A glimpse of gluons through deeply virtual compton scattering on the proton

The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)-a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting the distinct energy dependences of the DVCS and BH amplitudes. In the regime where the scattering is expected to occur off a single quark, measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction.

Rosenbluth Separation of the π^{0} Electroproduction Cross Section

We present deeply virtual π^{0} electroproduction cross-section measurements at x_{B}=0.36 and three different Q^{2} values ranging from 1.5 to 2  GeV^{2}, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term σ_{LT}. Results are compared with several models based on the leading-twist approach of generalized parton distributions (GPDs). In particular, a fair agreement is obtained with models in which the scattering amplitude includes convolution terms of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. This experiment, together with previous extensive unseparated measurements, provides strong support to the exciting idea that transversity GPDs can be accessed via neutral pion electroproduction in the high-Q^{2} regime.

Recoil-proton polarization in high-energy deuteron photodisintegration with circularly polarized photons

We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance.

Combined supra-infrasellar approach for large pituitary tumors

A combined supra- infrasellar approach for the resection of very large pituitary tumors is described. We think that it is superior to either the transsphenoidal or the intracranial approaches to these difficult tumors.

Lumbar stenosis: analysis of factors affecting outcome in 81 surgical cases

The authors report on a retrospective analysis of 81 patients undergoing laminectomy for the clinico-radiological diagnosis of lumbar stenosis. One hundred and eighty-five variables were considered and a computer system was used in their evaluation. The most frequent site of involvement was at L4-5. Follow-up time ranged from 3 months to 12 years. 95% good results were obtained, and the re-operation rate was 7%. The complication rate was 11%. There was no mortality. No significant correlation between factors investigated and the outcome was found. This is in contrast to our series of lumbosacral disc protrusions in which factors such as duration of symptoms and the presence of compensation indicated a poor outcome. Results are compared with other series.

Galactorrhea after prolonged traumatic coma: case report

A 17-year-old girl suffered a traumatic acute subdural hematoma and rib fractures after a motor vehicle accident. Prolonged coma resulted, and significant galactorrhea began 4 weeks after the accident. The galactorrhea was treated successfully by the administration of 2-bromoergocryptine. The pathophysiology of this condition is discussed.