A Method of Measuring Acoustic Wave Attenuation in the Laboratory

The measurement of attenuation is performed by directly determining the attenuation operator (or the impulse response of the medium) in the time domain. In this way, it is possible to separate the attenuation operator from other non-attenuation effects, e.g. reflections. The Wiener filtering technique, or the damped least-squares, is used to calculate the attenuation operator. For the damped least squares, we have corrected for the effect due to the addition of the damping constant using a perturbation method. Numerical tests are carried out to illustrate the technique. The geometric beam spreading of ultrasonic waves generated by a source of finite size can strongly affect the result of attenuation measurements. Corrections are made by equating the received signal to the average pressure over the receiver surface. The technique is used to measure ultrasonic attenuation in water, glycerol and mud. The measurement in water offers a test of the corrections made for the geometric beam spreading. The measurement in glycerol and mud shows that, in the frequency range of 0.2-1.5 MHz, the attenuation of glycerol increases rapidly with frequency, whereas the attenuation of mud is proportional to frequency, exhibiting a constant Q behavior. The measurements show that the technique used here is an effective approach to the measurement of attenuation.Massachusetts Institute of Technology. Full Waveform Acoustic Logging Consortiu

Laboratory Studies Of The Acoustic Properties Of Samples From The Salton Sea Scientific Drilling Project And Their Relation To Microstructure And Field Measurements

Compressional and shear wave velocities were measured at confining pressures up to 200 MPa for twelve core samples from the depth interval of 600 to 2600 m in the California State 2-14 borehole. Samples were selected to represent the various lithologies, including clean, heavily cemented sandstones, altered, impermeable claystones, and several intermediate siltstones. Velocities measured at ultrasonic frequencies in the laboratory correspond closely with velocities determined from acoustic waveform logs and vertical seismic profiles. The samples exhibit P-wave velocities around 3.5 km/sec at depths above 1250 m, but increase to nearly 5.0 km/sec at 1300 m in depth. Further increases with depth result in compressional wave velocity increasing to nearly 6.0 km/sec. These increases in velocities are related to systematic variations in lithology, microstructure and hydrothermal alteration of originally clay-rich sediments. Scanning electron microscope observations of core samples confirm that local core velocities are determined by the combined effects of pore size distributions, and the proportion of clays and alteration minerals such as epidote present in the form of pore fillings and veins.United States. Dept. of the Interior. Geological Survey (Grant 14-08-001A-0328)Elf-Aquitaine (Postdoctoral Fellowship

The effect of repeated shocks on individual competitiveness : an experiment

Individual competitiveness has gained growing interest in the behavioral and experimental economics literature due to its ability to predict labor market outcomes and educational choices. People who are more competitive tend to choose challenging fields for higher education, are more likely to earn more after graduation, and are often more successful in career than the less competitive. It is also argued that the gender difference in the preference to compete is a major reason behind the underrepresentation of women in the labor market. While the vast majority of literature has focused on studying the heterogeneity across individuals, it is important to study how negative shocks can potentially disrupt one’s willingness to compete. Shocks can directly or indirectly affect an individual’s productivity. Therefore, they may also alter their decision to choose competitive environments. This thesis aims to study, using an incentivized online labor market experiment, the effect of repeated shocks on individual competitiveness. Participants perform a real-effort task for multiple rounds under repeated shocks and face a decision to enter a tournament. Furthermore, it explores how resilience in performance may be linked with greater competitiveness along with gender differences. The results of the experiment suggest that repeated shocks can negatively affect competitiveness, and that performance resilience alone may not be sufficient to tackle this effect. Additionally, they indicate that both males and females are equally likely to be affected by shocks. While there is a slight gender difference in competitiveness, it may be due to the significant gap in confidence between the two genders. Even though the experiment follows a simple design framework, and the magnitude of the shock are small, it has several economic implications. First, demand transitions in the labor market can substantially reduce competitive choices, mainly due to the uncertainty of payoffs. Second, belief about oneself can play a larger role in explaining someone’s competitiveness than their task performance. Third, the existing gender gap in the labor market may be reduced by raising the overall confidence of women and with the help of advice

Judgements about actions and feelings in stories' interpretations: a Piagetian approach

Este artigo apresenta dados selecionados a partir de pesquisa com 76 crianças de cinco a dez anos sobre interpretações de dois contos de fadas dos Irmãos Grimm: O lobo e os sete cabritinhos e Senhor lobo e senhora gata. O objetivo é discutir os julgamentos das crianças sobre ações e sentimentos de personagens dos contos, baseados nos conceitos de valores, julgamentos e apreciações emocionais, de Piaget. A hipótese geral foi a de que os julgamentos e a capacidade de avaliar sentimentos evoluem com a idade. O método utilizado foi a entrevista clínica piagetiana adaptada aos dois contos. Os resultados indicaram diferenças entre as crianças mais velhas e as mais jovens da amostra, mas as análises estatísticas não apontaram diferenças significativas para comparações entre crianças de faixas etárias mais próximas. Esta pesquisa contribuiu para a discussão sobre o uso de contos de fadas em estudos sobre valorizações afetivas e julgamentos em crianças.This paper presents some data of 76 children's representation of two Brothers Grimm's fairy tales: The wolf and the seven young kids and Mr. Wolf and Mrs. Cat. Children were aged from 5 to 10/11 years old. The article aims to discuss children's judgements about characters'feelings and actions, based on Piaget's concepts of values, judgments and emotional appreciation. The general hypothesis was that quality of judgement and the capacity for feelings evaluation increase with age. The method was the clinical interview adapted to the two fairy tales. Results indicated differences between the oldest and the youngest children of the sample, but statistical analisis didn't show significant differences between children near in age. This research contributed to discuss the possibility for using fairy tales in studies about children emotional appreciation and moral judgements

Fabrication of Tm2O3/Al2O3-silica preform by improved MCVD-chelate delivery system

The fabrication of Tm/Al-doped silica preforms by an improved MCVD method with metal chelate precursors is discussed. Two fabrication techniques are employed, namely; simultaneous soot-dopant deposition (or standard MCVD) and stepwise soot-dopant deposition. The preforms are characterized by refractive index profiler and EPMA. The results show that the stepwise soot-dopant technique has a higher incorporation of Al2O3 and Tm2O3 as compared to the simultaneous soot-dopant method. This is due to the drawbacks of our chelate delivery system such as the temperature gradient and flow design. For the stepwise technique, the measured index difference of the preform is 0.006 with 0.8 wt% (maximum) Tm incorporated in the core

A review of Energy Efficient Routing Protocols in Underwater Internet of Things

Oceans, covering 70% of Earth's surface, arelargely unexplored, with about 95% remaining a mystery.Underwater wireless communication is pivotal in various domains,such as real-time aquatic data collection, marine surveillance,disaster prevention, archaeological exploration, andenvironmental monitoring. The Internet of Things has openednew avenues in underwater exploration through the underwaterInternet of Things concept. This innovative technology facilitatessmart ocean research, from small case studies to large-scaleoperations. UIoT networks utilise underwater equipment andsensors to gather and transmit data in aquatic environments.However, the dynamic nature of these environments poseschallenges to the network's structure and communication,necessitating efficient routing solutions. Quality-of-service-awarerouting is vital as it minimises energy usage, extends battery life,and enhances network performance. This paper delves into thechallenges and limitations of UIoT networks, highlighting recentrouting methodologies. It also proposes a comparison frameworkfor routing methods, focusing on the quality of service inunderwater IoT networks, to foster more optimal route selectionand better resource management.Comment: 6 pages, 1 figure, conferenc

Is It Ethical for Patients with Renal Disease to Purchase Kidneys from the World's Poor?

Background to the debate: In many countries, the number of patients waiting for a kidney transplant is increasing. But there is a widespread and serious shortage of kidneys for transplantation, a shortage that can lead to suffering and death. One approach to tackling the shortage is for a patient with renal disease to buy a kidney from a living donor, who is often in a developing country, a sale that could—in theory at least—help to lift the donor out of poverty. Such kidney sales are almost universally illegal. Proponents of kidney sales argue that since the practice is widespread, it would be safer to formally regulate it, and that society should respect people's autonomous control over their bodies. Critics express concern about the potential for exploitation and coercion of the poor, and about the psychological and physical after-effects on the donors of this illegal kidney trade

« Perdre ; ou ne pas perdre ; le rythme de la ponctuation dickensienne : là——est la question ! »

La notion de rythme est appréciée dans cet article à l’aune de la ponctuation dickensienne. Cette information rythmique que constitue le système ponctuationnel joue un rôle de premier plan dans les textes dickensiens, des textes hautement théâtraux. C’est plus particulièrement l’œuvre d’Oliver Twist qui fait ici l’objet de notre attention, un texte dont Dickens a révisé avec grand soin, plus que tout autre élément encore, le système de ponctuation, affirmant alors la primauté de ce système dans cette œuvre. De là, en s’appuyant sur l’analyse de quatre traductions d’Oliver Twist, il s’agit d’évaluer dans quelle mesure le traducteur reproduit ou peut reproduire le système mis en place par Dickens, sachant qu’il repose sur des variables telles que l’évolution des pratiques de lecture ou encore sur la fonction orale ou syntaxique de la ponctuation. Ainsi, cette analyse pose plus largement la question de la traduisibilité du système de ponctuation à valeur orale et du rythme qui en découle.The notion of rhythm is apprehended in this article through the lens of Dickensian punctuation. The rhythmic information that the punctuation system conveys is given pride of place in Dickensian texts, which are highly theatrical texts. This article focuses more specifically on Oliver Twist as Dickens thoroughly revised more than anything else its punctuation system, thus testifying to its primacy in this work. This paper concentrates on four translations of Oliver Twist and gauges to what extent the punctuation system used by Dickens is reproduced and / or reproducible by the translator, knowing that it relies on different parameters, such as the evolution of reading practices or on the oral or syntactic value of punctuation. Overall this study raises the question of the translatability of the punctuation system and of the rhythm that it conveys