30 research outputs found
Systematic Effects on Determination of the Growth Factor from Redshift-space Distortions
The linear growth factor of density perturbations is believed to be a
powerful observable of future redshift surveys to probe physical properties of
dark energy and to distinguish among gravity theories. We investigate
systematic effects on determination of the growth factor f from a measurement
of redshift-space distortions. Using N-body simulations we identify dark matter
halos over a broad mass range. We compute the power spectra and correlation
functions for the halos and then examine how well the redshift distortion
parameter beta=f/b can be reconstructed as a function of halo mass. We find
that beta measured for a fixed halo mass is generally a function of scale even
on large scales, in contrast with the common expectation that beta approaches a
constant described by Kaiser's formula on such scales. The scale dependence
depends on the halo mass, being stronger for smaller halos. It also cannot be
easily explained with the well-known distribution function of the halo peculiar
velocities. We demonstrate that the biasing for smaller halos has larger
nonlinearity and stochasticity, thus the linear bias assumption becomes worse
for smaller halos. Only for massive halos with b>1.5, beta approaches the
linear theory prediction on scales of r or pi/k>30Mpc/h. Luminous red galaxies
(LRG), targeted by the SDSS-III's BOSS survey, tend to reside in very massive
halos. Our results indicate that if the LRG is used for the measurement of
redshift distortions, f can be measured unbiasedly. On the other hand, if one
considers to use emission line galaxies, which are targeted by the BigBOSS
survey and inhabited in halos of a broad mass range, the scale dependence of
beta must be taken into account carefully; otherwise one might give incorrect
constraints on dark energy or modified gravity theories. We also find that beta
reconstructed in Fourier space behaves better than that in configuration space.Comment: 12 pages, 9 figures, submitted to ApJ, revised according to referee
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Methylprednisolone pulse therapy combined with mizoribine following tonsillectomy for immunoglobulin A nephropathy: clinical remission rate, steroid sparing effect, and maintenance of renal function
Neuronal activity in medial superior temporal area (MST) during memory-based smooth pursuit eye movements in monkeys
We examined recently neuronal substrates for predictive pursuit using a memory-based smooth pursuit task that distinguishes the discharge related to memory of visual motion-direction from that related to movement preparation. We found that the supplementary eye fields (SEF) contain separate signals coding memory and assessment of visual motion-direction, decision not-to-pursue, and preparation for pursuit. Since medial superior temporal area (MST) is essential for visual motion processing and projects to SEF, we examined whether MST carried similar signals. We analyzed the discharge of 108 MSTd neurons responding to visual motion stimuli. The majority (69/108 = 64%) were also modulated during smooth pursuit. However, in nearly all (104/108 = 96%) of the MSTd neurons tested, there was no significant discharge modulation during the delay periods that required memory of visual motion-direction or preparation for smooth pursuit or not-to-pursue. Only 4 neurons of the 108 (4%) exhibited significantly higher discharge rates during the delay periods; however, their responses were non-directional and not instruction specific. Representative signals in the MSTd clearly differed from those in the SEF during memory-based smooth pursuit. MSTd neurons are unlikely to provide signals for memory of visual motion-direction or preparation for smooth pursuit eye movements
Transcranial color-coded sonography of vertebral artery for diagnosis of right-to-left shunts.
Pseudomyopathic Changes in Needle Electromyography in Lambert-Eaton Myasthenic Syndrome
Lambert-Eaton myasthenic syndrome (LEMS) is a rare presynaptic disorder of the neuromuscular junction in association with cancer and subsequently in cases in which no neoplasm has been detected (O’Neill et al., 1988). The diagnosis of LEMS is based on the combination of fluctuating muscle weakness, diminished or absent reflexes, and a more than 60% increment of compound muscle action potential (CMAP) amplitude after brief exercise or 50 Hz stimulation for 1 s in a repetitive nerve stimulation (RNS) test (Oh et al., 2005). On the other hand, needle electromyography (EMG) findings related to LEMS have not been well described. Here, we report a case of LEMS, which showed apparent myopathic changes in needle EMG findings. Furthermore, we retrospectively examined the needle EMG findings in 8 patients with LEMS. In six of the 8 patients, the EMG findings showed myopathy-like findings. Although the findings of needle EMG indicated myopathic changes at a glance, the motor unit potential (MUP) returned to normal after a sustained strong muscle contraction. We propose the name “pseudomyopathic changes” for this phenomenon