461 research outputs found
Universal quantum Controlled-NOT gate
An investigation of an optimal universal unitary Controlled-NOT gate that
performs a specific operation on two unknown states of qubits taken from a
great circle of the Bloch sphere is presented. The deep analogy between the
optimal universal C-NOT gate and the `equatorial' quantum cloning machine (QCM)
is shown. In addition, possible applications of the universal C-NOT gate are
briefly discussed.Comment: 18 reference
Probabilistic Quantum Logic Operations Using Polarizing Beam Splitters
It has previously been shown that probabilistic quantum logic operations can
be performed using linear optical elements, additional photons (ancilla), and
post-selection based on the output of single-photon detectors. Here we describe
the operation of several quantum logic operations of an elementary nature,
including a quantum parity check and a quantum encoder, and we show how they
can be combined to implement a controlled-NOT (CNOT) gate. All of these gates
can be constructed using polarizing beam splitters that completely transmit one
state of polarization and totally reflect the orthogonal state of polarization,
which allows a simple explanation of each operation. We also describe a
polarizing beam splitter implementation of a CNOT gate that is closely
analogous to the quantum teleportation technique previously suggested by
Gottesman and Chuang [Nature 402, p.390 (1999)]. Finally, our approach has the
interesting feature that it makes practical use of a quantum-eraser technique.Comment: 9 pages, RevTex; Submitted to Phys. Rev. A; additional references
inlcude
Single Photons on Pseudo-Demand from Stored Parametric Down-Conversion
We describe the results of a parametric down-conversion experiment in which
the detection of one photon of a pair causes the other photon to be switched
into a storage loop. The stored photon can then be switched out of the loop at
a later time chosen by the user, providing a single photon for potential use in
a variety of quantum information processing applications. Although the stored
single photon is only available at periodic time intervals, those times can be
chosen to match the cycle time of a quantum computer by using pulsed
down-conversion. The potential use of the storage loop as a photonic quantum
memory device is also discussed.Comment: 8 pages, 7 Figs., RevTe
Quantum computing with mixed states
We discuss a model for quantum computing with initially mixed states.
Although such a computer is known to be less powerful than a quantum computer
operating with pure (entangled) states, it may efficiently solve some problems
for which no efficient classical algorithms are known. We suggest a new
implementation of quantum computation with initially mixed states in which an
algorithm realization is achieved by means of optimal basis independent
transformations of qubits.Comment: 2 figures, 52 reference
Clinical outcomes of patients with complicated post-operative course after gastrectomy for cancer: a GIRCG study using the GASTRODATA registry
Gastrectomy for gastric cancer is still performed in Western countries with high morbidity and mortality. Post-operative complications are frequent, and effective diagnosis and treatment of complications is crucial to lower the mortality rates. In 2015, a project was launched by the EGCA with the aim of building an agreement on list and definitions of post-operative complications specific for gastrectomy. In 2018, the platform www.gastrodata.org was launched for collecting cases by utilizing this new complication list. In the present paper, the Italian Research Group for Gastric Cancer endorsed a collection of complicated cases in the period 2015–2019, with the aim of investigating the clinical pictures, diagnostic modalities, and treatment approaches, as well as outcome measures of patients experiencing almost one post-operative complication. Fifteen centers across Italy provided 386 cases with a total of 538 complications (mean 1.4 complication/patient). The most frequent complications were non-surgical infections (gastrointestinal, pulmonary, and urinary) and anastomotic leaks, accounting for 29.2% and 17.3% of complicated patients, with a median Clavien–Dindo score of II and IIIB, respectively. Overall mortality of this series was 12.4%, while mortality of patients with anastomotic leak was 25.4%. The clinical presentation with systemic septic signs, the timing of diagnosis, and the hospital volume were the most relevant factors influencing outcome
Changes in reflectin protein phosphorylation are associated with dynamic iridescence in squid
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of The Royal Society for personal use, not for redistribution. The definitive version was published in Journal of The Royal Society Interface 6 (2010): 549-560, doi:10.1098/rsif.2009.0299.Many cephalopods exhibit remarkable dermal iridescence, a component of their complex,
dynamic camouflage and communication. In the species Euprymna scolopes, the light-organ iridescence
is static and is due to reflectin protein-based platelets assembled into lamellar thin-film
reflectors called iridosomes, contained within iridescent cells called iridocytes. Squid in the
family Loliginidae appear to be unique in that the dermis possesses a dynamic iridescent component,
with reflective, colored structures that are assembled and disassembled under the control of
the muscarinic cholinergic system and the associated neurotransmitter acetylcholine (Mathger et
al. 2004). Here we present the sequences and characterization of three new members of the reflectin
family associated with the dynamically changeable iridescence in Loligo and not found in
static Euprymna iridophores. In addition, we show that application of genistein, a protein tyrosine
kinase inhibitor, suppresses acetylcholine- and calcium-induced iridescence in Loligo. We
further demonstrate that two of these novel reflectins are extensively phosphorylated in concert
with the activation of iridescence by exogenous acetylcholine. This phosphorylation and the correlated
iridescence can be blocked with genistein. Our results suggest that tyrosine phosphorylation
of reflectin proteins is involved in the regulation of dynamic iridescence in Loligo.We gratefully acknowledge support from Anteon contract F33615-03-D-5408 to the Marine
Biological Laboratory, Woods Hole, MA and grant # W911NF-06-1-0285 from the Army
Research Office to D.E.M
TOpic: rare and special cases, the real "Strange cases"
Introduction: The bladder hernia represents approximately 1-3% of
all inguinal hernias, where patients aged more than 50 years have a
higher incidence (10%). Many factors contribute to the development of a bladder hernia,
including the presence of a urinary outlet obstruction causing chronic
bladder distention, the loss of bladder tone, pericystitis, the perivesical
bladder fat protrusion and the obesity
Utilizing Spatial Demographic and Life History Variation to Optimize Sustainable Yield of a Temperate Sex-Changing Fish
Fish populations vary geographically in demography and life history due to environmental and ecological processes and in response to exploitation. However, population dynamic models and stock assessments, used to manage fisheries, rarely explicitly incorporate spatial variation to inform management decisions. Here, we describe extensive geographic variation in several demographic and life history characteristics (e.g., size structure, growth, survivorship, maturation, and sex change) of California sheephead (Semicossyphus pulcher), a temperate rocky reef fish targeted by recreational and commercial fisheries. Fish were sampled from nine locations throughout southern California in 2007–2008. We developed a dynamic size and age-structured model, parameterized separately for each location, to assess the potential cost or benefit in terms of fisheries yield and conservation objectives of changing minimum size limits and/or fishing mortality rates (compared to the status quo). Results indicate that managing populations individually, with location-specific regulations, could increase yield by over 26% while maintaining conservative levels of spawning biomass. While this local management approach would be challenging to implement in practice, we found statistically similar increases in yield could be achieved by dividing southern California into two separate management regions, reflecting geographic similarities in demography. To maximize yield, size limits should be increased by 90 mm in the northern region and held at current levels in the south. We also found that managing the fishery as one single stock (the status quo), but with a size limit 50 mm greater than the current regulations, could increase overall fishery yield by 15%. Increases in size limits are predicted to enhance fishery yield and may also have important ecological consequences for the predatory role of sheephead in kelp forests. This framework for incorporating demographic variation into fisheries models can be exported generally to other species and may aid in identifying the appropriate spatial scales for fisheries management
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