465 research outputs found

    Validation of a New Ramping Aerobic Exercise Protocol (NDKS) in Overweight, Obese, and Normal Weight Individuals

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    International Journal of Exercise Science 15(4): 386-398, 2022. The research purpose was to establish reliability and validity of determining VO2max via a new NDKS (Nustad Dressler Kobes Saghiv; named for the sir names of department faculty at the time) ramping protocol compared to the Standard Bruce protocol in normal weight, overweight, and obese individuals. Forty-two physically active participants (23M, 19F) ages 18-28 years were grouped into normal weight (N = 15, 8F, BMI 18.5-24.9 kg/m2), overweight (N = 27, 11F, BMI = 25-29.9 kg/m2), and Class I obese (N = 7, 1F, BMI = 30-34.9 kg/m2). Blood pressure, heart rate, blood lactate, respiratory exchange ratio, test duration, rate of perceived exertion, and preference via survey were analyzed during each test. Test-retest reliability of the NDKS was determined first, via tests scheduled one week apart. The NDKS was then validated by comparison with results of the Standard Bruce protocol; tests also conducted one week apart. The normal weight group’s Cronbach’s Alpha was .995 for absolute VO2max (L/min) and .968 for relative VO2max (mL/kg.min). Overweight/obese Cronbach’s Alpha for absolute VO2max (L/min) was .960 and for relative VO2max (mL/kg.min) .908. Relative VO2max was slightly higher with NDKS and test time lower compared to the Bruce (p \u3c .05). 92.3% of subjects identified more localized muscle fatigue with the Bruce protocol vs NDKS. The NDKS is a reliable and valid exercise test which can be used to determine VO2max in physically active, young normal weight, overweight and obese individuals

    Reichenbach's Common Cause Principle in Algebraic Quantum Field Theory with Locally Finite Degrees of Freedom

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    In the paper it will be shown that Reichenbach's Weak Common Cause Principle is not valid in algebraic quantum field theory with locally finite degrees of freedom in general. Namely, for any pair of projections A and B supported in spacelike separated double cones O(a) and O(b), respectively, a correlating state can be given for which there is no nontrivial common cause (system) located in the union of the backward light cones of O(a) and O(b) and commuting with the both A and B. Since noncommuting common cause solutions are presented in these states the abandonment of commutativity can modulate this result: noncommutative Common Cause Principles might survive in these models

    In defense of the epistemic view of quantum states: a toy theory

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    We present a toy theory that is based on a simple principle: the number of questions about the physical state of a system that are answered must always be equal to the number that are unanswered in a state of maximal knowledge. A wide variety of quantum phenomena are found to have analogues within this toy theory. Such phenomena include: the noncommutativity of measurements, interference, the multiplicity of convex decompositions of a mixed state, the impossibility of discriminating nonorthogonal states, the impossibility of a universal state inverter, the distinction between bi-partite and tri-partite entanglement, the monogamy of pure entanglement, no cloning, no broadcasting, remote steering, teleportation, dense coding, mutually unbiased bases, and many others. The diversity and quality of these analogies is taken as evidence for the view that quantum states are states of incomplete knowledge rather than states of reality. A consideration of the phenomena that the toy theory fails to reproduce, notably, violations of Bell inequalities and the existence of a Kochen-Specker theorem, provides clues for how to proceed with this research program.Comment: 32 pages, REVTEX, based on a talk given at the Rob Clifton Memorial Conference, College Park, May 2003; v2: minor modifications throughout, updated reference

    Bipartite Mixed States of Infinite-Dimensional Systems are Generically Nonseparable

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    Given a bipartite quantum system represented by a tensor product of two Hilbert spaces, we give an elementary argument showing that if either component space is infinite-dimensional, then the set of nonseparable density operators is trace-norm dense in the set of all density operators (and the separable density operators nowhere dense). This result complements recent detailed investigations of separability, which show that when both component Hilbert spaces are finite-dimensional, there is a separable neighborhood (perhaps very small for large dimensions) of the maximally mixed state.Comment: 5 pages, RevTe

    Electron-lattice relaxation, and soliton structures and their interactions in polyenes

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    Density matrix renormalisation group calculations of a suitably parametrised model of long polyenes (polyacetylene oligomers), which incorporates both long range Coulomb interactions and adiabatic lattice relaxation, are presented. The triplet and 2Ag states are found to have a 2-soliton and 4-soliton form, respectively, both with large relaxation energies. The 1Bu state forms an exciton-polaron and has a very small relaxation energy. The relaxed energy of the 2Ag state lies below that of the 1Bu state. The soliton/anti-soliton pairs are bound.Comment: RevTeX, 5 pages, 4 eps figures included using epsf. To appear in Physical Review Letters. Fig. 1 fixed u

    Magnetic properties of a new molecular-based spin-ladder system: (5IAP)2CuBr4*2H2O

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    We have synthesized and characterized a new spin-1/2 Heisenberg antiferromagnetic ladder: bis 5-iodo-2-aminopyridinium tetrabromocuprate(II) dihydrate. X-ray diffraction studies show the structure of the compound to consist of well isolated stacked ladders and the interaction between the Cu(2+) atoms to be due to direct Br...Br contacts. Magnetic susceptibility and magnetization studies show the compound to be in the strong-coupling limit, with the interaction along the rungs (J' ~ 13 K) much greater than the interaction along the rails (J ~ 1 K). Magnetic critical fields are observed near 8.3 T and 10.4 T, respectively, establishing the existence of the energy gap.Comment: 10 pages, 4 figures, submitted to Phys. Rev. B Figure 4 did not print. *.eps files replaced with figures.ps fil

    AQFT from n-functorial QFT

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    There are essentially two different approaches to the axiomatization of quantum field theory (QFT): algebraic QFT, going back to Haag and Kastler, and functorial QFT, going back to Atiyah and Segal. More recently, based on ideas by Baez and Dolan, the latter is being refined to "extended" functorial QFT by Freed, Hopkins, Lurie and others. The first approach uses local nets of operator algebras which assign to each patch an algebra "of observables", the latter uses n-functors which assign to each patch a "propagator of states". In this note we present an observation about how these two axiom systems are naturally related: we demonstrate under mild assumptions that every 2-dimensional extended Minkowskian QFT 2-functor ("parallel surface transport") naturally yields a local net. This is obtained by postcomposing the propagation 2-functor with an operation that mimics the passage from the Schroedinger picture to the Heisenberg picture in quantum mechanics. The argument has a straightforward generalization to general pseudo-Riemannian structure and higher dimensions.Comment: 39 pages; further examples added: Hopf spin chains and asymptotic inclusion of subfactors; references adde

    Excited states of linear polyenes

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    We present density matrix renormalisation group calculations of the Pariser- Parr-Pople-Peierls model of linear polyenes within the adiabatic approximation. We calculate the vertical and relaxed transition energies, and relaxed geometries for various excitations on long chains. The triplet (3Bu+) and even- parity singlet (2Ag+) states have a 2-soliton and 4-soliton form, respectively, both with large relaxation energies. The dipole-allowed (1Bu-) state forms an exciton-polaron and has a very small relaxation energy. The relaxed energy of the 2Ag+ state lies below that of the 1Bu- state. We observe an attraction between the soliton-antisoliton pairs in the 2Ag+ state. The calculated excitation energies agree well with the observed values for polyene oligomers; the agreement with polyacetylene thin films is less good, and we comment on the possible sources of the discrepencies. The photoinduced absorption is interpreted. The spin-spin correlation function shows that the unpaired spins coincide with the geometrical soliton positions. We study the roles of electron-electron interactions and electron-lattice coupling in determining the excitation energies and soliton structures. The electronic interactions play the key role in determining the ground state dimerisation and the excited state transition energies.Comment: LaTeX, 15 pages, 9 figure

    Hyperentangled States

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    We investigate a new class of entangled states, which we call 'hyperentangled',that have EPR correlations identical to those in the vacuum state of a relativistic quantum field. We show that whenever hyperentangled states exist in any quantum theory, they are dense in its state space. We also give prescriptions for constructing hyperentangled states that involve an arbitrarily large collection of systems.Comment: 23 pages, LaTeX, Submitted to Physical Review

    The paradigm of the area law and the structure of transversal and longitudinal lightfront degrees of freedom

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    It is shown that an algebraically defined holographic projection of a QFT onto the lightfront changes the local quantum properties in a very drastic way. The expected ubiquitous vacuum polarization characteristic of QFT is confined to the lightray (longitudinal) direction, whereas operators whose localization is transversely separated are completely free of vacuum correlations. This unexpected ''transverse return to QM'' combined with the rather universal nature of the strongly longitudinal correlated vacuum correlations (which turn out to be described by rather kinematical chiral theories) leads to a d-2 dimensional area structure of the d-1 dimensional lightfront theory. An additive transcription in terms of an appropriately defined entropy related to the vacuum restricted to the horizon is proposed and its model independent universality aspects which permit its interpretation as a quantum candidate for Bekenstein's area law are discussed. The transverse tensor product foliation structure of lightfront degrees of freedom is essential for the simplifying aspects of the algebraic lightcone holography. Key-words: Quantum field theory; Mathematical physics, Quantum gravityComment: 16 pages latex, identical to version published in JPA: Math. Gen. 35 (2002) 9165-918
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