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Operators are pressured to maximize the achieved capacity over deployed links. This can be obtained by operating in the weakly nonlinear regime, requiring a precise understanding of the transmission conditions. Ideally, optical transponders should be capable of estimating the regime of operation from the received signal and feeding that information to the upper management layers to optimize the transmission characteristics; however, this estimation is challenging. This paper addresses this problem by estimating the linear and nonlinear signal-to-noise ratio (SNR) from the received signal. This estimation is performed by obtaining features of two distinct effects: nonlinear phase noise and second-order statistical moments. A small neural network is trained to estimate the SNRs from the extracted features. Over extensive simulations covering 19,800 sets of realistic fiber transmissions, we verified the accuracy of the proposed techniques. Employing both approaches simultaneously gave measured performances of 0.04 and 0.20 dB of standard error for the linear and nonlinear SNRs, respectively. [ABSTRACT FROM AUTHOR]

ULTRASPEC is a high-speed imaging photometer mounted permanently at one of the Nasmyth focii of the 2.4-m Thai National Telescope (TNT) on Doi Inthanon, Thailand's highest mountain. ULTRASPEC employs a 1024 × 1024 pixel frame-transfer, electron-multiplying CCD (EMCCD) in conjunction with re-imaging optics to image a field of 7.7 × 7.7 arcmin2 at (windowed) frame rates of up to ∼200 Hz. The EMCCD has two outputs – a normal output that provides a readout noise of 2.3 e− and an avalanche output that can provide essentially zero readout noise. A six-position filter wheel enables narrow-band and broad-band imaging over the wavelength range 330–1000 nm. The instrument saw first light on the TNT in 2013 November and will be used to study rapid variability in the Universe. In this paper we describe the scientific motivation behind ULTRASPEC, present an outline of its design and report on its measured performance on the TNT. [ABSTRACT FROM AUTHOR]

The dichotomy between acoustic temporal envelope (ENV) and fine structure (TFS) cues has stimulated numerous studies over the past decade to understand the relative role of acoustic ENV and TFS in human speech perception. Such acoustic temporal speech cues produce distinct neural discharge patterns at the level of the auditory nerve, yet little is known about the central neural mechanisms underlying the dichotomy in speech perception between neural ENV and TFS cues. We explored the question of how the peripheral auditory system encodes neural ENV and TFS cues in steady or fluctuating background noise, and how the central auditory system combines these forms of neural information for speech identification. We sought to address this question by (1) measuring sentence identification in background noise for human subjects as a function of the degree of available acoustic TFS information and (2) examining the optimal combination of neural ENV and TFS cues to explain human speech perception performance using computational models of the peripheral auditory system and central neural observers. Speech-identification performance by human subjects decreased as the acoustic TFS information was degraded in the speech signals. The model predictions best matched human performance when a greater emphasis was placed on neural ENV coding rather than neural TFS. However, neural TFS cues were necessary to account for the full effect of background-noise modulations on human speech-identification performance. [ABSTRACT FROM AUTHOR]

Background: Among women aged 50 to 59 years at baseline in the Women's Health Initiative (WHI) Estrogen‐Alone (E‐Alone) trial, randomization to conjugated equine estrogen‐alone versus placebo was associated with lower risk of myocardial infarction and mortality, and, in an ancillary study, the WHI‐CACS (WHI Coronary Artery Calcification Study) with lower CAC, measured by cardiac computed tomography ≈8.7 years after baseline randomization. We hypothesized that higher CAC would be related to post‐trial coronary heart disease (CHD), cardiovascular disease (CVD), and total mortality, independent of baseline randomization or risk factors. Methods and Results: WHI‐CACS participants (n=1020) were followed ≈8 years from computed tomography scan in 2005 (mean age=64.4) through 2013 for incident CHD (myocardial infarction and fatal CHD, n=17), CVD (n=69), and total mortality (n=55). Incident CHD and CVD analyses excluded women with CVD before scan (n=89). Women with CAC=0 (n=54%) had very low age‐adjusted rates/1000 person‐years of CHD (0.91), CVD (5.56), and mortality (3.45). In comparison, rates were ≈2‐fold higher for women with any CAC (>0). Associations were not modified by baseline randomization to conjugated equine estrogen–alone versus placebo. Adjusted for baseline randomization and risk factors, the hazard ratio (95% confidence interval) for CAC >100 (19%) was 4.06 (2.11, 7.80) for CVD and 2.70 (1.26, 5.79) for mortality. Conclusions: Among a subset of postmenopausal women aged 50 to 59 years at baseline in the WHI E‐Alone Trial, CAC at mean age of 64 years was strongly related to incident CHD, CVD, and to total mortality over ≈8 years, independent of baseline randomization to conjugated equine estrogen–alone versus placebo or CVD risk factors. Clinical Trial Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT00000611.

The goal of noise reduction (NR) algorithms in digital hearing aid devices is to reduce background noise whilst preserving as much of the original signal as possible. These algorithms may increase the signal-to-noise ratio (SNR) in an ideal case, but they generally fail to improve speech intelligibility. However, due to the complex nature of speech, it is difficult to disentangle the numerous low- and high-level effects of NR that may underlie the lack of speech perception benefits. The goal of this study was to better understand why NR algorithms do not improve speech intelligibility by investigating the effects of NR on the ability to discriminate two basic acoustic features, namely amplitude modulation (AM) and frequency modulation (FM) cues, known to be crucial for speech identification in quiet and in noise. Here, discrimination of complex, non-linguistic AM and FM patterns was measured for normal hearing listeners using a same/different task. The stimuli were generated by modulating 1-kHz pure tones by either a two-component AM or FM modulator with patterns changed by manipulating component phases. Modulation rates were centered on 3 Hz. Discrimination of AM and FM patterns was measured in quiet and in the presence of a white noise that had been passed through a gammatone filter centered on 1 kHz. The noise was presented at SNRs ranging from −6 to +12 dB. Stimuli were left as such or processed via an NR algorithm based on the spectral subtraction method. NR was found to yield small but systematic improvements in discrimination for the AM conditions at favorable SNRs but had little effect, if any, on FM discrimination. A computational model of early auditory processing was developed to quantify the fidelity of AM and FM transmission. The model captured the improvement in discrimination performance for AM stimuli at high SNRs with NR. However, the model also predicted a relatively small detrimental effect of NR for FM stimuli in contrast with the average psychophysical data. Overall, these results suggest that the lack of benefits of NR on speech intelligibility is partly caused by the limited effect of NR on the transmission of narrowband speech modulation cues. [ABSTRACT FROM AUTHOR]

Location and acoustic scale cues have both been shown to have an effect on the recognition of speech in multi-speaker environments. This study examines the interaction of these variables. Subjects were presented with concurrent triplets of syllables from a target voice and a distracting voice, and asked to recognize a specific target syllable. The task was made more or less difficult by changing (a) the location of the distracting speaker, (b) the scale difference between the two speakers, and/or (c) the relative level of the two speakers. Scale differences were produced by changing the vocal tract length and glottal pulse rate during syllable synthesis: 32 acoustic scale differences were used. Location cues were produced by convolving head-related transfer functions with the stimulus. The angle between the target speaker and the distracter was 0°, 4°, 8°, 16°, or 32° on the 0° horizontal plane. The relative level of the target to the distracter was 0 or -6 dB. The results show that location and scale difference interact, and the interaction is greatest when one of these cues is small. Increasing either the acoustic scale or the angle between target and distracter speakers quickly elevates performance to ceiling levels. [ABSTRACT FROM AUTHOR]

A melodic pitch experiment was performed to demonstrate the importance of time-interval resolution for pitch strength. The experiments show that notes with a low fundamental (75 Hz) and relatively few resolved harmonics support better performance than comparable notes with a higher fundamental (300 Hz) and more resolved harmonics. Two four note melodies were presented to listeners and one note in the second melody was changed by one or two semitones. Listeners were required to identify the note that changed. There were three orthogonal stimulus dimensions: F0 (75 and 300 Hz); lowest frequency component (3, 7, 11, or 15); and number of harmonics (4 or 8). Performance decreased as the frequency of the lowest component increased for both F0’s, but performance was better for the lower F0. The spectral and temporal information in the stimuli were compared using a time-domain model of auditory perception. It is argued that the distribution of time intervals in the auditory nerve can explain the decrease in performance as F0, and spectral resolution increase. Excitation patterns based on the same time-interval information do not contain sufficient resolution to explain listener’s performance on the melody task. [ABSTRACT FROM AUTHOR]

ULTRACAM is a portable, high-speed imaging photometer designed to study faint astronomical objects at high temporal resolutions. ULTRACAM employs two dichroic beamsplitters and three frame-transfer CCD cameras to provide three-colour optical imaging at frame rates of up to 500 Hz. The instrument has been mounted on both the 4.2-m William Herschel Telescope on La Palma and the 8.2-m Very Large Telescope in Chile, and has been used to study white dwarfs, brown dwarfs, pulsars, black hole/neutron star X-ray binaries, gamma-ray bursts, cataclysmic variables, eclipsing binary stars, extrasolar planets, flare stars, ultracompact binaries, active galactic nuclei, asteroseismology and occultations by Solar System objects (Titan, Pluto and Kuiper Belt objects). In this paper we describe the scientific motivation behind ULTRACAM, present an outline of its design and report on its measured performance. [ABSTRACT FROM AUTHOR]

A fast and accurate magnified near-field (NF) measurement technique that employs a charge-coupled device (CCD) camera is described to measure the two-dimensional (2-D) intensity distributions of optical waveguides with arbitrary refractive-index profiles. Calibration of the InGaAs CCD camera used in the system is essential in terms of correction for bad pixels, linearity, and uniformity in order to obtain accurate results. The magnification factor of the system is obtained using a calibrated optical dimensional standard. The NF measurement system with the calibrated CCD camera is validated from the mode field diameter (MFD) measured for six single-mode fibers with different refractive-index profiles. The MFD results from the magnified NF technique exhibit good agreement with those obtained from the far-field scanning technique to within 2.3%. An error of about 15% in the MFD would result if corrections to the CCD camera were not applied to the raw measured data. The refractive-index profiles computed from the measured data for a single-mode fiber and a Ti:LiNbO3 waveguide are also presented. The radial-index profile of the fiber exhibits good agreement with the profile measured from the refracted NF technique [ABSTRACT FROM PUBLISHER]

The length of the vocal tract is correlated with speaker size and, so, speech sounds have information about the size of the speaker in a form that is interpretable by the listener. A wide range of different vocal tract lengths exist in the population and humans are able to distinguish speaker size from the speech. Smith et al. [J. Acoust. Soc. Am. 117, 305–318 (2005)] presented vowel sounds to listeners and showed that the ability to discriminate speaker size extends beyond the normal range of speaker sizes which suggests that information about the size and shape of the vocal tract is segregated automatically at an early stage in the processing. This paper reports an extension of the size discrimination research using a much larger set of speech sounds, namely, 180 consonant-vowel and vowel-consonant syllables. Despite the pronounced increase in stimulus variability, there was actually an improvement in discrimination performance over that supported by vowel sounds alone. Performance with vowel-consonant syllables was slightly better than with consonant-vowel syllables. These results support the hypothesis that information about the length of the vocal tract is segregated at an early stage in auditory processing. [ABSTRACT FROM AUTHOR]

The article presents a discussion of the philosophy and concept of the Senior Executive Service (SES) in the Australian Public Service, adapted from a paper presented to a seminar on "Managing the Public Process: Issues for the '90's," at the Australian National University, Canberra, on June 3-4,1991.

Background and Purpose: Data from randomized clinical trials in Scotland and Sweden testing the efficacy of tamoxifen therapy in patients with breast cancer have suggested that the drug may also reduce the risk of coronary heart disease. In view of these findings, we examined mortality from coronary heart disease among patients with early stage breast cancer who were enrolled in the National Surgical Adjuvant Breast and Bowel Project B-14 trial of tamoxifen therapy.Methods: Deaths occurring among women who were randomly assigned to 5 years of either tamoxifen or placebo in the first phase of the B-14 trial were reviewed to determine the cause. Three categories of heart disease-related death were defined: 1) death from a definite fatal myocardial infarction, 2) death from definite fatal coronary heart disease/possible myocardial infarction, and 3) death from possible fatal coronary heart disease. Comparisons of the findings by treatment group were made on the basis of average annual hazard (i.e., death) rates and the corresponding relative hazard of death.Results: The average annual death rate from coronary heart disease was lower for patients who received tamoxifen than for patients who received placebo, but the difference was not statistically significant. There were eight definite heart-related deaths (i.e., definite fatal myocardial infarction or definite fatal coronary heart disease/possible myocardial infarction) among the patients who received tamoxifen, yielding an average annual rate of 0.62 per 1000 patients. There were 12 definite heart-related deaths among the patients who received placebo, yielding an average annual rate of 0.94 per 1000. The corresponding relative hazard of death from definite fatal heart disease (tamoxifen versus placebo) was 0.66 (95% confidence interval = 0.27-1.61). Eleven deaths in the tamoxifen group and 10 deaths in the placebo group were classified as possible cases of fatal coronary heart disease. When these cases and the definite cases were considered together, the average annual death rate for the patients who received tamoxifen was 1.48 per 1000, and the rate for the patients who received placebo was 1.73 per 1000. The corresponding relative hazard of death was 0.85 (95% confidence interval = 0.46-1.58).Conclusions: The findings from the B-14 trial are consistent with the findings from the Scottish and the Swedish trials, suggesting that tamoxifen treatment reduces coronary heart disease among patients with breast cancer. Continued follow-up of the patients in these trials and in ongoing prevention trials is needed to accumulate enough data so that reliable conclusions can be drawn about the benefits of tamoxifen in preventing heart disease. [ABSTRACT FROM AUTHOR]

This study compared the thiamine status of 37 elderly patients admitted with cardiac failure (CF) with that of 35 unselected elderly patients with other diagnoses (Non-CF), and with that of 41 apparently healthy elderly people. The thiamine pyrophosphate effect (TPPE) on erythrocyte transketolase activity was used to estimate thiamine status. The prevalence of thiamine deficiency (TPPE greater than 19%) on admission in the CF and Non-CF groups was 13% and 29%, respectively. The TPPE of the CF group was significantly lower than that of the Non-CF group, and was not significantly different from that of the elderly control group. The results indicate that thiamine deficiency is not common in an unselected group of elderly inpatients with cardiac failure, but a potential benefit of thiamine supplementation in such patients cannot be ruled out. [ABSTRACT FROM AUTHOR]