Beam Voltage Effects in the Study of Embedded Biological Materials by Secondary Electron Detectors

Thin and semithin sections were extensively examined by the secondary electron (SE) detector in a conventional scanning electron microscope (SEM), and in a transmission electron microscope with a scanning attachment (STEM). Various para-meters, in particular the beam voltage, were shown to affect the final SE image (SEI). As for SEM observation, a surface contrast was imaged at low primary electron (PE) voltages (0.6-2 kV), whereas a subsurface contrast predominated at higher energies (15-30 kV). In STEM, significant differences were not detected by varying the PE in the 20-100 kV range. Surface and subsurface in-formation was simultaneously imaged even though the SEI were better resolved at the highest energy

The Lectin-Gold Technique: An Overview of Applications to Pathological Problems

Lectins are proteins, mainly of vegetal origin, which recognize glycosidic residues with high specificity; for this property they have been used for many studies of molecular biology. The colloidal gold represents at present the most popular electron dense marker employed in immunocytochemistry, since it offers intrinsic and unique characteristics which are superior to those displayed by the other markers. The cytochemical method which utilizes the gold-labelled lectins takes advantages from both the two systems, in order to optimize the localization of the glycoconjugates. The present paper reviews both the technical aspects of the preparation of the lectin-gold complex and its application to some selected pathological problems. In particular, the papers concerning the eye and ear tissues, the urinary, reproductive, nervous and digestive systems and the blood cells are quoted

Learning to stop: a unifying principle for legged locomotion in varying environments.

Evolutionary studies have unequivocally proven the transition of living organisms from water to land. Consequently, it can be deduced that locomotion strategies must have evolved from one environment to the other. However, the mechanism by which this transition happened and its implications on bio-mechanical studies and robotics research have not been explored in detail. This paper presents a unifying control strategy for locomotion in varying environments based on the principle of 'learning to stop'. Using a common reinforcement learning framework, deep deterministic policy gradient, we show that our proposed learning strategy facilitates a fast and safe methodology for transferring learned controllers from the facile water environment to the harsh land environment. Our results not only propose a plausible mechanism for safe and quick transition of locomotion strategies from a water to land environment but also provide a novel alternative for safer and faster training of robots

A New Approach for Studying Semithin Sections of Human Pathological Material: Intermicroscopic Correlation Between Light Microscopy and Scanning Electron Microscopy

In order to obtain useful and complete information on the study of pathological material, we observed by scanning electron microscopy (SEM) the same semithin sections observed by light microscopy (LM). For this purpose, the specimen must have, at the same time, chromatic and electron dense characteristics. We thus developed different specimen preparation methods, subjecting the semithin sections to specific polychromatic staining with high atomic number (Z) elements, to monochromatic staining followed by routine contrasting with uranyl acetate and lead citrate, and to specific cytochemical and immunocytochemical procedures. The specimens were examined in sequence by LM, by SEM equipped with secondary electron, backscattered electron, transmitted electron detectors and by scanning transmission electron microscopy (S(T)EM)

Characterization of Mucus Glycoconjugates in Normal Human Conjunctiva by Lectins in Light Microscopy, Transmission and Scanning Electron Microscopy

Maintenance of tear film in normal conditions is dependent on 1) mucus layer integrity and 2) the presence and distribution of conjunctival epithelial cell microvilli. In the present work a new methodology has been developed to gain correlative information about microprojection assessment and mucus composition, from the same specimen, by Light Microscopy (LM), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). We have characterized the glycosidic residues secreted by goblet cells in normal human conjunctiva, by means of four lectins (WGA, ConA, PNA and SBA), conjugated with FITC for LM and with colloidal gold for TEM and SEM. The cytochemical reactions were performed on histological sections of paraffin-embedded material and on semithin and ultrathin sections of both Epon embedded material directly processed for TEM and of blocks recovered from SEM and reprocessed for TEM. WGA, ConA, PNA and SBA receptors were found to be constituents of the mucus produced by goblet cells in human conjunctiva. The granules of the so-called second mucus system (SMS) cells were labelled mainly by WGA. A difference in the quality of glycoconjugates between goblet cells and SMS cells has been also demonstrated. Our results provide an improved method to evaluate alterations of tear film that occur in many conjunctival diseases

Motor kinematic differences in children with autism sepectrum disorder : ecological gameplay with a sensorised toy

Background Evidence suggests gross motor differences are present in children with Autism Spectrum Disorder (ASD) from birth. Trevarthen and Delafield-Butt (2013) proposed that one of the early markers of ASD are abnormalities in the development of intentional movements, which are present before the manifestations of symptoms typically associated with autism, like deficiencies in social interaction and communication. A growing body of literature demonstrates kinematic and action patterns differences in children and adults with ASD. However, these experiments typically require expensive laboratory-based optical motion tracking systems. Here, we developed bespoke, sensorised wooden cubes for motor assessment of children’s play and report on the kinematic and action pattern differences of the children with autism compared to children developing typically. Objectives A description of ASD-specific action patterns and kinematics using sensorised toys. Methods Participants. Children 3 to 5 years diagnosed with ASD (n = 15) recruited from the Scottish Centre for Autism, Glasgow, UK. Children 3 to 5 years old developing typically recruited from nurseries in Glasgow, UK. Adults 20 to 25 years old without ASD recruited from Glasgow, UK. The study was approved by the University of Strathclyde Ethics Committee and consent obtained from the parents of children or the adults. In the case of the children with ASD, pre-screening with Vineland-II, AQ-Child and Leiter-R Brief IQ was performed. Procedure. The children were seated at a table and instructed to play two simple games that involved moving the cube from one position to another: a Serially Organized Action (SOA) game and a Single Repetitive Action (SRA) game. The first required complex motor sequencing and engagement with the experimenter, while the second consisted of a simple repetitive movement. Each game produced a single measured movement to a goal with 25 iterations or repetitions to yield 50 movements in total. An electronic board inside the cubes was equipped with tri-axial magnetometer, gyroscope and accelerometer wirelessly transferred the cube’s motion data to a laptop. The signal (raw motion data) was extracted through a Matlab-based platform and analysed. Data Analysis. Kinematic features of movement duration; maximum value of acceleration, velocity, and jerk during each movement; time to maximum value; % duration to maximum value; and the acceleration, velocity, and jerk action patterns profiles were calculated. Results The jerk profile of children with ASD was significantly different, showing increased maximum jerk, reduced time to maximum value and & duration to maximum value, and lower variability than typically developing children. Further, movement duration was shorter compared to age-matched typically developing children, and maximum velocity was significantly higher in children with ASD compared to children developing typically. Conclusion The increased jerk values and onset times in the ASD group are a particularly interesting finding that support new data appearing by other groups. It appeared, especially in the SRA game, that when moving the cube from one position to the next, the children with autism impacted on the surface of the table with greater velocity and typically included the resulting force immediately into to the next movement, giving it a greater jerk value in a shorter span of time that typically children. Typically developing children, on the other hand, paused for a moment (>100 ms) before commencing the next movement. Further, children with autism did not enjoy the SRA game, but they did enjoy the simpler, more repetitive SOA one. The repetitive simplicity of the SOA game and its resulting jerk profile appears to report on a particular behavioural motor feature distinct to ASD, namely stopping an action and starting a new one, while also describing an underlying motor difference that may contribute to it

Determining noise and vibration exposure in conifer cross-cutting operations by using Li-Ion batteries and electric chainsaws

In many activities, chainsaw users are exposed to the risk of injuries and several other hazard factors that may cause health problems. In fact, environmental and working conditions when using chainsaws result in workers' exposure to hazards such as noise, vibration, exhaust gases, and wood dust. Repeated or continuous exposure to these unfavourable conditions can lead to occupational diseases that become apparent after a certain period of time has elapsed. Since the use of electric tools is increasing in forestry, the present research aims to evaluate the noise and vibration exposure caused by four models of electric chainsaws (Stihl MSA160T, Stihl MSA200C Li-Ion battery powered and Stihl MSE180C, Stihl MSE220C wired) during cross-cutting. Values measured on the Stihl MSA160T chainsaw (Li-Ion battery) showed similar vibration levels on both right and left handles (0.9-1.0 m s-2, respectively) and so did the other battery-powered chainsaw, the Stihl MSA200C (2.2-2.3 m s-2 for right and left handles, respectively). Results showed a range of noise included between 81 and 90 dB(A) for the analysed chainsaws. In conclusion, the vibrations and noise were lower for the battery chainsaws than the wired ones, but, in general, all the values were lower than those measured in previous studies of endothermic chainsaws

Scanning Electron Microscopy, X-Ray Microanalysis and Immunohistochemistry on Worn Soft Contact Lenses

The deposits accumulated on the surfaces of soft contact lenses are a cause of problems for the wearer of these lenses, as the deposits are never completely removed by the available washing solutions. Therefore it appears of interest to investigate the composition of these deposits. In this paper we review the major findings in the literature and, in addition, present our personal experience. We have studied new, continuously and daily worn soft contact lenses by scanning electron microscopy (SEM), X-ray microanalysis and immunohistochemistry. We have carefully evaluated preparative methods, and we can conclude that SEM and X-ray microanalysis are best carried out on unfixed, air-dried lenses. The deposits present consist mainly of mucus, especially on the tarsal side of the lenses. Chloride and potassium, coming from the tear fluid, as well as sulfur, derived from proteins, were found. Calcium was very rarely detected. IgG, IgA, IgE and C3c complement fractions were found only on the outer surfaces and not within the lens. We believe that the best characterization of the deposits is achieved by means of correlative techniques on the same lens. In fact, this approach integrates morphology and composition