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Abstract Multiple sclerosis (MS) is a leading cause of non-traumatic disability in young adults. The highly dynamic nature of MS lesions has made them difficult to study using traditional histopathology due to the specificity of current stains. This requires numerous stains to track and study demyelinating activity in MS. Thus, we utilized Fourier transform infrared (FTIR) spectroscopy to generate holistic biomolecular profiles of demyelinating activities in MS brain tissue. Multivariate analysis can differentiate MS tissue from controls. Analysis of the absorbance spectra shows profound reductions of lipids, proteins, and phosphate in white matter lesions. Changes in unsaturated lipids and lipid chain length indicate oxidative damage in MS brain tissue. Altered lipid and protein structures suggest changes in MS membrane structure and organization. Unique carbohydrate signatures are seen in MS tissue compared to controls, indicating altered metabolic activities. Cortical lesions had increased olefinic lipid content and abnormal membrane structure in normal appearing MS cortex compared to controls. Our results suggest that FTIR spectroscopy can further our understanding of lesion evolution and disease mechanisms in MS paving the way towards improved diagnosis, prognosis, and development of novel therapeutics.

Pineal-region tumors are a histologically heterogeneous group of tumors and represent a rare occurrence, accounting for less than 1% of all adult intracranial tumors. Among these, primary pineal malignant melanomas (PPM) represent an even rarer entity, with only twenty-five cases being reported in the literature to date. We present the case of a 65-year-old patient who presented in our department for progressive headache, gait disturbance and memory impairment. Magnetic resonance imaging (MRI) of the brain revealed a solid mass in pineal region, measuring 2.2 × 1.2 × 2.0 cm and causing obstructive hydrocephalus. He underwent a third ventriculostomy, but we failed to obtain a sample for diagnostic purposes. The intraoperative surprise was the presence, at the level of the third ventricle, of multiple melanin deposits, which were not picked up by the MRI. Although the biopsy could not be performed and had to be obtained by stereotactic biopsy in a second intervention, the endoscopy findings allowed for the correct staging of the intracranial disease and appropriate treatment management.

A simple and fast experimental method of determining absolute zero temperature is presented. Air gas thermometer coupled with pressure sensor and data acquisition system COACH is applied in a wide range of temperature. By constructing a pressure vs temperature plot for air under constant volume it is possible to obtain--by extrapolation to zero pressure--a reasonable value of absolute zero temperature. The proposed way of conducting experiment allows students to "discover" intuitively the existence of minimal possible temperature and thus to understand the reason for introducing the concept of absolute zero temperature and absolute temperature Kelvin scale. It is a convincing and straightforward method to enhance understanding the general concept of temperature and support teaching thermodynamics and heat--mainly at secondary schools. This experiment was used with our university students who are being prepared to teach physics in secondary schools. They prepared physics lesson based on this material and then discussed didactic value of this material both for pupils and for teachers.

Pineal-region tumors are a histologically heterogeneous group of tumors and represent a rare occurrence, accounting for less than 1% of all adult intracranial tumors. Among these, primary pineal malignant melanomas (PPM) represent an even rarer entity, with only twenty-five cases being reported in the literature to date. We present the case of a 65-year-old patient who presented in our department for progressive headache, gait disturbance and memory impairment. Magnetic resonance imaging (MRI) of the brain revealed a solid mass in pineal region, measuring 2.2 × 1.2 × 2.0 cm and causing obstructive hydrocephalus. He underwent a third ventriculostomy, but we failed to obtain a sample for diagnostic purposes. The intraoperative surprise was the presence, at the level of the third ventricle, of multiple melanin deposits, which were not picked up by the MRI. Although the biopsy could not be performed and had to be obtained by stereotactic biopsy in a second intervention, the endoscopy findings allowed for the correct staging of the intracranial disease and appropriate treatment management. [ABSTRACT FROM AUTHOR]

Abstract Objective Neurodegeneration is thought to be the primary cause of neurological disability in multiple sclerosis (MS). Dysfunctional RNA‐binding proteins (RBPs) including their mislocalization from nucleus to cytoplasm, stress granule formation, and altered RNA metabolism have been found to underlie neurodegeneration in amyotrophic lateral sclerosis and frontotemporal dementia. Yet, little is known about the role of dysfunctional RBPs in the pathogenesis of neurodegeneration in MS. As a follow‐up to our seminal finding of altered RBP function in a single case of MS, we posited that there would be evidence of RBP dysfunction in cortical neurons in MS. Methods Cortical neurons from 12 MS and six control cases were analyzed by immunohistochemistry for heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) and TAR‐DNA‐binding protein‐43 (TDP‐43). Seven distinct neuronal phenotypes were identified based on the nucleocytoplasmic staining of these RBPs. Statistical analyses were performed by analyzing each phenotype in relation to MS versus controls. Results Analyses revealed a continuum of hnRNP A1 and TDP‐43 nucleocytoplasmic staining was found in cortical neurons, from neurons with entirely nuclear staining with little cytoplasmic staining in contrast to those with complete nuclear depletion of RBPs concurrent with robust cytoplasmic staining. The neuronal phenotypes that showed the most nucleocytoplasmic mislocalization of hnRNP A1 and TDP‐43 statistically distinguished MS from control cases (P

Bryan Hansen and Valentin Dragoi were previously included as authors in the publication [...]

Objective To establish the extent to which sound amplitudes delivered by a vibrating tuning fork change around its long axis and to evaluate whether such differences in amplitude might change the results of the Rinne test. Study Design Experimental measurements. Setting Laboratory setting. Methods Setup I: a vibrating tuning fork was handheld and manually rotated around its long axis next to a sound recording device (the simulated ear) in order to record sound amplitude data at a full range of angles relative to the device; files were split into segments in which sound amplitude changed: A (from a maximum to a minimum) and B (from a minimum to a maximum). Setup II: a vibrating tuning fork was machine-rotated, and the angle of rotation, along with the sound amplitude, was automatically recorded through a single full rotation. Results The angles of 0° and 180° (which equate to the established best practice in Rinne testing) were associated with the highest sound amplitudes. All other angles decreased sound amplitude. The greatest decrease in amplitude was recorded at 51° and 130°. This difference ranged from 9.8 to 34.7 dB, depending on the initial amplitude. Conclusion The outcome of a Rinne test can be affected if attention is not paid to the precise angle at which the tuning fork is held relative to the ear. The potential of this effect will be greater when high background noise or patient hearing loss requires that the tuning fork be vigorously excited to obtain high sound amplitudes.

It is increasingly being understood that perceptual learning involves different types of plasticity. Thus, whereas the practice-based improvement in the ability to perform specific tasks is believed to rely on top-down plasticity, the capacity of sensory systems to passively adapt to the stimuli they are exposed to is believed to rely on bottom-up plasticity. However, top-down and bottom-up plasticity have never been investigated concurrently, and hence their relationship is not well understood. To examine whether passive exposure influences perceptual performance, we asked subjects to test their orientation discrimination performance around and orthogonal to the exposed orientation axes, at an exposed and an unexposed location while oriented sine-wave gratings were presented in a fixed position. Here we report that repetitive passive exposure to oriented sequences that are not linked to a specific task induces a persistent, bottom-up form of learning that is stronger than top-down practice learning and generalizes across complex stimulus dimensions. Importantly, orientation-specific exposure learning led to a robust improvement in the discrimination of complex stimuli (shapes and natural scenes). Our results indicate that long-term sensory adaptation by passive exposure should be viewed as a form of perceptual learning that is complementary to practice learning in that it reduces constraints on speed and generalization.

Understanding how interactions within magnetic systems affect the reversal process is critical to the development of magneticrecording media. Using the first-order reversal curve (FORC) method we demonstrate an ability to map out and uniquely identifymagnetic recording media. We evaluate the interactions and intrinsic switching field distribution (SFD) in single layer and exchangecoupled composite granular recording media. Landau–Lifshitz–Gilbert-based simulations are used to probe the roles lateral andvertical exchange interactions have on the distribution of reversal events. We find that there is an optimal value for these terms whichmaximizes homogeneity of the reversal behavior.

The spin reorientation process in the Tm2-xHoxFe14B series of compounds was studied using 57Fe Mössbauer spectroscopy over the temperature range 5.2-320 K with a focus on the analysis of conical spin arrangement. Each compound was studied by precise Mössbauer scanning in the vicinity of the transition and during the transition. By applying computer simulations based on the simplified Yamada-Kato model, as well as on some literature data for R2Fe14B (R = Tm, Ho) compounds, the above series was selected for studies as it contains compounds with different spin arrangements (axial, planar, conical). It was a crucial requirement for obtaining unambiguous angular dependences when applying a simultaneous fitting procedure of Mössbauer spectra. Such an extended procedure was applied which allowed the temperature dependence of the angle describing the position of the magnetization vector to be obtained. The results were compared with those from theoretical simulations. The spin arrangement diagram was constructed. A conical spin arrangement was confirmed over a wide temperature range.

Glutamic acid decarboxylase (GAD) is an enzyme that catalyses the formation of γ-aminobutyric acid (GABA), the most important inhibitory neurotransmitter, from glutamic acid (Glu), which is considered the most important excitatory transmitter in the central and peripheral nervous systems. GAD is a key enzyme that provides a balance between Glu and GABA concentration. Hence, it can be assumed that if the GAD executes the synthesis of GABA from Glu, it is important in the stress response, and thus also in triggering the emotional states of the body that accompany stress. The aim of the study was to investigate the concentration of the GAD in motivational structures in the brain of the rabbit (Oryctolagus cuniculus) under altered homeostatic conditions caused by stress and variable availability of Glu. Summarising, the experimental results clearly showed variable concentrations of GAD in the motivational structures of the rabbit brain. The highest concentration of GAD was found in the hypothalamus, which suggests a strong effect of Glu and GABA on the activity of this brain structure. The GAD concentrations in individual experimental groups depended to a greater extent on blocking the activity of glutamate receptors than on the effects of a single stress exposure. The results obtained clearly support the possibility that a rapid change in the concentration of GAD could shift bodily responses to quickly achieve homeostasis, especially in this species. Further studies are necessary to reveal the role of the Glu–GAD–GABA system in the modulation of stress situations as well as in body homeostasis.

Atypical two-tine tuning fork is barely audible when held vibrating at an arm's length. It is enough, however, to touch its base to a table or, better, to a resonance box and the emitted sound becomes much louder. An inquiring student may pose questions: (1) Why is a bare tuning fork such a weak emitter of sound? (2) What is the role of the resonance box? and (3) Where does energy connected with larger intensity of emitted acoustic waves come from?

Abstract: The NA[D.sup.+]-dependent enzyme, [Δ.sup.1]-pyrroline-5-carboxylate dehydrogenase (P5CDH), has an important role in proline and hydroxyproline catabolism for humans. Specifically, this aldehyde dehydrogenase is responsible for the oxidation of both L-glutamate-γ-semialdehyde [...]

A classical experiment used to introduce the concept of body inertia, breaking of a thread below and above a hanging weight, is described mathematically and presented in a new way, using force sensors and a computer system.

The materials studied were polycrystalline compounds Er2−xTbxFe14B (x = 0.1, 0.2, 0.3, 0.4) which crystallize in a tetragonal lattice and display a variety of spin arrangements. The compounds have been measured with 57Fe Mössbauer spectroscopy over the temperature range 80–320 K in order to investigate the spin reorientation processes. Each compound was studied in a wide temperature range, with precise Mössbauer scanning in the vicinity of the transition. The set of spectra obtained for a given compound was analyzed using simultaneous fitting procedure to investigate the influence of the transition on the shape of the spectra. The fitting program was specified to analyze the transition according to the ‘two state model’: spins flip abruptly from initial angle to final arrangement (90° angle). Obtained results suggest that spin reorientation process cannot be described using only the mentioned above model. Additional computer simulations based on the Yamada–Kato model were conducted to determine temperature range and the type of spin alignments in the vicinity of the transition. These theoretical results supported by spectra analysis suggest the existence of intermediate (canted) spin arrangements in the studied compounds. The spin arrangement diagram was constructed.

A technique to determine experimentally the reader resolution in magnetic recording by using pseudo-random sequence (PRS) patterns written on the disc is presented. The spectrum of the PRS signal is analyzed to extract simultaneously the width of the magnetic transitions and the reader sensitivity as a function of frequency. When playback spacing is increased, reader sensitivity rolls off faster with frequency, in good quantitative agreement with modeling results involving micromagnetic simulation of the reader. The reader sensitivity is further employed to de-convolve the magnetic cluster size from measured spectra of media noise.

Nicotinamidase (Nic) is a key zinc-dependent enzyme in NAD metabolism that catalyzes the hydrolysis of nicotinamide to give nicotinic acid. A multi-scale computational approach has been used to investigate the catalytic mechanism, substrate binding and roles of active site residues of Nic from Streptococcus pneumoniae (SpNic). In particular, density functional theory (DFT), molecular dynamics (MD) and ONIOM quantum mechanics/molecular mechanics (QM/MM) methods have been employed. The overall mechanism occurs in two stages: (i) formation of a thioester enzyme-intermediate (IC2) and (ii) hydrolysis of the thioester bond to give the products. The polar protein environment has a significant effect in stabilizing reaction intermediates and in particular transition states. As a result, both stages effectively occur in one step with Stage 1, formation of IC2, being rate limiting barrier with a cost of 53.5 kJ•mol−1 with respect to the reactant complex, RC. The effects of dispersion interactions on the overall mechanism were also considered but were generally calculated to have less significant effects with the overall mechanism being unchanged. In addition, the active site lysyl (Lys103) is concluded to likely play a role in stabilizing the thiolate of Cys136 during the reaction.

This study focuses on the thermal characterization of porous gallium nitride (GaN) usingan extended 3ω method. Porous semiconductor materials provide a solution to the need for on-chipthermal insulation, a fundamental requirement for low-power, high-speed and high-accuracythermal sensors. Thermal insulation is especially important in GaN devices, due to the intrinsicallyhigh thermal conductivity of the material. The results show one order of magnitude reduction inthermal conductivity, from 130 W/mK to 10 W/mK, in line with theoretical predictions for porousmaterials. This achievement is encouraging in the quest for integrating sensors with opto-, powerandRF-electronics on a single GaN chip.