Compressional wave velocities are reported to pressures of 10 kb for 57 cores of rock dredged from the Mid-Atlantic Ridge at 22"N and 4" S latitude. Shear wave velocities are reported to pressures of 10 kb for 9 rock cores. The rocks studied consist of basalt, altered basalt, dolerite and chlorite-rich greenstones. Compressional wave velocities for all of the rocks, with the possible exception of the dolerites, are similar to reported velocities of the oceanic crust over the Mid-Atlantic Ridge crest. None of the rocks appear to be abundant constituents of the oceanic layer (Layer 3). Relationships between bulk density and velocity are given at pressures of 0.4, 1, 2, 6 and 10 kb. The least squares solution at 10 kb, V, = 2 . 5 3~ -0.76, falls between Birch's solutions for mean atomic weights 21 and 22. 1965-1 of R. V. Thomas Washington. The area was first examined during cruise 44 of R. V. Chain (van Andel et d. 1965; Melson & van Andel, 1966; van Andel & Bowin 1968). Melson et al. (1968) have studied in detail the petrology and chemistry of the rocks obtained on cruise 1965-1 of R. V. Thomas Washington. Locations of the dredged slopes where the samples in the present study were collected are shown in Fig. 1 of Melson et al. (1968).

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Measurements of compressional and shear wave velocities at −25 °C at pressures up to about 0.7 GPa show that the elastic properties of the high pressure polymorphs of ice are significantly different from the values for the room pressure phase. Data were obtained from ice Ih, III, V, and VI. The bulk modulus decreases slightly when ice Ih transforms to ice III while the shear modulus increases by nearly 50%. Both moduli increase substantially going from ice III to ice V. The bulk modulus of ice VI at 0.625 GPa is more than 50% greater than ice Ih and the shear modulus is more than two and one half times as large as for ice Ih. Apart from the interest in these properties for a material as important as ice, the results may be used in interpreting the internal structure and orbital histories of the icy satellites of the outer planets.

SummarySideroblastic anaemia with ringed sideroblasts and marked thrombocytosis, hereupon referred to as ringed sideroblasts with thrombocytosis (RST), is a provisional entity in the 2001 World Health Organisation classification scheme. This retrospective study identified 16 patients with RST over a 7-year period. Proposed diagnostic criteria include a sustained platelet count >500 · 10 9 /l, ‡15% ringed sideroblasts, <3% bone marrow blasts, and normal conventional cytogenetics. The median age was 76 years with eight males and eight females. With a median follow-up of 41 months, RST patients had a median overall survival of 71 months, comparable with refractory anaemia having ringed sideroblasts, but less favourable than essential thrombocythaemia. Thus far, no patients with RST are known to have died of disease-related causes. Patients with ringed sideroblasts and/or thrombocytosis need to be carefully evaluated for a variety of haematological diseases that may confer significantly different prognoses.

Histiocytic sarcoma (HS) is a rare malignancy of tissue histiocytes with a dismal prognosis. We report a 4-year-old male who developed HS during maintenance chemotherapy for precursor B-cell acute lymphoblastic leukemia (pre-B ALL). Both tumors showed identical clonal immunoglobulin and T-cell receptor gene re-arrangement patterns, as well as homozygous deletion of the CDKN2A gene encoding p16(INK4A). These data suggest a clonal relationship between the two neoplasms despite their distinct lineages. Since CDKN2A deletion predisposes to development of HS in experimental models, the cytogenetic features of the patient's pre-B ALL may have predisposed to this change in lineage.