The rare decay B→πℓ^{+}ℓ^{-} arises from b→d flavor-changing neutral currents and could be sensitive to physics beyond the standard model. Here, we present the first ab initio QCD calculation of the ...B→π tensor form factor f_{T}. Together with the vector and scalar form factors f_{+} and f_{0} from our companion work J. A. Bailey et al., Phys. Rev. D 92, 014024 (2015), these parametrize the hadronic contribution to B→π semileptonic decays in any extension of the standard model. We obtain the total branching ratio BR(B^{+}→π^{+}μ^{+}μ^{-})=20.4(2.1)×10^{-9} in the standard model, which is the most precise theoretical determination to date, and agrees with the recent measurement from the LHCb experiment R. Aaij et al., J. High Energy Phys. 12 (2012) 125.
The quark-gluon plasma is a novel state of matter in which quarks are no longer confined to bound states such as baryons and mesons. Just after the Big Bang the Universe was filled with a quark-gluon ...plasma. The cores of neutron stars may well be a quark-gluon plasma. At the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, scientists collide high energy gold beams to produce and study the quark gluon plasma. Lattice gauge theorists use computers to study to properties of the quark-gluon plasma such as the temperature required to produce it and its equation of state. These demanding calculations will require over a Petaflop-year of computing to achieve theoretical goals.
Lissencephaly is a malformation of cortical development typically caused by deficient neuronal migration resulting in cortical thickening and reduced gyration. Here we describe a “thin” lissencephaly ...(TLIS) variant characterized by megalencephaly, frontal predominant pachygyria, intellectual disability, and seizures. Trio-based whole-exome sequencing and targeted re-sequencing identified recessive mutations of CRADD in six individuals with TLIS from four unrelated families of diverse ethnic backgrounds. CRADD (also known as RAIDD) is a death-domain-containing adaptor protein that oligomerizes with PIDD and caspase-2 to initiate apoptosis. TLIS variants cluster in the CRADD death domain, a platform for interaction with other death-domain-containing proteins including PIDD. Although caspase-2 is expressed in the developing mammalian brain, little is known about its role in cortical development. CRADD/caspase-2 signaling is implicated in neurotrophic factor withdrawal- and amyloid-β-induced dendritic spine collapse and neuronal apoptosis, suggesting a role in cortical sculpting and plasticity. TLIS-associated CRADD variants do not disrupt interactions with caspase-2 or PIDD in co-immunoprecipitation assays, but still abolish CRADD’s ability to activate caspase-2, resulting in reduced neuronal apoptosis in vitro. Homozygous Cradd knockout mice display megalencephaly and seizures without obvious defects in cortical lamination, supporting a role for CRADD/caspase-2 signaling in mammalian brain development. Megalencephaly and lissencephaly associated with defective programmed cell death from loss of CRADD function in humans implicate reduced apoptosis as an important pathophysiological mechanism of cortical malformation. Our data suggest that CRADD/caspase-2 signaling is critical for normal gyration of the developing human neocortex and for normal cognitive ability.
The Cell Broadband Engine architecture is a revolutionary processor architecture well suited for many scientific codes. This paper reports on an effort to implement several traditional ...high-performance scientific computing applications on the Cell Broadband Engine processor, including molecular dynamics, quantum chromodynamics and quantum chemistry codes. The paper discusses data and code restructuring strategies necessary to adapt the applications to the intrinsic properties of the Cell processor and demonstrates performance improvements achieved on the Cell architecture. It concludes with the lessons learned and provides practical recommendations on optimization techniques that are believed to be most appropriate.
An accurate knowledge of the parameters governing the kinetics of block copolymer self‐assembly is crucial to model the time‐ and temperature‐dependent evolution of pattern formation during annealing ...as well as to predict the most efficient conditions for the formation of defect‐free patterns. Here, the self‐assembly kinetics of a lamellar PS‐b‐PMMA block copolymer under both isothermal and non‐isothermal annealing conditions are investigated by combining grazing‐incidence small‐angle X‐ray scattering (GISAXS) experiments with a novel modelling methodology that accounts for the annealing history of the block copolymer film before it reaches the isothermal regime. Such a model allows conventional studies in isothermal annealing conditions to be extended to the more realistic case of non‐isothermal annealing and prediction of the accuracy in the determination of the relevant parameters, namely the correlation length and the growth exponent, which define the kinetics of the self‐assembly.
The self‐assembly kinetics of a lamellar block copolymer are accurately characterized in situ and in real time using grazing‐incidence small‐angle X‐ray scattering. A novel modelling methodology is implemented for the determination of self‐assembly kinetic parameters by properly considering the initial annealing conditions for both isothermal and non‐isothermal processes.
A case of acute hemorrhagic leukoencephalitis (AHLE) in a 6-year-old girl is reported. The presentation was typical for acute hemorrhagic leukoencephalitis, with acute onset of a rapidly progressive ...neurologic disorder with asymmetric involvement of brain, with polymorphonuclear predominant peripheral leukocytosis and cerebrospinal fluid pleocytosis. Cerebrospinal fluid findings not previously reported included elevation of IgG and the presence of myelin basic protein. Additional previously unreported findings were striking abnormalities on magnetic resonance imaging (MRI) of the brain, in contrast to normal findings on computed tomography (CT). The child was treated with high dose intravenous steroids and made a full recovery, with a parallel disappearance of all of her cerebrospinal fluid abnormalities and almost all of her abnormalities on MRI. Detailed examination of cerebrospinal fluid and MRI of brain should facilitate early diagnosis in other cases of suspected acute hemorrhagic leukoencephalitis and high-dose steroid therapy may lead to improved clinical outcomes.
Abstract
We review lattice results related to pion, kaon,
D
-meson,
B
-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More ...specifically, we report on the determination of the light-quark masses, the form factor
$$f_+(0)$$
f
+
(
0
)
arising in the semileptonic
$$K \rightarrow \pi $$
K
→
π
transition at zero momentum transfer, as well as the decay constant ratio
$$f_K/f_\pi $$
f
K
/
f
π
and its consequences for the CKM matrix elements
$$V_{us}$$
V
us
and
$$V_{ud}$$
V
ud
. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of
$$SU(2)_L\times SU(2)_R$$
S
U
(
2
)
L
×
S
U
(
2
)
R
and
$$SU(3)_L\times SU(3)_R$$
S
U
(
3
)
L
×
S
U
(
3
)
R
Chiral Perturbation Theory. We review the determination of the
$$B_K$$
B
K
parameter of neutral kaon mixing as well as the additional four
B
parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for
$$m_c$$
m
c
and
$$m_b$$
m
b
as well as those for
D
- and
B
-meson decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant
$$\alpha _s$$
α
s
. Finally, in this review we have added a new section reviewing results for nucleon matrix elements of the axial, scalar and tensor bilinears, both isovector and flavor diagonal.
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