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Objective To determine the frequency and pattern of cerebellar haemorrhage (CBH) on routine cranial ultrasound (cUS) imaging in infants of =32 weeks gestation, and to investigate how extremely preterm infants with CBH differ from those with severe intraventricular haemorrhage (IVH). Methods 672 infants of =32 weeks gestation were prospectively examined for CBH on serial cUS imaging. In a separate case-control analysis, the clinical features, ultrasound findings and outcome of preterm infants with CBH were compared to those of infants with isolated severe IVH (grade III-IV). Results Nine cases of CBH were identified among 53 infants with severe IVH. The incidence of CBH in infants of ⩽32 weeks gestation was 1.3%. Five infants had bilateral CBH involving both hemispheres, three had unilateral left sided CBH and one had a right hemispheric lesion. Infants with CBH were male, signifi cantly more preterm (24.4 vs 27.0 weeks) and of lower birth weight (692 g vs 979 g). Vaginal births predominated in the CBH group (89% vs 50%). The median time to identification of haemorrhage for both groups was 3 days. Mortality in the CBH group was 100% (9/9) compared to 43% (19/44) in the severe IVH group. Conclusions Extensive CBH in preterm infants is rare and devastating. It appears to be confined to very preterm, extremely low birthweight infants and may have a male predominance. The co-existence of severe IVH and extensive CBH on routine cot-side cUS in the early neonatal period is an ominous finding. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to examine emergency department (ED) nurses' attitudes towards individuals presenting with deliberate self-harm (DSH), including the relationship between attitudes and factors such as age, academic achievements, length of experience, and self-harm education. Method: The study adopted a quantitative descriptive and correlational design. ED nurses' attitudes, working in a level 1 trauma ED in the Republic of Ireland, were surveyed, using an amended version of McAllister's et al. [McAllister, M., Creedy, D., Moyle, W., Farrugia, C., 2002. Nurses' attitudes towards clients who self-harm. Journal of Advanced Nursing 40(5), 578-586.] Attitude Towards Deliberate Self-Harm Questionnaire (ADSHQ). The survey yielded an 85% (n = 68) response rate. Results: The study found that ED nurses held positive attitudes towards individuals presenting with DSH. No correlation was found between total scores and gender, ED experience, or a history of self-harm education, although older nurses and hospital trained nurses had less positive attitudes. Age and length of clinical experience produced a trend in which attitudes increased, reached a peak and then declined. Conclusion: Although ED nurses in this study hold positive attitudes, ongoing continuing education, which was identified as a key theme in the study, remains an important strategy to maintain and further improve attitudes. The need for research into aspects of care such as knowledge, awareness and empathy is recommended, as is the need to evaluate the extent to which the National Strategy for Suicide Prevention 2005DS2014 recommendations [Department of Health and Children, Health Service Executive, National Suicide Review Group 2005. Reach Out -- Irish National Strategy for Action on Suicide Prevention 2005-2014. (accessed 22.02.08)] have been implemented. [ABSTRACT FROM AUTHOR]

This paper reports results of scanning ion probe studies of silicon implantation profiles in source and drain regions of AlGaN/GaN high-electron-mobility transistor (HEMT) heterostructures. It is shown that both the undoped channel length and the transition region between implanted and nonimplanted regions become wider with increasing depth in the structure. These results may explain the previously reported existence of resistance associated with the transition region between implanted and non-implanted semiconductor regions in AlGaN/GaN HEMT heterostructures with non-alloyed Si-implanted source and drain ohmic contact regions. [ABSTRACT FROM AUTHOR]

This paper reports results of a study of non-alloyed ohmic contacts on Si-implanted AlGaN/GaN heterostructures, obtained from current-voltage characteristics of transfer-length method (TLM) test structures. It is shown that the measured contact resistance from the Ti/Au/Ni metal contacts, deposited on Si-implanted regions, to the two-dimensional electron gas channel at the AlGaN/GaN heterointerface of the non-implanted region, is formed by three different components: (i) contact resistance between the metal and the semiconductor (0.60 ± 0.16 Ω mm), (ii) resistance of the implanted region (0.62 ± 0.03 Ω mm) and (iii) an additional resistance (0.72 ± 0.24 Ω mm) giving a total value of 1.9 ± 0.3 Ω mm. The specific ohmic contact resistance was determined to be (2.4 ± 0.5) x 10-5 X cm². [ABSTRACT FROM AUTHOR]

Migraine is a prevalent neurovascular disease with a significant genetic component. Linkage studies have so far identified migraine susceptibility loci on chromosomes 1, 4, 6, 11, 14, 19 and X. We performed a genome-wide scan of 92 Australian pedigrees phenotyped for migraine with and without aura and for a more heritable form of “severe” migraine. Multipoint non-parametric linkage analysis revealed suggestive linkage on chromosome 18p11 for the severe migraine phenotype (LOD*=2.32, P=0.0006) and chromosome 3q (LOD*=2.28, P=0.0006). Excess allele sharing was also observed at multiple different chromosomal regions, some of which overlap with, or are directly adjacent to, previously implicated migraine susceptibility regions. We have provided evidence for two loci involved in severe migraine susceptibility and conclude that dissection of the “migraine” phenotype may be helpful for identifying susceptibility genes that influence the more heritable clinical (symptom) profiles in affected pedigrees. Also, we concluded that the genetic aetiology of the common (International Headache Society) forms of the disease is probably comprised of a number of low to moderate effect susceptibility genes, perhaps acting synergistically, and this effect is not easily detected by traditional single-locus linkage analyses of large samples of affected pedigrees. [ABSTRACT FROM AUTHOR]

A practical limitation to the identification of genetic profiles predictive of drug-induced adverse events is the number of patients with the adverse event that can be tolerated before the drug is withdrawn. Whole genome screening for regions of linkage disequilibrium (LD) associated with a particular phenotype may provide the mechanism to rapidly discover specific and sensitive profiles. We have used data from a large phase III clinical trial of tranilast and typed 76 SNPs over a 2.7 megabase region flanking the uridine diphosphate glucuronosyltranserferase 1A1 gene. Three SNPs within one LD block showed strong association with tranilast-induced hyperbilirubinemia (P<10-13). Our data illustrated that a genome-wide LD scan of 100?000-200?000 SNPs is sufficient to identify a pharmacogenetic association with a drug-induced adverse event.The Pharmacogenomics Journal (2004) 4, 374-378. doi:10.1038/sj.tpj.6500268 Published online 10 August 2004 [ABSTRACT FROM AUTHOR]

Inductively coupled plasma (ICP) etching of GaN with high selectivity over Al.22 Ga.78N in BCl3/SF6 mixtures has been studied. Selectivity and surface morphology were investigated over a wide range of pressures (3.75-37.5mTorr), RF powers (30-120 W), ICP powers (100-400 W), and SF6/BCl3 ratios (0.1 -0.7). Higher pressures, lower dc biases, and higher SF6/BCl3 ratios increased the GaN to AlGaN selectivity. Selectivities up to 25 were measured by laser interferometry. A root mean square (rms) surface roughness of 0.67 nm was measured by atomic force microscopy (AFM) after removal of 0.5 μm from a GaN template (process selectivity: 15, as-grown rms surface roughness: 0.56 nm). A degradation in surface morphology, with the gradual formation of pits, was observed for selectivities above 10. [ABSTRACT FROM AUTHOR]

The use of AlGaN/GaN HEMTs and HBTs for switching power supplies is explored. With its high electron velocities and breakdown fields, GaN has great potential for power switching. The field-plate HEMT increased breakdown voltages by 20% to 570V by reducing the peak field at the drain-side edge of the gate. The use of a gate insulator is also investigated, using both JVD SiO2 and e-beam evaporated SiO2 to reduce gate leakage, increasing breakdown voltages to 1050V and 1300V respectively. The power device figure of merit (FOM) for these devices: $V^2_{BR}/R_{on}=9.94\times10^8[{\rm V}^2\cdot\Omega^{-1}{\rm cm}^{-2}]$, is the highest reported for switching devices. To reduce trapping effects, reactively sputtered SiNx, is used as a passivant, resulting in a switching time of less than 30 ns for devices blocking over 110V with a drain current of 1.4A under resistive load conditions. Dynamic load results are also presented. The development of HBTs for switching applications included the development of an etched emitter HBT with a selectively regrown extrinsic base. This was later improved upon with the selectively regrown emitter devices with current gains as high as 15. To improve breakdown in these devices, thick GaN layers were grown, reducing threading dislocation densities in the active layers. A further improvement included the use of a bevelled shallow etch and a lateral collector design to maximize device breakdown. [ABSTRACT FROM AUTHOR]