Statistical model analysis of the 12C(14N, α) reaction and coherence widths in 26Al

The ¹²C(¹⁴N, α)²²Na reaction was studied at bombarding energies between 22 and 39.2 MeV (lab) and a lab angle of 7°. Average coherence widths of states in the compound nucleus ²⁶Al populated in the reaction were obtained from excitation functions of twenty states or unresolved multiplets measured for states in ²²Na. From these data and Hauser-Feshbach predictions, values were determined for the level density parameters and for the effective moment of inertia of ²⁶Al. The critical angular momentum for the reaction was determined by comparing ratios of cross sections for excited states of ²²Na with Hauser-Feshbach predictions.     

Observation of structure in p̄p → π0π0

We present a partial wave amplitude analysis of the differential cross sections for p?p → π⁰π⁰ at 25 energies from 2.12 to 2.43 GeV. The results suggest the presence of a J^PCI^G = 2⁺⁺0⁺ resonance at 2.15 GeV. An isospin decomposition of p?p → π⁺π^- is also presented.     

Neutron and proton components of nuclear transitions in pion inelastic scattering on 26Mg

The elastic and inelastic scattering of 180 MeV positive and negative pions from ²⁶Mg has been measured. From these data the ratios of neutron and proton nuclear transition matrix elements have been determined for the first and second excited states. These ratios are compared with those obtained from electromagnetic transitions in mirror nuclei and with shell model predictions.     

Correcting the effects of background microcirculation in the measurement of arterial input functions using dynamic susceptibility contrast MRI of the brain

In dynamic susceptibility contrast MRI, the shape of the arterial input function (AIF) is commonly obtained in the near vicinity of the middle cerebral artery (MCA). However, the tissue regions where the AIF is sampled also have significant perfusion, which contributes to T(2)* changes. We investigate whether correction of this effect will introduce significant changes in the measurement of the AIF and, subsequently, the assessment of the mean transit time (MTT). Clinical dynamic susceptibility data from 13 patients with brain tumors were analyzed. Patients received either single or double doses of Magnevist followed by a saline flush through a power injector. In the correction procedure, DeltaR(2)* was sampled in a region of gray matter approximately 1-2 cm away from the MCA and then subtracted from the DeltaR(2)* sampled in the immediate vicinity of the MCA. We demonstrate that in the brain, this correction of DeltaR(2)* due to tissue perfusion leads to a narrower width of the AIF curve obtained with DeltaR(2)* (mean+/-S.D.=7.3+/-2.0 and 6.4+/-1.7 s, before and after correction, respectively, P<.001 using a two-tailed paired t-test). Furthermore, the peak of the AIF also moved to a slightly earlier time relative to the time of arrival (mean+/-S.D.=4.7+/-0.9 and 4.3+/-0.8 s, before and after correction, with P<.001). With the use of the corrected AIF, the measured MTT had increased values in areas of both gray and white matter.     

An empirical method for assessing the research relevance gap

There has been much debate on the relevance to firms of the academic research produced by business schools. However, what has not received as much attention is how the relevance of the research to businesses should be measured in a systematic and empirical way. We develop a systematic method to test for the relevance of academic research to businesses. Our method models as a vector autoregressive process the interests of the academic and practitioner communities in some new topic, as expressed by the number of articles published in the academic and the practitioner literature on that topic per calendar quarter, and then studies Granger causality between the academic and practitioner interest processes. This method can be used by academics to empirically demonstrate the impact of their intellectual contributions on practitioners and thence on the business world. We employ our approach to two relatively new and important topics, Real Options and Economic Value Added.     

A surface X-ray diffraction study of TiO2(1 1 0)(3 × 1)-S

Surface X-ray diffraction has been used to investigate the structure of TiO₂(1 1 0)(3 × 1)-S. In concert with existing STM and photoemission data it is shown that on formation of a (3 × 1)-S overlayer, sulphur adsorbs in a position bridging 6-fold titanium atoms, and all bridging oxygens are lost. Sulphur adsorption gives rise to significant restructuring of the substrate, detected as deep as the fourth layer of the selvedge. The replacement of a bridging oxygen atom with sulphur gives rise to a significant motion of 6-fold co-ordinated titanium atoms away from the adsorbate, along with a concomitant rumpling of the second substrate layer.     

Quantitative MRI: a reliable protocol for measurement of cerebral gyrification using stereology

Stereology is a sampling technique used to generate mathematically unbiased estimates of geometric properties of three-dimensional structures based on two-dimensional slices of the object. Using this method, volume and surface area estimates may be generated in a robust, reliable and time-efficient manner based on magnetic resonance (MR) image data. We present a method of determining the isoperimetric ratio, which may be used as an index of gyrification of the human cerebrum, using stereological volume and surface area estimates applied to in vivo MR image data. This parameter may be of use in identifying subtle cortical developmental malformations in diseases such as epilepsy and schizophrenia. We also conduct a series of inter- and intrarater repeatability tests based on 20 normal brains, which demonstrated the reliability and robustness of stereological techniques.     

Stability of polar oxide surfaces

The structures of the polar surfaces of ZnO are studied using ab initio calculations and surface x-ray diffraction. The experimental and theoretical relaxations are in good agreement. The polar surfaces are shown to be very stable; the cleavage energy for the (0001)-Zn and (0001;)-O surfaces is 4.0 J/m(2) comparable to 2.32 J/m(2) for the most stable nonpolar (1010) surface. The surfaces are stabilized by an electronic mechanism involving the transfer of 0.17 electrons between them. This leads to 2D metallic surface states, which has implications for the use of the material in gas sensing and catalytic applications.     

Dynamics of late-stage phase separation in crystalline solids

The dynamics of Ostwald ripening in elastically stressed crystalline solids is determined through large-scale numerical simulations. Using the insight provided by the simulations, a theory for the dynamics of late-stage phase separation in elastically anisotropic homogeneous solids is developed. Both the theory and simulations show that for the systems considered elastic stress does not alter the exponent of the temporal power law for the average particle size but does affect the amplitude of the power law in a manner that is only a function of the symmetry of the particle morphology.