A cautionary note on the use of the adaptive up-down method

Up-down staircases with equal sizes for the steps up and down are widely used to estimate detection and discrimination thresholds in psychoacoustics, but the conventional average-of-reversals estimator does not converge on its presumed percent point in Yes-No tasks or in two-alternative forced-choice detection tasks. The particular percent point of convergence is partly determined by the relative size of the steps with respect to the spread (inverse of slope) of the underlying psychometric function. In particular, threshold is increasingly underestimated as the spread of the psychometric function decreases. This characteristic may have serious consequences when thresholds estimated via up-down staircases are compared across conditions in which the spread of the psychometric function varies, because then these thresholds do not represent comparable measures of performance. This paper documents the misbehavior of the average-of-reversals estimator under up-down rules and types of forced-choice task that are in common use in psychoacoustics but which have not been studied before in simulations. It is also shown that a relatively simple modification of the up-down design (namely, using steps up and down of different size and in a certain ratio depending only on the task and the up-down rule being used) stabilizes the performance of these staircases.     

A simple model for planar dechanneling calculations

In this letter a simple procedure for calculating the initial dechanneling of ion is presented. The calculations show good agreement with both experimental data and computer simulation data on planar dechanneling.     

Measurements and calculations of photoemission from Ca

The band structure, density of states and photoemission energy distributions for calcium have been calculated from a muffin-tin potential. Photoemission energy distributions have been measured. Transitions between s-p bands are identified. Structure from the empty d-states does not contribute to the primary distribution but is observed in the scattered one.     

An adaptive procedure for categorical loudness scaling

In this study, an adaptive procedure for categorical loudness scaling is introduced and evaluated. The procedure adjusts the presentation levels to the subject's individual auditory dynamic range without employing any premeasurement and presents levels in randomized order. The procedure has been named "Oldenburg-ACALOS" (Oldenburg-Adaptive CAtegorical LOudness Scaling). It was evaluated using repeated measurements with ten subjects with normal hearing and ten subjects with sensorineural hearing impairment. The results of this investigation revealed that the adaptive procedure provides greater reliability, while being more time efficient than a reference procedure that uses constant stimuli.     

A simple procedure for electroluminescent phosphor assessment

A simple assessment procedure is described which facilitates optimal selection of an electroluminescent phosphor based on the measurement of two optically deduced energies—absorption and emission. These two energies are used as input for an appraisal analysis based on a classical configuration-coordinate diagram model of the phosphor. A phosphor performance figure-of-merit is proposed as a consequence of the formulation of this assessment procedure. This procedure is then used to rationalize the relative performance of five electroluminescent phosphors (ZnS:Mn, BaAl₂S₄:Eu, SrS:Ce, SrGa₂S₄:Ce, CaGa₂S₄:Ce). Additionally, two cathodoluminescent phosphors (ZnS:Ag and ZnS:Cu) are appraised using this methodology, suggesting that this procedure may be of some utility in the evaluation of other types of phosphors.     

A simple adaptive controller for chaos and hyperchaos synchronization

A novel and simple adaptive feedback controller is proposed for chaos and hyperchaos synchronization. In comparison with previous methods, the present control scheme is not only simple but employs only one control strength, converges very fast and also suitable for a large class of chaotic and hyperchaotic systems. In addition, the synchronization is efficient in the presence of noise. Numerical simulations are used to validate and demonstrate the effectiveness of the method.     

Standard Model theory calculations and experimental tests

To present knowledge, all the physics at the Large Hadron Collider (LHC) can be described in the framework of the Standard Model (SM) of particle physics. Indeed the newly discovered Higgs boson with a mass close to 125 GeV seems to confirm the predictions of the SM. Thus, besides looking for direct manifestations of the physics beyond the SM, one of the primary missions of the LHC is to perform ever more stringent tests of the SM. This requires not only improved theoretical developments to produce testable predictions and provide experiments with reliable event generators, but also sophisticated analyses techniques to overcome the formidable experimental environment of the LHC and perform precision measurements. The present article proposes an overview of the present theoretical tools and of the experimental results in the field of strong and electroweak interactions.     

Effect of adaptive psychophysical procedure on loudness matches

Large variability in equal-loudness matches has been observed across studies. The purpose of the present study was to gain insight into the extent to which this variability results from differences in psychophysical procedures and/or differences among listeners. Four adaptive two-interval, two-alternatives-forced-choice procedures were used to obtain equal-loudness matches between 5- and 200-ms 1-kHz tones as a function of level for each of six normal listeners. The procedures differed primarily in the sequence in which the stimuli were presented. The variations tested were the ordering of stimuli by amplitude across blocks of trials (both increasing and decreasing amplitudes), randomizing the order across those blocks, and randomizing the order within blocks. The random-within-block procedure, which sought to randomize any intertrial information, yielded a significantly greater amount of temporal integration than the other three procedures. The results show significant differences in temporal integration measurements at moderate levels for the same listeners across different procedures. Therefore, although there are individual differences among listeners in the amount of temporal integration measured across paradigms, the choice of paradigm also affects the amount of temporal integration measured at moderate levels.     

A simple reduction procedure for the three- and N-body scattering equations

A generalized form of the two-body Kowalski-Noyes method is shown to provide a both simple and powerful unitary reduction of the three- and N-body scattering equations. Employing generalized half-off-shell functions that satisfy of-sshell but real and non-singular integral equations, the reduction directly leads to on-shell integral equations for the scattering amplitudes. Physically, it is simple example of how the scattering problem can be split into an internal and an external part.     

激光玻璃包边后剩余反射率的测量和计算

对抑制激光玻璃自发辐射放大和寄生振荡效应的方法进行了论述,分别讨论了在硬包边和软包边情况下激光玻璃与包边材料折射率匹配及对剩余反射率的影响。进而提出采用分光光度计测量反射率的方法来计算剩余反射率,分别推导了在硬包边和软包边情况下剩余反射率的计算公式。推导出普适的剩余反射率的计算公式。     

A new procedure for refining force constants in normal coordinate calculations

We outline a new refinement procedure based on a Green function approach. We display the basic equation to be used and discuss some of the advantages of the procedure.     

Semantic and phonetic enhancements for speech-in-noise recognition by native and non-native listeners

Previous research has shown that speech recognition differences between native and proficient non-native listeners emerge under suboptimal conditions. Current evidence has suggested that the key deficit that underlies this disproportionate effect of unfavorable listening conditions for non-native listeners is their less effective use of compensatory information at higher levels of processing to recover from information loss at the phoneme identification level. The present study investigated whether this non-native disadvantage could be overcome if enhancements at various levels of processing were presented in combination. Native and non-native listeners were presented with English sentences in which the final word varied in predictability and which were produced in either plain or clear speech. Results showed that, relative to the low-predictability-plain-speech baseline condition, non-native listener final word recognition improved only when both semantic and acoustic enhancements were available (high-predictability-clear-speech). In contrast, the native listeners benefited from each source of enhancement separately and in combination. These results suggests that native and non-native listeners apply similar strategies for speech-in-noise perception: The crucial difference is in the signal clarity required for contextual information to be effective, rather than in an inability of non-native listeners to take advantage of this contextual information per se.     

A simple semi-empirical procedure for determining the parameters in the MO LCAO method

A simple method is described for evaluating the exchange and Coulomb integrals with account for the change in the properties of the atoms on entry into a molecule. Generalizations of Slater's rule permit the calculation of the ionization potentials of atoms in a molecule which make the main contribution to the Coulomb integrals. Analytical expressions are given for the Coulomb integrals in the -function approximation.I am indebted to N. A. Prilezhaeva and V. I. Danilova for their continuous interest in the work.     

An analytical procedure to evaluate electronic integrals for molecular quantum mechanical calculations

The main contribution of this paper is to provide an alternative strategy to reduce the number of bi-electronic integrals in ab initio quantum mechanics calculations. An analytical procedure to evaluate the energy of a molecule as well as two-electron integrals is proposed. This approach is based on the generalized exponential function (q-exponential) and is particularly advantageous because it reduces substantially the CPU time in quantum mechanical calculations. Some examples of the effectiveness of this methodology are presented. It is important to point out that the new methodology is applicable to any kind of molecular system including relatively large molecular systems in the context of the Hartree–Fock (HF) and density functional theories (DFT).     

Measurements and calculations of CO-H2O line-widths at high temperature

Diode-laser measurements of H₂O broadening of the CO P4 line in the 400–900 K range are presented. First comparisons between experimental CO-H₂O line-widths and the results of a recent theoretical model are also presented.     

A single-interval adjustment-matrix (SIAM) procedure for unbiased adaptive testing

A new unbiased adaptive procedure is described that requires only half as many presentations in achieving the same precision as the well-known two-interval forced-choice (2IFC) 2-step procedure. The procedure is based on a yes-no task which avoids redundant presentation time. Furthermore, certain psychophysical studies can only be realized with yes-no tasks. Every trial contains randomly presented signals or noises and the answer is either yes or no. The outcome (hit, miss, false alarm, correct rejection) is taken into account by adjusting the signal level in a staircase manner. The adjustment matrix is set up to induce a neutral response criterion. Its convergence point can be adjusted at will. The single-interval adjustment-matrix (SIAM) procedure is compared to von Békésy and 2IFC transformed up-down methods using a Monte-Carlo simulation. The SIAM procedure proves to be the fastest of the unbiased procedures. A test on four subjects verified these results. Implications for optimum track length and the number of reversals to discard are discussed.     

Efficient adaptive procedures for threshold and concurrent slope estimates for psychophysics and speech intelligibility tests

The minimum standard deviations achievable for concurrent estimates of thresholds and psychometric function slopes as well as the optimal target values for adaptive procedures are calculated as functions of stimulus level and track length on the basis of the binomial theory. The optimum pair of targets for a concurrent estimate is found at the correct response probabilities p1 = 0.19 and p2 = 0.81 for the logistic psychometric function. An adaptive procedure that converges at these optimal targets is introduced and tested with Monte Carlo simulations. The efficiency increases rapidly when each subject's response consists of more than one statistically independent Bernoulli trial. Sentence intelligibility tests provide more than one Bernoulli trial per sentence when each word is scored separately. The number of within-sentence trials can be quantified by the j factor [Boothroyd and Nittrouer, J. Acoust. Soc. Am. 84, 101-114 (1988)]. The adaptive procedure was evaluated with 10 normal-hearing and 11 hearing-impaired listeners using two German sentence tests that differ in j factors. The expected advantage of the sentence test with the higher j factor was not observed, possibly due to training effects. Hence, the number of sentences required for a reliable speech reception threshold (approximately 1 dB standard deviation) concurrently with a slope estimate (approximately 20%-30% relative standard deviation) is at least N = 30 if word scoring for short, meaningful sentences (j approximately 2) is performed.