Quantum information storage for over 180 s using donor spins in a 28Si "semiconductor vacuum"

A quantum computer requires systems that are isolated from their environment, but can be integrated into devices, and whose states can be measured with high accuracy. Nuclear spins in solids promise long coherence lifetimes, but they are difficult to initialize into known states and to detect with high sensitivity. We show how the distinctive optical properties of enriched (28)Si enable the use of hyperfine-resolved optical transitions, as previously applied to great effect for isolated atoms and ions in vacuum. Together with efficient Auger photoionization, these resolved hyperfine transitions permit rapid nuclear hyperpolarization and electrical spin-readout. We combine these techniques to detect nuclear magnetic resonance from dilute (31)P in the purest available sample of (28)Si, at concentrations inaccessible to conventional measurements, measuring a solid-state coherence time of over 180 seconds.

Costs of admission for paediatric pneumonia in a setting of human immunodeficiency virus infection

BACKGROUND

Pneumonia in South African children remains a major public health concern. The costs of hospital admission for pneumonia should be determined, especially where human immunodeficiency virus (HIV) infection is common.

OBJECTIVE

To determine the hospital costs of children (HIV-infected vs. non-HIV-infected) admitted for the management of pneumonia and compare them in the public and fee-for-service sectors.

METHODS

A retrospective review of paediatric admissions in 2007 was performed. Costs were determined for the public and fee-for-service sectors. Outcome measures included hospital mortality and comparative costs of admission.

RESULTS

There were 132 admissions in a public sector facility (67% HIV-infected), and 7882 in the fee-for-service sector (1.2% HIV-infected). Total mortality was respectively 25% in the public and 0.04% in the fee-for-service sectors. The mean cost for HIV-infected patients was respectively US$639.06 and US$10 540.04 in the public and fee-for-service sectors. For non-HIV-infected patients, the cost was respectively US$399.45 and US$3936.87. Length of stay for HIV-infected patients was longer by respectively 1.8 days and 5.7 days in the public sector among admissions to the ward and to the paediatric intensive care unit.

CONCLUSION

Admission for HIV-infected children with pneumonia costs significantly more in both sectors. Preventive strategies are needed.

Allo-SCT for multiple myeloma: a review of outcomes at a single transplant center

Allogeneic stem cell transplant for multiple myeloma (MM) is one treatment associated with long-term disease-free survival. The high incidence of treatment-related mortality and relapses, however, are important reasons for controversy about the role of allografting in the management of MM. We reviewed our results of allografting for MM spanning a period of 34 years in order to better define long-term outcomes and identify areas of progress as well as areas requiring improvement. A total of 278 patients received allogeneic marrow or PBSCs after high-dose myeloablative (N=144) or reduced intensity, non-myeloablative (N=134) regimens. In multivariable analysis, adjusting for differences in patient groups, reduced intensity/non-myeloablative transplants were associated with significantly less acute GVHD, lower transplant mortality, better PFS and overall survival. There were no significant differences in relapse, progression or chronic GVHD, when adjusted. In multivariable analysis of patients receiving only non-myeloablative transplants, decreased overall survival and PFS were associated with relapse after a prior autograft and a β2 microglobulin >4.0. Transplant mortality was reduced and only influenced by a prior tandem autograft.

The prevalence of intentional and unintentional injuries in selected Johannesburg housing settlements

Intentional and unintentional injuries were reported to be the second leading cause of Disability Adjusted Life Years in South Africa in 2000. We present household experiences of such injuries in 5 impoverished housing settlements in Johannesburg, Gauteng Province. Data for this study were extracted from the database of the Health, Environment and Development (HEAD) project. The incidence of reported intentional injuries was determined to be double that of unintentional injuries. Households in the Hospital Hill and Riverlea settlements reported the highest prevalence of stabbing and gunshot incidents. We concluded that impoverished South African neighbourhoods bear a high burden of intentional injury; surveillance mechanisms are required to inform prevention strategies at an individual, community and societal level.

The biaxial nonlinear crystal BiB₃O₆ as a polarization entangled photon source using non-collinear type-II parametric down-conversion

We describe the full characterization of the biaxial nonlinear crystal BiB₃O₆ (BiBO) as a polarization entangled photon source using non-collinear type-II parametric down-conversion. We consider the relevant parameters for crystal design, such as cutting angles, polarization of the photons, effective nonlinearity, spatial and temporal walk-offs, crystal thickness and the effect of the pump laser bandwidth. Experimental results showing entanglement generation with high rates and a comparison to the well investigated β-BaB₂O₄ (BBO) crystal are presented as well. Changing the down-conversion crystal of a polarization entangled photon source from BBO to BiBO enhances the generation rate as if the pump power was increased by 2.5 times. Such an improvement is currently required for the generation of multiphoton entangled states.

The cytotoxic potential of interleukin-15-stimulated cytokine-induced killer cells against leukemia cells

BACKGROUND AIMS

Cytokine-induced killer (CIK) cells may serve as an alternative approach to adoptive donor lymphocyte infusions (DLI) for patients with acute leukemia relapsing after haplo-identical hematopoietic stem cell transplantation (HSCT). We investigated the feasibility of enhancing CIK cell-mediated cytotoxicity by interleukin (IL)-15 against acute myeloid and lymphoblastic leukemia/lymphoma cells.

METHODS

CIK cells were activated using IL-2 (CIK(IL-2)) or IL-15 (CIK(IL-15)) and phenotypically analyzed by fluorescence-activated cell sorting (FACS). Cytotoxic potential was measured by europium release assay.

RESULTS

CIK(IL-2) cells showed potent cytotoxicity against the T-lymphoma cell line H9, T-cell acute lymphoblastic leukemia (T-ALL) cell line MOLT-4 and subtype M4 acute myeloid leukemia (AML) cell line THP-1, but low cytotoxicity against the precursor B (pB)-cell ALL cell line Tanoue. IL-15 stimulation resulted in a significant enhancement of CIK cell-mediated cytotoxicity against acute lymphoblastic leukemia/lymphoma cell lines as well as against primary acute myeloid and defined lymphoblastic leukemia cells. However, the alloreactive potential of CIK(IL-15) cells remained low. Further analysis of CIK(IL-15) cells demonstrated that the NKG2D receptor is apparently involved in the recognition of target cells whereas killer-cell immunoglobulin-like receptor (KIR)-HLA mismatches contributed to a lesser extent to the CIK(IL-15) cell-mediated cytotoxicity. In this context, CD3 (+) CD8 (+) CD25 (+) CD56(-) CIK(IL-15) cell subpopulations were more effective in the lysis of AML cells, in contrast with CD56 (+) CIK(IL-15) cells, which showed the highest cytotoxic potential against ALL cells.

CONCLUSIONS

This study provides the first evidence that CIK(IL-15) cells may offer a therapeutic option for patients with refractory or relapsed leukemia following haplo-identical HSCT.

The effect of pulsed 900-MHz GSM mobile phone radiation on the acrosome reaction, head morphometry and zona binding of human spermatozoa

Several recent studies have indicated that radiofrequency electromagnetic fields (RF-EMF) have an adverse effect on human sperm quality, which could translate into an effect on fertilization potential. This study evaluated the effect of RF-EMF on sperm-specific characteristics to assess the fertilizing competence of sperm. Highly motile human spermatozoa were exposed for 1 h to 900-MHz mobile phone radiation at a specific absorption rate of 2.0 W/kg and examined at various times after exposure. The acrosome reaction was evaluated using flow cytometry. The radiation did not affect sperm propensity for the acrosome reaction. Morphometric parameters were assessed using computer-assisted sperm analysis. Significant reduction in sperm head area (9.2 ± 0.7 μm² vs. 18.8 ± 1.4 μm²) and acrosome percentage of the head area (21.5 ± 4% vs. 35.5 ± 11.4%) was reported among exposed sperm compared with unexposed controls. Sperm-zona binding was assessed directly after exposure using the hemizona assay. The mean number of zona-bound sperm of the test hemizona and controls was 22.8 ± 12.4 and 31.8 ± 12.8 (p < 0.05), respectively. This study concludes that although RF-EMF exposure did not adversely affect the acrosome reaction, it had a significant effect on sperm morphometry. In addition, a significant decrease in sperm binding to the hemizona was observed. These results could indicate a significant effect of RF-EMF on sperm fertilization potential.

GaN nanodiscs embedded in nanowires as optochemical transducers

The photoluminescence (PL) response of GaN/AlGaN nanowire heterostructures (NWHs) to hydrogen and oxygen between room temperature and 300 °C is reported. Exposure of Pt-coated NWHs to H2 leads to an increase of the PL intensity attributed to the suppression of surface recombination by local dipole fields of adsorbed atomic hydrogen. When exposed to O2, uncoated NWHs show a decrease in PL intensity that is assigned to enhanced non-radiative recombination. The detection limits are below 5 ppm at 150 °C.

Neodymium(III) molybdenum(VI) borate, NdBO(2)MoO(4)

Single crystals of NdBO₂MoO₄ were obtained from a molybdenum oxide–boron oxide flux under an air atmosphere. The structure features double chains of edge- and face-sharing distorted [NdO₁₀] bicapped square-anti­prisms, which are linked by rows of isolated [MoO₄] tetra­hedra and by zigzag chains of corner-sharing [BO₃] groups, all of them running along the b axis. The chains of [NdO₁₀], chains of [BO₃] and rows of [MoO₄] groups are arranged in layers parallel to the bc plane.

Health-related quality of life of survivors of penetrating trunk trauma in Johannesburg, South Africa

PURPOSE

To study how the health-related quality of life (HRQOL) of survivors of penetrating trunk trauma (PTT) changes from pre-morbid status to 6 months after hospital discharge and to determine differences in the HRQOL between subjects ventilated for short and prolonged periods of time. To determine how the HRQOL of PTT survivors compares with that of a healthy control group in order to identify limitations imposed by critical illness.

METHODS

Retrospective and observational prospective assessment of the quality of life (QoL) of PTT survivors with the Medical Outcomes Short Form-36 (SF-36) UK English version questionnaire. Cross-sectional assessment of the QoL of a healthy control group with the SF-36.

RESULTS

The physical component summary (PCS) score was significantly reduced for the short mechanical ventilation (MV) group (n = 13) at 1 and 3 months compared to pre-admission status (p = 0.00, respectively). The mental component summary (MCS) score was significantly reduced at 1, 3 and 6 months (p = 0.00, respectively). The PCS and MCS were significantly reduced for the long MV group (n = 29) at all three assessments compared to the pre-admission HRQOL (p = 0.00-0.01). The short MV group reported HRQOL comparable to that of the healthy group (n = 40) at 6 months after discharge. The long MV group had a significant reduction in the PCS at 1, 3 and 6 months compared to the healthy group (p = 0.00, respectively). The long MV group had significantly reduced PCS at 3 and 6 months compared to the short MV group (p = 0.01 and 0.00, respectively).

CONCLUSIONS

Subjects who had higher morbidity and prolonged MV suffered from reduced HRQOL related to physical health for up to 6 months after discharge.

Determination of the Avogadro constant by counting the atoms in a 28Si crystal

The Avogadro constant links the atomic and the macroscopic properties of matter. Since the molar Planck constant is well known via the measurement of the Rydberg constant, it is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a definition of the kilogram in terms of a fundamental constant. We describe a new approach for its determination by counting the atoms in 1 kg single-crystal spheres, which are highly enriched with the 28Si isotope. It enabled isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, NA = 6.022,140,78(18) × 10(23) mol(-1), is the most accurate input datum for a new definition of the kilogram.

Intradermal tuberculin testing of wild African lions (Panthera leo) naturally exposed to infection with Mycobacterium bovis

African lions in the southern half of Kruger National Park (KNP) are infected with Mycobacterium bovis. Historically, reliable detection of mycobacteriosis in lions was limited to necropsy and microbiological analysis of lesion material collected from emaciated and ailing or repeat-offender lions. We report on a method of cervical intradermal tuberculin testing of lions and its interpretation capable of identifying natural exposure to M. bovis. Infected lions (n=52/95) were identified by detailed necropsy and mycobacterial culture. A large proportion of these confirmed infected lions (45/52) showed distinct responses to bovine tuberculin purified protein derivative (PPD) while responses to avian tuberculin PPD were variable and smaller. Confirmed uninfected lions from non-infected areas (n=11) responded variably to avian tuberculin PPD only. Various non-tuberculous mycobacteria (NTM) were cultured from 45/95 lions examined, of which 21/45 were co-infected with M. bovis. Co-infection with M. bovis and NTM did not influence skin reactions to bovine tuberculin PPD. Avian tuberculin PPD skin reactions were larger in M. bovis-infected lions compared to uninfected ones. Since NTM co-infections are likely to influence the outcome of skin testing, stricter test interpretation criteria were applied. When test data of bovine tuberculin PPD tests were considered on their own, as for a single skin test, sensitivity increased (80.8-86.5%) but false positive rate for true negatives (18.75%) remained unchanged. Finally, the adapted skin test procedure was shown not to be impeded by persistent Feline Immunodeficiency Virus(Ple) co-infection.

Atopy in HIV-infected children in Pretoria

INTRODUCTION

The development or aggravation of a pre-existing atopic state in patients with human immunodeficiency virus (HIV) has not been thoroughly investigated in South Africa. HIV-infected adults have been shown to have a higher prevalence of atopy in some international studies, but this has not been documented in children.

METHODS

A prospective convenience sample of 50 children aged between 3 months and 12 years attending the Tshwane District Hospital Paediatric HIV Clinic in Pretoria was recruited. Their personal and family histories of atopy, World Health Organization (WHO) HIV clinical staging and Centers for Disease Control (CDC) immunological staging with CD4 counts were documented. An age- and sex-matched control group of 50 HIV-negative children was included. Skin prick tests (SPTs) to identify common aeroallergens were conducted on all patients.

RESULTS

One hundred children were enrolled, with 50 in each group. Ten per cent of the HIV-infected patients compared with 16% of controls had positive SPTs to aeroallergens. A higher percentage of the HIV-infected patients had chronic rhinitis and eczema (60% and 68%, respectively). There was no relationship between CD4 count and positive SPTs (p = 0.61), mean log CD4 count and presence of reported asthma (p = 0.71), and CD4 count and presence of reported dermatitis (p = 0.84). The CD4 count was not statistically different between children with and without a family history of atopy (p = 0.68).

CONCLUSION

It appears that the stage of HIV disease does not influence the development or expression of allergy. There is a high prevalence of dermatitis and chronic rhinitis in HIV-infected children, probably not atopic in origin.

A contribution to borate crystal chemistry: Rules for the occurrence of polyborate anion types

The structural features of over 460 anhydrous oxoborates that are described in literature were analysed. Lewis acid strengths were calculated for all cations other than B3+ that were found in these structures, using the valences of the cations and their determined average coordination numbers. From the observation of a restriction of the occurrence of complex polyborate anions to specific ranges of cation Lewis acid strength in existing oxoborate compounds, the Lewis base strengths of the complex polyborate anions (not of the oxygen ligands) were inferred, using the idea that is at the bottom of the valence matching principle, that in the most stable compounds the Lewis acid strength of the cation nearly equals the Lewis base strength of the anion. From this, general inherent rules for the occurrence of the miscellaneous polyborate anions with respect to the ratio cation: boron (A:B), the Lewis acid strength(s) La of the cation(s) other than B3+ and the cation radii were developed. These rules offer the possibility for a prediction of the stoichiometry and the most probable polyborate structural group that will be adopted by a new anhydrous borate compound.

X-ray diffraction study of the piezoelectric properties of BiB3O6 single crystals

We have determined all eight components of the piezoelectric tensor of a monoclinic crystal, BiB3O6, by means of synchrotron X-ray diffraction technique. The experiments have been performed on a four circle goniometer using the ω-scan method introduced by Graafsma [1] which is universal in the choice of appropriate reflections. The determined values of the piezoelectric tensor are in good agreement with those obtained earlier for BiB3O6 with the use of an optical Michelson interferometer.