Interaction of atomic systems with X-ray free-electron lasers.

The planned construction of an X-ray free-electron laser (XFEL) will provide new opportunities for research in various areas of physics, chemistry and biology. The proposed design of the XFELs at DESY (Deutsches Elektronen-Synchrotron) and SLAC (Stanford Linear Accelerator Center) is built on the concept of a fourth-generation synchrotron source and will provide an intense pulse (I(0) approximately 10(16) W cm(-2), tau(gamma) approximately 100 fs) for photon wavelengths down to 1 A. Some guidelines for applications of these sources pertaining to atomic physics are presented here. Issues such as the onset of strong photon-field effects, multiple ionization and hollow-atom formation are analyzed. Attention is especially given to studying the interaction with rare-gas atoms, for which some numerical estimates are provided.

Further contributions to the genetic aspect of congenital sensorineural deafness in Dalmatians.

Sensorineural deafness is a common congenital disorder in Dalmatians and is genetically transmitted. Different modes of inheritance have been proposed and the objective of this study was to study these by segregation analyses using maximum likelihood procedures. Data from 33 complete Dalmatian families were collected and data from 56 single Dalmatians added. This resulted in a total of 575 dogs with 357 known phenotypes. All dogs were clinically evaluated and electrophysiologically tested with brainstem auditory evoked responses. The prevalence of deafness was 16.5% (9.4% unilaterally deaf, 7.1% bilaterally deaf). Females were 4.4% more affected than males but this difference was not significant. Within the same litter, different phenotypic expressions of deafness occurred, which suggested different expressions of the disease. In addition, two data sets were analysed: the first included normal, uni- and bilaterally deaf dogs, the second had normal and deaf Dalmatians. We found that a recessive allele at a single biallelic major locus fitted our data best, although an incomplete penetrance of the recessive homozygotes was observed.

Nerve root compression by a ganglion cyst of the lumbar anulus fibrosus. A case report.

STUDY DESIGN: A case report of a ganglion cyst rising from the anulus pulposus, causing lumbar nerve root compression. OBJECTIVES: A rare pathologic condition causing sciatica is described. The pathologic anatomy and the magnetic resonance image of the lesion is discussed. SUMMARY OF BACKGROUND DATA: A 35-year-old man was subjected to an abrupt twisting motion of the torso during a motor vehicle accident. The patient had a L5-S1 discectomy 1 year before the accident. His low back discomfort and right lower extremity pain were clearly exacerbated by the recent trauma. METHODS: Magnetic resonance imaging revealed enhancing lobulated epidural mass displacing the S1 nerve. RESULTS: Intraoperative findings were a lobulated cystic mass rising from the degenerated anulus fibrosus, determined on histologic examination to be a ganglion cyst. The patient noted significant relief of the right sciatica after surgery. CONCLUSION: The appearance and the signal intensity of the epidural mass appear to be important parameters in diagnosing the presence of a ganglion cyst of the anulus fibrous. Excision of the ganglion cyst is indicated in a patient who fails to respond to conservative treatment and where the symptoms correlate with the abnormality seen with magnetic resonance imaging.

A recurrent marker chromosome involving chromosome 1 in two mammary tumors of the dog.

An apparently identical marker chromosome resulting from a chromosome 1. translocation was found in the mammary carcinomas of two bitches. Although these karyotypic aberrations were the sole clonal aberrations detected, it was not possible to unambiguously identify the material translocated to the chromosome 1 in either animal. Our observations, however, represent the first report of a recurring marker chromosome in mammary tumors of the dog and suggest that these tumors may become an interesting model for human breast cancer.

Discography and magnetic resonance imaging in the diagnosis of lumbar disc disruption.

Four cases of patients with normal magnetic resonance (MR) studies of the lumbar spine and abnormal discography are presented to illustrate that normal lumbar disc signal intensity does not necessarily rule out disc degeneration.

[Electromyography and spinal evoked potentials in cauda equina syndrome of dogs]. / Elektromyographie und spinal evozierte Potentiale beim Cauda equina Syndrom des Hundes.

In order to investigate usefulness of electrodiagnostic methods in Cauda Equina-Compression, 26 dogs with this disease were subjected to electromyography and spinal evoked potentials. 16 normal dogs served as controls. It was found that--after stimulation of the Nn.tibialis, peronaeus, pudendus and coccygeales and recording at the lumbosacral junction--latencies and nerve-conduction velocities were largely normal. However the amplitudes were decreased and--depending on the severity of the compression--the morphology of the potentials was altered although considerable standard deviations were obtained. Electromyographically, increased spontaneous activity with fibrillations and positive sharp waves were found in the myotomes of the lumbosacral nerves. Their number increased according to the severity of the cauda equina compression and they had a centrifugal distribution pattern. Based on these results it appears indicated to perform an electromyographic exam before applying myelography. The technique of spinal evoked potentials will need more refinement and standardisation before being useful in a clinical situation.

Extreme lateral lumbar disc herniations. Clinical syndrome and computed tomography recognition.

The clinical histories of four patients with extreme lateral lumbar disc herniations are presented to demonstrate the ineffectiveness of myelography and the value of computed tomography.

Computed tomography in the postoperative lumbar spine.

A retrospective review of computed tomograms (CT) was performed in eight patients who underwent surgery for presumed reherniation of a lumbar disc. The CT scan in the three patients with surgically proven extradural scarring and no disc herniation, demonstrated distinct characteristics of perineural fibrosis which differed markedly from the uniform changes seen on the scans of the five patients with proven herniation.

Displaced intra-articular glenoid fractures treated by open reduction and internal fixation.

Displaced intra-articular glenoid fractures are extremely rare. Anatomic reduction, rigid internal fixation and early mobilization restored a full, painless range of motion in our two cases.

Atypical unstable burst fracture of the atlas. Treated by primary atlantoaxial fusion.

Burst fracture of the atlas with concomitant disruption of the transverse ligament is presented by the author because it demonstrated an atypical fracture pattern on computed tomography that has bearing on the treatment modalities. The integrity of the posterior arch was preserved, except for a fracture in the proximity of one of the lateral masses. The patient underwent a posterior C1-C2 fusion before there was evidence of healing of the posterior arch fracture. The fracture healed, and a good C1-C2 fusion was noted.