We measure the power spectrum, P F (k, z), of the transmitted flux in the Lyα forest using 3035 high redshift quasar spectra from the Sloan Digital Sky Survey. This sample is almost two orders of magnitude larger than any previously available data set, yielding statistical errors of ∼ 0.6% and ∼ 0.005 on, respectively, the overall amplitude and logarithmic slope of P F (k, z). This unprecedented statistical power requires a correspondingly careful analysis of the data and of possible systematic contaminations in it. For this purpose we reanalyze the raw spectra to make use of information not preserved by the standard pipeline. We investigate the details of the noise in the data, resolution of the spectrograph, sky subtraction, quasar continuum, and metal absorption. We find that background sources such as metals contribute significantly to the total power and have to be subtracted properly. We also find clear evidence for SiIII correlations with the Lyα forest and suggest a simple model to account for this contribution to the power. While it is likely that our newly developed analysis technique does not eliminate all systematic errors in the P F (k, z) measurement below the level of the statistical errors, our tests indicate that any residual systematics in the analysis are unlikely to affect the inference of cosmological parameters from P F (k, z). These results should provide an essential ingredient for all future attempts to constrain modeling of structure formation, cosmological parameters, and theories for the origin of primordial fluctuations.

We analyze the SDSS Lyα forest P F (k, z) measurement to determine the linear theory power spectrum. Our analysis is based on fully hydrodynamic simulations, extended using hydro-PM simulations. We account for the effect of absorbers with damping wings, which leads to an increase in the slope of the linear power spectrum. We break the degeneracy between the mean level of absorption and the linear power spectrum without significant use of external constraints. We infer linear theory power spectrum amplitude ∆ 2 L (k p = 0.009 s/km, z p = 3.0) = 0.452 +0.069 +0.141 −0.057 −0.116 and slope n eff (k p , z p ) = −2.321 +0.055 +0.131 −0.047 −0.102 (possible systematic errors are included through nuisance parameters in the fit -a factor 5 smaller errors would be obtained on both parameters if we ignored modeling uncertainties). The errors are correlated and not perfectly Gaussian, so we provide a χ 2 table to accurately describe the results. The result corresponds to σ 8 = 0.85, n = 0.94, for a ΛCDM model with Ω m = 0.3, Ω b = 0.04, and h = 0.7, but is most useful in a combined fit with the CMB. The inferred curvature of the linear power spectrum and the evolution of its amplitude and slope with -2redshift are consistent with expectations for ΛCDM models, with the evolution of the slope, in particular, being tightly constrained. We use this information to constrain systematic contamination, e.g., fluctuations in the UV background. This paper should serve as a starting point for more work to refine the analysis, including technical improvements such as increasing the size and number of the hydrodynamic simulations, and improvements in the treatment of the various forms of feedback from galaxies and quasars.Subject headings: cosmology: theory-intergalactic medium-large-scale structure of universe-quasars: absorption lines

We report the structural, electrical and optical properties of bulk InAsN alloy with various nitrogen contents deposited on (100) InP substrates using plasma-assisted gas-source molecular beam epitaxy. From absorption measurements, it is found that the fundamental absorption energy of InAsN is higher than that of InAs due to the Burstein-Moss effect resulting from the high residual carrier concentration in InAsN. To deduce the 'real' band-gap energy of InAsN samples, the energy shift due to the Burstein-Moss effect and the band-gap narrowing effect are calculated by using a self-consistent approach based on the band-anticrossing (BAC) model [Shan et al.: Phys. Rev. Lett. 82 (1999) 1221. After correction, the 'real' band-gap energy of InAsN samples decreases as N increases. The electron effective mass of InAsN is also investigated by plasma-edge measurement. We found a sizeable increase of the electron effective mass in these InAsN alloys, which is consistent with the theoretical predictions based on the BAC model.

The water level of ®ve river stages and seven groundwater wells in the Taipei Basin were analysed by spectral analysis in the frequency domain. The diurnal, semi-diurnal and quarter-diurnal tidal components of the Tanshui River appear to relate closely to astronomical tides as K 1 , M 2 and M 4 , respectively. It is also found that the diurnal component reveals a reversed phase angle in the middle section of the Tanshui River; the phase of the quarter-diurnal component is also found to be reversed at stations upstream in the Tanshui River and Hsintien Stream. It is believed that these phenomena could be caused by local variation in the river channel topography. The autospectrum and cross-spectrum between groundwater elevation and nearby river stage were observed to correlate highly with the frequency of the astronomical tides K 1 , M 2 and M 4 . From the study of the phase shift and time lag of water level¯uctuations at river stages and groundwater wells, it was found that the tidal eects of diurnal, semi-diurnal, and quarter-diurnal components were signi®cantly dierent. The relationships between phase and the¯uctuated range of atmospheric pressure and water level imply that change in atmospheric pressure does not aect water level¯uctuation in the river stage and groundwater well.

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Water level data at 16 ground water wells and two sea water gauging stations, coupled with barometric measurements in an alluvial plain in the central‐west region of Taiwan, are analyzed using spectral analysis in the time and frequency domains. The semi‐diurnal component from water level station is observed to be the most noticeable signal while the diurnal component is the less distinct signal recorded at the water level stations. Both semidiurnal and diurnal components are coupled with atmospheric pressure measurements. From the atmospheric pressure data, spectral analysis indicates that both the raw and the pressure adjusted water levels are almost in phase and retain the same amplitude in this area. It implies that the effect of pressure variations is not significant for the sea water and ground water level nearby; the astronomical tidal components, as expected, are the main factor causing fluctuation of ocean water and ground water levels in the Choshuihsi alluvial plain.

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The water level of a seawater gauging station and 18 groundwater wells coupled with atmospheric pressure in southwestern Taiwan are analyzed by using spectral analysis in time and frequency domain. The semidiurnal component is found to be the most significant signal from the measurement of water level and atmospheric pressure, and the diurnal component is less distinctive in part of water level and atmospheric pressure record. Although auto-spectral and crossspectral density functions are significant in atmospheric pressure and water level, the pressure variations do not significantly affect the seawater and the majority of groundwater level in the study area with amplitude of time series observations. The astronomical tidal components are likely the main factor causing seawater and groundwater level to fluctuate in Pingtung, Taiwan. Time lags are estimated from 20 min to a few hours in aquifers. It concludes that the disturbance on groundwater levels from the effect of oceanic astronomical tide is different from the varying hydrogeological characteristics of aquifer. In this study, the spectral analysis of water level in time and frequency domains gives strong indications of sensitive variations to water level fluctuation.