Using Uniaxial Stress to Probe the Relationship between Competing Superconducting States in a Cuprate with Spin-stripe Order.

We report muon spin rotation and magnetic susceptibility experiments on in-plane stress effects on the static spin-stripe order and superconductivity in the cuprate system La_{2-x}Ba_{x}CuO_{4} with x=0.115. An extremely low uniaxial stress of ∼0.1 GPa induces a substantial decrease in the magnetic volume fraction and a dramatic rise in the onset of 3D superconductivity, from ∼10 to 32 K; however, the onset of at-least-2D superconductivity is much less sensitive to stress. These results show not only that large-volume-fraction spin-stripe order is anticorrelated with 3D superconducting coherence but also that these states are energetically very finely balanced. Moreover, the onset temperatures of 3D superconductivity and spin-stripe order are very similar in the large stress regime. These results strongly suggest a similar pairing mechanism for spin-stripe order and the spatially modulated 2D and uniform 3D superconducting orders, imposing an important constraint on theoretical models.

External-cavity diode laser in second-order Littrow configuration.

In this Letter, we propose and demonstrate an external-cavity diode laser in second-order Littrow configuration. This topology utilizes a low-efficiency diffraction grating to establish a high-finesse external cavity, strong optical feedback, a high polarization discrimination, and a circular TEM00 output mode. In our proof-of-concept experiment, we realized a cavity with a finesse of 1855, being, to the best of our knowledge, the highest value ever reported for a three-port-grating-coupled cavity. With optical feedback, the laser threshold of the laser diode employed was reduced by a factor of 4.

Translational, rotational, and vibrational coupling into phase in diffractively coupled optical cavities.

All-reflective optical systems are under consideration for future gravitational wave detector topologies. A key feature of these all-reflective systems is the use of Fabry-Perot cavities with diffraction gratings as input couplers; however, theory predicts and experiment has shown that translation of the grating surface across the incident laser light will introduce additional phase into the system. This translation can be induced through simple side-to-side motion of the coupler, yaw motion of the coupler around a central point (i.e., rotation about a vertical axis), and even via internal resonances (i.e., vibration) of the optical element. In this Letter we demonstrate on a prototype-scale suspended cavity that conventional cavity length-sensing techniques used to detect longitudinal changes along the cavity axis will also be sensitive to translational, rotational, and vibrational motion of the diffractive input coupler. We also experimentally verify the amplitude response and frequency dependency of the noise coupling as given by theory.

2 kW incoherent beam combining of four narrow-linewidth photonic crystal fiber amplifiers.

We report on beam combining of four narrow-linewidth fiber amplifier chains, running at different wavelengths and each delivering 500 W optical output power. The main amplifier stage consists of a large mode area photonic crystal fiber. The four output beams of the amplifier chains are spectrally (incoherent) combined using a polarization-independent dielectric reflective diffraction grating to form an output beam of 2 kW continuous-wave optical power with good beam quality (M(2)x = 2.0, M(2)y = 1.8).

Experimental demonstration of a suspended diffractively coupled optical cavity.

All-reflective optical systems are under consideration for future gravitational wave detector topologies. One approach in proposed designs is to use diffraction gratings as input couplers for Fabry-Perot cavities. We present an experimental demonstration of a fully suspended diffractively coupled cavity and investigate the use of conventional Pound-Drever-Hall length sensing and control techniques to maintain the required operating condition.

Superior bit error rate and jitter due to improved switching field distribution in exchange spring magnetic recording media.

We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media.

Development of a 'Charcot-like joint' in tophaceous gout.

We report an unusually severe case of ulcerating tophaceous gout in which inflammation due to gout, infection and excessive alcohol intake resulted in complete destruction of an ankle joint.

'Benign thoracic pain' syndrome: role of magnetic resonance imaging in the detection and localization of thoracic disc disease.

The syndrome of 'benign thoracic pain' is seen in young women who have pain and tenderness in the mid-thoracic spine radiating around the chest and aggravated by spinal movement. Ten consecutive patients with this syndrome and 15 controls were evaluated with magnetic resonance imaging (MRI). This showed thoracic intervertebral disc dehydration with no associated prolapse in 90% of the patients and 13% of the controls. We postulate that the clinical features are due to impaired shock absorption of these degenerate discs rather than direct compression of surrounding structures. MRI is non-invasive and does not use ionizing radiation; it allows direct visualization of the entire thoracic spine and cord, and accurate detection of early disc degeneration. Thus, it is the imaging modality of choice for defining the subtle intervertebral disc abnormalities that characterize the 'benign thoracic pain' syndrome.

Benign thoracic pain.

Seventy-three patients with mid-dorsal and/or unilateral chest pain seen consecutively in the rheumatology clinic by a single clinician over a three-year period were studied, after exclusion of visceral disease. The majority were young women. The pain was dull and continuous, was aggravated by coughing and sneezing and relieved by rest. There was frequently tenderness over the thoracic spine (T4-5) and an adjacent rib, and pain at extremes of thoracic spinal movement in one or two directions was invariable. Cutaneous hyperaesthesia in a radicular distribution was found in 16.4%, but there were no other neurological abnormalities. This clinical picture is probably the result of a thoracic disc prolapse, though confirmation by myelography was not thought to be ethically justified. The condition settled in most of the patients following manipulative treatment and advice on back care. No patient developed spinal cord compression. It is concluded that this is a common benign condition which deserves wider recognition.

Periostitis in secondary syphilis: a place for bone scintigraphy.

Two cases of secondary syphilis are reported with periostitis as the main presenting feature. Technetium-99m bone scintigraphy was found to be superior to radiography in both defining the extent of involvement and in picking up early lesions.

Higher cortisol content in hair among long-term unemployed individuals compared to controls.

Unemployment and financial strain are chronic stressors that have been shown to be associated with an increase in mean salivary and serum cortisol levels. Hair analysis for cortisol content is a new promising tool by which hair segmental analysis may provide a retrospective calendar of cumulative cortisol exposure over time rather than momentary assessments. Participants of this study were 31 unemployed and 28 employed individuals (46 women). Hair segmental analysis was conducted using 3-cm long segments starting with the scalp-near segment. Due to differing hair length, 52 individuals had values for the second segment and n=33 individuals had values for the third segment. Univariate analysis of variance indicated that unemployed individuals had higher cortisol content in the first (p<0.05, eta(2)=0.071) and second (p<0.05, eta(2)=0.085) hair segment (a total of 6 cm long hair representing the preceding 6 months of collection). Consistent with other data from our laboratory, there was a wash-out effect for the third segment (p<0.05 for segment 3 vs. segment 1 and 2). Unemployed individuals indicated increased levels of perceived stress and impairments in subjective well-being compared to employed individuals. These subjective measures of perceived stress and well-being were unrelated to cortisol content in hair. We conclude that hair analysis for cortisol content may be a valid method to detect differences in cumulative cortisol exposure between chronically stressed individuals and healthy controls. Due to a wash-out effect, retrospective ascertainment of cortisol exposure may be limited to the preceding 6 months of specimen collection.

A prospective study of adhesive capsulitis of the shoulder ("frozen shoulder') in a high risk population.

In order to evaluate risk factors for adhesive capsulitis of the shoulder ("frozen shoulder') a prospective study was carried out in neurosurgical patients, in whom there is a high incidence of capsulitis. Ninety-nine patients were admitted into the study, most of whom had surgical treatment for sub-arachnoid haemorrhage. Ninety-one patients (92 per cent) were followed up at six months, and of these 23 (25.3 per cent) had developed adhesive capsulitis, which was bilateral in three. Three patients developed the shoulder-hand syndrome. By comparing the patients with capsulitis at six months with those in whom no capsulitis was found, we were able to evaluate 28 possible risk factors (Appendix I). The subsequent development of adhesive capsulitis in our patients was associated with, (1) impairment of consciousness, (2) hemiparesis, (3) duration of post-operative intravenous infusion, (4) age, and (5) depressive personality. These five associations were statistically significant. Associations with phenobarbitine therapy and hysterical personality were suggested, but these did not reach statistical significance. Routine treatment with corticosteroids post-operatively did not prevent capsulitis.

Identification of Mycoplasma fermentans in synovial fluid samples from arthritis patients with inflammatory disease.

Since 1970 Mycoplasma fermentans has been suspected of being associated with rheumatoid arthritis. However, this association has been difficult to prove, and this has been our goal. The distribution of M. fermentans was studied in the synovial fluid of patients suffering from different arthritides. Samples of synovial fluid were taken from patients with well-defined disease and a clear diagnosis. After removal of the inflammatory cells and hyaluran, they were treated with proteinase K and tested by a single or fully nested PCR with primers directed against part of the two 16S rRNA genes of M. fermentans. The product was sequenced automatically, by using an ALF Express automatic sequencer, to confirm the mycoplasma species and to identify the strain since the two genes were usually found to be polymorphic. This was also true of the type strain, strain PG18. M. fermentans was detected in 23 of 26 (88%) rheumatoid arthritis patients, and four different strains were found. It was also found in 7 of 8 (88%) of the nonrheumatoid inflammatory arthritis patient group, which consisted of one patient with reactive arthritis, one patient with pauciarticular juvenile chronic arthritis, two patients with gout, two patients with ankylosing spondylitis, and two patients with psoriatic arthritis, only one of whom was infected with M. fermentans. It was not detected in any of the 10 osteoarthritis patients. M. fermentans was therefore found to be a variable and very common organism in arthritic patients with inflammatory joint exudates and may well prove to be important in the etiology of the diseases.