1,071 research outputs found
The SIC Question: History and State of Play
Recent years have seen significant advances in the study of symmetric
informationally complete (SIC) quantum measurements, also known as maximal sets
of complex equiangular lines. Previously, the published record contained
solutions up to dimension 67, and was with high confidence complete up through
dimension 50. Computer calculations have now furnished solutions in all
dimensions up to 151, and in several cases beyond that, as large as dimension
844. These new solutions exhibit an additional type of symmetry beyond the
basic definition of a SIC, and so verify a conjecture of Zauner in many new
cases. The solutions in dimensions 68 through 121 were obtained by Andrew
Scott, and his catalogue of distinct solutions is, with high confidence,
complete up to dimension 90. Additional results in dimensions 122 through 151
were calculated by the authors using Scott's code. We recap the history of the
problem, outline how the numerical searches were done, and pose some
conjectures on how the search technique could be improved. In order to
facilitate communication across disciplinary boundaries, we also present a
comprehensive bibliography of SIC research.Comment: 16 pages, 1 figure, many references; v3: updating bibliography,
dimension eight hundred forty fou
Recommended from our members
Seasonal changes in water quality and Sargassum biomass in southwest Australia
Sargassum C. Agardh is one of the most diverse genera of marine macro-algae and commonly inhabits shallow tropical and sub-tropical waters. This study aimed to investigate the effect of seasonality and the associated water quality changes on the distribution, canopy cover, mean thallus length and the biomass of Sargassum beds around Point Peron, Shoalwater Islands Marine Park, Southwest Australia. Samples of Sargassum and seawater were collected every three months from summer 2012 to summer 2014 from four different reef zones. A combination of in situ observations and WorldView-2 satellite remote-sensing images were used to map the spatial
distribution of Sargassum beds and other associated benthic habitats. The results demonstrated a strong seasonal variation in the environmental parameters, canopy cover, mean thallus length, and biomass of Sargassum, which were significantly (P < 0.05) influenced by the nutrient concentration (PO43-, NO3-, NH4+) and rainfall. However, no variation in any studied parameter was observed among the four reef zones. The highest Sargassum biomass peaks occurred between late spring and early summer (from September to January). The results provide essential information to guide effective conservation and management, as well as sustainable utilisation of this coastal marine renewable resource
Thrust at N^3LL with Power Corrections and a Precision Global Fit for alphas(mZ)
We give a factorization formula for the e+e- thrust distribution dsigma/dtau
with tau=1-T based on soft-collinear effective theory. The result is applicable
for all tau, i.e. in the peak, tail, and far-tail regions. The formula includes
O(alphas^3) fixed-order QCD results, resummation of singular partonic alphas^j
ln^k(tau)/tau terms with N^3LL accuracy, hadronization effects from fitting a
universal nonperturbative soft function defined in field theory, bottom quark
mass effects, QED corrections, and the dominant top mass dependent terms from
the axial anomaly. We do not rely on Monte Carlo generators to determine
nonperturbative effects since they are not compatible with higher order
perturbative analyses. Instead our treatment is based on fitting
nonperturbative matrix elements in field theory, which are moments Omega_i of a
nonperturbative soft function. We present a global analysis of all available
thrust data measured at center-of-mass energies Q=35 to 207 GeV in the tail
region, where a two parameter fit to and the first moment
Omega_1 suffices. We use a short distance scheme to define Omega_1, called the
R-gap scheme, thus ensuring that the perturbative dsigma/dtau does not suffer
from an O(Lambda_QCD) renormalon ambiguity. We find alphas(mZ)=0.1135 \pm
(0.0002)_{expt} \pm (0.0005)_{hadr} \pm (0.0009)_{pert}, with chi^2/dof=0.91,
where the displayed 1-sigma errors are the total experimental error, the
hadronization uncertainty, and the perturbative theory uncertainty,
respectively. The hadronization uncertainty in alphas is significantly
decreased compared to earlier analyses by our two parameter fit, which
determines Omega_1=0.323 GeV with 16% uncertainty.Comment: 45 pages, 21 figures, v2: added discussion of bin integration vs.
cumulant differences; comparison to Becher & Schwartz improved; typo in Eq.55
fixe
Geography of hospital admissions for multiple sclerosis in England and comparison with the geography of hospital admissions for infectious mononucleosis: a descriptive study
Objective It is well recognised that variation in the geographical distribution of multiple sclerosis (MS) exists. Early studies in England have shown the disease to have been more common in the North than the South. However, this could be an artefact of inaccurate diagnosis and ascertainment, and recent data on MS prevalence are lacking. In the present study, data were analysed to provide a more contemporary map of the distribution of MS in England and, as infectious mononucleosis (IM) has been shown to be associated with the risk of MS, the geographical distribution of IM with that of MS was compared.Methods Analysis of linked statistical abstracts of hospital data for England between 1999 and 2005.Results There were 56 681 MS patients. The admission rate for MS was higher in females (22/10(5); 95% CI 21.8 to 22.3) than males (10.4/10(5); 95% CI 10.2 to 10.5). The highest admission rate for MS was seen for residents of Cumbria and Lancashire (North of England) (20.1/10(5); 95% CI 19.3 to 20.8) and the lowest admission rate was for North West London residents (South of England) (12.4/10(5); 95% CI 11.8 to 13.1). The geographical distributions of IM and MS were significantly correlated (weighted regression coefficient (r (w))=0.70, p<0.0001). Admission rates for MS were lowest in the area quintile with the highest level of deprivation and they were also lowest in the area quintile with the highest percentage of population born outside the UK. A significant association between northernliness and MS remained after adjustment for deprivation and UK birthplace.Conclusions The results show the continued existence of a latitude gradient for MS in England and show a correlation with the distribution of IM. The data have implications for healthcare provision, because lifetime costs of MS exceed 1 pound million per case in the UK, as well as for studies of disease causality and prevention
Renormalization group scaling in nonrelativistic QCD
We discuss the matching conditions and renormalization group evolution of
non-relativistic QCD. A variant of the conventional MS-bar scheme is proposed
in which a subtraction velocity nu is used rather than a subtraction scale mu.
We derive a novel renormalization group equation in velocity space which can be
used to sum logarithms of v in the effective theory. We apply our method to
several examples. In particular we show that our formulation correctly
reproduces the two-loop anomalous dimension of the heavy quark production
current near threshold.Comment: (27 pages, revtex
B decay shape variables and the precision determination of |Vcb| and mb
We present expressions for shape variables of B decay distributions in
several different mass schemes, to order and
(Lambda_{QCD}/mb)^3. Such observables are sensitive to the b quark mass and
matrix elements in the heavy quark effective theory, and recent measurements
allow precision determinations of some of these parameters. We perform a
combined fit to recent experimental results from CLEO, BABAR, and DELPHI, and
discuss the theoretical uncertainties due to nonperturbative and perturbative
effects. We discuss the possible discrepancy between the OPE prediction, recent
BABAR results and the measured branching fraction to D and D* states. We find
|Vcb| = (40.8 +- 0.9) x 10^{-3} and mb^{1S} = 4.74 +- 0.10 GeV, where the
errors are dominated by experimental uncertainties.Comment: 23 pages, 3 figures, Version to appear in PR
Redox Couples of Inducible Nitric Oxide Synthase
We report direct electrochemistry of the iNOS heme domain in a DDAB film on the surface of a basal plane graphite electrode. Cyclic voltammetry reveals Fe^(III/II) and Fe^(II/I) couples at −191 and −1049 mV (vs Ag/AgCl). Imidazole and carbon monoxide in solution shift the Fe^(III/II) potential by +20 and +62 mV, while the addition of dioxygen results in large catalytic waves at the onset of Fe^(III) reduction. Voltammetry at higher scan rates (with pH variations) reveals that the Fe^(III/II) cathodic peak can be resolved into two components, which are attributable to Fe^(III/II) couples of five- and six-coordinate hemes. Digital simulation of our experimental data implicates water dissociation from the heme as a gating mechanism for ET in iNOS
Multisite gynecologic endometrioid adenocarcinomas: Can mutation profiling be used to distinguish synchronous primary cancers from metastases?
It is well recognized that some patients with endometrioid gynecological cancers have tumors arising in multiple sites (ovary, endometrium, and endometriosis) at the time of diagnosis. Molecular analysis has helped discern whether these multisite cancers represent synchronous primary tumors or alternatively metastatic disease. We present a complex case of a patient with endometrioid carcinomas arising in multiple sites. We discuss the use of mutation profiling to discern clonality and highlight how this information may inform the clinical management of such cases
Global gene expression profiling identifies new therapeutic targets in acute Kawasaki disease.
BACKGROUND: Global gene expression profiling can provide insight into the underlying pathophysiology of disease processes. Kawasaki disease (KD) is an acute, self-limited vasculitis whose etiology remains unknown. Although the clinical illness shares certain features with other pediatric infectious diseases, the occurrence of coronary artery aneurysms in 25% of untreated patients is unique to KD. METHODS: To gain further insight into the molecular mechanisms underlying KD, we investigated the acute and convalescent whole blood transcriptional profiles of 146 KD subjects and compared them with the transcriptional profiles of pediatric patients with confirmed bacterial or viral infection, and with healthy control children. We also investigated the transcript abundance in patients with different intravenous immunoglobulin treatment responses and different coronary artery outcomes. RESULTS: The overwhelming signature for acute KD involved signaling pathways of the innate immune system. Comparison with other acute pediatric infections highlighted the importance of pathways involved in cell motility including paxillin, relaxin, actin, integrins, and matrix metalloproteinases. Most importantly, the IL1β pathway was identified as a potential therapeutic target. CONCLUSION: Our study revealed the importance of the IL-1 signaling pathway and a prominent signature of innate immunity and cell migration in the acute phase of the illness
- …