A candidate super-Earth planet orbiting near the snow line of Barnard's star.

Barnard's star is a red dwarf, and has the largest proper motion (apparent motion across the sky) of all known stars. At a distance of 1.8 parsecs1, it is the closest single star to the Sun; only the three stars in the α Centauri system are closer. Barnard's star is also among the least magnetically active red dwarfs known2,3 and has an estimated age older than the Solar System. Its properties make it a prime target for planetary searches; various techniques with different sensitivity limits have been used previously, including radial-velocity imaging4-6, astrometry7,8 and direct imaging9, but all ultimately led to negative or null results. Here we combine numerous measurements from high-precision radial-velocity instruments, revealing the presence of a low-amplitude periodic signal with a period of 233 days. Independent photometric and spectroscopic monitoring, as well as an analysis of instrumental systematic effects, suggest that this signal is best explained as arising from a planetary companion. The candidate planet around Barnard's star is a cold super-Earth, with a minimum mass of 3.2 times that of Earth, orbiting near its snow line (the minimum distance from the star at which volatile compounds could condense). The combination of all radial-velocity datasets spanning 20 years of measurements additionally reveals a long-term modulation that could arise from a stellar magnetic-activity cycle or from a more distant planetary object. Because of its proximity to the Sun, the candidate planet has a maximum angular separation of 220 milliarcseconds from Barnard's star, making it an excellent target for direct imaging and astrometric observations in the future.

A giant exoplanet orbiting a very-low-mass star challenges planet formation models.

Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.

[Analysis of hospital mortality at a regional hospital]. / Análisis de la mortalidad hospitalaria en un hospital comarcal.

The hospital mortality rate in our centre es 2.34% (264 deaths from a total of 11,336 discharges between 1991 and 1993). The most frequent causes are acute myocardial infarction and cerebrovascular accidents, followed in descending order by pneumonia, chronic bronchitis, congestive heart failure, upper GI haemorrhage, GI tumours, liver cirrhosis, lung tumours and arrhythmias. Our analysis reflects a mortality pattern of a rural population with an age pyramid in which 52% of the patients are older than 45 years. The pattern also reflects the little impact of accidents on our mortality. A 87% of the deaths were older than 65 years with a male to female ratio of 1, 6 and a Swaroop index of 93% and 94% for males and females respectively.

The issue of tenure and its future.

Tenure is being questioned by the public in light of competency-based education and teacher accountability. Academic freedom is essential, but some tenured faculty compromise the quality of education students receive. Renewable contracts may hold part of the answer to this issue.

[A basic health care center. Care oriented at the community]. / Examen de salud de un área básica. Enfermería orientada a la comunidad.

Principle problems of a basic health care area (Lérida) are identified. This area, which has a patient case load of 22,244 people, was studied during the winter of 1993-94 by using information from various sources. Results indicate that the population of this community are basically young, urban, have a high cultural and social level, and are mostly employed. The principle causes of mortality are the same as in the rest of Cataluña. Diseases that cause the most working days lost to illness are: respiratory, mental and bone-joint problems. The most frequent diseases seen in the clinic are: hypertension, respiratory infections, endocrine and mental. An overall look at the state of health of these patients show that the principle problems are: tobacco use, high blood pressure, arthritis, lumbago, depression, stroke, diabetes and breast cancer.

[In vitro granulomonocytopoiesis during and after treatment of acute lymphoblastic leukemia in children]. / Granulomonocitopoyesis in vitro durante y tras el tratamiento de las leucemias linfoblásticas agudas infantiles.

We studied the effects of antileukemic chemotherapy on the granulomonocytic precursors (CFU-GM) by the in vitro bone marrow culture method. Groups of study were: 1) 17 children with acute lymphoblastic leukemia in complete remission, under maintenance chemotherapy, and 2) 10 children who had finished the treatment. Both groups had the same treatment schedule. As a control group, we studied CFU-GM from 3 children without bone marrow lesion. The results show a diminution of the granulocyte-macrophage progenitor cells in individuals under treatment, compared with the control group, after a 14 days incubation period. The group of children out of treatment shows a higher number of progenitor cells after 7 days of incubation (mature progenitors), but number decreases after 14 days (immature progenitors). Therefore, we can deduce a toxic effect, direct or indirect, but probably sustained, of the chemotherapy on the granulomonocytic precursor cells.