Preventive treatment of nephrolithiasis with alkali citrate—a critical review

Using the keywords "urolithiasis and citrate treatment”, "nephrolithaisis and citrate treatment”, "kidney stones and citrate treatment”, a Medline search revealed 635 articles published between 1 January 1966 and 1 December 2004. For the present analysis, only studies meeting all of the following criteria were included: (1) publications in English or German, (2) studies on preventive alkali citrate treatment in patients with calcium oxalate, uric acid and infection stone disease, (3) clinical studies including at least ten subjects, and (4) treatment phases of at least 1week duration. A total of 43 studies met the inclusion criteria and were further subclassified according to intermediate or ultimate endpoints as well as to study design. With stone recurrence as the ultimate endpoint, 21 uncontrolled studies in almost 1,000 patients demonstrated a reduction in stone forming rate by 47-100%. In four randomized controlled trials including 227 patients, 53.5% on alkali citrate vs 35% on placebo remained stone-free after at least 1year of treatment (P<0.0005). Similar values (66% vs 27.5% for alkali citrate vs placebo, P<0.0005) were obtained in 104 patients from two randomized trials with dissolution/clearance of residual stones as endpoint. Unfortunately, up to 48% of alkali citrate treated patients left the studies prematurely, primarily due to adverse effects such as eructation, bloating, gaseousness or frank diarrhe

Creation of macroscopic superposition states from arrays of Bose-Einstein condensates

We consider how macroscopic quantum superpositions may be created from arrays of Bose-Einstein condensates. We study a system of three condensates in Fock states, all with the same number of atoms and show that this has the form of a highly entangled superposition of different quasi-momenta. We then show how, by partially releasing these condensates and detecting an interference pattern where they overlap, it is possible to create a macroscopic superposition of different relative phases for the remaining portions of the condensates. We discuss methods for confirming these superpositions.Comment: 7 pages, 5 figure

Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

We report on a quantum optical experimental implementation of teleportation of unknown pure quantum states. This realizes all the nonlocal aspects of the original scheme proposed by Bennett et al. and is equivalent to it up to a local operation. We exhibit results for the teleportation of a linearly polarized state and of an elliptically polarized state. We show that the experimental results cannot be explained in terms of a classical channel alone.Comment: 11 pages LaTeX, 3 figures, 1 page figures captions. The figures and figures captions are not encapsulated; please print them separatel

"All versus nothing" inseparability for two observers

A recent proof of Bell's theorem without inequalities [A. Cabello, Phys. Rev. Lett. 86, 1911 (2001)] is formulated as a Greenberger-Horne-Zeilinger-like proof involving just two observers. On one hand, this new approach allows us to derive an experimentally testable Bell inequality which is violated by quantum mechanics. On the other hand, it leads to a new state-independent proof of the Kochen-Specker theorem and provides a wider perspective on the relations between the major proofs of no-hidden-variables.Comment: REVTeX, 4 page

Experimentally realizable quantum comparison of coherent states and its applications

When comparing quantum states to each other, it is possible to obtain an unambiguous answer, indicating that the states are definitely different, already after a single measurement. In this paper we investigate comparison of coherent states, which is the simplest example of quantum state comparison for continuous variables. The method we present has a high success probability, and is experimentally feasible to realize as the only required components are beam splitters and photon detectors. An easily realizable method for quantum state comparison could be important for real applications. As examples of such applications we present a "lock and key" scheme and a simple scheme for quantum public key distribution.Comment: 14 pages, 5 figures, version one submitted to PRA. Version two is the final accepted versio

Coherent Time Evolution and Boundary Conditions of Two-Photon Quantum Walks

Multi-photon quantum walks in integrated optics are an attractive controlled quantum system, that can mimic less readily accessible quantum systems and exhibit behavior that cannot in general be accurately replicated by classical light without an exponential overhead in resources. The ability to observe time evolution of such systems is important for characterising multi-particle quantum dynamics---notably this includes the effects of boundary conditions for walks in spaces of finite size. Here we demonstrate the coherent evolution of quantum walks of two indistinguishable photons using planar arrays of 21 evanescently coupled waveguides fabricated in silicon oxynitride technology. We compare three time evolutions, that follow closely a model assuming unitary evolution, corresponding to three different lengths of the array---in each case we observe quantum interference features that violate classical predictions. The longest array includes reflecting boundary conditions.Comment: 7 pages,7 figure

Optimal entanglement purifying via entanglement swapping

It is known that entanglement swapping can be used to realize entanglement purifying. By this way, two particles belong to different non-maximally entangled pairs can be projected probabilisticly to a maximally entangled state or to a less entangled state. In this report, we show, when the less entangled state is obtained, if a unitary transformation is introduced locally, then a maximally entangled state can be obtained probabilisticly from this less entangled state. The total successful probability of our scheme is equal to the entanglement of a single pairpurification (if two original pairs are in the same non-maximally entangled states) or to the smaller entanglement of a single pair purification of these two pairs (if two original pairs are not in the same non-maximally entangled states). The advantage of our scheme is no continuous indefinite iterative procedure is needed to achieve optimal purifying.Comment: 7 pages, Revtex, no figure, accepted by Phys. Rev. A as a Brief Repor

Hiding bits in Bell states

We present a scheme for hiding bits in Bell states that is secure even when the sharers Alice and Bob are allowed to carry out local quantum operations and classical communication. We prove that the information that Alice and Bob can gain about a hidden bit is exponentially small in $n$, the number of qubits in each share, and can be made arbitrarily small for hiding multiple bits. We indicate an alternative efficient low-entanglement method for preparing the shared quantum states. We discuss how our scheme can be implemented using present-day quantum optics.Comment: 4 pages RevTex, 1 figure, various small changes and additional paragraph on optics implementatio

Violations of local realism with quNits up to N=16

Predictions for systems in entangled states cannot be described in local realistic terms. However, after admixing some noise such a description is possible. We show that for two quNits (quantum systems described by N dimensional Hilbert spaces) in a maximally entangled state the minimal admixture of noise increases monotonically with N. The results are a direct extension of those of Kaszlikowski et. al., Phys. Rev. Lett. {\bf 85}, 4418 (2000), where results for $N\leq 9$ were presented. The extension up to N=16 is possible when one defines for each N a specially chosen set of observables. We also present results concerning the critical detectors efficiency beyond which a valid test of local realism for entangled quNits is possible.Comment: 5 pages, 3 ps picture

Vascular risk factors in the Swiss population

Background and Purpose : Identification of the population at risk of stroke remains the best approach to assess the burden of cardiovascular morbidity and mortality. Methods : The prevalence of hypertension (HT), hypercholesterolemia (HCh), diabetes mellitus (DM), overweight (OW), obesity (OB), tobacco use (SM), and their combinations was examined in 4458 Swiss persons (1741 men and 2717 women, mean age 57.8 ± 15 years), who volunteered for the present survey. Results : OW was the most prevalent risk factor (50 %), followed by HT (47%), HCh (33%), SM (13 %) and DM (1.6 %). The proportion of persons without risk factors (RF) was 19.9%, with 1 RF 41.5%, 2 RF 33.8%, 3 RF 4%, and 4 RF 0.9%. OW was more prevalent in men than in women (53% vs. 41%, P=0.02). More men than women aged 41-50 years and 51-60 years had HT (49 % vs. 36%, P=0.01, and 52 % vs. 42%, P=0.02). The prevalence of HCh and DM did not show any sex-related differences. HT, OW and HCh were not only the most common single risk factors, but were also most likely to aggregate with each other. Conclusions : The majority of Swiss people have one or two vascular risk factors. OW and HT are by far most common and are likely to aggregate with each other. A small modification of these two factors would reduce the incidence of stroke and myocardial infarction significantl