The charge and magnetic form factors, F-C and F-M, respectively, of He-3 are extracted in the kinematic range 25 fm(-2) <= Q(2) <= 61 fm(-2) from elastic electron scattering by detecting He-3 recoil ...nuclei and scattered electrons in coincidence with the two High Resolution Spectrometers of the Hall A Facility at Jefferson Lab. The measurements find evidence for the existence of a second diffraction minimum for the magnetic form factor at Q(2) = 49.3 fm(-2) and for the charge form factor at Q(2) = 62.0 fm(-2). Both minima are predicted to exist in the Q(2) range accessible by this Jefferson Lab experiment. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the three-body nuclear problem
There is very little research in the extant literature on the asymmetry that may exist in consumers reactions to changes in the aggregate level of advertising in the marketplace. Aggregate levels of ...advertising act as a signal to consumers regarding the health of the economy. In this study, we investigate the extent of this asymmetry in terms of how consumer confidence, which is a proxy for future consumer spending, responds to upturns and downturns in advertising revenues. We find that consumers react with higher levels of confidence to upturns in advertising revenues. However, consumers do not react to downturns in advertising revenue with commensurate reductions in consumer confidence. They ignore the signaling effects of a downturn in advertising revenues, displaying asymmetric behavior in response to changes in advertising revenue. The increase in consumer confidence resulting from an increase in advertising revenue is a delayed response effect and comes after two quarters lag. It is statistically significant at conventional levels for the following two quarters as a response to a one-time upturn in advertising revenues. The results provide important information to practitioners and researchers on the asymmetric signaling and ratchet effects of advertising on consumer behavior. The implication for practitioners and policy makers is that aggregate increases in advertising has a delayed positive effect on consumer confidence with positive implications for consumer spending. The implications for researchers is another example of asymmetry in human decision-making and specifically the tendency to embrace positive and ignore negative economic signals. The implication for investors is a better understanding of how macro advertising expenditures function as a leading indicator for consumer confidence, consumer spending, and economic growth.
Arthropathy is considered as an irreversible and progressive complication in patients with haemophilia, even in children on prophylaxis. To estimate the progression of haemophilic arthropathy, 85 ...joints of 24 boys with severe (n = 18) and moderate (n = 6) haemophilia (A: 22, B: 2) were investigated with clinical examination, X‐rays and magnetic resonance imaging (MRI) at two time periods (time 0 and 1). Patients’ age at time 0 was 10.5 ± 3.6 years and time elapsed to time 1 was 3.8 ± 1.4 years. At time 0: all investigated joints had more than three bleeds. Sixteen boys were on secondary prophylaxis for 5.4 ± 2.8 years. Clinical score (a modification of World Federation of Haemophilia’s scale): 2.0 ± 3.6, X‐ray score (Pettersson): 2.1 ± 2.8, MRI score (Denver): 4.5 ± 3.8. After the first evaluation, prophylaxis was intensified in 11 children and initiated in four. At time 1: clinical score: 1.5 ± 3.1, X‐ray: 1.7 ± 2.7, MRI score: 5.1 ± 4.1. On average, the clinical and X‐ray scores showed a significant improvement (26% and 40% of the joints respectively, P < 0.01) and the number of haemarthroses evidenced a threefold reduction from time 0 to 1 (P < 0.01), findings that could be associated with the modification of prophylaxis after time 0. MRI findings showed deterioration in 34% of the joints. Conversely, 14 joints (16.5%) with mild or moderate synovitis without cartilage degradation at time 0 showed an improvement at time 1. The information carried by the three scales could be divided into information shared by the three scores and information specific to each score, thus giving a more complete picture of joint damage caused by bleedings.
We present a study of high energy photodisintegration of proton-pairs through the γ+He3→p+p+n channel. Photon energies, Eγ, from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair ...with high relative momentum and a neutron nearly at rest. The s−11 scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photodisintegration. For Eγ below the scaling region, the scaled cross section was found to present a strong energy-dependent structure not observed in deuteron photodisintegration.
We investigate deep inelastic scattering from
3He and
3H within a conventional convolution treatment of binding and Fermi motion effects. Using realistic Faddeev wave functions together with a ...nucleon spectral function, we demonstrate that the free neutron structure function can be extracted in deep-inelastic scattering from
A=3 mirror nuclei, with nuclear effects canceling to within 2% for
x≲0.85.
The catalytic domain of chitobiase (β-
N-1-4 acetylhexosaminidase) from
Serratia marcescens, is an α/β TIM-barrel. This enzyme belongs to family 20 of glycosyl hydrolases in which a conserved amino ...acid pair, aspartate-glutamate, is present (Asp539-Glu540). It was proposed that catalysis by this enzyme family is carried out by glutamate 540 acting as a proton donor and by the acetamido group of the substrate as a nucleophile. We investigated the role of Asp539 and Glu540 by site-directed mutagenesis, biochemical characterization and by structural analyses of chitobiase-substrate co-crystals. We found that both residues are essential for chitobiase activity. The mutations, however, led to subtle changes in the catalytic site. Our results support the model that Glu540 acts as the proton donor and that Asp539 acts in several different ways. Asp539 restrains the acetamido group of the substrate in a specific orientation by forming a hydrogen bond with N2 of the non-reduced (−1) sugar. In addition, this residue participates in substrate binding. It is also required for the correct positioning of Glu540 and may provide additional negative charge at the active site. Thus, these biochemical and structural studies provide a molecular explanation for the functional importance and conservation of these residues.
We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The kinematic point (theta_lab = 12.3 degrees and Q^2=0.48 (GeV/c)^2) is ...chosen to provide sensitivity, at a level that is of theoretical interest, to the strange electric form factor G_E^s. The result, A=-14.5 +- 2.2 ppm, is consistent with the electroweak Standard Model and no additional contributions from strange quarks. In particular, the measurement implies G_E^s + 0.39G_M^s = 0.023 +- 0.034 (stat) +- 0.022 (syst) +- 0.026 (delta G_E^n), where the last uncertainty arises from the estimated uncertainty in the neutron electric form factor.
We present a next-to-leading order perturbative QCD analysis of world data on the spin dependent structure functions
g
1
p
,
g
1
n
, and
g
1
d
, including the new experimental information on the
Q
2 ...dependence of
g
1
n
. Careful attention is paid to the experimental and theoretical uncertainties. The data constrain the first moments of the polarized valence quark distributions, but only qualitatively constrain the polarized sea quark and gluon distributions. The NLO results are used to determine the
Q
2 dependence of the ratio
g
1
F
1
and evolve the experimental data to a constant
Q
2 = 5 GeV
2. We determine the first moments of the polarized structure functions of the proton and neutron and find agreement with the Bjorken sum rule.
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