Why do bell plates ring?

Bell plates are polygonal plates which, when held in the hand and struck with a beater, produce an initial transient followed by a sustained, pure tone. The presence of the sustained tone depends sensitively on the shape. This paper addresses the question: why does a particular shape ring so well, while slightly different shapes do not? We show that, in the standard ringing shape, the nodal lines of one of the lowest modes of vibration fuse in the handle to produce a region that exerts neither vibrational force nor torque on the hand, and therefore does not transfer vibrational energy to the hand

Comparing unfamiliar voice and face identity perception using identity sorting tasks

Identity sorting tasks, in which participants sort multiple naturally varying stimuli of usually two identities into perceived identities, have recently gained popularity in voice and face processing research. In both modalities, participants who are unfamiliar with the identities tend to perceive multiple stimuli of the same identity as different people and thus fail to “tell people together.” These similarities across modalities suggest that modality-general mechanisms may underpin sorting behaviour. In this study, participants completed a voice sorting and a face sorting task. Taking an individual differences approach, we asked whether participants’ performance on voice and face sorting of unfamiliar identities is correlated. Participants additionally completed a voice discrimination (Bangor Voice Matching Test) and a face discrimination task (Glasgow Face Matching Test). Using these tasks, we tested whether performance on sorting related to explicit identity discrimination. Performance on voice sorting and face sorting tasks was correlated, suggesting that common modality-general processes underpin these tasks. However, no significant correlations were found between sorting and discrimination performance, with the exception of significant relationships for performance on “same identity” trials with “telling people together” for voices and faces. Overall, any reported relationships were however relatively weak, suggesting the presence of additional modality-specific and task-specific processes

Comparing unfamiliar voice and face identity perception using identity sorting tasks.

Identity sorting tasks, in which participants sort multiple naturally varying stimuli of usually two identities into perceived identities, have recently gained popularity in voice and face processing research. In both modalities, participants who are unfamiliar with the identities tend to perceive multiple stimuli of the same identity as different people and thus fail to "tell people together." These similarities across modalities suggest that modality-general mechanisms may underpin sorting behaviour. In this study, participants completed a voice sorting and a face sorting task. Taking an individual differences approach, we asked whether participants' performance on voice and face sorting of unfamiliar identities is correlated. Participants additionally completed a voice discrimination (Bangor Voice Matching Test) and a face discrimination task (Glasgow Face Matching Test). Using these tasks, we tested whether performance on sorting related to explicit identity discrimination. Performance on voice sorting and face sorting tasks was correlated, suggesting that common modality-general processes underpin these tasks. However, no significant correlations were found between sorting and discrimination performance, with the exception of significant relationships for performance on "same identity" trials with "telling people together" for voices and faces. Overall, any reported relationships were however relatively weak, suggesting the presence of additional modality-specific and task-specific processes

A novel approach to increasing cocaine detection confidence utilizing ion mobility spectrometry

When a positive detection of a narcotic occurs during the search of a vessel, a decision has to be made whether further intensive search is warranted. In terms of unwarranted delays of vessels and possible property damage, the accuracy of the analytical determination is very important. Analytical accuracy becomes critical when the data may be used in court actions as evidence. For this purpose, the U.S. Coast Guard has been investigating several confirmatory ion mobility spectrometry (IMS) field methods for the detection and identification of cocaine. This paper presents the findings of our investigations on the use of catalytic pyrolysis and base hydrolysis as confirmatory methods. The catalytic effects of various metals on the pyrolysis reaction are reported. In addition, the effects of several different ion mobility spectrometer sample transfer mediums and varying laboratory conditions on the base hydrolysis of the cocaine molecule are also be reported

The effect of sample holder material on ion mobility spectrometry reproducibility

When a positive detection of a narcotic occurs during the search of a vessel, a decision has to be made whether further intensive search is warranted. This decision is based in part on the results of a second sample collected from the same area. Therefore, the reproducibility of both sampling and instrumental analysis is critical in terms of justifying an in depth search. As reported at the 2nd Annual IMS Conference in Quebec City, the U.S. Coast Guard has determined that when paper is utilized as the sample desorption medium for the Barringer IONSCAN, the analytical results using standard reference samples are reproducible. A study was conducted utilizing papers of varying pore sizes and comparing their performance as a desorption material relative to the standard Barringer 50 micron Teflon. Nominal pore sizes ranged from 30 microns down to 2 microns. Results indicate that there is some peak instability in the first two to three windows during the analysis. The severity of the instability was observed to increase as the pore size of the paper is decreased. However, the observed peak instability does not create a situation that results in a decreased reliability or reproducibility in the analytical result

Cross-Species Differential Plasma Protein Binding of MBX-102/JNJ39659100: A Novel PPAR-γ Agonist

Drug binding to plasma proteins restricts their free and active concentrations, thereby affecting their pharmacokinetic properties. Species differences in plasma protein levels complicate the understanding of interspecies pharmacodynamic and toxicological effects. MBX-102 acid/JNJ39659100 is a novel PPAR-γ agonist in development for the treatment of type 2 diabetes. Studies were performed to evaluate plasma protein binding to MBX-102 acid and evaluate species differences in free drug levels. Equilibrium dialysis studies demonstrated that MBX-102 acid is highly bound (>98%) to human, rat and mouse albumin and that free MBX-102 acid levels are higher in rodent than in human plasma. Interspecies differences in free drug levels were further studied using PPAR-γ transactivation assays and a newly developed PPAR-γ corepressor displacement (biochemical) assay. PPAR-γ transactivation and corepressor displacement by MBX-102 acid was higher in rat and mouse serum than human serum. These results confirm the relevance of interspecies differences in free MBX-102 acid levels

Advanced Open-Cycle Desiccant Cooling System

The concept of staged regeneration as means of improving the desiccant cooling system performance is the subject of investigation in this study. In the staged regeneration, the regeneration section of desiccant dehumidifier is divided into two parts and only the latter fraction is subjected to the desorption air stream which has been heated to the desired regeneration temperature. In the present work, the mathematical model describing the heat and mass transfer processes that occur during sorption of moisture in the desiccnnt dehumidifier includes both the gas-side (film) and solid-side resistances for heat and mass transports. The moisture diffusion in the desiccant material is expressed by gas-phase diffusion and surface diffusion. Effects of several parameters on the performance of desiccant cooling system with staged regeneration are investigated and the results of present model are compared with those of the lumped-resistance model. Results of this study show that coefficient of perfomnnce of the desiccant cooling system can be substantially improved by using the staged regeneration concept. There is an optimum stage fraction and optimum cycle time for given system parmeters and operating conditions. The results also indicate that the cooling system performance is higher than that predicted by the lumped-resistance model

Speaker Sex Perception from Spontaneous and Volitional Nonverbal Vocalizations.

In two experiments, we explore how speaker sex recognition is affected by vocal flexibility, introduced by volitional and spontaneous vocalizations. In Experiment 1, participants judged speaker sex from two spontaneous vocalizations, laughter and crying, and volitionally produced vowels. Striking effects of speaker sex emerged: For male vocalizations, listeners' performance was significantly impaired for spontaneous vocalizations (laughter and crying) compared to a volitional baseline (repeated vowels), a pattern that was also reflected in longer reaction times for spontaneous vocalizations. Further, performance was less accurate for laughter than crying. For female vocalizations, a different pattern emerged. In Experiment 2, we largely replicated the findings of Experiment 1 using spontaneous laughter, volitional laughter and (volitional) vowels: here, performance for male vocalizations was impaired for spontaneous laughter compared to both volitional laughter and vowels, providing further evidence that differences in volitional control over vocal production may modulate our ability to accurately perceive speaker sex from vocal signals. For both experiments, acoustic analyses showed relationships between stimulus fundamental frequency (F0) and the participants' responses. The higher the F0 of a vocal signal, the more likely listeners were to perceive a vocalization as being produced by a female speaker, an effect that was more pronounced for vocalizations produced by males. We discuss the results in terms of the availability of salient acoustic cues across different vocalizations