Unconventional magnetism in all-carbon nanofoam

We report production of nanostructured carbon foam by a high-repetition-rate, high-power laser ablation of glassy carbon in Ar atmosphere. A combination of characterization techniques revealed that the system contains both sp2 and sp3 bonded carbon atoms. The material is a novel form of carbon in which graphite-like sheets fill space at very low density due to strong hyperbolic curvature, as proposed for ?schwarzite?. The foam exhibits ferromagnetic-like behaviour up to 90 K, with a narrow hysteresis curve and a high saturation magnetization. Such magnetic properties are very unusual for a carbon allotrope. Detailed analysis excludes impurities as the origin of the magnetic signal. We postulate that localized unpaired spins occur because of topological and bonding defects associated with the sheet curvature, and that these spins are stabilized due to the steric protection offered by the convoluted sheets.Comment: 14 pages, including 2 tables and 7 figs. Submitted to Phys Rev B 10 September 200

Amino Acids and N-acetyl-aspartyl-glutamate as Neurotransmitter Candidates in the Monkey Retinogeniculate Pathways

The lateral geniculate nucleus (LGNd) receives chemically identified inputs from brain stem structures, the thalamus and visual cortex. The identity of the neurotransmitter(s) in the retinal input, however, is unknown. To investigate the possibility that some amino acids and certain dipeptides, such as N-acetyl-aspartyl-glutamate (NAAG), fulfill this function, changes in their concentration were measured in the optic tract, parvocellular and magno-cellular segments of the LGNd, superior colliculus and visual cortex of six monkeys (Macaca fascicularis), seven days after right optic tractotomy. The LGNd was studied also in two additional macaques, three months after occipital lobectomy. Tissue was frozen within five minutes of death, regions were dissected with the micropunch technique, and substances were analyzed by HPLC. Of the ten compounds measured in the normal side, glutamate, glutamine, glycine, and alanine had homogeneous distributions. GABA was highest in the superior colliculus, cystathionine and NAAG decreased in the rostrocaudal direction, and N-acetyl-aspartate showed an opposite gradient of concentration. The heterogeneity in taurine and aspartate was less systematic. Optic tract section induced significant, large reductions in NAAG, glutamate and aspartate in the optic tract distal to the lesion. Significant decreases in NAAG, and to a lesser extent in glutamate, were observed in the LGNd. Changes in the dipeptide were apparent in both the parvocellular and magnocellular segments. Reductions in glutamate reached significance in the parvocellular laminae, and those of aspartate approached significance in the magnocellular division. No significant differences were detected in the superior colliculus and striate cortex. Occipital lobectomy produced large declines in aspartate and glutamate in the LGNd, as well as moderate reductions in alanine and GABA, and minor changes in glutamine and glycine. The results of optic tractotomy support the role of NAAG as a neurotransmitter candidate in the monkey retinogeniculate pathways; its significant decrease in both geniculate segments suggests that X- and Y- retinal axons utilize this substance. Although at times the reductions in glutamate or aspartate failed to reach significance, their role cannot be excluded. The findings after occipital lobectomy strongly favor these latter substances as corticogeniculate transmitters

Cervical lymph node biopsy - watch the nerves!

Experience with the delayed diagnosis and severe consequences of accessory nerve injury following cervical gland lymph node biopsy prompted us to survey the practice of South African paediatric surgeons and to ascertain the incidence of accessory nerve injury. Cervical lymph gland biopsies are often performed for diagnostic and therapeutic purposes and although spinal accessory nerve (SAN) injury seldom occurs, it remains a significant injury. The operation is relatively minor and cervical glands are commonly biopsied/removed in South Africa by junior doctors, registrars and general practitioners. The operation is often performed as a day case under suboptimal circumstances, despite the fact that it is common knowledge that posterior triangle nodular biopsy carries the risk of iatrogenic damage to the accessory nerve

You've Got Mail! Calendar, Weather and More: Customizable Phone Access to Personal Information

We present a design and a prototype of a system that provides access to calendar, email, weather, and news information over a phone using a VoiceXML interface. The system provides quick access to personal information, while enabling but not requiring interactivity. As one major application, we envision the system being used while commuting to work. At home, users define their preferences regarding content and order of presentation using a website. On the road, the personalized audio feed plays like a radio news show. Instead of commercials, the user is reminded of today's meetings, deadlines and listens to the email inbox

The history of paediatric trauma care in Cape Town

Trauma is a leading cause of morbidity, mortality and disability in childhood. In most developed countries where 18% of the population are in the age group 0 - 15 years, injury exceeds all other causes of childhood mortality. In the developing countries of Africa, however, children aged 0 - 15 years constitute 43% of the population and trauma has an even bigger impact on child health.There is an erroneous perception that trauma is not a major health problem in Africa, derived from undue emphasis on mortality statistics alone. Yet, the impact of trauma ought to be measured not only in terms of death, but also the tremendous morbidity and disability caused by injuries, and their socioeconomic consequences

Gender and the Lived Body Experience of Academic Work during Covid19

The rapid transition to online teaching in response to Covid-19 presented unprecedented challenges for academic communities. Staff had vastly different experiences of engaging with technology, and these experiences are shaped by factors including gender, (dis)ability, socio-economic resources and caring responsibilities. We report findings from an intersectional interview examination of how 412 staff in a large London-based university adapted to teaching and researching from home at the beginning of lockdown during the COVID-19 pandemic. In this article, we construct grounded theory around the divisibility of the body, and the conflicts arising from the need to span home and work-life, our findings illustrate how patterns of inequity for women academics converge to construct ways of managing the boundary work of home and work with different degrees of successes. We document how management support and/ or existing expertise were vital to enable women academics to overcome obstacles to equitable work.

Visualizing aerosol-particle injection for diffractive-imaging experiments

Delivering sub-micrometer particles to an intense x-ray focus is a crucial aspect of single-particle diffractive-imaging experiments at x-ray free-electron lasers. Enabling direct visualization of sub-micrometer aerosol particle streams without interfering with the operation of the particle injector can greatly improve the overall efficiency of single-particle imaging experiments by reducing the amount of time and sample consumed during measurements. We have developed in-situ non-destructive imaging diagnostics to aid real-time particle injector optimization and x-ray/particle-beam alignment, based on laser illumination schemes and fast imaging detectors. Our diagnostics are constructed to provide a non-invasive rapid feedback on injector performance during measurements, and have been demonstrated during diffraction measurements at the FLASH free-electron laser.Comment: 15 page

Meningococcal septicaemia complications involving skin and underlying deeper tissues - management considerations and outcome

Objective: To describe surgical experience with purpura fulminans related to meningococcaemia in a single institution, and to suggest a management protocol. Methods: A retrospective review was done of patients admitted to the intensive care unit at Red Cross War Memorial Children's Hospital in Cape Town with the clinical diagnosis of purpura fulminans. Results: During a 28-year period (1977 - 2005) 112 children (average age 3.4 years) were treated for meningococcaemia with purpura fulminans. Overall mortality was 10.7%. Local treatment consisted of measures to improve circulation, infection control and healing of necrotic tissue. Demarcation of necrotic areas was evident at 5.5 days and the average area of skin necrosis was 14% total body surface area (range 2 - 85%). The lower limbs were predominantly affected. Purpura fulminans resolved in 35 children (31.2%) without skin necrosis. Skin grafting was required in 77 children (68.8%). Factors associated with a poor outcome for peripheral extremity salvage were progressive irreversible skin changes, early disappearance of distal pulses, tense cold swollen extremities and intense pain on passive movement of the affected extremity. Amputations were performed proximal to the area of necrosis, on average 27 days after injury. Conclusions: Meningococcaemia is a disease with potentially devastating consequences. Early surgical consultation is essential. Skin- and soft-tissue-releasing incisions should be considered early to reduce the incidence of extremity necrosis. Small necrotic areas usually separate spontaneously with secondary healing or can be excised and sutured. Larger necrotic areas should be excised only after demarcation has been established, and can be covered with delayed skin grafting. Amputation should be conservative but may require revision