Nano-oxidation of silicon surfaces: Comparison of noncontact and contact atomic-force microscopy methods

3 pages, 4 figures.Local oxidation lithography by atomic-force microscopy is emerging as a powerful method for nanometer-scale patterning of surfaces. Here, we perform a comparative study of contact and noncontact atomic-force microscopy (AFM) oxidation experiments. The comparison of height and width dependencies on voltage and pulse duration allows establishing noncontact AFM as the optimum local oxidation method. For the same electrical conditions, noncontact AFM oxides exhibit higher aspect ratios (0.04 vs 0.02). The smallness of the liquid meniscus in noncontact AFM oxidation produces smaller oxide widths. We also report a slower oxidation rate in contact AFM oxidation. We explain this result by introducing an effective energy barrier (~0.14 eV) that includes the mechanical work done by the growing oxide against the cantilever (~0.01 eV).This work was financially supported by the Dirección General de Enseñanza Superior e Investigación (PB98-0471) and the European Commission (GR5D-CT- 2000-00349).Peer reviewe

Variability in subthalamic nucleus targeting for deep brain stimulation with 3 and 7 Tesla magnetic resonance imaging

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective surgical treatment for Parkinson's disease (PD). Side-effects may, however, be induced when the DBS lead is placed suboptimally. Currently, lower field magnetic resonance imaging (MRI) at 1.5 or 3 Tesla (T) is used for targeting. Ultra-high-field MRI (7 T and above) can obtain superior anatomical information and might therefore be better suited for targeting. This study aims to test whether optimized 7 T imaging protocols result in less variable targeting of the STN for DBS compared to clinically utilized 3 T images. Three DBS-experienced neurosurgeons determined the optimal STN DBS target site on three repetitions of 3 T-T2, 7 T-T2*, 7 T-R2* and 7 T-QSM images for five PD patients. The distance in millimetres between the three repetitive coordinates was used as an index of targeting variability and was compared between field strength, MRI contrast and repetition with a Bayesian ANOVA. Further, the target coordinates were registered to MNI space, and anatomical coordinates were compared between field strength, MRI contrast and repetition using a Bayesian ANOVA. The results indicate that the neurosurgeons are stable in selecting the DBS target site across MRI field strength, MRI contrast and repetitions. The analysis of the coordinates in MNI space however revealed that the actual selected location of the electrode is seemingly more ventral when using the 3 T scan compared to the 7 T scans

Clinical effectiveness of unilateral deep brain stimulation in Tourette syndrome

Dysfunctional basal ganglia loops are thought to underlie the clinical picture of Tourette syndrome (TS). By altering dopaminergic activity in the affected neural structures, bilateral deep brain stimulation is assumed to have a modulatory effect on dopamine transmission resulting in an amelioration of tics. While the majority of published case reports deals with the application of bilateral stimulation, the present study aims at informing about the high effectiveness of unilateral stimulation of pallidal and nigral thalamic territories in TS. Potential implications and gains of the unilateral approach are discussed

Dust and grit matter: abrasives of different size lead to opposing dental microwear textures in experimentally fed sheep (Ovis aries)

External abrasives ingested along with the herbivore diet are considered main contributors to dental wear, though how the different sizes and concentrations of these abrasives influence wear remains unclear. Dental microwear texture analysis (DMTA) is an establishedmethod for dietary reconstructionwhich describes a tooth’s surface topography on a micrometre scale. The method has yielded conflicting results as to the effect of external abrasives. In the present study, a feeding experiment was performed on sheep (Ovis aries) fed seven diets of different abrasiveness. Our aim was to discern the individual effects of size (4, 50 and 130 μm) and concentration (0%,4% and 8% of dry matter) of abrasives on dental wear, applying DMTA to four tooth positions. Microwear textures differed between individual teeth, but surprisingly, showed no gradient along the molar tooth row, and the strongest differentiation of experimental groups was achieved when combining data of all maxillary molars. Overall, a pattern of increasing height, volume and complexity of the tooth’s microscopic surface appeared with increasing size of dietary abrasives, and when compared with the control, the small abrasive diets showed a polishing effect. The results indicate that the size of dietary abrasives is more important for dental microwear texture traces than their concentration, and that different sizes can have opposing effects on the dietary signal. The latter finding possibly explains conflicting evidence from previous experimental DMTA applications. Further exploration is required to understand whether and how microscopic traces created by abrasives translate quantitatively to tissue loss

Between-hospital variation in mortality and survival after glioblastoma surgery in the Dutch Quality Registry for Neuro Surgery

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Dental microwear texture analysis correlations in guinea pigs (Cavia porcellus) and sheep (Ovis aries) suggest that dental microwear texture signal consistency is species-specific

Dental microwear texture (DMT) analysis is used to differentiate abrasive dental wear patterns in many species fed different diets. Because DMT parameters all describe the same surface, they are expected to correlate with each other distinctively. Here, we explore the data range of, and correlations between, DMT parameters to increase the understanding of how this group of proxies records wear within and across species. The analysis was based on subsets of previously published DMT analyses in guinea pigs, sheep, and rabbits fed either a natural whole plant diet (lucerne, grass, bamboo) or pelleted diets with or without added quartz abrasives (guinea pigs and rabbits: up to 45 days, sheep: 17 months). The normalized DMT parameter range (P4: 0.69   0.25; M2: 0.83   0.16) and correlation coefficients (P4: 0.50   0.31; M2: 0.63   0.31) increased along the tooth row in guinea pigs, suggesting that strong correlations may be partially explained by data range. A comparison between sheep and guinea pigs revealed a higher DMT data range in sheep (0.93   0.16; guinea pigs: 0.47   0.29), but this did not translate into more substantial correlation coefficients (sheep: 0.35   0.28; guinea pigs: 0.55   0.32). Adding rabbits to an interspecies comparison of low abrasive dental wear (pelleted lucerne diet), the softer enamel of the hypselodont species showed a smaller data range for DMT parameters (guinea pigs 0.49   0.32, rabbit 0.19   0.18, sheep 0.78   0.22) but again slightly higher correlations coefficients compared to the hypsodont teeth (guinea pigs 0.55   0.31, rabbits 0.56   0.30, sheep 0.42   0.27). The findings suggest that the softer enamel of fast-replaced ever-growing hypselodont cheek teeth shows a greater inherent wear trace consistency, whereas the harder enamel of permanent and non-replaced enamel of hypsodont ruminant teeth records less coherent wear patterns. Because consistent diets were used across taxa, this effect cannot be ascribed to the random overwriting of individual wear traces on the more durable hypsodont teeth. This matches literature reports on reduced DMT pattern consistency on harder materials; possibly, individual wear events become more random in nature on harder material. Given the species-specific differences in enamel characteristics, the findings suggest a certain species-specificity of DMT patterns

Description, Host-specificity, and Strain Selectivity of the Dinoflagellate Parasite Parvilucifera sinerae sp.nov. (Perkinsozoa)

17 pages, 7 figures, 2 tablesA new species of parasite, Parvilucifera sinerae sp. nov., isolated froma bloomof the toxic Dinoflagellate Alexandrium minutum in the harbor of Arenys de Mar (Mediterranean Sea, Spain), is described. This species is morphologically, behaviourally, and genetically (18S rDNA sequence) different from Parvilucifera infectans, until now the only species of the genus Parvilucifera to be genetically analyzed. Sequence análisis of the 18S ribosomal DNA supported P. Sinerae as a new species placed within the Perkinsozoa and close to P. infectans. Data on the seasonal occurrence of P. sinerae, its infective rates in natural and laboratory cultures, and intra-species strain-specific Resistance are presented. Life-cycle studies in field simples showed that the dinoflagellate resting zygote (restingcyst) was resistant to infection, but the mobile zygote (planozygote) orpelli clestage (temporary cyst) became infected. The effects of Light and salinity level son the growth of P. sinerae were examined, and the results showed that low salinity levels promote both sporangial germination and higher rates of infection. Our findings on this newly described parasite point to a complex host—parasite interaction and provide valuable information that leads to a reconsideration of the biological strategy to control dinoflagellate blooms by jeans of intentional parasitic infectionsThis research was funded by the EU Project SEED (GOCE-CT-2005-003875). R.I. Figueroa work is supported by a I3P contract and E. Garcés’ work is supported by a Ramon y Cajal grant, both from the Spanish Ministry of Education and SciencePeer reviewe

Unconventional animal models for traumatic brain injury and chronic traumatic encephalopathy

Traumatic brain injury (TBI) is one of the main causes of death worldwide. It is a complex injury that influences cellular physiology, causes neuronal cell death, and affects molecular pathways in the brain. This in turn can result in sensory, motor, and behavioral alterations that deeply impact the quality of life. Repetitive mild TBI can progress into chronic traumatic encephalopathy (CTE), a neurodegenerative condition linked to severe behavioral changes. While current animal models of TBI and CTE such as rodents, are useful to explore affected pathways, clinical findings therein have rarely translated into clinical applications, possibly because of the many morphofunctional differences between the model animals and humans. It is therefore important to complement these studies with alternative animal models that may better replicate the individuality of human TBI. Comparative studies in animals with naturally evolved brain protection such as bighorn sheep, woodpeckers, and whales, may provide preventive applications in humans. The advantages of an in-depth study of these unconventional animals are threefold. First, to increase knowledge of the often-understudied species in question; second, to improve common animal models based on the study of their extreme counterparts; and finally, to tap into a source of biological inspiration for comparative studies and translational applications in humans

Effect of Anesthesia on Microelectrode Recordings during Deep Brain Stimulation Surgery in Tourette Syndrome Patients

Background: Deep brain stimulation (DBS) is an accepted treatment for patients with medication-resistant Tourette syndrome (TS). Sedation is commonly required during electrode implantation to attenuate anxiety, pain, and severe tics. Anesthetic agents potentially impair the quality of microelectrode recordings (MER). Little is known about the effect of these anesthetics on MER in patients with TS. We describe our experience with different sedative regimens on MER and tic severity in patients with TS. Methods: The clinical records of all TS patients who underwent DBS surgery between 2010 and 2018 were reviewed. Demographic data, stimulation targets, anesthetic agents, perioperative complications, and MER from each hemisphere were collected and analyzed. Single-unit activity was identified by filtering spiking activity from broadband MER data and principal component analysis with K-means clustering. Vocal and motor tics which caused artifacts in the MER data were manually selected using visual and auditory inspection. Results: Six patients underwent bilateral DBS electrode implantation. In all patients, the target was the anterior internal globus pallidus. Patient comfort and hemodynamic and respiratory stability were maintained with conscious sedation with one or more of the following anesthetic drugs: propofol, midazolam, remifentanil, clonidine, and dexmedetomidine. Good quality MER and clinical testing were obtained in 9 hemispheres of 6 patients. In 3 patients, MER quality was poor on one side. Conclusion: Cautiously applied sedative drugs can provide patient comfort, hemodynamic and respiratory stability, and suppress severe tics, with minimal interference with MER. (C) 2019 The Author(s) Published by S. Karger AG, Base