6,687 research outputs found
On the "Security analysis and improvements of arbitrated quantum signature schemes"
Recently, Zou et al. [Phys. Rev. A 82, 042325 (2010)] pointed out that two
arbitrated quantum signature (AQS) schemes are not secure, because an
arbitrator cannot arbitrate the dispute between two users when a receiver
repudiates the integrity of a signature. By using a public board, they try to
propose two AQS schemes to solve the problem. This work shows that the same
security problem may exist in their schemes and also a malicious party can
reveal the other party's secret key without being detected by using the
Trojan-horse attacks. Accordingly, two basic properties of a quantum signature,
i.e. unforgeability and undeniability, may not be satisfied in their scheme
Needs Assessment for cancer patients and their families
BACKGROUND: The assessment of needs for cancer care is a critical step in providing high quality care and achieving cancer patients' and families' satisfaction. Instruments can be used to assess needs and guide cancer care planning. This study discusses the importance of the needs assessment, relationships between needs, satisfaction and quality of life; and reviews the assessment instruments of needs experienced by cancer patients and their families. METHODS: A systematic search was conducted in MEDLINE and CANCERLIT data bases. Instruments were evaluated based on their conceptual and measurement models as well as their demonstrated reliability and validity. The authors also sought information pertaining to instruments' burden of administration and responsiveness. Measures compromised by a lack of published psychometric description were not included. RESULTS: This search identified 17 patient needs assessment instruments and seven family needs assessment instruments. The development and psychometric proprieties of most of these instruments were well documented. However, data on their responsiveness and burden of administration were scarce. CONCLUSIONS: Each selected instrument meets some but not all of our criteria for validity, reliability, responsiveness and burden. It is questionable whether any instrument can be developed meeting all the requirements. However, there is still a need to continue researching and developing needs assessment instruments leading to effective intervention and improving quality of cancer care
Quantum refrigerator driven by current noise
We proposed a scheme to implement a self-contained quantum refrigerator
system composed of three rf-SQUID qubits, or rather, flux-biased phase qubits.
The three qubits play the roles of the target, the refrigerator and the heat
engine respectively. We provide different effective temperatures for the three
qubits, by imposing external current noises of different strengths. The
differences of effective temperatures give rise to the flow of free energy and
that drives the refrigerator system to cool down the target. We also show that
the efficiency of the system approaches the Carnot efficiency.Comment: 5 pages, 1 figur
Decoy State Quantum Key Distribution With Modified Coherent State
To beat PNS attack, decoy state quantum key distribution (QKD) based on
coherent state has been studied widely. We present a decoy state QKD protocol
with modified coherent state (MCS). By destruction quantum interference, MCS
with fewer multi-photon events can be get, which may improve key bit rate and
security distance of QKD. Through numerical simulation, we show about 2-dB
increment on security distance for BB84 protocol.Comment: 4 pages, 4 figure
Prostaglandin E2 promotes intestinal repair through an adaptive cellular response of the epithelium
Adaptive cellular responses are often required during wound repair. Following disruption of the intestinal epithelium, wound‐associated epithelial (WAE) cells form the initial barrier over the wound. Our goal was to determine the critical factor that promotes WAE cell differentiation. Using an adaptation of our in vitro primary epithelial cell culture system, we found that prostaglandin E2 (PGE (2)) signaling through one of its receptors, Ptger4, was sufficient to drive a differentiation state morphologically and transcriptionally similar to in vivo WAE cells. WAE cell differentiation was a permanent state and dominant over enterocyte differentiation in plasticity experiments. WAE cell differentiation was triggered by nuclear β‐catenin signaling independent of canonical Wnt signaling. Creation of WAE cells via the PGE (2)‐Ptger4 pathway was required in vivo, as mice with loss of Ptger4 in the intestinal epithelium did not produce WAE cells and exhibited impaired wound repair. Our results demonstrate a mechanism by which WAE cells are formed by PGE (2) and suggest a process of adaptive cellular reprogramming of the intestinal epithelium that occurs to ensure proper repair to injury
On the Conductance Sum Rule for the Hierarchical Edge States of the Fractional Quantum Hall Effect
The conductance sum rule for the hierarchical edge channel currents of a
Fractional Quantum Hall Effect state is derived analytically within the
Haldane-Halperin hierarchy scheme. We provide also an intuitive interpretation
for the hierarchical drift velocities of the edge excitations.Comment: 11 pages, no figure, Revtex 3.0, IC/93/329, ASITP-93-5
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