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Total Synthesis of (±)-Goniomitine via Radical Translocation
The aspidosperma alkaloid goniomitine was synthesized in six steps from 2-ethyl-δ-valerolactam. The convergent strategy features an Ullman coupling to assemble the required carbon atoms. A complexity-generating radical translocation reaction was used to build the indole architecture
Locally Chain-Parsable Languages
If a context-free language enjoys the local parsability property then, no matter how the source string is segmented, each segment can be parsed in- dependently, and an efficient parallel parsing algorithm becomes possible. The new class of locally chain-parsable languages (LCPL), included in deterministic context-free languages, is here defined by means of the chain-driven automa- ton and characterized by decidable properties of grammar derivations. Such au- tomaton decides to reduce or not a factor in a way purely driven by the terminal characters, thus extending the well-known concept of Input-Driven (ID) (visibly) pushdown machines. LCPL extend and improve the practically relevant operator- precedence languages (Floyd), which are known to strictly include the ID lan- guages, and for which a parallel-parser generator exists. Consistently with the classical results for ID, chain-compatible LCPL are closed under reversal and Boolean operations, and language inclusion is decidable
Flipping quantum coins
Coin flipping is a cryptographic primitive in which two distrustful parties
wish to generate a random bit in order to choose between two alternatives. This
task is impossible to realize when it relies solely on the asynchronous
exchange of classical bits: one dishonest player has complete control over the
final outcome. It is only when coin flipping is supplemented with quantum
communication that this problem can be alleviated, although partial bias
remains. Unfortunately, practical systems are subject to loss of quantum data,
which restores complete or nearly complete bias in previous protocols. We
report herein on the first implementation of a quantum coin-flipping protocol
that is impervious to loss. Moreover, in the presence of unavoidable
experimental noise, we propose to use this protocol sequentially to implement
many coin flips, which guarantees that a cheater unwillingly reveals
asymptotically, through an increased error rate, how many outcomes have been
fixed. Hence, we demonstrate for the first time the possibility of flipping
coins in a realistic setting. Flipping quantum coins thereby joins quantum key
distribution as one of the few currently practical applications of quantum
communication. We anticipate our findings to be useful for various
cryptographic protocols and other applications, such as an online casino, in
which a possibly unlimited number of coin flips has to be performed and where
each player is free to decide at any time whether to continue playing or not.Comment: 17 pages, 3 figure
Are multiple-trial experiments appropriate for eyewitness identification studies? Accuracy, choosing, and confidence across trials
Eyewitness identification experiments typically involve a single trial: a participant views an event and subsequently makes a lineup decision. Compared to this single-trial paradigm, multiple-trial designs are more efficient but significantly reduce ecological validity and may affect the strategies participants use to make lineup decisions. We examined the effects of a number of forensically-relevant variables (i.e., memory strength, type of disguise, degree of disguise, and lineup type) on eyewitness accuracy, choosing, and confidence across 12 target-present and 12 target-absent lineup trials (N = 349; 8,376 lineup decisions). Rates of correct rejections and choosing (across both target-present and -absent lineups) did not vary across the 24 trials as reflected by main effects or interactions with trial number. Trial number had a significant but trivial quadratic effect on correct identifications (OR = 0.99) and interacted significantly, but again trivially, with disguise type (OR = 1.00). Trial number did not significantly influence participants' confidence in correct identifications, confidence in correct rejections, or confidence in target-absent selections. Thus, multiple-trial designs appear to have minimal effects on eyewitness accuracy, choosing, and confidence. Researchers should consider using multiple-trial designs for conducting eyewitness identification experiments.div_PaS49pub4633pu
Implementation of the LDA+U method using the full potential linearized augmented plane wave basis
We provide a straightforward and efficient procedure to combine LDA+U total
energy functional with the full potential linearized augmented plane wave
method. A detailed derivation of the LDA+U Kohn-Sham type equations is
presented for the augmented plane wave basis set, and a simple
``second-variation'' based procedure for self-consistent LDA+U calculations is
given. The method is applied to calculate electronic structure and magnetic
properties of NiO and Gd. The magnetic moments and band eigenvalues obtained
are in very good quantitative agreement with previous full potential LMTO
calculations. We point out that LDA+U reduces the total d charge on Ni by 0.1
in NiO
Analyzing ligation mixtures using a PCR based method
We have developed a simple and effective method (Lig-PCR) for monitoring ligation reactions using PCR and primers that are common to many cloning vectors. Ligation mixtures can directly be used as templates and the results can be analyzed by conventional gel electrophoresis. The PCR products are representative of the recombinant molecules created during ligation and the corresponding transformants. Orientation of inserts can also be determined using an internal primer. The usefulness of this method has been demonstrated using ligation mixtures of two cDNA’s derived from the salivary glands of Aedes aegypti mosquitoes. The method described here is sensitive and easy to perform compared to currently available methods
The Road to Quantum Computational Supremacy
We present an idiosyncratic view of the race for quantum computational
supremacy. Google's approach and IBM challenge are examined. An unexpected
side-effect of the race is the significant progress in designing fast classical
algorithms. Quantum supremacy, if achieved, won't make classical computing
obsolete.Comment: 15 pages, 1 figur
Compressed Membership for NFA (DFA) with Compressed Labels is in NP (P)
In this paper, a compressed membership problem for finite automata, both
deterministic and non-deterministic, with compressed transition labels is
studied. The compression is represented by straight-line programs (SLPs), i.e.
context-free grammars generating exactly one string. A novel technique of
dealing with SLPs is introduced: the SLPs are recompressed, so that substrings
of the input text are encoded in SLPs labelling the transitions of the NFA
(DFA) in the same way, as in the SLP representing the input text. To this end,
the SLPs are locally decompressed and then recompressed in a uniform way.
Furthermore, such recompression induces only small changes in the automaton, in
particular, the size of the automaton remains polynomial.
Using this technique it is shown that the compressed membership for NFA with
compressed labels is in NP, thus confirming the conjecture of Plandowski and
Rytter and extending the partial result of Lohrey and Mathissen; as it is
already known, that this problem is NP-hard, we settle its exact computational
complexity. Moreover, the same technique applied to the compressed membership
for DFA with compressed labels yields that this problem is in P; for this
problem, only trivial upper-bound PSPACE was known
Evaluating lineup fairness: Variations across methods and measures
Triers of fact sometimes consider lineup fairness when determining the suggestiveness of an identification procedure. Likewise, researchers often consider lineup fairness when comparing results across studies. Despite their importance, lineup fairness measures have received scant empirical attention and researchers inconsistently conduct and report mock-witness tasks and lineup fairness measures. We conducted a large-scale, online experiment (N = 1010) to examine how lineup fairness measures varied with mock-witness task methodologies as well as to explore the validity and reliability of the measures. In comparison to descriptions compiled from multiple witnesses, when individual descriptions were presented in the mock-witness task, lineup fairness measures indicated a higher number of plausible lineup members but more bias towards the suspect. Target-absent lineups were consistently estimated to be fairer than target-present lineups-which is problematic because it suggests that lineups containing innocent suspects are less likely to be challenged in court than lineups containing guilty suspects. Correlations within lineup size measures and within some lineup bias measures indicated convergent validity and the correlations across the lineup size and lineup bias measures demonstrated discriminant validity. The reliability of lineup fairness measures across different descriptions was low and reliability across different sets of mock witnesses was moderate to high, depending on the measure. Researchers reporting lineup fairness measures should specify the type of description presented, the amount of detail in the description, and whether the mock witnesses viewed target-present and/or -absent lineups.div_PaS41pub4364pub
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