Anharmonicity in nuclear wobbling motion

International Nuclear Information System (INIS)

Oi, M.

2007-01-01

An unexpected strong anharmonicity was observed in the wobbling spectrum in 163 Lu. In an attempt to understand what causes the deviation from the original wobbling model by Bohr and Mottelson, an analysis is presented using several different approaches, such as exact diagonalization, a semiclassical model to deal with anharmonic wobbling motion, and a microscopic method based on the self-consistent cranking calculation

New estimates of quadrupole deformation β of some nearly spherical even Mo nuclei

International Nuclear Information System (INIS)

Singh, Y.; Gupta, K.K.; Singh, M.; Bihari, Chhail; Varshney, A.K.; Gupta, D.K.

2013-01-01

The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. In recent past the sets of deformation parameters (β, γ) have been extracted from both level energies and E2 transition rates in even Xe, Ba and Ce nuclei and Hf, W, Os, Pt and Hg nuclei using rigid triaxial rotor model of Davydov – Filippov

Bohr and Dirac*

Indian Academy of Sciences (India)

IAS Admin

We present an account of the work of Niels Bohr and Paul Dirac, their interactions and personal- ities. 1. Introduction. In this essay I would like to convey to my readers some- thing about the personalities and work of Niels Bohr and Paul Dirac, juxtaposed against one another. Let me hope that the portraits I will paint of these ...

A tribute to Niels Bohr

International Nuclear Information System (INIS)

1985-01-01

This report is organized around the contribution of A. Pais, 'Niels Bohr and the development of physics', presented at CERN on the occasion of a special colloquium in the honour of Niels Bohr. It gives a broad survey of Bohr's life, the revolution in physics created by his quantum theory and his attempts to influence the peaceful development of nuclear energy. (orig.)

Probing the (empirical quantum structure embedded in the periodic table with an effective Bohr model

Directory of Open Access Journals (Sweden)

Wellington Nardin Favaro

2013-01-01

Full Text Available The atomic shell structure can be observed by inspecting the experimental periodic properties of the Periodic Table. The (quantum shell structure emerges from these properties and in this way quantum mechanics can be explicitly shown considering the (semi-quantitative periodic properties. These periodic properties can be obtained with a simple effective Bohr model. An effective Bohr model with an effective quantum defect (u was considered as a probe in order to show the quantum structure embedded in the Periodic Table. u(Z shows a quasi-smoothed dependence of Z, i.e., u(Z ≈ Z2/5 - 1.

Odd - even staggering, a result of γ - band split

International Nuclear Information System (INIS)

Singh, M.; Gupta, D.K.; Singh, Yuvraj; Gupta, K.K.; Bihari, Chhail; Sharma, Aparna; Varshney, A.K.; Varshney, Mani

2011-01-01

The structure of low - lying K = 2+ gamma band in even - even nuclei represents quadrupole vibration breaking axial symmetry in unified collective model of Bohr-Mottelson. In the group theoretical approach of the Interacting boson model (IBM) the band structure can belong to one of the three limiting symmetries of U (6) algebra viz. U (5), SU (3) and O (6), corresponding to the anharmonic vibrator, deformed rotor and γ - unstable respectively

Contribution to the projected Hartree-Fock method and microscopic theory of coupling between rotation bands

International Nuclear Information System (INIS)

Brut, F.

1982-01-01

The spectroscopy of odd-A nuclei, in the 1p and 2s-1d shells, is studied in the framework of the projected Hartree-Fock method and by the generator coordinate method. The nuclear effective interactions of Cohen and Kurath, on the one hand, and of Kuo or Preedom-Wildenthal, on the other hand, are used. The binding energies, the nuclear spectra, the static moments and the electromagnetic transitions obtained by these two approaches are compared to the same quantities given by a complete diagonalization in the shell model basis. This study of light nuclei gives some possibilities to put in order the energy levels by coupled rotational bands. In the microscopic approach, thus we find all the elements of the unified model of Bohr and Mottelson. To give evidence of such a relation, the functions of the angle β, in the integrals of the projection method of Peierls and Yoccoz, for a Slater determinant, are developed in the vicinity of the bounds β = O and β = π. The microscopic coefficients are evaluated in the Hartree-Fock approximation, using the particle-hole formalism. Calculations are made for 20 Ne and 21 Ne and the resulting microscopic coefficients are compared with the corresponding terms of the unified model of Bohr and Mottelson [fr

Bohr's Electron was Problematic for Einstein: String Theory Solved the Problem

Science.gov (United States)

Webb, William

2013-04-01

Neils Bohr's 1913 model of the hydrogen electron was problematic for Albert Einstein. Bohr's electron rotates with positive kinetic energies +K but has addition negative potential energies - 2K. The total net energy is thus always negative with value - K. Einstein's special relativity requires energies to be positive. There's a Bohr negative energy conflict with Einstein's positive energy requirement. The two men debated the problem. Both would have preferred a different electron model having only positive energies. Bohr and Einstein couldn't find such a model. But Murray Gell-Mann did! In the 1960's, Gell-Mann introduced his loop-shaped string-like electron. Now, analysis with string theory shows that the hydrogen electron is a loop of string-like material with a length equal to the circumference of the circular orbit it occupies. It rotates like a lariat around its centered proton. This loop-shape has no negative potential energies: only positive +K relativistic kinetic energies. Waves induced on loop-shaped electrons propagate their energy at a speed matching the tangential speed of rotation. With matching wave speed and only positive kinetic energies, this loop-shaped electron model is uniquely suited to be governed by the Einstein relativistic equation for total mass-energy. Its calculated photon emissions are all in excellent agreement with experimental data and, of course, in agreement with those -K calculations by Neils Bohr 100 years ago. Problem solved!

Algebraic formulation of collective models. I. The mass quadrupole collective model

International Nuclear Information System (INIS)

Rosensteel, G.; Rowe, D.J.

1979-01-01

This paper is the first in a series of three which together present a microscopic formulation of the Bohr--Mottelson (BM) collective model of the nucleus. In this article the mass quadrupole collective (MQC) model is defined and shown to be a generalization of the BM model. The MQC model eliminates the small oscillation assumption of BM and also yields the rotational and CM (3) submodels by holonomic constraints on the MQC configuration space. In addition, the MQC model is demonstrated to be an algebraic model, so that the state space of the MQC model carries an irrep of a Lie algebra of microscopic observables, the MQC algebra. An infinite class of new collective models is then given by the various inequivalent irreps of this algebra. A microscopic embedding of the BM model is achieved by decomposing the representation of the MQC algebra on many-particle state space into its irreducible components. In the second paper this decomposition is studied in detail. The third paper presents the symplectic model, which provides the realization of the collective model in the harmonic oscillator shell model

Rotations as coherent states of SU(6) quadrupole phonons in the SU(3) limit

Energy Technology Data Exchange (ETDEWEB)

Canto, L F [Rio de Janeiro Univ. (Brazil). Inst. de Fisica; Paar, V [Zagreb Univ. (Yugoslavia). Prirodoslovno Matematicki Fakultet; Rio de Janeiro Univ. (Brazil). Inst. de Fisica)

1981-06-18

Analytic expressions for the wavefunctions of the ground-state rotational band for even and odd nuclei are derived in terms of spherical quadrupole phonons truncated at N(max) phonons. For N(max) ..-->.. infinite the Bohr-Mottelson rotational states are generated as an asymptotic gaussian distribution of quadrupole phonons.

Einstein, Bohr, and Bell

Science.gov (United States)

Bellac, Michel Le

2014-11-01

The final form of quantum physics, in the particular case of wave mechanics, was established in the years 1925-1927 by Heisenberg, Schrödinger, Born and others, but the synthesis was the work of Bohr who gave an epistemological interpretation of all the technicalities built up over those years; this interpretation will be examined briefly in Chapter 10. Although Einstein acknowledged the success of quantum mechanics in atomic, molecular and solid state physics, he disagreed deeply with Bohr's interpretation. For many years, he tried to find flaws in the formulation of quantum theory as it had been more or less accepted by a large majority of physicists, but his objections were brushed away by Bohr. However, in an article published in 1935 with Podolsky and Rosen, universally known under the acronym EPR, Einstein thought he had identified a difficulty in the by then standard interpretation. Bohr's obscure, and in part beyond the point, answer showed that Einstein had hit a sensitive target. Nevertheless, until 1964, the so-called Bohr-Einstein debate stayed uniquely on a philosophical level, and it was actually forgotten by most physicists, as the few of them aware of it thought it had no practical implication. In 1964, the Northern Irish physicist John Bell realized that the assumptions contained in the EPR article could be tested experimentally. These assumptions led to inequalities, the Bell inequalities, which were in contradiction with quantum mechanical predictions: as we shall see later on, it is extremely likely that the assumptions of the EPR article are not consistent with experiment, which, on the contrary, vindicates the predictions of quantum physics. In Section 3.2, the origin of Bell's inequalities will be explained with an intuitive example, then they will be compared with the predictions of quantum theory in Section 3.3, and finally their experimental status will be reviewed in Section 3.4. The debate between Bohr and Einstein goes much beyond a

Band mixing and electric monopole contribution in 2sub(. gamma. ). -->. 2sub(g) transition in /sup 168/Er

Energy Technology Data Exchange (ETDEWEB)

Sahota, H S; Hasiza, M L; Mittal, R [Punjabi Univ., Patiala (India). Dept. of Physics

1976-06-01

The 2sub(..gamma..)..-->..2sub(g) transition in /sup 168/Er has been examined for the presence of electric monopole contribution. The experimental E0/E2 reduced transition probabilities and monopole matrix element have been found to be somewhat larger than the theoretical predictions of the Bohr-Mottelson model but the ratio rhosup(2)/X has been found to agree well with the theoretical value. The band mixing parameters have also been evaluated and found to be sizeable.

Atoms, metaphors and paradoxes Niels Bohr and the construction of a new physics

CERN Document Server

Petruccioli, Sandro

2006-01-01

This book gives a detailed study of the development and the interpretation given to Niels Bohr's Principle of Correspondence. It also describes the role that this principle played in guiding Bohr's research over the critical period from 1920 to 1927. Quantum mechanics, developed in the 1920s and 1930s by Bohr, Heisenberg, Born, Schrödinger and Dirac, represents one of the most profound turning points in science. This theory required a wholly new kind of physics in which many of the principles, concepts and models representing reality, that had formed the basis of classical physics since Galileo and Newton, had to be abandoned. This book re-examines the birth of quantum mechanics, in particular examining the development of crucial and original insights of Niels Bohr.

Paul Ehrenfest, Niels Bohr, and Albert Einstein: Colleagues and Friends

Science.gov (United States)

Klein, Martin J.

2010-09-01

In May 1918 Paul Ehrenfest received a monograph from Niels Bohr in which Bohr had used Ehrenfest's adiabatic principle as an essential assumption for understanding atomic structure. Ehrenfest responded by inviting Bohr, whom he had never met, to give a talk at a meeting in Leiden in late April 1919, which Bohr accepted; he lived with Ehrenfest, his mathematician wife Tatyana, and their young family for two weeks. Albert Einstein was unable to attend this meeting, but in October 1919 he visited his old friend Ehrenfest and his family in Leiden, where Ehrenfest told him how much he had enjoyed and profited from Bohr's visit. Einstein first met Bohr when Bohr gave a lecture in Berlin at the end of April 1920, and the two immediately proclaimed unbounded admiration for each other as physicists and as human beings. Ehrenfest hoped that he and they would meet at the Third Solvay Conference in Brussels in early April 1921, but his hope was unfulfilled. Einstein, the only physicist from Germany who was invited to it in this bitter postwar atmosphere, decided instead to accompany Chaim Weizmann on a trip to the United States to help raise money for the new Hebrew University in Jerusalem. Bohr became so overworked with the planning and construction of his new Institute for Theoretical Physics in Copenhagen that he could only draft the first part of his Solvay report and ask Ehrenfest to present it, which Ehrenfest agreed to do following the presentation of his own report. After recovering his strength, Bohr invited Ehrenfest to give a lecture in Copenhagen that fall, and Ehrenfest, battling his deep-seated self-doubts, spent three weeks in Copenhagen in December 1921 accompanied by his daughter Tanya and her future husband, the two Ehrenfests staying with the Bohrs in their apartment in Bohr's new Institute for Theoretical Physics. Immediately after leaving Copenhagen, Ehrenfest wrote to Einstein, telling him once again that Bohr was a prodigious physicist, and again

Development by Niels Bohr of the quantum theory of the atom and of the correspondence principle

International Nuclear Information System (INIS)

El'yashevich, M.A.

1985-01-01

Bohr's investigations in 1912-1923 on the quantum theory of atoms are considered. The sources of N. Bohr's works on this subject are analyzed, and the beginning of his quantum research in 1912 is described. A detailed analysis is given of N. Bohr's famous paper on the hydrogen atom theory and on the origin of spectra. The further development of Bohr's ideas on atomic structure is considered, special attention is being payed to his postulates of stationary states and of radiation transitions and to the development of the correspondence principle. It is shown how well N. Bohr understood the difficulties of the model theory and how be tried to obtain a deep understanding of quantum phenomena

The core-quasiparticle model for odd-odd nuclei and applications to candidates for gamma-ray lasers

International Nuclear Information System (INIS)

Strottman, D.D.

1988-01-01

A reliable estimate of the properties of isomers that may be viable candidates for a gamma-ray laser requires the use of the most accurate save functions possible. The majority of models that have been used to estimate the properties of isomers are applicable to only selected regions of the nuclear mass table. In particular, the Bohr-Mottelson model of odd-A and odd-odd nuclei will fail if the even-even core is not strongly deformed or if the deformations are changing strongly as a function of mass. This paper reports how the problem is overcome in a new core- quasiparticle model for odd-odd nuclei. The model introduces the pairing interaction ab initio; the odd-A states are mixtures of particle and hole states. The core may be soft towards deformation or axial asymmetry and may change rapidly as a function of mass. Thus, the model is ideally suited for application to the region of transitional nuclei such as the Te, La, and Os regions

Considerations on Bohr's, Heisenberg's and Schroedinger's philosophy

International Nuclear Information System (INIS)

Shimony, A.

1981-01-01

In denying that the words 'physical reality' are meaningful without reference to an experimental arrangement, Bohr renounces any knowledge of the 'thing-in-itself'. However, the relation of his epistemology to both idealism and positivism remains obscure. Heisenberg departs from Bohr in enunciating a metaphysical implication of quantum mechanics. Heisenberg asserts that there is an intermediate modality -potentiality- between logical possibility and existence. His attempts to explain the transition from potentiality to existence are not convincing. Schroedinger rejects Bohr's interpretation of quantum mechanics as a positivist exercise and seeks instead a realist interpretation. Nevertheless, the metaphysics of Schroedinger is fundamentally idealistic, maintaining that the material aspect of the world is composed of the same elements as mind, but in a different order [fr

Creation and development of Bohr's theory (on the 90th anniversary of the Bohr theory of the atom)

International Nuclear Information System (INIS)

Milant'ev, Vladimir P

2004-01-01

The history of the creation and development of Bohr's atomic theory is discussed. Even now, with a consistent quantum theory available, Bohr's theory is not simply the property of history, of methodological interest only. To this day, the ideas of the theory not only provide an excellent introduction to atomic physics, but are also used successfully in treating atomic Rydberg states, exotic atoms, etc. (from the history of physics)

Niels Bohr and the philosophy of physics twenty-first century perspectives

CERN Document Server

Folse, Henry

2017-01-01

Niels Bohr and Philosophy of Physics: Twenty-First Century Perspectives examines the philosophical views, influences and legacy of the Nobel Prize physicist and philosophical spokesman of the quantum revolution, Niels Bohr. The sixteen contributions in this collection by some of the best contemporary philosophers and physicists writing on Bohr's philosophy today all carefully distinguish his subtle and unique interpretation of quantum mechanics from views often imputed to him under the banner of the “Copenhagen Interpretation.” With respect to philosophical influences on Bohr's outlook, the contributors analyse prominent similarities between his viewpoint and Kantian ways of thinking, the views of the Danish philosopher Harald Høffding, and themes characteristic of American pragmatism. In recognizing the importance of Bohr's epistemological naturalism they examine his defence of the indispensability of classical concepts from a variety of different perspectives. This collection shows us that Bohr's int...

Bohr's Creation of his Quantum Atom

Science.gov (United States)

Heilbron, John

2013-04-01

Fresh letters throw new light on the content and state of Bohr's mind before and during his creation of the quantum atom. His mental furniture then included the atomic models of the English school, the quantum puzzles of Continental theorists, and the results of his own studies of the electron theory of metals. It also included the poetry of Goethe, plays of Ibsen and Shakespeare, novels of Dickens, and rhapsodies of Kierkegaard and Carlyle. The mind that held these diverse ingredients together oscillated between enthusiasm and dejection during the year in which Bohr took up the problem of atomic structure. He spent most of that year in England, which separated him for extended periods from his close-knit family and friends. Correspondence with his fianc'ee, Margrethe Nørlund, soon to be published, reports his ups and downs as he adjusted to J.J. Thomson, Ernest Rutherford, the English language, and the uneven course of his work. In helping to smooth out his moods, Margrethe played an important and perhaps an enabling role in his creative process.

Address at the opening session of the Niels Bohr Symposium

International Nuclear Information System (INIS)

Mayor, F.

1998-01-01

In his address at the opening session of the Niels Bohr Symposium organized jointly by UNESCO and the Niels Bohr Institute in Copenhagen in May 1998 in order to examine the latest developments in key fields of physics, the Director General of UNESCO presented the scientific work and the spirit of Niels Bohr, emphasizing the impact of his discoveries for new openings in science and in society in general

Niels Bohr - his life and scientific achievements

International Nuclear Information System (INIS)

Kailas, S.

2013-01-01

Niels Bohr, a Nobel laureate and a celebrated scientist of the 20th century is remembered for his lasting contributions to atomic and nuclear physics. His pioneering works on Energy loss by charged particles, the structure of the atom, the compound nucleus model and the mechanism of nuclear fission are indeed remarkable. In this article a brief account of his life and scientific achievements is provided. (author)

Microscopic approach to nuclear anharmonicities

International Nuclear Information System (INIS)

Matsuo, Masayuki; Shimizu, Yoshifumi; Matsuyanagi, Kenichi

1985-01-01

Present status of microscopic study of nuclear anharmonicity phenomena is reviewed from the viewpoint of the time-dependent Hartree-Bogoliubov approach. Both classical- and quantum-mechanical aspects of this approach are discussed. The Bohr-Mottelson-type collective Hamiltonian for anharmonic gamma vibrations is microscopically derived by means of the self-consistent-collective-coordinate method, and applied to the problem of two-phonon states of 168 Er. (orig.)

The coupling one quasi-particle to a Bohr core

International Nuclear Information System (INIS)

Lewenkopf, C.H.

1988-01-01

Odd nuclei are studied coupling one quasi-particle to a Bohr's core, solved by Kumar Baranger's method. Calculations are performed for energies and transition rates for the following isotopes: 133 Xe, 183 W, 99 Tc and 101 Rh. Limitations of the model are discussed. (author) [pt

Spectrum of hydrogen atom, Niels Bohr and their impact on contemporary science: a glimpse of modern spectroscopy

International Nuclear Information System (INIS)

Sastry, M.D.

2013-01-01

This contribution reviews developments in the atomic spectroscopy subsequent to Bohr's model. This follows a brief description of Bohr's model of hydrogen atom that accounts for sharp line spectra of hydrogen atom. The developments include the effects of electron and nuclear spins, spectroscopy of multi electron atom which involve electron-electron repulsion and different angular momentum coupling schemes. More recently, Bohr's atom model has found application to processes at nano dimensions of semiconducting materials. It has now become possible to create a hydrogen-like atom, an exciton, with its size comparable or even more than that of the particle it self. This brings in extra quantization and has profound effects on the motion of the particles involved viz electron and hole. (author)

Two-body potentials in the collective model

International Nuclear Information System (INIS)

Draayer, J.P.; Rosensteel, G.; Arizona State Univ., Tempe

1982-01-01

The question, 'How well can a 1+2-body shell-model interaction represent a many-body potential.', is addressed by optimally expanding the (1+2+3)-body potential β 3 cos 3γ and the (1+2+3+4)-body potential β 4 of the Bohr-Mottelson collective model in terms of (1+2)-body operators. It is found that the correlation of β 4 with its approximation is greater than 97% throughout the sd shell. Although β 3 cos 3γ is also well approximated in the first half of the sd shell where it has more than 80% correlation with its approximation, the correlation drops abruptly at 28 Si to 50% and remains low in the second half of the shell. The approximations are primarily sums of the various components of the quadrupole-quadrupole interaction connecting different major oscillator shells. The results suggest that axially-symmetric deformation can be represented by simple (1+2)-body operators, whereas asymmetric shapes require non-simple 3-body terms. (orig.)

Niels Bohr collected works, volume 9: Nuclear physics (1929-1952)

International Nuclear Information System (INIS)

Peierls, R.

1985-01-01

This volume deals with Bohr's work on nuclear physics which began in the pre-1932 days with his thinking deeply, but inconclusively about the seeming contradictions then presented by the evidence about the nucleus. In 1936 Bohr recognized and described the insights provided by neutron scattering experiments and the excitement of this new understanding and its extension and consolidation occupied much of the subsequent years. In 1939 he was again first in understanding the essential features of the newly discovered phenomenon of fission, applying successfully the point of view of nuclear reactions which he had developed over the past three years. Later, in 1949-50, he was impressed by the success of the nuclear shell model, which on the face of it seemed hard to reconcile with the picture of the closely interacting nucleons which he had pioneered in 1936 and he put much effort into clarifying this paradox. As in earlier volumes the published papers are supported by appropriate selections from unpublished notes and drafts, and by relevant correspondence. CONTENTS: Foreword. Part I: Papers and Manuscripts Related to Nuclear Physics. Part II: Selected Correspondence (1929-1949). Inventory of Relevant Manuscripts in the Niels Bohr Archive. Index

Low-energy coupling of individual and collective degrees of freedom: a general microscopic approach

International Nuclear Information System (INIS)

Quentin, P.; Meyer, M.

1988-01-01

A general microscopic approach of low energy coupling of individual and collective degrees of freedom is presented. The ingredients of a Bohr-Mottelson unified model description are determined consistently from the Skyrme SIII effective interaction, through the adiabatic limit of the time-dependent Hartree-Fock-Bogoliubov approximation. Three specific aspects will be mostly developed: i) the effect of pairing correlations on adiabatic mass parameters and collective dynamics; ii) a consistent coupling of collective and individual degrees of freedom to describe odd nuclei; iii) a study of spectroscopic data in odd-odd nuclei as a test of effective nucleon-nucleon interactions. (author)

Bohr orbit theory revisited

International Nuclear Information System (INIS)

Harcourt, R.D.

1987-01-01

Bohr orbit theory is used to calculate energies for the 1S, 2P, 3D, 4F and 5G states of the helium muonic atom, when the muon is excited. These energies are close to those which have been calculated variationally by Huang (1977, Phys. Rev. A 15 1832-8). (author)

De novo nonsense mutations in ASXL1 cause Bohring-Opitz syndrome

DEFF Research Database (Denmark)

Hoischen, Alexander; van Bon, Bregje W M; Rodríguez-Santiago, Benjamín

2011-01-01

Bohring-Opitz syndrome is characterized by severe intellectual disability, distinctive facial features and multiple congenital malformations. We sequenced the exomes of three individuals with Bohring-Opitz syndrome and in each identified heterozygous de novo nonsense mutations in ASXL1, which...... is required for maintenance of both activation and silencing of Hox genes. In total, 7 out of 13 subjects with a Bohring-Opitz phenotype had de novo ASXL1 mutations, suggesting that the syndrome is genetically heterogeneous....

The splitting of giant multipole states of deformed nuclei

International Nuclear Information System (INIS)

Suzuki, T.; Rowe, D.J.

1977-01-01

A vibrating potential model is applied to deformed nuclei with a deformed harmonic oscillator potential in order to discuss the splitting of isoscalar giant quadrupole states. Eigenfrequencies of the collective states are estimated to be √2ω(1 - delta/3), √2ω(1 - delta/6) and √2ω(1 + delta/3) for K = 0 + ,1 + and 2 + modes, respectively. The splitting of isovector dipole and isovector quadrupole states is also studied according to a schematic model as proposed by Bohr and Mottelson. It is shown that isovector dipole states are split, as in a hydrodynamic model, while isovector quadrupole states with the same scaling factors as those of isocalar quadrupole modes. (Auth.)

Large boson number IBM calculations and their relationship to the Bohr model

International Nuclear Information System (INIS)

Thiamova, G.; Rowe, D.J.

2009-01-01

Recently, the SO(5) Clebsch-Gordan (CG) coefficients up to the seniority v max =40 were computed in floating point arithmetic (T.A. Welsh, unpublished (2008)); and, in exact arithmetic, as square roots of rational numbers (M.A. Caprio et al., to be published in Comput. Phys. Commun.). It is shown in this paper that extending the QQQ model calculations set up in the work by D.J. Rowe and G. Thiamova (Nucl. Phys. A 760, 59 (2005)) to N=v max =40 is sufficient to obtain the IBM results converged to its Bohr contraction limit. This will be done by comparing some important matrix elements in both models, by looking at the seniority decomposition of low-lying states and at the behavior of the energy and B(E2) transition strengths ratios with increasing seniority. (orig.)

Reconstructing Bohr's Reply to EPR in Algebraic Quantum Theory

Science.gov (United States)

Ozawa, Masanao; Kitajima, Yuichiro

2012-04-01

Halvorson and Clifton have given a mathematical reconstruction of Bohr's reply to Einstein, Podolsky and Rosen (EPR), and argued that this reply is dictated by the two requirements of classicality and objectivity for the description of experimental data, by proving consistency between their objectivity requirement and a contextualized version of the EPR reality criterion which had been introduced by Howard in his earlier analysis of Bohr's reply. In the present paper, we generalize the above consistency theorem, with a rather elementary proof, to a general formulation of EPR states applicable to both non-relativistic quantum mechanics and algebraic quantum field theory; and we clarify the elements of reality in EPR states in terms of Bohr's requirements of classicality and objectivity, in a general formulation of algebraic quantum theory.

The Niels Bohr Archive is Placing Collections on its Website

DEFF Research Database (Denmark)

Aaserud, Finn

2010-01-01

this supplement, the documents of which we hope to make available on our website by 2013, the centennial for Bohr's model of the nuclear atom. We have found the task of digitizing our collections generally complex, sometimes frustrating, and in the end satisfying. At this stage it is particularly important...

De novo nonsense mutations in ASXL1 cause Bohring-Opitz syndrome

NARCIS (Netherlands)

Hoischen, Alexander; van Bon, Bregje W. M.; Rodríguez-Santiago, Benjamín; Gilissen, Christian; Vissers, Lisenka E. L. M.; de Vries, Petra; Janssen, Irene; van Lier, Bart; Hastings, Rob; Smithson, Sarah F.; Newbury-Ecob, Ruth; Kjaergaard, Susanne; Goodship, Judith; McGowan, Ruth; Bartholdi, Deborah; Rauch, Anita; Peippo, Maarit; Cobben, Jan M.; Wieczorek, Dagmar; Gillessen-Kaesbach, Gabriele; Veltman, Joris A.; Brunner, Han G.; de Vries, Bert B. B. A.

2011-01-01

Bohring-Opitz syndrome is characterized by severe intellectual disability, distinctive facial features and multiple congenital malformations. We sequenced the exomes of three individuals with Bohring-Opitz syndrome and in each identified heterozygous de novo nonsense mutations in ASXL1, which is

A new model for nuclear matter

International Nuclear Information System (INIS)

Skyrme, T.H.R.

1994-01-01

The different values obtained for nuclear radii from electromagnetic interactions as compared with specifically nuclear interactions suggested a model of nuclear matter in which the meson field is supposed to condense into an incompressible fluid and the nucleonic sources are confined to its interior by a strong interaction between the sources and the fluid as a whole. The sources are also coupled to spin and charge fluctuations in the fluid, whose exchange leads to further internucleonic forces. It is necessary to postulate that the fluid have a comparatively low density; as a result rotational levels of the fluid are high, leading to a small probability of exchange of angular momentum (and charge coupled to it) with the sources. The values of the anomalous electrical interactions of nucleons deduced are in rough agreement with the facts. The nuclear structure indicated is a shell model embedded in the mesic fluid whose oscillations, strongly coupled to the nucleons, give rise to the collective features of nuclear structure as in the theory of Bohr and Mottelson. It is suggested that this picture of the mesic field may indicate where to look for solutions of the meson field equations. (author). 9 refs

Effectiveness of an Asynchronous Online Module on University Students' Understanding of the Bohr Model of the Hydrogen Atom

Science.gov (United States)

Farina, William J., Jr.; Bodzin, Alec M.

2018-01-01

Web-based learning is a growing field in education, yet empirical research into the design of high quality Web-based university science instruction is scarce. A one-week asynchronous online module on the Bohr Model of the atom was developed and implemented guided by the knowledge integration framework. The unit design aligned with three identified…

The field treatment of the nuclear spectrum. Historical foundation and two contributions to its ensuing development

International Nuclear Information System (INIS)

Bes, Daniel R

2016-01-01

The highlights of the model which was developed during the 1950s at the Niels Bohr Institute, Copenhagen, under the leadership of Aage Bohr and Ben Mottelson, are described in this contribution. Subsequently, it is shown that the field concept—the fundamental tool of the unified model—is not only an intelligent guess to describe the difficult many-body nuclear system. By means of a systematic expansion of field-coupling effects, the nuclear field theory (NFT) accounts for the overcompleteness of the initial product basis and the overlooking of the Pauli principle acting between constituents of the basis. Eventually it leads to the exact solution of the nuclear many-body problem. The description in terms of fields involves another problem if the field violates a symmetry inherent to the initial problem. The solution is borrowed from the BRST treatments of gauge systems, in which the lost symmetry is replaced by a more powerful one. (invited comment)

Nil Bohr-sets and almost automorphy of higher order

CERN Document Server

Huang, Wen; Ye, Xiangdong

2016-01-01

Two closely related topics, higher order Bohr sets and higher order almost automorphy, are investigated in this paper. Both of them are related to nilsystems. In the first part, the problem which can be viewed as the higher order version of an old question concerning Bohr sets is studied: for any d\\in \\mathbb{N} does the collection of \\{n\\in \\mathbb{Z}: S\\cap (S-n)\\cap\\ldots\\cap (S-dn)\

Christian Bohr og De syv små Djaevle: Et laerestykke i 4 akter om iltdiffusionsstriden mellem Christian Bohr og August Krogh

DEFF Research Database (Denmark)

Gjedde, Albert

2004-01-01

The author explores novel lessons emerging from the oxygen diffusion controversy between Christian Bohr on one side and August and Marie Krogh on the other. THe controversy found its emphatic expression in August and Marie Krogh's "Seven Little Devils", a series of papers published back-to-back i......The author explores novel lessons emerging from the oxygen diffusion controversy between Christian Bohr on one side and August and Marie Krogh on the other. THe controversy found its emphatic expression in August and Marie Krogh's "Seven Little Devils", a series of papers published back...

Niels Bohr and the Atomic Structure

Indian Academy of Sciences (India)

IAS Admin

principle with the restriction that no more than two electrons occupy a given ... displacement laws. Early in his ... The only difference between them is their atomic weight. F Soddy ... validity, Bohr took his theory to Rutherford. Unfortunately,.

Correction of the exciton Bohr radius in monolayer transition metal dichalcogenides

Science.gov (United States)

Li, Run-Ze; Dong, Xi-Ying; Li, Zhi-Qing; Wang, Zi-Wu

2018-07-01

We theoretically investigate the correction of exciton Bohr radius in monolayer transition metal dichalcogenides (TMDCs) on different polar substrates arising from the exciton-optical phonon coupling, in which both the intrinsic longitudinal optical phonon and surface optical phonon modes couple with the exciton are taken into account. We find that the exciton Bohr radius is enlarged markedly due to these coupling. Moreover, it can be changed on a large scale by modulating the polarizability of polar substrate and the internal distance between the monolayer TMDCs and polar substrate. Theoretical result provides a potential explanation for the variation of the exciton Bohr radius in experimental measurement.

Bohr's Philosophy of Wave–Particle Complementarity

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 10. Bohr's Philosophy of Wave–Particle Complementarity. Dipankar Home. General Article Volume 18 Issue 10 October 2013 pp 905-916. Fulltext. Click here to view fulltext PDF. Permanent link:

Bohr effect of human hemoglobin: Separation of tertiary and quaternary contributions based on the Wyman equation.

Science.gov (United States)

Okonjo, Kehinde Onwochei

2017-09-01

As a prelude to separating tertiary from quaternary structure contributions to the Bohr effect, we employed the Wyman equation to analyze Bohr data for human hemoglobin to which 2,3-bisphosphoglycerate, 2,3-BPG, is bound. Changes in the pK a s of the histidine Bohr groups result in a net reduction of their contributions to the Bohr effect at pH 7.4 compared to their contributions in stripped hemoglobin. The non-histidine 2,3-BPG binding groups - the β-chain terminal amino group and Lys82β - make negative and positive contributions, respectively, to the Bohr effect. The final result is that the Bohr effect at physiological pH is higher for 2,3-BPG bound compared to stripped hemoglobin. Contributions linked to His2β, His77β and His143β enable us to separate tertiary from quaternary Bohr contributions in stripped and in 2,3-BPG bound hemoglobin. Both contributions serve to make the Bohr effect for 2,3-BPG bound hemoglobin higher than for stripped hemoglobin at physiological pH. Copyright © 2017 Elsevier B.V. All rights reserved.

EPR, kvantemekanik og Bohr

OpenAIRE

Nielsen, Morten Klockmann

2007-01-01

Dette projekt omhandler området hvor filosofi og fysik smelter sammen. Kvantemekanikkens tilblivelse fik en hård medfart hvilket diskussionerne mellem især Albert Einstein og Niels Bohr vidner om. De var hovedpersoner i striden om hvordan kvantemekanikken skulle fortolkes, og diskussionen kulminerede i 1935 hvor Einstein sammen med kollegerne Podolsky og Rosen offentliggjorde en artikel med titlen “Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?” (EPR-artiklen)....

The BOHR Effect before Perutz

Science.gov (United States)

Brunori, Maurizio

2012-01-01

Before the outbreak of World War II, Jeffries Wyman postulated that the "Bohr effect" in hemoglobin demanded the oxygen linked dissociation of the imidazole of two histidines of the polypeptide. This proposal emerged from a rigorous analysis of the acid-base titration curves of oxy- and deoxy-hemoglobin, at a time when the information on the…

Love, literature and the quantum atom Niels Bohr's 1913 trilogy revisited

CERN Document Server

Aaserud, Finn

2013-01-01

Niels Bohr ranks with Einstein among the physicists of the 20th century. He rose to this status through his invention of the quantum theory of the atom and his leadership in its defense and development. He also ranks with Einstein in his humanism and his sense of responsibility to his science and the society that enabled him to create it. Our book presents unpublished excerpts from extensive correspondence between Bohr and his immediate family, and uses it to describe and analyze the psychological and cultural background to his invention. The book also contains a reprinting of the three papers of 1913 - the "Trilogy" - in which Bohr worked out the provisional basis of a quantum theory of the atom.

Reflections on collectivity

International Nuclear Information System (INIS)

Feshbach, H.

1983-01-01

Comments are made on papers presented to the International School of Nuclear Physics, Erice (1982) concerning collective bands and collectivity in nuclei. The importance of these collective modes of motion, the role of the Bohr-Mottelson model and the Interacting Boson Models (IBM-1 and IBM-2), and experimental evidence presented by a number of workers, are examined. The extensions of the models to take into account additional degrees of freedom both collective and non-collective, the discovery of new collective modes such as those corresponding to tri-axial shapes, and the possible existence of additional symmetries reported at the meeting, are discussed. Finally the importance is examined of relating the phenomenological models to a more fundamental underlying theory, which has been taken to be the nuclear shell model. (U.K.)

Complementarity beyond physics Niels Bohr's parallels

CERN Document Server

Bala, Arun

2017-01-01

In this study Arun Bala examines the implications that Niels Bohr’s principle of complementarity holds for fields beyond physics. Bohr, one of the founding figures of modern quantum physics, argued that the principle of complementarity he proposed for understanding atomic processes has parallels in psychology, biology, and social science, as well as in Buddhist and Taoist thought. But Bohr failed to offer any explanation for why complementarity might extend beyond physics, and his claims have been widely rejected by scientists as empty speculation. Scientific scepticism has only been reinforced by the naïve enthusiasm of postmodern relativists and New Age intuitionists, who seize upon Bohr’s ideas to justify anti-realist and mystical positions. Arun Bala offers a detailed defence of Bohr’s claim that complementarity has far-reaching implications for the biological and social sciences, as well as for comparative philosophies of science, by explaining Bohr’s parallels as responses to the omnipresence...

Bohr model description of the critical point for the first order shape phase transition

Science.gov (United States)

Budaca, R.; Buganu, P.; Budaca, A. I.

2018-01-01

The critical point of the shape phase transition between spherical and axially deformed nuclei is described by a collective Bohr Hamiltonian with a sextic potential having simultaneous spherical and deformed minima of the same depth. The particular choice of the potential as well as the scaled and decoupled nature of the total Hamiltonian leads to a model with a single free parameter connected to the height of the barrier which separates the two minima. The solutions are found through the diagonalization in a basis of Bessel functions. The basis is optimized for each value of the free parameter by means of a boundary deformation which assures the convergence of the solutions for a fixed basis dimension. Analyzing the spectral properties of the model, as a function of the barrier height, revealed instances with shape coexisting features which are considered for detailed numerical applications.

Niels Bohr. Physicist and philospher of the atomic era

International Nuclear Information System (INIS)

Fischer, Ernst Peter

2012-01-01

The physicist and Nobel-prize carrier Niels Bohr (1885-1962) changed by his research our view to the world. By his atomic model for the first time the stability of matter could be explained, but simultaneously the atomic physics and nuclear technique based on this made our world so dangerous as never before. In an impressive portrait Ernst Peter Fischer describes the life and action of this fascinating man, his great physical finding, as well as his political engagement.

Bohr model description of the critical point for the first order shape phase transition

Directory of Open Access Journals (Sweden)

R. Budaca

2018-01-01

Full Text Available The critical point of the shape phase transition between spherical and axially deformed nuclei is described by a collective Bohr Hamiltonian with a sextic potential having simultaneous spherical and deformed minima of the same depth. The particular choice of the potential as well as the scaled and decoupled nature of the total Hamiltonian leads to a model with a single free parameter connected to the height of the barrier which separates the two minima. The solutions are found through the diagonalization in a basis of Bessel functions. The basis is optimized for each value of the free parameter by means of a boundary deformation which assures the convergence of the solutions for a fixed basis dimension. Analyzing the spectral properties of the model, as a function of the barrier height, revealed instances with shape coexisting features which are considered for detailed numerical applications.

Bohr--Sommerfeld Lagrangians of moduli spaces of Higgs bundles

DEFF Research Database (Denmark)

Biswas, Indranil; Gammelgaard, Niels Leth; Logares, Marina

Let $X$ be a compact connected Riemann surface of genus at least two. Let $M_H(r,d)$ denote the moduli space of semistable Higgs bundles on $X$ of rank $r$ and degree $d$. We prove that the compact complex Bohr-Sommerfeld Lagrangians of $M_H(r,d)$ are precisely the irreducible components of the n......Let $X$ be a compact connected Riemann surface of genus at least two. Let $M_H(r,d)$ denote the moduli space of semistable Higgs bundles on $X$ of rank $r$ and degree $d$. We prove that the compact complex Bohr-Sommerfeld Lagrangians of $M_H(r,d)$ are precisely the irreducible components...

Collective excitations at low energy: microscopic study of rotation, vibration and their coupling in even-even nuclei; Excitations collectives a basse energie: Etude microscopique de la rotation, de la vibration et de leur couplage dans les noyaux pair-pairs

Energy Technology Data Exchange (ETDEWEB)

Deloncle, I.

1989-10-23

In this study we have built the quadrupolar collective Bohr Hamiltonian in a purely microscopic way by using an approximation of the time-dependant Hartree-Fock adiabatic approach. The purpose of this work was to obtain a quantitative description of the collective properties in the low energy range of intermediate and heavy nuclei by using a 2-body effective interaction of Skyrme-type. We consider low energy processes as dynamic regimes in which the collective movement is adiabatic when compared with modes associated to individual freedom. In the N-body solution we propose, we have assumed that: -) a mean field exists at any moment, -) some collective variables exist whose temporal variations include all the dynamics, and -) the collective movement is adiabatic. This work is a microscopic formulation and an efficient approach to resolve the Bohr and Mottelson unified model. Low energy spectra have been computed for 4 nuclei: Ge{sup 74}, Se{sup 76}, Cd{sup 110} and Pt{sup 186} and they agree well with experimental data.

Il danese tranquillo Niels Bohr, un fisico e il suo tempo, 1885-1962

CERN Document Server

Pais, Abraham

1993-01-01

Niels Bohr è una figura centrale nella fisica del Novecento, padre fondatore della teoria atomica e della meccanica quantistica. La storia della sua vita, ricca e piena anche sul piano affettivo e personale, non può dunque ridursi a un resoconto dei suoi successi scientifici e Pais, allievo e poi amico di Bohr, ne è perfettamente consapevole. Il libro si sviluppa su vari piani: capitoli strettamente biografici o storico-scientifici si alternano a discussioni sulle idee di Bohr in campo politico e filosofico, sui suoi rapporti con Einstein, sul suo ruolo nei drammatici anni della guerra e su molti altri aspetti della vicenda umana.

From correspondence to complementarity: The emergence of Bohr's Copenhagen interpretation of quantum mechanics

Science.gov (United States)

Tanona, Scott Daniel

I develop a new analysis of Niels Bohr's Copenhagen interpretation of quantum mechanics by examining the development of his views from his earlier use of the correspondence principle in the so-called 'old quantum theory' to his articulation of the idea of complementarity in the context of the novel mathematical formalism of quantum mechanics. I argue that Bohr was motivated not by controversial and perhaps dispensable epistemological ideas---positivism or neo-Kantianism, for example---but by his own unique perspective on the difficulties of creating a new working physics of the internal structure of the atom. Bohr's use of the correspondence principle in the old quantum theory was associated with an empirical methodology that used this principle as an epistemological bridge to connect empirical phenomena with quantum models. The application of the correspondence principle required that one determine the validity of the idealizations and approximations necessary for the judicious use of classical physics within quantum theory. Bohr's interpretation of the new quantum mechanics then focused on the largely unexamined ways in which the developing abstract mathematical formalism is given empirical content by precisely this process of approximation. Significant consistency between his later interpretive framework and his forms of argument with the correspondence principle indicate that complementarity is best understood as a relationship among the various approximations and idealizations that must be made when one connects otherwise meaningless quantum mechanical symbols to empirical situations or 'experimental arrangements' described using concepts from classical physics. We discover that this relationship is unavoidable not through any sort of a priori analysis of the priority of classical concepts, but because quantum mechanics incorporates the correspondence approach in the way in which it represents quantum properties with matrices of transition probabilities, the

Research on convergence of nuclear rotational spectra formula

International Nuclear Information System (INIS)

Chen Yongjing; Xu Fuxin

2001-01-01

The superdeformed bands in the A-190 region are systematically analyzed using four-parameter rotational spectra formula of Bohr-Mottelson's I(I + 1) expansion. The convergence of two-parameter ab formula is compared with that of three-parameter abc formula by four parameters A, B, C, D. The result shows that the four-parameter value relation does not support the theoretically expected values of ab and abc formulas, but comparatively the four-parameter value relation agrees with the theoretically expected value of ab formula better than that of abc formula

Noninvasive measurement of mean alveolar carbon dioxide tension and Bohr's dead space during tidal breathing.

Science.gov (United States)

Koulouris, N G; Latsi, P; Dimitroulis, J; Jordanoglou, B; Gaga, M; Jordanoglou, J

2001-06-01

The lack of methodology for measuring the alveolar carbon dioxide tension (PA,CO2) has forced investigators to make several assumptions, such as that PA,CO2 is equal to end-tidal (PET,CO2) and arterial CO2 tension (Pa,CO2). The present study measured the mean PA,CO2 and Bohr's dead space ratio (Bohr's dead space/tidal volume (VD,Bohr/VT)) during tidal breathing. The method used is a new, simple and noninvasive technique, based on the analysis of the expired CO2 volume per breath (VCO2) versus the exhaled VT. This curve was analysed in 21 normal, healthy subjects and 35 chronic obstructive pulmonary disease (COPD) patients breathing tidally through a mouthpiece apparatus in the sitting position. It is shown that: 1) PA,CO2 is similar to Pa,CO2 in normal subjects, whilst it is significantly lower than Pa,CO2 in COPD patients; 2) PA,CO2 is significantly higher than PET,CO2 in all subjects, especially in COPD patients; 3) VD,Bohr/VT is increased in COPD patients as compared to normal subjects; and 4) VD,Bohr/VT is lower than the "physiological" dead space ratio (VD,phys/VT) in COPD patients. It is concluded that the expired carbon dioxide versus tidal volume curve is a useful tool for research and clinical work, because it permits the noninvasive and accurate measurement of Bohr's dead space and mean alveolar carbon dioxide tension accurately during spontaneous breathing.

Complementarity in the Einstein-Bohr photon box

NARCIS (Netherlands)

Dieks, D.G.B.J.; Lam, S

2008-01-01

The Bohr-Einstein photon box thought experiment is a forerunner of the EPR experiment: a packet of radiation escapes from a box, and the box-plus-radiation state remains entangled. Hence, a measurement on the box makes a difference for the state of the far-away radiation long after its escape. This

Bohr quantum theory of the magnetic monopoles and classical electron electromagnetic mass problem

OpenAIRE

Pankovic, Vladan

2010-01-01

In the first part of this work we apply Bohr (old or naive quantum atomic) theory for analysis of the remarkable electro-dynamical problem of magnetic monopoles. We reproduce formally exactly some basic elements of the Dirac magnetic monopoles theory, especially Dirac electric/magnetic charge quantization condition. It follows after application of Bohr theory at the system, simply called magnetic monopole "atom", consisting of the practically standing, massive magnetic monopole as the "nucleu...

Prediction of energies of yrast band in some even-even nuclei

International Nuclear Information System (INIS)

Varshney, A.K.; Singh, Yuvraj; Gupta, D.K.; Singh, M.; Gupta, K.K.; Bihari, Chhail; Dhiman, S.K.

2012-01-01

The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. The researchers found that the values of γ obtained from energies (= γ e ) are nearly equal to the value of γ derived from transition rate (= γ b ) in even Xe, Ba and Ce nuclei (A∼120-140) and Hf, W, Os, Pt and Hg nuclei (A∼160-200) using rigid triaxial rotor model of Davydov-Filippov. In the present study, the relatively light mass nuclei (Mo, Ru and Pd) have been taken. As far as γ is concerned, it is known that the Ru chains of nuclei is intermediate between the two having opposite trends for parameter γ, decreasing for Mo and increasing for Pd, and has an irregular behaviour in itself with the increase of neutron number

The language of Orthodox theology & quantum mechanics: St Gregory Palamas and Niels Bohr

DEFF Research Database (Denmark)

Tanev, Stoyan

2013-01-01

The objective of this chapter is to provide an analytical framework that would enable the comparison of the ways of using words and language in the cases of St. Gregory Palamas and Niels Bohr. The main motivation will be to explore Christos Yannaras’ point about the opportunity of using quantum....... The focus on epistemological issues could be justified by the fact that both St. Gregory Palamas and Niels Bohr have been acknowledged for their epistemological insights....

The Bohr-Heisenberg correspondence principle viewed from phase space

DEFF Research Database (Denmark)

Dahl, Jens Peder

2002-01-01

Phase-space representations play an increasingly important role in several branches of physics. Here, we review the author's studies of the Bohr-Heisenberg correspondence principle within the Weyl-Wigner phase-space representation. The analysis leads to refined correspondence rules that can...

Triaxiality - recent progress in mass 160 region

International Nuclear Information System (INIS)

Ma Wenchao

2010-01-01

Triaxiality may affect various properties of the nucleus, such as the quasiparticle excitation energy, the relationship between signature partner bands, the electromagnetic decay strength between bands, etc. However, these effects can also be caused by other phenomena. On the other hand, quantized wobbling-phonon excitation, characterized by a sequence of rotational bands with increasing number of wobbling quanta, is a predicted mode uniquely related to triaxiality of nuclear shape [A. Bohr and B.R. Mottelson, Nuclear Structure, Vol. II, Benjamin, New York, 1975]. The search for experimental signatures of triaxial nuclear shapes has proven to be very challenging.

Niels Bohr and Complementarity An Introduction

CERN Document Server

Plotnitsky, Arkady

2012-01-01

This book offers a discussion of Niels Bohr’s conception of “complementarity,” arguably his greatest contribution to physics and philosophy. By tracing Bohr’s work from his 1913 atomic theory to the introduction and then refinement of the idea of complementarity, and by explicating different meanings of “complementarity” in Bohr and the relationships between it and Bohr’s other concepts, the book aims to offer a contained and accessible, and yet sufficiently comprehensive account of Bohr’s work on complementarity and its significance.

The Bohr--Einstein ''weighing-of-energy'' debate and the principle of equivalence

International Nuclear Information System (INIS)

Hughes, R.J.

1990-01-01

The Bohr--Einstein debate over the ''weighing of energy'' and the validity of the time--energy uncertainty relation is reexamined in the context of gravitation theories that do not respect the equivalence principle. Bohr's use of the equivalence principle is shown to be sufficient, but not necessary, to establish the validity of this uncertainty relation in Einstein's ''weighing-of-energy'' gedanken experiment. The uncertainty relation is shown to hold in any energy-conserving theory of gravity, and so a failure of the equivalence principle does not engender a failure of quantum mechanics. The relationship between the gravitational redshift and the equivalence principle is reviewed

High spin rotations of nuclei with the harmonic oscillator potential

International Nuclear Information System (INIS)

Cerkaski, M.; Szymanski, Z.

1978-01-01

Calculations of the nuclear properties at high angular momentum have been performed recently. They are based on the liquid drop model of a nucleus and/or on the assumption of the single particle shell structure of the nucleonic motion. The calculations are usually complicated and involve long computer codes. In this article we shall discuss general trends in fast rotating nuclei in the approximation of the harmonic oscillator potential. We shall see that using the Bohr Mottelson simplified version of the rigorous solution of Valatin one can perform a rather simple analysis of the rotational bands, structure of the yrast line, moments of inertia etc. in the rotating nucleus. While the precision fit to experimental data in actual nuclei is not the purpose of this paper, one can still hope to reach some general understanding within the model of the simple relations resulting in nuclei at high spin. (author)

Unified description of structure and reactions: implementing the nuclear field theory program

International Nuclear Information System (INIS)

Broglia, R A; Bortignon, P F; Barranco, F; Vigezzi, E; Idini, A; Potel, G

2016-01-01

The modern theory of the atomic nucleus results from the merging of the liquid drop model of Niels Bohr and Fritz Kalckar, and of the shell model of Marie Goeppert Meyer and Hans Jensen. The first model contributed the concepts of collective excitations. The second, those of independent-particle motion. The unification of these apparently contradictory views in terms of the particle-vibration and particle-rotation couplings carried out by Aage Bohr and Ben Mottelson has allowed for an ever more complete, accurate and detailed description of nuclear structure. Nuclear field theory (NFT), developed by the Copenhagen–Buenos Aires collaboration, provided a powerful quantal embodiment of this unification. Reactions are not only at the basis of quantum mechanics (statistical interpretation, Max Born), but also the specific tools to probe the atomic nucleus. It is then natural that NFT is being extended to deal with processes which involve the continuum in an intrinsic fashion, so as to be able to treat them on an equal footing with those associated with bound states (structure). As a result, spectroscopic studies of transfer to continuum states could eventually make use of the NFT rules, properly extended to take care of recoil effects. In the present contribution we review the implementation of the NFT program of structure and reactions, setting special emphasis on open problems and outstanding predictions. (invited comment)

The Life and Work of Niels Bohr – A Brief Sketch

Indian Academy of Sciences (India)

IAS Admin

Niels Henrik David Bohr was born to affluent parents on. 7 October 1885 in ... two years older; while his brother Harald, to whom he was ... sions from a very young age. ... married on 1 August 1912, the beginning of a 50-year relationship.

Niels Bohr's complementarity its structure, history, and intersections with hermeneutics and deconstruction

CERN Document Server

Katsumori, Makoto

2011-01-01

Through detailed textual and conceptual analysis, and with special attention to the potentially conflicting elements of Bohr's thought, this volume's fresh approach analyzes the relations between realism and antirealism through the prism of complementarity.

EPR before EPR: A 1930 Einstein-Bohr thought Experiment Revisited

Science.gov (United States)

Nikolic, Hrvoje

2012-01-01

In 1930, Einstein argued against the consistency of the time-energy uncertainty relation by discussing a thought experiment involving a measurement of the mass of the box which emitted a photon. Bohr seemingly prevailed over Einstein by arguing that Einstein's own general theory of relativity saves the consistency of quantum mechanics. We revisit…

Bohr Hamiltonian with an energy-dependent γ-unstable Coulomb-like potential

Energy Technology Data Exchange (ETDEWEB)

Budaca, R. [Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

2016-10-15

An exact analytical solution for the Bohr Hamiltonian with an energy-dependent Coulomb-like γ-unstable potential is presented. Due to the linear energy dependence of the potential's coupling constant, the corresponding spectrum in the asymptotic limit of the slope parameter resembles the spectral structure of the spherical vibrator, however with a different state degeneracy. The parameter free energy spectrum as well as the transition rates for this case are given in closed form and duly compared with those of the harmonic U(5) dynamical symmetry. The model wave functions are found to exhibit properties that can be associated to shape coexistence. A possible experimental realization of the model is found in few medium nuclei with a very low second 0{sup +} state known to exhibit competing prolate, oblate and spherical shapes. (orig.)

Effectiveness of an Asynchronous Online Module on University Students' Understanding of the Bohr Model of the Hydrogen Atom

Science.gov (United States)

Farina, William J.; Bodzin, Alec M.

2017-12-01

Web-based learning is a growing field in education, yet empirical research into the design of high quality Web-based university science instruction is scarce. A one-week asynchronous online module on the Bohr Model of the atom was developed and implemented guided by the knowledge integration framework. The unit design aligned with three identified metaprinciples of science learning: making science accessible, making thinking visible, and promoting autonomy. Students in an introductory chemistry course at a large east coast university completed either an online module or traditional classroom instruction. Data from 99 students were analyzed and results showed significant knowledge growth in both online and traditional formats. For the online learning group, findings revealed positive student perceptions of their learning experiences, highly positive feedback for online science learning, and an interest amongst students to learn chemistry within an online environment.

High resolution gamma-ray spectroscopy and the fascinating angular momentum realm of the atomic nucleus

International Nuclear Information System (INIS)

Riley, M A; Simpson, J; Paul, E S

2016-01-01

In 1974 Aage Bohr and Ben Mottelson predicted the different ‘phases’ that may be expected in deformed nuclei as a function of increasing angular momentum and excitation energy all the way up to the fission limit. While admitting their picture was highly conjectural they confidently stated ‘...with the ingenious experimental approaches that are being developed, we may look forward with excitement to the detailed spectroscopic studies that will illuminate the behaviour of the spinning quantised nucleus’ . High resolution gamma-ray spectroscopy has indeed been a major tool in studying the structure of atomic nuclei and has witnessed numerous significant advances over the last four decades. This article will select highlights from investigations at the Niels Bohr Institute, Denmark, and Daresbury Laboratory, UK, in the late 1970s and early 1980s, some of which have continued at other national laboratories in Europe and the USA to the present day. These studies illustrate the remarkable diversity of phenomena and symmetries exhibited by nuclei in the angular momentum–excitation energy plane that continue to surprise and fascinate scientists. (invited comment)

High resolution gamma-ray spectroscopy and the fascinating angular momentum realm of the atomic nucleus

Science.gov (United States)

Riley, M. A.; Simpson, J.; Paul, E. S.

2016-12-01

In 1974 Aage Bohr and Ben Mottelson predicted the different ‘phases’ that may be expected in deformed nuclei as a function of increasing angular momentum and excitation energy all the way up to the fission limit. While admitting their picture was highly conjectural they confidently stated ‘...with the ingenious experimental approaches that are being developed, we may look forward with excitement to the detailed spectroscopic studies that will illuminate the behaviour of the spinning quantised nucleus’. High resolution gamma-ray spectroscopy has indeed been a major tool in studying the structure of atomic nuclei and has witnessed numerous significant advances over the last four decades. This article will select highlights from investigations at the Niels Bohr Institute, Denmark, and Daresbury Laboratory, UK, in the late 1970s and early 1980s, some of which have continued at other national laboratories in Europe and the USA to the present day. These studies illustrate the remarkable diversity of phenomena and symmetries exhibited by nuclei in the angular momentum-excitation energy plane that continue to surprise and fascinate scientists.

Multilevel fitting of 235U resonance data sensitive to Bohr-and Brosa-fission channels

International Nuclear Information System (INIS)

Moore, M.S.

1995-01-01

The recent determination of the K, J dependence of the neutron induced fission cross section of 235 U by the Dubna group has led to a renewed interest in the mechanism of fission from saddle to scission. The K quantum numbers designate the so-called Bohr fission channels, which describe the fission properties at the saddle point. Certain other fission properties, e.g., the fragment mass and kinetic-energy distribution, are related to the properties of the scission point. The neutron energy dependence of the fragment kinetic energies has been measured by Hambsch et al., who analyzed their data according to a channel description of Brosa et al. How these two channel descriptions, the saddle-point Bohr channels and the scission-point Brosa channels, relate to one another is an open question, and is the subject matter of the present paper. We use the correlation coefficient between various data sets, in which variations are reported from resonance to resonance, as a measure of both-the statistical reliability of the data and of the degree to which different scission variables relate to different Bohr channels. We have carried out an adjustment of the ENDF/B-VI multilevel evaluation of the fission cross section of 235 U, one that provides a reasonably good fit to the energy dependence of the fission, capture, and total cross sections below 100 eV, and to the Bohr-channel structure deduced from an earlier measurement by Pattenden and Postma. We have also further explored the possibility of describing the data of Hambsch et al. in the Brosa-channel framework with the same set of fission-width vectors, only in a different reference system. While this approach shows promise, it is clear that better data are also needed for the neutron energy variation of the scission-point variables

Darwinism in disguise? A comparison between Bohr's view on quantum mechanics and QBism.

Science.gov (United States)

Faye, Jan

2016-05-28

The Copenhagen interpretation is first and foremost associated with Niels Bohr's philosophy of quantum mechanics. In this paper, I attempt to lay out what I see as Bohr's pragmatic approach to science in general and to quantum physics in particular. A part of this approach is his claim that the classical concepts are indispensable for our understanding of all physical phenomena, and it seems as if the claim is grounded in his reflection upon how the evolution of language is adapted to experience. Another, recent interpretation, QBism, has also found support in Darwin's theory. It may therefore not be surprising that sometimes QBism is said to be of the same breed as the Copenhagen interpretation. By comparing the two interpretations, I conclude, nevertheless, that there are important differences. © 2016 The Author(s).

Traffic restrictions on Routes Bloch, Maxwell and Bohr

CERN Multimedia

IT Department

2008-01-01

Excavation and pipework is being carried out in the framework of the transfer of the waste water treatment plant for the effluents from the surface treatment workshops from Building 254 to Building 676, currently under construction. This work may encroach onto Routes Bloch, Maxwell and Bohr and disrupt the flow of traffic. Users are requested to comply with the road signs that will be erected. The work is expected to last until the beginning of December 2008. Thank you for your understanding. TS/CE and TS/FM Groups Tel.7 4188 or 16 4314

Des images et des paraboles : Niels Bohr et le discours descriptif en physique quantique

Directory of Open Access Journals (Sweden)

Ilias Yocaris

2011-01-01

Full Text Available Cette étude porte sur l’importance accordée aux images verbales dans le discours descriptif utilisé en mécanique quantique, et plus précisément sur la conception de la langue scientifique qui est celle de Niels Bohr (1885-1962 : en raison d’une série de considérations techniques, méthodologiques et épistémologiques que nous nous proposons d’analyser in extenso, Bohr considère effectivement que les phénomènes subatomiques ne peuvent être évoqués directement (sans référence au contexte observationnel, par le biais d’un langage dénotatif non figural, mais uniquement de manière métaphorique, détournée, ce qui réduit à ses yeux le discours descriptif des physiciens à « des images et des paraboles ». En examinant les textes de Bohr à la lumière d’un certain nombre de travaux épistémologiques, de commentaires et d’expérimentations auxquels ils ont donné lieu ultérieurement, nous nous proposons de décrire les implications conceptuelles d’une telle prise de position, qui constitue une vraie révolution sur le plan philosophique.

Can we close the Bohr-Einstein quantum debate?

Science.gov (United States)

Kupczynski, Marian

2017-11-13

Recent experiments allow one to conclude that Bell-type inequalities are indeed violated; thus, it is important to understand what this means and how we can explain the existence of strong correlations between outcomes of distant measurements. Do we have to announce that Einstein was wrong, Nature is non-local and non-local correlations are produced due to quantum magic and emerge, somehow, from outside space-time? Fortunately, such conclusions are unfounded because, if supplementary parameters describing measuring instruments are correctly incorporated in a theoretical model, then Bell-type inequalities may not be proved. We construct a simple probabilistic model allowing these correlations to be explained in a locally causal way. In our model, measurement outcomes are neither predetermined nor produced in an irreducibly random way. We explain why, contrary to the general belief, the introduction of setting-dependent parameters does not restrict experimenters' freedom of choice. Since the violation of Bell-type inequalities does not allow the conclusion that Nature is non-local and that quantum theory is complete, the Bohr-Einstein quantum debate may not be closed. The continuation of this debate is important not only for a better understanding of Nature but also for various practical applications of quantum phenomena.This article is part of the themed issue 'Second quantum revolution: foundational questions'. © 2017 The Author(s).

Can we close the Bohr-Einstein quantum debate?

Science.gov (United States)

Kupczynski, Marian

2017-10-01

Recent experiments allow one to conclude that Bell-type inequalities are indeed violated; thus, it is important to understand what this means and how we can explain the existence of strong correlations between outcomes of distant measurements. Do we have to announce that Einstein was wrong, Nature is non-local and non-local correlations are produced due to quantum magic and emerge, somehow, from outside space-time? Fortunately, such conclusions are unfounded because, if supplementary parameters describing measuring instruments are correctly incorporated in a theoretical model, then Bell-type inequalities may not be proved. We construct a simple probabilistic model allowing these correlations to be explained in a locally causal way. In our model, measurement outcomes are neither predetermined nor produced in an irreducibly random way. We explain why, contrary to the general belief, the introduction of setting-dependent parameters does not restrict experimenters' freedom of choice. Since the violation of Bell-type inequalities does not allow the conclusion that Nature is non-local and that quantum theory is complete, the Bohr-Einstein quantum debate may not be closed. The continuation of this debate is important not only for a better understanding of Nature but also for various practical applications of quantum phenomena. This article is part of the themed issue `Second quantum revolution: foundational questions'.

Collective motion in prolate γ-rigid nuclei within minimal length concept via a quantum perturbation method

Science.gov (United States)

Chabab, M.; El Batoul, A.; Lahbas, A.; Oulne, M.

2018-05-01

Based on the minimal length concept, inspired by Heisenberg algebra, a closed analytical formula is derived for the energy spectrum of the prolate γ-rigid Bohr-Mottelson Hamiltonian of nuclei, within a quantum perturbation method (QPM), by considering a scaled Davidson potential in β shape variable. In the resulting solution, called X(3)-D-ML, the ground state and the first β-band are all studied as a function of the free parameters. The fact of introducing the minimal length concept with a QPM makes the model very flexible and a powerful approach to describe nuclear collective excitations of a variety of vibrational-like nuclei. The introduction of scaling parameters in the Davidson potential enables us to get a physical minimum of this latter in comparison with previous works. The analysis of the corrected wave function, as well as the probability density distribution, shows that the minimal length parameter has a physical upper bound limit.

Gravity, Special Relativity, and the Strong Force A Bohr-Einstein-de Broglie Model for the Formation of Hadrons

CERN Document Server

Vayenas, Constantinos G

2012-01-01

This book shows that the strong interaction forces, which keep hadrons and nuclei together, are relativistic gravitational forces exerted between very small particles in the mass range of neutrinos. First, this book considers the problematic motion of two charged particles under the influence of electrostatic and gravitational forces only, which shows that bound states are formed by following the same semi-classical methodology used by Bohr to describe the H atom. This approach is also coupled with Newton's gravitational law and with Einstein's special relativity. The results agree with experi

Quantum Humor: The Playful Side of Physics at Bohr's Institute for Theoretical Physics

Science.gov (United States)

Halpern, Paul

2012-09-01

From the 1930s to the 1950s, a period of pivotal developments in quantum, nuclear, and particle physics, physicists at Niels Bohr's Institute for Theoretical Physics in Copenhagen took time off from their research to write humorous articles, letters, and other works. Best known is the Blegdamsvej Faust, performed in April 1932 at the close of one of the Institute's annual conferences. I also focus on the Journal of Jocular Physics, a humorous tribute to Bohr published on the occasions of his 50th, 60th, and 70th birthdays in 1935, 1945, and 1955. Contributors included Léon Rosenfeld, Victor Weisskopf, George Gamow, Oskar Klein, and Hendrik Casimir. I examine their contributions along with letters and other writings to show that they offer a window into some issues in physics at the time, such as the interpretation of complementarity and the nature of the neutrino, as well as the politics of the period.

First measurement of the decoupling parameter for the K = 1 band of {sup 156}Gd

Energy Technology Data Exchange (ETDEWEB)

Beck, Tobias; Beller, Jacob; Gayer, Udo; Pietralla, Norbert; Ries, Philipp; Ries, Christopher; Werner, Volker; Zweidinger, Markus [IKP, TU Darmstadt (Germany); Derya, Vera [IKP, Universitaet zu Koeln (Germany); Isaak, Johann; Loeher, Bastian [EMMI, GSI, Darmstadt (Germany); FIAS, Frankfurt (Germany); Scheck, Marcus [IKP, TU Darmstadt (Germany); School of Engineering, UWS Paisley (United Kingdom); SUPA, Glasgow (United Kingdom); Tornow, Werner; Weller, Henry R. [Duke University, Durham (United States)

2016-07-01

In a deformed nucleus the nuclear states are combinations of an intrinsic motion and a rotational motion of the core. In this scenario the Coriolis force changes the projection of the angular momentum on the symmetry axis and admixes different K values. The effects of the Coriolis interactions have been observed experimentally for K = 1/2 bands. The recent observation of the first excited rotational state of the isovector low-lying J{sup π}{sub K} = 1{sup +}{sub 1} scissors mode in a (γ,γ{sup '}) experiment inaugurates a case to study the Coriolis decoupling for K = 1 bands. In the talk, the theoretical description provided by Bohr and Mottelson is presented, and their adaption to the particular case is explained alongside the ongoing analysis and open questions.

A united phenomenological description of quadrupole excitations in even-even nuclei

International Nuclear Information System (INIS)

Lipas, P.O.; Haapakoski, P.; Honkaranta, T.

1975-05-01

A phenomenological model is developed for the collective quadrupole properties of all even-even nuclei. Rotational, vibrational, and transitional nuclei are included in the model on an equal footing. A Bohr-type intrinsic Hamiltonian for harmonic quadrupole vibrations about an axially deformed shape is solved exactly. States of good angular momentum are projected out of the intrinsic states, and they are made orthogonal by a Schmidt scheme. The angular-momentum and phonon-number composition of the states is analyzed at various stages; states with K=1 are found spurious. Excitation energies for the ground, β and γ bands are calculated as expectation values of a radically simplified nuclear Hamiltonian in our projected and orthogonalized states. With increasing deformation the calculated energies evolve smoothly from the evenly spaced phonon spectrum to the Bohr-Mottelson rotational-vibrational spectrum according to the scheme of Sheline and Sakai. The basic model contains only two parameters (deformation d and energy scale) to fix the entire quadrupole spectrum of a nucleus. The results are given in the form of graphs suitable for immediate application; numerical results are readily produced by our computer code. The ground bands are fitted comparably to the VMI model, while the β and γ bands are reproduced qualitatively. The nuclei 152 Sm, 152 Gd, and 114 Cd are used as test cases. Quadrupole moments and E2 transition rates are also calculated. Intra-ground-band transition ratios and branching ratios from the β and γ bands are given in terms of the single parameter d. The results are applied to 152 Sm, with fair success. Finally the model to include two more parameters (anisotropy) is extended. The improvement over the basic model is modest in view of added parameters and computational effort. (author)

Complementarity and the Nature of Uncertainty Relations in Einstein–Bohr Recoiling Slit Experiment

Directory of Open Access Journals (Sweden)

Shogo Tanimura

2015-07-01

Full Text Available A model of the Einstein–Bohr recoiling slit experiment is formulated in a fully quantum theoretical setting. In this model, the state and dynamics of a movable wall that has two slits in it, as well as the state of a particle incoming to the two slits, are described by quantum mechanics. Using this model, we analyzed complementarity between exhibiting an interference pattern and distinguishing the particle path. Comparing the Kennard–Robertson type and the Ozawa-type uncertainty relations, we conclude that the uncertainty relation involved in the double-slit experiment is not the Ozawa-type uncertainty relation but the Kennard-type uncertainty relation of the position and the momentum of the double-slit wall. A possible experiment to test the complementarity relation is suggested. It is also argued that various phenomena which occur at the interface of a quantum system and a classical system, including distinguishability, interference, decoherence, quantum eraser, and weak value, can be understood as aspects of entanglement. Quanta 2015; 4: 1–9.

Bohring-Opitz (Oberklaid-Danks) syndrome: clinical study, review of the literature, and discussion of possible pathogenesis

DEFF Research Database (Denmark)

Hastings, Rob; Cobben, Jan-Maarten; Gillessen-Kaesbach, Gabriele

2011-01-01

Bohring-Opitz syndrome (BOS) is a rare congenital disorder of unknown etiology diagnosed on the basis of distinctive clinical features. We suggest diagnostic criteria for this condition, describe ten previously unreported patients, and update the natural history of four previously reported patients...

Nuclear shapes: from earliest ideas to multiple shape coexisting structures

International Nuclear Information System (INIS)

Heyde, K; Wood, J L

2016-01-01

The concept of the atomic nucleus being characterized by an intrinsic property such as shape came as a result of high precision hyperfine studies in the field of atomic physics, which indicated a non-spherical nuclear charge distribution. Herein, we describe the various steps taken through ingenious experimentation and bold theoretical suggestions that mapped the way for later work in the early 50s by Aage Bohr, Ben Mottelson and James Rainwater. We lay out a long and winding road that marked, in the period of 50s to 70s, the way shell-model and collective-model concepts were reconciled. A rapid increase in both accelerator and detection methods (70s towards the early 2000s) opened new vistas into nuclear shapes, and their coexistence, in various regions of the nuclear mass table. Next, we outline a possible unified view of nuclear shapes: emphasizing decisive steps taken as well as questions remaining, next to the theoretical efforts that could result in an emerging understanding of nuclear shapes, building on the nucleus considered as a strongly interacting system of nucleons as the microscopic starting point. (invited comment)

Systematic study of β-band and correlation with g- band using power law and soft rotor formula

International Nuclear Information System (INIS)

Katoch, Vikas; Kaushik, Reetu; Sharma, S.; Gupta, J.B.

2014-01-01

The nuclear structure of even Z even N medium mass transitional nuclei consist of ground state band, K π =0 1 β-band, K π =2 1 γ- band and other higher bands. As we move away from closed shell, energy levels are low lying from spherical to deformed nuclei and energy deviated from ideal rotor behavior. The energy of these transitional nuclei in ground band can also be studied using Bohr Mottelson energy expression, Soft Rotor Formula (SRF), Power Law (PL) etc. Recently, Gupta et al. (2013) modified SRF for non zero band head K π =2 1 γ-band and reproduced the level energies. Here same formula applied for K π =0 1 β-band and the level energies are reproduced and compared with experimental energies. The power law is also used for recalculation of level energies and for useful comparison

Wave-particle duality and Bohr's complementarity principle in quantum mechanics

International Nuclear Information System (INIS)

Sen, D.; Basu, A.N.; Sengupta, S.

1995-01-01

Interest on Bohr's complementarity principle has recently been revived particularly because of several thought experiments and some actually performed experiments to test the validity of mutual exclusiveness of wave and particle properties. A critical review of the situation is undertaken and it is pointed out that the problem with mutual exclusiveness arises because of some vagueness in the conventional formulation. An attempt is made to remove this vagueness by connecting the origin of mutual exclusiveness to some principles of quantum mechanics. Accordingly, it becomes obvious that to contradict complementarity principle without contradicting quantum mechanics would be impossible. Some of the recent experiments are critically analysed. (author). 31 refs., 3 ills

Oxygen affinity and Bohr effect responses to 2,3-diphosphoglycerate in equine and human blood.

Science.gov (United States)

diBella, G; Scandariato, G; Suriano, O; Rizzo, A

1996-05-01

The dependence of blood oxygen affinity and the Bohr effect on the concentration of 2,3-diphosphoglycerate (DPG) in erythrocytes was investigated in 24 trotter horses and 24 healthy men. The oxygen tension at half saturation and standard conditions (P50st at pH 7.4, PCO2(40) mmHg and 37 degrees C) and the carbon dioxide or fixed-acid-induced Bohr effect (dlogP50/dpH) were determined. Samples of fresh blood and blood depleted of or enriched with DPG were studied. In the absence of measurable DPG, the equine and human blood had similar mean (SD) values of P50st (16.6 [0.6] and 16.2 [0.7] mmHg, respectively). In both species these values increased with increasing DPG, but the response of equine blood was significantly lower, at least up to physiological values (P50st = 24.6 [0.6] and 26.2 [0.7]) mmHg; DPG = 14([1.8] and 12.8 [1.2] mumol gHb-1, respectively, in fresh blood). For concentrations above 20 to 25 mumol gHb-1 of DPG the difference between the values of P50st in the two species tended to decrease because the response in human blood reached a plateau. The interactions between the Bohr effect and the concentration of DPG showed that in the horses, as in the men, the level of DPG played an important role in governing the relative magnitude of carbon dioxide and fixed acid factors. The difference between them, which is associated with the oxylabile carbamino binding, was greatest in DPG-depleted blood, but whereas in the men the difference was suppressed by an above normal DPG concentration, in the horses it was still measurable.

Systematics of triaxial moment of inertia and deformation parameters (β, γ) in even-even nuclei of mass region A = 90-120

International Nuclear Information System (INIS)

Singh, Yuvraj; Gupta, D.K.; Singh, M.; Gupta, K.K.; Bihari, Chhail; Varshney, A.K.; Dhiman, S.K.

2012-01-01

The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. In recent past the sets of deformation parameters ((β, γ) have been extracted from both level energies and E2 transition rates in even Xe, Ba and Ce nuclei (A∼120-140) and Hf, W, Os, Pt and Hg nuclei (A∼160-200) using rigid triaxial rotor model of Davydov-Filippov (DF). Researcher have found that the values of β obtained separately from energy and transition rate (β e and β b respectively), though, are found almost equal in heavy mass region (A ∼160-200) but, not so in medium mass (A∼120-140) nuclei. This observation puts a question mark whether the ββ dependence of moment of inertia in hydrodynamic model is reliable. The purpose of the present work is to study a relatively lighter mass region (A∼90-120) where the gap between values of two sets of β may further increase. To improve the calculations for extracting β e , the use of Grodzins rule will be made along with uncertainties, since only through this rule the E2 1 + is related with β G (value of β for symmetric nucleus and evaluated using Grodzins rule)

Electric quadrupole giant resonance in the photofission of sup(238)U IFUSP-P--140

International Nuclear Information System (INIS)

Bhandari, B.S.; Arruda Neto, J.D.T.; Herdade, S.B.; Nascimento, I.C.

1978-02-01

The 238 U nucleus was studied measuring the electrofission yield and angular distributions of fission fragments, in the energy range of 5.5 to 28.3 MeV, using a new method of analysis. An E2 isoscalar giant resonance was found in the photofission cross section of 238 U. This resonance exhausts (71 + -7)% of the EWSR and is located at 9.9 + -0.2 MeV with a width of 6.8 + -0.4 MeV. The position of this resonance is in reasonable agreement with the Bohr and Mottelson prediction (58.Asup( - 1/3MeV). The width of 6.8 + -0.4 MeV is compatible with a possible triple splitting of the resonance. From the angular distributions of photofission fragments and yield measurements of multipoles other than E1, evidence of an M1 mixture in the energy region 6-7 MeV was found

Systematic measurements of the Bohr-Weisskopf effect at ISOLDE

CERN Multimedia

Nojiri, Y; Matsuki, S; Ragnarsson, I; Neugart, R; Redi, O; Stroke, H H; Duong, H T; Marescaux, D; Pinard, J; Juncar, P; Ekstrom, C; Pellarin, M; Vialle, J-L; Inamura, T

2002-01-01

The " Bohr-Weisskopf " effect, or " hyperfine structure (hfs) anomaly ", which results from the effect of the distribution of nuclear magnetization on the electro-nuclear interaction, will be measured systematically at the PS Booster ISOLDE, first for a long chain of radioactive cesium isotopes, analogously to previous isotope shift and hfs studies. In addition to the direct measurement of magnetic moment values, the results are expected to provide independent data for testing nuclear wavefunctions, these will be of importance for interpreting systematic parity non-conservation experiments, complementary to the single isotope study which requires a high precision knowledge of the electron wavefunction. Substantial progress in these calculations has been achieved recently. Precision measurements of the hfs splittings and nuclear magnetic moments are required, with sensitivity adequate for the radioactive isotopes produced. A triple resonance atomic beam magnetic resonance apparatus with optical pumping state s...

Niels Bohr, Max Delbruck and the paradox of light and life

International Nuclear Information System (INIS)

Scott, G.P.

1983-01-01

This paper features a concise, interdisciplinary history of philosophical issues which were the basis of Delbruck's scientific career. The paradox in living behavior of freedom-to-adapt versus deterministic atomism required complete reassessment with the advent of quantum mechanics. Apparent contradictions implied, for example, by the wave-particle model led Bohr to a belief in the ''complementarity of nature,'' which in 1932 he applied to biology. His claim was that purely physicochemical explanations of purposeful life functions such as ''self-generation and freedom of the will'' were impossible since mutually exclusive situations were involved. Thus Delbruck was challenged to spend his career investigating these vital functions. Beginning with ''fruit-fly photochemistry'' he established the molecular nature of the gene and then collected a world-wide group for a research effort on phage virus, which culminated in discovery of the DNA double helix by Watson and Crick. The second phase of his career featured a study of the total stimulus-response system of the fungus Phycomuces, which is still in progress. The extreme light-sensitivity observed, approaching one-quantum response, has raised the question of the survival value of amplified quantum noise. In critical comments to the author, Delbruck opposed the ''Compton-switch model'' for mind-body interaction; and in his lecture, ''Mind from Matter?'' he revealed his ''a priori concept of truth,'' which embraces a neutral monism and rejects the language of emergent evolution. His views are contrasted with those expressed in Popper's First Darwin Lecture

Systematic Measurements of the Bohr-Weisskopf Effect at ISOLDE

CERN Multimedia

2002-01-01

Nuclear electric and magnetic structure properties are measurable by high-resolution atomic spectroscopy through isotope shifts and the Bohr-Weisskopf effect (hyperfine structure anomalies). \\\\ \\\\ The greatest value of these measurements is when made systematically over a large number of isotopes. This has been done in the case of isotopes shifts most extensively by the experiment at ISOLDE. To date the magnetic distribution studies are few and isolated. Here we propose to intitiate a program at ISOLDE to measure hfs anomalies systematically. The experiments, requiring high-precision data on magnetic dipole constants as well as on nuclear g-factors, will be done by atomic-beam magnetic resonance with the use of laser excitation for polarization of the beam and a sixpole magnet acting as an analyser. \\\\ \\\\ The heavy alkali elements are the most promising candidates for hfs anomaly studies because of the large effect expected, the high production yields at ISOLDE and most importantly, the interesting variations...

Diffusive insights: on the disagreement of Christian Bohr and August Krogh at the Centennial of the Seven Little Devils

DEFF Research Database (Denmark)

Gjedde, Albert

2010-01-01

The year 2010 is the centennial of the publication of the “Seven Little Devils” in the predecessor of Acta Physiologica. In these seven papers, August and Marie Krogh sought to refute Christian Bohr's theory that oxygen diffusion from the lungs to the circulation is not entirely passive but rather...

Diffusive Insights: On the Disagreement of Christian Bohr and August Krogh at the Centennial of the Seven Little Devils

Science.gov (United States)

Gjedde, Albert

2010-01-01

The year 2010 is the centennial of the publication of the "Seven Little Devils" in the predecessor of "Acta Physiologica". In these seven papers, August and Marie Krogh sought to refute Christian Bohr's theory that oxygen diffusion from the lungs to the circulation is not entirely passive but rather facilitated by a specific cellular activity…

The divine clockwork: Bohr's correspondence principle and Nelson's stochastic mechanics for the atomic elliptic state

International Nuclear Information System (INIS)

Durran, Richard; Neate, Andrew; Truman, Aubrey

2008-01-01

We consider the Bohr correspondence limit of the Schroedinger wave function for an atomic elliptic state. We analyze this limit in the context of Nelson's stochastic mechanics, exposing an underlying deterministic dynamical system in which trajectories converge to Keplerian motion on an ellipse. This solves the long standing problem of obtaining Kepler's laws of planetary motion in a quantum mechanical setting. In this quantum mechanical setting, local mild instabilities occur in the Keplerian orbit for eccentricities greater than (1/√(2)) which do not occur classically

Investigation of Bohr Hamiltonian in presence of Killingbeck potential using bi-confluent Heun functions

Science.gov (United States)

Sobhani, Hadi; Hassanabadi, Hassan; Chung, Won Sang

2018-05-01

In this study, Bohr Hamiltonian is studied for the triaxial and rotational cases. In both cases, Killingbeck potential is used as interaction. The wave function and energy of these cases are found using bi-confluent Heun functions. The results are examined by reproducing experimental data of some isotopes for each case. Energy levels of the isotopes are shown graphically as well as theoretical results for staggering in γ bands of the isotopes is discussed. In the next step, we argue about B (E 2) transition rates of the isotopes for each case. The results have a good agreement with experimental data.

Excited collective states of nuclei within Bohr Hamiltonian with Tietz-Hua potential

Energy Technology Data Exchange (ETDEWEB)

Chabab, M.; El Batoul, A.; Lahbas, A.; Oulne, M. [Cadi Ayyad University, High Energy Physics and Astrophysics Laboratory, Faculty of Sciences Semlalia, Marrakesh (Morocco); Hamzavi, M. [University of Zanjan, Department of Physics, Zanjan (Iran, Islamic Republic of)

2017-07-15

In this paper, we present new analytical solutions of the Bohr Hamiltonian problem that we derived with the Tietz-Hua potential, here used for describing the β-part of the nuclear collective potential plus that of the harmonic oscillator for the γ-part. Also, we proceed to a systematic comparison of the numerical results obtained with this kind of β-potential with others which are widely used in such a framework as well as with the experiment. The calculations are carried out for energy spectra and electromagnetic transition probabilities for γ-unstable and axially symmetric deformed nuclei. In the same frame, we show the effect of the shape flatness of the β-potential beyond its minimum on transition rates calculations. (orig.)

The quest for reality Bohr and Wittgenstein : two complementary views

CERN Document Server

Stenholm, Stig

2015-01-01

In both science and philosophy, the twentieth century saw a radical breakdown of certainty in the human worldview, as quantum uncertainty and linguistic ambiguity destroyed the comfortable certitudes of the past. As these disciplines form the foundation for a human position in the world, a major epistemological reorganization had to take place. In this book, quantum theorist Stig Stenholm presents Bohr and Wittgenstein, in physics and in philosophy, as central figures representing this revision. Each of them took up the challenge of replacing apparent order and certainty with a provisional understanding based on limited concepts in constant flux. Stenholm concludes that the modern synthesis created by their heirs is far from satisfactory, and the story is so far an unfinished one. The book will appeal to any researcher in either discipline curious about the foundation of modern science, and works to provoke a renewal of discussion, and the eventual emergence of a reformed clarity and understanding.

A novel system for transcutaneous application of carbon dioxide causing an "artificial Bohr effect" in the human body.

Directory of Open Access Journals (Sweden)

Yoshitada Sakai

Full Text Available BACKGROUND: Carbon dioxide (CO(2 therapy refers to the transcutaneous administration of CO(2 for therapeutic purposes. This effect has been explained by an increase in the pressure of O(2 in tissues known as the Bohr effect. However, there have been no reports investigating the oxygen dissociation of haemoglobin (Hb during transcutaneous application of CO(2in vivo. In this study, we investigate whether the Bohr effect is caused by transcutaneous application of CO2 in human living body. METHODS: We used a novel system for transcutaneous application of CO(2 using pure CO(2 gas, hydrogel, and a plastic adaptor. The validity of the CO(2 hydrogel was confirmed in vitro using a measuring device for transcutaneous CO(2 absorption using rat skin. Next, we measured the pH change in the human triceps surae muscle during transcutaneous application of CO(2 using phosphorus-31 magnetic resonance spectroscopy ((31P-MRS in vivo. In addition, oxy- and deoxy-Hb concentrations were measured with near-infrared spectroscopy in the human arm with occulted blood flow to investigate O2 dissociation from Hb caused by transcutaneous application of CO(2. RESULTS: The rat skin experiment showed that CO(2 hydrogel enhanced CO(2 gas permeation through the rat skin. The intracellular pH of the triceps surae muscle decreased significantly 10 min. after transcutaneous application of CO(2. The NIRS data show the oxy-Hb concentration decreased significantly 4 min. after CO(2 application, and deoxy-Hb concentration increased significantly 2 min. after CO(2 application in the CO(2-applied group compared to the control group. Oxy-Hb concentration significantly decreased while deoxy-Hb concentration significantly increased after transcutaneous CO(2 application. CONCLUSIONS: Our novel transcutaneous CO(2 application facilitated an O(2 dissociation from Hb in the human body, thus providing evidence of the Bohr effect in vivo.

ToE in a nutshell or reconciliation of Bohr and Einstein

Energy Technology Data Exchange (ETDEWEB)

Kaesser, Juergen

2016-07-01

Unification of particle and gravitational physics is today's major challenge. This book describes a comprehensive theory able to accomplish it. Starting with a few basic assumptions it allows deducting so different features as e.g. the forces, the six quarks, particle mass etc. of the Standard Model or light deflection, perihelion rotation, Shapiro effect, red shift etc. of General Relativity. Furthermore among others it gives answers to open questions like GUT, Dark Mass and eventually Dark Energy, justifies why the behavior of elementary particles in a gravitational field complies with the Schroedinger equation or why the radii of the planets in our solar system are as they are. Einstein and Bohr fiercely struggled for an understanding of quantum physics. Their different perspectives seem to be irreconcilable. Because of the overwhelming success of quantum physics the dissent unsettling the foundation of physics was never resolved. Doing it, as it is tried in this book, comprehensibility for physical processes is regained. Paradoxes like Schroedinger's Cat vanish into thin air. A theory of unification cannot be simple as it has to contain the known physics. Moreover it has to overcome their contradictions as in defining space-time or in postulating separability. Advantage of the here presented approach compared to M-theory or Loop Quantum Gravitation is its ability to deduct observable features. Of course open questions remain being answered requiring the computational effort of actual theories if not even much more. But these items do not define the basic message of the theory but the derivation of specifics.

How to understand the tunneling in attosecond experiment?. Bohr-Einstein photon box Gedanken experiment, tunneling time and the wave particle duality

Science.gov (United States)

Kullie, Ossama

2018-02-01

The measurement of the tunneling time (T-time) in today's attosecond and strong field (low-frequency) experiments, despite its controversial discussion, offers a fruitful opportunity to understand time measurement and the time in quantum mechanics. In addition, as we will see in this work, a related controversial issue is the particulate nature of the radiation. The T-time in attosecond experiment and its different aspects and models, is discussed in this work, especially in relation to my model of real T-time (Kullie, 2015), where a good agreement with the experiment and an intriguing similarity to the Bohr-Einstein photon box Gedanken experiment was found. The tunneling process itself is still not well understood, but I am arguing that a scattering mechanism (by the laser wave packet) offers a possibility to understand the tunneling process in the tunneling region. This is related to the question about the corpuscular nature of light which is widely discussed in modern quantum optics experiments.

The Compton Radius, the de Broglie Radius, the Planck Constant, and the Bohr Orbits

Directory of Open Access Journals (Sweden)

Daywitt W. C.

2011-04-01

Full Text Available The Bohr orbits of the hydrogen atom and the Planck constant can be derived classically from the Maxwell equations and the assumption that there is a variation in the electron's velocity about its average value. The resonant nature of the circulating electron and its induced magnetic and Faraday fields prevents a radiative collapse of the electron into the nuclear proton. The derived Planck constant is $h=2pi e^2/alpha c$, where $e$, $alpha$, and $c$ are the electronic charge, the fine structure constant, and the speed of light. The fact that the Planck vacuum (PV theory derives the same Planck constant independently of the above implies that the two derivations are related. The following highlights that connection.

The Compton Radius, the de Broglie Radius, the Planck Constant, and the Bohr Orbits

Directory of Open Access Journals (Sweden)

Daywitt W. C.

2011-04-01

Full Text Available The Bohr orbits of the hydrogen atom and the Planck constant can be derived classically from the Maxwell equations and the assumption that there is a variation in the electron’s velocity about its average value [1]. The resonant nature of the circulating electron and its induced magnetic and Faraday fields prevents a radiative collapse of the electron into the nuclear proton. The derived Planck constant is h = 2 e 2 = c , where e , , and c are the electronic charge, the fine structure constant, and the speed of light. The fact that the Planck vacuum (PV theory [2] derives the same Planck constant independently of the above implies that the two derivations are related. The following highlights that connection.

A historical overview of nuclear structure studies in Strasbourg Laboratories: instrumentation, measurements and theory modelling—hand-in-hand

Science.gov (United States)

Beck, F. A.

2018-05-01

This article overviews a long period of an important evolution in the nuclear structure research in Strasbourg Laboratories, focussed on tracking of the weaker and weaker experimental signals carrying the more and more important physics messages. In particular we address the research of signatures of the collective behaviour of the nucleus as suggested in the early works of Bohr, Mottelson and Rainwater—at high and very high angular momenta—as well as the competition between the collective and non-collective excitation modes. These ambitious goals were possible to achieve only by constructing powerful spectrometers and developing related detectors, electronics and data acquisition systems. The theoretical modelling developed in parallel, provided essential guidance when choosing the right experiments and optimising their realisation. Theory calculations were equally helpful in interpreting the results of experiments leading to a more complete understanding of the underlying physics. Moreover, thanks to the development of heavy ion accelerators, the Strasbourg centre was the place where crossed the ways of many experimenters from European countries both from the Western and from the Central part of Europe, the place of the gradual development of more and more sophisticated European gamma-spectrometers in collaboration with more and more laboratories from the increasing number of countries allowing for the frontier-level studies of the nuclear behaviour at very high angular momenta.

Erik Rasmussen, Niels Bohr og Værdirelativismen - i anledning af Kasper Lippert-Rasmussens bog om Erik Rasmussen

DEFF Research Database (Denmark)

Ougaard, Morten

2015-01-01

En svaghed ved Kasper Lippert-Rasmussens i øvrigt udmærkede bog om Erik Rasmussen er, at den forbigår den sene Rasmussens bog om komplementaritet og statskundskab. Bogen var vigtig for Rasmussen, og den bør indgå i hans faglige eftermæle. Den rummer videnskabsteoretiske argumenter af stor relevans...... ikke mindst forholdet mellem normative og kognitive udsagn. Efter mødet med Niels Bohrs filosofi står Rasmussens værdirelativisme både skarpere og stærkere end før, og Kasper Lippert-Rasmussens karakteristik af denne position som et ubegrundet dogme i dansk politologi er ikke overbevisende....

Roles of the β 146 histidyl residue in the molecular basis of the Bohr Effect of hemoglobin: A proton nuclear magnetic resonance study

International Nuclear Information System (INIS)

Busch, M.R.; Mace, J.E.; Ho, N.T.; Ho, Chien

1991-01-01

Assessment of the roles of the carboxyl-terminal β146 histidyl residues in the alkaline Bohr effect in human and normal adult hemoglobin by high-resolution proton nuclear magnetic resonance spectroscopy requires assignment of the resonances corresponding to these residues. By a careful spectroscopic study of human normal adult hemoglobin, enzymatically prepared des(His146β)-hemoglobin, and the mutant hemoglobins Cowtown (β146His → Leu) and York (β146His → Pro), the authors have resolved some of these conflicting results. By a close incremental variation of pH over a wide range in chloride-free 0.1 M N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid buffer, a single resonance has been found to be consistently missing in the proton nuclear magnetic resonance spectra of these hemoglobin variants. The results indicate that the contribution of the β146 histidyl residues is 0.52 H + /hemoglobin tetramer at pH 7.6, markedly less than 0.8 H + /hemoglobin tetramer estimated by study of the mutant hemoglobin Cowtown (β146His → Leu) by Shih and Perutz. They have found that at least two histidyl residues in the carbonmonoxy form of this mutant have pK values that are perturbed, and they suggest that these pK differences may in part account for this discrepancy. The results show that the pK values of β146 histidyl residues in the carbonmonoxy form of hemoglobin are substantially affected by the presence of chloride and other anions in the solvent, and thus, the contribution of this amino acid residue to the alkaline Bohr effect can be shown to vary widely in magnitude, depending on the solvent composition. These results demonstrate that the detailed molecular mechanisms of the alkaline Bohr effect are not unique but are affected both by the hemoglobin structure and by the interactions with the solvent components in which the hemoglobin molecule resides

What is complementarity?: Niels Bohr and the architecture of quantum theory

Science.gov (United States)

Plotnitsky, Arkady

2014-12-01

This article explores Bohr’s argument, advanced under the heading of ‘complementarity,’ concerning quantum phenomena and quantum mechanics, and its physical and philosophical implications. In Bohr, the term complementarity designates both a particular concept and an overall interpretation of quantum phenomena and quantum mechanics, in part grounded in this concept. While the argument of this article is primarily philosophical, it will also address, historically, the development and transformations of Bohr’s thinking, under the impact of the development of quantum theory and Bohr’s confrontation with Einstein, especially their exchange concerning the EPR experiment, proposed by Einstein, Podolsky and Rosen in 1935. Bohr’s interpretation was progressively characterized by a more radical epistemology, in its ultimate form, which was developed in the 1930s and with which I shall be especially concerned here, defined by his new concepts of phenomenon and atomicity. According to this epistemology, quantum objects are seen as indescribable and possibly even as inconceivable, and as manifesting their existence only in the effects of their interactions with measuring instruments upon those instruments, effects that define phenomena in Bohr’s sense. The absence of causality is an automatic consequence of this epistemology. I shall also consider how probability and statistics work under these epistemological conditions.

What is complementarity?: Niels Bohr and the architecture of quantum theory

International Nuclear Information System (INIS)

Plotnitsky, Arkady

2014-01-01

This article explores Bohr’s argument, advanced under the heading of ‘complementarity,’ concerning quantum phenomena and quantum mechanics, and its physical and philosophical implications. In Bohr, the term complementarity designates both a particular concept and an overall interpretation of quantum phenomena and quantum mechanics, in part grounded in this concept. While the argument of this article is primarily philosophical, it will also address, historically, the development and transformations of Bohr’s thinking, under the impact of the development of quantum theory and Bohr’s confrontation with Einstein, especially their exchange concerning the EPR experiment, proposed by Einstein, Podolsky and Rosen in 1935. Bohr’s interpretation was progressively characterized by a more radical epistemology, in its ultimate form, which was developed in the 1930s and with which I shall be especially concerned here, defined by his new concepts of phenomenon and atomicity. According to this epistemology, quantum objects are seen as indescribable and possibly even as inconceivable, and as manifesting their existence only in the effects of their interactions with measuring instruments upon those instruments, effects that define phenomena in Bohr’s sense. The absence of causality is an automatic consequence of this epistemology. I shall also consider how probability and statistics work under these epistemological conditions. (paper)

Geometrical model for the electron

International Nuclear Information System (INIS)

El-Sherbini, T.M.

1985-07-01

A model for an electron of finite dimensions is proposed. This model disregards the concept of electronic charge and leads to Bohr's frequency formula for the hydrogen atom and to Maxwell's equations for electromagnetic fields. The stability of a free electron under the action of centrifugal and transverse forces is discussed. (author)

Entropy of Iterated Function Systems and Their Relations with Black Holes and Bohr-Like Black Holes Entropies

Directory of Open Access Journals (Sweden)

Christian Corda

2018-01-01

Full Text Available In this paper we consider the metric entropies of the maps of an iterated function system deduced from a black hole which are known the Bekenstein–Hawking entropies and its subleading corrections. More precisely, we consider the recent model of a Bohr-like black hole that has been recently analysed in some papers in the literature, obtaining the intriguing result that the metric entropies of a black hole are created by the metric entropies of the functions, created by the black hole principal quantum numbers, i.e., by the black hole quantum levels. We present a new type of topological entropy for general iterated function systems based on a new kind of the inverse of covers. Then the notion of metric entropy for an Iterated Function System ( I F S is considered, and we prove that these definitions for topological entropy of IFS’s are equivalent. It is shown that this kind of topological entropy keeps some properties which are hold by the classic definition of topological entropy for a continuous map. We also consider average entropy as another type of topological entropy for an I F S which is based on the topological entropies of its elements and it is also an invariant object under topological conjugacy. The relation between Axiom A and the average entropy is investigated.

Classical photodissociation dynamics with Bohr quantization: Application to the fragmentation of a van der Waals cluster

International Nuclear Information System (INIS)

Arbelo-González, W.; Bonnet, L.; Larrégaray, P.; Rayez, J.-C.; Rubayo-Soneira, J.

2012-01-01

Graphical abstract: A recent classical description of photodissociation dynamics in a quantum spirit is applied for the first time to a realistic process, the fragmentation of NeBr 2 . Highlights: ► The photo-dissociation of NeBr 2 is studied by means of two approaches. ► The first is the standard classical one with Gaussian binning. ► The second is a new method applied for the first time to a realistic system. ► The new method leads to exactly the same results as the standard one. ► However, it requires about 10 times less trajectories in the present case. - Abstract: The recent classical dynamical approach of photodissociations with Bohr quantization [L. Bonnet, J. Chem. Phys. 133 (2010) 174108] is applied for the first time to a realistic process, the photofragmentation of the van der Waals cluster NeBr 2 . We illustrate the fact that this approach, formally equivalent to the standard one, may be numerically much more efficient.

Loss of Asxl1 Alters Self-Renewal and Cell Fate of Bone Marrow Stromal Cell, Leading to Bohring-Opitz-like Syndrome in Mice

Directory of Open Access Journals (Sweden)

Peng Zhang

2016-06-01

Full Text Available De novo ASXL1 mutations are found in patients with Bohring-Opitz syndrome, a disease with severe developmental defects and early childhood mortality. The underlying pathologic mechanisms remain largely unknown. Using Asxl1-targeted murine models, we found that Asxl1 global loss as well as conditional deletion in osteoblasts and their progenitors led to significant bone loss and a markedly decreased number of bone marrow stromal cells (BMSCs compared with wild-type littermates. Asxl1−/− BMSCs displayed impaired self-renewal and skewed differentiation, away from osteoblasts and favoring adipocytes. RNA-sequencing analysis revealed altered expression of genes involved in cell proliferation, skeletal development, and morphogenesis. Furthermore, gene set enrichment analysis showed decreased expression of stem cell self-renewal gene signature, suggesting a role of Asxl1 in regulating the stemness of BMSCs. Importantly, re-introduction of Asxl1 normalized NANOG and OCT4 expression and restored the self-renewal capacity of Asxl1−/− BMSCs. Our study unveils a pivotal role of ASXL1 in the maintenance of BMSC functions and skeletal development.

Hydrogen atom as test field of theoretical models

International Nuclear Information System (INIS)

Baiquni, A.

1976-01-01

Semi classical theory, covering Bohr atom theory, Bohr Sommerfeld theory, Sommerfeld relativistic theory, and quantum theory such as particle and complementarity dualism, wave mechanics, approximation method, relativistic quantum mechanics, and hydrogen atom fine structure, are discussed. (SMN)

Fission via compound states and JπK A. Bohr's channels: what we can learn from recent studies with slow neutrons

Directory of Open Access Journals (Sweden)

Furman W.I.

2012-02-01

Full Text Available Last data on angular correlations of fission fragments from slow (s-wave neutron induced binary fission of spin-aligned nuclei 235U are discussed in the context of JπK A. Bohrs channels. Special attention is paid to K = 0 channel. Reasons for its suppression are specified for compound nucleus states of negative parity. A brief overview of recent data on T-odd angular correlations in ternary and binary (with emission of a third particle, a neutron or γ-quantum fission induced by slow polarized neutrons is presented. On the basis of the developed theoretical approach it is shown that a valuable information on JπK fission channels at scission point can be inferred from these T-odd angular correlations.

El pabellón Niels Bohr. Tradición Danesa y Modernidad

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Carmen García Sánchez

2015-12-01

Full Text Available La casa de invitados de Niels Bohr fue el primer edificio del arquitecto danés Vilhelm Wohlert (1920-2007. Arraigado a la tradición danesa, representa una renovación basada en la absorción de influencias extranjeras: la arquitectura americana y la tradición japonesa. La caja de madera tiene el carácter sensible de un organismo vivo, siempre cambiante según las variaciones de luz del día o temperatura. Puertas plegables y contraventanas generan extensiones de las habitaciones. Cuando se abren, crean una prolongación del espacio interior, que se extiende a la naturaleza circundante, y se expande hacia el espacio exterior, permitiendo su movilización. Se establece una arquitectura de flujos. Protagoniza un ejemplo de la modernidad como refinamiento en la técnica de los límites y la idea de que la arquitectura no es un objeto material, sino el espacio generado en su interior. Podría ser visto como un ikebana; “el arte del espacio”, donde se produce una circulación de aire entre sus componentes; algo vivo que expresa la tercera dimensión, el equilibrio asimétrico, un interés por la materia, su textura y efecto emocional que emana. Hay armonía y equilibrio, que transmiten serenidad y belleza; un encuentro con la naturaleza; un mundo de relaciones amable al ser humano.

Description of nuclear properties

International Nuclear Information System (INIS)

Faessler, A.

1991-01-01

The lectures want to give a survey about new developments in the description of nuclei. In a first chapter we try to derive nuclear properties from the basis theory of quantum chromodynamics. This is not rigorously possible. There are still many cracks in the bridge between QCD and nuclear structure. The basic ingredient for nuclear structure calculations is the nucleon-nucleon interaction. We shall discuss the nucleon-nucleon interaction in a quark model. In a further chapter we discuss the way to come from a bare nucleon-nucleon interaction in free space to an effective nucleon-nucleon interaction in a limited model space for nuclear structure calculations. Such nuclear structure calculations can be done as shell model calculations. But they are due to the large number of configurations limited to light nuclei. We discuss possibilities (MONSTER and VAMPIR) to enlarge the model space for medium heavy and heavy nuclei. As the example of the low lying isovector 1 + states we discuss collective models (Bohr - Mottelson Model, interacting Boson Model) with proton and neutron degrees of freedom. The same states can also be described microscopically with the Quasi-Particle Random Phase Approximation (QRPA). We discuss the removal of spurious states in RPA. We also discuss the calculation of form factors and compare with inelastic electron scattering data. Finally we apply QRPA to the double-beta decay. Grand unified models predict, that the neutrino is identical with his antiparticle, that it has a finite mass and a weak right-handed interaction. If these properties are found the standard model of the strong and the electro-weak interaction can not be correct. Presently we can only derive from lower limits of the half lives of neutrinoless double-beta decays upper limits of the neutrino mass and of the right-handedness of the weak interaction and lower limits of the mass of the right handed heavy vector boson, if a specific grand unified model is given. (author)

A new atomic model

International Nuclear Information System (INIS)

Petrescu, Florian Ion

2012-01-01

The movement of an electron around the atomic nucleus has today a great importance in many engineering fields. Electronics, aeronautics, micro and nanotechnology, electrical engineering, optics, lasers, nuclear power, computing, equipment and automation, telecommunications, genetic engineering, bioengineering, special processing, modern welding, robotics, energy and electromagnetic wave field is today only a few of the many applications of electronic engineering. This book presents, shortly, a new and original relation (20 and 20') who determines the radius with that, the electron is running around the nucleus of an atom. One utilizes, two times the Lorenz relation, the Niels Bohr generalized equation, and a mass relation, which was deduced from the kinematics energy relation written in two modes: classical and Coulombian. Equalizing the mass relation with Lorenz relation one obtains a form which is a relation between the squared electron speed (v 2 ) and the radius (r). The second relation between v 2 and r was obtained by equalizing the mass of Bohr equation and the mass of Lorenz relation. For a Bohr energetically level (n=a constant value), one determines now two energetically below levels, which form an electronic layer. The author realizes by this a new atomic model, or a new quantum theory, which explains the existence of electron-clouds without spin.Writing the kinematics energy relation in two modes, classical and Coulombian one determines a relation, from which explicitely the mass of the electron is determined.

A new atomic model

Energy Technology Data Exchange (ETDEWEB)

Petrescu, Florian Ion

2012-07-01

The movement of an electron around the atomic nucleus has today a great importance in many engineering fields. Electronics, aeronautics, micro and nanotechnology, electrical engineering, optics, lasers, nuclear power, computing, equipment and automation, telecommunications, genetic engineering, bioengineering, special processing, modern welding, robotics, energy and electromagnetic wave field is today only a few of the many applications of electronic engineering. This book presents, shortly, a new and original relation (20 and 20') who determines the radius with that, the electron is running around the nucleus of an atom. One utilizes, two times the Lorenz relation, the Niels Bohr generalized equation, and a mass relation, which was deduced from the kinematics energy relation written in two modes: classical and Coulombian. Equalizing the mass relation with Lorenz relation one obtains a form which is a relation between the squared electron speed (v{sup 2}) and the radius (r). The second relation between v{sup 2} and r was obtained by equalizing the mass of Bohr equation and the mass of Lorenz relation. For a Bohr energetically level (n=a constant value), one determines now two energetically below levels, which form an electronic layer. The author realizes by this a new atomic model, or a new quantum theory, which explains the existence of electron-clouds without spin.Writing the kinematics energy relation in two modes, classical and Coulombian one determines a relation, from which explicitely the mass of the electron is determined.

Loss of Asxl1 Alters Self-Renewal and Cell Fate of Bone Marrow Stromal Cell, Leading to Bohring-Opitz-like Syndrome in Mice.

Science.gov (United States)

Zhang, Peng; Xing, Caihong; Rhodes, Steven D; He, Yongzheng; Deng, Kai; Li, Zhaomin; He, Fuhong; Zhu, Caiying; Nguyen, Lihn; Zhou, Yuan; Chen, Shi; Mohammad, Khalid S; Guise, Theresa A; Abdel-Wahab, Omar; Xu, Mingjiang; Wang, Qian-Fei; Yang, Feng-Chun

2016-06-14

De novo ASXL1 mutations are found in patients with Bohring-Opitz syndrome, a disease with severe developmental defects and early childhood mortality. The underlying pathologic mechanisms remain largely unknown. Using Asxl1-targeted murine models, we found that Asxl1 global loss as well as conditional deletion in osteoblasts and their progenitors led to significant bone loss and a markedly decreased number of bone marrow stromal cells (BMSCs) compared with wild-type littermates. Asxl1(-/-) BMSCs displayed impaired self-renewal and skewed differentiation, away from osteoblasts and favoring adipocytes. RNA-sequencing analysis revealed altered expression of genes involved in cell proliferation, skeletal development, and morphogenesis. Furthermore, gene set enrichment analysis showed decreased expression of stem cell self-renewal gene signature, suggesting a role of Asxl1 in regulating the stemness of BMSCs. Importantly, re-introduction of Asxl1 normalized NANOG and OCT4 expression and restored the self-renewal capacity of Asxl1(-/-) BMSCs. Our study unveils a pivotal role of ASXL1 in the maintenance of BMSC functions and skeletal development. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

The Legnaro National Laboratories and the SPES facility: nuclear structure and reactions today and tomorrow

International Nuclear Information System (INIS)

De Angelis, Giacomo; Fiorentini, Gianni

2016-01-01

There is a very long tradition of studying nuclear structure and reactions at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (Italian Institute of Nuclear Physics). The wide expertise acquired in building and running large germanium arrays has made the laboratories one of the most advanced research centers in γ -ray spectroscopy. The ’gamma group’ has been deeply involved in all the national and international developments of the last 20 years and is currently one of the major contributors to the AGATA project, the first (together with its American counterpart GRETINA) γ -detector array based on γ -ray tracking. This line of research is expected to be strongly boosted by the coming into operation of the SPES radioactive ion beam project, currently under construction at LNL. In this report, written on the occasion of the 40th anniversary of the Nobel prize awarded to Aage Bohr, Ben R Mottelson and Leo Rainwater and particularly focused on the physics of nuclear structure, we intend to summarize the different lines of research that have guided nuclear structure and reaction research at LNL in the last decades. The results achieved have paved the way for the present SPES facility, a new laboratories infrastructure producing and accelerating radioactive ion beams of fission fragments and other isotopes. (invited comment)

The Legnaro National Laboratories and the SPES facility: nuclear structure and reactions today and tomorrow

Science.gov (United States)

de Angelis, Giacomo; Fiorentini, Gianni

2016-11-01

There is a very long tradition of studying nuclear structure and reactions at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (Italian Institute of Nuclear Physics). The wide expertise acquired in building and running large germanium arrays has made the laboratories one of the most advanced research centers in γ-ray spectroscopy. The ’gamma group’ has been deeply involved in all the national and international developments of the last 20 years and is currently one of the major contributors to the AGATA project, the first (together with its American counterpart GRETINA) γ-detector array based on γ-ray tracking. This line of research is expected to be strongly boosted by the coming into operation of the SPES radioactive ion beam project, currently under construction at LNL. In this report, written on the occasion of the 40th anniversary of the Nobel prize awarded to Aage Bohr, Ben R Mottelson and Leo Rainwater and particularly focused on the physics of nuclear structure, we intend to summarize the different lines of research that have guided nuclear structure and reaction research at LNL in the last decades. The results achieved have paved the way for the present SPES facility, a new laboratories infrastructure producing and accelerating radioactive ion beams of fission fragments and other isotopes.

O modelo atômico de Bohr e as suas limitações na interpretação do espectro do átomo de hélio

Directory of Open Access Journals (Sweden)

Danielle Nicolodelli Tenfen

2017-05-01

Full Text Available A inserção de tópicos de física moderna e contemporânea na Educação Básica já não é mais algo tão distante. Os livros didáticos aprovados no último Plano Nacional contemplam, de formas distintas, discussões a esse respeito. Porém, sabe-se que a efetiva implementação desses conteúdos em sala de aula depende da formação – tanto conceitual quanto pedagógica – dos professores. Nesse sentido, o presente artigo visa contribuir com professores e estudantes de graduação em Física, apresentando um breve delineamento histórico que enfatiza o contexto de surgimento do modelo atômico de Niels Bohr, conhecido por situar-se em um período de transição entre Física Clássica e Moderna. Ainda, mostram-se detalhadamente as limitações do modelo de Bohr, evidenciando a necessidade das explicações oriundas da nova Mecânica Quântica para uma descrição adequada do espectro do átomo de hélio. Por fim, apresenta-se uma proposta experimental que consiste na construção de um espectroscópio de baixo custo e problematizam-se alguns dados coletados a partir desse aparato.

Studying the Consistency between and within the Student Mental Models for Atomic Structure

Science.gov (United States)

Zarkadis, Nikolaos; Papageorgiou, George; Stamovlasis, Dimitrios

2017-01-01

Science education research has revealed a number of student mental models for atomic structure, among which, the one based on Bohr's model seems to be the most dominant. The aim of the current study is to investigate the coherence of these models when students apply them for the explanation of a variety of situations. For this purpose, a set of…

Conference: STANDARD MODEL @ LHC

CERN Multimedia

2012-01-01

HCØ institute Universitetsparken 5 DK-2100 Copenhagen Ø Denmark Room: Auditorium 2 STANDARD MODEL @ LHC Niels Bohr International Academy and Discovery Center 10-13 April 2012 This four day meeting will bring together both experimental and theoretical aspects of Standard Model phenomenology at the LHC. The very latest results from the LHC experiments will be under discussion. Topics covered will be split into the following categories:     * QCD (Hard,Soft & PDFs)     * Vector Boson production     * Higgs searches     * Top Quark Physics     * Flavour physics

Relation between the location of elements in the Thomsen-Bohr type periodic table and lysosomal accumulation in tumor and liver

International Nuclear Information System (INIS)

Ando, Atsushi; Ando, Itsuko

1989-01-01

This study was undertaken to evaluate the lysosomal accumulation of radioactive metal ions in tumor and liver, using tumor-bearing animals. From the experimental of lysosomal accumulation and binding substance for nineteen radioactive metal ions, the following results were obtained. Hard and borderline acids which have incomplete d-shells accumulated extensively in lysosomes of tumor and liver with time after administration of these ions. They were bound in these tissues to the acid mucopolysaccharides whose molecular weights exceed 40,000 daltons. Trivalent hard acids (Ga 3+ , In 3+ , Yb 3+ , Tm 3+ ) which have complete d-shells accumulated extensively in the lysosomes of liver, but very little in lysososmes of tumor, and were bound to the acid mucopolysaccharide with a molecular weight of about 10,000 daltons in tissues. It was clear based on these results and the facts reported previously that a very interesting relationship existed between the location of elements in the Thomsen-Bohr type periodic table and the lysosomal accumulation of metal ions

Big Atoms for Small Children: Building Atomic Models from Common Materials to Better Visualize and Conceptualize Atomic Structure

Science.gov (United States)

Cipolla, Laura; Ferrari, Lia A.

2016-01-01

A hands-on approach to introduce the chemical elements and the atomic structure to elementary/middle school students is described. The proposed classroom activity presents Bohr models of atoms using common and inexpensive materials, such as nested plastic balls, colored modeling clay, and small-sized pasta (or small plastic beads).

Epistemology and Rosen's Modeling Relation

International Nuclear Information System (INIS)

Dress, W.B.

1999-01-01

Rosen's modeling relation is embedded in Popper's three worlds to provide an heuristic tool for model building and a guide for thinking about complex systems. The utility of this construct is demonstrated by suggesting a solution to the problem of pseudo science and a resolution of the famous Bohr-Einstein debates. A theory of bizarre systems is presented by an analogy with entangled particles of quantum mechanics. This theory underscores the poverty of present-day computational systems (e.g., computers) for creating complex and bizarre entities by distinguishing between mechanism and organism

Microscopic descriptions of the superdeformed bands in the region A 190: Bohr and Routhian Hamiltonians in the Hartree-Fock-Bogolyubov approximation; Descriptions microscopiques des bandes superdeformees dans la region A 190: Hamiltonien de Bohr et Routhian a l`approximation de Hartee-Fock-Bogolyubov

Energy Technology Data Exchange (ETDEWEB)

Libert, J. [Centre d`Etudes Nucleaires, Bordeaux-1 Univ., 33 Gradignan (France); Girod, M.; Delaroche, J-P.; Berger, J-F.; Romain, P.; Peru, S. [CEA Centre d`Etudes de Bruyeres-le-Chatel, 91 (France)

1997-06-01

The superdeformed bands of the nuclei in the region A = 190 were described by two microscopic approaches using Gogny D1 finite range interaction. The first one consists in building a Bohr Hamiltonian in the framework of Gauss overlap approximation (GOA) of the generator-coordinate method, starting from Hartree-Fock-Bogolyubov solutions under quadrupole constraints. This collective Hamiltonian microscopically determined for five quadrupolar variables is then diagonalized by a projection method on a collective based adapted to the large variety of the deformations to be considered. A special attention was given to the precise definition of the under-barrier collective wavefunctions (for which an original method of solving the collective Schroedinger equation was developed) in order to described correctly the lifetime of the shape isomeric states. The other approach, that of Routhian is based also on the Hartree-Fock-Bogolyubov approximation. The calculations are carried out with and without restoring the broken symmetry associated to the particle numbers (as given by Lipkin-Nogami). The results (excitation energies, moments of inertia, etc...) of the two calculation methods are compared with most recent experimental data. The existence of the superdeformed bands corresponding to vibrational excitations similar to those appearing in {beta} and {gamma} bands is proposed

New level schemes with high-spin states of 105,107,109Tc

International Nuclear Information System (INIS)

Luo, Y.X.; Rasmussen, J.O.; Lee, I.Y.; Fallon, P.; Hamilton, J.H.; Ramayya, A.V.; Hwang, J.K.; Gore, P.M.; Zhu, S.J.; Wu, S.C.; Ginter, T.N.; Ter-Akopian, G.M.; Daniel, A.V.; Stoyer, M.A.; Donangelo, R.; Gelberg, A.

2004-01-01

New level schemes of odd-Z 105,107,109 Tc are proposed based on the 252 Cf spontaneous-fission-gamma data taken with Gammasphere in 2000. Bands of levels are considerably extended and expanded to show rich spectroscopic information. Spin/parity and configuration assignments are made based on determinations of multipolarities of low-lying transitions and the level analogies to the previously reported levels, and to those of the neighboring Rh isotopes. A non-yrast negative-parity band built on the 3/2 - [301] orbital is observed for the first time in 105 Tc. A positive-parity band built on the 1/2 + [431] intruder orbital originating from the π(g 7/2 /d 5/2 ) subshells and having a strong deformation-driving effect is observed for the first time in 105 Tc, and assigned in 107 Tc. A positive-parity band built on the excited 11/2 + level, which has rather low excitation energy and predominantly decays into the 9/2 + level of the ground state band, provides evidence of triaxiality in 107,109 Tc, and probably also in 105 Tc. Rotational constants are calculated and discussed for the K=1/2 intruder bands using the Bohr-Mottelson formula. Level systematics are discussed in terms of the locations of proton Fermi levels and deformations. The band crossings of yrast positive-parity bands are observed, most likely related to h 11/2 neutron alignment. Triaxial-rotor-plus-particle model calculations performed with ε=0.32 and γ=-22.5 deg. on the prolate side of maximum triaxiality yielded the best reproduction of the excitation energies, signature splittings, and branching ratios of the positive-parity bands (except for the intruder bands) of these Tc isotopes. The significant discrepancies between the triaxial-rotor-plus-particle model calculations and experiment for the K=1/2 intruder bands in 105,107 Tc need further theoretical studies

Validity of single term energy expression for ground state rotational band of even-even nuclei

International Nuclear Information System (INIS)

Sharma, S.; Kumar, R.; Gupta, J.B.

2005-01-01

Full text: There are large numbers of empirical studies of gs band of even-even nuclei in various mass regions. The Bohr-Mottelson's energy expression is E(I) = AX + BX 2 +CX 3 +... where X = I(I+1). The anharmonic vibrator energy expression is: E(I) = al + bl 2 + cl 3 SF model with energy expression: E(I)= pX + qI + rXI... where the terms represents the rotational, vibrational and R-V interaction energy, respectively. The validity f the various energy expressions with two terms had been tested by Sharma for light, medium and heavy mass regions using R I s. R 4 plots (where, spin I=6, 8, 10, 12), which are parameter independent. It was also noted, that of the goodness of energy expression can be judged with the minimum input of energies (i.e. only 2 parameters) and predictability's of the model p to high spins. Recently, Gupta et. al proposed a single term energy expression (SSTE) which was applied for rare earth region. This proposed power law reflected the unity of rotation - vibration in a different way and was successful in explaining the structure of gs-band. It will be useful for test the single term energy expression for light and heavy mass region. The single term expression for energy of ground state band can be written as: E I =axI b , where the index b and the coefficient a are the constant for the band. The values of b+1 and a 1 are as follows: b 1 =log(R 1 )/log(I/2) and a 1 =E I /I b ... The following results were gained: 1) The sharp variation in the value of index b at given spin will be an indication of the change in the shape of the nucleus; 2) The value of E I /I b is fairly constant with spin below back-bending, which reflects the stability of shape with spin; 3) This proposed power law is successful in explaining the structure of gs-band of nuclei

Epistemology and Rosen's Modeling Relation

Energy Technology Data Exchange (ETDEWEB)

Dress, W.B.

1999-11-07

Rosen's modeling relation is embedded in Popper's three worlds to provide an heuristic tool for model building and a guide for thinking about complex systems. The utility of this construct is demonstrated by suggesting a solution to the problem of pseudo science and a resolution of the famous Bohr-Einstein debates. A theory of bizarre systems is presented by an analogy with entangled particles of quantum mechanics. This theory underscores the poverty of present-day computational systems (e.g., computers) for creating complex and bizarre entities by distinguishing between mechanism and organism.

Statistics and the shell model

International Nuclear Information System (INIS)

Weidenmueller, H.A.

1985-01-01

Starting with N. Bohr's paper on compound-nucleus reactions, we confront regular dynamical features and chaotic motion in nuclei. The shell-model and, more generally, mean-field theories describe average nuclear properties which are thus identified as regular features. The fluctuations about the average show chaotic behaviour of the same type as found in classical chaotic systems upon quantisation. These features are therefore generic and quite independent of the specific dynamics of the nucleus. A novel method to calculate fluctuations is discussed, and the results of this method are described. (orig.)

A new spin on nuclei

International Nuclear Information System (INIS)

Clark, R.; Wadsworth, B.

1998-01-01

Magnetic rotation is a new phenomenon that is forcing physicists to rethink their understanding of what goes on inside the nucleus The rotation of quantum objects has a long and distinguished history in physics. In 1912 the Danish scientist Niels Bjerrum was the first to recognize that the rotation of molecules is quantized. In 1938 Edward Teller and John Wheeler observed similar features in the spectra of excited nuclei, and suggested that this was caused by the nucleus rotating. But a more complete explanation had to wait until 1951, when Aage Bohr (the son of Niels) pointed out that rotation was a consequence of the nucleus deforming from its spherical shape. We owe much of our current understanding of nuclear rotation to the work of Bohr and Ben Mottelson, who shared the 1975 Nobel Prize for Physics with James Rainwater for developing a model of the nucleus that combined the individual and collective motions of the neutrons and protons inside the nucleus. What makes it possible for a nucleus to rotate? Quantum mechanically, a perfect sphere cannot rotate because it appears the same when viewed from any direction and there is no point of reference against which its change in position can be detected. To see the rotation the spherical symmetry must be broken to allow an orientation in space to be defined. For example, a diatomic molecule, which has a dumbbell shape, can rotate about the two axes perpendicular to its axis of symmetry. A quantum mechanical treatment of a diatomic molecule leads to a very simple relationship between rotational energy, E, and angular momentum. This energy is found to be proportional to J(J + 1), where J is the angular momentum quantum number. The molecule also has a magnetic moment that is proportional to J. These concepts can be applied to the atomic nucleus. If the distribution of mass and/or charge inside the nucleus becomes non-spherical then the nucleus will be able to rotate. The rotation is termed ''collective'' because many

Systematics of B(E2;01+→21+) values for even-even nuclei

International Nuclear Information System (INIS)

Raman, S.; Nestor, C.W. Jr.; Bhatt, K.H.

1988-01-01

We have completed a compilation of experimental results for the electric quadrupole transition probability B(E2)up-arrow between the 0 + ground state and the first 2 + state in even-even nuclei. The adopted B(E2)up-arrow values have been employed to test the various systematic, empirical, and theoretical relationships proposed by several authors (Grodzins, Bohr and Mottelson, Wang et al., Ross and Bhaduri, Patnaik et al., Hamamoto, Casten, Moeller and Nix, and Kumar) on a global, local, or regional basis. These systematics offer methods for making reasonable predictions of unmeasured B(E2) values. For nuclei away from closed shells, the SU(3) limit of the intermediate boson approximation implies that the B(E2)up-arrow values are proportional to (e/sub p/N/sub p/+e/sub n/N/sub n/) 2 , where e/sub p /(e/sub n/) is the proton (neutron) effective charge and N/sub p/ (N/sub n/) refers to the number of valence protons (neutrons). This proportionality is consistent with the observed behavior of B(E2)up-arrow vs N/sub p/N/sub n/. For deformed nuclei and the actinides, the B(E2)up-arrow values calculated in a schematic single-particle ''SU(3)'' simulation or large single-j simulation of major shells successfully reproduce not only the empirical variation of the B(E2)up-arrow values but also the observed saturation of these values when plotted against N/sub p/N/sub n/. .AE

Atoms – How Small, and How Large!

Indian Academy of Sciences (India)

IAS Admin

found in the Bohr atom model, the birth centenary of which is celebrated in the year 2013. Neils Bohr intro- duced in his model the quantization (occurrence of dis- ... free or isolated H-atom is of the order of 1 Å = 10. −10 m. The quantity a0 is quite fundamental and it serves as a unit of length in the atomic–molecular physics.

Hydrodynamic model wavefunctions in intrinsic coordinates and their application to the structure of even-even nuclei

International Nuclear Information System (INIS)

Margetan, F.J.

1979-01-01

A closed expression is presented for intrinsic-coordinate (β, γ, theta/sub i/) eigenfunctions of the hydrodynamic, quadrupole-vibration Hamiltonian of A. Bohr. These functions are used as an expansion basis for the treatment of more general collective Hamiltonians. Two classes of such Hamiltonians are considered. In each the potential energy term of the Bohr Hamiltonian, 1/2 Cβ 2 , was replaced with a more general function of the shape coordinates, V(β, γ). The potential of Gneuss and Greiner (1) is used to demonstrate the soundness of the calculational techniques, and to illustrate convergence properties of calculated energies. Potentials possessing a single minimum on 0 less than or equal to γ less than or equal to 60 0 are considered through the study of a quadratic-potential [QP] Hamiltonian. The smooth development from spherical to asymmetrically deformed nuclear shapes is investigated by systematically varying the parameters β 0 and C/sub γ/. Model energies and E2 transition rates are traced during this process. The QP model is then applied to 106 Pd, 166 Er, 182 W, 122 Te, and 186 188 190 192 Os. Low-energy γ vibrations appear to play a prominent role in the latter five nuclei, and the QP model offers a better accounting of experimental spectra than does the model of Davydov and Chaban (2). 74 references

Alternate model of Chladni figures for the circular homogenous thin plate case with open boundaries

International Nuclear Information System (INIS)

Trejo-Mandujano, H A; Mijares-Bernal, G; Ordoñez-Casanova, E G

2015-01-01

The wave equation is a direct but a complex approach to solve analytically for the Chladni figures, mainly because of the complications that non-smooth and open boundary conditions impose. In this paper, we present an alternate solution model based on the principle of Huygens-Fresnel and on the ideas of Bohr for the hydrogen atom. The proposed model has been implemented numerically and compared, with good agreement, to our own experimental results for the case of a thin homogenous circular plate with open boundaries

Microscopic descriptions of the superdeformed bands in the region A 190: Bohr and Routhian Hamiltonians in the Hartree-Fock-Bogolyubov approximation

International Nuclear Information System (INIS)

Libert, J.; Girod, M.; Delaroche, J-P.; Berger, J-F.; Romain, P.; Peru, S.

1997-01-01

The superdeformed bands of the nuclei in the region A = 190 were described by two microscopic approaches using Gogny D1 finite range interaction. The first one consists in building a Bohr Hamiltonian in the framework of Gauss overlap approximation (GOA) of the generator-coordinate method, starting from Hartree-Fock-Bogolyubov solutions under quadrupole constraints. This collective Hamiltonian microscopically determined for five quadrupolar variables is then diagonalized by a projection method on a collective based adapted to the large variety of the deformations to be considered. A special attention was given to the precise definition of the under-barrier collective wavefunctions (for which an original method of solving the collective Schroedinger equation was developed) in order to described correctly the lifetime of the shape isomeric states. The other approach, that of Routhian is based also on the Hartree-Fock-Bogolyubov approximation. The calculations are carried out with and without restoring the broken symmetry associated to the particle numbers (as given by Lipkin-Nogami). The results (excitation energies, moments of inertia, etc...) of the two calculation methods are compared with most recent experimental data. The existence of the superdeformed bands corresponding to vibrational excitations similar to those appearing in β and γ bands is proposed

Calculation of M1-excitations in the 42Ca, 44Ca and 54Fe with allowance for the 1p 1h * phonon configurations

International Nuclear Information System (INIS)

Kamerdzhiev, S.P.; Tkachev, V.N.

1988-01-01

The microscopic model of account of 1p1hx phonon configurations is used to describe M1-excitations in 42 Ca, 44 Ca and 54 Fe 1f 7/2 -shell. The most low-lying and more collectivized electrical phonons are taken into account. The Boron-Mottelson collective model with parameters obtained in the experiment is used to describe them. The calculation results are compared with calculations on other models. A set of all data allows to make the supposition that the deficient part of M1-resonance force in nuclei of 1f 7/2 -shell should be distributed on low-intensive 1 + -levels in the wide range of the nucleon binding energy

The algebraic collective model

International Nuclear Information System (INIS)

Rowe, D.J.; Turner, P.S.

2005-01-01

A recently proposed computationally tractable version of the Bohr collective model is developed to the extent that we are now justified in describing it as an algebraic collective model. The model has an SU(1,1)xSO(5) algebraic structure and a continuous set of exactly solvable limits. Moreover, it provides bases for mixed symmetry collective model calculations. However, unlike the standard realization of SU(1,1), used for computing beta wave functions and their matrix elements in a spherical basis, the algebraic collective model makes use of an SU(1,1) algebra that generates wave functions appropriate for deformed nuclei with intrinsic quadrupole moments ranging from zero to any large value. A previous paper focused on the SO(5) wave functions, as SO(5) (hyper-)spherical harmonics, and computation of their matrix elements. This paper gives analytical expressions for the beta matrix elements needed in applications of the model and illustrative results to show the remarkable gain in efficiency that is achieved by using such a basis in collective model calculations for deformed nuclei

Absolute charge-changing cross sections for fast helium ions-C sub 6 sub 0 collisions

CERN Document Server

Nose, K; Shiraishi, K; Keizaki, T; Itoh, A

2003-01-01

Absolute charge-changing cross sections for fast helium ions passing through a C sub 6 sub 0 gas target have been measured. The measurements were carried out for incident projectile energies at 1.0MeV and 1.5MeV. The measured cross sections are compared with calculated values from Bohr-Lindhard model and Bohr model. In addition, we have obtained equilibrium charge state fractions and average equilibrium charge of helium ions passing through C sub 6 sub 0 , by using the measured cross sections.

Equilibrium fission model calculations

International Nuclear Information System (INIS)

Beckerman, M.; Blann, M.

1976-01-01

In order to aid in understanding the systematics of heavy ion fission and fission-like reactions in terms of the target-projectile system, bombarding energy and angular momentum, fission widths are calculated using an angular momentum dependent extension of the Bohr-Wheeler theory and particle emission widths using angular momentum coupling

17th Poincaré Seminar 2013

CERN Document Server

Duplantier, Bertrand; Raimond, Jean-Michel; Rivasseau, Vincent

2016-01-01

This fourteenth volume in the Poincaré Seminar Series is devoted to Niels Bohr, his foundational contributions to understanding atomic structure and quantum theory and their continuing importance today. This book contains the following chapters: - Tomas Bohr, Keeping Things Open; - Olivier Darrigol, Bohr's Trilogy of 1913; -John Heilbron, The Mind that Created the Bohr Atom; - Serge Haroche & Jean-Michel Raimond, Bohr's Legacy in Cavity QED; - Alain Aspect, From Einstein, Bohr, Schrödinger to Bell and Feynman: a New Quantum Revolution?; - Antoine Browaeys, Interacting Cold Rydberg Atoms: A Toy Many-Body System; - Michel Bitbol & Stefano Osnaghi, Bohr´s Complementarity and Kant´s Epistemology. Dating from their origin in lectures to a broad scientific audience these seven chapters are of high educational value. This volume is of general interest to physicists, mathematicians and historians.

Theory of collective Hamiltonian

Energy Technology Data Exchange (ETDEWEB)

Zhang Qingying

1982-02-01

Starting from the cranking model, we derive the nuclear collective Hamiltonian. We expand the total energy of the collective motion of the ground state of even--even nuclei in powers of the deformation parameter ..beta... In the first approximation, we only take the lowest-order non-vanished terms in the expansion. The collective Hamiltonian thus obtained rather differs from the A. Bohr's Hamiltonian obtained by the irrotational incompressible liquid drop model. If we neglect the coupling term between ..beta..-and ..gamma..-vibration, our Hamiltonian then has the same form as that of A. Bohr. But there is a difference between these collective parameters. Our collective parameters are determined by the state of motion of the nucleous in the nuclei. They are the microscopic expressions. On the contrary, A. Bohr's collective parameters are only the simple functions of the microscopic physical quantities (such as nuclear radius and surface tension, etc.), and independent of the state of motion of the nucleons in the nuclei. Furthermore, there exist the coupling term between ..beta..-and ..gamma..-vibration and the higher-order terms in our expansion. They can be treated as the perturbations. There are no such terms in A. Bohr's Hamiltonian. These perturbation terms will influence the rotational, vibrational spectra and the ..gamma..-transition process, etc.

The τ-compression effect in γ-soft nulei

International Nuclear Information System (INIS)

Pan, X.W.; Feng, D.H.

1993-01-01

It is shown that a particular deviation from the SO(5) level structure persists in most well known SO(6)-like nuclei, namely, the τ-dependent compression of levels in the gamma-soft nuclei. This compression can be regarded as an extention of Mottelson-Valatin effect in the SO(5) scheme, i.e.. The reduction of pairing interaction with the increasing of τ-number will cause a compression in the energy levels. We find that this phenomenon can be effectively explained in terms of the SO(6) plus Pairing model. Using the pairing term to perturb the SO(6) Hamiltonian, a new level regularity for the SO(5) scheme is obtained

Investigation of the spectroscopy properties of deformed nuclei by combining the X(3) and E(5) models

Energy Technology Data Exchange (ETDEWEB)

Alimohammadi, M.; Hassanabadi, H. [Shahrood University of Technology, Physics Department, Shahrood (Iran, Islamic Republic of)

2017-06-15

In this paper, we present a model which is composed of two parts related to the special critical points, E(5) (the phase transition between spherical oscillator and γ-soft) and X(3) (a γ-rigid version of X(5)). This model is studied to investigate the interplay situations by the free parameter χ. These situations are cited between the γ-unstable and γ-rigid version of the Bohr Hamiltonian. The corresponding wave equation has been considered and the eigenvalues as well as eigenfunctions have been determined by solving this equation. Moreover, we have calculated the energy spectra and transition rates in order to compare our results with experimental data. (orig.)

Communication: Wigner functions in action-angle variables, Bohr-Sommerfeld quantization, the Heisenberg correspondence principle, and a symmetrical quasi-classical approach to the full electronic density matrix

International Nuclear Information System (INIS)

Miller, William H.; Cotton, Stephen J.

2016-01-01

It is pointed out that the classical phase space distribution in action-angle (a-a) variables obtained from a Wigner function depends on how the calculation is carried out: if one computes the standard Wigner function in Cartesian variables (p, x), and then replaces p and x by their expressions in terms of a-a variables, one obtains a different result than if the Wigner function is computed directly in terms of the a-a variables. Furthermore, the latter procedure gives a result more consistent with classical and semiclassical theory—e.g., by incorporating the Bohr-Sommerfeld quantization condition (quantum states defined by integer values of the action variable) as well as the Heisenberg correspondence principle for matrix elements of an operator between such states—and has also been shown to be more accurate when applied to electronically non-adiabatic applications as implemented within the recently developed symmetrical quasi-classical (SQC) Meyer-Miller (MM) approach. Moreover, use of the Wigner function (obtained directly) in a-a variables shows how our standard SQC/MM approach can be used to obtain off-diagonal elements of the electronic density matrix by processing in a different way the same set of trajectories already used (in the SQC/MM methodology) to obtain the diagonal elements.

Communication: Wigner functions in action-angle variables, Bohr-Sommerfeld quantization, the Heisenberg correspondence principle, and a symmetrical quasi-classical approach to the full electronic density matrix.

Science.gov (United States)

Miller, William H; Cotton, Stephen J

2016-08-28

It is pointed out that the classical phase space distribution in action-angle (a-a) variables obtained from a Wigner function depends on how the calculation is carried out: if one computes the standard Wigner function in Cartesian variables (p, x), and then replaces p and x by their expressions in terms of a-a variables, one obtains a different result than if the Wigner function is computed directly in terms of the a-a variables. Furthermore, the latter procedure gives a result more consistent with classical and semiclassical theory-e.g., by incorporating the Bohr-Sommerfeld quantization condition (quantum states defined by integer values of the action variable) as well as the Heisenberg correspondence principle for matrix elements of an operator between such states-and has also been shown to be more accurate when applied to electronically non-adiabatic applications as implemented within the recently developed symmetrical quasi-classical (SQC) Meyer-Miller (MM) approach. Moreover, use of the Wigner function (obtained directly) in a-a variables shows how our standard SQC/MM approach can be used to obtain off-diagonal elements of the electronic density matrix by processing in a different way the same set of trajectories already used (in the SQC/MM methodology) to obtain the diagonal elements.

Communication: Wigner functions in action-angle variables, Bohr-Sommerfeld quantization, the Heisenberg correspondence principle, and a symmetrical quasi-classical approach to the full electronic density matrix

Energy Technology Data Exchange (ETDEWEB)

Miller, William H., E-mail: millerwh@berkeley.edu; Cotton, Stephen J., E-mail: StephenJCotton47@gmail.com [Department of Chemistry and Kenneth S. Pitzer Center for Theoretical Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2016-08-28

It is pointed out that the classical phase space distribution in action-angle (a-a) variables obtained from a Wigner function depends on how the calculation is carried out: if one computes the standard Wigner function in Cartesian variables (p, x), and then replaces p and x by their expressions in terms of a-a variables, one obtains a different result than if the Wigner function is computed directly in terms of the a-a variables. Furthermore, the latter procedure gives a result more consistent with classical and semiclassical theory—e.g., by incorporating the Bohr-Sommerfeld quantization condition (quantum states defined by integer values of the action variable) as well as the Heisenberg correspondence principle for matrix elements of an operator between such states—and has also been shown to be more accurate when applied to electronically non-adiabatic applications as implemented within the recently developed symmetrical quasi-classical (SQC) Meyer-Miller (MM) approach. Moreover, use of the Wigner function (obtained directly) in a-a variables shows how our standard SQC/MM approach can be used to obtain off-diagonal elements of the electronic density matrix by processing in a different way the same set of trajectories already used (in the SQC/MM methodology) to obtain the diagonal elements.

Energy shifts in the binary encounter peak of 0.5 MeV/amu Cuq+ +H2

International Nuclear Information System (INIS)

Hidmi, H.I.; Richard, P.; Sanders, J.M.; Zouros, T.J.M.

1993-01-01

The energy shifts from the classical prediction in the binary encounter peak of Cu q+ as a function of the charge state q has been experimentally measured. The data showed that this shift increases by increasing the charge state of the projectile. We fitted the energy shift to an equation of the form ΔE=aq n and obtained a value for the exponent n. The data is also compared to the Bohr-Lindhard calculation which predicts an exponent n=0.5. Good agreement was found between our data and the Bohr-Lindhard model

Hartree-Fock theory for the equilibrium shape of light nuclei; Theorie Hartree-Fock de la forme d'equilibre des noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Ripka, G. [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

1968-09-01

Most of the content of this thesis is published in english in Advances In Nuclear Physics, Vol. 1 (Editors: Baranger and Vogt - Plenum Press). The Hartree- Fock equations are derived. The expansions of the orbits and the possible symmetries of the Hartree-Fock field are discussed. Wavefunctions of even-even N = Z nuclei are given for 12 {<=} A {<=} 40. The role of the monopole, quadrupole and exchange components of the force are discussed. The multiplicity of the solutions and the effect of the spin-orbit interaction are discussed. Exact angular momentum projection is used to generate rotational bands. The validity of the adiabatic rotational model in light nuclei is discussed. Hartree-Fock calculations are extended to include major-shell mixing in order to obtain quadrupole deformations without the use of effective charge. The incompressibility, of nuclei is discussed and the compatibility between the Hartree-Fock solutions, the Mottelson model of quadrupole deformations and the SU3 states of J.P. Elliott and M. Moshinsky is established. (author) [French] La theorie de Hartree-Fock est appliquee au calcul des fonctions d'onde des noyaux legers deformes. Les equations de Hartree-Fock, les symetries permises et le choix du developpement des orbites sont discutes. Les fonctions d'onde des noyaux pair-pairs N = Z (12 {<=} A {<=} 40) sont tabulees. Les contributions des composantes monopolaires et quadrupolaires ainsi que des termes d'echange de la force nucleon-nucleon sont discutees. La methode de projection de moment cinetique est utilisee pour engendrer les bandes de rotation. La validite du modele rotationnel adiabatique est discutee. Les calculs de Hartree-Fock qui tiennent compte du melange de plusieurs couches majeures dans chaque orbite sont appliques au calcul des deformations quadrupolaires sans l'utilisation de charge effective. L'incompressibilite des noyaux et la compatibilite des fonctions d'onde de Hartree- Fock avec les

Hartree-Fock theory for the equilibrium shape of light nuclei; Theorie Hartree-Fock de la forme d'equilibre des noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Ripka, G [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

1968-09-01

Most of the content of this thesis is published in english in Advances In Nuclear Physics, Vol. 1 (Editors: Baranger and Vogt - Plenum Press). The Hartree- Fock equations are derived. The expansions of the orbits and the possible symmetries of the Hartree-Fock field are discussed. Wavefunctions of even-even N = Z nuclei are given for 12 {<=} A {<=} 40. The role of the monopole, quadrupole and exchange components of the force are discussed. The multiplicity of the solutions and the effect of the spin-orbit interaction are discussed. Exact angular momentum projection is used to generate rotational bands. The validity of the adiabatic rotational model in light nuclei is discussed. Hartree-Fock calculations are extended to include major-shell mixing in order to obtain quadrupole deformations without the use of effective charge. The incompressibility, of nuclei is discussed and the compatibility between the Hartree-Fock solutions, the Mottelson model of quadrupole deformations and the SU3 states of J.P. Elliott and M. Moshinsky is established. (author) [French] La theorie de Hartree-Fock est appliquee au calcul des fonctions d'onde des noyaux legers deformes. Les equations de Hartree-Fock, les symetries permises et le choix du developpement des orbites sont discutes. Les fonctions d'onde des noyaux pair-pairs N = Z (12 {<=} A {<=} 40) sont tabulees. Les contributions des composantes monopolaires et quadrupolaires ainsi que des termes d'echange de la force nucleon-nucleon sont discutees. La methode de projection de moment cinetique est utilisee pour engendrer les bandes de rotation. La validite du modele rotationnel adiabatique est discutee. Les calculs de Hartree-Fock qui tiennent compte du melange de plusieurs couches majeures dans chaque orbite sont appliques au calcul des deformations quadrupolaires sans l'utilisation de charge effective. L'incompressibilite des noyaux et la compatibilite des fonctions d'onde de Hartree- Fock avec les fonctions d'onde SU3 de J

Classical calculation of the total ionization energy of helium-like atoms

International Nuclear Information System (INIS)

Karastoyanov, A.

1990-01-01

Quantum mechanics rejects the classical modelling of microworld. One of the reasons is that the Bohr's rules can not be applied for many-electron atoms and molecules. But the many-body problem in classical mechanics has no analytical solution even for 3 particles. Numerical solutions should be used. The quantum Bohr's rule expressing the moment of momentum conservation for two particles is invalid in more complicated cases. Yet Bohr reached some success for helium-like atoms. The Bohr's formula concerning helim-like atoms is deduced again in this paper and its practical reliability is analyzed with contemporary data. The binding energy of the system is obtained in the simple form E=(Z-1/4) 2 α 2 mc 2 , where Z is the atomic number, α - the fine structure constant, M - the electron mass and c - the light speed in vacuum. The calculated values are compared with experimental data on the total ionization energy of the helium-like atoms from 2 He 4 to 29 Cu 64 . The error decreases quickly with the increasing of atomic mass, reaching zero for Cu. This indicated that the main source of error is the nucleus motion. The role of other possible causes is analyzed and proves negligible. (author). 1 tab, 4 refs

Nuclear structure at the limits of resolution: Looking through individual wave functions

Energy Technology Data Exchange (ETDEWEB)

Zelevinsky, V.G. [Michigan State Univ., East Lansing, MI (United States)

1996-12-31

60 years ago Niels Bohr suggested the idea of the compound nucleus. Bohr`s picture strongly resembles that of quantum chaos. Here one comes to the limits of resolution studying particular stationary states at high level density. Present knowledge comes from the experiment and from theoretical constructions, confirmed by the experiment at lower energies and extrapolated into the region where fine resolution measurements are not feasible. Such an analysis was carried out recently for heavy atoms and shell model nuclei. Among complicated states with the same values of integrals of motion, either (i) adjacent states have different structure or (ii) they {open_quotes}look the same{close_quotes} on the microscopic scale. Only (ii) corresponds to strong mixing assumed in the compound nucleus theory. Many-body chaos in nuclei is caused by residual interactions rather than by specific shape of the {open_quotes}container{close_quotes} as in quantum billiards. The shell model, including all degrees of freedom (in truncated space) along with the symmetry requirements, guarantees the correct level density up to some excitation energy. Therefore one can extrapolate the calculations into terra incognita of high lying states.

Rutherford and Bohr*

Indian Academy of Sciences (India)

IAS Admin

He was always concerned about hurting any person's feelings, and he found great ... classical picture might be modified by using Planck's quantum of action. A first manuscript .... problem soon was made academic by Rutherford moving to Cambridge. ..... I hope it will not have too much of a reaction on them'. And later: 'I am ...

Creating and Using Interactive, 3D-Printed Models to Improve Student Comprehension of the Bohr Model of the Atom, Bond Polarity, and Hybridization

Science.gov (United States)

Smiar, Karen; Mendez, J. D.

2016-01-01

Molecular model kits have been used in chemistry classrooms for decades but have seen very little recent innovation. Using 3D printing, three sets of physical models were created for a first semester, introductory chemistry course. Students manipulated these interactive models during class activities as a supplement to existing teaching tools for…

Magnetic dipole moments of deformed odd-A nuclei

Energy Technology Data Exchange (ETDEWEB)

Garg, V P; Sharma, S D; Mahesh, P S [Punjabi Univ., Patiala (India). Dept. of Physics

1976-12-01

Using an extended version of A S Davydov and G F Filippov's model (1958), B E Chi and J P Davidson have calculated magnetic moments of odd-A nuclei in 2s-ld shell, diagonalizing the state matrices for a set of parameters giving the best fit for nuclear spectra (1966). To study the failure of this model in case of nuclear moments, instead of diagonalizing an attempt has been made to simplify the expression for magnetic dipole moment for single nucleonic states without configuration mixing. The model takes care of the proper sign of spin projections. On replacing the total angular momentum j of odd particle (proton or neutron) by its projection ..cap omega.., the expression reduces to that of Mottelson and Nilsson for spin-up nuclei. The Coriolis coupling calculations also have been performed for those odd-A nuclei with K = 1/2. The results are found in better agreement with experimental report in comparison with those of other models.

Slowing down of 2–11 MeV {sup 12}C, {sup 16}O, {sup 28}Si and {sup 63}Cu heavy ions through Si{sub 3}N{sub 4} thin foil by using Time-of-Flight spectrometry

Energy Technology Data Exchange (ETDEWEB)

Guesmia, A., E-mail: guesmia@tlabs.ac.za [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Departement de physique, Faculté des Sciences Université Saad Dahleb, B. P. 270, Route de Soumaa, Blida (Algeria); Departement de physique, Faculté des Sciences Université M’hamedBougara, Boumerdes (Algeria); Msimanga, M. [Physics Department, Tshwane University of Technology, P Bag X 680, Pretoria 0001 (South Africa); Pineda-Vargas, C.A. [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Faculty of Health and Wellness Sciences, CPUT, P.O. Box 1906, Bellville 7535 (South Africa); Ammi, H.; Dib, A.; Ster, M. [Centre de Recherche Nucleaire d’Alger, 2 Bd. Frantz Fanon, B. P. 399, Alger-Gare, Algiers (Algeria)

2016-03-15

The stopping force and the energy-loss straggling of {sup 63}Cu, {sup 28}Si, {sup 16}O and {sup 12}C partially stripped heavy ions crossing silicon nitride foil has been determined over a continuous range of energies 2–11 MeV, by using a method based on the Heavy Ion-Elastic Recoil Detection Analysis (HI-ERDA) technique using a Time of Flight (ToF) spectrometer. The obtained energy loss straggling values corrected for non-statistical straggling and the thickness variation using the Besenbacher’s method have been analyzed and compared with the corresponding computed values. For computed electronic straggling we have used alternatively the widely used formulations such as, the universal Bohr straggling deduced from the Bohr stopping model, and the Lindhard–Scharff formula including the Bunching effect given by Hvelplund–Firsov formula according to the Besenbacher approach. The aim of such comparison is to check the reliability and accuracy of the existing energy loss straggling formulations, in the light of the present experimental results. The experimental results of energy loss straggling of all ions are found to be greater than those predicted by the Bohr stopping model or Lindhard–Scharff prediction model. The introduction of the bunching effect improves the comparison and gives an estimation of other effects such as charge exchange.

Beyond the Unified Model

Science.gov (United States)

Frauendorf, S.

2018-04-01

The key elements of the Unified Model are reviewed. The microscopic derivation of the Bohr Hamiltonian by means of adiabatic time-dependent mean field theory is presented. By checking against experimental data the limitations of the Unified Model are delineated. The description of the strong coupling between the rotational and intrinsic degrees of freedom in framework of the rotating mean field is presented from a conceptual point of view. The classification of rotational bands as configurations of rotating quasiparticles is introduced. The occurrence of uniform rotation about an axis that differs from the principle axes of the nuclear density distribution is discussed. The physics behind this tilted-axis rotation, unknown in molecular physics, is explained on a basic level. The new symmetries of the rotating mean field that arise from the various orientations of the angular momentum vector with respect to the triaxial nuclear density distribution and their manifestation by the level sequence of rotational bands are discussed. Resulting phenomena, as transverse wobbling, rotational chirality, magnetic rotation and band termination are discussed. Using the concept of spontaneous symmetry breaking the microscopic underpinning of the rotational degrees is refined.

Relaxation properties in classical diamagnetism

Science.gov (United States)

Carati, A.; Benfenati, F.; Galgani, L.

2011-06-01

It is an old result of Bohr that, according to classical statistical mechanics, at equilibrium a system of electrons in a static magnetic field presents no magnetization. Thus a magnetization can occur only in an out of equilibrium state, such as that produced through the Foucault currents when a magnetic field is switched on. It was suggested by Bohr that, after the establishment of such a nonequilibrium state, the system of electrons would quickly relax back to equilibrium. In the present paper, we study numerically the relaxation to equilibrium in a modified Bohr model, which is mathematically equivalent to a billiard with obstacles, immersed in a magnetic field that is adiabatically switched on. We show that it is not guaranteed that equilibrium is attained within the typical time scales of microscopic dynamics. Depending on the values of the parameters, one has a relaxation either to equilibrium or to a diamagnetic (presumably metastable) state. The analogy with the relaxation properties in the Fermi Pasta Ulam problem is also pointed out.

Molecular bonding in SF6 measured by elastic electron scattering

International Nuclear Information System (INIS)

Miller, J.D.; Fink, M.

1992-01-01

Elastic differential cross-section measurements of gaseous SF 6 were made with 30 keV electrons in the range of 0.25 bohrs -1 ≤s≤10 bohrs -1 . Structural parameters derived in this study closely matched those found in an earlier total (elastic plus inelastic) scattering investigation. Multiple-scattering effects were incorporated in the structural refinement. The discrepancies between the independent atom model and the measured differential cross section reproduce earlier total scattering results for momentum transfers of greater than 5 bohrs -1 . By extending the measurements to smaller s values, a closer examination of a Hartree--Fock calculation for SF 6 was possible. It was found that the difference curve obtained from the Hartree--Fock calculation matched the experimental data in this region. A more quantitative analysis was performed using the analytic expressions of Bonham and Fink to compute moments of the molecular charge distribution from the differential cross-section data. Comparison of these results with similar fits to the Hartree--Fock calculation confirmed the good agreement between the Hartree--Fock calculation and the current elastic data

Atomic structure in black hole

International Nuclear Information System (INIS)

Nagatani, Yukinori

2006-01-01

We propose that any black hole has atomic structure in its inside and has no horizon as a model of black holes. Our proposal is founded on a mean field approximation of gravity. The structure of our model consists of a (charged) singularity at the center and quantum fluctuations of fields around the singularity, namely, it is quite similar to that of atoms. Any properties of black holes, e.g. entropy, can be explained by the model. The model naturally quantizes black holes. In particular, we find the minimum black hole, whose structure is similar to that of the hydrogen atom and whose Schwarzschild radius is approximately 1.1287 times the Planck length. Our approach is conceptually similar to Bohr's model of the atomic structure, and the concept of the minimum Schwarzschild radius is similar to that of the Bohr radius. The model predicts that black holes carry baryon number, and the baryon number is rapidly violated. This baryon number violation can be used as verification of the model. (author)

L’ULTIMO ASSOLUTO DELLA RELATIVITÀ

Directory of Open Access Journals (Sweden)

Andrea Roselli

2014-03-01

Full Text Available Si mostra come la celebre disputa tra Einstein e Bohr riguardi i concetti di realtà retrostanti le loro relative concezioni della realtà fisica; conseguentemente, viene suggerita una significativa connessione tra le teorie di Copenaghen e la relatività einsteiniana. Bohr considerava la descrizione della realtà offerta dalla meccanica quantistica completa; Einstein, al contrario (nonostante il contributo apportato alla sua nascita, continuava a cercare una teoria deterministica. Quando nel 1935 Einstein, Podolsky e Rosen pubblicarono il famoso EPR, Bohr replicò centrando l’attenzione sul ragionevole criterio di realtà proposto dagli autori, rimarcando l’inconsistenza concettuale dell’esistenza indipendente di un costitutivo “inconoscibile”. La fisica, attraverso la grande lezione epistemologica – come era solito dirne Niels Bohr – rappresentata dalla MQ, si trovava di fronte ad una capitale questione filosofica: che cosa è la realtà? Viene infine suggerita una giustapposizione della problematizzazione einsteiniana del concetto di simultaneità e del carattere reciproco delle misurazioni quantomeccaniche esposto da Bohr, che suggerisce l’abbandono dell’ultimo grande assoluto: una realtà assoluta.

Einstein's Materialism and Modern Tests of Quantum Mechanics

Science.gov (United States)

Vigier, J. P.

After a presentation of Einstein's and Bohr's antagonistic point of view on the interpretation of Quantum Mechanics an illustration of their conflicting positions in the particular case of Young's double slit experiment is presented. It is then shown that in their most recent form (i. e. time dependent neutron interferometry) these experiments suggest (if one accepts absolute energymomentum conservation in all individual microprocesses) that Einstein was right in the Bohr-Einstein controversy.Translated AbstractEinsteins Materialismus und heutige Tests der QuantenmechanikNach einer Darstellung von Einsteins und Bohrs antagonistischen Standpunkten in der Interpretation der Quantenmechanik werden ihre widersprüchlichen Positionen im speziellen Fall des Youngschen Doppelspaltexperiments dargestellt. Es wird dann gezeigt, daß diese Experimente in ihrer neuesten Form (d. h. zeitabhängige Neutroneninterferometrie) Einstein in der Bohr-Einsteinkontroverse recht gaben (wenn man absolute Energie-Impulserhaltung bei allen individuellen Mikroprozessen annimmt).

Einstein and the Quantum: The Secret Life of EPR

Science.gov (United States)

Fine, Arthur

2006-05-01

Locality, separation and entanglement -- 1930s style. Starting with Solvay 1927, we'll explore the background to the 1935 paper by Einstein, Podolsky and Rosen: how it was composed, the actual argument and principles used, and how the paper was received by Schroedinger, and others. We'll also look at Bohr's response: the extent to which Bohr connects with what Einstein was after in EPR and the extent to which EPR marks a shift in Bohr's thinking about the quantum theory. Time permitting, we will contrast EPR with Bell's theorem.

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

Bohr's complementarity principle; quantum mechanics; mutual exclusiveness; quantum entanglement; uncertainty principle. ... casting light on the origin of complementarity in quantum interferometric experiments, the whole issue is reviewed on the basis of our earlier precise formulation of Bohr's complementarity principle.

Pythagoras' celestial spheres in the context of a simple model for quantization of planetary orbits

Energy Technology Data Exchange (ETDEWEB)

Oliveira Neto, Marcal de [Instituto de Quimica, Universidade de Brasilia, Campus Universitario, Asa Norte, 70904-970 Brasilia, DF (Brazil)]. E-mail: marcal@unb.br

2006-10-15

In the present article we attempt to search for a correlation between Pythagoras and Kepler's ideas on harmony of the celestial spheres through simple quantization procedure to describe planetary orbits in our solar system. It is reasoned that starting from a Bohr-like atomic model, planetary mean radii and periods of revolution can be obtained from a set of small integers and just one input parameter given by the mean planetary radius of Mercury. It is also shown that the mean planetary distances can be calculated with the help of a Schroedinger-type equation considering the flatness of the solar system. An attempt to obtain planetary radii using both gravitational and electrostatic approaches linked by Newton's dimensionless constant of gravity is presented.

The Bohr Correspondence Principle

Indian Academy of Sciences (India)

IAS Admin

Deepak Dhar. Keywords. Correspondence principle, hy- drogen atom, Kepler orbit. Deepak Dhar works at the. Tata Institute of Funda- mental Research,. Mumbai. His research interests are mainly in the area of statistical physics. We consider the quantum-mechanical non-relati- vistic hydrogen atom. We show that for bound.

The Bohr Correspondence Principle

Indian Academy of Sciences (India)

Resonance – Journal of Science Education. Current Issue : Vol. 23, Issue 4. Current Issue Volume 23 | Issue 4. April 2018. Home · Volumes & Issues · Categories · Special Issues · Search · Editorial Board · Information for Authors · Subscription ...

Dead space and slope indices from the expiratory carbon dioxide tension-volume curve

NARCIS (Netherlands)

A.H. Kars (Alice); J.M. Bogaard (Jan); Th. Stijnen (Theo); J. de Vries; A.F.M. Verbraak (Anton); C. Hilvering

1997-01-01

textabstractThe slope of phase 3 and three noninvasively determined dead space estimates derived from the expiratory carbon dioxide tension (PCO2) versus volume curve, including the Bohr dead space (VD,Bohr), the Fowler dead space (VD,Fowler) and pre-interface expirate

The Kantian framework of complementarity

Science.gov (United States)

Cuffaro, Michael

A growing number of commentators have, in recent years, noted the important affinities in the views of Immanuel Kant and Niels Bohr. While these commentators are correct, the picture they present of the connections between Bohr and Kant is painted in broad strokes; it is open to the criticism that these affinities are merely superficial. In this essay, I provide a closer, structural, analysis of both Bohr's and Kant's views that makes these connections more explicit. In particular, I demonstrate the similarities between Bohr's argument, on the one hand, that neither the wave nor the particle description of atomic phenomena pick out an object in the ordinary sense of the word, and Kant's requirement, on the other hand, that both 'mathematical' (having to do with magnitude) and 'dynamical' (having to do with an object's interaction with other objects) principles must be applicable to appearances in order for us to determine them as objects of experience. I argue that Bohr's 'complementarity interpretation' of quantum mechanics, which views atomic objects as idealizations, and which licenses the repeal of the principle of causality for the domain of atomic physics, is perfectly compatible with, and indeed follows naturally from a broadly Kantian epistemological framework.

Computer Simulations of Quantum Theory of Hydrogen Atom for Natural Science Education Students in a Virtual Lab

Science.gov (United States)

Singh, Gurmukh

2012-01-01

The present article is primarily targeted for the advanced college/university undergraduate students of chemistry/physics education, computational physics/chemistry, and computer science. The most recent software system such as MS Visual Studio .NET version 2010 is employed to perform computer simulations for modeling Bohr's quantum theory of…

Large boson number IBM calculations and their relationship to the Bohr model

Czech Academy of Sciences Publication Activity Database

Thiamová, Gabriela; Rowe, D. J.

2009-01-01

Roč. 41, č. 2 (2009), s. 189-195 ISSN 1434-6001 Institutional research plan: CEZ:AV0Z10480505 Keywords : COLLECTIVE NUCLEAR-STATES * O(6) DESCRIPTION * LIMIT Subject RIV: BE - Theoretical Physics Impact factor: 1.968, year: 2009

A microscopic derivation of nuclear collective rotation-vibration model and its application to nuclei

Energy Technology Data Exchange (ETDEWEB)

Gulshani, P., E-mail: matlap@bell.net [NUTECH Services, 3313 Fenwick Crescent, Mississauga, Ontario, L5L 5N1 (Canada)

2016-07-07

We derive a microscopic version of the successful phenomenological hydrodynamic model of Bohr-Davydov-Faessler-Greiner for collective rotation-vibration motion of an axially symmetric deformed nucleus. The derivation is not limited to small oscillation amplitude. The nuclear Schrodinger equation is canonically transformed to collective co-ordinates, which is then linearized using a constrained variational method. The associated constraints are imposed on the wavefunction rather than on the particle co-ordinates. The approach yields three self-consistent, time-reversal invariant, cranking-type Schrodinger equations for the rotation-vibration and intrinsic motions, and a self-consistency equation. For harmonic oscillator mean-field potentials, these equations are solved in closed forms for excitation energy, cut-off angular momentum, and other nuclear properties for the ground-state rotational band in some deformed nuclei. The results are compared with measured data.

Causality problem in atomic physics

Energy Technology Data Exchange (ETDEWEB)

Bor, N

1985-10-01

The casuality problem in atomic physics is analysed by Bohr in a wide methodological context. The first part of the paper is a short historical essay picturing the entry of statistical concepts into physics. Bohr underlines a close relationship between an unavoidably probabilitic nature of the quantum theory and quantum postulates introducing the alien-to-classical-physics concepts of integrity, individuality of atomic processes. In the second central part of the paper Bohr discusses the casuality problems in atomic physics in detail and shows that their solution requires a careful analysis of the observation process. Proceeding from the program methodological requirement to describe the measuring instrumentation operation and observation results in the language of classical physics, he explains that the statistical character of the uncertainty relationships expresses a substantial specifically quantum constraint to the applicifically of classical conceptions analyses of microphenomena. Then Bohr refines in principle the notion ''phenomenon'', as one of the central notions among those he employed for the formulation of his complementarity principle. According to bohr a phenomenon should be under-stood as an unambiguously present situation of a completed experiment. Therefore, it is erroneous to speak of the phenomenon perturbation by the observation. The final part of the article deals with the discussion of methodological parallels of the quantum theory and relativity theory.

The causality problem in atomic physics

International Nuclear Information System (INIS)

Bor, N.

1985-01-01

The casuality problem in atomic physics is analysed by Bohr in a wide methodological context. The first part of the paper is a short historical essay picturing the entry of statistical concepts into physics. Bohr underlines a close relationship between an unavoidably probabilitic nature of the quantum theory and quantum postulates introducing the alien-to-classical-physics concepts of integrity, individuality of atomic processes. In the second central part of the paper Bohr discusses the casuality problems in atomic physics in detail and shows that their solution requires a careful analysis of the observation process. Proceeding from the program methodological requirement to describe the measuring instrumentation operation and observation results in the language of classical physics, he explains that the statistical character of the uncertainty relationships expresses a substantial specifically quantum constraint to the applicifically of classical conceptions analyses of microphenomena. Then Bohr refines in principle the notion ''phenomenon'', as one of the central notions among those he employed for the formulation of his complementarity principle. According to bohr a phenomenon should be under-stood as an unambiguously present situation of a completed experiment. Therefore, it is erroneous to speak of the phenomenon perturbation by the observation. The final part of the article deals with the discussion of methodological parallels of the quantum theory and relativity theory

I grandi della fisica da Platone a Heisenberg

CERN Document Server

Von Weizsäcker, Carl Friedrich

2002-01-01

Parmenide ; Platone ; Aristotele ; Copernico, Keplero, Galilei ; Galileo Galilei ; Cartesio ; Gottfried Wilhelm Leibniz ; Cartesio, Newton, Leibniz, Kant ; Immanuel Kant ; Johann Wolfgang Goethe ; Robert Meyer ; Albert Einstein ; Niels Bohr ; Paul Adrien Maurice Dirac ; Niels Bohr e Werner Heisenberg, un ricordo del 1932 ; Werner Heisenberg ; Heisenberg, fisico e filosofo ; l'interpretazione filosofica della fisica moderna.

Resonance journal of science education

Indian Academy of Sciences (India)

IAS Admin

Sketch made by Niels Bohr in 1944 to illustrate the content of his debate with Einstein on the uncertainty principle at the 6th Solvay Conference in 1930. Niels Bohr (1885–1962). Sketch by Homi Bhabha. (Courtesy: TIFR, Bombay). Front Cover. 871. Science Smiles. Ayan Guha. 876. Back Cover. 948. Classics. Biology and ...

Consistent dynamical and statistical description of fission and comparison

Energy Technology Data Exchange (ETDEWEB)

Shunuan, Wang [Chinese Nuclear Data Center, Beijing, BJ (China)

1996-06-01

The research survey of consistent dynamical and statistical description of fission is briefly introduced. The channel theory of fission with diffusive dynamics based on Bohr channel theory of fission and Fokker-Planck equation and Kramers-modified Bohr-Wheeler expression according to Strutinsky method given by P.Frobrich et al. are compared and analyzed. (2 figs.).

Exploring Magnetic Fields with a Compass

Science.gov (United States)

Lunk, Brandon; Beichner, Robert

2011-01-01

A compass is an excellent classroom tool for the exploration of magnetic fields. Any student can tell you that a compass is used to determine which direction is north, but when paired with some basic trigonometry, the compass can be used to actually measure the strength of the magnetic field due to a nearby magnet or current-carrying wire. In this paper, we present a series of simple activities adapted from the Matter & Interactions textbook for doing just this. Interestingly, these simple measurements are comparable to predictions made by the Bohr model of the atom. Although antiquated, Bohr's atom can lead the way to a deeper analysis of the atomic properties of magnets. Although originally developed for an introductory calculus-based course, these activities can easily be adapted for use in an algebra-based class or even at the high school level.

Nuclear Checker Board Model

Science.gov (United States)

Lach, Theodore

2017-01-01

The Checkerboard model of the Nucleus has been in the public domain for over 20 years. Over those years it has been described by nuclear and particle physicists as; cute, ``the Bohr model of the nucleus'' and ``reminiscent of the Eightfold Way''. It has also been ridiculed as numerology, laughed at, and even worse. In 2000 the theory was taken to the next level by attempting to explain why the mass of the ``up'' and ``dn'' quarks were significantly heavier than the SM ``u'' and ``d'' quarks. This resulted in a paper published on arXiv.nucl-th/0008026 in 2000, predicting 5 generations of quarks, each quark and negative lepton particle related to each other by a simple geometric mean. The CBM predicts that the radii of the elementary particles are proportional to the cube root of their masses. This was realized Pythagorean musical intervals (octave, perfect 5th, perfect 4th plus two others). Therefore each generation can be explained by a simple right triangle and the height of the hypotenuse. Notice that the height of a right triangle breaks the hypotenuse into two line segments. The geometric mean of those two segments equals the length of the height of this characteristic triangle. Therefore the CBM theory now predicts that all the elementary particles mass are proportion to the cube of their radii. Therefore the mass density of all elementary particles (and perhaps black holes too) are a constant of nature.

Large degeneracy of excited hadrons and quark models

International Nuclear Information System (INIS)

Bicudo, P.

2007-01-01

The pattern of a large approximate degeneracy of the excited hadron spectra (larger than the chiral restoration degeneracy) is present in the recent experimental report of Bugg. Here we try to model this degeneracy with state of the art quark models. We review how the Coulomb Gauge chiral invariant and confining Bethe-Salpeter equation simplifies in the case of very excited quark-antiquark mesons, including angular or radial excitations, to a Salpeter equation with an ultrarelativistic kinetic energy with the spin-independent part of the potential. The resulting meson spectrum is solved, and the excited chiral restoration is recovered, for all mesons with J>0. Applying the ultrarelativistic simplification to a linear equal-time potential, linear Regge trajectories are obtained, for both angular and radial excitations. The spectrum is also compared with the semiclassical Bohr-Sommerfeld quantization relation. However, the excited angular and radial spectra do not coincide exactly. We then search, with the classical Bertrand theorem, for central potentials producing always classical closed orbits with the ultrarelativistic kinetic energy. We find that no such potential exists, and this implies that no exact larger degeneracy can be obtained in our equal-time framework, with a single principal quantum number comparable to the nonrelativistic Coulomb or harmonic oscillator potentials. Nevertheless we find it plausible that the large experimental approximate degeneracy will be modeled in the future by quark models beyond the present state of the art

Roadworks around the "Les Cèdres" car park

CERN Multimedia

SMB Department

2016-01-01

Diversions will be in place on Route Scherrer and Route Bohr from 4 to 31 July.   As we announced in a previous article, the SMB department is currently installing vehicle registration plate readers at the entrances and exits of the Les Cèdres car park and of the Building 4 and 5 car park, both on the Meyrin site. Please note that, due to the installation work involved: access to Buildings 50 and 52 via Route Scherrer (passing under the Building 50 walkway) will be closed from 4 to 8 July, access to the Les Cèdres car park via Route Scherrer will be closed from 4 to 14 July, access to the Les Cèdres car park via Route Bohr will be closed from 16 to 31 July, Route Bohr will be closed between Route Greinacher and Route Bell from 16 to 31 July. Please also note that, following the completion of the work, the Les Cèdres car park will operate as a one-way system, with entry only from Route Scherrer and exit only onto Route Bohr. Thank you for your understand...

Stapp's quantum dualism: The James/Heisenberg model of consciousness

International Nuclear Information System (INIS)

Noyes, H.P.

1994-01-01

Henry Stapp attempts to resolve the Cartesian dilemma by introducing what the author would characterize as an ontological dualism between mind and matter. His model for mind comes from William James' description of conscious events and for matter from Werner Heisenberg's ontological model for quantum events (wave function collapse). His demonstration of the isomorphism between the two types of events is successful, but in the author's opinion fails to establish a monistic, scientific theory. The author traces Stapp's failure to his adamant rejection of arbitrariness, or 'randomness'. This makes it impossible for him (or for Bohr and Pauli before him) to understand the power of Darwin's explanation of biology, let along the triumphs of modern 'neo-Darwinism'. The author notes that the point at issue is a modern version of the unresolved opposition between Leucippus and Democritus on one side and Epicurus on the other. Stapp's views are contrasted with recent discussions of consciousness by two eminent biologists: Crick and Edelman. They locate the problem firmly in the context of natural selection on the surface of the earth. Their approaches provide a sound basis for further scientific work. The author briefly examines the connection between this scientific (rather than ontological) framework and the new fundamental theory based on bit-strings and the combinatorial hierarchy

Quantum-like Modeling of Cognition

Science.gov (United States)

Khrennikov, Andrei

2015-09-01

This paper begins with a historical review of the mutual influence of physics and psychology, from Freud's invention of psychic energy inspired by von Boltzmann' thermodynamics to the enrichment quantum physics gained from the side of psychology by the notion of complementarity (the invention of Niels Bohr who was inspired by William James), besides we consider the resonance of the correspondence between Wolfgang Pauli and Carl Jung in both physics and psychology. Then we turn to the problem of development of mathematical models for laws of thought starting with Boolean logic and progressing towards foundations of classical probability theory. Interestingly, the laws of classical logic and probability are routinely violated not only by quantum statistical phenomena but by cognitive phenomena as well. This is yet another common feature between quantum physics and psychology. In particular, cognitive data can exhibit a kind of the probabilistic interference effect. This similarity with quantum physics convinced a multi-disciplinary group of scientists (physicists, psychologists, economists, sociologists) to apply the mathematical apparatus of quantum mechanics to modeling of cognition. We illustrate this activity by considering a few concrete phenomena: the order and disjunction effects, recognition of ambiguous figures, categorization-decision making. In Appendix 1 we briefly present essentials of theory of contextual probability and a method of representations of contextual probabilities by complex probability amplitudes (solution of the ``inverse Born's problem'') based on a quantum-like representation algorithm (QLRA).

Quantum-like Modeling of Cognition

Directory of Open Access Journals (Sweden)

Andrei eKhrennikov

2015-09-01

Full Text Available This paper begins with a historical review of the mutual influence of physics and psychology, from Freud's invention of psychic energy inspired by von Boltzmann' thermodynamics to the enrichment quantum physics gained from the side of psychology by the notion of complementarity (the invention of Niels Bohr who was inspired by William James, besides we consider the resonance of the correspondence between Wolfgang Pauli and Carl Jung in both physics and psychology. Then we turn to the problem of development of mathematical models for laws of thought starting with Boolean logic and progressing towards foundations of classical probability theory. Interestingly, the laws of classical logic and probability are routinely violated not only by quantum statistical phenomena but by cognitive phenomena as well. This is yet another common feature between quantum physics and psychology.In particular, cognitive data can exhibit a kind of the probabilistic interference effect. This similarity with quantum physics convinced a multi-disciplinary group of scientists (physicists, psychologists, economists, sociologists to apply the mathematical apparatus of quantum mechanics to modeling of cognition. We illustrate this activity by considering a few concrete phenomena: the order and disjunction effects, recognition of ambiguous figures, categorization-decision making.In Appendix 1 we briefly present essentials of theory of contextual probability and a method of representations of contextual probabilities by complex probability amplitudes(solution of the ``inverse Born's problem'' based on a quantum-like representation algorithm (QLRA.

Restrictions on the neutrino magnetic dipole moment

International Nuclear Information System (INIS)

Duncan, M.J.; Sankar, S.U.; Grifols, J.A.; Mendez, A.

1987-01-01

We examine mechanisms for producing neutrino magnetic moments from a wide class of particle theories which are extensions of the standard model. We show that it is difficult to naturally obtain a moment greater than ≅ 10 -2 electron Bohr magnetons. Thus models of phenomena requiring moments of order ≅ 10 -10 magnetons, such as those proposed as a resolution to the solar neutrino puzzle, are in conflict with current perceptions in particle physics. (orig.)

Cluster models of aqueous Na{sup +} and Cl{sup -} in sea water/ice

Energy Technology Data Exchange (ETDEWEB)

Michelsen, R.; Walker, R. [Randolph-Macon College, Department of Chemistry (United States); Shillady, D., E-mail: quantummechanicsllc@msn.com [Virginia Commonwealth University, Department of Chemistry (United States)

2012-10-15

In this article, we present finite cluster models of aqueous solutes [NaCl(H{sub 2}O){sub 10}, NaCl(H{sub 2}O){sub 5}, and (H{sub 2}O){sub 6}] in terms of molecular geometry and vibrational spectra for interpretation of experimental infrared spectra of NaCl brine solutions. The quantum chemistry program GAMESS is used to optimize the model clusters to a local minimum energy gradient of less than 5.0d-6 hartrees/bohr with B3LYP in a gaussian basis of 6-31G(d,p). Harmonic frequencies are computed for comparison with the infrared spectra measured by attenuated total reflection of a temperature-controlled Ge plate under a layer of cold brine solution. The motivation for this research is to understand the mechanism by which freezing seawater excludes halide ions (mainly Cl{sup -}) and why the O-H stretching region of the spectra changes with temperature. Frost flowers, sea ice, and snow in marine environments contain concentrated halides in liquid brine at their surfaces which lead to catalytic destruction of low-altitude ozone in the polar regions of the Earth.

Collective Quadrupole Excitations of Transactinide Nuclei

CERN Document Server

Zajac, K; Pomorski, K; Rohozinski, S G; Srebrny, J

2003-01-01

The quadrupole excitations of transuranic nuclei are described in the frame of the microscopic Bohr Hamiltonian modified by adding the coupling with the collective pairing vibrations. The energies of the states from the ground-state bands in U to No even-even isotopes as well as the B(E2) transition probabilities are reproduced within the model containing no adjustable parameters.

Current Research In The Institut D'optique - Orsay

Science.gov (United States)

Marechal, A.

1985-01-01

I - FUNDAMENTAL PROBLEMS A. ASPECT : Non locality in wave mechanics. The Einstein-Bohr dispute and the optical test of Bell's inequalities. A. Einstein and N. Bohr had a discussion about the role of probabilities in microphysics; as is well known the location and momentum of particles cannot be known precisely but only through probabilistic expressions. Einstein thought that complementary variables (hidden variables) are unknown at the present time and that the knowledge of those variables would suppress the actual uncertainty "God does not play random games". On the contrary, Bohr advocated the fundamental role of probabilities. During the sixties J. Bell established inequalities supporting the Einstein point of view. These inequalities are in contradiction with the predictions of quantum mechanics in some very rare situations. A.Aspect designed and realised an optical experiment where the correlation of polarisation of photons emitted by a single atom was measured with a very good signal to noise ratio. Moreover the orientation of the polarisation analyser was changed during the time of flight of photons. The experimental result is in full agreement with the point of view of N. Bohr : the uncertainty on the movement of particles is a fundamental component of the laws of nature and Bell's inequalities do not hold.

Fission barriers of light nuclei

International Nuclear Information System (INIS)

Grotowski, K.; Planeta, R.; Blann, M.; Komoto, T.

1989-01-01

Experimental fission excitation functions for compound nuclei /sup 52/Fe, /sup 49/Cr, /sup 46/V, and /sup 44/Ti formed in heavy-ion reactions are analyzed in the Hauser-Feshbach/Bohr-Wheeler formalism using fission barriers based on the rotating liquid drop model of Cohen et al. and on the rotating finite range model of Sierk. We conclude that the rotating finite range approach gives better reproduction of experimental fission yields, consistent with results found for heavier systems

L’ULTIMO ASSOLUTO DELLA RELATIVITÀ

OpenAIRE

Roselli, Andrea

2014-01-01

Si mostra come la celebre disputa tra Einstein e Bohr riguardi i concetti di realtà retrostanti le loro relative concezioni della realtà fisica; conseguentemente, viene suggerita una significativa connessione tra le teorie di Copenaghen e la relatività einsteiniana. Bohr considerava la descrizione della realtà offerta dalla meccanica quantistica completa; Einstein, al contrario (nonostante il contributo apportato alla sua nascita), continuava a cercare una teoria deterministica. Quando nel 19...

Dead space and slope indices from the expiratory carbon dioxide tension-volume curve

OpenAIRE

Kars, Alice; Bogaard, Jan; Stijnen, Theo; Vries, J.; Verbraak, Anton; Hilvering, C.

1997-01-01

textabstractThe slope of phase 3 and three noninvasively determined dead space estimates derived from the expiratory carbon dioxide tension (PCO2) versus volume curve, including the Bohr dead space (VD,Bohr), the Fowler dead space (VD,Fowler) and pre-interface expirate (PIE), were investigated in 28 healthy control subjects, 12 asthma and 29 emphysema patients (20 severely obstructed and nine moderately obstructed) with the aim to establish diagnostic value. Because breath volume and frequenc...

Principle And Practice Of Instrumental Analysis

International Nuclear Information System (INIS)

Kim, Chong Il; Kim, Chang Gyo; Oh, Yong Taek

2010-03-01

This book gives descriptions of instrumental analysis, which includes quantum physics and chemical foundation with Bohr's adatom model and structure of an electron of atom and the periodic table, analytical theory on analytical chemistry and chemometrics, measurement uncertainty and probability and statistics, state of crystalline materials, structure of crystalline materials, spectroscopy, like infrared spectroscopy and near infrared spectroscopy, electro spectroscopy, mass spectroscopy and Atomic spectroscopy.

An introduction to the adiabatic time-dependent Hartree-Fock method

International Nuclear Information System (INIS)

Giannoni, M.J.

1984-05-01

The aim of the adiabatic time-dependent Hartree-Fock method is to investigate the microscopic foundations of the phenomenological collective models. We briefly review the general formulation, which consists in deriving a Bohr-like Hamiltonian from a mean field theory, and discuss the limiting case where only a few collective variables participate to the motion. Some applications to soft nuclei and heavy ion collisions are presented

FTL Quantum Models of the Photon and the Electron

International Nuclear Information System (INIS)

Gauthier, Richard F.

2007-01-01

A photon is modeled by an uncharged superluminal quantum moving at 1.414c along an open 45-degree helical trajectory with radius R = λ/2π (where λ is the helical pitch or wavelength). A mostly superluminal spatial model of an electron is composed of a charged pointlike quantum circulating at an extremely high frequency ( 2.5 x 1020 hz) in a closed, double-looped hehcal trajectory whose helical pitch is one Compton wavelength h/mc. The quantum has energy and momentum but not rest mass, so its speed is not limited by c. sThe quantum's speed is superluminal 57% of the time and subluminal 43% of the time, passing through c twice in each trajectory cycle. The quantum's maximum speed in the electron's rest frame is 2.515c and its minimum speed is .707c. The electron model's helical trajectory parameters are selected to produce the electron's spin (ℎ/2π)/2 and approximate (without small QED corrections) magnetic moment e(ℎ/2π)/2m (the Bohr magneton μB) as well as its Dirac equation-related 'jittery motion' angular frequency 2mc2/(ℎ/2π), amplitude (ℎ/2π)/2mc and internal speed c. The two possible helicities of the electron model correspond to the electron and the positron. With these models, an electron is like a closed circulating photon. The electron's inertia is proposed to be related to the electron model's circulating internal Compton momentum mc. The internal superluminalily of the photon model, the internal superluminahty/subluminality of the electron model, and the proposed approach to the electron's inertia as ''momentum at rest'' within the electron, could be relevant to possible mechanisms of superluminal communication and transportation

Bohrian Complementarity in the Light of Kantian Teleology

Science.gov (United States)

Pringe, Hernán

2014-03-01

The Kantian influences on Bohr's thought and the relationship between the perspective of complementarity in physics and in biology seem at first sight completely unrelated issues. However, the goal of this work is to show their intimate connection. We shall see that Bohr's views on biology shed light on Kantian elements of his thought, which enables a better understanding of his complementary interpretation of quantum theory. For this purpose, we shall begin by discussing Bohr's views on the analogies concerning the epistemological situation in biology and in physics. Later, we shall compare the Bohrian and the Kantian approaches to the science of life in order to show their close connection. On this basis, we shall finally turn to the issue of complementarity in quantum theory in order to assess what we can learn about the epistemological problems in the quantum realm from a consideration of Kant's views on teleology.

Secret letters cast light on Copenhagen

Energy Technology Data Exchange (ETDEWEB)

Durrani, Matin

2001-11-01

Letters by Niels Bohr that have been kept secret since his death could explain the mystery of why Werner Heisenberg visited him in Copenhagen in 1941. When the author Michael Frayn spent two years writing Copenhagen, he had no idea how successful the play would become. He doubted that audiences would sit through a historical drama about a war-time meeting between Werner Heisenberg - head of Germany's nuclear programme - and his old mentor Niels Bohr in the Nazi-occupied Danish capital in 1941. But Frayn's efforts paid off. Audiences and critics alike have thrilled at the way the award-winning play probes the historical uncertainty that surrounds the encounter. Was Heisenberg fishing for information about the Allies' atomic plans - or was he trying to recruit Bohr for Germany's bomb programme? Did Heisenberg want to suggest that the Germans were close to finishing a bomb so that the Allies would make peace with Hitler? Maybe he was simply seeking approval from Bohr for his own atomic work. There is also a moral debate: did Heisenberg know how to build a bomb, but decided not to - or did he want to build one, but got his calculations wrong? Unfortunately, no-one was there to record or observe the encounter and we cannot know for sure what was said or implied between the two men. All we do know is that the pair dined together and took a short walk - and that the incident damaged Bohr and Heisenberg's friendship forever. To piece together what happened, historians of science have had to rely on Heisenberg's post-war recollections - which have been ambiguous and contradictory - along with scraps of evidence from secondary sources. (U.K.)

Phenomenological realism, superconductivity and quantum mechanics

International Nuclear Information System (INIS)

Shomar, T.L.E.

1998-01-01

was accepted as the fundamental theory of superconductivity, and how later failed to account for new kinds of superconductors. I contrast that with the building of the widely accepted phenomenological model of superconductivity. The other case study is a fresh look at the Bohr-Einstein debate. I think that the main difference between Bohr and Einstein was their position from how theoretical work ought to be conducted in physics. Einstein always sought the mathematical clarity and simplicity, he adopted a top-down approach toward theoretical work, while Bohr insisted on a bottom-up approach. (author)

Recent developments in quantum field theory

International Nuclear Information System (INIS)

Ambjoern, J.; Petersen, J.L.; Durhuus, B.J.

1985-01-01

This is the second volume in a set of three containing the proceedings of 3 conferences held in Copenhagen, to mark the centennial of Niels Bohr. The purpose of this symposium was to bring together theoretical particle physicists to discuss the present status and, in particular, the latest developments in quantum field theory, in their broadest aspects. This volume contains the main 19 lectures and reflects the contemporary status of a line of development, one of whose initiators was Niels Bohr. (orig.)

Collective excitation spectra of transitional even nuclei

International Nuclear Information System (INIS)

Quentin, P.; Paris-11 Univ., 91 - Orsay; Deloncle, I.; Libert, J.; Sauvage, J.

1990-01-01

This talk is dealing with the nuclear low energy collective motion as described in the context of microscopic versions of the Bohr Hamiltonian. Two different ways of building microscopically Bohr collective Hamiltonians will be sketched; one within the framework of the Generator Coordinate Method, the other using the Adiabatic Time-Dependent Hartree-Fock-Boholyubov approximation. A sample of recent results will be presented which pertains to the description of transitional even nuclei and to the newly revisited phenomenon of superdeformation at low spin

Stapp`s quantum dualism: The James/Heisenberg model of consciousness

Energy Technology Data Exchange (ETDEWEB)

Noyes, H.P.

1994-02-18

Henry Stapp attempts to resolve the Cartesian dilemma by introducing what the author would characterize as an ontological dualism between mind and matter. His model for mind comes from William James` description of conscious events and for matter from Werner Heisenberg`s ontological model for quantum events (wave function collapse). His demonstration of the isomorphism between the two types of events is successful, but in the author`s opinion fails to establish a monistic, scientific theory. The author traces Stapp`s failure to his adamant rejection of arbitrariness, or `randomness`. This makes it impossible for him (or for Bohr and Pauli before him) to understand the power of Darwin`s explanation of biology, let along the triumphs of modern `neo-Darwinism`. The author notes that the point at issue is a modern version of the unresolved opposition between Leucippus and Democritus on one side and Epicurus on the other. Stapp`s views are contrasted with recent discussions of consciousness by two eminent biologists: Crick and Edelman. They locate the problem firmly in the context of natural selection on the surface of the earth. Their approaches provide a sound basis for further scientific work. The author briefly examines the connection between this scientific (rather than ontological) framework and the new fundamental theory based on bit-strings and the combinatorial hierarchy.

Bohr's Philosophy of Wave–Particle Complementarity

Indian Academy of Sciences (India)

IAS Admin

recent years on the issues related to the .... quantum theory “forces us to adopt a new mode of description .... [18, 19]. The above-mentioned studies, therefore, serve to highlight that ... applied to different disciplines, like psychology and biology.

Genetics Home Reference: Bohring-Opitz syndrome

Science.gov (United States)

... Additional NIH Resources (1 link) National Institute of Neurological Disorders and Stroke: Microcephaly Information Page Educational Resources (9 links) Boston Children's Hospital: Metopic Synostosis (Trigonocephaly) Symptoms & Causes Centers for ...

The quantum cookbook

International Nuclear Information System (INIS)

Gribbin, John.

1985-01-01

The paper traces the development of quantum physics, from the early past of this century to modern applications including solid-state devices. The early quantum studies on the model of the atom, carried out by Niels Bohr, are described, as well as the work by Heisenberg and colleagues on matrix mechanics. De Broglie wavelength; particles and waves; uncertainty principles; lasers; and semiconductor systems; are all briefly discussed. (U.K.)

Ionization of Ar11+ ions during collisions near the Bohr velocity

International Nuclear Information System (INIS)

Zhou, Xianming; Cheng, Rui; Lei, Yu; Liu, Shidong; Deng, Jiachuan; Sun, Yuanbo; Ren, Jieru; Wang, Yuyu; Zhao, Yongtao; Xiao, Guoqing

2014-01-01

The K-shell X-rays of argon from the collisions of 1–3 MeV Ar 11+ ions with V target were measured. It was found that the Kα X-ray shifts to the high energy by 52 eV, and the intensity ratio of Kβ/Kα was larger than the atomic data, owing to the presence of 2p multiple vacancies. The X-ray production cross sections were obtained and compared with BEA, PWBA and ECPSSR theoretical predictions. The BEA model, taking into account the ionic binding energy, coulomb repulsion and multiple ionization effect on fluorescence yield, presented a better agreement with the experimental cross section data

The Colliderscope: a real-time show

CERN Multimedia

Francesco Poppi

2010-01-01

Ninety-six LED lights distributed over the facade of the Niels Bohr Institute (NBI) in Blegdamsvej (Denmark) reproduce the actual signals coming from the Transition Radiation Detector (TRT) in ATLAS. Thanks to the Colliderscope, when a collision occurs below the ground in Geneva, people passing by in Blegdamsvej will be aware of it almost in real-time.   Niels Bohr Institute facade lit up to reflect the latest data from ATLAS-TRT . The pattern, intensity and duration of the Colliderscope’s flashes of light depend on the physical parameters of particles crossing the ATLAS TRT detector. “At the Colliderscope very little happens randomly”, explains Troels Petersen, a physicist at NBI and one of the people who conceived it. “Particularly interesting events, such as electrons, are shown by a bright light that remains on the facade for several seconds”. The Niels Bohr Institute has participated in the development of the TRT detector, and this is why t...

On the relation between the Einstein-Podolsky-Rosen paradox and the problem of nonlocality in quantum mechanics

International Nuclear Information System (INIS)

de Muynck, W.M.

1986-01-01

The EPR problem is studied both from an instrumentalistic and from a realistic point of view. Bohr's reply to the EPR paper is analyzed and demonstrated to be not completely representative of Bohr's general views on the possibility of defining properties of a microscopic object. A more faithful Bohrian answer would not have led Einstein to the conclusion that Bohr's completeness claim of quantum mechanics implies nonlocality. The projection postulate, already denounced in 1936 by Margenau as the source of the EPR paradox, is found to be also at the origin of the nonlocality conundrum. Its unobservability in EPR-like experiments is demonstrated, thus showing the redundancy of the idea of nonlocality in the instrumentalist interpretation of quantum mechanics. It is argued that also from a realist point of view there is no reason to assume nonlocality. The relevance of Bohm's quantum potential and of Bells inequalities with respect to the (non) locality problem is discussed

Quantization of Poisson Manifolds from the Integrability of the Modular Function

Science.gov (United States)

Bonechi, F.; Ciccoli, N.; Qiu, J.; Tarlini, M.

2014-10-01

We discuss a framework for quantizing a Poisson manifold via the quantization of its symplectic groupoid, combining the tools of geometric quantization with the results of Renault's theory of groupoid C*-algebras. This setting allows very singular polarizations. In particular, we consider the case when the modular function is multiplicatively integrable, i.e., when the space of leaves of the polarization inherits a groupoid structure. If suitable regularity conditions are satisfied, then one can define the quantum algebra as the convolution algebra of the subgroupoid of leaves satisfying the Bohr-Sommerfeld conditions. We apply this procedure to the case of a family of Poisson structures on , seen as Poisson homogeneous spaces of the standard Poisson-Lie group SU( n + 1). We show that a bihamiltonian system on defines a multiplicative integrable model on the symplectic groupoid; we compute the Bohr-Sommerfeld groupoid and show that it satisfies the needed properties for applying Renault theory. We recover and extend Sheu's description of quantum homogeneous spaces as groupoid C*-algebras.

From the Old to the New World of Nuclear Physics

Science.gov (United States)

Stuewer, Roger H.

Physicists passed from the Old to the New World of Nuclear Physics in the two decades between the first and second world wars. The transition occurred against the background of the Great War, the postwar hyperinflation in Germany and Austria, and the greatest intellection migrations in history after the Nazi Civil Service law of 1933, the Anschlussof Austria in March 1938, and the Fascist anti-Semitic laws that fall. It involved Rutherford's discovery of artificial disintegration, Pettersson and Kirsch's challenge of it, and the concomitant rise and fall of Rutherford's satellite model of the nucleus; Gamow's quantum-mechanical theory of alpha decay and his liquid-drop model of the nucleus; the discoveries of deuterium and the deuteron, neutron, and positron, and the inventions of the Cockcroft-Walton accelerator and the cyclotron; the influence of the seventh Solvay Conference; Joliot and Curie's discovery of artificial radioactivity; Pauli's neutrino hypothesis, Fermi's theory of beta decay, and his discovery of the efficacy of slow neutrons in producing nuclear reactions; Bohr's theory of the compound nucleus and Breit and Wigner's theory of neutron-nucleus resonances; and the discovery of nuclear fission, Meitner and Frisch's interpretation of it, and Bohr and Fermi revelation of both in America.

Excited state populations and charge-exchange of fast ions in solids

International Nuclear Information System (INIS)

Miller, P.D.; Sofield, C.J.; Woods, C.J.

1984-01-01

Excited state populations and charge state fractions of 445 MeV Cl ions have been measured for a range of thicknesses of solid C targets. Cross sections for electron capture, loss, excitation and excited state quenching have been determined and these data are found to predict a quantitative difference between equilibrium charge state distributions from gases and solids for a special case of the Bohr-Lindhard density effect model. 8 references, 1 figure, 1 table

Quantum mechanical resonances

International Nuclear Information System (INIS)

Cisneros S, A.; McIntosh, H.V.

1982-01-01

A discussion of the nature of quantum mechanical resonances is presented from the point of view of the spectral theory of operators. In the case of Bohr-Feshbach resonances, graphs are presented to illustrate the theory showing the decay of a doubly excited metastable state and the excitation of the resonance by an incident particle with proper energy. A characterization of resonances is given as well as a procedure to determine widths using the spectral density function. A sufficient condition is given for the validity of the Breit-Wigner formula for Bohr-Feshbach resonances. (author)

Karl Popper and the Copenhagen interpretation

Science.gov (United States)

Peres, Asher

Popper conceived an experiment whose analysis led to a result that he deemed absurd. Popper wrote that his reasoning was based on the Copenhagen interpretation and therefore invalidated it. Many authors who have examined Popper's analysis have found in it various technical flaws which are briefly summarized here. However, the aim of the present article is not technical. My concern is to redress logical flaws in Popper's argument: the terminology he uses is ambiguous, his analysis involves counterfactual hypotheses, and it violates Bohr's complementarity principle. Therefore, the absurdity of Popper's result only confirms Bohr's approach.

Atomic theories

CERN Document Server

Loring, FH

2014-01-01

Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

Copenhagen, an unexplained encounter

CERN Multimedia

2003-01-01

Why did Werner Heisenberg, a participant in the nuclear research programme of the Third Reich, visit his friend and mentor Niels Bohr in occupied Denmark in September 1941? Was it a deliberate attempt to mislead the allies through talking to Bohr? Or was he really pursuing the utopian goal of halting the race to build the atomic bomb? What the historians have never been able to fully explain is explored in the play "Copenhagen", in which the ghosts of the two great scientists try to fathom why they failed to understand each other all those years ago. "Copenhagen", which has filled theatres in London, New York and Paris, is one of the most successful plays of British author Michael Frayn, also famous for his crime thrillers and comedies. A production of the play in French will be staged at the Théâtre de Carouge from 18th November. Werner Heisenberg and Niels Bohr before World War II.Both CERN and the Association pour l'Histoire des Sciences have associated themselves with the production...

Transferring and practicing the correspondence principle in the old quantum theory: Franck, Hund and the Ramsauer effect

Energy Technology Data Exchange (ETDEWEB)

Jaehnert, Martin [MPIWG, Berlin (Germany)

2013-07-01

In 1922 Niels Bohr wrote a letter to Arnold Sommerfeld complaining that: ''[i]n the last years my attempts to develop the principles of quantum theory were met with very little understanding.'' Looking for the correspondence idea in publications, one finds that the principle was indeed hardly applied by physicists outside of Copenhagen. Only by 1922 physicists from wider research networks of quantum theory started to transfer the principle into their research fields, often far removed from its initial realm of atomic spectroscopy. How and why did physicists suddenly become interested in the idea that Bohr*s writings had been promoting since 1918? How was the correspondence principle transferred to these fields and how did its transfer affect these fields and likewise the correspondence principle itself? To discuss these questions, my talk focuses on the work of James Franck and Friedrich Hund on the Ramsauer effect in 1922 and follows the interrelation of the developing understanding of a newly found effect and the adaptation of the correspondence idea in a new conceptual and sociological context.

Atomic physics made clear

International Nuclear Information System (INIS)

Meinhold, H.

1980-01-01

This book is a popular introduction into the foundations of atomic physics und quantum mechanics. Starting from some phenomenological concepts Bohr's model and the construction of the periodic system regarding the shell structure of atoms are introduced. In this framework the selection rules and magnetic moments of atomic electrons are considered. Finally the wave-particle dualism is considered. In the appendix some mathematical methods are described which are useful for a deeper penetration into the considered ideas. (HSI)

The integration of mind into physics

International Nuclear Information System (INIS)

Stapp, H.P.

1994-01-01

The proper goal of science is a unified theory of all of nature, including our thoughts. An adequate theory of this kind will resolve the quantum measurement problem, which is to reconcile the nonclassical character of the quantum world with the classical character of our perceptions of it. A framework for such a theory is described. It weds the opposing views of Bohr and Einstein. Bohr held that quantum theory provides rules that relate aspects of our knowledge, while Einstein claimed that basic theory should describe what could be reality itself, not merely our knowledge of it

The effect of a neutrino magnetic moment on nuclear excitation processes

International Nuclear Information System (INIS)

Dodd, A.C.; Papageorgiu, E.; Ranfone, S.

1991-01-01

It is shown that the MeV-range neutrinos with a magnetic moment of ≅ 10 -11 Bohr magnetons would excite nuclei, like 12 C, with cross sections comparable to those obtained in the Standard Model. This implies the possibility of improving the present experimental bounds on the magnetic moment of any flavour of neutrinos by one order of magnitude. Such a magnetic moment would also enhance the coherent neutrino-nuclear scattering in low-temperature detectors, enabling them to set comparable limits. (author)

Simultaneous Blood–Tissue Exchange of Oxygen, Carbon Dioxide, Bicarbonate, and Hydrogen Ion

Science.gov (United States)

Dash, Ranjan K.; Bassingthwaighte, James B.

2014-01-01

A detailed nonlinear four-region (red blood cell, plasma, interstitial fluid, and parenchymal cell) axially distributed convection-diffusion-permeation-reaction-binding computational model is developed to study the simultaneous transport and exchange of oxygen (O2) and carbon dioxide (CO2) in the blood–tissue exchange system of the heart. Since the pH variation in blood and tissue influences the transport and exchange of O2 and CO2 (Bohr and Haldane effects), and since most CO2 is transported as HCO3- (bicarbonate) via the CO2 hydration (buffering) reaction, the transport and exchange of HCO3- and H+ are also simulated along with that of O2 and CO2. Furthermore, the model accounts for the competitive nonlinear binding of O2 and CO2 with the hemoglobin inside the red blood cells (nonlinear O2–CO2 interactions, Bohr and Haldane effects), and myoglobin-facilitated transport of O2 inside the parenchymal cells. The consumption of O2 through cytochrome-c oxidase reaction inside the parenchymal cells is based on Michaelis–Menten kinetics. The corresponding production of CO2 is determined by respiratory quotient (RQ), depending on the relative consumption of carbohydrate, protein, and fat. The model gives a physiologically realistic description of O2 transport and metabolism in the microcirculation of the heart. Furthermore, because model solutions for tracer transients and steady states can be computed highly efficiently, this model may be the preferred vehicle for routine data analysis where repetitive solutions and parameter optimization are required, as is the case in PET imaging for estimating myocardial O2 consumption. PMID:16775761

Great Physicists - The Life and Times of Leading Physicists from Galileo to Hawking

Science.gov (United States)

Cropper, William H.

2004-09-01

Here is a lively history of modern physics, as seen through the lives of thirty men and women from the pantheon of physics. William H. Cropper vividly portrays the life and accomplishments of such giants as Galileo and Isaac Newton, Marie Curie and Ernest Rutherford, Albert Einstein and Niels Bohr, right up to contemporary figures such as Richard Feynman, Murray Gell-Mann, and Stephen Hawking. We meet scientists--all geniuses--who could be gregarious, aloof, unpretentious, friendly, dogged, imperious, generous to colleagues or contentious rivals. As Cropper captures their personalities, he also offers vivid portraits of their great moments of discovery, their bitter feuds, their relations with family and friends, their religious beliefs and education. In addition, Cropper has grouped these biographies by discipline--mechanics, thermodynamics, particle physics, and others--each section beginning with a historical overview. Thus in the section on quantum mechanics, readers can see how the work of Max Planck influenced Niels Bohr, and how Bohr in turn influenced Werner Heisenberg. Our understanding of the physical world has increased dramatically in the last four centuries. With Great Physicists , readers can retrace the footsteps of the men and women who led the way.

Quantum frames

Science.gov (United States)

Brown, Matthew J.

2014-02-01

The framework of quantum frames can help unravel some of the interpretive difficulties i the foundation of quantum mechanics. In this paper, I begin by tracing the origins of this concept in Bohr's discussion of quantum theory and his theory of complementarity. Engaging with various interpreters and followers of Bohr, I argue that the correct account of quantum frames must be extended beyond literal space-time reference frames to frames defined by relations between a quantum system and the exosystem or external physical frame, of which measurement contexts are a particularly important example. This approach provides superior solutions to key EPR-type measurement and locality paradoxes.

Transient field for W ions traversing Fe hosts and for Os ions traversing Fe and Ni hosts

International Nuclear Information System (INIS)

Stuchbery, A.E.; Bolotin, H.H.; Doran, C.E.

1987-02-01

Transient field strengths were measured for 184 W and 186 W ions traversing thin, magnetized Fe foils with velocities in the range 1.8 ≤ v/v>=o ≤ 5.7 (v>=o Bohr velocity) and for 188 Os, 190 Os, 192 Os ions traversing polarized Ni hosts with average velocities =o> ∼ 4. The present measured transient field strengths, together with previously measured results for W, Os ions, are compared with transient-field strength parametrizations, and discussed in terms of microscopic models of the transient field

A Symposium Associated with the Opening of the Play Copenhagen in Washington

International Nuclear Information System (INIS)

Schwartz, Brian

2002-01-01

On March 2, 2002 a special all day symposium was held in conjunction with the opening of the play Copenhagen in Washington. The play Copenhagen reenacts the 1941 visit of Werner Heisenberg, who was then in charge of the Nazi nuclear power program, to Niels Bohr, his mentor, and collaborator in creating quantum mechanics, complementarity, and the uncertainty principle, in German-occupied Denmark. The symposium entitled: THE COPENHAGEN INTERPRETATION: SCIENCE AND HISTORY ON STAGE was presented at the Baird Auditorium, in the National Museum of Natural History of the Smithsonian Institution. The program consisted of three two-hour sessions: (1) The Science of Copenhagen and its Influence of the 20th Century. (2) Bohr and Heisenberg: A strong Interaction. (3) Theater as Science ??? Science as Theater. The speakers included: Robert C. Card, Under Secretary of Energy; Ulrik Federspiel, Danish Ambassador to the US; John Marburger, III, Science Advisor President Bush; Jerome I. Friedman, MIT; Lene Vestergaard Hau, Harvard University; Richard Rhodes, Author; Rita Colwell, Director, NSF; Jeremy Bernstein, Author; Jochen H. Heisenberg, University of New Hampshire; Finn Aaserud, Director of the Niels Bohr Archive; Vilhelm A. Bohr, NIH; Thomas Powers, Author; Paul Lawrence Rose, Penn State University; Steven Barfield, University of Westminster, Jennifer Uphoff Gray, Associate Director, Copenhagen; Elizabeth Ireland McCann, Producer, Copenhagen; Lloyd Rose, Washington Post. Details of he program and useful information on the play Copenhagen are available on the web site http://web.gc.cuny.edu/ashp/nml/artsci/copenhagen.shtml . The complete symposium was video recorded and the set of 3 two-hour tapes can be obtained through the web site. The symposium was organized by Brian Schwartz, The Graduate Center, CUNY, Harry Lustig, Provost Emeritus at the City College of New York and Arthur Molella, Director, Lemelson Center, Smithsonian Institution. For further information contact Brian

A Symposium Associated with the Opening of the Play Copenhagen in Washington

Energy Technology Data Exchange (ETDEWEB)

Schwartz, Brian

2002-12-31

On March 2, 2002 a special all day symposium was held in conjunction with the opening of the play Copenhagen in Washington. The play Copenhagen reenacts the 1941 visit of Werner Heisenberg, who was then in charge of the Nazi nuclear power program, to Niels Bohr, his mentor, and collaborator in creating quantum mechanics, complementarity, and the uncertainty principle, in German-occupied Denmark. The symposium entitled: THE COPENHAGEN INTERPRETATION: SCIENCE AND HISTORY ON STAGE was presented at the Baird Auditorium, in the National Museum of Natural History of the Smithsonian Institution. The program consisted of three two-hour sessions: (1) The Science of Copenhagen and its Influence of the 20th Century. (2) Bohr and Heisenberg: A strong Interaction. (3) Theater as Science ??? Science as Theater. The speakers included: Robert C. Card, Under Secretary of Energy; Ulrik Federspiel, Danish Ambassador to the US; John Marburger, III, Science Advisor President Bush; Jerome I. Friedman, MIT; Lene Vestergaard Hau, Harvard University; Richard Rhodes, Author; Rita Colwell, Director, NSF; Jeremy Bernstein, Author; Jochen H. Heisenberg, University of New Hampshire; Finn Aaserud, Director of the Niels Bohr Archive; Vilhelm A. Bohr, NIH; Thomas Powers, Author; Paul Lawrence Rose, Penn State University; Steven Barfield, University of Westminster, Jennifer Uphoff Gray, Associate Director, Copenhagen; Elizabeth Ireland McCann, Producer, Copenhagen; Lloyd Rose, Washington Post. Details of he program and useful information on the play Copenhagen are available on the web site http://web.gc.cuny.edu/ashp/nml/artsci/copenhagen.shtml . The complete symposium was video recorded and the set of 3 two-hour tapes can be obtained through the web site. The symposium was organized by Brian Schwartz, The Graduate Center, CUNY, Harry Lustig, Provost Emeritus at the City College of New York and Arthur Molella, Director, Lemelson Center, Smithsonian Institution. For further information contact Brian

On the atomic-number similarity of the binding energies of electrons in filled shells of elements of the periodic table

Science.gov (United States)

Karpov, V. Ya.; Shpatakovskaya, G. V.

2017-03-01

An expression for the binding energies of electrons in the ground state of an atom is derived on the basis of the Bohr-Sommerfeld quantization rule within the Thomas-Fermi model. The validity of this relation for all elements from neon to uranium is tested within a more perfect quantum-mechanical model with and without the inclusion of relativistic effects, as well as with experimental binding energies. As a result, the ordering of electronic levels in filled atomic shells is established, manifested in an approximate atomic-number similarity. It is proposed to use this scaling property to analytically estimate the binding energies of electrons in an arbitrary atom.

Dynamical phase transitions in quantum mechanics

International Nuclear Information System (INIS)

Rotter, Ingrid

2012-01-01

1936 Niels Bohr: In the atom and in the nucleus we have indeed to do with two extreme cases of mechanical many-body problems for which a procedure of approximation resting on a combination of one-body problems, so effective in the former case, loses any validity in the latter where we, from the very beginning, have to do with essential collective aspects of the interplay between the constituent particles. 1963: Maria Goeppert-Mayer and J. Hans D. Jensen received the Nobel Prize in Physics for their discoveries concerning nuclear shell structure. State of the art 2011: - The nucleus is an open quantum system described by a non-Hermitian Hamilton operator with complex eigenvalues. The eigenvalues may cross in the complex plane ('exceptional points'), the phases of the eigenfunctions are not rigid in approaching the crossing points and the widths bifurcate. By this, a dynamical phase transition occurs in the many-level system. The dynamical phase transition starts at a critical value of the level density. Hence the properties of he low-lying nuclear states (described well by the shell model) and those of highly excited nuclear states (described by random ensembles) differ fundamentally from one another. The statement of Niels Bohr for compound nucleus states at high level density is not in contradiction to the shell-model description of nuclear (and atomic) states at low level density. Dynamical phase transitions are observed experimentally in different systems, including PT-symmetric ones, by varying one or more parameters

Direct interaction in nuclear reactions: a theory; L'interaction directe dans les reactions nucleaires: theorie

Energy Technology Data Exchange (ETDEWEB)

Dominicis, C.T. de [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

General treatment of the foundations of direct interaction in nuclear reactions; representation of the instantaneous elastic scattering amplitude by the scattering amplitude due to a complex potential; expansion of the instantaneous inelastic scattering amplitude and discussion of the 1. Bohr approximation (distorted waves) contribution to individual and collective states of excitation. (author) [French] Expose general sur les fondements de l'interaction directe dans les reactions nucleaires; representation de l'amplitude de diffusion instantanee elastique par celle due a un potentiel complexe; developpement de l'amplitude de diffusion instantanee inelastique et discussion de la contribution de la premiere approximation de Bohr (sur des distendues) a l'excitation d'etats individuels et collectifs. (auteur)

The birth of quantum mechanics

International Nuclear Information System (INIS)

Mehra, J.

1976-01-01

In an attempt to give an exact mathematical formulation of Bohr's Correspondence Principle, Heisenberg (June 1925) discovered the rules governing the behaviour of quantum- theoretical magnitudes. In fall 1925 Born, Heisenberg and Jordan and, independently, Dirac, formulated consistent algebraic schemes of quantum mechanics. Early in 1926 Schroedinger developed wave mechanics. In quick succession were discovered: Born's probability interpretation of the wave function, the transformation theory of Dirac, Jordan and F. London, Heisenberg's Uncertainty Relations and Bohr's Principle of Complementarity. By September 1927 the basis of a complete theory of atomic phenomena had been established. Aspects of this development, in which Heisenberg played a central role, are presented here as a tribute to his memory. (Author)

A report on the Einstein-Podolski-Rosen paradox

International Nuclear Information System (INIS)

Vizh'e, Zh.P.

1982-01-01

A question on the essence and the existance as itself of causality in the world of physical phenomene is stated. The classical concepts of Laplace and Einstein determinism, used in classical and stochastic mechanics, are exposed. The Einstein-Podolski-Rosen (EPR) paradox is analysed from two viewpoints: the Bohr theory of measurements in quantum mechanics and the theory of local hidden variables. As a conclusion it is marked that the experimental results will force the physisists to made a choice between the Bohr measurements theory, from which the presens of macroscopic space-like noncausal-nonmaterial interactions follows and between the Dirac ideas about real existance of real physical subquantum level of the matter

Hydrogen-tritium exchange survey of allosteric effects in hemoglobin

International Nuclear Information System (INIS)

Englander, J.J.; Englander, S.W.

1987-01-01

The oxy and deoxy forms of hemoglobin display major differences in H-exchange behavior. Hydrogen-tritium exchange experiments on hemoglobin were performed in the low-resolution mode to observe the dependence of these differences on pH (Bohr effect), organic phosphates, and salt. Unlike a prior report, increasing pH was found to decrease the oxy-deoxy difference monotonically, in general accordance with the alkaline Bohr effect. A prior report that the H-exchange difference between oxy- and deoxyhemoglobin vanishes at pH 9, and thus appears to reflect the Bohr effect alone, was found to be due to the borate buffer used, which at high pH tends to abolish the oxy-deoxy difference in a limited region of the H-exchange curve. Effects on hemoglobin H exchange due to organic phosphates parallel the differential binding of these agents (inositol hexaphosphate more than diphosphoglycerate, deoxy more than oxy, at low pH more than at high pH). Added salt slows H exchange of deoxyhemoglobin and has no effect on the oxy form. These results display the sensitivity of simple H-exchange measurements for finding and characterizing effects on structure and dynamics that may occur anywhere in the protein and help to define conditions for higher resolution approaches that can localize the changes observed

An outline of Albert Einstein's contribution to quantum theory up to 1925

International Nuclear Information System (INIS)

Gjoetterud, K.

1979-01-01

Einstein's paper of 1905 in which he introduces the concept of light quanta, or photons, and which was mentioned as the basis of his Nobel Prize in 1920, is discussed. His discussion of the static coutent in Planck's Radiation Law and his comments on Bohr's atom model are also treated. His work on the quantum theory of radiation is treated at more length and his comments on the direction of radiation processes are quoted. Finally brief mention is made of his contributions in quantum statistics and the quantum theory of the solid state. (JIW)

Transient-field strength measurements for 52Cr traversing Fe hosts at high velocity and polarization transfer mechanisms

International Nuclear Information System (INIS)

Stuchbery, A.E.; Doran, C.E.; Byrne, A.P.; Bolotin, H.H.; Dracoulis, G.D.

1986-12-01

Transient-field strengths were measured for 52 Cr ions traversing polarized Fe hosts at velocities up to 12v>=o (v>=o = c/137 = Bohr velocity). The results are compared with predictions of various transient field parametrizations and discussed in terms of possible mechanisms by which polarization might be transferred from the Fe host to inner vacancies of the moving Cr ions. The g-factor of the first 2 + state of 52 Cr was also measured by the transient field technique and found to be in accord with shell-model calculations

Bell's theorem and the problem of decidability between the views of Einstein and Bohr.

Science.gov (United States)

Hess, K; Philipp, W

2001-12-04

Einstein, Podolsky, and Rosen (EPR) have designed a gedanken experiment that suggested a theory that was more complete than quantum mechanics. The EPR design was later realized in various forms, with experimental results close to the quantum mechanical prediction. The experimental results by themselves have no bearing on the EPR claim that quantum mechanics must be incomplete nor on the existence of hidden parameters. However, the well known inequalities of Bell are based on the assumption that local hidden parameters exist and, when combined with conflicting experimental results, do appear to prove that local hidden parameters cannot exist. This fact leaves only instantaneous actions at a distance (called "spooky" by Einstein) to explain the experiments. The Bell inequalities are based on a mathematical model of the EPR experiments. They have no experimental confirmation, because they contradict the results of all EPR experiments. In addition to the assumption that hidden parameters exist, Bell tacitly makes a variety of other assumptions; for instance, he assumes that the hidden parameters are governed by a single probability measure independent of the analyzer settings. We argue that the mathematical model of Bell excludes a large set of local hidden variables and a large variety of probability densities. Our set of local hidden variables includes time-like correlated parameters and a generalized probability density. We prove that our extended space of local hidden variables does permit derivation of the quantum result and is consistent with all known experiments.

Root Effect Haemoglobins in Fish May Greatly Enhance General Oxygen Delivery Relative to Other Vertebrates.

Directory of Open Access Journals (Sweden)

Jodie L Rummer

Full Text Available The teleost fishes represent over half of all extant vertebrates; they occupy nearly every body of water and in doing so, occupy a diverse array of environmental conditions. We propose that their success is related to a unique oxygen (O2 transport system involving their extremely pH-sensitive haemoglobin (Hb. A reduction in pH reduces both Hb-O2 affinity (Bohr effect and carrying capacity (Root effect. This, combined with a large arterial-venous pH change (ΔpHa-v relative to other vertebrates, may greatly enhance tissue oxygen delivery in teleosts (e.g., rainbow trout during stress, beyond that in mammals (e.g., human. We generated oxygen equilibrium curves (OECs at five different CO2 tensions for rainbow trout and determined that, when Hb-O2 saturation is 50% or greater, the change in oxygen partial pressure (ΔPO2 associated with ΔpHa-v can exceed that of the mammalian Bohr effect by at least 3-fold, but as much as 21-fold. Using known ΔpHa-v and assuming a constant arterial-venous PO2 difference (Pa-vO2, Root effect Hbs can enhance O2 release to the tissues by 73.5% in trout; whereas, the Bohr effect alone is responsible for enhancing O2 release by only 1.3% in humans. Disequilibrium states are likely operational in teleosts in vivo, and therefore the ΔpHa-v, and thus enhancement of O2 delivery, could be even larger. Modeling with known Pa-vO2 in fish during exercise and hypoxia indicates that O2 release from the Hb and therefore potentially tissue O2 delivery may double during exercise and triple during some levels of hypoxia. These characteristics may be central to performance of athletic fish species such as salmonids, but may indicate that general tissue oxygen delivery may have been the incipient function of Root effect Hbs in fish, a trait strongly associated with the adaptive radiation of teleosts.

Introduction

Science.gov (United States)

Bub, Jeffrey; Fuchs, Christopher A.

The great debate between Einstein and Bohr on the interpretation of quantum mechanics culminated with the Einstein-Podolsky-Rosen (EPR) paper in 1935, "Can quantum-mechanical description of physical reality be considered complete?" (Einstein, Podolsky, & Rosen, 1935, and Bohr's reply, 1935). EPR showed that composite quantum systems, consisting of widely separated subsystems, could exist in certain quantum states that they thought spelled trouble for the Copenhagen interpretation. Specifically, they argued that for such states, the correlations between the outcomes of measurements on the subsystems were incompatible with the assumption that the quantum state was a complete description of the system. They concluded that quantum mechanics was an incomplete theory-that the quantum state could not be the whole story about a system.

Controversy and consensus nuclear beta decay 1911-1934

CERN Document Server

Jensen, Carsten

2000-01-01

In 1920s, a long-lasting controversy on the interpretation of nuclear beta spectrum arose between Lise Meitner and Charles Drummond Ellis. This controversy, and the reactions from the contending parties when it was settled, reflect clearly the difference between the scientific communities in Berlin and Cambridge at that time. The Meitner-Ellis controversy ended in 1929, and it left an anomaly that attracted leading theoretical physicists. A new dispute, this time between Niels Bohr and Wolfgang Pauli, broke out. It concerned the explanation of the continuity of the primary beta particles and dominated the discussions for the next five years. Pauli argued for a new particle, and Bohr for a new theory; both suggestions were radical steps, but they reflected two different ways of doing physics.

Einstein-Bohr controversy and theory of hidden variables

Czech Academy of Sciences Publication Activity Database

Lokajíček, Miloš V.

2010-01-01

Roč. 8, č. 4 (2010), s. 638-645 ISSN 1303-5150 R&D Projects: GA MŠk LA08015 Institutional research plan: CEZ:AV0Z10100502 Keywords : Schroedinger equation * EPR paradox * hidden variables Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 0.697, year: 2010 http://arxiv.org/abs/1004.3005

(Pre-) calibration of a Reduced Complexity Model of the Antarctic Contribution to Sea-level Changes

Science.gov (United States)

Ruckert, K. L.; Guan, Y.; Shaffer, G.; Forest, C. E.; Keller, K.

2015-12-01

(Pre-) calibration of a Reduced Complexity Model of the Antarctic Contribution to Sea-level ChangesKelsey L. Ruckert1*, Yawen Guan2, Chris E. Forest1,3,7, Gary Shaffer 4,5,6, and Klaus Keller1,7,81 Department of Geosciences, The Pennsylvania State University, University Park, Pennsylvania, USA 2 Department of Statistics, The Pennsylvania State University, University Park, Pennsylvania, USA 3 Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania, USA 4 GAIA_Antarctica, University of Magallanes, Punta Arenas, Chile 5 Center for Advanced Studies in Arid Zones, La Serena, Chile 6 Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark 7 Earth and Environmental Systems Institute, The Pennsylvania State University, University Park, Pennsylvania, USA 8 Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA * Corresponding author. E-mail klr324@psu.eduUnderstanding and projecting future sea-level changes poses nontrivial challenges. Sea-level changes are driven primarily by changes in the density of seawater as well as changes in the size of glaciers and ice sheets. Previous studies have demonstrated that a key source of uncertainties surrounding sea-level projections is the response of the Antarctic ice sheet to warming temperatures. Here we calibrate a previously published and relatively simple model of the Antarctic ice sheet over a hindcast period from the last interglacial period to the present. We apply and compare a range of (pre-) calibration methods, including a Bayesian approach that accounts for heteroskedasticity. We compare the model hindcasts and projections for different levels of model complexity and calibration methods. We compare the projections with the upper bounds from previous studies and find our projections have a narrower range in 2100. Furthermore we discuss the implications for the design of climate risk management strategies.

Quantum cosmology - science of Genesis

International Nuclear Information System (INIS)

Padmanabhan, Thanu

1987-01-01

Quantum cosmology, the marriage between the theories of the microscopic and macroscopic Universe, is examined in an attempt to explain the birth of the Universe in the 'big bang'. A quantum cosmological model of the Universe does not exist, but a rough approximation, or 'poor man's' version of quantum cosmology has been developed. The idea is to combine the theory of quantum mechanics with the classical cosmological solutions to obtain a quantum mechanical version of cosmology. Such a model of quantum cosmology is described -here the quantum universe behaves like a hydrogen atom with the Planck length replacing the Bohr radius. Properties of quantum cosmologies and the significance of the Planck length are both discussed. (UK)

Processus of fission at medium energy

International Nuclear Information System (INIS)

Delagrange, H.

1977-01-01

Excitation functions for the reactions 233 U, 234 U, 235 U( 4 He,xn)Pu have been measured radiochimically between 20 and 45 MeV. Neutron emission probabilities have been deduced from these measurements, for 239 Pu, 238 Pu. These results have been analysed in the framework of a statistical model; the double humped fission barrier has been taken into account explicitly and the parameters of the barrier extracted. In the case of heavy ion reactions, fission probabilities have been calculated with the help of the Bohr-Wheeler formula and compared to experimental data from other authors. Deduced fission parameters (asub(f)/asub(n), Bsub(f)) are compared to different theoretical models [fr

Historic physics reprints come home : six boxes of historic reprints have returned home to Pauli's Library

CERN Multimedia

Maximilien Brice

2005-01-01

The 146 items - preprints by Born, Bohr, Heisenberg and others some with dedications to Pauli from the author - had been part of the personal library of the Nobel prize-winning physicist, Wolfgang Pauli.

Book review

CERN Multimedia

1967-01-01

Niels Bohr. His life and work as seen by his friends and colleagues, edited by S. Rozentai. Translated from the Danish edition published in 1964. (Amsterdam, North- Holland Publishing Company, 1967, 58 s.)

to view fulltext PDF

Indian Academy of Sciences (India)

, USA bass@phy.duke.edu. Basu Madhumita, Physics Department, Bangabasi College, Kolkata 700 009. Bearden Ian, Niels Bohr Institute, Blegdamsvej 17, 2100 Kobenhavn, Denmark bearden@nbi.dk. Bhalerao Rajeev, Tata Institute of ...

A critical review on some aspects of the theory of fission

International Nuclear Information System (INIS)

Pauli, H.C.

1981-01-01

The lecture notes display briefly some of the facets which eventually will be part of a theory for the fission process. They cover some important aspects of our present understanding in a qualitative fashion and complement the existing review articles rather than replacing them. The notes include sections on (I) The Bohr-Wheeler Fission of a Drop, (II) The Strutinsky-Swiatecki Quantum Droplet, (III) The Question of Inertias of a Fluid in Motion, (IV) Some Selected Aspects of the Distributions of Mass and Kinetic Energy, and (V) Possible Relations Between the Phenomenological Models and Self-Consistent Field Approximations. (author)

Student perception and conceptual development as represented by student mental models of atomic structure

Science.gov (United States)

Park, Eun Jung

The nature of matter based upon atomic theory is a principal concept in science; hence, how to teach and how to learn about atoms is an important subject for science education. To this end, this study explored student perceptions of atomic structure and how students learn about this concept by analyzing student mental models of atomic structure. Changes in student mental models serve as a valuable resource for comprehending student conceptual development. Data was collected from students who were taking the introductory chemistry course. Responses to course examinations, pre- and post-questionnaires, and pre- and post-interviews were used to analyze student mental models of atomic structure. First, this study reveals that conceptual development can be achieved, either by elevating mental models toward higher levels of understanding or by developing a single mental model. This study reinforces the importance of higher-order thinking skills to enable students to relate concepts in order to construct a target model of atomic structure. Second, Bohr's orbital structure seems to have had a strong influence on student perceptions of atomic structure. With regard to this finding, this study suggests that it is instructionally important to teach the concept of "orbitals" related to "quantum theory." Third, there were relatively few students who had developed understanding at the level of the target model, which required student understanding of the basic ideas of quantum theory. This study suggests that the understanding of atomic structure based on the idea of quantum theory is both important and difficult. Fourth, this study included different student assessments comprised of course examinations, questionnaires, and interviews. Each assessment can be used to gather information to map out student mental models. Fifth, in the comparison of the pre- and post-interview responses, this study showed that high achieving students moved toward more improved models or to advanced

Heating electrons with ion irradiation: A first-principles approach

International Nuclear Information System (INIS)

Pruneda, J.M.; Sanchez-Portal, D.; Arnau, A.; Juaristi, J.I.; Artacho, E.

2009-01-01

Using time-dependent density functional theory we calculate from first-principles the rate of energy transfer from a moving charged particle to the electrons in an insulating material. The behavior of the electronic stopping power in LiF (a wide band gap insulator) versus projectile velocity displays an effective threshold velocity of 8.2 Bohr/asec for the proton, consistent with recent experimental observations. The calculated proton/antiproton stopping power ratio is 2.4 at velocities slightly above the threshold (16.5 Bohr/asec) as compared to the experimental value of 2.1. The approximations introduced in this new non-perturbative methodology are discussed, and results on the velocity dependence of the stopping power, the locality of the energy transfer, and other characteristics of the host material are presented.

Introducing quantum theory a graphic guide

CERN Document Server

McEvoy, J P

2013-01-01

Quantum theory confronts us with bizarre paradoxes which contradict the logic of classical physics. At the subatomic level, one particle seems to know what the others are doing, and according to Heisenberg's "uncertainty principle", there is a limit on how accurately nature can be observed. And yet the theory is amazingly accurate and widely applied, explaining all of chemistry and most of physics. "Introducing Quantum Theory" takes us on a step-by-step tour with the key figures, including Planck, Einstein, Bohr, Heisenberg and Schrodinger. Each contributed at least one crucial concept to the theory. The puzzle of the wave-particle duality is here, along with descriptions of the two questions raised against Bohr's "Copenhagen Interpretation" - the famous "dead and alive cat" and the EPR paradox. Both remain unresolved.

Fulltext PDF

Indian Academy of Sciences (India)

twentieth century - the relativity theories and quantum ... major contributions coming from Planck, Einstein,. Bohr and .... cessful union of special relativity with quantum particles of ... the explanation of many puzzling features of the electron - its ...

Fulltext PDF

Indian Academy of Sciences (India)

Catholic church, his godfather being the physicist - philosopher Ernst Mach. ... in 1918. He then joined Arnold Sommerfeld as a student in Munich, and ... and its orthodox or Copenhagen interpretation created by Bohr, Heisenberg and Pauli.

Inauguration of Proton Synchrotron

CERN Multimedia

1960-01-01

On 5 February 1960, the Proton Synchrotron (PS) was formally inaugurated. The great Danish physicist, Niels Bohr, releases a bottle of champagne against a shielding block to launch the PS on its voyage in physics.

[The function of analogies in natural sciences, also in contrast to metaphors and models].

Science.gov (United States)

Hentschel, Klaus

2010-01-01

This introduction surveys the various functions of analogies in science, medicine and technology. The focus is on their heuristic importance. The productiveness of analogies is linked to the systematic depth and breadth of the established connections. Various examples are presented from different periods in the history of science, most notably Galileo; such late-Victorian Maxwellians as George Francis FitzGerald and Oliver Lodge; and Heinrich HERTZ and Niels BOHR. These examples are examined in terms of the specific differing temporal ranges of their claimed validities. They serve as evidence or counterevidence for various systematic analyses of analogies as put forward by various philosophers of science, most notably Francis Bacon, John Stuart Mill, Ernst Mach, Harald Høffding, Ernest Nagel, Mary Hesse and Peter Achinstein. The analytic framework for analogies supported here is what the cognitive scientist Dedre Gentner has termed structure-mapping.

At WA7

CERN Multimedia

1977-01-01

The CERN-Genoa-Annecy(LAPP)- Niels Bohr Institute, Copenhagen-Oslo-University College,London Collaboration set-up the experiment WA7 to study two-body reactions at large transverse momentum. Here, Michel Yvert, Alberto Santronico, Per Carlson

What hope is there for South Africa? A public theological reflection ...

African Journals Online (AJOL)

2015-04-29

Apr 29, 2015 ... As the Danish physicist, Niels Bohr, rightly said: 'Prediction is very difficult, especially if it ..... sanitation, electricity and refuse removal have also increased in ..... Real final consumption expenditure (FCE) per capita labour force ...

Miscasting, TV adaptation inhibit 'Copenhagen' drama

CERN Multimedia

Winn, S

2002-01-01

Review of a television adaptation of the play 'Copenhagen', produced by Howard Davies for PBS, USA . The play speculates on the real reason that Werner Heisenberg came to see Niels Bohr in Copenhagen in 1941 (1 page).

Classroom

Indian Academy of Sciences (India)

responses, or both. "Classroom" is equally a forum for raising broader issues and .... Research Institute, Bangalore ... From Bohr's theory we can calculate v = (En - En -1) / h the ... important reason for the failure of the qualitative arguments. An.

A double-slit 'which-way' experiment on the complementarity-uncertainty debate

International Nuclear Information System (INIS)

Mir, R; Lundeen, J S; Mitchell, M W; Steinberg, A M; Garretson, J L; Wiseman, H M

2007-01-01

A which-way measurement in Young's double-slit will destroy the interference pattern. Bohr claimed this complementarity between wave- and particle-behaviour is enforced by Heisenberg's uncertainty principle: distinguishing two positions at a distance s apart transfers a random momentum q ∼ ℎ/s to the particle. This claim has been subject to debate: Scully et al (1991 Nature 351 111) asserted that in some situations interference can be destroyed with no momentum transfer, while Storey et al (1994 Nature 367 626) asserted that Bohr's stance is always valid. We address this issue using the experimental technique of weak measurement. We measure a distribution for q that spreads well beyond [-ℎ/s, ℎ/s], but nevertheless has a variance consistent with zero. This weak-valued momentum-transfer distribution P wv (q) thus reflects both sides of the debate

ancei--ju-iy

Indian Academy of Sciences (India)

Later, John Wheeler and Bohr ex- ... probability that two particles with similar sign get very close is zero. Gamow realised that quantum tunneling can make this probability non-zero (al- ... league Robert Herman, he was the first to develop.

Comments on microscopic mechanics, generalizations of classical mechanics and Planck's oscillators

International Nuclear Information System (INIS)

Yussouff, M.

1983-05-01

The new microscopic mechanics removes the dichotomy of physics into classical and quantum phenomena. Its physical picture and connections with generalizations of classical mechanics are discussed. It gives a new meaning to Bohr's frequency relation and Planck's oscillators. (author)

Back to the Future

CERN Multimedia

Collins, Graham

2004-01-01

"Predictions are hard to make, especially about the future" said Nobel physicist Niels Bohr, many years ago. But two months ago, 150 leading physicists gathered at the University of California to engage in just that daunting task (1 page)

Joint probabilities reproducing three EPR experiments on two qubits

NARCIS (Netherlands)

Roy, S. M.; Atkinson, D.; Auberson, G.; Mahoux, G.; Singh, V.

2007-01-01

An eight-parameter family of the most general non-negative quadruple probabilities is constructed for EPR-Bohm-Aharonov experiments when only three pairs of analyser settings are used. It is a simultaneous representation of three different Bohr-incompatible experimental configurations involving

Critique of the quantum power of judgment. A transcendental foundation of quantum objectivity

International Nuclear Information System (INIS)

Pringe, H.

2007-01-01

In this book Kant's critique of pure ratio is considered in the framework of quantum mechanics. In this connections Bohr's thought is considered with a short view on the EPR paradox. Finally a transcendental foundation of quantum mechanics is presented. (HSI)

GROGi-F. Modified version of GROGi 2 nuclear evaporation computer code including fission decay channel

International Nuclear Information System (INIS)

Delagrange, H.

1977-01-01

This report is the user manual of the GR0GI-F code, modified version of the GR0GI-2 code. It calculates the cross sections for heavy ion induced fission. Fission probabilities are calculated via the Bohr-Wheeler formalism

Effect of laser radiation on physicochemical and functional properties of human hemoglobin in vitro

NARCIS (Netherlands)

Irzhak, LI; Zotova, EA; Mamaeva, SA

Exposure to laser radiation increases pH and isoelectric point of human hemoglobin solution, improves the acid-base properties, increases affinity for oxygen, and decreases the Bohr effect in comparison with intact hemoglobin. The mechanisms underlying these changes are discussed.

Einstein as Armchair Detective: The Case of Stimulated Radiation

Indian Academy of Sciences (India)

theory and of gravity in the case of the general theory. It might be argued that the ... the radiation density p at different frequencies through. Planck's law. He assumes .... derive both Planck's law and Bohr's principle based on these hypotheses.

Physics in the twentieth century. A selection of papers. La physique du XXe siecle. Morceaux choisis

Energy Technology Data Exchange (ETDEWEB)

Weisskopf, V F

1974-01-01

A number of papers from Victor F. Weisskopf have been collected in this book. The papers included in the first part are dealing with basic concepts in quantum mechanics. Particle-wave duality, quantum scale, and the Niels Bohr works. Papers in the second part describe the recent developments in the physics field during the 20th century: the electron theory, compound nucleus, nuclear structure, and quantum theory of elementary particles. The third part is concerned with peculiar cases: nuclear models, the Lorentz relativistic contraction, light-matter interaction, parity decay, and symmetry. In the fourth part are gathered papers on sciences in general, for which they present a sort of natural philosophy.

Dynamics of the Vacuum and Casimir Analogs to the Hydrogen Atom

Science.gov (United States)

White, Harold; Vera, Jerry; Bailey, Paul; March, Paul; Lawrence, Tim; Sylvester, Andre; Brady, David

2015-01-01

This paper will discuss the current viewpoint of the vacuum state and explore the idea of a "natural" vacuum as opposed to immutable, non-degradable vacuum. This concept will be explored for all primary quantum numbers to show consistency with observation at the level of Bohr theory. A comparison with the Casimir force per unit area will be made, and an explicit function for the spatial variation of the vacuum density around the atomic nucleus will be derived. This explicit function will be numerically modeled using the industry multi-physics tool, COMSOL(trademark), and the eigenfrequencies for the n = 1 to n = 7 states will be found and compared to expectation.

Binding energy of two-dimensional biexcitons

DEFF Research Database (Denmark)

Singh, Jai; Birkedal, Dan; Vadim, Lyssenko

1996-01-01

Using a model structure for a two-dimensional (2D) biexciton confined in a quantum well, it is shown that the form of the Hamiltonian of the 2D biexciton reduces into that of an exciton. The binding energies and Bohr radii of a 2D biexciton in its various internal energy states are derived...... analytically using the fractional dimension approach. The ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be 0.228, which agrees very well with the recent experimental value. The results of our approach are compared with those of earlier theories....

Photoluminescence decay dynamics in γ-Ga2O3 nanocrystals: The role of exclusion distance at short time scales

Science.gov (United States)

Fernandes, Brian; Hegde, Manu; Stanish, Paul C.; Mišković, Zoran L.; Radovanovic, Pavle V.

2017-09-01

We developed a comprehensive theoretical model describing the photoluminescence decay dynamics at short and long time scales based on the donor-acceptor defect interactions in γ-Ga2O3 nanocrystals, and quantitatively determined the importance of exclusion distance and spatial distribution of defects. We allowed for donors and acceptors to be adjacent to each other or separated by different exclusion distances. The optimal exclusion distance was found to be comparable to the donor Bohr radius and have a strong effect on the photoluminescence decay curve at short times. The importance of the exclusion distance at short time scales was confirmed by Monte Carlo simulations.

ODE/IM correspondence and the Argyres-Douglas theory

Science.gov (United States)

Ito, Katsushi; Shu, Hongfei

2017-08-01

We study the quantum spectral curve of the Argyres-Douglas theories in the Nekrasov-Sahashvili limit of the Omega-background. Using the ODE/IM correspondence we investigate the quantum integrable model corresponding to the quantum spectral curve. We show that the models for the A 2 N -type theories are non-unitary coset models ( A 1)1 × ( A 1) L /( A 1) L+1 at the fractional level L=2/2N+1-2 , which appear in the study of the 4d/2d correspondence of N = 2 superconformal field theories. Based on the WKB analysis, we clarify the relation between the Y-functions and the quantum periods and study the exact Bohr-Sommerfeld quantization condition for the quantum periods. We also discuss the quantum spectral curves for the D and E type theories.

Theory of threshold phenomena

International Nuclear Information System (INIS)

Hategan, Cornel

2002-01-01

Theory of Threshold Phenomena in Quantum Scattering is developed in terms of Reduced Scattering Matrix. Relationships of different types of threshold anomalies both to nuclear reaction mechanisms and to nuclear reaction models are established. Magnitude of threshold effect is related to spectroscopic factor of zero-energy neutron state. The Theory of Threshold Phenomena, based on Reduced Scattering Matrix, does establish relationships between different types of threshold effects and nuclear reaction mechanisms: the cusp and non-resonant potential scattering, s-wave threshold anomaly and compound nucleus resonant scattering, p-wave anomaly and quasi-resonant scattering. A threshold anomaly related to resonant or quasi resonant scattering is enhanced provided the neutron threshold state has large spectroscopic amplitude. The Theory contains, as limit cases, Cusp Theories and also results of different nuclear reactions models as Charge Exchange, Weak Coupling, Bohr and Hauser-Feshbach models. (author)

Bohr Hamiltonian with different mass parameters applied to band ...

Indian Academy of Sciences (India)

The band structure of the proton-odd nuclei 153,155Eu, built on Nilsson orbitals, is .... [6]. When m = 0, the angular momentum vector of the prolate core is .... For the relevant results, figures 1 and 2, it is meaningful to discuss the quality of cal-.

Horizons of description: Black holes and complementarity

Science.gov (United States)

Bokulich, Peter Joshua Martin

Niels Bohr famously argued that a consistent understanding of quantum mechanics requires a new epistemic framework, which he named complementarity . This position asserts that even in the context of quantum theory, classical concepts must be used to understand and communicate measurement results. The apparent conflict between certain classical descriptions is avoided by recognizing that their application now crucially depends on the measurement context. Recently it has been argued that a new form of complementarity can provide a solution to the so-called information loss paradox. Stephen Hawking argues that the evolution of black holes cannot be described by standard unitary quantum evolution, because such evolution always preserves information, while the evaporation of a black hole will imply that any information that fell into it is irrevocably lost---hence a "paradox." Some researchers in quantum gravity have argued that this paradox can be resolved if one interprets certain seemingly incompatible descriptions of events around black holes as instead being complementary. In this dissertation I assess the extent to which this black hole complementarity can be undergirded by Bohr's account of the limitations of classical concepts. I begin by offering an interpretation of Bohr's complementarity and the role that it plays in his philosophy of quantum theory. After clarifying the nature of classical concepts, I offer an account of the limitations these concepts face, and argue that Bohr's appeal to disturbance is best understood as referring to these conceptual limits. Following preparatory chapters on issues in quantum field theory and black hole mechanics, I offer an analysis of the information loss paradox and various responses to it. I consider the three most prominent accounts of black hole complementarity and argue that they fail to offer sufficient justification for the proposed incompatibility between descriptions. The lesson that emerges from this

Nuclear structure 1985

International Nuclear Information System (INIS)

Broglia, R.; Hagemann, G.; Herskind, B.

1985-01-01

These proceedings of the Niels Bohr Centennial Conference contains 40 lectures in nuclear physics ranging over the following subjects: single particle motion; collective motion at low excitation energy; collective motion at high angular momentum; giant resonances and nuclear forces. (G.J.P.)

PbSe Nanorod Field-Effect Transistors : Room- and Low-Temperature Performance

NARCIS (Netherlands)

Han, Lu; Balazs, Daniel M.; Shulga, Artem G.; Abdu-Aguye, Mustapha; Ma, Wanli; Loi, Maria Antonietta

Lead chalcogenides with large exciton Bohr radius display strong quantum confinement, which make them applicable in a wide range of optoelectronic devices such as solar cells and photodetectors. Especially, 1D PbSe nanocrystals attract much attention with their potential for multiple exciton

A Review on hematology and hemoglobin of fish

Directory of Open Access Journals (Sweden)

Ebru YILMAZ

2015-01-01

Full Text Available Determination of hematological parameters of fish living in natüre helps to recognize population and to determinate of pollutants in the aquatic environment. In this review, hematological parameters of fish, fish hemoglobin and the Bohr effect were given information.

Semiclassical multicomponent wave function

NARCIS (Netherlands)

Mostovoy, M.V.

A consistent method for obtaining the semiclassical multicomponent wave function for any value of adiabatic parameter is discussed and illustrated by examining the motion of a neutral particle in a nonuniform magnetic field. The method generalizes the Bohr-Sommerfeld quantization rule to

19 November 2014 - C. Staur Ambassador Permanent Representative of Denmark to the United Nations Office and other international organisations in Geneva

CERN Multimedia

Brice, Maximilien

2014-01-01

signing the Guest book with CERN Director-General R. Heuer and visiting the ATLAS cavern with ATLAS Collaboration, Former Spokesperson P. Jenni, ATLAS Collaboration, University of Copenhagen M. Dam and Niels Bohr Institute, University of Copenhagen, senior ATLAS Denmark member P. Hansen.

The 1956 CERN Symposium

CERN Document Server

Jarlskog, Cecilia

2014-01-01

CERN, currently the largest organization in the world for particle physics, was founded in 1954. Originally located in Meyrin, at the outskirts of the city of Geneva in Switzerland, it has with time extended into neighboring France. The Theoretical Study Division of CERN, however, was created already in 1952, i.e., before the official inauguration of CERN. It was situated in Copenhagen. Christian Møller [1] was appointed (part-time) as the Director and there were two full time senior staff members, Gunnar Källén and Ben R. Mottelson. While constructing buildings and accelerators were in progress, an international conference was organized by CERN in the city of Geneva. This “CERN Symposium on High Energy Accelerators and Pion Physics”, 11–23 June 1956, attracted about 250 participants from outside CERN, among them at least 18 Nobel Laureates or future Laureates. Unfortunately, the participants from CERN are not listed in the Proceedings [2]. The conference focused on measuring devices such as bubbl...

Report of the Study Group on Complete Spectroscopy

International Nuclear Information System (INIS)

Garrett, J.D.

1989-01-01

This report summarizes the topics considered in four discussions of about two hours each attended by most of the workshop participants. The contents of the lectures of David Radford, Fumihiko Sakata, Ben Mottelson, and Jerry Garret pertaining to Complete Spectroscopy are contained elsewhere in this proceedings. Most detailed nuclear structure information is derived from measurements of the spectroscopic properties (e.g. excitation energies, angular momenta, parities, lifetimes, magnetic moments, population cross sections, methods of decay, etc.) of discrete nuclear eigenstates. The present instrumentation allows in the best cases such measurements to approach the angular momentum limit imposed by fission and to as many as fifteen different excited bands. In anticipation of the new generation of detection equipment, such as the EUROBall and the GAMMASPHERE, the Complete Spectroscopy Study Group attempted to define the limits to such studies imposed by physical considerations and to consider some of the new, interesting physics that can be addressed from more complete discrete spectroscopic studies. 28 refs

CMS Centre at CERN

CERN Multimedia

2007-01-01

A new "CMS Centre" is being established on the CERN Meyrin site by the CMS collaboration. It will be a focal point for communications, where physicists will work together on data quality monitoring, detector calibration, offline analysis of physics events, and CMS computing operations. Construction of the CMS Centre begins in the historic Proton Synchrotron (PS) control room. The historic Proton Synchrotron (PS) control room, Opened by Niels Bohr in 1960, will be reused by CMS to built its control centre. TThe LHC@FNAL Centre, in operation at Fermilab in the US, will work very closely with the CMS Centre, as well as the CERN Control Centre. (Photo Fermilab)The historic Proton Synchrotron (PS) control room is about to start a new life. Opened by Niels Bohr in 1960, the room will be reused by CMS to built its control centre. When finished, it will resemble the CERN Contro...

3 minutes to understand the 50 greatest theories of quantum physics

International Nuclear Information System (INIS)

Clegg, Brian; Ball, Philip; Clifford, Leon; Close, Frank; Hebden, Sophie; Hellemans, Alexander; Holgate, Sharon Ann; May, Andrew; Martinez, Rachel; Dubois, Richard

2015-01-01

This book aims at using 2 pages, 300 words and 1 image to explain each of the 50 most important theories of quantum physics. After a first part addressing the origins of the theory (Planck quanta, the photoelectric effect according to Einstein, the predictable Balmer series, the Bohr's atom, the wave/particle duality, the matter waves of De Broglie, the double quantum slit), the chapters address basic notions (quantum spin, matrix mechanics, Schroedinger's equation and cat, the Heisenberg uncertainty principle, the wave function reduction, the decoherence), light and matter physics, quantum effects and their interpretation, quantum entanglement, quantum applications, and quantum extremes. Each chapter proposes a glossary, a presentation of specific issues according to the adopted format, and a portrait of a scientist involved in the addressed topics (Niels Bohr, Erwin Schroedinger, Paul Dirac, David Bohm, John Bell, Brian Josephson, and Satyendra Nath Bose)

G+K 1Σ+/sub g/ double-minimum excited state of H2

International Nuclear Information System (INIS)

Glover, R.M.; Weinhold, F.

1977-01-01

We have obtained a Born--Oppenheimer potential curve for the previously uncharacterized third 1 Σ + /sub g/ state of H 2 , using a correlated 20-term wavefunction of generalized James--Coolidge type. We find this potential curve to have a double-minimum character, with the inner (Rydberg-like) and outer (''ionic'') wells having minima at about 1.99 and 3.30 bohr, respectively, and an intervening maximum at 2.76 bohr. Unlike the extensively studied E+F double-minimum state, the outer well here appears to be the deeper, by some 450 cm -1 in our calculation. The inner and outer minima can apparently be associated with spectral lines that in experimental tables have previously been attributed to distinct G and K electronic states. The appropriate spectroscopic term symbol of this combined state is accordingly G+K 1 Σ + /sub g/ (1ssigma3dsigma+2pπ 2 )

Reviving Complementarity: John Wheeler's efforts to apply complementarity toward a quantum description of gravitation

Science.gov (United States)

Halpern, Paul

2017-01-01

In 1978, John Wheeler proposed the delayed-choice thought experiment as a generalization of the classic double slit experiment intended to help elucidate the nature of decision making in quantum measurement. In particular, he wished to illustrate how a decision made after a quantum system was prepared might retrospectively affect the outcome. He extended his methods to the universe itself, raising the question of whether the universe is a ``self-excited circuit'' in which scientific measurements in the present affect the quantum dynamics in the past. In this talk we'll show how Wheeler's approach revived the notion of Bohr's complementarity, which had by then faded from the prevailing discourse of quantum measurement theory. Wheeler's advocacy reflected, in part, his wish to eliminate the divide in quantum theory between measurer and what was being measured, bringing greater consistency to the ideas of Bohr, a mentor whom he deeply respected.

Measurement of Forward-Backward Charged Particle Correlations with ALICE

DEFF Research Database (Denmark)

Søgaard, Carsten

Part I of the defence covers experimental development carried out in the ALICE experiment at the Large Hadron Collider at the European Organisation for Nuclear Research - CERN. For the Time Projection Chamber a sophisticated laser calibration system has been developed by the Niels Bohr Institute...

Structural and magnetic studies on copper succinate dihydrate

Indian Academy of Sciences (India)

The four bis-bidendate succinate anions form syn–syn bridges among two copper atomsto form a polymeric two-dimensional chain. From room temperature vibrating sample magnetometer (VSM) studies themagnetic moment of the material is calculated as 1.35 Bohr magneton (BM), indicating antiferromagnetic interaction ...

Critique of the quantum power of judgment. A transcendental foundation of quantum objectivity

Energy Technology Data Exchange (ETDEWEB)

Pringe, H.

2007-07-01

In this book Kant's critique of pure ratio is considered in the framework of quantum mechanics. In this connections Bohr's thought is considered with a short view on the EPR paradox. Finally a transcendental foundation of quantum mechanics is presented. (HSI)

Tunable band gap emission and surface passivation of germanium nanocrystals synthesized in the gas phase

NARCIS (Netherlands)

Wheeler, LM; Levij, L.M.; Kortshagen, U.R.

2013-01-01

The narrow bulk band gap and large exciton Bohr radius of germanium (Ge) make it an attractive material for optoelectronics utilizing band-gap-tunable photoluminescence (PL). However, realization of PL due to quantum confinement remains scarcely reported. Instead, PL is often observed from surface

Fulltext PDF

Indian Academy of Sciences (India)

Dirac : I am trying to get a relativistic theory of the electron. Bohr : But .... the difference in energy as radiation? .... ory is now recognized as a general law of nature: To every ... have to obey Pauli's principle and Fermi-Dirac statistics. The other ...

Quantum States of Neutron in Earth's Gravitational Field

Indian Academy of Sciences (India)

Keywords. Neutron; gravitational field; Bohr-Sommerfeld-Wilson quantization; projectile motion; elastic collision; Olympiad. Author Affiliations. Vijay A Singh1 Praveen Pathak1 K Krishna Chaitanya2. Homi Bhabha Centre For Science Education (TIFR), V N Purav Marg, Mankhurd Mumbai 400088, India. Physics Department ...

From Nancy to Copenhagen to the World: The internationalization of Laurent Schwartz and his theory of distributions

DEFF Research Database (Denmark)

Barany, Michael J.; Paumier, Anne-Sandrine; Lützen, Jesper

2017-01-01

Nancy, via Copenhagen, to the world stage, culminating in his 1950 Fields Medal awarded in Cambridge, Massachusetts. We identify, based on new archival findings, the pivotal role of Danish mathematician Harald Bohr along this trajectory. Our analysis reveals the emerging dynamics of early postwar...

Resonance – Journal of Science Education | Indian Academy of ...

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education. Dipankar Home. Articles written in Resonance – Journal of Science Education. Volume 18 Issue 10 October 2013 pp 905-916 General Article. Bohr's Philosophy of Wave–Particle Complementarity · Dipankar Home · More Details Fulltext PDF ...

Quark approach to Santilli's conjecture on hadronic structure - II

International Nuclear Information System (INIS)

Animalu, A.O.E.

1982-08-01

In this paper, we continue an earlier investigation of an exactly soluble relativistic Bohr-type model of the internal structure of the proton (three-quark baryon system) and the pion (quark-antiquark meson system), based on a realization of Santilli's conjecture that the hadronic constituents are extended (non-pointlike) objects. The model is abstracted from an expansion of a Yukawa-type potential between the valence quarks and a massive core, in which the meson or gluon exchange term has the effect of reducing the effective Bohr radius for binding to a value less than the radius of the strong charge sphere (or Compton wavelength) of each constituent, so that appreciable overlap of charge volumes occurs, to within a typical distance of order 0.25F or 1/(800 MeV) in qqq-system, and order 1/(1200 MeV) in qq-bar-system, which are comparable to gluon masses, msub(G) approx.= 800 to 1200 MeV, required by the lattice QCD and the MIT Bag Model. Based on the assumptions that the ground state of the proton has 1s 2 2s valence quark configuration, the non-strange quark mass is msub(p)/3, and the dimensionless strong coupling constant of the Yukawa-type potential is g 2 =1, the mass of the proton core is determined self-consistently to be 2470 MeV, exactly balancing the quark binding energy so that the valence quarks appear free. The model correctly predicts the masses of the well-known resonant states of the proton with Jsup(P)=1/2 + as excited states associated with the configuration 1s2s 2 and predicts an upper bound (spectroscopic limit) for the mass of the excited states of the proton in ns 2 ms configuration, as n→infinity and m→infinity, to be 3409 MeV. Based on a generalization of the model to qq-bar-systems, an upper bound (spectroscopic limit) for the mass of qq-bar in ns 2 configuration, as n→infinity, is found to be 3096 MeV, which is the mass of the J/psi-meson. The relation of the model to violation of time-reversal invariance (T-symmetry) by non

Historia y filosofía de las ciencias en la educación polimodal: propuesta para su incorporación al aula History and philosophy of science in science curricula: a proposal for its incorporation in science classes

Directory of Open Access Journals (Sweden)

Verónica Guridi

2004-12-01

Full Text Available Durante los últimos años se viene enfatizando la necesidad de la incorporación de la Historia y Filosofía de las Ciencias (HFC, en adelante a los currículos de Ciencias. Mucho se ha avanzado respecto de la definición de los marcos teóricos que debieran orientar la incorporación de la HFC en la Enseñanza de las Ciencias, pero sin embargo son pocos los trabajos que muestran propuestas concretas de incorporación de la HFC en las clases de Ciencias. Este trabajo intenta realizar un aporte en el sentido antes mencionado, presentando una propuesta para el tratamiento de un núcleo temático específico correspondiente al primer año Polimodal (orientación Humanidades y Ciencias Sociales en el espacio curricular Físico - Química. El núcleo temático seleccionado corresponde al estudio de la evolución de los modelos atómicos (hasta el modelo atómico de Bohr.In the last few years the necessity of including History and Philosophy of Science (HFC, hereafter in Science Curricula has been emphasised. There have been important advances in theoretical frameworks, which should orient the incorporation of HFC into Science classes. However, there are only a few works that include proposals that show some ways of making this concrete. This work attempts to make a contribution in that direction, presenting a proposal for the treatment of a specific thematic nucleus of the curricular area "Physics-Chemistry". The proposal is designed for the first year of High School Education (with orientation in Humanities and Social Sciences. The selected content corresponds to the study of the evolution of atomic models (up to the model of Bohr.

Is Quantum Mechanics a Complete Theory?: A Philosophical ...

African Journals Online (AJOL)

In 1935, Einstein, Podolsky, and Rosen published their thought experiment I a paper entitled, “Can Quantum – Mechanical Description of Physical Reality be considered complete?”. At that time, Bohr, Heisenberg, and the proponents of the Copenhagen interpretation of Quantum mechanics, were saying that Quantum ...

Erratum: Back reaction, emission spectrum and entropy spectroscopy

Science.gov (United States)

Jiang, Qing-Quan; Cai, Xu

2012-06-01

In our paper [Qing-Quan Jiang and Xu Cai, Back reaction, emission spectrum and entropy spectroscopy, JHEP 11 (2010) 066], there was an error in using the first law of black hole thermodynamic and the Bohr-Sommerfeld quantization rule. In this erratum, we attempt to rectify them.

Science through the looking glass of literature

NARCIS (Netherlands)

Saris, F.W.

2005-01-01

The scientific revolution brought about by Einstein, Lorentz, Bohr, Heisenberg and others has changed our society and our worldview, as is reflected also in literature, fiction as well as non-fiction. Of course we need textbooks to teach relativity, cosmology and quantum mechanics, but I think

EPR: how subtle is the Lord and how is the Lord subtle?

Science.gov (United States)

Plotnitsky, Arkady

The article offers a counterargument to the argument of A. Einstein, B. Podolsky and N. Rosen (EPR) concerning the incompleteness, or else nonlocality, of quantum mechanics, based on Bohr's reply to EPR's article. The article also relates argument to the impossibility of exact repetition of quantum events.

Classical quantum theory of wobbling modes

International Nuclear Information System (INIS)

Onishi, Naoki

1986-01-01

Wobbling modes are studied extensively in terms of time-dependent variational theory. Quantum states and their energies are determined by the Bohr-Sommerfeld rule of classical quantization. Numerical calculations are performed for states of 166 Er with vertical strokejvertical stroke=30-40 (h/2π). (orig.)

We All Want to Live Longer and Nobody Wants to be Called Old. In: Oldetopia - an Exhibition on Age and Ageing

DEFF Research Database (Denmark)

Otto, Lene

Kataloget bag udstillingen Oldetopia, vist på Medicinsk Museion fra den 12. oktober 2007 til den 14. december 2008. Bidrag af Camilla Mordhorst, Bente Vinge Pedersen, Thomas Söderqvist, Bente Klarlund Pedersen, Mette Sørensen, Tinna Stevnsner, Vilhelm A. Bohr, Bernard Jeune, Liv Carlé Mortensen, ...

UNESCO accolade for former DG

CERN Multimedia

2006-01-01

Former CERN Director General, Herwig Schopper, has been awarded the UNESCO Niels Bohr Gold Medal award. He shares this year's distinction with two other recipients: Sir Martin Rees, Britain's astronomer royal, and Professor Peter Zoller, a central figure in the field of quantum information. Herwig Schopper (left) receiving the 2005 Niels Bohr Gold Medal from Helge Sander, Denmark's Minister of Science, Technology and Innovation. The awards, which took place at the Danish Royal Academy of Science and Letters on 15 November, recognise scientific excellence, concern for the impact of science, and efforts to promote the free exchange of ideas on a broad international scale. Herwig Schopper was Director-General of CERN from 1981 to 1988. Today, he is President of the SESAME Council, the International Centre for Synchrotron Light for Experimental Science and Applications in the Middle East (see Bulletin No. 26/2003). In his opening address at the ceremony, Jens Jørgen Gaardhøje, from the Danish National Commi...

André Petermann (1922-2011)

CERN Multimedia

2012-01-01

The CERN theory community mourns the loss of André Petermann, one of the first members of the Theory Division, who passed away last August in his 89th year. He pioneered, together with his advisor Stueckelberg, the renormalization group, one of the fundamental ideas in quantum field theory that underlies the modern theory of phase transitions as well as asymptotic freedom and the quest for unification of all the particle interactions.   André was among the very first staff members of CERN, which at the beginning was a small group of theorists at the Niels Bohr Institute in Copenhagen, headed by Bohr himself.  When the group moved to Geneva, they first occupied a set of barracks in Cointrin, next to the airport, before moving to the University of Geneva, and then finally settling on the Meyrin site. André was our last direct contact with our nomadic origins. The importance of André’s early work on the renormalization group was recogn...

Measurability of quantum fields and the energy-time uncertainty relation

International Nuclear Information System (INIS)

Mensky, Mikhail B

2011-01-01

Quantum restrictions on the measurability of an electromagnetic field strength and their relevance to the energy-time uncertainty relation are considered. The minimum errors in measuring electromagnetic field strengths, as they were estimated by the author (1988) in the framework of the phenomenological method of restricted path integral (RPI), are compared with the analogous estimates found by Landau and Peierls (1931) and by Bohr and Rosenfeld (1933) with the help of certain measurement setups. RPI-based restrictions, including those of Landau and Peierls as a special case, hold for any measuring schemes meeting the strict definition of measurement. Their fundamental nature is confirmed by the fact that their associated field detectability condition has the form of the energy-time uncertainty relation. The weaker restrictions suggested by Bohr and Rosenfeld rely on an extended definition of measurement. The energy-time uncertainty relation, which is the condition for the electromagnetic field to be detectable, is applied to the analysis of how the near-field scanning microscope works. (methodological notes)

Yoshio Nishina father of modern physics in Japan

CERN Document Server

Kim, Dong-Won

2007-01-01

Yoshio Nishina not only made a great contribution to the emergence of a research network that produced two Nobel prize winners, but he also raised the overall level of physics in Japan. Focusing on his roles as researcher, teacher, and statesman of science, Yoshio Nishina: Father of Modern Physics in Japan analyzes Nishina''s position in and his contributions to the Japanese physics community.After a concise biographical introduction, the book examines Nishina''s family, his early studies, the creation of RIKEN, and the greater Japanese physics community in the early twentieth century. It then focuses on Nishina''s work at the Cavendish Laboratory and at the University of Göttingen as well as his more fruitful research at Niels Bohr''s Institute of Theoretical Physics in Copenhagen. The book also describes the establishment of the Nishina Laboratory at RIKEN, the collaboration between its experimentalists and theoreticians, and the cosmic ray research of its scientists. The last two chapters discuss Nishina'...

Resonance structure in the fission of ( sup 235 U+n)

Energy Technology Data Exchange (ETDEWEB)

Moore, M.S. (Los Alamos National Lab. (LANL), NM (USA). Physics Div.); Leal, L.C.; De Saussure, G.; Perez, R.B.; Larson, N.M. (Oak Ridge National Lab., TN (USA))

1989-10-09

A new multilevel reduced R-matrix analysis of the neutron-induced resonance cross sections of {sup 235}U has been carried out. We used as a constraint in the analysis the angular anisotropy measurements of Pattenden and Postma, obtaining a Bohr-channel (or J, K channel) representation of the resonances in a two-fission vector space for each spin state. Hambsch et al., have reported definitive measurements of the mass- and kinetic-energy distributions of fission fragments of ({sup 235}U+n) in the resonance region and analyzed their results according to the fission-channel representation of Brosa et al., extracting relative contributions of the two asymmetric and one symmetric Brosa fission channels. We have explored the connection between Bohr-channel and asymmetric Brosa-channel representations. The results suggest that a simple rotation of coordinates in channel space may be the only transformation required; the multilevel fit to the total and partial cross sections is invariant to such a transformation. (orig.).

Nuclear magnetic ordering in silver

International Nuclear Information System (INIS)

Lefmann, K.

1995-12-01

Nuclear antiferromagnetic ordering has been observed by neutron diffraction in a single crystal of 109 Ag. The critical temperature is found to 700 pK, and the critical field is 100 μT. From the paramagnetic phase a second order phase transition leads into a type-I 1-k structure with long range order. The experiments have taken place at the Hahn-Meitner Institut in Berlin in collaboration with the low Temperature Laboratory in Helsinki, the Niels Bohr Institute in Copenhagen, and Risoe National Laboratory, Roskilde. The present report is a Ph.D. thesis which has been successfully defended at the Niels Bohr Institute. Besides the results of the nuclear ordering experiments the thesis contains a description of the theoretical background for nuclear magnetism and a review of earlier nuclear ordering experiments as well as theoretical work. The principles for studying polarized nuclei with use of polarized and unpolarized neutrons are presented, as well as the results of such experiments. (au) 11 tabs., 59 ills., 143 refs

Trying to explain Copenhagen

CERN Document Server

2003-01-01

The documentary "The Copenhagen Fallout" recounts the friendship and "falling out" of Niels Bohr and Werner Heisenberg, two of the greatest contemporary physicists - friends whom war turned into enemies. It will be shown at CERN on 1st December. During a lecture in Germany towards the end of 1922, a 20-year-old physicist dared to interrupt Physics Nobel-Prize winner Niels Bohr with the words "There is a mathematical error in what you have said." The young scientist in question was none other than Werner Heisenberg. From this audacious beginning a fruitful collaboration and great friendship grew. But World War II threw up a wall of incomprehension between the two scientists, as one worked for the Nazi regime and the other opened his Copenhagen institute to German Jewish scientists. Then came their famous meeting in September 1941, dramatised by the no less famous play "Copenhagen", currently being performed in association with CERN at th...

Particle penetration and radiation effects

CERN Document Server

Sigmund, Peter

This book, which has evolved from the author’s lectures at the University of Copenhagen and the University of Southern Denmark, draws on his experience as an active researcher in the interaction of charged particles with matter over more than forty years. The emphasis is on the theoretical description of fundamental phenomena, and much attention has been given to classic topics such as: Rutherford scattering; the theory of particle stopping as developed by Bohr, Bethe, Bloch and Lindhard; the statistical description of energy loss as developed by Bohr, Bothe, Williams and Landau; and numerous more recent developments. An attempt has been made to provide at least one complete derivation of a theoretical description for all central aspects. The presentation is intended to respect the ideas of the original authors, but much effort has been invested in establishing a unified and appealing notation consistent with present-day standards. It is intended that this volume will satisfy a long-standing need for a text...

(4)He Thermophysical Properties: New Ab Initio Calculations.

Science.gov (United States)

Hurly, John J; Mehl, James B

2007-01-01

Since 2000, atomic physicists have reduced the uncertainty of the helium-helium "ab initio" potential; for example, from approximately 0.6 % to 0.1 % at 4 bohr, and from 0.8 % to 0.1 % at 5.6 bohr. These results led us to: (1) construct a new inter-atomic potential ϕ 07, (2) recalculate values of the second virial coefficient, the viscosity, and the thermal conductivity of (4)He from 1 K to 10,000 K, and (3), analyze the uncertainties of the thermophysical properties that propagate from the uncertainty of ϕ 07 and from the Born-Oppenheimer approximation of the electron-nucleon quantum mechanical system. We correct minor errors in a previous publication [J. J. Hurly and M. R. Moldover, J. Res. Nat. Inst. Standards Technol. 105, 667 (2000)] and compare our results with selected data published after 2000. The ab initio results tabulated here can serve as standards for the measurement of thermophysical properties.

4He Thermophysical Properties: New Ab Initio Calculations

Science.gov (United States)

Hurly, John J.; Mehl, James B.

2007-01-01

Since 2000, atomic physicists have reduced the uncertainty of the helium-helium “ab initio” potential; for example, from approximately 0.6 % to 0.1 % at 4 bohr, and from 0.8 % to 0.1 % at 5.6 bohr. These results led us to: (1) construct a new inter-atomic potential ϕ07, (2) recalculate values of the second virial coefficient, the viscosity, and the thermal conductivity of 4He from 1 K to 10,000 K, and (3), analyze the uncertainties of the thermophysical properties that propagate from the uncertainty of ϕ07 and from the Born-Oppenheimer approximation of the electron-nucleon quantum mechanical system. We correct minor errors in a previous publication [J. J. Hurly and M. R. Moldover, J. Res. Nat. Inst. Standards Technol. 105, 667 (2000)] and compare our results with selected data published after 2000. The ab initio results tabulated here can serve as standards for the measurement of thermophysical properties. PMID:27110456

Bell's theorem and quantum realism. Reassessment in light of the Schroedinger paradox

International Nuclear Information System (INIS)

Shakur, Asif M.; Hemmick, Douglas L.

2012-01-01

Quantum theory presents a strange picture of the world, offering no real account of physical properties apart from observation. Neils Bohr felt that this reflected a core truth of nature: ''There is no quantum world. There is only an abstract mathematical description.'' Among the most significant developments since Bohr's day has been the theorem of John S. Bell. It is important to consider whether Bell's analysis supports such a denial of microrealism. In this book, we evaluate the situation in terms of an early work of Erwin Schroedinger. Doing so, we see how Bell's theorem is conceptually related to the Conway and Kochen Free Will theorem and also to all the major anti-realism efforts. It is easy to show that none of these analyses imply the impossibility of objective realism. We find that Schroedinger's work leads to the derivation of a new series of theoretical proofs and potential experiments, each involving ''entanglement,'' the link between particles in some quantum systems. (orig.)

Nuclei far from stability. Individual and collective excitations at low energy

International Nuclear Information System (INIS)

Meyer, M.

1984-01-01

The low energy structure of exotic nuclei is discussed in terms of self-consistent microscopic models. The experimental striking features of the spectroscopy of these nuclei are briefly surveyed and the schematic steps performed to obtain from effective N-N interactions their spectroscopic properties are presented. Their saturation and deformation properties are given by the Hartree-Fock approximation (HF). Then it is shown how to describe the dynamics of even-even exotic nuclei excited states by solving the complete Bohr Hamiltonian, built microscopically using the HF approximation and the adiabatic limit (and its derivatives) of the time-dependent HF approximation (ATDHF). The structure of odd and doubly odd nuclei is discussed in the framework of the unified model, ie the microscopic rotor + quasiparticles model. Finally possible future directions of experimental research concerning exotic nuclei are described and improvements or new theoretical approaches discussed [fr

The problem of deriving the field-induced thermal emission in Poole-Frenkel theories

Science.gov (United States)

Ongaro, R.; Pillonnet, A.

1992-10-01

A discussion is made of the legitimity of implementing the usual model of field-assisted release of electrons, over the lowered potential barrier of donors. It is stressed that no reliable interpretation can avail for the usual modelling of wells, on which Poole-Frenkel (PF) derivations are established. This is so because there does not seem to exist reliable ways of implanting a Coulomb potential well in the gap of a material. In an attempt to bridge the gap between the classical potential-energy approaches and the total-energy approach of Mahapatra and Roy, a Bohr-type model of wells is proposed. In addition, a brief review of quantum treatments of electronic transport in materials is presented, in order to see if more reliable ways of approaching PF effect can be derived on undisputable bases. Finally, it is concluded that, presently, PF effect can be established safely neither theoretically nor experimentally.

Strongly coupled semiclassical plasma: interaction model and some properties

International Nuclear Information System (INIS)

Baimbetov, N.F.; Bekenov, N.A.

1999-01-01

In the report a fully ionized strongly coupled hydrogen plasma is considered. The density number is considered within range n=n e =n i ≅(10 21 -2·10 25 )sm -3 , and the temperature domian is T≅(5·10 4 -10 6 ) K. The coupling parameter Γ is defined by Γ=e 2 /αk B T, where k B is the Boltzmann constant and e is electrical charge, α=(3/4πn) 1/3 is the average distance between the particles (Wigner-Seitz radius). The dimensionless density parameter r s =α/α B is given in terms of the Bohr radius α B =ℎ 2 /me 2 ∼0.529·10 - 8 sm. The degeneracy parameter for the electron was defined by the ratio between the thermal energy k B T and the Fermi energy E F :Θ=k B T/E F ∼0.54·r s /Γ. The intermediate temperature-density region, where Γ≥1; Θ≅1; T>13.6 eV is examined. A semiclassical effective potential which account for the short-range, quantum diffraction and symmetry effects of charge carriers screening

Physics in the twentieth century. A selection of papers

International Nuclear Information System (INIS)

Weisskopf, V.F.

1974-01-01

A number of papers from Victor F. Weisskopf have been collected in this book. The papers included in the first part are dealing with basic concepts in quantum mechanics. Particle-wave duality, quantum scale, and the Niels Bohr works. Papers in the second part describe the recent developments in the physics field during the 20th century: the electron theory, compound nucleus, nuclear structure, and quantum theory of elementary particles. The third part is concerned with peculiar cases: nuclear models, the Lorentz relativistic contraction, light-matter interaction, parity decay, and symmetry. In the fourth part are gathered papers on sciences in general, for which they present a sort of natural philosophy [fr

The Golden ratio, ionic and atomic radii and bond lengths

Czech Academy of Sciences Publication Activity Database

Heyrovská, Rajalakshmi

2005-01-01

Roč. 103, 6-8 (2005), s. 877-882 ISSN 0026-8976 R&D Projects: GA MPO(CZ) 1H-PK/42 Institutional research plan: CEZ:AV0Z40400503 Keywords : Bohr radius * bond lengths * axial ratios Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.351, year: 2005

Cern collisions light up Copenhagen

CERN Multimedia

Banks, Michael

2010-01-01

"Anyone passing by the Niels Bohr Institute in Copenhagen, Denmark, might be startled by some strange moving lights on the facade of the institute's main building. In fact, the dancing beams show, almost in real time, collisions form the Atlas experiment at Cern's Large Hadron Collider (LHC)" (1 paragraph)

Inelastic two composite particle systems scattering at high energy

International Nuclear Information System (INIS)

Zhang Yushun.

1986-11-01

In this paper, by using the collective coordinate of Bohr and phenomenological deformed optical potentials, the scattering amplitudes of two composite particle systems can be obtained and the collective excitation for two composite particle systems in the scattering process is discussed. (author). 10 refs, 6 figs, 2 tabs

Hemoglobin function and allosteric regulation in semi-fossorial rodents (family Sciuridae) with different altitudinal ranges

Science.gov (United States)

Revsbech, Inge G.; Tufts, Danielle M.; Projecto-Garcia, Joana; Moriyama, Hideaki; Weber, Roy E.; Storz, Jay F.; Fago, Angela

2013-01-01

SUMMARY Semi-fossorial ground squirrels face challenges to respiratory gas transport associated with the chronic hypoxia and hypercapnia of underground burrows, and such challenges are compounded in species that are native to high altitude. During hibernation, such species must also contend with vicissitudes of blood gas concentrations and plasma pH caused by episodic breathing. Here, we report an analysis of hemoglobin (Hb) function in six species of marmotine ground squirrels with different altitudinal distributions. Regardless of their native altitude, all species have high Hb–O2 affinities, mainly due to suppressed sensitivities to allosteric effectors [2,3-diphosphoglycerate (DPG) and chloride ions]. This suppressed anion sensitivity is surprising given that all canonical anion-binding sites are conserved. Two sciurid species, the golden-mantled and thirteen-lined ground squirrel, have Hb–O2 affinities that are characterized by high pH sensitivity and low thermal sensitivity relative to the Hbs of humans and other mammals. The pronounced Bohr effect is surprising in light of highly unusual amino acid substitutions at the C-termini that are known to abolish the Bohr effect in human HbA. Taken together, the high O2 affinity of sciurid Hbs suggests an enhanced capacity for pulmonary O2 loading under hypoxic and hypercapnic conditions, while the large Bohr effect should help to ensure efficient O2 unloading in tissue capillaries. In spite of the relatively low thermal sensitivities of the sciurid Hbs, our results indicate that the effect of hypothermia on Hb oxygenation is the main factor contributing to the increased blood–O2 affinity in hibernating ground squirrels. PMID:24172889

Cross sections of electron loss and capture for beams of O+ in water vapor from the energy range of 0,2 to 1,2 MeV

International Nuclear Information System (INIS)

Oliveira, Vitor Jesus de

2015-01-01

The study of the interactions between atoms and molecules is important for the knowledge of the cross sections of the processes that contribute to the deposition of energy by charged particle beams used in radiotherapy planning and transport particle simulation codes. Heavy ions, such as oxygen, induce many cellular and molecular damages in human cells.as a result of interaction between the projectile and atoms and molecules. The use of proton and carbon as the projectile interacting with water molecules is well characterized, however there are few studies with oxygen ions. In this work we are interested in the study of electron loss (projectile ionization) and electron capture with charge state 1+. The Pelletron accelerator of 1.7 MeV from the Federal University of Rio de Janeiro housed in the Atomic and Molecular collisions Laboratory (LACAM) has been used, which can accelerate atomic and molecular ions up to speeds of the order of hundredths of light speed, and consists of the source of negative ions, the Wien filter, the accelerator itself and the magnet load selector. The detection device used to evaluate the processes of interaction (capture and loss) between the beam of the O + and the water molecule is a Microchannel Plate (MCP) at the position sensitive anode. The collisions of O + beans are being studied in the range of 0.2 to 1.2 MeV with water vapor (Z = 10). Were obtained the respective absolute cross sections for electron loss and electron capture and compared with the cross sections of the molecule methane (CH4 → Z = 10), the isoelectronic water molecule. The experimental results show an agreement between the measurements with water and methane. Comparisons were made with results of theoretical models for electron loss using the 'Free Collision Model' and for capture the Bohr and Lindhard model. The theoretical results for electron loss show an agreement of experimental data with the model used. The model of Bohr and Lindhard describes

Cross sections of electron loss and capture for beams of O{sup +} in water vapor from the energy range of 0,2 to 1,2 MeV; Secoes de choque de perda e captura eletronica para feixes de O{sup +} em vapor de agua em uma faixa de energia entre 0,2 e 1,2 MeV

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Vitor Jesus de

2015-06-01

The study of the interactions between atoms and molecules is important for the knowledge of the cross sections of the processes that contribute to the deposition of energy by charged particle beams used in radiotherapy planning and transport particle simulation codes. Heavy ions, such as oxygen, induce many cellular and molecular damages in human cells.as a result of interaction between the projectile and atoms and molecules. The use of proton and carbon as the projectile interacting with water molecules is well characterized, however there are few studies with oxygen ions. In this work we are interested in the study of electron loss (projectile ionization) and electron capture with charge state 1+. The Pelletron accelerator of 1.7 MeV from the Federal University of Rio de Janeiro housed in the Atomic and Molecular collisions Laboratory (LACAM) has been used, which can accelerate atomic and molecular ions up to speeds of the order of hundredths of light speed, and consists of the source of negative ions, the Wien filter, the accelerator itself and the magnet load selector. The detection device used to evaluate the processes of interaction (capture and loss) between the beam of the O{sup +} and the water molecule is a Microchannel Plate (MCP) at the position sensitive anode. The collisions of O{sup +} beans are being studied in the range of 0.2 to 1.2 MeV with water vapor (Z = 10). Were obtained the respective absolute cross sections for electron loss and electron capture and compared with the cross sections of the molecule methane (CH4 → Z = 10), the isoelectronic water molecule. The experimental results show an agreement between the measurements with water and methane. Comparisons were made with results of theoretical models for electron loss using the 'Free Collision Model' and for capture the Bohr and Lindhard model. The theoretical results for electron loss show an agreement of experimental data with the model used. The model of Bohr and Lindhard

Valter Ritz as a theoretical physicist and his research on atomic spectra theory

International Nuclear Information System (INIS)

El'yashevich, M.A.; Kemberovskaya, N.G.; Tomil'chik, L.M.

1995-01-01

The article presents a historic-methodological analysis of the scientific heritage of an outstanding Swiss physicist Walter Ritz (1878-1909); the analysis is based on the study of a complete collection of his works published in 1911. In addition to a general description of Ritz's works which comprise publications in spectroscopy, variational method and electrodynamics, the article deals in detail with this fundamental research into atomic spectra theory. Elastic and magnetic model of the atom proposed by Ritz for explaining atomic spectra within the framework of the classical approach are discussed. It is shown that the generalized formulas of Balmer and Rydbery, as well as the combination principle which served later as a basis for formalting Bohr's condition of frequencies, were derived by Ritz as regions corollaries of this models and were out of semiempiric nature, as was assumed. 124 refs

Quantum principles and particles

CERN Document Server

Wilcox, Walter

2012-01-01

QUANTUM PRINCIPLESPerspective and PrinciplesPrelude to Quantum MechanicsStern-Gerlach Experiment Idealized Stern-Gerlach ResultsClassical Model AttemptsWave Functions for Two Physical-Outcome CaseProcess Diagrams, Operators, and Completeness Further Properties of Operators/ModulationOperator ReformulationOperator RotationBra-Ket Notation/Basis StatesTransition AmplitudesThree-Magnet Setup Example-CoherenceHermitian ConjugationUnitary OperatorsA Very Special OperatorMatrix RepresentationsMatrix Wave Function RecoveryExpectation ValuesWrap Up ProblemsFree Particles in One DimensionPhotoelectric EffectCompton EffectUncertainty Relation for PhotonsStability of Ground StatesBohr ModelFourier Transform and Uncertainty RelationsSchrödinger EquationSchrödinger Equation ExampleDirac Delta FunctionsWave Functions and ProbabilityProbability CurrentTime Separable SolutionsCompleteness for Particle StatesParticle Operator PropertiesOperator RulesTime Evolution and Expectation ValuesWrap-UpProblemsSome One-Dimensional So...

The Colloquium

Science.gov (United States)

Amoroso, Richard L.

HÉCTOR A.A brief introductory survey of Unified Field Mechanics (UFM) is given from the perspective of a Holographic Anthropic Multiverse cosmology in 12 `continuous-state' dimensions. The paradigm with many new parameters is cast in a scale-invariant conformal covariant Dirac polarized vacuum utilizing extended HD forms of the de Broglie-Bohm and Cramer interpretations of quantum theory. The model utilizes a unique form of M-Theory based in part on the original hadronic form of string theory that had a variable string tension, TS and included a tachyon. The model is experimentally testable, thus putatively able to demonstrate the existence of large-scale additional dimensionality (LSXD), test for QED violating tight-bound state spectral lines in hydrogen `below' the lowest Bohr orbit, and surmount the quantum uncertainty principle utilizing a hyperincursive Sagnac Effect resonance hierarchy.

Effects of adiabatic, relativistic, and quantum electrodynamics interactions on the pair potential and thermophysical properties of helium.

Science.gov (United States)

Cencek, Wojciech; Przybytek, Michał; Komasa, Jacek; Mehl, James B; Jeziorski, Bogumił; Szalewicz, Krzysztof

2012-06-14

The adiabatic, relativistic, and quantum electrodynamics (QED) contributions to the pair potential of helium were computed, fitted separately, and applied, together with the nonrelativistic Born-Oppenheimer (BO) potential, in calculations of thermophysical properties of helium and of the properties of the helium dimer. An analysis of the convergence patterns of the calculations with increasing basis set sizes allowed us to estimate the uncertainties of the total interaction energy to be below 50 ppm for interatomic separations R smaller than 4 bohrs and for the distance R = 5.6 bohrs. For other separations, the relative uncertainties are up to an order of magnitude larger (and obviously still larger near R = 4.8 bohrs where the potential crosses zero) and are dominated by the uncertainties of the nonrelativistic BO component. These estimates also include the contributions from the neglected relativistic and QED terms proportional to the fourth and higher powers of the fine-structure constant α. To obtain such high accuracy, it was necessary to employ explicitly correlated Gaussian expansions containing up to 2400 terms for smaller R (all R in the case of a QED component) and optimized orbital bases up to the cardinal number X = 7 for larger R. Near-exact asymptotic constants were used to describe the large-R behavior of all components. The fitted potential, exhibiting the minimum of -10.996 ± 0.004 K at R = 5.608 0 ± 0.000 1 bohr, was used to determine properties of the very weakly bound (4)He(2) dimer and thermophysical properties of gaseous helium. It is shown that the Casimir-Polder retardation effect, increasing the dimer size by about 2 Å relative to the nonrelativistic BO value, is almost completely accounted for by the inclusion of the Breit-interaction and the Araki-Sucher contributions to the potential, of the order α(2) and α(3), respectively. The remaining retardation effect, of the order of α(4) and higher, is practically negligible for the bound

Measurability of non-abelium gauge fields

Energy Technology Data Exchange (ETDEWEB)

Ivanenko, D.D.; Obukhov, Yu.N.

New estimations of the accuracy of measurement of non-abeliar gauge field components are obtained on the base of qualitative analysis of the test body equations of motion. They generalize the Bohr and Rosenfeld results on the measurability of an electomagnetic field for the case of an arbitrary gauge group.

Fulltext PDF

Indian Academy of Sciences (India)

level as much as graduate and postgraduate students to have a correct grasp of this process at their initial stages of learning. locate the Electrons. By Bohr's laws, an electron around a nucleus is restricted from occupying any arbitrary state of energy (energy level) and hence only predetermined discrete energy levels.

New look at the nuclear force

International Nuclear Information System (INIS)

Noyes, P.

1975-07-01

Nuclear force theory and calculations are discussed. It is noted that whether the quark interpretation or the vague bootstrap ideas indicated turn out to be better approximations, it is hoped that the deuteron problem is on the verge of being turned into the Bohr atom of strong interaction physics. 2 references

Kvantemekanik

DEFF Research Database (Denmark)

Mølmer, Klaus

enorm succes, men fortolkningen af den splittede samtidig tidens største videnskabsmænd, særligt Niels Bohr og Albert Einstein. Denne bog gennemgår kvantemekanikkens og fysikkens udvikling i det 20. århundrede - og giver indblik i de nyeste opdagelser af, hvordan den atomare verden fungerer...

Spontaneous Magnetization in the Dipolar Ising Ferromagnet LiTbF4

DEFF Research Database (Denmark)

Als-Nielsen, Jens Aage; Holmes, L. M.; Krebs Larsen, F.

1975-01-01

The spontaneous magnetization μ in Bohr magnetons below TC=2.874 K in LiTbF4 has been measured by magnetic Bragg scattering of neutrons. The data were normalized by comparing the magnetic Bragg scattering to the nuclear Bragg scattering at T>TC. The nuclear structure factors as well...

Hybrid Quantum Mechanical-Quasi-Classical Model for Evaluating Ionization and Stripping Cross Sections in Atom-Ion Collisions

CERN Document Server

Kaganovich, I D; Startsev, E

2005-01-01

Ion-atom ionization cross sections are needed in many applications employing the propagation of fast ions through matter. When experimental data or full-scale theoretical calculations are non-existent, approximate methods must be used. The most robust and easy-to-use approximations include the Born approximation of quantum mechanics and the quasi-classical approach utilizing classical mechanics together with the Bohr-Sommerfeld quantization rule.* The simplest method to extend the validity of both approaches is to combine them, i.e., use the two different approaches but only for the regions of impact parameters in which they are valid, and sum the results to obtain the total cross section. We have recently investigated theoretically and experimentally the stripping of more than 18 different pairs of projectile and target atoms in the range of 3-38 MeV/amu to study the range of validity of various approximations. The results of the modified approach agree better with the experimental data than either the Born ...

Ionization of highly charged iodine ions near the Bohr velocity

International Nuclear Information System (INIS)

Zhou, Xianming; Cheng, Rui; Lei, Yu; Sun, Yuanbo; Ren, Jieru; Liu, Shidong; Deng, Jiachuan; Zhao, Yongtao; Xiao, Guoqing

2015-01-01

We have measured the L-shell X-rays of iodine from the collisions of 3 MeV I q+(q=15,20,22,25,26) ions with an iron target. It is found that the X-ray yield decreases with the increasing initial charge state. The energy of the subshell X-ray has a blue shift, which is independent of the projectile charge state. In addition, the relative intensity ratios of Lβ 1,3,4 and Lβ 2,15 to Lα 1,2 X-ray are obtained and compared with the theoretical calculations. That they are larger than for a singly ionized atom can be understood by the multiple ionization effect of the outer-shell electrons

Anomalies and the crisis of the Bohr-Sommerfeld atomic theory

DEFF Research Database (Denmark)

Kragh, Helge

2014-01-01

In: Scientific Cosmopolitanism and Local Cultures: Religions, Ideologies, Societies (5th ESHS Conference Proceedings, 2014), pp. 652-657.......In: Scientific Cosmopolitanism and Local Cultures: Religions, Ideologies, Societies (5th ESHS Conference Proceedings, 2014), pp. 652-657....

Quantum cosmology. 18

International Nuclear Information System (INIS)

Padmanabhan, T.

1989-01-01

Quantum cosmology is to quantum gravity what the Bohr model is to the full quantum mechanical description of the hydrogen atom. In quantum cosmology one attempts to give a quantum-mechanical meaning to classical solutions of general relativity. This is discussed in this chapter. The approach is illustrated by quantizing only the conformal degree of freedom of the gravitational field, in particular the Friedmann-Robertson-Walker models. And, as in the hydrogen atom, the classical singularity of general relativity is avoided and one has analogous stationary states in the quantum Universe. The chapter ends with a model of the fundamental role that the Planck length may play as the universal cutoff in all field theories, thus ridding the theory of ultra-violet divergences. Two appendices introduce field theory in the Schroedinger representation and the Schroedinger equation for quantum gravity, namely the Wheeler-De Wit equation. (author). 38 refs.; 2 figs.; 1 tab

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Indian Academy of Sciences (India)

IAS Admin

Bohr's life and work is covered in this issue in an article by N. Mukunda, who dwells on all aspects of his life – family, his stay in. England and the crucial contact with Rutherford, old quantum ... Many-Worlds Interpretation of Quantum Mechanics, Princeton. Series in Physics, Princeton University Press, 1973). Another as-.

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Indian Academy of Sciences (India)

1932, he attended the opening address by Niels Bohr at the 'International Congress on Light Therapy' on the topic ... understanding of the molecular processes taking place in the cell in term of atomic physics, might be ... Delbriick recalls in a few well-chosen words the paradoxes that gave rise to the quantum mechanical.

Epistemology and Probability

CERN Document Server

Plotnitsky, Arkady

2010-01-01

Offers an exploration of the relationships between epistemology and probability in the work of Niels Bohr, Werner Heisenberg, and Erwin Schrodinger; in quantum mechanics; and in modern physics. This book considers the implications of these relationships and of quantum theory for our understanding of the nature of thinking and knowledge in general

Synthesis and Characterization of Quantum Dots: A Case Study Using PbS

Science.gov (United States)

Pan, Yi; Li, Yue Ru; Zhao, Yu; Akins, Daniel L.

2015-01-01

A research project for senior undergraduates of chemistry has been developed to introduce syntheses of a series of monodispersed semiconductor PbS quantum dots (QDs) and their characterization methodologies. In this paper, we report the preparation of monodispersed semiconductor PbS QDs with sizes smaller than the exciton Bohr radius using a…

Speakable in quantum mechanics

NARCIS (Netherlands)

Hermens, Ronnie

2013-01-01

At the 1927 Como conference Bohr spoke the famous words "It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature." However, if the Copenhagen interpretation really adheres to this motto, why then is there this nagging feeling of

Determination of neutron-induced fission cross-sections of unstable ...

Indian Academy of Sciences (India)

2014-11-04

Nov 4, 2014 ... powerful tool for a wide range of applications that involve compound nuclear reactions. In Bohr's hypothesis, formation and decay of a compound nucleus are considered to be independent of each other. This independence is exploited in the surrogate reaction. Pramana – J. Phys., Vol. 83, No. 5, November ...

An Introduction to Chemistry for Merchant Marine Oriented Individuals (Ch-1 and Ch-1C). A Study Guide to Minicourse D-1, Elementary Background.

Science.gov (United States)

Schlenker, Richard M.; Dillon, Timothy

This document contains lab activities, problem sets, and a tape script to be accompanied by a slide show. The minicourse covers the following topics of general chemistry: kinetic-molecular theory, the Bohr atom, acids, bases, and salts, the periodic table, bonding, chemical equations, the metric system, computation of density, mass, and volume,…

Whole blood-oxygen binding properties of four cold-temperate marine fishes: blood affinity is independent of pH-dependent binding, routine swimming performance, and environmental hypoxia

DEFF Research Database (Denmark)

Herbert, Neill A; Skov, Peter V; Wells, Rufus M G

2006-01-01

performance and the predicted low O(2) response of each species. The ecotype of the four marine species was also unrelated to pH-dependent binding because no difference in the Bohr effect was apparent ( Phi varied insignificantly from -0.90 to -1.06), and differences in the magnitude of the cooperative...

Direct interaction in nuclear reactions: a theory

International Nuclear Information System (INIS)

Dominicis, C.T. de

1959-01-01

General treatment of the foundations of direct interaction in nuclear reactions; representation of the instantaneous elastic scattering amplitude by the scattering amplitude due to a complex potential; expansion of the instantaneous inelastic scattering amplitude and discussion of the 1. Bohr approximation (distorted waves) contribution to individual and collective states of excitation. (author) [fr

Der Quantensprung ist keine Hexerei die neue Physik für Einsteiger

CERN Document Server

Wolf, Fred Alan

1986-01-01

Eine faszinierende Reise von den Grundbegriffen der Physik bis zu den Grenzen der Naturwissenschaft und den menschlichen Vorstellungsvermögens. Dieses Buch verfolgt die Geschichte der Physik von den Beobachtungen der alten Griechen über die Entdeckungen Galileis und Newtons bis zu den erstaunlichen Theorien von Denkern wie Planck, Einstein, Bohr und Born.

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Indian Academy of Sciences (India)

the electrons have to be situated somewhere between the two orbits (i.e. between energy levels 1 and 2) at some point of time. But again, by Bohr's laws, they are forbidden from occupying any intermediate positions. Wherein does the anomaly lie? Question by: Anirban Sadhu. Department of Microbiology. Y M College.

Nuclides and isotopes. Twelfth edition

International Nuclear Information System (INIS)

Anon.

1977-01-01

This explanatory booklet was designed to be used with the Chart of the Nuclides. It contains a brief history of the atomic theory of matter: ancient speculations, periodic properties of elements (Mendeleev table), radioactivity, early models of atomic structure, the Bohr atom, quantum numbers, nature of isotopes, artificial radioactivity, and neutron fission. Information on the pre-Fermi (natural) nuclear reactor at Oklo and the search for superheavy elements is given. The booklet also discusses information presented on the Chart and its coding: stable nuclides, metastable states, data display and color, isotopic abundances, neutron cross sections, spins and parities, fission yields, half-life variability, radioisotope power and production data, radioactive decay chains, and elements without names. The Periodic Table of the Elements is appended. 3 figures, 3 tables

Systematic measurements of transient fields for W, Os and Pt ions traversing Fe

International Nuclear Information System (INIS)

Stuchbery, A.E.; Heseltine, T.H.; Anderssen, S.S.; Bolotin, H.H.; Byrne, A.P.; Fabricius, B.; Kibedi, T.

1994-01-01

Transient magnetic fields were measured for W, Os and Pt ions traversing iron hosts with average velocities in the range from approximately 1.6 v 0 to 4.8 v 0 (v 0 = c/137, Bohr velocity). Transient fields for W and Os in Fe are consistent with behaviour found for lighter rare-earth ions and are about 20% stronger than those for Pt in Fe over the majority of the velocity range examined. A measurement was made to confirm that possible heavy-ion beam induced attenuations of the transient field are negligible for low-velocity Pt ions excited by Ni beams. Results are discussed in terms of both empirical and model-based parameterizations of the transient field strength. (orig.)

Contribution to the study of the influences of the excitation energy on the characteristics of the fission process

International Nuclear Information System (INIS)

Wagemans, C.

1979-01-01

Neutron induced and spontaneous fission with neutron energies from 10 -2 to 2.10 5 eV have been studied. Thermal neutron induced fission measurements in Pa 231 , Th 232 , Np 237 , U 233 , U 235 , Pu 239 and Pu 241 are reported. Energy and mass distributions of heavy fission fragments due to the spontaneous fission of Pu 240 are compared to the results obtained by thermal neutron fission of Pu 239 ; the events observed with U 236 , Pu 240 , Pa 232 and Np 238 are explained by the Bohr theory of fission channels. Ternary fission phenomena of U 233 , U 235 , Pu 239 , Pa 231 and Np 237 induced by thermal neutrons are explained and compared to models of Carjan and Feather. (MDC)

Multiple Evolutionary Events Involved in Maintaining Homologs of Resistance to Powdery Mildew 8 in Brassica napus.

Science.gov (United States)

Li, Qin; Li, Jing; Sun, Jin-Long; Ma, Xian-Feng; Wang, Ting-Ting; Berkey, Robert; Yang, Hui; Niu, Ying-Ze; Fan, Jing; Li, Yan; Xiao, Shunyuan; Wang, Wen-Ming

2016-01-01

The Resistance to Powdery Mildew 8 (RPW8) locus confers broad-spectrum resistance to powdery mildew in Arabidopsis thaliana. There are four Homologous to RPW8s (BrHRs) in Brassica rapa and three in Brassica oleracea (BoHRs). Brassica napus (Bn) is derived from diploidization of a hybrid between B. rapa and B. oleracea, thus should have seven homologs of RPW8 (BnHRs). It is unclear whether these genes are still maintained or lost in B. napus after diploidization and how they might have been evolved. Here, we reported the identification and sequence polymorphisms of BnHRs from a set of B. napus accessions. Our data indicated that while the BoHR copy from B. oleracea is highly conserved, the BrHR copy from B. rapa is relatively variable in the B. napus genome owing to multiple evolutionary events, such as gene loss, point mutation, insertion, deletion, and intragenic recombination. Given the overall high sequence homology of BnHR genes, it is not surprising that both intragenic recombination between two orthologs and two paralogs were detected in B. napus, which may explain the loss of BoHR genes in some B. napus accessions. When ectopically expressed in Arabidopsis, a C-terminally truncated version of BnHRa and BnHRb, as well as the full length BnHRd fused with YFP at their C-termini could trigger cell death in the absence of pathogens and enhanced resistance to powdery mildew disease. Moreover, subcellular localization analysis showed that both BnHRa-YFP and BnHRb-YFP were mainly localized to the extra-haustorial membrane encasing the haustorium of powdery mildew. Taken together, our data suggest that the duplicated BnHR genes might have been subjected to differential selection and at least some may play a role in defense and could serve as resistance resource in engineering disease-resistant plants.

RE-SONAN--CEIFeb-ru-aN

Indian Academy of Sciences (India)

discovery of energy quanta"; 1921 - to Albert Einstein "for services to theoretical physics, and especially for his discovery of the law of the photoelectric effect"; 1922 - to Niels Bohr" for his investigations of the structure of atoms, and ofthe radiation emanating from them"; 1929 - to Louis Victor de Broglie "for his discovery of the ...

Quantum information and information loss in general relativity

NARCIS (Netherlands)

Hooft, G. 't

1996-01-01

When it comes to performing thought experiments with black holes, Einstein-Bohr like discussions have to be re-opened. For instance one can ask what happens to the quantum state of a black hole when the wave function of a single ingoing particle is replaced by an other one that is orthogonal to the

Quantum-Classical Connection for Hydrogen Atom-Like Systems

Science.gov (United States)

Syam, Debapriyo; Roy, Arup

2011-01-01

The Bohr-Sommerfeld quantum theory specifies the rules of quantization for circular and elliptical orbits for a one-electron hydrogen atom-like system. This article illustrates how a formula connecting the principal quantum number "n" and the length of the major axis of an elliptical orbit may be arrived at starting from the quantum…

Fulltext PDF

Indian Academy of Sciences (India)

Lise Meitner was the first to rec- ognize that 'uranium atom had been split' in this reaction. The idea germinated when Meitner and Frisch were spending Christmas vacation together in 1938. Discussing about the recent results during a long walk in the snow, considering Bohr's suggestion of nucleus as a liquid drop, they ...

Wave equation of hydrogen atom

International Nuclear Information System (INIS)

Suwito.

1977-01-01

The calculation of the energy levels of the hydrogen atom using Bohr, Schroedinger and Dirac theories is reviewed. The result is compared with that obtained from infinite component wave equations theory which developed recently. The conclusion can be stated that the latter theory is better to describe the composit system than the former. (author)

Increases in arterial blood oxygen during exercise in the lemon shark (Negaprion brevirostris)

DEFF Research Database (Denmark)

BUSHNELL, PG; LUTZ, PL; STEFFENSEN, JF

1982-01-01

Polyethylene cannulae were implanted in pre- and post-branchial blood vessels allowing nonstressful blood sampling over a variety of activity ranges in an active tropical elasmobranch, the lemon shark (Negaprion brevirostris). TheP 50 was found to be 11.8 Torr at 24°C and pH of 7.7. A Bohr shift...

The new dedicated PIXE set-up at the National Environmental Research Institute, Denmark

International Nuclear Information System (INIS)

Kemp, Ka ring re; Waahlin, Peter

1999-01-01

The Niels Bohr Institute in Copenhagen was in the beginning of the 70'es one of the early places for PIXE. Contributions were made to the theoretical interpretation of the PIXE spectra as well as the practical application. The home-made 4 MV van de Graaff accelerator at the Niels Bohr Institute was an excellent tool for PIXE. The accelerator, which was used for many years, has now found its place on a museum after more than 40 years of active service. A dedicated PIXE set-up has now been established at the National Environmental Research Institute using a new 1.7 MV Tandem Pelletron (5SDH) from NEC. The main application is elemental analysis of outdoor aerosols. The main work is unsophisticated macro analyses, which do not push the equipment to its limits. This enables automated analysis of about 10,000 samples per year using very limited manpower resources. The research focuses on the contribution from various source types to the atmosphere over Europe, the North Atlantic and Greenland. Source compositions and their temporal variations are studied

Blood O2 affinity of a large polar elasmobranch, the Greenland shark Somniosus microcephalus

DEFF Research Database (Denmark)

Herbert, N.A.; Skov, Peter Vilhelm; Tirsgaard, B.

2017-01-01

The Greenland shark (Somniosus microcephalus. Bloch & Schneider 1801) is a polar elasmobranch that is hypothesised to possess a unique metabolic physiology due to its extreme large size, the cold waters it inhabits and its slow swimming lifestyle. Our results therefore provide the first insight...... into the metabolic physiology of this unique shark, with a focus on blood O2 affinity. An evaluation of blood O2 affinity at 2 °C using tonometry revealed a P50 of 11.7 mmHg at a PCO2 of 2.25 mmHg and a Bohr effect (binding sensitivity of blood to pH, ϕ = Δlog P50/ΔpH) of −0.26. A comparative evaluation of blood O2...... affinity across elasmobranch fishes suggests that S. microcephalus has a high blood O2 affinity (i.e., low P50) and a small Bohr effect but these are common traits in sluggish elasmobranch fishes, with little evidence for any relationship of blood O2 affinity to the low metabolic rates, low environmental...

Homogeneous Field and WKB Approximation in Deformed Quantum Mechanics with Minimal Length

Directory of Open Access Journals (Sweden)

Jun Tao

2015-01-01

Full Text Available In the framework of the deformed quantum mechanics with a minimal length, we consider the motion of a nonrelativistic particle in a homogeneous external field. We find the integral representation for the physically acceptable wave function in the position representation. Using the method of steepest descent, we obtain the asymptotic expansions of the wave function at large positive and negative arguments. We then employ the leading asymptotic expressions to derive the WKB connection formula, which proceeds from classically forbidden region to classically allowed one through a turning point. By the WKB connection formula, we prove the Bohr-Sommerfeld quantization rule up to Oβ2. We also show that if the slope of the potential at a turning point is too steep, the WKB connection formula is no longer valid around the turning point. The effects of the minimal length on the classical motions are investigated using the Hamilton-Jacobi method. We also use the Bohr-Sommerfeld quantization to study statistical physics in deformed spaces with the minimal length.

A Historical Survey of Sir Karl Popper's Contribution to Quantum Mechanics

Directory of Open Access Journals (Sweden)

William M. Shields

2012-11-01

Full Text Available Sir Karl Popper (1902-1994, though not trained as a physicist and embarrassed early in his career by a physics error pointed out by Einstein and Bohr, ultimately made substantial contributions to the interpretation of quantum mechanics. As was often the case, Popper initially formulated his position by criticizing the views of others - in this case Niels Bohr and Werner Heisenberg. Underlying Popper's criticism was his belief that, first, the Copenhagen interpretation of quantum mechanics abandoned scientific realism and second, the assertion that quantum theory was complete (an assertion rejected by Einstein among others amounted to an unfalsifiable claim. Popper insisted that the most basic predictions of quantum mechanics should continue to be tested, with an eye towards falsification rather than mere adding of decimal places to confirmatory experiments. His persistent attacks on the Copenhagen interpretation were aimed not at the uncertainty principle itself and the formalism from which it was derived, but at the acceptance by physicists of an unclear epistemology and ontology that left critical questions unanswered. Quanta 2012; 1: 1–12.

Reality, Causality, and Probability, from Quantum Mechanics to Quantum Field Theory

Science.gov (United States)

Plotnitsky, Arkady

2015-10-01

These three lectures consider the questions of reality, causality, and probability in quantum theory, from quantum mechanics to quantum field theory. They do so in part by exploring the ideas of the key founding figures of the theory, such N. Bohr, W. Heisenberg, E. Schrödinger, or P. A. M. Dirac. However, while my discussion of these figures aims to be faithful to their thinking and writings, and while these lectures are motivated by my belief in the helpfulness of their thinking for understanding and advancing quantum theory, this project is not driven by loyalty to their ideas. In part for that reason, these lectures also present different and even conflicting ways of thinking in quantum theory, such as that of Bohr or Heisenberg vs. that of Schrödinger. The lectures, most especially the third one, also consider new physical, mathematical, and philosophical complexities brought in by quantum field theory vis-à-vis quantum mechanics. I close by briefly addressing some of the implications of the argument presented here for the current state of fundamental physics.

Energy straggling determination for charged particles in thick targets

International Nuclear Information System (INIS)

Lopez M, J.

1980-01-01

Energy straggling is reported for deuterons in carbon and protons in silicon, and the data obtained is compared with predictions of Bohr and Bethe. The experimental method used is based on a reaction resonance widening, observed at backward angles in the thick targets. The incident energy determines the depth at which the resonant scattering occurs and the energy straggling can be measured from the backscattering spectra. The data obtained for the energy straggling of deuterons are approximately two times bigger than those predicted by Bohr's theory; nevertheless, the values found for the energy straggling of protons in silicon are in agreement with the values predicted by the aforesaid theory. This disagreement was explained by the fact that carbon targets used were amorphous and porous, in contrast with those of cristal silicon, (it is an experimental fact that porous materials are expected to give higher stragglings than non-porous ones). Thus, the method reviewed in this work is valid, but the porosity effects should be taken into account in comparing results among materials with different densities. (author)

Nuclear magnetic ordering in silver

Energy Technology Data Exchange (ETDEWEB)

Lefmann, K

1995-12-01

Nuclear antiferromagnetic ordering has been observed by neutron diffraction in a single crystal of {sup 109}Ag. The critical temperature is found to 700 pK, and the critical field is 100 {mu}T. From the paramagnetic phase a second order phase transition leads into a type-I 1-k structure with long range order. The experiments have taken place at the Hahn-Meitner Institut in Berlin in collaboration with the low Temperature Laboratory in Helsinki, the Niels Bohr Institute in Copenhagen, and Risoe National Laboratory, Roskilde. The present report is a Ph.D. thesis which has been successfully defended at the Niels Bohr Institute. Besides the results of the nuclear ordering experiments the thesis contains a description of the theoretical background for nuclear magnetism and a review of earlier nuclear ordering experiments as well as theoretical work. The principles for studying polarized nuclei with use of polarized and unpolarized neutrons are presented, as well as the results of such experiments. (au) 11 tabs., 59 ills., 143 refs.

Physics comes to the stage

CERN Multimedia

2005-01-01

The Théâtre de Carouge - Atelier de Genève is putting on two plays as part of the World Year of Physics in 2005. Both plays pay tribute to scientists past and future, and the decisive choices they are called upon to make when their discoveries affect the destiny of mankind. "The Physicists" by Friedrich Dürrenmatt until 20 February 2005 How can one control extraordinary and potentially dangerous discoveries? That is the question put by Friedrich Dürrenmatt in this thriller-cum-spy drama. A physicist in a mental asylum is in fact a genius who has realised that his fundamental discoveries can bring about the destruction of the planet and mankind. "Copenhagen" by Michael Frayn on 29 January and on 4, 10, 15 and 16 February 2005 Why did Werner Heisenberg, who was involved in the Third Reich's nuclear research programme, visit his friend and mentor Niels Bohr in occupied Denmark in September 1941? Was it a deliberate attempt to mislead the allies, whose cause Bohr supported? Or was h...

Physics comes to the stage

CERN Multimedia

2005-01-01

The Théâtre de Carouge - Atelier de Genève is putting on two plays as part of the World Year of Physics in 2005. Both plays pay tribute to scientists past and future, and the decisive choices they are called upon to make when their discoveries affect the destiny of mankind. "The Physicists" by Friedrich Dürrenmatt until 20 February 2005 How can one control extraordinary and potentially dangerous discoveries? That is the question put by Friedrich Dürrenmatt in this thriller-cum-spy drama. A physicist in a mental asylum is in fact a genius who has realised that his fundamental discoveries can bring about the destruction of the planet and mankind. "Copenhagen" by Michael Frayn on 29 January and on 4, 10, 15 and 16 February 2005 Why did Werner Heisenberg, who was involved in the Third Reich's nuclear research programme, visit his friend and mentor Niels Bohr in occupied Denmark in September 1941? Was it a deliberate attempt to mislead the allies, whose cause Bohr supported? Or was he r...

Uncertainty relation and simultaneous measurements in quantum theory

International Nuclear Information System (INIS)

Busch, P.

1982-01-01

In this thesis the question for the interpretation of the uncertainty relation is picked up, and a program for the justification of its individualistic interpretation is formulated. By means of quantum mechanical models for the position and momentum measurement a justification of the interpretaton has been tried by reconstruction of the origin of the uncertainties from the conditions of the measuring devices and the determination of the relation of the measured results to the object. By means of a model of the common measurement it could be shown how the uncertainty relation results from the not eliminable mutual disturbance of the devices and the uncertainty relation for the measuring system. So finally the commutation relation is conclusive. For the illustration the split experiment is discussed, first according to Heisenberg with fixed split, then for the quantum mechanical, movable split (Bohr-Einstein). (orig./HSI) [de

The Ineliminable Distortion of Reality: On Causality, Representation, Abstraction and Idealization in Batterman’s Philosophy of Science

DEFF Research Database (Denmark)

Bentzen, Martin Mose

will be subject to the same type of criticism as the deductive-nomological model, e.g. why not explain the length of strings of pendulums via an analysis of parameters connected to their periods and gravitational acceleration? I conclude that although asymptotic explanations do not directly appeal to causality...... explanations do not directly appeal to causal factors at the macro level, they presuppose them. For instance, the modeler’s choice of which parameters (or dimensions) are essential to the explanation of a certain phenomenon and which are consequently taken as a starting point for a dimensional analysis, see......) or that they proceed by appealing to fictional highly idealized models in physics, see (Bokulich, 2011), (Pexton, 2014), (Wayne, 2015). I claim that these arguments do not preclude that causality is presupposed at the macro-level, except perhaps in quantum theoretical explanations in which case an appeal to Bohr...

Perovskite Quantum Dots Modeled Using ab Initio and Replica Exchange Molecular Dynamics

KAUST Repository

Buin, Andrei; Comin, Riccardo; Ip, Alexander H.; Sargent, Edward H.

2015-01-01

© 2015 American Chemical Society. Organometal halide perovskites have recently attracted tremendous attention at both the experimental and theoretical levels. Much of this work has been dedicated to bulk material studies, yet recent experimental work has shown the formation of highly efficient quantum-confined nanocrystals with tunable band edges. Here we investigate perovskite quantum dots from theory, predicting an upper bound of the Bohr radius of 45 Å that agrees well with literature values. When the quantum dots are stoichiometric, they are trap-free and have nearly symmetric contributions to confinement from the valence and conduction bands. We further show that surface-associated conduction bandedge states in perovskite nanocrystals lie below the bulk states, which could explain the difference in Urbach tails between mesoporous and planar perovskite films. In addition to conventional molecular dynamics (MD), we implement an enhanced phase-space sampling algorithm, replica exchange molecular dynamics (REMD). We find that in simulation of methylammonium orientation and global minima, REMD outperforms conventional MD. To the best of our knowledge, this is the first REMD implementation for realistic-sized systems in the realm of DFT calculations.

Perovskite Quantum Dots Modeled Using ab Initio and Replica Exchange Molecular Dynamics

KAUST Repository

Buin, Andrei

2015-06-18

© 2015 American Chemical Society. Organometal halide perovskites have recently attracted tremendous attention at both the experimental and theoretical levels. Much of this work has been dedicated to bulk material studies, yet recent experimental work has shown the formation of highly efficient quantum-confined nanocrystals with tunable band edges. Here we investigate perovskite quantum dots from theory, predicting an upper bound of the Bohr radius of 45 Å that agrees well with literature values. When the quantum dots are stoichiometric, they are trap-free and have nearly symmetric contributions to confinement from the valence and conduction bands. We further show that surface-associated conduction bandedge states in perovskite nanocrystals lie below the bulk states, which could explain the difference in Urbach tails between mesoporous and planar perovskite films. In addition to conventional molecular dynamics (MD), we implement an enhanced phase-space sampling algorithm, replica exchange molecular dynamics (REMD). We find that in simulation of methylammonium orientation and global minima, REMD outperforms conventional MD. To the best of our knowledge, this is the first REMD implementation for realistic-sized systems in the realm of DFT calculations.

Bell's theorem and the nature of reality

International Nuclear Information System (INIS)

Bertlmann, R.A.

1988-01-01

We rediscuss the Einstein-Podolsky-Rosen paradox in Bohm's spin version and oppose to it Bohr's controversial point of view. Then we explain Bell's theorem, Bell inequalities and its consequences. We describe the experiment of Aspect, Dalibard and Roger in detail. Finally we draw attention to the nonlocal structure of the underlying theory. 61 refs., 8 tabs. (Author)

Proceedings of the symposium on the foundations of modern physics, 1987

International Nuclear Information System (INIS)

Lahti, P.

1987-01-01

This book discusses the following subjects: The Quantum Postulate and atomic theory; modern mathematics in formulation of basic laws of physics; uncertainty principles, Quantum systems; Niels Bohr's concept of reality; Quantum theory; language and reality in Quantum physics; Wolfgang Pauli's conception of reality; interpretation of Quantum mechanics; varieties of realism; and many-Hilbert-spaces theory of Quantum measurements

David Bohm and his work-on the occasion of his seventieth birthday

International Nuclear Information System (INIS)

Jammer, M.

1988-01-01

This biographical sketch of David Bohm summarizes his professional career, his relationships with Bohr, Einstein, Pauli, and other quantum theorists of his time, and discusses his published contributions to the fields of quantum mechanics, the refinement of the Schroedinger and Hamilton-Jacobi equations, the notion of hidden variables in particle observation and measure theory, and special relativity theory

Fulltext PDF

Indian Academy of Sciences (India)

The attitude of slightly flippant irreverence for dogma reflected in Ghalib's lines, and indeed in his life, has played an important role in the development of every scientific discipline. The physicist Niels Bohr is said to have once remarked that the opposite of a great truth was usually another great truth. Scientific belief, once it ...

Conversazioni con la sfinge il ruolo dei paradossi nelle rivoluzioni scientifiche

CERN Document Server

Klein, Etienne

1993-01-01

Niels Bohr rifiutava ogni idea troppo conservatrice con il lapidario giudizio "Non è abbastanza folle". La fisica moderna ha dimostrato l'inefficacia del buon senso per costruire teorie o comprendere particolari risultati sperimentali. In rottura con l'esperenzia comune, ha contrapposto l'inaudito all'abitudine, i concetti delicati agli archetipi classici, le ipotesi piu ardite alle apparenze rassicuranti.

On the direct observability of quantum waves

International Nuclear Information System (INIS)

Selleri, F.

1984-01-01

Fundamental experiments on the dual nature of atomic entities can be interpreted in terms of ''empty'' waves not carrying energy and momentum. Similar points of view were advanced in famous papers by Einstein, de Broglie, Bohr, and Born. Recent proposals could lead to experimental tests of this idea, using low intensity photon beams, thanks to modern experimental apparatus. (author)

The calculation of collective energies from periodic time-dependent Hartree-Fock solutions

International Nuclear Information System (INIS)

Zahed, I.; Baranger, M.

1983-06-01

A periodic TDHF solution is used as the reference state for a diagrammatic expansion of the propagator. A discrete Fourier transform leads to a function of energy, whose poles are the corresponding energy levels. Limiting the expansion to first-order diagrams leads to a new derivation of the Bohr-Sommerfeld-like quantization rule for collective states

The quark revolution and the ZGS - new quarks physics since the ZGS

International Nuclear Information System (INIS)

Lipkin, H.J.

1994-01-01

Overwhelming experimental evidence for quarks as real physical constituents of hadrons along with the QCD analogs of the Balmer Formula, Bohr Atom and Schroedinger Equation already existed in 1966 but was dismissed as heresy. ZGS experiments played an important role in the quark revolution. This role is briefly reviewed and subsequent progress in quark physics is described

The atom in human thought history

International Nuclear Information System (INIS)

Pullman, B.

1995-01-01

This book speaks of atom history. From the ancient Greece until now, science debated around the question for or against the atom conception of universe. In this book of sciences history, the author goes over the major events of this intellectual joust with a real pedagogic care, from Democrite, Aristote, Platon to Planck, Bohr, Einstein, Schroedinger and some others

Report of the Army Science Board Summer Study on Installations 2025

Science.gov (United States)

2009-12-01

stresses , beha- vioral health problems, and injuries associated with war. Transform: IMCOM is modernizing installation management processes, policies...well. For example, "Prediction is very difficult, especially about the future" (Niels Bohr). Others stress that the future will be a lot like the...34homogenization" Endangered species Continuous and ubiquitous of society Islanding computing Telecommuting Wireless proliferation across appliances

Inelastic Transitions in Slow Collisions of Anti-Hydrogen with Hydrogen Atoms

Science.gov (United States)

Harrison, Robert; Krstic, Predrag

2007-06-01

We calculate excited adiabatic states and nonadiabatic coupling matrix elements of a quasimolecular system containing hydrogen and anti-hydrogen atoms, for a range of internuclear distances from 0.2 to 20 Bohrs. High accuracy is achieved by exact diagonalization of the molecular Hamiltionian in a large Gaussian basis. Nonadiabatic dynamics was calculated by solving MOCC equations. Positronium states are included in the consideration.

Neutrons as Party Animals: An Analogy for Understanding Heavy-Element Fissility

Science.gov (United States)

Reed, B. Cameron

2012-01-01

I teach a general education class on the history of nuclear physics and the Manhattan Project. About halfway through the course we come to the discovery of fission and Niels Bohr's insight that it is the rare isotope of uranium, U-235, which fissions under slow-neutron bombardment as opposed to the much more common U-238 isotope. As an…

Quantum leaps in philosophy of mind: Reply to Bourget'scritique

Energy Technology Data Exchange (ETDEWEB)

Stapp, Henry P.

2004-07-26

David Bourget has raised some conceptual and technical objections to my development of von Neumann's treatment of the Copenhagen idea that the purely physical process described by the Schroedinger equation must be supplemented by a psychophysical process called the choice of the experiment by Bohr and Process 1 by von Neumann. I answer here each of Bourget's objections.

Oxygen and carbon dioxide transporting qualities of hemocyanin in the hemolymph of a natant decapod Palaemon adspersus

DEFF Research Database (Denmark)

Weber, Roy E.; Hagerman, L.

1981-01-01

, pH dependent Bohr factor (=logP 50/pH=-2.0 and -0.9 at pH 7.85 and 7.4, respectively) (Figs. 1 and 2). These qualities are distinct from those typifying reptant hemocyanins and appear illsuited for O2 transport at low ambient tensions, but well-adapted for O2 delivery in tissues at high PO2...

Interfacial properties at the organic-metal interface probed using quantum well states

Science.gov (United States)

Lin, Meng-Kai; Nakayama, Yasuo; Wang, Chin-Yung; Hsu, Jer-Chia; Pan, Chih-Hao; Machida, Shin-ichi; Pi, Tun-Wen; Ishii, Hisao; Tang, S.-J.

2012-10-01

Using angle-resolved photoemission spectroscopy, we investigated the interfacial properties between the long-chain normal-alkane molecule n-CH3(CH2)42CH3 [tetratetracontane (TTC)] and uniform Ag films using the Ag quantum well states. The entire quantum well state energy band dispersions were observed to shift toward the Fermi level with increasing adsorption coverage of TTC up to 1 monolayer (ML). However, the energy shifts upon deposition of 1 ML of TTC are approximately inversely dependent on the Ag film thickness, indicating a quantum-size effect. In the framework of the pushback and image-force models, we applied the Bohr-Sommerfeld quantization rule with the modified Coulomb image potential for the phase shift at the TTC/Ag interface to extract the dielectric constant for 1 ML of TTC.

Nonlinear Schroedinger equation with U(p,q) isotopical group

International Nuclear Information System (INIS)

Makhankov, V.G.; Pashaev, O.K.

1981-01-01

The properties of the nonlinear Schroedinger equation (NLS) with U(1,1) isogroup are considered in detail. This example illustrates the essential difference between the system and the well-known ''vector'' NLS, i.e. the large set of allowed boundary conditions on the fields that leads to a rich set of solutions of the system. Four types of boundary conditions and related soliton solutions are considered. The Bohr-Sommerfeld quantization allows to interpret them in terms of ''drops'' and ''bubbles'' as bound states of a large number of constituent bosons subject to the thermodynamical relations for gas mixtures. The U(1,1) system under the vanishing boundary conditions may be considered as continuous analog of the Hubbard model and therefore the paper is concluded by studying the inverse scattering equations for this case [ru

Observation of the 1S–2S transition in trapped antihydrogen

CERN Document Server

Ahmadi, M.; Baker, C.J.; Bertsche, W.; Butler, E.; Capra, A.; Carruth, C.; Cesar, C.L.; Charlton, M.; Cohen, S.; Collister, R.; Eriksson, S.; Evans, A.; Evetts, N.; Fajans, J.; Friesen, T.; Fujiwara, M.C.; Gill, D.R.; Gutierrez, A.; Hangst, J. S.; Hardy, W.N.; Hayden, M.E.; Isaac, C.A.; Ishida, A.; Johnson, M.A.; Jones, S.A.; Jonsell, S.; Kurchaninov, L.; Madsen, N.; Mathers, M.; Maxwell, D.; McKenna, J.T.K.; Menary, S.; Michan, J.M.; Momose, T.; Munich, J.J.; Nolan, P.; Olchanski, K.; Olin, A.; Pusa, P.; Rasmussen, C.Ø.; Robicheaux, F.; Sacramento, R.L.; Sameed, M.; Sarid, E.; Silveira, D.M.; Stracka, S.; Stutter, G.; So, C.; Tharp, T.D.; Thompson, J.E.; Thompson, R.I.; van der Werf, D.P.; Wurtele, J.S.

2016-01-01

The spectrum of the hydrogen atom has played a central part in fundamental physics in the past 200 years. Historical examples of its significance include the wavelength measurements of absorption lines in the solar spectrum by Fraunhofer, the identification of transition lines by Balmer, Lyman et al., the empirical description of allowed wavelengths by Rydberg, the quantum model of Bohr, the capability of quantum electrodynamics to precisely predict transition frequencies, and modern measurements of the 1S–2S transition by Hänsch1 to a precision of a few parts in 1015. Recently, we have achieved the technological advances to allow us to focus on antihydrogen—the antimatter equivalent of hydrogen2,3,4. The Standard Model predicts that there should have been equal amounts of matter and antimatter in the primordial Universe after the Big Bang, but today’s Universe is observed to consist almost entirely of ordinary matter. This motivates physicists to carefully study antimatter, to see if there is a small ...

Observation of the 1S–2S transition in trapped antihydrogen

CERN Document Server

Ahmadi, M.; Baker, C.J.; Bertsche, W.; Butler, E.; Capra, A.; Carruth, C.; Cesar, C.L.; Charlton, M.; Cohen, S.; Collister, R.; Eriksson, S.; Evans, A.; Evetts, N.; Fajans, J.; Friesen, T.; Fujiwara, M.C.; Gill, D.R.; Gutierrez, A.; Hangst, J. S.; Hardy, W.N.; Hayden, M.E.; Isaac, C.A.; Ishida, A.; Johnson, M.A.; Jones, S.A.; Jonsell, S.; Kurchaninov, L.; Madsen, N.; Mathers, M.; Maxwell, D.; McKenna, J.T.K.; Menary, S.; Michan, J.M.; Momose, T.; Munich, J.J.; Nolan, P.; Olchanski, K.; Olin, A.; Pusa, P.; Rasmussen, C.Ø.; Robicheaux, F.; Sacramento, R.L.; Sameed, M.; Sarid, E.; Silveira, D.M.; Stracka, S.; Stutter, G.; So, C.; Tharp, T.D.; Thompson, J.E.; Thompson, R.I.; van der Werf, D.P.; Wurtele, J.S.

2017-01-01

The spectrum of the hydrogen atom has played a central part in fundamental physics in the past 200 years. Historical examples of its significance include the wavelength measurements of absorption lines in the solar spectrum by Fraunhofer, the identification of transition lines by Balmer, Lyman et al., the empirical description of allowed wavelengths by Rydberg, the quantum model of Bohr, the capability of quantum electrodynamics to precisely predict transition frequencies, and modern measurements of the 1S–2S transition by Hänsch1 to a precision of a few parts in 1015. Recently, we have achieved the technological advances to allow us to focus on antihydrogen—the antimatter equivalent of hydrogen2,3,4. The Standard Model predicts that there should have been equal amounts of matter and antimatter in the primordial Universe after the Big Bang, but today’s Universe is observed to consist almost entirely of ordinary matter. This motivates physicists to carefully study antimatter, to see if there is a small ...

A Research-Informed Approach to Teaching About Light & Matter in STEM Classrooms

Science.gov (United States)

Hornstein, Seth D.; Wallace, C. S.; Schlingman, W. M.; Prather, E. E.

2014-01-01

In collaboration with the National Radio Astronomy Observatory (NRAO), we have engaged in a research and curriculum development program to bring the detailed science of light and matter into STEM classrooms. Typical Astro 101 classes often discuss emission/absorption spectra with reference to the Bohr model only and teach radiation as produced/absorbed only by electron transitions. We present here curricula developed to highlight other emission/absorption phenomena (specifically those produced by rotational/vibrational molecular transitions as well as synchrotron radiation.) Appropriate for physical science classrooms from middle school to the introductory college level, the learner-centered active engagement activities we are developing are going through an iterative research and assessment process to ensure that they enable students to achieve increased conceptual understandings and reasoning skills. In this talk, we will report on our development process for a suite of activities, including lecture slides, Think-Pair-Share questions, assessment questions and a new Lecture-Tutorial that help students learn about these other important emission models.

The Bohr-Sommerfeld quantization of n-dimensional neutral and charged pulsons

International Nuclear Information System (INIS)

Bogolubsky, I.L.

1978-01-01

The spectrum of masses of 1) neutral and 2) having elementary charge Q=1 of n-dimensional pulsons (i.e., localized oscillating extended solutions) is found by numerical integration using a computer in the framework of the Klein-Gordon equation with the logarithmic nonlinearity. Computer experiments point out that the pulsons under consideration are apparently stable at any n

Gravitationally confined relativistic neutrinos

Science.gov (United States)

Vayenas, C. G.; Fokas, A. S.; Grigoriou, D.

2017-09-01

Combining special relativity, the equivalence principle, and Newton’s universal gravitational law with gravitational rather than rest masses, one finds that gravitational interactions between relativistic neutrinos with kinetic energies above 50 MeV are very strong and can lead to the formation of gravitationally confined composite structures with the mass and other properties of hadrons. One may model such structures by considering three neutrinos moving symmetrically on a circular orbit under the influence of their gravitational attraction, and by assuming quantization of their angular momentum, as in the Bohr model of the H atom. The model contains no adjustable parameters and its solution, using a neutrino rest mass of 0.05 eV/c2, leads to composite state radii close to 1 fm and composite state masses close to 1 GeV/c2. Similar models of relativistic rotating electron - neutrino pairs give a mass of 81 GeV/c2, close to that of W bosons. This novel mechanism of generating mass suggests that the Higgs mass generation mechanism can be modeled as a latent gravitational field which gets activated by relativistic neutrinos.

Investigating the fission process at high excitation energies through proton induced reactions on 181Ta

International Nuclear Information System (INIS)

Ayyad, Y.; Benlliure, J.; Casajeros, E.; Alvarez Pol, H.; Paradela, C.; Perez-Loureido, D.; Tarrio, D.; Bacquias, A.; Boudard, A.; Kezzar, K.; Leray, S.; Enqvist, T.; Foehr, V.; Kelic, A.; Pleskac, R.

2010-01-01

In this work we have investigated the total fission cross section of 181 Ta + 1 H at FRS (Fragment Separator - GSI) at 1, 0.8, 0.5 and 0.3 GeV with a specific setup, providing high accuracy measurements of the cross section values. the comparison of our data with previous results reveals a good agreement at high energies. However the situation remains unclear at lower energies. In general, our results covering a wide range of energy, are smoother. We have also compared the results obtained in this experiment, with several calculations performed with the intra-nuclear cascade model (INCL v4.1) coupled to de-excitation code (ABLAv3p), according to two different models describing fission process at high-excitation energies: statistical model of Bohr and Wheeler and the dynamical description of the fission process. We have showed that a simple statistical description largely over-predict the measured cross-section. Only a dynamical description of the fission, involving the role of the viscosity of the nuclear matter, provides a realistic result.

Exciton confinement in strain-engineered metamorphic InAs/I nxG a1 -xAs quantum dots

Science.gov (United States)

Khattak, S. A.; Hayne, M.; Huang, J.; Vanacken, J.; Moshchalkov, V. V.; Seravalli, L.; Trevisi, G.; Frigeri, P.

2017-11-01

We report a comprehensive study of exciton confinement in self-assembled InAs quantum dots (QDs) in strain-engineered metamorphic I nxG a1 -xAs confining layers on GaAs using low-temperature magnetophotoluminescence. As the lattice mismatch (strain) between QDs and confining layers (CLs) increases from 4.8% to 5.7% the reduced mass of the exciton increases, but saturates at higher mismatches. At low QD-CL mismatch there is clear evidence of spillover of the exciton wave function due to small localization energies. This is suppressed as the In content x in the CLs decreases (mismatch and localization energy increasing). The combined effects of low effective mass and wave-function spillover at high x result in a diamagnetic shift coefficient that is an order of magnitude larger than for samples where In content in the barrier is low (mismatch is high and localization energy is large). Finally, an anomalously small measured Bohr radius in samples with the highest x is attributed to a combination of thermalization due to low localization energy, and its enhancement with magnetic field, a mechanism which results in small dots in the ensemble dominating the measured Bohr radius.

On the Character of Quantum Law: Complementarity, Entanglement, and Information

Science.gov (United States)

Plotnitsky, Arkady

2017-08-01

This article considers the relationships between the character of physical law in quantum theory and Bohr's concept of complementarity, under the assumption of the unrepresentable and possibly inconceivable nature of quantum objects and processes, an assumption that may be seen as the most radical departure from realism currently available. Complementarity, the article argues, is a reflection of the fact that, as against classical physics or relativity, the behavior of quantum objects of the same type, say, all electrons, is not governed by the same physical law in all contexts, specifically in complementary contexts. On the other hand, the mathematical formalism of quantum mechanics offers correct probabilistic or statistical predictions (no other predictions are possible on experimental grounds) in all contexts, here, again, under the assumption that quantum objects themselves and their behavior are beyond representation or even conception. Bohr, in this connection, spoke of "an entirely new situation as regards the description of physical phenomena that, the notion of complementarity aims at characterizing." The article also considers the relationships among complementarity, entanglement, and quantum information, by basing these relationships on this understanding of complementarity.

Karl Popper's Quantum Ghost

Science.gov (United States)

Shields, William

2004-05-01

Karl Popper, though not trained as a physicist and embarrassed early in his career by a physics error pointed out by Einstein and Bohr, ultimately made substantial contributions to the interpretation of quantum mechanics. As was often the case, Popper initially formulated his position by criticizing the views of others - in this case Niels Bohr and Werner Heisenberg. Underlying Popper's criticism was his belief that, first, the "standard interpretation" of quantum mechanics, sometimes called the Copenhagen interpretation, abandoned scientific realism and second, the assertion that quantum theory was "complete" (an assertion rejected by Einstein among others) amounted to an unfalsifiable claim. Popper insisted that the most basic predictions of quantum mechanics should continue to be tested, with an eye towards falsification rather than mere adding of decimal places to confirmatory experiments. His persistent attacks on the Copenhagen interpretation were aimed not at the uncertainty principle itself and the formalism from which it was derived, but at the acceptance by physicists of an unclear epistemology and ontology that left critical questions unanswered. In 1999, physicists at the University of Maryland conducted a version of Popper's Experiment, re-igniting the debate over quantum predictions and the role of locality in physics.

Physical explanation of the periodic table.

Science.gov (United States)

Ostrovsky, V N

2003-05-01

The Periodic Table of the elements, the most important generalization in chemistry, is often considered as a representative special case in the study of the relation between chemistry and physics. Its quantum interpretation was initiated, but not completed, by Niels Bohr. In this paper, post-Bohr conceptual developments are discussed from historical and epistemological points of view. The difference between high-precision numerical calculations for individual atoms and the theory of the periodic system as a whole is emphasized. Periodic laws met in Nature are not restricted to the chemical Periodic Table. A comparative study of these laws makes it possible to single out essential features that define the particular pattern of periodicity. It is shown that the periodic system of neutral ground state atoms now has a firm nonempirical quantum-theoretical basis. Alternative approaches, based on group theory and other mathematical schemes, are briefly discussed. It is argued that, while quantum theory is capable of fully accurate calculations for relatively simple atoms or molecular objects, the complexity of polyatomic molecules and chemical reactions guarantees the flourishing of chemistry as a separate scientific discipline.

Locality and reality

International Nuclear Information System (INIS)

Stapp, H.P.

1980-01-01

Einstein's principle that no signal travels faster than light suggests that observations in one spacetime region should not depend on whether or not a radioactive decay is detected in a spacelike-separated region. This locality property is incompatible with the predictions of quantum theory, and this incompatibility holds independently of the questions of realism, objective reality, and hidden variables. It holds both in the pragmatic quantum theory of Bohr and in realistic frameworks. It is shown here to hold in a completed realistic quantum theory that reconciles Einstein's demand for a description of reality itself with Bohr's contention that quantum theory is complete. This completed realistic quantum theory has no hidden variables, and no objective reality in which observable attributes can become definite independently of observers. The theory is described in some detail, with particular attention to those aspects related to the question of locality. This completed realistic quantum theory is in principle more comprehensive than Bohn's pragmatic quantum theory because it is not limited in principle by the requirement that the observed system be physically separated from the observing one. Applications are discussed

The Magnetisation of MnB and its Variation with Temperature

Energy Technology Data Exchange (ETDEWEB)

Lundquist, N; Myers, H P

1960-12-15

It has been shown that MnB is the only ferromagnetic phase occurring in the Mn-B system. The magnetisation per unit mass at 0 K and in infinite field strength has been found to be 163 corresponding to a Bohr magneton value 1.92 per Mn atom. The Curie temperature in zero field is 300 C. The significance of this magnetic data is discussed.

Details of Nazis' A-Bomb program surface

CERN Multimedia

Glanz, J

2002-01-01

Werner Heisenberg, leader of the Nazi atomic bomb program, revealed the projects existence to Niels Bohr in a meeting in Copenhagen in 1941. But contrary to several historical accounts of the meeting, Heisenberg never expressed moral qualms about building a bomb for Hitler nor hinted that he might be willing to sabotage the project, according to secret documents cited in a London newspaper yesterday (2 pages).

Wave-Particle Dualism in Action

Science.gov (United States)

Schleich, Wolfgang P.

The wave-particle dualism, that is the wave nature of particles and the particle nature of light together with the uncertainty relation of Werner Heisenberg and the principle of complementarity formulated by Niels Bohr represent pillars of quantum theory. We provide an introduction into these fascinating yet strange aspects of the microscopic world and summarize key experiments confirming these concepts so alien to our daily life.

Magnetic susceptibility of Gd/sub 3/Ga/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Hacker, H Jr; Gupta, R M [Duke Univ., Durham, N.C. (USA). Dept. of Electrical Engineering

1976-03-01

The magnetic susceptibility of the intermetallic compound Gd/sub 3/Ga/sub 2/ has been measured by the Faraday method over the range 8 - 300 K. The data indicate antiferromagnetic behavior below 53 K. Above 100 K, the mass susceptibility obeys the Curie-Weiss law, chisub(g)=4.45X10/sup -2//(T+23)emu/gOe. The corresponding effective moment is 8.51 Bohr magnetons.

On the Way of Truth: Strigachev, 2016 [In Bulgarian

Directory of Open Access Journals (Sweden)

B.V. Toshev

2017-12-01

Full Text Available The first part of Strigachev’s book is devoted to the contribution of the greatest scientists of modern physics Planck, Einstein, Rutherford and Bohr. Relativity is understood as a negation of the absolute. Two are the main principles: the principle of conservation and the principle of complementarity. The author suggests a proper combination of four principles – those of relativity, conservation, correspondence and complementarity.

Multiple evolutionary events involved in maintaining homologs of Resistance to Powdery Mildew 8 in Brassica napus

Directory of Open Access Journals (Sweden)

Qin Li

2016-07-01

Full Text Available The Resistance to Powdery Mildew 8 (RPW8 locus confers broad-spectrum resistance to powdery mildew in Arabidopsis thaliana. There are four Homologous to RPW8s (BrHRs in Brassica rapa and three in B. oleracea (BoHRs. B. napus (Bn is derived from diploidization of a hybrid between B. rapa and B. oleracea, thus should have seven homologs of RPW8 (BnHRs. It is unclear whether these genes are still maintained or lost in B. napus after diploidization and how they might have been evolved. Here we reported the identification and sequence polymorphisms of BnHRs from a set of B. napus accessions. Our data indicated that while the BoHR copy from B. oleracea is highly conserved, the BrHR copy from B. rapa is relatively variable in the B. napus genome owing to multiple evolutionary events, such as gene loss, point mutation, insertion, deletion and intragenic recombination. Given the overall high sequence homology of BnHR genes, it is not surprising that both intragenic recombination between two orthologs and two paralogs were detected in B. napus, which may explain the loss of BoHR genes in some B. napus accessions. When ectopically expressed in Arabidopsis, a C-terminally truncated version of BnHRa and BnHRb, as well as the full length BnHRd fused with YFP at their C-termini could trigger cell death in the absence of pathogens and enhanced resistance to powdery mildew disease. Moreover, subcellular localization analysis showed that both BnHRa-YFP and BnHRb-YFP were mainly localized to the extra-haustorial membrane (EHM encasing the haustorium of powdery mildew. Taken together, our data suggest that the duplicated BnHR genes might have been subjected to differential selection and at least some may play a role in defense and could serve as resistance resource in engineering disease-resistant plants.

Description of giant resonances

International Nuclear Information System (INIS)

Lane, A.M.

1975-01-01

The history of collective theories in nuclear physics is briefly reviewed. It is emphasised that some theories (like RPA) allow collectivity to emerge from calculations, while others (like GCM) essentially impose a collective framework from teh start. The former class has the incidental merit that it treats spreading of collective states arising from interaction with (discrete and continuum) particle excitations. A problem with the RPA calculations is that they are almost too detailed if one's interest is in exposing systematic qualitative features. The speaker (along with co-authors) has developed a sum-rule method for exposing such trends. It is based on the fact that one can readily evaluate three sum-rules; in addition to the familiar one with plus-one power of energy-weighting, those with minus-one and plus-three powers can be evaluated for RPA states in closed form. From the three moments, the energy and spread of the collective state can be obtained. Amongst other things, the approach gives a very simple derivation of the Suzuki-Mottelson result that collective energy equals √2 times the oscillator quantum. (orig.) [de

Thermodynamics of charged Lovelock: AdS black holes

International Nuclear Information System (INIS)

Prasobh, C.B.; Suresh, Jishnu; Kuriakose, V.C.

2016-01-01

We investigate the thermodynamic behavior of maximally symmetric charged, asymptotically AdS black hole solutions of Lovelock gravity. We explore the thermodynamic stability of such solutions by the ordinary method of calculating the specific heat of the black holes and investigating its divergences which signal second-order phase transitions between black hole states. We then utilize the methods of thermodynamic geometry of black hole spacetimes in order to explain the origin of these points of divergence. We calculate the curvature scalar corresponding to a Legendre-invariant thermodynamic metric of these spacetimes and find that the divergences in the black hole specific heat correspond to singularities in the thermodynamic phase space. We also calculate the area spectrum for large black holes in the model by applying the Bohr-Sommerfeld quantization to the adiabatic invariant calculated for the spacetime. (orig.)

Thermodynamics of charged Lovelock: AdS black holes

Science.gov (United States)

Prasobh, C. B.; Suresh, Jishnu; Kuriakose, V. C.

2016-04-01

We investigate the thermodynamic behavior of maximally symmetric charged, asymptotically AdS black hole solutions of Lovelock gravity. We explore the thermodynamic stability of such solutions by the ordinary method of calculating the specific heat of the black holes and investigating its divergences which signal second-order phase transitions between black hole states. We then utilize the methods of thermodynamic geometry of black hole spacetimes in order to explain the origin of these points of divergence. We calculate the curvature scalar corresponding to a Legendre-invariant thermodynamic metric of these spacetimes and find that the divergences in the black hole specific heat correspond to singularities in the thermodynamic phase space. We also calculate the area spectrum for large black holes in the model by applying the Bohr-Sommerfeld quantization to the adiabatic invariant calculated for the spacetime.

L'Afrique, nouvel Eldorado du commerce | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

5 déc. 2013 ... Il est directeur du Perimeter Institute for Theoretical Physics, où il est également titulaire de la chaire Mike and Ophelia Lazaridis Niels Bohr. Thierry Zomahoun, M.B.A., M.Ph., est directeur général de l'AIMS Next Einstein Initiative (AIMS-NEI) et directeur du secrétariat mondial d'AIMS. Cet article a été publié ...

Quantum mechanics interpretation: scalled debate

International Nuclear Information System (INIS)

Sanchez Gomez, J. L.

2000-01-01

This paper discusses the two main issues of the so called quantum debate, that started in 1927 with the famous Bohr-Einstein controversy; namely non-separability and the projection postulate. Relevant interpretations and formulations of quantum mechanics are critically analyzed in the light of the said issues. The treatment is focused chiefly on fundamental points, so that technical ones are practically not dealt with here. (Author) 20 refs

Quantum mechanics interpretation: scalled debate; La interpretacion de la teoria cuantica: un debate permanente

Energy Technology Data Exchange (ETDEWEB)

Sanchez Gomez, J. L.

2000-07-01

This paper discusses the two main issues of the so called quantum debate, that started in 1927 with the famous Bohr-Einstein controversy; namely non-separability and the projection postulate. Relevant interpretations and formulations of quantum mechanics are critically analyzed in the light of the said issues. The treatment is focused chiefly on fundamental points, so that technical ones are practically not dealt with here. (Author) 20 refs.

Report of activities, 1975

International Nuclear Information System (INIS)

1976-01-01

A list of staff and research fellows at NORDITA is given. NORDITA publications and lecture notes of the period in question are listed. In addition to regular lectures, colloquia were held in collaboration with the Niels Bohr Institute. Details are given of visiting physicists attached to NORDITA. The exchange of physicists within the Nordic institutions as well as the visits by former NORDITA research fellows are listed. (B.R.H.)

L'Afrique, nouvel Eldorado du commerce | CRDI - Centre de ...

International Development Research Centre (IDRC) Digital Library (Canada)

5 déc. 2013 ... Il est directeur du Perimeter Institute for Theoretical Physics, où il est également titulaire de la chaire Mike and Ophelia Lazaridis Niels Bohr. Thierry Zomahoun, M.B.A., M.Ph., est directeur général de l'AIMS Next Einstein Initiative (AIMS-NEI) et directeur du secrétariat mondial d'AIMS. Cet article a été publié ...

An atomically thin matter-wave beamsplitter.

Science.gov (United States)

Brand, Christian; Sclafani, Michele; Knobloch, Christian; Lilach, Yigal; Juffmann, Thomas; Kotakoski, Jani; Mangler, Clemens; Winter, Andreas; Turchanin, Andrey; Meyer, Jannik; Cheshnovsky, Ori; Arndt, Markus

2015-10-01

Matter-wave interferometry has become an essential tool in studies on the foundations of quantum physics and for precision measurements. Mechanical gratings have played an important role as coherent beamsplitters for atoms, molecules and clusters, because the basic diffraction mechanism is the same for all particles. However, polarizable objects may experience van der Waals shifts when they pass the grating walls, and the undesired dephasing may prevent interferometry with massive objects. Here, we explore how to minimize this perturbation by reducing the thickness of the diffraction mask to its ultimate physical limit, that is, the thickness of a single atom. We have fabricated diffraction masks in single-layer and bilayer graphene as well as in a 1 nm thin carbonaceous biphenyl membrane. We identify conditions to transform an array of single-layer graphene nanoribbons into a grating of carbon nanoscrolls. We show that all these ultrathin nanomasks can be used for high-contrast quantum diffraction of massive molecules. They can be seen as a nanomechanical answer to the question debated by Bohr and Einstein of whether a softly suspended double slit would destroy quantum interference. In agreement with Bohr's reasoning we show that quantum coherence prevails, even in the limit of atomically thin gratings.

Adaptation to extreme environments: structure-function relationships in Emperor penguin haemoglobin.

Science.gov (United States)

Tamburrini, M; Condò, S G; di Prisco, G; Giardina, B

1994-04-15

The functional properties of the single haemoglobin (Hb) of Emperor penguin (Aptenodytes forsteri) have been investigated at different temperatures as a function of proton and organic phosphate concentration. The complete amino acid sequence has been established. Comparison with that of human HbA shows 12 substitutions in the contact regions of alpha beta dimers. In addition to overall similarities shared with most of the avian Hbs previously described, this Hb shows significant differences, which could be related to the peculiar behaviour of this penguin. In particular we may consider that: (1) the shape of the Bohr effect curve seems well adapted for gas exchange during very prolonged dives, preserving penguin Hb from a sudden and not controlled stripping of oxygen; (2) the very minor enthalpy change observed at lower pH could be an example of molecular adaptation, through which oxygen delivery becomes essentially insensitive to exposure to the extremely low temperatures of the environment. Moreover, the small alkaline Bohr effect has been found to be only chloride-linked, since the pH dependence of the oxygen affinity is totally abolished in the absence of this ion. These functional characteristics are discussed on the basis of the primary structure of alpha and beta-chains.

PIXE and Moseley's law

International Nuclear Information System (INIS)

Huddle, James R.

2001-01-01

In an undergraduate atomic physics experiment, 2.8 MeV protons are used to bombard thick elemental targets. X rays emitted from the targets are detected with a Si(Li) detector, and their energies are measured with a multichannel analyzer. The Kα and Kβ x-ray energies are each plotted as functions of (Z-1) 2 , and the Rydberg energy, Rch, is extracted from the slopes of the resulting lines. The Kα plot gives Rch=14.099±0.025 eV, while the Kβ plot gives 13.557±0.027 eV. The experiment extends the Bohr Theory as discussed in class, serves to introduce PIXE as a quantitative technique for elemental analysis, gives the students experience in using modern instruments which may be used in later experiments, and experience in using uncertainty analysis to decide whether their measurements agree or disagree with other measurements or theoretical calculations. Although the experimental values differ from each other and from the accurately-known value of 13.606 eV by less than 4%, they do not agree to within the experimental uncertainties, forcing students to consider a systematic error arising from their use of the Bohr Theory to derive Moseley's Law

Erythrocyte 2,3-DPG, PO2 50% and available O2 during the early post-natal fall in hemoglobin in rabbits.

Science.gov (United States)

Holter, P H; Halvorsen, S; Refsum, H E

1982-09-01

Erythrocyte 2,3-DPG, PO2 50%, whole blood hemoglobin and available O2, and fixed acid Bohr effect were studied during the first 10 days after birth in rapidly growing suckling rabbits. The post-natal fall in hemoglobin concentration was accompanied by a marked rise in erythrocyte 2,3-DPG and a gradual increase in PO2 50%. The rise in PO2 50% was sufficient to keep the available O2 of the blood unchanged throughout the observation period. The observations show that a 2,3-DPG mediated rise in PO2 50% very effectively contributes to maintenance of adequate tissue oxygenation during the post-natal fall in hemoglobin. The rise in 2,3-DPG and and PO2 50% may be due to the ordinary hypoxia-induced shift to the right of the hemoglobin O2 dissociation curve, as observed under other circumstances when blood hemoglobin is rapidly reduced, but the very marked rise in 2,3-DPG and the very low delta PO2 50%/delta 2,3-DPG ratio suggest that the rise may as well be due to hypoxia independent, pre-programmed processes. The fixed acid Bohr effect was essentially the same in newborn and adult rabbits, and was uninfluenced by large variations in 2,3-DPG.

Quantum Einstein, Bohr and the great debate about the nature of reality

CERN Document Server

Kumar, Manjit

2008-01-01

For most people, quantum theory is a byword for mysterious, impenetrable science. And yet for many years it was equally baffling for scientists themselves. Manjit Kumar gives a dramatic and superbly-written history of this fundamental scientific revolution, and the divisive debate at its heart.  For 60 years most physicists believed that quantum theory denied the very existence of reality itself. Yet Kumar shows how the golden age of physics ignited the greatest intellectual debate of the twentieth century.  Quantum sets the science in the context of the great upheavals of the modern age. In 1

Uncertainty Einstein, Heisenberg, Bohr, and the struggle for the soul of science

CERN Document Server

Lindley, David

2007-01-01

The uncertainty in this delightful book refers to Heisenberg's Uncertainty Principle, an idea first postulated in 1927 by physicist Werner Heisenberg in his attempt to make sense out of the developing field of quantum mechanics. As Lindley so well explains it, the concept of uncertainty shook the philosophical underpinnings of science. It was Heisenberg's work that, to a great extent, kept Einstein from accepting quantum mechanics as a full explanation for physical reality. Similarly, it was the Uncertainty Principle that demonstrated the limits of scientific investigation: if Heisenberg is correct there are some aspects of the physical universe that are to remain beyond the reach of scientists. As he has done expertly in books like Boltzmann's Atom, Lindley brings to life a critical period in the history of science, explaining complex issues to the general reader, presenting the major players in an engaging fashion, delving into the process of scientific discovery and discussing the interaction between scien...

How physics confronts reality Einstein was correct, but Bohr won the game

CERN Document Server

Newton, Roger G

2009-01-01

This book recalls, for nonscientific readers, the history of quantum mechanics, the main points of its interpretation, and Einstein's objections to it, together with the responses engendered by his arguments. Most popular discussions on the strange aspects of quantum mechanics ignore the fundamental fact that Einstein was correct in his insistence that the theory does not directly describe reality. While that fact does not remove the theory's counterintuitive features, it casts them in a different light.Context is provided by following the history of two central aspects of physics: the elucida

Quasi-particle excitations and dynamical structure function of trapped Bose-condensates in the WKB approximation

OpenAIRE

Csordás, András; Graham, Robert; Szépfalusy, Péter

1997-01-01

The Bogoliubov equations of the quasi-particle excitations in a weakly interacting trapped Bose-condensate are solved in the WKB approximation in an isotropic harmonic trap, determining the discrete quasi-particle energies and wave functions by torus (Bohr-Sommerfeld) quantization of the integrable classical quasi-particle dynamics. The results are used to calculate the position and strengths of the peaks in the dynamic structure function which can be observed by off-resonance inelastic light...

A new state of the H sub 2 sup + molecular ion

CERN Document Server

Carbonell, J; Hilico, L; Kilic, S; Lazauskas, R

2002-01-01

A new state of the H sub 2 sup + molecular ion with binding energy of 1.09 x 10 sup - sup 9 a.u. below the first dissociation limit is predicted, using highly accurate numerical nonrelativistic quantum calculations. It is the first L=0 excited state, antisymmetric with respect to the exchange of the two protons. It manifests itself as a huge p-H scattering length of a = 750 +-5 Bohr radii.

Nordita. Nordic Institute for Theoretical Atomic Physics

International Nuclear Information System (INIS)

1990-01-01

This report covers the period from January 1st to December 31st, 1989. The purpose of Nordita is to encourage scientific collaboration between the Nordic countries within scientific and basic nuclear physics. The scientific programme at Nordita covers astrophysics, elementary particle physics, solid state physics and nuclear physics. The scientific work is published or otherwise made public. The research at Nordita is performed in close cooperation with the Niels Bohr Institute, Denmark. (author)

Review of Considerations, Management, and Treatment of Medical Emergencies During Commercial Flight

Science.gov (United States)

2017-04-01

MedAire, from Banner Good Samaritan Hospital, Phoenix, AZ; Stat-MD, from the University of Pittsburgh Hospital, Pittsburgh, PA; and The First Call, from...COMMON MEDICAL EMERGENCIES IN FLIGHT: THE FLIGHT ENVIRONMENT Air travel has become quite the luxurious mode of transportation in the past few...pH, known as the Bohr effect [12]. As the hydrogen ion concentration is increased, indicated by a decrease in pH, the oxyhemoglobin dissociation curve

Quantized gauge invariant periodic TDHF solutions

International Nuclear Information System (INIS)

Kan, K.-K.; Griffin, J.J.; Lichtner, P.C.; Dworzecka, M.

1979-01-01

Time-dependent Hartree-Fock (TDHF) is used to study steady state large amplitude nuclear collective motions, such as vibration and rotation. As is well known the small amplitude TDHF leads to the RPA equation. The analysis of periodicity in TDHF is not trivial because TDHF is a nonlinear theory and it is not known under what circumstances a nonlinear theory can support periodic solutions. It is also unknown whether such periodic solution, if they exist, form a continuous or a discrete set. But, these properties may be important in obtaining the energy spectrum of the collective states from the TDHF description. The periodicity and Gauge Invariant Periodicity of solutions are investigated for that class of models whose TDHF solutions depend on time through two parameters. In such models TDHF supports a continuous family of periodic solutions, but only a discrete subset of these is gauge invariant. These discrete Gauge Invariant Periodic solutions obey the Bohr-Summerfeld quantization rule. The energy spectrum of the Gauge Invariant Periodic solutions is compared with the exact eigenergies in one specific example

Synthesis and spectral properties of Methyl-Phenyl pyrazoloquinoxaline fluorescence emitters: Experiment and DFT/TDDFT calculations

Science.gov (United States)

Gąsiorski, P.; Matusiewicz, M.; Gondek, E.; Uchacz, T.; Wojtasik, K.; Danel, A.; Shchur, Ya.; Kityk, A. V.

2018-01-01

Paper reports the synthesis and spectroscopic studies of two novel 1-Methyl-3-phenyl-1H-pyrazolo[3,4-b]quinoxaline (PQX) derivatives with 6-substituted methyl (MeMPPQX) or methoxy (MeOMPPQX) side groups. The optical absorption and fluorescence emission spectra are recorded in solvents of different polarity. Steady state and time-resolved spectroscopy provide photophysical characterization of MeMPPQX and MeOMPPQX dyes as materials for potential luminescence or electroluminescence applications. Measured optical absorption and fluorescence emission spectra are compared with quantum-chemical DFT/TDDFT calculations using long-range corrected xc-functionals, LRC-BLYP and CAM-B3LYP in combination with self-consistent reaction field model based on linear response (LR), state specific (SS) or corrected linear response (CLR) solvations. Performances of relevant theoretical models and approaches are compared. The reparameterized LRC-BLYP functional (ω = 0.231 Bohr-1) in combination with CLR solvation provides most accurate prediction of both excitation and emission energies. The MeMPPQX and MeOMPPQX dyes represent efficient fluorescence emitters in blue-green region of the visible spectra.

Lessons from two paradigmatic developments; Rutherford's nuclear atom and halo nuclei

International Nuclear Information System (INIS)

Vaagen, J S; Ershov, S N; Zhukov, M V

2012-01-01

In its initial 1911 version, underpinned by discoveries in alpha-scattering experiments, Rutherford's atom model made a gross separation of neutral matter; A veil of light negative matter surrounding a tiny impenetrable heavy positive core. The model had however little to say about the atomic (electronic) architecture and dynamics, hence did not make it straight to the catwalk of physics of those days. Three quarters of a century later, in 1985, new discoveries in collision experiments revealed existence of abnormally large light nuclei, but could say less about the nuclear architecture. History sometimes repeats itself: Like Bohr's ad hoc planetary model (1913) changed the fate of Rutherford's discovery, again Scandinavian inspired ideas on architecture, this time nuclear halos, changed our paradigm for the heart of matter. We comment on the need for a concerted Rutherfordian effort between theory and increasingly complete reaction experiments if further ground-breaking progress is going to be made in halo physics, and physics in vicinities of neutron and proton driplines, and generally in the more widely growing field of many-body open quantum systems, where structure and reactions come together.

Finite Blaschke products and their connections

CERN Document Server

Garcia, Stephan Ramon; Ross, William T

2018-01-01

This monograph offers an introduction to finite Blaschke products and their connections to complex analysis, linear algebra, operator theory, matrix analysis, and other fields. Old favorites such as the Carathéodory approximation and the Pick interpolation theorems are featured, as are many topics that have never received a modern treatment, such as the Bohr radius and Ritt's theorem on decomposability. Deep connections to hyperbolic geometry are explored, as are the mapping properties, zeros, residues, and critical points of finite Blaschke products. In addition, model spaces, rational functions with real boundary values, spectral mapping properties of the numerical range, and the Darlington synthesis problem from electrical engineering are also covered. Topics are carefully discussed, and numerous examples and illustrations highlight crucial ideas. While thorough explanations allow the reader to appreciate the beauty of the subject, relevant exercises following each chapter improve technical fluency with t...

Ensembles and Experiments in Classical and Quantum Physics

Science.gov (United States)

Neumaier, Arnold

A philosophically consistent axiomatic approach to classical and quantum mechanics is given. The approach realizes a strong formal implementation of Bohr's correspondence principle. In all instances, classical and quantum concepts are fully parallel: the same general theory has a classical realization and a quantum realization. Extending the ''probability via expectation'' approach of Whittle to noncommuting quantities, this paper defines quantities, ensembles, and experiments as mathematical concepts and shows how to model complementarity, uncertainty, probability, nonlocality and dynamics in these terms. The approach carries no connotation of unlimited repeatability; hence it can be applied to unique systems such as the universe. Consistent experiments provide an elegant solution to the reality problem, confirming the insistence of the orthodox Copenhagen interpretation on that there is nothing but ensembles, while avoiding its elusive reality picture. The weak law of large numbers explains the emergence of classical properties for macroscopic systems.

Measurement of stopping powers of gases for heavy ions of 3 to 13 MeV by nucleon

International Nuclear Information System (INIS)

Orliange, I.

1985-09-01

The stopping powers of gases have been measured for incident 10 Ne, 18 Ar, 29 Cu, 36 Kr and 47 Ag ions of 3 to 13 MeV/u. These measurements have confirmed the existence of a gas-solid difference for the stopping powers (the stopping power of solids being larger than that of gazes). Such a difference was theoretically postulated by Bohr and Lindhard in 1954, and experimentally observed for the first time by Geissel in 1982. This effect can be qualitatively interpreted by a difference in the ion's effective charge in stopping power. However, the determination of charge state distribution for Ar and Fe ions in two particular cases (Ar + Nsub(2s)or Nsub(2g) and (Fe + Csub(s) or Csub(g)) from a theoric model and experimental cross sections for atomic collisions don't quantitatively account for observed differences [fr

Holistic aspects of quantum mechanics

International Nuclear Information System (INIS)

Pietschmann, H.

1987-01-01

Aspects of quantum mechanics irreconcilable with classical physics are outlined. Quantum mechanics started with a negative statement about reality, namely: it is impossible to determine momentum and position of a particle simultaneously. Meanwhile it has generated an impressive body of predictions which can be tested and have been confirmed by suitable experiments. As a consequence a naive, local, materialistic concept of reality must be abolished and a novel approach, the holistic is introduced. This is illustrated by some examples e.g. the Pauli exclusion principle for electrons, the electron capture decay of 135 La as a model of the wavefunction reduction, the Bohr radius of the atom, electron localisation in the atom. An example from the quantum field theory is the calculation of magnetic moments of electron and muon where a particle cannot be considered separately and all other particles must be taken into account. (G.Q.)

Semiclassical methods in field theories

International Nuclear Information System (INIS)

Ventura, I.

1978-10-01

A new scheme is proposed for semi-classical quantization in field theory - the expansion about the charge (EAC) - which is developed within the canonical formalism. This method is suitable for quantizing theories that are invariant under global gauge transformations. It is used in the treatment of the non relativistic logarithmic theory that was proposed by Bialynicki-Birula and Mycielski - a theory we can formulate in any number of spatial dimensions. The non linear Schroedinger equation is also quantized by means of the EAC. The classical logarithmic theories - both, the non relativistic and the relativistic one - are studied in detail. It is shown that the Bohr-Sommerfeld quantization rule(BSQR) in field theory is, in many cases, equivalent to charge quantization. This rule is then applied to the massive Thirring Model and the logarithmic theories. The BSQR can be see as a simplified and non local version of the EAC [pt

The Strange Friendship of Pauli and Jung - When Physics Met Psychology

CERN Multimedia

CERN. Geneva

2009-01-01

At a key time in his scientific development, Pauli was undergoing analysis by Jung. What can we learn about Pauli's discoveries of the exclusion principle and the CPT theorem, as well as his thoughts on non-conservation of parity, and his quest with Heisenberg for a unified field theory of elementary particles from Jung’s analysis of his dreams? A very different Pauli emerges, one at odds with esteemed colleagues such as Niels Bohr and Werner Heisenberg.

The statistic-thermodynamically calculations of magnetic thermodynamically functions for nuclear magnetic moments

International Nuclear Information System (INIS)

Zhu Zhenghe; Luo Deli; Feng Kaiming

2013-01-01

The present work is to calculate the magnetic thermodynamically functions, i.e. energy, the intensity of magnetization, enthalpy, entropy and Gibbs function for nuclear magnetic moments of T, D and neutron n at 2 T and 1, 50, 100 and 150 K from partition functions. It is shown that magnetic saturation of thermonuclear plasma does not easily occur for nuclear magneton is only of 10 -3 of Bohr magneton. The work done by magnetic field is considerable. (authors)

Electron Pathways through Erythrocyte Plasma Membrane in Human Physiology and Pathology: Potential Redox Biomarker?

OpenAIRE

Matteucci, Elena; Giampietro, Ottavio

2007-01-01

Erythrocytes are involved in the transport of oxygen and carbon dioxide in the body. Since pH is the influential factor in the Bohr-Haldane effect, pHi is actively maintained via secondary active transports Na+/H+ exchange and HC3 -/Cl- anion exchanger. Because of the redox properties of the iron, hemoglobin generates reactive oxygen species and thus, the human erythrocyte is constantly exposed to oxidative damage. Although the adult erythrocyte lacks protein synthesis and cannot restore dama...

Physiologically based indices of volumetric capnography in patients receiving mechanical ventilation.

Science.gov (United States)

Romero, P V; Lucangelo, U; Lopez Aguilar, J; Fernandez, R; Blanch, L

1997-06-01

Several indices of ventilatory heterogeneity can be identified from the expiratory CO2 partial pressure or CO2 elimination versus volume curves. The aims of this study were: 1) to analyse several computerizable indices of volumetric capnography in order to detect ventilatory disturbances; and 2) to establish the relationship between those indices and respiratory system mechanics in subjects with normal lungs and in patients with acute respiratory distress syndrome (ARDS), both receiving mechanical ventilation. We studied six normal subjects and five patients with early ARDS mechanically ventilated at three levels of tidal volume (VT). Respiratory system mechanics were assessed by end-expiratory and end-inspiratory occlusion methods, respectively. We determined Phase III slopes, Fletcher's efficiency index, Bohr's dead space (VD,Bohr/VT), and the ratio of alveolar ejection volume to tidal volume (VAE/VT) from expiratory capnograms, as a function of expired volume. Differences between normal subjects and ARDS patients were significant both for capnographic and mechanical parameters. Changes in VT significantly altered capnographic indices in normal subjects, but failed to change ventilatory mechanics and VAE/VT in ARDS patients. After adjusting for breathing pattern, VAE/VT exhibited the best correlation with the mechanical parameters. In conclusion, volumetric capnography, and, specifically, the ratio of alveolar ejection volume to tidal volume allows evaluation and monitoring of ventilatory disturbances in patients with adult respiratory distress syndrome.

Diving behaviour and haemoglobin function: the primary structure of the alpha- and beta-chains of the sea turtle (Caretta caretta) and its functional implications.

Science.gov (United States)

Petruzzelli, R; Aureli, G; Lania, A; Galtieri, A; Desideri, A; Giardina, B

1996-06-15

The amino acid sequence of the alpha- and beta-chains of haemoglobin (Hb) from the loggerhead sea turtle (Caretta caretta) has been determined. Comparison with that of human Hb shows differences in several residues involved in both alpha 1 beta 1 and alpha 1 beta 2 packing contacts. On the whole, in spite of the mutations, the essential characteristics of both interfaces seem to be maintained. The functional properties of the sea turtle Hb have been investigated at different temperatures and as a function of proton, chloride and organic phosphate concentrations. In addition to overall similarities shared with most of the vertebrate Hbs previously described, this molecule shows significant differences which could be related to the life behaviour of the turtle. In fact, while the shape of the Bohr-effect curve is well adapted for gas exchange during prolonged dives, the very small enthalpy change for O2 binding ensures that O2 delivery becomes essentially insensitive to the temperature changes of the environment. Moreover, and similarly to the case of emperor penguin Hb, the small alkaline Bohr effect appears to be only choride-linked, since the pH dependence of the O2 affinity is abolished in the absence of this ion. These functional characteristics are discussed on the basis of the primary structure of alpha- and beta-chains.

Generalization of the Greenberger-Horne-Zeilinger algebraic proof of nonlocality

International Nuclear Information System (INIS)

Clifton, R.K.; Redhead, M.L.G.; Butterfield, J.N.

1991-01-01

The authors further develop a recent new proof (by Greenberger, Horne, and Zeilinger - GHZ) that local deterministic hidden-variable theories are inconsistent with certain strict correlations predicted by quantum mechanics. First, they generalize GHZ's proof so that it applied to factorable stochastic theories in which apparatus hidden variables are casually relevant to measurement results, and theories in which the hidden variables evolve indeterministically prior to the particle-apparatus interactions. Then they adopt a more general measure-theoretic approach which requires that GHZ's argument be modified in order to produce a valid proof. Finally, they motivate the more general proof's assumptions in a somewhat different way from previous authors in order to strengthen the implications of the proof as much as possible. After developing GHZ's proof along these lines, they then consider the analogue, for their proof, of Bohr's reply to the EPR argument, and conclude (pace GHZ) that in at least one respect (viz, that of most concern to Bohr) the proof is no more powerful than Bell's. Nevertheless, they point out some new advantages of their proof over Bell's, and over other algebraic proofs of nonlocality. And they conclude by giving a modified version of their proof that, like Bell's does not rely on experimentally unrealizable strict correlations, but still leads to a testable quasi-algebraic locality inequality

Quantum communication and other quantum information technologies

CSIR Research Space (South Africa)

Roux, FS

2014-02-01

Full Text Available -Podolsky-Rosen Albert Einstein Boris Podolsky Nathan Rosen Quantum mechanics: measurements on one particle dictate the state of the other particle. Spontaneous decay Unstable particle x p ∆x ∆p – p. 4/41 Parametric down conversion One incoming photon→ Two outgoing... ⊲ Decay of entanglement in turbulence — Theory — Numerical simulations — Experimental results – p. 2/41 Quantum mechanics Neils Bohr Paul Dirac Erwin Schroedinger Werner Heisenberg Lasers Computers Microelectronics Transistors – p. 3/41 Einstein...

Fractional Schroedinger equation

International Nuclear Information System (INIS)

Laskin, Nick

2002-01-01

Some properties of the fractional Schroedinger equation are studied. We prove the Hermiticity of the fractional Hamilton operator and establish the parity conservation law for fractional quantum mechanics. As physical applications of the fractional Schroedinger equation we find the energy spectra of a hydrogenlike atom (fractional 'Bohr atom') and of a fractional oscillator in the semiclassical approximation. An equation for the fractional probability current density is developed and discussed. We also discuss the relationships between the fractional and standard Schroedinger equations

The uncertainty principle

International Nuclear Information System (INIS)

Martens, Hans.

1991-01-01

The subject of this thesis is the uncertainty principle (UP). The UP is one of the most characteristic points of differences between quantum and classical mechanics. The starting point of this thesis is the work of Niels Bohr. Besides the discussion the work is also analyzed. For the discussion of the different aspects of the UP the formalism of Davies and Ludwig is used instead of the more commonly used formalism of Neumann and Dirac. (author). 214 refs.; 23 figs

Quantum field theory with infinite component local fields as an alternative to the string theories

Science.gov (United States)

Krasnikov, N. V.

1987-09-01

We show that the introduction of the infinite component local fields with higher-order derivatives in the interaction makes the theory completely ultraviolet finite. For the γ5-anomalous theories the introduction of the infinite component field makes the theory renormalizable or even superrenormalizable. I am indebted to J. Ambjōrn, P. Di Vecchia, H.B. Nielsen and L. Rozhansky for useful discussions. It is a pleasure to thank the Niels Bohr Institute (Copenhagen) where this work was completed for kind hospitality.

Reconciling Through Science Exhibition Science Bringing Nations Together

CERN Multimedia

2000-01-01

Over 200 experiments are carried out now with the pulsed neutron reactor IBR-2. They involve physicists, biologists and chemists from the scientific centres of the JINR Member States and other countries. Major contributions are made by the physicists from Germany, Hungary, Poland, and Russia. During a visit to Dubna, Niels Bohr took an interest in a simple idea behind the periodic pulsed reactor and said: "I admire the courage of the people who ventured to build such a remarkable facility!"

EPR and Bell Locality

OpenAIRE

Norsen, Travis

2004-01-01

A new formulation of the EPR argument is presented, one which uses John Bell's mathematically precise local causality condition in place of the looser locality assumption which was used in the original EPR paper and on which Niels Bohr seems to have based his objection to the EPR argument. The new formulation of EPR bears a striking resemblance to Bell's derivation of his famous inequalities. The relation between these two arguments -- in particular, the role of EPR as part one of Bell's two-...

EPR: Some History and Clarification

Science.gov (United States)

Fine, Arthur

2002-04-01

Locality, separation and entanglement 1930s style. We’ll explore the background to the 1935 paper by Einstein, Podolsky and Rosen, how it was composed, the actual argument of the paper, the principles used, and how the paper was received by Schroedinger, and others.We’ll also look at Bohr’s response: the extent to which Bohr connects with what Einstein was after in EPR and the extent to EPR marks a shift in Bohr’s thinking about the quantum theory.

Polymerization of a divalent/tetravalent metal-storing atom-mimicking dendrimer

OpenAIRE

Albrecht, Ken; Hirabayashi, Yuki; Otake, Masaya; Mendori, Shin; Tobari, Yuta; Azuma, Yasuo; Majima, Yutaka; Yamamoto, Kimihisa

2016-01-01

The phenylazomethine dendrimer (DPA) has a layer-by-layer electron density gradient that is an analog of the Bohr atom (atom mimicry). In combination with electron pair mimicry, the polymerization of this atom-mimicking dendrimer was achieved. The valency of the mimicked atom was controlled by changing the chemical structure of the dendrimer. By mimicking a divalent atom, a one-dimensional (1D) polymer was obtained, and by using a planar tetravalent atom mimic, a 2D polymer was obtained. Thes...

EPR and Bell's theorem: A critical review

International Nuclear Information System (INIS)

Stapp, H.P.

1991-01-01

The argument of Einstein, Podolsky, and Rosen is reviewed with attention to logical structure and character of assumptions. Bohr's reply is discussed. Bell's contribution is formulated without use of hidden variables, and efforts to equate hidden variables to realism are critically examined. An alternative derivation of nonlocality that makes no use of hidden variables, microrealism, counterfactual definiteness, or any other assumption alien to orthodox quantum thinking is described in detail, with particular attention to the quartet or broken-square question

Directory of Researchers for Manpower, Personnel, Training, and Human Factors

Science.gov (United States)

1998-03-01

Cambridge, MA Bohres, G Naval Surface Warfare Center - Dahlgren Div 904-234-4184 Panama City, FL DSN:436-4184 Bowers, Clint A Dr Univ of Central...Research 703-696-4318 Arlington, VA DSN:426-4318 Clevenger, J Evans and Sutherland Computer Corp 801-588-1518 Salt Lake City, UT Clingerman, B Space and...Drew W. CAPT Bergondy, M Bilazarian, P Bowers, Clint A Dr Bradley, S Breaux, R Mr Burke, J Burns, Christopher M Mr Burns, J Cannon-Bowers, Janis A Dr

Timeless Approach to Quantum Jumps

Directory of Open Access Journals (Sweden)

Ignazio Licata

2015-10-01

Full Text Available According to the usual quantum description, the time evolution of the quantum state is continuous and deterministic except when a discontinuous and indeterministic collapse of state vector occurs. The collapse has been a central topic since the origin of the theory, although there are remarkable theoretical proposals to understand its nature, such as the Ghirardi–Rimini–Weber. Another possibility could be the assimilation of collapse with the now experimentally well established phenomenon of quantum jump, postulated by Bohr already in 1913. The challenge of nonlocality offers an opportunity to reconsider the quantum jump as a fundamental element of the logic of the physical world, rather than a subsidiary accident. We propose here a simple preliminary model that considers quantum jumps as processes of entry to and exit from the usual temporal domain to a timeless vacuum, without contradicting the quantum relativistic formalism, and we present some potential connections with particle physics. Quanta 2015; 4: 10–26.

The influence of the grain boundary structure on diffusional creep

International Nuclear Information System (INIS)

Thorsen, P.A.

1998-05-01

An experiment was carried out to quantify the deformation in the diffusional creep domain. It was found that material had indisputably been deposited at grain boundaries in tension. A characterisation of 131 boundaries in terms of their misorientation was carried out and this was correlated to the observed deformation. Twin boundaries below a certain limit of deviation from an exact twin misorientation were totally inactive in the deformation. A large qualitative difference was found in the way general boundaries take part in the deformation. The experiments have taken place at Materials Research Department, Risoe National Laboratory at Roskilde. The present thesis has been submitted in partial fulfillment of the requirements for the Ph.D. degree in physics at the Niels Bohr Institute, University of Copenhagen. Besides the results of the creep experiment the thesis contains a description of the theoretical background to diffusional creep models. Also, the results from an investigation of helium bubble formation in an irradiated copper sample is included. (au)

Theoretical nuclear fission: The evolution of the first fifty years

International Nuclear Information System (INIS)

Griffin, J.J.

1989-01-01

The evolution of the dynamical theory of nuclear fission is reviewed through four recognizable major phases. Its conceptual structure was from the outset shaped by the Bohr-Wheeler idea of the nucleus as a liquid drop. On the other hand, today's nuclear drop is a system which has under study repeatedly revealed remarkable and unexpected properties, especially with respect to the dependence of its energy upon its shape. Although some of these special properties arise from quantal effects, the theory of fission is still expressed largely in terms of classical dynamics. This situation leaves open the question whether our theoretical success flows entirely from physical truth or in part from the great phenomenological flexibility of the drop model. It leads one also to wonder whether in the next phase connections with the quantal many-body dynamics might finally find a firm place in the theory, and tie its predictions quantitatively to the deeper microscopic reality

Theory of superfluidity macroscopic quantum waves

International Nuclear Information System (INIS)

Ventura, I.

1978-10-01

A new description of superfluidity is proposed, based upon the fact that Bogoliubov's theory of superfluidity exhibits some so far unsuspected macroscopic quantum waves (MQWs), which have a topological nature and travel within the fluid at subsonic velocities. To quantize the bounded quasi-particles the field theoretic version of the Bohr-Sommerfeld quantization rule, is employed and also resort to a variational computation. In an instantaneous configuration the MQWs cut the condensate into blocks of phase, providing, by analogy with ferromagnetism, a nice explanation of what could be the lambda-transition. A crude estimate of the critical temperature gives T sub(c) approximately equal to 2-4K. An attempt is made to understand Tisza's two-fluid model in terms of the MQWs, and we rise the conjecture that they play an important role in the motion of second. We present also a qualitative prediction concerning to the behavior of the 'phononroton' peak below 1.0K, and propose two experiments to look for MQWs [pt

Energy loss straggling in Aluminium foils for Li and C ions in fractional energy loss limits (ΔE/E) ∼10-60%

Science.gov (United States)

Diwan, P. K.; Kumar, Sunil; Kumar, Shyam; Sharma, V.; Khan, S. A.; Avasthi, D. K.

2016-02-01

The energy loss straggling of Li and C ions in Al foils of various thicknesses has been measured, within the fractional energy loss limit (∆E/E) ∼ 10-60%. These measurements have been performed using the 15UD Pelletron accelerator facility available at Inter University Accelerator Centre (IUAC), New Delhi, India. The measured straggling values have been compared with the corresponding predicted values adopting popularly used collisional straggling formulations viz Bohr, Lindhard and Scharff, Bethe-Livingston, Titeica. In addition, the experimental data has been compared to the Yang et al. empirical formula and Close Form Model, recently proposed by Montanari et al. The straggling values derived by Titeica theory were found to be in better agreement with the measured values as compared to other straggling formulations. The charge-exchange straggling component has been estimated from the measured data based on Titeica's theory. Finally, a function of the ion effective charge and the energy loss fraction within the target has been fitted to the latter straggling component.

Alpha Particle Induced X-ray Emission in the Classroom

International Nuclear Information System (INIS)

Lopez, Jorge A.; Borunda, Mario F.; Morales, Jaime

2003-01-01

We report on an experimental demonstration in an introductory modern physics course to elucidate the X-ray line spectra, and how they arise from transitions of electrons to inner shells. We seek to determine the effect of limited use of an interactive component as a supplement to a traditional lecture, and how it would improve the student achievement. In this preliminary study the students were exposed to traditional lectures on X-ray production and Bohr's model, they then were given a homework on the abc of X-ray spectra, after which they were given a pre-test on the materials, followed by an in-class demonstration, and a final post-exam. The gain, as measured from pre- to post-exams appears to remark the differences in how students approached the subject before and after the use of the demonstration. This initial study shows the validity of in-class demonstrations as teaching tools and opens a wide new area of research in modern physics teaching

Learning and the variation in focus among physics students when using a computer simulation

Directory of Open Access Journals (Sweden)

Åke Ingerman

2012-07-01

Full Text Available This article presents a qualitative analysis of the essential characteristics of university students’ “focus of awareness” whilst engaged with learning physics related to the Bohr model with the aid of a computer simulation. The research is located within the phenomenographic research tradition, with empirical data comprising audio and video recordings of student discussions and interactions, supplemented by interviews. Analysis of this data resulted in descriptions of four qualitatively distinct focuses: Doing the Assignment, Observing the Presentation, Manipulating the Parameters and Exploring the Physics. The focuses are further elucidated in terms of students’ perceptions of learning and the nature of physics. It is concluded that the learning outcomes possible for the students are dependent on the focus that is adopted in the pedagogical situation. Implications for teaching physics using interactive-type simulations can be drawn through epistemological and meta-cognitive considerations of the kind of mindful interventions appropriate to a specific focus.

Fabrication and characterization of solid PbI2 nanocrystals

International Nuclear Information System (INIS)

Kasi, Gopi K; Dollahon, Norman R; Ahmadi, Temer S

2007-01-01

Lead iodide nanoparticles are synthesized in reverse micelle solution of AOT/H 2 O/n-heptane. Optical absorption spectra and TEM analysis indicated the formation of crystalline particles with an average radius of 1.5 nm, which is less than the Bohr radius of the exciton (1.9 nm) in bulk PbI 2 . Using theoretical models and optical spectra of quantum confined PbI 2 nanoparticles, a radius of 1.5 nm and a thickness of 1.7 nm was calculated, which are in full agreement with the TEM results. Particles were isolated from the dispersed medium and were analysed by powder XRD and Raman spectroscopy, indicating the formation of a predominantly 2H-PbI 2 polytype. This work presents the first case of fully isolated, fully characterized solid nanoparticles of PbI 2 . It also presents XRD and Raman spectrum for the first time for PbI 2 nanoparticles of intermediate quantum confinement

Communicating the Heisenberg uncertainty relations: Niels Bohr, Complementarity and the Einstein-Rupp experiments

NARCIS (Netherlands)

van Dongen, Jeroen|info:eu-repo/dai/nl/242629431

2015-01-01

The Einstein-Rupp experiments have been unduly neglected in the history of quantum mechanics. While this is to be explained by the fact that Emil Rupp was later exposed as a fraud and had fabricated the results, it is not justified, due to the importance attached to the experiments at the time. This

Mechanism of the Enhancement of the Bohr Effect in Mammalian Hemoglobins by Diphosphoglycerate

Science.gov (United States)

Riggs, Austen

1971-01-01

The number of protons released from several mammalian hemoglobins as a consequence of oxygenation is greater in the presence of low concentrations of 2,3-diphosphoglycerate than in its absence. A mechanism for this enhancement of proton release is proposed. The basis of this mechanism is that 2,3-diphosphoglycerate binds primarily between the protonated α-NH2 terminal groups of the two β chains in deoxyhemoglobin. This binding will shift the ionization equilibria in favor of the protonation of the deoxyhemoglobin. Partial release of 2,3-diphosphoglycerate upon oxygenation of the hemoglobin is then accompanied by a release of protons. The apparent enthalpy of diphosphoglycerate binding appears to be close to zero. The previously reported temperature dependence appears to be due entirely to the associated protonation reaction. If only a single diphosphoglycerate binding site is assumed, the intrinsic association constant is estimated to be 3.9 × 105 M-1 for deoxyhemoglobin and 1.05 × 104 M-1 for oxyhemoglobin at 20°C in 0.1 M NaCl. PMID:5289365

Mechanism of the enhancement of the Bohr effect in mammalian hemoglobins by diphosphoglycerate.

Science.gov (United States)

Riggs, A

1971-09-01

The number of protons released from several mammalian hemoglobins as a consequence of oxygenation is greater in the presence of low concentrations of 2,3-diphosphoglycerate than in its absence. A mechanism for this enhancement of proton release is proposed. The basis of this mechanism is that 2,3-diphosphoglycerate binds primarily between the protonated alpha-NH(2) terminal groups of the two beta chains in deoxyhemoglobin. This binding will shift the ionization equilibria in favor of the protonation of the deoxyhemoglobin. Partial release of 2,3-diphosphoglycerate upon oxygenation of the hemoglobin is then accompanied by a release of protons. The apparent enthalpy of diphosphoglycerate binding appears to be close to zero. The previously reported temperature dependence appears to be due entirely to the associated protonation reaction. If only a single diphosphoglycerate binding site is assumed, the intrinsic association constant is estimated to be 3.9 x 10(5) M(-1) for deoxyhemoglobin and 1.05 x 10(4) M(-1) for oxyhemoglobin at 20 degrees C in 0.1 M NaCl.

Competition between collective and single particle excitations in nuclear structure description

International Nuclear Information System (INIS)

Petrovici, A.N.

1983-01-01

The microscopic description of the quadrupole collective dynamics in even krypton isotopes is presented. A microscopic calculation of Bohr's collective Hamiltonian is used to describe the collective motion in 76 Kr. A single-particle basis calculated in a deformed Woods-Saxon potential leads to the potential energy surface obtained by the Strutinsky renormalization procedure, and to the inertial functions determined in the cranking model approximation. The collective Schroedinger equation is solved numerically to analyse the low-energy, even parity states in 76 Kr. A good agreement between experiment and theory is obtained without specifically adjusting any parameter in the model for this nucleus. Some results regarding statical and dynamical characteristics of sup(74,78,80)Kr isotopes are also presented. The asymmetric rotor model with admixture of two quasiparticles is used to describe the sup(66,68,70)Ge and the sup(64,66)Zn isotopes. The interplay of collective and single particle motions is further investigated by magnetic moment measurements using the method of integral angular correlations perturbed by recoil into gas. The results involve g-factor measurements for 166 Ho, 68 Ge, 64 Zn, 66 Zn and 68 Ga nuclei. Finally, a discussion of further possible improvements and more general developments of the problems under investigation is given. (author)

Density functional theory of electron transfer beyond the Born-Oppenheimer approximation: Case study of LiF

Science.gov (United States)

Li, Chen; Requist, Ryan; Gross, E. K. U.

2018-02-01

We perform model calculations for a stretched LiF molecule, demonstrating that nonadiabatic charge transfer effects can be accurately and seamlessly described within a density functional framework. In alkali halides like LiF, there is an abrupt change in the ground state electronic distribution due to an electron transfer at a critical bond length R = Rc, where an avoided crossing of the lowest adiabatic potential energy surfaces calls the validity of the Born-Oppenheimer approximation into doubt. Modeling the R-dependent electronic structure of LiF within a two-site Hubbard model, we find that nonadiabatic electron-nuclear coupling produces a sizable elongation of the critical Rc by 0.5 bohr. This effect is very accurately captured by a simple and rigorously derived correction, with an M-1 prefactor, to the exchange-correlation potential in density functional theory, M = reduced nuclear mass. Since this nonadiabatic term depends on gradients of the nuclear wave function and conditional electronic density, ∇Rχ(R) and ∇Rn(r, R), it couples the Kohn-Sham equations at neighboring R points. Motivated by an observed localization of nonadiabatic effects in nuclear configuration space, we propose a local conditional density approximation—an approximation that reduces the search for nonadiabatic density functionals to the search for a single function y(n).

Our (Represented) World: A Quantum-Like Object

Science.gov (United States)

Lambert-Mogiliansky, Ariane; Dubois, François

It has been suggested that observed cognitive limitations may be an expression of the quantum-like structure of the mind. In this chapter we explore some implications of this hypothesis for learning i.e., for the construction of a representation of the world. For a quantum-like individual, there exists a multiplicity of mentally incompatible (Bohr complementary) but equally valid and complete representations (mental pictures) of the world. The process of learning i.e., of constructing a representation, involves two kinds of operations on the mental picture. The acquisition of new data which is modelled as a preparation procedure and the processing of data which is modelled as an introspective measurement operation. This process is shown not to converge to a single mental picture. Rather, it can evolve forever. We define a concept of entropy to capture relative intrinsic uncertainty. The analysis suggests a new perspective on learning. First, it implies that we must turn to double objectification as in Quantum Mechanics: the cognitive process is the primary object of learning. Second, it suggests that a representation of the world arises as the result of creative interplay between the mind and the environment.

Dynamic plasma screening effects on electron capture process in hydrogenic ion fully stripped ion collisions in dense plasmas

International Nuclear Information System (INIS)

Jung, Y.

1997-01-01

In dense plasmas, dynamic plasma screening effects are investigated on electron capture from hydrogenic ions by past fully stripped ions. The classical Bohr Lindhard model has been applied to obtain the electron capture probability. The interaction potential in dense plasmas is represented in terms of the longitudinal dielectric function. The classical straight-line trajectory approximation is applied to the motion of the projectile ion in order to visualize the electron capture probability as a function of the impact parameter, projectile energy, and plasma parameters. The electron capture probability including the dynamic plasma screening effect is always greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity, the dynamic polarization screening effect becomes the static plasma screening effect. When the projectile velocity is greater than the plasma electron thermal velocity, the interaction potential is almost unshielded. The difference between the dynamic and static plasma screening effects is more significant for low energy projectiles. It is found that the static screening formula obtained by the Debye Hueckel model overestimates the plasma screening effects on the electron capture processes in dense plasmas. copyright 1997 American Institute of Physics

Nuclear and atomic physics governing changes in the composition of relativistic cosmic rays

International Nuclear Information System (INIS)

Wilson, L.W.

1978-05-01

Many quantitative studies of relativistic cosmic ray propagation exist in which ''standard'' values for the input quantities are adopted in an uncritical manner. In contrast, the major emphasis of this study is on developing the proper set of formulae and error estimates for each of the atomic and nuclear processes that govern the composition of the cosmic rays between lithium and nickel. In particular, it is shown that errors of approximately a factor of two exist in the standard (Bohr) cross sections for stripping, that the correction function from high energy photoionization needs to be introduced into the standard cross section for radiative attachment, and that because the half-life of a fast nucleus with at most one K-shell electron can differ from the half-life of a neutral atom, several laboratory-based values need correction. The framework used to assemble and correct these quantities is a matrix formalism for the leaky box model similar to that used by Cowsik and Wilson in their ''nested leaky box'' model. It is shown that once the assumption of species-independent leakage is introduced, the matrix formalism becomes virtually identical with the standard exponential path length formalism. 87 references

IAEA Theory Summary 1998 IAEA Meeting, Yokohama, Japan - Oct. 17-24, 1998

International Nuclear Information System (INIS)

Tang, W.M.

2000-01-01

This is a summary of the advances in magnetic fusion energy theory research presented at the 17th International Atomic Energy Agency Fusion Energy Conference from 17--24 October, 1998 in Yokohama, Japan. Theory and simulation results from this conference provided encouraging evidence of significant progress in understanding the physics of thermonuclear plasmas. Indeed, the grand challenge for this field is to acquire the basic understanding that can readily enable the innovations which would make fusion energy practical. In this sense, as depicted in Fig. 1, research in fusion energy is increasingly able to be categorized as fitting well the ''Pasteur's Quadrant'' paradigm, where the research strongly couples basic science (''Bohr's Quadrant'') to technological impact (''Edison's Quadrant''). As supported by some of the work presented at this conference, this trend will be further enhanced by advanced simulations. Eventually, realistic three-dimensional modeling capabilities, when properly combined with rapid and complete data interpretation of results from both experiments and simulations, can contribute to a greatly enhanced cycle of understanding and innovation. Plasma science theory and simulation have provided reliable foundations for this improved modeling capability, and the exciting advances in high-performance computational resources have further accelerated progress

Conformal maps and group contractions in nuclear structure

International Nuclear Information System (INIS)

Bonatsos, D.

2011-01-01

In mathematics, a conformal map is a function which preserves angles. We show how this procedure can be used in the framework of the Bohr Hamiltonian, leading to a Hamiltonian in a curved space, in which the mass depends on the nuclear deformation β, while it remains independent of the collective variable γ and the three Euler angles. This Hamiltonian is proved to be equivalent to that obtained using techniques of Supersymmetric Quantum Mechanics. Group contraction is a procedure in which a symmetry group is reduced into a group of lower symmetry in a certain limiting case. Examples are provided in the large boson number limit of the Interacting Boson Approximation (IBA) model by a) the contraction of the SU(3) algebra into the [R 5 ]SO(3) algebra of the rigid rotator, consisting of the angular momentum operators forming SO(3), plus 5 mutually commuting quantities, the quadrupole operators, b) the contraction of the O(6) algebra into the [R 5 ]SO(5) algebra of the γ-unstable rotator. We show how contractions can be used for constructing symmetry lines in the interior of the symmetry triangle of the IBA model. (author)

George de Hevesy

International Nuclear Information System (INIS)

Levi, H.

1985-01-01

George de Hevesy (1875-1966) worked with Rutherford in Manchester in the early 1900's and with Niels Bohr in Denmark after the first world war. With Coster he discovered an unknown element, later named Hafrivm. In the 1930's he moved to Copenhagen and developed radiotracer techniques using the new artificially produced radioisotopes. This work found wide application in medicine and biology and other branches of science and technology and for his pioneer work de Hevesy was awarded a Nobel Prize in 1944. (UK)

In search of Schroedinger's cat

International Nuclear Information System (INIS)

Gribbin, John.

1984-01-01

The book explains how the paradox of Schroedinger's cat led to an understanding of reality in quantum physics. The contents of the book is divided into three parts. Part one concerns light, atoms and Bohr's atom. Quantum mechanics is discussed in Part Two, including photons and electrons, matrices and waves, and applications of quanta. The last part deals with chance and uncertainty, paradoxes and possibilities, the experimental proof of the paradoxical reality of the quantum world, and the many-worlds interpretation of quantum mechanics. (U.K.)

Heisenberg, his wife s account

International Nuclear Information System (INIS)

Heisenberg, E.

1990-01-01

A wife tells about her husband life, Werner Heisenberg, Physics Nobel Price in 1932. After a happy childhood, this brilliant student was Albert Einstein, Niels Bohr, Arnold Sommerfeld s student. But at the nazism time, the great physician refused to leave his country, guaranteeing the Hitler regime and taking part in effort of war, that is to say the run to the bomb. The account of Elisabeth Heisenberg, although subjective, allows to understand the scientist s behaviour face terrifying realities of his time. (N.C.)

History of Science Web Resources at American Institute of Physics

Science.gov (United States)

Good, G. A.

2009-12-01

The Center for History of Physics and the associated Niels Bohr Library & Archives at the American Institute of Physics were pioneers in web resource development for education and for research in the 1990s. While these units of AIP continue to add significantly to the traditional ways of putting content before the public, they are also experimenting with blogs and Facebook, and are looking at other forms of interactive web presence. This talk explores how an active research center is trying to do both.

Genomic organization and evolution of the Atlantic salmon hemoglobin repertoire

Directory of Open Access Journals (Sweden)

Phillips Ruth B

2010-10-01

Full Text Available Abstract Background The genomes of salmonids are considered pseudo-tetraploid undergoing reversion to a stable diploid state. Given the genome duplication and extensive biological data available for salmonids, they are excellent model organisms for studying comparative genomics, evolutionary processes, fates of duplicated genes and the genetic and physiological processes associated with complex behavioral phenotypes. The evolution of the tetrapod hemoglobin genes is well studied; however, little is known about the genomic organization and evolution of teleost hemoglobin genes, particularly those of salmonids. The Atlantic salmon serves as a representative salmonid species for genomics studies. Given the well documented role of hemoglobin in adaptation to varied environmental conditions as well as its use as a model protein for evolutionary analyses, an understanding of the genomic structure and organization of the Atlantic salmon α and β hemoglobin genes is of great interest. Results We identified four bacterial artificial chromosomes (BACs comprising two hemoglobin gene clusters spanning the entire α and β hemoglobin gene repertoire of the Atlantic salmon genome. Their chromosomal locations were established using fluorescence in situ hybridization (FISH analysis and linkage mapping, demonstrating that the two clusters are located on separate chromosomes. The BACs were sequenced and assembled into scaffolds, which were annotated for putatively functional and pseudogenized hemoglobin-like genes. This revealed that the tail-to-tail organization and alternating pattern of the α and β hemoglobin genes are well conserved in both clusters, as well as that the Atlantic salmon genome houses substantially more hemoglobin genes, including non-Bohr β globin genes, than the genomes of other teleosts that have been sequenced. Conclusions We suggest that the most parsimonious evolutionary path leading to the present organization of the Atlantic salmon

Genomic organization and evolution of the Atlantic salmon hemoglobin repertoire

Science.gov (United States)

2010-01-01

Background The genomes of salmonids are considered pseudo-tetraploid undergoing reversion to a stable diploid state. Given the genome duplication and extensive biological data available for salmonids, they are excellent model organisms for studying comparative genomics, evolutionary processes, fates of duplicated genes and the genetic and physiological processes associated with complex behavioral phenotypes. The evolution of the tetrapod hemoglobin genes is well studied; however, little is known about the genomic organization and evolution of teleost hemoglobin genes, particularly those of salmonids. The Atlantic salmon serves as a representative salmonid species for genomics studies. Given the well documented role of hemoglobin in adaptation to varied environmental conditions as well as its use as a model protein for evolutionary analyses, an understanding of the genomic structure and organization of the Atlantic salmon α and β hemoglobin genes is of great interest. Results We identified four bacterial artificial chromosomes (BACs) comprising two hemoglobin gene clusters spanning the entire α and β hemoglobin gene repertoire of the Atlantic salmon genome. Their chromosomal locations were established using fluorescence in situ hybridization (FISH) analysis and linkage mapping, demonstrating that the two clusters are located on separate chromosomes. The BACs were sequenced and assembled into scaffolds, which were annotated for putatively functional and pseudogenized hemoglobin-like genes. This revealed that the tail-to-tail organization and alternating pattern of the α and β hemoglobin genes are well conserved in both clusters, as well as that the Atlantic salmon genome houses substantially more hemoglobin genes, including non-Bohr β globin genes, than the genomes of other teleosts that have been sequenced. Conclusions We suggest that the most parsimonious evolutionary path leading to the present organization of the Atlantic salmon hemoglobin genes involves

Excitonic effects and related properties in semiconductor nanostructures: roles of size and dimensionality

Science.gov (United States)

Wu, Shudong; Cheng, Liwen; Wang, Qiang

2017-08-01

The size- and dimensionality-dependence of excitonic effects and related properties in semiconductor nanostructures are theoretically studied in detail within the effective-mass approximation. When nanostructure sizes become smaller than the bulk exciton Bohr radius, excitonic effects are significantly enhanced with reducing size or dimensionality. This is as a result of quantum confinement in more directions leading to larger exciton binding energies and normalized exciton oscillator strengths. These excitonic effects originate from electron-hole Coulombic interactions, which strongly enhance the oscillator strength between the electron and hole. It is also established that the universal scaling of exciton binding energy versus the inverse of the exciton Bohr radius follows a linear scaling law. Herein, we propose a stretched exponential law for the size scaling of optical gap, which is in good agreement with the calculated data. Due to differences in the confinement dimensionality, the radiative lifetime of low-dimensional excitons becomes shorter than that of bulk excitons. The size dependence of the exciton radiative lifetimes is in good agreement with available experimental data. This strongly enhanced electron-hole exchange interaction is expected in low-dimensional structures due to enriched excitonic effects. The main difference in nanostructures compared to the bulk can be interpreted in terms of the enhanced excitonic effects induced by exciton localization. The enhanced excitonic effects are expected to be of importance in developing stable and high-efficiency nanoscale excitonic optoelectronic devices.

Participants of the 5th Solvay Congress

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Benjamin Croupie, Bruxelles

1927-01-01

1st line. l.to r. : I Langmeir, M Planck, M Curie, H A Lorentz, A Einstein, P Langevin, Ch E Guye, C T R Wilson, O W Richardson 2nd line l.to r. : P Debye, M Knudesen, W L Bragg, H A Kramers, P A M Dirac, A H Compton, L V De Broglie, M Born, N Bohr3rd line, l. to r. : A Piccard, E Henriot, P ehrenfest, E Herzen, Th De Donder, E Schroendinger, E Verschaffelt, W Pauli, w Heisenberg, R H Fowler

Denotational World-indexed Logical Relations and Friends

DEFF Research Database (Denmark)

Thamsborg, Jacob Junker

and solve the fundamental type-worlds circularity by metric-space theory. This approach scales to state-of-theart step-indexed techniques and permits unrestricted relational reasoning by the use of so-called Bohr relations. Along the way, we develop auxiliary theory; most notably a generalized version...... of separation logic with assertion variables. In particular, we give criteria for when standard, unary separation logic proofs lift to the binary setting. Phrased dierently, given a module-dependent client and a standard separation logic proof of its correctness, we ponder the default question of representation...

Can Yin-Yang Guide Chinese Indigenous Management Research?

DEFF Research Database (Denmark)

Li, Xin

2014-01-01

: Chinese Yin-Yang philosophy, Hegel's dialectic, and Niels Bohr's complementarity principle, as well as Aristotle's formal (either/or) logic. I show that the four logical systems have differences and similarities and show that Westerners can and do think dialectically. I also argue that Chinese Yin......-Yang philosophy, while useful and powerful in some situations, is not always superior to the other logical systems and philosophies. My purpose is to alert Chinese management scholars to the dangers of overconfidence and to stimulate discussion and debate on the true value of Yin-Yang in particular...

La gamba di Tamerlano. Contestualizzazione del sintomo e prospettiva metaculturale nell’etnopsichiatria di Georges Devereux

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Viola Carofalo

2014-06-01

Full Text Available The aim of the reflection of Georges Devereux is the establishment of a therapeutic practice in the ethnopsychiatric field, based on the complementary idea of the Danish mathematician Niels Bohr. This article will show how Devereux applies this principle to the studies on mental illness suffered by the Plains Indian during the mid-fifties, using his skills in the fields of anthropology and psychoanalysis. It will give a special attention to the case of Jimmy Picard, the main character of the famous essay Reality and dream: Psychotherapy of a Plains Indian.

Haphazard Reality Half a Century of Science

CERN Document Server

Casimir, HBG

2010-01-01

Casimir, himself a famous physician, studied and worked with three great physicists of the twentieth century: Niels Bohr, Wolfgang Pauli and Paul Ehrenfest. In his autobiography, the brilliant theoretician lets the reader witness the revolution that led to quantum physics, whose influence on modern society turned out to be many times larger than the first atomic physicists could have imagined. Through his involvement in the technical-scientific and the business aspects of physics, through management positions at Philips Research Laboratory and as a member of the Board of Directors of Philips,

Field Induced Magnetic Moments in a Metastable Iron-Mercury Alloy

DEFF Research Database (Denmark)

Pedersen, M.S.; Mørup, Steen; Linderoth, Søren

1996-01-01

The magnetic properties of a metastable iron-mercury alloy have been investigated in the temperature range from 5 to 200 K by Mossbauer spectroscopy and magnetization measurements. At low temperature the magnetic moment per iron atom is larger than af alpha-Fe. The effective spontaneous magnetic ....... It was found that the field-induced increase of the magnetic moment in the metastable iron-mecury alloy was about 0.06 Bohr magnetons per iron atom in the temperature range from 5 to 200 K for a field change from 6 to 12 T....