Lateralizing Value of Interictal Spikes on Overnight Sleep-EEG Studies in Temporal Lobe Epilepsy

Purpose: To determine the lateralizing value of interictal epileptiform discharges (IEDs) recorded during overnight sleep-EEG studies in temporal lobe epilepsy. Because IEDs are more prevalent in non-rapid eye movement (NREM) sleep than in wakefulness, overnight sleep-EEG recordings may contribute additional lateralizing information to the epilepsy surgery evaluation beyond daytime EEGs. Methods: Twenty-four subjects with medically refractory temporal lobe epilepsy underwent continuous overnight sleep-EEG recordings. Subjects were seizure free ≤24 h before study and receiving stable doses of medication. The IED foci recorded on overnight studies were compared with daytime EEGs, interictal samples, and ictal recordings during long-term monitoring, brain magnetic resonance images (MRIs), and surgical outcome. Results: (a) In all 24 subjects, including 13 without IEDs on daytime EEGs, temporal IEDs were present during NREM sleep and were exclusively or predominantly (<95%) unilateral in 15 and bitemporal in nine. (b) Unilateral NREM IEDs were concordant with surface or depth ictal-onset regions in 14 subjects, even if MRIs were normal (three subjects) or surface ictal-onset regions were bilateral (five subjects). Eleven of 12 subjects with unilateral concordant NREM IEDs who have undergone surgery are seizure free. (c) Bitemporal IEDs were associated with postoperative seizures in all subjects with normal MRIs or widespread MRI abnormalities. However, all subjects with bitemporal IEDs and MRI hippocampal abnormalities concordant with ictal-onset regions had good to excellent surgical outcomes. Conclusions: When combined with other investigations, IEDs recorded on overnight studies add prognostic data to the epilepsy surgery evaluation not provided by daytime EEGs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66154/1/j.1528-1157.1999.tb02044.x.pd

Improvements to the Synthesis of Polyimide Aerogels

Cross-linked polyimide aerogels are viable approach to higher temperature, flexible insulation for inflatable decelerators. Results indicate that the all-polyimide aerogels are as strong or stronger than polymer reinforced silica aerogels at the same density. Currently, examining use of carbon nanofiber and clay nanoparticles to improve performance. Flexible, polyimide aerogels have potential utility in other applications such as space suits, habitats, shelter applications, etc. where low dusting is desire

Role of Condom Negotiation on Condom use among Women of Reproductive Age in three Districts in Tanzania.

ABSTRACT: BACKGROUND: HIV/AIDS remains being a disease of great public health concern worldwide. In regions such as sub-Saharan Africa (SSA) where women are disproportionately infected with HIV, women are reportedly less likely capable of negotiating condom use. However, while knowledge of condom use for HIV prevention is extensive among men and women in many countries including Tanzania, evidence is limited about the role of condom negotiation on condom use among women in rural Tanzania. METHODS: Data originate from a cross-sectional survey of random households conducted in 2011 in Rufiji, Kilombero and Ulanga districts in Tanzania. The survey assessed health-seeking behaviour among women and children using a structured interviewer-administered questionnaire. A total of 2,614 women who were sexually experienced and aged 15--49 years were extracted from the main database for the current analysis. Linkage between condom negotiation and condom use at the last sexual intercourse was assessed using multivariate logistic regression. RESULTS: Prevalence of condom use at the last sexual intercourse was 22.2% overall, ranging from12.2% among married women to 54.9% among unmarried (single) women. Majority of the women (73.4%) reported being confident to negotiate condom use, and these women were significantly more likely than those who were not confident to have used a condom at the last sexual intercourse (OR = 3.13, 95% CI 2.22-4.41). This effect was controlled for marital status, age, education, religion, number of sexual partners, household wealth and knowledge of HIV prevention by condom use. CONCLUSION: Confidence to negotiate condom use is a significant predictor of actual condom use among women in rural Tanzania. Women especially unmarried ones or those in multiple partnerships should be empowered with condom negotiation skills to enhance their sexual and reproductive health outcomes

Atomic-scale modeling of the deformation of nanocrystalline metals

Nanocrystalline metals, i.e. metals with grain sizes from 5 to 50 nm, display technologically interesting properties, such as dramatically increased hardness, increasing with decreasing grain size. Due to the small grain size, direct atomic-scale simulations of plastic deformation of these materials are possible, as such a polycrystalline system can be modeled with the computational resources available today. We present molecular dynamics simulations of nanocrystalline copper with grain sizes up to 13 nm. Two different deformation mechanisms are active, one is deformation through the motion of dislocations, the other is sliding in the grain boundaries. At the grain sizes studied here the latter dominates, leading to a softening as the grain size is reduced. This implies that there is an ``optimal'' grain size, where the hardness is maximal. Since the grain boundaries participate actively in the deformation, it is interesting to study the effects of introducing impurity atoms in the grain boundaries. We study how silver atoms in the grain boundaries influence the mechanical properties of nanocrystalline copper.Comment: 10 pages, LaTeX2e, PS figures and sty files included. To appear in Mater. Res. Soc. Symp. Proc. vol 538 (invited paper). For related papers, see http://www.fysik.dtu.dk/~schiotz/publist.htm

Divergent Cortical Generators of MEG and EEG during Human Sleep Spindles Suggested by Distributed Source Modeling

Background: Sleep spindles are,1-second bursts of 10–15 Hz activity, occurring during normal stage 2 sleep. In animals, sleep spindles can be synchronous across multiple cortical and thalamic locations, suggesting a distributed stable phaselocked generating system. The high synchrony of spindles across scalp EEG sites suggests that this may also be true in humans. However, prior MEG studies suggest multiple and varying generators. Methodology/Principal Findings: We recorded 306 channels of MEG simultaneously with 60 channels of EEG during naturally occurring spindles of stage 2 sleep in 7 healthy subjects. High-resolution structural MRI was obtained in each subject, to define the shells for a boundary element forward solution and to reconstruct the cortex providing the solution space for a noise-normalized minimum norm source estimation procedure. Integrated across the entire duration of all spindles, sources estimated from EEG and MEG are similar, diffuse and widespread, including all lobes from both hemispheres. However, the locations, phase and amplitude of sources simultaneously estimated from MEG versus EEG are highly distinct during the same spindles. Specifically, the sources estimated from EEG are highly synchronous across the cortex, whereas those from MEG rapidly shift in phase, hemisphere, and the location within the hemisphere. Conclusions/Significance: The heterogeneity of MEG sources implies that multiple generators are active during huma

Environmental enrichment intervention for Rett syndrome: An individually randomised stepped wedge trial

Background: Rett syndrome is caused by a pathogenic mutation in the MECP2 gene with major consequences for motor and cognitive development. One of the effects of impaired MECP2 function is reduced production of Brain Derived Neurotrophic Factor (BDNF), a protein required for normal neuronal development. When housed in an enriched environment, MECP2 null mice improved motor abilities and increased levels of BDNF in the brain. We investigated the effects of environmental enrichment on gross motor skills and blood BDNF levels in girls with Rett syndrome. Methods: A genetically variable group of 12 girls with a MECP2 mutation and younger than 6 years participated in a modified individually randomised stepped wedge design study. Assessments were conducted on five occasions, two during the baseline period and three during the intervention period. Gross motor function was assessed using the Rett Syndrome Gross Motor Scale (maximum score of 45) on five occasions, two during the baseline period and three during the intervention period. Blood levels of BDNF were measured at the two baseline assessments and at the end of the intervention period. The intervention comprised motor learning and exercise supplemented with social, cognitive and other sensory experiences over a six-month period. Results: At the first assessment, the mean (SD) age of the children was 3 years (1 year 1 month) years ranging from 1 year 6 months to 5 years 2 months. Also at baseline, mean (SD) gross motor scores and blood BDNF levels were 22.7/45 (9.6) and 165.0 (28.8) ng/ml respectively. Adjusting for covariates, the enriched environment was associated with improved gross motor skills (coefficient 8.2, 95%CI 5.1, 11.2) and a 321.4 ng/ml (95%CI 272.0, 370.8) increase in blood BDNF levels after 6 months of treatment. Growth, sleep quality and mood were unaffected. Conclusions: Behavioural interventions such as environmental enrichment can reduce the functional deficit in Rett syndrome, contributing to the evidence-base for management and further understanding of epigenetic mechanisms. Environmental enrichment will be an important adjunct in the evaluation of new drug therapies that use BDNF pathways because of implications for the strengthening of synapses and improved functioning. Trial registration: ACTRN12615001286538

HighP–TNano-Mechanics of Polycrystalline Nickel

We have conducted highP–Tsynchrotron X-ray and time-of-flight neutron diffraction experiments as well as indentation measurements to study equation of state, constitutive properties, and hardness of nanocrystalline and bulk nickel. Our lattice volume–pressure data present a clear evidence of elastic softening in nanocrystalline Ni as compared with the bulk nickel. We show that the enhanced overall compressibility of nanocrystalline Ni is a consequence of the higher compressibility of the surface shell of Ni nanocrystals, which supports the results of molecular dynamics simulation and a generalized model of a nanocrystal with expanded surface layer. The analytical methods we developed based on the peak-profile of diffraction data allow us to identify “micro/local” yield due to high stress concentration at the grain-to-grain contacts and “macro/bulk” yield due to deviatoric stress over the entire sample. The graphic approach of our strain/stress analyses can also reveal the corresponding yield strength, grain crushing/growth, work hardening/softening, and thermal relaxation under highP–Tconditions, as well as the intrinsic residual/surface strains in the polycrystalline bulks. From micro-indentation measurements, we found that a low-temperature annealing (T < 0.4 Tm) hardens nanocrystalline Ni, leading to an inverse Hall–Petch relationship. We explain this abnormal Hall–Petch effect in terms of impurity segregation to the grain boundaries of the nanocrystalline Ni