3D analysis of advanced nano-devices using electron and atom probe tomography

The structural and chemical properties of advanced nano-devices with a three-dimensional (3D) architecture have been studied at the nanometre scale. An original method has been used to characterize gate-all-around and tri-gate silicon nanowire transistor by combining electron tomography and atom probe tomography (APT). Results show that electron tomography is a well suited method to determine the morphological structure and the dimension variations of devices provided that the atomic number contrast is sufficient but without an absolute chemical identification. APT can map the 3D chemical distribution of the atoms in devices but suffers from strong distortions in the dimensions of the reconstructed volume. These may be corrected using a simple method based on atomic density correction and electron tomography data. Moreover, this combination is particularly useful in helping to understand the evaporation mechanisms and improve APT reconstructions. This paper demonstrated that a full 3D characterization of nano-devices requires the combination of both tomography techniques.

Brain abnormalities and neurodevelopmental delay in congenital heart disease: systematic review and meta-analysis

OBJECTIVES

Studies have demonstrated an association between congenital heart disease (CHD) and neurodevelopmental delay. Neuroimaging studies have also demonstrated a high incidence of preoperative brain abnormalities. The aim of this study was to perform a systematic review to quantify the non-surgical risk of brain abnormalities and of neurodevelopmental delay in infants with CHD.

METHODS

MEDLINE, EMBASE and The Cochrane Library were searched electronically without language restrictions, utilizing combinations of the terms congenital heart, cardiac, neurologic, neurodevelopment, magnetic resonance imaging, ultrasound, neuroimaging, autopsy, preoperative and outcome. Reference lists of relevant articles and reviews were hand-searched for additional reports. Cohort and case-control studies were included. Studies reporting neurodevelopmental outcomes and/or brain lesions on neuroimaging in infants with CHD before heart surgery were included. Cases of chromosomal or genetic abnormalities, case reports and editorials were excluded. Between-study heterogeneity was assessed using the I(2) test.

RESULTS

The search yielded 9129 citations. Full text was retrieved for 119 and the following were included in the review: 13 studies (n = 425 cases) reporting on brain abnormalities either preoperatively or in those who did not undergo congenital cardiac surgery and nine (n = 512 cases) reporting preoperative data on neurodevelopmental assessment. The prevalence of brain lesions on neuroimaging was 34% (95% CI, 24-46; I(2) = 0%) in transposition of the great arteries, 49% (95% CI, 25-72; I(2) = 65%) in left-sided heart lesions and 46% (95% CI, 40-52; I(2) =18.1%) in mixed/unspecified cardiac lesions, while the prevalence of neurodevelopmental delay was 42% (95% CI, 34-51; I(2) = 68.9).

CONCLUSIONS

In the absence of chromosomal or genetic abnormalities, infants with CHD are at increased risk of brain lesions as revealed by neuroimaging and of neurodevelopmental delay. These findings are independent of the surgical risk, but it is unclear whether the time of onset is fetal or postnatal.

The effects of obesity on oesophageal function, acid exposure and the symptoms of gastro-oesophageal reflux disease

BACKGROUND

Obese patients have an increased risk of gastro-oesophageal reflux disease; however, the mechanism underlying this association is uncertain.

AIM

To test the hypothesis that mechanical effects of obesity on oesophageal function increase acid exposure and symptoms.

METHODS

Height, weight and waist circumference (WC) were measured in patients with typical reflux symptoms referred for manometry and 24 h ambulatory pH studies. Symptom severity was assessed by questionnaire. The association between obesity [WC, body mass index (BMI)], oesophageal function, acid exposure and reflux symptoms was assessed.

RESULTS

Physiological measurements were obtained from 582 patients (median age 48, 56% female) of whom 406 (70%) completed symptom questionnaires. The prevalence of general obesity was greater in women (BMI ≥ 30 kg/m(2) ; F 23%:M 16%; P = 0.056), however more men had abdominal obesity (WC ≥ 99 cm (M 41%:F 28%; P = 0.001)). Oesophageal acid exposure increased with obesity (WC: R = 0.284, P < 0.001) and was associated also with lower oesophageal sphincter (LOS) pressure, reduced abdominal LOS length and peristaltic dysfunction (all P < 0.001). Univariable regression showed a negative association of WC with both LOS pressure and abdominal LOS length (R = -0.221 and -0.209 respectively; both P < 0.001). However, multivariable analysis demonstrated that the effects of increasing WC on oesophageal function do not explain increased acid reflux in obese patients. Instead, independent effects of obesity and oesophageal dysfunction on acid exposure were present. Reflux symptoms increased with acid exposure (R = 0.300; P < 0.001) and this association explained increased symptom severity in obese patients.

CONCLUSIONS

Abdominal obesity (waist circumference) is associated with oesophageal dysfunction, increased acid exposure and reflux symptoms; however, this analysis does not support the mechanical hypothesis that the effects of obesity on oesophageal function are the cause of increased acid exposure in obese patients.

Paediatric asthma hospital utilization varies by demographic factors and area socio-economic status

OBJECTIVES

Associations of emergency department (ED) visits and hospital admissions for asthma in children with demographics and area socio-economic status (SES) were examined to evaluate long-term trends and identify vulnerable populations.

STUDY DESIGN

Retrospective population-based trend and cross-sectional analyses.

METHODS

Asthma hospital admissions (2000-2007) and ED visits (2005-2007) for children aged 0-14 years living in Orange County, California were linked with zip-code-level SES data (2000 US Census). Annual population estimates were obtained to calculate age-specific admissions and ED visit rates. Average annual percentage changes (AAPC) were calculated with joinpoint analyses. The risks of ED visits and hospital admissions were estimated from SES indicators with negative binomial regression.

RESULTS

Rates of asthma hospital admissions and ED visits were highest among children aged 0-4 years, males and African Americans, and lowest among Asian/Pacific Islanders. African Americans and Hispanics/Latinos were more likely to be uninsured. Asthma admissions decreased significantly for all age groups over the study period. The greatest declines per 100,000 were among children aged 0-4 years (AAPC: -15.3%, 95% confidence interval -17.0% to -13.4%). Rates of hospital admissions and ED visits were significantly higher in low-SES groups. Hospital admission rates were 30-60% higher and ED visits were 80-90% higher in zip codes in the lowest tertile of median household income compared with the highest tertile of median household income.

CONCLUSIONS

Paediatric asthma hospitalizations and ED visit rates are declining in Orange County. However, certain groups are disproportionately affected, including those living in areas with low SES. This information will help in targeting intervention strategies to children at highest risk for severe asthma episodes.

Assessment of Infant Movement With a Compact Wireless Accelerometer System

There is emerging data that patterns of motor activity early in neonatal life can predict impairments in neuromotor development. However, current techniques to monitor infant movement mainly rely on observer scoring, a technique limited by skill, fatigue, and inter-rater reliability. Consequently, we tested the use of a lightweight, wireless, accelerometer system that measures movement and can be worn by premature babies without interfering with routine care. We hypothesized that this system would be useful in assessing motor activity, in identifying abnormal movement, and in reducing the amount of video that a clinician would need to review for abnormal movements. Ten preterm infants in the NICU were monitored for 1 h using both the accelerometer system and video. A physical therapist trained to recognize cramped-synchronized general movements scored all of the video data by labeling each abnormal movement observed. The parameters of three different computer models were then optimized based on correlating features computed from accelerometer data and the observer’s annotations. The annotations were compared to the model’s prediction on unseen data. The trained observer identified cramped-synchronized general movements in 6 of the 10 infants. The computer models attained between 70% and 90% accuracy when predicting the same observer label for each data point. Our study suggests that mini-accelerometers may prove useful as a clinical tool assessing patterns of movement in preterm infants.

Patient/caregiver perceived benefits and barriers to elective orthopedic surgery (EOS) in patients with congenital hemophilia with inhibitors

OBJECTIVE

Congenital hemophilia patients with inhibitors are at greater risk for developing arthropathy and orthopedic complications compared to those without inhibitors. Elective orthopedic surgeries (EOS) may be an option for these patients and may provide long-term cost savings due to reduced bleed frequency. However, patient motivations and goals for undergoing or delaying such surgeries are not well understood. A US-based patient/caregiver survey was designed to describe inhibitor patient experiences and outcomes following EOS and to develop a comprehensive understanding of patient preferences for EOS, which are lacking in the literature.

METHODS

The paper-pencil questionnaire was mailed to 261 US inhibitor patients/caregivers and included history and timing of EOS, quality-of-life (QoL) and potential benefits of and barriers to receiving EOS. Univariate/bivariate descriptive analyses were performed to characterize those with/without a history of EOS.

RESULTS

For 103 subjects who responded, the mean age was 20.9 years. Approximately 25% (n = 26) of respondents underwent EOS, most commonly on the knee (21, 81%); 73.1% of surgery recipients reported the surgery improved or greatly improved their QoL based on single-item response. The highest ranked perceived benefits were less pain, fewer bleeds, and improved mobility. However, the leading concerns reported were lack of improved mobility (62.2%), fear of uncontrolled bleeding (61.3%), and surgical complications, such as blood clot (60.0%).

LIMITATIONS

The study consisted of a small sample size, primarily due to the difficulty in trying to reach inhibitor patients or their caregivers, thereby restricting inferential and stratification analysis.

CONCLUSIONS

QoL improved for most inhibitor patients who reported having EOS. For those considering surgery, there is optimism about the potential benefits, but realistic concerns associated with bleed control and post-op complications.

Guideline on safer conception in fertile HIV-infected individuals and couples

Ninety years ago the isolation of insulin transformed the lives of people with type 1 diabetes. Now, models based on empirical data estimate that a 25-year-old person with HIV, when appropriately treated with antiretroviral therapy, can expect to enjoy a median survival of 35 years, remarkably similar to that for someone of the same age with type 1 diabetes. It is high time we normalised the lives of people living positively with HIV. This includes the basic human right to conceive and raise children. HIV-positive individuals may be in serodiscordant relationships or in seroconcordant relationships. As health care providers, it is our responsibility to ensure we understand the opportunities and risks of natural conception in these scenarios, so that we can help our patients to make informed decisions about their own lives. Most of all, it is our duty to make family planning in the setting of positive prevention as safe as we can. This includes informed decisions on contraception, adoption, fostering, conception and prevention of mother-to-child transmission. Some months ago a dedicated group of individuals, invited and sponsored by the Southern African HIV Clinicians Society, came together in Cape Town to devise guidance in this area, recognising that there are ideal strategies that may be outside the realm of the resource constraints of the public sector or health programmes in southern Africa. This guideline therefore attempts to provide a range of strategies for various resource settings. It is up to us, the providers, to familiarise ourselves with the merits/benefits and risks of each, and to then engage patients in meaningful discussions. All the above, however, is based on the premise and prerequisite that the subject of family planning is actively raised and frequently discussed in our patient encounters.Please find a link to the update of this guideline: http://sajhivmed.org.za/index.php/hivmed/article/view/399

In vitro activity of doripenem and other carbapenems against contemporary Gram-negative pathogens isolated from hospitalised patients in the Asia-Pacific region: results of the COMPACT Asia-Pacific Study

The Comparative Activity of Carbapenems Testing (COMPACT) Study was designed to determine the in vitro potency of doripenem compared with imipenem and meropenem against a large number of contemporary Gram-negative pathogens from more than 100 centres across Europe and the Asia-Pacific region and to assess the reliability of Etest methodology for doripenem minimum inhibitory concentration (MIC) determination against these pathogens. Data from eight countries within the Asia-Pacific region, which collected 1612 bacterial isolates, are presented here. Etest methodology was found to be a reliable method for MIC determination. Doripenem showed in vitro activity similar to or better than meropenem and at least four-fold better than imipenem against Enterobacteriaceae. Against Pseudomonas aeruginosa, doripenem was also the most active of the three carbapenems in vitro. However, in vitro results do not necessarily correlate with clinical outcome.

Structural and optical properties of InGaN/GaN nanowire heterostructures grown by PA-MBE

The structural and optical properties of InGaN/GaN nanowire heterostructures grown by plasma-assisted molecular beam epitaxy have been studied using a combination of transmission electron microscopy, electron tomography and photoluminescence spectroscopy. It is found that, depending on In content, the strain relaxation of InGaN may be elastic or plastic. Elastic relaxation results in a pronounced radial In content gradient. Plastic relaxation is associated with the formation of misfit dislocations at the InGaN/GaN interface or with cracks in the InGaN nanowire section. In all cases, a GaN shell was formed around the InGaN core, which is assigned to differences in In and Ga diffusion mean free paths.