Wigner surmise for Hermitian and non-Hermitian chiral random matrices.

We use the idea of a Wigner surmise to compute approximate distributions of the first eigenvalue in chiral random matrix theory, for both real and complex eigenvalues. Testing against known results for zero and maximal non-Hermiticity in the microscopic large- N limit, we find an excellent agreement valid for a small number of exact zero eigenvalues. Compact expressions are derived for real eigenvalues in the orthogonal and symplectic classes and at intermediate non-Hermiticity for the unitary and symplectic classes. Such individual Dirac eigenvalue distributions are a useful tool in lattice gauge theory, and we illustrate this by showing that our results can describe data from two-color quantum chromodynamics simulations with chemical potential in the symplectic class.

Individual complex Dirac eigenvalue distributions from random matrix theory and comparison to quenched lattice QCD with a quark chemical potential.

We analyze how individual eigenvalues of the QCD Dirac operator at nonzero quark chemical potential are distributed in the complex plane. Exact and approximate analytical results for both quenched and unquenched distributions are derived from non-Hermitian random matrix theory. When comparing these to quenched lattice QCD spectra close to the origin, excellent agreement is found for zero and nonzero topology at several values of the quark chemical potential. Our analytical results are also applicable to other physical systems in the same symmetry class.

Ultrasound tissue characterization of breast biopsy specimens: expanded study.

Tissue classification by examining sets of ultrasound parameters is an elusive goal. We report analysis of measurements of ultrasound speed, attenuation and backscatter in the range 3 to 8 MHz in breast tissues at 37 C. Statistical discriminant analysis and neural net analysis were employed. Data were acquired from 24 biopsy and 7 mastectomy specimens. Best separation of the classes normal, benign, and malignant occurred in the 18 cases where two tissue classes were present in the same specimen and parameters were corrected for within-patient mean; then 85-90% of cases in test sets were correctly classified. Most errors comprised misclassified benign cases. The neural net was comparable to discriminant analysis and slightly superior in separating normal and malignant classes.

Magnetic resonance imaging in the diagnosis of localized pigmented villonodular synovitis of the ankle: a case report.

The use of magnetic resonance imaging (MRI) in pigmented villonodular synovitis (PVS) has been well described in the literature. MRI has been used predominantly with diffuse PVS lesions. We recently had a patient with an unusual case of localized PVS of the ankle with bone and cartilage destruction. Preoperative MRI was useful in the diagnosis of localized PVS and in the planning for surgery. MRI in a patient with this lesion had not been documented previously, but should be considered whenever PVS, either diffuse or localized PVS, is suspected.

Case report 710: Symmetrical eosinophilic granuloma of the lower extremities (proven) and Erdheim-Chester disease (probable).

We present a case of symmetrical EG of the lower extremities in a 36-year-old man. Several entities are considered in the differential diagnosis. However, many of the features bear a striking resemblance to ECD, which probably coexists in this case. A link between the two entities, EG and ECD, has been suggested by others. Future experience may confirm this hypothesis.

A philosophy of limb salvage in war: use of the fixateur externe.

Over the period 1973-1983, we treated by external fixation 110 severe grade three open or complicated fractures caused in war (minimum follow-up, 7 years). We present our data analyzed according to method, location, and type of fracture. The methods we have evolved over the years are described in detail: primary wound stabilization by fixateur externe; primary radical wound excision, repeated every 48 hours as required, including excision of dead bone; delayed primary vascular soft tissue cover; delayed primary or secondary skeletal and soft tissue reconstruction as dictated by local wound conditions; prophylactic antibiotics and intensive physiotherapy to the joints and muscles of the injured limb and as rapid an ambulation of the patient as possible. The advantages and limitations of external fixation are enumerated. It is possible to avoid the complications of pin tract infection and ring necroses, but care is required to avoid refracture after removal of the apparatus, since the quality of bone healing is not always good with the use of external fixation. External fixation has greatly facilitated the various methods for achieving delayed primary vascular soft tissue cover over severe open fractures, bringing about an improved prognosis; micro-vascular techniques hold great promise for wound cover and skeletal reconstruction. Similarly, the Ilizarov method of bone osteotaxis has opened up new vistas in the treatment of bone mass loss. The latter requires a sophisticated set-up which will not be available in most war zones. In spite of the advances in treatment and in the improved results achieved by modern techniques of wound stabilization, wound soft tissue cover, and bone and soft tissue reconstructions, the temptation to try to salvage useless limbs must be resisted. Amputation, judiciously adjudged and correctly timed, remains one of the most successful forms of treatment in these severe injuries, saving the casualty from a physical and spiritual via dolorosa. Enthusiasm for surgical endeavor must be well tempered with mature judgment and realistic clinical acumen.

[Evaluation of thrombocyte retractile activity using a retractograph]. / Otsenka retraktil'noi aktivnosti trombotsitov s pomoshch'iu retraktografa.

Direct measurement of the force of clot contraction from the plasma in normal subjects and standardization of plasma platelet count, carried out with a retractograph, a newly designed apparatus, have helped assess the platelet retractile activity. Linear relationship between platelet count in the clot from the plasma and the force of the clot contraction, detected in normal subjects, allows one to do without standardization of the platelet count to a preset level when measuring the blood platelet retractile activity in patients.

[A universal measuring rectifier for a multifunctional hemocoagulation analyzer]. / Universal'nyi izmeritel'nyi preobrazovatel' mnogofunktsional'nogo analizatora gemokoaguliatsii.

For complex investigation of coagulation blood system the universal rectifier should rectify homogeneous physical values in the direct and reverse rectifying modes. High operational and metrological parameters of the rectifier are gained due to the cylinder differential electromagnetic system, which has distributed magnetic and concentrated electrical parameters. Electromagnetic excitation system allows one to correct calculation errors by the method of changing current in the excitation coil, which simplifies the system's calculations.

Idiopathic transient osteoporosis of the hip.

We have reviewed 11 patients with idiopathic transient osteoporosis of the hip; the six who were women all developed the condition during pregnancy. Both simultaneous and sequential bilateral involvement were seen, but biochemical studies were consistently normal and one synovial biopsy showed only non-specific inflammation. Radioisotope bone scans and CT scans were useful to aid diagnosis. Treatment by limiting weight-bearing relieved symptoms, and spontaneous resolution was paralleled by radiographic remineralisation, usually within a few months. One patient developed a stress fracture of the hip and other areas of transient osteoporosis. A hip involved by the condition should be protected from overloading until bone density has recovered.

[Measuring converter for elastometric medical instruments]. / Izmeritel'nyi preobrazovatel' élastometricheskikh meditsinskikh priborov.

According to thorough consideration of converting characteristics of elastometric instruments, the measurement error can be diminished by introducing in the measuring converter some regulation means for the angle of the moment of counteracting springs and an assembly to limit the radial shift of the converter moving part. Such a modification provides high operational and metrologic characteristics for elastometric medical instruments.

Arthroscopy of a dislocated hip replacement: a case report.

A 55-year-old woman had a dislocation of a total hip arthroplasty that could not be reduced by closed manipulation because of an obstructing cement fragment. The use of percutaneous arthroscopic instrumentation allowed reduction by successful manipulation of the fragment out of the joint.