Intensity of the Earth's magnetic field: Evidence for a Mid-Paleozoic dipole low.

The Mesozoic Dipole Low (MDL) is a period, covering at least ∼80 My, of low dipole moment that ended at the start of the Cretaceous Normal Superchron. Recent studies of Devonian age Siberian localities identified similarly low field values a few tens of million years prior to the Permo-Carboniferous Reverse Superchron (PCRS). To constrain the length and timing of this potential dipole low, this study presents paleointensity estimates from Strathmore (∼411 to 416 Ma) and Kinghorn (∼332 Ma) lava flows, United Kingdom. Both localities have been studied for paleomagnetic poles (Q values of 6 to 7), and the sites were assessed for their suitability for paleointensity from paleodirections, rock magnetic analysis, and microscopy. Thermal and microwave experiments were used to determine site mean paleointensity estimates of ∼3 to 51 µT (6 to 98 ZAm2) and 4 to 11 µT (9 to 27 ZAm2) from the Strathmore and Kinghorn localities, respectively. These, and all the sites from 200 to 500 Ma from the (updated) Paleointensity database (PINT15), were assessed using the Qualitative Paleointensity criteria (QPI). The procurement of reliable (QPI ≥ 5) weak paleointensity estimates from this and other studies indicates a period of low dipole moment (median field strength of 17 ZAm2) from 332 to 416 Ma. This "Mid-Paleozoic Dipole Low (MPDL)" bears a number of similarities to the MDL, including the substantial increase in field strength near the onset of the PCRS. The MPDL also adds support to the inverse relationship between reversal frequency and field strength and a possible ∼200-My cycle in paleomagnetic behavior relating to mantle convection.

Reasons for lower survival from non-Hodgkin's lymphoma among older patients.

Cancer-registry data for 710 patients, treated for non-Hodgkin's lymphoma (NHL) at a South Australian teaching hospital between 1977 and 2000, gave a five-year disease-specific survival of 53%, which was similar to population based estimates for Australia, the USA, and Europe. This figure reduced with age at diagnosis from 69% for patients less than 40 years at diagnosis to 30% for those aged 80 years or more. Multivariable analysis indicated that older age was predictive of lower survival (p<0.001), after adjusting for grade (Working Formulation), Ann Arbor stage,bulk disease, B symptoms (weight loss, unexplained fever, night sweats), extra-lymphatic site involvement, and diagnostic period. No other clinical variable, when included in the model, affected the risk coefficient for age. Even among patients gaining complete remission following chemotherapy, the relative risk of death from NHL was 2.11(95% CL: 1.24, 3.57) for patients aged 70 years or more at diagnosis when compared with younger patients. We conclude that older patients have lower survivals not explained by established risk factors and that this also applies to patients who achieve complete remission following chemotherapy.