Generalized quantum measurements and local realism

The structure of a local hidden variable model for experiments involving sequences of measurements rigorously is analyzed. Constraints imposed by local realism on the conditional probabilities of the outcomes of such measurement schemes are explicitly derived. The violation of local realism in the case of ``hidden nonlocality'' is illustrated by an operational example.Comment: Revtex, 12 pages; Some modifications of introduction has been made; a note stating that part of results had been obtained earlier by other authors, has been added; one postscript figure available at request from [email protected]

No-hidden-variables proof for two spin-1/2 particles preselected and postselected in unentangled states

It is a well-known fact that all the statistical predictions of quantum mechanics on the state of any physical system represented by a two-dimensional Hilbert space can always be duplicated by a noncontextual hidden-variables model. In this paper, I show that, in some cases, when we consider an additional independent (unentangled) two-dimensional system, the quantum description of the resulting composite system cannot be reproduced using noncontextual hidden variables. In particular, a no-hidden-variables proof is presented for two individual spin-1/2 particles preselected in an uncorrelated state AB and postselected in another uncorrelated state aB, B being the same state for the second particle in both preselection and postselection.Comment: LaTeX, 8 page

Successful Implementation of a Window for Routine Antimicrobial Prophylaxis Shorter than That of the World Health Organization Standard

Objective. To evaluate the feasibility of implementation of the refined window for routine antimicrobial prophylaxis (RAP) of 30-74 minutes before skin incision compared to the World Health Organization (WHO) standard of 0-60 minutes. Design. Prospective study on timing of routine antimicrobial prophylaxis in 2 different time periods. Setting. Tertiary referral university hospital with 30,000 surgical procedures per year. Methods. In all consecutive vascular, visceral, and trauma procedures, the timing was prospectively recorded during a first time period of 2 years (A; baseline) and a second period of 1 year (B; after intervention). An intensive intervention program was initiated after baseline. The primary outcome parameter was timing; the secondary outcome parameter was surgical site infection (SSI) rate in the subgroup of patients undergoing cholecystectomy/colon resection. Results. During baseline time period A (3,836 procedures), RAP was administered 30-74 minutes before skin incision in 1,750 (41.0%) procedures; during time period B (1,537 procedures), it was administered in 914 (56.0%; P < .001). The subgroup analysis did not reveal a significant difference in SSI rate. Conclusions. This bundle of interventions resulted in a statistically significant improvement of timing of RAP even at a shortened window compared to the WHO standar

Good Quantum Convolutional Error Correction Codes And Their Decoding Algorithm Exist

Quantum convolutional code was introduced recently as an alternative way to protect vital quantum information. To complete the analysis of quantum convolutional code, I report a way to decode certain quantum convolutional codes based on the classical Viterbi decoding algorithm. This decoding algorithm is optimal for a memoryless channel. I also report three simple criteria to test if decoding errors in a quantum convolutional code will terminate after a finite number of decoding steps whenever the Hilbert space dimension of each quantum register is a prime power. Finally, I show that certain quantum convolutional codes are in fact stabilizer codes. And hence, these quantum stabilizer convolutional codes have fault-tolerant implementations.Comment: Minor changes, to appear in PR

Preparation of polarization entangled mixed states of two photons

We propose a scheme for preparing arbitrary two photons polarization entangled mixed states via controlled location decoherence. The scheme uses only linear optical devices and single-mode optical fibers, and may be feasible in experiment within current optical technology.Comment: 3 pages, 5 figs. The article has been rewritten. Discussion about experiment are added. To appear in Phys. Rev.

Collective tests for quantum nonlocality

Pairs of spin-1/2 particles are prepared in a Werner state (namely, a mixture of singlet and random components). If the random component is large enough, the statistical results of spin measurements that may be performed on each pair separately can be reproduced by an algorithm involving local ``hidden'' variables. However, if several such pairs are tested simultaneously, a violation of the Clauser-Horne-Shimony-Holt inequality may occur, and no local hidden variable model is compatible with the results.Comment: 14 pages, LaTeX, 1 figure on separate pag

Economic Burden of Surgical Site Infections at a European University Hospital

Objective. To quantify the economic burden of in-hospital surgical site infections (SSIs) at a European university hospital. Design. Matched case-control study nested in a prospective observational cohort study. Setting. Basel University Hospital in Switzerland, where an average of 28,000 surgical procedures are performed per year. Methods. All in-hospital occurrences of SSI associated with surgeries performed between January 1, 2000, and December 31, 2001, by the visceral, vascular, and traumatology divisions at Basel University Hospital were prospectively recorded. Each case patient was matched to a control patient by age, procedure code, and National Nosocomial Infection Surveillance System risk index. The case-control pairs were analyzed for differences in cost of hospital care and in provision of specialized care. Results. A total of 6,283 procedures were performed:187 SSIs were detected in inpatients, 168 of whom were successfully matched with a control patient. For case patients, the mean additional hospital cost was SwF19,638 (95% confidence interval [CI], SwF8,492-SwF30,784); the mean additional postoperative length of hospital stay was 16.8 days (95% CI, 13-20.6 days); and the mean additional in-hospital duration of antibiotic therapy was 7.4 days (95% CI, 5.1-9.6 days). Differences were primarily attributable to organ space SSIs (n = 76). Conclusions. Ina European university hospital setting, SSIs are costly and constitute a heavy and potentially preventable burden on both patients and healthcare provider

Improved diagnostics targeting c-MET in non-small cell lung cancer: expression, amplification and activation?

Background: Several c-MET targeting inhibitory molecules have already shown promising results in the treatment of patients with Non-small Cell Lung Cancer (NSCLC). Combination of EGFR-and c-MET-specific molecules may overcome EGFR tyrosine kinase inhibitor (TKI) resistance. The aim of this study was to allow for the identification of patients who might benefit from TKI treatments targeting MET and to narrow in on the diagnostic assessment of MET. Methods: 222 tumor tissues of patients with NSCLC were analyzed concerning c-MET expression and activation in terms of phosphorylation (Y1234/1235 and Y1349) using a microarray format employing immunohistochemistry (IHC). Furthermore, protein expression and MET activation was correlated with the amplification status by Fluorescence in Situ Hybridization (FISH). Results: Correlation was observed between phosphorylation of c-MET at Y1234/1235 and Y1349 (spearman correlation coefficient r(s) = 0.41;p 0.05). c-MET gene amplification was detected in eight of 214 patients (3.7 %). No significant association was observed between c-MET amplification, c-MET protein expression and phosphorylation. Conclusion: Our data indicate, that neither expression of c-MET nor the gene amplification status might be the best way to select patients for MET targeting therapies, since no correlation with the activation status of MET was observed. We propose to take into account analyzing the phosphorylation status of MET by IHC to select patients for MET targeting therapies. Signaling of the receptor and the activation of downstream molecules might be more crucial for the benefit of therapeutics targeting MET receptor tyrosine kinases than expression levels alone

Quantum circuits for spin and flavor degrees of freedom of quarks forming nucleons

We discuss the quantum-circuit realization of the state of a nucleon in the scope of simple symmetry groups. Explicit algorithms are presented for the preparation of the state of a neutron or a proton as resulting from the composition of their quark constituents. We estimate the computational resources required for such a simulation and design a photonic network for its implementation. Moreover, we highlight that current work on three-body interactions in lattices of interacting qubits, combined with the measurement-based paradigm for quantum information processing, may also be suitable for the implementation of these nucleonic spin states.Comment: 5 pages, 2 figures, RevTeX4; Accepted for publication in Quantum Information Processin