External inversion,internal inversion,and reflection invariance

Having in mind that physical systems have different levels of structure we develop the concept of external, internal and total improper Lorentz transformation (space inversion and time reversal). A particle obtained from the ordinary one by the application of internal space inversion or time reversal is generally a different particle. From this point of view the intrinsic parity of a nuclear particle (elementary particle) is in fact the external intrinsic parity, if we take into account the internal structure of a particle. We show that non-conservation of the external parity does not necessarily imply noninvariance of nature under space inversion. The conventional theory of beta-decay can be corrected by including the internal degrees of freedom to become invariant under total space inversion, though not under the external one.     

External and internal noise surveys of London primary schools

Internal and external noise surveys have been carried out around schools in London, UK, to provide information on typical levels and sources to which children are exposed while at school. Noise levels were measured outside 142 schools, in areas away from flight paths into major airports. Here 86% of the schools surveyed were exposed to noise from road traffic, the average external noise level outside a school being 57 dB L(Aeq). Detailed internal noise surveys have been carried out in 140 classrooms in 16 schools, together with classroom observations. It was found that noise levels inside classrooms depend upon the activities in which the children are engaged, with a difference of 20 dB L(Aeq) between the "quietest" and "noisiest" activities. The average background noise level in classrooms exceeds the level recommended in current standards. The number of children in the classroom was found to affect noise levels. External noise influenced internal noise levels only when children were engaged in the quietest classroom activities. The effects of the age of the school buildings and types of window upon internal noise were examined but results were inconclusive.     

Physical limitations of rate,depth, and minimum energy in information processing

The effect of the quantum nature of matter on the maximum informationprocesssing potentialities is considered. It is shown that the degeneracy of the energy levels of a physical information-processing system results in the fact that a universal limit of information-processing rates does not exist, though for any specific system this rate is indeed bounded. A physical interpretation is then proposed for an elementary act of information-processing and the concept of information-processing depth is introduced. The example of a system of quantum oscillators is used to show that the maximal information-processing depth is bounded, only a very small fraction of the possible system states being used. The effect of thermal noise on information processing is briefly discussed.     

The effect of carrier level on tuning in amplitude-modulation masking

The effect of carrier level on tuning in modulation masking was investigated for noise and tonal carriers. Bandwidths of the modulation filters, estimated from the masked detection thresholds using an envelope power spectrum model, were independent of level for the noise carrier but seemed to decrease with increasing level for the tonal carrier. However, the apparently sharper tuning could be explained by increased modulation sensitivity and modulation dynamic range with increasing level rather than improved modulation-frequency selectivity. Consistent with this interpretation, the addition of a high-pass noise with a level adjusted to maintain the same threshold for the detection of the signal modulation for each carrier level used eliminated the effect of level on tuning. Overall, modulation filters estimated from psychophysical data do not depend on level in contrast to the modulation transfer functions obtained from neural recordings in the inferior colliculus in physiological studies. The results highlight differences between the characteristics of modulation processing obtained from neural data and perception. The discrepancies indicate the need for further investigation into physiological correlates of tuning in modulation processing.     

Possibilities and limitations of ultrasonic diagnosis of space occupying lesions in internal medicine.

Possibilities and limitations of ultrasonic tumour diagnosis in internal medicine (thyroid gland, liver, pancreas, kidney, malignant lymphomas) are discussed on the basis of a five years experience with about 4,000 examinations a year. A real time and gray-scale technique is used. The accuracy of the presented ultrasonic findings is proven by comparative studies. Besides the well known advantages of ultrasonography the independence from contrast medias must be stressed in comparison to diagnostic radiology. The main limitations of ultrasonography are the impossibility of diagnosing tumours smaller than 1.5-2 cm and the absence of an ultrasonic pattern typical of malignancy. To establish a morphobiological diagnosis, ultrasonically guided fine needle biopsy has proved to be a reliable method.     

External and internal features of garnet revealed by the multifocus imaging technique

This publication illustrates the imaging of both external and internal features of a single-garnet crystal using the multifocus imaging technique. Based on image stacks acquired using a standard optical microscope, it demonstrates that this easily implemented technique yields information on single grains and may in some cases provide more information than that obtainable from a conventional thin section.     

External and internal coupling effects of rotor's bending and torsional vibrations under unbalances

External and internal bending–torsion coupling effects of a rotor system with comprehensive unbalances are studied by analytical analysis and numerical simulations. Based on Lagrangian approach, a full-degree-of-freedom dynamic model of a Jeffcott rotor is developed. The harmonic balance method and the Floquet theory are combined to analyze the stability of the system equations. Numerical simulations are conducted to observe the bending–torsion coupling effects. In the formulation of rotordynamic model, two bending–torsion coupling patterns, external coupling and internal coupling, are suggested. By analytical analysis, it is concluded that the periodic solution of the system is asymptotically stable. From numerical simulations, three bending–torsion coupling effects are observed in three cases. Under static unbalance, synchronous torsional response is observed, which is the result of external coupling under unbalanced force. Under dynamic unbalance, two-time synchronous frequency torsional response is observed, which is the result of internal coupling under unbalanced moment. Under comprehensive unbalance, synchronous and two-time synchronous frequency torsional components are observed, which are the results of both external and internal couplings under unbalanced force and moment. These observations agree with the analytical analysis. It is believed that these observed phenomena should make sense in the dynamical design and fault diagnostics of a rotor system.     

Perceptual learning and generalization resulting from training on an auditory amplitude-modulation detection task

Fluctuations in sound amplitude provide important cues to the identity of many sounds including speech. Of interest here was whether the ability to detect these fluctuations can be improved with practice, and if so whether this learning generalizes to untrained cases. To address these issues, normal-hearing adults (n = 9) were trained to detect sinusoidal amplitude modulation (SAM; 80-Hz rate, 3-4 kHz bandpass carrier) 720 trials/day for 6-7 days and were tested before and after training on related SAM-detection and SAM-rate-discrimination conditions. Controls (n = 9) only participated in the pre- and post-tests. The trained listeners improved more than the controls on the trained condition between the pre- and post-tests, but different subgroups of trained listeners required different amounts of practice to reach asymptotic performance, ranging from 1 (n = 6) to 4-6 (n = 3) sessions. This training-induced learning did not generalize to detection with two untrained carrier spectra (5 kHz low-pass and 0.5-1.5 kHz bandpass) or to rate discrimination with the trained rate and carrier spectrum, but there was some indication that it generalized to detection with two untrained rates (30 and 150 Hz). Thus, practice improved the ability to detect amplitude modulation, but the generalization of this learning to untrained cases was somewhat limited.     

External and internal problems of modeling the heat and mass transfer coefficients at particles motion in liquids

An approach to the determination of the heat and mass transfer coefficients from dispersed particles by the development of the hydrodynamic analogy is considered. The equations for computing the heat and mass transfer coefficients in continuous phase at a laminar regime of the flow around solid particles as well as the mass transfer coefficients in droplets are obtained. Comparisons with the experimental data of different authors are presented.     

Decay of amplitude-modulation property of song and an analysis of sounding mechanism in mottled cicade (Gaeana maculata Drury)

I-IntroductionTheamp1itudc-modulationpropcrtyexistsgcnerallyinthesongsofarthropods.Insingingorthoptcraninsccts,suchasmo1c-cricket,1ocust,cricketandkatydid,thesongsproduccdbystridulationsarctypica1andcachwave(thetoothstrike)incarrierwavesisisproducedbythatthescrapcrstrikesateachtoothofthedenticulatedvein(fi1e)t'J.IncicadasoftheHomoptera,thesongsareproduccdbycontractionmovcmentsofthesoundingmusc1etodrivethesoundingmembranewithribstructurestovibrations,andaregeneral1yamplitude-modu1ationpu1sesou…     

浅海中内波对匹配场时间相关的影响

利用一次夏季浅海水文实验资料,数值仿真研究有线性内波和孤立子内波存在条件下的匹配场时间相关性.考察和总结了有内波存在时不同声源频率、声源深度和内波幅度等参数对匹配场时间相关的影响.研究结果表明:由于内波与声场的相互作用,匹配场时间相关长度会随着线性内波的平均能流密度及孤立子内波幅度的增大而减小;频率越高,声波穿过内波场时的匹配场时间相关下降的越快;声源位于跃层下时的匹配场时间相关明显的优于跃层上的情况;孤立子内波距声源的位置对匹配场时间相关影响相对较小.     

The effects of the internal waves on temporal correlation of matched-field processing in shallow water

Effects of linear and solitary internal waves on the temporal correlation of matched-field processing(MFP) in shallow water are numerically investigated for acoustic sources with different frequencies and depths based on oceanographic data from an experiment.It is shown that the temporal correlation of MFP decreases as the amplitude of solitary internal waves or the average energy density of linear internal waves increases.For acoustic source with lower frequency or located below the thermocline,the temp...     

Binaural processing of noisy stimuli: internal/external noise ratios for diotic and dichotic stimuli

A set of ten digitized statistically similar Gaussian maskers was used in one-internal tone-in-noise detection experiments under diotic (NoSo) and dichotic (NoS pi) interaural conditions. Stimulus/response matrices were generated for each masker in the presence or absence of a target 500-Hz tone. For both NoSo and NoS pi, nonparametric analyses show that response probabilities and sensitivities vary significantly across noise waveforms, indicating a considerable external noise component in subject response variability. A parametric model is developed that maps individual stimulus waveforms onto a decision axis, facilitating evaluation of internal/external noise variance ratios. For both NoSo and NoS pi, internal and external noise variance are of similar magnitude.     

Bandwidth limitations in pulse code modulation

The calculations of Huang and Reiss for the power spectrum of a pulse code modulation message is here extended, corrected, and generalized to include a formalism for an arbitrary Markovian process. The formalism contains arbitrary pulse shape and transmission times. For a first-order Markovian message the importance of the quasidiscrete frequencies is emphasized and it is concluded that these frequencies are more significant in defining the necessary bandwidth for transmission than any “optimized” choice of transmission times.     

Overcoming limitations in semiconductor alloy design

The phenomenon of giant band gap ‘bowing’ recently observed in several III–V dilute nitride alloys is promising for increasing the flexibility in choice of semiconductor band gaps available for specified lattice constants. However, the poor electrical transport properties that these materials exhibit seriously limit their usefulness. It is proposed that these materials behave as heavily nitrogen-doped semiconductors rather than dilute nitride alloys and that the abnormal or irregular alloy behavior is associated with impurity band formation that manifests itself in the giant bowing and poor transport properties. The potential for regularizing the alloy behavior using isoelectronic co-doping is discussed.     

Classical and quantum limitations on energy consumption in computation

Fundamental limitations on the energy dissipated during one elementary logical operation are discussed. A model of a real physical device (parametric quantron) based on the Josephson effect in superconductors is used throughout the discussion. This device is shown to be physically reversible, and moreover it can serve as the clementary cell of a logically reversible computer, both these properties being necessary to achieve the fundamental limits of energy dissipation. These limits due to classical and quantum statistics are shown to lie well below the earlier estimates,k _B T and , respectively.     

Potential and limitations of rare-earth luminescence in inverse opals

Inverse opals exhibiting strong photonic effects can cooperate with luminescent materials imbedded in their voids. While this has been demonstrated for dye molecules in the past, inspection of the literature reveals only few experiments on the potential of rare earths in this context. The efforts described focus on the spectral and spatial modification of emissive properties, whereas we here pursue the study of corresponding absorption properties. However, arbitrary incorporation of the luminescent species disturbs the photonic effects, therefore, principal preparative efforts need to be conducted to preserve both, the photonic properties of the opaline hosts and the luminescence efficiency of the guests. In this paper, we describe issues regarding the morphology and efficiency of inverse opal-incorporated rare-earth fluorides and oxifluorides and present an interior coating method for efficiency improvement. In addition, we were in this context, able to demonstrate the feasibility of energy transfer from Tb³⁺ modified host walls to Eu³⁺ guest species.     

南海线性内波条件下的匹配场时间相关长度

对于相位敏感的算法,声场时间相关长度是一个重要的参数。它能确定与相位有关的水声通讯算法的比特率和误码率,以及其他对相位敏感的信号处理算法如匹配场处理的信号增益。为了考察南海线性内波对匹配场时间相关长度的影响,本文分析了2001年亚洲海国际声学实验(ASIAEX2001)南中国海实验的水文数据,得到了符合该海域的内波频谱表示,并通过数值仿真研究了该海域存在线性内波时匹配场时间相关长度与声源频率f、收发距离R以及声速起伏δC的关系,总结了南海线性内波环境中匹配场时间相关长度的经验表示。仿真中所用的声源频率f为150~1200 Hz,收发距离R为20~32 km,声速起伏δC为1.37~5.0 m/s。结果表明,在该实验水文条件下,匹配场时间相关长度与δC^-1.3和f^-1.1成正比;在海底水平不变和水平变化时分别与R^0.7和R^-0.5成正比。