Our Present Physical Knowledge of X-Rays

The Present Status of Our Knowledge of the Vitamins *

It is important that brief consideration be given to the background from which the vitamin hypothesis has evolved, not only for the information thus conveyed but also because such an account will clearly illustrate the evolution of one phase of the science of nutrition and will indicate the current tendency of thought in this field. It is, of course, difficult to determine the precise beginning...

Psychosis in Children: What is our present state of knowledge

Schizophrenic disorders in childhood comprise between 0.1 and 1% of all schizophrenic disorders before he age of 10, and 4 % before he age of 15 (Remschmidt, H., 2000). The term childhood schizophrenia was previously used to refer to all forms of childhood psychoses. This practice was an impediment to the advancement of knowledge, because marked differences exist between the types of psychosis ...

Soft X-rays from DG Tau: A physical jet model

DG Tau is a classical T Tauri star showing an unusual X-ray spectrum, best described by two thermal components with different absorption columns. The soft X-rays are less absorbed than the hard X-rays, presumably coronal, component. This rules out stellar accretion as the origin of the soft photons and requires an emission region above the circum-stellar absorption layer. We constrain the model...

Subject headings: galaxies: general—galaxies: spiral—X-rays: general—X-rays: galaxies—X-rays: ISM

We present results from the analysis of deep ROSAT HRI and PSPC observations of the spiral galaxy M81. The inferred total (0.5–2 keV band) luminosity of M81 is ∼ 3×10 ergs s, excluding the contribution from identified interlopers found within the D25 ellipse. The nucleus of the galaxy alone accounts for about 65% of this luminosity. The rest is due to 26 other X-ray sources (contributing ∼ 10%)...

Diffraction of X-rays