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Sample records for cerebellar mossy fibres

  1. Presynaptic calcium signalling in cerebellar mossy fibres

    DEFF Research Database (Denmark)

    Thomsen, Louiza Bohn; Jörntell, Henrik; Midtgaard, Jens

    2010-01-01

    appeared to be isolated from one another in terms of calcium signalling. CGP55845 application showed that GABA B receptors mediated presynaptic inhibition of the calcium signal over the entire firing frequency range of mossy fibres. A paired-pulse depression of the calcium signal lasting more than 1 s...... affected burst firing in mossy fibres; this paired-pulse depression was reduced by GABA B antagonists. While our results indicated that a presynaptic rosette electrophysiologically functioned as a unit, topical GABA application showed that calcium signals in the branches of complex rosettes could be...

  2. Regulation of synaptic transmission in the mossy fibre-granule cell pathway of rat cerebellum by metabotropic glutamate receptors.

    Science.gov (United States)

    Vetter, P; Garthwaite, J; Batchelor, A M

    1999-06-01

    The role of metabotropic glutamate receptors (mGluRs) in the mossy fibre-granule cell pathway in rat cerebellum was studied using slice preparations and electrophysiological techniques. Application of the group I selective agonist (S)-3,5-dihydroxyphenylglycine (DHPG) evoked, in a concentration-dependent manner (EC50 = 33 microM), a depolarising/hyperpolarising complex response from granule cells which was preferentially inhibited by the group I selective antagonist (S)-4-carboxyphenylglycine (4CPG). The group III selective agonist L-amino-4-phosphonobutyrate (AP4) evoked a hyperpolarising response (EC50 = 10 microM) which was inhibited by the group II/III selective antagonist (S)-alpha-methyl-4-phosphonophenylglycine (MPPG). The group II agonist (2S,2'R,3'R)-2-(2',3'-dicarboxylcyclopropyl)glycine (DCG-IV) elicited no measurable voltage change. The amplitude of the synaptically-mediated mossy fibre response in granule cells was unaffected during application of AP4, was reduced by DHPG and was enhanced by DCG-IV (EC50 = 80 nM). These effects were inhibited by the group selective antagonists 4CPG and (2S,1'S,2'S,3'R)-2-(2'-carboxy-3'-phenylcyclopropyl)glycine (PCCG-4), respectively. Further investigation using patch-clamp recording revealed that DCG-IV potently inhibited spontaneous GABAergic currents. We conclude that group I and III (but not group II) mGluRs are functionally expressed by granule cells, whereas unexpectedly group II or III mGluRs do not appear to be present presynaptically on mossy fibre terminals. Group II mGluRs are located on Golgi cell terminals; when activated these receptors cause disinhibition, a function which may be important for gating information transfer from the mossy fibres to the granule cells. PMID:10465684

  3. Coincidence detection of convergent perforant path and mossy fibre inputs by CA3 interneurons.

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    Calixto, Eduardo; Galván, Emilio J; Card, J Patrick; Barrionuevo, Germán

    2008-06-01

    We performed whole-cell recordings from CA3 s. radiatum (R) and s. lacunosum-moleculare (L-M) interneurons in hippocampal slices to examine the temporal aspects of summation of converging perforant path (PP) and mossy fibre (MF) inputs. PP EPSPs were evoked from the s. lacunosum-moleculare in area CA1. MF EPSPs were evoked from the medial extent of the suprapyramidal blade of the dentate gyrus. Summation was strongly supralinear when examining PP EPSP with MF EPSP in a heterosynaptic pair at the 10 ms ISI, and linear to sublinear at longer ISIs. This pattern of nonlinearities suggests that R and L-M interneurons act as coincidence detectors for input from PP and MF. Summation at all ISIs was linear in voltage clamp mode demonstrating that nonlinearities were generated by postsynaptic voltage-dependent conductances. Supralinearity was not detected when the first EPSP in the pair was replaced by a simulated EPSP injected into the soma, suggesting that the conductances underlying the EPSP boosting were located in distal dendrites. Supralinearity was selectively eliminated with either Ni2+ (30 microm), mibefradil (10 microm) or nimodipine (15 microm), but was unaffected by QX-314. This pharmacological profile indicates that supralinearity is due to recruitment of dendritic T-type Ca2+channels by the first subthreshold EPSP in the pair. Results with the hyperpolarization-activated (Ih) channel blocker ZD 7288 (50 microm) revealed that Ih restricted the time course of supralinearity for coincidently summed EPSPs, and promoted linear to sublinear summation for asynchronous EPSPs. We conclude that coincidence detection results from the counterbalanced activation of T-type Ca2+ channels and inactivation of Ih. PMID:18388134

  4. Effect of nitric oxide synthase inhibition on long-term potentiation at associational-commissural and mossy fibre synapses on CA3 pyramidal neurones.

    OpenAIRE

    Nicolarakis, P. J.; Lin, Y Q; Bennett, M. R.

    1994-01-01

    1. The sensitivity of long-term potentiation (LTP) to nitric oxide synthase (NOS) inhibition was determined for two synaptic input systems onto CA3 pyramidal neurones the LTP of which display differential sensitivity to N-methyl-D-aspartate (NMDA) receptor antagonists: the fimbrial input which activates the associational-commissural synapses on the distal apical dendrites and the mossy fibre input which synapses on the proximal apical dendrites of CA3 pyramidal neurones. 2. Following high-fre...

  5. The dentate mossy fibers

    DEFF Research Database (Denmark)

    Blaabjerg, Morten; Zimmer, Jens

    2007-01-01

    Hippocampal mossy fibers are the axons of the dentate granule cells and project to hippocampal CA3 pyramidal cells and mossy cells of the dentate hilus (CA4) as well as a number of interneurons in the two areas. Besides their role in hippocampal function, studies of which are still evolving and t...

  6. Caffeine Modulates Vesicle Release and Recovery at Cerebellar Parallel Fibre Terminals, Independently of Calcium and Cyclic AMP Signalling.

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    Katharine L Dobson

    Full Text Available Cerebellar parallel fibres release glutamate at both the synaptic active zone and at extrasynaptic sites-a process known as ectopic release. These sites exhibit different short-term and long-term plasticity, the basis of which is incompletely understood but depends on the efficiency of vesicle release and recycling. To investigate whether release of calcium from internal stores contributes to these differences in plasticity, we tested the effects of the ryanodine receptor agonist caffeine on both synaptic and ectopic transmission.Whole cell patch clamp recordings from Purkinje neurons and Bergmann glia were carried out in transverse cerebellar slices from juvenile (P16-20 Wistar rats.Caffeine caused complex changes in transmission at both synaptic and ectopic sites. The amplitude of postsynaptic currents in Purkinje neurons and extrasynaptic currents in Bergmann glia were increased 2-fold and 4-fold respectively, but paired pulse ratio was substantially reduced, reversing the short-term facilitation observed under control conditions. Caffeine treatment also caused synaptic sites to depress during 1 Hz stimulation, consistent with inhibition of the usual mechanisms for replenishing vesicles at the active zone. Unexpectedly, pharmacological intervention at known targets for caffeine--intracellular calcium release, and cAMP signalling--had no impact on these effects.We conclude that caffeine increases release probability and inhibits vesicle recovery at parallel fibre synapses, independently of known pharmacological targets. This complex effect would lead to potentiation of transmission at fibres firing at low frequencies, but depression of transmission at high frequency connections.

  7. Distributed Cerebellar Motor Learning: A Spike-Timing-Dependent Plasticity Model

    OpenAIRE

    Luque, Niceto R.; Garrido, Jesús A.; Naveros, Francisco; Carrillo, Richard R.; D'Angelo, Egidio; Ros, Eduardo

    2016-01-01

    Deep cerebellar nuclei neurons receive both inhibitory (GABAergic) synaptic currents from Purkinje cells (within the cerebellar cortex) and excitatory (glutamatergic) synaptic currents from mossy fibers. Those two deep cerebellar nucleus inputs are thought to be also adaptive, embedding interesting properties in the framework of accurate movements. We show that distributed spike-timing-dependent plasticity mechanisms (STDP) located at different cerebellar sites (parallel fibers to Purkinje ce...

  8. Model cerebellar granule cells can faithfully transmit modulated firing rate signals

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    Christian eRössert

    2014-10-01

    Full Text Available A crucial assumption of many high-level system models of the cerebellum is that information in the granular layer is encoded in a linear manner. However, granule cells are known for their non-linear and resonant synaptic and intrinsic properties that could potentially impede linear signal transmission.In this modelling study we analyse how electrophysiological granule cell properties and spike sampling influence information coded by firing rate modulation, assuming no signal-related, i.e. uncorrelated inhibitory feedback (open-loop mode.A detailed one-compartment granule cell model was excited in simulation by either direct current or mossy-fibre synaptic inputs. Vestibular signals were represented as tonic inputs to the flocculus modulated at frequencies up to 20 Hz (approximate upper frequency limit of vestibular-ocular reflex, VOR. Model outputs were assessed using estimates of both the transfer function, and the fidelity of input-signal reconstruction measured as variance-accounted-for.The detailed granule cell model with realistic mossy-fibre synaptic inputs could transmit information faithfully and linearly in the frequency range of the vestibular-ocular reflex. This was achieved most simply if the model neurons had a firing rate at least twice the highest required frequency of modulation, but lower rates were also adequate provided a population of neurons was utilized, especially in combination with push-pull coding. The exact number of neurons required for faithful transmission depended on the precise values of firing rate and noise. The model neurons were also able to combine excitatory and inhibitory signals linearly, and could be replaced by a simpler (modified integrate-and-fire neuron in the case of high tonic firing rates.These findings suggest that granule cells can in principle code modulated firing-rate inputs in a linear manner, and are thus consistent with the high-level adaptive-filter model of the cerebellar microcircuit.

  9. Excitatory Cerebellar Nucleocortical Circuit Provides Internal Amplification during Associative Conditioning.

    Science.gov (United States)

    Gao, Zhenyu; Proietti-Onori, Martina; Lin, Zhanmin; Ten Brinke, Michiel M; Boele, Henk-Jan; Potters, Jan-Willem; Ruigrok, Tom J H; Hoebeek, Freek E; De Zeeuw, Chris I

    2016-02-01

    Closed-loop circuitries between cortical and subcortical regions can facilitate precision of output patterns, but the role of such networks in the cerebellum remains to be elucidated. Here, we characterize the role of internal feedback from the cerebellar nuclei to the cerebellar cortex in classical eyeblink conditioning. We find that excitatory output neurons in the interposed nucleus provide efference-copy signals via mossy fibers to the cerebellar cortical zones that belong to the same module, triggering monosynaptic responses in granule and Golgi cells and indirectly inhibiting Purkinje cells. Upon conditioning, the local density of nucleocortical mossy fiber terminals significantly increases. Optogenetic activation and inhibition of nucleocortical fibers in conditioned animals increases and decreases the amplitude of learned eyeblink responses, respectively. Our data show that the excitatory nucleocortical closed-loop circuitry of the cerebellum relays a corollary discharge of premotor signals and suggests an amplifying role of this circuitry in controlling associative motor learning. PMID:26844836

  10. Hilar mossy cell circuitry controlling dentate granule cell excitability

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    Seiichiro Jinde

    2013-02-01

    Full Text Available Glutamatergic hilar mossy cells of the dentate gyrus can either excite or inhibit distant granule cells, depending on whether their direct excitatory projections to granule cells or their projections to local inhibitory interneurons dominate. However, it remains controversial whether the net effect of mossy cell loss is granule cell excitation or inhibition. Clarifying this controversy has particular relevance to temporal lobe epilepsy, which is marked by dentate granule cell hyperexcitability and extensive loss of dentate hilar mossy cells. Two diametrically opposed hypotheses have been advanced to explain this granule cell hyperexcitability – the “dormant basket cell” and the “irritable mossy cell” hypotheses. The “dormant basket cell” hypothesis proposes that mossy cells normally exert a net inhibitory effect on granule cells and therefore their loss causes dentate granule cell hyperexcitability. The “irritable mossy cell” hypothesis takes the opposite view that mossy cells normally excite granule cells and that the surviving mossy cells in epilepsy increase their activity, causing granule cell excitation. The inability to eliminate mossy cells selectively has made it difficult to test these two opposing hypotheses. To this end, we developed a transgenic toxin-mediated, mossy cell-ablation mouse line. Using these mutants, we demonstrated that the extensive elimination of hilar mossy cells causes granule cell hyperexcitability, although the mossy cell loss observed appeared insufficient to cause clinical epilepsy. In this review, we focus on this topic and also suggest that different interneuron populations may mediate mossy cell-induced translamellar lateral inhibition and intralamellar recurrent inhibition. These unique local circuits in the dentate hilar region may be centrally involved in the functional organization of the dentate gyrus.

  11. Hilar mossy cells of the dentate gyrus: a historical perspective

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    Helen E Scharfman

    2013-01-01

    Full Text Available The circuitry of the dentate gyrus of the hippocampus is unique compared to other hippocampal subfields because there are two glutamatergic principal cells instead of one: granule cells, which are the vast majority of the cells in the dentate gyrus, and the so-called ‘mossy cells.’ The distinctive appearance of mossy cells, the extensive divergence of their axons, and their vulnerability to excitotoxicity relative to granule cells has led to a great deal of interest in mossy cells. Nevertheless, there is no consensus about the normal functions of mossy cells and the implications of their vulnerability. There even seems to be some ambiguity about exactly what mossy cells are. Here we review initial studies of mossy cells, characteristics that define them, and suggest a practical definition to allow investigators to distinguish mossy cells from other hilar neurons even if all morphological and physiological information is unavailable due to technical limitations of their experiments. In addition, hypotheses are discussed about the role of mossy cells in the dentate gyrus network, reasons for their vulnerability and their implications for disease.

  12. Cerebellar Degeneration

    Science.gov (United States)

    ... and olivopontocerebellar degeneration, progressive degenerative disorders in which cerebellar degeneration is a key feature Friedreich’s ataxia, and other spinocerebellar ataxias, which are caused by ...

  13. Mixed neurotransmission in the hippocampal mossy fibers

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    Agnieszka eMuenster-Wandowski

    2013-11-01

    Full Text Available The hippocampal mossy fibers (MFs, the axons of the granule cells of the dentate gyrus, innervate mossy cells and interneurons in the hilus on its way to CA3 where they innervate interneurons and pyramidal cells. Synapses on each target cell have distinct anatomical and functional characteristics. In recent years, the paradigmatic view of the MF synapses being only glutamatergic and, thus, excitatory has been questioned. Several laboratories have provided data supporting the hypothesis that the MFs can transiently release GABA during development and, in the adult, after periods of enhanced excitability. This transient glutamate-GABA co-transmission coincides with the transient expression of the machinery for the synthesis and release of GABA in the glutamatergic granule cells. Although some investigators have deemed this evidence controversial, new data has appeared with direct evidence of co-release of glutamate and GABA from single, identified MF boutons. However, this must still be confirmed by other groups and with other methodologies. A second, intriguing observation is that MF activation produced fast spikelets followed by excitatory postsynaptic potentials in a number of pyramidal cells, which, unlike the spikelets, underwent frequency potentiation and were strongly depressed by activation of metabotropic glutamate receptors. The spikelets persisted during blockade of chemical transmission and were suppressed by the gap junction blocker carbenoxolone. These data is consistent with the hypothesis of mixed electrical-chemical synapses between MFs and some pyramidal cells. Dye coupling between these types of principal cells and ultrastructural studies showing the co-existence of AMPA receptors and connexin 36 in this synapse corroborate their presence. A deeper consideration of mixed neurotransmission taking place in this synapse may expand our search and understanding of communication channels between different regions of the mammalian CNS.

  14. Modulatory effects of serotonin on glutamatergic synaptic transmission and long-term depression in the deep cerebellar nuclei.

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    Murano, M; Saitow, F; Suzuki, H

    2011-01-13

    The deep cerebellar nuclei (DCN) are the terminal components of the cerebellar circuitry and constitute its primary output structure. Their activity is important for certain forms of motor learning as well as generation and control of movement. DCN neurons receive glutamatergic excitatory inputs from the pontine nuclei via mossy fibres (MFs) and concomitantly receive inputs from 5-HT-containing neurons of the raphe nuclei. We aimed to explore the roles of 5-HT at MF-DCN synapses by using cerebellar slices from 11 to 15-day-old rats. Bath application of 5-HT reversibly decreased the amplitude of stimulation-evoked excitatory postsynaptic currents (eEPSCs) via the activation of 5-HT1B receptors at the presynaptic terminals of the MFs. Burst stimulation of the MFs elicited long-term depression (LTD) at the MF-DCN synapses that require activation of the group I metabotropic glutamate receptor (mGluR). In the presence of 5-HT, the extent of burst-induced LTD of MF EPSCs was significantly reduced. Application of 5-HT also decreased the amplitude of mGluR-dependent slow EPSCs evoked by similar burst stimulation. Furthermore, (S)-3,5-dihydroxyphenylglycine (DHPG), a group I mGluR agonist, induced chemical LTD of MF EPSCs, and 5-HT had no significant effect on this LTD. Taken together, the results suggest that 5-HT not only has transitory inhibitory effects on MF EPSCs but also plays a role in regulating the long-term synaptic efficacy. PMID:20969929

  15. In the Rat Cerebellar Cortex

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    Gokhan Ordek

    2014-10-01

    Full Text Available The changes of excitability in affected neural networks can be used as a marker to study the temporal course of traumatic brain injury (TBI. The cerebellum is an ideal platform to study brain injury mechanisms at the network level using the electrophysiological methods. Within its crystalline morphology, the cerebellar cortex contains highly organized topographical subunits that are defined by two main inputs, the climbing and mossy fibers. Here we demonstrate the use of cerebellar evoked potentials (EPs mediated through these afferent systems for monitoring the injury progression in a rat model of fluid percussion injury (FPI. A mechanical tap on the dorsal hand was used as a stimulus, and EPs were recorded from the paramedian lobule (PML of the posterior cerebellum via multi-electrode arrays (MEA. Post-injury evoked response amplitudes (EPAs were analyzed on a daily basis for one week and compared with pre-injury values. We found a trend of consistently decreasing EPAs in all nine animals, losing as much as 72±4% of baseline amplitudes measured before the injury. Notably, our results highlighted two particular time windows; the first 24 hours of injury in the acute period and day-3 to day-7 in the delayed period where the largest drops (~50% and 24% were observed in the EPAs. In addition, cross-correlations of spontaneous signals between electrode pairs declined (from 0.47±0.1 to 0.35±0.04, p<0.001 along with the EPAs throughout the week of injury. In support of the electrophysiological findings, immunohistochemical analysis at day-7 post-injury showed detectable Purkinje cell loss at low FPI pressures and more with the largest pressures used. Our results suggest that sensory evoked potentials recorded from the cerebellar surface can be a useful technique to monitor the course of cerebellar injury and identify the phases of injury progression even at mild levels.

  16. Cerebellar Hypoplasia

    Science.gov (United States)

    ... disorders that begin in early childhood, such as ataxia telangiectasia. In an infant or young child, symptoms of a disorder that features cerebellar hypoplasia might include floppy muscle tone, developmental or ...

  17. Acute cerebellar ataxia

    Science.gov (United States)

    Cerebellar ataxia; Ataxia - acute cerebellar; Cerebellitis; Post-varicella acute cerebellar ataxia; PVACA ... Acute cerebellar ataxia in children, especially younger than age 3, may occur several weeks after an illness caused by a virus. ...

  18. [Cerebellar stroke].

    Science.gov (United States)

    Paradowski, Michał; Zimny, Anna; Paradowski, Bogusław

    2015-01-01

    Cerebellar stroke belongs to a group of rare diseases of vascular origin. Cerebellum, supplied by three pairs of arteries (AICA, PICA, SCA) with many anastomoses between them is less susceptible for a stroke, especially ischemic one. Diagnosis of the stroke in this region is harder due to lower sensibility of commonly used CT of the head in case of stroke suspicion. The authors highlight clinical symptoms distinguishing between vascular territories or topographical locations of the stroke, diagnostic procedures, classical and surgical treatment, the most common misdiagnoses are also mentioned. The authors suggest a diagnostic and therapeutic algorithm development, including rtPA treatment criteria for ischemic cerebellar stroke. PMID:26181157

  19. Cerebellar abiotrophy.

    Science.gov (United States)

    DeBowes, R M; Leipold, H W; Turner-Beatty, M

    1987-08-01

    Cerebellar abiotrophy is a degenerative condition of Arabian horses that produces signs of head tremors and ataxia. Affected foals demonstrate clinical signs between the time of birth and 6 months of age. The condition is untreatable, although some animals have reportedly improved to varying degrees. The disease is believed to be inherited; however, definitive evidence is lacking at this time. PMID:3497695

  20. High-pass filtering and dynamic gain regulation enhance vertical bursts transmission along the mossy fiber pathway of cerebellum

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    Jonathan Mapelli

    2010-05-01

    Full Text Available Signal elaboration in the cerebellum mossy fiber input pathway presents controversial aspects, especially concerning gain regulation and the spot-like (rather than beam-like appearance of granular-to-molecular layer transmission. By using voltage-sensitive dye (VSD imaging in rat cerebellar slices (Mapelli et al., 2010, we found that mossy fiber bursts optimally excited the granular layer above ~50 Hz and the overlaying molecular layer above ~100 Hz, thus generating a cascade of high-pass filters. NMDA receptors enhanced transmission in the granular, while GABA-A receptors depressed transmission in both the granular and molecular layer. Burst transmission gain was controlled through a dynamic frequency-dependent involvement of these receptors. Moreover, while high-frequency transmission was enhanced along vertical lines connecting the granular to molecular layer, no high-frequency enhancement was observed along the parallel fiber axis in the molecular layer. This was probably due to the stronger effect of Purkinje cell GABA-A receptor-mediated inhibition occurring along the parallel fibers than along the granule cell axon ascending branch. The consequent amplification of burst responses along vertical transmission lines could explain the spot-like activation of Purkinje cells observed following punctuate stimulation in vivo .

  1. Control of cerebellar granule cell output by sensory-evoked Golgi cell inhibition

    OpenAIRE

    Duguid, Ian; BRANCO, Tiago; Chadderton, Paul; Arlt, Charlotte; Powell, Kate; Häusser, Michael

    2015-01-01

    Understanding how synaptic inhibition regulates sensory responses is a fundamental question in neuroscience. In cerebellar granule cells, sensory stimulation is thought to evoke an excitation–inhibition sequence driven by direct input from mossy fibers and followed by classical disynaptic feed-forward inhibition from nearby Golgi cells. We made, to our knowledge, the first voltage-clamp recordings of sensory-evoked inhibition in granule cells in vivo and show that, surprisingly, sensory-evoke...

  2. The cerebellar Golgi cell and spatiotemporal organization of granular layer activity

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    Egidio eD‘Angelo

    2013-05-01

    Full Text Available The cerebellar granular layer has been suggested to perform a complex spatiotemporal reconfiguration of incoming mossy fiber signals. Central to this role is the inhibitory action exerted by Golgi cells over granule cells: Golgi cells inhibit granule cells through double feedforward and feedback inhibitory loops and generate a broad lateral inhibition that extends beyond the afferent synaptic field. This characteristic connectivity has recently been investigated in great detail and been correlated with specific functional properties of the neuron. These include theta-frequency pacemaking, network entrainment into coherent oscillations and phase resetting. Important advances have also been made in terms of determining the membrane and synaptic properties of the neuron, and clarifying the mechanisms of activation by input bursts. Moreover, voltage sensitive dye imaging and multi-electrode array recordings, combined with mathematical simulations based on realistic computational models, have improved our understanding of the impact of Golgi cell activity on granular layer circuit computations. These investigations have highlighted the critical role of Golgi cells in: generating dense clusters of granule cell activity organized in center-surround structures, implementing combinatorial operations on multiple mossy fiber inputs, regulating transmission gain and cut-off frequency, controlling spike timing and burst transmission, and determining the sign, intensity and extension of long-term synaptic plasticity at the mossy fiber-granule cell relay. This review considers recent advances in the field, highlighting the functional implications of Golgi cells for granular layer network computation and indicating new challenges for cerebellar research.

  3. Adaptive robotic control driven by a versatile spiking cerebellar network.

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    Casellato, Claudia; Antonietti, Alberto; Garrido, Jesus A; Carrillo, Richard R; Luque, Niceto R; Ros, Eduardo; Pedrocchi, Alessandra; D'Angelo, Egidio

    2014-01-01

    The cerebellum is involved in a large number of different neural processes, especially in associative learning and in fine motor control. To develop a comprehensive theory of sensorimotor learning and control, it is crucial to determine the neural basis of coding and plasticity embedded into the cerebellar neural circuit and how they are translated into behavioral outcomes in learning paradigms. Learning has to be inferred from the interaction of an embodied system with its real environment, and the same cerebellar principles derived from cell physiology have to be able to drive a variety of tasks of different nature, calling for complex timing and movement patterns. We have coupled a realistic cerebellar spiking neural network (SNN) with a real robot and challenged it in multiple diverse sensorimotor tasks. Encoding and decoding strategies based on neuronal firing rates were applied. Adaptive motor control protocols with acquisition and extinction phases have been designed and tested, including an associative Pavlovian task (Eye blinking classical conditioning), a vestibulo-ocular task and a perturbed arm reaching task operating in closed-loop. The SNN processed in real-time mossy fiber inputs as arbitrary contextual signals, irrespective of whether they conveyed a tone, a vestibular stimulus or the position of a limb. A bidirectional long-term plasticity rule implemented at parallel fibers-Purkinje cell synapses modulated the output activity in the deep cerebellar nuclei. In all tasks, the neurorobot learned to adjust timing and gain of the motor responses by tuning its output discharge. It succeeded in reproducing how human biological systems acquire, extinguish and express knowledge of a noisy and changing world. By varying stimuli and perturbations patterns, real-time control robustness and generalizability were validated. The implicit spiking dynamics of the cerebellar model fulfill timing, prediction and learning functions. PMID:25390365

  4. Electrophysiological, morphological and topological properties of two histochemically distinct subpopulations of cerebellar unipolar brush cells

    OpenAIRE

    Kim, Jin-Ah; Sekerková, Gabriella; Mugnaini, Enrico; Martina, Marco

    2012-01-01

    Unipolar brush cells (UBCs) are excitatory cerebellar granular layer interneurons whose brush-like dendrites receive one-to-one mossy fiber inputs. Subclasses of UBCs differ primarily by expressing metabotropic glutamate receptor (mGluR) 1α or calretinin. We used GENSAT Tg(Grp-EGFP) BAC-transgenic mice, which selectively express EGFP in mGluR1α-positive UBCs to compare the functional properties of the two subclasses. Compared to EGFP-negative UBCs, which include the calretinin-positive cells,...

  5. Contribution of cerebellar sensorimotor adaptation to hippocampal spatial memory.

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    Jean-Baptiste Passot

    Full Text Available Complementing its primary role in motor control, cerebellar learning has also a bottom-up influence on cognitive functions, where high-level representations build up from elementary sensorimotor memories. In this paper we examine the cerebellar contribution to both procedural and declarative components of spatial cognition. To do so, we model a functional interplay between the cerebellum and the hippocampal formation during goal-oriented navigation. We reinterpret and complete existing genetic behavioural observations by means of quantitative accounts that cross-link synaptic plasticity mechanisms, single cell and population coding properties, and behavioural responses. In contrast to earlier hypotheses positing only a purely procedural impact of cerebellar adaptation deficits, our results suggest a cerebellar involvement in high-level aspects of behaviour. In particular, we propose that cerebellar learning mechanisms may influence hippocampal place fields, by contributing to the path integration process. Our simulations predict differences in place-cell discharge properties between normal mice and L7-PKCI mutant mice lacking long-term depression at cerebellar parallel fibre-Purkinje cell synapses. On the behavioural level, these results suggest that, by influencing the accuracy of hippocampal spatial codes, cerebellar deficits may impact the exploration-exploitation balance during spatial navigation.

  6. Spatial, contextual and working memory are not affected by the absence of mossy fiber long-term potentiation and depression

    NARCIS (Netherlands)

    Hensbroek, R.A.; Kamal, A.; Baars, A.M.; Verhage, M.; Spruijt, B.M.

    2003-01-01

    The mossy fibers of the hippocampus display NMDA-receptor independent long-term plasticity. A number of studies addressed the role of mossy fiber long-term plasticity in memory, but have provided contrasting results. Here, we have exploited a genetic model, the rab3A null-mutant, which is characteri

  7. Recurrent cerebellar architecture solves the motor-error problem

    OpenAIRE

    Porrill, J.; P Dean; Stone, J.V.

    2004-01-01

    Current views of cerebellar function have been heavily influenced by the models of Marr and Albus, who suggested that the climbing fibre input to the cerebellum acts as a teaching signal for motor learning. It is commonly assumed that this teaching signal must be motor error (the difference between actual and correct motor command), but this approach requires complex neural structures to estimate unobservable motor error from its observed sensory consequences. We have proposed elsewhere a...

  8. Extracellular proteolysis in structural and functional plasticity of mossy fiber synapses in hippocampus

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    Grzegorz eWiera

    2015-11-01

    Full Text Available Brain is continuously altered in response to experience and environmental changes. One of the underlying mechanisms is synaptic plasticity, which is manifested by modification of synapse structure and function. It is becoming clear that regulated extracellular proteolysis plays a pivotal role in the structural and functional remodeling of synapses during brain development, learning and memory formation. Clearly, plasticity mechanisms may substantially differ between projections. Mossy fiber synapses onto CA3 pyramidal cells display several unique functional features, including pronounced short-term facilitation, a presynaptically expressed LTP that is independent of NMDAR activation, and NMDA-dependent metaplasticity. Moreover, structural plasticity at mossy fiber synapses ranges from the reorganization of projection topology after hippocampus-dependent learning, through intrinsically different dynamic properties of synaptic boutons to pre- and postsynaptic structural changes accompanying LTP induction. Although concomitant functional and structural plasticity in this pathway strongly suggests a role of extracellular proteolysis, its impact only starts to be investigated in this projection. In the present report, we review the role of extracellular proteolysis in various aspects of synaptic plasticity in hippocampal mossy fiber synapses. A growing body of evidence demonstrates that among perisynaptic proteases, tPA/plasmin system, β-site amyloid precursor protein-cleaving enzyme 1 (BACE1 and metalloproteinases play a crucial role in shaping plastic changes in this projection. We discuss recent advances and emerging hypotheses on the roles of proteases in mechanisms underlying mossy fiber target specific synaptic plasticity and memory formation.

  9. Primary progressive cerebellar ataxia

    International Nuclear Information System (INIS)

    Thirty-two patients with primary progressive cerebellar ataxia were studied using MRI. This technique is better than CT in demonstrating atrophy of cerebellar structures as well as of brainstem and spinal cord. The differential diagnosis from other diseases particularly with multiple sclerosis is easier. The degree of ataxia correlated well with the degree of atrophy of cerebellum. However, we could not see any correlation between the degree of atrophy and the onset and duration of the disease and no certain specific aspects could be demonstrated in the different groups examined. (orig.)

  10. Cerebellar anatomy as applied to cerebellar microsurgical resections

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    Alejandro Ramos

    2012-06-01

    Full Text Available OBJECTIVE: To define the anatomy of dentate nucleus and cerebellar peduncles, demonstrating the surgical application of anatomic landmarks in cerebellar resections. METHODS: Twenty cerebellar hemispheres were studied. RESULTS: The majority of dentate nucleus and cerebellar peduncles had demonstrated constant relationship to other cerebellar structures, which provided landmarks for surgical approaching. The lateral border is separated from the midline by 19.5 mm in both hemispheres. The posterior border of the cortex is separated 23.3 mm from the posterior segment of the dentate nucleus; the lateral one is separated 26 mm from the lateral border of the nucleus; and the posterior segment of the dentate nucleus is separated 25.4 mm from the posterolateral angle formed by the junction of lateral and posterior borders of cerebellar hemisphere. CONCLUSIONS: Microsurgical anatomy has provided important landmarks that could be applied to cerebellar surgical resections.

  11. Consensus Paper: Neuroimmune Mechanisms of Cerebellar Ataxias.

    Science.gov (United States)

    Mitoma, Hiroshi; Adhikari, Keya; Aeschlimann, Daniel; Chattopadhyay, Partha; Hadjivassiliou, Marios; Hampe, Christiane S; Honnorat, Jérôme; Joubert, Bastien; Kakei, Shinji; Lee, Jongho; Manto, Mario; Matsunaga, Akiko; Mizusawa, Hidehiro; Nanri, Kazunori; Shanmugarajah, Priya; Yoneda, Makoto; Yuki, Nobuhiro

    2016-04-01

    In the last few years, a lot of publications suggested that disabling cerebellar ataxias may develop through immune-mediated mechanisms. In this consensus paper, we discuss the clinical features of the main described immune-mediated cerebellar ataxias and address their presumed pathogenesis. Immune-mediated cerebellar ataxias include cerebellar ataxia associated with anti-GAD antibodies, the cerebellar type of Hashimoto's encephalopathy, primary autoimmune cerebellar ataxia, gluten ataxia, Miller Fisher syndrome, ataxia associated with systemic lupus erythematosus, and paraneoplastic cerebellar degeneration. Humoral mechanisms, cell-mediated immunity, inflammation, and vascular injuries contribute to the cerebellar deficits in immune-mediated cerebellar ataxias. PMID:25823827

  12. Operando electron paramagnetic resonance spectroscopy – formation of mossy lithium on lithium anodes during charge–discharge cycling

    OpenAIRE

    Wandt, Johannes; Marino, Cyril; Gasteiger, Hubert A.; Jakes, Peter; Eichel, Rüdiger-A.; Granwehr, Josef

    2015-01-01

    The formation of mossy lithium and lithium dendrites so far prevents the use of lithium metal anodes in lithium ion batteries. To develop solutions for this problem (e.g., electrolyte additives), operando measurement techniques are required to monitor mossy lithium and dendrite formation during electrochemical cycling. Here we present a novel battery cell design that enables operando electron paramagnetic resonance (EPR) spectroscopy. It is shown that time-resolved operando EPR spectroscopy d...

  13. Conditions and constraints for astrocyte calcium signaling in the hippocampal mossy fiber pathway

    OpenAIRE

    Haustein, Martin D.; Kracun, Sebastian; Lu, Xiao-Hong; Shih, Tiffany; Jackson-Weaver, Olan; Tong, Xiaoping; Xu, Ji; Yang, X William; O'Dell, Thomas J.; Marvin, Jonathan S.; Ellisman, Mark H.; Bushong, Eric A.; Looger, Loren L.; Khakh, Baljit S.

    2014-01-01

    The spatiotemporal activities of astrocyte Ca2+ signaling in mature neuronal circuits remain unclear. We used genetically encoded Ca2+ and glutamate indicators as well as pharmacogenetic and electrical control of neurotransmitter release to explore astrocyte activity in the hippocampal mossy fiber pathway. Our data revealed numerous localised spontaneous Ca2+ signals in astrocyte branches and territories, but these were not driven by neuronal activity or glutamate. Moreover, evoked astrocyte ...

  14. The primary vestibular projection to the cerebellar cortex in the pigeon (Columba livia)

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, I.E.; Schwarz, D.W.

    1983-06-01

    The cerebellar cortex of the pigeon receiving direct vestibular afferents was delineated by anterograde transport of (/sup 3/H)-amino acids injected into the vestibular nerve. Labelled mossy fiber rosettes in the granular layer were concentrated in lobule X (nodulus) and to a lesser extent, in the ventral portion of lobule IXd (uvula and paraflocculus). A few solitary labelled rosettes were also found in more dorsal portions of lobule IX, as well as in the anterior lobe between lobule II and IV. The lingula remained unlabelled. Discrete injections of (/sup 3/H)-leucine into the cristae of each of the three semicircular canals or the utricular macula yielded a similar distribution of fewer labelled rosettes. A few primary mossy fiber terminals labelled after cochlear injections are attributed to afferents from the lagenar macula. Since effective diffusion of label from the injection site was excluded by controls, it is concluded that projection of individual canal and macula nerves to the vestibulocerebellar cortex is not topographically separated. It is proposed that this extensive convergence of various afferents is required by the cerebellum to compute precise and directionally specific control signals during head rotation in all conceivable planes.

  15. The primary vestibular projection to the cerebellar cortex in the pigeon (Columba livia)

    International Nuclear Information System (INIS)

    The cerebellar cortex of the pigeon receiving direct vestibular afferents was delineated by anterograde transport of [3H]-amino acids injected into the vestibular nerve. Labelled mossy fiber rosettes in the granular layer were concentrated in lobule X (nodulus) and to a lesser extent, in the ventral portion of lobule IXd (uvula and paraflocculus). A few solitary labelled rosettes were also found in more dorsal portions of lobule IX, as well as in the anterior lobe between lobule II and IV. The lingula remained unlabelled. Discrete injections of [3H]-leucine into the cristae of each of the three semicircular canals or the utricular macula yielded a similar distribution of fewer labelled rosettes. A few primary mossy fiber terminals labelled after cochlear injections are attributed to afferents from the lagenar macula. Since effective diffusion of label from the injection site was excluded by controls, it is concluded that projection of individual canal and macula nerves to the vestibulocerebellar cortex is not topographically separated. It is proposed that this extensive convergence of various afferents is required by the cerebellum to compute precise and directionally specific control signals during head rotation in all conceivable planes

  16. Photonic crystal fibres - novel fibres, new applications

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Riishede, Jesper; Libori, Stig E. Barkou; Broeng, Jes

    Photonic crystal fibres with an air-silica micro-structured cross-section, offer novel fibre designs and new fibre characteristics, compared to standard silica fibres, such as new guiding mechanisms, different group velocity dispersion characteristics and new possibilities when designed as non...

  17. Diffusion-and T2-weighted MRI of the transverse pontine fibres in spinocerebellar degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, M.; Hosoya, T.; Yamaguchi, K. [Dept. of Radiology, Yamagata University School of Medicine (Japan); Kawanami, T.; Kato, T. [3. Dept. of Internal Medicine, Yamagata University School of Medicine (Japan)

    2000-11-01

    Because the transverse pontine fibres degenerate in some subtypes of spinocerebellar degeneration (SCD), demonstration of these fibres may be helpful for radiological diagnosis of SCD. Using multishot diffusion-weighted MRI, we attempted to find a way to show the transverse pontine fibres. We assessed the quality of demonstration of these fibres on DWI and of abnormal high signal in the pons and middle cerebellar peduncles on T2-weighted images. We examined evaluated 24 control subjects and 12 patients with SCD: two with sporadic olivopontocerebellar atrophy (OPCA), five with spinocerebellar ataxia type 1 (SCA1), two with SCA3, and three with SCA6. In all control subjects and patients with SCA6, we succeeded in demonstrating the transverse pontine fibres as clear low-signal bundles using DWI. In two patients with SCA3, these fibres were identified less distinctly. In contrast, in two patients with sporadic OPCA and in four of five patients with SCA1, the fibres were not identified. In both patients with sporadic OPCA, abnormal high-signal foci were seen in the base of the pons and middle cerebellar peduncles on T2-weighted images; no such foci were detected in any patient with SCA1, SCA3 or SCA6. DWI seems to be useful for demonstrating transverse pontine fibres. Abnormal high signal in the pons and middle cerebellar peduncles may provide a clue to differentiation of sporadic OPCA from other types of SCD. (orig.)

  18. Surviving mossy cells enlarge and receive more excitatory synaptic input in a mouse model of temporal lobe epilepsy.

    Science.gov (United States)

    Zhang, Wei; Thamattoor, Ajoy K; LeRoy, Christopher; Buckmaster, Paul S

    2015-05-01

    Numerous hypotheses of temporal lobe epileptogenesis have been proposed, and several involve hippocampal mossy cells. Building on previous hypotheses we sought to test the possibility that after epileptogenic injuries surviving mossy cells develop into super-connected seizure-generating hub cells. If so, they might require more cellular machinery and consequently have larger somata, elongate their dendrites to receive more synaptic input, and display higher frequencies of miniature excitatory synaptic currents (mEPSCs). To test these possibilities pilocarpine-treated mice were evaluated using GluR2-immunocytochemistry, whole-cell recording, and biocytin-labeling. Epileptic pilocarpine-treated mice displayed substantial loss of GluR2-positive hilar neurons. Somata of surviving neurons were 1.4-times larger than in controls. Biocytin-labeled mossy cells also were larger in epileptic mice, but dendritic length per cell was not significantly different. The average frequency of mEPSCs of mossy cells recorded in the presence of tetrodotoxin and bicuculline was 3.2-times higher in epileptic pilocarpine-treated mice as compared to controls. Other parameters of mEPSCs were similar in both groups. Average input resistance of mossy cells in epileptic mice was reduced to 63% of controls, which is consistent with larger somata and would tend to make surviving mossy cells less excitable. Other intrinsic physiological characteristics examined were similar in both groups. Increased excitatory synaptic input is consistent with the hypothesis that surviving mossy cells develop into aberrantly super-connected seizure-generating hub cells, and soma hypertrophy is indirectly consistent with the possibility of axon sprouting. However, no obvious evidence of hyperexcitable intrinsic physiology was found. Furthermore, similar hypertrophy and hyper-connectivity has been reported for other neuron types in the dentate gyrus, suggesting mossy cells are not unique in this regard. Thus

  19. Consensus Paper: Neuroimmune Mechanisms of Cerebellar Ataxias

    OpenAIRE

    Mitoma, Hiroshi; Adhikari, Keya; Aeschlimann, Daniel; Chattopadhyay, Partha; Hadjivassiliou, Marios; Hampe, Christiane S.; Honnorat, Jérôme; Joubert, Bastien; Kakei, Shinji; Lee, Jongho; Manto, Mario; Matsunaga, Akiko; Mizusawa, Hidehiro; Nanri, Kazunori; Shanmugarajah, Priya

    2015-01-01

    In the last few years, a lot of publications suggested that disabling cerebellar ataxias may develop through immune-mediated mechanisms. In this consensus paper, we discuss the clinical features of the main described immune-mediated cerebellar ataxias and address their presumed pathogenesis. Immune-mediated cerebellar ataxias include cerebellar ataxia associated with anti-GAD antibodies, the cerebellar type of Hashimoto’s encephalopathy, primary autoimmune cerebellar ataxia, gluten ataxia, Mi...

  20. Connections of the lateral reticular nucleus to the lateral vestibular nucleus in the rat. An anterograde tracing study with Phaseolus vulgaris leucoagglutinin

    OpenAIRE

    Ruigrok, Tom; Cella, Massimo; Voogd, J.

    1995-01-01

    textabstractEfferent projections from the lateral reticular nucleus in the rat were investigated with anterograde transport of Phaseolus vulgaris leucoagglutinin. Besides the well known mossy fibre connections to the cerebellar cortex and collaterals to the cerebellar nuclei, a substantial bilateral projection to the lateral vestibular nucleus was found. Terminal arborizations found within this nucleus appeared to detach from the reticulocerebellar fibres in the cerebellar white matter and en...

  1. [Cerebellar cognitive affective syndrome secondary to a cerebellar tumour].

    Science.gov (United States)

    Domínguez-Carral, J; Carreras-Sáez, I; García-Peñas, J J; Fournier-Del Castillo, C; Villalobos-Reales, J

    2015-01-01

    Cerebellar cognitive affective syndrome is characterized by disturbances of executive function, impaired spatial cognition, linguistic difficulties, and personality change. The case of an 11 year old boy is presented, with behavior problems, learning difficulties and social interaction problems. In the physical examination he had poor visual contact, immature behavior, reduced expressive language and global motor disability with gait dyspraxia, with no defined cerebellar motor signs. In the neuropsychological evaluation he has a full scale overall intellectual quotient of 84, with signs of cerebellar cognitive affective syndrome. A tumour affecting inferior cerebellar vermis was observed in the magnetic resonance imaging, which had not significantly grown during 5 years of follow up. The cerebellum participates in controlling cognitive and affective functions. Cerebellar pathology must be considered in the differential diagnosis of children with cognitive or learning disorder with associated behavioral and emotional components. PMID:24954915

  2. Scintillating fibres

    International Nuclear Information System (INIS)

    In the search for new detector techniques, scintillating fibre technology has already gained a firm foothold, and is a strong contender for the extreme experimental conditions of tomorrow's machines. Organized by a group from the Institute of High Energy Physics, Berlin-Zeuthen, a workshop held from 3-5 September in the nearby village of Blossin brought together experts from East and West, and from science and industry

  3. Connections of the lateral reticular nucleus to the lateral vestibular nucleus in the rat. An anterograde tracing study with Phaseolus vulgaris leucoagglutinin

    NARCIS (Netherlands)

    T.J.H. Ruigrok (Tom); M. Cella (Massimo); J. Voogd

    1995-01-01

    textabstractEfferent projections from the lateral reticular nucleus in the rat were investigated with anterograde transport of Phaseolus vulgaris leucoagglutinin. Besides the well known mossy fibre connections to the cerebellar cortex and collaterals to the cerebellar nuclei, a substantial bilateral

  4. Sleep disorders in cerebellar ataxias

    Directory of Open Access Journals (Sweden)

    José L. Pedroso

    2011-04-01

    Full Text Available Cerebellar ataxias comprise a wide range of etiologies leading to central nervous system-related motor and non-motor symptoms. Recently, a large body of evidence has demonstrated a high frequency of non-motor manifestations in cerebellar ataxias, specially in autosomal dominant spinocerebellar ataxias (SCA. Among these non-motor dysfunctions, sleep disorders have been recognized, although still under or even misdiagnosed. In this review, we highlight the main sleep disorders related to cerebellar ataxias focusing on REM sleep behavior disorder (RBD, restless legs syndrome (RLS, periodic limb movement in sleep (PLMS, excessive daytime sleepiness (EDS, insomnia and sleep apnea.

  5. Metastatic cerebellar tumor of papillary thyroid carcinoma mimicking cerebellar hemangioblastoma

    OpenAIRE

    Ideguchi, Makoto; Nishizaki, Takafumi; Ikeda, Norio; Nakano, Shigeki; Okamura, Tomomi; Fujii, Natsumi; Kimura, Tokuhiro; Ikeda, Eiji

    2016-01-01

    Introduction Well-differentiated papillary thyroid carcinoma generally (PTC) have a favorable prognosis. This metastasis is rare in the central nervous system. Brain metastasis has a relatively poor prognosis. We present a rare case of cerebellar metastasis, one that mimics a solid type cerebellar hemangioblastoma and because of which it was very hard to reach accurate preoperative diagnosis. Accurate diagnosis was challenging because of the similar imaging and histopathological findings for ...

  6. Cerebellar Malformations and Cognitive Disdorders

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2007-10-01

    Full Text Available The behavioral developmental profile of 27 children and adults (17 males and 10 females with congenital cerebellar malformations was determined in a clinical, neuroradiological and neuropsychological study at the Scientific Institute 'E Medea', University of Milano, Italy.

  7. Dock leaf beetle, Gastrophysa viridula Deg., herbivory on Mossy Sorrel, Rumex confertus Willd: Induced plant volatiles and beetle orientation responses

    Science.gov (United States)

    The invasive weed Rumex confertus Willd. (mossy sorrel) is fed upon and severely defoliated by Gastrophysa viridula Deg. (dock leaf beetle), a highly promising biological control agent for this weed. We report volatile organic compound (VOC) induction when one leaf on R. confertus was damaged by G. ...

  8. Cognition and Emotion in Cerebellar Disorders

    Science.gov (United States)

    ... FREQUENTLY ASKED QUESTIONS ABOUT... Cognition and Emotion in Cerebellar Disorders Are problems in the areas of cognition and ... active investigation. Why is this important for the ataxia patient? Cerebellar patients and families generally find it helpful to ...

  9. Familial cerebellar ataxia and diabetes insipidus.

    OpenAIRE

    Robinson, I C; O'Malley, B P; Young, I D

    1988-01-01

    Two sisters are reported who both developed partial cranial diabetes insipidus in their 4th decade, followed by progressive cerebellar ataxia. This appears to be the first report of cerebellar ataxia and diabetes insipidus occurring together as a genetic entity.

  10. Alcohol Withdrawal and Cerebellar Mitochondria.

    Science.gov (United States)

    Jung, Marianna E

    2015-08-01

    Cerebellar disorders trigger the symptoms of movement problems, imbalance, incoordination, and frequent fall. Cerebellar disorders are shown in various CNS illnesses including a drinking disorder called alcoholism. Alcoholism is manifested as an inability to control drinking in spite of adverse consequences. Human and animal studies have shown that cerebellar symptoms persist even after complete abstinence from drinking. In particular, the abrupt termination (ethanol withdrawal) of long-term excessive ethanol consumption has shown to provoke a variety of neuronal and mitochondrial damage to the cerebellum. Upon ethanol withdrawal, excitatory neurotransmitter molecules such as glutamate are overly released in brain areas including cerebellum. This is particularly relevant to the cerebellar neuronal network as glutamate signals are projected to Purkinje neurons through granular cells that are the most populated neuronal type in CNS. This excitatory neuronal signal may be elevated by ethanol withdrawal stress, which promotes an increase in intracellular Ca(2+) level and a decrease in a Ca(2+)-binding protein, both of which result in the excessive entry of Ca(2+) to the mitochondria. Subsequently, mitochondria undergo a prolonged opening of mitochondrial permeability transition pore and the overproduction of harmful free radicals, impeding adenosine triphosphate (ATP)-generating function. This in turn provokes the leakage of mitochondrial molecule cytochrome c to the cytosol, which triggers a cascade of adverse cytosol reactions. Upstream to this pathway, cerebellum under the condition of ethanol withdrawal has shown aberrant gene modifications through altered DNA methylation, histone acetylation, or microRNA expression. Interplay between these events and molecules may result in functional damage to cerebellar mitochondria and consequent neuronal degeneration, thereby contributing to motoric deficit. Mitochondria-targeting research may help develop a powerful new

  11. Hypertensive cerebellar hemorrhage and cerebellar hemorrhage caused by cryptic angioma

    International Nuclear Information System (INIS)

    A series of 44 patients with hypertensive cerebellar hemorrhage and nine patients with cerebellar hemorrhage caused by small angiomas is described. Hypertensive hemorrhage occurred most frequently in the patients in their seventies, whereas the onset of angioma-caused hemorrhage was often seen below the age of 40. Clinical syndromes of cerebellar hemorrhages can be categorized into three basic types: the vertigo syndrome, cerebellar dysfunction syndrome and brain stem compression syndrome. Patients with small (>= 2 cm in diameter in CT scans) and medium-sized (2 cm = 3 cm) hematomas deteriorated into unresponsive conditions and developed signs of brain stem compression. Surgical mortality was 32% in the hypertensive group, while it was 0% in the angioma group. Mortality as well as morbidity in both groups was strongly influenced by the preoperative status of consciousness. Our results suggest that substantial improvement could be obtained in the overall outcome of this disease by emergency craniectomy and removal of hematomas in all patients with large hematomas regardless of the levels of consciousness and regardless of the causes of bleeding. Furthermore, when clinical information and CT findings are suggestive of a ''cryptic'' angioma as the causative lesion, posterior fossa surgery may be indicated to extirpate the lesion, even if the hematoma is small. (author)

  12. Fibred Fibration Categories

    OpenAIRE

    Uemura, Taichi

    2016-01-01

    We show that, for a fibred category whose base category is a type-theoretic fibration category, fiberwise and total structures of type-theoretic fibration categories coincide. This gives the notion of fibred type-theoretic fibration categories which includes Shulman's inverse diagrams. Fibred type-theoretic fibration categories give categorical foundation of logical relation for identity types.

  13. Cultures of Cerebellar Granule Neurons

    OpenAIRE

    sprotocols

    2014-01-01

    Authors: Parizad M. Bilimoria and Azad Bonni1 Corresponding author ([]()) ### INTRODUCTION Primary cultures of granule neurons from the post-natal rat cerebellum provide an excellent model system for molecular and cell biological studies of neuronal development and function. The cerebellar cortex, with its highly organized structure and few neuronal subtypes, offers a well-characterized neural circuitry. Many fundamental insight...

  14. Cerebellar arteriovenous malformations in children

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, P.D. [Sheffield Univ. (United Kingdom). Acad. Dept. of Radiol.; Blaser, S.; Armstrong, D.; Chuang, S.; Harwood-Nash, D. [Division of Neuroradiology, The Hospital for Sick Children and University of Toronto, Toronto (Canada); Humphreys, R.P. [Division of Neurosurgery, The Hospital for Sick Children and University of Toronto, Toronto (Canada)

    1998-05-01

    We review the presentation, imaging findings and outcome in 18 children with cerebellar arteriovenous malformations (AVM). This group is of particular interest because of the reported poor outcome despite modern imaging and neurosurgical techniques. All children had CT and 15 underwent catheter angiography at presentation. Several of the children in the latter part of the study had MRI. Of the 18 children, 17 presented with a ruptured AVM producing intracranial haemorrhage. The remaining child presented with temporal lobe epilepsy and was shown to have temporal, vermian and cerebellar hemisphere AVM. This child had other stigmata of Osler-Weber-Rendu syndrome. Three other children had pre-existing abnormalities of possible relevance. One had a vascular malformation of the cheek and mandible, one a documented chromosomal abnormality and another a midline cleft upper lip and palate. Six of the 17 children with a ruptured cerebellar AVM died within 7 days of the ictus. Vascular pathology other than an AVM was found in 10 of the 14 children with a ruptured cerebellar AVM who had angiography: 4 intranidal aneurysms, 5 venous aneurysms and 2 cases of venous outflow obstruction (one child having both an aneurysm and obstruction). The severity of clinical presentation was directly related to the size of the acute haematoma, which was a reasonable predictor of outcome. (orig.) With 4 figs., 4 tabs., 23 refs.

  15. Cerebellar arteriovenous malformations in children

    International Nuclear Information System (INIS)

    We review the presentation, imaging findings and outcome in 18 children with cerebellar arteriovenous malformations (AVM). This group is of particular interest because of the reported poor outcome despite modern imaging and neurosurgical techniques. All children had CT and 15 underwent catheter angiography at presentation. Several of the children in the latter part of the study had MRI. Of the 18 children, 17 presented with a ruptured AVM producing intracranial haemorrhage. The remaining child presented with temporal lobe epilepsy and was shown to have temporal, vermian and cerebellar hemisphere AVM. This child had other stigmata of Osler-Weber-Rendu syndrome. Three other children had pre-existing abnormalities of possible relevance. One had a vascular malformation of the cheek and mandible, one a documented chromosomal abnormality and another a midline cleft upper lip and palate. Six of the 17 children with a ruptured cerebellar AVM died within 7 days of the ictus. Vascular pathology other than an AVM was found in 10 of the 14 children with a ruptured cerebellar AVM who had angiography: 4 intranidal aneurysms, 5 venous aneurysms and 2 cases of venous outflow obstruction (one child having both an aneurysm and obstruction). The severity of clinical presentation was directly related to the size of the acute haematoma, which was a reasonable predictor of outcome. (orig.)

  16. Language Impairment in Cerebellar Ataxia

    NARCIS (Netherlands)

    van Gaalen, Judith; de Swart, Bert J. M.; Oostveen, Judith; Knuijt, Simone; van de Warrenburg, Bart P. C.; Kremer, Berry (H. ) P. H.

    2014-01-01

    Background: Several studies have suggested that language impairment can be observed in patients with cerebellar pathology. The aim of this study was to investigate language performance in patients with spinocerebellar ataxia type 6 (SCA6). Methods: We assessed speech and language in 29 SCA6 patients

  17. Speech Prosody in Cerebellar Ataxia

    Science.gov (United States)

    Casper, Maureen A.; Raphael, Lawrence J.; Harris, Katherine S.; Geibel, Jennifer M.

    2007-01-01

    Persons with cerebellar ataxia exhibit changes in physical coordination and speech and voice production. Previously, these alterations of speech and voice production were described primarily via perceptual coordinates. In this study, the spatial-temporal properties of syllable production were examined in 12 speakers, six of whom were healthy…

  18. Fibre illumination system

    DEFF Research Database (Denmark)

    2012-01-01

    Source: EP2426402A The invention relates to a fibre illumination module and system for the collection and delivery of daylight for illumination purposes. The fibre illumination module comprises a plurality of collector elements, each collector element comprising an input fibre having a first end...... multi-directional arrangement. The fibre illumination system comprises a fibre illumination module of the above-mentioned type. By the invention, daylight may be exploited for the illumination of remote interior spaces of buildings in order to save energy, and improve the well-being of users in both...

  19. Ovarian steroids modulate leu-enkephalin levels and target leu-enkephalinergic profiles in the female hippocampal mossy fiber pathway

    OpenAIRE

    Torres-Reveron, Annelyn; Khalid, Sana; Tanya J. Williams; Waters, Elizabeth M.; Drake, Carrie T.; McEwen, Bruce S.; Milner, Teresa A.

    2008-01-01

    In the hippocampal formation (HF), the enkephalin opioids and estrogen are each known to modulate learning and cognitive performance relevant to drug abuse. Within the HF, leu-enkephalin (LENK) is most prominent in the mossy fiber (MF) pathway formed by the axons of dentate gyrus (DG) granule cells. To examine the influence of ovarian steroids on MF pathway LENK levels, we used quantitative light microscopic immunocytochemistry to evaluate LENK levels in normal cycling rats and in estrogen-tr...

  20. Cerebellar Information Processing in Relapsing-Remitting Multiple Sclerosis (RRMS

    Directory of Open Access Journals (Sweden)

    E. Lesage

    2010-01-01

    Full Text Available Recent research has characterized the anatomical connectivity of the cortico-cerebellar system – a large and important fibre system in the primate brain. Within this system, there are reciprocal projections between the prefrontal cortex and Crus II of the cerebellar cortex, which both play important roles in the acquisition and execution of cognitive skills. Here, we propose that this system also plays a particular role in sustaining skilled cognitive performance in patients with Relapsing-Remitting Multiple Sclerosis (RRMS, in whom advancing neuropathology causes increasingly inefficient information processing. We scanned RRMS patients and closely matched healthy subjects while they performed the Paced Auditory Serial Addition Test (PASAT, a demanding test of information processing speed, and a control task. This enabled us to localize differences between conditions that change as a function of group (group-by-condition interactions. Hemodynamic activity in some patient populations with CNS pathology are not well understood and may be atypical, so we avoided analysis strategies that rely exclusively on models of hemodynamic activity derived from the healthy brain, using instead an approach that combined a ‘model-free’ analysis technique (Tensor Independent Component Analysis, TICA that was relatively free of such assumptions, with a post-hoc ‘model-based’ approach (General Linear Model, GLM. Our results showed group-by-condition interactions in cerebellar cortical Crus II. We suggest that this area may have in role maintaining performance in working memory tasks by compensating for inefficient data transfer associated with white matter lesions in MS.

  1. Cerebellar ataxia and functional genomics : Identifying the routes to cerebellar neurodegeneration

    NARCIS (Netherlands)

    Smeets, C J L M; Verbeek, D S

    2014-01-01

    Cerebellar ataxias are progressive neurodegenerative disorders characterized by atrophy of the cerebellum leading to motor dysfunction, balance problems, and limb and gait ataxia. These include among others, the dominantly inherited spinocerebellar ataxias, recessive cerebellar ataxias such as Fried

  2. Cerebellar ataxia of early onset

    International Nuclear Information System (INIS)

    Eight cases of childhood cerebellar ataxia were reported. All these cases showed chronic cerebellar ataxia with early onset, and the other diseases of cerebellum such as infections, neoplasms and storage diseases were excluded by clinical symptoms and laboratory findings including blood counts, blood chemistry, lactate, pyruvate, ceruloplasmine, urinalysis, serum immunoglobulins, amino acid analysis in blood and urine, CSF analysis, leukocyte lysosomal enzymes, MCV, EMG, EEG and brain X-CT. Two pairs of siblings were included in this study. The clinical diagnosis were cerebellar type (5), spinocerebellar type (1), one Marinesco-Sjoegren syndrome and undetermined type (1). The age of onset was 1 to 5 years. The chief complaint was motor developmental delay in 6 cases; among them 5 patients could walk alone at the ages of 2 to 3 years'. Mental retardation was observed in 7 cases and epilepsy in 2. TRH was effective in 5 cases. The MRI study revealed that the area of medial sagittal slice of the cerebellum was reduced significantly in all cases and also that of pons was reduced in 5 cases. Different from typical adult onset spinocerebellar degenerations, most of the present cases have achieved slow developmental milestones and the clinical course was not progressive. Genetic factors are suspected in the pathogenesis of this disease in some cases. (author)

  3. Cerebellar hemangioblastoma: magnetic resonance findings

    International Nuclear Information System (INIS)

    To characterize the results of magnetic resonance imaging in cerebellar hemangioblastoma. This retrospective study deals with seven cases of histologically-confirmed cerebellar hemangioblastoma after surgery. Another patient, diagnosed as having Von Hippel-Lindau disease, also developed this lesions, but the finding was not histologically confirmed. In all, there were 2 women and 6 men. Three of these patients presented Von Hippel-Lindaus disease. All were studied on a 0.5 T imager with T1, T2 and PD-weighted spin-echo axial planes; T1-weighted sequences were repeated after intravenous gadolinium administration. According to their aspects, the lesions were divided into three groups as follows: cyst containing a mural nodule (n=3)solid tumor (n=3) and cavitated tumor (n=1). In one patient, the lesion was initially solid and was found to present cavitation two years later. Abnormal vascularization was observed in all the tumors except for two small solid tumors, and the findings were not clear in one of the cysts containing a mural nodule. In the differential diagnosis it may be difficult to rule out other tumors, such as cystic astrocytoma. However, magnetic resonance imaging, together with the clinical data, is of diagnostic value in the three morphological types of cerebellar hemangioblastoma. (Author) 15 refs

  4. Specific disruption of hippocampal mossy fiber synapses in a mouse model of familial Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Scott A Wilke

    Full Text Available The earliest stages of Alzheimer's disease (AD are characterized by deficits in memory and cognition indicating hippocampal pathology. While it is now recognized that synapse dysfunction precedes the hallmark pathological findings of AD, it is unclear if specific hippocampal synapses are particularly vulnerable. Since the mossy fiber (MF synapse between dentate gyrus (DG and CA3 regions underlies critical functions disrupted in AD, we utilized serial block-face electron microscopy (SBEM to analyze MF microcircuitry in a mouse model of familial Alzheimer's disease (FAD. FAD mutant MF terminal complexes were severely disrupted compared to control - they were smaller, contacted fewer postsynaptic spines and had greater numbers of presynaptic filopodial processes. Multi-headed CA3 dendritic spines in the FAD mutant condition were reduced in complexity and had significantly smaller sites of synaptic contact. Significantly, there was no change in the volume of classical dendritic spines at neighboring inputs to CA3 neurons suggesting input-specific defects in the early course of AD related pathology. These data indicate a specific vulnerability of the DG-CA3 network in AD pathogenesis and demonstrate the utility of SBEM to assess circuit specific alterations in mouse models of human disease.

  5. Studies on the development of mossy zinc electrodeposits from flowing alkaline electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Mc Vay, L.

    1991-07-01

    The initiation and characteristics of mossy zinc electrodeposits have been investigated. Batteries with zinc electrodes are candidates for electric vehicle applications; however, this electrode is prone to form non-compact deposits that contribute to capacity loss and battery failure. Moss is deposited when the current density is far from the limiting current. This morphology first appears only after the bulk deposit is approximately 1 {mu}m thick. In this investigation, the effects of flow rate (Re=0--4000), current density (0--50 mA/cm{sup 2}), concentration of the electroactive species (0.25 and 0.5 M), and the concentration of supporting electrolyte (3, 6, and 12 M) on the initiation of moss were examined. The rotating concentric cylinder electrode was employed for most of the experiments; and a flow channel was used to study the development of morphology. After the experiment, the deposit was characterized using microscopic, x-ray diffraction, and profilometric techniques. 94 refs., 72 figs.

  6. NeuroD2 regulates the development of hippocampal mossy fiber synapses

    Directory of Open Access Journals (Sweden)

    Wilke Scott A

    2012-02-01

    Full Text Available Abstract Background The assembly of neural circuits requires the concerted action of both genetically determined and activity-dependent mechanisms. Calcium-regulated transcription may link these processes, but the influence of specific transcription factors on the differentiation of synapse-specific properties is poorly understood. Here we characterize the influence of NeuroD2, a calcium-dependent transcription factor, in regulating the structural and functional maturation of the hippocampal mossy fiber (MF synapse. Results Using NeuroD2 null mice and in vivo lentivirus-mediated gene knockdown, we demonstrate a critical role for NeuroD2 in the formation of CA3 dendritic spines receiving MF inputs. We also use electrophysiological recordings from CA3 neurons while stimulating MF axons to show that NeuroD2 regulates the differentiation of functional properties at the MF synapse. Finally, we find that NeuroD2 regulates PSD95 expression in hippocampal neurons and that PSD95 loss of function in vivo reproduces CA3 neuron spine defects observed in NeuroD2 null mice. Conclusion These experiments identify NeuroD2 as a key transcription factor that regulates the structural and functional differentiation of MF synapses in vivo.

  7. HIPPI and Fibre Channel

    International Nuclear Information System (INIS)

    The High-Performance Parallel Interface (HIPPI) and Fibre Channel are near-gigabit per second data communications interfaces being developed in ANSI standards Task Group X3T9.3. HIPPI is the current interface of choice in the high-end and supercomputer arena, and Fibre Channel is a follow-on effort. HIPPI came from a local area network background, and Fibre Channel came from a mainframe to peripheral interface background

  8. Mice deficient in carbonic anhydrase type 8 exhibit motor dysfunctions and abnormal calcium dynamics in the somatic region of cerebellar granule cells.

    Science.gov (United States)

    Lamont, Matthew G; Weber, John T

    2015-06-01

    The waddles (wdl) mouse is characterized by a namesake "side-to-side" waddling gait due to a homozygous mutation of the Car8 gene. This mutation results in non-functional copies of the protein carbonic anhydrase type 8. Rota-rod testing was conducted to characterize the wdl mutations' effect on motor output. Results indicated that younger homozygotes outperformed their older cohorts, an effect not seen in previous studies. Heterozygotes, which were thought to be free of motor impairment, displayed motor learning deficiencies when compared with wild type performance. Acute cerebellar slices were then utilized for fluorescent calcium imaging experiments, which revealed significant alterations in cerebellar granule cell somatic calcium signaling when exposed to glutamate. The contribution of GABAergic signaling to these alterations was also verified using bath application of bicuculline. Changes in somatic calcium signals were found to be applicable to an in vivo scenario by comparing group responses to electrical stimulation of afferent mossy fiber projections. Finally, intracellular calcium store function was also found to be altered by the wdl mutation when slices were treated with thapsigargin. These findings, taken together with previous work on the wdl mouse, indicate a widespread disruption in cerebellar circuitry hampering proper neuronal communication. PMID:25721739

  9. Crossed cerebral - cerebellar diaschisis : MRI evaluation.

    Directory of Open Access Journals (Sweden)

    Chakravarty A

    2002-07-01

    Full Text Available MRI, done later in life, in two patients with infantile hemiplegia syndrome showed significant volume loss in the cerebellar hemisphere contralateral to the side of the affected cerebrum. The cerebellar volume loss seemed to correlate with the degree of volume loss in the contralateral cerebral hemisphere. These observations provide morphological evidence of the phenomenon of crossed cerebral-cerebellar diaschisis (CCD. Functional neuroimaging studies in support of the concept of CCD has been critically reviewed.

  10. Climbing Fiber Signaling and Cerebellar Gain Control

    OpenAIRE

    Ohtsuki, Gen; Piochon, Claire; Hansel, Christian

    2009-01-01

    The physiology of climbing fiber signals in cerebellar Purkinje cells has been studied since the early days of electrophysiology. Both the climbing fiber-evoked complex spike and the role of climbing fiber activity in the induction of long-term depression (LTD) at parallel fiber-Purkinje cell synapses have become hallmark features of cerebellar physiology. However, the key role of climbing fiber signaling in cerebellar motor learning has been challenged by recent reports of forms of synaptic ...

  11. Cerebellar medulloblastoma presenting with skeletal metastasis

    OpenAIRE

    Barai Sukanta; Bandopadhayaya G; Julka P; Dhanapathi H; Haloi A; Seith A

    2004-01-01

    Medulloblastomas are highly malignant brain tumours, but only rarely produce skeletal metastases. No case of medulloblastoma has been documented to have produced skeletal metastases prior to craniotomy or shunt surgery. A 21-year-old male presented with pain in the hip and lower back with difficulty in walking of 3 months′ duration. Signs of cerebellar dysfunction were present hence a diagnosis of cerebellar neoplasm or skeletal tuberculosis with cerebellar abscess formation was consid...

  12. Crossed cerebellar hyperperfusion in brain perfusion SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Jinnouchi, Seishi; Nagamachi, Shigeki; Nishii, Ryuuichi; Futami, Shigemi; Tamura, Shozo [Miyazaki Medical Coll., Kiyotake (Japan); Kawai, Keiichi

    2000-10-01

    Crossed cerebellar diaschisis is a well-known brain SPECT finding in stroke patients. Few reports, however, have described supratentorial and contralateral cerebellar hyperperfusion (crossed cerebellar hyperperfusion, CCH). We assessed the incidence of CCH in 33 patients with cerebral hyperperfusion. Brain SPECT showed CCH in five patients out of 20 epilepsy and three of 13 patients with acute encephalitis. These eight patients with CCH had recent epileptic attack. CCH was found in ECD SPECT as well as HM-PAO. The contralateral cerebellar activity correlated with the cerebral activity in patients with CCH. CCH would have a relation with supratentrial hyperfunction in epilepsy and acute encephalitis. (author)

  13. Roles for nitric oxide and arachidonic acid in the induction of heterosynaptic cerebellar LTD.

    Science.gov (United States)

    Reynolds, T; Hartell, N A

    2001-01-22

    In cerebellar slices conjunctive pairing of parallel fibre (PF) stimulation with depolarization of Purkinje cells (PCs) induces a long-term depression (LTD) of PF synaptic transmission that spreads to unpaired PF inputs to the same cell. Inhibitors of NO synthase (7-nitro-indazole), soluble guanylate cyclase (ODQ) and PKG (KT5823) all prevented depression at each of two independent PF pathways to a single PC. Inhibition of NOS also unmasked a platelet activating factor (PAF)-mediated synaptic potentiation of possible presynaptic origin. LTD was also prevented by the phospholipase A2 inhibitor OBAA but was rescued by co-perfusion with arachidonic acid. We conclude that NO and diffusible products of phospholipase A2 metabolism are potential mediators of the spread of cerebellar plasticity at the single cell level. PMID:11201073

  14. Dietary Fibre and Prebiotics

    OpenAIRE

    Bellei G; Haslberger A

    2012-01-01

    Dietary fibre intake is associated with a myriad of health benefits. Among others, their fermentation by the microbiota results in the formation of short chain fatty acids, which protect against pathogenic bacteria. Together with dietary fibres, prebiotics are colonic nutrients but prebiotics are degraded and utilized only by beneficial bacteria, namely bifidobacteria and/or lactobacilli. (S. Macfarlane, 2010)

  15. Fibre reinforced polymer nanocomposites

    NARCIS (Netherlands)

    Vlasveld, D.P.N.

    2005-01-01

    In this thesis the results are described of the research on a combination of two types of composites: thermoplastic nanocomposites and continuous fibre composites. In this three-phase composite the main reinforcing phase are continuous glass or carbon fibres, and the matrix consists of a polyamide 6

  16. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    bandgap structures and thoughts of inspiration from microstructures in nature, as well as classification of the various photonic crystal fibres, theoretical tools for analysing the fibres and methods of their production. Finally, the book points toward some of the many future applications, where photonic...

  17. Fibre Flocculation in Papermaking

    Science.gov (United States)

    Kerekes, R. J.

    1998-11-01

    Pulp fibres flocculate into aggregates which paper a characteristic non-uniformity on a scale of several millimetres. This non-uniformity, visible in transmitted light, diminishes the physical and optical properties of paper. Consequently, minimization of fibre flocculation has been an objective of papermaking ever since the process was invented. It was established over 50 years ago that mechanical rather than colloidal forces governed fibre flocculation in the shear flows used in papermaking. However, the process by which individual flocs form and the conditions required for their creation have only recently been investigated in detail. This paper will review recent research on this topic at the University of British Columbia. The paper will focus on the formation and properties of coherent flocs, the importance of the Crowding Number in defining the level of interfibre contact necessary for floc creation, the role of hydrodynamic and inter-fibre forces in producing flocs, and the structure and strength of fibre flocs.

  18. Acute cerebellar ataxia and infectious mononucleosis.

    OpenAIRE

    Wadhwa, N. K.; Ghose, R R

    1983-01-01

    A 28-year-old man, who presented with acute cerebellar ataxia, was found to have haematological features of infectious mononucleosis. There was serological evidence of recent infection with Epstein-Barr virus. It is speculated that cerebellar dysfunction results from virus-induced inflammatory changes within the central nervous system.

  19. Synaptic responses evoked by tactile stimuli in Purkinje cells in mouse cerebellar cortex Crus II in vivo.

    Directory of Open Access Journals (Sweden)

    Chun-Ping Chu

    Full Text Available BACKGROUND: Sensory stimuli evoke responses in cerebellar Purkinje cells (PCs via the mossy fiber-granule cell pathway. However, the properties of synaptic responses evoked by tactile stimulation in cerebellar PCs are unknown. The present study investigated the synaptic responses of PCs in response to an air-puff stimulation on the ipsilateral whisker pad in urethane-anesthetized mice. METHODS AND MAIN RESULTS: Thirty-three PCs were recorded from 48 urethane-anesthetized adult (6-8-week-old HA/ICR mice by somatic or dendritic patch-clamp recording and pharmacological methods. Tactile stimulation to the ipsilateral whisker pad was delivered by an air-puff through a 12-gauge stainless steel tube connected with a pressurized injection system. Under current-clamp conditions (I = 0, the air-puff stimulation evoked strong inhibitory postsynaptic potentials (IPSPs in the somata of PCs. Application of SR95531, a specific GABA(A receptor antagonist, blocked IPSPs and revealed stimulation-evoked simple spike firing. Under voltage-clamp conditions, tactile stimulation evoked a sequence of transient inward currents followed by strong outward currents in the somata and dendrites in PCs. Application of SR95531 blocked outward currents and revealed excitatory postsynaptic currents (EPSCs in somata and a temporal summation of parallel fiber EPSCs in PC dendrites. We also demonstrated that PCs respond to both the onset and offset of the air-puff stimulation. CONCLUSIONS: These findings indicated that tactile stimulation induced asynchronous parallel fiber excitatory inputs onto the dendrites of PCs, and failed to evoke strong EPSCs and spike firing in PCs, but induced the rapid activation of strong GABA(A receptor-mediated inhibitory postsynaptic currents in the somata and dendrites of PCs in the cerebellar cortex Crus II in urethane-anesthetized mice.

  20. Facial stimulation induces long-term depression at cerebellar molecular layer interneuron–Purkinje cell synapses in vivo in mice

    Directory of Open Access Journals (Sweden)

    De-Lai eQiu

    2015-06-01

    Full Text Available Cerebellar long-term synaptic plasticity has been proposed to provide a cellular mechanism for motor learning. Numerous studies have demonstrated the induction and mechanisms of synaptic plasticity at parallel fiber–Purkinje cell (PF–PC, parallel fiber–molecular layer interneurons (PF–MLI and mossy fiber–granule cell (MF–GC synapses, but no study has investigated sensory stimulation-evoked synaptic plasticity at MLI–PC synapses in the cerebellar cortex of living animals. We studied the expression and mechanism of MLI–PC GABAergic synaptic plasticity induced by a train of facial stimulation in urethane-anesthetized mice by cell-attached recordings and pharmacological methods. We found that 1 Hz, but not a 2 Hz or 4 Hz, facial stimulation induced a long-term depression (LTD of GABAergic transmission at MLI–PC synapses, which was accompanied with a decrease in the stimulation-evoked pause of spike firing in PCs, but did not induce a significant change in the properties of the sensory-evoked spike events of MLIs. The MLI–PC GABAergic LTD could be prevented by blocking cannabinoid type 1 (CB1 receptors, and could be pharmacologically induced by a CB1 receptor agonist. Additionally, 1 Hz facial stimulation delivered in the presence of a metabotropic glutamate receptor 1 (mGluR1 antagonist, JNJ16259685, still induced the MLI–PC GABAergic LTD, whereas blocking N-methyl-D-aspartate (NMDA receptors during 1 Hz facial stimulation abolished the expression of MLI–PC GABAergic LTD. These results indicate that sensory stimulation can induce an endocannabinoid (eCB-dependent LTD of GABAergic transmission at MLI–PC synapses via activation of NMDA receptors in cerebellar cortical Crus II in vivo in mice. Our results suggest that the sensory stimulation-evoked MLI–PC GABAergic synaptic plasticity may play a critical role in motor learning in animals.

  1. Metronidazole-Induced Cerebellar Toxicity

    Science.gov (United States)

    Agarwal, Amit; Kanekar, Sangam; Sabat, Shyam; Thamburaj, Krishnamurthy

    2016-01-01

    Metronidazole is a very common antibacterial and antiprotozoal with wide usage across the globe, including the least developed countries. It is generally well-tolerated with a low incidence of serious side-effects. Neurological toxicity is fairly common with this drug, however majority of these are peripheral neuropathy with very few cases of central nervous toxicity reported. We report the imaging findings in two patients with cerebellar dysfunction after Metronidazole usage. Signal changes in the dentate and red nucleus were seen on magnetic resonance imaging in these patients. Most of the cases reported in literature reported similar findings, suggesting high predilection for the dentate nucleus in metronidazole induced encephalopathy.

  2. Metronidazole-induced cerebellar toxicity

    Directory of Open Access Journals (Sweden)

    Amit Agarwal

    2016-04-01

    Full Text Available Metronidazole is a very common antibacterial and antiprotozoal with wide usage across the globe, including the least developed countries. It is generally well-tolerated with a low incidence of serious side-effects. Neurological toxicity is fairly common with this drug, however majority of these are peripheral neuropathy with very few cases of central nervous toxicity reported. We report the imaging findings in two patients with cerebellar dysfunction after Metronidazole usage. Signal changes in the dentate and red nucleus were seen on magnetic resonance imaging in these patients. Most of the cases reported in literature reported similar findings, suggesting high predilection for the dentate nucleus in metronidazole induced encephalopathy.

  3. Cerebellar stroke-manifesting as mania

    Directory of Open Access Journals (Sweden)

    Venkatesan Jagadesan

    2014-01-01

    Full Text Available Secondary mania resulting from cerebral Cortex are described commonly. But secondary mania produced by cerebellar lesions are relatively uncommon. This case report describes a patient who developed cerebellar stoke and manic features simultaneously. 28 years old male developed giddiness and projectile vomiting. Then he would lie down for about an hour only to find that he could not walk. He became quarrelsome. His Psycho motor activities and speech were increased. He was euphoric and was expressing grandiose ideas. Bender Gestalt Test showed signs of organicity. Score in Young mania relating scale was 32; productivity was low in Rorschach. Neurological examination revealed left cerebellar signs like ataxia and slurring of speech. Computed tomography of brain showed left cerebellar infarct. Relationship between Psychiatric manifestations and cerebellar lesion are discussed.

  4. Cellular and molecular basis of cerebellar development

    Science.gov (United States)

    Martinez, Salvador; Andreu, Abraham; Mecklenburg, Nora; Echevarria, Diego

    2013-01-01

    Historically, the molecular and cellular mechanisms of cerebellar development were investigated through structural descriptions and studying spontaneous mutations in animal models and humans. Advances in experimental embryology, genetic engineering, and neuroimaging techniques render today the possibility to approach the analysis of molecular mechanisms underlying histogenesis and morphogenesis of the cerebellum by experimental designs. Several genes and molecules were identified to be involved in the cerebellar plate regionalization, specification, and differentiation of cerebellar neurons, as well as the establishment of cellular migratory routes and the subsequent neuronal connectivity. Indeed, pattern formation of the cerebellum requires the adequate orchestration of both key morphogenetic signals, arising from distinct brain regions, and local expression of specific transcription factors. Thus, the present review wants to revisit and discuss these morphogenetic and molecular mechanisms taking place during cerebellar development in order to understand causal processes regulating cerebellar cytoarchitecture, its highly topographically ordered circuitry and its role in brain function. PMID:23805080

  5. Asymptomatic cerebellar atrophy after acute enteroviral encephalitis.

    Science.gov (United States)

    Vitaszil, Edina; Kamondi, Anita; Csillik, Anita; Velkey, Imre; Szirmai, Imre

    2005-07-01

    We report on a 13-year-old male who had acute enteroviral encephalitis causing cerebellar symptoms at the age of 10 years. Magnetic resonance imaging (MRI) showed no abnormalities. Clinically he appeared to be recovered completely after 6 months. Twenty-three months after the recovery, MRI was performed because he presented with slight lower-limb and truncal ataxia experienced as lack of foot coordination while playing football or riding a bicycle. MRI demonstrated severe cerebellar atrophy. Clinically he recovered completely in 10 days. Only sophisticated electrophysiological methods revealed cerebellar dysfunction. The case provides evidence for the plasticity of cerebellar regulatory structures involved in the coordination of fine movements. It seems that in childhood the slow, isolated disintegration of cerebellar systems can be compensated for by upper thalamic or telencephalic connections, in a similar way to a congenital deficit of the cerebellum. PMID:15991870

  6. Cellular and Molecular Basis of Cerebellar Development

    Directory of Open Access Journals (Sweden)

    Salvador eMartinez

    2013-06-01

    Full Text Available Historically, the molecular and cellular mechanisms of cerebellar development were investigated through structural descriptions and studying spontaneous mutations in animal models and humans. Advances in experimental embryology, genetic engineering and neuroimaging techniques render today the possibility to approach the analysis of molecular mechanisms underlying histogenesis and morphogenesis of the cerebellum by experimental designs. Several genes and molecules were identified to be involved in the cerebellar plate regionalization, specification and differentiation of cerebellar neurons, as well as the establishment of cellular migratory routes and the subsequent neuronal connectivity. Indeed, pattern formation of the cerebellum requires the adequate orchestration of both key morphogenetic signals, arising from distinct brain regions, and local expression of specific transcription factors. Thus, the present review wants to revisit and discuss these morphogenetic and molecular mechanisms taking place during cerebellar development in order to understand causal processes regulating cerebellar cytoarchitecture, its highly topographically ordered circuitry and its role in brain function.

  7. Gating of long-term potentiation by nicotinic acetylcholine receptors at the cerebellum input stage.

    Directory of Open Access Journals (Sweden)

    Francesca Prestori

    Full Text Available The brain needs mechanisms able to correlate plastic changes with local circuit activity and internal functional states. At the cerebellum input stage, uncontrolled induction of long-term potentiation or depression (LTP or LTD between mossy fibres and granule cells can saturate synaptic capacity and impair cerebellar functioning, which suggests that neuromodulators are required to gate plasticity processes. Cholinergic systems innervating the cerebellum are thought to enhance procedural learning and memory. Here we show that a specific subtype of acetylcholine receptors, the α7-nAChRs, are distributed both in cerebellar mossy fibre terminals and granule cell dendrites and contribute substantially to synaptic regulation. Selective α7-nAChR activation enhances the postsynaptic calcium increase, allowing weak mossy fibre bursts, which would otherwise cause LTD, to generate robust LTP. The local microperfusion of α7-nAChR agonists could also lead to in vivo switching of LTD to LTP following sensory stimulation of the whisker pad. In the cerebellar flocculus, α7-nAChR pharmacological activation impaired vestibulo-ocular-reflex adaptation, probably because LTP was saturated, preventing the fine adjustment of synaptic weights. These results show that gating mechanisms mediated by specific subtypes of nicotinic receptors are required to control the LTD/LTP balance at the mossy fibre-granule cell relay in order to regulate cerebellar plasticity and behavioural adaptation.

  8. mGluR2 acts through inhibitory Gα subunits to regulate transmission and long-term plasticity at hippocampal mossy fiber-CA3 synapses

    OpenAIRE

    Nicholls, Russell E.; ZHANG, XIAO-LEI; Bailey, Christopher P.; Conklin, Bruce R; Kandel, Eric R.; Stanton, Patric K.

    2006-01-01

    Presynaptic inhibitory G protein-coupled receptors play a critical role in regulating transmission at a number of synapses in the central and peripheral nervous system. We generated transgenic mice that express a constitutively active form of an inhibitory Gα subunit to examine the molecular mechanisms underlying the actions of one such receptor, metabotropic glutamate receptor (mGluR) 2, at mossy fiber-CA3 synapses in the hippocampus. mGluR2 participates in at least three types of mossy fibe...

  9. The effect of elementary fibre variability on bamboo fibre strength

    International Nuclear Information System (INIS)

    Highlights: • Fibre diameter was found to have a significant effect on bamboo fibre strength. • The average fibre strength decreases with increasing quantity of elementary fibres. • A new model can be used for predicting fibre strength at different fibre diameters. - Abstract: Tensile strength of brittle fibres exhibits statistical distribution and size dependence. In this work, the average strength of bamboo fibre is found to decrease from 568 to 483 MPa as mean diameter increases from 196.6 to 584.3 μm. The morphologies of bamboo fibres with increasing diameters were investigated through Scanning Electron Microscopy (SEM) to demonstrate variations in the quantity of elementary fibres. The influence of elementary fibre distributions on the fibre strength was also studied. A modified Weibull model based on number of elementary fibres is proposed to perform scaling predictions for the fracture strength of the fibres at different between-fibre diameters. It was shown that the predicted results are in reasonable agreement with experimental data, highlighting the adequacies of the new analytical model for describing the diameter dependence of tensile strength

  10. POLARISATION PRESERVING OPTICAL FIBRE

    DEFF Research Database (Denmark)

    2000-01-01

    A micro-structured optical fibre having a cladding comprising a number of elements having a non-circular cross-section. Each element has at least one part extending outside a circle having the same cross-sectional area as the element. These extending parts are directed in the same direction. This...... cladding structure provides polarisation preserving properties to the optical fibre. Optical fibres using this technology may have claddings with elements placed non-periodically as well as in a two-dimensional periodic lattice - such as cladding providing Photonic Band Gap (PBG) effects....

  11. Cerebellar contributions to verbal working memory.

    Science.gov (United States)

    Tomlinson, Simon P; Davis, Nick J; Morgan, Helen M; Bracewell, R Martyn

    2014-06-01

    There is increasing evidence for a cerebellar role in working memory. Clinical research has shown that working memory impairments after cerebellar damage and neuroimaging studies have revealed task-specific activation in the cerebellum during working memory processing. A lateralisation of cerebellar function within working memory has been proposed with the right hemisphere making the greater contribution to verbal processing and the left hemisphere for visuospatial tasks. We used continuous theta burst stimulation (cTBS) to examine whether differences in post-stimulation performance could be observed based on the cerebellar hemisphere stimulated and the type of data presented. We observed that participants were significantly less accurate on a verbal version of a Sternberg task after stimulation to the right cerebellar hemisphere when compared to left hemisphere stimulation. Performance on a visual Sternberg task was unaffected by stimulation of either hemisphere. We discuss our results in the context of prior studies that have used cerebellar stimulation to investigate working memory and highlight the cerebellar role in phonological encoding. PMID:24338673

  12. Optical fibre microwire sensors

    OpenAIRE

    Brambilla, G; Belal, M.; Jung, Y.; Song, Z.; F. Xu; Newson, T.P.; Richardson, D. J.

    2011-01-01

    This paper reviews sensing applications of optical fibre microwires and nanowires. In addition to the usual benefits of sensors based on optical fibres, these sensors are extremely compact and have fast response speeds. In this review sensors will be grouped in three categories according to their morphology: linear sensors, resonant sensors and tip sensors. While linear and resonant sensors mainly exploit the fraction of power propagating outside the microwire physical boundary, tip sensors t...

  13. Fibre-reinforced thermoplastics

    OpenAIRE

    Røsand, Vegar Rydén

    2011-01-01

    This thesis presents experimental tests of fibre-reinforced polypropylene, as well as calibration of material coefficients and simulations of experimental tests. The focus is on exploring the dependence on loading direction to fibre direction and rate of strain, and on validation of the material coefficient.First the material and the experimental procedure is presented together with the results from the tests.Uniaxial tension tests, cyclic loading-unloading tests and components tests is perfo...

  14. Fibre reinforced polymer nanocomposites

    OpenAIRE

    Vlasveld, D.P.N.

    2005-01-01

    In this thesis the results are described of the research on a combination of two types of composites: thermoplastic nanocomposites and continuous fibre composites. In this three-phase composite the main reinforcing phase are continuous glass or carbon fibres, and the matrix consists of a polyamide 6 / layered silicate nanocomposite. To be able to produce and understand this new type of thermoplastic composite, the properties of the nanocomposite matrix materials have been investigated, follow...

  15. Sonic hedgehog patterning during cerebellar development.

    Science.gov (United States)

    De Luca, Annarita; Cerrato, Valentina; Fucà, Elisa; Parmigiani, Elena; Buffo, Annalisa; Leto, Ketty

    2016-01-01

    The morphogenic factor sonic hedgehog (Shh) actively orchestrates many aspects of cerebellar development and maturation. During embryogenesis, Shh signaling is active in the ventricular germinal zone (VZ) and represents an essential signal for proliferation of VZ-derived progenitors. Later, Shh secreted by Purkinje cells sustains the amplification of postnatal neurogenic niches: the external granular layer and the prospective white matter, where excitatory granule cells and inhibitory interneurons are produced, respectively. Moreover, Shh signaling affects Bergmann glial differentiation and promotes cerebellar foliation during development. Here we review the most relevant functions of Shh during cerebellar ontogenesis, underlying its role in physiological and pathological conditions. PMID:26499980

  16. Pediatric Neurocutaneous Syndromes with Cerebellar Involvement.

    Science.gov (United States)

    Bosemani, Thangamadhan; Huisman, Thierry A G M; Poretti, Andrea

    2016-08-01

    Neurocutaneous syndromes encompasses a broad group of genetic disorders with different clinical, genetic, and pathologic features that share developmental lesions of the skin as well as central and peripheral nervous system. Cerebellar involvement has been shown in numerous types of neurocutaneous syndrome. It may help or be needed for the diagnosis and to explain the cognitive and behavioral phenotype of affected children. This article describes various types of neurocutaneous syndrome with cerebellar involvement. For each neurocutaneous disease or syndrome, clinical features, genetic, neuroimaging findings, and the potential role of the cerebellar involvement is discussed. PMID:27423801

  17. CT findings in cerebellar hemangioblastomas

    Energy Technology Data Exchange (ETDEWEB)

    Heiss, E.; Albert, F.

    1982-02-01

    The computed tomographic (CT) findings in 16 personal cases of cerebellar hemangioblastomas are presented. Accordings to other reports in the literature, three-quarters of the tumours were cystic, containing a small mural nodule, whereas the others were predominantly solid. By CT scan the cystic tumours were always identified as roundish or oval space-occupying lesions, sharply demarcated from the surrounding tissue. The solid portion of these tumours, projecting into the cystic part, was delineated more precisely by contrast enhancement, but sometimes escaped identification. On the contrary, even after contrast enhancement the predominantly solid tumours could not be clearly identified as hemangioblastomas. Calcification could not be demonstrated. Additional angiographic investigations were imperative in order to establish the diagnosis, besides visualizing further hypervascular nodules of hemangioblastoma, which CT scanning failed to reveal.

  18. Cerebellar mutism syndrome and its relation to cerebellar cognitive and affective function: Review of the literature

    Directory of Open Access Journals (Sweden)

    Yildiz Ozlem

    2010-01-01

    Full Text Available Tumors of the cerebellum and brainstem account for half of all brain tumors in children. The realization that cerebellar lesions produce clinically relevant intellectual disability makes it important to determine whether neuropsychological abnormalities occur in long-term survivors of pediatric cerebellar tumors. Little is known about the neurobehavioral sequale resulting specifically from the resection of these tumors in this population. We therefore reviewed neuropsychological findings associated with postoperative cerebellar mutism syndrome and discuss the further implications for cerebellar cognitive function.

  19. Cerebellar Involvement in Ataxia and Generalized Epilepsy

    NARCIS (Netherlands)

    L. Kros (Lieke)

    2015-01-01

    markdownabstract__Abstract__ The work described in this thesis was performed in order to elucidate the role of different cerebellar modules in ataxia and generalized epilepsy using various techniques including in vivo electrophysiology, optogenetics, pharmacological interventions, immunohistology a

  20. Cerebellar mutism: review of the literature

    DEFF Research Database (Denmark)

    Gudrunardottir, Thora; Sehested, Astrid; Juhler, Marianne;

    2011-01-01

    Cerebellar mutism is a common complication of posterior fossa surgery in children. This article reviews current status with respect to incidence, anatomical substrate, pathophysiology, risk factors, surgical considerations, treatment options, prognosis and prevention....

  1. Synchrony and neural coding in cerebellar circuits

    Directory of Open Access Journals (Sweden)

    Abigail L Person

    2012-12-01

    Full Text Available The cerebellum regulates complex movements and is also implicated in cognitive tasks, and cerebellar dysfunction is consequently associated not only with movement disorders, but also with conditions like autism and dyslexia. How information is encoded by specific cerebellar firing patterns remains debated, however. A central question is how the cerebellar cortex transmits its integrated output to the cerebellar nuclei via GABAergic synapses from Purkinje neurons. Possible answers come from accumulating evidence that subsets of Purkinje cells synchronize their firing during behaviors that require the cerebellum. Consistent with models predicting that coherent activity of inhibitory networks has the capacity to dictate firing patterns of target neurons, recent experimental work supports the idea that inhibitory synchrony may regulate the response of cerebellar nuclear cells to Purkinje inputs, owing to the interplay between unusually fast inhibitory synaptic responses and high rates of intrinsic activity. Data from multiple laboratories lead to a working hypothesis that synchronous inhibitory input from Purkinje cells can set the timing and rate of action potentials produced by cerebellar nuclear cells, thereby relaying information out of the cerebellum. If so, then changing spatiotemporal patterns of Purkinje activity would allow different subsets of inhibitory neurons to control cerebellar output at different times. Here we explore the evidence for and against the idea that a synchrony code defines, at least in part, the input-output function between the cerebellar cortex and nuclei. We consider the literature on the existence of simple spike synchrony, convergence of Purkinje neurons onto nuclear neurons, and intrinsic properties of nuclear neurons that contribute to responses to inhibition. Finally, we discuss factors that may disrupt or modulate a synchrony code and describe the potential contributions of inhibitory synchrony to other motor

  2. Tutorial: Applications of Fibre Gratings

    Institute of Scientific and Technical Information of China (English)

    Hwayaw; Tam; Bai; ou; Guan; Shunyee; Liu

    2003-01-01

    Fibre grating is an important enabling technology that has found numerous applications in both telecommunications and sensor systems. This tutorial describes the basic characteristics of fibre gratings and gives examples of where they are being employed.

  3. Particle tracking with scintillating fibres

    CERN Document Server

    D'Ambrosio, C; Leutz, H; Puertolas, D

    1996-01-01

    This article presents our R&D-work on particle tracking with scintillating fibres. We have developed new fibre dyes, more efficient fibre cladding, coherent fibre bundles with improved packing fraction and a new fibre readout technique (ISPA-tube). Altogether, these new developments increased the hit density of fine grain (60 µm) fibres by about 7 times. This results in mini-tracks per 2.5 mm fibre layer rather than in single hits only and enhances the track reconstruction efficiency to nearly 100 %. Compared with competing tracking methods (silicon strips, MSGCs), our scintillating fibres are superior in hit numbers per radiation length and in the 2-track resolution. They require much less readout channels and consequently no cooling provisions to remove their electronic heat.

  4. Bilateral Cerebellar Cortical Dysplasia without Other Malformations: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jung Seok; Ahn Kook Jin; Kim, Jee Young; Lee, Sun Jin; Park, Jeong Mi [Catholic University Yeouido St. Mary' s Hospital, College of Medicine, Seoul (Korea, Republic of)

    2010-06-15

    Recent advances in MRI have revealed congenital brain malformations and subtle developmental abnormalities of the cerebral and cerebellar cortical architecture. Typical cerebellar cortical dysplasia as a newly categorized cerebellar malformation, has been seen in patients with Fukuyama congenital muscular dystrophy. Cerebellar cortical dysplasia occurs at the embryonic stage and is often observed in healthy newborns. It is also incidentally and initially detected in adults without symptoms. To the best of our knowledge, cerebellar dysplasia without any related disorders is very rare. We describe the MRI findings in one patient with disorganized foliation of both cerebellar hemispheres without a related disorder or syndrome

  5. Multibeam Fibre Laser Cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove

    The appearance of the high power high brilliance fibre laser has opened for new possibilities in laser materials processing. In laser cutting this laser has demonstrated high cutting performance compared to the dominating cutting laser, the CO2-laser. However, quality problems in fibre-laser...... cutting have until now limited its application in metal cutting. In this paper the first results of proof-of-principle studies applying a new approach (patent pending) for laser cutting with high brightness short wavelength lasers will be presented. In the approach, multi beam patterns are applied...... to control the melt flow out of the cut kerf resulting in improved cut quality in metal cutting. The beam patterns in this study are created by splitting up beams from 2 single mode fibre lasers and combining these beams into a pattern in the cut kerf. The results are obtained with a total of 550 W of single...

  6. Mineral fibres and health

    International Nuclear Information System (INIS)

    The use of inorganic fibrous materials is a comparatively new phenomenon and was uncommon before the Industrial Revolution. Humans evolved in a comparatively fibre-free environment and consequently never fully developed the defence mechanisms needed to deal with the consequences of inhaling fibres. However, the urban environment now has an airborne fibre concentration of around 1 f.l-1, which is a tenfold increase on the natural background. Any sample of ambient air collected indoors or outdoors will probably contain some mineral fibres, but there is little evidence that these pose any risk to human health. They come from asbestos used in brakes, glass and mineral wools used as insulation and fire proofing of buildings, gypsum from plaster and a variety of types from many sources. Few of these have the potential to do any harm. Asbestos is the only fibre of note but urban levels are insignificant compared to occupational exposures. When the health of cohorts occupationally exposed to the several types of asbestos is studied the problem can be put into perspective. Studies of workers in the chrysotile industry exposed to much higher dust levels than in a factory today show no excess lung cancer or mesothelioma. By comparison those living near crocidolite mines, let alone working in them, may develop asbestos-related disease. As always, dose is the critical factor. Chrysotile is cleared from the lungs very efficiently, only the amphiboles are well retained. The only real health problem comes from the earlier use of asbestos products that may now be old, friable and damaged and made from amphibole or mixed fibre. If though, these are still in good condition, they do not pose a health problem. Asbestos-related diseases are very rare in those not occupationally exposed. Where they exist exposure has nearly always been to crocidolite. (author)

  7. Fibre Optics in Undersea Applications

    Directory of Open Access Journals (Sweden)

    A. K. Talwar

    1984-01-01

    Full Text Available Role of optical fibres for underwater communication cables and hydrophones is discussed. The fibre optics cables provide an excellent solution to the historical bandwidth-diameter problems of conventional coaxial cables.Fibre optic hydrophones are found to have many more advantages apart from high sensitivity and large dynamic range, over the classical sound sensors used in underwater work.

  8. Fibre Optics in Undersea Applications

    OpenAIRE

    A. K. Talwar; Srivastava, D. K.

    1984-01-01

    Role of optical fibres for underwater communication cables and hydrophones is discussed. The fibre optics cables provide an excellent solution to the historical bandwidth-diameter problems of conventional coaxial cables.Fibre optic hydrophones are found to have many more advantages apart from high sensitivity and large dynamic range, over the classical sound sensors used in underwater work.

  9. Metabolic anatomy of paraneoplastic cerebellar degeneration

    International Nuclear Information System (INIS)

    Eleven patients with acquired cerebellar degeneration (10 of whom had paraneoplastic cerebellar degeneration [PCD]) were evaluated using neuropsychological tests and 18F-fluorodeoxyglucose/positron emission tomography to (1) quantify motor, cognitive, and metabolic abnormalities; (2) determine if characteristic alterations in the regional cerebral metabolic rate for glucose (rCMRGlc) are associated with PCD; and (3) correlate behavioral and metabolic measures of disease severity. Eighteen volunteer subjects served as normal controls. Although some PCD neuropsychological test scores were abnormal, these results could not, in general, be dissociated from the effects of dysarthria and ataxia. rCMRGlc was reduced in patients with PCD (versus normal control subjects) in all regions except the brainstem. Analysis of patient and control rCMRGlc data using a mathematical model of regional metabolic interactions revealed two metabolic pattern descriptors, SSF1 and SSF2, which distinguished patients with PCD from normal control subjects; SSF2, which described a metabolic coupling between cerebellum, cuneus, and posterior temporal, lateral frontal, and paracentral cortex, correlated with quantitative indices of cerebellar dysfunction. Our inability to document substantial intellectual impairment in 7 of 10 patients with PCD contrasts with the 50% incidence of dementia in PCD reported by previous investigators. Widespread reductions in PCD rCMRGlc may result from the loss of cerebellar efferents to thalamus and forebrain structures, a reverse cerebellar diaschisis

  10. Oculomotor studies of cerebellar function in autism.

    Science.gov (United States)

    Nowinski, Caralynn V; Minshew, Nancy J; Luna, Beatriz; Takarae, Yukari; Sweeney, John A

    2005-11-15

    Histopathological, neuroimaging and genetic findings indicate cerebellar abnormalities in autism, but the extent of neurophysiological dysfunction associated with those findings has not been systematically examined. Suppression of intrusive saccades (square wave jerks) and the ability to sustain eccentric gaze, two phenomena requiring intact cerebellar function, were examined in 52 high-functioning individuals with autism and 52 age- and IQ-matched healthy subjects during visual fixation of static central and peripheral targets. Rates of intrusive saccades were not increased in autism during visual fixation, and foveopetal ocular drift was also not increased when subjects held an eccentric gaze. The absence of gross disturbances of visual fixation associated with cerebellar disease in individuals with autism, such as increased square wave jerk rates and foveopetal drift when holding eccentric gaze, indicates that the functional integrity of cerebellar--brainstem networks devoted to oculomotor control is preserved in autism despite reported anatomic variations. However, increased amplitude of intrusive saccades and reduced latency of target refixation after intrusive saccades were observed in individuals with autism, especially when subjects maintained fixation of remembered target locations without sensory guidance. The atypical metrics of intrusive saccades that were observed may be attributable to faulty functional connectivity in cortico-cerebellar networks. PMID:16214219

  11. Metabolic anatomy of paraneoplastic cerebellar degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, N.E.; Posner, J.B.; Sidtis, J.J.; Moeller, J.R.; Strother, S.C.; Dhawan, V.; Rottenberg, D.A.

    1988-06-01

    Eleven patients with acquired cerebellar degeneration (10 of whom had paraneoplastic cerebellar degeneration (PCD)) were evaluated using neuropsychological tests and /sup 18/F-fluorodeoxyglucose/positron emission tomography to (1) quantify motor, cognitive, and metabolic abnormalities; (2) determine if characteristic alterations in the regional cerebral metabolic rate for glucose (rCMRGlc) are associated with PCD; and (3) correlate behavioral and metabolic measures of disease severity. Eighteen volunteer subjects served as normal controls. Although some PCD neuropsychological test scores were abnormal, these results could not, in general, be dissociated from the effects of dysarthria and ataxia. rCMRGlc was reduced in patients with PCD (versus normal control subjects) in all regions except the brainstem. Analysis of patient and control rCMRGlc data using a mathematical model of regional metabolic interactions revealed two metabolic pattern descriptors, SSF1 and SSF2, which distinguished patients with PCD from normal control subjects; SSF2, which described a metabolic coupling between cerebellum, cuneus, and posterior temporal, lateral frontal, and paracentral cortex, correlated with quantitative indices of cerebellar dysfunction. Our inability to document substantial intellectual impairment in 7 of 10 patients with PCD contrasts with the 50% incidence of dementia in PCD reported by previous investigators. Widespread reductions in PCD rCMRGlc may result from the loss of cerebellar efferents to thalamus and forebrain structures, a reverse cerebellar diaschisis.

  12. Genetics Home Reference: autosomal recessive cerebellar ataxia type 1

    Science.gov (United States)

    ... Genetics Home Health Conditions ARCA1 autosomal recessive cerebellar ataxia type 1 Enable Javascript to view the expand/ ... Open All Close All Description Autosomal recessive cerebellar ataxia type 1 ( ARCA1 ) is a condition characterized by ...

  13. Landmark based shape analysis for cerebellar ataxia classification and cerebellar atrophy pattern visualization

    Science.gov (United States)

    Yang, Zhen; Abulnaga, S. Mazdak; Carass, Aaron; Kansal, Kalyani; Jedynak, Bruno M.; Onyike, Chiadi; Ying, Sarah H.; Prince, Jerry L.

    2016-03-01

    Cerebellar dysfunction can lead to a wide range of movement disorders. Studying the cerebellar atrophy pattern associated with different cerebellar disease types can potentially help in diagnosis, prognosis, and treatment planning. In this paper, we present a landmark based shape analysis pipeline to classify healthy control and different ataxia types and to visualize the characteristic cerebellar atrophy patterns associated with different types. A highly informative feature representation of the cerebellar structure is constructed by extracting dense homologous landmarks on the boundary surfaces of cerebellar sub-structures. A diagnosis group classifier based on this representation is built using partial least square dimension reduction and regularized linear discriminant analysis. The characteristic atrophy pattern for an ataxia type is visualized by sampling along the discriminant direction between healthy controls and the ataxia type. Experimental results show that the proposed method can successfully classify healthy controls and different ataxia types. The visualized cerebellar atrophy patterns were consistent with the regional volume decreases observed in previous studies, but the proposed method provides intuitive and detailed understanding about changes of overall size and shape of the cerebellum, as well as that of individual lobules.

  14. Modelling of photonic crystal fibres

    DEFF Research Database (Denmark)

    Knudsen, Erik

    2003-01-01

    In the presenta ph.d. work a theoretical study of aspects of modelling photonic crystal fibres was carried out. Photonic crystal fibres form a class of optical waveguides where guidance is no longer provided by a difference in refractive index between core and cladding. Instead, guidance is...... provided by an arrangement of air-holes running along the length of the fibre. Depending on the geometry of the fibre, the guiding mechanism may be either arising from the formation of a photonic bandgap in the cladding structure (photonic bandgap fibre), or by an effect resembling total internal...... modes in contiguous fibre segments curved at different radii. Overall microbend loss is expressed as a statistical mean of mismatch losses. Extending a well proven, established formula for macrobending losses in stop index fibres, we provide an estimate of macrobend losses in an air-guiding photonic...

  15. Multiplicative gain modulation arising from inhibitory synaptic plasticity in the cerebellar nuclei

    Directory of Open Access Journals (Sweden)

    Dimitris Bampasakis

    2014-03-01

    Full Text Available Neurons use the rate of action potentials to encode sensory variables. This makes the output rate as a function of input, also known as input-output (I–O relationship, a core computational function in neuronal processing. The introduction, or increase, of a modulatory input, can transform this function in multiple ways: additive transformations result in a shift, and multiplicative transformations in a change of slope of the I–O relationship. This slope change is known as gain modulation, and it can implement important forms of neural computation such as coordinate transformations. Gain modulation can be found in a wide range of brain systems, including the cerebellum, where it can be enabled by synaptic plasticity at both excitatory and inhibitory synapses. We use a realistic, conductance based, multi-compartmental model of a cerebellar nucleus (CN neuron, to investigate the determinants of gain modulation mediated by synaptic plasticity. In particular, we are interested in the effect of short term depression (STD at the inhibitory synapse from Purkinje cells (PCs to CN neurons. Considering the inhibitory PC input as the driving input, we compare the I–O relationship of the CN neuron in the presence and absence of STD for 20 Hz of excitatory synaptic input from mossy fibers (MFs, and find that STD introduces a gain change, changing the slope of the I–O function. We then proceed to compare the transformation performed by the increase of the modulatory input from 20 to 50 Hz, in the presence and absence of STD. We find that the presence of STD in the inhibitory synapse introduces a multiplicative component in the transformation performed by the excitatory input, an effect that persists for different levels of STD, and various combinations of regularity and synchronicity in the input.

  16. Anomalous Cerebellar Anatomy in Chinese Children with Dyslexia

    OpenAIRE

    Yang, Ying-Hui; Yang, Yang; Chen, Bao-Guo; Zhang, Yi-Wei; Bi, Hong-Yan

    2016-01-01

    The cerebellar deficit hypothesis for developmental dyslexia claims that cerebellar dysfunction causes the failures in the acquisition of visuomotor skills and automatic reading and writing skills. In people with dyslexia in the alphabetic languages, the abnormal activation and structure of the right or bilateral cerebellar lobes have been identified. Using a typical implicit motor learning task, however, one neuroimaging study demonstrated the left cerebellar dysfunction in Chinese children ...

  17. Intercomparison of sediment sampling devices using artificial radionuclides in Baltic Sea sediments. The MOSSIE Report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    affect the results, at least if the calculations are based on the Cs{sup -137} and Pu{sup -239,240} peaks. To get proper results, it is essential to obtain reliable samples from sediments. False conclusions are an obvious risk if the studies are based on biased field samples. To be more precise, it is unreasonable to perform exacting and expensive analyses if the samples themselves are unreliable or of poor quality. However, sampling of the top, least consolidated sediments is difficult and, in addition to properly designed devices, requires standardised, and precise working methods, as well as experience and competence from the crew, including awareness of sources of error. Sediment sampling is without doubt one of the most exacting sampling tasks in the aquatic environment. The prime reason is that the upper, most recent layers of sediments are usually very soft and susceptible to resuspension, i.e. the interface between water and sediment resembles 'a line drawn in water'. The fact that the crew normally can not see what is happening when the sampling device penetrates the sediment makes the work even more difficult. The MORS (Monitoring of Radioactive Substances) Group of HELCOM (Helsinki Commission) handles radioactivity monitoring in the Baltic Sea. All the countries surrounding the Baltic Sea are partners in this co-operation and all results from participating laboratories are reported and stored in a joint database. The MORS monitoring programme includes regulatory sampling and analyses of sediments at permanent stations performed by different partners, and the variety of sampling devices used by different laboratories is great. The Group therefore decided to arrange an intercomparison exercise on sediment sampling methods and devices called 'MOSSIE' (MOrs Sediment Sampling Intercalibration Exercise) in 1992. The arrangements for the exercise, the devices compared and the results are presented and discussed in this report. In addition to the

  18. Cerebellar contribution to feedforward control of locomotion

    Directory of Open Access Journals (Sweden)

    Iolanda Pisotta

    2014-06-01

    Full Text Available The cerebellum is an important contributor to feedforward control mechanisms of the central nervous system, and sequencing—the process that allows spatial and temporal relationships between events to be recognized—has been implicated as the fundamental cerebellar mode of operation. By adopting such a mode and because of cerebellar activity patterns are sensitive to a variety of sensorimotor-related tasks, the cerebellum is believed to support motor and cognitive functions that are encoded in the frontal and parietal lobes of the cerebral cortex. In this model, the cerebellum is hypothesized to make predictions about the consequences of a motor or cognitive command that originates from the cortex to prepare the entire system to cope with ongoing changes. In this framework, cerebellar predictive mechanisms for locomotion are addressed, focusing on sensorial and motoric sequencing. The hypothesis that sequence recognition is the mechanism by which the cerebellum functions in gait control is presented and discussed.

  19. Cerebellar contribution to feedforward control of locomotion.

    Science.gov (United States)

    Pisotta, Iolanda; Molinari, Marco

    2014-01-01

    The cerebellum is an important contributor to feedforward control mechanisms of the central nervous system, and sequencing-the process that allows spatial and temporal relationships between events to be recognized-has been implicated as the fundamental cerebellar mode of operation. By adopting such a mode and because cerebellar activity patterns are sensitive to a variety of sensorimotor-related tasks, the cerebellum is believed to support motor and cognitive functions that are encoded in the frontal and parietal lobes of the cerebral cortex. In this model, the cerebellum is hypothesized to make predictions about the consequences of a motor or cognitive command that originates from the cortex to prepare the entire system to cope with ongoing changes. In this framework, cerebellar predictive mechanisms for locomotion are addressed, focusing on sensorial and motoric sequencing. The hypothesis that sequence recognition is the mechanism by which the cerebellum functions in gait control is presented and discussed. PMID:25009490

  20. CT and MR imaging of acute cerebellar ataxia

    International Nuclear Information System (INIS)

    An adult female showed mild cerebellar ataxia and CSF pleocytosis following an acute infection of the upper respiratory tract, and was diagnosed as having acute cerebellar ataxia (ACA). CT and MR appearances in the acute stage revealed moderate swelling of the cerebellum and bilaterally increased signal intensity in the cerebellar cortex. (orig.)

  1. Electrophysiological, morphological, and topological properties of two histochemically distinct subpopulations of cerebellar unipolar brush cells.

    Science.gov (United States)

    Kim, Jin-Ah; Sekerková, Gabriella; Mugnaini, Enrico; Martina, Marco

    2012-12-01

    Unipolar brush cells (UBCs) are excitatory cerebellar granular layer interneurons whose brush-like dendrites receive one-to-one mossy fiber inputs. Subclasses of UBCs differ primarily by expressing metabotropic glutamate receptor (mGluR) 1α or calretinin. We used GENSAT Tg(Grp-EGFP) BAC transgenic mice, which selectively express enhanced green fluorescent protein (EGFP) in mGluR1α-positive UBCs to compare the functional properties of the two subclasses. Compared to EGFP-negative UBCs, which include the calretinin-positive cells, EGFP-positive UBCs had smaller somata (area 48 vs 63 μm(2)), lower specific membrane resistance (6.4 vs. 13.7 KΩ cm(2)), were less prone to intrinsic firing, and showed more irregular firing (in cell-attached ~49 % were firing vs. ~88 %, and the CV was 0.53 vs. 0.32 for EGFP-negative cells). Some of these differences are attributable to higher density of background K(+) currents in EGFP-positive cells (at -120 mV, the barium-sensitive current was 94 vs. 37 pA in EGFP-negative cells); Ih, on the contrary, was more abundantly expressed in EGFP-negative cells (at -140 mV, it was -122 vs. -54 pA in EGFP-positive neurons); furthermore, while group II mGluR modulation of the background potassium current in EGFP-negative UBCs was maintained after intracellular dialysis, mGluR modulation in EGFP-positive UBCs was lost in whole-cell recordings. Finally, cell-attached firing was reversibly abolished by the GABA(B) activation in EGFP-positive, but not in EGFP-negative UBCs. Immunohistochemistry showed that EGFP-negative UBCs express GIRK2 at high density, while mGluR1α UBCs are GIRK2 negative, suggesting that GIRK2 mediates the mGluR-sensitive current in EGFP-negative UBCs. These data suggest that the two subclasses perform different functions in the cerebellar microcircuits. PMID:22528965

  2. A rare case of tubercular cerebellar abscess

    Directory of Open Access Journals (Sweden)

    Wanjari K

    2009-01-01

    Full Text Available Tubercular brain abscess are uncommon and tubercular cerebellar abscess are rarely reported. Most of these cases occur in immunocompromised patients. We report a case of multiple cerebellar abscesses in a 55-year-old HIV seronegative non-diabetic female, who complained of headache, neck pain and unsteadiness of gait since two months. She had been on treatment for pulmonary tuberculosis, diagnosed earlier. Diagnosis was made by CT scan of brain and confirmed by bacteriological examination of drained pus obtained by suboccipital craniotomy. The patient showed signs of recovery.

  3. Crossed cerebellar diaschisis in ischemic stroke

    DEFF Research Database (Denmark)

    Meneghetti, G; Vorstrup, S; Mickey, B; Lindewald, H; Lassen, N A

    1984-01-01

    Seventy measurements of CBF were performed in 12 stroke patients by 133Xe inhalation and a rapidly rotating single photon emission computerized tomograph. CBF was measured every other day during the acute phase and at 2- and 6-month follow-up visits. A persistent contralateral cerebellar blood flow...... is concluded from this serial study that crossed cerebellar diaschisis is a common finding in completed stroke. It is probably caused by disconnection of the corticopontine pathways, a disconnection that tends to persist. The phenomenon is in fact less variable than the stroke-related CBF changes in...

  4. Neuroprotective Effect of Uncaria rhynchophylla in Kainic Acid-Induced Epileptic Seizures by Modulating Hippocampal Mossy Fiber Sprouting, Neuron Survival, Astrocyte Proliferation, and S100B Expression

    Directory of Open Access Journals (Sweden)

    Chung-Hsiang Liu

    2012-01-01

    Full Text Available Uncaria rhynchophylla (UR, which is a traditional Chinese medicine, has anticonvulsive effect in our previous studies, and the cellular mechanisms behind this are still little known. Because of this, we wanted to determine the importance of the role of UR on kainic acid- (KA- induced epilepsy. Oral UR for 6 weeks can successfully attenuate the onset of epileptic seizure in animal tests. Hippocampal mossy fiber sprouting dramatically decreased, while neuronal survival increased with UR treatment in hippocampal CA1 and CA3 areas. Furthermore, oral UR for 6 weeks significantly attenuated the overexpression of astrocyte proliferation and S100B proteins but not γ-aminobutyric acid A (GABAA receptors. These results indicate that oral UR for 6 weeks can successfully attenuate mossy fiber sprouting, astrocyte proliferation, and S100B protein overexpression and increase neuronal survival in KA-induced epileptic rat hippocampus

  5. The Cerebellar Mutism Syndrome and Its Relation to Cerebellar Cognitive Function and the Cerebellar Cognitive Affective Disorder

    Science.gov (United States)

    Wells, Elizabeth M.; Walsh, Karin S.; Khademian, Zarir P.; Keating, Robert F.; Packer, Roger J.

    2008-01-01

    The postoperative cerebellar mutism syndrome (CMS), consisting of diminished speech output, hypotonia, ataxia, and emotional lability, occurs after surgery in up to 25% of patients with medulloblastoma and occasionally after removal of other posterior fossa tumors. Although the mutism is transient, speech rarely normalizes and the syndrome is…

  6. Non-progressive cerebellar ataxia and previous undetermined acute cerebellar injury: a mysterious clinical condition

    Directory of Open Access Journals (Sweden)

    Wladimir Bocca Vieira de Rezende Pinto

    2015-01-01

    Full Text Available Cerebellar ataxias represent a wide group of neurological diseases secondary to dysfunctions of cerebellum or its associated pathways, rarely coursing with acute-onset acquired etiologies and chronic non-progressive presentation. We evaluated patients with acquired non-progressive cerebellar ataxia that presented previous acute or subacute onset. Clinical and neuroimaging characterization of adult patients with acquired non-progressive ataxia were performed. Five patients were identified with the phenotype of acquired non-progressive ataxia. Most patients presented with a juvenile to adult-onset acute to subacute appendicular and truncal cerebellar ataxia with mild to moderate cerebellar or olivopontocerebellar atrophy. Establishing the etiology of the acute triggering events of such ataxias is complex. Non-progressive ataxia in adults must be distinguished from hereditary ataxias.

  7. Non-progressive cerebellar ataxia and previous undetermined acute cerebellar injury: a mysterious clinical condition

    Directory of Open Access Journals (Sweden)

    Wladimir Bocca Vieira de Rezende Pinto

    2015-10-01

    Full Text Available Cerebellar ataxias represent a wide group of neurological diseases secondary to dysfunctions of cerebellum or its associated pathways, rarely coursing with acute-onset acquired etiologies and chronic non-progressive presentation. We evaluated patients with acquired non-progressive cerebellar ataxia that presented previous acute or subacute onset. Clinical and neuroimaging characterization of adult patients with acquired non-progressive ataxia were performed. Five patients were identified with the phenotype of acquired non-progressive ataxia. Most patients presented with a juvenile to adult-onset acute to subacute appendicular and truncal cerebellar ataxia with mild to moderate cerebellar or olivopontocerebellar atrophy. Establishing the etiology of the acute triggering events of such ataxias is complex. Non-progressive ataxia in adults must be distinguished from hereditary ataxias.

  8. Case of subacute cerebellar degeneration associated with pleocytosis and cerebellar swelling shown in computed tomography scanning

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, Hiide; Anezaki, Toshiharu; Takashima, Noriko; Inuzuka, Takashi; Miyatake, Tadashi

    1988-02-01

    A 44 year old woman was healthy until January 3, 1986, when she had headache. On January 9, she developed gait ataxia and dysarthria. Cerebellar ataxia worsened rapidly. Aftar a week she could not sit without support and her consciousness was disturbed. Corticosteroid was administrated and consciousness proved alert, but cerebellar ataxia and dysarthria remained unchanged. The patient was found carcinoma of the lung in August 1986. Characteristic features of clinical and laboratory findings of this patient are acute progression, cerebrospinal fluid pleocytosis of 1,064/3 cells (860 mononuclear cell, 204 polymorphonuclear cell), and cerebellar swelling shown in computed tomography scanning. Though the mechanism of acute cerebellar degeneration is still uncertained, inflammatory process was supported to exist in cerebellum of this case.

  9. Effet dose-réponse de la gonadotropine (PMSG sur la reproduction de la brebis Djalonké variété 'Mossi'

    Directory of Open Access Journals (Sweden)

    Boly, H.

    2000-01-01

    Full Text Available Dose Effects of Pregnant Mare Serum Gonadotropin on Reproductive Performances of Djalonke var. 'Mossi' Ewes. The dose/response effects of PMSG (Pregnant Mare Serum Gonadotropin were appreciated in 3 lots of Djalonke var. 'Mossi' ewes synchronised using an intravaginal device of progestagen associated with 0 ; 200 or 400 IU of PMSG. The use of ram jumping combined with plasma progesterone measurements showed that in the ewes treated with PMSG, estrus occured earlier after sponge removal : 54.7 ± 18 h in lot 0 ; 37.2 ± 12.5 h in lot 1 and 34.4 ±12 h in lot 2. However, the duration of estrus increased : 38.4 ± 36.3 h (lot 0, 43.2 ± 10.7 h (lot 1 and 57.6 ± 27.3 h (lot 2. The ovum of ewes treated with PMSG were not all good for fertilization and pregnancy because of the repeat heat frequency and fetus deaths found in the PMSG treated group. There is a dose dependant relation with PMSG, and the 200 IU of lot 1 seem to be better than the 400 IU of lot 2. Moreover during parturition, mortinatality was found in lot 2. The reproductive performances were weak for the lot without PMSG and may be related to the use of a progestagen standard dose not adapted to the small format of Djalonke var. 'Mossi' ewe.

  10. Optical fibre nanowire devices

    OpenAIRE

    Xu, Fei

    2008-01-01

    The Optical Fibre Nanowire (OFN) is a potential building block in future micro- and nano-photonic device since it offers a number of unique optical and mechanical properties. In this thesis, the background and fundamental features of nanowires are introduced; the theory, design and demonstration of novel nanowire devices are discussed. At first, a short adiabatic taper tip is manufactured, and it is used as optical tweezers for trapping 1?m microspheres. Then, the most important devic...

  11. Cerebellar motor dysfunction in schizophrenia and psychosis risk: the importance of regional cerebellar analysis approaches

    Directory of Open Access Journals (Sweden)

    Jessica A Bernard

    2014-11-01

    Full Text Available Motor abnormalities in individuals with schizophrenia and those at-risk for psychosis are well documented. An accumulating body of work has also highlighted motor abnormalities related to cerebellar dysfunction in schizophrenia including eye-blink conditioning, timing, postural control, and motor learning. We have also recently found evidence for motor dysfunction in individuals at ultra high-risk for psychosis (1–3. This is particularly relevant as the cerebellum is thought to be central to the cognitive dysmetria model of schizophrenia, and these overt motor signs may point to more general cerebellar dysfunction in the etiology of psychotic disorders. While studies have provided evidence indicative of motor cerebellar dysfunction in at-risk populations and in schizophrenia, findings with respect to the cerebellum have been mixed. One factor potentially contributing to these mixed results is the whole-structure approach taken when investigating the cerebellum. In non-human primates there are distinct closed-loop circuits between the cerebellum, thalamus, and brain with motor and non-motor cortical regions. Recent human neuroimaging has supported this finding and indicates that there is a cerebellar functional topography (4, and this information is being missed with whole-structure approaches. Here, we review cerebellar motor dysfunction in individuals with schizophrenia and those at-risk for psychosis. We also discuss cerebellar abnormalities in psychosis, and the cerebellar functional topography. Because of the segregated functional regions of the cerebellum, we propose that it is important to look at the structure regionally in order to better understand its role in motor dysfunction in these populations. This is analogous to approaches taken with the basal ganglia, where each region is considered separately. Such an approach is necessary to better understand cerebellar pathophysiology on a macro-structural level with respect to the

  12. Ultrasonically detectable cerebellar haemorrhage in preterm infants.

    LENUS (Irish Health Repository)

    McCarthy, Lisa Kenyon

    2011-07-01

    To determine the frequency and pattern of cerebellar haemorrhage (CBH) on routine cranial ultrasound (cUS) imaging in infants of ≤32 weeks gestation, and to investigate how extremely preterm infants with CBH differ from those with severe intraventricular haemorrhage (IVH).

  13. Cerebellar dysregulation and heterogeneity of mood disorders

    OpenAIRE

    Tobe EH

    2014-01-01

    Edward H Tobe Department of Psychiatry, Cooper Medical School of Rowan University, Camden, NJ, USA Abstract: This paper discusses diverse studies to consider the hypothesis that cerebellar pathology supports the heterogeneous metabolic pathologies of mood disorders. The evidence presented includes studies selected from the following areas of scientific research: magnetic resonance imaging, histology, clinical syndromes, comparative anatomy, neuronal connections, and mitochondrial dysfunctio...

  14. Cerebellar liponeurocytoma: a case-report

    Directory of Open Access Journals (Sweden)

    K.V. Sreedhar Babu

    Full Text Available Cerebellar liponeurocytoma is a rare cerebellar neoplasm of adults with advanced neuronal / neurocytic and focal lipomatous differentiation, a low proliferative potential and a favorable clinical prognosis corresponding to World Health Organization grade I or II. Only a few cases have been described in the literature (approximately 20 cases by different names. A 48-years old female, presented with history of headache and dizziness associated with neck pain; restricted neck movements, drop attacks and occasional regurgitation of food since one year. Magnetic resonance imaging disclosed a right cerebellar mass lesion. Gross total resec- tion of the tumour was accomplished through a suboccipital craniotomy. The excised tissue was diagnosed as cerebellar liponeurocytoma, a rare entity, based on histopathological examination and immunohistochemistry. The morphological appearance of this neoplasm can be confused with that of oligodendroglioma, neurocytoma, ependymoma, medulloblastoma, solid hemangioblastoma and metastatic carcinomas etc., with unpredictable prognosis, which require postoperative radiotherapy, hence the importance of accurately diagnosing this rare neoplasm. This tumour should be added to the differential diagnosis of mass lesions of the posterior fossa.

  15. Inverse Stochastic Resonance in Cerebellar Purkinje Cells

    Science.gov (United States)

    Häusser, Michael; Gutkin, Boris S.; Roth, Arnd

    2016-01-01

    Purkinje neurons play an important role in cerebellar computation since their axons are the only projection from the cerebellar cortex to deeper cerebellar structures. They have complex internal dynamics, which allow them to fire spontaneously, display bistability, and also to be involved in network phenomena such as high frequency oscillations and travelling waves. Purkinje cells exhibit type II excitability, which can be revealed by a discontinuity in their f-I curves. We show that this excitability mechanism allows Purkinje cells to be efficiently inhibited by noise of a particular variance, a phenomenon known as inverse stochastic resonance (ISR). While ISR has been described in theoretical models of single neurons, here we provide the first experimental evidence for this effect. We find that an adaptive exponential integrate-and-fire model fitted to the basic Purkinje cell characteristics using a modified dynamic IV method displays ISR and bistability between the resting state and a repetitive activity limit cycle. ISR allows the Purkinje cell to operate in different functional regimes: the all-or-none toggle or the linear filter mode, depending on the variance of the synaptic input. We propose that synaptic noise allows Purkinje cells to quickly switch between these functional regimes. Using mutual information analysis, we demonstrate that ISR can lead to a locally optimal information transfer between the input and output spike train of the Purkinje cell. These results provide the first experimental evidence for ISR and suggest a functional role for ISR in cerebellar information processing. PMID:27541958

  16. Improving cerebellar segmentation with statistical fusion

    Science.gov (United States)

    Plassard, Andrew J.; Yang, Zhen; Prince, Jerry L.; Claassen, Daniel O.; Landman, Bennett A.

    2016-03-01

    The cerebellum is a somatotopically organized central component of the central nervous system well known to be involved with motor coordination and increasingly recognized roles in cognition and planning. Recent work in multiatlas labeling has created methods that offer the potential for fully automated 3-D parcellation of the cerebellar lobules and vermis (which are organizationally equivalent to cortical gray matter areas). This work explores the trade offs of using different statistical fusion techniques and post hoc optimizations in two datasets with distinct imaging protocols. We offer a novel fusion technique by extending the ideas of the Selective and Iterative Method for Performance Level Estimation (SIMPLE) to a patch-based performance model. We demonstrate the effectiveness of our algorithm, Non- Local SIMPLE, for segmentation of a mixed population of healthy subjects and patients with severe cerebellar anatomy. Under the first imaging protocol, we show that Non-Local SIMPLE outperforms previous gold-standard segmentation techniques. In the second imaging protocol, we show that Non-Local SIMPLE outperforms previous gold standard techniques but is outperformed by a non-locally weighted vote with the deeper population of atlases available. This work advances the state of the art in open source cerebellar segmentation algorithms and offers the opportunity for routinely including cerebellar segmentation in magnetic resonance imaging studies that acquire whole brain T1-weighted volumes with approximately 1 mm isotropic resolution.

  17. Calcium binding by dietary fibre

    International Nuclear Information System (INIS)

    Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre reduces the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids liberates the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity on the colon for calcium. (author)

  18. Flow diagnostics using fibre optics

    OpenAIRE

    Vasudevan, B.; Padbidri, Srikanth; Kishore, Chandra M

    2007-01-01

    Research in the area of flow diagnostics using fibre-optics started in our laboratory in early 1998. The first-ever multi-component wind tunnel balance in the world, working with fibre-optic sensors was built and demonstrated in 1999. Since then, several new applications of the technique in the area of fluid dynamic load measurements have been tried successfully. Very recently, fibre-optic sensors have been effectively used for underwater applications, where conventional measurements are r...

  19. Magnetic resonance imaging of cerebellar Schistosomiasis mansoni

    International Nuclear Information System (INIS)

    A 15-year-old boy was admitted to hospital with a history of headache, dizziness, vomiting and double vision that started two weeks before. His parents denied any previous disease. During clinical examination he presented diplopia on lateral gaze to the left and horizontal nystagmus. No major neurological dysfunction was detected. He was well built, mentally responsive and perceptive. Laboratory findings revealed a leukocyte count of 10,000/mL, a normal red blood cell count and no eosinophilia. The magnetic resonance images (MRI) of the brain showed a left cerebellar lesion with mass effect compressing the surrounding tissues. Contrast-enhanced images showed a mass like structure and punctate nodules (Figures A and B: axial and coronal contrast-enhanced T1-weighted MR images showed the nodular - yellow arrows - enhancement pattern of a left cerebellar intraxial lesion). The lesion extended to the vermis and brachium pons and compressed the medulla. There was no hydrocephalus. He was taken to the operating room with the presumptive diagnosis of a neuroglial tumor, and submitted to a lateral suboccipital craniectomy. A brown, brittle tumoral mass without a clearly defined margin with the cerebellar tissue was removed. Microscopic examination revealed schistosomal granulomas in the productive phase in the cerebellum (Figure C). After surgery, treatment with praziquantel (50 mg/kg/dia, single dose) and prednisone (1 mg/kg/day) was offered and the patient improved quickly. Thirty days later he was seen again at the outpatient clinic: he was asymptomatic and with no neurological impairment. This is the eighth case of cerebellar involvement in schistosomiasis mansoni and the second report of a tumoral form of cerebellar schistosomiasis documented by magnetic resonance images. (author)

  20. Fibre constituents of some foods.

    Science.gov (United States)

    Rani, B; Kawatra, A

    1994-06-01

    Some plant foods viz. bottlegourd, carrot, cauliflower, cabbage, green bengalgram, pea, apple, plum, guava, karonda, blackgram husk and lentil husk were analysed for their dietary fibre components. The total dietary fibre contents of these foods varied from 14.68 to 78.21 percent on dry matter basis. As compared to fruits and vegetables, the husks had higher amount of total dietary fibre. Cellulose represented as the major fibre constituent in most of the foods whereas, husks were observed to be good sources of hemicellulose. All foods were low in pectin and lignin contents except guava. PMID:7971775

  1. Analysis of glass fibre sizing

    DEFF Research Database (Denmark)

    Petersen, Helga Nørgaard; Kusano, Yukihiro; Brøndsted, Povl;

    2014-01-01

    Glass fibre reinforced polymer composites are widely used for industrial and engineering applications which include construction, aerospace, automotive and wind energy industry. During the manufacturing glass fibres, they are surface-treated with an aqueous solution. This process and the treated...... surfaces are called sizing. The sizing influences the properties of the interface between fibres and a matrix, and subsequently affects mechanical properties of composites. In this work the sizing of commercially available glass fibres was analysed so as to study the composition and chemical structures...

  2. The GABAB1a isoform mediates heterosynaptic depression at hippocampal mossy fiber synapses

    DEFF Research Database (Denmark)

    Guetg, Nicole; Seddik, Riad; Vigot, Réjan;

    2009-01-01

    GABA(B) receptor subtypes are based on the subunit isoforms GABA(B1a) and GABA(B1b), which associate with GABA(B2) subunits to form pharmacologically indistinguishable GABA(B(1a,2)) and GABA(B(1b,2)) receptors. Studies with mice selectively expressing GABA(B1a) or GABA(B1b) subunits revealed that...... GABA(B(1a,2)) receptors are more abundant than GABA(B(1b,2)) receptors at glutamatergic terminals. Accordingly, it was found that GABA(B(1a,2)) receptors are more efficient than GABA(B(1b,2)) receptors in inhibiting glutamate release when maximally activated by exogenous application of the agonist...... baclofen. Here, we used a combination of genetic, ultrastructural and electrophysiological approaches to analyze to what extent GABA(B(1a,2)) and GABA(B(1b,2)) receptors inhibit glutamate release in response to physiological activation. We first show that at hippocampal mossy fiber (MF)-CA3 pyramidal...

  3. Microstructured Optical Fibres

    DEFF Research Database (Denmark)

    1999-01-01

    complete PBGs, which reflects light incident from air or vacuum. Such structures may be used as cladding structures in optical fibres, where light is confined and thereby guided in a hollow core region. In addition, the present invention relates to designs for ultra low-loss PBG waveguiding structures......, which are easy to manufacture. Finally, the present invention relates to a new fabrication technique, which allows easy manufacturing of preforms for photonic crystal fibers with large void filling fractions, as well as it allows a high flexibility in the design of the cladding and core structures....

  4. Scintillating-fibre calorimetry

    International Nuclear Information System (INIS)

    In the past decade, calorimetry based on scintillating plastic fibres as active elements was developed from a conceptual idea to a mature detector technology, which is nowadays widely applied in particle physics experiments. This development and the performance characteristics of representative calorimeters, both for the detection of electromagnetic and hadronic showers, are reviewed. We also discuss new information on shower development processes in dense matter and its application to calorimetric principles that has emerged from some very thorough studies that were performed in the framework of this development. (orig.)

  5. Design of DFB fibre lasers

    DEFF Research Database (Denmark)

    Lauridsen, Vibeke Claudia; Povlsen, Jørn Hedegaard; Varming, Poul

    1998-01-01

    A numerical model for erbium distributed feedback (DFB) fibre lasers is presented. The model is used to optimise the location of a discrete phase-shift to obtain maximum output power. For DFB fibre lasers of up to 10cm in length it is shown that the influence of Kerr nonlinearity with respect to...

  6. Fibre-induced drag reduction

    NARCIS (Netherlands)

    Gillissen, J.J.J.; Boersma, B.J.; Mortensen, P.H.; Andersson, H.I.

    2008-01-01

    We use direct numerical simulation to study turbulent drag reduction by rigid polymer additives, referred to as fibres. The simulations agree with experimental data from the literature in terms of friction factor dependence on Reynolds number and fibre concentration. An expression for drag reduction

  7. High-power fibre lasers

    Science.gov (United States)

    Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2013-11-01

    Fibre lasers are now associated with high average powers and very high beam qualities. Both these characteristics are required by many industrial, defence and scientific applications, which explains why fibre lasers have become one of the most popular laser technologies. However, this success, which is largely founded on the outstanding characteristics of fibres as an active medium, has only been achieved through researchers around the world striving to overcome many of the limitations imposed by the fibre architecture. This Review focuses on these limitations, both past and current, and the creative solutions that have been proposed for overcoming them. These solutions have enabled fibre lasers to generate the highest diffraction-limited average power achieved to date by solid-state lasers.

  8. Aligned flax fibre/polylactate composites

    DEFF Research Database (Denmark)

    Madsen, Bo; Lilholt, Hans; Thygesen, Anders;

    2008-01-01

    The potential of biocomposites in engineering applications is demonstrated by using aligned flax fibre/polylactate composites as a materials model system. The failure stress of flax fibres is measured by tensile testing of single fibres and fibre bundles. For both fibre configurations, it is foun...... flax fibre composites and traditional fibre composites (exemplified by glass fibre composites) are presented. The stiffness per volume, per weight and per cost is compared for these two types of composites.......The potential of biocomposites in engineering applications is demonstrated by using aligned flax fibre/polylactate composites as a materials model system. The failure stress of flax fibres is measured by tensile testing of single fibres and fibre bundles. For both fibre configurations, it is found...... that failure stress is decreased by increasing the tested fibre volume. Based on two types of flax fibre preforms: carded sliver and unidirectional non-crimp fabric, aligned flax fibre/polylactate composites were fabricated with variable fibre content. The volumetric composition and tensile properties...

  9. An update on Spino-cerebellar ataxias

    Directory of Open Access Journals (Sweden)

    Banashree Mondal

    2013-01-01

    Full Text Available The dominantly inherited ataxias, also known as Spino-cerebellar ataxias (SCAs, are rapidly expanding entities. New mutations are being identified at remarkable regularity. Recent awareness of molecular abnormalities in SCAs has addressed some of the long sought questions, but gaps in knowledge still exist. Three major categories of SCAs, according to molecular mechanisms, have evolved over recent few years: Polyglutamate expansion ataxia, non-coding zone repeat ataxia, and ataxia due to conventional mutation. Using the fulcrum of these mechanisms, the article provides an update of SCAs. Shared and specific clinical features, genetic abnormalities, and possible links between molecular abnormalities and cerebellar degeneration have been discussed. Emphasis has been placed on the mechanisms of polyglutamate toxicity.

  10. Isolated rhomboencephalosynapsis – a rare cerebellar anomaly

    International Nuclear Information System (INIS)

    Rhomboencephalosynapsis (RES, RS) is a unique entity usually recognized in infancy based on neuroimaging. Cerebellar fusion and absence of cerebellar vermis is often associated with supratentorial findings. Since now there are about 50 cases described worldwide, with approximately 36 patients diagnosed by MRI. The authors present the first in Poland case of this uncommon malformation and review the literature. The authors describe a 28-month-old-girl with microcephaly and proper psychomotor development. The family history was unrelevant. Based on MRI the congenital malformation of posterior fossa-rhombencephalosynapsis was confirmed Presented patient is a typical example of MRI usefulness especially in patients with RES. RES symptoms are mild and that is why the diagnosis is usually made only in adulthood

  11. Hereditary spastic paraplegia with cerebellar ataxia

    DEFF Research Database (Denmark)

    Nielsen, J E; Johnsen, B; Koefoed, P;

    2004-01-01

    identified in those individuals who were clinically affected by a complex phenotype consisting of HSP and cerebellar ataxia. Other features noted in this kindred including epilepsy, cognitive impairment, depression, and migraine did not segregate with the HSP phenotype or mutation, and therefore the...... significantly relatively decreased regional cerebral blood flow in most of the cerebellum. We conclude that this kindred demonstrates a considerable overlap between cerebellar ataxia and spastic paraplegia, emphasizing the marked clinical heterogeneity of HSP associated with spastin mutations.......Complex forms of hereditary spastic paraplegia (HSP) are rare and usually transmitted in an autosomal recessive pattern. A family of four generations with autosomal dominant hereditary spastic paraplegia (AD-HSP) and a complex phenotype with variably expressed co-existing ataxia, dysarthria...

  12. Cerebellar ataxia as presenting feature of hypothyroidism.

    Science.gov (United States)

    Kotwal, Suman Kumar; Kotwal, Shalija; Gupta, Rohan; Singh, Jang Bhadur; Mahajan, Annil

    2016-04-01

    Symptoms and signs of the hypothyroidism vary in relation to the magnitude and acuteness of the thyroid hormone deficiency. The usual clinical features are constipation, fatigue, cold intolerance and weight gain. Rarely it can present with neurologic problems like reversible cerebellar ataxia, dementia, peripheral neuropathy, psychosis and coma. Hypothyroidism should be suspected in all cases of ataxia, as it is easily treatable. A 40 year-old male presented with the history facial puffiness, hoarseness of voice and gait-ataxia. Investigations revealed frank primary hypothyroidism. Anti-TPO antibody was positive. Thyroxine was started and patient improved completely within eight weeks. Hypothyroidism can present with ataxia as presenting feature. Hypothyroidism should be considered in all cases of cerebellar ataxia as it is a reversible cause of ataxia. PMID:26886095

  13. Speciality optical fibres for astronomy

    Science.gov (United States)

    Ellis, S. C.; Bland-Hawthorn, J.

    2015-05-01

    Astrophotonics is a rapidly developing area of research which applies photonic technology to astronomical instrumentation. Such technology has the capability of significantly improving the sensitivity, calibration and stability of astronomical instruments, or indeed providing novel capabilities which are not possible using classical optics. We review the development and application of speciality fibres for astronomy, including multi-mode to single-mode converters, notch filters and frequency combs.In particular we focus on our development of instruments designed to filter atmospheric emission lines to enable much deeper spectroscopic observations in the near-infrared. These instruments employ two novel photonic technologies. First, we have developed complex aperiodic fibre Bragg gratings which filter over 100 irregularly spaced wavelengths in a single device, covering a bandwidth of over 200 nm. However, astronomical instruments require highly multi-mode fibres to enable sufficient coupling into the fibre, since atmospheric turbulence heavily distorts the wavefront. But photonic technologies such as fibre Bragg gratings, require single mode fibres. This problem is solved by the photonic lantern, which enables efficient coupling from a multi-mode fibre to an array of single-mode fibres and vice versa. We present the results of laboratory tests of these technologies and of on-sky experiments made using the first instruments to deploy these technologies on a telescope. These tests show that the fibre Bragg gratings suppress the night sky background by a factor of 9. Current instruments are limited by thermal and detector emission. Planned instruments should improve the background suppression even further, by optimising the design of the spectrograph for the properties of the photonic components. Finally we review ongoing research in astrophotonics, including multi-moded multicore fibre Bragg gratings, which enable multiple gratings to be written into the same device

  14. CT in autosomal dominant and idiopathic cerebellar ataxia

    International Nuclear Information System (INIS)

    Signs of atrophy on cranial CT were investigated in 35 patients diagnosed as suffering from autosomal dominant (n=21) or idiopathic (n=14) cerebellar ataxia. Thirteen patients with a pure cerebellar syndrome were examined after at least 4 years of disease (mean duration 10.5 years) and were classified as cerebellar atrophy (CA). Twenty-two patients with additional non-cerebellar signs were classified as olivo-ponto-cerebellar atrophy (OPCA). Four (30%) of the patients with CA had atrophy of the brain stem in addition. Of the 22 patients with OPCA, 9 (40%) had atrophy of the cerebellum only. In patients with CA or OPCA correlation of clinical signs with severity of atrophy on CT was poor. Atrophy on CT often fails to differentiate autosomal dominant or idiopathic cerebellar ataxias in CA or OPCA: Patients with CA can also have atrophy of the brain stem and patients with OPCA do not necessarily show brain stem atrophy. (orig.)

  15. Moving, sensing and learning with cerebellar damage

    OpenAIRE

    Bastian, Amy J.

    2011-01-01

    The cerebellum is a subcortical brain structure that is essential for learning and controlling movement. Recent work shows that the cerebellum also plays a role in certain perceptual abilities, beyond what would be expected secondary to poor movement control. This review covers these and other recent advances, focusing on how cerebellar damage affects human abilities ranging from sensory perception to movement control and motor learning.

  16. Cerebellar and cerebral atrophy in trichothiodystrophy

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Hye-Kyung; Sargent, Michael A.; Poskitt, Kenneth J. [British Columbia Children' s Hospital, Department of Radiology, Vancouver, BC (Canada); Prendiville, Julie S. [British Columbia Children' s Hospital, Division of Paediatric Dermatology, Department of Paediatrics, Vancouver, BC (Canada)

    2005-10-01

    Trichothiodystrophy is a rare neuroectodermal disorder of autosomal recessive inheritance that is characterized by brittle hair, nail dysplasia, ichthyosis, mental retardation, and gonadal failure. We describe a female patient whose cranial MRI revealed almost total lack of myelination in the supratentorial white matter, which is similar to the previously described cases. In addition, there was progressive cerebellar and cerebral atrophy, which has not been well documented in association with trichothiodystrophy. (orig.)

  17. Random distributed feedback fibre lasers

    International Nuclear Information System (INIS)

    The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors–random distributed feedback fibre laser–was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (∼0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the

  18. [Diagnostic and treatment of hypertensive cerebellar hematomas].

    Science.gov (United States)

    Krylov, V V; Dash'ian, V G; Murashko, A A; Burov, S A

    2009-01-01

    Authors analyzed the results of treatment of 56 patients with hypertensive cerebellar hemorrhages (volume 0,5-41 cm3). Brain stem symptoms were found in 45 (80%) of patients. The dislocation of brain stem was observed in 38 (68%) cases, occlusive hydrocephaly - in 22 (39%), intraventricular hemorrhage - in 26 (46%). Severity of state depended on character of disease course, presence of stem symptoms, awakening level, volume and localization of cerebellar hematoma, development of intraventricular hemorrhage, occlusive hydrocephaly and dislocation of brain stem. Thirty-six patients were operated. After the neurosurgical intervention, 22 (61%) patients were discharged without or with the minimal neurological deficit, 1 (3%) with marked disability and 13 (36%) patients died. In conclusion, the removal of hematoma is recommended in dislocation of brain stem and disturbance of consiousnes: the ventricular drainage - in occlusive hydrocephaly developed as a consequence of hemotamponade of IV ventricular. The surgical treatment is not recommended to patients with cerebellar hematomas with the volume less than 7 cm3. PMID:19491806

  19. Cerebro-cerebellar circuits in autism spectrum disorder

    OpenAIRE

    D'Mello, Anila M.; Stoodley, Catherine J.

    2015-01-01

    The cerebellum is one of the most consistent sites of abnormality in autism spectrum disorder (ASD) and cerebellar damage is associated with an increased risk of ASD symptoms, suggesting that cerebellar dysfunction may play a crucial role in the etiology of ASD. The cerebellum forms multiple closed-loop circuits with cerebral cortical regions that underpin movement, language, and social processing. Through these circuits, cerebellar dysfunction could impact the core ASD symptoms of social and...

  20. Sensory mechanisms of balance control in cerebellar disease

    OpenAIRE

    Bunn, L. M.

    2011-01-01

    A wealth of evidence exists to suggest that the cerebellum has an important role in the integration of vestibular, proprioceptive and visual sensory signals. Human bipedal balance depends on sensory integration and balance impairment is a common feature of cerebellar disease. I test the hypothesis that disrupted sensori-motor processing is responsible for balance impairment in cerebellar disease. Balance control in subjects with pure cerebellar disease (SCA6) was compared with matched healthy...

  1. GlyT2+ Neurons in the Lateral Cerebellar Nucleus

    OpenAIRE

    Uusisaari, Marylka; Knöpfel, Thomas

    2009-01-01

    The deep cerebellar nuclei (DCN) are a major hub in the cerebellar circuitry but the functional classification of their neurons is incomplete. We have previously characterized three cell groups in the lateral cerebellar nucleus: large non-GABAergic neurons and two groups of smaller neurons, one of which express green fluorescence protein (GFP) in a GAD67/GFP mouse line and is therefore GABAergic. However, as a substantial number of glycinergic and glycine/GABA co-expressing neurons have been ...

  2. Lacunar thalamic stroke with pure cerebellar and proprioceptive deficits.

    OpenAIRE

    Gutrecht, J A; Zamani, A A; D N Pandya

    1992-01-01

    Case reports of two patients with cerebellar ataxia and proprioceptive sensory loss are presented. MRI of the brain revealed lesions of the ventroposterior part of the thalamus. These patients illustrate clinically the anatomical independence of cerebellar and sensory pathways in the thalamus. We suggest that the ataxic deficit is caused by interruption of cerebellar outflow pathways in the thalamus and not secondary to sensory deafferentation.

  3. Ondansetron, a 5-HT3 antagonist, improves cerebellar tremor.

    OpenAIRE

    Rice, G P; Lesaux, J; Vandervoort, P.; Macewan, L; Ebers, G C

    1997-01-01

    It has been previously shown that ondansetron, a 5-HT3 antagonist, can ameliorate vertigo in patients with acute brainstem disorders. A coincidental benefit was the improvement of cerebellar tremor in some patients with both vertigo and tremor. To further evaluate this effect, a placebo controlled, double blind, crossover study was conducted of a single dose of intravenous ondansetron in 20 patients with cerebellar tremor caused by multiple sclerosis, cerebellar degeneration, or drug toxicity...

  4. Unilateral absence of cerebellar hemisphere: a case report

    International Nuclear Information System (INIS)

    We describe a 38-year-old woman with absence of right cerebellar hemisphere incidentally discovered by MR imaging. No cerebellar abnormality was detected on neurological examination. Tissue probably representing dysgenetic cerebellar tissue with no corticomedullary differentiation was present, connected to the right superior cerebellar peduncle. Ipsilateral enlargement of the pons and cerebral peduncle were additional findings. Although the terms ''aplasia'' or ''agenesis'' have been used to describe this entity, intrauterine destruction is the presumed pathogenetic mechanism in our case, and therefore these terms have been avoided. Asymmetry of pons and mesencephalon may be related to compensatory reorganisation or to the impairment of sequential development of nuclei and neural tracts. (orig.)

  5. Association Between Microglia, Inflammatory Factors, and Complement with Loss of Hippocampal Mossy Fiber Synapses Induced by Trimethyltin.

    Science.gov (United States)

    Kraft, Andrew D; McPherson, Christopher A; Harry, G Jean

    2016-07-01

    Complement-associated factors are implicated in pathogen presentation, neurodegeneration, and microglia resolution of tissue injury. To characterize complement activation with microglial clearance of degenerating mossy fiber boutons, hippocampal dentate granule neurons were ablated in CD-1 mice with trimethyltin (TMT; 2.2 mg/kg, i.p.). Neuronal apoptosis was accompanied by amoeboid microglia and elevations in tumor necrosis factor [Tnfa], interleukin 1β [Il1b], and Il6 mRNA and C1q protein. Inos mRNA levels were unaltered. Silver degeneration and synaptophysin staining indicated loss of synaptic innervation to CA3 pyramidal neurons. Reactive microglia with thickened bushy morphology showed co-localization of synaptophysin+ fragments. The initial response at 2 days post-TMT included transient elevations in Tnfa, Il1b, Il6, and Inos mRNA levels. A concurrent increase at 2 days was observed in arginase-1 [Arg1], Il10, transforming growth factor β1 [Tgfb1], and chitinase 3 like-3 [Ym1] mRNA levels. At 2 days, C1q protein was evident in the CA3 with elevated C1qa, C1qb, C3, Cr3a, and Cr3b mRNA levels. mRNA levels remained elevated at 5 days, returning to control by 14 days, corresponding to silver degeneration. mRNA levels for pentraxin3 (Ptx3) were elevated on day 2 and Ptx1 was not altered. Our data suggest an association between microglia reactivity, the induction of anti-inflammatory genes concurrent with pro-inflammatory genes and the expression of complement-associated factors with the degeneration of synapses following apoptotic neuronal loss. PMID:26892644

  6. Oxytocin depolarizes fast-spiking hilar interneurons and induces GABA release onto mossy cells of the rat dentate gyrus.

    Science.gov (United States)

    Harden, Scott W; Frazier, Charles J

    2016-09-01

    Delivery of exogenous oxytocin (OXT) to central oxytocin receptors (OXT-Rs) is currently being investigated as a potential treatment for conditions such as post-traumatic stress disorder (PTSD), depression, social anxiety, and autism spectrum disorder (ASD). Despite significant research implicating central OXT signaling in modulation of mood, affect, social behavior, and stress response, relatively little is known about the cellular and synaptic mechanisms underlying these complex actions, particularly in brain regions which express the OXT-R but lie outside of the hypothalamus (where OXT-synthesizing neurons reside). We report that bath application of low concentrations of the selective OXT-R agonist Thr4,Gly7-OXT (TGOT) reliably and robustly drives GABA release in the dentate gyrus in an action potential dependent manner. Additional experiments led to identification of a small subset of small hilar interneurons that are directly depolarized by acute application of TGOT. From a physiological perspective, TGOT-responsive hilar interneurons have high input resistance, rapid repolarization velocity during an action potential, and a robust afterhyperpolarization. Further, they fire irregularly (or stutter) in response to moderate depolarization, and fire quickly with minimal spike frequency accommodation in response to large current injections. From an anatomical perspective, TGOT responsive hilar interneurons have dense axonal arborizations in the hilus that were found in close proximity with mossy cell somata and/or proximal dendrites, and also invade the granule cell layer. Further, they have primary dendrites that always extend into the granule cell layer, and sometimes have clear arborizations in the molecular layer. Overall, these data reveal a novel site of action for OXT in an important limbic circuit, and represent a significant step towards better understanding how endogenous OXT may modulate flow of information in hippocampal networks. © 2016 Wiley

  7. Compressive Strength of Fibre Reinforced Concrete

    OpenAIRE

    Jelušič, Matjaž

    2009-01-01

    The thesis features an analysis of the time development of compressive strength of fibre reinforced normal and high strength concrete. Concrete mixtures, taken from the doctoral dissertation of assistant Dr Drago Saje, were used as comparable mixtures to fibre reinforced concrete mixtures with different volume shares of fibres. Two types of steel fibres were used, both featuring the same characteristics but having different lengths (16 and 30 mm), as well as polypropylene fibres. The percenta...

  8. The mechanics of fibre-reinforced sand

    OpenAIRE

    Dos Santos, APS; Consoli, NC; Baudet, BA

    2010-01-01

    Fibres can be an effective means of reinforcing soils. This paper presents data from laboratory triaxial tests on quartzitic sand reinforced with polypropylene fibres. By keeping the studied composite consistent throughout the study (host sand and fibre characteristics kept constant), it has been possible to develop a framework of behaviour for the sand-fibre material, which provides a solid base for future research on fibre-reinforced soils. Data from previous work and from new tests have be...

  9. Holey optical fibres for high nonlinearity devices

    OpenAIRE

    Belardi, Walter

    2003-01-01

    This thesis describes the development of a novel type of optical fibre, namely holey optical fibre (HF), for its specific incorporation in optical devices based on fibre nonlinearity. The development of the fabrication technique to produce such a fibre is discussed, and the fibres produced are characterized and used in device applications, proving the advantages of HF technology in the implementation of highly nonlinear optical devices, as well as showing its limitations. The initial fabricat...

  10. The Chemical Composition of Grape Fibre

    OpenAIRE

    Jolana Karovičová; Zlatica Kohajdová; Lucia Minarovičová; Veronika Kuchtová

    2015-01-01

    Dietary fibres from cereals are much more used than dietary fibres from fruits; however, dietary fibres from fruits have better quality. In recent years, for economic and environmental reasons, there has been a growing pressure to recover and exploit food wastes. Grape fibre is used to fortify baked goods, because the fibre can lower blood sugar, cut cholesterol and may even prevent colon cancer. Grape pomace is a functional ingredient in bakery goods to increase total phenolic content and di...

  11. Influence du taux de concentré sur l'ïngestibilité, la croissance pondérale et le développement corporel du mouton Djalonké "Mossi"

    OpenAIRE

    Nignan, M.; Nianogo, AJ.; Sawadogo, LL.; Bougouma-Yameogo, V.

    2000-01-01

    Effect of Dietary Concentrate Rate on Intake, Weight Gain and Body Development in Djalonke Mossi Sheep. Three levels (75 %, 50 % and 25 %) of concentrate were used to evaluate their effects on feed intake, weight gain and body development in sheep. Forty Djalonke Mossi lambs at least twenty-four (24) months old were splited in four groups. Three groups were assigned the three levels of concentrate and fed during 84 days, and the fourth was a control, with all animals slaughtered on day one of...

  12. Natural Fibre-Reinforced Biofoams

    Directory of Open Access Journals (Sweden)

    Anne Bergeret

    2011-01-01

    Full Text Available Starches and polylactic acids (PLAs represent the main biobased and biodegradable polymers with potential industrial availability in the next decades for “bio” foams applications. This paper investigates the improvement of their morphology and properties through processing and materials parameters. Starch foams were obtained by melt extrusion in which water is used as blowing agent. The incorporation of natural fibres (hemp, cellulose, cotton linter, sugarcane, coconut in the starch foam induced a density reduction up to 33%, a decrease in water absorption, and an increase in mechanical properties according to the fibre content and nature. PLA foams were obtained through single-screw extrusion using of a chemical blowing agent that decomposed at the PLA melting temperature. A void content of 48% for PLA and 25% for cellulose fibre-reinforced PLA foams and an improvement in mechanical properties were achieved. The influence of a fibre surface treatment was investigated for both foams.

  13. [Cerebellar Control of Ocular Movements: Application to the Topographical Diagnosis of Cerebellar Lesions].

    Science.gov (United States)

    Hirose, Genjiro

    2016-03-01

    Over the last decade, substantial information on cerebellar oculomotor control has been provided by the use of sophisticated neuroanatomical, neurophysiological, and imaging techniques. We now know that an intact cerebellum is a prerequisite for normal oculomotor performance. This review clarifies the current knowledge on structure-function correlations of the cerebellum in relation to ocular movements and allows them to be applied to topographical diagnosis of cerebellar lesions. The cerebellar regions most closely related to oculomotor function are: (1) the flocculus/paraflocculus for VOR suppression, cancellation, smooth pursuit eye movement and gaze-holding, (2) the nodulus/ventral uvula for velocity storage and low frequency prolonged vestibular response, and (3) the dorsal oculomotor vermis (declive VI, folium VII) and the posterior portion of the fastigial nucleus (fastigial oculomotor region) for saccades and smooth pursuit initiation. Symptomatically, defects in the flocculus/parflocculus cause saccadic pursuit, downbeat nystagmus, and impairments to visual suppression of the VOR. Lesions of the nodulus/uvula reveal as periodic alternating nystagmus. Lesions of the oculomotor vermis and the fastigial nucleus can induce saccadic dysmetria, while fastigial nucleus lesions may also cause ocular flutter/opsoclonus. A detailed knowledge of cerebellar anatomy and the physiology of eye movements enables localization of lesions to specific areas of the cerebellum. PMID:27001776

  14. Modeling of photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Barkou, Stig Eigil

    1999-01-01

    Diferent theoretical models for analysis of photonic crystal fibres are reviewed and compaired. The methods span from simple scalar approaches to full-vectorial models using different mode-field decompositions. The specific advantages of the methods are evaluated.......Diferent theoretical models for analysis of photonic crystal fibres are reviewed and compaired. The methods span from simple scalar approaches to full-vectorial models using different mode-field decompositions. The specific advantages of the methods are evaluated....

  15. Hacking a Fibre Channel network

    OpenAIRE

    Hänninen, Harri

    2013-01-01

    This thesis provides a general introduction to storage area networking, the Fibre Channel protocol and SCSI, as well as why enterprises use SAN attached storage array subsystems today. The focus is on the security of storage area networking. The objective of the thesis was to study and test in practice the possibility to eavesdrop a Fibre Channel Storage Area Network. The tests were conducted by sniffering the fiber optic cables by breaking the optical link and placing an optical splitter...

  16. The Chemical Composition of Grape Fibre

    Directory of Open Access Journals (Sweden)

    Jolana Karovičová

    2015-05-01

    Full Text Available Dietary fibres from cereals are much more used than dietary fibres from fruits; however, dietary fibres from fruits have better quality. In recent years, for economic and environmental reasons, there has been a growing pressure to recover and exploit food wastes. Grape fibre is used to fortify baked goods, because the fibre can lower blood sugar, cut cholesterol and may even prevent colon cancer. Grape pomace is a functional ingredient in bakery goods to increase total phenolic content and dietary fibre in nourishment. The aim of this study was to determine the chemical composition of commercial fibres, obtained from different Grape sources concerning their chemical properties such as moisture, ash, fat, protein, total dietary fibre. The chemical composition of Grape fibre is known to vary depending on the Grape cultivar, growth climates, and processing conditions. The obliged characteristics of the fibre product are: total dietary fibre content above 50%, moisture lower than 9%, low content of lipids, a low energy value and neutral flavour and taste. Grape pomace represents a rich source of various high-value products such as ethanol, tartrates and malates, citric acid, Grape seed oil, hydrocolloids and dietary fibre. Used commercial Grape fibres have as a main characteristic, the high content of total dietary fibre. Amount of total dietary fibre depends on the variety of Grapes. Total dietary fibre content (TDF in our samples of Grape fibre varied from 56.8% to 83.6%. There were also determined low contents of moisture (below 9%. In the samples of Grape fibre were determined higher amount of protein (8.6 - 10.8%, mineral (1.3 - 3.8% and fat (2.8 - 8.6%. This fact opens the possibility of using both initial by-products as ingredients in the food industry, due to the effects associated with the high total dietary fibre content.

  17. Acute cerebellar ataxia with human parvovirus B19 infection

    OpenAIRE

    Shimizu, Y; Ueno, T.; Komatsu, H.; Takada, H.; Nunoue, T.

    1999-01-01

    A 2 year old boy developed acute cerebellar ataxia in association with erythema infectiosum. During the disease, genomic DNA and antibodies against human parvovirus B19 were detected in serum but not in cerebrospinal fluid. Parvovirus B19 associated acute cerebellar ataxia might occur due to transient vascular reaction in the cerebellum during infection.



  18. Cerebellar involvement in metabolic disorders: a pattern-recognition approach

    International Nuclear Information System (INIS)

    Inborn errors of metabolism can affect the cerebellum during development, maturation and later during life. We have established criteria for pattern recognition of cerebellar abnormalities in metabolic disorders. The abnormalities can be divided into four major groups: cerebellar hypoplasia (CH), hyperplasia, cerebellar atrophy (CA), cerebellar white matter abnormalities (WMA) or swelling, and involvement of the dentate nuclei (DN) or cerebellar cortex. CH can be an isolated typical finding, as in adenylsuccinase deficiency, but is also occasionally seen in many other disorders. Differentiation from CH and CA is often difficult, as in carbohydrate deficient glycoprotein syndrome or 2-l-hydroxyglutaric acidaemia. In cases of atrophy the relationship of cerebellar to cerebral atrophy is important. WMA may be diffuse or patchy, frequently predominantly around the DN. Severe swelling of white matter is present during metabolic crisis in maple syrup urine disease. The DN can be affected by metabolite deposition, necrosis, calcification or demyelination. Involvement of cerebellar cortex is seen in infantile neuroaxonal dystrophy. Changes in DN and cerebellar cortex are rather typical and therefore most helpful; additional features should be sought as they are useful in narrowing down the differential diagnosis. (orig.)

  19. Pre- and Postnatal Neuroimaging of Congenital Cerebellar Abnormalities.

    Science.gov (United States)

    Poretti, Andrea; Boltshauser, Eugen; Huisman, Thierry A G M

    2016-02-01

    The human cerebellum has a protracted development that makes it vulnerable to a broad spectrum of developmental disorders including malformations and disruptions. Starting from 19 to 20 weeks of gestation, prenatal magnetic resonance imaging (MRI) can reliably study the developing cerebellum. Pre- and postnatal neuroimaging plays a key role in the diagnostic work-up of congenital cerebellar abnormalities. Diagnostic criteria for cerebellar malformations and disruptions are based mostly on neuroimaging findings. The diagnosis of a Dandy-Walker malformation is based on the presence of hypoplasia, elevation, and counterclockwise upward rotation of the cerebellar vermis and cystic dilatation of the fourth ventricle, which extends posteriorly filling out the posterior fossa. For the diagnosis of Joubert syndrome, the presence of the molar tooth sign (thickened, elongated, and horizontally orientated superior cerebellar peduncles and an abnormally deep interpeduncular fossa) is needed. The diagnostic criteria of rhombencephalosynapsis include a complete or partial absence of the cerebellar vermis and continuity of the cerebellar hemispheres across the midline. Unilateral cerebellar hypoplasia is defined by the complete aplasia or hypoplasia of one cerebellar hemisphere. Familiarity with these diagnostic criteria as well as the broad spectrum of additional neuroimaging findings is important for a correct pre- and postnatal diagnosis. A correct diagnosis is essential for management, prognosis, and counseling of the affected children and their family. PMID:26166429

  20. Reduced contralateral hemispheric flow measured by SPECT in cerebellar lesions

    DEFF Research Database (Denmark)

    Sönmezoğlu, K; Sperling, B; Henriksen, T; Tfelt-Hansen, P; Lassen, N A

    1993-01-01

    Four patients with clinical signs of cerebellar stroke were studied twice by SPECT using 99mTc-HMPAO as a tracer for cerebral blood flow (CBF). When first scanned 6 to 22 days after onset, all had a region of very low CBF in the symptomatic cerebellar hemisphere, and a mild to moderate CBF reduct...

  1. Foxc1 dependent mesenchymal signalling drives embryonic cerebellar growth

    Science.gov (United States)

    Haldipur, Parthiv; Gillies, Gwendolyn S; Janson, Olivia K; Chizhikov, Victor V; Mithal, Divakar S; Miller, Richard J; Millen, Kathleen J

    2014-01-01

    Loss of Foxc1 is associated with Dandy-Walker malformation, the most common human cerebellar malformation characterized by cerebellar hypoplasia and an enlarged posterior fossa and fourth ventricle. Although expressed in the mouse posterior fossa mesenchyme, loss of Foxc1 non-autonomously induces a rapid and devastating decrease in embryonic cerebellar ventricular zone radial glial proliferation and concurrent increase in cerebellar neuronal differentiation. Subsequent migration of cerebellar neurons is disrupted, associated with disordered radial glial morphology. In vitro, SDF1α, a direct Foxc1 target also expressed in the head mesenchyme, acts as a cerebellar radial glial mitogen and a chemoattractant for nascent Purkinje cells. Its receptor, Cxcr4, is expressed in cerebellar radial glial cells and conditional Cxcr4 ablation with Nes-Cre mimics the Foxc1−/− cerebellar phenotype. SDF1α also rescues the Foxc1−/− phenotype. Our data emphasizes that the head mesenchyme exerts a considerable influence on early embryonic brain development and its disruption contributes to neurodevelopmental disorders in humans. DOI: http://dx.doi.org/10.7554/eLife.03962.001 PMID:25513817

  2. Cerebellar glioblastoma multiforme presenting as a cerebellopontine angle mass

    Directory of Open Access Journals (Sweden)

    Anupam Jindal

    2006-01-01

    Full Text Available Cerebellar glioblastoma multiforme (GBM is a highly malignant brain tumour, which is exceedingly rare and such tumour presenting as cerebellopontine angle (CPA mass is even rarer. We here discuss the case of a 15-year-old girl who had cerebellar GBM presenting as CPA mass that resembled meningioma on CT scan and was managed successfully with minimal problems.

  3. Drug-induced cerebellar ataxia: a systematic review

    NARCIS (Netherlands)

    Gaalen, J. van; Kerstens, F.G.; Maas, R.P.P.W.M.; Harmark, L.; Warrenburg, B.P.C. van de

    2014-01-01

    BACKGROUND AND OBJECTIVES: Cerebellar ataxia can be induced by a large number of drugs. We here conducted a systemic review of the drugs that can lead to cerebellar ataxia as an adverse drug reaction (ADR). METHODS: We performed a systematic literature search in Pubmed (1966 to January 2014) and EMB

  4. A Case of Adrenoleukodystrophy Presenting as Progressive Cerebellar Dysfunction

    Directory of Open Access Journals (Sweden)

    Seunguk Jung

    2009-10-01

    Full Text Available X-linked adrenoleukodystrophy (X-ALD is a hereditary neurological disorder affecting the nervous system and adrenal cortex. The phenotype of X-ALD ranges from the rapidly progressive cerebral form to milder adrenomyeloneuropathy. However, cerebellar manifestations are rare. We report a case of adrenoleukodystrophy presenting as progressive cerebellar dysfunction resembling olivopontocerebellar degeneration, with a review of the literature

  5. Time estimation in Parkinson's disease and degenerative cerebellar disease

    NARCIS (Netherlands)

    Beudel, Martijin; Galama, Sjoukje; Leenders, Klaus L.; de Jong, Bauke M.

    2008-01-01

    With functional MRI, we recently identified fronto-cerebellar activations in predicting time to reach a target and basal ganglia activation in velocity estimation, that is, small interval assessment. We now tested these functions in patients with Parkinson's disease (PD) and degenerative cerebellar

  6. Cerebellar control of gait and interlimb coordination.

    Science.gov (United States)

    Vinueza Veloz, María Fernanda; Zhou, Kuikui; Bosman, Laurens W J; Potters, Jan-Willem; Negrello, Mario; Seepers, Robert M; Strydis, Christos; Koekkoek, Sebastiaan K E; De Zeeuw, Chris I

    2015-11-01

    Synaptic and intrinsic processing in Purkinje cells, interneurons and granule cells of the cerebellar cortex have been shown to underlie various relatively simple, single-joint, reflex types of motor learning, including eyeblink conditioning and adaptation of the vestibulo-ocular reflex. However, to what extent these processes contribute to more complex, multi-joint motor behaviors, such as locomotion performance and adaptation during obstacle crossing, is not well understood. Here, we investigated these functions using the Erasmus Ladder in cell-specific mouse mutant lines that suffer from impaired Purkinje cell output (Pcd), Purkinje cell potentiation (L7-Pp2b), molecular layer interneuron output (L7-Δγ2), and granule cell output (α6-Cacna1a). We found that locomotion performance was severely impaired with small steps and long step times in Pcd and L7-Pp2b mice, whereas it was mildly altered in L7-Δγ2 and not significantly affected in α6-Cacna1a mice. Locomotion adaptation triggered by pairing obstacle appearances with preceding tones at fixed time intervals was impaired in all four mouse lines, in that they all showed inaccurate and inconsistent adaptive walking patterns. Furthermore, all mutants exhibited altered front-hind and left-right interlimb coordination during both performance and adaptation, and inconsistent walking stepping patterns while crossing obstacles. Instead, motivation and avoidance behavior were not compromised in any of the mutants during the Erasmus Ladder task. Our findings indicate that cell type-specific abnormalities in cerebellar microcircuitry can translate into pronounced impairments in locomotion performance and adaptation as well as interlimb coordination, highlighting the general role of the cerebellar cortex in spatiotemporal control of complex multi-joint movements. PMID:25139623

  7. Cerebellar glioblastoma multiforme in an adult

    OpenAIRE

    Mattos João Paulo; Marenco Horacio Armando; Campos José Maria; Faria Andréa Vasconcellos; Queiroz Luciano de Souza; Borges Guilherme; Oliveira Evandro de

    2006-01-01

    Cerebellar glioblastoma multiforme (GBM) is a rare tumor. This is the third case published in Brazilian literature and, the last one has been described more than 15 years ago. The aggressive behavior of GBM prompts for fast treatment, which can be hampered by the fact that the diagnosis of GBM requires a high degree of suspicion. We describe a case of GBM in a 46 years old man. In conjunction, we present a literature review including particular issues, clinical data, advances in imaging studi...

  8. Cerebellar glioblastoma multiforme in an adult

    Directory of Open Access Journals (Sweden)

    Mattos João Paulo

    2006-01-01

    Full Text Available Cerebellar glioblastoma multiforme (GBM is a rare tumor. This is the third case published in Brazilian literature and, the last one has been described more than 15 years ago. The aggressive behavior of GBM prompts for fast treatment, which can be hampered by the fact that the diagnosis of GBM requires a high degree of suspicion. We describe a case of GBM in a 46 years old man. In conjunction, we present a literature review including particular issues, clinical data, advances in imaging studies, pathological characteristics, treatment options and the behavior of such malignant tumor.

  9. Strength of Concrete Containing Basalt Fibre

    Directory of Open Access Journals (Sweden)

    Parvez Imraan Ansari

    2015-04-01

    Full Text Available This paper presents the comparative study of effect of basalt fibre on compressive and split tensile strength of M40 grade concrete. The basalt fibre was mixed in concrete by (0.5%, 1%, and 1.5% of its total weight of cement in concrete. Results indicated that the strength increases with increase of basalt fibre content up to 1.0% beyond that there is a reduction in strength on increasing basalt fibre. The results show that the concrete specimen with 1.0% of basalt fibre gives better performance when it compared with 0.5%and 1.5% basalt fibre mix in concrete specimens.

  10. Practical Hydrogen Loading of Air Silica Fibres

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Jensen, Jesper Bevensee; Jensen, Jesper Bo Damm;

    2005-01-01

    A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown.......A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown....

  11. Remote cerebellar hemorrhage after lumbar spinal surgery

    Energy Technology Data Exchange (ETDEWEB)

    Cevik, Belma [Baskent University Faculty of Medicine, Department of Radiology, Fevzi Cakmak Cad. 10. sok. No: 45, Bahcelievler, Ankara 06490 (Turkey)], E-mail: belmac@baskent-ank.edu.tr; Kirbas, Ismail; Cakir, Banu; Akin, Kayihan; Teksam, Mehmet [Baskent University Faculty of Medicine, Department of Radiology, Fevzi Cakmak Cad. 10. sok. No: 45, Bahcelievler, Ankara 06490 (Turkey)

    2009-04-15

    Background: Postoperative remote cerebellar hemorrhage (RCH) as a complication of lumbar spinal surgery is an increasingly recognized clinical entity. The aim of this study was to determine the incidence of RCH after lumbar spinal surgery and to describe diagnostic imaging findings of RCH. Methods: Between October 1996 and March 2007, 2444 patients who had undergone lumbar spinal surgery were included in the study. Thirty-seven of 2444 patients were scanned by CT or MRI due to neurologic symptoms within the first 7 days of postoperative period. The data of all the patients were studied with regard to the following variables: incidence of RCH after lumbar spinal surgery, gender and age, coagulation parameters, history of previous arterial hypertension, and position of lumbar spinal surgery. Results: The retrospective study led to the identification of two patients who had RCH after lumbar spinal surgery. Of 37 patients who had neurologic symptoms, 29 patients were women and 8 patients were men. CT and MRI showed subarachnoid hemorrhage in the folia of bilateral cerebellar hemispheres in both patients with RCH. The incidence of RCH was 0.08% among patients who underwent lumbar spinal surgery. Conclusion: RCH is a rare complication of lumbar spinal surgery, self-limiting phenomenon that should not be mistaken for more ominous pathologic findings such as hemorrhagic infarction. This type of bleeding is thought to occur secondary to venous infarction, but the exact pathogenetic mechanism is unknown. CT or MRI allowed immediate diagnosis of this complication and guided conservative management.

  12. Computed tomographic features of cerebellar hemangioblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yong Lan; Ko, Young Tae; Kim, Ho Kyun [Kyung Hee University Hospital, Seoul (Korea, Republic of)

    1980-06-15

    Computed tomographic and angiographic findings of 6 proven cerebellar Hemangiotoma seen in this hospital during last 2 years were analyzed. The results were as follows: 1. Except one 14 years old female, all of them wee 37 to 48 years old males. 2. The operative findings of the tumors were 3 cystic tumors with mural nodules and 3 solid tumors. Computed tomographic findings were: 3. Of three cases of cystic cerebellar hemangiotomas, 2 cases revealed characteristic CT findings such as; a. In precontrast study, a well defined round lower density containing one isodense nodule in its periphery was seen in each case. The absorption coefficiency of each lower density was around 5 EMI unit. b. In post contrast study, the nodules were enhanced densely and homogeneously white the lower densities remain unchanged. 4. Of three cases of solid cerebella hemangiotoma, 2 cases revealed isodense mass suggested by mass effect such as displaced 4th ventricle and peripheral edema in precontrast study, while the remaining case revealed ill defined slightly high density with peripheral edema. In postcontrast study, the 2 isodense masses showed well circumscribed homogenous enhancement with central slight lower density in one of them, while high density mass revealed no enhancement at all. 5. The vertebral angiography performed in 5 cases revealed high vascular tumors with feeding arteries, draining veins and increased circulation time. 6. The tumor blushing seen in vertebral angiography was correlated to the postcontrast enhancement of solid tumors and mural nodules in cystic hemangioblastoma.

  13. Properties of hemp fibre polymer composites - An optimisation of fibre properties using novel defibration methods and fibre characterisation

    DEFF Research Database (Denmark)

    Thygesen, Anders

    2006-01-01

    obtained by steam explosion of hemp fibres prior defibrated with pectin degrading enzymes. The S2 layer in the fibre wall of the hemp fibres consisted of1-4 cellulose rich and lignin poor concentric layers constructed of ca. 100 nm thick lamellae. The microfibril angle showed values in the range 0-10° for...... the main part of the S2-layer and 70-90° for the S1-layer. The microfibrils that are mainly parallelwith the fibre axis explain the high fibre stiffness, which in defibrated hemp fibres reached 94 GPa. The defibrated hemp fibres had higher fibre stiffness (88-94 GPa) than hemp yarn (60 GPa), which the...

  14. Neural correlates of impaired emotional face recognition in cerebellar lesions.

    Science.gov (United States)

    Adamaszek, Michael; Kirkby, Kenneth C; D'Agata, Fedrico; Olbrich, Sebastian; Langner, Sönke; Steele, Christopher; Sehm, Bernhard; Busse, Stefan; Kessler, Christof; Hamm, Alfons

    2015-07-10

    Clinical and neuroimaging data indicate a cerebellar contribution to emotional processing, which may account for affective-behavioral disturbances in patients with cerebellar lesions. We studied the neurophysiology of cerebellar involvement in recognition of emotional facial expression. Participants comprised eight patients with discrete ischemic cerebellar lesions and eight control patients without any cerebrovascular stroke. Event-related potentials (ERP) were used to measure responses to faces from the Karolinska Directed Emotional Faces Database (KDEF), interspersed in a stream of images with salient contents. Images of faces augmented N170 in both groups, but increased late positive potential (LPP) only in control patients without brain lesions. Dipole analysis revealed altered activation patterns for negative emotions in patients with cerebellar lesions, including activation of the left inferior prefrontal area to images of faces showing fear, contralateral to controls. Correlation analysis indicated that lesions of cerebellar area Crus I contribute to ERP deviations. Overall, our results implicate the cerebellum in integrating emotional information at different higher order stages, suggesting distinct cerebellar contributions to the proposed large-scale cerebral network of emotional face recognition. PMID:25912431

  15. On the effect of different polymer matrix and fibre treatment on single fibre pullout test using betelnut fibres

    International Nuclear Information System (INIS)

    Research highlights: → Optimization on interfacial adhesion strength using betelnut fibres. → Using different chemical treatments and thermosetting polymer matrix. → Uniqueness of the fibre having 'trichomes' on its fibre surface. → 'Trichomes' to boost interfacial adhesion strength of fibre/matrix. -- Abstract: This study is aimed at exploring the possibility of improving the interfacial adhesion strength of betelnut fibres using different chemical treatments namely 4% and 6% of HCl and NaOH respectively. The fibre specimens were partially embedded into different thermosetting polymer matrix (polyester and epoxy) as reinforcement blocks. Single fibre pullout tests were carried out for both the untreated (Ut) and treated betelnut fibres with different resins and tested under dry conditions. Scanning electron microscopy was used to examine the material failure morphology. The studies revealed the differences of interfacial adhesion strengths for the various test specimens of betelnut fibres treated with the polyester and epoxy matrix which followed in the order of: N6 >> N4 > H4 > Ut > H6. It was proven that fibres treated with 6% of NaOH exhibits excellent interfacial adhesion properties. The interfacial adhesion shear strength of these fibres using polyester and epoxy has improved by 141% and 115% correspondingly compared to untreated fibre under the same treatment.

  16. Fusion splicing of silicon optical fibres

    OpenAIRE

    Xiao, L.M.; Healy, N; Gibson, U.; Hawkins, T.; Jones, M.; Ballato, J; A. C. Peacock

    2015-01-01

    The first splicing experiments between silicon optical fibres (SOFs) and conventional fibres are investigated. An optimized fusion splicing approach for a polycrystalline SOF is demonstrated and the material properties after splicing are characterized.

  17. Underwater Acoustic Sensing with Optical Fibres

    Directory of Open Access Journals (Sweden)

    V. V. Rampal

    1982-01-01

    Full Text Available The use of optical fibres for the detection of acoustic pressure underwater has been discussed with particular reference to the recent literature on the development of fibre optic hydrophones.

  18. Crossed cerebellar diaschisis in putaminal hemorrhage

    International Nuclear Information System (INIS)

    Metabolic depression in the contralateral cerebellar hemisphere caused by a supratentorial lesion is called crossed cerebellar diaschisis (CCD). In order to investigate diaschisis based on the location and extension of lesions, time course and prognosis, 31 patients with putaminal hemorrhage were examined by the Xe-133 clearance method (67 studies in all). They consisted of 20 males and 11 females, from 40 to 77 years old (mean: 57.1±8.9). Small hematomas (mean volume: 16.1±8.4 ml) in 18 patients were treated nonsurgically, whereas medium and large hematomas (mean volume: 57.5±29.9 ml) in 13 patients were treated by craniotomy for evacuation. rCBF was measured using a BI 1400 rCBF Analyzer and CCD was considered positive when the percentage difference in cerebellar blood flow was 10.1% (mean +2SD) greater than obtained in 21 normal controls. CCD was observed in 10 patients (55.6%) in the non-surgical group and in 9 patients (69.2%) in the surgical group. In the non-surgical group, CCD was positive in 5 of the 7 cases (71.4%) involving the posterior limb of the internal capsule and in 7 of the 11 cases (63.6%) involving the corona radiata. The surgical group was divided into three types based on the time course of CCD after surgery, i.e., type A: persistent CCD found two months later, type B: postoperative CCD had resolved two months later, and type C: no CCD observed after surgery. Mean hematoma volume was significantly greater in type A (79.0±19.8 ml) than in type B (44.6±8.5 ml) or type C (30.7±3.7 ml) (p<0.05). Type A had a poorer outcome than the other two types. In conclusion, putaminal hemorrhage induced CCD when the corticopontocerebellar pathway was involved in anatomical and/or functional change. It appeared that his pathway was irreversibly affected in patients who showed persistent CCD and poor outcome. The time course of CCD may be helpful in making a prognosis. (author)

  19. Carbon fibre material for tomorrow

    International Nuclear Information System (INIS)

    As science and technology continue to cross boundaries of known practices, materials and manufacturing techniques and into the frontiers of new materials, environment and applications, the opportunities for research in materials in general will inevitably increase. The unique properties of carbon fibre which combines low weight and high stiffness, makes it in ever greater demand as substitutes for traditional materials. This is due to the rising costs of raw materials and energy and the necessity to reduce carbon dioxide emission. The carbon fibres produced are particularly of high standard in terms of quality and processing characteristics especially when it is designed in structural components in the aerospace and defence industries. This results in a well structured organisation in producing the fibre starting from its raw material to the final composite products. In achieving this effort, research and communication of the progress takes a fundamental role. (author)

  20. Wavelength Filters in Fibre Optics

    CERN Document Server

    Venghaus, Herbert

    2006-01-01

    Wavelength filters constitute an essential element of fibre-optic networks. This book gives a comprehensive account of the principles and applications of such filters, including their technological realisation. After an introductory chapter on wavelength division multiplexing in current and future fibre optic networks follows a detailed treatment of the phase characteristics of wavelength filters, a factor frequently neglected but of significant importance at high bit rates. Subsequent chapters cover three-dimensional reflection of gratings, arrayed waveguide gratings, fibre Bragg gratings, Fabry-Perot filters, dielectric multilayer filters, ring filters, and interleavers. The book explains the relevant performance parameters, the particular advantages and shortcomings of the various concepts and components, and the preferred applications. It also includes in-depth information on the characteristics of both commercially available devices and those still at the R&D stage. All chapters are authored by inter...

  1. Variant PTA Terminating in Cerebellar Artery, Associated with Multiple Aneurysms

    Directory of Open Access Journals (Sweden)

    Yeong Uk Hwang

    2016-01-01

    Full Text Available Persistent trigeminal artery (PTA is one of the remnant fetal anastomoses between the carotid artery and basilar artery. PTAs are classified according to angiographic appearance and various connection. Among them, those directly terminating in the cerebellar arteries are rare subtype. In addition, aneurysms of the PTA are unusual in the literature and have not previously accompanied this subtype of PTA connecting cerebellar artery. We present the first case of an aneurysm of the PTA which is directly terminating in the cerebellar arteries and combined with multiple aneurysms.

  2. Variant PTA Terminating in Cerebellar Artery, Associated with Multiple Aneurysms.

    Science.gov (United States)

    Hwang, Yeong Uk; Kim, Jin Woo

    2016-01-01

    Persistent trigeminal artery (PTA) is one of the remnant fetal anastomoses between the carotid artery and basilar artery. PTAs are classified according to angiographic appearance and various connection. Among them, those directly terminating in the cerebellar arteries are rare subtype. In addition, aneurysms of the PTA are unusual in the literature and have not previously accompanied this subtype of PTA connecting cerebellar artery. We present the first case of an aneurysm of the PTA which is directly terminating in the cerebellar arteries and combined with multiple aneurysms. PMID:27446623

  3. Consensus Paper: Revisiting the Symptoms and Signs of Cerebellar Syndrome.

    Science.gov (United States)

    Bodranghien, Florian; Bastian, Amy; Casali, Carlo; Hallett, Mark; Louis, Elan D; Manto, Mario; Mariën, Peter; Nowak, Dennis A; Schmahmann, Jeremy D; Serrao, Mariano; Steiner, Katharina Marie; Strupp, Michael; Tilikete, Caroline; Timmann, Dagmar; van Dun, Kim

    2016-06-01

    The cerebellum is involved in sensorimotor operations, cognitive tasks and affective processes. Here, we revisit the concept of the cerebellar syndrome in the light of recent advances in our understanding of cerebellar operations. The key symptoms and signs of cerebellar dysfunction, often grouped under the generic term of ataxia, are discussed. Vertigo, dizziness, and imbalance are associated with lesions of the vestibulo-cerebellar, vestibulo-spinal, or cerebellar ocular motor systems. The cerebellum plays a major role in the online to long-term control of eye movements (control of calibration, reduction of eye instability, maintenance of ocular alignment). Ocular instability, nystagmus, saccadic intrusions, impaired smooth pursuit, impaired vestibulo-ocular reflex (VOR), and ocular misalignment are at the core of oculomotor cerebellar deficits. As a motor speech disorder, ataxic dysarthria is highly suggestive of cerebellar pathology. Regarding motor control of limbs, hypotonia, a- or dysdiadochokinesia, dysmetria, grasping deficits and various tremor phenomenologies are observed in cerebellar disorders to varying degrees. There is clear evidence that the cerebellum participates in force perception and proprioceptive sense during active movements. Gait is staggering with a wide base, and tandem gait is very often impaired in cerebellar disorders. In terms of cognitive and affective operations, impairments are found in executive functions, visual-spatial processing, linguistic function, and affective regulation (Schmahmann's syndrome). Nonmotor linguistic deficits including disruption of articulatory and graphomotor planning, language dynamics, verbal fluency, phonological, and semantic word retrieval, expressive and receptive syntax, and various aspects of reading and writing may be impaired after cerebellar damage. The cerebellum is organized into (a) a primary sensorimotor region in the anterior lobe and adjacent part of lobule VI, (b) a second sensorimotor

  4. Different approaches to tailoring chemical pulp fibres

    OpenAIRE

    El-Sharkawy, Khalil

    2008-01-01

    The objective of this thesis work was to examine different approaches to tailor chemical fibres of different raw materials. The focus in searching for new approaches was on pressure screen fractionation, selective treatment of each fraction, mechanical pre-treatment before refining, refiner loadability and its link to fibre properties and filling design, and on-line quality control of fibre properties. The evaluation is based on the impacts on fibre properties, filtration, refining and the re...

  5. Engineered properties in ceramized optical fibres

    OpenAIRE

    Blanc, Wilfried; Mauroy, Valérie; Ude, Michèle; Trzesien, Stanislaw; Nguyen, Van Luan; Vennegues, Philippe; Dussardier, Bernard

    2010-01-01

    DNP are observed in fibres when alkaline-earth elements (Mg, Ca and Sr) are incorporated. Mean size of the DNP, deduced from SEM pictures, depends on the composition... This last composition leads to a low loss fibre... From EDX measurements, we have observed that alkaline-earth elements and erbium ions are located inside or very close to the DNP. Fibre samples were spectroscopically analysed at room temperature. It was observed that erbium emission broadens in the DNP-doped fibres...

  6. Dietary fibre and cardiovascular health.

    Science.gov (United States)

    Sánchez-Muniz, F J

    2012-01-01

    Cardiovascular disease (CVD) is the leading cause of mortality and morbidity in developed countries. CVD is an inflammatory disease associated with risk factors that include hypercholesterolemia and hypertension. Furthermore, the evolution of this disease depends on the amount of modified lipoproteins (e.g. oxidized) present in the arterial subendothelium. Diet is considered the cornerstone for CVD treatment, as it can lower not only atherogenic lipoprotein levels and degree of oxidation, but also blood pressure, thrombogenesis and concentrations of some relevant factors (e.g. homocystein).Among different diets, the Mediterranean diet stands out due to their benefits on several health benefits, in particular with regard to CVD. Rich in vegetable foods, this diet contributes both quantitatively and qualitatively to essential fibre compounds (cellulose, hemicellulose, gums, mucilages, pectins, oligosaccharides, lignins, etc.). The present paper analyzes the effects of fibre consumption on a) cholesterol and lipoprotein levels; b) systolic and diastolic blood pressures; and c) antioxidant availability and profile. Some studies and meta-analysis are revised, as the possible mechanisms by which fibre may decrease plasma total cholesterol and LDL-cholesterol and blood pressure and to act as antioxidant, as well. In addition, author's own publications regarding the effect of fibre matrix (e.g. seaweeds) on arylesterase and the gene expression of some key antioxidant enzymes are reviewed. The paper also includes data concerning the possible interaction between fibre and some hypolipemic drugs, which may make it possible to attain similar hypolipemic effects with lower dosages, with the consequent decrease in possible side effects. The review concludes with a summary of nutritional objectives related to the consumption of carbohydrates and fibre supplements. PMID:22566302

  7. Fibre Optic Communication Key Devices

    CERN Document Server

    Grote, Norbert

    2012-01-01

    The book gives an in-depth description of the key devices of current and next generation fibre optic communication networks. In particular, the book covers devices such as semiconductor lasers, optical amplifiers, modulators, wavelength filters, and detectors but the relevant properties of optical fibres as well. The presentations include the physical principles underlying the various devices, the technologies used for the realization of the different devices, typical performance characteristics and limitations, and development trends towards more advanced components are also illustrated. Thus the scope of the book spans relevant principles, state-of-the-art implementations, the status of current research and expected future components.

  8. Investigations into fibre laser cutting

    OpenAIRE

    Hashemzadeh, Majid

    2014-01-01

    Fibre laser cutting of mild steel using oxygen and nitrogen is widely used in industries throughout the world. An IPG YLR-2000 Ytterbium fibre machine with a maximum power of 2 kW and a wavelength of 1.06 µm is used throughout this research. The effects of oxygen and nitrogen as assist gases on the feature of laser cutting process are different in terms of kerf width, surface roughness, heat affected zone and striation pattern. The kerf width in oxygen laser cutting is wider than that for nit...

  9. Portable smartphone optical fibre spectrometer

    Science.gov (United States)

    Hossain, Md. Arafat; Canning, John; Cook, Kevin; Jamalipour, Abbas

    2015-09-01

    A low cost, optical fibre based spectrometer has been developed on a smartphone platform for field-portable spectral analysis. Light of visible wavelength is collected using a multimode optical fibre and diffracted by a low cost nanoimprinted diffraction grating. A measurement range over 300 nm span (λ = 400 to 700 nm) is obtained using the smartphone CMOS chip. The spectral resolution is Δλ ~ 0.42 nm/screen pixel. A customized Android application processed the spectra on the same platform and shares with other devices. The results compare well with commercially available spectrometer.

  10. Friction and wear of human hair fibres

    Science.gov (United States)

    Bowen, James; Johnson, Simon A.; Avery, Andrew R.; Adams, Michael J.

    2016-06-01

    An experimental study of the tribological properties of hair fibres is reported, and the effect of surface treatment on the evolution of friction and wear during sliding. Specifically, orthogonally crossed fibre/fibre contacts under a compressive normal load over a series of 10 000 cycle studies are investigated. Reciprocating sliding at a velocity of 0.4 mm s‑1, over a track length of 0.8 mm, was performed at 18 °C and 40%–50% relative humidity. Hair fibres retaining their natural sebum were studied, as well as those stripped of their sebum via hexane cleaning, and hair fibres conditioned using a commercially available product. Surface topography modifications resulting from wear were imaged using scanning electron microscopy and quantified using white light interferometry. Hair fibres that presented sebum or conditioned product at the fibre/fibre junction exhibited initial coefficients of friction at least 25% lower than those that were cleaned with hexane. Coefficients of friction were observed to depend on the directionality of sliding for hexane cleaned hair fibres after sufficient wear cycles that cuticle lifting was present, typically on the order 1000 cycles. Cuticle flattening was observed for fibre/fibre junctions exposed to 10 mN compressive normal loads, whereas loads of 100 mN introduced substantial cuticle wear and fibre damage.

  11. Miniature multi-turn fibre current sensors

    OpenAIRE

    Li, L.; Qian, J.R.; Payne, D. N.

    1987-01-01

    Highly birefringent Bow-Tie fibres can be sensitized to Faraday rotation by spinning the fibres during draw. The fibres become elliptically-birefringent and this permits multi-turn small-diameter coil to be wound without loss of current sensitivity.

  12. Hereditary Cerebellar Ataxias: A Korean Perspective

    Directory of Open Access Journals (Sweden)

    Ji Sun Kim

    2015-05-01

    Full Text Available Hereditary ataxia is a heterogeneous disorder characterized by progressive ataxia combined with/without peripheral neuropathy, extrapyramidal symptoms, pyramidal symptoms, seizure, and multiple systematic involvements. More than 35 autosomal dominant cerebellar ataxias have been designated as spinocerebellar ataxia, and there are 55 recessive ataxias that have not been named systematically. Conducting genetic sequencing to confirm a diagnosis is difficult due to the large amount of subtypes with phenotypic overlap. The prevalence of hereditary ataxia can vary among countries, and estimations of prevalence and subtype frequencies are necessary for planning a diagnostic strategy in a specific population. This review covers the various hereditary ataxias reported in the Korean population with a focus on the prevalence and subtype frequencies as the clinical characteristics of the various subtypes.

  13. Weibull statistics of bamboo fibre bundles: methodology for tensile testing of natural fibres

    OpenAIRE

    Trujillo De Los Rios, Efrain Eduardo; Moesen, Maarten; Osorio Serna, Lina Rocío; Van Vuure, Aart Willem; Ivens, Jan; Verpoest, Ignace

    2012-01-01

    In order to characterize bamboo (Guadua angustifolia) fibres mechanically, single fibre (SFT), dry fibre bundle (DFB) and impregnated bundle (IFB) tests were performed. It was found that the strength of the fibres follows a Weibull distribution, furthermore showing that the variability of the material (obtained from the shape parameter m=8.3) is relatively low. The tensile strength of the fibres was around 800 MPa (SFT). In order to determine experimentally the two Weibull parameters from loa...

  14. Microstructure and Mechanical Properties of Aligned Natural Fibre Composites

    DEFF Research Database (Denmark)

    Rask, Morten

    expected based on tests of single fibres. 3) Compared to continuous glass fibres, natural fibres are relatively short, which makes it difficult to achieve an optimized fibre architecture. 4) Natural fibres are hydrophilic, meaning that they do not bond well with standard polymer matrix systems, most of...... failure. Since individual natural fibres are relatively short (50-70mm), they are traditionally spun into fibre yarns in order to be able to handle the fibres. However, spinning the fibres effectively equates to introducing a large amount of fibre misalignment, which decreases the composite stiffness...

  15. Cerebellar blood flow in methylmercury poisoning (Minamata disease)

    International Nuclear Information System (INIS)

    We looked at regional cerebellar blood flow in patients with Minamata disease (MD) using technetium-99 m ethyl cysteinate dimer (99m-Tc-ECD). We carried out single-photon emission computed tomography (SPECT) on 15 patients with MD (eight men, seven women, aged 51-78 years, mean 70.5 years) and 11 control subjects (eight men, three women, aged 62-80 years, mean 72.5 years). Regional blood flow was measured in the superior, middle, and inferior portions of the cerebellar hemispheres, and the frontal, temporal and occipital cerebral lobes. The degree of cerebellar atrophy was assessed on MRI. There were significant differences in regional blood flow in all parts of the cerebellum between patients and control, but no significant decrease was observed in the cerebrum. Blood flow was lower in the inferior cerebellum than in the other parts. Even in patients without cerebellar atrophy, flow was significantly decreased regional blood flow in the inferior part. (orig.)

  16. Anomalous Cerebellar Anatomy in Chinese Children with Dyslexia.

    Science.gov (United States)

    Yang, Ying-Hui; Yang, Yang; Chen, Bao-Guo; Zhang, Yi-Wei; Bi, Hong-Yan

    2016-01-01

    The cerebellar deficit hypothesis for developmental dyslexia claims that cerebellar dysfunction causes the failures in the acquisition of visuomotor skills and automatic reading and writing skills. In people with dyslexia in the alphabetic languages, the abnormal activation and structure of the right or bilateral cerebellar lobes have been identified. Using a typical implicit motor learning task, however, one neuroimaging study demonstrated the left cerebellar dysfunction in Chinese children with dyslexia. In the present study, using voxel-based morphometry, we found decreased gray matter volume in the left cerebellum in Chinese children with dyslexia relative to age-matched controls. The positive correlation between reading performance and regional gray matter volume suggests that the abnormal structure in the left cerebellum is responsible for reading disability in Chinese children with dyslexia. PMID:27047403

  17. Cerebellar infarct patterns: The SMART-Medea study

    Directory of Open Access Journals (Sweden)

    Laurens J.L. De Cocker, MD

    2015-01-01

    Conclusions: Small cerebellar infarcts proved to be much more common than larger infarcts, and preferentially involved the cortex. Small cortical infarcts predominantly involved the posterior lobes, showed sparing of subcortical white matter and occurred in characteristic topographic patterns.

  18. Cerebellar giant cell glioblastoma multiforme in an adult

    Directory of Open Access Journals (Sweden)

    Sudhansu Sekhar Mishra

    2014-01-01

    Full Text Available Cerebellar glioblastoma multiforme (GBM is a rare tumor that accounts for only 1% of all cases of GBM and its giant cell variant is even much rarely encountered in adults. A case of cerebellar giant cell GBM managed at our institution reporting its clinical presentation, radiological and histological findings, and treatment instituted is described. In conjunction, a literature review, including particular issues, clinical data, advances in imaging studies, pathological characteristics, treatment options, and the behavior of such malignant tumor is presented. It is very important for the neurosurgeon to make the differential diagnosis between the cerebellar GBM, and other diseases such as metastasis, anaplastic astrocytomas, and cerebellar infarct because their treatment modalities, prognosis, and outcome are different.

  19. Anomalous Cerebellar Anatomy in Chinese Children with Dyslexia

    Science.gov (United States)

    Yang, Yang; Chen, Bao-Guo; Zhang, Yi-Wei; Bi, Hong-Yan

    2016-01-01

    The cerebellar deficit hypothesis for developmental dyslexia claims that cerebellar dysfunction causes the failures in the acquisition of visuomotor skills and automatic reading and writing skills. In people with dyslexia in the alphabetic languages, the abnormal activation and structure of the right or bilateral cerebellar lobes have been identified. Using a typical implicit motor learning task, however, one neuroimaging study demonstrated the left cerebellar dysfunction in Chinese children with dyslexia. In the present study, using voxel-based morphometry, we found decreased gray matter volume in the left cerebellum in Chinese children with dyslexia relative to age-matched controls. The positive correlation between reading performance and regional gray matter volume suggests that the abnormal structure in the left cerebellum is responsible for reading disability in Chinese children with dyslexia. PMID:27047403

  20. Anomalous cerebellar anatomy in Chinese children with dyslexia

    Directory of Open Access Journals (Sweden)

    Ying-Hui eYang

    2016-03-01

    Full Text Available The cerebellar deficit hypothesis for developmental dyslexia (DD claims that cerebellar dysfunction causes the failures in the acquisition of visuomotor skills and automatic reading and writing skills. In people with dyslexia in the alphabetic languages, the abnormal activation and structure of the right or bilateral cerebellar lobes have been identified. Using a typical implicit motor learning task, however, one neuroimaging study demonstrated the left cerebellar dysfunction in Chinese children with dyslexia. In the present study, using voxel-based morphometry, we found decreased gray matter volume in the left cerebellum in Chinese children with dyslexia relative to age-matched controls. The positive correlation between reading performance and regional gray matter volume suggests that the abnormal structure in the left cerebellum is responsible for reading disability in Chinese children with dyslexia.

  1. Bilateral cerebellar activation in unilaterally challenged essential tremor

    Directory of Open Access Journals (Sweden)

    Marja Broersma

    2016-01-01

    Conclusions: Our results expand on previous findings of bilateral cerebellar involvement in ET. We have identified specific areas in the bilateral somatomotor regions of the cerebellum: lobules V, VI and VIII.

  2. Cerebellar Hemangioblastoma and Von Hippel-Lindau Disease

    Directory of Open Access Journals (Sweden)

    J. Gordon Millichap

    2002-02-01

    Full Text Available Six pediatric patients with cerebellar hemangioblastoma were screened for germline or somatic mutations of the von Hippel-Landau gene, in a study at Stanford University Medical Center, Palo Alto, CA.

  3. Adult-onset cerebellar Ataxia: a clinical and genetic Survey

    NARCIS (Netherlands)

    E. Brusse (Esther)

    2011-01-01

    textabstractCerebellar ataxias represent a heterogeneous group of neurodegenerative disorders. Two main categories are distinguished: hereditary and sporadic ataxias. Sporadic ataxias may be symptomatic or idiopathic. The clinical classification of hereditary ataxias is nowadays being replaced by an

  4. Unilateral absence of cerebellar hemisphere: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Erdogan, N.; Ozturk, O. [Department of Radiology, Erciyes University Faculty of Medicine, Kayseri (Turkey); Kocakoc, E. [Department of Radiology, Women' s Hospital, Sivas (Turkey); Bekar, D. [Department of Neurology, City Hospital, Sivas (Turkey)

    2002-01-01

    We describe a 38-year-old woman with absence of right cerebellar hemisphere incidentally discovered by MR imaging. No cerebellar abnormality was detected on neurological examination. Tissue probably representing dysgenetic cerebellar tissue with no corticomedullary differentiation was present, connected to the right superior cerebellar peduncle. Ipsilateral enlargement of the pons and cerebral peduncle were additional findings. Although the terms ''aplasia'' or ''agenesis'' have been used to describe this entity, intrauterine destruction is the presumed pathogenetic mechanism in our case, and therefore these terms have been avoided. Asymmetry of pons and mesencephalon may be related to compensatory reorganisation or to the impairment of sequential development of nuclei and neural tracts. (orig.)

  5. Prenatal exposure to alcohol does not affect radial maze learning and hippocampal mossy fiber sizes in three inbred strains of mouse

    Directory of Open Access Journals (Sweden)

    Bertholet Jean-Yves

    2005-04-01

    Full Text Available Abstract Background The aim of this study was to investigate the effects of prenatal alcohol exposure on radial-maze learning and hippocampal neuroanatomy, particularly the sizes of the intra- and infrapyramidal mossy fiber (IIPMF terminal fields, in three inbred strains of mice (C57BL/6J, BALB/cJ, and DBA/2J. Results Although we anticipated a modification of both learning and IIPMF sizes, no such effects were detected. Prenatal alcohol exposure did, however, interfere with reproduction in C57BL/6J animals and decrease body and brain weight (in interaction with the genotype at adult age. Conclusion Prenatal alcohol exposure influenced neither radial maze performance nor the sizes of the IIPMF terminal fields. We believe that future research should be pointed either at different targets when using mouse models for Fetal Alcohol Syndrome (e.g. more complicated behavioral paradigms, different hippocampal substructures, or other brain structures or involve different animal models.

  6. An MRI Study of Cerebellar Volume in Tuberous Sclerosis Complex

    OpenAIRE

    Weisenfeld, Neil I.; Peters, Jurriaan M.; Tsai, Peter T; Prabhu, Sanjay P.; Dies, Kira A.; Sahin, Mustafa; Warfield, Simon K.

    2013-01-01

    The cerebellum plays an important role in motor learning and cognition, and structural cerebellar abnormalities have been associated with cognitive impairment. In tuberous sclerosis complex, neurological outcome is highly variable, and no consistent imaging or pathological determinant of cognition has been firmly established. The cerebellum calls for specific attention as mouse models of tuberous sclerosis complex have demonstrated a loss of cerebellar Purkinje cells and cases of human histol...

  7. Anticipatory cerebellar responses during somatosensory omission in man.

    Science.gov (United States)

    Tesche, C D; Karhu, J J

    2000-03-01

    The traditional view of cerebellum is a structure that modifies and synchronizes elements of motor performance. Recent evidence indicates that human cerebellum is involved in a wide range of nonmotor sensory and cognitive functions. A common feature in these diverse motor and nonmotor tasks may be the capacity of cerebellar neuronal circuits to process and anticipate sensory input with high temporal acuity. We present evidence supporting this hypothesis from measurements of the magnetic field at the scalp evoked by neuronal population activity in human cerebellum. Intermittent electrical stimulation of the finger and the median nerve elicited stimulus-locked cerebellar responses with oscillatory components at 6-12 Hz and 25-35 Hz. Sustained oscillatory activity followed random stimulus omissions, with initiation of cerebellar responses prior to the next overt stimulus. These responses indexed processing of temporal features of somatosensory input independent of motor performance or response. The refractory behavior of the responses suggested that a neuronal trace of the temporal pattern of somatosensory stimulation remained in cerebellar circuits for 2-4 s. The cerebellar activity elicited by violation of an established temporal pattern was enhanced when attention was directed to somatosensory stimuli, in concordance with recent imaging studies suggesting participation of cerebellum in attentional networks. The attentional enhancement of the cerebellar responses supports the salience of cerebellar activity in the processing of purely somatosensory input. The short-term maintenance of cerebellar templates for predictable sensory input may reflect a physiological substrate for fine-grained temporal tuning and optimization of performance in large-scale sensory and integrative systems. PMID:10739364

  8. Deep Learning for Cerebellar Ataxia Classification and Functional Score Regression

    OpenAIRE

    Yang, Zhen; Zhong, Shenghua; Carass, Aaron; Ying, Sarah H.; Prince, Jerry L.

    2014-01-01

    Cerebellar ataxia is a progressive neuro-degenerative disease that has multiple genetic versions, each with a characteristic pattern of anatomical degeneration that yields distinctive motor and cognitive problems. Studying this pattern of degeneration can help with the diagnosis of disease subtypes, evaluation of disease stage, and treatment planning. In this work, we propose a learning framework using MR image data for discriminating a set of cerebellar ataxia types and predicting a disease ...

  9. Cerebellar contributions to neurological soft signs in healthy young adults.

    Science.gov (United States)

    Hirjak, Dusan; Thomann, Philipp A; Kubera, Katharina M; Stieltjes, Bram; Wolf, Robert C

    2016-02-01

    Neurological soft signs (NSS) are frequently found in psychiatric disorders of significant neurodevelopmental origin, e.g., in patients with schizophrenia and autism. Yet NSS are also present in healthy individuals suggesting a neurodevelopmental signature of motor function, probably as a continuum between health and disease. So far, little is known about the neural mechanisms underlying these motor phenomena in healthy persons, and it is even less known whether the cerebellum contributes to NSS expression. Thirty-seven healthy young adults (mean age = 23 years) were studied using high-resolution structural magnetic resonance imaging (MRI) and "resting-state" functional MRI at three Tesla. NSS levels were measured using the "Heidelberg Scale." Cerebellar gray matter volume was investigated using cerebellum-optimized voxel-based analysis methods. Cerebellar function was assessed using regional homogeneity (ReHo), a measure of local network strength. The relationship between cerebellar structure and function and NSS was analyzed using regression models. There was no significant relationship between cerebellar volume and NSS (p < 0.005, uncorrected for height, p < 0.05 corrected for spatial extent). Positive associations with cerebellar lobule VI activity were found for the "motor coordination" and "hard signs" NSS domains. A negative relationship was found between lobule VI activity and "complex motor task" domain (p < 0.005, uncorrected for height, p < 0.05 corrected for spatial extent). The data indicate that in healthy young adults, distinct NSS domains are related to cerebellar activity, specifically with activity of cerebellar subregions with known cortical somatomotor projections. In contrast, cerebellar volume is not predictive of NSS in healthy persons. PMID:25708455

  10. Oxidative Stress in Autism: Elevated Cerebellar 3-nitrotyrosine Levels

    Directory of Open Access Journals (Sweden)

    Elizabeth M. Sajdel-Sulkowska

    2008-01-01

    Full Text Available It has been suggested that oxidative stress and/or mercury compounds play an important role in the pathophysiology of autism. This study compared for the first time the cerebellar levels of the oxidative stress marker 3-nitrotyrosine (3-NT, mercury (Hg and the antioxidant selenium (Se levels between control and autistic subjects. Tissue homogenates were prepared in the presence of protease inhibitors from the frozen cerebellar tissue of control (n=10; mean age, 15.5 years; mean PMI, 15.5 hours and autistic (n=9; mean age 12.1 years; mean PMI, 19.3 hours subjects. The concentration of cerebellar 3-NT, determined by ELISA, in controls ranged from 13.69 to 49.04 pmol g-1 of tissue; the concentration of 3-NT in autistic cases ranged from 3.91 to 333.03 pmol g-1 of tissue. Mean cerebellar 3-NT was elevated in autism by 68.9% and the increase was statistically significant (p=0.045. Cerebellar Hg, measured by atomic absorption spectrometry ranged from 0.9 to 35 pmol g-1 tissue in controls (n=10 and from 3.2 to 80.7 pmol g-1 tissue in autistic cases (n=9; the 68.2% increase in cerebellar Hg was not statistically significant. However, there was a positive correlation between cerebellar 3-NT and Hg levels (r=0.7961, p=0.0001. A small decrease in cerebellar Se levels in autism, measured by atomic absorption spectroscopy, was not statistically significant but was accompanied by a 42.9% reduction in the molar ratio of Se to Hg in the autistic cerebellum. While preliminary, the results of the present study add elevated oxidative stress markers in brain to the growing body of data reflecting greater oxidative stress in autism.

  11. Cerebellar Neuroblastoma in 2.5 Years Old Child

    OpenAIRE

    Pedram, Mohammad; Vafaie, Majid; Fekri, Kiavash; Haghi, Sabahat; Rashidi, Iran; Pirooti, Chia

    2013-01-01

    Neuroblastoma is the third most common malignancy of childhood, after leukemia and brain tumors. Only 2% of all neuroblastoma occur in the brain. Primary cerebellar neuroblastoma is an specific subset of Primitive Neuroectodermal Tumors (PNET). Meduloblastoma is a relatively common and well-established entity, consisting of primitive and multipotential cells that may exhibit some evidence of neuroblastic or gliad differentiation. But cerebellar neuroblastoma with ultrastractural evidence of s...

  12. Cerebellar medulloblastoma in a 65 year old Indian male.

    Directory of Open Access Journals (Sweden)

    Jaiswal A

    2000-04-01

    Full Text Available A case of cerebellar medulloblastoma in a 65 year old male is reported. Cerebellar medulloblastoma is classically seen during childhood, and less than 25% of these tumours are found in adults below 40 years of age. Rarely, cases are reported above the age of 40 years. So far only three cases have been reported in patients aged above 64 years and none of these case reports are from India.

  13. The Clinical Differentiation of Cerebellar Infarction from Common Vertigo Syndromes

    OpenAIRE

    Nelson, James A.; Viirre, Erik

    2009-01-01

    This article summarizes the emergency department approach to diagnosing cerebellar infarction in the patient presenting with vertigo. Vertigo is defined and identification of a vertigo syndrome is discussed. The differentiation of common vertigo syndromes such as benign paroxysmal positional vertigo, Meniere’s disease, migrainous vertigo, and vestibular neuritis is summarized. Confirmation of a peripheral vertigo syndrome substantially lowers the likelihood of cerebellar infarction, as do ind...

  14. A PHOTONIC BAND GAP FIBRE

    DEFF Research Database (Denmark)

    1999-01-01

    An optical fibre having a periodicidal cladding structure provididing a photonic band gap structure with superior qualities. The periodical structure being one wherein high index areas are defined and wherein these are separated using a number of methods. One such method is the introduction of...

  15. Cool application for Optical Fibres

    CERN Multimedia

    2001-01-01

    In a new first for CERN, optical fibres have been put on test to measure very low temperatures. If these tests prove successful, this new technology could lead to important cost-saving changes in the way the temperatures of superconducting magnets are measured. There was excitement in the air last March when the team led by Walter Scandale and Luc Thévenaz tested very low temperature measurement using optical fibres. This spring in CERN's Cryogenics lab an idea was put to the test as a new kind of low-temperature thermometry using optical fibres was tested down to 2 Kelvin (around 300 degrees below room temperature), and the first results are looking good. Optical fibres are well known for their ability to carry large amounts of data around the world, but it is less well known that they can be used for measuring temperatures. The intuition that they might be able to measure very low temperatures - such as those of the LHC magnets - came to the attention of CERN's Walter Scandale at the Optical Fi...

  16. Transplantation and Stem Cell Therapy for Cerebellar Degenerations.

    Science.gov (United States)

    Cendelin, Jan

    2016-02-01

    Stem cell-based and regenerative therapy may become a hopeful treatment for neurodegenerative diseases including hereditary cerebellar degenerations. Neurotransplantation therapy mainly aims to substitute lost cells, but potential effects might include various mechanisms including nonspecific trophic effects and stimulation of endogenous regenerative processes and neural plasticity. Nevertheless, currently, there remain serious limitations. There is a wide spectrum of human hereditary cerebellar degenerations as well as numerous cerebellar mutant mouse strains that serve as models for the development of effective therapy. By now, transplantation has been shown to ameliorate cerebellar function, e.g. in Purkinje cell degeneration mice, Lurcher mutant mice and mouse models of spinocerebellar ataxia type 1 and type 2 and Niemann-Pick disease type C. Despite the lack of direct comparative studies, it appears that there might be differences in graft development and functioning between various types of cerebellar degeneration. Investigation of the relation of graft development to specific morphological, microvascular or biochemical features of the diseased host tissue in various cerebellar degenerations may help to identify factors determining the fate of grafted cells and potential of their functional integration. PMID:26155762

  17. Voltage-gated calcium channel autoimmune cerebellar degeneration

    Science.gov (United States)

    McKasson, Marilyn; Clawson, Susan A.; Hill, Kenneth E.; Wood, Blair; Carlson, Noel; Bromberg, Mark; Greenlee, John E.

    2016-01-01

    Objectives: To describe response to treatment in a patient with autoantibodies against voltage-gated calcium channels (VGCCs) who presented with autoimmune cerebellar degeneration and subsequently developed Lambert-Eaton myasthenic syndrome (LEMS), and to study the effect of the patient's autoantibodies on Purkinje cells in rat cerebellar slice cultures. Methods: Case report and study of rat cerebellar slice cultures incubated with patient VGCC autoantibodies. Results: A 53-year-old man developed progressive incoordination with ataxic speech. Laboratory evaluation revealed VGCC autoantibodies without other antineuronal autoantibodies. Whole-body PET scans 6 and 12 months after presentation detected no malignancy. The patient improved significantly with IV immunoglobulin G (IgG), prednisone, and mycophenolate mofetil, but worsened after IV IgG was halted secondary to aseptic meningitis. He subsequently developed weakness with electrodiagnostic evidence of LEMS. The patient's IgG bound to Purkinje cells in rat cerebellar slice cultures, followed by neuronal death. Reactivity of the patient's autoantibodies with VGCCs was confirmed by blocking studies with defined VGCC antibodies. Conclusions: Autoimmune cerebellar degeneration associated with VGCC autoantibodies may precede onset of LEMS and may improve with immunosuppressive treatment. Binding of anti-VGCC antibodies to Purkinje cells in cerebellar slice cultures may be followed by cell death. Patients with anti-VGCC autoantibodies may be at risk of irreversible neurologic injury over time, and treatment should be initiated early. PMID:27088118

  18. Verbal Memory Impairments in Children after Cerebellar Tumor Resection

    Directory of Open Access Journals (Sweden)

    Matthew P. Kirschen

    2008-01-01

    Full Text Available This study was designed to investigate cerebellar lobular contributions to specific cognitive deficits observed after cerebellar tumor resection. Verbal working memory (VWM tasks were administered to children following surgical resection of cerebellar pilocytic astrocytomas and age-matched controls. Anatomical MRI scans were used to quantify the extent of cerebellar lobular damage from each patient's resection. Patients exhibited significantly reduced digit span for auditory but not visual stimuli, relative to controls, and damage to left hemispheral lobule VIII was significantly correlated with this deficit. Patients also showed reduced effects of articulatory suppression and this was correlated with damage to the vermis and hemispheral lobule IV/V bilaterally. Phonological similarity and recency effects did not differ overall between patients and controls, but outlier patients with abnormal phonological similarity effects to either auditory or visual stimuli were found to have damage to hemispheral lobule VIII/VIIB on the left and right, respectively. We postulate that damage to left hemispheral lobule VIII may interfere with encoding of auditory stimuli into the phonological store. These data corroborate neuroimaging studies showing focal cerebellar activation during VWM paradigms, and thereby allow us to predict with greater accuracy which specific neurocognitive processes will be affected by a cerebellar tumor resection.

  19. Abnormal cerebellar volume in acute and remitted major depression.

    Science.gov (United States)

    Depping, Malte S; Wolf, Nadine D; Vasic, Nenad; Sambataro, Fabio; Hirjak, Dusan; Thomann, Philipp A; Wolf, Robert C

    2016-11-01

    Abnormal cortical volume is well-documented in patients with major depressive disorder (MDD), but cerebellar findings have been heterogeneous. It is unclear whether abnormal cerebellar structure relates to disease state or medication. In this study, using structural MRI, we investigated cerebellar volume in clinically acute (with and without psychotropic treatment) and remitted MDD patients. High-resolution structural MRI data at 3T were obtained from acute medicated (n=29), acute unmedicated (n=14) and remitted patients (n=16). Data from 29 healthy controls were used for comparison purposes. Cerebellar volume was investigated using cerebellum-optimized voxel-based analysis methods. Patients with an acute MDD episode showed increased volume of left cerebellar area IX, and this was true for both medicated and unmedicated individuals (pbrain functional network with known relevance to core depressive symptom expression, exhibits abnormal volume in patients independent of clinical severity or medication. Thus, the data imply a possible trait marker of the disorder. However, given bilaterality and an association with clinical scores at least in remitted patients, the current findings raise the possibility that cerebellar volume may be reflective of successful treatment as well. PMID:27321187

  20. Oxidative injury in multiple sclerosis cerebellar grey matter.

    Science.gov (United States)

    Kemp, Kevin; Redondo, Juliana; Hares, Kelly; Rice, Claire; Scolding, Neil; Wilkins, Alastair

    2016-07-01

    Cerebellar dysfunction is a significant contributor to disability in multiple sclerosis (MS). Both white matter (WM) and grey matter (GM) injury occurs within MS cerebellum and, within GM, demyelination, inflammatory cell infiltration and neuronal injury contribute to on-going pathology. The precise nature of cerebellar GM injury is, however, unknown. Oxidative stress pathways with ultimate lipid peroxidation and cell membrane injury occur extensively in MS and the purpose of this study was to investigate these processes in MS cerebellar GM. Post-mortem human cerebellar GM from MS and control subjects was analysed immunohistochemically, followed by semi-quantitative analysis of markers of cellular injury, lipid peroxidation and anti-oxidant enzyme expression. We have shown evidence for reduction in myelin and neuronal markers in MS GM, coupled to an increase in expression of a microglial marker. We also show that the lipid peroxidation product 4-hydroxynonenal co-localises with myelin and its levels negatively correlate to myelin basic protein levels. Furthermore, superoxide dismutase (SOD1 and 2) enzymes, localised within cerebellar neurons, are up-regulated, yet the activation of subsequent enzymes responsible for the detoxification of hydrogen peroxide, catalase and glutathione peroxidase are relatively deficient. These studies provide evidence for oxidative injury in MS cerebellar GM and further help define disease mechanisms within the MS brain. PMID:27086975

  1. Optical fibre laser velocimetry: a review

    International Nuclear Information System (INIS)

    The applications of optical fibre technology to laser velocimetry are diverse and often critical to their successful implementation, particularly in harsh environments. Applications range from the use of optical fibres for beam delivery and scattered light collection, aiding the miniaturization of instrument probes, to the use of imaging fibre bundles for imaging the flow field in planar velocimetry systems. Optical fibre techniques have also been used in signal processing, for example fibre frequency shifters, and optical fibre devices such as amplifiers and lasers have been exploited. This paper will review the use of optical fibres in point-wise laser velocimetry techniques such as laser Doppler velocimetry and laser transit anemometry, as well as in planar measurement techniques such as particle imaging velocimetry and planar Doppler velocimetry. (topical review)

  2. Relationship between the cerebellar function and cerebellar atrophy in Minamata disease. Investigations using body balance analyzer and MR imaging method

    Energy Technology Data Exchange (ETDEWEB)

    Okajima, Toru [Johnan Hospital, Minami, Kumamoto (Japan); Ikeda, Osamu; Sannomiya, Kunihiro; Korogi, Yukinori; Uchino, Makoto

    1995-11-01

    Interrelations between the cerebellar function and cerebellar atrophy were studied in the cases with Minamata disease and spinocerebellar degeneration and in the healthy subjects. For evaluation of the cerebellar function, the statokinesigraph (SKG) was recorded and the shifting length (L-SKG) and moving area (A-SKG) of postural sway were obtained using body balance analyzer. Cerebellar atrophy was evaluated by the rostrocaudal and ventrodorsal diameters of whole vermis and the total area of upper and lower parts (area-UL) of vermis on the midsagittal plane of MR imaging. It was disclosed that there was significant correlation between the L-SKG and the measurement of rostrocaudal diameter as well as the area-UL of vermis through the patients with Minamata disease and the healthy subjects. When added the patients with spinocerebellar degeneration, the significant correlation was not obtainable probably because of the progressive processes of the disease. (author).

  3. A case of subacute cerebellar degeneration associated with pleocytosis and cerebellar swelling shown in computed tomography scanning

    International Nuclear Information System (INIS)

    A 44 year old woman was healthy until January 3, 1986, when she had headache. On January 9, she developed gait ataxia and dysarthria. Cerebellar ataxia worsened rapidly. Aftar a week she could not sit without support and her consciousness was disturbed. Corticosteroid was administrated and consciousness proved alert, but cerebellar ataxia and dysarthria remained unchanged. The patient was found carcinoma of the lung in August 1986. Characteristic features of clinical and laboratory findings of this patient are acute progression, cerebrospinal fluid pleocytosis of 1,064/3 cells (860 mononuclear cell, 204 polymorphonuclear cell), and cerebellar swelling shown in computed tomography scanning. Though the mechanism of acute cerebellar degeneration is still uncertained, inflammatory process was supported to exist in cerebellum of this case. (author)

  4. Characterisation of Flax Fibres and Flax Fibre Composites. Being cellulose based sources of materials

    DEFF Research Database (Denmark)

    Aslan, Mustafa

    growing interest among composite manufacturers for such low-cost and low-weight cellulosic fibre composites. In addition, wood and plant fibre based composites with thermoplastic polymeric matrices are recyclable, and they are cost attractive alternatives to oil based fibre reinforced polymer composites......Cellulosic fibres, like wood and plant fibres, have the potential for use as load-bearing constituents in composite materials due to their attractive properties such as high stiffness-to-weight ratio that makes cellulosic fibre composites ideal for many structural applications. There is thus a...... that currently have the largest market share for composite applications. However, the most critical limitation in the use of cellulosic fibre composites for structural applications is the lack of well described fibre properties, in particular, the tensile strength. This is due to variations in fibre...

  5. Cerebellar control of postural scaling and central set in stance.

    Science.gov (United States)

    Horak, F B; Diener, H C

    1994-08-01

    1. The effects of cerebellar deficits in humans on scaling the magnitude of automatic postural responses based on sensory feedback and on predictive central set was investigated. Electromyographic (EMG) and surface reactive torques were compared in patients with anterior lobe cerebellar disorders and in normal healthy adults exposed to blocks of four velocities and five amplitudes of surface translations during stance. Correlations between the earliest postural responses (integrated EMG and initial rate of change of torque) and translation velocity provided a measure of postural magnitude scaling using sensory information from the current displacement. Correlations of responses with translation amplitude provided a measure of scaling dependent on predictive central set based on sequential experience with previous like displacements because the earliest postural responses occurred before completion of the displacements and because scaling to displacement amplitude disappeared when amplitudes were randomized in normal subjects. 2. Responses of cerebellar patients to forward body sway induced by backward surface displacements were hypermetric, that is, surface-reactive torque responses were two to three times larger than normal with longer muscle bursts resulting in overshooting of initial posture. Despite this postural hypermetria, the absolute and relative latencies of agonist muscle bursts at the ankle, knee, and hip were normal in cerebellar patients. 3. Although they were hypermetric, the earliest postural responses of cerebellar patients were scaled normally to platform displacement velocities using somatosensory feedback. Cerebellar patients, however, were unable to scale initial postural response magnitude to expected displacement amplitudes based on prior experience using central set. Randomization of displacement amplitudes eliminated the set effect of amplitude on initial responses in normal subjects, but responses to randomized and blocked trials were not

  6. Lack of Kinase Regulation of Canonical Transient Receptor Potential 3 (TRPC3) Channel-dependent Currents in Cerebellar Purkinje Cells

    OpenAIRE

    Nelson, Charmaine; Glitsch, Maike D.

    2011-01-01

    Background: TRPC3 channels are inhibited by PKC and PKG, which also induce cerebellar LTD. We investigate if PKC- and PKG-mediated modulation of cerebellar TRPC3 channels contributes to cerebellar LTD.

  7. Modulational instability in a fibre and a fibre Bragg grating

    International Nuclear Information System (INIS)

    In this review article, we study the influence of cross-phase modulation, higher order nonlinear effects such as self-steepening, self-induced Raman scattering and higher order dispersion effects such as third and fourth order dispersion on cross-phase modulational instability for a highly elliptical birefringent optical fibre, and obtain the conditions for the occurrence of cross-phase modulational instability in the normal dispersion regime. In addition, we also consider the pulse propagation through a fibre Bragg grating structure where we investigate the occurrence of modulational instability at the two edges of the photonic bandgap as well as on the upper and lower branches of the dispersion curves. (review article)

  8. Comparison of Acoustic Characteristics of Date Palm Fibre and Oil Palm Fibre

    OpenAIRE

    Lamyaa Abd ALRahman; Raja Ishak Raja; Roslan Abdul Rahman; Zawawi Ibrahim

    2014-01-01

    This study investigated and compared the acoustic characteristics of two natural organic fibres: date palm fibre and oil palm fibre, these materials eligible for acoustical absorption. During the processing stage, both fibre sheets are treated with latex. The two fibres are compressed after latex treatment Circular samples (100 mm in diameter and 28 mm, based on the measurement tube requirements) are cut out of the sheets. The density of the date palm fibre sheet is 150 kg/m3 for a 50 mm thic...

  9. Cerebellar cognitive affective syndrome CCAS – a case report

    Directory of Open Access Journals (Sweden)

    Starowicz-Filip, Anna

    2013-09-01

    Full Text Available Aim. The aim of the study was to describe a case of the patient with cerebellar cognitive affective syndrome CCAS, characterize the role of cerebellum in the regulation of cognitive functions and present theprocedure of neuropsychological diagnosis useful in indicating the specific cognitive and emotional problems in patients with cerebellar damage.Case report. A 41- year old man with an ischemic cerebellar stroke of its right hemisphere manifested the neuropsychological symptoms typical for the frontal damage: euphoric mood, disorganized behavior,lack of criticism and mental plasticity, tendency to shorten the personal distance, problems with mistake correction. In neuropsychological diagnosis we used following methods: Raven Progressive Matrices Test, Mini Mental Stage Examination (MMSE, Trail Making Test, Wisconsin Card Sorting Test, Stroop Interference Test, Word Fluency Test, Auditory Verbal Learning Test by Łuria, Benton Visual Retention Test, Digit Span.Results. Analyzing the obtained results we observed the significant decrease of all executive functions: planning, abstract thinking, cognitive flexibility, adaptation to new situations as well as memory impairments and changes in emotional and behavioral state similar to frontal syndrome. The whole of impairments including the typical cerebellar symptoms (ataxia, dysarthria, dysmetria,hypotonia create the cerebellar cognitive affective syndrome CCAS with leading role of dysexecutive syndrome.Conclusions. The cerebellum takes part in the regulation of cognitive functions. The cerebellar damages can imitate the emotional- cognitive problems of patients after frontal damages what additionally stress the functional link between these two brain structures. Patient’s with cerebellar damages should have neuropsychological and neuropsychiatric diagnosis and care.

  10. A cerebellar neuroprosthetic system: computational architecture and in vivo experiments

    Directory of Open Access Journals (Sweden)

    PaulF.M.J.Verschure

    2014-05-01

    Full Text Available Emulating the input-output functions performed by a brain structure opens the possibility for developing neuro-prosthetic systems that replace damaged neuronal circuits. Here, we demonstrate the feasibility of this approach by replacing the cerebellar circuit responsible for the acquisition and extinction of motor memories. Specifically, we show that a rat can undergo acquisition, retention and extinction of the eye-blink reflex even though the biological circuit responsible for this task has been chemically inactivated via anesthesia. This is achieved by first developing a computational model of the cerebellar microcircuit involved in the acquisition of conditioned reflexes and training it with synthetic data generated based on physiological recordings. Secondly, the cerebellar model is interfaced with the brain of an anesthetized rat, connecting the model's inputs and outputs to afferent and efferent cerebellar structures. As a result, we show that the anesthetized rat, equipped with our neuro-prosthetic system, can be classically conditioned to the acquisition of an eye-blink response. However, non-stationarities in the recorded biological signals limit the performance of the cerebellar model. Thus, we introduce an updated cerebellar model and validate it with physiological recordings showing that learning becomes stable and reliable. The resulting system represents an important step towards replacing lost functions of the central nervous system via neuro-prosthetics, obtained by integrating a synthetic circuit with the afferent and efferent pathways of a damaged brain region. These results also embody an early example of science-based medicine, where on the one hand the neuro-prosthetic system directly validates a theory of cerebellar learning that informed the design of the system, and on the other one it takes a step towards the development of neuro-prostheses that could recover lost learning functions in animals and, in the longer term

  11. Methodology for characterisation of glass fibre composite architecture

    DEFF Research Database (Denmark)

    Hansen, Jens Zangenberg; Larsen, J.B.; Østergaard, R.C.;

    2012-01-01

    fibres. The information is used for different analyses to investigate and characterise the fibre architecture. As an example, the methodology is applied to glass fibre reinforced composites with varying fibre contents. The different fibre volume fractions (FVFs) affect the number of contact points per...... fibre, the communal fibre distance and the local FVF. The fibre diameter distribution and packing pattern remain somewhat similar for the considered materials. The methodology is a step towards a better understanding of the composite microstructure and can be used to evaluate the interconnection between...... fibre architecture and composite properties....

  12. Electrophysiological mapping of novel prefrontal - cerebellar pathways

    Directory of Open Access Journals (Sweden)

    Matthew W Jones

    2009-08-01

    Full Text Available Whilst the cerebellum is predominantly considered a sensorimotor control structure, accumulating evidence suggests that it may also subserve non motor functions during cognition. However, this possibility is not universally accepted, not least because the nature and pattern of links between higher cortical structures and the cerebellum are poorly characterized. We have therefore used in vivo electrophysiological methods in anaesthetized rats to directly investigate connectivity between the medial prefrontal cortex (prelimbic subdivision, PrL and the cerebellum. Stimulation of deep layers of PrL evoked distinct field potentials in the cerebellar cortex with a mean latency to peak of approximately 35ms. These responses showed a well-defined topography, and were maximal in lobule VII of the contralateral vermis (a known oculomotor centre; they were not attenuated by local anesthesia of the overlying M2 motor cortex, though M2 stimulation did evoke field potentials in lobule VII with a shorter latency. Single-unit recordings showed that prelimbic cortical stimulation elicits complex spikes in lobule VII Purkinje cells, indicating transmission via a previously undescribed cerebro-olivocerebellar pathway. Our results therefore establish a physiological basis for communication between PrL and the cerebellum. The role(s of this pathway remain to be resolved, but presumably relate to control of eye movements and/or distributed networks associated with integrated prefrontal cortical functions.

  13. Surface modification of cellulose fibres

    Directory of Open Access Journals (Sweden)

    Mohamed Naceur Belgacem

    2005-06-01

    Full Text Available Several approaches to the modification of cellulose fibres are described, namely: (i physical treatments such as corona or plasma treatments under different atmospheres; (ii grafting with hydrophobic molecules using well-known sizing compounds; (iii grafting with bi-functional molecules, leaving one of the functions available for further exploitation; and (iv grafting with organometallic compounds. The modified surfaces were characterized by elemental analysis, contact angle measurements, inverse gas chromatography, X-ray photoelectron and infrared spectroscopy, wettability, etc. These different tools provided clear-cut evidence of the occurrence of chemical reactions between the grafting agent used and the hydroxy functions of the cellulose surface, as well as of the existence of covalent bonding in the ensuing composite materials between the matrix and the fibres through the use of doubly reactive coupling agents.

  14. Lime mortars with natural fibres

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš; Michoinová, D.

    Varšava : ZTUREK, 2003 - (Brandt, A.; Li, V.; Marshall, I.), s. 523-532 ISBN 1-85573-769-8. [International Symposium of Brittle matrix /7./. Varšava (PL), 13.10.2003-15.10.2003] R&D Projects: GA MK PK00P04OPP015 Institutional research plan: CEZ:AV0Z2071913 Keywords : lime mortar * natural fibres * experimental research Subject RIV: JM - Building Engineering

  15. CCD technology beyond fibre optics

    International Nuclear Information System (INIS)

    For the past 25 years the accepted method of viewing inside industrial components, or indeed the human body, has been by the use of either flexible or rigid fibre optics. In the last five years however, many developments have enabled television cameras to reduce to a size small enough to allow internal viewing of an object, without prior dismantling. This concept was achieved five years ago, with the Welch Allyn Videoprobe 2000, a charge coupled device. (author)

  16. Effect of histamine on the electric activities of cerebellar Purkinje cell

    CERN Document Server

    Tang, L

    1999-01-01

    The effect of histamine (HA) on the electric activities of Purkinje cell (PC) is studied on the cerebellum slice. We find that: (1) HA's main effect on PC is excitative (72.9%); there are also a small amount of PC showing inhibitive (10.2%) or no (16.9%) response to HA. (2) Different from the conventional opinion, HA's excitative effect on PC is mutually conducted by H1 and H2 receptors; the antagonist for H1 receptor could weaken HA's excitative effect on PC, while the antagonist for H2 receptor could weaken or even block the excitative effect of HA on PC. (3) PC's reaction to HA is related to its intrinsic discharge frequency; there exists a frequency at which PC is highly sensitive to HA, and well above this frequency PC becomes stable against HA. These results indicate that the histaminergic afferent fibre can adjust PC's electric activities by releasing HA, and thereby influence the global function of the cerebellar cortex; and that just like the $\\gamma $ region of cerebrum, cerebellum may also have som...

  17. Frost resistance of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    0.4-1% by volume of fibres cannot replace air entrainment in order to secure a frost resistant concrete; the minimum amount of air needed to make the concrete frost resistant is not changed when adding fibres· the amount of air entrainment must be increased when fibres are added to establish the......Frost resistance of fibre reinforced concrete with 2.5-4.2% air and 6-9% air (% by volume in fresh concrete) casted in the laboratory and in-situ is compared. Steel fibres with hooked ends (ZP, length 30 mm) and polypropylene fibres (PP, CS, length 12 mm) are applied. It is shown that· addition of...

  18. Material dispersion measurements in optical fibre waveguides

    International Nuclear Information System (INIS)

    Preliminary measurements of material dispersion on optical fibres now being routinely produced by TELEBRAS in Brasil are carried out. This was done by using two semiconductor lasers emitting at the different wavelengths of 800 nm and 904 nm. The result of approximately 100 ps/nm/km in germania-doped silica fibres is approximately 30% higher than the value for pure silica; this agrees well with results obtained in other laboratories with similar fibres. Material dispersion can limit the bandwidth of an optical fibre, especially when a light emitting diode, operating in the 800. 900 nm wavelength region is used as the light source in a fibre optical communication system having graded-index fibres with an optimum index profile. (Author)

  19. Development of the cerebellar cortex in the mouse

    Institute of Scientific and Technical Information of China (English)

    Xiangshu Cheng; Jin Du; Dongming Yu; Qiying Jiang; Yanqiu Hu; Lei Wang; Mingshan Li; Jinbo Deng

    2011-01-01

    The cerebellum is a highly conserved structure in the central nervous system of vertebrates, and is involved in the coordination of voluntary motor behavior. Supporting this function, the cerebellar cortex presents a layered structure which requires precise spatial and temporal coordination of proliferation, migration, differentiation, and apoptosis events. The formation of the layered structure in the developing cerebellum remains unclear. The present study investigated the development of the cerebellar cortex. The results demonstrate that the primordium of the cerebellum comprises the ependymal, mantle, and marginal layers at embryonic day 12 (E12). Subsequently, the laminated cerebellar cortex undergoes cell proliferation, differentiation, and migration, and at about postnatal day 0 (P0), the cerebellar cortex presents an external granular layer, a molecular layer, a Purkinje layer, and an internal granular layer. The external granular layer is thickest at P6/7 and disappears at P20. From P0 to P30, the internal granular cells and the Purkinje cells gradually differentiate and develop until maturity. Apoptotic neurons are evident in the layered structure in the developing cerebellar cortex. The external granular layer disappears gradually because of cell migration and apoptosis. The cells of the other layers primarily undergo differentiation, development, and apoptosis.

  20. MR imaging of solid cerebellar tumors in adult

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Kee Hyun; Han, Moon Hee; Yu, In Kyu [Seoul National University College of Medicine, Seoul (Korea, Republic of); Choo, Sung Wook; Byun, Hong Sik [Samsung Medical Center, Seoul (Korea, Republic of); Choi, Kyu Ho; Kim, Ki Jun [Catholic University Medical College, Seoul (Korea, Republic of)

    1995-07-15

    The solid variety of cerebellar tumors in adult is relatively uncommon. This study is to describe the characteristic MR findings of various solid cerebellar tumors in adult. Twenty three cerebellar solid tumors from 22 consecutive patients over age of 15 with surgical confirmations were retrospectively evaluated with MR findings. Histologic diagnosis included hemangioblastoma (n = 6), metastasis (n = 6), high-grade astrocytoma (n = 3), and medulloblastoma (n = 8). The MR findings were reviewed with attention of the size, the signal intensity of the tumors, pattern of enhancement, tumoral margin, degree of peritumoral edema, signal void vascular structures within and/or around the tumor, and location in relation to attachment to the pial surface of the tumor. Solid hemangioblastomas consistently showed slightly low or iso signal intensity on T1-weighted images and high intensity on T2-weighted images, dense homogeneous enhancement, and signal void vessels within and/or around the mass. Metastatic tumors showed various findings with predominantly low or iso signal intensity on T2-weighted images. Medulloblastomas was midline and/or paramidline in location, and had larger mass formation. High-grade astrocytomas revealed nonspecific MR findings with no signal void vessels. Hemangioblastoma, metastasis, malignant astrocytoma, and medulloblastoma should be included in differential diagnosis of solid cerebellar tumors in adult. Dense homogeneous enhancement and signal void vessels are characteristic of hemangioblastoma. The signal intensity of the tumor, and presence of signal void vessels, location and enhancement pattern can be some value in differential diagnosis of solid cerebellar tumors in adult.

  1. Emotions and their cognitive control in children with cerebellar tumors.

    Science.gov (United States)

    Hopyan, Talar; Laughlin, Suzanne; Dennis, Maureen

    2010-11-01

    A constellation of deficits, termed the cerebellar cognitive affective syndrome (CCAS), has been reported following acquired cerebellar lesions. We studied emotion identification and the cognitive control of emotion in children treated for acquired tumors of the cerebellum. Participants were 37 children (7-16 years) treated for cerebellar tumors (19 benign astrocytomas (AST), 18 malignant medulloblastomas (MB), and 37 matched controls (CON). The Emotion Identification Task investigated recognition of happy and sad emotions in music. In two cognitive control tasks, we investigated whether children could identify emotion in situations in which the emotion in the music and the emotion in the lyrics was either congruent or incongruent. Children with cerebellar tumors identified emotion as accurately and quickly as controls (p > .05), although there was a significant interaction of emotions and group (p sad emotions, and both cerebellar tumor groups were impaired in the cognitive control of emotions (p emotion rather than emotion identification provides some support for a model of the CCAS as a disorder, not so much of emotion as of the regulation of emotion by cognition. PMID:20887648

  2. Does cerebellar neuronal integrity relate to cognitive ability?

    International Nuclear Information System (INIS)

    Full text: Magnetic resonance spectroscopy (MRS) allows the non-invasive measurement of metabolite levels in the brain. One of these is N-acetylaspartate (NA), a molecule found solely in neurones, synthesised there by mitochondria. This compound can be considered as a marker of 1) neuronal density and 2) neuronal mitochondria function. We recently completed a joint MRS and neuropsychological investigation of Williams-Beuren syndrome (WBS), a rare (1/20,000) autosomal dominant disorder caused by a deletion which includes the elastin locus and LIM-kinase. The syndrome has an associated behavioural and cognitive profile which includes hyperactivity, hyperacusis and excessive sociability. Spatial skills are severely affected, while verbal skills are left relatively intact Our investigation showed loss of NA from the cerebellum in WBS compared with normal controls, with the subject population as a whole displaying a continuum of cerebellar NA concentration. Ability at cognitive tests, including the Weschler IQ scale and various verbal and spatial tests, was shown to correlate significantly and positively with the concentration of NA in the cerebellum. This finding can be interpreted in one of two ways: 1. Our sampling of cerebellar metabolite levels represents a 'global' sampling of total brain neuronal density and, as such, is independent of cerebellar integrity. 2. Cerebellar neuronal integrity is associated with performance at cognitive tests. If the latter interpretation is shown to be the case, it will have important implications for our current understanding of cerebellar function. Copyright (1998) Australian Neuroscience Society

  3. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Polarisation reflectometry of anisotropic optical fibres

    Science.gov (United States)

    Konstantinov, Yurii A.; Kryukov, Igor'I.; Pervadchuk, Vladimir P.; Toroshin, Andrei Yu

    2009-11-01

    Anisotropic, polarisation-maintaining fibres have been studied using a reflectometer and integrated optic polariser. Linearly polarised pulses were launched into the fibre under test at different angles between their plane of polarisation and the main optical axis of the fibre. A special procedure for the correlation analysis of these reflectograms is developed to enhance the reliability of the information about the longitudinal optical uniformity ofanisotropic fibres.

  4. The usability of recycled carbon fibres in short fibre thermoplastics: interfacial properties

    OpenAIRE

    Burn, D.T.; Harper, Lee Thomas; Johnson, M.; Warrior, N. A.; Nagel, U.; Yang, L.; Thomason, J.

    2016-01-01

    The objective of this study was to investigate the feasibility of combining discontinuous recycled carbon fibres with polypropylene, to produce a low-cost, high specific stiffness material for high-volume applications. The inherent low affinity of carbon fibre and polypropylene motivated a detailed study of the surface characteristics of carbon fibre and interfacial behaviour between the two materials, using the microbond test. The effects of removing the sizing from the fibres, as well as in...

  5. Continuous jute fibre reinforced laminated paper composite and reinforcement-fibre free paper laminate

    Indian Academy of Sciences (India)

    B B Verma

    2009-12-01

    Plastic bags create a serious environmental problem. The proposed jute fibre reinforced laminated paper composite and reinforcement-fibre free paper laminate may help to combat the war against this pollutant to certain extent. The paper laminate, without reinforcement fibre, exhibited a few fold superiority in tensile properties than single paper strip. The studies further show that an appreciable improvement in tensile properties can be achieved by introducing continuous jute fibre in paper laminates.

  6. Fibre Reinforced Concrete: Optimization of fibre content and shear capacity of dapped-end beams

    OpenAIRE

    Boix Roca, Miguel

    2013-01-01

    Fibre reinforced concrete is a type of concrete which improves the fracture characteristics and structural behaviour through the fibres ability to bridge cracks: it offers a much more ductile response. Thus, the principal aim of this project has been to improve the current knowledge of the fresh and mechanical behaviour of fibre reinforced concrete. When casting FRC, the addition of fibres can substitute traditional reinforcement, which reduces the worker hours required and improves economic ...

  7. Differential Geometry of Composite Fibred Manifolds

    OpenAIRE

    Sardanashvily, G.

    1994-01-01

    In classical field theory, the composite fibred manifolds Y -> Z -> X provides the adequate mathematical formulation of gauge models with broken symmetries, e.g., the gauge gravitation theory. This work is devoted to connections on composite fibred manifolds. In particular, we get the horizontal splitting of the vertical tangent bundle of a composite fibred manifold, besides the familiar one of its tangent bundle. This splitting defines the modified covariant differential and implies the spec...

  8. Guideline for Use of Fibre Optic Sensors

    OpenAIRE

    Habel, Wolfgang R.; Baumann, Ingolf; Berghmans, Francis; Borzycki, Krzysztof; Chojetzki, Christoph; Haase, Karl-Heinz; Jaroszewicz, Leszek R.; Kleckers, Thomas; Nikles, Marc; Rothhardt, Manfred; Schluter, Vivien; Thévenaz, Luc; Tur, Moshe; Wuilpart, Marc

    2009-01-01

    Development of standards and guidelines for performance specifications and testing for fibre optic sensors has been discussed since the mid-nineties of the last century in the scientific community as well as in the industry. Very global standards for the use of fibre optic components in data communication and telecommunication have been available for more than 20 years. Guidelines or substantial standards for fibre optic sensors are rather an exception. The first standard draft on generic spe...

  9. Muscle fibre ontogenesis in farm animal species

    OpenAIRE

    Picard, Brigitte; Lefaucheur, Louis; Berri, Cécile; Duclos, Michel

    2002-01-01

    International audience In farm animals (bovine, ovine, swine, rabbit and poultry), muscle fibre characteristics play a key role in meat quality. The present review summarises the knowledge on muscle fibre characteristics and ontogenesis in these species. Myofibre ontogenesis begins very early during embryonic life, with the appearance of two or three successive waves of myoblasts which constitute the origin of the different types of muscle fibres. In small animals (rodents and poultry), a ...

  10. Evanescent wave spectroscopy using multimode optical fibres

    OpenAIRE

    Murphy, Joseph A.

    1990-01-01

    The use of multimode optical fibre as an intrinsic chemical sensor, with application in on-line analysis in the process industry, is described. The technique of attenuated total reflection spectroscopy is applied to the unclad section of the fibre which is in contact with the chemical being detected. A model based on selective mode propagation is developed to relate the evanescent absorption coefficient of the fibre probe to the bulk absorption coefficient of the absor...

  11. Mitotic Events in Cerebellar Granule Progenitor Cells that Expand Cerebellar Surface Area Are Critical for Normal Cerebellar Cortical Lamination in Mice

    Science.gov (United States)

    Chang, Joshua C.; Leung, Mark; Gokozan, Hamza Numan; Gygli, Patrick Edwin; Catacutan, Fay Patsy; Czeisler, Catherine; Otero, José Javier

    2015-01-01

    Late embryonic and postnatal cerebellar folial surface area expansion promotes cerebellar cortical cytoarchitectural lamination. We developed a streamlined sampling scheme to generate unbiased estimates of murine cerebellar surface area and volume using stereological principles. We demonstrate that during the proliferative phase of the external granule layer (EGL) and folial surface area expansion, EGL thickness does not change and thus is a topological proxy for progenitor self-renewal. The topological constraints indicate that during proliferative phases, migration out of the EGL is balanced by self-renewal. Progenitor self-renewal must, therefore, include mitotic events yielding either 2 cells in the same layer to increase surface area (β-events) and mitotic events yielding 2 cells, with 1 cell in a superficial layer and 1 cell in a deeper layer (α-events). As the cerebellum grows, therefore, β-events lie upstream of α-events. Using a mathematical model constrained by the measurements of volume and surface area, we could quantify inter-mitotic times for β-events on a per-cell basis in post-natal mouse cerebellum. Furthermore, we found that loss of CCNA2, which decreases EGL proliferation and secondarily induces cerebellar cortical dyslamination, shows preserved α-type events. Thus, CCNA2-null cerebellar granule progenitor cells are capable of self-renewal of the EGL stem cell niche; this is concordant with prior findings of extensive apoptosis in CCNA2-null mice. Similar methodologies may provide another layer of depth to the interpretation of results from stereological studies. PMID:25668568

  12. Liquid core fibre versus doped sol-gel layered structured fibre for chemical sensing

    Science.gov (United States)

    Canning, John; Huyang, George; Åslund, Mattias L.; Naqshbandi, Masood; Stocks, Danial; Crossley, Maxwell J.

    2010-10-01

    We review recent work on evaluating the performance of a simple porphyrin-based acid sensor using structured fibre technology. Specifically, the same sensor in a multimode liquid core is compared to that in a sol-gel coated structured optical fibre. General implications for fibre chemical sensing are discussed.

  13. Tensile and compressive properties of flax fibres for natural fibre reinforced composites

    NARCIS (Netherlands)

    Bos, H.L.; Oever, van den M.J.A.; Peters, O.C.J.J.

    2002-01-01

    Mechanical properties of standard decorticated and hand isolated flax bast fibres were determined in tension as well as in compression. The tensile strength of technical fibre bundles was found to depend strongly on the clamping length. The tensile strength of elementary flax fibres was found to ran

  14. Plant fibre composites - porosity and volumetric interaction

    DEFF Research Database (Denmark)

    Madsen, Bo; Thygesen, Anders; Lilholt, Hans

    Plant fibre composites contain typically a relative large amount of porosity, which considerably influences properties and performance of the composites. The large porosity must be integrated in the conversion of weight fractions into volume fractions of the fibre and matrix parts. A model is...... the combination of a high fibre volume fraction, a low porosity and a high composite density is optimal. Experimental data from the literature on volumetric composition and density of four types of plant fibre composites are used to validate the model. It is demonstrated that the model provides a...

  15. A novel photonic crystal fibre switch

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Hermann, D.S.; Broeng, Jes;

    2003-01-01

    A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB.......A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB....

  16. Structure development in electrospun fibres of gelatin

    International Nuclear Information System (INIS)

    Gelatin fibres have been successfully electrospun from water by heating a gelatin solution above the sol-gel transition temperature, and allowing cooling in a controlled environment as the fibres are produced. The development of structure with in these fibres is monitored using wide angle x-ray scattering, in this way the presence of the triple helix structure, which provides the physical cross-linkages in the gel could be probed. There is clear evidence that these structures are obtained in gelatin electrospun from aqueous solutions. In contrast fibres electrospun from a solution of gelatin in glacial acetic acid, showed no evidence of the triple helix structure.

  17. Towards the Knittability of Graphene Oxide Fibres

    Science.gov (United States)

    Seyedin, Shayan; Romano, Mark S.; Minett, Andrew I.; Razal, Joselito M.

    2015-10-01

    Recent developments in graphene oxide fibre (GO) processing include exciting demonstrations of hand woven textile structures. However, it is uncertain whether the fibres produced can meet the processing requirements of conventional textile manufacturing. This work reports for the first time the production of highly flexible and tough GO fibres that can be knitted using textile machinery. The GO fibres are made by using a dry-jet wet-spinning method, which allows drawing of the spinning solution (the GO dispersion) in several stages of the fibre spinning process. The coagulation composition and spinning conditions are evaluated in detail, which led to the production of densely packed fibres with near-circular cross-sections and highly ordered GO domains. The results are knittable GO fibres with Young’s modulus of ~7.9 GPa, tensile strength of ~135.8 MPa, breaking strain of ~5.9%, and toughness of ~5.7 MJ m-3. The combination of suitable spinning method, coagulation composition, and spinning conditions led to GO fibres with remarkable toughness; the key factor in their successful knitting. This work highlights important progress in realising the full potential of GO fibres as a new class of textile.

  18. The diversity of fibre laser technology

    OpenAIRE

    Richardson, D J

    2007-01-01

    High power fibre laser technology has come of age over the past five years or so, due primarily to developments in fibre design and fabrication and semiconductor pump lasers. Fibre is now emerging as the technology of choice for a wide range of laser applications. Nowhere has the progress been more striking than in terms of the maximum continuous wave output power achievable from a single-mode fibre laser. Up until the start of 2001 the maximum reported output power from such a laser was ~110...

  19. Internal carotid-cerebellar artery anastomosis. So-called persistent trigeminal artery variant

    Energy Technology Data Exchange (ETDEWEB)

    Tanohata, Kazunori; Maehara, Tadayuki; Noda, Masanobu; Katoh, Hiromi

    1987-09-01

    Five cases of internal carotid-cerebellar artery anastomosis are presented. These anomalous vessels are identical to the so-called persistent trigeminal artery variant (PTAV). In our cases, two superior cerebellar arteries (SCAs), two anterior inferior cerebellar arteries (AICAs) and one posterior inferior cerebellar artery (PICA) arose from the precavernous segment of the internal carotid artery. We discuss the embryolgical and neuroradiological aspects of this anomaly.

  20. A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

    Science.gov (United States)

    Hopmann, Ch.; Weber, M.; van Haag, J.; Schöngart, M.

    2015-05-01

    To improve the mechanical performance of polymeric parts, fibre reinforcement has established in industrial applications during the last decades. Next to the widely used Short Fibre-reinforced Thermoplastics (SFT) the use of Long Fibre-reinforced Thermoplastics (LFT) is increasingly growing. Especially for non-polar polymeric matrices like polypropylene (PP), longer fibres can significantly improve the mechanical performance. As with every kind of discontinuous fibre reinforcement the fibre orientations (FO) show a high impact on the mechanical properties. On the contrary to SFT where the local fibre length distribution (FLD) can be often neglected, for LFT the FLD show a high impact on the material's properties and has to be taken into account in equal measure to the FOD. Recently numerical models are available in commercial filling simulation software and allow predicting both the local FOD and FLD in LFT parts. The aim of this paper is to compare i.) the FOD results and ii) the FLD results from available orientation- and fibre length attrition-models to those obtained from experimental data. The investigations are conducted by the use of different injection moulded specimens made from long glass fibre reinforced PP. In order to determine the FOD, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation. The FLD results are also obtained by using digital image processing after a thermal pyrolytic separation of the polymeric matrix from the fibres. Further the FOD and the FLD are predicted by using a reduced strain closure (RSC) as well as an anisotropic rotary diffusion - reduced strain closure model (ARD-RSC) and Phelps-Tucker fibre length attrition model implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA.

  1. A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

    Energy Technology Data Exchange (ETDEWEB)

    Hopmann, Ch.; Weber, M.; Haag, J. van; Schöngart, M. [Institute of Plastics Processing (IKV) at RWTH Aachen University, Pontstr. 49, 52062 Aachen (Germany)

    2015-05-22

    To improve the mechanical performance of polymeric parts, fibre reinforcement has established in industrial applications during the last decades. Next to the widely used Short Fibre-reinforced Thermoplastics (SFT) the use of Long Fibre-reinforced Thermoplastics (LFT) is increasingly growing. Especially for non-polar polymeric matrices like polypropylene (PP), longer fibres can significantly improve the mechanical performance. As with every kind of discontinuous fibre reinforcement the fibre orientations (FO) show a high impact on the mechanical properties. On the contrary to SFT where the local fibre length distribution (FLD) can be often neglected, for LFT the FLD show a high impact on the material’s properties and has to be taken into account in equal measure to the FOD. Recently numerical models are available in commercial filling simulation software and allow predicting both the local FOD and FLD in LFT parts. The aim of this paper is to compare i.) the FOD results and ii) the FLD results from available orientation- and fibre length attrition-models to those obtained from experimental data. The investigations are conducted by the use of different injection moulded specimens made from long glass fibre reinforced PP. In order to determine the FOD, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation. The FLD results are also obtained by using digital image processing after a thermal pyrolytic separation of the polymeric matrix from the fibres. Further the FOD and the FLD are predicted by using a reduced strain closure (RSC) as well as an anisotropic rotary diffusion - reduced strain closure model (ARD-RSC) and Phelps-Tucker fibre length attrition model implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA.

  2. Surface treated polypropylene (PP) fibres for reinforced concrete

    Energy Technology Data Exchange (ETDEWEB)

    López-Buendía, Angel M., E-mail: buendia@uv.es [AIDICO Technological Institute of Construction, Benjamin Franklin 17, 46380 Paterna, Valencia (Spain); Romero-Sánchez, María Dolores [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain); Climent, Verónica [Lafarge Cementos, Polígono Sepes, Isaac Newton s/n, 46500 Sagunto, Valencia (Spain); Guillem, Celia [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain)

    2013-12-15

    Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.

  3. Surface treated polypropylene (PP) fibres for reinforced concrete

    International Nuclear Information System (INIS)

    Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment

  4. Cerebellar networks with the cerebral cortex and basal ganglia.

    Science.gov (United States)

    Bostan, Andreea C; Dum, Richard P; Strick, Peter L

    2013-05-01

    The dominant view of cerebellar function has been that it is exclusively concerned with motor control and coordination. Recent findings from neuroanatomical, behavioral, and imaging studies have profoundly changed this view. Neuroanatomical studies using virus transneuronal tracers have demonstrated that cerebellar output reaches vast areas of the neocortex, including regions of prefrontal and posterior parietal cortex. Furthermore, it has recently become clear that the cerebellum is reciprocally connected with the basal ganglia, which suggests that the two subcortical structures are part of a densely interconnected network. Taken together, these findings elucidate the neuroanatomical substrate for cerebellar involvement in non-motor functions mediated by the prefrontal and posterior parietal cortex, as well as in processes traditionally associated with the basal ganglia. PMID:23579055

  5. An unusual cause of adult onset cerebellar ataxia with hypogonadism

    Directory of Open Access Journals (Sweden)

    Menon Ramshekhar

    2009-01-01

    Full Text Available We report an unusual case of sporadic adult onset cerebellar ataxia with hypogonadism. A 40-year-old unmarried man presented with progressive ataxia and dysarthria along with complaints of non-development of secondary sexual characteristics and erectile dysfunction. There were complaints of intermittent diarrhea. Clinical examination revealed a pan-cerebellar syndrome with features of hypoandrogenism. No eye movement abnormalities were evident. There were signs of malabsorption. Investigations confirmed the presence of auto-antibodies found in celiac disease, and a duodenal biopsy confirmed the same. Hypoandrogenism was postulated to be due to hypergonadotropic hypogonadism which has been mentioned in a few patients of celiac disease. However, the pattern seen in our patient was of a hypogonadotropic hypogonadism. This is probably secondary to an autoimmune hypophysitis seen in some patients in the absence of other clinical manifestations. Autoantibody testing should be a diagnostic necessity in any adult with a sporadic cerebellar ataxia.

  6. File list: DNS.Neu.10.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Neu.10.AllAg.Cerebellar_granule_neurons mm9 DNase-seq Neural Cerebellar granule neurons... SRX685882,SRX685880,SRX685883,SRX685885,SRX685877,SRX685878 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/DNS.Neu.10.AllAg.Cerebellar_granule_neurons.bed ...

  7. File list: Oth.Neu.20.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Neu.20.AllAg.Cerebellar_granule_neurons mm9 TFs and others Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.Neu.20.AllAg.Cerebellar_granule_neurons.bed ...

  8. File list: ALL.Neu.50.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Neu.50.AllAg.Cerebellar_granule_neurons mm9 All antigens Neural Cerebellar granule neurons... SRX685885,SRX685882,SRX685880 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Neu.50.AllAg.Cerebellar_granule_neurons.bed ...

  9. File list: Unc.Neu.10.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Neu.10.AllAg.Cerebellar_granule_neurons mm9 Unclassified Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Unc.Neu.10.AllAg.Cerebellar_granule_neurons.bed ...

  10. File list: Unc.Neu.05.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Neu.05.AllAg.Cerebellar_granule_neurons mm9 Unclassified Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Unc.Neu.05.AllAg.Cerebellar_granule_neurons.bed ...

  11. File list: ALL.Neu.20.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Neu.20.AllAg.Cerebellar_granule_neurons mm9 All antigens Neural Cerebellar granule neurons... SRX685885,SRX685882,SRX685880 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Neu.20.AllAg.Cerebellar_granule_neurons.bed ...

  12. File list: His.Neu.05.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Neu.05.AllAg.Cerebellar_granule_neurons mm9 Histone Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/His.Neu.05.AllAg.Cerebellar_granule_neurons.bed ...

  13. File list: Oth.Neu.10.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Neu.10.AllAg.Cerebellar_granule_neurons mm9 TFs and others Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.Neu.10.AllAg.Cerebellar_granule_neurons.bed ...

  14. File list: Unc.Neu.50.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Neu.50.AllAg.Cerebellar_granule_neurons mm9 Unclassified Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Unc.Neu.50.AllAg.Cerebellar_granule_neurons.bed ...

  15. File list: DNS.Neu.20.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Neu.20.AllAg.Cerebellar_granule_neurons mm9 DNase-seq Neural Cerebellar granule neurons... SRX685885,SRX685882,SRX685880 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/DNS.Neu.20.AllAg.Cerebellar_granule_neurons.bed ...

  16. File list: His.Neu.10.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Neu.10.AllAg.Cerebellar_granule_neurons mm9 Histone Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/His.Neu.10.AllAg.Cerebellar_granule_neurons.bed ...

  17. File list: Pol.Neu.20.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Neu.20.AllAg.Cerebellar_granule_neurons mm9 RNA polymerase Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Neu.20.AllAg.Cerebellar_granule_neurons.bed ...

  18. File list: Pol.Neu.50.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Neu.50.AllAg.Cerebellar_granule_neurons mm9 RNA polymerase Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Neu.50.AllAg.Cerebellar_granule_neurons.bed ...

  19. File list: DNS.Neu.50.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Neu.50.AllAg.Cerebellar_granule_neurons mm9 DNase-seq Neural Cerebellar granule neurons... SRX685885,SRX685882,SRX685880 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/DNS.Neu.50.AllAg.Cerebellar_granule_neurons.bed ...

  20. File list: Unc.Neu.20.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Neu.20.AllAg.Cerebellar_granule_neurons mm9 Unclassified Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Unc.Neu.20.AllAg.Cerebellar_granule_neurons.bed ...

  1. File list: His.Neu.50.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Neu.50.AllAg.Cerebellar_granule_neurons mm9 Histone Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/His.Neu.50.AllAg.Cerebellar_granule_neurons.bed ...

  2. File list: DNS.Neu.05.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Neu.05.AllAg.Cerebellar_granule_neurons mm9 DNase-seq Neural Cerebellar granule neurons... SRX685885,SRX685878,SRX685882,SRX685877,SRX685880,SRX685883 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/DNS.Neu.05.AllAg.Cerebellar_granule_neurons.bed ...

  3. File list: Oth.Neu.50.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Neu.50.AllAg.Cerebellar_granule_neurons mm9 TFs and others Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.Neu.50.AllAg.Cerebellar_granule_neurons.bed ...

  4. File list: His.Neu.20.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Neu.20.AllAg.Cerebellar_granule_neurons mm9 Histone Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/His.Neu.20.AllAg.Cerebellar_granule_neurons.bed ...

  5. File list: ALL.Neu.10.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Neu.10.AllAg.Cerebellar_granule_neurons mm9 All antigens Neural Cerebellar granule neurons... SRX685882,SRX685880,SRX685883,SRX685885,SRX685877,SRX685878 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Neu.10.AllAg.Cerebellar_granule_neurons.bed ...

  6. File list: ALL.Neu.05.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Neu.05.AllAg.Cerebellar_granule_neurons mm9 All antigens Neural Cerebellar granule neurons... SRX685885,SRX685878,SRX685882,SRX685877,SRX685880,SRX685883 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Neu.05.AllAg.Cerebellar_granule_neurons.bed ...

  7. File list: Pol.Neu.10.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Neu.10.AllAg.Cerebellar_granule_neurons mm9 RNA polymerase Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Neu.10.AllAg.Cerebellar_granule_neurons.bed ...

  8. File list: Oth.Neu.05.AllAg.Cerebellar_granule_neurons [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Neu.05.AllAg.Cerebellar_granule_neurons mm9 TFs and others Neural Cerebellar granule neurons... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.Neu.05.AllAg.Cerebellar_granule_neurons.bed ...

  9. Hemorrhagic cerebellar anaplastic glioma appearing 12 years after prophylactic cranial radiotherapy for acute lymphocytic leukemia

    International Nuclear Information System (INIS)

    A radiation-induced cerebellar glioma is extremely rare, and the etiology of such a tumor is unknown. We report a rare case of hemorrhagic cerebellar anaplastic glioma occurring 12 years after prophylactic cranial radiotherapy for acute lymphocytic leukemia. We discuss the etiologies of the radiation-induced hemorrhagic cerebellar glioma as a secondary malignancy after radiotherapy. (author)

  10. Cerebellar atrophy in an epileptic child: is it due to phenytoin?

    Directory of Open Access Journals (Sweden)

    Ahuja S

    2000-10-01

    Full Text Available A four and half year old epileptic child on phenytoin therapy since one year presented with signs of cerebellar dysfunction. Serum phenytoin level was high (33 mcg/ml and computerised tomographic scan of the brain showed severe generalised cerebellar atrophy. The cerebellar signs represented drug over dosage and toxicity and persisted long after omission of phenytoin.

  11. Non-Linear Fibres for Widely Tunable Femtosecond Fibre Lasers

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard

    theoretically and numerically. For the intermodal four-wave mixing experiment an alternative version of the Generalised Non-Linear Schrödinger Equation is derived, which includes the correct dispersion of the transverse field. It is observed that the alternative version of the Generalised Non-Linear Schrödinger...... Equation, as opposed to the commonly used version, is able to reproduce the intermodal four-wave mixing experiment. The relation between the intramodal self-phase modulation and the intramodal Raman effect is determined from experimental measurements on a number of step-index fibres. The Raman fraction is...

  12. Emotional disorders in patients with cerebellar damage – case studies

    Directory of Open Access Journals (Sweden)

    Siuda, Katarzyna

    2014-04-01

    Full Text Available Aim: Growing number of research shows the role of the cerebellum in the regulation of affect. Lesions of the cerebellum can lead to emotional disregulation, a significant part of the Cerebellar Cognitive Affective Syndrome. The aim of this article is to analyze the most recent studies concerning the cerebellar participation in emotional reactions and to present three cases: two female and one male who suffered from cerebellar damage and presented post-traumatic affective and personality change. Method: The patients’ neuropsychological examination was performed with Raven’s Progressive Matrices Test – standard version, Trial Making Test, Wisconsin Card Sorting Test, Auditory Verbal Learning Test by Łuria, Benton Visual Retention Test, Verbal Fluency Test, Stroop Interference Test, Attention and Perceptivity Test (Test Uwagi i Spostrzegawczości TUS, Frontal Behavioral Inventory (FBI. Results: The review of the literature suggest cerebellar participation, especially teh vermis and paravermial regions, in the detection, integration and filtration of emotional information and in regulation of autonomic emotional responses. In the described patients we observed: oversensitivity, irritability, impulsivity and self-neglect. The man and the woman with right-sided lesions presented similar symptoms: rigidity of thought, stubbornness, lack of criticism, jocular and inappropriate behavior. The woman with left-sided cerebellar lesion was adynamic, apathic and passive, she presented emotional blunting, social isolation, lack of interests and motivation, general cognitive slowdown. Conclusions: Both the analyzed research and the described cases indicate the connection between the cerebellum and emotion regulation. The symptoms presented by the described patients were most probably a consequence of damaged cerebellar projections to subcortical structures (the limbic system and frontal areas. The diversification of symptoms depending on the localization

  13. Cerebellar infarction in vascular territory of arteria cerebelli superior

    Directory of Open Access Journals (Sweden)

    Savić Dejan

    2010-01-01

    Full Text Available Introduction. Cerebellar vascular diseases are focal cerebrovascular diseases in posterior circulation - vertebrobasilar system. The cerebellum is supplied by three main arteries arising from the vertebrobasilar system: arteria cerebelli inferior posterior, arteria cerebelli inferior anterior and arteria cerebelli superior. Cerebelar infarctions are rare but unpredictable disorders. The aim of this study was determination of main risk factors, clinical presentation and prognosis of the cerebellar infarctions in distal vascular territory of the arteria cerebelli superior. Material and methods. We evaluated 60 patients hospitalized after acute cerebellar infarction among other hospitalized patients in five year period. In 18 patients computerized tomography demonstrated infarction in distal vascular territory of the arteria cerebelli superior. All patients underwent clinical and other diagnostic investigations (computerized tomography, electrocardyography and standard blood tests and were questioned by phone after finishing hospital treatment. Results. Cerebellar infarcts in distal vascular territory of arteria cerebeli superior was 30% of all cerebellar infarcts. The most frequent risk factor was hypertension (66. 7%. Symptomatology and clinical signs were heterogenous but the most frequent were instability (77.8%, vertigo (72.2% and vomiting (55.6% followed by ataxia of the limbs (77.8% and the body (61.1%, nystagmus (55.6% and disarthria (33.3% in clinical presentation. All patients had good recovery in hospital and one year afterwards. Discussion. Infarctions in distribution of arteria cerebelli superior are rare and have multiple risk factors and various clinical features in majority of other studies as in this one. Mass effects are present in several studies but none in this one which reflects contraversions present in other published investigations. Conclusion. Cerebellar infarctions in vascular territory of arteria cerebelli superior have

  14. Recycled Polyamide-6/Waste Silk & Cotton Fibre Polymer Composites:Effect of Fibre length

    OpenAIRE

    TAŞDEMİR, Münir; KOÇAK, Dilara; MERDAN, Nigar; USTA, İsmail; AKALIN, Mehmet

    2013-01-01

    Among textile fibres today, cotton is the most commonly used natural fibre. Cotton is being used in almost all areas of textiles. Waste cotton which is produced during the yarn production process is then re-used in yarn production again or as a waste in other uses. Besides this, silk fibres have been used for nearly 5000 years. Silk is one of the most precious fibres among all textile fibres and it has a very wide range of uses like: sewing threads, clothes, home textiles, technical textiles ...

  15. Scintillating fibre tracking neutron detector

    International Nuclear Information System (INIS)

    A detector for measurements of collimated fluxes of neutrons in the energy range 2-20 MeV is proposed. It utilizes (n.p) elastic scattering in scintillating optical fibres placed in successive orthogonal layers perpendicular to the neutron flux. A test module has been designed, constructed and tested with respect to separation of neutron and gamma events. The pulse height measurements show the feasibility to discriminate between neutron, gamma and background events. Application to measurements of fusion neutrons is considered. 18 refs, 22 figs, 4 tabs

  16. Preserved Glucose Metabolism of Deep Cerebellar Nuclei in a Case of Multiple System Atrophy with Predominant Cerebellar Ataxia: F-18 Fluorodeoxyglucose Positron Emission Tomography Study

    Directory of Open Access Journals (Sweden)

    Oh Dae Kwon

    2010-10-01

    Full Text Available The cerebellar glucose metabolism of multiple system atrophy with predominant cerebellar ataxia (MSA-C is known to be decreased but is not defined among areas of cerebellum. We encountered a 54-year-old man who developed dizziness and progressive ataxia followed by urinary incontinence and orthostatic hypotension, all of those symptoms progressed relentlessly and the symptoms responded poorly to levodopa therapy. Visual analysis and statistical parametric mapping analysis of F-18 fluorodeoxyglucose positron emission tomography showed hypometabolism of both cerebellar hemisphere, severe at cortical area, and pons. There was clear sparing of deep cerebellar nuclei. Our report, as we know, shows the first case of preserved glucose metabolism of deep cerebellar nuclei relative to cerebellar cortex in an MSA-C patient.

  17. Adolescent mice show anxiety- and aggressive-like behavior and the reduction of long-term potentiation in mossy fiber-CA3 synapses after neonatal maternal separation.

    Science.gov (United States)

    Shin, S Y; Han, S H; Woo, R-S; Jang, S H; Min, S S

    2016-03-01

    Exposure to maternal separation (MS) during early life is an identified risk factor for emotional disorders such as anxiety and depression later in life. This study investigated the effects of neonatal MS on the behavior and long-term potentiation (LTP) as well as basic synaptic transmission at hippocampal CA3-CA1 and mossy fiber (MF)-CA3 synapses in adolescent mice for 19days. When mice were adolescents, we measured depression, learning, memory, anxious and aggressive behavior using the forced swimming test (FST), Y-maze, Morris water maze (MWM), elevated plus maze (EPM), three consecutive days of the open field test, the social interaction test, the tube-dominance test and the resident-intruder test. The results showed that there was no difference in FST, Y-maze, and MWM performance. However, MS mice showed more anxiety-like behavior in the EPM test and aggressive-like behavior in the tube-dominance and resident-intruder tests. In addition, the magnitude of LTP and release probability in the MF-CA3 synapses was reduced in the MS group but not in the CA3-CA1 synapse. Our results indicate that early life stress due to MS may induce anxiety- and aggressive-like behavior during adolescence, and these effects are associated with synaptic plasticity at the hippocampal MF-CA3 synapses. PMID:26733385

  18. A novel method for the description of voltage-gated ionic currents based on action potential clamp results - Application to hippocampal mossy fiber boutons

    Directory of Open Access Journals (Sweden)

    John R Clay

    2016-01-01

    Full Text Available Action potential clamp (AP-clamp recordings of the delayed rectifier K+ current IK and the fast-activated Na+ current INa in rat hippocampal mossy fiber boutons (MFBs are analyzed using a computational technique recently reported. The method is implemented using a digitized AP from an MFB and computationally applying that that data set to published models of IK and INa. These numerical results are compared with experimental AP-clamp recordings. The INa result is consistent with experiment; the IK result is not. The difficulty with the IK model concerns the fully activated current-voltage relation, which is described here by the Goldman-Hodgkin-Katz dependence of the driving force (V-EK rather than (V-EK itself, the standard model for this aspect of ion permeation. That revision leads to the second - a much steeper voltage dependent activation curve for IK than the one obtained from normalization of a family of IK records by (V-EK. The revised model provides an improved description of the AP-clamp measurement of IK in MFBs compared with the standard approach The method described here is general. It can be used to test models of ionic currents in any excitable cell. In this way it provides a novel approach to the relationship between ionic currents and membrane excitability in neurons.

  19. Effect of ketogenic diet on hippocampus mossy fiber sprouting and GluR5 expression in kainic acid induced rat model

    Institute of Scientific and Technical Information of China (English)

    XU Xiang-ping; SUN Ruo-peng; JIN Rui-feng

    2006-01-01

    @@ Ketogenic diet (KD) is a high fat, low protein, low carbohydrate diet. Its antiepileptic effect is certain but the underlying mechanism is unknown.1Mossy fiber sprouting in the inner molecular layer of the dentate gyrus causes the synaptic reorganization in the hippocampus, which is an important cause of temporal lobe epilepsy in animals and humans.1,2 It is also essential to the genesis and development of epilepsy. As the predominant excitatory neurotransmitter in the central nervous system, glutamate plays a role in synaptic reorganization and development of epilepsy. In recent years, the role of glutamate receptor 5 (GluR5) in the genesis of seizures has attracted more and more attention of researchers and this receptor has become a candidate target of new antiepileptic drugs.3,4 In this study, we investigated the possible antiepileptic mechanism of KD in terms of synaptic reorganization and GluR5 expression, attempting to provide a theoretical basis for the development of new antiepileptic drugs.

  20. Insertion of optic fibre for CMS

    CERN Multimedia

    Maximilien Brice

    2003-01-01

    The MicroJET system uses high pressure to carefully put the optical fibres into their protective tubes. These fibres are vital for rapid data transfer, but are also very delicate and, if damanged, may not work at the required efficiency. Similiar methods are used to install cables for the telecommunications industry.

  1. low pump power photonic crystal fibre amplifiers

    DEFF Research Database (Denmark)

    Hougaard, Kristian G.; Broeng, Jes; Bjarklev, Anders Overgaard

    2003-01-01

    Designs of low pump power optical amplifiers, based on photonic crystal fibres are presented. The potential of these fibre amplifiers is investigated, and it is demonstrated that such amplifiers may deliver gains of more than 15 dB at 1550 nm with less than 1 mW of optical pump power....

  2. Thermally induced structural changes in Nomex fibres

    Indian Academy of Sciences (India)

    Anjana Jain; Kalyani Vijayan

    2002-08-01

    Thermally aged Nomex fibres manifest several residual effects viz. reduction in X-ray crystallinity, weight loss and deterioration in tensile characteristics. Surface damages in the form of longitudinal openings, holes, material deposits etc have also been observed. Based on the data from thermally exposed fibres, the time needed for states of zero tensile strength and modulus have been predicted.

  3. Durability of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard

    The planned research will indicate, whether fibre reinforced concrete has better or worse durability than normal concrete. Durability specimens will be measured on cracked as well as uncracked specimens. Also the pore structure in the concrete will be characterized.Keywords: Fibre reinforced...... concrete, durability, pore structure, mechanical load...

  4. A novel photonic crystal fibre switch

    OpenAIRE

    Alkeskjold, Thomas Tanggaard; Hermann, D.S.; Broeng, Jes; Bjarklev, Anders Overgaard

    2003-01-01

    A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB.

  5. Recent advances in poled optical fibres

    DEFF Research Database (Denmark)

    Pruneri, V.; Margulis, W.; Myrén, N.; Li, J.; Fage-Pedersen, Jacob; Kristensen, Martin; Belmonte, M.; Kazansky, P.; Corbari, C.; Canagasabey, A.; Deparis, O.; Ferraris, M.; Poumellec, B.; Blum, R.; Liu, Q..; Zhoa, S.; Ortega, B.; Pastor, D.; Martinelli, G.; Kudlinski, A.; Quiquempois, Y.

    A second-order nonlinearity can be induced in optical fibres through poling. We describe accomplishments of the EU project GLAMOROUS in making low-cost high performance electrooptic and nonlinear optical fibre- and waveguide-based components. In particular a comparison with more traditional ferro...... ferroelectric based devices will be presented....

  6. Strength variability of single flax fibres

    DEFF Research Database (Denmark)

    Aslan, Mustafa; Chinga-Carrasco, G.; Sørensen, Bent F.;

    2011-01-01

    –strain behaviours (linear and nonlinear) of the fibres are found to be correlated with the amount of defects. The linear stress–strain curves tend to show a higher tensile strength, a higher Young’s modulus, and a lower strain to failure than the nonlinear curves. Finally, the fibres are found to fracture by a...

  7. Dispersion properties of photonic crystal fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Dridi, Kim;

    1998-01-01

    Approximate dispersion and bending properties of all-silica two-dimensional photonic crystal fibres are characterised by the combination of an effective-index model and classical analysis tools for optical fibres. We believe for the first time to have predicted the dispersion properties of photonic...

  8. Fibre Distribution in Friction-spun Yarns

    Institute of Scientific and Technical Information of China (English)

    Eric Oyondi Nganyi; YU Chong-wen

    2006-01-01

    According to the yarn forming characteristics in friction spinning, the arrangement of fed sliver is designed, to get the desired fiber distribution in the resultant yarn. On the base of that, the relation between the theoretical fibre distribution and the actual fibre distribution is analyzed by use of electron microscope.

  9. Image analysis of insulation mineral fibres.

    Science.gov (United States)

    Talbot, H; Lee, T; Jeulin, D; Hanton, D; Hobbs, L W

    2000-12-01

    We present two methods for measuring the diameter and length of man-made vitreous fibres based on the automated image analysis of scanning electron microscopy images. The fibres we want to measure are used in materials such as glass wool, which in turn are used for thermal and acoustic insulation. The measurement of the diameters and lengths of these fibres is used by the glass wool industry for quality control purposes. To obtain reliable quality estimators, the measurement of several hundred images is necessary. These measurements are usually obtained manually by operators. Manual measurements, although reliable when performed by skilled operators, are slow due to the need for the operators to rest often to retain their ability to spot faint fibres on noisy backgrounds. Moreover, the task of measuring thousands of fibres every day, even with the help of semi-automated image analysis systems, is dull and repetitive. The need for an automated procedure which could replace manual measurements is quite real. For each of the two methods that we propose to accomplish this task, we present the sample preparation, the microscope setting and the image analysis algorithms used for the segmentation of the fibres and for their measurement. We also show how a statistical analysis of the results can alleviate most measurement biases, and how we can estimate the true distribution of fibre lengths by diameter class by measuring only the lengths of the fibres visible in the field of view. PMID:11106965

  10. Neodymium doped chalcogenide glass fibre laser

    OpenAIRE

    Samson, B.N.; Schweizer, T.; Moore, R C; Hewak, D.W.; Payne, D.N.

    1997-01-01

    We report on laser action in a Neodymium doped Gallium Lanthanum Sulphide glass fibre. Laser action at 1080nm was obtained in a 22mm long multimode glass fibre with a neodymium doped core, fabricated by the rod-in-tube technique. The laser was pumped continuous wave with a Ti:sapphire laser at 815nm and showed a self-pulsing behaviour

  11. Winding of fibre composites; Vikling af fiberkompositter

    Energy Technology Data Exchange (ETDEWEB)

    Lystrup, Aage

    2006-01-01

    Within the project 'Storage of hydrogen in advanced high pressure vessels' under the PSO-R AND D 2005 program one of the tasks is to describe the technology, which is used for manufacturing of fibre reinforced pressure vessels. Fibre reinforced pressure vessels for high pressures are manufactured by winding structural load bearing fibres around a mandrel or an internal liner. There are two different types of cylindrical pressure vessels: 1) Cylinders with thick metal liner, where only the cylindrical part is over wrapped with hoop windings, and 2) cylinders with a thin metal or polymer liner, where both the cylindrical part and the end domes are over wrapped with more layers with different fibre orientations (helical and hoop windings). This report describes the fundamental principles for filament winding of fibre reinforced polymer composites. After a short introduction to the advanced fibre composites, their properties and semi-raw materials used for fibre composites, the focus is on the process parameters, which have influence on the material quality of filament wound components. The report is both covering winding of fibre reinforced thermo-setting polymers as well as thermoplastic polymers, and there are references to vendors of filament winding machines, accessory equipment and computer software for design and manufacturing of filament wound components. (au)

  12. CHLORINE DIOXIDE TREATMENT OF SISAL FIBRE: SURFACE LIGNIN AND ITS INFLUENCES ON FIBRE SURFACE CHARACTERISTICS AND INTERFACIAL BEHAVIOUR OF SISAL FIBRE/PHENOLIC RESIN COMPOSITES

    OpenAIRE

    Linxin Zhong; Shiyu Fu; Feng Li; Huaiyu Zhan

    2010-01-01

    This paper describes an investigation of the influences of chlorine dioxide treatment on fibre surface lignin. The fibre surface characteristics and the interfacial behaviour of the sisal fibre/phenolic resin composites were also studied by SEM, AFM, and XPS. The results show that the surface of the untreated fibre contains a large amount of lignin with granular structure and non-granular structure. The surface lignin concentration is up to 51% for the untreated fibre, and then it decreases t...

  13. Fracture characterisation of short bamboo fibre reinforced polyester composites

    International Nuclear Information System (INIS)

    In the study, fracture behaviour of short bamboo fibre reinforced polyester composites is investigated. The matrix is reinforced with fibres ranging from 10 to 50, 30 to 50 and 30 to 60 vol.% at increments of 10 vol.% for bamboo fibres at 4, 7 and 10 mm lengths respectively. The results reveal that at 4 mm of fibre length, the increment in fibre content deteriorates the fracture toughness. As for 7 and 10 mm fibre lengths, positive effect of fibre reinforcement is observed. The optimum fibre content is found to be at 40 vol.% for 7 mm fibre and 50 vol.% for 10 mm fibre. The highest fracture toughness is achieved at 10 mm/50 vol.% fibre reinforced composite, with 340% of improvement compared to neat polyester. Fractured surfaces investigated through the Scanning Electron Microscopy (SEM) describing different failure mechanisms are also reported.

  14. Durability of cracked fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    fibre reinforcement are exposed to a combination of mechanical and environmental load to indicate whether fibre reinforcement will improve the durability of cracked concrete structures. Secondly, it is the aim to identify important mechanisms for the effect of the fibre reinforcement on the durability......Durability studies are carried out at BKM as part of the research project "Design Methods for Fibre Reinforced Concrete" (FRC) involving BKM, The Concrete Research Center at DTI, Building Technology at Aalborg University, Rambøll, 4K-Beton and Rasmussen & Schiøtz. Concrete beams with or without...... pore structure are made on specimens drilled or sawed from beams after unloading (mechanical load). The pore structure of the concretes will be studied by microscopy, sorption and suction curves. The test programme involves three different concrete qualities (water-cement ratios). Both steel fibres (ZP...

  15. Supercontinuum generation in thulium-doped fibres

    Energy Technology Data Exchange (ETDEWEB)

    Kurkov, Andrei S; Kamynin, V A; Tsvetkov, V B; Sadovnikova, Ya E; Marakulin, A V; Minashina, L A

    2012-09-30

    Supercontinuum generation in thulium-doped fibres under pumping at 1.59 {mu}m is investigated. Amplification of supercontinuum in the range of 1.8--2.0 {mu}m is found for a fibre doped to a level of 2 Multiplication-Sign 10{sup 19} cm{sup -3}. For a fibre with an activator concentration of 2 Multiplication-Sign 10{sup 20} cm{sup -3} amplification is also observed in the (2.1 - 2.45)-{mu}m band, which suggests the occurrence of the {sup 3}H{sub 4} {yields} {sup 3}H{sub 5} optical transition in the fibre. The occupation of the {sup 3}H{sub 4} level can be explained by cooperative effects. (optical fibres, lasers and amplifiers. properties and applications)

  16. Simulation of complex phenomena in optical fibres

    CERN Document Server

    Allington-Smith, Jeremy; Lemke, Ulrike

    2012-01-01

    Optical fibres are essential for many types of highly-multiplexed and precision spectroscopy. The success of the new generation of multifibre instruments under construction to investigate fundamental problems in cosmology, such as the nature of dark energy, requires accurate modellisation of the fibre system to achieve their signal-to-noise goals. Despite their simple construction, fibres exhibit unexpected behaviour including non-conservation of Etendue (Focal Ratio Degradation; FRD) and modal noise. Furthermore, new fibre geometries (non-circular or tapered) have become available to improve the scrambling properties that, together with modal noise, limit the achievable SNR in precision spectroscopy. These issues have often been addressed by extensive tests on candidate fibres and their terminations but these are difficult and time-consuming. Modelling by ray-tracing and wave analysis is possible with commercial software packages but these do not address the more complex features, in particular FRD. We use a...

  17. Enhancing the radiation dose detection sensitivity of optical fibres

    International Nuclear Information System (INIS)

    A method for improving the thermoluminescence (TL) yield of silica-based optical fibres is demonstrated. Using silica obtained from a single manufacturer, three forms of pure (undoped) fibre (capillary-, flat-, and photonic crystal fibre (PCF)) and two forms of Ge-doped fibre (capillary- and flat-fibre) were fabricated. The pure fibre samples were exposed to 6 and 21 MeV electrons, the doped fibres to 6 MV photons. The consistent observation of large TL yield enhancement is strongly suggestive of surface-strain defects generation. For 6 MeV irradiations of flat-fibre and PCF, respective TL yields per unit mass of about 12.0 and 17.5 times that of the undoped capillary-fibre have been observed. Similarly, by making a Ge-doped capillary-fibre into flat-fibre, the TL response is found to increase by some 6.0 times. Thus, in addition to TL from the presence of a dopant, the increase in fused surface areas of flat-fibres and PCF is seen to be a further important source of TL. The glow-curves of the undoped fibres have been analysed by computational deconvolution. Trap centre energies have been estimated and compared for the various fibre samples. Two trap centre types observed in capillary-fibre are also observed in flat-fibre and PCF. An additional trap centre in flat-fibre and one further trap centre in PCF are observed when compared to capillary fibre. These elevated-energy trap centres are linked with strain-generated defects in the collapsed regions of the flat fibre and PCF. - Highlights: • Improved TL yield of irradiated silica-based optical fibres. • A range of forms of silica fibre have been fabricated. • Large TL yield enhancement strongly suggests surface-strain defects generation. • Novel forms with TL yields many times that of undoped capillary-fibre

  18. Haemangioblastoma, Histological and immunohistological study of an enigmatic cerebellar tumour

    OpenAIRE

    Cruz-Sánchez, F. F.; Rossi, M L; Rodríguez-Prados, S.; Nakamura, N; Hughes, J T; Coakham, H. B.

    1990-01-01

    Paraffin-embedded blocks of 36 cerebellar haemangioblastomas were reacted with a panel of antibodies including glial fibrillary acidic protein, vimentin, epithelial membrane antigen, cytokeratin, Factor VIII, a neuroendocrine marker and with Ulex europaeus. agglutinin The main histological features, apart from the characteristic large abnormal vessels, were a prominent reticulin network, a cystic architecture and cellular and nuclear polymorphism. Two cell type...

  19. Hippocampo-cerebellar theta band phase synchrony in rabbits.

    Science.gov (United States)

    Wikgren, J; Nokia, M S; Penttonen, M

    2010-02-17

    Hippocampal functioning, in the form of theta band oscillation, has been shown to modulate and predict cerebellar learning of which rabbit eyeblink conditioning is perhaps the most well-known example. The contribution of hippocampal neural activity to cerebellar learning is only possible if there is a functional connection between the two structures. Here, in the context of trace eyeblink conditioning, we show (1) that, in addition to the hippocampus, prominent theta oscillation also occurs in the cerebellum, and (2) that cerebellar theta oscillation is synchronized with that in the hippocampus. Further, the degree of phase synchrony (PS) increased both as a response to the conditioning stimuli and as a function of the relative power of hippocampal theta oscillation. However, the degree of PS did not change as a function of either training or learning nor did it predict learning rate as the hippocampal theta ratio did. Nevertheless, theta band synchronization might reflect the formation of transient neural assemblies between the hippocampus and the cerebellum. These findings help us understand how hippocampal function can affect eyeblink conditioning, during which the critical plasticity occurs in the cerebellum. Future studies should examine cerebellar unit activity in relation to hippocampal theta oscillations in order to discover the detailed mechanisms of theta-paced neural activity. PMID:19945512

  20. Very Preterm Birth, Cerebellar Development and Neuropsychological Outcome in Adolescence

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2008-06-01

    Full Text Available Cerebellar volumes were measured on structural MRI at adolescence and adulthood in 65 preterm individuals (born before 33 weeks’ gestation, and a term-born comparison group, in a study at King’s College, Great Ormond Street Hospital, and University College, London; and Seoul National University College of Medicine, Korea.

  1. Long-Term Sequelae after Cerebellar Astrocytoma Surgery

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-05-01

    Full Text Available The long-term effects on neurologic, neuropsychological, and behavioral functioning in a consecutive series of 23 children treated surgically for cerebellar pilocytic astrocytoma without additional radio- and chemotherapy are determined in a study at Sophia Children’s Hospital, Rotterdam, The Netherlands, and other medical centers.

  2. Cerebellar Control of Locomotion in Health and Disease

    NARCIS (Netherlands)

    M.F. Vinueza Veloz (Maria)

    2015-01-01

    markdownabstract__Abstract__ Modern neuroscience is paving the way for new insight into cerebellar functions including the control of cognitive, autonomic and emotional processes. Yet, how the cerebellum contributes to complex motor behaviors, such as locomotion, is still only partially understood.

  3. Grip-load force coordination in cerebellar patients.

    Science.gov (United States)

    Serrien, D J; Wiesendanger, M

    1999-09-01

    The study examined the anticipatory grip force modulations to load force changes during a drawer-opening task. An impact force was induced by a mechanical stop which abruptly arrested movement of the pulling hand. In performing this task, normal subjects generated a typical grip force profile characterized by an initial force impulse related to drawer movement onset, followed by a ramp-like grip force increase prior to the impending load perturbation. Finally, a reactive response was triggered by the impact. In patients with bilateral cerebellar dysfunction, the drawer-opening task was performed with an alternative control strategy. During pulling, grip force was increased to a high (overestimated) default level. The latter suggests that cerebellar patients were unable to adjust and to scale precisely the grip force according to the load force. In addition, the latency between impact and reactive activity was prolonged in the patients, suggesting an impaired cerebellar transmission of the long-latency responses. In conclusion, these data demonstrate the involvement of cerebellar circuits in both proactive and reactive mechanisms in view of predictable load perturbations during manipulative behavior. PMID:10473743

  4. Cerebellar output controls generalized spike-and-wave discharge occurrence

    NARCIS (Netherlands)

    L. Kros (Lieke); S.J. Eelkman Rooda; J.K. Spanke (Jochen); P. Alva (Parimala); M. van Dongen (Marijn); A. Karapatis (Athanasios); E.A. Tolner (Else A.); C. Strydis (Christos); N. Davey (Neil); B.H.J. Winkelman (Beerend); M. Negrello (Mario); W. Serdijn (Wouter); V. Steuber (Volker); A.M.J.M. Maagdenberg (Arn); C.I. de Zeeuw (Chris); F.E. Hoebeek (Freek)

    2015-01-01

    textabstractObjective Disrupting thalamocortical activity patterns has proven to be a promising approach to stop generalized spike-and-wave discharges (GSWDs) characteristic of absence seizures. Here, we investigated to what extent modulation of neuronal firing in cerebellar nuclei (CN), which are a

  5. Cerebellar Output Controls Generalized Spike-and-Wave Discharge Occurrence

    NARCIS (Netherlands)

    Kros, L.; Eelkman Rooda, O.H.J.; Spanke, J.K.; Alva, P.; Van Dongen, M.N.; Karapatis, A.; Tolner, E.A.; Strydis, C.; Davey, N.; Winkelman, B.H.J.; Negrello, M.; Serdijn, W.A.; Steuber, V.; Van den Maagdenberg, A.M.J.M.; De Zeeuw, C.I.; Hoebeek, F.E.

    2015-01-01

    Objective Disrupting thalamocortical activity patterns has proven to be a promising approach to stop generalized spike-and-wave discharges (GSWDs) characteristic of absence seizures. Here, we investigated to what extent modulation of neuronal firing in cerebellar nuclei (CN), which are anatomically

  6. Cerebellar output controls generalized spike-and-wave discharge occurrence

    NARCIS (Netherlands)

    Kros, Lieke; Eelkman Rooda, Oscar H J; Spanke, Jochen K; Alva, Parimala; van Dongen, Marijn N; Karapatis, Athanasios; Tolner, Else A; Strydis, Christos; Davey, Neil; Winkelman, Beerend H J; Negrello, Mario; Serdijn, Wouter A; Steuber, Volker; van den Maagdenberg, Arn M J M; De Zeeuw, Chris I; Hoebeek, Freek E

    2015-01-01

    OBJECTIVE: Disrupting thalamocortical activity patterns has proven to be a promising approach to stop generalized spike-and-wave discharges (GSWDs) characteristic of absence seizures. Here, we investigated to what extent modulation of neuronal firing in cerebellar nuclei (CN), which are anatomically

  7. Speech and Language Findings Associated with Paraneoplastic Cerebellar Degeneration

    Science.gov (United States)

    Paslawski, Teresa; Duffy, Joseph R.; Vernino, Steven

    2005-01-01

    Paraneoplastic cerebellar degeneration (PCD) is an autoimmune disease that can be associated with cancer of the breast, lung, and ovary. The clinical presentation of PCD commonly includes ataxia, visual disturbances, and dysarthria. The speech disturbances associated with PCD have not been well characterized, despite general acceptance that…

  8. Autosomal recessive cerebellar ataxia with bull's-eye macular dystrophy.

    NARCIS (Netherlands)

    Cruysberg, J.R.M.; Eerola, K.U.; Vrijland, H.R.; Aandekerk, A.L.; Kremer, H.P.H.; Deutman, A.F.

    2002-01-01

    PURPOSE: In 1980, we published in the American Journal of Ophthalmology two siblings with hereditary ataxia and atrophic maculopathy. The report is cited in the literature as autosomal dominant cerebellar ataxia with retinal degeneration. The purpose of the present study is to document the progressi

  9. CLINICOPATHOLOGICAL STUDY OF CEREBELLAR ASTROCYTOMA: REPORT OF THIRTY CASES

    Directory of Open Access Journals (Sweden)

    Murali

    2013-10-01

    Full Text Available ABSTRACT: AIMS: Cerebellar astrocytoma occurs more often in children and young adults than in adults. They are the most common astrocytic tumours in children, accounting for 80 – 85% of cerebellar astrocytomas and 60% of optic gliomas. They comprise about 33% of all posterior fossa tumours in children and represent about 25% of a ll paediatric tumours. The aim of this study was to study the clinicopathological features and analyze the clinical outcome, complications and prognosis of total or subtotal excision of cerebellar astrocytomas . METHODS AND MATERIAL: In the present study, the sex distribution was male predominance: 17 patients were male and 13 were female. The age at diagnosis varied from 4 years to 28 years. 84% of the patients were below 20 years of age. RESULTS AND CONCLUSIONS: H istopathological examinations showed low grade astrocytoma and two cases had malignant tumors which were pilocytic and non pilocytic. Reccur e nce and mortality in the present study showed that 1 patient had recurrence. Out of 30 cases, 2 patients expired (6%. The cause of death was brain stem dys function probably due to brainstem infiltration. In conclusion, the present study may be of importance to clinicians to establish the correct diagnosis and proper therapy about cerebellar astrocytomas.

  10. Post-Plasmodium vivax malaria cerebellar ataxia and optic neuritis: A new form of delayed cerebellar ataxia or cerebellar variant of acute disseminated encephalomyelitis?

    Directory of Open Access Journals (Sweden)

    Gaurav M Kasundra

    2015-01-01

    Full Text Available Acute disseminated encephalomyelitis (ADEM is commonly seen after viral and bacterial infections, immunization, and Plasmodium falciparum (PF malaria. Plasmodium vivax (PV rarely causes ADEM. We report a 14-year-old female patient who presented with acute onset bilateral cerebellar ataxia and optic neuritis, 2 weeks after recovery from PV. Magnetic resonance imaging showed bilateral cerebellar hyperintensities suggestive of ADEM. No specific viral etiology was found on cerebrospinal fluid examination. Patient responded well to treatment without any sequelae. Thus, PV too is an important cause of ADEM along with PF. Two of the previously reported cases had co-infection with falciparum malaria. The only other two reported cases, as also this patient, are from Asia. A geographical or racial predisposition needs to be evaluated. Also, a possibility of post-PV delayed cerebellar ataxia, which is classically described post-PF infection, may be considered as it may be clinically, radiologically, and prognostically indistinguishable from a milder presentation of ADEM.

  11. Effects of fibre content on mechanical properties and fracture behaviour of short carbon fibre reinforced geopolymer matrix composites

    Indian Academy of Sciences (India)

    Tiesong Lin; Dechang Jia; Meirong Wang; Peigang He; Defu Liang

    2009-02-01

    Geopolymer matrix composites reinforced with different volume fractions of short carbon fibres (Cf/geopolymer composites) were prepared and the mechanical properties, fracture behaviour and microstructure of as-prepared composites were studied and correlated with fibre content. The results show that short carbon fibres have a great strengthening and toughening effect at low volume percentages of fibres (3.5 and 4.5 vol.%). With the increase of fibre content, the strengthening and toughening effect of short carbon fibres reduce, possibly due to fibre damage, formation of high shear stresses at intersect between fibres and strong interface cohesion of fibre/matrix under higher forming pressure. The property improvements are primarily based on the network structure of short carbon fibre preform and the predominant strengthening and toughening mechanisms are attributed to the apparent fibre bridging and pulling-out effect.

  12. Effect of Fibre Properties on Flocculation and Fractionation of Cellulosic Fibres in Dry State

    Directory of Open Access Journals (Sweden)

    Jaakko Larkomaa

    2009-12-01

    Full Text Available This paper investigates a fractionation method ofcellulosic fibres in dry state. Although processing ofcellulosic fibres in airstream has been utilised fordecades in airlaid processes, no attempts tofractionate fibres in dry state have been reported. Ourmain goal is to determine how fibre properties andfibre consistency affect fibre flocculation and thus thebehaviour of fibres in fractionation. Also evaluationsof quality and capacity of fractionation operation aremade. Pulp flocculation behaviour is measured withdigital imaging and image recognition techniquebefore and after the fractionation device. A doubleview,orthogonal imaging approach is appliedobtaining statistics of three-dimensional shape,dimensions and coordinates of detected fibre flocs.Fraction and fibre properties are determined withMetso Fractionator and Metso Fiberlab. Results showthat fibre behaviour in a given system stronglydepends on the pulp properties. Flocculation wasfound to be strongly dependent on fibre consistency.Evaluation of fractionation operation was done withhelp of calculations of mass-reject rates andseparation efficiencies. Calculations showed thathighest separation efficiencies can be achieved withsystem when mass-reject rate is between 0.30 and0.40.

  13. Cerebellar and pontine tegmental hypermetabolism in miller-fisher syndrome

    International Nuclear Information System (INIS)

    Miller Fisher syndrome (MFS) has been considered as a variant of Guillain-Barre syndrome (GBS), a type of acute immune neuropathies involving peripheral nerve system. Unlike GBS, presence of cerebellar type ataxia and supranuclear ophthalmioplesia in MFS suggests additional involvement of the central nervous system. To determine involvement of the central nervous system in MFS, we investigated the cerebral metabolic abnormalities in patients with MFS using FDG PET. Nine patients who were diagnosed as MFS based on acute ophthalmoplegia, ataxia, and areflexia without other identifiable causes participated in this study. In six patients, serum antibodies possibly related with symptom of MFS (anti- GQ1b or anti-GM1) were detected at the time of the study. With the interval of 25 26 days (range: 3-83 days) from the symptom on set, brain FDG PET were underwent in patients and compared with those from healthy controls. In group analysis comparing with healthy controls, FDG PET of patients revealed increased metabolism in the bilateral cerebellar hemispheres and vermis, and the thalamus. In contrast, the occipital cortex showed decreased metabolism. Individual analyses disclosed hypermetabolism in the cerebellar vermis or hemispheres in 5, and in the pontine tegmentum in 2 of the 9 patients. We also found that the cerebellar vermian hypermetabolism was inversely correlated with the interval between from the symptom on set to PET study. Moreover, follow-up PET of a patient demonstrated that cerebellar hypermetabolism decreased markedly with an improvement of the ophthalmoplegia and ataxia. These findings indicate an involvement of the central nervous system in MFS and suggest an antibody-associated acute inflammatory process as a mechanism of this disorder

  14. GDNF-induced cerebellar toxicity: A brief review.

    Science.gov (United States)

    Luz, Matthias; Mohr, Erich; Fibiger, H Christian

    2016-01-01

    Recombinant-methionyl human glial cell line-derived neurotrophic factor (GDNF) is known for its neurorestorative and neuroprotective effects in rodent and primate models of Parkinson's disease (PD). When administered locally into the putamen of Parkinsonian subjects, early clinical studies showed its potential promise as a disease-modifying agent. However, the development of GDNF for the treatment of PD has been significantly clouded by findings of cerebellar toxicity after continuous intraputamenal high-dose administration in a 6-month treatment/3-month recovery toxicology study in rhesus monkeys. Specifically, multifocal cerebellar Purkinje cell loss affecting 1-21% of the cerebellar cortex was observed in 4 of 15 (26.7%; 95% confidence interval [CI]: 10.5-52.4%) animals treated at the highest dose level tested (3000μg/month). No cerebellar toxicity was observed at lower doses (450 and 900μg/month) in the same study, or at similar or higher doses (up to 10,000μg/month) in subchronic or chronic toxicology studies testing intermittent intracerebroventricular administration. While seemingly associated with the use of GDNF, the pathogenesis of the cerebellar lesions has not been fully understood to date. This review integrates available information to evaluate potential pathogenic mechanisms and provide a consolidated assessment of the findings. While other explanations are considered, the existing evidence is most consistent with the hypothesis that leakage of GDNF into cerebrospinal fluid during chronic infusions into the putamen down-regulates GDNF receptors on Purkinje cells, and that subsequent acute withdrawal of GDNF generates the observed lesions. The implications of these findings for clinical studies with GDNF are discussed. PMID:26535469

  15. Idiopathic aneurysms of distal cerebellar arteries: endovascular treatment after rupture

    International Nuclear Information System (INIS)

    Idiopathic ruptured aneurysms of distal cerebellar arteries (DCAAs) are rare, and their endovascular therapy (EVT) has as yet not been extensively reported. They are usually assumed to result from local arterial wall disruption rather than infection, unlike distal supratentorial artery aneurysms. This study was performed to audit their frequency, potential aetiology and results of EVT. Using strict inclusion criteria and a database of 1715 EVT patients, we identified ten idiopathic ruptured DCAAs (0.6%) over a 13-year period (1993-2006). The series comprised six males and four females with mean age of 64 years and solitary aneurysms located on posterior inferior cerebellar artery (five patients), anterior inferior cerebellar artery (three patients) and superior cerebellar artery (two patients). Nine aneurysms were fusiform and were treated by endovascular parent artery occlusion, and one was saccular and treated by endosaccular packing. Endovascular therapy was performed with coils in seven cases, n-butyl-2-cyanoacrylate (NBCA) in two cases and with both in one case. Primary EVT was successful in eight patients. One patient died following a procedure-related re-bleeding and one patient required re-treatment after failed endosaccular packing. Nine patients made good or excellent clinical recoveries (modified Rankin Scale 2 or less). Focal cerebellar infarctions were seen on computed tomography images after EVT in three patients, only one of whom was symptomatic with transient dysmetria, which resolved completely during follow up. No aneurysm recanalisation was detected on late follow-up imaging up to 24 months. Ruptured DCAAs are rare. The majority are fusiform in shape and their aetiology remains uncertain. Endovascular treatment is feasible and effective. It usually requires parent artery occlusion. (orig.)

  16. Long lasting cerebellar alterations after perinatal asphyxia in rats.

    Science.gov (United States)

    Campanille, Verónica; Saraceno, G Ezequiel; Rivière, Stéphanie; Logica, Tamara; Kölliker, Rodolfo; Capani, Francisco; Castilla, Rocío

    2015-07-01

    The developing brain may be particularly vulnerable to injury before, at and after birth. Among possible insults, hypoxia suffered as a consequence of perinatal asphyxia (PA) exhibits the highest incidence levels and the cerebellar circuitry appears to be particularly susceptible, as the cellular makeup and the quantity of inputs change quickly during days and weeks following birth. In this work, we have used a murine model to induce severe global PA in rats at the time of birth. Short-term cerebellar alterations within this PA model have been previously reported but whether such alterations remain in adulthood has not been conclusively determined yet. For this reason, and given the crucial cerebellar role in determining connectivity patterns in the brain, the aim of our work is to unveil long-term cerebellum histomorphology following a PA insult. Morphological and cytological neuronal changes and glial reaction in the cerebellar cortex were analyzed at postnatal 120 (P120) following injury performed at birth. As compared to control, PA animals exhibited: (1) an increase in molecular and granular thickness, both presenting lower cellular density; (2) a disarrayed Purkinje cell layer presenting a higher number of anomalous calbindin-stained cells. (3) focal swelling and marked fragmentation of microtubule-associated protein 2 (MAP-2) in Purkinje cell dendrites and, (4) an increase in glial fibrillary acidic protein (GFAP) expression in Bergmann cells and the granular layer. In conclusion, we demonstrate that PA produces long-term damage in cellular histomorphology in rat cerebellar cortex which could be involved in the pathogenesis of cognitive deficits observed in both animals and humans. PMID:26116983

  17. Cerebellar and pontine tegmental hypermetabolism in miller-fisher syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu Kyrong; Kim, Ji Soo; Lee, Won Woo; Kim, Sang Eun [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    2007-07-01

    Miller Fisher syndrome (MFS) has been considered as a variant of Guillain-Barre syndrome (GBS), a type of acute immune neuropathies involving peripheral nerve system. Unlike GBS, presence of cerebellar type ataxia and supranuclear ophthalmioplesia in MFS suggests additional involvement of the central nervous system. To determine involvement of the central nervous system in MFS, we investigated the cerebral metabolic abnormalities in patients with MFS using FDG PET. Nine patients who were diagnosed as MFS based on acute ophthalmoplegia, ataxia, and areflexia without other identifiable causes participated in this study. In six patients, serum antibodies possibly related with symptom of MFS (anti- GQ1b or anti-GM1) were detected at the time of the study. With the interval of 25 26 days (range: 3-83 days) from the symptom on set, brain FDG PET were underwent in patients and compared with those from healthy controls. In group analysis comparing with healthy controls, FDG PET of patients revealed increased metabolism in the bilateral cerebellar hemispheres and vermis, and the thalamus. In contrast, the occipital cortex showed decreased metabolism. Individual analyses disclosed hypermetabolism in the cerebellar vermis or hemispheres in 5, and in the pontine tegmentum in 2 of the 9 patients. We also found that the cerebellar vermian hypermetabolism was inversely correlated with the interval between from the symptom on set to PET study. Moreover, follow-up PET of a patient demonstrated that cerebellar hypermetabolism decreased markedly with an improvement of the ophthalmoplegia and ataxia. These findings indicate an involvement of the central nervous system in MFS and suggest an antibody-associated acute inflammatory process as a mechanism of this disorder.

  18. Comparison of Acoustic Characteristics of Date Palm Fibre and Oil Palm Fibre

    Directory of Open Access Journals (Sweden)

    Lamyaa Abd ALRahman

    2014-02-01

    Full Text Available This study investigated and compared the acoustic characteristics of two natural organic fibres: date palm fibre and oil palm fibre, these materials eligible for acoustical absorption. During the processing stage, both fibre sheets are treated with latex. The two fibres are compressed after latex treatment Circular samples (100 mm in diameter and 28 mm, based on the measurement tube requirements are cut out of the sheets. The density of the date palm fibre sheet is 150 kg/m3 for a 50 mm thickness and 130 kg/m3 for a 30 mm thickness. In contrast, the density of oil palm fibre is 75 kg/m3 for a 50 mm thickness and 65 kg/m3 for a 30 mm thickness. An impedance tube was used to test the thicknesses of both samples based on international standards. The results show that the date palm fibre exhibits two Acoustic Absorption Coefficient (AAC peaks: 0.93 at 1356 Hz and 0.99 at 4200-4353 Hz for the 50-mm-thick sample. In contrast, the 30-mm-thick sample has a single AAC peak of 0.83 at 2381.38-2809.38 Hz. However, the 50-mm-thick oil palm fibre has an AAC peak of 0.75 at 1946.88-2178.13 Hz and the 30-mm-thick oil palm fibre has an acoustic absorption coefficient peak 0.59 at 3225-3712.5 Hz. Thus, the date palm fibre has a higher acoustic absorption coefficient for high and low frequencies than does oil palm fibre. Both fibres are promising for use as sound absorber materials to protect against environmental noise pollution.

  19. Defects in the CAPN1 gene result in alterations in cerebellar development and in cerebellar ataxia in mice and humans

    Science.gov (United States)

    Wang, Yubin; Hersheson, Joshua; Lopez, Dulce; Hamad, Monia Ben; Liu, Yan; Lee, Ka-Hung; Pinto, Vanessa; Seinfeld, Jeff; Wiethoff, Sarah; Sun, Jiandong; Amouri, Rim; Hentati, Faycal; Baudry, Neema; Tran, Jennifer; Singleton, Andrew B; Coutelier, Marie; Brice, Alexis; Stevanin, Giovanni; Durr, Alexandra; Bi, Xiaoning; Houlden, Henry; Baudry, Michel

    2016-01-01

    SUMMARY A CAPN1 missense mutation in Parson Russell Terrier dogs is associated with spinocerebellar ataxia. We now report that homozygous CAPN1 null mutations in humans result in cerebellar ataxia and limb spasticity in four independent pedigrees. Calpain-1 knock-out (KO) mice also exhibit a mild form of ataxia due to abnormal cerebellar development, including enhanced neuronal apoptosis, decreased number of cerebellar granule cells, and altered synaptic transmission. Enhanced apoptosis is due to absence of calpain-1 mediated cleavage of PH domain and Leucine rich repeat Protein Phosphatase 1 (PHLPP1), which results in inhibition of the Akt pro-survival pathway in developing granule cells. Injection of neonatal mice with the indirect Akt activator, bisperoxovanadium, or crossing calpain-1 KO mice with PHLPP1 KO mice prevented increased postnatal cerebellar granule cell apoptosis, and restored granule cell density and motor coordination in adult mice. Thus, mutations in CAPN1 are an additional cause of ataxia in mammals, including humans. PMID:27320912

  20. Improvement of fibre and composites for new markets

    NARCIS (Netherlands)

    Toonen, M.A.J.; Ebskamp, M.J.M.; Kohler, R.

    2007-01-01

    Plant fibres have decisive advantages compared with synthetic fibres. One great advantage of plant fibres is their optimized strength to weight ratio. Others are their better workability as a result of optimum fibre length and cell wall thickness, their high anisotropic qualities and their good ion

  1. Propagation of Light in Photonic Crystal Fibre Devices

    OpenAIRE

    Dabirian, Ali; Akbari, Mahmood; Mortensen, Niels Asger

    2005-01-01

    We describe a semi-analytical approach for three-dimensional analysis of photonic crystal fibre devices. The approach relies on modal transmission-line theory. We offer two examples illustrating the utilization of this approach in photonic crystal fibres: the verification of the coupling action in a photonic crystal fibre coupler and the modal reflectivity in a photonic crystal fibre distributed Bragg reflector.

  2. Chalcogenide-tellurite composite microstructured optical fibre

    Science.gov (United States)

    Kohoutek, T.; Duan, Z.; Kawashima, H.; Yan, X.; Suzuki, T.; Matsumoto, M.; Misumi, Takashi; Ohishi, Y.

    2012-02-01

    We report on fabrication a composite microstructured optical fibre composed of highly nonlinear chalcogenide Ge-Ga- Sb-S glass core and tellurite TeO2-ZnO-Li20-Bi2O3 glass clad. We aimed at obtaining more flattened chromatic dispersion for pumping chalcogenide glass based optical fibre by a pulse laser at current telecommunication wavelengths, i.e. λ = 1.35 - 1.7 μm, which is difficult to achieve by using a single material chalcogenide fibers due to their high refractive index (n > 2.1). A fibre design exploiting a composite of two glasses and one ring of the air holes brings similar options for tuning the fibre dispersion such as use of complex multi rings of air-holes approach. A good choice of glasses, allows for fabricating a composite chalcogenide-tellurite optical fibre benefiting from high nonlinearity of chalcogenide core glass but exploiting a tellurite glass technology and fibre drawing. In the paper, we discuss some aspects of CMOF design concerning current chalcogenide and tellurite glass choice. Also, we show the supercontinuum spectra recorded from current chalcogenide-tellurite CMOF pumped with a custom made femtosecond fibre laser at λ = 1.55 μm with the pulse duration of 400 fs.

  3. Commercial optical fibre as TLD material

    International Nuclear Information System (INIS)

    This work presents a study of commercial SiO2 optical fibre thermoluminescence (TL) properties as part of the efforts within the Dosimetric Application Project at the Physics Inst. of the Univ. of Mexico to develop new radiation detection materials and technologies. The SiO2 commercial optical fibre studied demonstrates useful TL properties and is an excellent candidate for use in TL dosimetry of ionising radiation. The optical fibre's glow curve was observed between 30 and 400 deg. C after exposure to 60Co gamma radiation. One very well-defined glow peak has a maximum at 230 deg. C. The TL response between 100 and 350 deg. C increases monotonically over a wide dose range, from 0.1 Gy to several kGy. It is linear in the range 0.1-3 Gy, which is important for clinical high dose or accident dosimetry. The optical fibre demonstrated high data reproducibility, low residual signal and almost no fading in our study. Moreover, the optical fibre can be re-used several times, after thermal annealing, without any detriment in the dose-response. All these TL characteristics, plus the small size of the 150 μm diameter SiO2 optical fibre, the high flexibility, easy handling and low cost compared with other TL materials, make the commercial optical fibre a very promising TL material for use in research, medicine, industry, reactors, and a variety of other applications. (authors)

  4. Timing tasks synchronize cerebellar and frontal ramping activity and theta oscillations: Implications for cerebellar stimulation in diseases of impaired cognition

    Directory of Open Access Journals (Sweden)

    Krystal Lynn Parker

    2016-01-01

    Full Text Available Timing is a fundamental and highly conserved mammalian capability yet the underlying neural mechanisms are widely debated. Ramping activity of single neurons that gradually increase or decrease activity to encode the passage of time, has been speculated to predict a behaviorally relevant temporal event. Cue-evoked low-frequency activity has also been implicated in temporal processing. Ramping activity and low-frequency oscillations occur throughout the brain and could indicate a network-based approach to timing. Temporal processing requires cognitive mechanisms of working memory, attention, and reasoning which are dysfunctional in neuropsychiatric disease. Therefore, timing tasks could be used to probe cognition in animals with disease phenotypes. The medial frontal cortex and cerebellum are involved in cognition. Cerebellar stimulation has been shown to influence medial frontal activity and improve cognition in schizophrenia. However, the mechanism underlying the efficacy of cerebellar stimulation is unknown. Here we discuss how timing tasks can be used to probe cerebellar interactions with the frontal cortex and the therapeutic potential of cerebellar stimulation. The goal of this theory and hypothesis manuscript is threefold. First, we will summarize evidence indicating that in addition to motor learning, timing tasks involve cognitive processes that are present within both the cerebellum and medial frontal cortex. Second, we propose methodologies to investigate the connections between these areas in patients with Parkinson’s disease, autism, and schizophrenia. We hypothesis that cerebellar transcranial stimulation may rescue medial frontal ramping activity, theta oscillations, and timing abnormalities, thereby restoring executive function in diseases of impaired cognition. These hypotheses could inspire the use of timing tasks as biomarkers for neuronal and cognitive abnormalities in neuropsychiatric disease and promote the therapeutic

  5. Cerebellar Transcranial Direct Current Stimulation (ctDCS): A Novel Approach to Understanding Cerebellar Function in Health and Disease.

    Science.gov (United States)

    Grimaldi, Giuliana; Argyropoulos, Georgios P; Bastian, Amy; Cortes, Mar; Davis, Nicholas J; Edwards, Dylan J; Ferrucci, Roberta; Fregni, Felipe; Galea, Joseph M; Hamada, Masahi; Manto, Mario; Miall, R Chris; Morales-Quezada, Leon; Pope, Paul A; Priori, Alberto; Rothwell, John; Tomlinson, S Paul; Celnik, Pablo

    2016-02-01

    The cerebellum is critical for both motor and cognitive control. Dysfunction of the cerebellum is a component of multiple neurological disorders. In recent years, interventions have been developed that aim to excite or inhibit the activity and function of the human cerebellum. Transcranial direct current stimulation of the cerebellum (ctDCS) promises to be a powerful tool for the modulation of cerebellar excitability. This technique has gained popularity in recent years as it can be used to investigate human cerebellar function, is easily delivered, is well tolerated, and has not shown serious adverse effects. Importantly, the ability of ctDCS to modify behavior makes it an interesting approach with a potential therapeutic role for neurological patients. Through both electrical and non-electrical effects (vascular, metabolic) ctDCS is thought to modify the activity of the cerebellum and alter the output from cerebellar nuclei. Physiological studies have shown a polarity-specific effect on the modulation of cerebellar-motor cortex connectivity, likely via cerebellar-thalamocortical pathways. Modeling studies that have assessed commonly used electrode montages have shown that the ctDCS-generated electric field reaches the human cerebellum with little diffusion to neighboring structures. The posterior and inferior parts of the cerebellum (i.e., lobules VI-VIII) seem particularly susceptible to modulation by ctDCS. Numerous studies have shown to date that ctDCS can modulate motor learning, and affect cognitive and emotional processes. Importantly, this intervention has a good safety profile; similar to when applied over cerebral areas. Thus, investigations have begun exploring ctDCS as a viable intervention for patients with neurological conditions. PMID:25406224

  6. Fibre Optic Protection System for Concrete Structures

    Institute of Scientific and Technical Information of China (English)

    J.S.Leng; A.Hameed; D.Winter; R.A.Barnes; G.C.Mays; G.F.Fernando

    2006-01-01

    The design concepts, modelling and implementation of various fibre optic sensor protection systems for development in concrete structures were investigated. Design concepts and on-site requirements for surface-mounted and embedded optical fibre sensor in concrete were addressed. Finite element (FE) modelling of selected sensor protection systems in strain-transfer efficiency from the structure to the sensing region was also studied. And experimental validation of specified sensor protection system was reported. Results obtained indicate that the protection system for the sensors performs adequately in concrete environment and there is very good correlation between results obtained by the protected fibre optic sensors and conventional electrical resistance strain gauges.

  7. The digitisation of the scintillating fibre detector

    CERN Document Server

    Cogneras, E; van Tilburg, J; de Vries, J

    2014-01-01

    In this note the digitisation of the scintillating fibre detector for the LHCb upgrade is described. The steps for transforming the hits generated by the GEANT simulation into a digital signal are given. The main effects of this detector are described in the simulation code for the LHCb upgrade. In particular, the attenuation of the fibres after irradiation, the geometry of the fibres with respect to the SiPM channels, the gain of the SiPM’s, the thermal noise, the noise from afterpulses and spillover, and the clustering are described. The output is given in the same data format as the one that is expected from the final detector.

  8. Pseudodifferential operators on manifolds with fibred boundaries

    OpenAIRE

    Mazzeo, Rafe; Melrose, Richard B.

    1998-01-01

    Let $X$ be a compact manifold with boundary. Suppose that the boundary is fibred, $\\phi:\\pa X\\longrightarrow Y,$ and let $x\\in\\CI(X)$ be a boundary defining function. This data fixes the space of `fibred cusp' vector fields, consisting of those vector fields $V$ on $X$ satisfying $Vx=O(x^2)$ and which are tangent to the fibres of $\\phi;$ it is a Lie algebra and $\\CI(X)$ module. This Lie algebra is quantized to the `small calculus' of pseudodifferential operators $\\PsiF*(X).$ Mapping propertie...

  9. FibreForm Paper ties (Design)

    OpenAIRE

    Kirkby, John; Battle, Steve; Macqueen, Peter

    2014-01-01

    BillerudKorsnas contracted Design Futures to work with a new paper material they had developed. The material is FibreForm, a paper with an exceptionally high tear strength. BillerudKornas requested our structural design team research the packaging sector and suggest existing packaging solutions that could be replaced with products made from FibreForm. The main features of FibreForm is it is made from sustainable resources and is 100% recyclable. Due to its high burst strength BillerudKornsnas...

  10. Cerebellar contributions to self-motion perception: evidence from patients with congenital cerebellar agenesis.

    Science.gov (United States)

    Dahlem, Kilian; Valko, Yulia; Schmahmann, Jeremy D; Lewis, Richard F

    2016-05-01

    The cerebellum was historically considered a brain region dedicated to motor control, but it has become clear that it also contributes to sensory processing, particularly when sensory discrimination is required. Prior work, for example, has demonstrated a cerebellar contribution to sensory discrimination in the visual and auditory systems. The cerebellum also receives extensive inputs from the motion and gravity sensors in the vestibular labyrinth, but its role in the perception of head motion and orientation has received little attention. Drawing on the lesion-deficit approach to understanding brain function, we evaluated the contributions of the cerebellum to head motion perception by measuring perceptual thresholds in two subjects with congenital agenesis of the cerebellum. We used a set of passive motion paradigms that activated the semicircular canals or otolith organs in isolation or combination, and compared results of the agenesis patients with healthy control subjects. Perceptual thresholds for head motion were elevated in the agenesis subjects for all motion protocols, most prominently for paradigms that only activated otolith inputs. These results demonstrate that the cerebellum increases the sensitivity of the brain to the motion and orientation signals provided by the labyrinth during passive head movements. PMID:26888100

  11. Shrinkage Behaviour of Fibre Reinforced Concrete with Recycled Tyre Polymer Fibres

    OpenAIRE

    Marijana Serdar; Ana Baričević; Marija Jelčić Rukavina; Martina Pezer; Dubravka Bjegović; Nina Štirmer

    2015-01-01

    Different types of fibres are often used in concrete to prevent microcracking due to shrinkage, and polypropylene fibres are among the most often used ones. If not prevented, microcracks can lead to the development of larger cracks as drying shrinkage occurs, enabling penetration of aggressive substances from the environment and reducing durability of concrete structures. The hypothesis of the present research is that polypropylene fibres, used in concrete for controlling formation of microcr...

  12. Influence of Fibre Architecture on Mechanical Properties of Jute Fibre Reinforced Composites

    OpenAIRE

    Hasan, Md Rejaul

    2013-01-01

    Jute fibre reinforced epoxy based composites were manufactured by vacuum bagging method using three different jute fibre structures; woven fabric, non-woven mat and carded sliver. The composites were made using different number of layers of reinforcing materials. Then the tensile test on composite laminates was conducted in different directions of composites according to ASTM D 3039 standards. The tensile properties were evaluated as a function of fibre architecture (woven, non-woven and sliv...

  13. Determining the number of fibre-fibre contacts in cardboard samples using tomographic imaging

    OpenAIRE

    Ekman, Axel

    2011-01-01

    The fibrous network of cardboard samples was studied with the aid of tomographic imaging. For analysing the samples a method of determing the number of contacts between fibres in a planar fibrous network was introduced. The model is based on the fact that deposited paper-like structures tend to have predominantly planar fibre orientation. With this assumption an expression of the mean segment length was derived in terms of the average shortest path along fibres through th...

  14. Changing the properties of natural fibres by coating and of synthetic fibres by infiltration

    OpenAIRE

    Mohamed, Amina Lotfy Owess

    2011-01-01

    The Thesis deals with the development of new concepts for improving the properties of natural and synthetic textile fibres. A natural fibre, cotton, has been chosen as fibrous material. The focus of the modification has been directed towards its handle properties, which usually are improved at the expense of moisture up-take. The silicon based compounds were used for this work. Polylactic acid and polypropylene have been chosen as synthetic fibres whose textile potential is hindered by their ...

  15. The Airy fibre: an optical fibre that guides light diffracted by a circular aperture

    CERN Document Server

    Gris-Sánchez, I; Birks, T A

    2016-01-01

    We have designed and made an optical fibre that guides an approximate Airy pattern as one of its guided modes. The fibre's attenuation was 11.0 dB/km at 1550 nm wavelength, the match between the fibre's mode and the ideal infinite Airy pattern was 93.7%, and the far field resembled a top-hat beam. The guidance mechanism has strong similarities to photonic bandgap guidance.

  16. At immature mossy fibers-CA3 connections, activation of presynaptic GABAB receptors by endogenously released GABA contributes to synapses silencing

    Directory of Open Access Journals (Sweden)

    Victoria F Safiulina

    2009-02-01

    Full Text Available Early in postnatal life correlated GABAergic activity in the hippocampus is thought to play a crucial role in synaptogenesis and in the development of adult neuronal networks. Unlike adulthood, at this developmental stage, mossy fibers (MF which are the axons of granule cells, release GABA into CA3 principal cells and interneurons. Here, we tested the hypothesis that at MF-CA3 connections, tonic activation of GABAB autoreceptors by GABA is responsible for the low probability of release and synapse silencing. Blocking GABAB receptors with CGP55845 enhanced the probability of GABA release and switched on silent synapses while the opposite was observed with baclofen. Both these effects were presynaptic and were associated with changes in paired-pulse ratio and coefficient of variation. In addition, enhancing the extracellular GABA concentration by repetitive stimulation of MF or by blocking the GABA transporter GAT-1, switched off active synapses, an effect that was prevented by CGP55845. In the presence of CGP55845, stimulation of MF induced synaptic potentiation. The shift of EGABA from the depolarizing to the hyperpolarizing direction with bumetanide, a blocker of the cation-chloride co-transporter NKCC1, prevented synaptic potentiation and caused synaptic depression, suggesting that the depolarizing action of GABA observed in the presence of CGP55845 is responsible for the potentiating effect. It is proposed that, activation of GABAB receptors by spillover of GABA from MF terminals reduces the probability of release and contributes to synapses silencing. This would act as a filter to prevent excessive activation of the auto-associative CA3 network and the emergence of seizures.

  17. Detection of aberrant hippocampal mossy fiber connections: Ex vivo mesoscale diffusion MRI and microtractography with histological validation in a patient with uncontrolled temporal lobe epilepsy.

    Science.gov (United States)

    Modo, Michel; Hitchens, T Kevin; Liu, Jessie R; Richardson, R Mark

    2016-02-01

    Understanding the neurobiology and functional connectivity of hippocampal structures is essential for improving the treatment of mesial temporal lobe epilepsy. At the macroscale, in vivo MRI often reveals hippocampal atrophy and decreased fractional anisotropy, whereas at the microscopic scale, there frequently is evidence of neuronal loss and gliosis. Mossy fiber sprouting in the dentate gyrus (DG), with evidence of glutamatergic synapses in the stratum moleculare (SM) putatively originating from granule cell neurons, may also be observed. This aberrant connection between the DG and SM could produce a reverberant excitatory circuit. However, this hypothesis cannot easily be evaluated using macroscopic or microscopic techniques. We here demonstrate that the ex vivo mesoscopic MRI of surgically excised hippocampi can bridge the explanatory and analytical gap between the macro- and microscopic scale. Specifically, diffusion- and T2 -weighted MRI can be integrated to visualize a cytoarchitecture that is akin to immunohistochemistry. An appropriate spatial resolution to discern individual cell layers can then be established. Processing of diffusion tensor images using tractography detects extra- and intrahippocampal connections, hence providing a unique systems view of the hippocampus and its connected regions. Here, this approach suggests that there is indeed an aberrant connection between the DG and SM, supporting the sprouting hypothesis of a reverberant excitatory network. Mesoscopic ex vivo MR imaging hence provides an exciting new avenue to study hippocampi from treatment-resistant patients and allows exploration of existing hypotheses, as well as the development of new treatment strategies based on these novel insights. Hum Brain Mapp 37:780-795, 2016. © 2015 Wiley Periodicals, Inc. PMID:26611565

  18. Shrinkage Behaviour of Fibre Reinforced Concrete with Recycled Tyre Polymer Fibres

    Directory of Open Access Journals (Sweden)

    Marijana Serdar

    2015-01-01

    Full Text Available Different types of fibres are often used in concrete to prevent microcracking due to shrinkage, and polypropylene fibres are among the most often used ones. If not prevented, microcracks can lead to the development of larger cracks as drying shrinkage occurs, enabling penetration of aggressive substances from the environment and reducing durability of concrete structures. The hypothesis of the present research is that polypropylene fibres, used in concrete for controlling formation of microcracks due to shrinkage, can be replaced with recycled polymer fibres obtained from end-of-life tyres. To test the hypothesis, concrete mixtures containing polypropylene fibres and recycled tyre polymer fibres were prepared and tested. Experimental programme focused on autogenous, free, and restrained shrinkage. It was shown that PP fibres can be substituted with higher amount of recycled tyre polymer fibres obtaining concrete with similar shrinkage behaviour. The results indicate promising possibilities of using recycled tyre polymer fibres in concrete products. At the same time, such applications would contribute to solving the problem of waste tyre disposal.

  19. Gauge factors of fibre Bragg grating strain sensors in different types of optical fibres

    International Nuclear Information System (INIS)

    Gauge factors of fibre Bragg grating (FBG)-based strain sensors that had been inscribed into three different types of optical fibres, which differ in core diameters and doping concentrations, were determined at room temperature with high accuracy. Repeated measurements were carried out with several samples of each type of fibre to allow statistical evaluations. For each type, the gauge factors were measured in two configurations: when the bare fibres were glued on a specimen at the location of the FBG and when they were vertically suspended and not bonded to any structure at the location of the FBG. By combining the results of both configurations, the strain transfer ratio of the gluing process and the strain-optic coefficient, peff, of the different types of fibres were determined. The strain-optic coefficient was found to vary up to 1.5% for the different types of optical fibres. The strain transfer ratio was obtained to be close to unity (>99%), showing the high quality of the gluing technique employed. The investigations demonstrate that highly accurate strain sensing is possible with fibre-optic strain sensors. The results are important for the development of accurate and reliable attaching techniques for coated sensor fibres and fibre-optic sensor patches. (paper)

  20. Analysing the nanoporous structure of aramid fibres

    DEFF Research Database (Denmark)

    Pauw, Brian Richard; Vigild, Martin Etchells; Mortensen, Kell;

    2010-01-01

    for validity against the computed scattering pattern for a simulated nanostructure, after which it is used to fit the scattering from the void structure of commercially available heat-treated poly(p-phenylene terephtalamide) fibre and its as-spun precursor fibre. The application shows a reasonable fit...... fibrillar scattering on the scattering pattern. The fit to the scattering pattern of as-spun aramid fibre is improved by the introduction of the large scatterers, while the fit to the scattering pattern obtained from the heat-treated fibre improves when an orientation distribution is taken into account. It...... is concluded that, as a result of the heat treatment, the average width and length of the scatterers increase....

  1. Design of distributed feedback fibre lasers

    DEFF Research Database (Denmark)

    Lauridsen, Vibeke Claudia; Søndergaard, Thomas; Varming, Poul; Povlsen, Jørn Hedegaard

    1997-01-01

    A numerical model for erbium fibre lasers with Bragg gratings is presented. The model is used to optimize the location of a discrete phase-shift and the phase-shift magnitude for a distributed phase-shift....

  2. Durability of cracked fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Nielsen, Laila

    Durability studies are carried out by subjecting FRC-beams to combined mechanical and environmental load. Mechanical load is obtained by exposing beams to il-point bending until a predefined crack width is reached, using a newly developed test setup. As environmental load, exposure to water...... (capillary water uptake) is used, involving an in-situ method and a laboratory method. Three different concrete qualities as well as steel fibres (ZP) and polypropylene fibres (PP) are used. Results of the durability tests on cracked FRC-beams are compared to results for uncracked FRC-beams and beams without...... fibres and the influence of fibres and cracks on the water uptake is discussed....

  3. Optical fibre angle sensor used in MEMS

    International Nuclear Information System (INIS)

    There is a need for displacement and angle measurements in many movable MEMS structures. The use of fibre optical sensors helps to measure micrometre displacements and small rotation angles. Advantages of this type of transducers are their simple design, high precision of processing, low costs and ability of a non-contact measurement. The study shows an analysis of a fibre-optic intensity sensor used for MEMS movable structure rotation angle measurement. An intensity of the light in the photodetector is basically dependent on a distance between a reflecting surface and a head surface of the fibre transmitting arm, and the deflection angle. Experimental tests were made for PMMA 980/1000 plastic fibres, ΘNA=33°. The study shows both analytical and practical results. It proves that calculated and experimental characteristics for the analysed transducers are similar.

  4. Optical fibres bringing the LHC into focus

    CERN Multimedia

    2003-01-01

    New components are being added to CERN's optical fibre network, which will transport the torrents of data produced by the LHC. 1500 kilometres of cables will be installed in the tunnels and at ground level.

  5. Central Tracking Detector Based on Scintillating Fibres

    CERN Multimedia

    2002-01-01

    Scintillating fibres form a reasonable compromise for central tracking detectors in terms of price, resolution, response time, occupancy and heat production. \\\\ \\\\ New fluorescents with large Stokes shifts have been produced, capable of working without wavelength shifters. Coherent multibundles have been developed to achieve high packing fractions. Small segments of tracker shell have been assembled and beam tests have confirmed expectations on spatial resolution. An opto-electronic delay line has been designed to delay the track patterns and enable coincidences with a first level trigger. Replacement of the conventional phosphor screen anode with a Si pixel chip is achieved. This tube is called ISPA-tube and has already been operated in beam tests with a scintillating fibres tracker. \\\\ \\\\ The aim of the proposal is to improve hit densities for small diameter fibres by increasing the fraction of trapped light, by reducing absorption and reflection losses, by reflecting light at the free fibre end, and by inc...

  6. Chinese Market for Fibres and Cables

    Institute of Scientific and Technical Information of China (English)

    Yuxing Zhao

    2003-01-01

    This article presents a summary of Chinese market of optical fibres and cables based on the development of the optical communications industry. Analysis shows that the market will keep growing for sometime in the future.

  7. A cryogenic optical fibre temperature sensor

    OpenAIRE

    Scandale, Walter; Facchini, Massimo; Thévenaz, Luc

    2002-01-01

    A sensor for sensing cryogenic temperatures, which includes an optical fibre(2) and a Brillouin spectral analyser (8) for measuring one or more temperature dependent Brillouin scattering parameters. Once the parameters are measured, they are used to determine the temperature.

  8. Photonic Technologies Integrated into Optical Fibres

    Science.gov (United States)

    Martelli, Cicero; Canning, John

    2008-10-01

    Structured optical fibres are numerically and experimentally assessed with focus on technology integration. Three main areas are considered: Fresnel waveguiding, molecular photonics and photo-diffractive gratings. Results lead to new opportunities for sensors and devices.

  9. Step index fibre using laser interferometer

    Indian Academy of Sciences (India)

    A M Hamed

    2014-03-01

    model is suggested to describe the fringe shift which occurs due to the phase variations of cladded glass fibre introduced between the two plates of the liquid wedge interferometer illuminated with a He–Ne laser. The fringe shift of the phase object which appears in the denominator of the Airy distribution formula of the multiple beam interference is represented in the harmonic term. An experiment is conducted using liquid wedge interferometer where the step index glass fibre of a nearly quadratic thickness variation is introduced between the two plates of the interferometer. The obtained fringe shift shows a good agreement with the proposed quadratic model. The Matlab code is written to plot the interferometer fringes comprising the shift of the step index fibre. Secondly, recognition of elliptical fibres is outlined using tomographic imaging. Finally, results and concluding remarks are given.

  10. Optical Fibre Pressure Sensors in Medical Applications

    Directory of Open Access Journals (Sweden)

    Sven Poeggel

    2015-07-01

    Full Text Available This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based pressure sensors, together with being lightweight and flexible, mean that they are minimally invasive for many medical applications and, thus, particularly suited to in vivo measurement. This means that the sensor can be placed directly inside a patient, e.g., for urodynamic and cardiovascular assessment. This paper presents an overview of the recent developments in optical fibre-based pressure measurements with particular reference to these application areas.

  11. Formation and properties of polyelectrolyte multilayers on wood fibres :  influence on paper strength and fibre wettability

    OpenAIRE

    Lingström, Rikard

    2006-01-01

    The work in this licentiate thesis examines the adsorption of polyelectrolyte multilayers (PEM) onto wood fibres as a new way to influence the properties of the fibre surfaces and hence the fibres. Fundamental aspects of PEM formation on wood fibres have been studied, and discussed in terms of paper strength and wood fibre wettability. PEMs have been formed from three different polymer systems: 1) two strong polyelectrolytes (i.e., fully charged over a wide pH range), polydimethyldiallylammon...

  12. Fibre Body’: The Concept of Fibre in Eighteenth-century Medicine, c.1700–401

    OpenAIRE

    Ishizuka, Hisao

    2012-01-01

    This paper attempts a comprehensive account of ‘fibre medicine’ elaborated by iatromechanists from c. 1700 to c. 1740. Fibre medicine, a medical theory informed by the notion of the fibre, has been neglected by medical historians despite the pivotal role played by the fibre in animal economy. Referring to a wide range of medical fields such as anatomy, physiology, pathology, therapeutics and life sciences, this paper elucidates the ways that the fibre serves as an indispensable concept for ia...

  13. The effect of fibre layering pattern in resisting bending loads of natural fibre-based hybrid composite materials

    OpenAIRE

    Jusoh Muhamad Shahirul Mat; Yahya Mohd Yazid; Hussein Nur Izan Syahriah

    2016-01-01

    The effect of fibre layering pattern and hybridization on the flexural properties of composite hybrid laminates between natural fibres of basalt, jute and flax with synthetic fibre of E-glass reinforced epoxy have been investigated experimentally. Results showed that the effect fibre layering pattern was highly significant on the flexural strength and modulus, which were strongly dependent on the hybrid configuration between sandwich-like (SL) and intercalation (IC) sequence of fibre layers. ...

  14. Angiogenic effect induced by mineral fibres

    International Nuclear Information System (INIS)

    Highlights: → In this study we described the angiogenetic effect of some mineral fibres. → Wollastonite fibres induce blood vessel formation. → The size and shape of the fibres were important factors for the cell signalling. → Wollastonite induce ROS-NFκB activation and EGFR signalling. → Involvement of wollastonite exposure in the development of pathological conditions. -- Abstract: Due to the toxic effect of asbestos, other materials with similar chemical-physical characteristics have been introduced to substitute it. We evaluate the angiogenic effect of certain asbestos substitute fibres such as glass fibres (GFs), ceramic fibres (CFs) and wollastonite fibres (WFs) and then compare angiogenic responses to those induced by crocidolite asbestos fibres (AFs). An in vitro model using human endothelial cells in small islands within a culture matrix of fibroblasts (Angio-Kit) was used to evaluate vessel formation. The release of IL-6, sIL-R6, IL-8, VEGF-A and their soluble receptors, sVEGFR-1, sVEGFR-2, was determined in the conditioning medium of Angio-Kit system after fibre treatment. ROS formation and cell viability were evaluated in cultured endothelial cells (HUVEC). To evaluate the involvement of intracellular mechanisms, EGFR signalling, ROS formation and nuclear factor-κB (NFκB) pathway were then inhibited by incubating HUVEC cells with AG1478, NAC and PDTC respectively, and the cytokine and growth factor release was analyzed in the culture medium after 7 days of fibre incubation. Among the mineral fibres tested, WFs markedly induced blood vessel formation which was associated with release of IL-6 and IL-8, VEGF-A and their soluble receptors. ROS production was observed in HUVEC after WFs treatment which was associated with cell cytotoxicity. The EGFR-induced ERK phosphorylation and ROS-mediated NFκB activation were involved in the cytokine and angiogenic factor release. However, only the EGFR activation was able to induce angiogenesis. The WFs

  15. Elevated temperature concrete curing - using polypropylene fibres

    OpenAIRE

    Richardson, Alan; Coventry, Kathryn; Morgan, Miles

    2011-01-01

    This paper examines cement hydration when concrete cures at elevated temperatures with and without the addition of Type 1 polypropylene fibres and addresses some of the ambiguities that have arisen from previous research. Paired comparison tests were carried out to compare density, strength, pulse velocity, and absorption using plain and fibre concrete at ambient UK indoor temperatures, compared to concrete at elevated temperatures that would be found in The Middle East. The results ...

  16. PASSIVE OPTICAL FIBRE SENSOR FOR REB MEASUREMENT

    Institute of Scientific and Technical Information of China (English)

    王耀才

    1990-01-01

    The paper systematically describes the theoretical research on Cerenkov effect of REB in optical fibres. The analytical expressions for light generation ,collection efficiency ,electron incident angle .the Cerenkov radiation sensitivity of the optical fibre to the current density of the REB stream.and the response of the sensitivity to both electron energy and electron incident angles are given. The typical sensor system for REB measurement is presented. The dynamic range and bandwidth are quantitatively analyzed. The calculation results are illustrated,

  17. Design Methods for Fibre Reinforced Concrete

    DEFF Research Database (Denmark)

    Stang, Henrik

    The present paper describes the outline of a research project on Fibre Reinforced Concrete (FRC) currently being carried out in Denmark under the supervision of Danish Council of Technology, Danish Technical Research Council and Danish Natural Science Research Counsil.......The present paper describes the outline of a research project on Fibre Reinforced Concrete (FRC) currently being carried out in Denmark under the supervision of Danish Council of Technology, Danish Technical Research Council and Danish Natural Science Research Counsil....

  18. Optical fibre devices: vibrometer, current monitor & amplifier

    OpenAIRE

    Laming, Richard Ian

    1989-01-01

    A practical all-fibre laser vibrometer is described. The design has been optimised for hand-held use and incorporates a frequency-scanned laser diode and single-mode optical fibre coupler. Vibration information is extracted by a pseudo-heterodyne technique. The vibrometer is an ideal portable device for machine vibration analysis, since it is insensitive to external vibrations, is robust and lightweight uses inexpensive components and allows access to difficult targets. Performance has been d...

  19. Compressive Failure of Fibre Reinforced Materials

    DEFF Research Database (Denmark)

    Jensen, Henrik Myhre

    2003-01-01

    Compressive failure of uni-directional fibre composites by the kink band mechanism is analysed taking into account effects of residual stresses. Two criteria for determining the strength of the composite material have been investigated: Kink band formation at a bifurcation stress in a composite...... with perfectly aligned fibres, and kink band formation at a peak stress in a composite with a band of imperfect material....

  20. Photonic crystal fibres in the market

    DEFF Research Database (Denmark)

    Broeng, Jes; Laurila, Marko; Noordegraaf, Danny;

    2011-01-01

    Photonic crystal fibres (PCFs) emerged as a research topic in the mid 1990'ies [1]. Today, 15 years later, these fibres are increasing deployed in various commercial markets. Here, we will address three of these markets; medical imaging, materials processing and sensors. We will describe how the...... PCFs provide radical improvements and illustrate the strong diversity in the evolution of PCFs to serve these different markets....

  1. SILK FIBRE DEGRADATION AND ANALYSIS BY PROTEOMICS

    OpenAIRE

    YUKSELOGLU S. Muge; CANOGLU Suat

    2016-01-01

    Silk is one of the promising natural fibres and has a long established history in textile production throughout the centuries. Silk is produced by cultured silk worms, spiders, scorpions, mites and flies. It is extracellular proteinaceous fibres which consist of highly crystalline and insoluble proteins, the fibroins glued with sericin and an amourphous protein. On the other hand, understanding and controlling the degradation of protein materials are important for determining quality and the...

  2. Nanostructured optical fibre tapers and related applications

    OpenAIRE

    Ding, Ming

    2013-01-01

    In the last decade, optical fibre tapers have attracted considerable interest because they offer a variety of enabling properties, including large evanescent fields, flexibility, configurability, high confinement, robustness and compactness. These distinctive features have been exploited in a wealth of applications ranging from telecommunication devices to sensors, from optical manipulation to high-Q resonators. Nanostructures on the optical fibre tapers are very promising since the size of t...

  3. Dynamic response analysis of DFB fibre lasers

    DEFF Research Database (Denmark)

    Yujun, Qian; Varming, Poul; Povlsen, Jørn Hedegaard;

    1998-01-01

    We present a model for relative intensity noise (RIN) in DFB fibre lasers which predicts measured characteristics accurately. Calculation results implies that the RIN decreases rapidly with stronger Bragg grating and higher pump power. We propose here a simplified model based on three spatially...... independent rate equations to describe the dynamic response of erbium doped DFB fibre lasers on pump power fluctuations, using coupled-mode theory to calculate the steady-state hole-burning of the erbium ion inversion...

  4. Endovascular treatment of the posterior inferior cerebellar artery aneurysms

    Energy Technology Data Exchange (ETDEWEB)

    Bradac, G.B.; Bergui, M. [Neuroradiology, Univ. di Torino, Turin (Italy)

    2004-12-01

    Aneurysms may arise at various locations along the course of the posterior inferior cerebellar artery. Brainstem and cranial nerves manipulation make the surgical approach to proximal aneurysms difficult, while the occlusion of the parent vessel is sometimes unavoidable in peripheral aneurysms. Endovascular treatment can be a good alternative, but also with this approach the location of the aneurysm is critical. If occlusion of the parent vessel is planned, anatomical variations and vascular territories of the brainstem should be considered. We report our experience with 18 consecutive aneurysms (12 proximal, 6 peripheral) treated by coils. Complete occlusion was achieved in 14 patients and subtotal in 4. In three patients the parent vessel had to be sacrificed. During treatment two perforations occurred; aneurysms were completely occluded without clinical consequences. Two small asymptomatic cerebellar infarctions were seen on postoperative computed tomography. Clinical outcome was good in 16 patients. (orig.)

  5. Short latency cerebellar modulation of the basal ganglia.

    Science.gov (United States)

    Chen, Christopher H; Fremont, Rachel; Arteaga-Bracho, Eduardo E; Khodakhah, Kamran

    2014-12-01

    The graceful, purposeful motion of our body is an engineering feat that remains unparalleled in robotic devices using advanced artificial intelligence. Much of the information required for complex movements is generated by the cerebellum and the basal ganglia in conjunction with the cortex. Cerebellum and basal ganglia have been thought to communicate with each other only through slow, multi-synaptic cortical loops, begging the question as to how they coordinate their outputs in real time. We found that the cerebellum rapidly modulates the activity of the striatum via a disynaptic pathway in mice. Under physiological conditions, this short latency pathway was capable of facilitating optimal motor control by allowing the basal ganglia to incorporate time-sensitive cerebellar information and by guiding the sign of cortico-striatal plasticity. Conversely, under pathological condition, this pathway relayed aberrant cerebellar activity to the basal ganglia to cause dystonia. PMID:25402853

  6. A Study Of Sporadic Adult Onset Degenerative Cerebellar Ataxias

    Directory of Open Access Journals (Sweden)

    Sinha K K

    1999-01-01

    Full Text Available Twenty-four cases of sporadic olivo-ponto-cerebellar atrophy (OPCA of adult onset were studied over a period of two years. Results suggest that this disorder has its usual onset in the 5th and 6th decade of life with a male: female ratio of 2:1. It manifests clinically with gait ataxia in all, dysarthria, other cerebellar signs and autonomic involvement in vast majority. There were features of basal ganglia involvement in some. No known identifiable environmental cause was found and genetically they are quite distinct from the known autosomal dominant spinocerebellar ataxias though sporadic occurrence in recessive inheritance or a de novo mutation could not be ruled out completely, but it is unlikely.

  7. Cognitive planning deficit in patients with cerebellar atrophy.

    Science.gov (United States)

    Grafman, J; Litvan, I; Massaquoi, S; Stewart, M; Sirigu, A; Hallett, M

    1992-08-01

    We compared the performance of 12 patients with cerebellar atrophy (CA) and 12 normal controls matched for age and education on the Tower of Hanoi, a nine-problem task that requires cognitive planning. CA patients performed significantly worse than controls on this task despite no difference in planning and between-move pause times. A reanalysis of the data using just the subgroup of patients with pure cerebellar cortical atrophy (CCA) (N = 9) replicated the above results and also showed that CCA patients had significantly increased planning times compared with controls. Neither age, sex, education level, severity of dementia, word fluency, response time, memory, nor visuomotor procedural learning predicted CA or CCA performance. This deficit in cognitive planning suggests a functional link between the cerebellum, basal ganglia, and the frontal lobe concerning specific cognitive processes. However, the exact role of the cerebellum in cognitive planning remains undetermined. PMID:1641142

  8. Paraneoplastic cerebellar degeneration in Hodgkin′s lymphoma

    Directory of Open Access Journals (Sweden)

    Vinit Suri

    2012-01-01

    Full Text Available Paraneoplastic cerebellar degeneration (PCD is a rare disorder presenting typically with acute or subacute severe cerebellar ataxia. PCD is most commonly associated with small cell lung cancer followed by adenocarcinoma of breast and ovary, and Hogdkin′s lymphoma. We report a case of a 54-year-old male with acute-onset pancerebellar syndrome with underlying Hodgkin′s lymphoma. A high index of suspicion of PCD resulted in arriving at an early diagnosis of underlying Hodgkin′s disease. The patient was managed with six cycles of chemotherapy, which resulted in clinical stabilization and reversal of magnetic resonance imaging abnormalities. Antitumor therapy appears to have a significant impact on reversing PCD and hence early diagnosis and intervention for the primary remains the corner stone in stabilizing the neurological condition.

  9. Propofol effects on cerebellar long-term depression.

    Science.gov (United States)

    Lee, Kwan Young; Kim, Young Im; Kim, Se Hoon; Park, Hyung Seo; Park, Youn Joon; Ha, Myung Sook; Jin, Yunju; Kim, Dong Kwan

    2015-11-16

    Propofol is an intravenously administered anesthetic that induces γ-aminobutyric acid-mediated inhibition in the central nervous system. It has been implicated in prolonged movement disorders. Since the cerebellum is important for motor coordination and learning, we investigated the potential effects of propofol on cerebellar circuitry. Using the whole-cell patch-clamp technique in Wister rat cerebellar slices, we demonstrated that propofol administration impaired long-term depression from the parallel fiber (PF) to Purkinje cell (PC) synapses (PF-LTD). Also, propofol reduced metabotropic glutamate receptor 1 (mGluR1)-mediated and group I mGluR agonist-induced slow currents in PCs. These results suggest that the propofol-induced PF-LTD impairment may be related to an alteration in mGluR1 signaling, which is essential to motor learning. PMID:26455962

  10. [Atypical cerebellar neurocytoma resembling a hemangioblastoma. A case report].

    Science.gov (United States)

    Lista Martínez, Olalla; Rivas López, Luis Alfredo; Pombo Otero, Jorge Francisco; Amaro Cendón, Santiago; Bravo García, Christian; Villa Fernández, Juan Manuel

    2014-01-01

    Through August 2013, 105 cases of intracranial extraventricular neurocytoma (EVN) had been described; 6% were located in cerebellum and 22% were atypical EVN. A rare morphologic form of neurocytoma, atypical EVN has had only 24 cases reported to date. Its prognosis is poorer than the typical central neurocytoma. This case report describes an atypical cerebellar EVN, a form that has not been reported yet, hence the interest of this article. We emphasise its cystic nature and mural nodule, in an infrequent presentation. EVN are low-incidence tumours that we need to take into consideration when making the differential diagnosis of cystic cerebellar lesions with mural nodule. Given that the prognosis of atypical EVNs depends on the atypical nature and on the grade of resection, medical follow up has to be more constant, due to the greater degree of recurrence. PMID:24837842

  11. Palatoglossal fusion with cleft palate and hypoplasia of cerebellar vermis

    Directory of Open Access Journals (Sweden)

    Shailesh Solanki

    2016-01-01

    Full Text Available A new-born male presented within 12 h of birth with respiratory distress. On examination and workup, he had palatoglossal fusion, cleft palate and hypoplasia of the cerebellar vermis. A 2.5 Fr endotracheal tube was inserted into the pharynx through nostril as a nasopharyngeal stent, following which his respiratory distress improved. Once child was optimised, then feeding was started by nasogastric tube and feeds were tolerated well. Elective tracheostomy and gastrostomy were done, followed by release of adhesions between the tongue and palate at a later stage. Review of literature suggests that palatoglossal fusion is uncommon and presents as an emergency. Mostly, these oral synechiae are associated with digital and/or cardiac anomaly. Other disorders associated with intra-oral synechiae include congenital alveolar synechiae, van der Woude syndrome, popliteal pterygium syndrome and oromandibular limb hypogenesis syndrome. The authors report a hitherto undescribed association of palatoglossal fusion with cleft palate and hypoplasia of the cerebellar vermis.

  12. Crossed cerebellar diaschisis demonstrated by SPECT in hemiplegic children

    International Nuclear Information System (INIS)

    Crossed cerebellar diaschisis (CCD) in twenty five children with hemiplegia were studied using single photon emission computed tomography (SPECT) with N-isopropyl-p-I-123-iodoamphetamine. Seven of twenty-five patients had cerebral palsy, and the others were impaired by acquired brain injury between ten months and fourteen years of age. CCD was demonstrated in five patients (20%), who were impaired by acquired brain injury after seven years of age. CCD could never be detected in patients with cerebral palsy. Ipsilateral cerebellar diaschisis was also demonstrated in two patients with cerebral palsy and three with early acquired brain injury before three years of age. It is suggested that diaschisis presents itself as a different form in a contralateral and ipsilateral cerebellum before three years of age from a form which presents after seven years of age. (author)

  13. Dewatering of fibre suspensions by pressure filtration

    Science.gov (United States)

    Hewitt, Duncan R.; Paterson, Daniel T.; Balmforth, Neil J.; Martinez, D. Mark

    2016-06-01

    A theoretical and experimental study of dewatering of fibre suspensions by uniaxial compression is presented. Solutions of a one-dimensional model are discussed and asymptotic limits of fast and slow compression are explored. Particular focus is given to relatively rapid compression and to the corresponding development of spatial variations in the solidity and velocity profiles of the suspension. The results of complementary laboratory experiments are presented for nylon or cellulose fibres suspended in viscous fluid. The constitutive relationships for each suspension were measured independently. Measurements of the load for different fixed compression speeds, together with some direct measurements of the velocity profiles using particle tracking velocimetry, are compared with model predictions. The comparison is reasonable for nylon, but poor for cellulose fibres. An extension to the model, which allows for a strain-rate-dependent component in the network stress, is proposed, and is found to give a dramatic improvement in the model predictions for cellulose fibre suspensions. The reason for this improvement is attributed to the microstructure of cellulose fibres, which, unlike nylon fibres, are themselves porous.

  14. Reinforcing of Cement Composites by Estabragh Fibres

    Science.gov (United States)

    Merati, A. A.

    2014-04-01

    The influence of Estabragh fibres has been studied to improve the performance characteristics of the reinforced cement composites. The concrete shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of concrete specimens. Although, the Estabragh fibres lose their strength in an alkali environment of cement composites, but, the ability of Estabragh fibres to bridge on the micro cracks in the concrete matrix causes to decrease the width of the cracks on the surface of the concrete samples in comparison with the plain concrete. However, considering the mechanical properties of specimens such as bending strength and impact resistance, the specimens with 0.25 % of Estabragh fibre performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of concrete. Consequently, by adding 0.25 % of Estabragh fibres to the cement composite of concrete, a remarkable improvement in physical and mechanical properties of fibre-containing cement composite is achieved.

  15. Radiation curing of carbon fibre composites

    International Nuclear Information System (INIS)

    Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides a higher uniformity in the network although some slight degradation effects. Mode I delamination fracture toughness and Interlaminar Shear Strength (ISS) were also investigated by means of Double Cantilever Beam (DCB) and Short Beam Shear tests, respectively. Results from this mechanical characterisation allowed to correlate fracture toughness of the bulk matrix resin, cross-linking density and fibre/matrix interaction to the delamination fracture behaviour of the fibre reinforced material. - Highligths: • Epoxy/carbon fibre composites were produced by means of e-beam irradiation. • DMTA analysis pointed out a nonuniformity in the cross-linking degree of the material. • An out-of-mould post irradiation thermal treatment allows a higher uniformity. • Mechanical tests were interpreted on the basis of the cross-linking density and fibre/matrix interaction

  16. Knowledge about dietary fibre: a fibre study framework.

    Science.gov (United States)

    Guiné, Raquel P F; Ferreira, Manuela; Correia, Paula; Duarte, João; Leal, Marcela; Rumbak, Ivana; Barić, Irena C; Komes, Drazenka; Satalić, Zvonimir; Sarić, Marijana M; Tarcea, Monica; Fazakas, Zita; Jovanoska, Dijana; Vanevski, Dragoljub; Vittadini, Elena; Pellegrini, Nicoletta; Szűcs, Viktória; Harangozó, Júlia; El-Kenawy, Ayman; El-Shenawy, Omnia; Yalçın, Erkan; Kösemeci, Cem; Klava, Dace; Straumite, Evita

    2016-09-01

    The objective of this work was to study the degree of knowledge about dietary fibre (DF), as influenced by factors such as gender, level of education, living environment or country. For this, a descriptive cross-sectional study was undertaken on a non-probabilistic sample of 6010 participants from 10 countries in different continents (Europe, Africa and America). The results showed that the participants revealed on average a positive but still low global level of knowledge, which alerts for the need to take some actions to further inform the population about DF and its role as a component of a healthy diet. The results also indicated differences between genders, levels of education, living environments and countries. The highest level of knowledge was revealed by the participants from female gender, with higher education and living in urban areas. Concerning the country, the best informed were the participants from Romania, followed by those from Portugal and Turkey while the least informed were from Egypt. PMID:27263981

  17. A Cerebellar Deficit in Sensorimotor Prediction Explains Movement Timing Variability

    OpenAIRE

    Bo, Jin; Block, Hannah J.; Jane E. Clark; Bastian, Amy J.

    2008-01-01

    A popular theory is that the cerebellum functions as a timer for clocking motor events (e.g., initiation, termination). Consistent with this idea, cerebellar patients have been reported to show greater deficits during hand movements that repeatedly start and stop (i.e., discontinuous movements) compared with continuous hand movements. Yet, this finding could potentially be explained by an alternate theory in which the cerebellum acts as an internal model of limb mechanics. We tested whether a...

  18. Acute cerebellar ataxia: A neurological manifestation in malaria

    Directory of Open Access Journals (Sweden)

    Peddametla Shravan Kumar

    2014-01-01

    Full Text Available Malaria is a vector-borne disease transmitted by the bite of an infected female anopheles mosquito presents with varied clinical manifestations. Neurological manifestations include headaches, confusion, convulsions, hemiplegia, ataxia, cerebral palsy, cortical blindness, and Guillain-Barre syndrome (GBS. We are presenting a case report of acute cerebellar ataxia in a 20-year-old male patient who presented with fever and positive for Plasmodium vivax and Plasmodium falciparum malaria antibodies.

  19. Cerebellar Control of Locomotion in Health and Disease

    OpenAIRE

    Vinueza Veloz, Maria

    2015-01-01

    markdownabstract__Abstract__ Modern neuroscience is paving the way for new insight into cerebellar functions including the control of cognitive, autonomic and emotional processes. Yet, how the cerebellum contributes to complex motor behaviors, such as locomotion, is still only partially understood. Here, we have investigated the contribution of the cerebellum to locomotion from the perspective of studies performed on mutant mouse lines generated through genetic engineering techniques. Specifi...

  20. Cerebellar Herniation after Lumbar Puncture in Galactosemic Newborn

    Directory of Open Access Journals (Sweden)

    Salih Kalay

    2011-09-01

    Full Text Available Cerebral edema resulting in elevated intracranial pressure is a well-known complication of galactosemia. Lumbar puncture was performed for the diagnosis of clinically suspected bacterial meningitis. Herniation of cerebral tissue through the foramen magnum is not a common problem in neonatal intensive care units because of the open fontanelle in infants. We present the case of a 3-week-old infant with galactosemia who presented with signs of cerebellar herniation after lumbar puncture.

  1. Cerebellar Herniation after Lumbar Puncture in Galactosemic Newborn

    OpenAIRE

    Salih Kalay; Osman Öztekin; Gönül Tezel; Hakan Demirtaş; Mustafa Akçakuş; Nihal Oygür

    2011-01-01

    Cerebral edema resulting in elevated intracranial pressure is a well-known complication of galactosemia. Lumbar puncture was performed for the diagnosis of clinically suspected bacterial meningitis. Herniation of cerebral tissue through the foramen magnum is not a common problem in neonatal intensive care units because of the open fontanelle in infants. We present the case of a 3-week-old infant with galactosemia who presented with signs of cerebellar herniation after lumbar puncture.

  2. Mapping the development of cerebellar Purkinje cells in zebrafish.

    Science.gov (United States)

    Hamling, Kyla R; Tobias, Zachary J C; Weissman, Tamily A

    2015-11-01

    The cells that comprise the cerebellum perform a complex integration of neural inputs to influence motor control and coordination. The functioning of this circuit depends upon Purkinje cells and other cerebellar neurons forming in the precise place and time during development. Zebrafish provide a useful platform for modeling disease and studying gene function, thus a quantitative metric of normal zebrafish cerebellar development is key for understanding how gene mutations affect the cerebellum. To begin to quantitatively measure cerebellar development in zebrafish, we have characterized the spatial and temporal patterning of Purkinje cells during the first 2 weeks of development. Differentiated Purkinje cells first emerged by 2.8 days post fertilization and were spatially patterned into separate dorsomedial and ventrolateral clusters that merged at around 4 days. Quantification of the Purkinje cell layer revealed that there was a logarithmic increase in both Purkinje cell number as well as overall volume during the first 2 weeks, while the entire region curved forward in an anterior, then ventral direction. Purkinje cell dendrites were positioned next to parallel fibers as early as 3.3 days, and Purkinje cell diameter decreased significantly from 3.3 to 14 days, possibly due to cytoplasmic reappropriation into maturing dendritic arbors. A nearest neighbor analysis showed that Purkinje cells moved slightly apart from each other from 3 to 14 days, perhaps spreading as the organized monolayer forms. This study establishes a quantitative spatiotemporal map of Purkinje cell development in zebrafish that provides an important metric for studies of cerebellar development and disease. PMID:25655100

  3. Patterns of regional cerebellar atrophy in genetic frontotemporal dementia

    Directory of Open Access Journals (Sweden)

    Martina Bocchetta

    2016-01-01

    Conclusion: There appears to be a differential pattern of cerebellar atrophy in the major genetic forms of FTD, being relatively spared in GRN, localized to the lobule VIIa-Crus I in the superior-posterior region of the cerebellum in C9orf72, the area connected via the thalamus to the prefrontal cortex and involved in cognitive function, and localized to the vermis in MAPT, the ‘limbic cerebellum’ involved in emotional processing.

  4. Relationship Between Essential Tremor and Cerebellar Dysfunction According to Age

    OpenAIRE

    Lim, Eui-Seong; Seo, Man-Wook; Woo, Seong-Ryong; Jeong, Suk-Young; Jeong, Seul-Ki

    2005-01-01

    Background The cerebellum and its neural circuitry have been assumed to play a major role in the pathophysiology of essential tremor (ET). In this study, we sought to find associations between ET and cerebellar dysfunction. Methods We performed tandem gait test in 41 ET patients and 44 age-matched controls. Investigators assessed tandem gait by counting the number of missteps during ten-step tandem walk and each subject repeated the trial three times. Results ET patients had a higher average ...

  5. Atypical cerebral and cerebellar language organisation: a case study

    OpenAIRE

    Dun, Kim; Witte, Elke; Daele, Wendy Van; Van Hecke, Wim; Manto, Mario; Mariën, Peter

    2015-01-01

    Background In the majority of right-handed subjects, language processing is subserved by a close interplay between the left cerebral hemisphere and right cerebellum. Within this network, the dominant fronto-insular region and the contralateral posterior cerebellum are crucially implicated in oral language production. Case Presentation We report atypical anatomoclinical findings in a right-handed patient with an extensive right cerebellar infarction and an older left fronto-insular stroke. Sta...

  6. Distal posterior inferior cerebellar artery aneurysm in a child

    OpenAIRE

    J. FRANCISCO SALOMÃO; René D. Leibinger; Yara M. S. Lima Ciro de A. Cunha; Ilton G. Shinzato; Paulo de T. L. Dantas

    1992-01-01

    The case of a 7-year-old boy presenting with recurrent episodes of subarachnoid hemorrhage due to a distal posterior inferior cerebellar artery aneurysm (PICA), successfully operated, is reported.' The low incidence of intracranial aneurysms in the first decade of life and the rare occurrence of distal PICA aneurysms are unusual features of this case. The theories regarding the origin of intracranial berry aneurysms are discussed.

  7. Direct transcranial puncture for Onyx embolization of a cerebellar hemangioblastoma.

    Science.gov (United States)

    Ding, Dale; Starke, Robert M; Evans, Avery J; Liu, Kenneth C

    2014-06-01

    Intracranial hemangioblastomas are benign but hypervascular tumors, most commonly located in the cerebellum, which are difficult to resect without significant operative blood loss. While preoperative embolization may decrease the amount of operative bleeding, the vascular supply of cerebellar hemangioblastomas frequently precludes safe embolization by an endovascular route due to the risk of thromboembolic vertebrobasilar infarction. Direct puncture embolization overcomes many of the limitations of endovascular embolization but its safety and feasibility for intracranial tumors is unknown. We report a 48-year-old man who was diagnosed with a large cerebellar mass after presenting with headaches and gait ataxia. Based on diagnostic angiography, which demonstrated a highly vascular tumor supplied by the posterior inferior cerebellar and posterior meningeal arteries, we decided to embolize the tumor by a direct transcranial puncture approach. After trephinating the skull in a standard fashion, a catheter-needle construct, composed of an Echelon 10 microcatheter (ev3 Endovascular, Plymouth, MN, USA) placed into a 21-gauge spinal needle, was inserted into the tumor under biplanar angiographic guidance. Using continuous angiographic monitoring, 9cc of Onyx 34 (ev3 Endovascular) was injected through the catheter, resulting in 75% tumor devascularization without evidence of complications. The patient was taken directly to surgery where a gross total resection of the hemangioblastoma was achieved with an acceptable operative blood loss. At his 2 year follow-up, the patient was neurologically intact without neuroimaging evidence of residual tumor. We describe, to our knowledge, the first case of direct transcranial puncture for preoperative embolization of a cerebellar hemangioblastoma. PMID:24370504

  8. [Cerebellar hemangioblastoma and thrombocytopenia: Report of one case].

    Science.gov (United States)

    Patiño G, Santiago

    2016-04-01

    The association between vascular tumors and thrombocytopenia is rare. Kasabach-Merritt Syndrome is seen in childhood and is characterized by hemangiomas and thrombocytopenia. A 42 years-old man with a cerebellar hemangioblastoma and thrombocytopenia, admitted with a subarachnoid hemorrhage is reported. The patient was operated and required a splenectomy to manage the thrombocytopenia. After the splenectomy the patient developed a subdural hematoma that was operated. Despite the surgical treatment, the patient died. PMID:27401386

  9. Cerebellar Hemangioblastoma: Four Case Reports and Review of the Literature

    OpenAIRE

    Sevgi Bakaris; Muruvet Yuksel

    2015-01-01

    Hemangioblastoma (HB) is a benign, slow-growing, highly vascular tumour of not well defined histological origin. These tumors make up about 1 to 2 percent of all intracranial neoplasms and occur primarily in the posterior fossa. Hemangioblastomas can occur sporadically but in about 20% to 30% cases, it is associated with von Hippel-Lindau (VHL) disease. Four cases of cerebellar haemangioblastoma, not associated with von Hippel-Lindau disease (sporadic haemangioblastomas), were presented and r...

  10. Intratumoral Hemorrhage in a Patient With Cerebellar Hemangioblastoma

    OpenAIRE

    Wang, Zhen; Hu, Jun; Xu, Liang; Malaguit, Jay; Chen, Sheng

    2015-01-01

    Abstract Spontaneous hemorrhage is rarely associated with hemangioblastomas. Intratumoral hemorrhage occurring in cerebellar hemangioblastomas is more rare. A 25-year-old man was admitted to our hospital with headache. We found a round cystic lesion with solid part in the right cerebellum. The lesion was resected. The final pathological diagnosis was hemangioblastomas. The radiological features of this case were similar to normal hemangioblastomas, whereas our histological examination showed ...

  11. Lissencephaly-pachygyria and cerebellar hypoplasia in a calf

    OpenAIRE

    Bianca Lemos dos Santos; Maria Cecília Florisbal Damé; Ana Carolina Barreto Coelho; Plínio Aguiar de Oliveira; Clairton Marcolongo-Pereira; Ana Lucia Schild

    2016-01-01

    ABSTRACT: A case of lissencephaly-pachygyria and cerebellar hypoplasia diagnosed in a Charolais x Tabapuã calf is described. The calf presented since birth, clinical signs characterized by apathy, prolonged recumbency, tremors of the head and neck, ataxia, hypermetria, difficulty walking, blindness and swelling of the joints of the four limbs. Due to the unfavorable prognosis, the animal was euthanized and necropsied at 34 days of age. At necropsy, a rudimentary development of the brain folds...

  12. Consensus paper on post-operative pediatric cerebellar mutism syndrome

    DEFF Research Database (Denmark)

    Gudrunardottir, Thora; Morgan, Angela T; Lux, Andrew L;

    2016-01-01

    INTRODUCTION: Confusion has surrounded the description of post-operative mutism and associated morbidity in pediatric patients with cerebellar tumors for years. The heterogeneity of definitions and diagnostic features has hampered research progress within the field, and to date, no international...... and follow-up. METHODS: Consensus was obtained using the modified nominal group technique, involving four rounds of online Delphi questionnaires interspersed with a structured consensus conference with lectures, group work, and open discussion sessions. RESULTS: A new, proposed definition of "post...

  13. Imaging Spectrum of Cerebellar Pathologies: A Pictorial Essay

    International Nuclear Information System (INIS)

    The cerebellum is a crucial structure of hindbrain which helps in maintaining motor tone, posture, gait and also coordinates skilled voluntary movements including eye movements. Cerebellar abnormalities have different spectrum, presenting symptoms and prognosis as compared to supratentorial structures and brainstem. This article intends to review the various pathological processes involving the cerebellum along with their imaging features on MR, which are must to know for all radiologists, neurologists and neurosurgeons for their prompt diagnosis and management

  14. Phenytoin-induced cerebellar atrophy in an epileptic boy

    Directory of Open Access Journals (Sweden)

    Nithin Kumar

    2013-01-01

    Full Text Available Epilepsy is an important health problem due to its high prevalence and potential for causing long-term morbidity. It is commonly treated in children with phenytoin sodium. It has wide pharmacokinetic variability and a narrow therapeutic range that leads to toxicity. Here, we report a case of phenytoin-induced cerebellar atrophy in a 16-year-old epileptic boy who presented to the hospital with a viral infection.

  15. Extra-Axial Medulloblastoma in the Cerebellar Hemisphere

    OpenAIRE

    Chung, Eui Jin; Jeun, Sin Soo

    2014-01-01

    Extra-axial medulloblastoma is a rare phenomenon. We report a case in a 5-year-old boy who presented with nausea, vomiting, and gait disturbance. He was treated with total removal of the tumor. This is the first case of an extra-axially located medulloblastoma occurring in the cerebellar hemisphere posteriolateral to the cerebellopontine angle in Korea. Although the extra-axial occurrence of medulloblastoma is rare, it should be considered in the differential diagnosis of extra-axial lesions ...

  16. Modulating basal ganglia and cerebellar activity to suppress parkinsonian tremor

    OpenAIRE

    Heida, T.; Zhao, Yan; Wezel, van, H.B.

    2013-01-01

    Despite extensive research, the detailed pathophysiology of the parkinsonian tremor is still unknown. It has been hypothesized that the generation of parkinsonian tremor is related to abnormal activity within the basal ganglia. The cerebello-thalamic-cortical loop has been suggested to indirectly contribute to the expression of parkinsonian tremor. However, the observed tremor-related hyperactivity in the cerebellar loop may have a compensatory rather than a causal role in Parkinson's disease...

  17. Fibre agglomerate transport in a horizontal flow

    International Nuclear Information System (INIS)

    Loss of coolant accidents in the primary circuit of pressure and boiling water reactors can cause the damage of adjacent insulation materials. These materials may then find their way to the containment sump where water is drawn into the ECCS (emergency core cooling system). Strainers in the containment sump may become fully or partially blocked by the insulation materials. The consequences of such blockages are an increased pressure drop acting on the operating ECCS pumps. If the strainers are partially blocked smaller particles can also penetrate the strainers. These smaller particles can therefore enter the reactor coolant system and then accumulate in the reactor pressure vessel. An experimental and theoretical study that concentrates on mineral wool fibre transport in the containment sump and the ECCS is being performed. The study entails the generation of fibre agglomerates and the assessment of their transport in single and multi-effect experiments. The experiments include measurement of the terminal settling velocity, the strainer pressure drop, fibre sedimentation and resuspension in a channel flow, jet flow in a rectangular tank and the importance of chemical effects on any filter cake formed on the strainer. An integrated test facility is also operated to assess the compounded effects. Each experimental facility is used to provide data for the validation of equivalent computational fluid dynamic models. The channel flow facility allows the determination of the steady state distribution of the fibres at different flow velocities. The channel has a racetrack configuration with nine straight sections (1 m by 1 m by 0.1 m) and two 90 deg. bends with a radius of 0.5 m to the channel midpoint. The height of the bends is also 1 m and the channel width is 0.1 m. An elliptical section located upstream of one of the bends is used to house the impellers, which drives the flow into the next bend. Laser Doppler anemometry, particle image velocimetry, ultrasound

  18. Paraneoplastic cerebellar degeneration with anti-Yo antibodies - a review.

    Science.gov (United States)

    Venkatraman, Anand; Opal, Puneet

    2016-08-01

    The ataxic syndrome associated with Anti-Yo antibody, or Purkinje cell cytoplasmic antibody type 1 (PCA1), is the most common variant of paraneoplastic cerebellar degeneration (PCD). The typical presentation involves the subacute development of pancerebellar deficits with a clinical plateau within 6 months. The vast majority of cases have been reported in women with pelvic or breast tumors. Magnetic resonance imaging of the brain is often normal in the early stages, with cerebellar atrophy seen later. The underlying mechanism is believed to be an immunological reaction to cerebellar degeneration-related protein 2 (CDR2), a protein usually found in the cerebellum that is ectopically produced by tumor cells. Although both B- and T-cell abnormalities are seen, there is debate about the relative importance of the autoantibodies and cytotoxic T lymphocytes in the neuronal loss. Cerebrospinal fluid abnormalities, primarily elevated protein, lymphocytic pleocytosis, and oligoclonal bands, are common in the early stages. The low prevalence of this condition has not allowed for large-scale randomized controlled trials. Immunotherapies, such as steroids, intravenous immune globulins, and plasma exchange, have been extensively used in managing this condition, with limited success. Although some reports indicate benefit from antitumor therapies like surgery and chemotherapy, this has not been consistently observed. The prognosis for anti-Yo PCD is almost uniformly poor, with most patients left bedridden. Further studies are required to clarify the pathophysiology and provide evidence-based treatment options. PMID:27606347

  19. Magnetic resonance imaging in the diagnosis of cerebellar ataxias

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Hiroyuki; Takase, Sadao; Mochizuki, Hiroshi; Kogure, Kyuya; Yamada, Kenji; Hishinuma, Takashi; Matsuzawa, Taiju.

    1987-11-01

    Radiological evaluation in order to quantitatively analyse the size of structures in the posterior fossa using magnetic resonance imaging (MRI) was performed in the patients with spinocerebellar degeneration (SCD). The subjects consisted of 17 patients including 11 OPCA (olivopontocerebellar atrophy)-type and 6 LCCA (late cortical cerebellar atrophy)-type SCD patients, and their disease was in the initial phase. Using a mid-line sagittal view, quantitative measurements of the cerebellum, pons and the medulla oblongata were performed. In the OPCA-type SCD patients, the area, and the longitudinal and anteroposterior diameters of the cerebellar vermis, the area and the anteroposterior diameter of the pons, the height of the fourth ventricle, and the anteroposterior diameter of the medulla oblongata were significantly smaller than those of normal subjects. In the LCCA-type SCD patients, only the area and the anteroposterior diameter of the cerebellar vermis were smaller than those of the normal. As a result, MRI is useful in the diagnosis of SCD, and in the differential diagnosis between the OPCA-type and the LCCA-type SCDs.

  20. Deficits in reflexive covert attention following cerebellar injury.

    Science.gov (United States)

    Striemer, Christopher L; Cantelmi, David; Cusimano, Michael D; Danckert, James A; Schweizer, Tom A

    2015-01-01

    Traditionally the cerebellum has been known for its important role in coordinating motor output. Over the past 15 years numerous studies have indicated that the cerebellum plays a role in a variety of cognitive functions including working memory, language, perceptual functions, and emotion. In addition, recent work suggests that regions of the cerebellum involved in eye movements also play a role in controlling covert visual attention. Here we investigated whether regions of the cerebellum that are not strictly tied to the control of eye movements might also contribute to covert attention. To address this question we examined the effects of circumscribed cerebellar lesions on reflexive covert attention in a group of patients (n = 11) without any gross motor or oculomotor deficits, and compared their performance to a group of age-matched controls (n = 11). Results indicated that the traditional RT advantage for validly cued targets was significantly smaller at the shortest (50 ms) SOA for cerebellar patients compared to controls. Critically, a lesion overlap analysis indicated that this deficit in the rapid deployment of attention was linked to damage in Crus I and Crus II of the lateral cerebellum. Importantly, both cerebellar regions have connections to non-motor regions of the prefrontal and posterior parietal cortices-regions important for controlling visuospatial attention. Together, these data provide converging evidence that both lateral and midline regions of the cerebellum play an important role in the control of reflexive covert visual attention. PMID:26300756

  1. Deficits in reflexive covert attention following cerebellar injury.

    Directory of Open Access Journals (Sweden)

    Christopher eStriemer

    2015-08-01

    Full Text Available Traditionally the cerebellum has been known for its important role in coordinating motor output. Over the past fifteen years numerous studies have indicated that the cerebellum plays a role in a variety of cognitive functions including working memory, language, perceptual functions, and emotion. In addition, recent work suggests that regions of the cerebellum involved in eye movements also play a role in controlling covert visual attention. Here we investigated whether regions of the cerebellum that are not strictly tied to the control of eye movements might also contribute to covert attention. To address this question we examined the effects of circumscribed cerebellar lesions on reflexive covert attention in a group of patients (n=11 without any gross motor or oculomotor deficits, and compared their performance to a group of age-matched controls (n=11. Results indicated that the traditional RT advantage for validly cued targets was significantly smaller at the shortest (50ms SOA for cerebellar patients compared to controls. Critically, a lesion overlap analysis indicated that this deficit in the rapid deployment of attention was linked to damage in Crus I and Crus II of the lateral cerebellum. Importantly, both cerebellar regions have connections to non-motor regions of the prefrontal and posterior parietal cortices – regions important for controlling visuospatial attention. Together, these data provide converging evidence that both lateral and midline regions of the cerebellum play an important role in the control of reflexive covert visual attention.

  2. Ataxia-telangiectasia: the pattern of cerebellar atrophy on MRI

    International Nuclear Information System (INIS)

    We describe MRI of the brain in 19 patients with ataxia-telangiectasia (AT) and correlate the appearances with the degree of neurologic deficit. We examined 10 male and nine female patients; 17 were aged between 2 and 12 years (mean 8 years) but a woman and her brother were 35 and 38 years old, and had a variant of AT. Ataxia was the first recognized sign of the disease in every patient. We detected the following patterns of cerebellar atrophy: in the youngest patient, aged 2 years, the study was normal; in the five next youngest patients 3-7 years of age, the lateral cerebellum and superior vermis showed the earliest changes of atrophy; and all but one of the other patients had moderate to marked diffuse atrophy of vermis and cerebellar hemispheres. There were 12 patients aged 9 years and above; one, who was normal, was 9 years old. The five patients who at the time of examination were unable to walk all had diffuse atrophy involving both vermis and cerebellar hemispheres. (orig.)

  3. Ataxia-telangiectasia: the pattern of cerebellar atrophy on MRI

    Energy Technology Data Exchange (ETDEWEB)

    Tavani, F. [Department of Radiology, University of Modena (Italy); Zimmerman, R.A.; Gatti, R.; Bingham, P. [Department of Radiology, Children' s Hospital of Philadelphia, 34th Street and Civic Center Boulevard, PA 19104, Philadelphia (United States); Berry, G.T. [Department of Endocrinology, Children' s Hospital of Philadelphia, 34th Street and Civic Center Boulevard, PA 19104, Philadelphia (United States); Sullivan, K. [Department of Immunology, Children' s Hospital of Philadelphia, 34th Street and Civic Center Boulevard, PA 19104, Philadelphia (United States)

    2003-05-01

    We describe MRI of the brain in 19 patients with ataxia-telangiectasia (AT) and correlate the appearances with the degree of neurologic deficit. We examined 10 male and nine female patients; 17 were aged between 2 and 12 years (mean 8 years) but a woman and her brother were 35 and 38 years old, and had a variant of AT. Ataxia was the first recognized sign of the disease in every patient. We detected the following patterns of cerebellar atrophy: in the youngest patient, aged 2 years, the study was normal; in the five next youngest patients 3-7 years of age, the lateral cerebellum and superior vermis showed the earliest changes of atrophy; and all but one of the other patients had moderate to marked diffuse atrophy of vermis and cerebellar hemispheres. There were 12 patients aged 9 years and above; one, who was normal, was 9 years old. The five patients who at the time of examination were unable to walk all had diffuse atrophy involving both vermis and cerebellar hemispheres. (orig.)

  4. Dual Transgene Expression in Murine Cerebellar Purkinje Neurons by Viral Transduction In Vivo

    OpenAIRE

    Bosch, Marie K.; Nerbonne, Jeanne M.; Ornitz, David M.

    2014-01-01

    Viral-vector mediated gene transfer to cerebellar Purkinje neurons in vivo is a promising avenue for gene therapy of cerebellar ataxias and for genetic manipulation in functional studies of animal models of cerebellar disease. Here, we report the results of experiments designed to identify efficient methods for viral transduction of adult murine Purkinje neurons in vivo. For these analyses, several lentiviral and an adeno-associated virus (AAV), serotype 1, vector with various promoter combin...

  5. Implications of functional anatomy on information processing in the deep cerebellar nuclei

    OpenAIRE

    Jacobson, Gilad A.; Dana Cohen

    2009-01-01

    The cerebellum has been implicated as a major player in producing temporal acuity. Theories of cerebellar timing typically emphasize the role of the cerebellar cortex while overlooking the role of the deep cerebellar nuclei (DCN) that provide the sole output of the cerebellum. Here we review anatomical and electrophysiological studies to shed light on the DCN’s ability to support temporal pattern generation in the cerebellum. Specifically, we examine data on the structure of the DCN, th...

  6. Implications of Functional Anatomy on Information Processing in the Deep Cerebellar Nuclei

    OpenAIRE

    Baumel, Yuval; Jacobson, Gilad A.; Cohen, Dana

    2009-01-01

    The cerebellum has been implicated as a major player in producing temporal acuity. Theories of cerebellar timing typically emphasize the role of the cerebellar cortex while overlooking the role of the deep cerebellar nuclei (DCN) that provide the sole output of the cerebellum. Here we review anatomical and electrophysiological studies to shed light on the DCN's ability to support temporal pattern generation in the cerebellum. Specifically, we examine data on the structure of the DCN, the biop...

  7. Successfull Management of a Life Threatening Cerebellar Haemorrhage Following Spine Surgery - A Case Report -

    OpenAIRE

    Pallud, Johan; Belaïd, Hayat; Aldea, Sorin

    2009-01-01

    Cerebellar haemorrhages are rare life-threatening complications following spine surgery that present challenges for their diagnostic and their therapeutic management. Their patho-physiology remains unclear. We report a case of a life-threatening cerebellar haemorrhage secondary to an occult dural tear following a planned L5-S1 laminectomy. The patient was treated with emergent external ventriculostomy following by a posterior fossa decompressive craniectomy. Cerebellar haemorrhages have to be...

  8. Adams Oliver syndrome: Description of a new phenotype with cerebellar abnormalities in a family

    International Nuclear Information System (INIS)

    To describe cerebellar abnormalities in a family composed by a father and two affected sibs with Adams Oliver syndrome (AOS) (OMIM 100300). Brain MRI and MR angiography were performed at 1.5T. The siblings presented cerebellar cortex dysplasia characterized by the presence of cysts. Abnormalities of CNS are an unusual manifestation of AOS. To our knowledge, this is the first report of cerebellar cortical dysplasia in a family with AOS

  9. Calbindin in cerebellar Purkinje cells is a critical determinant of the precision of motor coordination

    OpenAIRE

    Barski, J. J.; Hartmann, J.; Rose, C. R.; Hoebeek, F.; Morl, K.; Noll-Hussong, M; De Zeeuw, C.I.; Konnerth, A; Meyer, M.

    2003-01-01

    Long-term depression (LTD) of Purkinje cell-parallel fiber synaptic transmission is a critical determinant of normal cerebellar function. Impairment of LTD through, for example, disruption of the metabotropic glutamate receptor-IP3-calcium signaling cascade in mutant mice results in severe deficits of both synaptic transmission and cerebellar motor control. Here, we demonstrate that selective genetic deletion of the calcium-binding protein calbindin D-28k (calbindin) from cerebellar Purkinje ...

  10. Heat-stroke-induced cerebellar atrophy: clinical course, CT and MRI findings

    International Nuclear Information System (INIS)

    We report the clinical course and CT and MRI findings in a case of heat-stroke-induced cerebellar atrophy. Although the cerebellar syndrome was severe concomitant with the onset of heat stroke, no abnormality was observed on brain CT in the first 2 weeks following the event. Cerebellar atrophy was first noted after 10 weeks on MRI; it was progressive during a 1-year follow-up. (orig.)

  11. Cerebellar hemorrhage after spine fixation misdiagnosed as a complication of narcotics use -A case report-

    OpenAIRE

    Yang, Ki-Hwan; Han, Jeong Uk; Jung, Jong-Kwon; Lee, Doo Ik; Hwang, Sung-Il; Lim, Hyun Kyoung

    2011-01-01

    Cerebellar hemorrhage occurs mainly due to hypertension. Postoperative cerebellar hemorrhage is known to be associated frequently with frontotemporal craniotomy, but quite rare with spine operation. A 56-year-old female received spinal fixation due to continuous leg tingling sensation for since two years ago. Twenty-one hours after operation, she was disoriented and unresponsive to voice. Performed computed tomography showed both cerebellar hemorrhage. An emergency decompressive craniotomy wa...

  12. Surgical resection of cerebellar hemangioblastoma with enhanced wall thickness: A report of two cases

    OpenAIRE

    Sun, Zhenxing; Yuan, Dan; SUN, YAXING; YAN, PENGXIANG; Zuo, Huancong

    2015-01-01

    Hemangioblastomas are tumors of the central nervous system, and the cerebellum is the most common site of occurrence. Cerebellar hemangioblastoma with enhanced wall thickness is rare and often misdiagnosed preoperatively. At present, no unified radiological classification system based on magnetic resonance imaging (MRI) findings exists for cerebellar hemangioblastoma, and this tumor type can be solid or cystic mass, according to the MRI findings. The most common presentation of cerebellar hem...

  13. Restoring Cognitive Functions Using Non-Invasive Brain Stimulation Techniques in Patients with Cerebellar Disorders

    OpenAIRE

    RChrisMiall

    2014-01-01

    Numerous studies have highlighted the possibility of modulating the excitability of cerebro–cerebellar circuits bi-directionally using transcranial electrical brain stimulation, in a manner akin to that observed using magnetic stimulation protocols. It has been proposed that cerebellar stimulation activates Purkinje cells in the cerebellar cortex, leading to inhibition of the dentate nucleus, which exerts a tonic facilitatory drive onto motor and cognitive regions of cortex through a synaptic...

  14. Autosomal dominant cerebellar ataxia type III: a review of the phenotypic and genotypic characteristics

    OpenAIRE

    Fujioka Shinsuke; Sundal Christina; Wszolek Zbigniew K

    2013-01-01

    Abstract Autosomal Dominant Cerebellar Ataxia (ADCA) Type III is a type of spinocerebellar ataxia (SCA) classically characterized by pure cerebellar ataxia and occasionally by non-cerebellar signs such as pyramidal signs, ophthalmoplegia, and tremor. The onset of symptoms typically occurs in adulthood; however, a minority of patients develop clinical features in adolescence. The incidence of ADCA Type III is unknown. ADCA Type III consists of six subtypes, SCA5, SCA6, SCA11, SCA26, SCA30, and...

  15. Hybrid RSOA and fibre raman amplified long reach feeder link for WiMAX-on-fibre

    DEFF Research Database (Denmark)

    Amaya Fernández, Ferney Orlando; Martinez, Javier; Yu, Xianbin;

    2009-01-01

    A distributed fibre Raman amplified long reach optical access feeder link using a reflective semiconductor optical amplifier in the remote base station is experimentally demonstrated for supporting WiMAXover- fibre transmission. The measured values for the error vector magnitude for quadrature...

  16. The coupling performance of photonic crystal fibres in fibre stellar interferometry

    DEFF Research Database (Denmark)

    Corbett, J.; Dabirian, A.; Butterley, T.;

    2006-01-01

    Large mode area (LMA), single-mode photonic crystal fibres (PCFs) have the potential to provide significant instrumental advantages in fibre stellar interferometry, due to their broadband attenuation spectrum, endlessly single-moded performance and very large core size. We investigate the...

  17. Effect of Steel Fibre Content on Bending and Compression Behaviour of Fibre Reinforced Concrete

    OpenAIRE

    Šahmenko, G; Krasņikovs, A; Lapsa, V; Teļnova, I; Mačanovskis, A

    2010-01-01

    Steel fibre reinforced concrete (SFRC) as modern perspective building material is increasingly used in diverse civil engineering applications. In SFRG mox fibres traditionally are the most expensive component, so its rational use is an actual task of SFRC mix design. In present investiganion different types of commercially available fibers, having different geometry, were used for SFRC samples preparation.

  18. Strength Evaluation of Steel-Nylon Hybrid Fibre Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Maniram Kumar

    2014-07-01

    Full Text Available When fibres like steel, glass, polypropylene, nylon, carbon, aramid, polyester, jute, etc are mixed with concrete known as fibre reinforced concrete. To overcome the deficiencies of concrete; fibres are added to improve the performance of concrete. In this research hybrid reinforced concrete is made by using steel and nylon 6 fibres. The inclusion of both steel and nylon 6 fibres are used in order to combine the benefits of both fibers; structural improvements provided by steel fibers and the resistance to plastic shrinkage improvements provided by nylon fibers. So the aim of this project is to investigate the mechanical properties (compressive strength, flexure strength and split tensile strength of hybrid fiber reinforced concrete under compression, flexure & tension. The total volume of fibre was taken 0.75 % of total volume of concrete. In this experimental work, four different concrete mix proportions were casted with fibres and one mix without fibres. Four different mix combinations of steel- nylon 6 fibres were 100-00%, 75-25%, 50-50% and 25-75%. Superplasticizer was used in all mixes to make concrete more workable. The results shown that compressive, split tensile and flexural strength of hybrid fibre reinforced concrete increase by increasing quantity of steel and nylon 6 fibres. The increase in compressive and tensile strength due to incorporation of steel fibre is greater than that of using nylon fibre. For the nylon 6 fibres, adding more fibres into the concrete has a limited improvement on splitting tensile strength. Inclusion of nylon 6 fibres along with steel fibres results in considerable improvement in flexural strength as compared to solo steel fibre.

  19. SELECTIVE EFFECTS OF DATURA STRAMONIUM ON THE GRANULAR PARALLEL FIBRES AND PURKINJE CELLS OF THE CEREBELLUM IN WISTAR RATS

    Directory of Open Access Journals (Sweden)

    Peter E. Ekanem

    2015-12-01

    Full Text Available Introduction: Datura stramonium (DS is a tropical ubiquitous shrub which is often used to increase intoxication in some beverages and is also freely used as a hallucinogen. It is a depressant of the central nervous system, yet commonly smoked in like manner tobacco. The present study investigated changes induced by intoxication with DS on the purkinje cells and parallel fibres of the cerebellum in Wistar rats to further elucidate the effects of this drug on cerebellar structure. Materials and Methods: The study was conducted on both male and female Wistar rats (200-250 g. They were placed into three batches and four groups were derived from each batch, with eight animals per group. Ethanolic dried seed extract of DS was diluted in normal saline and administered intraperitoneally (I.P. at a dose of 750mg/kg and given to the treatment groups: once in batch 1, twice in batch 2, twelve hourly and thrice in batch 3, eight hourly per day respectively for 4 weeks, while the control groups received an equivalent of normal saline. The rats were euthanized and sections of the cerebellum were histologically processed in all groups. Silver impregnation stain for degenerating axons and neurons was used to elucidate the actions of DS on purkinje cells and the parallel fibres of the cerebellum. Results: The result of IP administration of DS extract (750 mg/kg given three times daily to the treated rats showed significant histological changes, which included atrophy of the parallel fibres but no significant changes in the purkinje cells of the cerebellum. Conclusions: Intoxication of DS seed as a result of excessive ingestion may have a selective degenerative effect on the parallel fibres of the granule cells of the cerebellum while the purkinje cells are spared; the implication being motor dysfunction.

  20. D fibre antenna for microcellular communications

    International Nuclear Information System (INIS)

    Over the years, optical fibre sensors have been developed for many application areas. With the recent growth of microcellular communication systems this area has great economic potential. Therefore with this in mind one promising application for a new optical fibre sensor system is in the detection of Radio Frequency/Electric Fields (RF/EF). By constructing such a sensor from totally dielectric materials, it could be used as an antenna for receiving radio frequency transmissions without distorting or disturbing the field lines since there are no metallic components to reflect or transmit radio frequency energy. One of the key issues in the realisation of Radio-over-Fibre (RoF) architecture is the development of an effective means of generating and transmitting the radio subcarrier. The simplest method for the optical generation of radio signals, for transmission through an optical network is to directly modulate the light source with the received RF signal. Direct modulation of the laser can lead to a number of problems such as relative intensity noise (RIN), chirp and intermodulation distortion (IMD). A novel approach as described in this thesis, for generating an externally modulated optical signal would be to use an optical antenna comprising of a piezoelectric polymer coated D-fibre configured within a Mach-Zehnder interferometer to phase modulate the lightwave with a received RF electrical signal. One of the primary advantages of the D-fibre antenna over conventional antennae is its ability to serve a dual purpose. First it can be used to directly detect the RF signal, and secondly it provides a convenient means for modulating the light within the fibre thus bypassing the need for directly modulating the laser. The work presented in this thesis forms a comprehensive study on the design and modelling of a novel all-optical antenna using D-shaped optical fibre for use in next generation RoF networks. For the first time Finite Element Analysis (FEA) has been used

  1. Influence of fibre design and curvature on crosstalk in multi-core fibre

    Science.gov (United States)

    Egorova, O. N.; Astapovich, M. S.; Melnikov, L. A.; Salganskii, M. Yu; Mishkin, S. N.; Nishchev, K. N.; Semjonov, S. L.; Dianov, E. M.

    2016-03-01

    We have studied the influence of cross-sectional structure and bends on optical cross-talk in a multicore fibre. A reduced refractive index layer produced between the cores of such fibre with a small centre-to-centre spacing between neighbouring cores (27 μm) reduces optical cross-talk by 20 dB. The cross-talk level achieved, 30 dB per kilometre of the length of the multicore fibre, is acceptable for a number of applications where relatively small lengths of fibre are needed. Moreover, a significant decrease in optical cross-talk has been ensured by reducing the winding diameter of multicore fibres with identical cores.

  2. Hemp fibres: Enzymatic effect of microbial processing on fibre bundle structure

    DEFF Research Database (Denmark)

    Thygesen, Anders; Liu, Ming; Meyer, Anne S.;

    2013-01-01

    The effects of microbial pretreatment on hemp fibres were evaluated after microbial retting using the white rot fungi Ceriporiopsis subvermispora and Phlebia radiata Cel 26 and water retting. Based on chemical composition, P. radiata Cel 26 showed the highest selectivity for pectin and lignin...... with the microbial retting to evaluate the effects on their ultrastructure. SEM microscopy of the composites showed low porosity on the fibre surfaces after defibration with P. radiata Cel 26 and C. subvermispora indicating good epoxy polymer impregnation. In contrast, fibres treated by water retting...... degradation and lowest cellulose loss (14%) resulting in the highest cellulose content (78.4%) for the treated hemp fibres. The pectin and lignin removal after treatment with P. radiata Cel 26 were of the order 82% and 50%, respectively. Aligned epoxy-matrix composites were made from hemp fibres defibrated...

  3. Flavoprotein imaging in the cerebellar cortex in vivo: cellular and metabolic basis and insights into cerebellar function

    Science.gov (United States)

    Gao, Wangcai; Chen, Gang; Ebner, Timothy J.

    2009-02-01

    Flavoprotein autofluorescence is an activity dependent intrinsic signal. Flavoproteins are involved in the electron transport chain and change their fluorescence according to the cellular redox state. We have been using flavoprotein autofluorescence in the cerebellum to examine properties of cerebellar circuits. Studies have also focused on understanding the cellular and metabolic origins of this intrinsic optical signal. Parallel fiber stimulation evokes a beamlike response intersected by bands of decreased fluorescence. The beam response is biphasic, with an early fluorescence increase (light phase) followed by a slower decrease (dark phase). We show this signal originates from flavoproteins as determined by its wavelength selectivity and sensitivity to blockers of the electron transport chain. Selectively blocking glutamate receptors abolished the on-beam light phase with the dark phase remaining intact. This demonstrates that the light phase is due to postsynaptic neuronal activation and suggests the dark phase is primarily due to glial activation. The bands of reduced fluorescence intersecting the beam are primarily neuronal in origin, mediated by GABAergic transmission, and due to the inhibitory action of molecular layer interneurons on Purkinje cells and the interneurons themselves. This parasagittally organized molecular layer inhibition differentially modulates the spatial pattern of cerebellar cortical activity. Flavoprotein imaging also reveals the functional architectures underlying the responses to inferior olive and peripheral whisker pad stimulation. Therefore, flavoprotein autofluorescence imaging is providing new insights into cerebellar cortical function and neurometabolic coupling.

  4. Natural Composites: Cellulose Fibres and the related Performance of Composites

    DEFF Research Database (Denmark)

    Lilholt, Hans; Madsen, Bo

    2014-01-01

    Biobased materials are becoming of increasing interest as potential structural materials for the future. A useful concept in this context is the fibre reinforcement of materials by stiff and strong fibres. The biobased resources can contribute with cellulose fibres and biopolymers. This offers...... in stiffness, on the packing ability of cellulose fibres and the related maximum fibre volume fraction in composites, on the moisture sorption of cellulose fibres and the related mass increase and (large) hygral strains induced, and on the mechanical performance of composites....

  5. Mechanical Properties of Man-Made Mineral glass fibres

    DEFF Research Database (Denmark)

    Lund, Majbritt Deichgræber; Yue, Yuanzheng

    In nature basaltic volcanic glass fibres are know from Hawaii as Pele's hair, formed by droplets of lava thrown into the air during volcanic eruption. The concept of glass fibre formation by an air stream dragging fibres from drops of melt is copied in industry to form basaltic glass wool fibres...... and hence they are used for insulation products. In spite of those advantages, man made mineral wool fibres still show a certain degree of brittleness, which limits the further improvement of man made mineral wool fibres for both transportation and application. Therefore, a reduction in the...

  6. Latest developments in silica fibre luminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D. A.; Abdul S, S. F.; Jafari, S. M.; Alanazi, A. [University of Surrey, Department of Physics, GU2 7XH Guildford, Surrey (United Kingdom); Amouzad M, G. [University of Malaya, Faculty of Engineering, Department of Electrical Engineering, Integrated Lightwave Research Group, 50603 Kuala Lumpur (Malaysia); Addul R, H. A.; Mizanur R, A. K. M.; Zubair, H. T.; Begum, M.; Yusoff, Z.; Omar, N. Y. M. [Multimedia University, Faculty of Engineering, 2010 Cyberjaya, Selangor (Malaysia); Maah, M. J. [University of Malaya, Department of Chemistry, 50603 Kuala Lumpur (Malaysia); Collin, S. [National Physical Laboratory, Hampton Road, Teddington, TW11 OLW Middlesex (United Kingdom); Mat-Sharif, K. A.; Muhd-Yassin, S. Z.; Zulkifli, M. I., E-mail: d.a.bradley@surrey.ac.uk [Telekom Malaysia Research and Development Sdn Bhd., 63000 Cyberjaya, Selangor (Malaysia)

    2015-10-15

    Full text: Using tailor made sub-mm diameter doped-silica fibres, we are carrying out luminescence dosimetry studies for a range of situations, including thermoluminescence (Tl)investigations on a liquid alpha source formed of {sup 223}RaCl (the basis of the Bayer Health care product Xofigo), the Tl response to a 62 MeV proton source and Tl response to irradiation from an {sup 241}Am-Be neutron source. In regard to the former, in accord with the intrinsic high linear energy transfer (Let) and short path length (<100 um) of the α-particles in calcified tissue, the product is in part intended as a bone-seeking radionuclide for treatment of metastatic cancer, offering high specificity and efficacy. The Tl yield of Ge-doped SiO{sub 2} fibres has been investigated including for photonic crystal fibre un collapsed, flat fibres and single mode fibres, these systems offering many advantages over conventional passive dosimetry types. In particular, one can mention comparable and even superior sensitivity, an effective atomic number Z{sub eff} of the silica dosimetric material close to that of bone, and the glassy nature of the fibres offering the additional advantage of being able to place such dosimeters directly into liquid environments. Finally we review the use of our tailor made fibres for on-line radioluminescence measurements of radiotherapy beams. The outcome from these various lines of research is expected to inform development of doped fiber radiation dosimeters of versatile utility, ranging from clinical applications through to industrial studies and environmental evaluations. (Author)

  7. Latest developments in silica fibre luminescence dosimetry

    International Nuclear Information System (INIS)

    Full text: Using tailor made sub-mm diameter doped-silica fibres, we are carrying out luminescence dosimetry studies for a range of situations, including thermoluminescence (Tl)investigations on a liquid alpha source formed of 223RaCl (the basis of the Bayer Health care product Xofigo), the Tl response to a 62 MeV proton source and Tl response to irradiation from an 241Am-Be neutron source. In regard to the former, in accord with the intrinsic high linear energy transfer (Let) and short path length (<100 um) of the α-particles in calcified tissue, the product is in part intended as a bone-seeking radionuclide for treatment of metastatic cancer, offering high specificity and efficacy. The Tl yield of Ge-doped SiO2 fibres has been investigated including for photonic crystal fibre un collapsed, flat fibres and single mode fibres, these systems offering many advantages over conventional passive dosimetry types. In particular, one can mention comparable and even superior sensitivity, an effective atomic number Zeff of the silica dosimetric material close to that of bone, and the glassy nature of the fibres offering the additional advantage of being able to place such dosimeters directly into liquid environments. Finally we review the use of our tailor made fibres for on-line radioluminescence measurements of radiotherapy beams. The outcome from these various lines of research is expected to inform development of doped fiber radiation dosimeters of versatile utility, ranging from clinical applications through to industrial studies and environmental evaluations. (Author)

  8. Studies on fibre quality of a long staple cotton variety using high volume instrument and advanced fibre information system for fibre quality improvement

    Directory of Open Access Journals (Sweden)

    S Manickam and S Venkatakrishnan

    2014-06-01

    Full Text Available Fibre quality parameters of 20 plants of a long staple cotton variety Suraj were analyzed using High Volume Instrument (HVI and Advanced Fibre Information System (AFIS and were compared. From AFIS data, narrow range of coefficient of variability (of less than 10 % was noticed in characters like length (by weight, upper quartile length (by weight, length (by number, 5 % length (by number, fineness (mtex, maturity ratio and fibre neps. Comparatively larger extent of variability was noticed (of more than 10 % for short fibre content (both by weight and by number, immature fibre content, fibre neps – count/g, seed coat neps – count/g and for seed coat neps – mean size. However, the coefficient of variability for 2.5 % span length (mm, uniformity ratio (%, micronaire (μg/inch and tenacity at 3.2 mm gauge (g/tex was low when the fibre quality data was generated in HVI. This shows that variability estimates were narrow in the selected plants when fibre quality was analysed in HVI and exposes inherent weakness in analysing the fibre quality with HVI in breeders’ perspective. Correlation coefficients between immature fibre content and short fibre content, both by number (r = 0.89 and by weight (r = 0.84 were very high indicating that by reducing short fibre content the immature fibre content can be reduced drastically. Further, the correlation between immature fibre content and tenacity at 3.2 mm gauge was negative and was high (-0.91. Plants with ideal combination of yield and fibre quality parameters were identified for further exploitation.

  9. Influence of the Testing Gage Length on the Strength, Young's Modulus and Weibull Modulus of Carbon Fibres and Glass Fibres

    Directory of Open Access Journals (Sweden)

    Luiz Claudio Pardini

    2002-10-01

    Full Text Available Carbon fibres and glass fibres are reinforcements for advanced composites and the fiber strength is the most influential factor on the strength of the composites. They are essentially brittle and fail with very little reduction in cross section. Composites made with these fibres are characterized by a high strength/density ratio and their properties are intrisically related to their microstructure, i.e., amount and orientation of the fibres, surface treatment, among other factors. Processing parameters have an important role in the fibre mechanical behaviour (strength and modulus. Cracks, voids and impurities in the case of glass fibres and fibrillar misalignments in the case of carbon fibres are created during processing. Such inhomogeneities give rise to an appreciable scatter in properties. The most used statistical tool that deals with this characteristic variability in properties is the Weibull distribution. The present work investigates the influence of the testing gage length on the strength, Young's modulus and Weibull modulus of carbon fibres and glass fibres. The Young's modulus is calculated by two methods: (i ASTM D 3379M, and (ii interaction between testing equipment/specimen The first method resulted in a Young modulus of 183 GPa for carbon fibre, and 76 GPa for glass fibre. The second method gave a Young modulus of 250 GPa for carbon fibre and 50 GPa for glass fibre. These differences revelead differences on how the interaction specimen/testing machine can interfere in the Young modulus calculations. Weibull modulus can be a tool to evaluate the fibre's homogeneity in terms of properties and it is a good quality control parameter during processing. In the range of specimen gage length tested the Weibull modulus for carbon fibre is ~ 3.30 and for glass fibres is ~ 5.65, which indicates that for the batch of fibres tested, the glass fibre is more uniform in properties.

  10. THERMOMECHANICAL PROPERTIES OF JUTE/BAGASSE HYBRID FIBRE REINFORCED EPOXY THERMOSET COMPOSITES

    OpenAIRE

    Sudhir Kumar Saw; Chandan Datta

    2009-01-01

    Natural fibres are partly replacing currently used synthetic fibres as reinforcement for polymer composites. Jute fibre bundles were high-cellulose-content modified by alkali treatment, while the bagasse fibre bundles were modified by creating quinones in the lignin portions of fibre surfaces and reacting them with furfuryl alcohol (FA) to increase their adhesiveness. The effects of different fibre bundle loading and modification of bagasse fibre surfaces in hybrid fibre reinforced epoxy comp...

  11. Complex geometrical optics of nonlinear inhomogeneous fibres

    International Nuclear Information System (INIS)

    This paper analyses the Gaussian beam (GB) evolution in nonlinear fibres with special attention given to the influence of the initial curvature of the wavefront and to the fibres' permittivity profile. The analysis is performed in the framework of paraxial complex geometrical optics (PCGO). This method reduces the problem of GB evolution in nonlinear and inhomogeneous media to the solution of ordinary differential equations, which can be easily solved either analytically or numerically. It is shown that the PCGO approach radically simplifies modelling of nonlinear phenomena in fibres as compared with standard methods of nonlinear optics such as the variational method approach and the method of moments. It is shown that the PCGO method readily supplies the solution of the nonlinear Schrödinger equation (NLS) for a self-focusing fibre with a focusing permittivity profile and provides a number of new results. The discussion on the interplay between the nonlinear (self-focusing and self-defocusing) and linear (focusing and defocusing) components of the total permittivity demonstrates the new possibilities to limit the collapse phenomenon in nonlinear fibres of Kerr type taking into account the effect of initial beam divergence

  12. Complex geometrical optics of nonlinear inhomogeneous fibres

    Science.gov (United States)

    Berczynski, Pawel

    2011-03-01

    This paper analyses the Gaussian beam (GB) evolution in nonlinear fibres with special attention given to the influence of the initial curvature of the wavefront and to the fibres' permittivity profile. The analysis is performed in the framework of paraxial complex geometrical optics (PCGO). This method reduces the problem of GB evolution in nonlinear and inhomogeneous media to the solution of ordinary differential equations, which can be easily solved either analytically or numerically. It is shown that the PCGO approach radically simplifies modelling of nonlinear phenomena in fibres as compared with standard methods of nonlinear optics such as the variational method approach and the method of moments. It is shown that the PCGO method readily supplies the solution of the nonlinear Schrödinger equation (NLS) for a self-focusing fibre with a focusing permittivity profile and provides a number of new results. The discussion on the interplay between the nonlinear (self-focusing and self-defocusing) and linear (focusing and defocusing) components of the total permittivity demonstrates the new possibilities to limit the collapse phenomenon in nonlinear fibres of Kerr type taking into account the effect of initial beam divergence.

  13. Gauge symmetries and fibre bundles

    International Nuclear Information System (INIS)

    The matter is organized as follows. After a brief introduction to the concept of gauge invariance and its relationship to determinism, we introduce in chapters 3 and 4 the notion of fibre bundles in the context of a discussion on spinning point particles and Dirac monopoles. Chapter 3 deals with a non relativistic treatment of the spinning particle. The non trivial extension to relativistic spinning particles is dealt with in Chapter 5. The free particle system as well as interactions with external electromagnetic and gravitational fields are discussed in detail. In chapter 5 we also elaborate on a remarkable relationship between the charge-monopole system and the system of a massless particle with spin. The classical description of Yang-Mills particles with internal degrees of freedom, such as isospin or colour, is given in chapter 6. We apply the above in a discussion of the classical scattering of particles off a 't Hooft-Polyakov monopole. In chapter 7 we elaborate on a Kaluza-Klein description of particles with internal degrees of freedom. The canonical formalism and the quantization of most of the preceeding systems are discussed in chapter 8. The dynamical systems given in chapters 3-7 are formulated on group manifolds. The procedure for obtaining the extension to super-group manifolds is briefly discussed in chapter 9. In chapter 10, we show that if a system admits only local Lagrangians for a configuration space Q, then under certain conditions, it admits a global Lagrangian when Q is enlarged to a suitable U(1) bundle over Q. Conditions under which a symplectic form is derivable from a Lagrangian are also found. (orig./HSI)

  14. Dietary fibre: consensus and controversy.

    Science.gov (United States)

    Bijlani, R L

    1985-01-01

    Technological advances have reduced and refined man's plant food intake and consequently brought about an unprecedented decline in his consumption of dietary fibre (DF). The emergence of certain diseases selectively in regions which have been affected the most by this dietary change has led to an enhanced awareness of the functions of DF. DF is a heterogeneous group of substances which resist digestion by the endogenous enzymes of the human gut, although they are fermented to a substantial extent by the bacterial flora of the large intestine. Chemically, DF essentially consists of nonstarch polysaccharides and lignin, and its major constituents are cellulose, hemicelluose, lignin and pectin. The physiological effects of DF are attributable largely to its physicochemical properties. DF primarily affects gastrointestinal (GI) function; its effects are observable at all stages from ingestion through defaecation. It restricts caloric intake, shows gastric and small intestinal transit, and affects the activity of digestive enzymes and release of GI hormones. Its overall impact is to reduce apparent digestibility of nutrients marginally but consistently. In the large intestine, DF accelerates transit, supports bacterial growth and serves to hold water. As a result, the faecal weight and water content increase, and the transit time generally becomes shorter. Secondary to its GI effects, DF attenuates postprandial glycaemia and has long term effects on glucose tolerance and lipoprotein metabolism. These effects have important implications in the aetiopathogenesis of constipation and its sequelae including diverticulosis, cholesterol gallstones, colorectal cancer, obesity, diabetes mellitus and atherosclerosis. DF has traditionally been used therapeutically for constipation; now its use in diabetes is also well established. Our appreciation of the role of DF in human nutrition has undergone a major change in the last two decades. From a redundant constituent of plant foods

  15. Clinical and genetic analysis of a four-generation family with a distinct autosomal dominant cerebellar ataxia

    NARCIS (Netherlands)

    Schelhaas, H J; Ippel, P F; Hageman, G; Sinke, R J; van der Laan, E N; Beemer, F A

    2001-01-01

    The autosomal dominant cerebellar ataxias (ADCAs) are a heterogeneous group of neurodegenerative disorders characterised by progressive cerebellar dysfunction in combination with a variety of other associative features. Since 1993 ADCAs have been increasingly characterised in terms of their genetic

  16. Inhibition of starch absorption by dietary fibre. A comparative study of wheat bran, sugar-beet fibre, and pea fibre

    DEFF Research Database (Denmark)

    Hamberg, O; Rumessen, J J; Gudmand-Høyer, E

    1989-01-01

    .5% (5-20%) (p less than 0.01), and 12% (5-27%) (p less than 0.01), respectively. Bread made from 100 g of low-gluten wheat flour only escaped small-bowel absorption in three subjects with a maximal fraction of 6% (p less than 0.05). All three fibres decreased mouth-to-caecum transit time. We conclude...... that the dietary fibres used in this impaired the absorption of wheat starch and thereby increased the amount of starch-derived carbohydrate available for colonic fermentation....

  17. Study of injection moulded long glass fibre-reinforced polypropylene and the effect on the fibre length and orientation distribution

    Science.gov (United States)

    Parveeen, B.; Caton-Rose, P.; Costa, F.; Jin, X.; Hine, P.

    2014-05-01

    Long glass fibre (LGF) composites are extensively used in manufacturing to produce components with enhanced mechanical properties. Long fibres with length 12 to 25mm are added to a thermoplastic matrix. However severe fibre breakage can occur in the injection moulding process resulting in shorter fibre length distribution (FLD). The majority of this breakage occurs due to the melt experiencing extreme shear stress during the preparation and injection stage. Care should be taken to ensure that the longer fibres make it through the injection moulding process without their length being significantly degraded. This study is based on commercial 12 mm long glass-fibre reinforced polypropylene (PP) and short glass fibre Nylon. Due to the semi-flexiable behaviour of long glass fibres, the fibre orientation distribution (FOD) will differ from the orientation distribution of short glass fibre in an injection molded part. In order to investigate the effect the change in fibre length has on the fibre orientation distribution or vice versa, FOD data was measured using the 2D section image analyser. The overall purpose of the research is to show how the orientation distribution chnages in an injection moulded centre gated disc and end gated plaque geometry and to compare this data against fibre orientation predictions obtained from Autodesk Moldflow Simulation Insight.

  18. Observations on the electrical resistivity of steel fibre reinforced concrete

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe; Geiker, Mette Rica; Edvardsen, Carola; Kuter, Andr

    Steel fibre reinforced concrete (SFRC) is in many ways a well-known construction material, and its use has gradually increased over the last decades. The mechanical properties of SFRC are well described based on the theories of fracture mechanics. However, knowledge on other material properties...... observed correlation between the fibre volume fraction and the electrical resistivity of the composite (the SFRC) for conductive fibres and moisture saturated concrete. This indicates that the steel fibres were conducting when measuring the electrical resistivity by AC at 126 Hz. For partly saturated...... concrete the model underestimated the influence of the addition of fibres. The results indicate that the addition of steel fibres reduce the electrical resistivity of concrete if the fibres are conductive. This represents a hypothetical case where all fibres are depassivated (corroding) which was created...

  19. Manufacturing Titanium Metal Matrix Composites by Consolidating Matrix Coated Fibres

    Institute of Scientific and Technical Information of China (English)

    Hua-Xin PENG

    2005-01-01

    Titanium metal matrix composites (TiMMCs) reinforced by continuous silicon carbide fibres are being developed for aerospace applications. TiMMCs manufactured by the consolidation of matrix-coated fibre (MCF) method offer optimum properties because of the resulting uniform fibre distribution, minimum fibre damage and fibre volume fraction control. In this paper, the consolidation of Ti-6Al-4V matrix-coated SiC fibres during vacuum hot pressing has been investigated. Experiments were carried out on multi-ply MCFs under vacuum hot pressing (VHP). In contrast to most of existing studies, the fibre arrangement has been carefully controlled either in square or hexagonal arraysthroughout the consolidated sample. This has enabled the dynamic consolidation behaviour of MCFs to be demonstrated by eliminating the fibre re-arrangement during the VHP process. The microstructural evolution of the matrix coating was reported and the deformation mechanisms involved were discussed.

  20. Special Polymer Optical Fibres and Devices for Photonic Applications

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Remarkable progresses have been made in developing special polymer optical fibres and devices for photonic applications in recent years. This presentation will mainly report on the development of electro-optic, photosensitive and photorefractive polymer optical fibres and related devices.

  1. Neodymium doped gallium lanthanum sulphide glass fibre laser

    OpenAIRE

    Schweizer, T.; Samson, B.N.; Hewak, D.W.; Payne, D.N.

    1997-01-01

    We report laser action in a neodymium doped gallium lanthanum sulphide glass fibre at 1.08µm. To our knowledge, this is the first demonstration of laser action in a rare-earth doped chalcogenide glass fibre.

  2. Fatigue processes in thermoplastic fibres; Les mecanismes de fatigue dans les fibres thermoplastiques

    Energy Technology Data Exchange (ETDEWEB)

    Herrera Ramirez, J.M.

    2004-09-15

    The present study examines and compares the behaviour of the two types of PA66 fibres and two types of PET fibres under fatigue loading up to failure, and the correlation between the fibres (nano)structures and their structural heterogeneities, with fatigue lifetimes. Several techniques have been used to analyze the materials, such as scanning electron microscopy (SEM), microanalysis (EDS), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and micro-Raman spectroscopy. A meticulous analysis by scanning electron microscopy of the fracture morphology of fibres broken in tension and in fatigue, as well as a study of the fatigue life, were undertaken. The fatigue process occurs when the cyclic load amplitude is sufficiently large, however a condition for fatigue failure is that the minimum load each cycle must be lower than a threshold stress level. Failure under fatigue conditions leads to distinctive fracture morphologies which are very different from those seen after tensile or creep failure and this allows easy identification of the fatigue process. The fibres have been analyzed in the as received state and after fatigue failure in order to observe the microstructural changes resulting from the fatigue loading. The results will be compared with those obtained for fibres loaded under conditions where the fatigue process was hindered. The role of the microstructure of the fibres in determining fatigue will be discussed in this work and the possibility of improving their resistance to fatigue or eliminating the fatigue process will be discussed. (author)

  3. Degradation of basalt fibre and glass fibre/epoxy resin composites in seawater

    International Nuclear Information System (INIS)

    Research highlights: → BFRP degradation process in seawater environment was first investigated. → The mass gain change includes two effects: absorption and extraction. → The interfacial adhesion of BFRP is bigger than GFRP. → After treated, the bending strength of BFRP is lower than GFRP. → Reducing the Fe2+ in the basalt fibre could lead to a higher stability of BFRP. - Abstract: Epoxy resins reinforced, respectively, by basalt fibres and glass fibres were treated with a seawater solution for different periods of time. Both the mass gain ratio and the strength maintenance ratio of the composites were examined after the treatment. The fracture surfaces were characterized using scanning electron microscopy. The tensile and bending strengths of the seawater treated samples showed a decreasing trend with treating time. In general, the anti-seawater corrosion property of the basalt fibre reinforced composites was almost the same as that of the glass fibre reinforced ones. Based on the experimental results, possible corrosion mechanisms were explored, indicating that an effective lowering of the Fe2+ content in the basalt fibre could lead to a higher stability for the basalt fibre reinforced composites in a seawater environment.

  4. Degradation of basalt fibre and glass fibre/epoxy resin composites in seawater

    Energy Technology Data Exchange (ETDEWEB)

    Wei Bin [Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Xili, Shenzhen 518055 (China); Cao Hailin, E-mail: caohl@hit.edu.c [Harbin Institute of Technology, Harbin 150001 (China); Shenzhen Aerospace Tech-Innovation Institute, Shenzhen Key Laboratory of Composite Materials, Shenzhen 518057 (China); Song Shenhua [Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Xili, Shenzhen 518055 (China)

    2011-01-15

    Research highlights: {yields} BFRP degradation process in seawater environment was first investigated. {yields} The mass gain change includes two effects: absorption and extraction. {yields} The interfacial adhesion of BFRP is bigger than GFRP. {yields} After treated, the bending strength of BFRP is lower than GFRP. {yields} Reducing the Fe{sup 2+} in the basalt fibre could lead to a higher stability of BFRP. - Abstract: Epoxy resins reinforced, respectively, by basalt fibres and glass fibres were treated with a seawater solution for different periods of time. Both the mass gain ratio and the strength maintenance ratio of the composites were examined after the treatment. The fracture surfaces were characterized using scanning electron microscopy. The tensile and bending strengths of the seawater treated samples showed a decreasing trend with treating time. In general, the anti-seawater corrosion property of the basalt fibre reinforced composites was almost the same as that of the glass fibre reinforced ones. Based on the experimental results, possible corrosion mechanisms were explored, indicating that an effective lowering of the Fe{sup 2+} content in the basalt fibre could lead to a higher stability for the basalt fibre reinforced composites in a seawater environment.

  5. Compression properties of novel thermoplastic carbon fibre and poly-ethylene terephthalate fibre composite lattice structures

    International Nuclear Information System (INIS)

    Highlights: • An efficient manufacturing route to produce a thermoplastic lattice is presented. • The influence of core geometry on the mechanical properties have been investigated. • Thermoplastic carbon fibre structures show competitive mechanical performance. • Thermoplastic single polymer structures show better performance than foams. • Single polymer lattice cores have good recyclability and energy absorption. - Abstract: A novel manufacturing route to efficiently produce fibre composite lattice structures has been developed. By using thermoplastic composite materials, flat sheets have been continuously folded, cut into a lattice shape and joined into a sandwich structure. Carbon fibre reinforced poly-ethylene terephthalate (CPET) and poly-ethylene terephthalate fibre reinforced poly-ethylene terephthalate (SrPET) materials have been used to explore two different core options; a carbon fibre option which gives high performance but low recyclability and a single polymer PET option which gives lower performance but full recyclability. Parametric numerical simulations have been used to investigate how the various manufacturing parameters affect the mechanical performance of the core. The carbon fibre composite cores have mechanical performance on-par or better than existing metallic and composite lattice cores presented in literature. Single polymer PET cores show better performance compared to high-end foam cores but have considerable lower performance than carbon fibre lattice cores

  6. EDITORIAL: Optical Fibre Sensors 18 (OFS-18)

    Science.gov (United States)

    Jones, Julian D. C.; Tatam, Ralph P.

    2007-10-01

    The International Conference on Optical Fibre Sensors (OFS-18) was held in October 2006 in Cancún, Mexico, under the general chairmanship of Dr Alexis Mendez (MCH Engineering LLC, USA) and Dr Fernando Mendoza (Centro de Investigaciones en Optica, Mexico). 'OFS', as it has become known, is firmly established as the leading international conference for the optical fibre sensor community. Since its inception, in London in 1983, and under the leadership of an international steering committee independent of any learned society or professional institution, it has been held approximately every eighteen months. The venue nominally rotates from Europe, to the Americas, and thence to Asia and the Pacific. OFS-18 demonstrated the continuing vigour of the community, with some 250 papers presented, plus two workshops, with attendance as international as ever. In recent years, it has become a tradition to publish a post-conference special issue in the journal Measurement Science and Technology, and these special issues offer a representative sample of the current status of the field. In the nearly 25 years since OFS began, many of the early ideas and laboratory-based proof-of-principle experiments have led to highly developed instrumentation systems, and to successful commercial products. Perhaps the most mature of all of these technologies is the optical fibre gyroscope, with the fibre hydrophone a close second—originally developed for defence applications for which it is now established, but with increasing relevance to the oil and gas industry; electromagnetic sensors based on the Faraday and electro-optic effects are of growing significance in the power generation and distribution industry; whilst in-fibre grating-based sensors occupy an expanding niche in structural monitoring, especially in civil engineering. It is therefore appropriate that the first day of OFS was devoted to workshops on structural health monitoring, and to commemorate the 30th anniversary of the

  7. Secure Communication System Basedon Chaosin Optical Fibre

    Institute of Scientific and Technical Information of China (English)

    Pak L Chu; Fan Zhang; William Mak; Robust Lai

    2003-01-01

    @@ 1 Introduction Recently, there have been intense research activities on the study of synchronized chaos generated by fibre lasers [1] and its application to secure communication systems . So far, all studies concentrate on two aspects:[2].So far,all studies concentrate on two aspects:(1) the effect of the transmission channel between the transmitter and the receiver has been neglected, and (2)the chaos and the signal are carried by one wavelength.Both theoretical and experimental investigations make these two assumptions. In the experiments, the transmission fibre is invariably short, in the order of tens of metres. Hence its dispersion and nonlinear effects are negligible. The fibre laser responsible for the generation of chaos is often designed to lase at one wavelength only.

  8. Theoretical aspects of fibre laser cutting

    International Nuclear Information System (INIS)

    Fibre lasers offer distinct advantages over established laser systems with respect to power efficiency, beam guidance and beam quality. Consequently, the potential of these new laser beam sources will be increasingly exploited for laser cutting applications that are conventionally carried out with CO2 lasers. However, theoretical estimates of the effective absorptivity at the cut front suggest that the shorter wavelength of the fibre laser in combination with its high focusability seems to be primarily advantageous for thin sheet metal cutting whereas the CO2 laser is probably still capable of cutting thicker materials more efficiently. This surprising result is a consequence of the absorptivity behaviour of metals that shows essential quantitative differences for the corresponding wavelengths of both laser sources as a function of the angle of incidence between the laser beam and the material to be cut. In evaluation of the revealed dependences, solution strategies for an improvement of the efficiency of fibre laser cutting of thicker metal sheets are suggested.

  9. Theoretical aspects of fibre laser cutting

    Science.gov (United States)

    Mahrle, A.; Beyer, E.

    2009-09-01

    Fibre lasers offer distinct advantages over established laser systems with respect to power efficiency, beam guidance and beam quality. Consequently, the potential of these new laser beam sources will be increasingly exploited for laser cutting applications that are conventionally carried out with CO2 lasers. However, theoretical estimates of the effective absorptivity at the cut front suggest that the shorter wavelength of the fibre laser in combination with its high focusability seems to be primarily advantageous for thin sheet metal cutting whereas the CO2 laser is probably still capable of cutting thicker materials more efficiently. This surprising result is a consequence of the absorptivity behaviour of metals that shows essential quantitative differences for the corresponding wavelengths of both laser sources as a function of the angle of incidence between the laser beam and the material to be cut. In evaluation of the revealed dependences, solution strategies for an improvement of the efficiency of fibre laser cutting of thicker metal sheets are suggested.

  10. Development of SERS active fibre sensors

    CERN Document Server

    Polwart, E

    2002-01-01

    Surface-enhanced Raman scattering (SERS) is sensitive and selective and when coupled with fibre-optics could potentially produce an effective chemical sensing system. This thesis concerns the development of a single-fibre-based sensor, with an integral SERS-active substrate. A number of different methods for the manufacture of SERS-active surfaces on glass substrates were investigated and compared. The immobilisation of metal nanoparticles on glass functionalised with (3-aminopropyl)trimethoxysilane emerged as a suitable approach for the production of sensors. Substrates prepared by this approach were characterised using UV-visible spectroscopy, electron microscopy and Raman mapping. It was found that exposure of substrates to laser radiation led to a decrease in the signal recorded from adsorbed analytes. This speed of the decrease was shown to depend on the analyte, and the exciting wavelength and power. SERS-active fibre sensors were produced by immobilisation of silver nanoparticles at the distal end of a...

  11. Laser acceleration... now with added fibre

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    Laser acceleration technology is plagued by two main issues: efficiency and repetition rates. In other words, lasers consume too much power and cannot sustain accelerating particles long enough to produce collisions. ICAN, a new EU-funded project, is examining how fibre lasers may help physicists tackle these issues.   A diode-pumped fibre laser. (Image courtesy of Laser Zentrum Hannover.) The International Coherent Amplification Network (ICAN) is studying the potential of lasers for collision physics. CERN is a beneficiary of the project and will collaborate with 15 other institutes from around the world, including KEK in Japan, Fermilab in the USA, and DESY in Germany. “The network is looking into existing fibre laser technology, which we believe has fantastic potential for accelerators,” says Gerard Mourou, ICAN co-ordinator at the École Polytechnique in France. “The hope is to make laser acceleration competitive with traditional radio-fre...

  12. A fibre bundle formulation of quantum geometry

    International Nuclear Information System (INIS)

    Quantum geometries whose points are stochastic and serve as seats for quantum space-time excitons are formulated as fibre bundles over base spaces of mean values with a Minkowski or general relativistic structure. The fibres contain the proper wave functions of all exciton states in a given model. The notion of covariance and propagation in quantum space-times constituting such fibre bundles is investigated. Maxwell and Yang-Mills gauge degrees of freedom are introduced by appropriately enlarging the structure group, which in all cases contains phase-space representations of the Poincare group corresponding to the exciton wave function sample space specific to a given model. It is shown that these formulations give rise in a natural manner to certain realizations of the relativistic canonical commutation relations in terms of covariant derivatives involving internal as well as external degrees of freedom of space-time excitons

  13. LTP fibre injector qualification and status

    International Nuclear Information System (INIS)

    This paper presents the current state of the LISA Technology Package (LTP) fibre injector qualification project in terms of vibration and shock tests. The fibre injector is a custom built part and therefore must undergo a full space qualification process. The mounting structure and method for sinusoidal vibration and random vibration tests as well as shock tests will be presented. Furthermore a proposal will be presented to use the fibre injector pair qualification model to build an optical prototype bench. The optical prototype bench is a full-scale model of the flight model. It will be used for development and rehearsal of all the assembly stages of the flight model and will provide an on-ground simulator for investigation as an updated engineering model.

  14. On the topology of chromatin fibres

    Science.gov (United States)

    Barbi, Maria; Mozziconacci, Julien; Victor, Jean-Marc; Wong, Hua; Lavelle, Christophe

    2012-01-01

    The ability of cells to pack, use and duplicate DNA remains one of the most fascinating questions in biology. To understand DNA organization and dynamics, it is important to consider the physical and topological constraints acting on it. In the eukaryotic cell nucleus, DNA is organized by proteins acting as spools on which DNA can be wrapped. These proteins can subsequently interact and form a structure called the chromatin fibre. Using a simple geometric model, we propose a general method for computing topological properties (twist, writhe and linking number) of the DNA embedded in those fibres. The relevance of the method is reviewed through the analysis of magnetic tweezers single molecule experiments that revealed unexpected properties of the chromatin fibre. Possible biological implications of these results are discussed. PMID:24098838

  15. Facile synthesis of ZnO hollow fibres

    Indian Academy of Sciences (India)

    B T Su; K Wang; X W Zuo; H M Mu; N Dong; Y C Tong; J Bai; Z Q Lei

    2007-12-01

    In this paper, cotton fibres were used as bio-template to successfully synthesize new ceramic materials, ZnO hollow fibres and in an effort to explore the synthesis condition, and simplify the synthesis procedure. In this synthesis, a direct thermal decomposition of zinc acetate dihydrate coated on the surface of cotton fibres was explored. The wall porosity of the ZnO hollow fibres was controlled by changing the concentration of zinc acetate aqueous solution.

  16. Stable multiple wavelength generation in all-fibre DFB lasers

    OpenAIRE

    Ibsen, Morten; Ronnekleiv, Erland; Hadeler, Oliver; Cowle, Gregory J.; Zervas, Michalis N.; Laming, Richard I.

    1999-01-01

    Fibre DFB lasers exhibit many attractive features and being based on and around a fibre Bragg grating they exhibit the robustness in performance offered by these, together with inherent fibre compatibility They can readily be manufactured to operate in both a single longitudinal and single polarisation mode and strong preferential output has also been demonstrated by offsetting the phase-shift from the centre position. As the technology of fibre Bragg grating fabrication and manipulation have...

  17. Advanced waveguides for high power optical fibre sources

    OpenAIRE

    Soh, Daniel Beom Soo

    2005-01-01

    This thesis reports on theoretical and experimental studies of wavelength-selective waveguide structures for high-power Nd3+- and Yb3+-doped fibre lasers. Cladding-pumped high-power fibre lasers based on these novel waveguide designs and operating at desired unconventional wavelengths were investigated through numerical simulations and fibre laser experiments. Rare earth doped fibres have typically multiple emission bands of different effective strengths. Stimulate emission from strong ba...

  18. Collagen fibre arrangement in the skin of the pig.

    OpenAIRE

    Meyer, W.; Neurand, K; Radke, B

    1982-01-01

    The arrangement and proportion of collagen fibres and fibre bundles in the dermis of the pig have been investigated with light microscopical (Nomarski's interference contrast, polarization optics) and scanning electron microscopical methods. Skin samples were obtained from different body regions of wild boars, domestic pigs and miniature pigs. All the methods used have demonstrated that the bulk of the dermis is dominated by a massive three dimensional network of collagen fibres and fibre bun...

  19. Fibre Bragg Grating Components for Filtering, Switching and Lasing

    OpenAIRE

    Yu, Zhangwei

    2008-01-01

    Fibre Bragg gratings (FBGs) are key components for a vast number of applications in optical communication systems, microwave photonics systems, and optical sensors, etc. The main topic of this thesis is fibre Bragg grating fabrication and applications in direct microwave optical filtering, high speed switching and switchable dual-wavelength fibre lasers. First, a brief overview is given about the photosensitivity in optical fibre, basic FBG fabrication techniques, the popular coupled-mode the...

  20. Investigation of digital light processing using fibre-reinforced polymers

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; Pedersen, David Bue; Nielsen, Jakob Skov;

    2016-01-01

    fibre length and shape compared to layer thickness has been investigated including concepts to circumvent clustering of the fibres.This research contributes to the implementation of fibre-reinforced polymers in additive manufacturing technologies. Digital light processing allows generation of...... miniaturized objects with relatively high surface quality compared to other additive manufacturing technologies. This paper aim to move fibre reinforced resin parts one step closer towards mechanically strong production-quality components....