972 research outputs found
A Zoology of Bell inequalities resistant to detector inefficiency
We derive both numerically and analytically Bell inequalities and quantum
measurements that present enhanced resistance to detector inefficiency. In
particular we describe several Bell inequalities which appear to be optimal
with respect to inefficient detectors for small dimensionality d=2,3,4 and 2 or
more measurement settings at each side. We also generalize the family of Bell
inequalities described in Collins et all (Phys. Rev. Lett. 88, 040404) to take
into account the inefficiency of detectors. In addition we consider the
possibility for pairs of entangled particles to be produced with probability
less than one. We show that when the pair production probability is small, one
must in general use different Bell inequalities than when the pair production
probability is high.Comment: 12 pages, revtex. Appendix completed, minor revision
Transcendence over Diversity: black women in the academy
Universities, like many major public institutions have embraced the notion of âdiversityâ virtually uncritically- it is seen as a moral âgood in itselfâ. But what happens to those who come to represent âdiversityâ- the black and minority ethnic groups targeted to increase the institutions thirst for global markets and aversion to accusations of institutional racism? Drawing on existing literature which analyses the process of marginalization in higher education, this paper explores the individual costs to black and female academic staff regardless of the discourse on diversity. However despite the exclusion of staff, black and minority ethnic women are also entering higher education in relatively large numbers as students. Such âgrassrootsâ educational urgency transcends the dominant discourse on diversity and challenges presumptions inherent in top down initiatives such as âwidening participationâ. Such a collective movement from the bottom up shows the importance of understanding black female agency when unpacking the complex dynamics of gendered and racialised exclusion. Black womenâs desire for education and learning makes possible a reclaiming of higher education from creeping instrumentalism and reinstates it as a radical site of resistance and refutation
The core of Rodinia formed by the juxtaposition of opposed retreating and advancing accretionary orogens
Long-lived (800âŻMa) Paleoâ to Mesoproterozoic accretionary orogens on the margins of Laurentia, Baltica, Amazonia, and Kalahari collided to form the core of the supercontinent, Rodinia. Accretionary orogens in Laurentia and Baltica record predominately radiogenic zircon ΔHf(t) and whole-rock Pb isotopic compositions, short crustal residence times (ca. 0.5âŻGa), and the development of arc-backarc complexes. The accretionary orogenic record of Laurentia and Baltica is consistent with a retreating accretionary orogen and analogous to the Phanerozoic western Pacific orogenic system. In contrast, the Mesoproterozoic orogens of Amazon and Kalahari cratons record unradiogenic zircon ΔHf(t) values, ca. 0.8âŻGa crustal residence times, and more ancient whole-rock Pb isotopic signatures. The accretionary orogenic record of Amazonia and Kalahari indicates the preferential incorporation of cratonic material in continental arcs of advancing accretionary orogens comparable to the Phanerozoic eastern Pacific orogenic system. Based on similarities in the geodynamic evolution of the Phanerozoic circum-Pacific orogens peripheral to Gondwana/Pangea, we suggest that the Mesoproterozoic accretionary orogens formed as peripheral subduction zones along the margin of the supercontinent Nuna (ca. 1.8â1.6âŻGa). The eventual collapse of this peripheral subduction zone onto itself and closure of the external ocean around Nuna to form Rodinia is equivalent to the projected future collapse of the circum-Pacific subduction system and juxtaposition of Australia-Asia with South America. The juxtaposition of advancing and retreating accretionary orogens at the core of the supercontinent Rodinia demonstrates that supercontinent assembly can occur by the closure of external oceans and indicates that future closure of the Pacific Ocean is plausible
Scaling tests of the improved Kogut-Susskind quark action
Improved lattice actions for Kogut-Susskind quarks have been shown to improve
rotational symmetry and flavor symmetry. In this work we find improved scaling
behavior of the rho and nucleon masses expressed in units of a length scale
obtained from the static quark potential, and better behavior of the Dirac
operator in instanton backgrounds.Comment: 4 pages, 4 figures, Revte
Determination of the Strange Quark Content of the Nucleon from a Next-to-Leading-Order QCD Analysis of Neutrino Charm Production
We present the first next-to-leading-order QCD analysis of neutrino charm
production, using a sample of 6090 - and -induced
opposite-sign dimuon events observed in the CCFR detector at the Fermilab
Tevatron. We find that the nucleon strange quark content is suppressed with
respect to the non-strange sea quarks by a factor \kappa = 0.477 \:
^{+\:0.063}_{-\:0.053}, where the error includes statistical, systematic and
QCD scale uncertainties. In contrast to previous leading order analyses, we
find that the strange sea -dependence is similar to that of the non-strange
sea, and that the measured charm quark mass, , is larger and consistent with that determined in other processes.
Further analysis finds that the difference in -distributions between
and is small. A measurement of the Cabibbo-Kobayashi-Maskawa
matrix element is also presented.
uufile containing compressed postscript files of five Figures is appended at
the end of the LaTeX source.Comment: Nevis R#150
The impact of hydraulic retention time on the performance of two configurations of anaerobic pond for municipal sewage treatment
Anaerobic ponds have the potential to contribute to low carbon wastewater treatment, however are currently restricted by long hydraulic residence time (HRT) which leads to large land requirements. A two-stage anaerobic pond (SAP) design was trialled against a single-stage control (CAP) over four HRTs down to 0.5 days, to determine the lowest HRT at which the ponds could operate effectively. No statistical differences were observed in particulate removal between the ponds over all four HRTs, suggesting solids loading is not a critical factor in AP design. Significantly higher biogas production rates were observed in the SAP than the CAP at 1.5 d and 1.0 d HRT, and microbial community profiling suggests the two-stage design may be facilitating spatial separation of the anaerobic digestion process along reactor length. Hydrogenotrophic methanogensis dominated over aceticlastic, with acetate oxidisation a likely degradation pathway. Experimental tracer studies were compared to CFD simulations, with the SAP showing greater hydraulic efficiency, and differences more pronounced at shorter HRTs. Greater flow recirculation between baffles was observed in CFD velocity profiles, demonstrating baffles can dissipate preferential flow patterns and increase effective pond volume, especially at high flow rates. The study demonstrates the potential of APs to be operated at shorter HRTs in psychrophilic conditions, presenting an opportunity for use as pre-treatments (in place of septic tanks) and primary treatment for full wastewater flows. Two-stage designs should be investigated to separate the stages of the anaerobic digestion process by creating preferential conditions along the pond length
Static quantities of the W boson in the SU_L(3) X U_X(1) model with right-handed neutrinos
The static electromagnetic properties of the boson, and
, are calculated in the SU_L(3)} \times U_X(1) model with
right-handed neutrinos. The new contributions from this model arise from the
gauge and scalar sectors. In the gauge sector there is a new contribution from
a complex neutral gauge boson and a singly-charged gauge boson .
The mass of these gauge bosons, called bileptons, is expected to be in the
range of a few hundreds of GeV according to the current bounds from
experimental data. If the bilepton masses are of the order of 200 GeV, the size
of their contribution is similar to that obtained in other weakly coupled
theories. However the contributions to both and are
negligible for very heavy or degenerate bileptons. As for the scalar sector, an
scenario is examined in which the contribution to the form factors is
identical to that of a two-Higgs-doublet model. It is found that this sector
would not give large corrections to and .Comment: New material included. Final version to apppear in Physical Review
Proton-proton scattering above 3 GeV/c
A large set of data on proton-proton differential cross sections, analyzing
powers and the double polarization parameter A_NN is analyzed employing the
Regge formalism. We find that the data available at proton beam momenta from 3
GeV/c to 50 GeV/c exhibit features that are very well in line with the general
characteristics of Regge phenomenology and can be described with a model that
includes the rho, omega, f_2, and a_2 trajectories and single Pomeron exchange.
Additional data, specifically for spin-dependent observables at forward angles,
would be very helpful for testing and refining our Regge model.Comment: 16 pages, 19 figures; revised version accepted for publication in
EPJ
A novel cardiovascular systems model to quantify drugs effects on the interârelationship between contractility and other hemodynamic variables
The use of systems-based pharmacological modeling approaches to characterize mode-of-action and concentration-effect relationships for drugs on specific hemodynamic variables has been demonstrated. Here, we (i) expand a previously developed hemodynamic system model through integration of cardiac output (CO) with contractility (CTR) using pressure-volume loop theory, and (ii) evaluate the contribution of CO data for identification of system-specific parameters, using atenolol as proof-of-concept drug. Previously collected experimental data was used to develop the systems model, and included measurements for heart rate (HR), CO, mean arterial pressure (MAP), and CTR after administration of atenolol (0.3-30Â mg/kg) from three in vivo telemetry studies in conscious Beagle dogs. The developed cardiovascular (CVS)-contractility systems model adequately described the effect of atenolol on HR, CO, dP/dtmax, and MAP dynamics and allowed identification of both system- and drug-specific parameters with good precision. Model parameters were structurally identifiable, and the true mode of action can be identified properly. Omission of CO data did not lead to a significant change in parameter estimates compared to a model that included CO data. The newly developed CVS-contractility systems model characterizes short-term drug effects on CTR, CO, and other hemodynamic variables in an integrated and quantitative manner. When the baseline value of total peripheral resistance is predefined, CO data was not required to identify drug- and system-specific parameters. Confirmation of the consistency of system-specific parameters via inclusion of data for additional drugs and species is warranted. Ultimately, the developed model has the potential to be of relevance to support translational CVS safety studies.Pharmacolog
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