An extreme magneto-ionic environment associated with the fast radio burst source FRB 121102.

Fast radio bursts are millisecond-duration, extragalactic radio flashes of unknown physical origin. The only known repeating fast radio burst source-FRB 121102-has been localized to a star-forming region in a dwarf galaxy at redshift 0.193 and is spatially coincident with a compact, persistent radio source. The origin of the bursts, the nature of the persistent source and the properties of the local environment are still unclear. Here we report observations of FRB 121102 that show almost 100 per cent linearly polarized emission at a very high and variable Faraday rotation measure in the source frame (varying from +1.46 × 105 radians per square metre to +1.33 × 105 radians per square metre at epochs separated by seven months) and narrow (below 30 microseconds) temporal structure. The large and variable rotation measure demonstrates that FRB 121102 is in an extreme and dynamic magneto-ionic environment, and the short durations of the bursts suggest a neutron star origin. Such large rotation measures have hitherto been observed only in the vicinities of massive black holes (larger than about 10,000 solar masses). Indeed, the properties of the persistent radio source are compatible with those of a low-luminosity, accreting massive black hole. The bursts may therefore come from a neutron star in such an environment or could be explained by other models, such as a highly magnetized wind nebula or supernova remnant surrounding a young neutron star.

Effect of the number of preceding muscle actions on subsequent peak power output.

Many sports events require participants to exert a maximal effort in the closing stages-that is, after prior fatiguing exercise. Peak and mean pedalling rate during 30 s of high-intensity cycle ergometer exercise was manipulated by altering the applied resistance or the initial exercise intensity so that the effect of three contrasting strategies on subsequent peak power output could be examined. Seven female students cycled for 30 s in one of three conditions: (1) all-out effort against an applied resistance of 7.5% of body weight (test 1); (2) at a constant pace of 55% of the peak pedal rate of test 1 against a resistance of 10.9 +/- 0.4% of body weight (test 2); (3) all-out effort against the greater resistance (test 3). A 6 s sprint against the lesser resistance was performed 3 s after each test. Total work was greater (P < 0.01) in test 3 than in test 1, while mean pedal rate was higher (P < 0.01) in test 1 (mean +/- S.E.: 10.0 +/- 0.4 rad s-1) than in tests 2 and 3 (7.2 +/- 0.4 and 7.8 +/- 0.3 rad s-1 respectively). The peak power output in the subsequent 6 s sprint was similar following tests 2 and 3 (516 +/- 37 and 534 +/- 41 W respectively), but was lower following test 1 (420 +/- 37 W) (P < 0.01, test 1 vs tests 2 and 3). These results indicate that the number of muscle actions during 30 s of fatiguing exercise may exert a considerable influence on one's ability to subsequently produce peak power output. In sports such as cycling where the same external velocity is attainable at different muscle action speeds, then appropriate gear selection during the race will impact on the rider's ability to sprint in the latter stages.

First example of Rh:-32,-46 red cell phenotype.

The red cells of a white male blood donor typed as Rh:-1, -2, -3,w4,w5,6,-17,w19,-31,-32,-34, and -46. Although the donor has no history of transfusion, his serum contains an alloantibody that is weakly reactive with most red blood cells (RBCs) tested. Only Rhnull and D-- RBCs are nonreactive. Reactivity is enhanced with ficin- or papain-treated RBCs and is unaffected by AET or DTT treatment of the RBCs. Previously described Rh:-46 RBCs have been of deletion types D--, D, and Rhnull, or Rh:32. In three multitransfused patients, the Rh46 antigen was temporarily suppressed and the phenotype eventually reverted to normal. This is the first report of RBCs of the Rh:-32,-46 phenotype that are not of a rare Rh deletion or Rhnull type. In addition, the Rh:w5,w19,-31,-34 phenotype is rarely found in whites.

Serologic investigation of fatal hemolytic anemia associated with a multiple drug history and Rh-like autoantibody.

A patient who expired during an episode of gross intravascular hemolysis had a complex medical history, including renal disease, Coombs positive anemia of unclear etiology, recent transfusion, and cholecystectomy. Drug history included 21 different medications, including penicillin, acetaminophen, procainamide, furosemide, sulindac, and tolmetin, all of which have been associated with a positive direct antiglobulin test or drug-induced hemolytic anemia. The patient had a history of recent use of three chemically similar nonsteroidal anti-inflammatory drugs: tolmetin (Tolectin), sulindac (Clinoril), and ketorolac (Toradol). Only tolmetin and furosemide (Lasix) antibodies were demonstrable in the patient's serum at the time of her final admission. The patient's serum at final admission contained panagglutinating IgG and IgM antibody with a titer of 1:80 using a pool of R1R1 and R2R2 screening cells. When tolmetin was added to the test system, the titer increased to 1:2,560. The direct antiglobulin test was 3+ (IgG and C3d,b). Eluates contained an Rh-like antibody compatible only with Rh deletion cells, and anti-tolmetin antibodies detected when the drug was added to the eluate in the presence of Rh deletion cells. Allogeneic adsorbed sera contained anti-tolmetin antibodies with a titer of 1:10 and a weakly reactive IgM antibody to furosemide. Antibodies to tolmetin and furosemide were apparent only when the drugs were added to sera or eluates, not with drug-coated cells. Because of the patient's complex medical history, it was not possible to attribute the fatal autoimmune hemolytic anemia solely to drug antibody.

Segmenting blood donors by their perceptions and awareness about blood donation.

A battery of 26 items was used to assess blood donors' perceptions on donor eligibility, blood testing, and notification procedures. An analysis of these items from a mail survey of 392 California blood donors resulted in the identification of four clusters of differing perceptions regarding four aspects of the blood collection process. Three of the four segments identified exhibited moderate to strong degrees of skepticism regarding blood donation. Implications for the continued encouragement and maintenance of donor pools are discussed.