The sub-clinical see-saw nystagmus embedded in infantile nystagmus

AbstractA transient, decompensated vertical phoria in an individual with infantile nystagmus syndrome (INS) resulted in two images that oscillated vertically—a diplopic oscillopsia. Ocular motor studies during the vertical oscillopsia recreated by vertical prisms, led to the identification of a sub-clinical see-saw nystagmus (SSN), present under the prism-induced diplopic condition. Retrospective analysis of ocular motor recordings made prior to the above episode of vertical diplopia revealed the presence of that same sub-clinical SSN. The SSN had not been detected previously despite extensive observations and recordings of this subject’s pendular IN over a period of forty years. Three- dimensional search-coil data from fourteen additional INS subjects (with pendular and jerk waveforms) confirmed the existence of sub-clinical SSN embedded within the clinically detectable horizontal-torsional IN in seven of the fifteen and a sub-clinical, conjugate, vertical component in the remaining eight. Unlike the clinically visible SSN found in achiasma, the cause of this sub-clinical SSN is hypothesized to be due to a failure of the forces of the oblique muscles (responsible for the torsional component of the IN) to balance out the associated forces of the vertical recti; the net result is a small, sub-clinical SSN. Thus, so-called “horizontal” IN is actually a horizontal-torsional oscillation with a secondary, sub-clinical SSN or conjugate vertical component. The suppression of oscillopsia by efference copy in INS appears to be accomplished for each eye individually, even in a binocular individual. However, failure to fuse the two images results in oscillopsia of one of them

The congenital and see-saw nystagmus in the prototypical achiasma of canines: comparison to the human achiasmatic prototype

AbstractWe applied new methods for canine eye-movement recording to the study of achiasmatic mutant Belgian Sheepdogs, documenting their nystagmus waveforms and comparing them to humans with either congenital nystagmus (CN) alone or in conjunction with achiasma. A sling apparatus with head restraints and infrared reflection with either earth- or head-mounted sensors were used. Data were digitized for later evaluation. The horizontal nystagmus (1–6 Hz) was similar to that of human CN. Uniocular and disconjugate nystagmus and saccades were recorded. See-saw nystagmus (SSN), not normally seen with human CN, was present in all mutants (0.5–6 Hz) and in the one human achiasmat studied thus far. This pedigree is an animal model of CN and the SSN caused by achiasma or uniocular decussation. Given the finding of SSN in all mutant dogs and in a human, achiasma may be sufficient for the development of congenital SSN and, in human infants, SSN should alert the clinician to the possibility of either achiasma or uniocular decussation. Finally, the interplay of conjugacy and disconjugacy suggests independent ocular motor control of each eye with variable yoking in the dog

Conductance fluctuations in diffusive rings: Berry phase effects and criteria for adiabaticity

We study Berry phase effects on conductance properties of diffusive mesoscopic conductors, which are caused by an electron spin moving through an orientationally inhomogeneous magnetic field. Extending previous work, we start with an exact, i.e. not assuming adiabaticity, calculation of the universal conductance fluctuations in a diffusive ring within the weak localization regime, based on a differential equation which we derive for the diffuson in the presence of Zeeman coupling to a magnetic field texture. We calculate the field strength required for adiabaticity and show that this strength is reduced by the diffusive motion. We demonstrate that not only the phases but also the amplitudes of the h/2e Aharonov-Bohm oscillations are strongly affected by the Berry phase. In particular, we show that these amplitudes are completely suppressed at certain magic tilt angles of the external fields, and thereby provide a useful criterion for experimental searches. We also discuss Berry phase-like effects resulting from spin-orbit interaction in diffusive conductors and derive exact formulas for both magnetoconductance and conductance fluctuations. We discuss the power spectra of the magnetoconductance and the conductance fluctuations for inhomogeneous magnetic fields and for spin-orbit interaction.Comment: 18 pages, 13 figures; minor revisions. To appear in Phys. Rev.

Age-related differences in the functional topography of the locus coeruleus and their implications for cognitive and affective functions

The locus coeruleus (LC) is an important noradrenergic nucleus that has recently attracted a lot of attention because of its emerging role in cognitive and psychiatric disorders. Although previous histological studies have shown that the LC has heterogeneous connections and cellular features, no studies have yet assessed its functional topography in vivo, how this heterogeneity changes over aging, and whether it is associated with cognition and mood. Here, we employ a gradient-based approach to characterize the functional heterogeneity in the organization of the LC over aging using 3T resting-state fMRI in a population-based cohort aged from 18 to 88 years of age (Cambridge Centre for Ageing and Neuroscience cohort, n=618). We show that the LC exhibits a rostro-caudal functional gradient along its longitudinal axis, which was replicated in an independent dataset (Human Connectome Project [HCP] 7T dataset, n=184). Although the main rostrocaudal direction of this gradient was consistent across age groups, its spatial features varied with increasing age, emotional memory, and emotion regulation. More specifically, a loss of rostral-like connectivity, more clustered functional topography, and greater asymmetry between right and left LC gradients was associated with higher age and worse behavioral performance. Furthermore, participants with higher-than-normal Hospital Anxiety and Depression Scale (HADS) ratings exhibited alterations in the gradient as well, which manifested in greater asymmetry. These results provide an in vivo account of how the functional topography of the LC changes over aging, and imply that spatial features of this organization are relevant markers of LC-related behavioral measures and psychopathology. © Veréb et al

The Planetary Nebula Luminosity Function at the Dawn of Gaia

The [O III] 5007 Planetary Nebula Luminosity Function (PNLF) is an excellent extragalactic standard candle. In theory, the PNLF method should not work at all, since the luminosities of the brightest planetary nebulae (PNe) should be highly sensitive to the age of their host stellar population. Yet the method appears robust, as it consistently produces < 10% distances to galaxies of all Hubble types, from the earliest ellipticals to the latest-type spirals and irregulars. It is therefore uniquely suited for cross-checking the results of other techniques and finding small offsets between the Population I and Population II distance ladders. We review the calibration of the method and show that the zero points provided by Cepheids and the Tip of the Red Giant Branch are in excellent agreement. We then compare the results of the PNLF with those from Surface Brightness Fluctuation measurements, and show that, although both techniques agree in a relative sense, the latter method yields distances that are ~15% larger than those from the PNLF. We trace this discrepancy back to the calibration galaxies and argue that, due to a small systematic error associated with internal reddening, the true distance scale likely falls between the extremes of the two methods. We also demonstrate how PNLF measurements in the early-type galaxies that have hosted Type Ia supernovae can help calibrate the SN Ia maximum magnitude-rate of decline relation. Finally, we discuss how the results from space missions such as Kepler and Gaia can help our understanding of the PNLF phenomenon and improve our knowledge of the physics of local planetary nebulae.Comment: 12 pages, invited review at the conference "The Fundamental Cosmic Distance Scale: State of the Art and Gaia Perspective", to appear in Astrophysics and Space Scienc

ERP and four dimensions of absorptive capacity: lessons from a developing country

Enterprise resource planning systems can grant crucial strategic, operational and information-based benefits to adopting firms when implemented successfully. However, a failed implementation can often result in financial losses rather than profits. Until now, the research on the failures and successes were focused on implementations in large manufacturing and service organizations firms located in western countries, particularly in USA. Nevertheless, IT has gained intense diffusion to developing countries through declining hardware costs and increasing benefits that merits attention as much as developed countries. The aim of this study is to examine the implications of knowledge transfer in a developing country, Turkey, as a paradigm in the knowledge society with a focus on the implementation activities that foster successful installations. We suggest that absorptive capacity is an important characteristic of a firm that explains the success level of such a knowledge transfer.Publicad

The common ABCA4 variant p.Asn1868ile shows nonpenetrance and variable expression of stargardt disease when present in trans with severe variants

PURPOSE. To assess the occurrence and the disease expression of the common p.Asn1868Ile variant in patients with Stargardt disease (STGD1) harboring known, monoallelic causal ABCA4 variants. METHODS. The coding and noncoding regions of ABCA4 were sequenced in 67 and 63 STGD1 probands respectively, harboring monoallelic ABCA4 variants. In case p.Asn1868Ile was detected, segregation analysis was performed whenever possible. Probands and affected siblings harboring p.Asn1868Ile without additional variants in cis were clinically evaluated retrospe

High pTp_{T} non-photonic electron production in pp+pp collisions at s\sqrt{s} = 200 GeV

We present the measurement of non-photonic electron production at high transverse momentum ($p_T >$ 2.5 GeV/$c$) in $p$ + $p$ collisions at $\sqrt{s}$ = 200 GeV using data recorded during 2005 and 2008 by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The measured cross-sections from the two runs are consistent with each other despite a large difference in photonic background levels due to different detector configurations. We compare the measured non-photonic electron cross-sections with previously published RHIC data and pQCD calculations. Using the relative contributions of B and D mesons to non-photonic electrons, we determine the integrated cross sections of electrons ($\frac{e^++e^-}{2}$) at 3 GeV/$c < p_T <~$10 GeV/$c$ from bottom and charm meson decays to be ${d\sigma_{(B\to e)+(B\to D \to e)} \over dy_e}|_{y_e=0}$ = 4.0$\pm0.5$({\rm stat.})$\pm1.1$({\rm syst.}) nb and ${d\sigma_{D\to e} \over dy_e}|_{y_e=0}$ = 6.2$\pm0.7$({\rm stat.})$\pm1.5$({\rm syst.}) nb, respectively.Comment: 17 pages, 17 figure