2,768 research outputs found
Hippocampal Infusion of Zeta Inhibitory Peptide Impairs Recent, but Not Remote, Recognition Memory in Rats.
Spatial memory in rodents can be erased following the infusion of zeta inhibitory peptide (ZIP) into the dorsal hippocampus via indwelling guide cannulas. It is believed that ZIP impairs spatial memory by reversing established late-phase long-term potentiation (LTP). However, it is unclear whether other forms of hippocampus-dependent memory, such as recognition memory, are also supported by hippocampal LTP. In the current study, we tested recognition memory in rats following hippocampal ZIP infusion. In order to combat the limited targeting of infusions via cannula, we implemented a stereotaxic approach for infusing ZIP throughout the dorsal, intermediate, and ventral hippocampus. Rats infused with ZIP 3-7 days after training on the novel object recognition task exhibited impaired object recognition memory compared to control rats (those infused with aCSF). In contrast, rats infused with ZIP 1 month after training performed similar to control rats. The ability to form new memories after ZIP infusions remained intact. We suggest that enhanced recognition memory for recent events is supported by hippocampal LTP, which can be reversed by hippocampal ZIP infusion
Lunar navigation study, volume 2 Final report, Jan. - Dec. 1966
Performance data utilization in mission phase, lunar exploration phase, and navigational phase of lunar roving vehicle mission
Qudit versions of the qubit "pi-over-eight" gate
When visualised as an operation on the Bloch sphere, the qubit
"pi-over-eight" gate corresponds to one-eighth of a complete rotation about the
vertical axis. This simple gate often plays an important role in quantum
information theory, typically in situations for which Pauli and Clifford gates
are insufficient. Most notably, when it supplements the set of Clifford gates
then universal quantum computation can be achieved. The "pi-over-eight" gate is
the simplest example of an operation from the third level of the Clifford
hierarchy (i.e., it maps Pauli operations to Clifford operations under
conjugation). Here we derive explicit expressions for all qudit (d-level, where
d is prime) versions of this gate and analyze the resulting group structure
that is generated by these diagonal gates. This group structure differs
depending on whether the dimensionality of the qudit is two, three or greater
than three. We then discuss the geometrical relationship of these gates (and
associated states) with respect to Clifford gates and stabilizer states. We
present evidence that these gates are maximally robust to depolarizing and
phase damping noise, in complete analogy with the qubit case. Motivated by this
and other similarities we conjecture that these gates could be useful for the
task of qudit magic-state distillation and, by extension, fault-tolerant
quantum computing. Very recent, independent work by Campbell, Anwar and Browne
confirms the correctness of this intuition, and we build upon their work to
characterize noise regimes for which noisy implementations of these gates can
(or provably cannot) supplement Clifford gates to enable universal quantum
computation.Comment: Version 2 changed to reflect improved distillation routines in
arXiv:1205.3104v2. Minor typos fixed. 12 Pages,2 Figures,3 Table
Percolative shunting on electrified surface
The surface discharge of electrified dielectrics at high humidity is
considered. The percolative nature of charge transport in electrets is
established. Particular attention is given to the phenomena of adsorption and
nucleation of electrically conducting phase in the cause of percolation cluster
growth on electrified surface. The critical index of the correlation lenght for
percolation cluster is found, and its value is in good agreement with the known
theoretical estimations.Comment: 4 pages with 1 figure, revtex, published in Tech. Phys. Lett. 25
(1999) 877-879 with one additional figur
QMA-hardness of Consistency of Local Density Matrices with Applications to Quantum Zero-Knowledge
We provide several advances to the understanding of the class of Quantum
Merlin-Arthur proof systems (QMA), the quantum analogue of NP. Our central
contribution is proving a longstanding conjecture that the Consistency of Local
Density Matrices (CLDM) problem is QMA-hard under Karp reductions. The input of
CLDM consists of local reduced density matrices on sets of at most k qubits,
and the problem asks if there is an n-qubit global quantum state that is
consistent with all of the k-qubit local density matrices. The containment of
this problem in QMA and the QMA-hardness under Turing reductions were proved by
Liu [APPROX-RANDOM 2006]. Liu also conjectured that CLDM is QMA-hard under Karp
reductions, which is desirable for applications, and we finally prove this
conjecture. We establish this result using the techniques of simulatable codes
of Grilo, Slofstra, and Yuen [FOCS 2019], simplifying their proofs and
tailoring them to the context of QMA.
In order to develop applications of CLDM, we propose a framework that we call
locally simulatable proofs for QMA: this provides QMA proofs that can be
efficiently verified by probing only k qubits and, furthermore, the reduced
density matrix of any k-qubit subsystem of an accepting witness can be computed
in polynomial time, independently of the witness. Within this framework, we
show advances in quantum zero-knowledge. We show the first commit-and-open
computational zero-knowledge proof system for all of QMA, as a quantum analogue
of a "sigma" protocol. We then define a Proof of Quantum Knowledge, which
guarantees that a prover is effectively in possession of a quantum witness in
an interactive proof, and show that our zero-knowledge proof system satisfies
this definition. Finally, we show that our proof system can be used to
establish that QMA has a quantum non-interactive zero-knowledge proof system in
the secret parameter setting.Comment: Title changed to highlight the QMA-hardness proof of CLDM.
Improvement on the presentation of the paper (including self-contained proofs
of results needed from Grilo, Slofstra, and Yuen'19). The extended abstract
of this paper appears in the proceedings of FOCS'202
Equivalence of operator-splitting schemes for the integration of the Langevin equation
We investigate the equivalence of different operator-splitting schemes for
the integration of the Langevin equation. We consider a specific problem, so
called the directed percolation process, which can be extended to a wider class
of problems. We first give a compact mathematical description of the
operator-splitting method and introduce two typical splitting schemes that will
be useful in numerical studies. We show that the two schemes are essentially
equivalent through the map that turns out to be an automorphism. An associated
equivalent class of operator-splitting integrations is also defined by
generalizing the specified equivalence.Comment: 4 page
Climate change policy networks : Why and how to compare them across countries
Why do some countries enact more ambitious climate change policies than others? Macro level economic and political structures, such as the economic weight of fossil fuel industries, play an important role in shaping these policies. So do the national science community and the national culture of science. But the process by which such macro-structural factors translate into political power and national climate change policies can be analyzed through focussing on meso level policy networks. The Comparing Climate Change Policy Networks (COMPON) research project has studied climate change policy networks in twenty countries since 2007. Along with some findings, this paper presents some methodological challenges faced and the solutions developed in the course of the project. After a presentation of the project, we first outline some practical challenges related to conducting cross-national network surveys and solutions to overcome them, and present the solutions adopted during the project. We then turn to challenges related to causal explanation of the national policy differences, and propose Qualitative Comparative Analysis as one solution for combining different levels of analysis (macro and meso) and different data types (quantitative, network and qualitative).Peer reviewe
Optimizing prediction of binge eating episodes : a comparison approach to test alternative conceptualizations of the affect regulation model
Background : Although a wealth of studies have tested the link between negative mood states and likelihood of a subsequent binge eating episode, the assumption that this relationship follows a typical linear dose–response pattern (i.e., that risk of a binge episode increases in proportion to level of negative mood) has not been challenged. The present study demonstrates the applicability of an alternative, non-linear conceptualization of this relationship, in which the strength of association between negative mood and probability of a binge episode increases above a threshold value for the mood variable relative to the slope below this threshold value (threshold dose response model). Methods : A sample of 93 women aged 18 to 40 completed an online survey at random intervals seven times per day for a period of one week. Participants self-reported their current mood state and whether they had recently engaged in an eating episode symptomatic of a binge. Results : As hypothesized, the threshold approach was a better predictor than the linear dose–response modeling of likelihood of a binge episode. The superiority of the threshold approach was found even at low levels of negative mood (3 out of 10, with higher scores reflecting more negative mood). Additionally, severity of negative mood beyond this threshold value appears to be useful for predicting time to onset of a binge episode. Conclusions : Present findings suggest that simple dose–response formulations for the association between negative mood and onset of binge episodes miss vital aspects of this relationship. Most notably, the impact of mood on binge eating appears to depend on whether a threshold value of negative mood has been breached, and elevation in mood beyond this point may be useful for clinicians and researchers to identify time to onset. <br /
Delegating Quantum Computation in the Quantum Random Oracle Model
A delegation scheme allows a computationally weak client to use a server's
resources to help it evaluate a complex circuit without leaking any information
about the input (other than its length) to the server. In this paper, we
consider delegation schemes for quantum circuits, where we try to minimize the
quantum operations needed by the client. We construct a new scheme for
delegating a large circuit family, which we call "C+P circuits". "C+P" circuits
are the circuits composed of Toffoli gates and diagonal gates. Our scheme is
non-interactive, requires very little quantum computation from the client
(proportional to input length but independent of the circuit size), and can be
proved secure in the quantum random oracle model, without relying on additional
assumptions, such as the existence of fully homomorphic encryption. In practice
the random oracle can be replaced by an appropriate hash function or block
cipher, for example, SHA-3, AES.
This protocol allows a client to delegate the most expensive part of some
quantum algorithms, for example, Shor's algorithm. The previous protocols that
are powerful enough to delegate Shor's algorithm require either many rounds of
interactions or the existence of FHE. The protocol requires asymptotically
fewer quantum gates on the client side compared to running Shor's algorithm
locally.
To hide the inputs, our scheme uses an encoding that maps one input qubit to
multiple qubits. We then provide a novel generalization of classical garbled
circuits ("reversible garbled circuits") to allow the computation of Toffoli
circuits on this encoding. We also give a technique that can support the
computation of phase gates on this encoding.
To prove the security of this protocol, we study key dependent message(KDM)
security in the quantum random oracle model. KDM security was not previously
studied in quantum settings.Comment: 41 pages, 1 figures. Update to be consistent with the proceeding
versio
Lunar navigation study, sections 1 through 7 Final report, Jun. 1964 - May 1965
Lunar navigation analysis using passive nongyro, inertial navigation, and radio frequency technolog
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