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Notes: Low-temperature reflectance data on epitaxial GaN thin-film samples covering the widest range of tensile and compressive stress (−3.8–3.5 kbar) thus far explicitly show the nonlinear behavior of the B–A and C–A splittings versus the energy of the A exciton. Lineshape ambiguities that hindered previous interpretations have been resolved with reciprocal-space analysis, allowing us to obtain band parameters such as ΔSO=17.0±1meV with increased confidence. © 1997 American Institute of Physics.

Notes: A new form of light emitting devices called BICE (bias induced color-tunable emitter) is reported. It is a voltage controlled multiwavelength semiconductor light emitter based on the bias dependent injection and collection of electrons and holes in quantum wells. In this letter, two-terminal dual wavelength BICE operation is demonstrated. It exhibits coaxial optical output, a large separation between emission wavelengths ((approximately-greater-than)500 A(ring)) and an emission contrast ratio ranging from 4:1 to 1:33 at 77 K.

Notes: We discuss trends in residual stress as a function of film thickness, growth temperature, and substrate orientation for GaN/AlN/6H–SiC heterostructures. Films are mostly compressive for samples less than about 0.7 μm thick, are tensile up to about 2 μm, then abruptly become less tensile with stress values near 1 kbar thereafter. We interpret this as a successive relief of lattice mismatch and thermal stresses culminating in a catastrophic relief by unknown mechanisms at moderate thicknesses. These data indicate that relaxation processes in these heterostructures are not as well understood as previously supposed. © 1998 American Institute of Physics.

Notes: Spectroscopic ellipsometry was used to assess the preparation of smooth and abrupt GaN, AlN, and AlGaN surfaces by wet chemical treatments in real time. About 20–50 A(ring) of overlayer typically can be removed from air-exposed samples. © 1996 American Institute of Physics.

Notes: Temperature-dependent time-resolved photoluminescence measurements were performed on GaN film/AlN buffer/6H–SiC substrate heterostructures grown by metalorganic chemical vapor deposition. The overlying GaN layers were under tension, as estimated from the free A exciton (FEA) position. The recombination lifetimes were determined for the FEA and for the neutral-donor-bound exciton (D0X). We observed that the recombination lifetime for the FEA has the same value of 40–50 ps in all the layers, whereas the recombination time for the D0X varies for different samples. We observed that the recombination lifetimes for D0X have a clear dependence on the position of FEA, i.e., the recombination lifetime increases with decreasing strain in the layers. We discuss the results in term of the hole states involved in the donor-bound exciton recombination. © 2001 American Institute of Physics.

Notes: The effect of feedlot runoff on the environmental quality of the Cottonwood River in east central Kansas was evaluated by analysis of community structure of benthic macroinvertebrates using the species diversity index, (d). The benthic fauna along the study reach was dominated by mayflies, caddisflies, midges, riffle beetles, and the pelecypod, Sphaerium. Sixty-five taxa were identified during the study; the benthic fauna was most abundant during the 1968–69 segment of the study. However, the mean 3 per station indicated the river was subject to moderate environmental stress, and 3's of those stations immediately downstream from feedlots were significantly lower than the 3 at the control station. There was a significant increase in d's during the 1970–71 segment of the study, following the closing of two feedlots. The results indicate periodic feedlot runoff had a continuing adverse affect on the environmental quality of the river, but recovery was rapid as the organic load on the river was reduced.

Notes: Background:  Home-like birth settings have been established in or near conventional labour wards for the care of pregnant women who prefer and require little or no medical intervention during labour and birth.Objectives:  Primary: to assess the effects of care in a home-like birth environment compared to care in a conventional labour ward. Secondary: to determine if the effects of birth settings are influenced by staffing or organizational models or geographical location of the birth centre.Search strategy:  We searched the Cochrane Pregnancy and Childbirth Group trials register (18 May 2004) and handsearched eight journals and two published conference proceedings.Selection criteria:  All randomized or quasi-randomized controlled trials that compared the effects of a home-like institutional birth environment to conventional hospital care.Data collection and analysis:  Standard methods of the Cochrane Collaboration Pregnancy and Childbirth Group were used. Two review authors evaluated methodological quality. Double data entry was performed. Results are presented using relative risks and 95% confidence intervals.Main results:  Six trials involving 8677 women were included. No trials of freestanding birth centres were found. Between 29% and 67% of women allocated to home-like settings were transferred to standard care before or during labour. Allocation to a home-like setting significantly increased the likelihood of: no intrapartum analgesia/anaesthesia (four trials; n = 6703; relative risk (RR) 1.19, 95% confidence interval (CI) 1.01 to 1.40), spontaneous vaginal birth (five trials; n = 8529; RR 1.03, 95% CI 1.01 to 1.06), vaginal/perineal tears (four trials; n = 8415; RR 1.08, 95% CI 1.03 to 1.13), preference for the same setting the next time (one trial; n = 1230; RR 1.81, 95% CI 1.65 to 1.98), satisfaction with intrapartum care (one trial; n = 2844; RR 1.14, 95% CI 1.07 to 1.21), and breastfeeding initiation (two trials; n = 1431; RR 1.05, 95% CI 1.02 to 1.09) and continuation to six to eight weeks (two trials; n = 1431; RR 1.06, 95% CI 1.02 to 1.10). Allocation to a home-like setting decreased the likelihood of episiotomy (five trials; n = 8529; RR 0.85, 95% CI 0.74 to 0.99). There was a trend towards higher perinatal mortality in the home-like setting (five trials; n = 8529; RR 1.83, 95% CI 0.99 to 3.38). No firm conclusions could be drawn regarding the effects of staffing or organizational models.Authors’ conclusions:  When compared to conventional institutional settings, home-like settings for childbirth are associated with modest benefits, including reduced medical interventions and increased maternal satisfaction. Caregivers and clients should be vigilant for signs of complications.Citation:  Hodnett ED, Downe S, Edwards N, Walsh D. Home-like versus conventional institutional settings for birth. The Cochrane Database of Systematic Reviews 2005, Issue 1. Art. No.: CD000012.pub2. DOI: 10.1002/14651858.CD000012.pub2.

Notes: The utilisation of the pre-operative ECG in patients undergoing routine surgery was investigated in 354 adult patients over a 2-week period. Sixty-four percent of patients had an ECG pre-operatively. An ECG was not performed in 17% of patients who, current hospital policy suggests, should have had one. In contrast, an ECG was performed in 33% of patients who, hospital policy suggests, have no need of one (all of which were normal), which represented 18% of the total number of pre-operative ECGs performed. In 62% of patients with known cardiac disease, and 44% of patients with strong risk factors for ischaemic heart disease (in the absence of known disease) the ECG was abnormal. This compares with only 7% of patients aged over 50 with no risk factors in whom the ECG was abnormal. These findings suggest that there is room for improvement in the utilisation of the pre-operative ECG, which may have cost implications.

Notes: A previously fit 20-year-old man presented with a large haemothorax following a stab wound to the left chest. Pre-operative airway assessment indicated that tracheal intubation would be routine. On induction of anaesthesia, visualisation of the larynx proved impossible because of soft tissue swelling. Successful intubation was eventually achieved with the aid of a gum elastic bougie. At operation, the patient's common carotid artery was found to have been perforated close to its origin on the aorta. The patient made an uneventful recovery.

Notes: A double-blind randomised study was performed to assess the value of the addition of pethidine 50 mg to the initial dose of bupivacaine given for epidural analgesia in labour. Forty-nine patients received either I ml of saline (n = 24), or 50 mg of pethidine (n = 25), added to 9 ml of 0.25% bupivacaine as an initial injection for intrapartum epidural analgesia. There was a significant increase in the mean duration of analgesia in the pethidine group. However, pethidine did not increase the speed of onset of analgesia, or improve the quality of analgesia.