Robust parallel laser driving of quantum dots for multiplexing of quantum light sources

Deterministic sources of quantum light (i.e. single photons or pairs of entangled photons) are required for a whole host of applications in quantum technology, including quantum imaging, quantum cryptography and the long-distance transfer of quantum information in future quantum networks. Semiconductor quantum dots are ideal candidates for solid-state quantum emitters as these artificial atoms have large dipole moments and a quantum confined energy level structure, enabling the realization of single photon sources with high repetition rates and high single photon purity. Quantum dots may also be triggered using a laser pulse for on-demand operation. The naturally-occurring size variations in ensembles of quantum dots offers the potential to increase the bandwidth of quantum communication systems through wavelength-division multiplexing, but conventional laser triggering schemes based on Rabi rotations are ineffective when applied to inequivalent emitters. Here we report the demonstration of the simultaneous triggering of >10 quantum dots using adiabatic rapid passage. We show that high-fidelity quantum state inversion is possible in a system of quantum dots with a 15 meV range of optical transition energies using a single broadband, chirped laser pulse, laying the foundation for high-bandwidth, multiplexed quantum networks.

Suppression of decoherence tied to electron-phonon coupling in telecom-compatible quantum dots: low-threshold reappearance regime for quantum state inversion

We demonstrate suppression of dephasing tied to deformation potential coupling of confined electrons to longitudinal acoustic (LA) phonons in optical control experiments on large semiconductor quantum dots (QDs) with emission compatible with the low-dispersion telecommunications band at 1.3 µm. By exploiting the sensitivity of the electron-phonon spectral density to the size and shape of the QD, we demonstrate a fourfold reduction in the threshold pulse area required to enter the decoupled regime for exciton inversion using adiabatic rapid passage (ARP). Our calculations of the quantum state dynamics indicate that the symmetry of the QD wave function provides an additional means to engineer the electron-phonon interaction. Our findings will support the development of solid-state quantum emitters in future distributed quantum networks using semiconductor QDs.

Relationship of Functional Reach Test scores and falls in Special Olympics athletes

BACKGROUND

The Functional Reach Test is used to assess balance of Special Olympic athletes as part of the FUNfitness screens held at Special Olympics games. However, it is unknown if the Functional Reach Test is an accurate assessment of balance in this population. The objective of this study was to explore the relationship between Functional Reach Test scores and falls in Special Olympic athletes.

METHODS

Data were collected as a part of the FUNfitness screens during Arizona Special Olympics games. The Functional Reach Test scores of 272 Special Olympic athletes were recorded. Athletes were asked to report the number of falls they experienced in the last 12 months.

RESULTS

A two-tailed Kendall tau test revealed little to no relationship between number of falls and Functional Reach Test scores of either the left upper extremity (n = 263, τ = -0.063, P = 0.202) or the right upper extremity (n = 263, τ = -0.107, P = 0.030). Sensitivity of the Functional Reach Test to identify fallers was 28.8%, and specificity was 83.5%.

CONCLUSIONS

Scores of the Functional Reach Test did not correlate with actual falls. The relatively high specificity indicates the assessment is good at identifying non-fallers, while the low sensitivity results in a high number of fallers not being recognised as such. Therefore, the cut-off scores used for the Functional Reach Test in FUNfitness screenings may need to be altered to more accurately identify balance deficits in this population. FUNfitness screens need to be quick, efficient and accurate. As such, selection of the most appropriate assessment tools is essential. Consideration should be given on how to make the Functional Reach Test the most beneficial as a FUNfitness screen.

Discordant tuberculin skin and interferon-gamma tests during contact investigations: a dilemma for tuberculosis controllers

Current recommendations conflict over the appropriate use of interferon-gamma whole blood assays to screen for tuberculosis (TB) infection in contact investigations. We report here on a worksite TB contact investigation in which tuberculin skin test (TST) and QuantiFERON-TB Gold (QFT-G) were both used to identify infection among 61 co-workers. Of the 27 (44%) who had a TST > or =15 mm, 11 (41%) had negative QFT-G, raising concerns that QFT-G may not be sufficiently sensitive when used alone in contact investigations. The questionable performance of QFT-G in this setting is not unexpected, as the negative predictive value of a test decreases with increasing prevalence.

Using chaos theory to understand a community-built occupational therapy practice

SUMMARY Community-built occupational therapy programs interact with a wide range of systems. This interaction does not occur in an orderly manner, but in an unpredictable fashion. The use of chaos theory may help program developers understand actual and potential interactions that may occur. To illustrate the use of chaos theory, a case study is presented.

Ligament tissue engineering using synthetic biodegradable fiber scaffolds

Tissue engineering offers the possibility of replacing damaged human ligaments with engineered ligament tissues. Hence, we attempted to culture in vitro ligament tissues by seeding human anterior cruciate ligament (ACL) and medial collateral ligament (MCL) cells onto synthetic biodegradable polymer fiber scaffolds. The ACL and MCL cells readily attached to the scaffold fibers. These cells and their secreted matrix soon surrounded the scaffold fibers and bridged the gaps in between. Beginning at 2 weeks, portions of the scaffolds were completely filled with tissue matrix. By 5 weeks, the scaffolds became single bundles of tissue. Thus the cell/fiber system appears to be a viable system for culturing ligament tissues. Additionally, cell proliferation under mechanical and biochemical stimuli was studied for up to 4 days. Whereas mechanical stimulus and transforming growth factor enhanced proliferation, inflammatory agents (lipopolysaccharide and complement C5a) had a negative effect. This work can thus contribute to a sound strategy for culturing replacement ligament tissues in vitro.

A mobile clinic experience: nurse practitioners providing care to a rural population

Improving access to health care for rural underserved populations is a growing concern. This article reviews the advantages of mobile clinics and describes a collaborative model for a nurse practitioner-operated mobile clinic that has provided cost education, early detection, and referral for low-income, rural populations. Examples of health care provided to a rural population in South Carolina are described. This approach to improving access to health care for underserved populations has implications for nursing practice in other rural areas.

Myeloproliferative disorder with profound hypereosinophilia associated with chemotherapy for breast cancer

A 47-year-old woman developed a unique myeloproliferative disorder 36 months after receiving adjuvant chemotherapy postoperatively for breast carcinoma. Her bone marrow and peripheral blood exhibited many of the myelodysplastic changes commonly observed in treatment-linked leukemia. In addition, there was striking marrow and blood eosinophilia and eosinophilic infiltration in multiple organs. She also developed a poorly differentiated lymphocytic lymphoma which responded to therapy. Her myeloproliferative disorder, with marked eosinophilia, continued to progress, however, and she died shortly after its diagnosis.

Phosphorylation of the beta subunit of Na+K+-ATPase in Ehrlich ascites tumor by a membrane-bound protein kinase

We have shown previously that proteoliposomes reconstituted with purified Na+K+-ATPase from Ehrlich ascites tumor cells, transport Na+ with low efficiency (Spector, M., O'Neal, S. and Racker, E. (1980) J. Biol. Chem., 255, 5504-5507). We now present evidence that this low efficiency (expressed in the ratio of Na+-transported/ATP-hydrolyzed) is caused by the phosphorylation of the beta subunit of the Na+K+-ATPase by an endogenous protein kinase. On addition of [gamma-32P]ATP, crude tumor plasma membrane preparations phosphorylated the beta subunit of the ATPase, whereas crude mouse brain plasma membranes did not. However, solubilized Na+K+-ATPase from either tumor or brain wre phosphorylated by purified protein kinase from the tumor plasma membrane and dephosphorylated by a phosphatase. In both cases, the phosphorylated enzyme was inefficient; the dephosphorylated enzyme was efficient after reconstitution into liposomes. During isolation of the Na+K+-ATPase from Ehrlich ascites tumor or mouse brain, an endogenous protease partially cleaved from the beta subunit a polypeptide of 29,000 daltons that contained the phosphorylation site. The proteolytic cleavage of the beta subunit was partially inhibited by phenylmethylsulfonyl fluoride and the major site of phosphorylation was then seen in the 53,000-dalton beta subunit of the enzyme. The isolated 29,000-dalton polypeptide from mouse brain ATPase was phosphorylated by tumor protein kinase with a stoichiometry of 1 mol of phosphate/mol of protein. When this 29,000-dalton polypeptide from mouse brain was incorporated into the tumor Na+K+-ATPase after mild proteolytic digestion, a marked increase in efficiency was observed after reconstitution of the Na+ pump.

Reconstitution of the Na+K+ pump of Ehrlich ascites tumor and enhancement of efficiency by quercetin

Plasma membranes from Ehrlich ascites tumor cells were solubilized by octylglucoside in the presence of phospholipids. The Na+K+-ATPase was purified from this extract by adsorption and elution from thio-Seph-arose 4B. The enzyme (specific activity, 7 mumoles of ATP hydrolyzed min-1 mg of protein -1) was reconstituted into liposomes by the octyglucoside dilution procedure. An ATP-dependent Na+ influx with low efficiency was observed. On addition of appropriate amounts of quercetin, the Na+ flux/ATP hydrolysis ratio was increased from 0.4 to 1.4.

Home birth in Salt Lake County, Utah

In Salt Lake County, Utah in 1972 and 1975, 167 women had planned home deliveries. Birth certificate data indicated they did not differ from the total population in age, marital, and socioeconomic status. Eighty-four women were interviewed and reported hostility from health professionals which may have placed them at unnecessary risk.