The effect of the helicotrema on low-frequency loudness perception

Below approximately 40 Hz, the cochlear travelling wave reaches the apex, and differential pressure is shunted through the helicotrema, reducing hearing sensitivity. Just above this corner frequency, a resonance feature is often observed in objectively measured middle-ear-transfer functions (METFs). This study inquires whether overall and fine structure characteristics of the METF are also perceptually evident. Equal-loudness-level contours (ELCs) were measured between 20 and 160 Hz for 14 subjects in a purpose-built test chamber. In addition, the inverse shapes of their METFs were obtained by adjusting the intensity of a low-frequency suppressor tone to maintain an equal suppression depth of otoacoustic emissions for various suppressor tone frequencies (20–250 Hz). For 11 subjects, the METFs showed a resonance. Six of them had coinciding features in both ears, and also in their ELC. For two subjects only the right-ear METF was obtainable, and in one case it was consistent with the ELC. One other subject showed a consistent lack of the feature in their ELC and in both METFs. Although three subjects displayed clear inconsistencies between both measures, the similarity between inverse METF and ELC for most subjects shows that the helicotrema has a marked impact on low-frequency sound perception

Tomografía sísmica vertical inversa 2.5D alrededor del sondeo científico Almera-1, ICTJA-CSIC, Barcelona

En 2011 junto al Instituto de Ciencias de la Tierra Jaume Almera-CSIC, en Barcelona, se perforó un sondeo científico con el objeto de disponer de una infraestructura destinada a la investigación con sondas de testificación geofísica, monitorización de sondeos, la formación especializada y también para la exploración del subsuelo urbano. La extracción de testigo continuo y un completo estudio mediante sondas de testificación geofísica del ICTJA-CSIC, permitieron caracterizar la sección geológica, estructuras atravesadas y características hidrogeológicas en el sondeo Almera-1. Se presentan aquí los resultados obtenidos en una exploración sísmica de la estructura en el entorno del sondeo y el reconocimiento de la estructura en la que está emplazado el mismo. En este contexto se planteó una tomografía sísmica vertical inversa pseudo-3D (o 2.5D), cuyo dispositivo experimental, metodología y resultados son objeto de este trabajo. Se define la estructura en el entorno del sondeo y se establece una correlación entre las respuestas geofísicas y los distintos tramos de materiales reconocidos en el subsuelo.Peer Reviewe

Employee empowerment and HR flexibility in Information Technology SMEs

CAUL read and publish agreement 2023HR systems in IT organizations need to be flexible to enable them to adjust to the fast rate of technological change. Employee empowerment, often practiced at IT organizations under the banner of agile practices, has been highlighted as likely to enable HR flexibility. Based on a research panel based survey of top managers at 163 IT organizations in New Zealand and Australia, we confirmed positive effects of employee empowerment on four dimensions of HR flexibility: resource flexibility in employee skills and behaviors, coordination flexibility in employee skills and behaviors, resource flexibility in HR practices, and coordination flexibility in HR practices. The results are consistent with the view that, at IT organizations, employee empowerment both promotes employee ability and willingness to be flexible and facilitates the organizational structures and practices that enable flexible use of HR resources.fals

Calculation of climatic reference values and its use for automatic outlier detection in meteorological datasets

The climatic reference values for monthly and annual average air temperature and total precipitation in Catalonia – northeast of Spain – are calculated using a combination of statistical methods and geostatistical techniques of interpolation. In order to estimate the uncertainty of the method, the initial dataset is split into two parts that are, respectively, used for estimation and validation. The resulting maps are then used in the automatic outlier detection in meteorological datasets

Transient effects in fission evidenced from new experimental signatures

A new experimental approach is introduced to investigate the relaxation of the nuclear deformation degrees of freedom. Highly excited fissioning systems with compact shapes and low angular momenta are produced in peripheral relativistic heavy-ion collisions. Both fission fragments are identified in atomic number. Fission cross sections and fission-fragment element distributions are determined as a function of the fissioning element. From the comparison of these new observables with a nuclear-reaction code a value for the transient time is deduced.Comment: 6 pages, 2 figures, background information at http://www-w2k.gsi.de/kschmidt

Zymological indicators: a new concept applied to the detection of potential spoilage yeast species associated with fruit pulps and concentrates

DOI:10.1006/fmic.2000.0360; available online at http://www.idealibrary.comIn a survey of the microbial quality of raw materials used in fruit juice processing, yeast counts in fruit concentrates and pulps were found to range from51to 2?96103 cfu g71. Ascomycetous yeasts were representedby 76%of the isolateswhile 24%were basidiomycetes.The identi¢cation of strains isolated by the simpli¢ed identi¢cation system(SIM) revealed19 yeast species representing12 genera.Themost frequently isolated yeasts belonged to the genera Saccharomyces, Pichia, Cryptococcus, Kluyvero- myces and Candida. Fatty acid yeast composition allowed the separation of contaminating yeasts into one of threemajor groups. Group I included yeasts without linoleic (C 18:2) and linolenic (C 18:3) fatty acids such as Saccharomyces cerevisiae. Group II comprised yeasts without C 18:3 fatty acid like Zygosaccharo- myces rouxii and Torulaspora delbrueckii, and group III included yeasts with C18:2 and C18:3 acids that belong, among others, to one of the following yeast genera: Pichia, Candida, Kluyveromyces or Cryptococcus. Species-speci¢c PCR primers were used for the rapid detection and identi¢cation of the most dangerous species a¡ecting fruit concentrate stability. The simpli¢ed protocol used consisted of PCR-ampli¢cation of conserved tracts in the ITS region of the rDNA unit, thus enabling the detection ofpotentially dangerous £ora such as Zygosaccharomyces species andT. delbrueckii in contaminated fruit concentrates. Results from PCR-typing were in full agreement with the fatty acid compositions of these species. The grouping of contaminant yeasts into threemain groups showed that fatty acid compositionmay be used to di¡erentiate yeasts according to their technological signi¢cance.Yeasts isolated in thiswork as being most dangerous to product stability belong to either group II ( Z. rouxii and T. delbrueckii) or group I (Saccharomyces spp.). Group III was comprised of several species regarded as indicators of de¢ciencies in `good manufacturing practices'.Thus, each of the groups delineated may be considered to be a zymological indicator of technological signi¢cance.The conjugation of fatty acid pro¢les with PCR-typing methods may be used as a rapid detection system for contaminant yeasts. The fatty acid pro¢les provide a preliminary identi¢cation of yeasts potentially dangerous to product stability present within 48 h. of isolation. Whereas the PCR-typing method is mainly used to confirm isolate identity, when required, after the initial diagnosis has been performed, over a period of 4 h

Critical Repetition Rates for Perceptual Segregation of Time-Varying Auditory, Visual and Vibrotactile Stimulation

What sound quality has led to exclude infrasound from sound in the conventional hearing range? We examined whether temporal segregation of pressure pulses is a distinctive property and evaluated this perceptual limit via an adaptive psychophysical procedure for pure tones and carriers of different envelopes. Further, to examine across-domain similarity and individual covariation of this limit, here called the critical segregation rate (CSR), it was also measured for various periodic visual and vibrotactile stimuli. Results showed that sequential auditory or vibrotactile stimuli separated by at least ~80‒90 ms (~11‒12-Hz repetition rates), will be perceived as perceptually segregated from one another. While this limit did not statistically differ between these two modalities, it was significantly lower than the ~150 ms necessary to perceptually segregate successive visual stimuli. For the three sensory modalities, stimulus periodicity was the main factor determining the CSR, which apparently reflects neural recovery times of the different sensory systems. Among all experimental conditions, significant within- and across-modality individual CSR correlations were observed, despite the visual CSR (mean: 6.8 Hz) being significantly lower than that of both other modalities. The auditory CSR was found to be significantly lower than the frequency above which sinusoids start to elicit a tonal quality (19 Hz; recently published for the same subjects). Returning to our initial question, the latter suggests that the cessation of tonal quality — not the segregation of pressure fluctuations — is the perceptual quality that has led to exclude infrasound (sound with frequencies < 20 Hz) from the conventional hearing range

Practical advantages of inverted decoupling

This paper presents a study of the main advantages of inverted decoupling in 2x2 processes. Two simulation examples and an experimental process are used to show these advantages in comparison with simplified decoupling. The study is focused on the following practical advantages: the apparent process is the same as that obtained if one loop changes to manual, bumpless transfer and anti-windup are achieved easily using a feedforward input in the controllers, and abnormalities of secondary loops do not affect the opposite loop. Thanks to them, inverted decoupling may be a good and easy way to improve the performance of industrial TITO processes with interaction problems (when it can be applied)

Amplitude Modulation May Be Confused with Infrasound

Environmental infrasound is usually accompanied by low-frequency (LF) sounds. Considering that inner hair cell transduction equals half-wave rectification, activity of low-frequency auditory nerve fibres may be indistinguishable whether elicited by LF sound that is amplitude-modulated at an infrasonic rate, or LF sound that is superimposed onto infrasound that "biases" the basilar membrane position. We tested whether listeners are able to distinguish a 63-Hz carrier tone, amplitude modulated at 8 Hz, from a 63-Hz pure tone that was perceptually loudness-modulated by an 8-Hz biasing tone. Using a maximum-likelihood procedure, 12 participants first adjusted the intensity of the 8-Hz tone so that the perceived modulation of the pure tone matched a reference amplitude-modulated tone. Both stimuli types were then presented in random order, and participants had to identify presentations which contained the infrasound tone. About half the participants performed close to chance. The best had 81% correct. Experiments with a 125-Hz carrier tone gave similar results. Although performance may improve in a 2-interval discrimination task, this would not be representative of real listening conditions. Results suggest that slowly amplitude-modulated LF sounds may underlie complaints about environmental infrasound, where measured infrasound levels are well below sensation threshold