Self-planarized quantum-disks-in-nanowires ultraviolet-B emitters utilizing pendeo-epitaxy.

The growth of self-assembled, vertically oriented and uniform nanowires (NWs) has remained a challenge for efficient light-emitting devices. Here, we demonstrate dislocation-free AlGaN NWs with spontaneous coalescence, which are grown by plasma-assisted molecular beam epitaxy on an n-type doped silicon (100) substrate. A high density of NWs (filling factor >95%) was achieved under optimized growth conditions, enabling device fabrication without planarization using ultraviolet (UV)-absorbing polymer materials. UV-B (280-320 nm) light-emitting diodes (LEDs), which emit at ∼303 nm with a narrow full width at half maximum (FWHM) (∼20 nm) of the emission spectrum, are demonstrated using a large active region ("active region/NW length-ratio" ∼50%) embedded with 15 stacks of AlxGa1-xN/AlyGa1-yN quantum-disks (Qdisks). To improve the carrier injection, a graded layer is introduced at the AlGaN/GaN interfaces on both p- and n-type regions. This work demonstrates a viable approach to easily fabricate ultra-thin, efficient UV optoelectronic devices on low-cost and scalable silicon substrates.

Outcome of Living Donor Transplant Kidneys With Multiple Arteries.

BACKGROUND: Living donor transplantation (LDT) using kidneys with multiple arteries (MA) has previously been reported to be associated with increased complications and poorer outcomes in recipients. The objective of this study was to investigate outcomes of LDT with MA at the National University Hospital of Singapore, an institution with modest kidney transplant volumes. METHODS: From 2007 to 2014, a total of 109 consecutive living donor kidney transplantations were performed. Of the nephrectomies, 91% were left sided. A total of 19 cases involved MA, of which 7 with small polar vessels (<2 mm) were ligated and 12 were revascularized. Baseline characteristics and outcomes were comparable between donor-recipient pairs with MA and single artery (SA). Both groups had equivalent induction and maintenance immunosuppressive regimens. RESULTS: Mean warm ischemia time (minutes) was similar for kidneys with MA and SA (4.3 ± 3.2 vs 3.9 ± 3.2, P = .38). Operative time (minutes) in the recipients was also equivalent (P > .05) for MA and SA (158 ± 39.2 and 145 ± 57.2, respectively). The MA kidney recipients had a lower estimated glomerular filtration rate (eGFR) on postoperative day 5 compared to SA (56.6 ± 24.2 vs 74.1 ± 35.9 mL/min/1.73 m(2), P = .058). However, eGFR at 1 year was the similar for both groups (64.9 ± 16.2 vs 66.4 ± 18.1 mL/min/1.73 m(2), respectively, P = .76). Delayed graft function rates were 5.6% and 6.6% for MA and SA, respectively (P = .9). There were no surgical complications for LDT recipients within the MA group. Patient and graft survival was 100% in the MA group compared with 98% in the SA group (P > .05). CONCLUSIONS: With current surgical techniques, LDT with MA can achieve equally good functional outcomes at 1 year as SA kidneys, with minimal surgical complications.

Performance Evaluation of the Verigene Gram-Positive and Gram-Negative Blood Culture Test for Direct Identification of Bacteria and Their Resistance Determinants from Positive Blood Cultures in Hong Kong.

BACKGROUND: A multicenter study was conducted to evaluate the diagnostic performance and the time to identifcation of the Verigene Blood Culture Test, the BC-GP and BC-GN assays, to identify both Gram-positive and Gram-negative bacteria and their drug resistance determinants directly from positive blood cultures collected in Hong Kong. METHODS AND RESULTS: A total of 364 blood cultures were prospectively collected from four public hospitals, in which 114 and 250 cultures yielded Gram-positive and Gram-negative bacteria, and were tested with the BC-GP and BC-GN assay respectively. The overall identification agreement for Gram-positive and Gram-negative bacteria were 89.6% and 90.5% in monomicrobial cultures and 62.5% and 53.6% in polymicrobial cultures, respectively. The sensitivities for most genus/species achieved at least 80% except Enterococcus spp. (60%), K.oxytoca (0%), K.pneumoniae (69.2%), whereas the specificities for all targets ranged from 98.9% to 100%. Of note, 50% (7/14) cultures containing K.pneumoniae that were missed by the BC-GN assay were subsequently identified as K.variicola. Approximately 5.5% (20/364) cultures contained non-target organisms, of which Aeromonas spp. accounted for 25% and are of particular concern. For drug resistance determination, the Verigene test showed 100% sensitivity for identification of MRSA, VRE and carbapenem resistant Acinetobacter, and 84.4% for ESBL-producing Enterobacteriaceae based on the positive detection of mecA, vanA, blaOXA and blaCTXM respectively. CONCLUSION: Overall, the Verigene test provided acceptable accuracy for identification of bacteria and resistance markers with a range of turnaround time 40.5 to 99.2 h faster than conventional methods in our region.

Virgin olive oil, palm olein and coconut oil diets do not raise cell adhesion molecules and thrombogenicity indices in healthy Malaysian adults.

BACKGROUND/OBJECTIVES: Effects of high-protein diets that are rich in saturated fats on cell adhesion molecules, thrombogenicity and other nonlipid markers of atherosclerosis in humans have not been firmly established. We aim to investigate the effects of high-protein Malaysian diets prepared separately with virgin olive oil (OO), palm olein (PO) and coconut oil (CO) on cell adhesion molecules, lipid inflammatory mediators and thromobogenicity indices in healthy adults. METHODS: A randomized cross-over intervention with three dietary sequences, using virgin OO, PO and CO as test fats, was carried out for 5 weeks on each group consisting of 45 men and women. These test fats were incorporated separately at two-thirds of 30% fat calories into high-protein Malaysian diets. RESULTS: For fasting and nonfasting blood samples, no significant differences were observed on the effects of the three test-fat diets on thrombaxane B2 (TXB2), TXB2/PGF1α ratios and soluble intracellular and vascular cell adhesion molecules. The OO diet induced significantly lower (P<0.05) plasma leukotriene B4 (LTB4) compared with the other two test diets, whereas PGF1α concentrations were significantly higher (P<0.05) at the end of the PO diet compared with the OO diet. CONCLUSION: Diets rich in saturated fatty acids from either PO or CO and high in monounsaturated oleic acid from virgin OO do not alter the thrombogenicity indices-cellular adhesion molecules, thromboxane B2 (TXB2) and TXB2/prostacyclin (PGF1α) ratios. However, the OO diet lowered plasma proinflammatory LTB4, whereas the PO diet raised the antiaggregatory plasma PGF1α in healthy Malaysian adults. This trial was registered at clinicaltrials.gov as NCT 00941837.

Direct detection and prediction of all pneumococcal serogroups by target enrichment-based next-generation sequencing.

Despite the availability of standard methods for pneumococcal serotyping, there is room for improvement in the available methods, in terms of throughput, multiplexing capacity, and the number of serotypes identified. We describe a target enrichment-based next-generation sequencing method applied to nasopharyngeal samples for direct detection and serogroup prediction of all known serotypes of Streptococcus pneumoniae, 32 to the serotype level and the rest to the closely related serogroup level. The method was applied to detect and to predict the serogroups of pneumococci directly in clinical samples and from sweeps of primary culture DNA, with increased detection rates versus culture-based identification and agreement with the serotypes/serogroups determined by conventional serotyping methods. We propose this method, in conjunction with traditional serotyping methods, as an alternative to rapid detection and serotyping of pneumococci.

FPR1 interacts with CFH, HTRA1 and smoking in exudative age-related macular degeneration and polypoidal choroidal vasculopathy.

PURPOSE: To determine the genetic association of an inflammation-related gene, formyl peptide receptor 1 (FPR1), in exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV). METHODS: The coding region of FPR1 gene was sequenced in 554 unrelated Chinese individuals: 155 exudative AMD patients, 179 PCV patients, and 220 controls. Interactions and combined effects of FPR1 with complement factor H (CFH), high temperature requirement factor A1 (HTRA1), and smoking were also investigated. RESULTS: A total of 28 polymorphisms in FPR1 were identified. Single nucleotide polymorphisms (SNP) rs78488639 increased the risk to exudative AMD (P=0.043) and PCV (P=0.016), whereas SNP rs867229 decreased the risk to exudative AMD (P=0.0026), but not PCV. Homozygous G allele of rs1042229 was associated with exudative AMD (P=0.0394, odds ratio (OR)=2.27, 95% confident interval: 1.08-4.74), but not with PCV. Exudative AMD, but not PCV, was associated with the heterozygous genotypes of rs2070746 (P=0.019, OR=0.57) and rs867229 (P=0.0082, OR=0.54). Significantly, interactions were identified among FPR1 rs78488639, CFH rs800292, and HTRA1 rs11200638 in both exudative AMD and PCV. Combined heterozygous risk alleles of CFH rs800292 GA and FPR1 rs78488639 CA were posed to PCV (P=2.22 × 10(-4), OR=10.47), but not exudative AMD. Furthermore, FPR1 rs78488639 CA combining with HTRA1 rs11200638 and smoking was also predisposed risks to exudative AMD and PCV. CONCLUSION: FPR1 is associated with exudative AMD and PCV in a Hong Kong Chinese cohort. FPR1 rs78488639 interacted with CFH rs800292, HTRA1 rs11200638, and smoking, enhancing risk to exudative AMD and PCV.

Selective equal-spin Andreev reflections induced by Majorana fermions.

In this work, we find that Majorana fermions induce selective equal spin Andreev reflections (SESARs), in which incoming electrons with certain spin polarization in the lead are reflected as counterpropagating holes with the same spin. The spin polarization direction of the electrons of this Andreev reflected channel is selected by the Majorana fermions. Moreover, electrons with opposite spin polarization are always reflected as electrons with unchanged spin. As a result, the charge current in the lead is spin polarized. Therefore, a topological superconductor which supports Majorana fermions can be used as a novel device to create fully spin-polarized currents in paramagnetic leads. We point out that SESARs can also be used to detect Majorana fermions in topological superconductors.

Simultaneous quantum dash-well emission in a chirped dash-in-well superluminescent diode with spectral bandwidth >700 nm.

We report on the quantitative evidence of simultaneous amplified spontaneous emission from the AlGaInAs/InAs/InP-based quantum-well (Qwell) and quantum-dashes (Qdash) in a multistack dash-in-an-asymmetric-well superluminescent diode heterostructure. As a result, an emission bandwidth (full width at half-maximum) of >700 nm is achieved, covering entire O-E-S-C-L-U communication bands, and a maximum continuous wave output power of 1.3 mW, from this device structure. This demonstration paves a way to bridge entire telecommunication bands through proper optimization of device gain region, bringing significant advances and impact to a variety of cross-disciplinary field applications.

Detecting topological phases in cold atoms.

Chern insulators are band insulators which exhibit a gap in the bulk and gapless excitations in the edge. Detection of Chern insulators is a serious challenge in cold atoms since the Hall transport measurements are technically unrealistic for neutral atoms. By establishing a natural correspondence between the time-reversal invariant topological insulator and the quantum anomalous Hall system, we show for a class of Chern insulators that the topology can be determined by only measuring Bloch eigenstates at highly symmetric points of the Brillouin zone. Furthermore, we introduce two experimental schemes, including the spin-resolved Bloch oscillation, to carry out the measurement. These schemes are highly feasible under realistic experimental conditions. Our results may provide a powerful tool to detect topological phases in cold atoms.

Evaluation of the LightCycler methicillin-resistant Staphylococcus aureus (MRSA) advanced test for detection of MRSA nasal colonization.

Rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization is crucial for the prevention and control of MRSA infections in health care settings. The LightCycler MRSA Advanced Test (Roche Diagnostics) is a commercially available real-time PCR assay for direct detection of MRSA nasal colonization by targeting of the staphylococcal cassette chromosome mec (SCCmec)-orfX junction. The diagnostic performance of the assay was compared with that of ChromID MRSA agar (bioMérieux) culture and an in-house duplex real-time PCR assay. Among 1,246 nasal swab specimens collected from 2 general hospitals in Hong Kong, 174 (14%) were considered true positive for MRSA. Chromogenic culture and the in-house real-time PCR assay identified 147 (84.5%) and 133 (76.4%) true-positive cases with specificities of 100% and 98.6%, respectively. Based on the target melting temperature (Tm) values (57.0 to 62.0 °C) defined by the manufacturer, the LightCycler MRSA Advanced Test identified only 85 (48.9%) true-positive specimens. Interestingly, an additional 60 (34.5%) true-positive specimens were detected despite atypical Tm values of 55 °C, providing overall sensitivity and specificity values of 83.3% and 99%, respectively. Among isolates with Tm values of 55 °C, most were typed as clonal complex 45 (CC45). By sequence analysis of the SCCmec-orfX junction, characteristic single-nucleotide polymorphisms (SNPs) were identified only in isolates with Tm values of 55°C and not in those with typical Tm values. It is conceivable that those SNPs were located inside the target region of the proprietary hybridization probes, which resulted in a Tm shift in the melting curve analysis. Our study highlights the importance of a global evaluation of commercial kits so that the interpretation algorithm covers different lineages of MRSA clones prevalent in various geographical regions.

Hong Kong experiences the 'Ultimate superbug': NDM-1 Enterobacteriaceae.

We report the second imported case of New Delhi metallo-beta-lactamase (NDM-1) Enterobacteriaceae encountered in Hong Kong soon after the patient's arrival in the territory for medical care. As NDM-1 is spreading throughout the world via international travel, being an international city, Hong Kong was always expected to encounter the same public health threat. This case also illustrates the importance of active surveillance of at-risk patients in preventing the spread of this 'superbug'.

Use of red palm oil in local snacks can increase intake of provitamin A carotenoids in young aborigines children: a Malaysian experience.

INTRODUCTION: Carotenoid-rich red palm oil (RPO)-based snacks have been provided to children in impoverished communities to improve their vitamin A status. The non-availabilty of information on the acceptability of RPO-based snacks by Malaysian aborigines (Orang Asli) children forms the basis of this study. METHODS: Twenty-one Orang Asli children, majority of whom had normal body mass index for age (BMI-for-age) and aged 4.73 +/- 0.92 years in Sungai Tekir, Negeri Sembilan were provided with three freshly-prepared snacks (springroll, curry puff or doughnut) each containing one teaspoon or 5 ml of RPO per serving, on separate mornings. On the fourth morning, one serving each of all 3 different snacks was provided together on a plate to every child for consumption and preference for the snacks recorded. The children's habitual vitamin A intakes were assessed by a semi-quantitative food frequency questionnaire (FFQ) and carotenoid retention tests for the prepared snacks were performed by column chromatography. RESULTS: Fifty-four percent of the children did not meet their RNI for vitamin A. Based on acceptance criterion of consuming at least one-half serving of the snacks provided, springroll and curry puff recorded 100% acceptability while doughnut had 82% acceptability. Preference of snack was in the order, springroll (47%) > doughtnut (35%) > curry puff (18%), but a Z-test test for proportions showed no statistical significance. Carotenoid retention tests showed great variation between snacks namely, doughnut (100%) > springroll (84%) > curry puff (45%). CONCLUSION: The overall findings indicate that the RPO-based snacks are highly acceptable and can be used to improve the dietary intake of provitamin A carotenoids of Malaysian Orang Asli children.

Effect of the number of stacking layers on the characteristics of quantum-dash lasers.

A theoretical model is evaluated to investigate the characteristics of InAs/InP quantum dash (Qdash) lasers as a function of the stack number. The model is based on multimode carrier-photon rate equations and accounts for both inhomogeneous and homogeneous broadenings of the optical gain. The numerical results show a non monotonic increase in the threshold current density and a red shift in the lasing wavelength on increasing the stack number, which agrees well with reported experimental results. This observation may partly be attributed to an increase of inhomogeneity in the active region.

A double-blind randomised comparison of intravenous patient-controlled remifentanil with intramuscular pethidine for labour analgesia.

In a prospective, double-blind, randomised controlled trial, we compared the efficacy of patient-controlled analgesia using remifentanil (25-30 µg per bolus) with intramuscular pethidine (50-75 mg) for labour analgesia in 69 parturients. Parturients receiving patient-controlled analgesia reported less pain than those receiving intramuscular pethidine throughout the study period (p < 0.001), with maximal reduction in visual analogue pain score at 2 h after commencement of analgesia (mean (SD) 20 (17) in the patient-controlled analgesia group and 36 (22) in the intramuscular pethidine group. The median (95% CI) time to the first request for rescue analgesics was significantly longer with patient-controlled analgesia (8.0 (6.8-9.2) h) compared with intramuscular pethidine (4.9 (3.8-5.4) h, p < 0.001). Maternal satisfaction scores were also higher with remifentanil compared with intramuscular pethidine (p= 0.001). There was no report of sedation, aponea or oxygen desaturation in either group, and Apgar scores were similar between groups. We conclude that patient-controlled analgesia with remifentanil provides better labour analgesia and maternal satisfaction than intramuscular pethidine. At this dose, maternal and fetal side effects were uncommon.

Prevalence and risk factors for Chlamydia trachomatis infection among cross-border truck drivers in Hong Kong.

OBJECTIVES: To determine the prevalence and risk factors for chlamydial infection in cross-border truck drivers. METHODS: 225 Hong Kong-based cross-border truck drivers were screened for chlamydial infection. Associations between infection and potential risk factors were determined by questionnaire. RESULTS: 8.5% of drivers were positive for chlamydial infection. Of 62% of drivers reporting recent sex with commercial sex workers (CSW), 39% had not used condoms. 75% of drivers with extramarital sex partners (ESP) also frequented CSW and 47% of this group had not used condoms with CSW. 43.3% PCR-positive cases reported symptoms. No risk factor was associated with chlamydial infection after adjustment, although "had sex with ESP" approached significance. CONCLUSIONS: The prevalence of chlamydial infection among cross-border truck drivers was not strikingly high, although drivers engaged in sex with both ESP and CSW, with many admitting unprotected intercourse. The findings highlight the importance of promoting safe sex to truck drivers.

Molecular epidemiology of community-associated methicillin-resistant Staphylococcus aureus.

1. Community-associated methicillin-resistant Staphylococcus aureus (MRSA) strains with diverse genetic backgrounds are emerging in Hong Kong. 2. Intra-familial spread of community-associated MRSA is common.

Community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infections in Hong Kong.

Community-associated methicillin resistant Staphylococcus aureus is an emerging cause of skin and soft tissue infections in Hong Kong, especially among certain ethnic minorities.

Majorana fermion induced resonant Andreev reflection.

We describe experimental signatures of Majorana fermion edge states, which form at the interface between a superconductor and the surface of a topological insulator. If a lead couples to the Majorana fermions through electron tunneling, the Majorana fermions induce resonant Andreev reflections from the lead to the grounded superconductor. The linear tunneling conductance is 0 (2e(2)/h) if there is an even (odd) number of vortices in the superconductor. Similar resonance occurs for tunneling into the zero mode in the vortex core. We also study the current and noise of a two-lead device.