4,244 research outputs found
Incidence and classification of childhood vasculitides in Denmark 1976â1998 according to the consensus criteria for the classification of childhood vasculitides
The Effects of Possible Contamination on the Radiocarbon Dating of the Dead Sea Scrolls II: Empirical Methods to Remove Castor Oil and Suggestions for Redating
While kept at the Rockefeller Museum in East Jerusalem, many Dead Sea Scroll fragments were exposed to castor oil by the original team of editors in the course of cleaning the parchments. Castor oil must be regarded as a serious contaminant in relation to radiocarbon dating. If modern castor oil is present and is not removed prior to dating, the 14C dates will be skewed artificially towards modern values. Earlier, it was shown that the standard AAA pretreatment procedure used in the 2 previous studies dating Dead Sea Scroll samples is not capable of removing castor oil from parchment samples. In the present work, we show that it is unlikely that castor oil reacts with the amino acids of the parchment proteins, a finding which leaves open the possibility of devising a cleaning method that can effectively remove castor oil. We then present 3 different pretreatment protocols designed to effectively remove castor oil from parchment samples. These involve 3 different cleaning techniques: extraction with supercritical CO2, ultrasound cleaning, and Soxhlet extractionâeach with their own advantages and disadvantages. Our data show that the protocol involving Soxhlet extraction is the best suited for the purpose of decontaminating the Dead Sea Scrolls, and we recommend that this protocol be used in further attempts to 14C date the Dead Sea Scrolls. If such an attempt is decided on by the proper authorities, we propose a list of Scroll texts, which we suggest be redated in order to validate the 14C dates done earlier.
Distinguishing n Hamiltonians on C^n by a single measurement
If an experimentalist wants to decide which one of n possible Hamiltonians
acting on an n dimensional Hilbert space is present, he can conjugate the time
evolution by an appropriate sequence of known unitary transformations in such a
way that the different Hamiltonians result in mutual orthogonal final states.
We present a general scheme providing such a sequence.Comment: 4 pages, Revte
Geochemical comparison of K-T boundaries from the Northern and Southern Hemispheres
Closely spaced (cm-scale) traverses through the K-T boundary at Stevns Klint (Denmark), Woodside Creek (New Zealand) and a new Southern Hemisphere site at Richards Bay (South Africa) were subjected to trace element and isotopic (C, O, Sr) investigation. Intercomparison between these data-sets, and correlation with the broad K-T database available in the literature, indicate that the chemistry of the boundary clays is not globally constant. Variations are more common than similarities, both of absolute concentrations, and interelement ratios. For example, the chondrite normalized platinum-group elements (PGE) patterns of Stevns Klint are not like those of Woodside Creek, with the Pt/Os ratios showing the biggest variation. These differences in PGE patterns are difficult to explain by secondary alteration of a layer that was originally chemically homogeneous, especially for elements of such dubious crustal mobility as Os and Ir. The data also show that enhanced PGE concentrations, with similar trends to those of the boundary layers, occur in the Cretaceous sediments below the actual boundary at Stevns Klint and all three the New Zealand localities. This confirms the observations of others that the geochemistry of the boundary layers apparently does not record a unique component. It is suggested that terrestrial processes, eg. an extended period of Late Cretaceous volcanism can offer a satisfactory explanation for the features of the K-T geochemical anomaly. Such models would probably be more consistent with the observed stepwise, or gradual, palaeontological changes across this boundary, than the instant catastrophe predicated by the impact theory
Quantum state tomography using a single apparatus
The density matrix of a two-level system (spin, atom) is usually determined
by measuring the three non-commuting components of the Pauli vector. This
density matrix can also be obtained via the measurement data of two commuting
variables, using a single apparatus. This is done by coupling the two-level
system to a mode of radiation field, where the atom-field interaction is
described with the Jaynes--Cummings model. The mode starts its evolution from a
known coherent state. The unknown initial state of the atom is found by
measuring two commuting observables: the population difference of the atom and
the photon number of the field. We discuss the advantages of this setup and its
possible applications.Comment: 7 pages, 8 figure, Phys. Rev.
Exogenous lactate supplementation to the injured brain: misleading conclusions with clinical implications
Evidence for entangled states of two coupled flux qubits
We have studied the low-frequency magnetic susceptibility of two inductively
coupled flux qubits using the impedance measurement technique (IMT), through
their influence on the resonant properties of a weakly coupled high-quality
tank circuit. In a single qubit, an IMT dip in the tank's current--voltage
phase angle at the level anticrossing yields the amplitude of coherent flux
tunneling. For two qubits, the difference (IMT deficit) between the sum of
single-qubit dips and the dip amplitude when both qubits are at degeneracy
shows that the system is in a mixture of entangled states (a necessary
condition for entanglement). The dependence on temperature and relative bias
between the qubits allows one to determine all the parameters of the effective
Hamiltonian and equilibrium density matrix, and confirms the formation of
entangled eigenstates.Comment: 4 pages, 4 figures, final versio
Massive Parallel Quantum Computer Simulator
We describe portable software to simulate universal quantum computers on
massive parallel computers. We illustrate the use of the simulation software by
running various quantum algorithms on different computer architectures, such as
a IBM BlueGene/L, a IBM Regatta p690+, a Hitachi SR11000/J1, a Cray X1E, a SGI
Altix 3700 and clusters of PCs running Windows XP. We study the performance of
the software by simulating quantum computers containing up to 36 qubits, using
up to 4096 processors and up to 1 TB of memory. Our results demonstrate that
the simulator exhibits nearly ideal scaling as a function of the number of
processors and suggest that the simulation software described in this paper may
also serve as benchmark for testing high-end parallel computers.Comment: To appear in Comp. Phys. Com
Contributions of genetic and nonâgenetic sources to variation in cooperative behaviour in a cooperative mammal
This is the author accepted manuscript. the final version is available from Wiley via the DOI in this recordData archiving:
Data and code for reproducing the main analyses are available through the Dryad Digital Repository database (https://doi.org/10.5061/dryad.cfxpnvx68). The data and code for the meta-analysis of heritability estimates of selected traits in wild mammals are available in Files S3âS5.The evolution of cooperative behavior is a major area of research among evolutionary biologists and behavioral ecologists, yet there are few estimates of its heritability or its evolutionary potential, and long-term studies of identifiable individuals are required to disentangle genetic and nongenetic components of cooperative behavior. Here, we use long-term data on over 1800 individually recognizable wild meerkats (Suricata suricatta) collected over 30 years and a multigenerational genetic pedigree to partition phenotypic variation in three cooperative behaviors (babysitting, pup feeding, and sentinel behavior) into individual, additive genetic, and other sources, and to assess their repeatability and heritability. In addition to strong effects of sex, age, and dominance status, we found significant repeatability in individual contributions to all three types of cooperative behavior both within and across breeding seasons. Like most other studies of the heritability of social behavior, we found that the heritability of cooperative behavior was low. However, our analysis suggests that a substantial component of the repeatable individual differences in cooperative behavior that we observed was a consequence of additive genetic variation. Our results consequently indicate that cooperative behavior can respond to selection, and suggest scope for further exploration of the genetic basis of social behaviorEuropean Union Horizon 2020Human Frontier Science ProgramUniversity of Zurich.Swiss National Science FoundationMammal Research Institute at the University of Pretoria, South Afric
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