G eant 4 is a toolkit for simulating the passage of particles through matter. It includes a complete range of functionality including tracking, geometry, physics models and hits. The physics processes offered cover a comprehensive range, including electromagnetic, hadronic and optical processes, a large set of long-lived particles, materials and elements, over a wide energy range starting, in some cases, from 250 eV and extending in others to the TeV energy range. It has been designed and constructed to expose the physics models utilised, to handle complex geometries, and to enable its easy adaptation for optimal use in different sets of applications. The toolkit is the result of a worldwide collaboration of physicists and software engineers. It has been created exploiting software engineering and object-oriented technology and implemented in the C++ programming language. It has been used in applications in particle physics, nuclear physics, accelerator design, space engineering and medical physics.

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Geant4—a simulation toolkit

Geant4 - A Simulation Toolkit

* Caring for children * The origins of attachment theory * Psychoanalysis as art and science * Psychoanalysis as a natural science * Violence in the family * On knowing what you are not supposed to know and feeling what you are not supposed to feel * The role of attachment in personality development * Attachment, communication, and the therapeutic process * Developmental psychiatry comes of age

A Secure Base. Parent-Child Attachment and Healthy Human Development. New York (Basic Books) 1988.

More is different.

Feshbach resonances are the essential tool to control the interaction between atoms in ultracold quantum gases. They have found numerous experimental applications, opening up the way to important breakthroughs. This review broadly covers the phenomenon of Feshbach resonances in ultracold gases and their main applications. This includes the theoretical background and models for the description of Feshbach resonances, the experimental methods to find and characterize the resonances, a discussion of the main properties of resonances in various atomic species and mixed atomic species systems, and an overview of key experiments with atomic Bose-Einstein condensates, degenerate Fermi gases, and ultracold molecules.

Feshbach resonances in ultracold gases

I would like to draw the attention of physicists to a recent paper by James Terrell in which he does away with an old prejudice held by practically all of us. We all believed that, according to special relativity, an object in motion appears to be contracted in the direction of motion by a factor [1−(υ/c)]1/2. A passenger in a fast space ship, looking out of the window, so it seemed to us, would see spherical objects contracted to ellipsoids. This is definitely not so according to Terrell's considerations, which for the special case of a sphere were also carried out by R. Penrose. The reason is quite simple. When we see or photograph an object, we record light quanta emitted by the object when they arrive simultaneously at the retina or at the photographic film. This implies that these light quanta have not been emitted simultaneously by all points of the object. The points further away from the observer have emitted their part of the picture earlier than the closer points. Hence, if the object is in moti...

The visual appearance of rapidly moving objects

https://link.springer.com/content/pdf/10.1007%2FBF02902203.pdf

Erratum to: Hadron decay processes and the quark model

Es wird die Kopplungsverbreiterung der Spektrallinien auf rationelle Weise berechnet. Man findet, das die Kopplung wesentlich schwacher verbreitert, als nach den bisherigen Theorien angenommen wurde. Die starke Verbreiterung durch gleichartige Atome mus auf grose Stosdampfungsquerschnitte zuruckgefuhrt werden. Im zweiten Teil wird eine Methode zur Abschatzung von optischen Stosquerschnitten und eine wellenmechanische Beschreibung des Stosdampfungsvorganges gegeben.

Zur Theorie der Kopplungsbreite und der Stoßdämpfung

The Scattering of Electromagnetic Waves by Turbulent Atmospheric Fluctuations

Es wird die Selbstenergie des Elektrons im engeren formalen Anschlus an die klassische Strahlungstheorie abgeleitet, und die Selbstenergie eines Elektrons bei besetzten negativen Energiezustanden berechnet, was der Vorstellung der Diracschen „Lochertheorie“ des positiven und negativen Elektrons entspricht. Wie zu erwarten, divergiert die Selbstenergie auch in dieser Theorie, und zwar in dem gleichen Grade wie in der gewohnlichen Einelektronentheorie.

Victor F. Weisskopf

Papers

The visual appearance of rapidly moving objects

Erratum to: Hadron decay processes and the quark model

Zur Theorie der Kopplungsbreite und der Stoßdämpfung

The Scattering of Electromagnetic Waves by Turbulent Atmospheric Fluctuations

Über die Selbstenergie des Elektrons