Wireless recording of the calls of Rousettus aegyptiacus and their reproduction using electrostatic transducers

Bats are capable of imaging their surroundings in great detail using echolocation. To apply similar methods to human engineering systems requires the capability to measure and recreate the signals used, and to understand the processing applied to returning echoes. In this work, the emitted and reflected echolocation signals of Rousettus aegyptiacus are recorded while the bat is in flight, using a wireless sensor mounted on the bat. The sensor is designed to replicate the acoustic gain control which bats are known to use, applying a gain to returning echoes that is dependent on the incurred time delay. Employing this technique allows emitted and reflected echolocation calls, which have a wide dynamic range, to be recorded. The recorded echoes demonstrate the complexity of environment reconstruction using echolocation. The sensor is also used to make accurate recordings of the emitted calls, and these calls are recreated in the laboratory using custom-built wideband electrostatic transducers, allied with a spectral equalization technique. This technique is further demonstrated by recreating multi-harmonic bioinspired FM chirps. The ability to record and accurately synthesize echolocation calls enables the exploitation of biological signals in human engineering systems for sonar, materials characterization and imaging

Continuous first order logic for unbounded metric structures

We present an adaptation of continuous first order logic to unbounded metric structures. This has the advantage of being closer in spirit to C. Ward Henson's logic for Banach space structures than the unit ball approach (which has been the common approach so far to Banach space structures in continuous logic), as well as of applying in situations where the unit ball approach does not apply (i.e., when the unit ball is not a definable set). We also introduce the process of single point \emph{emboundment} (closely related to the topological single point compactification), allowing to bring unbounded structures back into the setting of bounded continuous first order logic. Together with results from \cite{BenYaacov:Perturbations} regarding perturbations of bounded metric structures, we prove a Ryll-Nardzewski style characterisation of theories of Banach spaces which are separably categorical up to small perturbation of the norm. This last result is motivated by an unpublished result of Henson

Examining the Effect of Perceived Responsibility on Online Bystander Intervention, Target Hardening, and Inaction

Failure to take responsibility for intervening has been identified as a primary barrier to bystander intervention. Building on these findings, we examine how perceptions of responsibility affect responses to witnessing victimization in the online realm—a topic that has received limited attention. Using a maximum-likelihood selection model, we analyze data from the Pew American Trends Panel (N = 3709) to estimate the effects of respondents’ perceptions of the role different groups should play in addressing online harassment on their likelihood to engage in intervention, target hardening, or inaction in response to witnessing online harassment, conditioned upon their likelihood of having witnessed such behavior. Findings indicate that the greater role respondents believe online users should have in addressing online harassment, the more likely they are to intervene. (b = .310). The greater role respondents believe law enforcement or elected officials should have in addressing online harassment, the less likely they are to intervene (b = −.135 and −.072, respectively). These findings have implications for future efforts to curb online harassment through users’ crime prevention efforts

Respiratory muscle activity in relation to vocalization in flying bats.

The structure of the thoracic and abdominal walls of Pteronotus parnellii (Microchiroptera: Mormoopidae) was described with respect to their function in respiration and vocalization. We monitored electromyographic activity of respiratory and flight muscles in relation to echolocative vocalization. In flight, signals were telemetered with a small FM transmitter modified to summate the low-frequency myopotentials with biosonar signals from a ceramic-crystal microphone. Recordings were also made from the same bats confined to a small cage. Vocalizations were used as the parameter by which all muscle activities were correlated. A discrete burst of activity in the lateral abdominal wall muscles accompanied each vocalization. Diaphragmatic myopotentials occurred between groups of calls and did not coincide with activity of the abdominal wall or with vocalizations. Flight muscles were not active in resting bats. During flight, vocalizations and the abdominal muscle activity that accompanied them coincided with myopotentials of the pectoralis and serratus ventralis muscles. We propose that contractions of the lateral abdominal wall provide the primary power for the production of intense biosonar vocalization in flying and in stationary bats. In flight, synchronization of vocalization with activity of the pectoralis and serratus ventralis jointly contribute to the pressurization of the thoraco-abdominal cavity. This utilization of pressure that is normally generated in flight facilitates respiration and allows for the production of intense vocalizations with little additional energetic expenditure

Ultrasonic vocalizations of flying bats monitored by radiotelemetry

Ultrasonic vocalizations of flying bats were effectively monitored with radiotelemetry. We describe a device light enough to be carried by an 11 g bat for periods of up to 1 h. It transmitted signals adequate for fine frequency analysis within a range of approximately 3 m. Telemetry permitted the recording of constant-frequency pulses free from flight-induced Doppler shifts and without time delays. The difference in frequency between telemetered signals and the same signals detected by a remote microphone was used to calculate velocity and Doppler shifts. Pulse emission behavior of Pteronotus parnellii in flight was compared with simulated flight on a pendulum. The data showed significant differences in echo bandwidths, constant-frequency pulse durations and interpulse intervals. In flight, pulses and interpulse intervals tended to be shorter and bats maintained echo frequencies within a significantly narrower band. Phases of echolocation that characterized the approach to a target were clearly evident in flight, but not during pendulum swings. Differences in pulse durations and interpulse intervals may be correlated with the integration of wingbeat, respiration and vocalization. The absence of wing motion in simulated flight changes this integration

Examining the Effect of Perceived Responsibility On Online Bystander Intervention, Target Hardening, and Inaction

Failure to take responsibility for intervening has been identified as a primary barrier to bystander intervention. Building on these findings, we examine how perceptions of responsibility affect responses to witnessing victimization in the online realm—a topic that has received limited attention. Using a maximum-likelihood selection model, we analyze data from the Pew American Trends Panel (N = 3709) to estimate the effects of respondents’ perceptions of the role different groups should play in addressing online harassment on their likelihood to engage in intervention, target hardening, or inaction in response to witnessing online harassment, conditioned upon their likelihood of having witnessed such behavior. Findings indicate that the greater role respondents believe online users should have in addressing online harassment, the more likely they are to intervene. (b = .310). The greater role respondents believe law enforcement or elected officials should have in addressing online harassment, the less likely they are to intervene (b = −.135 and −.072, respectively). These findings have implications for future efforts to curb online harassment through users’ crime prevention efforts