14 research outputs found
Isospin Mixing and Model Dependence
We show that recent calculations of \Delta I=3/2 effects in nonleptonic
hyperon decay induced by m_d-m_u\neq 0 are subject to significant model
dependence.Comment: 8 page standard Latex fil
Superpartner Solutions of a BPS Monopole in Noncommutative Space
We construct U(2) BPS monopole superpartner solutions in N=2 non-commutative
super Yang-Mills theory. Calculation to the second order in the noncommutative
parameter shows that there is no electric quadrupole moment that is
expected from the magnetic dipole structure of noncommtative U(2) monopole.
This might give an example of the nature of how supersymmetry works not
changing between the commutative and noncommutative theories.Comment: 8 page
Electric Dipole Moment of a BPS Monopole
Monopole ``superpartner'' solutions are constructed by acting with finite,
broken supersymmetry transformations on a bosonic N=2 BPS monopole. The terms
beyond first order in this construction represent the backreaction of the the
fermionic zero-mode state on the other fields. Because of the quantum nature of
the fermionic zero-modes, the superpartner solution is necessarily operator
valued. We extract the electric dipole moment operator and show that it is
proportional to the fermion zero-mode angular momentum operator with a
gyroelectric ratio g=2. The magnetic quadrupole operator is shown to vanish
identically on all states. We comment on the usefulness of the monopole
superpartner solution for a study of the long-range spin dependent dynamics of
BPS monopoles.Comment: 8 pages, references and note adde
Asymptotic Limits and Structure of the Pion Form Factor
We use dispersive techniques to address the behavior of the pion form factor
as and . We perform the matching with the
constraints of perturbative QCD and chiral perturbation theory in the high
energy and low energy limits, leading to four sum rules. We present a version
of the dispersive input which is consistent with the data and with all
theoretical constraints. The results indicate that the asymptotic perturbative
QCD limit is approached relatively slowly, and give a model independent
determination of low energy chiral parameters.Comment: 8 pages, Latex, 2 figure
Carriage of the V279F Null Allele within the Gene Encoding Lp-PLA2 Is Protective from Coronary Artery Disease in South Korean Males
The Asia-specific PLA2G7 994G-T transversion leads to V279F substitution within the lipoprotein-associated phospholipase-A2 (Lp-PLAโ) and to absence of enzyme activity in plasma. This variant offers a unique natural experiment to assess the role of Lp-PLAโ in the pathogenesis of coronary artery disease (CAD) in humans. Given conflicting results from mostly small studies, a large two-stage case-control study was warranted.PLA2G7 V279F genotypes were initially compared in 2890 male cases diagnosed with CAD before age 60 with 3128 male controls without CAD at age 50 and above and subsequently in a second independent male dataset of 877 CAD cases and 1230 controls. In the first dataset, the prevalence of the 279F null allele was 11.5% in cases and 12.8% in controls. After adjustment for age, body mass index, diabetes, smoking, glucose and lipid levels, the OR (95% CI) for CAD for this allele was 0.80 (0.66-0.97, pโ=โ0.02). The results were very similar in the second dataset, despite lower power, with an allele frequency of 11.2% in cases and 12.5% in controls, leading to a combined OR of 0.80 (0.69-0.92), pโ=โ0.002. The magnitude and direction of this genetic effect were fully consistent with large epidemiological studies on plasma Lp-PLAโ activity and CAD risk.Natural deficiency in Lp-PLAโ activity due to carriage of PLA2G7 279F allele protects from CAD in Korean men. These results provide evidence for a causal relationship between Lp-PLAโ and CAD, and support pharmacological inhibition of this enzyme as an innovative way to prevent CAD
Carriage of the V279F Null Allele within the Gene Encoding Lp-PLA2 Is Protective from Coronary Artery Disease in South Korean Males
The Asia-specific PLA2G7 994G-T transversion leads to V279F substitution within the lipoprotein-associated phospholipase-A2 (Lp-PLAโ) and to absence of enzyme activity in plasma. This variant offers a unique natural experiment to assess the role of Lp-PLAโ in the pathogenesis of coronary artery disease (CAD) in humans. Given conflicting results from mostly small studies, a large two-stage case-control study was warranted.PLA2G7 V279F genotypes were initially compared in 2890 male cases diagnosed with CAD before age 60 with 3128 male controls without CAD at age 50 and above and subsequently in a second independent male dataset of 877 CAD cases and 1230 controls. In the first dataset, the prevalence of the 279F null allele was 11.5% in cases and 12.8% in controls. After adjustment for age, body mass index, diabetes, smoking, glucose and lipid levels, the OR (95% CI) for CAD for this allele was 0.80 (0.66-0.97, pโ=โ0.02). The results were very similar in the second dataset, despite lower power, with an allele frequency of 11.2% in cases and 12.5% in controls, leading to a combined OR of 0.80 (0.69-0.92), pโ=โ0.002. The magnitude and direction of this genetic effect were fully consistent with large epidemiological studies on plasma Lp-PLAโ activity and CAD risk.Natural deficiency in Lp-PLAโ activity due to carriage of PLA2G7 279F allele protects from CAD in Korean men. These results provide evidence for a causal relationship between Lp-PLAโ and CAD, and support pharmacological inhibition of this enzyme as an innovative way to prevent CAD
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Asymptotic Limits and Structure of the Pion Form-Factor
We use dispersive techniques to address the behavior of the pion form factor as Q2โโ and Q2โ0. We perform the matching with the constraints of perturbative QCD and chiral perturbation theory in the high-energy and low-energy limits, leading to four sum rules. We present a version of the dispersive input which is consistent with the data and with all theoretical constraints. The results indicate that the asymptotic perturbative QCD limit is approached relatively slowly, and give a model-independent determination of low-energy chiral parameters