Generation of polarization entangled photons using type-II doubly periodically poled lithium niobate waveguides

In this paper, we address the issue of the generation of non-degenerate cross-polarization-entangled photon pairs using type-II periodically poled lithium niobate. We show that, by an appropriate engineering of the quasi-phase-matching grating, it is possible to simultaneously satisfy the conditions for two spontaneous parametric down-conversion processes, namely ordinary pump photon down-conversion to either extraordinary signal and ordinary idler paired photons, or to ordinary signal and extraordinary idler paired photons. In contrast to single type-II phase-matching, these two processes, when enabled together, can lead to the direct production of cross-polarization-entangled state for non degenerate signal and idler wavelengths. Such a scheme should be of great interest in applications requiring polarization-entangled non degenerate paired photons with, for instance, one of the entangled photons at an appropriate wavelength being used for local operation or for quantum storage in an atomic ensemble, and the other one at the typical wavelength of 1550 nm for propagation through an optical fiber.Comment: 9 pages, 5 figures, 2 table

Increased pump acceptance bandwidth in spontaneous parametric downconversion process using Bragg reflection waveguides

In this paper we show that by suitably tailoring the dispersion characteristics of a Bragg reflection waveguide (BRW) mode, it is possible to achieve efficient photon pair generation over a large pump bandwidth while maintaining narrow signal bandwidth. The structure proposed consists of a high index core BRW with a periodically poled GaN core and periodically stratified cladding made up of alternate layers of $Al_{0.02}Ga_{0.98}N$ and $Al_{0.45}Ga_{0.55}N$. Such photon-pair generators should find applications in realizing compact and stable sources for quantum information processing.Comment: 6 pages, 5 figure

The inverse Laplace transform as the ultimate tool for transverse mass spectra

New high statistics data from the second generation of ultrarelativistic heavy-ion experiments open up new possibilities in terms of data analysis. To fully utilize the potential we propose to analyze the $m_\perp$-spectra of hadrons using the inverse Laplace transform. The problems with its inherent ill-definedness can be overcome and several applications in other fields like biology, chemistry or optics have already shown its feasability. Moreover, the method also promises to deliver upper bounds on the total information content of the spectra, which is of big importance for all other means of analysis. Here we compute several Laplace inversions from different thermal scenarios, both analytically and numerically, to test the efficiency of the method. Especially the case of a two component structure, related to a possible first order phase transition to a quark gluon plasma, is closer investigated and it is shown that at least a signal to noise ratio of $10^4$ is necessary to resolve two individual components.Comment: 13 pages (PostScript, including figures), BNL-NTHES

Polarization entangled photon-pair source based on a type-II PPLN waveguide emitting at a telecom wavelength

We report the realization of a fiber coupled polarization entangled photon-pair source at 1310 nm based on a birefringent titanium in-diffused waveguide integrated on periodically poled lithium niobate. By taking advantage of a dedicated and high-performance setup, we characterized the quantum properties of the pairs by measuring two-photon interference in both Hong-Ou-Mandel and standard Bell inequality configurations. We obtained, for the two sets of measurements, interference net visibilities reaching nearly 100%, which represent important and competitive results compared to similar waveguide-based configurations already reported. These results prove the relevance of our approach as an enabling technology for long-distance quantum communication.Comment: 13 pages, 4 figures, to appear in New Journal of Physic

Serratia marcescens bacteremia traced to an infused narcotic

BACKGROUND From June 30, 1998, through March 21, 1999, several patients in the surgical intensive care unit of a hospital acquired Serratia marcescens bacteremia. We investigated this outbreak. METHODS A case was defined as the occurrence of S. marcescens bacteremia in any patient in the surgical intensive care unit during the period of the epidemic. To identify risk factors, we compared patients with S. marcescens bacteremia with randomly selected controls. Isolates from patients and from medications were evaluated by pulsed-field gel electrophoresis. The hair of one employee was tested for fentanyl. RESULTS Twenty-six patients with S. marcescens bacteremia were identified; eight (31 percent) had polymicrobial bacteremia, and seven of these had Enterobacter cloacae and S. marcescens in the same culture. According to univariate analysis, patients with S. marcescensbacteremia stayed in the surgical intensive care unit longer than controls (13.5 vs. 4.0 days, PS. marcescens and E. cloacae. The isolates from the case patients and from the fentanyl infusions had similar patterns on pulsed-field gel electrophoresis. After removal of the implicated respiratory therapist, no further cases occurred. Full Text of Results... CONCLUSIONS An outbreak of S. marcescens and E. cloacae bacteremia in a surgical intensive care unit was traced to extrinsic contamination of the parenteral narcotic fentanyl by a health care worker. Our findings underscore the risk of complications in patients that is associated with illicit narcotic use by health care workers

Deciphering ligand specificity of a Clostridium thermocellum family 35 carbohydrate binding module (CtCBM35) for Gluco- and Galacto- Substituted mannans and Its calcium induced stability

Articles in International JournalsThis study investigated the role of CBM35 from Clostridium thermocellum (CtCBM35) in polysaccharide recognition. CtCBM35 was cloned into pET28a (+) vector with an engineered His6 tag and expressed in Escherichia coli BL21 (DE3) cells. A homogenous 15 kDa protein was purified by immobilized metal ion chromatography (IMAC). Ligand binding analysis of CtCBM35 was carried out by affinity electrophoresis using various soluble ligands. CtCBM35 showed a manno-configured ligand specific binding displaying significant association with konjac glucomannan (Ka = 14.3×104 M−1), carob galactomannan (Ka = 12.4×104 M−1) and negligible association (Ka = 12 µM−1) with insoluble mannan. Binding of CtCBM35 with polysaccharides which was calcium dependent exhibited two fold higher association in presence of 10 mM Ca2+ ion with konjac glucomannan (Ka = 41×104 M−1) and carob galactomannan (Ka = 30×104 M−1). The polysaccharide binding was further investigated by fluorescence spectrophotometric studies. On binding with carob galactomannan and konjac glucomannan the conformation of CtCBM35 changed significantly with regular 21 nm peak shifts towards lower quantum yield. The degree of association (Ka) with konjac glucomannan and carob galactomannan, 14.3×104 M−1 and 11.4×104 M−1, respectively, corroborated the findings from affinity electrophoresis. The association of CtCBM35with konjac glucomannan led to higher free energy of binding (ΔG) −25 kJ mole−1 as compared to carob galactomannan (ΔG) −22 kJ mole−1. On binding CtCBM35 with konjac glucomannan and carob galactomannan the hydrodynamic radius (RH) as analysed by dynamic light scattering (DLS) study, increased to 8 nm and 6 nm, respectively, from 4.25 nm in absence of ligand. The presence of 10 mM Ca2+ ions imparted stiffer orientation of CtCBM35 particles with increased RH of 4.52 nm. Due to such stiffer orientation CtCBM35 became more thermostable and its melting temperature was shifted to 70°C from initial 50°C

A cost-of-illness analysis of β-Thalassaemia major in children in Sri Lanka - experience from a tertiary level teaching hospital

Background Sri Lanka has a high prevalence of β-thalassaemia major. Clinical management is complex and long-term and includes regular blood transfusion and iron chelation therapy. The economic burden of β-thalassaemia for the Sri Lankan healthcare system and households is currently unknown. Methods A prevalence-based, cost-of-illness study was conducted on the Thalassaemia Unit, Department of Paediatrics, Kandy Teaching Hospital, Sri Lanka. Data were collected from clinical records, consultations with the head of the blood bank and a consultant paediatrician directly involved with the care of patients, alongside structured interviews with families to gather data on the personal costs incurred such as those for travel. Results Thirty-four children aged 2–17 years with transfusion dependent thalassaemia major and their parent/guardian were included in the study. The total average cost per patient year to the hospital was $US 2601 of which$US 2092 were direct costs and $US 509 were overhead costs. Mean household expenditure was$US 206 per year with food and transport per transfusion ($US 7.57 and$US 4.26 respectively) being the highest cost items. Nine (26.5%) families experienced catastrophic levels of healthcare expenditure (> 10% of income) in the care of their affected child. The poorest households were the most likely to experience such levels of expenditure. Conclusions β-thalassaemia major poses a significant economic burden on health services and the families of affected children in Sri Lanka. Greater support is needed for the high proportion of families that suffer catastrophic out-of-pocket costs

Colocalized Structural and Functional Changes in the Cortex of Patients with Trigeminal Neuropathic Pain

Background: Recent data suggests that in chronic pain there are changes in gray matter consistent with decreased brain volume, indicating that the disease process may produce morphological changes in the brains of those affected. However, no study has evaluated cortical thickness in relation to specific functional changes in evoked pain. In this study we sought to investigate structural (gray matter thickness) and functional (blood oxygenation dependent level – BOLD) changes in cortical regions of precisely matched patients with chronic trigeminal neuropathic pain (TNP) affecting the right maxillary (V2) division of the trigeminal nerve. The model has a number of advantages including the evaluation of specific changes that can be mapped to known somatotopic anatomy. Methodology/Principal Findings: Cortical regions were chosen based on sensory (Somatosensory cortex (SI and SII), motor (MI) and posterior insula), or emotional (DLPFC, Frontal, Anterior Insula, Cingulate) processing of pain. Both structural and functional (to brush-induced allodynia) scans were obtained and averaged from two different imaging sessions separated by 2–6 months in all patients. Age and gender-matched healthy controls were also scanned twice for cortical thickness measurement. Changes in cortical thickness of TNP patients were frequently colocalized and correlated with functional allodynic activations, and included both cortical thickening and thinning in sensorimotor regions, and predominantly thinning in emotional regions. Conclusions: Overall, such patterns of cortical thickness suggest a dynamic functionally-driven plasticity of the brain. These structural changes, which correlated with the pain duration, age-at-onset, pain intensity and cortical activity, may be specific targets for evaluating therapeutic interventions

Serratia marcescens internalization and replication in human bladder epithelial cells

BACKGROUND: Serratia marcescens, a frequent agent of catheterization-associated bacteriuria, strongly adheres to human bladder epithelial cells in culture. The epithelium normally provides a barrier between lumal organisms and the interstitium; the tight adhesion of bacteria to the epithelial cells can lead to internalization and subsequent lysis. However, internalisation was not shown yet for S. marcescens strains. METHODS: Elektronmicroscopy and the common gentamycin protection assay was used to assess intracellular bacteria. Via site directed mutagenesis, an hemolytic negative isogenic Serratia strain was generated to point out the importance of hemolysin production. RESULTS: We identified an important bacterial factor mediating the internalization of S. marcescens, and lysis of epithelial cells, as the secreted cytolysin ShlA. Microtubule filaments and actin filaments were shown to be involved in internalization. However, cytolysis of eukaryotic cells by ShlA was an interfering factor, and therefore hemolytic-negative mutants were used in subsequent experiments. Isogenic hemolysin-negative mutant strains were still adhesive, but were no longer cytotoxic, did not disrupt the cell culture monolayer, and were no longer internalized by HEp-2 and RT112 bladder epithelial cells under the conditions used for the wild-type strain. After wild-type S. marcescens became intracellular, the infected epithelial cells were lysed by extended vacuolation induced by ShlA. In late stages of vacuolation, highly motile S. marcescens cells were observed in the vacuoles. S. marcescens was also able to replicate in cultured HEp-2 cells, and replication was not dependent on hemolysin production. CONCLUSION: The results reported here showed that the pore-forming toxin ShlA triggers microtubule-dependent invasion and is the main factor inducing lysis of the epithelial cells to release the bacteria, and therefore plays a major role in the development of S. marcescens infections