Echo-delay resolution in sonar images of the big brown bat, Eptesicus fuscus

Echolocating big brown bats (Eptesicus fuscus) broadcast ultrasonic frequency-modulated (FM) biosonar sounds (20–100 kHz frequencies; 10–50 μs periods) and perceive target range from echo delay. Knowing the acuity for delay resolution is essential to understand how bats process echoes because they perceive target shape and texture from the delay separation of multiple reflections. Bats can separately perceive the delays of two concurrent electronically generated echoes arriving as little as 2 μs apart, thus resolving reflecting points as close together as 0.3 mm in range (two-point threshold). This two-point resolution is roughly five times smaller than the shortest periods in the bat’s sounds. Because the bat’s broadcasts are 2,000–4,500 μs long, the echoes themselves overlap and interfere with each other, to merge together into a single sound whose spectrum is shaped by their mutual interference depending on the size of the time separation. To separately perceive the delays of overlapping echoes, the bat has to recover information about their very small delay separation that was transferred into the spectrum when the two echoes interfered with each other, thus explicitly reconstructing the range profile of targets from the echo spectrum. However, the bat’s 2-μs resolution limit is so short that the available spectral cues are extremely limited. Resolution of delay seems overly sharp just for interception of flying insects, which suggests that the bat’s biosonar images are of higher quality to suit a wider variety of orientation tasks, and that biosonar echo processing is correspondingly more sophisticated than has been suspected.

A risk assessment for exposure to grunerite asbestos (amosite) in an iron ore mine

The potential for health risks to humans exposed to the asbestos minerals continues to be a public health concern. Although the production and use of the commercial amphibole asbestos minerals—grunerite (amosite) and riebeckite (crocidolite)—have been almost completely eliminated from world commerce, special opportunities for potentially significant exposures remain. Commercially viable deposits of grunerite asbestos are very rare, but it can occur as a gangue mineral in a limited part of a mine otherwise thought asbestos-free. This report describes such a situation, in which a very localized seam of grunerite asbestos was identified in an iron ore mine. The geological occurrence of the seam in the ore body is described, as well as the mineralogical character of the grunerite asbestos. The most relevant epidemiological studies of workers exposed to grunerite asbestos are used to gauge the hazards associated with the inhalation of this fibrous mineral. Both analytical transmission electron microscopy and phase-contrast optical microscopy were used to quantify the fibers present in the air during mining in the area with outcroppings of grunerite asbestos. Analytical transmission electron microscopy and continuous-scan x-ray diffraction were used to determine the type of asbestos fiber present. Knowing the level of the miner’s exposures, we carried out a risk assessment by using a model developed for the Environmental Protection Agency.

Validation of the Item-Attribute Matrix in TIMSS-Mathematics Using Multiple Regression and the LSDM

The purposes of this study were (1) to validate of the item-attribute matrix using two levels of attributes (Level 1 attributes and Level 2 sub-attributes), and (2) through retrofitting the diagnostic models to the mathematics test of the Trends in International Mathematics and Science Study (TIMSS), to evaluate the construct validity of TIMSS mathematics assessment by comparing the results of two assessment booklets. Item data were extracted from Booklets 2 and 3 for the 8th grade in TIMSS 2007, which included a total of 49 mathematics items and every student's response to every item. The study developed three categories of attributes at two levels: content, cognitive process (TIMSS or new), and comprehensive cognitive process (or IT) based on the TIMSS assessment framework, cognitive procedures, and item type. At level one, there were 4 content attributes (number, algebra, geometry, and data and chance), 3 TIMSS process attributes (knowing, applying, and reasoning), and 4 new process attributes (identifying, computing, judging, and reasoning). At level two, the level 1 attributes were further divided into 32 sub-attributes. There was only one level of IT attributes (multiple steps/responses, complexity, and constructed-response). Twelve Q-matrices (4 originally specified, 4 random, and 4 revised) were investigated with eleven Q-matrix models (QM1 ~ QM11) using multiple regression and the least squares distance method (LSDM). Comprehensive analyses indicated that the proposed Q-matrices explained most of the variance in item difficulty (i.e., 64% to 81%). The cognitive process attributes contributed to the item difficulties more than the content attributes, and the IT attributes contributed much more than both the content and process attributes. The new retrofitted process attributes explained the items better than the TIMSS process attributes. Results generated from the level 1 attributes and the level 2 attributes were consistent. Most attributes could be used to recover students' performance, but some attributes' probabilities showed unreasonable patterns. The analysis approaches could not demonstrate if the same construct validity was supported across booklets. The proposed attributes and Q-matrices explained the items of Booklet 2 better than the items of Booklet 3. The specified Q-matrices explained the items better than the random Q-matrices.

Expert Approaches to Mental Toughness Development in the High Risk Sport of Diving

Research focusing on mental toughness development and high risk sport is limited to one examination of elite gymnasts' perceptions. Coaches have acknowledged that mental toughness is important to performance success, while admitting they do not know effective development strategies. The aim of the current research is to address both these concerns by employing a grounded theory approach to ascertain elite diving coaches perceptions of mental toughness development and what mental toughness is. Seven diving coaches volunteered and were interviewed for an average of 49 minutes. They all coached an athlete that participated either in the world championships or Olympic games since 2008. Participants reported that mental toughness was the ability of a diver to perform a movement in a crucial moment that requires focus, extending beyond their comfort zone, overcoming fear, and never giving up. Mentaltoughness may not be the appropriate term due to its lack of multicultural sensitivity. Participants felt that dealing with adversity was something divers would have to constantly process. Mental toughness can be developed by the coach, the environment, or individual athlete. Unique attributes specific to divers were an awareness of self and a distinct level of knowing what the athlete was going to do. More research needs to be conducted to determine if these concepts can be generalized to other high risk sports. Future research could help establish a valid quantitative measure of mental toughness development.

Testing prospect theory in students’ performance

This paper tests the existence of ‘reference dependence’ and ‘loss aversion’ in students’ academic performance. Accordingly, achieving a worse than expected academic performance would have a much stronger effect on students’ (dis)satisfaction than obtaining a better than expected grade. Although loss aversion is a well-established finding, some authors have demonstrated that it can be moderated – diminished, to be precise–. Within this line of research, we also examine whether the students’ emotional response (satisfaction/dissatisfaction) to their performance can be moderated by different musical stimuli. We design an experiment through which we test loss aversion in students’ performance with three conditions: ‘classical music’, ‘heavy music’ and ‘no music’. The empirical application supports the reference-dependence and loss aversion hypotheses (significant at p < 0.05), and the musical stimuli do have an influence on the students’ state of satisfaction with the grades (at p < 0.05). Analyzing students’ perceptions is vital to find the way they process information. Particularly, knowing the elements that can favour not only the academic performance of students but also their attitude towards certain results is fundamental. This study demonstrates that musical stimuli can modify the perceptions of a certain academic result: the effects of ‘positive’ and ‘negative’ surprises are higher or lower, not only in function of the size of these surprises, but also according to the musical stimulus received.

Direct versus indirect channels: Differentiated loss aversion in a high‐involvement, non‐frequently purchased hedonic product

Purpose – This article aims to investigate whether intermediaries reduce loss aversion in the context of a high-involvement non-frequently purchased hedonic product (tourism packages). Design/methodology/approach – The study incorporates the reference-dependent model into a multinomial logit model with random parameters, which controls for heterogeneity and allows representation of different correlation patterns between non-independent alternatives. Findings – Differentiated loss aversion is found: consumers buying high-involvement non-frequently purchased hedonic products are less loss averse when using an intermediary than when dealing with each provider separately and booking their services independently. This result can be taken as identifying consumer-based added value provided by the intermediaries. Practical implications – Knowing the effect of an increase in their prices is crucial for tourism collective brands (e.g. “sun and sea”, “inland”, “green destinations”, “World Heritage destinations”). This is especially applicable nowadays on account of the fact that many destinations have lowered prices to attract tourists (although, in the future, they will have to put prices back up to their normal levels). The negative effect of raising prices can be absorbed more easily via indirect channels when compared to individual providers, as the influence of loss aversion is lower for the former than the latter. The key implication is that intermediaries can – and should – add value in competition with direct e-tailing. Originality/value – Research on loss aversion in retailing has been prolific, exclusively focused on low-involvement and frequently purchased products without distinguishing the direct or indirect character of the distribution channel. However, less is known about other types of products such as high-involvement non-frequently purchased hedonic products. This article focuses on the latter and analyzes different patterns of loss aversion in direct and indirect channels.

A catalogue of books in the College library: [which Benjamin Welles wished to read], 1797

In this small paper-bound catalog, Benjamin Welles (1781-1860) listed books in the Harvard College Library which he wished to read. He presumably compiled the list by consulting the Library's 1790 printed catalog, as the works are categorized according to subjects outlined in that catalog (Antiquities, Astronomy, Ancient Authors, Biography, Sacred Criticism, Ethics, Geography, Geometry, History, Nature, Travels / Voyages, Natural Law, Logic, Metaphysics, Miscellaneous Works, Dramatic, Phililogy, Natural Philosophy, Poetry, Rhetoric, and Theology). The final pages of Welles' catalog, which he titles "Another Selection," list additional volumes he wished to read. These are listed alphabetically, A - G. Some titles throughout the catalog have been marked with a "+" perhaps to indicate that Welles had read them.

Record of undergraduates’ activities in virtual learning environments

Virtual learning environments (VLEs) have witnessed a high evolution, namely regarding their potentialities, the tools and the activities they provide. VLEs enable us to access large quantities of data resulting from both students and teachers’ activities developed in those environments. Monitoring undergraduates’ activities in VLEs is important as it allows us to showcase, in a structured way, a number of indicators which may be taken into account to understand the learning process more deeply and to propose improvements in the teaching and learning strategies as well as in the institution’s virtual environment. Although VLEs provide several data sectorial statistics, they do not provide knowledge regarding the institution’s evolution. Therefore, we consider the analysis of the activity logs in VLEs over a period of five years to be paramount. This paper focuses on the analysis of the activities developed by students in a virtual learning environment, from a sample of undergraduate students, approximately 7000 per year, over a period of five academic years, namely from 2009/2010 to 2013/2014. The main aims of this research work are to assess the evolution of activity logs in the virtual learning environment of a Portuguese public higher education institution, in order to fill possible gaps and to hold out the prospect of new forms of use of the environment. The results obtained from the data analysis show that overall, the number of accesses to the virtual learning environment increased over the five years under study. The most used tools were Resources, Messages and Assignments. The most frequent activities developed with these tools were respectively consulting information, sending messages and submitting assignments. The frequency of accesses to the virtual learning environment was characterized according to the number of accesses in the activity log. The data distribution was divided into five frequency categories named very low, low, moderate, high and very high, determined by the percentiles 20, 40, 60, 80 and 100, respectively. The study of activity logs of virtual learning environments is important not only because they provide real knowledge of the use that undergraduates make of these environments, but also because of the possibilities they create regarding the identification of a need for new pedagogical approaches or a reinforcement of previously consolidated approaches.

The language issue in Ukraine: An attempt at a new perspective. OSW Study 40/2012

Ukraine has been an independent state for only 20 years and the consequence of the long-term incorporation of Ukrainian lands into the Russian/Soviet state is an ethnically mixed society. In Ukraine, alongside Ukrainians, there are very many Russians and members of other nationalities of the former Soviet Union as well as a still large group of people who identify themselves as Soviets (in terms of their nationality). A significant part of Ukrainians use Russian in their everyday life (particularly professional) while knowing Ukrainian to only a small degree or not at all. Due to this Kyiv has to implement a language policy (which does not have to be pursued in e.g. Poland or Hungary) in search of solutions to ensure the stable functioning of a modern state for a multilingual society. The language issue is therefore an important challenge for the Ukrainian state and one of the more significant issues in Ukraine’s internal politics. In this text I eschew a detailed analysis of the question of Crimea as its social dynamics (also in the language area) is clearly distinct from the remaining part of Ukraine for four reasons: the short-term character of the region’s links with Ukraine, its relative geographic isolation (Crimea is almost an island), the formal autonomy of the Autonomous Republic of Crimea, and the presence of the Crimean Tatar community which is demanding the recognition of its language rights.

The knowing employment of illegal immigrants : hearing before the Subcommittee on Immigration and Refugee Policy of the Committee on the Judiciary, United States Senate, Ninety-seventh Congress, first session, on employer sanctions, September 30, 1981.

Item 1042-A, 1042-B (microfiche)

Knowing our waters : tribal reporting under section 305(b).

Mode of access: Internet.

Professional minority consulting firms /

Previously published as: Nation-wide roster of professional minority consulting firms

Knowing and teaching the migrant child.

Mode of access: Internet.

Characteristics of vehicle repair and maintenance problems for current vehicle-in-use. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Inquire within for anything you want to know, or, Over three thousand seven hundred facts worth knowing : particularly intended as a book for family reference on all subjects connected with domestic economy and containing the largest and most valuable collection of useful information that has ever yet been published : inquirers are referred to the index.

Includes index.