137 research outputs found
The Stern-Gerlach Experiment Revisited
The Stern-Gerlach-Experiment (SGE) of 1922 is a seminal benchmark experiment
of quantum physics providing evidence for several fundamental properties of
quantum systems. Based on today's knowledge we illustrate the different
benchmark results of the SGE for the development of modern quantum physics and
chemistry.
The SGE provided the first direct experimental evidence for angular momentum
quantization in the quantum world and thus also for the existence of
directional quantization of all angular momenta in the process of measurement.
It measured for the first time a ground state property of an atom, it produced
for the first time a `spin-polarized' atomic beam, it almost revealed the
electron spin. The SGE was the first fully successful molecular beam experiment
with high momentum-resolution by beam measurements in vacuum. This technique
provided a new kinematic microscope with which inner atomic or nuclear
properties could be investigated.
The original SGE is described together with early attempts by Einstein,
Ehrenfest, Heisenberg, and others to understand directional quantization in the
SGE. Heisenberg's and Einstein's proposals of an improved multi-stage SGE are
presented. The first realization of these proposals by Stern, Phipps, Frisch
and Segr\`e is described. The set-up suggested by Einstein can be considered an
anticipation of a Rabi-apparatus. Recent theoretical work is mentioned in which
the directional quantization process and possible interference effects of the
two different spin states are investigated.
In full agreement with the results of the new quantum theory directional
quantization appears as a general and universal feature of quantum
measurements. One experimental example for such directional quantization in
scattering processes is shown. Last not least, the early history of the
`almost' discovery of the electron spin in the SGE is revisited.Comment: 50pp, 17 fig
Electromagnetic properties of non-Dirac particles with rest spin 1/2
We resolve a number of questions related to an analytic description of
electromagnetic form factors of non-Dirac particles with the rest spin 1/2. We
find the general structure of a matrix antisymmetric tensor operator. We obtain
two recurrence relations for matrix elements of finite transformations of the
proper Lorentz group and explicit formulas for a certain set of such elements.
Within the theory of fields with double symmetry, we discuss writing the
components of wave vectors of particles in the form of infinite continued
fractions. We show that for (GeV/c), where is
the transferred momentum squared, electromagnetic form factors that decrease as
increases and are close to those experimentally observed in the proton
can be obtained without explicitly introducing an internal particle structure.Comment: 18 pages, 2 figure
Internally Electrodynamic Particle Model: Its Experimental Basis and Its Predictions
The internally electrodynamic (IED) particle model was derived based on
overall experimental observations, with the IED process itself being built
directly on three experimental facts, a) electric charges present with all
material particles, b) an accelerated charge generates electromagnetic waves
according to Maxwell's equations and Planck energy equation and c) source
motion produces Doppler effect. A set of well-known basic particle equations
and properties become predictable based on first principles solutions for the
IED process; several key solutions achieved are outlined, including the de
Broglie phase wave, de Broglie relations, Schr\"odinger equation, mass,
Einstein mass-energy relation, Newton's law of gravity, single particle self
interference, and electromagnetic radiation and absorption; these equations and
properties have long been broadly experimentally validated or demonstrated. A
specific solution also predicts the Doebner-Goldin equation which emerges to
represent a form of long-sought quantum wave equation including gravity. A
critical review of the key experiments is given which suggests that the IED
process underlies the basic particle equations and properties not just
sufficiently but also necessarily.Comment: Presentation at the 27th Int Colloq on Group Theo Meth in Phys, 200
Social interaction patterns, therapist responsiveness, and outcome in treatments for borderline personality disorder.
Inflexible social interaction patterns are defining features of borderline personality disorder (BPD). Specific beliefs about the self and others may be activated across interaction situations, often leading to instable relationships. It may be pivotal to address these difficulties in early treatment phases, through appropriate therapist responsiveness, which means an adaptation of therapist's activity to their client's behaviours using emerging information in the process (Stiles, 2009, Clinical Psychology: Science and Practice, 16, 86).
In this process-outcome study, responsiveness is operationalized by the motive-oriented therapeutic relationship (Caspar, 2007, Handbook of psychotherapeutic case formulations, 2nd ed., 251-289, Guilford), based on the Plan analysis case formulation. The present study assesses the interplay between social interaction problems and therapist responsiveness, explaining symptoms at discharge and the therapeutic alliance.
In total, N = 50 clients with BPD entered the study, and standard and responsive treatments were compared. Social interaction patterns were assessed by the newly developed Borderline Interaction Patterns Scale (BIPS), applied to recorded material of three sessions per therapy. Outcome was measured by general symptoms (OQ-45), borderline symptoms (BSL-23), interpersonal problems (IIP), and the therapeutic alliance (WAI).
Results suggest that in standard treatment, social interaction patterns are neither related to outcome nor the therapeutic alliance. In responsive treatment, more activation of social interaction patterns predicted better outcome on IIP and lower therapist ratings of the alliance.
The conclusions seem promising for specific effectiveness of responsive treatments in particular in the interpersonal problem area of BPD. Identifying social interaction patterns early in treatment may be a crucial pathway to change for BPD.
Responsive therapy activating social interaction patterns may be crucial for better outcome. Future research should focus on mechanisms of change in early treatment phases for BPD. New scale for assessing social interaction patterns specific to borderline personality disorder
Engolo and Capoeira. From Ethnic to Diasporic Combat Games in the Southern Atlantic
This article provides a re-examination of the main Afrocentric narrative of capoeira origins, the engolo or ‘Zebra Dance’, in light of historical primary sources and new ethnographic evidence gathered during fieldwork in south-west Angola. By examining engolo’s bodily techniques, its socio-historical context and cultural meanings, the piece emphasises its insertion into a pastoral lifestyle and highlights the relatively narrow ethnic character of the practice in Angola. This analysis and the comparison with capoeira helps us to develop certain hypotheses about the formation, migration, and re-invention of diasporic combat games between southern Angola and coastal Brazil, and more broadly, to increase our understanding of how African cultures spread across the southern Atlantic
Supersymmetric QCD corrections to and the Bernstein-Tkachov method of loop integration
The discovery of charged Higgs bosons is of particular importance, since
their existence is predicted by supersymmetry and they are absent in the
Standard Model (SM). If the charged Higgs bosons are too heavy to be produced
in pairs at future linear colliders, single production associated with a top
and a bottom quark is enhanced in parts of the parameter space. We present the
next-to-leading-order calculation in supersymmetric QCD within the minimal
supersymmetric SM (MSSM), completing a previous calculation of the SM-QCD
corrections. In addition to the usual approach to perform the loop integration
analytically, we apply a numerical approach based on the Bernstein-Tkachov
theorem. In this framework, we avoid some of the generic problems connected
with the analytical method.Comment: 14 pages, 6 figures, accepted for publication in Phys. Rev.
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