We generalize Bell's inequalities to biparty systems with continuous quantum variables. This is achieved by introducing the Bell operator in perfect analogy to the usual spin- 1/2 systems. It is then demonstrated that two-mode squeezed vacuum states display quantum nonlocality by using the generalized Bell operator. In particular, the original Einstein-Podolsky-Rosen states, which are the limiting case of the two-mode squeezed vacuum states, can maximally violate Bell's inequality due to Clauser, Horne, Shimony, and Holt. The experimental aspect of our scheme is briefly considered.

Epoxyeicosatrienoic acids (EETs) are released from endothelial cells and potently dilate small arteries by hyperpolarizing vascular myocytes. In the present study, we investigated the structural specificity of EETs in dilating canine and porcine coronary microvessels (50-140 microm ID) and activating large-conductance Ca2+-activated K+ (BK(Ca)) channels. The potencies and efficacies of EET regioisomers and enantiomers were compared with those of two EET homologs: epoxyeicosaquatraenoic acids (EEQs), which are made from eicosapentaenoic acid by the same cytochrome P-450 epoxygenase that generates EETs from arachidonic acid, and epoxydocosatetraenoic acids (EDTs), which are EETs that are two carbons longer. With EC50 values of 3-120 pM but without regio- or stereoselectivity, EETs potently dilated canine and porcine microvessels. Surprisingly, the EEQs and EDTs had comparable potencies and efficacies in dilating microvessels. Moreover, 50 nM 13,14-EDT activated the BK(Ca) channels with the same efficacy as either 11,12-EET enantiomer at 50 nM. We conclude that coronary microvessels and BK(Ca) channels possess low structural specificity for EETs and suggest that EEQs and EDTs may thereby also be endothelium-derived hyperpolarizing factors.

A laboratory test was undertaken to evaluate the interfacial frictional characteristics of cortical and cancellous bone, as well as a novel porous tantalum biomaterial (Hedrocel ® , Implex Corp.). Three sets of tests were conducted to measure the friction coefficients of (1) bovine cancellous bone against bovine cortical bone; (2) net-shape formed porous tantalum against bovine cortical and cancellous bone; and (3) electron-discharge-machine formed (EDM'd) porous tantalum against bovine cortical and cancellous bone. The bovine cortical bone was tested in three conditions: periosteum-intact, periosteum-denuded and surface-flattened. An inclined plane apparatus was used to determine the coefficients of friction. By gradually increasing the substrate tilt, the angle of slippage was determined, and the friction coefficient was calculated.The average friction coefficients of cancellous bone against periosteum-intact, periosteum-denuded and surface-flattened cortical bone were 0.91 ± 0.14, 0.61 ± 0.07 and 0.58 ± 0.06, respectively. Porous tantalum specimens prepared from a preshaped vitreous carbon skeleton, when tested against periosteum-intact, periosteum-denuded and surface-flattened cortical bone, and against cancellous bone, had average friction coefficients of 1.10 ± 0.18, 0.82 ± 0.15, 0.86 ± 0.11, and 0.98 ± 0.17, respectively. Porous tantalum specimens prepared by electron-discharge machining, when tested against periosteum-intact cortical bone, periosteum-denuded cortical bone and cancellous bone, had average friction coefficients of 1.75 ± 0.33, 0.74 ± 0.07, and 0.88 ± 0.09, respectively. The friction coefficient of the porous tantalum material was very high in comparison to natural bone autografts or allografts, and to conventional orthopedic implant coating materials (sintered beads and wire mesh). Other factors being equal, this high-friction characteristic would be expected to translate into higher initial stability of a porous tantalum implant, as compared to natural bone grafts.

A 3-setting Bell-type inequality enforced by the indeterminacy relation of complementary local observables is proposed as an experimental test of the 2-qubit entanglement. The proposed inequality has an advantage of being a sufficient and necessary criterion of the separability. Therefore any entangled 2-qubit state cannot escape the detection by this kind of tests. It turns out that the orientation of the local testing observables plays a crucial role in our perfect detection of the entanglement.PACS numbers: 03.67. Mn, 03.65.Ud, 03.65.Ta The entanglement or the quantum correlation has become a key concept in the nowadays quantum mechanics. From a fundamental point of view the entangled states of two spacelike separated quantum systems give rise to the question of the completeness of quantum mechanics starting with Einstein-Podolsky-Rosen paper [1] and culminating in Bell's theorem [2]. Form a practical point of view the entanglement has found numerous applications in the quantum information such as quantum computation and quantum teleportation [3,4]. A practical question arises as to how we can detect the entanglement experimentally.As is well known, the entangled states of a bipartite system are states that cannot be prepared locally. More precisely, entangled states are not classically correlated states, i.e, separable states which are convex combinations of product states. The entanglement, though simply defined, is notoriously difficult to detect from both the mathematical and physical point of view. There are plenty separability criteria for the separability of bipartite systems [5,6,7,8], among which the Peres-Horodecki (PH) partial transpose criterion [5,6] is an operationalfriendly criterion and the Bell inequality distinguishes itself as an experimentally doable test for the entanglement.Initially, Bell's inequalities and its generalizations aimed at ruling out various kinds of local realistic theories quantitatively, providing a sufficient and necessary condition for the existence of local hidden variable model in the case of two settings [9,10,11]. Since any separable state admits a local hidden variable model it obeys the Bell inequality. For all separable states of two qubits the Bell-Clauser-Horne-Shimony-Holt inequality [12]holds true. Here A i = a i · σ and B i = b i · τ (i = 1, 2) are two arbitrary sets of local testing observables with σ and τ being the Pauli matrices for two qubits respectively; the norms of the real vectors a i , b i are less than or equal to 1; AB ρ = Tr(ρAB) denotes the average of the observable AB in the state ρ as usual. Since the Bell inequality can be viewed as a property of separable states, it provides a sufficient criterion for the entanglement. One needs only choose properly the testing observables such that the above inequality is violated in order to ensure an entangled states. For multi particles the generalization of the Bell inequalities can be employed to detect the totally separable states [13,14] and fully entangled states [15,16,17], and to classify th...

It is shown that the Greenberger-Horne-Zeilinger theorem can be generalized to the case with only two entangled particles. The reasoning makes use of two photons which are maximally entangled both in polarization and in spatial degrees of freedom. In contrast to Cabello's argument of "all versus nothing" nonlocality with four photons [Phys. Rev. Lett. 87, 010403 (2001)], our proposal to test the theorem can be implemented with linear optics and thus is well within the reach of current experimental technology.PACS numbers: 03.65. Ud, 03.65.Ta, Bell's theorem [1], which is derived from Einstein, Podolsky, and Rosen's (EPR's) notion of local realism [2], represents the most radical departure of quantum mechanics (QM) from one's classical intuitions. On the one hand, Bell's inequalities (BI) state that certain statistical correlations predicted by QM for measurements on two-particle ensembles cannot be understood within a realistic picture based on local properties of each individual particle. On the other hand, an unstatisfactory feature in the derivation of BI is that such a local realistic and thus classical picture can explain perfect correlations and is only in conflict with statistical prediction of the theory.Strikingly, "Bell's theorem without inequalities" has been demonstrated for multiparticle Greenberger-HorneZeilinger (GHZ) states [3,4,5], where the contradiction between QM and local realistic theories arises even for definite predictions. The quantum nonlocality can thus, in principle, be manifest in a single run of a certain measurement. This is known as the "all versus nothing" proof of Bell's theorem. In addition, the GHZ contradiction applies for all (100%) multiparticle systems that are in the same GHZ state. In the sense that it is for definite predictions and for all systems the GHZ theorem represents the strongest conflict between QM and local realism. However, the GHZ reasoning requires at least three particles and, consequently, three space-like separated regions (observers). This can be seen as a sort of three-particle quantum nonlocality, which differs from the two-particle quantum nonlocality as implied in usual BI.Then Hardy's argument of "quantum nonlocality without inequalities" for nonmaximally entangled biparticle states [6] came as a surprise. Now it is known as "the best version of Bell's theorem" [7] for two-dimensional two-particle systems. However, compared to the GHZ case, in Hardy's proof only a fraction ( 9%) of the photon pairs shows a contradiction with local realism. Most recently, another way to reveal sharper violations of local realism for two-particle entangled states in higherdimensional Hilbert spaces was found [8,9]. For the two-particle entangled states of high-dimensionality, the violation of local realism has more resistance to noise, but is still statistical. Motivated by Hardy and the highdimensional versions of Bell's theorem, one may ask: Can the conflict between QM and local realism arise even for the definite predictions and for all (100%) of the photon pair...

Existing animal models of femoral head osteonecrosis, while displaying varying levels of concordance with early histopathologic features of the human disorder, generally fail to progress to end-stage mechanical collapse. A new animal model of osteonecrosis is here introduced, utilizing the emu (Drornaius nouaehollandie). These animals' bipedality and their high activity level represent a much more challenging biomechanical environment to the hip than seen in quadrupedal models of this disorder. Femoral head osteonecrosis was induced surgically, using a combination of ischemic (vessel ligation) and cryogenic (liquid nitrogen) insults. Of nineteen emus allowed free-roaming pen activity to study the natural history of such lesions, eighteen progressed to an osseous structural failure, sixteen of them developing incapacitating lameness at an average time point 11.75 weeks after the surgical insult. Histologically, the animals showed close concordance with both the early-and late-stage human pathology, in six cases even to the point of developing a crescent sign. Because of its large physical size and its consistent progression to mechanical collapse, the emu appears to offer a unique opportunity for the near-human-scale study of surgical interventions to forestall femoral head collapse. Toward this end, various directions for model refinement are outlined.

All the states of N qubits can be classified into N-1 entanglement classes from 2-entangled to N-entangled (fully entangled) states. Each class of entangled states is characterized by an entanglement index that depends on the partition of N. The larger the entanglement index of a state, the more entangled or the less separable is the state in the sense that a larger maximal violation of Bell's inequality is attainable for this class of state.

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