Spatiotemporal symmetries in the disynaptic canal-neck projection

The vestibular system in almost all vertebrates, and in particular in humans, controls balance by employing a set of six semicircular canals, three in each inner ear, to detect angular accelerations of the head in three mutually orthogonal coordinate planes. Signals from the canals are transmitted to eight (groups of) neck motoneurons, which activate the eight corresponding muscle groups. These signals may be either excitatory or inhibitory, depending on the direction of head acceleration. McCollum and Boyle have observed that in the cat the relevant network of neurons possesses octahedral symmetry, a structure that they deduce from the known innervation patterns (connections) from canals to muscles. We rederive the octahedral symmetry from mathematical features of the probable network architecture, and model the movement of the head in response to the activation patterns of the muscles concerned. We assume that connections between neck muscles can be modeled by a “coupled cell network,” a system of coupled ODEs whose variables correspond to the eight muscles, and that this network also has octahedral symmetry. The network and its symmetries imply that these ODEs must be equivariant under a suitable action of the octahedral group. It is observed that muscle motoneurons form natural “push-pull pairs” in which, for given movements of the head, one neuron produces an excitatory signal, whereas the other produces an inhibitory signal. By incorporating this feature into the mathematics in a natural way, we are led to a model in which the octahedral group acts by signed permutations on muscle motoneurons. We show that with the appropriate group actions, there are six possible spatiotemporal patterns of time-periodic states that can arise by Hopf bifurcation from an equilibrium representing an immobile head. Here we use results of Ashwin and Podvigina. Counting conjugate states, whose physiological interpretations can have significantly different features, there are 15 patterns of periodic oscillation, not counting left-right reflections or time-reversals as being different. We interpret these patterns as motions of the head, and note that all six types of pattern appear to correspond to natural head motions

Classical and Quantum Cosmology of Multigravity

Recently, a multigraviton theory on a simple closed circuit graph corresponding to the discretization of $S^1$ compactification of the Kaluza-Klein (KK) theory has been considered. In the present paper, we extend this theory to that on a general graph and study what modes of particles are included. Furthermore, we generalize it in a possible nonlinear theory based on the vierbein formalism and study classical and quantum cosmological solutions in the theory. We found that scale factors in a solution for this theory repeat acceleration and deceleration.Comment: 17 pages, 15 figures, RevTeX4.1, revised versio

Atmospheric response to observed intraseasonal tropical sea surface temperature anomalies

The major tropical convective and circulation features of the intraseasonal or Madden-Julian Oscillation (MJO) are simulated as a passive response to observed MJO sea surface temperature (SST) anomalies in an atmospheric general circulation model (AGCM), strengthening the case for ocean-atmosphere interactions being central to MJO dynamics. However, the magnitude of the surface fluxes diagnosed from the MJO cycle in the AGCM, that would feed back onto the ocean in a coupled system, are much weaker than in observations. The phasing of the convective-dynamical model response to the MJO SST anomalies and the associated surface flux anomalies is too fast compared to observations of the (potentially) coupled system, and would act to damp the SST anomalies

Surface MIMO: Using Conductive Surfaces For MIMO Between Small Devices

As connected devices continue to decrease in size, we explore the idea of leveraging everyday surfaces such as tabletops and walls to augment the wireless capabilities of devices. Specifically, we introduce Surface MIMO, a technique that enables MIMO communication between small devices via surfaces coated with conductive paint or covered with conductive cloth. These surfaces act as an additional spatial path that enables MIMO capabilities without increasing the physical size of the devices themselves. We provide an extensive characterization of these surfaces that reveal their effect on the propagation of EM waves. Our evaluation shows that we can enable additional spatial streams using the conductive surface and achieve average throughput gains of 2.6-3x for small devices. Finally, we also leverage the wideband characteristics of these conductive surfaces to demonstrate the first Gbps surface communication system that can directly transfer bits through the surface at up to 1.3 Gbps.Comment: MobiCom '1

Minor Immunoreactivity in GDNF-, BDNF-, or NT-3-Treated Substantia Nigra Allografts

Glial-cell-line-derived neurotrophic factor (GDNF) stimulates the survival of dopaminergic neurons. Little is known, however, about the possible immune sequelae of GDNF exposure or of exposure to other putative trophic factors. To address these questions, pieces of mesencephalic tissue, substantia nigra, from 15-day-old donor embryos were transplanted into the anterior chamber of the eye of adult male Sprague- Dawley recipient rats. At 5-day intervals, an aliquot (0.5 μg) of GDNF, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), or cytochrome-C (CC) was injected into the anterior chamber of the eye of the recipients, and the sizes of the transplants were measured. GDNF increased transplant survival and growth. On day 42, all rats were sacrificed, and the grafts were evaluated by cresyl-violet staining and by immunohistochemistry using antibodies raised against neurofilament (NF), tyrosine hydroxylase, or glial fibrillary acidic protein (GFAP), as well as the following monoclonai antibodies: OX-38 anti-CD4, OX-8 anti-CD8, OX-18 anti-MHC class I, OX-6 anti- MHC class II, OX-42 anti-CD11b, R-73 anti-α and anti-β T-cell receptor, and EDI raised against monocytes/macrophages. BDNF-treated grafts showed only weak immunoreactivity, and even weaker reactions were seen in grafts treated with NT-3, GDNF, or CC. No single immune system marker was significantly elevated in grafts from any treatment group. We used OX-42 and EDI to study possible alterations of microglial components. Ramified microglial cells were found in GDNF-treated grafts and to a lesser extent in NT-3 and BDNF-treated grafts. EDl-labeled reactive microglial components were found in NT-3- and BDNF-treated grafts. Additionally, large and rounded OX-42-positive phagocytic cells were found in NT-3-treated grafts. Together with our previous finding that GDNF treatment of spinal cord transplants activates immune responses and leads to microglial activation, our data dempnstrate that although treatment with GDNF and to some degree with BDNF can enhance immune responses to immunogenic grafts, such as fetal spinal cord grafts, but the trophic factors per se do not elicit any marked response in non-immunogenic grafts like substantia nigra

Irreducible characters of GSp(4, q) and dimensions of spaces of fixed vectors

In this paper, we compute the conjugacy classes and the list of irreducible characters of GSp(4,q), where q is odd. We also determine precisely which irreducible characters are non-cuspidal and which are generic. These characters are then used to compute dimensions of certain subspaces of fixed vectors of smooth admissible non-supercuspidal representations of GSp(4,F), where F is a non-archimedean local field of characteristic zero with residue field of order q.Comment: 48 pages, 21 tables. Corrected an error in Table 16 for type V* representations (theta_11 and theta_12 were switched

Ocean temperature and salinity components of the Madden-Julian oscillation observed by Argo floats

New diagnostics of the Madden-Julian Oscillation (MJO) cycle in ocean temperature and, for the first time, salinity are presented. The MJO composites are based on 4 years of gridded Argo float data from 2003 to 2006, and extend from the surface to 1,400 m depth in the tropical Indian and Pacific Oceans. The MJO surface salinity anomalies are consistent with precipitation minus evaporation fluxes in the Indian Ocean, and with anomalous zonal advection in the Pacific. The Argo sea surface temperature and thermocline depth anomalies are consistent with previous studies using other data sets. The near-surface density changes due to salinity are comparable to, and partially offset, those due to temperature, emphasising the importance of including salinity as well as temperature changes in mixed-layer modelling of tropical intraseasonal processes. The MJO-forced equatorial Kelvin wave that propagates along the thermocline in the Pacific extends down into the deep ocean, to at least 1,400 m. Coherent, statistically significant, MJO temperature and salinity anomalies are also present in the deep Indian Ocean

Recent X-ray measurements of the accretion-powered pulsar 4U 1907+09

X-ray observations of the accreting X-ray pulsar 4U~1907+09, obtained during February 1996 with the Proportional Counter Array on the Rossi X-ray Timing Experiment (RXTE), have enabled the first measurement of the intrinsic pulse period Ppulse since 1984: Ppulse=440.341[+0.012,-0.017] s. 4U 1907+09 is in a binary system with a blue supergiant. The orbital parameters were solved and this enabled the correction for orbital delay effects of a measurement of Ppulse obtained in 1990 with Ginga. Thus, three spin down rates could be extracted from four pulse periods obtained in 1983, 1984, 1990, and 1996. These are within 8% equal to a value of dPpulse/dt=+0.225 s/yr. This suggest that the pulsar is perhaps in a monotonous spin down mode since its discovery in 1983. Furthermore, the RXTE observations show transient ~18 s oscillations during a flare that lasted about 1 hour. The oscillations may be interpreted as Keplerian motion of an accretion disk near the magnetospheric radius. This, and the notion that the co-rotation radius is much larger than any conceivable value for the magnetospheric radius (because of the long spin period), renders it unlikely that this pulsar spins near equilibrium like is suspected for other slowing accreting X-ray pulsars. We suggest as an alternative that perhaps the frequent occurrence of a retrograde transient accretion disk may be consistently slowing the pulsar down. Further observations of flares can provide more evidence of this.Comment: 26 pages, 11 figures, to be published in Astrophysical Journal part I on March 20, 199

Satellite glial cell P2Y12 receptor in the trigeminal ganglion is involved in lingual neuropathic pain mechanisms in rats

<p>Abstract</p> <p>Background</p> <p>It has been reported that the P2Y₁₂receptor (P2Y₁₂R) is involved in satellite glial cells (SGCs) activation, indicating that P2Y₁₂R expressed in SGCs may play functional roles in orofacial neuropathic pain mechanisms. However, the involvement of P2Y₁₂R in orofacial neuropathic pain mechanisms is still unknown. We therefore studied the reflex to noxious mechanical or heat stimulation of the tongue, P2Y₁₂R and glial fibrillary acidic protein (GFAP) immunohistochemistries in the trigeminal ganglion (TG) in a rat model of unilateral lingual nerve crush (LNC) to evaluate role of P2Y₁₂R in SGC in lingual neuropathic pain.</p> <p>Results</p> <p>The head-withdrawal reflex thresholds to mechanical and heat stimulation of the lateral tongue were significantly decreased in LNC-rats compared to sham-rats. These nocifensive effects were apparent on day 1 after LNC and lasted for 17 days. On days 3, 9, 15 and 21 after LNC, the mean relative number of TG neurons encircled with GFAP-immunoreactive (IR) cells significantly increased in the ophthalmic, maxillary and mandibular branch regions of TG. On day 3 after LNC, P2Y₁₂R expression occurred in GFAP-IR cells but not neuronal nuclei (NeuN)-IR cells (i.e. neurons) in TG. After 3 days of successive administration of the P2Y₁₂R antagonist MRS2395 into TG in LNC-rats, the mean relative number of TG neurons encircled with GFAP-IR cells was significantly decreased coincident with a significant reversal of the lowered head-withdrawal reflex thresholds to mechanical and heat stimulation of the tongue compared to vehicle-injected rats. Furthermore, after 3 days of successive administration of the P2YR agonist 2-MeSADP into the TG in naïve rats, the mean relative number of TG neurons encircled with GFAP-IR cells was significantly increased and head-withdrawal reflex thresholds to mechanical and heat stimulation of the tongue were significantly decreased in a dose-dependent manner compared to vehicle-injected rats.</p> <p>Conclusions</p> <p>The present findings provide the first evidence that the activation of P2Y₁₂R in SGCs of TG following lingual nerve injury is involved in the enhancement of TG neuron activity and nocifensive reflex behavior, resulting in neuropathic pain in the tongue.</p

Stabilisation of Na,K-ATPase structure by the cardiotonic steroid ouabain

Cardiotonic steroids such as ouabain bind with high affinity to the membrane-bound cation-transporting P-type Na,K-ATPase, leading to complete inhibition of the enzyme. Using synchrotron radiation circular dichroism we show that the enzyme-ouabain complex is less susceptible to thermal denaturation (unfolding) than the ouabain-free enzyme, and this protection is observed with Na,K-ATPase purified from pig kidney as well as from shark rectal glands. It is also shown that detergent-solubilised preparations of Na,K-ATPase are stabilised by ouabain, which could account for the successful crystallisation of Na,K-ATPase in the ouabain-bound form. The secondary structure is not significantly affected by the binding of ouabain. Ouabain appears however, to induce a reorganization of the tertiary structure towards a more compact protein structure which is less prone to unfolding; recent crystal structures of the two enzymes are consistent with this interpretation. These circular dichroism spectroscopic studies in solution therefore provide complementary information to that provided by crystallography