The twins and the bucket: How Einstein made gravity rather than motion relative in general relativity

In publications in 1914 and 1918, Einstein claimed that his new theory of gravity in some sense relativizes the rotation of a body with respect to the distant stars (a stripped-down version of Newton's rotating bucket experiment) and the acceleration of the traveler with respect to the stay-at-home in the twin paradox. What he showed was that phenomena seen as inertial effects in a space-time coordinate system in which the non-accelerating body is at rest can be seen as a combination of inertial and gravitational effects in a (suitably chosen) space-time coordinate system in which the accelerating body is at rest. Two different relativity principles play a role in these accounts: (a) the relativity of non-uniform motion, in the weak sense that the laws of physics are the same in the two space-time coordinate systems involved; (b) what Einstein in 1920 called the relativity of the gravitational field, the notion that there is a unified inertio-gravitational field that splits differently into inertial and gravitational components in different coordinate systems. I provide a detailed reconstruction of Einstein's rather sketchy accounts of the twins and the bucket and examine the role of these two relativity principles. I argue that we can hold on to (b) but that (a) is either false or trivial.     

Teratogenic interactions between cadmium and radiation in mice

Summary Mouse embryos were exposed to various doses of cadmium and/or X-rays on day 8 of gestation. The combined treatment exerted an antagonistic effect regarding the teratogenic action of the two agents.     

Radiation embryology

Summary Prenatal development, characterized by intensive cell proliferation, cell differentiation and cell migration, shows a high radiosensitivity. Therefore, radiation exposure of embryos and fetuses is of great concern for radiological protection and human health. Irradiation during gestation can cause death, growth disorders, malformations, functional impairment and malignant diseases in childhood. These effects are strongly dependent on the developmental stage at exposure and on the radiation dose. The first trimester of pregnancy is regarded as the period with the highest risk for malformation and cancer induction. The developing nervous system shows a special susceptibility to ionizing radiation over a long period and is therefore of great significance for risk estimation. Knowledge about radiation effects on prenatal development has been derived from animal experimentation and from the exposure of human embryos. There is evidence that doses between 1 and 10 cGy may lead to developmental anomalies and that the radiation response can be modified by additional factors.     

Ergastoplasmic granules,cytophysiological adaptation of the locusts corpora cardiaca to migratory flights?

Summary A good correlation was shown between the presence of ergastoplasmic granules in the glandular cells of the locusts corpora cardiaca and the flight activity of these insects.Research supported by grants A.T.P. No. 1831 and E.R.A. No. 620 from the Centre National de la Recherche Scientifique, French Ministry.     

Binding of 3,3',5'-triiodo-L-thyronine (rT3) to human serum proteins]

The rT3-binding and human serum proteins was directly studied with tracer doses of radioactive rT3. Polyacrylamide gel electrophoresis showed 125I-rT3 added to human serum was distributed among two proteins: albumin (carrying 57% of tracer rT3) and TBPA )22%). No binding was observed to TBG, protein binding T4.