Realization of Vertically Aligned, Ultrahigh Aspect Ratio InAsSb Nanowires on Graphite.

The monolithic integration of InAs(1-x)Sb(x) semiconductor nanowires on graphitic substrates holds enormous promise for cost-effective, high-performance, and flexible devices in optoelectronics and high-speed electronics. However, the growth of InAs(1-x)Sb(x) nanowires with high aspect ratio essential for device applications is extremely challenging due to Sb-induced suppression of axial growth and enhancement in radial growth. We report the realization of high quality, vertically aligned, nontapered and ultrahigh aspect ratio InAs(1-x)Sb(x) nanowires with Sb composition (xSb(%)) up to ∼12% grown by indium-droplet assisted molecular beam epitaxy on graphite substrate. Low temperature photoluminescence measurements show that the InAs(1-x)Sb(x) nanowires exhibit bright band-to-band related emission with a distinct redshift as a function of Sb composition providing further confirmation of successful Sb incorporation in as-grown nanowires. This study reveals that the graphite substrate is a more favorable platform for InAs(1-x)Sb(x) nanowires that could lead to hybrid heterostructures possessing potential device applications in optoelectronics.

Charged nano-domes and bubbles in epitaxial graphene.

For the first time, new epitaxial graphene nano-structures resembling charged 'bubbles' and 'domes' are reported. A strong influence, arising from the change in morphology, on the graphene layer's electronic, mechanical and optical properties has been shown. The morphological properties of these structures have been studied with atomic force microscopy (AFM), ultrasonic force microscopy (UFM) and Raman spectroscopy. After initial optical microscopy observation of the graphene, a detailed description of the surface morphology, via AFM and nanomechanical UFM measurements, was obtained. Here, graphene nano-structures, domes and bubbles, ranging from a few tens of nanometres (150­200 nm) to a few µm in size have been identified. The AFM topographical and UFM stiffness data implied the freestanding nature of the graphene layer within the domes and bubbles, with heights on the order of 5­12 nm. Raman spectroscopy mappings of G and 2D bands and their ratio confirm not only the graphene composition of these structures but also the existence of step bunching, defect variations and the carrier density distribution. In particular, inside the bubbles and substrate there arises complex charge redistribution; in fact, the graphene bubble­substrate interface forms a charged capacitance. We have determined the strength of the electric field inside the bubble­substrate interface, which may lead to a minigap of the order of 5 meV opening for epitaxial graphene grown on 4H-SiC face-terminated carbon.

Intermediate ice scour disturbance is key to maintaining a peak in biodiversity within the shallows of the Western Antarctic Peninsula.

Climate-related disturbance regimes are changing rapidly with profound consequences for ecosystems. Disturbance is often perceived as detrimental to biodiversity; however, the literature is divided on how they influence each other. Disturbance events in nature are diverse, occurring across numerous interacting trophic levels and multiple spatial and temporal scales, leading to divergence between empirical and theoretical studies. The shallow Antarctic seafloor has one of the largest disturbance gradients on earth, due to iceberg scouring. Scour rates are changing rapidly along the Western Antarctic Peninsula because of climate change and with further changes predicted, the Antarctic benthos will likely undergo dramatic shifts in diversity. We investigated benthic macro and megafaunal richness across 10-100 m depth range, much of which, 40-100 m, has rarely been sampled. Macro and megafauna species richness peaked at 50-60 m depth, a depth dominated by a diverse range of sessile suspension feeders, with an intermediate level of iceberg disturbance. Our results show that a broad range of disturbance values are required to detect the predicted peak in biodiversity that is consistent with the Intermediate Disturbance Hypothesis, suggesting ice scour is key to maintaining high biodiversity in Antarctica's shallows.

The impact of trained assistance on error rates in anaesthesia: a simulation-based randomised controlled trial.

Trained assistance for the anaesthetist appears likely to improve safety in anaesthesia. However, there are few objective data to support this assumption, and the requirement for a trained assistant is not universally enforced. We applied a simulation-based model developed in previous work to test the hypothesis that the presence of a trained assistant reduces error in anaesthesia. Ten randomly selected anaesthetists, five trained anaesthetic technicians and five theatre nurses without training in anaesthesia participated in two simulated emergencies, with anaesthetists working alternately with a technician or a nurse. The mean (SD) error rate per scenario was 4.75 (2.9). There were significantly fewer errors in the technician group than the nurse group (33 vs 62, p = 0.01) and this difference remained significant when errors were weighted for severity. This provides objective evidence supporting the requirement for trained assistance to the anaesthetist, and furthermore, demonstrates that a simulation-based model can provide rigorous evidence on safety interventions in anaesthesia.

A simulation design for research evaluating safety innovations in anaesthesia*.

SUMMARY: It is notoriously difficult to obtain evidence from clinical randomised controlled trials for safety innovations in healthcare. We have developed a research design using simulation for the evaluation of safety initiatives in anaesthesia. We used a standard and a modified scenario in a human-patient simulator, involving a potentially life-threatening problem requiring prompt attention--either a cardiac arrest or a failure in oxygen supply. The modified scenarios involved distractions such as loud music, a demanding and uncooperative surgeon, telephone calls and frequent questions from a medical student. Twenty anaesthetics were administered by 10 anaesthetists. A mean (SD) of 11.3 (2.8) errors per anaesthetic were identified in the oxygen failure scenarios, compared with 8.0 (3.4) in the cardiac arrest scenarios (ANOVA: p = 0.04). The difference between the combined standard scenarios and the combined modified scenarios was not significant. The mean rate of errors overall was 9.7 per simulation, with a pooled SD of 4.46, so in future studies 21 subjects would provide 80% statistical power to show a reduction in error rate of 30% from baseline with p

Use of antithymocyte globulin (dose by rosette protocol) in pediatric renal allograft recipients.

Total rosette-forming cells (TRFCs) and percentage of rosette-forming cell (RFC) levels were measured in patients undergoing dialysis and in recipients following renal transplantation. The percentage of RFCs of the dialysis patients was not different from the percentage of RFCs of normal subjects, whereas the TRFCs were significantly lower in the dialysis patients. After transplantation, the percentage of RFCs and TRFCs was significantly lower in recipients treated with antithymocyte globulin (ATG) than in those of the control group; however, there was no difference in allograft survival between the ATG-treated and control recipients when using ATG in the dose by rosette protocol.

Postnatal development of corneal endothelium.

Comparison specular micrographs of infant and adult corneas from cats, cows, dogs, rabbits, and humans demonstrate that a large decrease in central endothelial cell density occurs during maturation of the cornea. Central endothelial cell counts of developing cat, dog, and rabbit corneas decrease rapidly during the first months of life. This rapid decline in endothelial cell density correlates with growth of the cornea to the adult size. Central endothelial cell counts of adult cat, cow, deer, dog, pig, rabbit, and human corneas are similar (2500 cells/mm2) despite a wide variation in corneal size. Comparison of observed endothelial cell counts with two hypothetical situations, one of unrestricted endothelial mitosis and the other of only endothelial hypertrophy, indicates that hypertrophy of individual cells is primarily responsible for achieving the adult cell density of 2500 cells/mm2 for these species. This observation is true for species that have a high adult endothelial mitotic capacity (rabbit) as well as those that do not (cat). The human cornea is a special case because the decline in central endothelial cell density indicates that a large apparent corneal endothelial cell loss (approximately 45%) occurs early in postnatal development.

Is resection of pulmonary and hepatic metastases warranted in patients with colorectal cancer?

BACKGROUND: Conventional management of stage IV colorectal carcinoma is palliative. The value of resecting both liver and lung colorectal metastases that occur in isolation of other sites of metastasis is undetermined. OBJECTIVES: Our objectives were to (1) assess the efficacy of resecting both hepatic and pulmonary metastases, (2) investigate the influence of the sequence and timing of metastases, and (3) identify the profile of patients likely to benefit from both hepatic and pulmonary metastasectomy. PATIENTS AND METHODS: Of 48 patients identified with resection of colorectal cancer and, at some point in time, both liver and lung metastases, 25 patients underwent metastasectomy (resection group). The remaining 23 patients comprised the nonresection group. Risk factors for death were identified by multivariable analyses. RESULTS: Median survival was longer after the last metastatic appearance in the resection group (16 months) than in the nonresection group (6 months; P <.001). The pattern of risk also differed; it peaked at 2 years and then declined in the resection group but was constant in the nonresection group. In the resection group, patients with metachronous resections survived longer after colorectal resection (median, 70 months) than patients with synchronous (median, 22 months) or mixed resections (median, 31 months; P <.001). Risk factors for death included older age, multiple liver metastases, and a short disease-free interval. CONCLUSIONS: Younger patients with solitary metachronous metastases to the liver, then the lung, and long disease-free intervals are more likely to benefit from resection of both liver and lung metastases. Patients with risk factors also had better survival with resection than without resection.

Pretransplant T cell levels and renal allograft survival rates.

Total rosette forming cell (TRFC) levels were measured in 50 patients awaiting cadaveric renal transplantation. Preliminary data show a statistically significant difference in allograft survival in patients with low TRFC levels before transplant as compared with patients with medium or high TRFC levels. Pretransplant TRFC levels may be predictive of a nonresponder status and portend a favorable renal allograft outcome.

Mechanism of ethanol-induced vasodilation.

The mechanism by which ethanol ingestion causes dermal vasodilation is unclear, but it may result from a direct action on central vascular control mechanisms. Forearm blood flow and peripheral skin temperatures were examined in five quadriplegics (lesions above T7) and five control subjects, before and after the ingestion of ethanol (0.75 ml/kg body wt). The lack of vasomotor efferent function was confirmed in the quadriplegics by the absence of vasodilation in response to radiant heating of the torso. There were no significant changes in peripheral temperatures or forearm blood flow after ethanol in the quadriplegics. The control subjects had a significant increase in forearm blood flow (1.12 +/- 0.2 ml.min-1.100 ml-1) and skin temperature (finger 2.4 +/- 0.4 degrees C, toe 3.4 +/- 0.3 degrees C) after ethanol. These data suggest that ethanol may induce peripheral vasodilation by modulation of central vasomotor control mechanisms.

The misuse of buprenorphine and a buprenorphine-naloxone combination in Wellington, New Zealand.

Two surveys of 12 months duration were undertaken on opioid users presenting to the Wellington Alcohol and Drug Centre before and after the introduction of a combination buprenorphine 0.2 mg-naloxone 0.17 mg tablet (Bu-Nx), which was launched in 1991 in the hope of reducing intravenous misuse. There was considerable intravenous (i.v.) misuse of buprenorphine 0.2 mg tablets (Bu) in 1990 with self-reports of misuse in 81% of the patients over the 4 weeks prior to presentation, and 65% of the patients had buprenorphine in their urine. In the repeat survey 57% reported misuse of the Bu-Nx combination over the previous 4 weeks, and 43% had buprenorphine +/- naloxone detected in their urine. There was a reduction in the street price of Bu-Nx. One-third of the patients who used Bu-Nx i.v. reported instances of withdrawal symptoms, and subjectively the drug was less attractive to misusers. The combination product may have less misuse potential than buprenorphine alone, but it remains a preparation, in the dosages employed, that is intravenously misused.

No improvement in ethanol-induced memory deficits after administration of a vasopressin analog.

Acute ingestion of ethanol impairs memory, an effect which might be related to ethanol-induced inhibition of vasopressin release. This was studied using tests of memory and cognitive function in 26 normal subjects before and after ethanol ingestion. Equal numbers of subjects received randomly, by double-blind intranasal administration, placebo or 1-desamino-8-D-arginine vasopressin prior to ethanol ingestion. Administration of the vasopressin analog did not reverse the ethanol-induced deficits in memory and cognitive function.

Dislocation of the bearing of the Oxford lateral unicompartmental arthroplasty. A radiological assessment.

When the Oxford unicompartmental meniscal bearing arthroplasty is used in the lateral compartment of the knee, 10% of the bearings dislocate. A radiological review was carried out to establish if dislocation was related to surgical technique. The postoperative radiographs of 46 lateral unicompartmental arthroplasties were analysed. Five variables which related to the position and alignment of the components were measured. Dislocations occurred in six knees. Only one of the five variables, the proximal tibial varus angle, had a statistically significant relationship to dislocation. This variable quantifies the height of the lateral joint line. The mean proximal tibial varus angle for knees the bearings of which had dislocated was 9 degrees and for those which had not it was 5 degrees. In both groups it was greater than would be expected in the normal knee (3 degrees). Our study suggests that a high proximal tibial varus angle is associated with dislocation. The surgical technique should be modified to account for this, with care being taken to avoid damage to or overdistraction of the lateral soft tissues.

Antibodies to donor B lymphocytes and autoantibodies in renal transplantation.

A positive CDC B-lymphocyte XM is not deleterious to long-term graft outcome. A positive unfractionated CDC XM is not a contraindication to transplantation if the positive crossmatch is due entirely to anti-B-lymphocyte antibody. B-lymphocyte autoantibodies are common in hemodialysis patients, but may account for only a minority of positive B-lymphocyte XMs.

Detection of problem-drinkers in an emergency department using a breathalyser and questionnaire.

Over a 2-week period in January 1990 consecutive adult emergency attenders were breathalysed and screened for problem drinking using the WHO screening instrument. Results were compared with a similar study conducted 8 years previously. Of the patients tested, 12.5% had a positive alcohol in 1990 compared with 16% in 1982. Of those with positive alcohol results, the mean blood alcohol equivalent (BAE) concentration was significantly (p=0.0006) lower in 1990 (73.6+/-65.1; mg/100 ml; mean+/-SD) when compared to those levels found in 1982 (136.9+/-102.4 mg/100 ml). There was also significant reductions in 1990 of positive breath alcohol attenders both from road traffic accidents (p<0.03), and from head injuries (p<0.005) compared to 1982. In 1990 the questionnaire was positive in 23% of attendees. These studies suggest a trend towards less alcohol misuse in emergency department patients, but nevertheless indicate high rates of problem drinking. It is suggested that alcohol breathalysers be available in emergency departments to assist the detection of alcohol misusers and predict alcohol-associated medical problems.

Mortality of intravenous drug users: attenders of the Wellington Drug Clinic, 1972-89.

A mortality study of 997 patients registered for treatment at the Wellington Drug Clinic since 1971 was undertaken by examining the New Zealand death records. Sixty-seven known deaths were reported. The mortality rates were increased 11.5 times under the age of 25 years, and 5.8 times for age 25-34 years, but not significantly thereafter. There were 7 deaths from trauma, 8 from suicide, and 28 accidental deaths. Myocarditis was the cause of death in four cases. In the 28 drug-related deaths the principle drugs incriminated were dextropropoxyphene, barbiturates, chloral hydrate, methadone and other opiates. Twenty-one deaths were due to unrelated diseases. It was considered important to document mortality in intravenous drug users in the 'pre-HIV' era. This study demonstrates quite low death rates from opioid drugs themselves.

Defining the femoral axis on lateral knee fluoroscopy.

The methodological detail about determining the femoral axis on lateral fluoroscopic images of the knee is lacking. This paper reports on the use of the posterior border of the lower femoral diaphysis to represent the axis. This method is accurate, simple, reliable and can be used by researchers studying knee joint kinematics using dynamic video fluoroscopy. It is also useful in the outpatient clinic to assess the flexion/extension position of femoral components after knee arthroplasty.

A kinematic study of lateral unicompartmental arthroplasty.

When the Oxford unicompartmental meniscal bearing arthroplasty (UCA) is used in the lateral compartment 10% of the bearings dislocate. A fluoroscopic study was performed to investigate if abnormal mid-sagittal plane kinematics was related to bearing dislocation. Video fluoroscopy is an accepted means of determining in-vivo knee kinematics in the sagittal plane. Video fluoroscopy was obtained of 5 Oxford lateral UCAs 10 years post-operatively and of five normal knees. Patellar tendon angle (PTA), derived from dynamic fluoroscopic images, was used to describe the joint kinematics. This in-vivo experiment demonstrated that the PTA/knee relationship for the Oxford lateral UCA is similar to the normal knee. Both the normal knee (r(2)=0.99) and the Oxford lateral UCA (r(2)=0.98) demonstrated a linear relationship between flexion angle and PTA. No significant difference in PTA was found between the normal knee and the Oxford lateral UCA. This study demonstrated normal kinematics, as indicated by PTA, ten years after implantation of the Oxford lateral UCA. It is therefore reasonable to suggest that abnormal kinematics is not a significant factor relating to meniscal bearing dislocation in the lateral compartment.

Hepatitis C prevalence and needle/syringe sharing behaviours in recent onset injecting drug users.

AIM: To investigate the prevalence of hepatitis C antibody (anti-HCV) in injecting drug users (IDU), particularly amongst those of recent onset beginning since the advent of the needle-exchange programme. Secondly this study sought information on needle-sharing practices. METHODS: The records of injecting drug users over 2 years from January 1992 were examined for anti-HCV results and needle-sharing reports on initial assessment at the Wellington drug dependency clinic. RESULTS: Amongst 110 injecting drug users 92 (84%) were tested for anti-HCV, and 71 (77%) were positive. There was a significant (p = 0.02) association between the reported duration of intravenous drug misuse and the proportion of injecting drug users who were positive for anti-HCV. Of those injecting drug users who had reported use of less than 4 years, since the introduction of the New Zealand needle exchange programme, 53% were positive for anti-HCV. Needle-sharing was frequently reported to have ever occurred in 74% of these patients at some time, and in 64% of those who reported use of less than 4 years. These differences were not significant. However, in the period before presenting 67% had not shared over the last 3 months and 57% had not shared over the previous 1 year, which are improvements on previous studies of needle-sharing, considered to be the most important mode of transmission for blood-borne viruses in injecting drug users. CONCLUSIONS: These results suggest considerable potential for HIV infection rates among injecting drug users in New Zealand to increase from the current low level. There needs to be continuing emphasis on public health programmes to eradicate needle-sharing, and to promote safe injecting techniques for injecting drug users.

Wellington coroner autopsy cases 1970-89: acute deaths due to drugs, alcohol and poisons.

Coronal autopsy reports attributing deaths to drugs or poisonings were examined for the period 1970-89. There were 239 deaths of which 69% were suicide, 23% were accidental, 4% therapeutic misadventure, and 4% of uncertain category. 10.4% of deaths were due solely to alcohol and alcohol was found in another 13% of deaths from other drugs and poisons [corrected]. Twenty-seven percent of deaths were attributed to carbon monoxide poisoning. Five percent of deaths were due to poisons. Prescription drugs were the cause of deaths in 54% with the principle drug classes being opioids (14%), tricyclic antidepressants (12%), barbiturates (11%), hypnosedatives (8%). Prescribers need to be aware of the interactions of such drugs with alcohol, and to consider safer alternative drugs for those at risk of overdose or drug misuse.