5,571 research outputs found
Thermodynamics of quantum systems with multiple conserved quantities
We consider a generalisation of thermodynamics that deals with multiple
conserved quantities at the level of individual quantum systems. Each conserved
quantity, which, importantly, need not commute with the rest, can be extracted
and stored in its own battery. Unlike in standard thermodynamics, where the
second law places a constraint on how much of the conserved quantity (energy)
that can be extracted, here, on the contrary, there is no limit on how much of
any individual conserved quantity that can be extracted. However, other
conserved quantities must be supplied, and the second law constrains the
combination of extractable quantities and the trade-offs between them which are
allowed. We present explicit protocols which allow us to perform arbitrarily
good trade-offs and extract arbitrarily good combinations of conserved
quantities from individual quantum systems.Comment: 16 pages, 3 figure
Exploring the limits of no backward in time signalling
We present an operational and model-independent framework to investigate the
concept of no-backwards-in-time signaling. We define no-backwards-in-time
signaling conditions, closely related to the spatial no-signaling conditions.
These allow for theoretical possibilities in which the future affects the past,
nevertheless without signaling backwards in time. This is analogous to
non-local but no-signaling spatial correlations. Furthermore, our results shed
new light on situations with indefinite causal structure and their connection
to quantum theory.Comment: 10 pages, 3 figures, v2: reference adde
Pre- and post-selected quantum states: density matrices, tomography, and Kraus operators
We present a general formalism for charecterizing 2-time quantum states,
describing pre- and post-selected quantum systems. The most general 2-time
state is characterized by a `density vector' that is independent of
measurements performed between the preparation and post-selection. We provide a
method for performing tomography of an unknown 2-time density vector. This
procedure, which cannot be implemented by weak or projective measurements,
brings new insight to the fundamental role played by Kraus operators in quantum
measurements. Finally, after showing that general states and measurements are
isomorphic, we show that any measurement on a 2-time state can be mapped to a
measurement on a preselected bipartite state.Comment: 7 page
Lattice Gluon and Ghost Propagators, and the Strong Coupling in Pure SU(3) Yang-Mills Theory: Finite Lattice Spacing and Volume Effects
The dependence of the Landau gauge two point gluon and ghost correlation
functions on the lattice spacing and on the physical volume are investigated
for pure SU(3) Yang-Mills theory in four dimensions using lattice simulations.
We present data from very large lattices up to and for two lattice
spacings fm and fm corresponding to volumes of (13 fm)
and (8 fm), respectively. Our results show that, for sufficiently
large physical volumes, both propagators have a mild dependence on the lattice
volume. On the other hand, the gluon and ghost propagators change with the
lattice spacing in the infrared region, with the gluon propagator having a
stronger dependence on compared to the ghost propagator. In what concerns
the strong coupling constant , as defined from gluon and ghost
two point functions, the simulations show a sizeable dependence on the lattice
spacing for the infrared region and for momenta up to GeV
Development of a DNA Mini-Barcoding Protocol Targeting COI for the Identification of Elasmobranch Species in Shark Cartilage Pills
Many elasmobranch (shark and ray) species are considered threatened and their identification in processed products is important for conservation and authentication purposes. However, identification of elasmobranch species in shark cartilage pills has proven difficult using existing methodologies. The objective of this study was to develop a DNA mini-barcoding protocol using a ~130 bp region of the cytochrome c oxidase subunit I (COI) gene for species identification in shark cartilage pills. A total of 22 shark cartilage products underwent DNA extraction in duplicate using the DNeasy Blood and Tissue Kit (Qiagen). The effectiveness of a clean-up step following DNA extraction was analyzed by comparing DNA purity values and polymerase chain reaction (PCR) amplification rates. Next, five different mini-barcode primer sets were compared based on amplification rates, and the three top-performing primer sets were used in DNA sequencing. The incorporation of a clean-up step following DNA extraction showed a slight advantage over DNA extraction alone, with a higher amplification rate (52.3% vs. 47.8%) and A260/A230 value (3.3 vs. 0.6). The three primer sets selected for DNA mini-barcoding showed DNA sequencing rates of 54.5–65.9% among the 44 duplicate samples. When the results for all three primer sets were combined, 18 of the 22 shark cartilage products were identified to the species or genus level. On an individual basis, the best-performing primer set identified 16 of the 22 products to the species or genus level. Overall, the protocol developed in this study increased the identification rate for elasmobranches in cartilage products by more than 2-fold as compared to previous research
Properties of the open cluster Tombaugh 1 from high resolution spectroscopy and uvbyCaH photometry
Open clusters can be the key to deepen our knowledge on various issues
involving the structure and evolution of the Galactic disk and details of
stellar evolution because a cluster's properties are applicable to all its
members. However the number of open clusters with detailed analysis from high
resolution spectroscopy and/or precision photometry imposes severe limitation
on studies of these objects. To expand the number of open clusters with
well-defined chemical abundances and fundamental parameters, we investigate the
poorly studied, anticenter open cluster Tombaugh 1. Using precision
uvbyCaH photometry and high resolution spectroscopy, we derive the
cluster's properties and, for the first time, present detailed abundance
analysis of 10 potential cluster stars. Using radial position from the cluster
center and multiple color indices, we have isolated a sample of unevolved
probable, single-star members of Tombaugh 1. The weighted photometric
metallicity from and is [Fe/H] = -0.10 0.02, while a match to
the Victoria-Regina Str\"{o}mgren isochrones leads to an age of 0.95 0.10
Gyr and an apparent modulus of = 13.10 0.10. Radial velocities
identify 6 giants as probable cluster members and the elemental abundances of
Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni, Y,Ba, Ce, and Nd have been derived for both
the cluster and the field stars. Tombaugh 1 appears to be a typical inner thin
disk, intermediate-age open cluster of slightly subsolar metallicity, located
just beyond the solar circle, with solar elemental abundance ratios except for
the heavy s-process elements, which are a factor of two above solar. Its
metallicity is consistent with a steep metallicity gradient in the
galactocentric region between 9.5 and 12 kpc. Our study also shows that Cepheid
XZ CMa is not a member of Tombaugh 1, and reveals that this Cepheid presents
signs of barium enrichment.Comment: 74 pages, 15 figures, 13 tables; Accepted for publication in A
PCR Cloning Combined With DNA Barcoding Enables Partial Identification of Fish Species in a Mixed-Species Product
DNA barcoding is a valuable tool for regulatory identification of fish species; however, it does not perform well when multiple species are present within the same food product. Therefore, the objective of this study was to examine the use of PCR cloning to identify fish in a mixed-species product that cannot be identified with standard DNA barcoding. A total of 15 fish ball mixtures were prepared with known amounts of Nile tilapia (Oreochromis niloticus), Pacific cod (Gadus macrocephalus), and walleye pollock (Gadus chalcogrammus). Three subsamples from each fish ball underwent DNA extraction, full DNA barcoding (655 bp), and mini-barcoding (226 bp) of the cytochrome c oxidase subunit 1 (CO1) gene. Subsamples that did not pass sequencing according to regulatory standards were further analyzed with PCR cloning. All fish balls made of just one species tested positive for that species (i.e., tilapia, cod, or pollock) with both full and mini-barcoding. However, only tilapia was detected in fish balls containing multiple species when tested with standard barcoding techniques, reflecting an inaccurate representation of the fish mixture and suggesting species bias. PCR cloning allowed for identification of Pacific cod in 86% of the mixed-species fish balls tested with fullbarcode cloning and 100% of the mixed-species fish ball tested with mini-barcode cloning. However, PCR cloning did not enable the identification of walleye pollock. Standard full barcoding produced more high quality sequences compared to minibarcoding yet failed to accurately detect all species present in the tested fish mixtures. Overall, the results of this study show that PCR cloning may be an effective method to identify certain fish in mixed-species products when standard DNA barcoding fails. However, additional research is needed to overcome the species bias observed in this study
Predicting In-Hospital Mortality of ICU Patients: The PhysioNet/Computing in Cardiology Challenge 2012
Acuity scores, such as APACHE, SAPS, MPM, and SOFA, are widely used to account for population differ ences in studies aiming to compare how medications, care guidelines, surgery, and other interventions impact mortality in Intensive Care Unit (ICU) patients. By contrast, the focus of the PhysioNet/CinC Challenge 2012 is to develop methods for patient-specific prediction of in-hospital mortality. The data used for the challenge consisted of 5 general descriptors and 36 time series (measurements of vital signs and laboratory results) from the first 48 hours of the first available ICU stay of 12,000 adult patients from the MIMIC II database. The challenge was organized as two events: event 1 measured performance of a binary classifier, and event 2 measured performance of a risk estimator. The score of event 1 was the lower of sensitivity and positive predictive value. The score for event 2 was a range-normalized Hosmer-Lemeshow statistic. A baseline algorithm (using SAPS-1) obtained event 1 and 2 scores of 0.3125 and 68.58 respectively. Most participants submitted entries that outperformed the baseline algorithm. The top final scores for events 1 and 2 were 0.5353 and 17.88 respectively.National Institute for Biomedical Imaging and Bioengineering (U.S.)National Institute of General Medical Sciences (U.S.) (NIH cooperative agreement U01-EB-008577)National Institute of General Medical Sciences (U.S.) (NIH grant R01-EB-001659
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