An elementary quantum network operation involves storing a qubit state in an atomic quantum memory node, and then retrieving and transporting the information through a single photon excitation to a ...remote quantum memory node for further storage or analysis. Implementations of quantum network operations are thus conditioned on the ability to realize matter-to-light and/or light-to-matter quantum state mappings. Here we report the generation, transmission, storage and retrieval of single quanta using two remote atomic ensembles. A single photon is generated from a cold atomic ensemble at one site , and is directed to another site through 100 metres of optical fibre. The photon is then converted into a single collective atomic excitation using a dark-state polariton approach. After a programmable storage time, the atomic excitation is converted back into a single photon. This is demonstrated experimentally, for a storage time of 0.5 microseconds, by measurement of an anti-correlation parameter. Storage times exceeding ten microseconds are observed by intensity cross-correlation measurements. This storage period is two orders of magnitude longer than the time required to achieve conversion between photonic and atomic quanta. The controlled transfer of single quanta between remote quantum memories constitutes an important step towards distributed quantum networks.
In a fibre-based quantum information network, telecom-wavelength transmission between quantum memory elements is required to minimize absorption. Owing to the paucity of suitable ground-state atomic ...transitions, a quantum memory interfaced with telecom light has not been previously realized. We report its demonstration by converting to telecom wavelength near-infrared light emitted on a ground-state transition. The conversion is achieved with a diamond configuration of atomic transitions, in an optically thick gas of cold rubidium. The quantum memory is also realized with cold rubidium, but confined in an optical lattice to suppress motional dephasing on a submillisecond timescale. We observe quantum memory lifetimes in excess of 0.1 s by laser compensation of the lattice light shifts that limited the previous generation of atomic memory to 7 ms. By measuring quantum correlations of light fields before and after telecom down-conversion, transmission and up-conversion, we demonstrate a basic memory element for a scalable, long-distance quantum network. PUBLICATION ABSTRACT
Summary Background The prevalence of hepatitis E virus (HEV) genotype 3 infections in the English population (including blood donors) is unknown, but is probably widespread, and the virus has been ...detected in pooled plasma products. HEV-infected donors have been retrospectively identified through investigation of reported cases of possible transfusion-transmitted hepatitis E. The frequency of HEV transmission by transfusion and its outcome remains unknown. We report the prevalence of HEV RNA in blood donations, the transmission of the virus through a range of blood components, and describe the resulting morbidity in the recipients. Methods From Oct 8, 2012, to Sept 30, 2013, 225 000 blood donations that were collected in southeast England were screened retrospectively for HEV RNA. Donations containing HEV were characterised by use of serology and genomic phylogeny. Recipients, who received any blood components from these donations, were identified and the outcome of exposure was ascertained. Findings 79 donors were viraemic with genotype 3 HEV, giving an RNA prevalence of one in 2848. Most viraemic donors were seronegative at the time of donation. The 79 donations had been used to prepare 129 blood components, 62 of which had been transfused before identification of the infected donation. Follow-up of 43 recipients showed 18 (42%) had evidence of infection. Absence of detectable antibody and high viral load in the donation rendered infection more likely. Recipient immunosuppression delayed or prevented seroconversion and extended the duration of viraemia. Three recipients cleared longstanding infection after intervention with ribavirin or alteration in immunosuppressive therapy. Ten recipients developed prolonged or persistent infection. Transaminitis was common, but short-term morbidity was rare; only one recipient developed apparent but clinically mild post-transfusion hepatitis. Interpretation Our findings suggest that HEV genotype 3 infections are widespread in the English population and in blood donors. Transfusion-transmitted infections rarely caused acute morbidity, but in some immunosuppressed patients became persistent. Although at present blood donations are not screened, an agreed policy is needed for the identification of patients with persistent HEV infection, irrespective of origin, so that they can be offered antiviral therapy. Funding Public Health England and National Health Service Blood and Transplant.
Droplet microfluidics enables high-throughput manipulation of fL-μL volume samples. Methods implemented for the chemical analysis of microfluidic droplets have been limited in scope, leaving some ...applications of droplet microfluidics difficult to perform or out of reach entirely. Nanoelectrospray ionization-mass spectrometry (nESI-MS) is an attractive approach for droplet analysis, because it allows rapid, label-free, information-rich analysis with high mass sensitivity and resistance to matrix effects. Previous proof-of-concept systems for the nESI-MS analysis of droplets have been limited by the microfluidics used so that stable, long-term operation needed for high-throughput applications has not been demonstrated. We describe a platform for the stable analysis of microfluidic droplet samples by nESI-MS. Continuous infusion of droplets to an nESI emitter was demonstrated for as long as 2.5 h, corresponding to analysis of over 20 000 samples. Stable signal was observed for droplets as small as 65 pL and for throughputs as high as 10 droplets/s. A linear-concentration-based response and sample-to-sample carryover of <3% were also shown. The system is demonstrated for measuring products of in-droplet enzymatic reactions.
Chronic hepatitis B virus （HBV） infection progresses through distinct disease phases that are strongly associated with patient age. The so-called immune tolerant （IT） phase represents the classical ...early phase of infection; it is associated with high levels of HBV replication and lack of clinical signs of liver Inflammation. Whether this phase of HBV infection is also associated with immunological features of ＂tolerance＇ has recently been challenged. Here, we review the data that dispute this concept of immune tolerance and then propose an alternative interpretation of the immunopathological events that take place during this early phase of CHB infection.
Materials exhibiting a spontaneous electrical polarization that can be switched easily between antiparallel orientations are of potential value for sensors, photonics and energy-efficient memories. ...In this context, organic ferroelectrics are of particular interest because they promise to be lightweight, inexpensive and easily processed into devices. A recently identified family of organic ferroelectric structures is based on intermolecular charge transfer, where donor and acceptor molecules co-crystallize in an alternating fashion known as a mixed stack: in the crystalline lattice, a collective transfer of electrons from donor to acceptor molecules results in the formation of dipoles that can be realigned by an external field as molecules switch partners in the mixed stack. Although mixed stacks have been investigated extensively, only three systems are known to show ferroelectric switching, all below 71 kelvin. Here we describe supramolecular charge-transfer networks that undergo ferroelectric polarization switching with a ferroelectric Curie temperature above room temperature. These polar and switchable systems utilize a structural synergy between a hydrogen-bonded network and charge-transfer complexation of donor and acceptor molecules in a mixed stack. This supramolecular motif could help guide the development of other functional organic systems that can switch polarization under the influence of electric fields at ambient temperatures.
Summary
Background
Although highly prevalent, little is known about the economic impact of functional dyspepsia (FD).
Aims
To quantify FD patients' health care utilisation patterns and to estimate ...direct and indirect costs of FD to patients.
Methods
ICD‐9 codes identified adult patients with dyspepsia. A validated questionnaire was mailed to patients who met Rome III criteria for FD.
Results
Three hundred and fifty‐five patients met all inclusion criteria. The response rate was 63%. The respondents' mean age was 50 (14) years; 75% were women; 52% of respondents rated their FD as moderate. Patients reported 3 visits (mean) to their PCP over 12 months; 75% reported having blood work, 92% an EGD, 59% an ultrasound and 40% a CT scan. The direct cost of testing using Medicare reimbursement rates per patient was $582. To treat FD symptoms, 89% tried dietary changes, 89% over‐the‐counter medications, 87% prescription medications and 25% alternative therapies. Mean patient expenditure over the last year was $246 for OTC medications (range $0–12,000), $290 for co‐payments (range $0–9,000) and $110 for alternative treatments (range $0–3,741). Total mean direct cost yearly to patients was $699. In the 7 days prior to completing the questionnaire, respondents reported a mean of 1.4 h absence from work. Extrapolating the results to the US population, we conservatively calculate the costs of FD were $18.4 billion in 2009.
Conclusions
Functional dyspepsia patients incur significant direct and indirect costs and work productivity is impaired by dyspeptic symptoms.
NK cells are important antiviral effectors, highly enriched in the liver, with the potential to regulate immunopathogenesis in persistent viral infections. Here we examined whether changes in the NK ...pool are induced when patients with eAg-positive CHB are 'primed' with PegIFNα and importantly, whether these changes are sustained or further modulated long-term after switching to nucleos(t)ides (sequential NUC therapy), an approach currently tested in the clinic. Longitudinal sampling of a prospectively recruited cohort of patients with eAg+CHB showed that the cumulative expansion of CD56bright NK cells driven by 48-weeks of PegIFNα was maintained at higher than baseline levels throughout the subsequent 9 months of sequential NUCs. Unexpectedly, PegIFNα-expanded NK cells showed further augmentation in their expression of the activating NK cell receptors NKp30 and NKp46 during sequential NUCs. The expansion in proliferating, functional NK cells was more pronounced following sequential NUCs than in comparison cohorts of patients treated with de novo NUCs or PegIFNα only. Reduction in circulating HBsAg concentrations, a key goal in the path towards functional cure of CHB, was only achieved in those patients with enhancement of NK cell IFNγ and cytotoxicity but decrease in their expression of the death ligand TRAIL. In summary, we conclude that PegIFNα priming can expand a population of functional NK cells with an altered responsiveness to subsequent antiviral suppression by NUCs. Patients on sequential NUCs with a distinct NK cell profile show a decline in HBsAg, providing mechanistic insights for the further optimisation of treatment strategies to achieve sustained responses in CHB.
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