further study inunderstanding the multifaceted phenomenon of housing insecurity.

  7. Predictors of chronic food insecurity among adolescents in Southwest Ethiopia: a longitudinal study

    Directory of Open Access Journals (Sweden)

    Belachew Tefera

    2012-08-01

    Full Text Available Abstract Background Evidence on the differential impacts of the global food crisis as it translates into chronic food insecurity locally is essential to design food security interventions targeting the most vulnerable population groups. There are no studies on the extent of chronic food insecurity or its predictors among adolescents in developing countries. In the context of increased food prices in Ethiopia, we hypothesized that adolescents in low income urban households are more likely to suffer from chronic food insecurity than those in the rural areas who may have direct access to agricultural products. Methods This report is based on data from the first two rounds of the Jimma Longitudinal Family Survey of Youth (JLFSY. Both adolescents and households were selected using a stratified random sampling method. A total of 1911 adolescents aged 13-17 years were interviewed on their personal experiences of food insecurity both at baseline and at year two. Multivariable logistic regression analyses were used to compare chronic adolescent food insecurity by household income, household food insecurity, and socio-demographic variables after one year of follow-up. Results Overall, 20.5% of adolescents were food insecure in the first round survey, while the proportion of adolescents with food insecurity increased to 48.4% one year later. During the one year follow up period, more than half (54.8% of the youth encountered transient food insecurity – that is, either during the first or the second round survey. During the follow up period, 14.0% of adolescents had chronic food insecurity (i.e. were food insecure at both rounds. Multivariable logistic regression analysis showed that adolescents in the urban households with low (OR = 1.69, P = 0.008 and middle (OR = 1.80, P = 0.003 income tertiles were nearly twice as likely to suffer from chronic food insecurity compared with those in high income tertile, while this was not the case in

  8. Quantum Information: Opportunities and Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Bennink, Ryan S [ORNL

    2008-01-01

    Modern society is shaped by the ability to transmit, manipulate, and store large amounts of information. Although we tend to think of information as abstract, information is physical, and computing is a physical process. How then should we understand information in a quantum world, in which physical systems may exist in multiple states at once and are altered by the very act of observation? This question has evolved into an exciting new field of research called Quantum Information (QI). QI challenges many accepted rules and practices in computer science. For example, a quantum computer would turn certain hard problems into soft problems, and would render common computationally-secure encryption methods (such as RSA) insecure. At the same time, quantum communication would provide an unprecedented kind of intrinsic information security at the level of the smallest physical objects used to store or transmit the information. This talk provides a general introduction to the subject of quantum information and its relevance to cyber security. In the first part, two of the stranger aspects of quantum physics namely, superposition and uncertainty are explained, along with their relation to the concept of information. These ideas are illustrated with a few examples: quantum ID cards, quantum key distribution, and Grover s quantum search algorithm. The state-of-the-art in quantum computing and communication hardware is then discussed, along with the daunting technological challenges that must be overcome. Relevant experimental and theoretical efforts at ORNL are highlighted. The talk concludes with speculations on the short- and long-term impact of quantum information on cyber security.

  9. Nutritional Outcomes Related to Household Food Insecurity among Mothers in Rural Malaysia

    Science.gov (United States)

    Ihab, A.N.; Manan, W.M. Wan; Suriati, W.N. Wan; Zalilah, M.S.; Rusli, A. Mohamed

    2013-01-01

    During the past two decades, the rates of food insecurity and obesity have risen. Although a relationship between these two seemingly-paradoxical states has not been repeatedly seen in men, research suggests that a correlation between them exists in women. This study examines nutritional outcomes of household food insecurity among mothers in rural Malaysia. A cross-sectional survey of low-income households was conducted, and 223 households with mothers aged 18–55 years, who were non-lactating, non-pregnant, and had at least one child aged 2–12 years, were purposively selected. A questionnaire was administered that included the Radimer/Cornell Scale, items about sociodemographic characteristics, and anthropometric measurements. Of the households, 16.1% were food-secure whereas 83.9% experienced some kind of food insecurity: 29.6% of households were food-insecure, 19.3% contained individuals who were food-insecure, and 35.0% fell into the ‘child hunger’ category. The result reported that household-size, total monthly income, income per capita, and food expenditure were significant risk factors of household food insecurity. Although there was a high prevalence of overweight and obese mothers (52%) and 47.1% had at-risk waist-circumference (≥80 cm), no significant association was found between food insecurity, body mass index, and waist-circumference. In conclusion, the rates of household food insecurity and overweight and obesity were high in the study population, although they are looking paradoxical. Longitudinal studies with larger sample-sizes are recommended to further examine the relationship between food insecurity and obesity. PMID:24592589

  10. Household food insecurity is associated with childhood malaria in rural Haiti.

    Science.gov (United States)

    Pérez-Escamilla, Rafael; Dessalines, Michael; Finnigan, Mousson; Pachón, Helena; Hromi-Fiedler, Amber; Gupta, Nishang

    2009-11-01

    Haiti is the poorest country in the Western Hemisphere and is heavily affected by food insecurity and malaria. To find out if these 2 conditions are associated with each other, we studied a convenience sample of 153 women with children 1-5 y old in Camp Perrin, South Haiti. Household food insecurity was assessed with the 16-item Escala Latinoamericana y Caribeña de Seguridad Alimentaria (ELCSA) scale previously validated in the target communities. ELCSA's reference time period was the 3 mo preceding the survey and it was answered by the mother. Households were categorized as either food secure (2%; ELCSA score = 0), food insecure/very food insecure (42.7%; ELCSA score range: 1-10), or severely food insecure (57.3%; ELCSA score range: 11-16). A total of 34.0% of women reported that their children had malaria during the 2 mo preceding the survey. Multivariate analyses showed that severe food insecure was a risk factor for perceived clinical malaria (odds ratio: 5.97; 95% CI: 2.06-17.28). Additional risk factors for perceived clinical malaria were as follows: not receiving colostrum, poor child health (via maternal self-report), a child BMI <17 kg/m(2), and child vitamin A supplementation more than once since birth. Findings suggest that policies and programs that address food insecurity are also likely to reduce the risk of malaria in Haiti.

  11. Broadband Quantum Cryptography

    CERN Document Server

    Rogers, Daniel

    2010-01-01

    Quantum cryptography is a rapidly developing field that draws from a number of disciplines, from quantum optics to information theory to electrical engineering. By combining some fundamental quantum mechanical principles of single photons with various aspects of information theory, quantum cryptography represents a fundamental shift in the basis for security from numerical complexity to the fundamental physical nature of the communications channel. As such, it promises the holy grail of data security: theoretically unbreakable encryption. Of course, implementing quantum cryptography in real br

  12. Food insecurity and cognitive function in Puerto Rican adults

    Science.gov (United States)

    Food insecurity is associated with nutrient inadequacy and a variety of unfavorable health outcomes. However, little is known about whether food security is associated with lower cognitive function in the elderly. We investigated the prevalence of food insecurity in a representative sample of 1358 P...

  13. The cognitive/affective distinction of job insecurity: Validation and ...

    African Journals Online (AJOL)

    Kirstam

    emotional exhaustion were also gathered from employees in a variety of South African ... the cognitive and affective dimensions of job insecurity could be distinguished ...... from the perception of an external reality, whereas the affective response represents an internal .... 'Differentiating cognitive and affective job insecurity: ...

  14. Insecure attachment is associated with math anxiety in middle childhood.

    Science.gov (United States)

    Bosmans, Guy; De Smedt, Bert

    2015-01-01

    Children's anxiety for situations requiring mathematical problem solving, a concept referred to as math anxiety, has a unique and detrimental impact on concurrent and long-term mathematics achievement and life success. Little is known about the factors that contribute to the emergence of math anxiety. The current study builds on the hypothesis that math anxiety might reflect a maladaptive affect regulation mechanism that is characteristic for insecure attachment relationships. To test this hypothesis, 87 children primary school children (M age = 10.34 years; SD age = 0.63) filled out questionnaires measuring insecure attachment and math anxiety. They all completed a timed and untimed standardized test of mathematics achievement. Our data revealed that individual differences in math anxiety were significantly related to insecure attachment, independent of age, sex, and IQ. Both tests of mathematics achievement were associated with insecure attachment and this effect was mediated by math anxiety. This study is the first to indicate that math anxiety might develop in the context of insecure parent-child attachment relationships.

  15. Insecure attachment is associated with math anxiety in middle childhood

    Directory of Open Access Journals (Sweden)

    Guy eBosmans

    2015-10-01

    Full Text Available Children’s anxiety for situations requiring mathematical problem solving, a concept referred to as math anxiety, has a unique and detrimental impact on concurrent and long-term mathematics achievement and life success. Little is known about the factors that contribute to the emergence of math anxiety. The current study builds on the hypothesis that math anxiety might reflect a maladaptive affect-regulation mechanism that is characteristic for insecure attachment relationships. To test this hypothesis, 87 children primary school children (Mage = 10.34 years; SDage = 0.63 filled out questionnaires measuring insecure attachment and math anxiety. They all completed a timed and untimed standardized test of mathematics achievement. Our data revealed that individual differences in math anxiety were significantly related to insecure attachment, independent of age, sex and IQ. Both tests of mathematics achievement were associated with insecure attachment and this effect was mediated by math anxiety. This study is the first to indicate that math anxiety might develop in the context of insecure parent-child attachment relationships.

  16. Employment and Economic Insecurity: A Commonsian Perspective

    Directory of Open Access Journals (Sweden)

    Sylvie Morel

    2010-01-01

    Full Text Available The principal concern of this paper is with the need of a theoretical shift in economics for analyzing and devising efficient and innovative policy reforms to combat employment insecurity. Mainstream economics is unable to provide appropriate theorizing about economic phenomena, including economic insecurity. Thus, we must turn to economic theories which radically question the dominant paradigm in economics. John Rogers Commons's institutionalist theory accomplishes that. First, the author of this paper outlines the distinctive character of this theory by presenting some of its crucial methodological differences with neoclassical economics. Second, she explains how economic insecurity is conceptualized as an "instituted" process with this theory of institution. A better mastery of this specific school of thought in economics appears to escape the problems met by mainstream economics by proposing a real theoretical alternative for the development of a truly evolutionary, trans-disciplinary and ethical economic theory.

  17. Employment and Economic Insecurity: A Commonsian Perspective

    Directory of Open Access Journals (Sweden)

    Sylvie Morel

    2009-12-01

    Full Text Available The principal concern of this paper is with the need of a theoretical shift in economics for analyzing and devising efficient and innovative policy reforms to combat employment insecurity. Mainstream economics is unable to provide appropriate theorizing about economic phenomena, including economic insecurity. Thus, we must turn to economic theories which radically question the dominant paradigm in economics. John Rogers Commons's institutionalist theory accomplishes that. First, the author of this paper outlines the distinctive character of this theory by presenting some of its crucial methodological differences with neoclassical economics. Second, she explains how economic insecurity is conceptualized as an "instituted" process with this theory of institution. A better mastery of this specific school of thought in economics appears to escape the problems met by mainstream economics by proposing a real theoretical alternative for the development of a truly evolutionary, trans-disciplinary and ethical economic theory.

  18. Haiti, insecurity, and the politics of asylum.

    Science.gov (United States)

    James, Erica Caple

    2011-09-01

    In this article, I seek to show how states of insecurity provoked by ongoing social, economic, and political ruptures in Haiti can disorder individual subjectivity and generate the flight of individuals seeking asylum within and across borders. Nongovernmental actors working in Haiti and with Haitians in the diaspora frequently managed the long-term psychosocial effects of insecurity. Their interventions can range from repressive to compassionate and influence the formation of identity and the embodied experiences of trauma for vulnerable Haitians. The case of a young Haitian refugee who was repatriated to Haiti from the United States in the 1990s demonstrates how insecurity is both an existential state reflecting the disordering of embodied experience, as well as a collective sociopolitical condition the effects of which cannot be managed or contained within national borders. The case is emblematic of the plight of thousands of Haitians affected by the January 12, 2010, earthquake.

  19. Non-Markovian entanglement dynamics of noisy continuous-variable quantum channels

    International Nuclear Information System (INIS)

    An, J.-H.; Zhang, W.-M.

    2007-01-01

    We investigate the entanglement dynamics of continuous-variable quantum channels in terms of an entangled squeezed state of two cavity fields in a general non-Markovian environment. Using the Feynman-Vernon influence functional theory in the coherent-state representation, we derive an exact master equation with time-dependent coefficients reflecting the non-Markovian influence of the environment. The influence of environments with different spectral densities, e.g., Ohmic, sub-Ohmic, and super-Ohmic, is numerically studied. The non-Markovian process shows its remarkable influence on the entanglement dynamics due to the sensitive time dependence of the dissipation and noise functions within the typical time scale of the environment. The Ohmic environment shows a weak dissipation-noise effect on the entanglement dynamics, while the sub-Ohmic and super-Ohmic environments induce much more severe noise. In particular, the memory of the system interacting with the environment contributes a strong decoherence effect to the entanglement dynamics in the super-Ohmic case

  20. Quantum simulation of an ultrathin body field-effect transistor with channel imperfections

    Science.gov (United States)

    Vyurkov, V.; Semenikhin, I.; Filippov, S.; Orlikovsky, A.

    2012-04-01

    An efficient program for the all-quantum simulation of nanometer field-effect transistors is elaborated. The model is based on the Landauer-Buttiker approach. Our calculation of transmission coefficients employs a transfer-matrix technique involving the arbitrary precision (multiprecision) arithmetic to cope with evanescent modes. Modified in such way, the transfer-matrix technique turns out to be much faster in practical simulations than that of scattering-matrix. Results of the simulation demonstrate the impact of realistic channel imperfections (random charged centers and wall roughness) on transistor characteristics. The Landauer-Buttiker approach is developed to incorporate calculation of the noise at an arbitrary temperature. We also validate the ballistic Landauer-Buttiker approach for the usual situation when heavily doped contacts are indispensably included into the simulation region.

  1. Optical reading of field-effect transistors by phase-space absorption quenching in a single InGaAs quantum well conducting channel

    Science.gov (United States)

    Chemla, D. S.; Bar-Joseph, I.; Klingshirn, C.; Miller, D. A. B.; Kuo, J. M.

    1987-03-01

    Absorption switching in a semiconductor quantum well by electrically varying the charge density in the quantum well conducting channel of a selectively doped heterostructure transistor is reported for the first time. The phase-space absorption quenching (PAQ) is observed at room temperature in an InGaAs/InAlAs grown on InP FET, and it shows large absorption coefficient changes with relatively broad spectral bandwidth. This PAQ is large enough to be used for direct optical determination of the logic state of the FET.

  2. Frequent food insecurity among injection drug users: correlates and concerns

    Directory of Open Access Journals (Sweden)

    Strike Carol

    2012-12-01

    Full Text Available Abstract Background Food insecurity and nutrition are two topics that are under-researched among injection drug users (IDUs. Our study examined the extent and correlates of food insecurity among a sample of IDUs and explored whether there is an association between food insecurity and injection-related HIV risk. Methods A cross-sectional survey was conducted using interviewer-administered questionnaires. Data were collected at a needle exchange program in London, Ontario, Canada between September 2006 and January 2007. Participants included 144 English-speaking IDUs who had injected drugs in the past 30 days. Participants were asked about their socio-demographic characteristics, HIV risk behaviours, food insecurity, and health/social service use. Results In the past 6 months, 54.5% of participants reported that on a daily/weekly basis they did not have enough to eat because of a lack of money, while 22.1% reported this type of food insecurity on a monthly basis. Moreover, 60.4% and 24.3% reported that they did not eat the quality or quantity of food they wanted on a daily/weekly or a monthly basis, respectively. Participants reported re-using someone else’s injection equipment: 21% re-used a needle, 19% re-used water, and 37.3% re-used a cooker. The odds of sharing injection equipment were increased for food insecure individuals. Conclusions Findings show that IDUs have frequent and variable experiences of food insecurity and these experiences are strongly correlated with sharing of injection-related equipment. Such behaviours may increase the likelihood of HIV and HCV transmission in this population. Addressing food-related needs among IDUs is urgently needed.

  3. Local Perspectives on Environmental Insecurity and Its Influence on Illegal Biodiversity Exploitation.

    Directory of Open Access Journals (Sweden)

    Meredith L Gore

    Full Text Available Environmental insecurity is a source and outcome of biodiversity declines and social conflict. One challenge to scaling insecurity reduction policies is that empirical evidence about local attitudes is overwhelmingly missing. We set three objectives: determine how local people rank risk associated with different sources of environmental insecurity; assess perceptions of environmental insecurity, biodiversity exploitation, myths of nature and risk management preferences; and explore relationships between perceptions and biodiversity exploitation. We conducted interviews (N = 88 with residents of Madagascar's Torotorofotsy Protected Area, 2014. Risk perceptions had a moderate effect on perceptions of environmental insecurity. We found no effects of environmental insecurity on biodiversity exploitation. Results offer one if not the first exploration of local perceptions of illegal biodiversity exploitation and environmental security. Local people's perception of risk seriousness associated with illegal biodiversity exploitation such as lemur hunting (low overall may not reflect perceptions of policy-makers (considered to be high. Discord is a key entry point for attention.

  4. Effects of work-family conflict and job insecurity on psychological distress.

    Science.gov (United States)

    Mutambudzi, M; Javed, Z; Kaul, S; Prochaska, J; Peek, M K

    2017-12-02

    Work-family conflict (WFC) and job insecurity are important determinants of workers' mental health. To examine the relationship between WFC and psychological distress, and the co-occurring effects of WFC and job insecurity on distress in US working adults. This study used cross-sectional data from the 2010 National Health Interview Survey (NHIS) for adults aged 18-64 years. The 2010 NHIS included occupational data from the National Institute for Occupational Safety and Health (NIOSH) sponsored Occupational Health Supplement. Logistic regression models were used to examine the independent and co-occurring effects of WFC and job insecurity on distress. The study group consisted of 12059 participants. In the model fully adjusted for relevant occupational, behavioural, sociodemographic and health covariates, WFC and job insecurity were independently significantly associated with increased odds of psychological distress. Relative to participants reporting WFC only, participants reporting no WFC and no job insecurity had lower odds of moderate and severe distress. Co-occurring WFC and job insecurity was associated with significantly higher odds of both moderate [odds ratio (OR) = 1.55; 95% confidence interval (CI) 1.25-1.9] and severe (OR = 3.57; 95% CI 2.66-4.79) distress. Rates of WFC and job insecurity were influenced by differing factors in working adults; however, both significantly increased risk of adverse mental health outcomes, particularly when experienced jointly. Future studies should explore the temporal association between co-occurring WFC and job insecurity and psychological distress. © The Author 2017. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  5. Consequences of job insecurity and the moderator role of occupational group.

    Science.gov (United States)

    Sora Miana, Beatriz; González-Morales, M Gloria; Caballer, Amparo; Peiró, José M

    2011-11-01

    In recent decades, transformations in organizations and the labour market have produced an increase in employee job insecurity. In response to this situation, workers present different negative reactions. However, the intensity of these reactions varies across studies that have investigated the outcomes of job insecurity. One possible explanation for this inconsistency may lie in the influence of other factors, such as the occupational group (Sverke et al., 2002). The aim of this study is to provide additional evidence about the relationship between job insecurity and its outcomes (i.e., life satisfaction, job satisfaction, perceived performance and organizational commitment), and examine the moderator role of occupational group in this relationship. The sample was composed of 321 employees from different Spanish organizations. The results showed that job insecurity was directly and negatively related to life satisfaction, job satisfaction and organizational commitment, and they suggest that occupational group moderated relations between job insecurity and three studied outcomes. In the case of life satisfaction and perceived performance, this relationship was stronger among blue collar workers. The relationship between job insecurity and job satisfaction was stronger in white collar workers. The implications and limitations of this study are discussed.

  6. The sudden death and sudden birth of quantum discord.

    Science.gov (United States)

    Xia, Wei; Hou, Jin-Xing; Wang, Xiao-Hui; Liu, Si-Yuan

    2018-03-28

    The interaction of quantum system and its environment brings out abundant quantum phenomenons. The sudden death of quantum resources, including entanglement, quantum discord and coherence, have been studied from the perspective of quantum breaking channels (QBC). QBC of quantum resources reveal the common features of quantum resources. The definition of QBC implies the relationship between quantum resources. However, sudden death of quantum resources can also appear under some other quantum channels. We consider the dynamics of Bell-diagonal states under a stochastic dephasing noise along the z-direction, and the sudden death and sudden birth of quantum discord are investigated. Next we explain this phenomenon from the geometric structure of quantum discord. According to the above results, the states with sudden death and sudden birth can be filtered in three-parameter space. Then we provide two necessary conditions to judge which kind of noise channels can make Bell-diagonal states sudden death and sudden birth. Moreover, the relation between quantum discord and coherence indicates that the sudden death and sudden birth of quantum discord implies the sudden death and sudden birth of coherence in an optimal basis.

  7. Household food insecurity is associated with low interferon-gamma levels in pregnant Indian women.

    Science.gov (United States)

    Vaidya, A; Bhosale, R; Sambarey, P; Suryavanshi, N; Young, S; Mave, V; Kanade, S; Kulkarni, V; Deshpande, P; Balasubramanian, U; Elf, J; Gupte, N; Gupta, A; Mathad, J S

    2017-07-01

    Over 20% of tuberculosis (TB) cases during pregnancy occur in India. To determine the association between household food insecurity and interferon-gamma (IFN-γ) levels in pregnancy. Pregnant women in India were administered the Household Food Insecurity Access Scale (HFIAS) questionnaire and underwent an IFN-γ release assay. Logistic regression was used to identify factors associated with food insecurity. Of 538 women, 60 (11%) had household food insecurity, 47 (78%) of which were moderate or severe food insecure. After mitogen stimulation, moderate or severe food insecure women had a median IFN-γ concentration of 4.2 IU/ml (IQR 2.2-9.8) vs. 8.4 IU/ml (IQR 3.0-10) in women with no or mild food insecurity (P = 0.03). In multivariate analysis, higher IFN-γ concentrations were associated with human immunodeficiency virus infection (OR 1.3, 95%CI 0.51-2.1, P = 0.001), and inversely associated with moderate or severe food insecurity (OR -1.6, 95%CI -2.9 to -0.27, P = 0.02) and the number of adults in the household (OR -0.08, 95%CI -0.16 to -0.01, P = 0.03). There was no association between food insecurity and IFN-γ response to Mycobacterium tuberculosis antigen. Food insecurity in pregnancy is associated with low IFN-γ levels. There was no association between food insecurity and IFN-γ response to M. tuberculosis antigen, but our study was underpowered to detect this outcome.

  8. Quantum internet using code division multiple access

    Science.gov (United States)

    Zhang, Jing; Liu, Yu-xi; Özdemir, Şahin Kaya; Wu, Re-Bing; Gao, Feifei; Wang, Xiang-Bin; Yang, Lan; Nori, Franco

    2013-01-01

    A crucial open problem inS large-scale quantum networks is how to efficiently transmit quantum data among many pairs of users via a common data-transmission medium. We propose a solution by developing a quantum code division multiple access (q-CDMA) approach in which quantum information is chaotically encoded to spread its spectral content, and then decoded via chaos synchronization to separate different sender-receiver pairs. In comparison to other existing approaches, such as frequency division multiple access (FDMA), the proposed q-CDMA can greatly increase the information rates per channel used, especially for very noisy quantum channels. PMID:23860488

  9. Eavesdropping on the two-way quantum communication protocols with invisible photons

    Energy Technology Data Exchange (ETDEWEB)

    Cai Qingyu [State Key Laboratory of Magnetics Resonance and Atomic and Molecular Physics, Wuhan Institution of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)]. E-mail: qycai@wipm.ac.cn

    2006-02-20

    The crucial issue of quantum communication protocol is its security. In this Letter, we show that all the deterministic and direct two-way quantum communication protocols, sometimes called ping-pong (PP) protocols, are insecure when an eavesdropper uses the invisible photon to eavesdrop on the communication. With our invisible photon eavesdropping (IPE) scheme, the eavesdropper can obtain full information of the communication with zero risk of being detected. We show that this IPE scheme can be implemented experimentally with current technology. Finally, a possible improvement of PP communication protocols security is proposed00.

  10. Eavesdropping on the two-way quantum communication protocols with invisible photons

    International Nuclear Information System (INIS)

    Cai Qingyu

    2006-01-01

    The crucial issue of quantum communication protocol is its security. In this Letter, we show that all the deterministic and direct two-way quantum communication protocols, sometimes called ping-pong (PP) protocols, are insecure when an eavesdropper uses the invisible photon to eavesdrop on the communication. With our invisible photon eavesdropping (IPE) scheme, the eavesdropper can obtain full information of the communication with zero risk of being detected. We show that this IPE scheme can be implemented experimentally with current technology. Finally, a possible improvement of PP communication protocols security is proposed

  11. Food insecurity and mental health problems among a community sample of young adults.

    Science.gov (United States)

    Pryor, Laura; Lioret, Sandrine; van der Waerden, Judith; Fombonne, Éric; Falissard, Bruno; Melchior, Maria

    2016-08-01

    Food insecurity has been found to be related to anxiety and depression; however, the association with other psychiatric disorders, particularly among young adults, is not well known. We examined whether food insecurity is independently associated with four common mental health problems among a community sample of young adults in France. Data are from the TEMPO longitudinal cohort study. In 1991, participants' parents provided information on health and family socioeconomic characteristics. In 2011, participants' (18-35 years) reported food insecurity, mental health symptoms, and socioeconomic conditions (n = 1214). Mental health problems ascertained included major depressive episode, suicidal ideation, attention deficit and hyperactivity disorder, and substance abuse and/or dependence (nicotine, alcohol and cannabis). Cross-sectional associations between food insecurity and mental health problems were tested using modified Poisson regressions, weighted by inverse probability weights (IPW) of exposure. This makes food insecure and not food insecure participants comparable on all characteristics including socioeconomic factors and past mental health problems. 8.5 % of young adults were food insecure. In IPW-controlled analyses, food insecurity was associated with increased levels of depression (RR = 2.01, 95 % CI 1.01-4.02), suicidal ideation (RR = 3.23, 95 % CI 1.55-6.75) and substance use problems (RR = 1.68, 95 % CI 1.15-2.46). Food insecurity co-occurs with depression, suicidal ideation and substance use problems in young adulthood. Our findings suggest that reductions in food insecurity during this important life period may help prevent mental health problems. Policies aiming to alleviate food insecurity should also address individuals' psychiatric problems, to prevent a lifelong vicious circle of poor mental health and low socioeconomic attainment.

  12. Quantum Secure Direct Communication with Quantum Memory.

    Science.gov (United States)

    Zhang, Wei; Ding, Dong-Sheng; Sheng, Yu-Bo; Zhou, Lan; Shi, Bao-Sen; Guo, Guang-Can

    2017-06-02

    Quantum communication provides an absolute security advantage, and it has been widely developed over the past 30 years. As an important branch of quantum communication, quantum secure direct communication (QSDC) promotes high security and instantaneousness in communication through directly transmitting messages over a quantum channel. The full implementation of a quantum protocol always requires the ability to control the transfer of a message effectively in the time domain; thus, it is essential to combine QSDC with quantum memory to accomplish the communication task. In this Letter, we report the experimental demonstration of QSDC with state-of-the-art atomic quantum memory for the first time in principle. We use the polarization degrees of freedom of photons as the information carrier, and the fidelity of entanglement decoding is verified as approximately 90%. Our work completes a fundamental step toward practical QSDC and demonstrates a potential application for long-distance quantum communication in a quantum network.

  13. Food Insecurity and Family Well-Being Outcomes among Households with Young Children.

    Science.gov (United States)

    Johnson, Anna D; Markowitz, Anna J

    2018-05-01

    To investigate associations between household food insecurity and multiple family well-being variables in an effort to illuminate previously understudied, policy-amenable mechanisms through which food insecurity threatens healthy development. Data are drawn from the nationally representative Early Childhood Longitudinal Study-Birth Cohort. The Early Childhood Longitudinal Study-Birth Cohort contains longitudinal data on household food insecurity and several family well-being factors including maternal physical and mental health, positive parenting practices and disciplinary strategies, and frequency and severity of spousal conflict. We use regression models with lagged dependent variables to estimate associations between food insecurity and family well-being outcomes, on a subsample of low-income families (N ≈ 2100-4700). Household food insecurity was significantly associated with poorer maternal physical health; increased depressive symptoms and use of harsh discipline strategies; and greater frequency and negativity of conflict between parents. Associations were strongest and most consistent when children were preschool aged. Transitions into food insecurity between toddlerhood and preschool were also associated with significantly worse parental physical and mental health outcomes, and more family conflict, with similar though slightly weaker and less consistent associations for transitioning into food insecurity between infancy and toddlerhood. Food insecurity is associated with significant decreases in family health and well-being. Clinicians and other public health officials play a critical role in assessing risk for children and families, and linking families with supportive services. Screening families experiencing or at risk for food insecurity and connecting them with resources is an avenue through which public health practitioners can support family health. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Small holder farmers coping strategies to household food insecurity ...

    African Journals Online (AJOL)

    Small holder farmers coping strategies to household food insecurity and hunger in Southern Ethiopia. ... Ethiopian Journal of Environmental Studies and Management ... The study further showed that households in the study area employ a range of coping strategies to respond to the high and sustained food insecurity and ...

  15. The cognitive/affective distinction of job insecurity: Validation and ...

    African Journals Online (AJOL)

    We administered a short version of the measure of job insecurity originally devised by De Witte (2000), which distinguishes between cognitive and affective job insecurity. Data on job satisfaction, commitment, psychological ill-health and emotional exhaustion were also gathered from employees in a variety of South African ...

  16. Universal quantum interfaces

    International Nuclear Information System (INIS)

    Lloyd, Seth; Landahl, Andrew J.; Slotine, Jean-Jacques E.

    2004-01-01

    To observe or control a quantum system, one must interact with it via an interface. This article exhibits simple universal quantum interfaces--quantum input/output ports consisting of a single two-state system or quantum bit that interacts with the system to be observed or controlled. It is shown that under very general conditions the ability to observe and control the quantum bit on its own implies the ability to observe and control the system itself. The interface can also be used as a quantum communication channel, and multiple quantum systems can be connected by interfaces to become an efficient universal quantum computer. Experimental realizations are proposed, and implications for controllability, observability, and quantum information processing are explored

  17. Food and nutrition insecurity: a marker of vulnerability to asthma symptoms.

    Science.gov (United States)

    Ribeiro-Silva, Rita de Cássia; Oliveira-Assis, Ana Marlúcia; Junqueira, Samuel Badaró; Fiaccone, Rosemeire Leovigildo; Dos Santos, Sandra Maria Chaves; Barreto, Maurício Lima; de Jesus Pinto, Elizabete; da Silva, Luce Alves; Rodrigues, Laura Cunha; Alcantara-Neves, Neuza Maria

    2014-01-01

    To evaluate the association between food and nutrition insecurity and asthma in children from Latin America. Cross-sectional study. São Francisco do Conde, Bahia, north-eastern Brazil. The study included 1307 children aged 6-12 years from public elementary schools. Asthma symptoms were collected using a questionnaire that was translated and adapted from the International Study of Asthma and Allergies in Childhood, phase III. The diagnosis of asthma was determined based on reports of wheezing in the previous 12 months. The Brazilian Food Insecurity Scale was used to identify food insecurity. We also obtained demographic, socio-economic and anthropometric information for each participant. We used multivariate logistic regression analyses to assess the associations of interest. Of the children surveyed, 10·4% had a history of wheezing and 64·5% had some degree of food and nutrition insecurity. We found a positive dose-response relationship and statistically significant associations of asthma with moderate (OR = 1·71, 95% CI 1·01, 2·89) and severe (OR = 2·51, 95% CI 1·28, 4·93) food and nutrition insecurity. The results show that moderate and severe food and nutrition insecurity are markers of vulnerability to wheezing. It is important to note that the results of studies in this field have potential implications for social policies that promote food security. Further studies to identify the mechanisms involved in the relationship between food and nutrition insecurity and asthma are needed.

  18. On the possibility of a quantum bremsstrahlung induced self-modulation of a relativistic beam channeling in crystals

    International Nuclear Information System (INIS)

    Vysotskij, V.I.; Vorontsov, V.I.; Kuz'min, R.N.

    1987-01-01

    Physical predictions and quantitative estimations of a new physical effect - the phenomenon of quantum bremsstrahlung induced selfmodulation of a fast beam channeling in the crystals are considered and carried out. The occurrence of induced self-modulation results from nonstationary interference of proper waves of a channeled particle in the range of mutual coherence and with account of difference of selective bremsstrahlung losses of these waves. The modulation frequency for superrelativistic particles is shown to lie within the range from soft X-ray to hard gamma range. It proceeds from the estimations that modulation at these frequencies is preserved within the limits of macroscopically large ranges after the crystal attaining several meters. The maximum frequency of modulation for nonrelativistic heavy particles (protons) corresponds to the optical range

  19. Food Insecurity and Chronic Disease: Addressing Food Access as a Healthcare Issue.

    Science.gov (United States)

    Decker, Dominic; Flynn, Mary

    2018-05-01

    Food insecurity, or lack of access to nutritionally adequate food, affects millions of US households every year. Food insecure individuals face disproportionately higher rates of chronic diseases, like diabetes mellitus and HIV/AIDS, and therefore accrue more healthcare costs. This puts into motion a cycle of disease and expense that furthers disparities between food secure and insecure patients. Our aim is to provide an overview of food insecurity, define its link to chronic disease and offer practical solutions for addressing this growing problem. [Full article available at http://rimed.org/rimedicaljournal-2018-05.asp].

  20. Current-voltage characteristics of quantum-point contacts in the closed-channel regime: Transforming the bias voltage into an energy scale

    DEFF Research Database (Denmark)

    Gloos, K.; Utko, P.; Aagesen, M.

    2006-01-01

    We investigate the I(V) characteristics (current versus bias voltage) of side-gated quantum-point contacts, defined in GaAs/AlxGa1-xAs heterostructures. These point contacts are operated in the closed-channel regime, that is, at fixed gate voltages below zero-bias pinch-off for conductance. Our....... Such a built-in energy-voltage calibration allows us to distinguish between the different contributions to the electron transport across the pinched-off contact due to thermal activation or quantum tunneling. The first involves the height of the barrier, and the latter also its length. In the model that we...

  1. Quantum model for a periodically driven selectivity filter in a K+ ion channel

    International Nuclear Information System (INIS)

    Cifuentes, A A; Semião, F L

    2014-01-01

    In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions through the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlled time-dependent external field, which changes the free-energy scenario and consequently the conduction of the ions. In particular, we demonstrate that the two-pathway conduction mechanism is more advantageous for the filter when dephasing in the transient configurations is lower than in the main configurations. As a matter of fact, K + ions in the main configurations are highly coordinated by oxygen atoms of the filter backbone, and this increases noise. Moreover, we also show that for a wide range of dephasing rates and driving frequencies, the two-pathway conduction used by the filter leads to higher ionic currents than the single–path model. (paper)

  2. Manager Characteristics and Employee Job Insecurity around a Merger Announcement: The Role of Status and Crossover

    Science.gov (United States)

    Lam, Jack; Fox, Kimberly; Fan, Wen; Moen, Phyllis; Kelly, Erin; Hammer, Leslie; Kossek, Ellen

    2014-01-01

    Most existing research theorizes individual factors as predictors of perceived job insecurity. Incorporating contextual and organizational factors at an information technology organization where a merger was announced during data collection, we draw on status expectations and crossover theories to investigate whether managers’ characteristics and insecurity shape their employees’ job insecurity. We find having an Asian as opposed to a White manager is associated with lower job insecurity, while managers’ own insecurity positively predicts employees’ insecurity. Also contingent on the organizational climate, managers’ own tenure buffers, and managers’ perceived job insecurity magnifies insecurity of employees interviewed after a merger announcement, further specifying status expectations theory by considering context. PMID:26190868

  3. Household Food Insecurity, Mother's Feeding Practices, and the Early Childhood's Iron Status.

    Science.gov (United States)

    Salarkia, Nahid; Neyestani, Tirang R; Omidvar, Nasrin; Zayeri, Farid

    2015-01-01

    Health consequences of food insecurity among infants and toddlers have not been fully examined. The purpose of this study was to assess the relationship between household food insecurity, mother's infant feeding practices and iron status of 6-24 months children. In this cross-sectional study, 423 mother-child pairs were randomly selected by multistage sampling method. Children blood samples were analyzed for hemoglobin and serum ferritin concentrations. Household food security was evaluated using a validated Household Food Insecurity Access Scale. The mother's feeding practices were evaluated using Infant and Young Child Feeding practice variables including: The duration of breastfeeding and the time of introducing of complementary feeding. Based on the results, of the studied households only 47.7% were food secure. Mild and moderate-severe household food insecurity was 39.5% and 12.8%, respectively. Anemia, iron deficiency (ID), and iron deficiency anemia were seen in 29.1%, 12.2%, and 4.8% of children, respectively. There was no significant association between household food insecurity; mother's feeding practices and child ID with or without anemia. We found no association between household food insecurity and the occurrence of anemia in the 6-24 months children. However, these findings do not rule out the possibility of other micronutrient deficiencies among the food-insecure household children.

  4. Breaking Gaussian incompatibility on continuous variable quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Heinosaari, Teiko, E-mail: teiko.heinosaari@utu.fi [Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Kiukas, Jukka, E-mail: jukka.kiukas@aber.ac.uk [Department of Mathematics, Aberystwyth University, Penglais, Aberystwyth, SY23 3BZ (United Kingdom); Schultz, Jussi, E-mail: jussi.schultz@gmail.com [Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Dipartimento di Matematica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

    2015-08-15

    We characterise Gaussian quantum channels that are Gaussian incompatibility breaking, that is, transform every set of Gaussian measurements into a set obtainable from a joint Gaussian observable via Gaussian postprocessing. Such channels represent local noise which renders measurements useless for Gaussian EPR-steering, providing the appropriate generalisation of entanglement breaking channels for this scenario. Understanding the structure of Gaussian incompatibility breaking channels contributes to the resource theory of noisy continuous variable quantum information protocols.

  5. Tema con variazioni: quantum channel capacity

    Science.gov (United States)

    Kretschmann, Dennis; Werner, Reinhard F.

    2004-02-01

    Channel capacity describes the size of the nearly ideal channels, which can be obtained from many uses of a given channel, using an optimal error correcting code. In this paper we collect and compare minor and major variations in the mathematically precise statements of this idea which have been put forward in the literature. We show that all the variations considered lead to equivalent capacity definitions. In particular, it makes no difference whether one requires mean or maximal errors to go to zero, and it makes no difference whether errors are required to vanish for any sequence of block sizes compatible with the rate, or only for one infinite sequence.

  6. Secure quantum key distribution using squeezed states

    International Nuclear Information System (INIS)

    Gottesman, Daniel; Preskill, John

    2001-01-01

    We prove the security of a quantum key distribution scheme based on transmission of squeezed quantum states of a harmonic oscillator. Our proof employs quantum error-correcting codes that encode a finite-dimensional quantum system in the infinite-dimensional Hilbert space of an oscillator, and protect against errors that shift the canonical variables p and q. If the noise in the quantum channel is weak, squeezing signal states by 2.51 dB (a squeeze factor e r =1.34) is sufficient in principle to ensure the security of a protocol that is suitably enhanced by classical error correction and privacy amplification. Secure key distribution can be achieved over distances comparable to the attenuation length of the quantum channel

  7. Healing and/or breaking? The mental health implications of repeated economic insecurity.

    Science.gov (United States)

    Watson, Barry; Osberg, Lars

    2017-09-01

    Current literature confirms the negative consequences of contemporaneous economic insecurity for mental health, but ignores possible implications of repeated insecurity. This paper asks how much a person's history of economic insecurity matters for psychological distress by contrasting the implications of two models. Consistent with the health capital literature, the Healing model suggests psychological distress is a stock variable affected by shocks from life events, with past events having less impact than more recent shocks. Alternatively, the Breaking Point model considers that high levels of distress represent a distinct shift in life state, which occurs if the accumulation of past life stresses exceeds some critical value. Using five cycles of Canadian National Population Health Survey data (2000-2009), we model the impact of past economic insecurity shocks on current psychological distress in a way that can distinguish between these hypotheses. In our sample of 1775 males and 1883 females aged 25 to 64, we find a robust healing effect for one-time economic insecurity shocks. For males, only a recent one-time occurrence of economic insecurity is predictive of higher current psychological distress (0.19 standard deviations). Moreover, working age adults tend to recover from past accumulated experiences of economic insecurity if they were recently economically secure. However, consistent with the Breaking Point hypothesis, males experiencing three or four cycles of recent insecurity are estimated to have a level of current psychological distress that is 0.26-0.29 standard deviations higher than those who were employed and job secure throughout the same time period. We also find, consistent with other literature, distinct gender differences - for working age females, all economic insecurity variables are statistically insignificant at conventional levels. Our results suggest that although Canadians are resilient to one-time insecurity shocks, males most

  8. Food insecurity and children's mental health: a prospective birth cohort study.

    Directory of Open Access Journals (Sweden)

    Maria Melchior

    Full Text Available Food insecurity (which can be defined as inadequate access to sufficient, safe, and nutritious food that meets individuals' dietary needs is concurrently associated with children's psychological difficulties. However, the predictive role of food insecurity with regard to specific types of children's mental health symptoms has not previously been studied. We used data from the Longitudinal Study of Child Development in Québec, LSCDQ, a representative birth cohort study of children born in the Québec region, in Canada, in 1997-1998 (n = 2120. Family food insecurity was ascertained when children were 1½ and 4½ years old. Children's mental health symptoms were assessed longitudinally using validated measures of behaviour at ages 4½, 5, 6 and 8 years. Symptom trajectory groups were estimated to identify children with persistently high levels of depression/anxiety (21.0%, aggression (26.2%, and hyperactivity/inattention (6.0%. The prevalence of food insecurity in the study was 5.9%. In sex-adjusted analyses, children from food-insecure families were disproportionately likely to experience persistent symptoms of depression/anxiety (OR: 1.79, 95% CI 1.15-2.79 and hyperactivity/inattention (OR: 3.06, 95% CI 1.68-5.55. After controlling for immigrant status, family structure, maternal age at child's birth, family income, maternal and paternal education, prenatal tobacco exposure, maternal and paternal depression and negative parenting, only persistent hyperactivity/inattention remained associated with food insecurity (fully adjusted OR: 2.65, 95% CI 1.16-6.06. Family food insecurity predicts high levels of children's mental health symptoms, particularly hyperactivity/inattention. Addressing food insecurity and associated problems in families could help reduce the burden of mental health problems in children and reduce social inequalities in development.

  9. Sub-micrometer fluidic channel for measuring photon emitting entities

    Science.gov (United States)

    Stavis, Samuel M; Edel, Joshua B; Samiee, Kevan T; Craighead, Harold G

    2014-11-18

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  10. Quantum photonic network and physical layer security.

    Science.gov (United States)

    Sasaki, Masahide; Endo, Hiroyuki; Fujiwara, Mikio; Kitamura, Mitsuo; Ito, Toshiyuki; Shimizu, Ryosuke; Toyoshima, Morio

    2017-08-06

    Quantum communication and quantum cryptography are expected to enhance the transmission rate and the security (confidentiality of data transmission), respectively. We study a new scheme which can potentially bridge an intermediate region covered by these two schemes, which is referred to as quantum photonic network. The basic framework is information theoretically secure communications in a free space optical (FSO) wiretap channel, in which an eavesdropper has physically limited access to the main channel between the legitimate sender and receiver. We first review a theoretical framework to quantify the optimal balance of the transmission efficiency and the security level under power constraint and at finite code length. We then present experimental results on channel characterization based on 10 MHz on-off keying transmission in a 7.8 km terrestrial FSO wiretap channel.This article is part of the themed issue 'Quantum technology for the 21st century'. © 2017 The Author(s).

  11. Accounting for Water Insecurity in Modeling Domestic Water Demand

    Science.gov (United States)

    Galaitsis, S. E.; Huber-lee, A. T.; Vogel, R. M.; Naumova, E.

    2013-12-01

    Water demand management uses price elasticity estimates to predict consumer demand in relation to water pricing changes, but studies have shown that many additional factors effect water consumption. Development scholars document the need for water security, however, much of the water security literature focuses on broad policies which can influence water demand. Previous domestic water demand studies have not considered how water security can affect a population's consumption behavior. This study is the first to model the influence of water insecurity on water demand. A subjective indicator scale measuring water insecurity among consumers in the Palestinian West Bank is developed and included as a variable to explore how perceptions of control, or lack thereof, impact consumption behavior and resulting estimates of price elasticity. A multivariate regression model demonstrates the significance of a water insecurity variable for data sets encompassing disparate water access. When accounting for insecurity, the R-squaed value improves and the marginal price a household is willing to pay becomes a significant predictor for the household quantity consumption. The model denotes that, with all other variables held equal, a household will buy more water when the users are more water insecure. Though the reasons behind this trend require further study, the findings suggest broad policy implications by demonstrating that water distribution practices in scarcity conditions can promote consumer welfare and efficient water use.

  12. Is Insecurity Worse for Well-Being in Turbulent Times? Mental Health in Context

    Science.gov (United States)

    Lam, Jack; Fan, Wen; Moen, Phyllis

    2014-01-01

    Using General Social Survey data, we examine whether any association between job insecurity and well-being is contingent on economic climate (comparing those interviewed in turbulent 2010 vs. pre-recessionary 2006), as well as income and gender. We find respondents with higher levels of job insecurity in 2010 reported lower levels of happiness compared to those similarly insecure in 2006. The positive relationship between job insecurity and days of poor mental health becomes more pronounced for those in the 3rd quartile of personal income in 2010, suggesting middle-class vulnerability during the economic downturn. Men (but not women) with higher insecurity report more days of poor mental health in both 2006 and 2010. These findings reinforce a “cycles of control” theoretical approach, given the mental health-job insecurity relationship is heightened for workers in turbulent times. PMID:25436177

  13. An environment-mediated quantum deleter

    International Nuclear Information System (INIS)

    Srikanth, R.; Banerjee, Subhashish

    2007-01-01

    Environment-induced decoherence presents a great challenge to realizing a quantum computer. We point out the somewhat surprising fact that decoherence can be useful, indeed necessary, for practical quantum computation, in particular, for the effective erasure of quantum memory in order to initialize the state of the quantum computer. The essential point behind the deleter is that the environment, by means of a dissipative interaction, furnishes a contractive map towards a pure state. We present a specific example of an amplitude damping channel provided by a two-level system's interaction with its environment in the weak Born-Markov approximation. This is contrasted with a purely dephasing, non-dissipative channel provided by a two-level system's interaction with its environment by means of a quantum nondemolition interaction. We point out that currently used state preparation techniques, for example using optical pumping, essentially perform as quantum deleters

  14. Hard to Stomach: Food Insecurity and Inequitable Access to Nutritious Food in Vancouver

    OpenAIRE

    Moe, Jennifer Lauren

    2014-01-01

    Food insecurity is a problem in Vancouver, BC. Through analysis of the systemic causes and negative correlates of food insecurity, this study examines effective ways to mitigate food insecurity in Vancouver by enabling consistent access to sufficient, nutritious food. Assessments of the economics of food insecurity and multi-level governmental positions on the issue provide a theoretical and practical basis for the research. A literature review and four in-depth stakeholder interviews identif...

  15. Household water insecurity after a historic flood: Diarrhea and dehydration in the Bolivian Amazon.

    Science.gov (United States)

    Rosinger, Asher Y

    2018-01-01

    While 884 million people worldwide lack access to clean water, millions live in flood-prone regions. Unexpected flooding increases risk of diarrheal diseases and is expected to occur with increased frequency in the 21st century. Water insecurity is linked to mental distress in water scarce regions, yet this construct has not been examined closely among populations living in flood-prone regions. This paper examines how differences in water sources and lifestyle among Tsimane' forager-horticulturalists in lowland Bolivia are related to water insecurity after a historic flood in 2014, and in turn, how water insecurity is associated with diarrhea and dehydration. Pre-flood data come from qualitative interviews with 36 household heads, anthropometrics, participant observation, and water quality analysis between September 2013-January 2014 used to create a locally-adapted water insecurity questionnaire. Water insecurity was measured after the historic flood; no pre-flood water insecurity measures are available. Post-flood data were collected through surveys, water quality analysis, and health exams using near-exhaustive sampling in two villages, yielding 118 adults and 115 children (aged 2-12 years) in 62 households between March-April 2014. Overall, 89% of adults reported medium or high water insecurity. Only hand-pumps tested negative for pathogenic bacteria both pre- and post-flood. Tobit regressions suggest that hand-pumps (when available) and adult age were associated with lower water insecurity scores. Multiple logistic regressions suggest that adults with high water insecurity were more likely to report diarrhea than adults with low (Odds Ratio [OR] 9.2; 95% CI: 1.27-67.1). Children from households with medium (OR: 6.8; 95% CI: 1.41-32.5) or high (OR: 14.0; 95% CI: 2.40-81.5) water insecurity had significantly higher odds of dehydration than children in households with low water insecurity. Catastrophic flooding may systematically increase dimensions of household

  16. Understanding Food Insecurity in the USA and Canada: Potential Insights for Europe.

    Science.gov (United States)

    Gundersen, Craig

    2016-01-01

    Food insecurity is a leading nutrition-related health care issue in the USA due to the magnitude of the problem (almost 50 million Americans are food insecure) and its association with a wide array of negative health and other outcomes. Alongside this interest in the USA, there has also been growing interest in Canada. In contrast, food insecurity has received less attention in Europe. Nevertheless, there is both direct and indirect evidence that food insecurity and its attendant consequences are present in Europe. Given the similarities between the USA, Canada, and Europe, previous research can offer numerous insights into the causes and consequences of food insecurity in Europe and possible directions to address these through measurement and public policies. I first cover the methods used to measure food insecurity in the USA and Canada. In both countries, a series of 18 questions in the Core Food Security Module are used to identify whether a household is food insecure. I then briefly cover the current extent of food insecurity in each country along with some discussion of the recent history of food insecurity. A central advantage to using the Core Food Security Module in Europe is that the measure has been proven useful in other high-income countries, and using a standardized measure would allow for cross-country comparisons. I next cover two large-scale food assistance programs from the USA, the Supplemental Nutrition Assistance Program (formerly known as the Food Stamp Program) and the National School Lunch Program. For each, I summarize how the program is structured, how eligibility is established, and how participation proceeds. Europe has generally used income-based assistance programs to improve the well-being of low-income households; I consider a couple of reasons for why food assistance programs may also be worth considering. © 2016 S. Karger AG, Basel.

  17. Policy Approaches to Offset Childhood Food Insecurity and Obesity

    Science.gov (United States)

    Broberg, Danielle M.; Broberg, Katharine A.; McGuire, Jenifer K.

    2009-01-01

    Policies originally designed to address food insecurity are in need of revision due to rising rates of obesity among those they serve. Within the context of national policies, this article uses an ecological perspective to consider the links between food insecurity and obesity. The recommendations include adjusting the nutritional standards of the…

  18. The Temporal Impact of Economic Insecurity on Child Maltreatment: A Systematic Review.

    Science.gov (United States)

    Conrad-Hiebner, Aislinn; Byram, Elizabeth

    2018-01-01

    Economically insecure children experience 3-9 times more maltreatment than economically secure children. Although economic insecurity is associated with child physical abuse, neglect, and psychological maltreatment, there have been no systematic reviews dedicated to the relation between familial economic insecurity and child maltreatment. This is problematic because multiple forms of familial economic insecurity-including debt, material hardship, income, unemployment, and income transfers-are related to child maltreatment. These findings, however, are not causal or reliably replicated across studies. Until we identify the state of the evidence concerning the temporal association between economic insecurity and child maltreatment, our ability to reduce child maltreatment may be limited. In this systematic review (PROSPERO registration # CRD42017081445), we searched PsycINFO, PubMed, Scopus, ProQuest Dissertations, and the gray literature for English-language, peer-reviewed articles and dissertations published between 1970 and 2016. We synthesized evidence from 26 longitudinal studies on the temporal relation between economic insecurity and child maltreatment. Income losses, cumulative material hardship, and housing hardship were the most reliable predictors of child maltreatment. Implications for research, policy, and practice are discussed.

  19. Factors associated with child hunger among food insecure households in Bangladesh.

    Science.gov (United States)

    Haque, Md Ahshanul; Farzana, Fahmida Dil; Sultana, Sabiha; Raihan, Mohammad Jyoti; Rahman, Ahmed Shafiqur; Waid, Jillian L; Choudhury, Nuzhat; Ahmed, Tahmeed

    2017-02-16

    Hunger is associated with food insecurity at the household level and is considered as a global public health problem with long term adverse consequences on children's health. This study aims to determine the factors associated with child hunger from a nationally representative sample in Bangladesh among food insecure households. Data was derived from the Food Security and Nutritional Surveillance Project; 14,712 children aged 6-59 months belonging to food insecure households contributed to the analysis. Information on food security at the household level was collected for 30 days preceding the survey. Descriptive statistics served to illustrate the variables studied and multiple logistic regression analysis was conducted to identify the significant risk factors for child hunger. Overall 10% of the children were found to be hungry. After adjusting for seasonality, residence type and education level of household head, the variables - female headed households [OR: 1.87 (1.43-2.45); p hunger. Out of the potential risk factors examined, our study found significant and independent association of five variables with child hunger: sex of the household head, household food insecurity status, educational status of household women and asset index. Despite all sampled household being food insecure, degree of household food insecurity status appeared to be the strongest predictor of child hunger.

  20. Obesity and household food insecurity: evidence from a sample of rural households in Malaysia.

    Science.gov (United States)

    Shariff, Z Mohd; Khor, G L

    2005-09-01

    The study examined nutritional outcomes related to body fat accumulation of food insecurity among women from selected rural communities in Malaysia. Cross-sectional study. Rural communities (seven villages and two palm plantations) in a district with high percentage of welfare recipients. Malay (n = 140) and Indian (n = 60) women were interviewed and measured for demographic, socioeconomic, anthropometric, dietary and physical activity information. The women were measured for their body mass index and waist circumference (WC). Energy and nutrient intakes, food group intake and food variety score were analyzed from 24 h dietary recalls and food-frequency questionnaire. Daily physical activity of the women was examined as the number of hours spent in economic, domestic, leisure and sport activities. Using the Radimer/Cornell Hunger and Food Insecurity Instrument, 58% of the women reported some degree of food insecurity (household insecure 14%, adult insecure 9.5% and child hunger 34.5%). In general, food-insecure women had lower years of education, household income and income per capita, more children and mothers as housewives. More than 50% of food-insecure women were overweight and obese than women from food-secure households (38%). Similarly, more food-insecure women (32-47%) had at-risk WC (> or = 88 cm) than food-secure women (29%). Food-insecure women spent significantly more time in domestic and leisure activities than food-secure women. Overweight and abdominal adiposity among the women were associated with a number of independent variables, such as women as housewives, women with more children, larger household size, food insecurity, shorter time spent in economic activities, longer time spent in leisure activities and lower food variety score. After adjusting for factors that are related to both adiposity and food insecurity, women from food-insecure households were significantly more likely to have at-risk WC, but not obese. Among this sample of rural

  1. Resilience and (in)security

    DEFF Research Database (Denmark)

    dunn cavelty, myriam; Kaufmann, Mareile; Kristensen, Kristian Søby

    2015-01-01

    , and redefine relations of security and insecurity. We show the increased attention – scholarly as well as political – given to resilience in recent times and provide a review of the state of critical security studies literature on resilience. We argue that to advance this discussion, resilience needs...

  2. The effect of quantum memory on quantum games

    International Nuclear Information System (INIS)

    Ramzan, M; Nawaz, Ahmad; Toor, A H; Khan, M K

    2008-01-01

    We study quantum games with correlated noise through a generalized quantization scheme. We investigate the effects of memory on quantum games, such as Prisoner's Dilemma, Battle of the Sexes and Chicken, through three prototype quantum-correlated channels. It is shown that the quantum player enjoys an advantage over the classical player for all nine cases considered in this paper for the maximally entangled case. However, the quantum player can also outperform the classical player for subsequent cases that can be noted in the case of the Battle of the Sexes game. It can be seen that the Nash equilibria do not change for all the three games under the effect of memory

  3. Improved Multipartite Quantum Secret Sharing Protocol Using Preshared Greenberger-Horne-Zeilinger States

    International Nuclear Information System (INIS)

    Xie Deng; Ye Mingyong; Li Xinghua

    2011-01-01

    Inspired by the protocol presented by Bagherinezhad and Karimipour [Phys. Rev. A 67 (2003) 044302], which will be shown to be insecure, we present a multipartite quantum secret sharing protocol using reusable Greenberger-Horne-Zeilinger (GHZ) states. This protocol is robust against eavesdropping and could be used for the circumstance of many parties. (general)

  4. A high-speed, reconfigurable, channel- and time-tagged photon arrival recording system for intensity-interferometry and quantum optics experiments

    Science.gov (United States)

    Girish, B. S.; Pandey, Deepak; Ramachandran, Hema

    2017-08-01

    We present a compact, inexpensive multichannel module, APODAS (Avalanche Photodiode Output Data Acquisition System), capable of detecting 0.8 billion photons per second and providing real-time recording on a computer hard-disk, of channel- and time-tagged information of the arrival of upto 0.4 billion photons per second. Built around a Virtex-5 Field Programmable Gate Array (FPGA) unit, APODAS offers a temporal resolution of 5 nanoseconds with zero deadtime in data acquisition, utilising an efficient scheme for time and channel tagging and employing Gigabit ethernet for the transfer of data. Analysis tools have been developed on a Linux platform for multi-fold coincidence studies and time-delayed intensity interferometry. As illustrative examples, the second-order intensity correlation function ( g 2) of light from two commonly used sources in quantum optics —a coherent laser source and a dilute atomic vapour emitting spontaneously, constituting a thermal source— are presented. With easy reconfigurability and with no restriction on the total record length, APODAS can be readily used for studies over various time scales. This is demonstrated by using APODAS to reveal Rabi oscillations on nanosecond time scales in the emission of ultracold atoms, on the one hand, and, on the other hand, to measure the second-order correlation function on the millisecond time scales from tailored light sources. The efficient and versatile performance of APODAS promises its utility in diverse fields, like quantum optics, quantum communication, nuclear physics, astrophysics and biology.

  5. Validating operational food insecurity indicators against a dynamic benchmark : evidence from Mali

    OpenAIRE

    Christiaensen, Luc J.; Boisvert, Richard N.; Hoddinott, John

    2000-01-01

    The authors develop an explicitly forward-looking indicator of food insecurity that takes into account both current dietary inadequacy and vulnerability to dietary inadequacy in the future. Application of this measure to data from northern Mali shows that neglecting the future dimension of food insecurity causes serious underestimation of food insecurity in this area. The authors evaluate ...

  6. Quantum hacking of two-way continuous-variable quantum key distribution using Trojan-horse attack

    Science.gov (United States)

    Ma, Hong-Xin; Bao, Wan-Su; Li, Hong-Wei; Chou, Chun

    2016-08-01

    We present a Trojan-horse attack on the practical two-way continuous-variable quantum key distribution system. Our attack mainly focuses on the imperfection of the practical system that the modulator has a redundancy of modulation pulse-width, which leaves a loophole for the eavesdropper inserting a Trojan-horse pulse. Utilizing the unique characteristics of two-way continuous-variable quantum key distribution that Alice only takes modulation operation on the received mode without any measurement, this attack allows the eavesdropper to render all of the final keys shared between the legitimate parties insecure without being detected. After analyzing the feasibility of the attack, the corresponding countermeasures are put forward. Project supported by the National Basic Research Program of China (Grant No. 2013CB338002) and the National Natural Science Foundation of China (Grant Nos. 11304397 and 61505261).

  7. Addressing Household Food Insecurity in Canada - Position Statement and Recommendations - Dietitians of Canada.

    Science.gov (United States)

    2016-09-01

    POSITION STATEMENT It is the position of Dietitians of Canada that household food insecurity is a serious public health issue with profound effects on physical and mental health and social well-being. All households in Canada must have sufficient income for secure access to nutritious food after paying for other basic necessities. Given the alarming prevalence, severity and impact of household food insecurity in Canada, Dietitians of Canada calls for a pan-Canadian, government-led strategy to specifically reduce food insecurity at the household level, including policies that address the unique challenges of household food insecurity among Indigenous Peoples. Regular monitoring of the prevalence and severity of household food insecurity across all of Canada is required. Research must continue to address gaps in knowledge about household vulnerability to food insecurity and to evaluate the impact of policies developed to eliminate household food insecurity in Canada. Dietitians of Canada recommends: Development and implementation of a pan-Canadian government-led strategy that includes coordinated policies and programs, to ensure all households have consistent and sufficient income to be able to pay for basic needs, including food. Implementation of a federally-supported strategy to comprehensively address the additional and unique challenges related to household food insecurity among Indigenous Peoples, including assurance of food sovereignty, with access to lands and resources, for acquiring traditional/country foods, as well as improved access to more affordable and healthy store-bought/market foods in First Nation reserves and northern and remote communities. Commitment to mandatory, annual monitoring and reporting of the prevalence of marginal, moderate and severe household food insecurity in each province and territory across Canada, including among vulnerable populations, as well as regular evaluation of the impact of poverty reduction and protocols for

  8. Decoherence Effects on Multiplayer Cooperative Quantum Games

    International Nuclear Information System (INIS)

    Khan, Salman; Ramzan, M.; Khan, M. Khalid.

    2011-01-01

    We study the behavior of cooperative multiplayer quantum games [Q. Chen, Y. Wang, J.T. Liu, and K.L. Wang, Phys. Lett. A 327 (2004) 98; A.P. Flitney and L.C.L. Hollenberg, Quantum Inf. Comput. 7 (2007) 111] in the presence of decoherence using different quantum channels such as amplitude damping, depolarizing and phase damping. It is seen that the outcomes of the games for the two damping channels with maximum values of decoherence reduce to same value. However, in comparison to phase damping channel, the payoffs of cooperators are strongly damped under the influence amplitude damping channel for the lower values of decoherence parameter. In the case of depolarizing channel, the game is a no-payoff game irrespective of the degree of entanglement in the initial state for the larger values of decoherence parameter. The decoherence gets the cooperators worse off. (general)

  9. Global Warming and Food Insecurity in Rural Latin America

    Science.gov (United States)

    Byrne, T. R.; Byrne, J. M.; McDaniel, S.

    2012-12-01

    Food insecurity is one of the most important challenges facing humanity in the 21st century - a challenge that will be further exacerbated by the changing climate. The effects of human induced climate change will be most disproportionate and severe in the developing world, where a stable food supply, decreased purchasing power, and adequate nutrition are often already a daily struggle. This study will build on work done by the Food and Agriculture Organization (FAO) of the United Nations (UN), and will assess how vulnerability to household food insecurity will be affected by global warming in various rural parts of Latin America. Temperature data from downscaled Global Circulation Models (GCM) will be used in conjunction with the results of national household surveys to generate information on each rural farming household's probability of falling below a food poverty threshold in the near future. The results of the study will allow us to distinguish between households that are likely to experience chronic food insecurity and those that are likely to experience transitory food insecurity, permitting for improved targeting of policy responses.

  10. Quantum information theory with Gaussian systems

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, O.

    2006-04-06

    This thesis applies ideas and concepts from quantum information theory to systems of continuous-variables such as the quantum harmonic oscillator. The focus is on three topics: the cloning of coherent states, Gaussian quantum cellular automata and Gaussian private channels. Cloning was investigated both for finite-dimensional and for continuous-variable systems. We construct a private quantum channel for the sequential encryption of coherent states with a classical key, where the key elements have finite precision. For the case of independent one-mode input states, we explicitly estimate this precision, i.e. the number of key bits needed per input state, in terms of these parameters. (orig.)

  11. Quantum information theory with Gaussian systems

    International Nuclear Information System (INIS)

    Krueger, O.

    2006-01-01

    This thesis applies ideas and concepts from quantum information theory to systems of continuous-variables such as the quantum harmonic oscillator. The focus is on three topics: the cloning of coherent states, Gaussian quantum cellular automata and Gaussian private channels. Cloning was investigated both for finite-dimensional and for continuous-variable systems. We construct a private quantum channel for the sequential encryption of coherent states with a classical key, where the key elements have finite precision. For the case of independent one-mode input states, we explicitly estimate this precision, i.e. the number of key bits needed per input state, in terms of these parameters. (orig.)

  12. Mother and Adolescent Eating in the Context of Food Insecurity: Findings from Urban Public Housing.

    Science.gov (United States)

    Bruening, Meg; Lucio, Joanna; Brennhofer, Stephanie

    2017-10-01

    Introduction Anecdotal evidence suggests that parents protect their children from food insecurity and its effects, but few studies have concurrently assessed food insecurity among youth and parents. The purpose of this study was to examine food insecurity and eating behaviors among an urban sample of mother-adolescent dyads. Methods Mother-adolescent dyads (n = 55) were from six public housing sites in Phoenix, Arizona who completed surveys during 2014. Multivariate mixed linear and logistic regression models assessed the relationship between mother and adolescent eating behaviors in the context of food insecurity. Results Food insecurity was prevalent with 65.4% of parents and 43.6% of adolescents reporting food insecurity; 34.5% of parents and 14.5% of adolescents reported very low food security. After adjusting for food insecurity status, parents' and adolescents' fruit, vegetable, and sugar-sweetened beverage consumption was not associated. However, significant associations were observed between mothers' and adolescents' fast food intake (β = 0.52; p insecurity given the lower prevalence of food insecurity observed among adolescents. Interventions addressing food insecurity among mothers and adolescents may want to capitalize on shared eating patterns and address issues related to binge eating and leverage site-based strengths of public housing.

  13. Application of a Theoretical Model Toward Understanding Continued Food Insecurity Post Hurricane Katrina.

    Science.gov (United States)

    Clay, Lauren A; Papas, Mia A; Gill, Kimberly; Abramson, David M

    2018-02-01

    Disaster recovery efforts focus on restoring basic needs to survivors, such as food, water, and shelter. However, long after the immediate recovery phase is over, some individuals will continue to experience unmet needs. Ongoing food insecurity has been identified as a post-disaster problem. There is a paucity of information regarding the factors that might place an individual at risk for continued food insecurity post disaster. Using data from a sample (n=737) of households severely impacted by Hurricane Katrina, we estimated the associations between food insecurity and structural, physical and mental health, and psychosocial factors 5 years after Hurricane Katrina. Logistic regression models were fit and odds ratios (OR) and 95% CI estimated. Nearly one-quarter of respondents (23%) reported food insecurity 5 years post Katrina. Marital/partner status (OR: 0.7, CI: 0.42, 0.99), self-efficacy (OR: 0.56, CI: 0.37, 0.84), sense of community (OR: 0.7, CI: 0.44, 0.98), and social support (OR: 0.59, CI: 0.39, 0.89) lowered the odds of food insecurity and explained most of the effects of mental health distress on food insecurity. Social support, self-efficacy, and being partnered were protective against food insecurity. Recovery efforts should focus on fostering social-support networks and increased self-efficacy to improve food insecurity post disaster. (Disaster Med Public Health Preparedness. 2018;12:47-56).

  14. A qualitative pilot study of food insecurity among Maasai women in Tanzania.

    Science.gov (United States)

    Fenton, Carol; Hatfield, Jennifer; McIntyre, Lynn

    2012-01-01

    Food insecurity is an ongoing threat in rural sub-Saharan Africa and is complicated by cultural practices, the rise of chronic conditions such as HIV and land use availability. In order to develop a successful food security intervention program, it is important to be informed of the realities and needs of the target population. The purpose of this study was to pilot a qualitative method to understand food insecurity based on the lived experience of women of the Maasai population in the Ngorongoro Conservation Area of Tanzania. Short semi-structured qualitative interviews with 4 Maasai women. FOOD INSECURITY WAS PRESENT IN THE MAASAI COMMUNITY: the participants revealed that they did not always have access to safe and nutritious food that met the needs of themselves and their families. Themes that emerged from the data fell into three categories: Current practices (food sources, planning for enough, food preparation, and food preservation), food Insecurity (lack of food, emotions, coping strategies, and possible solutions), and division (co-wives, food distribution, and community relationships). This pilot study suggested the presence of food insecurity in the Maasai community. Larger sample studies are needed to clarify the extent and severity of food insecurity among this population. Having a detailed understanding of the various aspects of the food insecurity lived experience could inform a targeted intervention program.

  15. Job insecurity and organizational citizenship behavior: exploring curvilinear and moderated relationships.

    Science.gov (United States)

    Lam, Chak Fu; Liang, Jian; Ashford, Susan J; Lee, Cynthia

    2015-03-01

    This article examined a curvilinear relationship between job insecurity and organizational citizenship behavior (OCB). Drawing from social exchange theory and research on personal control, we developed and tested an explanation for employees' reactions to job insecurity based on their conceptualization of their social exchange relationship with the organization at different levels of job insecurity. Using data from 244 Chinese employees and 102 supervisory ratings of OCB, we found support for a U-shaped relationship between job insecurity and OCB. Moreover, 2 factors--psychological capital and subordinate-supervisor guanxi--moderated the curvilinear relationship, such that the curvilinear relationship is more pronounced among those with lower psychological capital or less positive subordinate-supervisor guanxi. PsycINFO Database Record (c) 2015 APA, all rights reserved.

  16. Diamond-based Fabry-Perot microcavities for quantum networks

    NARCIS (Netherlands)

    Bogdanovic, S.

    2017-01-01

    A quantumnetwork would allow the distribution of a quantum state over many spatially separated quantum nodes which individually possess the ability to generate, process and store quantum information. Connecting these nodes through quantum communication channels would enable sending quantum

  17. Quantum red-green-blue image steganography

    Science.gov (United States)

    Heidari, Shahrokh; Pourarian, Mohammad Rasoul; Gheibi, Reza; Naseri, Mosayeb; Houshmand, Monireh

    One of the most considering matters in the field of quantum information processing is quantum data hiding including quantum steganography and quantum watermarking. This field is an efficient tool for protecting any kind of digital data. In this paper, three quantum color images steganography algorithms are investigated based on Least Significant Bit (LSB). The first algorithm employs only one of the image’s channels to cover secret data. The second procedure is based on LSB XORing technique, and the last algorithm utilizes two channels to cover the color image for hiding secret quantum data. The performances of the proposed schemes are analyzed by using software simulations in MATLAB environment. The analysis of PSNR, BER and Histogram graphs indicate that the presented schemes exhibit acceptable performances and also theoretical analysis demonstrates that the networks complexity of the approaches scales squarely.

  18. Risk factors associated with the presence and severity of food insecurity in rural Honduras.

    Science.gov (United States)

    Ben-Davies, Maureen E; Kinlaw, Alan; Estrada Del Campo, Yaniré; Bentley, Margaret E; Siega-Riz, Anna Maria

    2014-01-01

    To identify factors associated with the presence and severity of food insecurity among a sample of Honduran caregivers of young children. Cross-sectional study in which the dependent variable, household food insecurity, was measured using a fourteen-item questionnaire developed and validated in a population of similar cultural context. A predictive modelling strategy used backwards elimination in logistic regression and multinomial logit regression models to compute odds ratios and 95% confidence intervals for food insecurity. Rural Honduras in the department of Intibucá, between March and April 2009. Two-hundred and ninety-eight Honduran caregivers of children aged 6-18 months. Ninety-three per cent of households were classified as having some degree of food insecurity (mild, moderate or severe). After controlling for caregiver age and marital status, compared with caregivers with more than primary-school education, those with less than primary-school education had 3·47 (95% CI 1·34, 8·99) times the odds of severe food insecurity and 2·29 (95% CI 1·00, 5·25) times the odds of moderate food insecurity. Our results also found that child anthropometric status was not associated with the presence or severity of food insecurity. These results show that among the sociodemographic factors assessed, food insecurity in rural Honduras is associated with maternal education. Understanding key factors associated with food insecurity that are unique to Honduras can inform the design of interventions to effectively mitigate the negative impact of food insecurity on children.

  19. Occupations at Risk and Organizational Well-Being: An Empirical Test of a Job Insecurity Integrated Model.

    Science.gov (United States)

    Chirumbolo, Antonio; Urbini, Flavio; Callea, Antonino; Lo Presti, Alessandro; Talamo, Alessandra

    2017-01-01

    One of the more visible effects of the societal changes is the increased feelings of uncertainty in the workforce. In fact, job insecurity represents a crucial occupational risk factor and a major job stressor that has negative consequences on both organizational well-being and individual health. Many studies have focused on the consequences about the fear and the perception of losing the job as a whole (called quantitative job insecurity), while more recently research has begun to examine more extensively the worries and the perceptions of losing valued job features (called qualitative job insecurity). The vast majority of the studies, however, have investigated the effects of quantitative and qualitative job insecurity separately. In this paper, we proposed the Job Insecurity Integrated Model aimed to examine the effects of quantitative job insecurity and qualitative job insecurity on their short-term and long-term outcomes. This model was empirically tested in two independent studies, hypothesizing that qualitative job insecurity mediated the effects of quantitative job insecurity on different outcomes, such as work engagement and organizational identification (Study 1), and job satisfaction, commitment, psychological stress and turnover intention (Study 2). Study 1 was conducted on 329 employees in private firms, while Study 2 on 278 employees in both public sector and private firms. Results robustly showed that qualitative job insecurity totally mediated the effects of quantitative on all the considered outcomes. By showing that the effects of quantitative job insecurity on its outcomes passed through qualitative job insecurity, the Job Insecurity Integrated Model contributes to clarifying previous findings in job insecurity research and puts forward a framework that could profitably produce new investigations with important theoretical and practical implications.

  20. Occupations at Risk and Organizational Well-Being: An Empirical Test of a Job Insecurity Integrated Model

    Science.gov (United States)

    Chirumbolo, Antonio; Urbini, Flavio; Callea, Antonino; Lo Presti, Alessandro; Talamo, Alessandra

    2017-01-01

    One of the more visible effects of the societal changes is the increased feelings of uncertainty in the workforce. In fact, job insecurity represents a crucial occupational risk factor and a major job stressor that has negative consequences on both organizational well-being and individual health. Many studies have focused on the consequences about the fear and the perception of losing the job as a whole (called quantitative job insecurity), while more recently research has begun to examine more extensively the worries and the perceptions of losing valued job features (called qualitative job insecurity). The vast majority of the studies, however, have investigated the effects of quantitative and qualitative job insecurity separately. In this paper, we proposed the Job Insecurity Integrated Model aimed to examine the effects of quantitative job insecurity and qualitative job insecurity on their short-term and long-term outcomes. This model was empirically tested in two independent studies, hypothesizing that qualitative job insecurity mediated the effects of quantitative job insecurity on different outcomes, such as work engagement and organizational identification (Study 1), and job satisfaction, commitment, psychological stress and turnover intention (Study 2). Study 1 was conducted on 329 employees in private firms, while Study 2 on 278 employees in both public sector and private firms. Results robustly showed that qualitative job insecurity totally mediated the effects of quantitative on all the considered outcomes. By showing that the effects of quantitative job insecurity on its outcomes passed through qualitative job insecurity, the Job Insecurity Integrated Model contributes to clarifying previous findings in job insecurity research and puts forward a framework that could profitably produce new investigations with important theoretical and practical implications. PMID:29250013

  1. Occupations at Risk and Organizational Well-Being: An Empirical Test of a Job Insecurity Integrated Model

    Directory of Open Access Journals (Sweden)

    Antonio Chirumbolo

    2017-11-01

    Full Text Available One of the more visible effects of the societal changes is the increased feelings of uncertainty in the workforce. In fact, job insecurity represents a crucial occupational risk factor and a major job stressor that has negative consequences on both organizational well-being and individual health. Many studies have focused on the consequences about the fear and the perception of losing the job as a whole (called quantitative job insecurity, while more recently research has begun to examine more extensively the worries and the perceptions of losing valued job features (called qualitative job insecurity. The vast majority of the studies, however, have investigated the effects of quantitative and qualitative job insecurity separately. In this paper, we proposed the Job Insecurity Integrated Model aimed to examine the effects of quantitative job insecurity and qualitative job insecurity on their short-term and long-term outcomes. This model was empirically tested in two independent studies, hypothesizing that qualitative job insecurity mediated the effects of quantitative job insecurity on different outcomes, such as work engagement and organizational identification (Study 1, and job satisfaction, commitment, psychological stress and turnover intention (Study 2. Study 1 was conducted on 329 employees in private firms, while Study 2 on 278 employees in both public sector and private firms. Results robustly showed that qualitative job insecurity totally mediated the effects of quantitative on all the considered outcomes. By showing that the effects of quantitative job insecurity on its outcomes passed through qualitative job insecurity, the Job Insecurity Integrated Model contributes to clarifying previous findings in job insecurity research and puts forward a framework that could profitably produce new investigations with important theoretical and practical implications.

  2. Ontological insecurity and subjective feelings of unsafety: Analysing socially constructed fears in Italy.

    Science.gov (United States)

    Valente, Riccardo; Valera Pertegas, Sergi

    2018-03-01

    Perception of insecurity arises as a complex social phenomenon affected by factors that go beyond actual crime rates. Previous contributions to the field of fear of crime studies have shown, for instance, that the perception of social and physical disorder may generate insecurity among residents even in contexts where crime is comparatively low. Meanwhile, sociological approaches have led to a conceptualization of insecurity as an umbrella sentiment grounded in a wider feeling of unease. Building further on this assumption, data gathered in a large-scale survey in Italy (n = 15,428) were analysed by implementing exploratory and confirmatory factor analysis with the objective of assessing the validity of a model of "ontological insecurity". The results of our analysis support a conceptualization of insecurity where socially constructed anxieties (due to health and financial precariousness), as well as ethnic, sexual and religious-based stigmatization, play a prominent role in determining an individual's feeling of insecurity. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Food Insecurity Increases HIV Risk Among Young Sex Workers in Metro Vancouver, Canada.

    Science.gov (United States)

    Barreto, Daniella; Shannon, Kate; Taylor, Chrissy; Dobrer, Sabina; Jean, Jessica St; Goldenberg, Shira M; Duff, Putu; Deering, Kathleen N

    2017-03-01

    This research aimed to determine the effect of food insecurity on sexual HIV risk with clients among youth sex workers (YSWs) sex workers (2010-2013). We examined the independent relationship between YSWs' food insecurity and being pressured into sex without a condom by clients ("client condom refusal"). Of 220 YSWs, 34.5 % (n = 76) reported client condom refusal over the 3.5-year study period and 76.4 % (n = 168) reported any food insecurity. Adjusting for other HIV risk pathways, food insecurity retained an independent effect on client condom refusal (AOR 2.08, 95 % CI 1.23-3.51), suggesting that food insecurity is significantly associated with HIV risk among YSWs. This study indicates a critical relationship between food insecurity and HIV risk, and demonstrates YSWs' particular vulnerability. Public policies for food assistance as a harm reduction measure may be key to addressing this disparity.

  4. Healing and coping with life within challenges of spiritual insecurity ...

    African Journals Online (AJOL)

    Spiritual insecurity among African Christians is a huge challenge. The insecurity among other things arises from African people's former traditional African ancestral world view of ancestral veneration. The ancestors promote or hinder African Christians' reliance on Christ because they have presupposedly acquired the ...

  5. Food insecurity and dietary intake of immigrant food bank users.

    Science.gov (United States)

    Rush, Timothy J; Ng, Victor; Irwin, Jennifer D; Stitt, Larry W; He, Meizi

    2007-01-01

    The degree of food insecurity and dietary intake was examined in adult Colombians who are new immigrants to Canada and use a food bank. In-person surveys were conducted on a convenience sample of 77 adult Colombian immigrant food bank users in London, Ontario. Degree of food insecurity was measured by the Radimer/Cornell questionnaire, food intakes by 24-hour recall, sociodemographics, and questionnaires about changes in dietary patterns before and after immigration. Thirty-six men and 41 women participated in the study. Despite being highly educated, all respondents had experienced some form of food insecurity within the previous 30 days. The degree of food insecurity seems to be inversely associated with income and length of residency in Canada. Total daily energy intake was low, with a mean value of 1,568.3 +/- 606.0 kcal (6,217.5 +/- 2,336.4 kJ). In particular, a large proportion of participants consumed a diet low in fruits and vegetables (73%) and milk and dairy products (58%). Colombian immigrant food bank users new to Canada experience various degrees of food insecurity, which is associated with inadequate food intake. Interventions are needed to assist this population with adapting to society while concurrently sustaining healthy eating patterns.

  6. Multiparty Quantum Secret Sharing of Secure Direct Communication Using Teleportation

    International Nuclear Information System (INIS)

    Wang Jian; Zhang Quan; Tang Chaojing

    2007-01-01

    We present an (n,n) threshold quantum secret sharing scheme of secure direct communication using Greenberger-Horne-Zeilinger state and teleportation. After ensuring the security of the quantum channel, the sender encodes the secret message directly on a sequence of particle states and transmits it to the receivers by teleportation. The receivers can recover the secret message by combining their measurement results with the sender's result. If a perfect quantum channel is used, our scheme is completely secure because the transmitting particle sequence does not carry the secret message. We also show our scheme is secure for noise quantum channel.

  7. Food Insecurity and Health Care Expenditures in the United States, 2011-2013.

    Science.gov (United States)

    Berkowitz, Seth A; Basu, Sanjay; Meigs, James B; Seligman, Hilary K

    2018-06-01

    To determine whether food insecurity, limited or uncertain food access owing to cost, is associated with greater health care expenditures. Nationally representative sample of the civilian noninstitutionalized population of the United States (2011 National Health Interview Survey [NHIS] linked to 2012-2013 Medication Expenditure Panel Survey [MEPS]). Longitudinal retrospective cohort. A total of 16,663 individuals underwent assessment of food insecurity, using the 10-item adult 30-day food security module, in the 2011 NHIS. Their total health care expenditures in 2012 and 2013 were recorded in MEPS. Expenditure data were analyzed using zero-inflated negative binomial regression and adjusted for age, gender, race/ethnicity, education, income, insurance, and residence area. Fourteen percent of individuals reported food insecurity, representing 41,616,255 Americans. Mean annualized total expenditures were $4,113 (standard error $115); 9.2 percent of all individuals had no health care expenditures. In multivariable analyses, those with food insecurity had significantly greater estimated mean annualized health care expenditures ($6,072 vs. $4,208, p insecurity was associated with greater subsequent health care expenditures. Future studies should determine whether food insecurity interventions can improve health and reduce health care costs. © Health Research and Educational Trust.

  8. Food Insecurity and Pre-diabetes in Adults: Race/Ethnic and Sex Differences.

    Science.gov (United States)

    Murillo, Rosenda; Reesor, Layton M; Scott, Claudia W; Hernandez, Daphne C

    2017-07-01

    We examined sex and race/ethnicity differences in the association between food insecurity status and prediabetes among adults. We used cross-sectional 2011 and 2012 National Health Interview Survey data on non-Hispanic white, non-Hispanic black, and Hispanic adults aged 18-59 years whose household income was ≤ 299% Federal Poverty Line (N = 19,048). Food insecurity status was determined by 3 or more affirmative responses on the 10-item USDA Food Security Scale. Pre-diabetes was self-reported. Logistic regression analyses were used to estimate associations of food insecurity with pre-diabetes and adjusted for several demographic characteristics. All models were stratified by sex and race/ethnicity. In adjusted models, food insecure non-Hispanic white women and non-Hispanic black women had 53% and over 200% higher odds of being pre-diabetic, respectively. Food insecurity was not related to pre-diabetes for Hispanic women or men. Limited food resources appear to place non-Hispanic white and non-Hispanic black women at risk for pre-diabetes. Linking food assistance programs with community-based health education programs may be a comprehensive approach to support those who are food insecure with diabetes prevention.

  9. Job Insecurity Research is Still Alive and Kicking Twenty Years Later : A Commentary

    NARCIS (Netherlands)

    Schaufeli, Wilmar B.

    2016-01-01

    This paper comments on the review of longitudinal job insecurity studies in this special issue. The main conclusion of that review, namely that job insecurity leads to poor health and well-being, remains undisputed. It is argued, however, that future job insecurity research should focus more on: (a)

  10. The Relation between Food Insecurity and Mental Health Care Service Utilization in Ontario.

    Science.gov (United States)

    Tarasuk, Valerie; Cheng, Joyce; Gundersen, Craig; de Oliveira, Claire; Kurdyak, Paul

    2018-01-01

    To determine the relationship between household food insecurity status over a 12-month period and adults' use of publicly funded health care services in Ontario for mental health reasons during this period. Data for 80,942 Ontario residents, 18 to 64 years old, who participated in the Canadian Community Health Survey in 2005, 2007-2008, 2009-2010, or 2011-2012 were linked to administrative health care data to determine individuals' hospitalizations, emergency department visits, and visits to psychiatrists and primary care physicians for mental health reasons. Household food insecurity over the past 12 months was assessed using the Household Food Security Survey Module. Logistic regression models were used to estimate the odds of mental health service utilization in the past 12 months by household food insecurity status, adjusting for sociodemographic factors and prior use of mental health services. In our fully adjusted models, in comparison to food-secure individuals, the odds of any mental health care service utilization over the past 12 months were 1.15 (95% confidence interval [CI], 1.04 to 1.29) for marginally food-insecure individuals, 1.39 (95% CI, 1.19 to 1.42) for moderately food-insecure individuals, and 1.50 (95% CI, 1.35 to 1.68) for severely food-insecure individuals. A similar pattern persisted across individual types of services, with odds of utilization highest with severe food insecurity. Household food insecurity status is a robust predictor of mental health service utilization among working-age adults in Ontario. Policy interventions are required to address the underlying causes of food insecurity and the particular vulnerability of individuals with mental illness.

  11. Quantum secure direct communication by EPR pairs and entanglement swapping

    CERN Document Server

    Gao, T; Yan, F L; 10.1393/ncb/i2004-10090-1

    2004-01-01

    We present, a quantum secure direct communication scheme achieved by swapping quantum entanglement. In this scheme a set of ordered Einstein-Podolsky-Rosen (HPIl) pairs is used as a quantum information channel for sending secret messages directly. After insuring the safety of the quantum channel, the sender Alice encodes the secret messages directly by applying a series local operations on her particle sequences according to their stipulation. Using three EPR pairs, three bits of secret classical information can be faithfully transmitted from Alice to remote Bob without revealing any information to a potential eavesdropper. By both Alice and Bob's GHZ state measurement results, Bob is able to read out the encoded secret messages directly. The protocol is completely secure if perfect quantum channel is used, because there is not a transmission of the qubits carrying the secret message between Alice and Bob in the public channel.

  12. Quantum speed limits for Bell-diagonal states

    International Nuclear Information System (INIS)

    Han Wei; Jiang Ke-Xia; Zhang Ying-Jie; Xia Yun-Jie

    2015-01-01

    The lower bounds of the evolution time between two distinguishable states of a system, defined as quantum speed limit time, can characterize the maximal speed of quantum computers and communication channels. We study the quantum speed limit time between the composite quantum states and their target states in the presence of nondissipative decoherence. For the initial states with maximally mixed marginals, we obtain the exact expressions of the quantum speed limit time which mainly depend on the parameters of the initial states and the decoherence channels. Furthermore, by calculating the quantum speed limit time for the time-dependent states started from a class of initial states, we discover that the quantum speed limit time gradually decreases in time, and the decay rate of the quantum speed limit time would show a sudden change at a certain critical time. Interestingly, at the same critical time, the composite system dynamics would exhibit a sudden transition from classical decoherence to quantum decoherence. (paper)

  13. Food insecurity among the elderly: cross-sectional study with soup kitchen users

    Directory of Open Access Journals (Sweden)

    Bruna Fernanda do Nascimento Jacinto de Souza

    2013-12-01

    Full Text Available OBJECTIVE: To investigate whether food insecurity is associated with the demographic, socioeconomic, lifestyle, and health conditions of the elderly. METHODS: This cross-sectional study included 427 elderly (³60 years from Campinas, São Paulo; half were users of a government-run soup kitchen and the others, their neighbors of the same sex. Food insecurity was measured by the Brazilian Food Insecurity Scale. Univariate multinomial logistic regression was used for calculating the odds ratio and 95% confidence interval to measure the association between the independent variables and food insecurity. Variables with p<0.20 were included in a multinomial model, and only those with p<0.05 remained. RESULTS: Most respondents (63.2% were males; 15.2% and 6.6% were experiencing mild and moderate/severe food insecurity, respectively. The final model, adjusted for sex and age, showed that elderly with a total family income ≤2 minimum salaries (OR=3.41, 95%CI=1.27-9.14, who did not have a job (OR=2.95, 95%CI=1.23-7.06, and who were obese (OR=2.01, 95%CI=1.04-3.87 were more likely to be mildly food insecure. Elderly with cancer (OR=4.13, 95%CI=1.21-14.0 and those hospitalized in the past year (OR=3.16, 95%CI=1.23-8.11 were more likely to be moderately/severely food insecure. Finally, elderly living in unfinished houses (OR=2.71; and OR=2.92 and who did not consume fruits (OR=2.95 and OR=4.11 or meats daily (OR=2.04 and OR=3.83 were more likely to be mildly and moderately/severely food insecure. CONCLUSION: Food insecure elderly are more likely to have chronic diseases, poor nutritional status, and poor socioeconomic condition. Therefore, the welfare programs should expand the number of soup kitchens and develop other strategies to assure adequate nutrition to these elderly.

  14. Comment on 'Quantum secret sharing based on reusable Greenberger-Horne-Zeilinger states as secure carriers'

    International Nuclear Information System (INIS)

    Gao Fei; Guo Fenzhuo; Wen Qiaoyan; Zhu Fuchen

    2005-01-01

    In a recent paper [S. Bagherinezhad and V. Karimipour, Phys. Rev. A 67, 044302 (2003)], a quantum secret sharing protocol based on reusable Greenberger-Horne-Zeilinger states was proposed. However, in this Comment, it is shown that this protocol is insecure if Eve employs a special strategy to attack

  15. Effects of Maternal Depression on Family Food Insecurity

    OpenAIRE

    Kelly Noonan; Hope Corman; Nancy E. Reichman

    2014-01-01

    Theory suggests that adverse life events--such as unemployment or health shocks--can result in food insecurity, which has increased substantially in the U.S. over the past decade alongside the obesity epidemic. We test this proposition by estimating the effects of a specific and salient mental health event--maternal depression during the postpartum year--on child and family food insecurity. Using data from the Early Childhood Longitudinal Study--Birth Cohort, we estimate the effects of matern...

  16. Household food insecurity and dietary patterns in rural and urban American Indian families with young children.

    Science.gov (United States)

    Tomayko, Emily J; Mosso, Kathryn L; Cronin, Kate A; Carmichael, Lakeesha; Kim, KyungMann; Parker, Tassy; Yaroch, Amy L; Adams, Alexandra K

    2017-06-30

    High food insecurity has been demonstrated in rural American Indian households, but little is known about American Indian families in urban settings or the association of food insecurity with diet for these families. The purpose of this study was to examine the prevalence of food insecurity in American Indian households by urban-rural status, correlates of food insecurity in these households, and the relationship between food insecurity and diet in these households. Dyads consisting of an adult caregiver and a child (2-5 years old) from the same household in five urban and rural American Indian communities were included. Demographic information was collected, and food insecurity was assessed using two validated items from the USDA Household Food Security Survey. Factors associated with food insecurity were examined using logistic regression. Child and adult diets were assessed using food screeners. Coping strategies were assessed through focus group discussions. These cross-sectional baseline data were collected from 2/2013 through 4/2015 for the Healthy Children, Strong Families 2 randomized controlled trial of a healthy lifestyles intervention for American Indian families. A high prevalence of food insecurity was determined (61%) and was associated with American Indian ethnicity, lower educational level, single adult households, WIC participation, and urban settings (p = 0.05). Food insecure adults had significantly lower intake of vegetables (p insecure children had significantly higher intakes of fried potatoes (p insecurity. The prevalence of food insecurity in American Indian households in our sample is extremely high, and geographic designation may be an important contributing factor. Moreover, food insecurity had a significant negative influence on dietary intake for families. Understanding strategies employed by households may help inform future interventions to address food insecurity. ( NCT01776255 ). Registered: January 16, 2013. Date of enrollment

  17. Markov Chain-Like Quantum Biological Modeling of Mutations, Aging, and Evolution

    Directory of Open Access Journals (Sweden)

    Ivan B. Djordjevic

    2015-08-01

    Full Text Available Recent evidence suggests that quantum mechanics is relevant in photosynthesis, magnetoreception, enzymatic catalytic reactions, olfactory reception, photoreception, genetics, electron-transfer in proteins, and evolution; to mention few. In our recent paper published in Life, we have derived the operator-sum representation of a biological channel based on codon basekets, and determined the quantum channel model suitable for study of the quantum biological channel capacity. However, this model is essentially memoryless and it is not able to properly model the propagation of mutation errors in time, the process of aging, and evolution of genetic information through generations. To solve for these problems, we propose novel quantum mechanical models to accurately describe the process of creation spontaneous, induced, and adaptive mutations and their propagation in time. Different biological channel models with memory, proposed in this paper, include: (i Markovian classical model, (ii Markovian-like quantum model, and (iii hybrid quantum-classical model. We then apply these models in a study of aging and evolution of quantum biological channel capacity through generations. We also discuss key differences of these models with respect to a multilevel symmetric channel-based Markovian model and a Kimura model-based Markovian process. These models are quite general and applicable to many open problems in biology, not only biological channel capacity, which is the main focus of the paper. We will show that the famous quantum Master equation approach, commonly used to describe different biological processes, is just the first-order approximation of the proposed quantum Markov chain-like model, when the observation interval tends to zero. One of the important implications of this model is that the aging phenotype becomes determined by different underlying transition probabilities in both programmed and random (damage Markov chain-like models of aging, which

  18. Optimization of Communication in Noisy Quantum Channels

    National Research Council Canada - National Science Library

    Ruskai, Mary

    2002-01-01

    .... This project has been concerned with the analysis of mathematical models of noise for qubit channels, with the capacity of qubit channels used to transmit classical information, and with exchange...

  19. Children with Special Health Care Needs, Supplemental Security Income, and Food Insecurity.

    Science.gov (United States)

    Rose-Jacobs, Ruth; Fiore, Jennifer Goodhart; de Cuba, Stephanie Ettinger; Black, Maureen; Cutts, Diana B; Coleman, Sharon M; Heeren, Timothy; Chilton, Mariana; Casey, Patrick; Cook, John; Frank, Deborah A

    2016-01-01

    To assess food insecurity in low-income households with young children with/without special health care needs (SHCN) and evaluate relationships between child Supplemental Security Income (SSI) receipt and food insecurity. A cross-sectional survey (2013-2015) of caregivers was conducted at 5 medical centers. Eligibility included index child age Children with Special Health Care Needs Screener, 18-item US Food Security Survey Module, household public assistance program participation, and child SSI receipt. Household and child food insecurity, each, were evaluated using multivariable logistic regression models. Of 6724 index children, 81.5% screened negative for SHCN, 14.8% positive for SHCN (no SSI), and 3.7% had SHCN and received SSI. After covariate control, households, with versus without a child with SHCN, were more likely to experience household (Adjusted odds ratios [AOR] 1.24, 95% confidence intervals [CI], 1.03-1.48) and child (AOR 1.35, 95% CI, 1.11-1.63) food insecurity. Among households with children with SHCN, those with children receiving, versus not receiving SSI, were more likely to report household (AOR 1.42, 95% CI, 0.97-2.09) but not child food insecurity. Low-income households with young children having SHCN are at risk for food insecurity, regardless of child SSI receipt and household participation in other public assistance programs. Policy recommendations include reevaluation of assistance programs' income and medical deduction criteria for households with children with SHCN to decrease the food insecurity risk faced by these children and their families.

  20. Student Hunger on Campus: Food Insecurity Among College Students and Implications for Academic Institutions.

    Science.gov (United States)

    Payne-Sturges, Devon C; Tjaden, Allison; Caldeira, Kimberly M; Vincent, Kathryn B; Arria, Amelia M

    2018-02-01

    To estimate the prevalence of food insecurity among students at a large mid-Atlantic publicly funded university; examine the association between food insecurity, demographic characteristics, potential financial risk factors, and self-reported physical and mental health and academic performance; and identify possible risk factors for food insecurity. Cross-sectional survey. Large, public mid-Atlantic university. Two hundred thirty-seven undergraduate students. US Department of Agriculture (USDA) 18-item Household Food Security Survey Module (HFSSM) and questions on demographics, student status, economic factors, housing stability, living arrangements, academic performance, and self-rated physical health and depression symptoms. Multivariate logistic regression analysis. Among students surveyed, 15% were food insecure; an additional 16% were at risk of food insecurity. Students who were African American, other race/ethnicity, receiving multiple forms of financial aid, or experiencing housing problems were more likely to be food insecure or at the risk of food insecurity (Adjusted Odds Ratio [AOR] = 4.00, 95% confidence interval [CI] = 1.83-8.71, P value health concern that might have implications for academic performance, retention, and graduation rates. Universities that measure food insecurity among their students will be better positioned to advocate for policy changes at state and federal levels regarding college affordability and student financial assistance.

  1. Household food insecurity and food expenditure in Bolivia, Burkina Faso, And the Philippines.

    Science.gov (United States)

    Melgar-Quinonez, Hugo R; Zubieta, Ana C; MkNelly, Barbara; Nteziyaremye, Anastase; Gerardo, Maria Filipinas D; Dunford, Christopher

    2006-05-01

    This study examined the association between food insecurity, determined by a modified version of the U.S. Household Food Security Survey Module (US HFSSM), and total daily per capita (DPC) consumption (measured as household expenditures) in Bolivia, Burkina Faso, and the Philippines. Household food insecurity was determined by an adapted 9-item US HFSSM version. A short version of the World Bank's Living Standards Measurement Study (LSMS) consumption module measured household expenditures. Focus groups were used to adapt the survey instrument to each local context. The sample (n approximately 330 per country) includes residents of urban and rural areas. A 12-month food expenditure aggregate was generated as part of the total household expenditures calculation. DPC food expenditure, which represented over 60% of the total household consumption, as well as expenditures on specific food groups correlated with food insecurity both as a continuous Food Insecurity Score (FinSS) and a tricategorical food insecurity status variable. ANOVA and regression analysis were executed adjusting for social and demographic covariates. Food-secure households have significantly higher (P insecure households. The results offer evidence that the US HFSSM is able to discriminate between households at different levels of food insecurity status in diverse developing world settings.

  2. Transfer of an unknown quantum state, quantum networks, and memory

    International Nuclear Information System (INIS)

    Biswas, Asoka; Agarwal, G.S.

    2004-01-01

    We present a protocol for transfer of an unknown quantum state. The protocol is based on a two-mode cavity interacting dispersively in a sequential manner with three-level atoms in the Λ configuration. We propose a scheme for quantum networking using an atomic channel. We investigate the effect of cavity decoherence in the entire process. Further, we demonstrate the possibility of an efficient quantum memory for arbitrary superposition of two modes of a cavity containing one photon

  3. Dietary patterns and household food insecurity in rural populations of Kilosa district, Tanzania.

    Directory of Open Access Journals (Sweden)

    Julius Edward Ntwenya

    Full Text Available Few studies have investigated the relationship between dietary pattern and household food insecurity. The objective of the present analysis was to describe the food consumption patterns and to relate these with the prevalence of food insecurity in the context of a rural community.Three hundred and seven (307 randomly selected households in Kilosa district participated in the study. Data were collected during the rainy season (February-May and post harvest season (September-October in the year 2011. Food consumption pattern was determined using a 24-h dietary recall method. Food insecurity data were based on the 30 day recall experience to food insecurity in the household. Factor analysis method using Principal Components extraction function was used to derive the dietary patterns and correlation analysis was used to establish the existing relationship between household food insecurity and dietary patterns factor score.Four food consumption patterns namely (I Meat and milk; (II Pulses, legumes, nuts and cooking oils; (III fish (and other sea foods, roots and tubers; (IV Cereals, vegetables and fruits consumption patterns were identified during harvest season. Dietary patterns identified during the rainy season were as follows: (I Fruits, cooking oils, fats, roots and tubers (II Eggs, meat, milk and milk products (III Fish, other sea foods, vegetables, roots and tubers and (IV Pulses, legumes, nuts, cereals and vegetables. Household food insecurity was 80% and 69% during rainy and harvest-seasons, respectively (P = 0.01. Household food insecurity access scale score was negatively correlated with the factor scores on household dietary diversity.Food consumption patterns and food insecurity varied by seasons with worst scenarios most prevalent during the rainy season. The risk for inadequate dietary diversity was higher among food insecure households compared to food secure households. Effort geared at alleviating household food insecurity could

  4. [Socio-demographic and food insecurity characteristics of soup-kitchen users in Brazil].

    Science.gov (United States)

    Godoy, Kátia Cruz; Sávio, Karin Eleonora Oliveira; Akutsu, Rita de Cássia; Gubert, Muriel Bauermann; Botelho, Raquel Braz Assunção

    2014-06-01

    This study aimed to characterize users of a government soup-kitchen program and the association with family food insecurity, using a cross-sectional design and random sample of 1,637 soup-kitchen users. The study used a questionnaire with socioeconomic variables and the Brazilian Food Insecurity Scale, and measured weight and height. The chi-square test was applied, and the crude and adjusted prevalence ratios (PR) were calculated using Poisson regression. Prevalent characteristics included per capita income ranging from one-half to one minimum wage (35.1%), complete middle school (39.8%), and food security (59.4%). Users in the North of Brazil showed the worst data: incomplete primary school (39.8%), per capita income up to one-half the minimum wage (50.8%), and food insecurity (55.5%). Prevalence ratios for food insecurity were higher among users with per capita income up to one-fourth the minimum wage (p soup-kitchen users with food insecurity can help orient the program's work, location, and operations.

  5. Self-Perceived Job Insecurity and Social Context: Are There Different European Cultures of Anxiety?

    OpenAIRE

    Marcel Erlinghagen

    2007-01-01

    Job insecurity causes far reaching negative outcomes. The fear of job loss damages the health of employees and reduces the productivity of firms. Thus, job insecurity should result in increasing social costs. Analyzing representative data from 17 European countries, this paper investigates self perceived job insecurity. Our multi level analysis reveals significant cross-country differences in individuals' perception of job insecurity. This finding is not only driven by social-structural or in...

  6. Relationship between food insecurity and nutritional status of Brazilian children under the age of five.

    Science.gov (United States)

    Santos, Leonardo Pozza dos; Gigante, Denise Petrucci

    2013-12-01

    The aim of this study was to investigate the relationship between food insecurity and nutritional status of Brazilian children. The National Demographic and Health Survey 2006 database is available on the worldwide web. Thus, the analyzed variables were obtained in this study, including nutritional indices, food insecurity and other socioeconomic and demographic variables. The height-for-age, weight-for-age and weight-for-height indices were evaluated as the Z-score of the World Health Organization reference curves. Food insecurity was defined by using the Brazilian Food Insecurity Scale. Averages of three indices according to the presence of food insecurity were analyzed, including other variables. Linear regression evaluated the effect of food insecurity on the Z-score of the three nutritional indices. The sample included 4,817 children, out of whom 7% had deficit in height, 7% were overweight and 47% had food insecurity. It was found that the average of height-for-age, weight-for-age and weight-for-height were -0.31, 0.12 and 0.40, respectively, being lower among children with food insecurity. The regression analysis showed that children living with some level of food insecurity have worse rates of height-for-age, even controlling for demographic and socioeconomic factors.

  7. A tunable colloidal quantum dot photo field-effect transistor

    KAUST Repository

    Ghosh, Subir; Hoogland, Sjoerd; Sukhovatkin, Vlad; Levina, Larissa; Sargent, Edward H.

    2011-01-01

    We fabricate and investigate field-effect transistors in which a light-absorbing photogate modulates the flow of current along the channel. The photogate consists of colloidal quantum dots that efficiently transfer photoelectrons to the channel across a charge-separating (type-II) heterointerface, producing a primary and sustained secondary flow that is terminated via electron back-recombination across the interface. We explore colloidal quantum dot sizes corresponding to bandgaps ranging from 730 to 1475 nm and also investigate various stoichiometries of aluminum-doped ZnO (AZO) channel materials. We investigate the role of trap state energies in both the colloidal quantum dot energy film and the AZO channel. © 2011 American Institute of Physics.

  8. Short-Term Effects of Traditional and Alternative Community Interventions to Address Food Insecurity.

    Directory of Open Access Journals (Sweden)

    Federico Roncarolo

    Full Text Available Despite the effects of food insecurity on health are well documented, clear governmental policies to face food insecurity do not exist in western countries. In Canada, interventions to face food insecurity are developed at the community level and can be categorized into two basic strategies: those providing an immediate response to the need for food, defined "traditional" and those targeting the improvement of participants' social cohesion, capabilities and management of their own nutrition, defined "alternative".The objective of this study was to evaluate the effects of food insecurity interventions on food security status and perceived health of participants.This was a longitudinal multilevel study implemented in Montreal, Quebec, Canada. Participants were recruited in a two-stage cluster sampling frame. Clustering units were community organizations working on food insecurity; units of analysis were participants in community food security interventions. A total of 450 participants were interviewed at the beginning and after 9 months of participation in traditional or alternative food security interventions. Food security and perceived health were investigated as dependent variables. Differences overtime were assessed through multilevel regression models.Participants in traditional interventions lowered their food insecurity at follow-up. Decreases among participants in alternative interventions were not statistically significant. Participants in traditional interventions also improved physical (B coefficient 3.00, CI 95% 0.42-5.59 and mental health (B coefficient 6.25, CI 95% 4.15-8.35.Our results challenge the widely held view suggesting the ineffectiveness of traditional interventions in the short term. Although effects may be intervention-dependent, food banks decreased food insecurity and, in so doing, positively affected perceived health. Although study findings demonstrate that food banks offer short term reprise from the effects of food

  9. Quantum election scheme based on anonymous quantum key distribution

    International Nuclear Information System (INIS)

    Zhou Rui-Rui; Yang Li

    2012-01-01

    An unconditionally secure authority-certified anonymous quantum key distribution scheme using conjugate coding is presented, based on which we construct a quantum election scheme without the help of an entanglement state. We show that this election scheme ensures the completeness, soundness, privacy, eligibility, unreusability, fairness, and verifiability of a large-scale election in which the administrator and counter are semi-honest. This election scheme can work even if there exist loss and errors in quantum channels. In addition, any irregularity in this scheme is sensible. (general)

  10. A Quantum Proxy Weak Blind Signature Scheme Based on Controlled Quantum Teleportation

    Science.gov (United States)

    Cao, Hai-Jing; Yu, Yao-Feng; Song, Qin; Gao, Lan-Xiang

    2015-04-01

    Proxy blind signature is applied to the electronic paying system, electronic voting system, mobile agent system, security of internet, etc. A quantum proxy weak blind signature scheme is proposed in this paper. It is based on controlled quantum teleportation. Five-qubit entangled state functions as quantum channel. The scheme uses the physical characteristics of quantum mechanics to implement message blinding, so it could guarantee not only the unconditional security of the scheme but also the anonymity of the messages owner.

  11. Food Insecurity and Food Access in U.S. Metro Areas

    NARCIS (Netherlands)

    Bonanno, A.; Li, J.

    2015-01-01

    Household food insecurity in the United States has reached its highest levels to date. As public and private initiatives have emerged to help improve diets by fostering access to food, the availability of more food stores may result in lower levels of food insecurity. In this article, we assess the

  12. Factors associated with child hunger among food insecure households in Bangladesh

    Directory of Open Access Journals (Sweden)

    Md Ahshanul Haque

    2017-02-01

    Full Text Available Abstract Background Hunger is associated with food insecurity at the household level and is considered as a global public health problem with long term adverse consequences on children’s health. This study aims to determine the factors associated with child hunger from a nationally representative sample in Bangladesh among food insecure households. Methods Data was derived from the Food Security and Nutritional Surveillance Project; 14,712 children aged 6–59 months belonging to food insecure households contributed to the analysis. Information on food security at the household level was collected for 30 days preceding the survey. Descriptive statistics served to illustrate the variables studied and multiple logistic regression analysis was conducted to identify the significant risk factors for child hunger. Results Overall 10% of the children were found to be hungry. After adjusting for seasonality, residence type and education level of household head, the variables - female headed households [OR: 1.87 (1.43–2.45; p < 0.001], severely food insecure households [OR: 10.5 (1.43–76.6; p < 0.05], households having women with no education [OR: 1.56 (1.27–1.92; p < 0.05], poorest asset quintile [OR: 1.50 (1.11–2.15; p < 0.05] and the amount of rice consumed per household per week [OR: 0.94 (0.92–0.96; p < 0.001] were found to be significantly and independently associated with child hunger. Conclusions Out of the potential risk factors examined, our study found significant and independent association of five variables with child hunger: sex of the household head, household food insecurity status, educational status of household women and asset index. Despite all sampled household being food insecure, degree of household food insecurity status appeared to be the strongest predictor of child hunger.

  13. Fidelity deviation in quantum teleportation

    OpenAIRE

    Bang, Jeongho; Ryu, Junghee; Kaszlikowski, Dagomir

    2018-01-01

    We analyze the performance of quantum teleportation in terms of average fidelity and fidelity deviation. The average fidelity is defined as the average value of the fidelities over all possible input states and the fidelity deviation is their standard deviation, which is referred to as a concept of fluctuation or universality. In the analysis, we find the condition to optimize both measures under a noisy quantum channel---we here consider the so-called Werner channel. To characterize our resu...

  14. Food Insecurity Screening in Pediatric Primary Care: Can Offering Referrals Help Identify Families in Need?

    Science.gov (United States)

    Bottino, Clement J; Rhodes, Erinn T; Kreatsoulas, Catherine; Cox, Joanne E; Fleegler, Eric W

    2017-07-01

    To describe a clinical approach for food insecurity screening incorporating a menu offering food-assistance referrals, and to examine relationships between food insecurity and referral selection. Caregivers of 3- to 10-year-old children presenting for well-child care completed a self-administered questionnaire on a laptop computer. Items included the US Household Food Security Survey Module: 6-Item Short Form (food insecurity screen) and a referral menu offering assistance with: 1) finding a food pantry, 2) getting hot meals, 3) applying for Supplemental Nutrition Assistance Program (SNAP), and 4) applying for Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Referrals were offered independent of food insecurity status or eligibility. We examined associations between food insecurity and referral selection using multiple logistic regression while adjusting for covariates. A total of 340 caregivers participated; 106 (31.2%) reported food insecurity, and 107 (31.5%) selected one or more referrals. Forty-nine caregivers (14.4%) reported food insecurity but selected no referrals; 50 caregivers (14.7%) selected one or more referrals but did not report food insecurity; and 57 caregivers (16.8%) both reported food insecurity and selected one or more referrals. After adjustment, caregivers who selected one or more referrals had greater odds of food insecurity compared to caregivers who selected no referrals (adjusted odds ratio 4.0; 95% confidence interval 2.4-7.0). In this sample, there was incomplete overlap between food insecurity and referral selection. Offering referrals may be a helpful adjunct to standard screening for eliciting family preferences and identifying unmet social needs. Copyright © 2016 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

  15. Proof-of-concept of real-world quantum key distribution with quantum frames

    International Nuclear Information System (INIS)

    Lucio-Martinez, I; Mo, X; Tittel, W; Chan, P; Hosier, S

    2009-01-01

    We propose a fibre-based quantum key distribution system, which employs polarization qubits encoded into faint laser pulses. As a novel feature, it allows sending of classical framing information via sequences of strong laser pulses that precede the quantum data. This allows synchronization, sender and receiver identification and compensation of time-varying birefringence in the communication channel. In addition, this method also provides a platform to communicate implementation specific information such as encoding and protocol in view of future optical quantum networks. We demonstrate in a long-term (37 h) proof-of-principle study that polarization information encoded in the classical control frames can indeed be used to stabilize unwanted qubit transformation in the quantum channel. All optical elements in our setup can be operated at Gbps rates, which is a first requirement for a future system delivering secret keys at Mbps. In order to remove another bottleneck towards a high rate system, we investigate forward error correction based on low-density parity-check codes.

  16. Food insecurity among students at the University of the Free State ...

    African Journals Online (AJOL)

    with hunger”, and 26% food insecurity “without hunger”. The highest prevalence of food insecurity was in black and coloured, undergraduate, first-generation and male students, as well as in students who were unmarried, unemployed and those ...

  17. Reducing job insecurity and increasing performance ratings: does impression management matter?

    Science.gov (United States)

    Huang, Guo-hua; Zhao, Helen Hailin; Niu, Xiong-ying; Ashford, Susan J; Lee, Cynthia

    2013-09-01

    Prior research on job insecurity has demonstrated its detrimental effects on both employees and the organization, yet no research has detailed how people actively deal with it. Drawing from proactivity research, this article argues that job insecurity prompts a proactive use of impression management tactics in the workplace. The effectiveness of these tactics depends on the level of supervisory liking for the employee and the attributions supervisors make regarding the employee's motives for the impression management behaviors (i.e., for the good of the organization or for self-interest). A 3-wave survey study of 271 Chinese employees and their supervisors showed that employees experiencing job insecurity in Time 1 reported using a variety of tactics to impress their supervisors at Time 2 and that these tactics curbed the affect associated with job insecurity and enhanced supervisor rated performance, through supervisor's liking and attributed motives. The relationship between impression management and increased supervisor-rated performance was moderated by supervisor attributions; the relationship between impression management and reduced affective job insecurity depended on supervisor liking. PsycINFO Database Record (c) 2013 APA, all rights reserved

  18. Software-defined network abstractions and configuration interfaces for building programmable quantum networks

    Energy Technology Data Exchange (ETDEWEB)

    Dasari, Venkat [U.S. Army Research Laboratory, Aberdeen Proving Ground, MD; Sadlier, Ronald J [ORNL; Geerhart, Mr. Billy [U.S. Army Research Laboratory, Aberdeen Proving Ground, MD; Snow, Nikolai [U.S. Army Research Laboratory, Aberdeen Proving Ground, MD; Williams, Brian P [ORNL; Humble, Travis S [ORNL

    2017-01-01

    Well-defined and stable quantum networks are essential to realize functional quantum applications. Quantum networks are complex and must use both quantum and classical channels to support quantum applications like QKD, teleportation, and superdense coding. In particular, the no-cloning theorem prevents the reliable copying of quantum signals such that the quantum and classical channels must be highly coordinated using robust and extensible methods. We develop new network abstractions and interfaces for building programmable quantum networks. Our approach leverages new OpenFlow data structures and table type patterns to build programmable quantum networks and to support quantum applications.

  19. Household food insecurity status and Hispanic immigrant children’s body mass index and adiposity

    Science.gov (United States)

    Despite the high prevalence rates of food insecurity and obesity among children of Hispanic immigrants, there has been a dearth of research on the direct relationship between food insecurity and obesity among this population. Further, prior research examining the association between food insecurity ...

  20. Prevalence of food insecurity among food bank users in Germany and its association with population characteristics.

    Science.gov (United States)

    Depa, Julia; Gyngell, Fiona; Müller, Annalena; Eleraky, Laila; Hilzendegen, Carolin; Stroebele-Benschop, Nanette

    2018-03-01

    The prevalence of food insecurity (FI) among food bank users in many European countries is unknown. The study aims to examine FI prevalence and associated population characteristics among this particular group of disadvantaged people in Germany. Food insecurity status was assessed among 1033 adult food bank users with a mean age of 53 years (57% female, 43% male) in Germany in 2015 using the food insecurity experience scale (FIES). About half of the participants (55.8%) were single with no children and born in Germany. Over 37% had a self-reported BMI of 30 kg/m 2 or above and 37.4% indicated to smoke. Over 70% of the food bank users can be described as food insecure. Of those, about 35% were considered mildly food insecure. Almost 30% were categorized as moderately food insecure while over 7% were categorized as severely food insecure. Significant associations with food insecurity were found for gender, age, subjective health status, smoking, duration of food bank use, school education and family type. Among this socially disadvantaged population, food insecurity is highly prevalent and public health efforts should be focusing on this vulnerable population taken into account the identified population and behavioral characteristics associated with food insecurity.

  1. Towards ending conflict and insecurity in the Niger Delta region: A ...

    African Journals Online (AJOL)

    Towards ending conflict and insecurity in the Niger Delta region: A collective ... State as conflicts in different parts of the country have continued to make life insecure. ... Findings from the work show that the Federal Government's approach to ...

  2. Heat Coulomb blockade of one ballistic channel

    Science.gov (United States)

    Sivre, E.; Anthore, A.; Parmentier, F. D.; Cavanna, A.; Gennser, U.; Ouerghi, A.; Jin, Y.; Pierre, F.

    2018-02-01

    Quantum mechanics and Coulomb interaction dictate the behaviour of small circuits. The thermal implications cover fundamental topics from quantum control of heat to quantum thermodynamics, with prospects of novel thermal machines and an ineluctably growing influence on nanocircuit engineering. Experimentally, the rare observations thus far include the universal thermal conductance quantum and heat interferometry. However, evidence for many-body thermal effects paving the way to markedly different heat and electrical behaviours in quantum circuits remains wanting. Here we report on the observation of the Coulomb blockade of electronic heat flow from a small metallic circuit node, beyond the widespread Wiedemann-Franz law paradigm. We demonstrate this thermal many-body phenomenon for perfect (ballistic) conduction channels to the node, where it amounts to the universal suppression of precisely one quantum of conductance for the transport of heat, but none for electricity. The inter-channel correlations that give rise to such selective heat current reduction emerge from local charge conservation, in the floating node over the full thermal frequency range (laws for thermal transport in nanocircuits.

  3. Perceived job insecurity as a risk factor for incident coronary heart disease

    DEFF Research Database (Denmark)

    Virtanen, Marianna; Nyberg, Solja T; Batty, George David

    2013-01-01

    To determine the association between self reported job insecurity and incident coronary heart disease.......To determine the association between self reported job insecurity and incident coronary heart disease....

  4. Conceptual framework for understanding the bidirectional links between food insecurity and HIV/AIDS1234

    Science.gov (United States)

    Young, Sera L; Cohen, Craig R; Kushel, Margot B; Tsai, Alexander C; Tien, Phyllis C; Hatcher, Abigail M; Frongillo, Edward A; Bangsberg, David R

    2011-01-01

    Food insecurity, which affects >1 billion people worldwide, is inextricably linked to the HIV epidemic. We present a conceptual framework of the multiple pathways through which food insecurity and HIV/AIDS may be linked at the community, household, and individual levels. Whereas the mechanisms through which HIV/AIDS can cause food insecurity have been fairly well elucidated, the ways in which food insecurity can lead to HIV are less well understood. We argue that there are nutritional, mental health, and behavioral pathways through which food insecurity leads to HIV acquisition and disease progression. Specifically, food insecurity can lead to macronutrient and micronutrient deficiencies, which can affect both vertical and horizontal transmission of HIV, and can also contribute to immunologic decline and increased morbidity and mortality among those already infected. Food insecurity can have mental health consequences, such as depression and increased drug abuse, which, in turn, contribute to HIV transmission risk and incomplete HIV viral load suppression, increased probability of AIDS-defining illness, and AIDS-related mortality among HIV-infected individuals. As a result of the inability to procure food in socially or personally acceptable ways, food insecurity also contributes to risky sexual practices and enhanced HIV transmission, as well as to antiretroviral therapy nonadherence, treatment interruptions, and missed clinic visits, which are strong determinants of worse HIV health outcomes. More research on the relative importance of each of these pathways is warranted because effective interventions to reduce food insecurity and HIV depend on a rigorous understanding of these multifaceted relationships. PMID:22089434

  5. Food insecurity and emotional health in the USA: a systematic narrative review of longitudinal research.

    Science.gov (United States)

    Bruening, Meg; Dinour, Lauren M; Chavez, Jose B Rosales

    2017-12-01

    To examine the causal directionality in the relationship between food insecurity and emotional well-being among US-based populations. Systematic literature review from January 2006 to July 2016 using MEDLINE (PubMed), PsychInfo, Web of Science and CINHAL. Inclusion criteria were: written in English; examined a longitudinal association between food insecurity and emotional well-being. The USA. Children and adults. Twelve out of 4161 peer-reviewed articles met inclusion criteria. Three articles examined the effect of emotional well-being on food insecurity, five studies examined the effect of food insecurity on emotional well-being, and four studies examined a bidirectional relationship. Most studies (83 %) reported a positive relationship between negative emotional well-being and food insecurity over time. Findings suggest a bidirectional association whereby food insecurity increases the risk of poor emotional health, and poor emotional health increases the risk of food insecurity. Better-constructed studies are needed to follow cohorts at risk for both food insecurity and poor emotional health to further understand the mediators and moderators of the relationships. Intervention studies designed to mitigate or reverse risks are also needed to determine best evidence for practice and policy.

  6. High Prevalence of Severe Food Insecurity and Malnutrition among HIV-Infected Adults in Senegal, West Africa.

    Science.gov (United States)

    Benzekri, Noelle A; Sambou, Jacques; Diaw, Binetou; Sall, El Hadji Ibrahima; Sall, Fatima; Niang, Alassane; Ba, Selly; Ngom Guèye, Ndèye Fatou; Diallo, Mouhamadou Baïla; Hawes, Stephen E; Seydi, Moussa; Gottlieb, Geoffrey S

    2015-01-01

    Malnutrition and food insecurity are associated with increased mortality and poor clinical outcomes among people living with HIV/AIDS; however, the prevalence of malnutrition and food insecurity among people living with HIV/AIDS in Senegal, West Africa is unknown. The objective of this study was to determine the prevalence and severity of food insecurity and malnutrition among HIV-infected adults in Senegal, and to identify associations between food insecurity, malnutrition, and HIV outcomes. We conducted a cross-sectional study at outpatient clinics in Dakar and Ziguinchor, Senegal. Data were collected using participant interviews, anthropometry, the Household Food Insecurity Access Scale, the Individual Dietary Diversity Scale, and chart review. One hundred and nine HIV-1 and/or HIV-2 participants were enrolled. The prevalence of food insecurity was 84.6% in Dakar and 89.5% in Ziguinchor. The prevalence of severe food insecurity was 59.6% in Dakar and 75.4% in Ziguinchor. The prevalence of malnutrition (BMI insecurity was associated with missing clinic appointments (p = 0.01) and not taking antiretroviral therapy due to hunger (p = 0.02). Malnutrition was associated with lower CD4 cell counts (p = 0.01). Severe food insecurity and malnutrition are highly prevalent among HIV-infected adults in both Dakar and Ziguinchor, and are associated with poor HIV outcomes. Our findings warrant further studies to determine the root causes of malnutrition and food insecurity in Senegal, and the short- and long-term impacts of malnutrition and food insecurity on HIV care. Urgent interventions are needed to address the unacceptably high rates of malnutrition and food insecurity in this population.

  7. Inconsistent Access to Food and Cardiometabolic Disease: The Effect of Food Insecurity

    OpenAIRE

    Castillo, Darleen C.; Ramsey, Natalie LM; Yu, Sophia SK; Ricks, Madia; Courville, Amber B.; Sumner, Anne E.

    2012-01-01

    Food insecurity is defined as limited or uncertain ability to acquire nutritionally adequate and safe foods in socially acceptable ways. The United States Department of Agriculture (USDA) has divided food insecurity into two categories: low food security and very low food security. Low food security is characterized by irregular access to food, binge eating when food is available, overconsumption of energy-dense foods, obesity, and even type 2 diabetes. This type of food insecurity occurs in ...

  8. Agricultural support measures of advanced countries and food insecurity in developing countries

    OpenAIRE

    Herrmann, Michael

    2006-01-01

    Many developing nations, especially the least developed countries, are subjected to recurrent spells of food insecurity. In order to understand food insecurity in these countries it is necessary to consider not only immediate or trigger-causes of food crises, but also its underlying or systemic causes. This paper argues that the agricultural support measures of advanced countries may act as a systemic cause for food insecurity in developing countries. While the import of subsidized foods by d...

  9. Food Insecurity Is Associated with Obesity among US Adults in 12 States

    OpenAIRE

    Pan, Liping; Sherry, Bettylou; Njai, Rashid; Blanck, Heidi M.

    2012-01-01

    A redesigned food insecurity question that measured food stress was included in the 2009 Behavioral Risk Factor Surveillance System in the Social Context optional module. The objective of our study was to examine the association between food stress and obesity using this question as a surrogate for food insecurity. Our analytic sample included 66,553 adults from 12 states. Food insecurity was determined by response (always/usually/sometimes) to the question,“Howoften in the past 12 months wou...

  10. Urban Insecurity as a Language of Political Contention in Madrid (Spain

    Directory of Open Access Journals (Sweden)

    Montserrat Cañedo Rodríguez

    2013-07-01

    Full Text Available Public policies for urban planning developed since the 1980s in Spanish city centres have been marked by the idea of “refurbishing” areas that are “in crisis.” The discourse of citizens’ insecurity has become the framework of shared meaning for diagnosing problems, as well as for legitimizing policies. Using an ethnographic analysis carried out in a central Madrid neighbourhood, I will analyze how the experience of insecurity of one sector of the residents, which is shaped in the framework of the general discourse of citizen insecurity, is, however, rooted in a specific life trajectory that indicates socio-cultural and economic keys that have little to do with the causes of insecurity that the hegemonic discourse continually indicates. More generally, I hope to show, with this case study, how anthropological analyses can contribute to the evaluation of public urban policies.

  11. Free-Space Quantum Communication with a Portable Quantum Memory

    Science.gov (United States)

    Namazi, Mehdi; Vallone, Giuseppe; Jordaan, Bertus; Goham, Connor; Shahrokhshahi, Reihaneh; Villoresi, Paolo; Figueroa, Eden

    2017-12-01

    The realization of an elementary quantum network that is intrinsically secure and operates over long distances requires the interconnection of several quantum modules performing different tasks. In this work, we report the realization of a communication network functioning in a quantum regime, consisting of four different quantum modules: (i) a random polarization qubit generator, (ii) a free-space quantum-communication channel, (iii) an ultralow-noise portable quantum memory, and (iv) a qubit decoder, in a functional elementary quantum network possessing all capabilities needed for quantum-information distribution protocols. We create weak coherent pulses at the single-photon level encoding polarization states |H ⟩ , |V ⟩, |D ⟩, and |A ⟩ in a randomized sequence. The random qubits are sent over a free-space link and coupled into a dual-rail room-temperature quantum memory and after storage and retrieval are analyzed in a four-detector polarization analysis akin to the requirements of the BB84 protocol. We also show ultralow noise and fully portable operation, paving the way towards memory-assisted all-environment free-space quantum cryptographic networks.

  12. The relationship between leader-follower exchange and job insecurity: The mediating role of trust

    Directory of Open Access Journals (Sweden)

    Olufemi Adigun Lawal

    2016-07-01

    Full Text Available The study examines the extent and nature of mediational roles of affective and cognitive trusts on the predictive relationship between leader-member exchange (LMX and job insecurity. Six hundred and twenty-six employees are surveyed through questionnaire administration. Analysis of the data is done with simple regression and multiple regression analyses. The findings show no significant prediction of job insecurity by affective trust as well as no significant mediation of the LMX and job insecurity relationship by affective trust. The study also shows significant prediction of job insecurity by LMX, and significant mediation of the LMX-job insecurity relationship by cognitive trust. The results are discussed in the light of reviewed literature and current realities. The implications of the study are also highlighted.

  13. Who is food-insecure in California? Findings from the California Women's Health Survey, 2004.

    Science.gov (United States)

    Kaiser, Lucia; Baumrind, Nikki; Dumbauld, Sheila

    2007-06-01

    To identify factors associated with food insecurity in California women. The California Women's Health Survey is an ongoing annual telephone survey that collects data about health-related attitudes and behaviours from a randomly selected sample of women. Food insecurity of the women was measured by a 6-item subset of the Food Security Module. Statistical procedures included chi-square tests, t-tests, logistic regression analysis and analysis of covariance. California, USA. Four thousand and thirty-seven women (18 years or older). Prevalence of food insecurity was 25.7%. After controlling for income, factors associated with greater food insecurity were Hispanic or Black race/ethnicity; less than a 12th grade education; being unmarried; less than 55 years old; being Spanish-speaking; having spent less than half of one's life in the USA; sadness/depression; feeling overwhelmed; poor physical/mental health interfering with activities; and fair to poor general health. Among Food Stamp Program (FSP) participants, 71% were food-insecure. Among FSP-eligible women who had not applied for the programme, the prevalence of food insecurity was lower among women responding that they did not need food stamps than in women giving other reasons for not applying (23.9% vs. 66.9%, P < 0.001). Factors associated with food insecurity in FSP recipients included being unable to make food stamps last for 30 days, feeling overwhelmed, and having a birthplace in Mexico or Central America. Along with several socio-economic variables, poor physical and mental health is associated with food insecurity. Whether food insecurity is a cause or effect of poor health remains in question.

  14. Need depriving effects of financial insecurity: Implications for well-being and financial behaviors.

    Science.gov (United States)

    Weinstein, Netta; Stone, Dan N

    2018-06-28

    Evidence suggests that experiencing financial insecurity lowers well-being and increases problematic financial behaviors. The present article employs a self-determination theory (SDT; R. M. Ryan & Deci, 2000a) perspective to understand the mechanisms by which experiencing financial insecurity contributes to these detrimental outcomes. Informed by SDT, we expected that the basic psychological needs for autonomy, competence, and relatedness would drive these effects. Studies were concerned with individuals' general experiences of financial insecurity (using community samples; Studies 1 and 2), and employed manipulations involving self-reflection (Study 3) and hypothetical scenarios (Study 4). Findings demonstrated that financially insecure conditions undermined basic psychological needs and lowered well-being (measured in terms of self-esteem, depression, and anxiety). In addition, lower satisfaction of basic psychological needs linked financial insecurity to a greater likelihood of engaging in financial cheating (Studies 2 and 3) and risky financial decisions (Study 4). Importantly, this pattern of effects remained in evidence across socioeconomically diverse samples and income levels. We discuss implications for future interventions to improve the wellness of individuals in financially insecure circumstances. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  15. An assessment of the impact of energy insecurity on state stability in India

    International Nuclear Information System (INIS)

    Varigonda, Kesava Chandra

    2013-01-01

    This paper studies the relation between energy insecurity and state stability in India. Primarily it looks at the ways in which specific aspects of energy insecurity impact the stability of the Indian state. The paper contends that energy insecurity in the form of fuel supply and electricity supply insecurities gives rise to social and political instability, which in extreme forms could lead to state destabilisation. A combination of inadequate and unreasonably priced fuel supply gives rise to instability in the social and political spheres; if the fuel supply is also unreliable, it could lead to chronic socio-political instability. Likewise, a combination of inadequate and unreliable electricity supply could, in certain instances, cause limited social instability; if this is also accompanied by an electricity price hike, it could lead to chronic socio-political instability. Chronic socio-political instability in an already weakened state could facilitate state destabilisation. - Highlights: • Studies the impact of energy insecurity on the stability of the Indian state. • Secondary sources from press releases of the last three decades are examined. • Fuel supply and electricity supply insecurities cause socio-political instability. • Chronic socio-political instability may lead to destabilisation of a week state

  16. Developing and Implementing a Food Insecurity Screening Initiative for Adult Patients Living With Type 2 Diabetes.

    Science.gov (United States)

    Thomas, Brittany; Fitzpatrick, Sandra; Sidani, Souraya; Gucciardi, Enza

    2018-06-01

    Routine food insecurity screening is recommended in diabetes care to inform more tailored interventions that better support diabetes self-management among food-insecure patients. This pilot study explored the acceptability and feasibility of a food insecurity screening initiative within a diabetes care setting in Toronto. A systematic literature review informed the development of a food insecurity screening initiative to help health-care providers tailor diabetes management plans and better support food-insecure patients with type 2 diabetes. Interviews with 10 patients and a focus group with 15 care providers elicited feedback on the relevance and acceptance of the food insecurity screening questions and a care algorithm. Subsequently, 5 care providers at 4 sites implemented the screening initiative over 2 weeks, screening 33 patients. After implementation, 7 patients and 5 care providers were interviewed to assess the acceptability and feasibility of the screening initiative. Our findings demonstrate that patients are willing to share their experiences of food insecurity, despite the sensitivity of this topic. Screening elicited information about how patients cope with food insecurity and how this affects their ability to self-manage diabetes. Care providers found this information helpful in directing their care and support for patients. Using a standardized, respectful method of assessing food insecurity can better equip health-care providers to support food-insecure patients with diabetes self-management. Further evaluation of this initiative is needed to determine how food insecurity screening can affect patients' self-management and related health outcomes. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  17. The Association between Food Insecurity and Obesity in Children-The National Health and Nutrition Examination Survey.

    Science.gov (United States)

    Kaur, Jasbir; Lamb, Molly M; Ogden, Cynthia L

    2015-05-01

    Food insecurity can put children at greater risk of obesity because of altered food choices and nonuniform consumption patterns. We examined the association between obesity and both child-level food insecurity and personal food insecurity in US children. Data from 9,701 participants in the National Health and Nutrition Examination Survey, 2001-2010, aged 2 to 11 years were analyzed. Child-level food insecurity was assessed with the US Department of Agriculture's Food Security Survey Module based on eight child-specific questions. Personal food insecurity was assessed with five additional questions. Obesity was defined, using physical measurements, as body mass index (calculated as kg/m²) greater than or equal to the age- and sex-specific 95th percentile of the Centers for Disease Control and Prevention growth charts. Logistic regressions adjusted for sex, race/ethnic group, poverty level, and survey year were conducted to describe associations between obesity and food insecurity. Obesity was significantly associated with personal food insecurity for children aged 6 to 11 years (odds ratio=1.81; 95% CI 1.33 to 2.48), but not in children aged 2 to 5 years (odds ratio=0.88; 95% CI 0.51 to 1.51). Child-level food insecurity was not associated with obesity among 2- to 5-year-olds or 6- to 11-year-olds. Personal food insecurity is associated with an increased risk of obesity only in children aged 6 to 11 years. Personal food-insecurity measures may give different results than aggregate food-insecurity measures in children. Published by Elsevier Inc.

  18. High Prevalence of Severe Food Insecurity and Malnutrition among HIV-Infected Adults in Senegal, West Africa.

    Directory of Open Access Journals (Sweden)

    Noelle A Benzekri

    Full Text Available Malnutrition and food insecurity are associated with increased mortality and poor clinical outcomes among people living with HIV/AIDS; however, the prevalence of malnutrition and food insecurity among people living with HIV/AIDS in Senegal, West Africa is unknown. The objective of this study was to determine the prevalence and severity of food insecurity and malnutrition among HIV-infected adults in Senegal, and to identify associations between food insecurity, malnutrition, and HIV outcomes.We conducted a cross-sectional study at outpatient clinics in Dakar and Ziguinchor, Senegal. Data were collected using participant interviews, anthropometry, the Household Food Insecurity Access Scale, the Individual Dietary Diversity Scale, and chart review.One hundred and nine HIV-1 and/or HIV-2 participants were enrolled. The prevalence of food insecurity was 84.6% in Dakar and 89.5% in Ziguinchor. The prevalence of severe food insecurity was 59.6% in Dakar and 75.4% in Ziguinchor. The prevalence of malnutrition (BMI <18.5 was 19.2% in Dakar and 26.3% in Ziguinchor. Severe food insecurity was associated with missing clinic appointments (p = 0.01 and not taking antiretroviral therapy due to hunger (p = 0.02. Malnutrition was associated with lower CD4 cell counts (p = 0.01.Severe food insecurity and malnutrition are highly prevalent among HIV-infected adults in both Dakar and Ziguinchor, and are associated with poor HIV outcomes. Our findings warrant further studies to determine the root causes of malnutrition and food insecurity in Senegal, and the short- and long-term impacts of malnutrition and food insecurity on HIV care. Urgent interventions are needed to address the unacceptably high rates of malnutrition and food insecurity in this population.

  19. Household Food Insecurity Is Associated with Nutritional Status among Iranian Children.

    Science.gov (United States)

    Shahraki, Soudabeh Hamedi; Amirkhizi, Farshad; Amirkhizi, Behzad; Hamedi, Sousan

    2016-01-01

    This cross-sectional study was conducted to determine household food security status and sociodemographic factors influencing it and to examine whether food insecurity of household is a risk factor for underweight, stunting, and thinness in primary school children of Sistan and Baluchestan Province in southeastern Iran. A sample of 610 students aged 7-11 years was selected by a multistage cluster random sampling method during December 2013-May 2014. Using U.S. Department of Agriculture Food Security questionnaire, 42.3% of households showed some degree of food insecurity. Food insecurity was positively associated with household size (p = .002) and number of children per household (p = .001) and negatively associated with mother's and father's education level (p = .005 and p = .042, respectively), father's occupation status, and household income (p Children living in food insecure with severe hunger households were 10.13, 10.07, and 4.54 times as likely to be underweight, stunted, and thin, respectively, as counterparts from food secure households. The findings showed food insecurity was prevalent and associated with sociodemographic factors among households with schoolchildren in southeastern Iran. Nutritional status of children was also associated with food security status of their households.

  20. Measuring household food insecurity: why it's so important and yet so difficult to do.

    Science.gov (United States)

    Webb, Patrick; Coates, Jennifer; Frongillo, Edward A; Rogers, Beatrice Lorge; Swindale, Anne; Bilinsky, Paula

    2006-05-01

    Food insecurity is a daily reality for hundreds of millions of people around the world. Although its most extreme manifestations are often obvious, many other households facing constraints in their access to food are less identifiable. Operational agencies lack a method for differentiating households at varying degrees of food insecurity in order to target and evaluate their interventions. This chapter provides an overview of a set of papers associated with a research initiative that seeks to identify more precise, yet simple, measures of household food insecurity. The overview highlights three main conceptual developments associated with practical approaches to measuring constraints in access to food: 1) a shift from using measures of food availability and utilization to measuring "inadequate access"; 2) a shift from a focus on objective to subjective measures; and 3) a growing emphasis on fundamental measurement as opposed to reliance on distal, proxy measures. Further research is needed regarding 1) how well measures of household food insecurity designed for chronically food-insecure contexts capture the processes leading to, and experience of, acute food insecurity, 2) the impact of short-term shocks, such as major floods or earthquake, on household behaviors that determine responses to food security questions, 3) better measurement of the interaction between severity and frequency of household food insecurity behaviors, and 4) the determination of whether an individual's response to survey questions can be representative of the food insecurity experiences of all members of the household.

  1. Association between overweight, obesity and self-perceived job insecurity in German employees

    Directory of Open Access Journals (Sweden)

    Letzel Stephan

    2011-03-01

    Full Text Available Abstract Background Recent studies have shown an association between job insecurity and morbidity as well as mortality, however until now, knowledge about a potential association between job insecurity and overweight or obesity has been lacking. Methods In order to identify a possible association between job insecurity and overweight or obesity, we analysed data from the German Socioeconomic Panel (GSOEP 2004/2005, a longitudinal study of private households in Germany. In this representative cohort of the German adult population, living and working conditions were observed. Data on Body Mass Index (BMI and self-perceived probability of job loss within the next 2 years were available for 10,747 adults either employed or attending training programs. Results We identified 5,216 (49% individuals as being overweight (BMI > 25 kg/m2 and 1,358(13% individuals as being obese (BMI > 30 kg/m2. A total of 5,941 (55% participants reported having concerns regarding job insecurity. In the multivariate analysis - after adjustment for relevant confounders - a statistically significant association between obesity and job insecurity (100% probability for losing the job in the following two years could be observed with an adjusted odds ratio of 2.55 (95% confidence interval: 1.09-5.96. Conclusions Because of these results, we were able to conclude that overweight and obese persons perceive job insecurity more often than their normal weight counterparts in Germany and that the concurrence of obesity and job insecurity might lead employees into a vicious cycle. Further research with an emphasis on the occupational setting might be necessary in order to establish useful preventive programmes at the workplace.

  2. Insecure Commitment and Resistance: An Examination of Change Leadership, Self-Efficacy, and Trust on the Relationship between Job Insecurity, Employee Commitment, and Resistance to Organizational Change

    Science.gov (United States)

    Smith, Robert Elijah

    2013-01-01

    This study was designed to examine the mediation role of self-efficacy and the moderating roles of change leadership strategy and trust on the change attitudes of job insecure employees. Using job insecurity theory (Greenhalgh, 1983), Chin & Benne's (1961) seminal classification of change leadership strategies and the tripartite model of…

  3. Introduction to quantum information science

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Masahito [Nagoya Univ. (Japan). Graduate School of Mathematics; Ishizaka, Satoshi [Hiroshima Univ., Higashi-Hiroshima (Japan). Graduate School of Integrated Arts and Sciences; Kawachi, Akinori [Tokyo Institute of Technology (Japan). Dept. of Mathematical and Computing Sciences; Kimura, Gen [Shibaura Institute of Technology, Saitama (Japan). College of Systems Engineering and Science; Ogawa, Tomohiro [Univ. of Electro-Communications, Tokyo (Japan). Graduate School of Information Systems

    2015-04-01

    Presents the mathematical foundation for quantum information in a very didactic way. Summarizes all required mathematical knowledge in linear algebra. Supports teaching and learning with more than 100 exercises with solutions. Includes brief descriptions to recent results with references. This book presents the basics of quantum information, e.g., foundation of quantum theory, quantum algorithms, quantum entanglement, quantum entropies, quantum coding, quantum error correction and quantum cryptography. The required knowledge is only elementary calculus and linear algebra. This way the book can be understood by undergraduate students. In order to study quantum information, one usually has to study the foundation of quantum theory. This book describes it from more an operational viewpoint which is suitable for quantum information while traditional textbooks of quantum theory lack this viewpoint. The current book bases on Shor's algorithm, Grover's algorithm, Deutsch-Jozsa's algorithm as basic algorithms. To treat several topics in quantum information, this book covers several kinds of information quantities in quantum systems including von Neumann entropy. The limits of several kinds of quantum information processing are given. As important quantum protocols,this book contains quantum teleportation, quantum dense coding, quantum data compression. In particular conversion theory of entanglement via local operation and classical communication are treated too. This theory provides the quantification of entanglement, which coincides with von Neumann entropy. The next part treats the quantum hypothesis testing. The decision problem of two candidates of the unknown state are given. The asymptotic performance of this problem is characterized by information quantities. Using this result, the optimal performance of classical information transmission via noisy quantum channel is derived. Quantum information transmission via noisy quantum channel by quantum error

  4. Introduction to quantum information science

    International Nuclear Information System (INIS)

    Hayashi, Masahito; Ishizaka, Satoshi; Kawachi, Akinori; Kimura, Gen; Ogawa, Tomohiro

    2015-01-01

    Presents the mathematical foundation for quantum information in a very didactic way. Summarizes all required mathematical knowledge in linear algebra. Supports teaching and learning with more than 100 exercises with solutions. Includes brief descriptions to recent results with references. This book presents the basics of quantum information, e.g., foundation of quantum theory, quantum algorithms, quantum entanglement, quantum entropies, quantum coding, quantum error correction and quantum cryptography. The required knowledge is only elementary calculus and linear algebra. This way the book can be understood by undergraduate students. In order to study quantum information, one usually has to study the foundation of quantum theory. This book describes it from more an operational viewpoint which is suitable for quantum information while traditional textbooks of quantum theory lack this viewpoint. The current book bases on Shor's algorithm, Grover's algorithm, Deutsch-Jozsa's algorithm as basic algorithms. To treat several topics in quantum information, this book covers several kinds of information quantities in quantum systems including von Neumann entropy. The limits of several kinds of quantum information processing are given. As important quantum protocols,this book contains quantum teleportation, quantum dense coding, quantum data compression. In particular conversion theory of entanglement via local operation and classical communication are treated too. This theory provides the quantification of entanglement, which coincides with von Neumann entropy. The next part treats the quantum hypothesis testing. The decision problem of two candidates of the unknown state are given. The asymptotic performance of this problem is characterized by information quantities. Using this result, the optimal performance of classical information transmission via noisy quantum channel is derived. Quantum information transmission via noisy quantum channel by quantum error correction are

  5. Examining the Impact of Structural Racism on Food Insecurity: Implications for Addressing Racial/Ethnic Disparities.

    Science.gov (United States)

    Odoms-Young, Angela; Bruce, Marino A

    Food insecurity is defined as "a household-level economic and social condition of limited or uncertain access to adequate food." While, levels of food insecurity in the United States have fluctuated over the past 20 years; disparities in food insecurity rates between people of color and whites have continued to persist. There is growing recognition that discrimination and structural racism are key contributors to disparities in health behaviors and outcomes. Although several promising practices to reduce food insecurity have emerged, approaches that address structural racism and discrimination may have important implications for alleviating racial/ethnic disparities in food insecurity and promoting health equity overall.

  6. Optimal unitary dilation for bosonic Gaussian channels

    International Nuclear Information System (INIS)

    Caruso, Filippo; Eisert, Jens; Giovannetti, Vittorio; Holevo, Alexander S.

    2011-01-01

    A general quantum channel can be represented in terms of a unitary interaction between the information-carrying system and a noisy environment. In this paper the minimal number of quantum Gaussian environmental modes required to provide a unitary dilation of a multimode bosonic Gaussian channel is analyzed for both pure and mixed environments. We compute this quantity in the case of pure environment corresponding to the Stinespring representation and give an improved estimate in the case of mixed environment. The computations rely, on one hand, on the properties of the generalized Choi-Jamiolkowski state and, on the other hand, on an explicit construction of the minimal dilation for arbitrary bosonic Gaussian channel. These results introduce a new quantity reflecting ''noisiness'' of bosonic Gaussian channels and can be applied to address some issues concerning transmission of information in continuous variables systems.

  7. Household food insecurity and dietary patterns in rural and urban American Indian families with young children

    Directory of Open Access Journals (Sweden)

    Emily J. Tomayko

    2017-06-01

    Full Text Available Abstract Background High food insecurity has been demonstrated in rural American Indian households, but little is known about American Indian families in urban settings or the association of food insecurity with diet for these families. The purpose of this study was to examine the prevalence of food insecurity in American Indian households by urban-rural status, correlates of food insecurity in these households, and the relationship between food insecurity and diet in these households. Methods Dyads consisting of an adult caregiver and a child (2–5 years old from the same household in five urban and rural American Indian communities were included. Demographic information was collected, and food insecurity was assessed using two validated items from the USDA Household Food Security Survey. Factors associated with food insecurity were examined using logistic regression. Child and adult diets were assessed using food screeners. Coping strategies were assessed through focus group discussions. These cross-sectional baseline data were collected from 2/2013 through 4/2015 for the Healthy Children, Strong Families 2 randomized controlled trial of a healthy lifestyles intervention for American Indian families. Results A high prevalence of food insecurity was determined (61% and was associated with American Indian ethnicity, lower educational level, single adult households, WIC participation, and urban settings (p = 0.05. Food insecure adults had significantly lower intake of vegetables (p < 0.05 and higher intakes of fruit juice (<0.001, other sugar-sweetened beverages (p < 0.05, and fried potatoes (p < 0.001 than food secure adults. Food insecure children had significantly higher intakes of fried potatoes (p < 0.05, soda (p = 0.01, and sports drinks (p < 0.05. Focus group participants indicated different strategies were used by urban and rural households to address food insecurity. Conclusions The prevalence of food insecurity in

  8. Associations between food insecurity and the severity of psychological distress among African-Americans.

    Science.gov (United States)

    Allen, Nickolas L; Becerra, Benjamin J; Becerra, Monideepa B

    2018-07-01

    Little research exists on the association between food insecurity and mild to moderate psychological distress (MPD) among Black/African-Americans. In this study, we assess the relationship between food insecurity with and without hunger to that of both MPD and serious psychological distress (SPD) among this population. 2009 and 2011/2012 adult public-use data from African-American respondents of the California Health Interview Survey were utilized for this study (n = 4003). Descriptive statistics were utilized to identify prevalence of psychological distress among sociodemographic and mental-health associated variables. Bivariate analyses were conducted between these variables and psychological distress using survey-weighted chi-square analyses. To evaluate the association between psychological distress, our primary exposure variable of food security, and other variables, we utilized survey-weighted multinomial logistic regression. Prevalence of mild to MPD was higher among those reporting food insecurity while SPD was highest for those with food insecurity and hunger. Results of multinomial logistic regression analysis demonstrate that while MPD was significantly associated with food insecurity, Black/African-Americans with food insecurity and hunger displayed over sixfold odds of higher serious psychological distress, as compared to those living at or above 200% federal poverty level. Our findings add to this growing segment of the literature on psychological distress and food insecurity. Further focus should be placed on improving the efficacy and reach of both formal and informal food support networks to improve the collective health and well-being of poor Black/African-American communities.

  9. Perceived job insecurity as a risk factor for incident coronary heart disease

    DEFF Research Database (Denmark)

    Virtanen, Marianna; Nyberg, Solja T; Batty, George David

    2013-01-01

    OBJECTIVE: To determine the association between self reported job insecurity and incident coronary heart disease. DESIGN: A meta-analysis combining individual level data from a collaborative consortium and published studies identified by a systematic review. DATA SOURCES: We obtained individual....... REVIEW METHODS: Prospective cohort studies that reported risk estimates for clinically verified incident coronary heart disease by the level of self reported job insecurity. Two independent reviewers extracted published data. Summary estimates of association were obtained using random effects models...... versus low job insecurity was 1.32 (95% confidence interval 1.09 to 1.59). The relative risk of job insecurity adjusted for sociodemographic and risk factors was 1.19 (1.00 to 1.42). There was no evidence of significant differences in this association by sex, age (

  10. Food Insecurity among Community College Students: Prevalence and Relationship to GPA, Energy, and Concentration

    Science.gov (United States)

    Maroto, Maya E.

    2013-01-01

    The latest U.S. government surveys indicate that one in six Americans suffer from food insecurity, which means they have trouble affording adequate food. Previous research has shown that food insecurity affects adult cognitive ability, energy levels, ability to concentrate as well as child academic success. Food insecurity has been studied in…

  11. Key distillation in quantum cryptography

    Science.gov (United States)

    Slutsky, Boris Aron

    1998-11-01

    Quantum cryptography is a technique which permits two parties to communicate over an open channel and establish a shared sequence of bits known only to themselves. This task, provably impossible in classical cryptography, is accomplished by encoding the data on quantum particles and harnessing their unique properties. It is believed that no eavesdropping attack consistent with the laws of quantum theory can compromise the secret data unknowingly to the legitimate users of the channel. Any attempt by a hostile actor to monitor the data carrying particles while in transit reveals itself through transmission errors it must inevitably introduce. Unfortunately, in practice a communication is not free of errors even when no eavesdropping is present. Key distillation is a technique that permits the parties to overcome this difficulty and establish a secret key despite channel defects, under the assumption that every particle is handled independently from other particles by the enemy. In the present work, key distillation is described and its various aspects are studied. A relationship is derived between the average error rate resulting from an eavesdropping attack and the amount of information obtained by the attacker. Formal definition is developed of the security of the final key. The net throughput of secret bits in a quantum cryptosystem employing key distillation is assessed. An overview of quantum cryptographic protocols and related information theoretical results is also given.

  12. Resource Theory of Quantum Memories and Their Faithful Verification with Minimal Assumptions

    Science.gov (United States)

    Rosset, Denis; Buscemi, Francesco; Liang, Yeong-Cherng

    2018-04-01

    We provide a complete set of game-theoretic conditions equivalent to the existence of a transformation from one quantum channel into another one, by means of classically correlated preprocessing and postprocessing maps only. Such conditions naturally induce tests to certify that a quantum memory is capable of storing quantum information, as opposed to memories that can be simulated by measurement and state preparation (corresponding to entanglement-breaking channels). These results are formulated as a resource theory of genuine quantum memories (correlated in time), mirroring the resource theory of entanglement in quantum states (correlated spatially). As the set of conditions is complete, the corresponding tests are faithful, in the sense that any non-entanglement-breaking channel can be certified. Moreover, they only require the assumption of trusted inputs, known to be unavoidable for quantum channel verification. As such, the tests we propose are intrinsically different from the usual process tomography, for which the probes of both the input and the output of the channel must be trusted. An explicit construction is provided and shown to be experimentally realizable, even in the presence of arbitrarily strong losses in the memory or detectors.

  13. Memory effects in attenuation and amplification quantum processes

    International Nuclear Information System (INIS)

    Lupo, Cosmo; Giovannetti, Vittorio; Mancini, Stefano

    2010-01-01

    With increasing communication rates via quantum channels, memory effects become unavoidable whenever the use rate of the channel is comparable to the typical relaxation time of the channel environment. We introduce a model of a bosonic memory channel, describing correlated noise effects in quantum-optical processes via attenuating or amplifying media. To study such a channel model, we make use of a proper set of collective field variables, which allows us to unravel the memory effects, mapping the n-fold concatenation of the memory channel to a unitarily equivalent, direct product of n single-mode bosonic channels. We hence estimate the channel capacities by relying on known results for the memoryless setting. Our findings show that the model is characterized by two different regimes, in which the cross correlations induced by the noise among different channel uses are either exponentially enhanced or exponentially reduced.

  14. Adverse health effects of experiencing food insecurity among Greenlandic school children

    Directory of Open Access Journals (Sweden)

    Birgit Niclasen

    2013-08-01

    Full Text Available Background. In vulnerable populations, food security in children has been found to be associated with negative health effects. Still, little is known about whether the negative health effects can be retrieved in children at the population level. Objective. To examine food insecurity reported by Greenlandic school children as a predictor for perceived health, physical symptoms and medicine use. Design. The study is based on the Greenlandic part of the Health Behaviour in School-aged Children survey. The 2010 survey included 2,254 students corresponding to 40% of all Greenlandic school children in Grade 5 through 10. The participation rate in the participating schools was 65%. Food insecurity was measured as going to bed or to school hungry because there was no food at home. Results. Boys, the youngest children (11–12 year-olds, and children from low affluence homes were at increased risk for food insecurity. Poor or fair self-rated health, medicine use last month and physical symptoms during the last 6 months were all more frequent in children reporting food insecurity. Controlling for age, gender and family affluence odds ratio (OR for self-rated health was 1.60 (95% confidence interval (CI 1.23–2.06 (p<0.001, for reporting physical symptoms 1.34 (95% CI 1.06–1.68 (p=0.01 and for medicine use 1.79 (95% CI 1.42–2.26 (p<0.001. Stratification on age groups suggested that children in different age groups experience different health consequences of food insecurity. The oldest children reported food insecurity less often and experienced less negative health effects compared to the younger children. Conclusions. All 3 measures of health were negatively associated to the occurrence of food insecurity in Greenlandic school children aged 11–17. Food security must be seen as a public health issue of concern, and policies should be enforced to prevent food poverty particularly among boys, younger school children and children from low affluence

  15. Association between food insecurity and anemia among women of reproductive age

    Directory of Open Access Journals (Sweden)

    Bishwajit Ghose

    2016-05-01

    Full Text Available Background: Food insecurity and hidden hunger (micronutrient deficiency affect about two billion people globally. Household food insecurity (HFI has been shown to be associated with one or multiple micronutrient (MMN deficiencies among women and children. Chronic food insecurity leads to various deficiency disorders, among which anemia stands out as the most prevalent one. As a high malnutrition prevalent country, Bangladesh has one of the highest rates of anemia among all Asian countries. In this study, we wanted to investigate for any association exists between HFI and anemia among women of reproductive age in Bangladesh. Methodology: Information about demographics, socioeconomic and anemia status on 5,666 married women ageing between 13 and 40 years were collected from a nationally representative cross-sectional survey Bangladesh Demographic and Health Survey (BDHS 2011. Food security was measured by the Household Food Insecurity Access Scale (HFIAS. Capillary hemoglobin concentration (Hb measured by HemoCue® was used as the biomarker of anemia. Data were analysed using cross-tabulation, chi-square tests and multiple logistic regression methods. Results: Anemia prevalence was 41.7%. Logistic regression showed statistically significant association with anemia and type of residency (p = 0.459; OR = 0.953, 95%CI = 0.840–1.082, wealth status (Poorest: p < 0.001; OR = 1.369, 95%CI = 1.176–1.594; and average: p = 0.030; 95%CI = 1.017–1.398, educational attainment (p < 0.001; OR = 1.276, 95%CI = 1.132–1.439 and household food insecurity (p < 0.001; 95%CI = 1.348–1.830. Women who reported food insecurity were about 1.6 times more likely to suffer from anemia compared to their food secure counterparts. Conclusion: HFI is a significant predictor of anemia among women of reproductive age in Bangladesh. Programs targeting HFI could prove beneficial for anemia reduction strategies. Gender aspects of food and nutrition insecurity should be taken

  16. Quantum Secure Direct Communication by Using Three-Dimensional Hyperentanglement

    International Nuclear Information System (INIS)

    Shi Jin; Gong Yanxiao; Xu Ping; Zhu Shining; Zhan Youbang

    2011-01-01

    We propose two schemes for realizing quantum secure direct communication (QSDC) by using a set of ordered two-photon three-dimensional hyperentangled states entangled in two degrees of freedom (DOFs) as quantum information channels. In the first scheme, the photons from Bob to Alice are transmitted only once. After insuring the security of the quantum channels, Bob encodes the secret message on his photons. Then Alice performs single-photon two-DOF Bell bases measurements on her photons. This scheme has better security than former QSDC protocols. In the second scheme, Bob transmits photons to Alice twice. After insuring the security of the quantum channels, Bob encodes the secret message on his photons. Then Alice performs two-photon Bell bases measurements on each DOF. The scheme has more information capacity than former QSDC protocols. (general)

  17. Hunger and Food Insecurity in the Fifty States: 1998-2000.

    Science.gov (United States)

    Sullivan, Ashley F.; Choi, Eunyoung

    Noting that the persistence of hunger and food insecurity in the United States is an issue of pressing social and public health concern, this study examined the magnitude and severity of hunger and food insecurity in U.S. households in each of the 50 states and the District of Columbia. Data were obtained from the August 1998, April 1999, and…

  18. Location-dependent communications using quantum entanglement

    International Nuclear Information System (INIS)

    Malaney, Robert A.

    2010-01-01

    The ability to unconditionally verify the location of a communication receiver would lead to a wide range of new security paradigms. However, it is known that unconditional location verification in classical communication systems is impossible. In this work we show how unconditional location verification can be achieved with the use of quantum communication channels. Our verification remains unconditional irrespective of the number of receivers, computational capacity, or any other physical resource held by an adversary. Quantum location verification represents an application of quantum entanglement that delivers a feat not possible in the classical-only channel. It gives us the ability to deliver real-time communications viable only at specified geographical coordinates.

  19. Job insecurity and its association with health among employees in the Taiwanese general population.

    Science.gov (United States)

    Cheng, Yawen; Chen, Chun-Wan; Chen, Chiou-Jong; Chiang, Tung-liang

    2005-07-01

    As employers respond to intensive global competition through the deregulation of labor, job insecurity has become a widespread problem. It has been shown to have significant health impacts in a growing number of workers, but less is known about its social distribution, the mechanisms through which it may act, and the moderating effects of gender, socioeconomic position, and company size. Utilizing data from a national survey of a representative sample of paid employees in Taiwan, we examined the prevalence of job insecurity and its associations with psychosocial work characteristics and health status. A total of 8705 men and 5986 women aged between 25 and 65 years old were studied. Information on perceived job insecurity, industrial and occupational types, psychosocial work characteristics as assessed by the Job Strain model, and various measures of health status were obtained by a self-administered questionnaire. The overall prevalence of job insecurity was high (50%). Job insecurity was more prevalent among employees with lower education attainment, in blue-collar and construction workers, those employed in smaller companies, and in older women. Insecure employees also reported lower job control, higher job demands, and poor workplace social support, as compared with those who held secure positions. Regression analyses showed that job insecurity was strongly associated with poor health, even with adjustment of age, job control, job demands, and work place social support. The deleterious effects of job insecurity appeared to be stronger in men than women, in women who held managerial or professional jobs than women in other employment grades, and in those working in larger companies than smaller ones. The findings of this study suggest that perceived job insecurity is an important source of stress, and it is accompanied with adverse psychosocial work conditions and poor health. High-risk groups were identified for further investigation.

  20. Food insecurity and mental disorders in a national sample of U.S. adolescents.

    Science.gov (United States)

    McLaughlin, Katie A; Green, Jennifer Greif; Alegría, Margarita; Jane Costello, E; Gruber, Michael J; Sampson, Nancy A; Kessler, Ronald C

    2012-12-01

    To examine whether food insecurity is associated with past-year DSM-IV mental disorders after controlling for standard indicators of family socioeconomic status (SES) in a U.S. national sample of adolescents. Data were drawn from 6,483 adolescent-parent pairs who participated in the National Comorbidity Survey Replication Adolescent Supplement, a national survey of adolescents 13 to 17 years old. Frequency and severity of food insecurity were assessed with questions based on the U.S. Department of Agriculture's Food Security Scale (standardized to a mean of 0, variance of 1). DSM-IV mental disorders were assessed with the World Health Organization Composite International Diagnostic Interview. Associations of food insecurity with DSM-IV/Composite International Diagnostic Interview diagnoses were estimated with logistic regression models controlling for family SES (parental education, household income, relative deprivation, community-level inequality, and subjective social status). Food insecurity was highest in adolescents with the lowest SES. Controlling simultaneously for other aspects of SES, standardized food insecurity was associated with an increased odds of past-year mood, anxiety, behavior, and substance disorders. A 1 standard deviation increase in food insecurity was associated with a 14% increase in the odds of past-year mental disorder, even after controlling for extreme poverty. The association between food insecurity and mood disorders was strongest in adolescents living in families with a low household income and high relative deprivation. Food insecurity is associated with a wide range of adolescent mental disorders independently of other aspects of SES. Expansion of social programs aimed at decreasing family economic strain might be one useful policy approach for improving youth mental health. Copyright © 2012 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

  1. Controlled quantum secure direct communication using a non-symmetric quantum channel with quantum superdense coding

    International Nuclear Information System (INIS)

    Xia, Yan; Song, He-Shan

    2007-01-01

    We present a controlled quantum secure direct communication protocol that uses a 2-dimensional Greenberger-Horne-Zeilinger (GHZ) entangled state and a 3-dimensional Bell-basis state and employs the high-dimensional quantum superdense coding, local collective unitary operations and entanglement swapping. The proposed protocol is secure and of high source capacity. It can effectively protect the communication against a destroying-travel-qubit-type attack. With this protocol, the information transmission is greatly increased. This protocol can also be modified, so that it can be used in a multi-party control system

  2. Experimental demonstration of subcarrier multiplexed quantum key distribution system.

    Science.gov (United States)

    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.

  3. Accidental cloning of a single-photon qubit in two-channel continuous-variable quantum teleportation

    International Nuclear Information System (INIS)

    Ide, Toshiki; Hofmann, Holger F.

    2007-01-01

    The information encoded in the polarization of a single photon can be transferred to a remote location by two-channel continuous-variable quantum teleportation. However, the finite entanglement used in the teleportation causes random changes in photon number. If more than one photon appears in the output, the continuous-variable teleportation accidentally produces clones of the original input photon. In this paper, we derive the polarization statistics of the N-photon output components and show that they can be decomposed into an optimal cloning term and completely unpolarized noise. We find that the accidental cloning of the input photon is nearly optimal at experimentally feasible squeezing levels, indicating that the loss of polarization information is partially compensated by the availability of clones

  4. Application of quantum key distribution for mutual identification - experimental realization

    International Nuclear Information System (INIS)

    Dusek, M.; Haderka, O.; Hendrych, M.

    1998-01-01

    A secure quantum identification system combining a classical identification procedure and quantum key distribution is proposed. Each identification sequence is always used just once and new sequences are 're fuelled' from a shared secret key transferred over a quantum channel. The question of authentication of information sent over a public channel is discussed. An apparatus using two unbalanced Mach-Zehnder interferometers has been built, and quantum key distribution and 'quantum identification' have been successfully tested through a single-mode optical fibre at 830 nm, employing low intensity coherent states (below 0,1 photons per pulse). (author)

  5. Insecurity of petroleum supplies and external effect: the case of security storage

    International Nuclear Information System (INIS)

    Sanchez, B.

    1997-01-01

    The public intervention in the domain of security of petroleum supplies is in general justified in the literature by the existence of external effects linked with the phenomenon of insecurity of supplies. This work proposes to analyse in detail the validity of this justification and its implication in terms of energy policy recommendations. The components of the insecurity cost is analyzed in the first part. Two components are retained: the macro-economical effects of insecurity and the monopsony cost. The study of the macro-economical component of insecurity uses a disequilibrium economy-type approach. On the basis of a modeling of the macro-economical effects of insecurity on a conventionalized economy, a relation is evidenced between rupture probability and level of usefulness. This model is applied to 4 European Union countries and the effects of supplies insecurity is measured for each of them. For the monopsony component of supplies insecurity, the additional cost generated by insecurity in relation with the monopsony situation is analyzed. A numerical analysis illustrates this analysis. Then, the relevance of the monopsony concept in the description of the situation of petroleum consuming economies is questioned. The analysis of the US case leads to reject the existence of a petroleum monopsony made of the USA alone and to favour the definition of a monopsony made of the IEA member countries. Then, the analysis of the insecurity cost is made using the external cost notion. This study allows to settle the status of the macro-economical component: there effectively exists a macro-economical cost of insecurity but this cost cannot be considered as external. This result is interesting because many analyses justify the public intervention using the external cost property of the macro-economical effects. On the contrary, the monopsony component can be unambiguously identified as being at the origin of a pecuniary external cost. The insecurity of supplies can be

  6. Exposure to temporary employment and job insecurity: a longitudinal study of the health effects.

    Science.gov (United States)

    Virtanen, Pekka; Janlert, Urban; Hammarström, Anne

    2011-08-01

    This study analysed interactions between job insecurity and temporary employment and health. We tested the violation hypothesis (whether permanent employment increases the health risk associated with job insecurity) and the intensification hypothesis (whether temporary employment increases the health risk associated with job insecurity) in a longitudinal setting. Previous research on this topic is scarce and based on cross-sectional data. A population cohort (n=1071) was surveyed at age 30 and age 42. Exposure to temporary employment during this 12-year period was elicited with a job-time matrix and measured as the score of 6-month periods. Exposure to job insecurity was measured according to the perceived threat of unemployment. Health at follow-up was assessed as optimal versus suboptimal self-rated health, sleep quality and mental health. In addition to sociodemographics and baseline health, the analyses were adjusted for exposure to unemployment, non-employment and self-employment during the 12-year period. 26% of participants had been exposed to temporary employment. The effect of job insecurity on health was the same in the exposed and unexposed groups, that is the violation hypothesis was not supported. Non-significant interactions between the exposures and all health outcomes also indicated null findings regarding the intensification hypothesis. These findings suggest that perceived job insecurity can lead to adverse health effects in both permanent and temporary employees. Policies should aim to improve work-related well-being by reducing job insecurity. Efforts towards 'flexicurity' are important, but it is equally important to remember that a significant proportion of employees with a permanent contract experience job insecurity.

  7. Prioritization of the essentials in the spending patterns of Canadian households experiencing food insecurity.

    Science.gov (United States)

    Fafard St-Germain, Andrée-Anne; Tarasuk, Valerie

    2018-03-21

    Food insecurity is a potent determinant of health and indicator of material deprivation in many affluent countries. Food insecurity is associated with compromises in food and housing expenditures, but how it relates to other expenditures is unknown. The present study described households' resource allocation over a 12-month period by food insecurity status. Expenditure data from the 2010 Survey of Household Spending were aggregated into four categories (basic needs, other necessities, discretionary, investments/assets) and ten sub-categories (food, clothing, housing, transportation, household/personal care, health/education, leisure, miscellaneous, personal insurance/pension, durables/assets). A four-level food insecurity status was created using the adult-specific items of the Household Food Security Survey Module. Mean dollars spent and budget share by food insecurity status were estimated with generalized linear models adjusted first for household size and composition, and subsequently for after-tax income quartiles. Canada. Population-based sample of households from the ten provinces (n 9050). Food-secure households had higher mean total expenditures than marginally, moderately and severely food-insecure households (P-trend insecurity increased, households spent less on all categories and sub-categories, except transportation, but they allocated a larger budget share to basic needs and smaller shares to discretionary spending and investments/assets. The downward trends for dollars spent on basic needs and other necessities became non-significant after accounting for income, but the upward trend in the budget shares for basic needs persisted. The spending patterns of food-insecure households suggest that they prioritized essential needs above all else.

  8. Food Insecurity and Behavioral Characteristics for Academic Success in Young Adults Attending an Appalachian University.

    Science.gov (United States)

    Hagedorn, Rebecca L; Olfert, Melissa D

    2018-03-16

    In order to investigate the impact of food insecurity on college students in a highly health disparate region we (1) assessed the prevalence of food insecurity among young adults at a large, rural university in Appalachia, and (2) investigated the relationship between food insecurity and behavioral characteristics including academic performance, coping strategies, and money expenditure. A cross-sectional design was used to capture a representative sample of young adults attending a large, central Appalachian university in Fall 2016. The United States Department of Agriculture (USDA) Adult Food Security Survey was used to measure food insecurity. Independent variables include money expenditure (MES), coping strategies (CSS), academic performance (APS), and demographic, health, economic and culinary variables. Participant responses ( n = 692) showed one third (36.6%) of respondents were food-insecure. Students with higher scores for MES and CSS had significantly higher odds of being food-insecure (odds ratio (OR) = 2.07; 95% confidence interval (CI) 1.81 to 2.38 and OR = 1.20; 95% CI 1.16 to 1.23, respectively). The odds of high APS scores (OR = 0.79; 95% CI 0.73 to 0.86) were inversely related to food insecurity. Results of the logistic regression showed MES, CSS, health, and school year remained a significant predictor of food insecurity in college students. These findings suggest behavioral differences in terms of coping strategies, money expenditure, and academic progress among food-insecure students and can be used to identify and target at-risk students to promote student food security and well-being.

  9. Food Insecurity as a Risk Factor for Obesity in Low-Income Boushehrian Women

    Directory of Open Access Journals (Sweden)

    Masoumeh Mohammadpour Kaldeh

    2010-12-01

    Full Text Available Background: Food insecurity contributes to poor health and nutritional status such as higher prevalence of overweight and obesity and other mental and physical problems. This study was conducted to investigate the relationship between food insecurity and obesity in low-income women living in Bushehr. Methods: A cross sectional study was conducted among 300 Bushehrian women (19-49 years, non pregnant and non lactating. The women were interviewed for socio-economic, demographic, physical and household food security. The radimer-cornell food insecurity instrument and international physical activity questionnaire were used. For data analysis, logistic regression was conducted. Results: Overall, a majority of the households (86% experienced food insecurity. About more than half (55% of the women were obese. The mean body mass index of food insecure groups (30.43 ± 4.67 Kg/cm2 were significantly higher than food secure group (21.41 ± 1.61 Kg/cm2 (p<0.05. After adjusting for other variables using logistic regression, housewives (OR=3.99 and lower physical activity (OR=2.65 significantly increased as well as food security (OR= 0.04 significantly decreased the risk of obesity. Conclusion: The consumption of chip and high dense food and lower physical activity can be important reasons for overweight and obesity in food insecure women.

  10. Household Food Insecurity and Sleep Patterns Among Mexican Adults: Results from ENSANUT-2012.

    Science.gov (United States)

    Jordan, Monica L; Perez-Escamilla, Rafael; Desai, Mayur M; Shamah-Levy, Teresa

    2016-10-01

    To examine the independent association of household food insecurity with sleep duration and quality in a nationally representative survey of adults in Mexico. The Latin American and Caribbean Food Security Scale was used to categorize households as secure, mild (43.7 %), moderate (19.0 %), or severe (11.8 %). We assessed the association between household food insecurity and self-reported sleep duration and quality among 11,356 adults using weighted multinomial and binomial logistic regression. After adjusting for potential confounders, a significant association was found between severe household food insecurity and getting less than the recommended 7-8 h of sleep [adjusted odds ratio (AOR) =1.83, 95 % confidence interval (CI) =1.37-2.43]. Compared with food-secure households, odds of poor sleep quality increased with level of severity (AOR = 1.27, 95 % CI 1.04-1.56 for mild; AOR = 1.71, 95 % CI 1.36-2.14 for moderate; and AOR = 1.89, 95 % CI 1.45-2.45 for severe household food insecurity). Household food insecurity is associated with inadequate sleep duration and poor sleep quality among Mexican adults. This study underscores the adverse effects of household food insecurity on the well-being of vulnerable populations.

  11. A qualitative pilot study of food insecurity among Maasai women in ...

    African Journals Online (AJOL)

    The purpose of this study was to pilot a qualitative method to understand food insecurity based on the lived experience of women of the Maasai population in the Ngorongoro Conservation Area of Tanzania. Methods: Short semi-structured qualitative interviews with 4 Maasai women. Results: Food insecurity was present in ...

  12. Insurgency and Insecurity: Bane of Global Literacy Development

    Directory of Open Access Journals (Sweden)

    T.A. Adebisi

    2016-08-01

    Full Text Available Year-in, year-out, decades after decades and centuries upon centuries, there has continued to be recurrent calls for eradication of illiteracy globally. The experience over the years has, however, shown that no target fixed for eradication of illiteracy has ever been met. There have always been renewed calls for eradication of illiteracy at the expiration of countless number of failed decades set as targets for Education for All without meeting the target. Parts of the major causes of unrealized and unfulfilled dreams of education for all have been challenges posed by insurgency and insecurity bedeviling the entire world. The outbreak of insurgencies culminating in high level of insecurity has hampered children and adults access to all forms of education be it formal, non-formal, or adult education. Due to insurgencies, school have been physically touched, destroyed, burnt and broken down. The systems of education in many countries globally have been adversely affected. Communities scattered and destabilized, people displaced and killed. This paper therefore premised on the existing literature on insurgency and insecurity issues considers them as bane of global literacy development. The paper explores debilitating effects of insurgency and insecurity on literacy development in Africa in particular and the entire world in general. It highlights instances of insurgency in various dimensions world over, the toll it has on security and education and consequently offers suggestions on the way forward with a view to advancing the course of development that the world so much desires especially in terms of education.

  13. Race Differences in Diet Quality of Urban Food-Insecure Blacks and Whites Reveals Resiliency in Blacks.

    Science.gov (United States)

    Allen, Allyssa J; Kuczmarski, Marie Fanelli; Evans, Michele K; Zonderman, Alan B; Waldstein, Shari R

    2016-12-01

    Evidence from epidemiological studies shows a link between food insecurity and diet intake or quality. However, the moderating effect of race in this relation has not yet been studied. Food insecurity (USDA Food Security Module) and diet quality (Healthy Eating Index-2010; HEI) were measured in 1741 participants from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study. Data were collected from 2004 to 2009 and analyzed in 2014. Multivariable regression assessed the interaction of race and food insecurity on HEI scores, adjusting for age, sex, poverty status, single parent status, drug, alcohol and cigarette use, and comorbid diseases. The interaction of food insecurity and race was significantly associated with diet quality (p = 0.001). In the absence of food insecurity, HEI scores were similar across race. However, with each food insecurity item endorsed, HEI scores were substantially lower for Whites compared to Blacks. An ad hoc analysis revealed that Blacks were more likely than Whites to participate in SNAP (p race stratified analyses revealed that Blacks participating in SNAP showed diminished associations of food insecurity with diet quality. Study findings provide the first evidence that the influence of food insecurity on diet quality may be potentiated for Whites, but not Blacks. Additionally, results show that Blacks are more likely to participate in SNAP and show attendant buffering of the effects of food insecurity on diet quality. These findings may have important implications for understanding how food insecurity affects diet quality differentially by race.

  14. The relationship between job insecurity and well-being among Peruvian workers

    Directory of Open Access Journals (Sweden)

    Alarco, Barbara

    2012-12-01

    Full Text Available The present study’s aims are twofold: to introduce job insecurity research in Peru, and to investigate the relationship between job insecurity and a broad range of well-being indicators, including optimal and impaired, and general and work-related well-being. We hypothesise that job insecurity (1 relates negatively to work-related optimal well-being (i.e., job satisfaction, career satisfaction and work engagement and positively to work-related impaired well-being (i.e., burnout, and (2 negatively to general optimal well-being (i.e., life satisfaction and positively to general impaired well-being (i.e., psychological distress. In 2008, we administered questionnaires to employees from eight organizations based in Metropolitan Lima, yielding a convenience sample of 651 respondents. We used hierarchical regression analyses and controlled for organizations, age, gender, job-related (e.g., occupational position and family-related (e.g., financial contribution to the household variables. Results supported our hypotheses. We conclude that job insecurity shows a strong association with impaired well-being. A particular strength of this study is that it is situated in Lima, Peru, and in a context of economic growth. It also contributes to understand the association of job insecurity with work-related well-being by including rarely studied variables such as career satisfaction, work engagement and burnout.

  15. Food Insecurity in Nigeria: Way Forward

    African Journals Online (AJOL)

    Toshiba

    mankind and his economic activities including food production. Food is different from ... insecurity for the past four decades as a result of neglect in food production when oil .... This creates no room for stability and progress in food production.

  16. Device calibration impacts security of quantum key distribution.

    Science.gov (United States)

    Jain, Nitin; Wittmann, Christoffer; Lydersen, Lars; Wiechers, Carlos; Elser, Dominique; Marquardt, Christoph; Makarov, Vadim; Leuchs, Gerd

    2011-09-09

    Characterizing the physical channel and calibrating the cryptosystem hardware are prerequisites for establishing a quantum channel for quantum key distribution (QKD). Moreover, an inappropriately implemented calibration routine can open a fatal security loophole. We propose and experimentally demonstrate a method to induce a large temporal detector efficiency mismatch in a commercial QKD system by deceiving a channel length calibration routine. We then devise an optimal and realistic strategy using faked states to break the security of the cryptosystem. A fix for this loophole is also suggested.

  17. Lossless quantum data compression and variable-length coding

    International Nuclear Information System (INIS)

    Bostroem, Kim; Felbinger, Timo

    2002-01-01

    In order to compress quantum messages without loss of information it is necessary to allow the length of the encoded messages to vary. We develop a general framework for variable-length quantum messages in close analogy to the classical case and show that lossless compression is only possible if the message to be compressed is known to the sender. The lossless compression of an ensemble of messages is bounded from below by its von-Neumann entropy. We show that it is possible to reduce the number of qbits passing through a quantum channel even below the von Neumann entropy by adding a classical side channel. We give an explicit communication protocol that realizes lossless and instantaneous quantum data compression and apply it to a simple example. This protocol can be used for both online quantum communication and storage of quantum data

  18. Food Insecurity in Singapore: The Communicative (Dis)Value of the Lived Experiences of the Poor.

    Science.gov (United States)

    Tan, Naomi; Kaur-Gill, Satveer; Dutta, Mohan J; Venkataraman, Nina

    2017-08-01

    Food insecurity is a form of health disparity that results in adverse health outcomes, particularly among disenfranchised and vulnerable populations. Using the culture-centered approach, this article engages with issues of food insecurity, health, and poverty among the low-income community in Singapore. Through 30 in-depth interviews, the narratives of the food insecure are privileged in articulating their lived experiences of food insecurity and in co-constructing meanings of health informed by their sociocultural context, in a space that typically renders them invisible. Arguing that poverty is communicatively sustained through the erasure of subaltern voices from mainstream discourses and policy platforms, we ask the research question: What are the meanings of food insecurity in the everyday experiences of health among the poor in Singapore? Our findings demonstrate that the meanings of health among the food insecure are constituted in culture and materiality, structurally constrained, and ultimately complexify their negotiations of health and health decision making.

  19. Three-player quantum Kolkata restaurant problem under decoherence

    Science.gov (United States)

    Ramzan, M.

    2013-01-01

    Effect of quantum decoherence in a three-player quantum Kolkata restaurant problem is investigated using tripartite entangled qutrit states. Different qutrit channels such as, amplitude damping, depolarizing, phase damping, trit-phase flip and phase flip channels are considered to analyze the behaviour of players payoffs. It is seen that Alice's payoff is heavily influenced by the amplitude damping channel as compared to the depolarizing and flipping channels. However, for higher level of decoherence, Alice's payoff is strongly affected by depolarizing noise. Whereas the behaviour of phase damping channel is symmetrical around 50% decoherence. It is also seen that for maximum decoherence ( p = 1), the influence of amplitude damping channel dominates over depolarizing and flipping channels. Whereas, phase damping channel has no effect on the Alice's payoff. Therefore, the problem becomes noiseless at maximum decoherence in case of phase damping channel. Furthermore, the Nash equilibrium of the problem does not change under decoherence.

  20. Quantum theory of scattering of channeled electrons and positrons in a crystal

    International Nuclear Information System (INIS)

    Bazylev, V.A.; Goloviznin, V.V.

    1982-01-01

    The quantum theory of elastic scattering of electrons and positrons on plane or axial channeling in a thin crystal is developed. The role of coherent (without phonon excitation) and incoherent scattering by atoms of the plane (chain) is investigated. It is shown that incoherent scattering which leads to dechanneling cannot be reduced to scattering by an isolated atom. Allowance for ordered arrangement of the atoms in the plane (chain) of the crystal leads to suppression of the motion levels. It is also shown that on movement of a particle along the plane in directions strongly differing from those of the principal axes, the scattering is incoherent and is determined by thermal vibrations of the nuclei. As the direction of the particle momentum approaches those of the principal axes, the role of coherent scattering without recoil by the crystal lattice nuclei increases and may become dicisive. The probability of large- angle scattering increases relatively in this case. Under certain conditions coherent scattering may become resonant [ru