Low Frequency Characterization of Flaws in Ceramics

There is an increasing need for the characterization of small flaws in ceramic components. This project is concerned with detecting and characterizing flaws in the bulk of ceramic parts. Cylindrical tensile test specimens of hot pressed Si3N4 are being prepared and, when available, will be inspected. In preparation for the arrival of the samples, measurement techniques have been developed for inspection of cylindrical shaped samples, signal processing techniques have been developed for obtaining flaw scattering data over a broad range of frequencies and analysis techniques have been developed to automatically extract flaw characteristics from measured data

CT imaging of dogs with perineal hernia reveals large prostates with morphological and spatial abnormalities

The etiology of canine perinea) hernia (PH) remains unclear, although as a disease of older male dogs, it is likely to be hormonal. The role of the prostate in the formation of PH has been questioned; however, prospective and systematic evaluation of prostates in these dogs is absent in the literature. In this prospective case-control study, CT imaging was used to assess prostatic changes in dogs with PH (n = 46) and compare these findings with those of intact age-matched male dogs (n = 23). Using the OsiriX (R) DICOM viewer, we measured prostatic volume and correlated it with the size of the dog by using the length of the sixth lumbar vertebra. In addition, we recorded spatial and morphological changes of the prostate, such as heterogenicity, intra- and paraprostatic cysts, and mineralizations, as well as prostatic location and rotation. We found that dogs with PH had larger prostates (P < .001) that more often contained cysts (P < .001) and had larger cyst diameters (P = .013) than age-matched controls. Prostates of PH dogs also contained paraprostatic cysts (17.4%) and focal mineralizations (32.6%), which were absent in the control group. Abnormal rotation and location of the prostate were common in dogs with PH. In conclusion, these findings support the use of CT as an adjunct diagnostic imaging modality for the evaluation of the prostate in dogs with PH. Further studies are needed to evaluate nonprostatic CT findings in the pelvic cavity of PH dogs.Peer reviewe

Oro-facial pain experience among symphony orchestra musicians in Finland is associated with reported stress, sleep bruxism and disrupted sleep-Independent of the instrument group

Background To evaluate whether oro-facial pain experience was related to the type of musical instrument and to learn more about the roles of sleep and sleep-related issues in the pain among professional musicians. Objectives A standard questionnaire was sent to all Finnish symphony orchestras (n = 19), with altogether 1005 professional musicians and other personnel. Methods The questionnaire covered descriptive data, instrument group, items on perceived quality of sleep, possible sleep bruxism, stress experience and oro-facial pain experience during the past 30 days. Results In the present study, which included the musicians only, the response rate was 58.7% (n = 488). All orchestras participated in the study, and there was no significant difference in the response rate between the orchestras. The mean age of men (52.3%) was 47.7 (SD 10.3) and of women (47.7%) was 43.4 (SD 9.8) years (P <0.001). Overall, current pain in the oro-facial area was reported by 28.9%, frequent bruxism by 12.1% and frequent stress by 20.8%. According to Somers' d, there were statistically significant but moderate correlations between overall pain reports in the oro-facial area and disrupted sleep (d = 0.127, P = 0.001), sleep bruxism (d = 0.241, P <0.001) and stress experiences (d = 0.193, P <0.001). Logistic regression revealed, independent of the instrument group (string, woodwind, brass wind, percussion), that current oro-facial pain experience was significantly associated with disrupted sleep (P = 0.001), frequent sleep bruxism (P <0.001) and frequent stress (P = 0.002) experiences. Conclusions Among symphony orchestra musicians, oro-facial pain experience seems to be related to perceptions of stress, sleep bruxism and disrupted sleep rather than the instrument group.Peer reviewe

Tides: A key environmental driver of osteichthyan evolution and the fish-tetrapod transition?

Tides are a major component of the interaction between the marine and terrestrial environments, and thus play an important part in shaping the environmental context for the evolution of shallow marine and coastal organisms. Here, we use a dedicated tidal model and palaeogeographic reconstructions from the Late Silurian to early Late Devonian (420 Ma, 400 Ma and 380 Ma, Ma = millions of years ago) to explore the potential significance of tides for the evolution of osteichthyans (bony fish) and tetrapods (land vertebrates). The earliest members of the osteichthyan crown-group date to the Late Silurian, approximately 425 Ma, while the earliest evidence for tetrapods is provided by trackways from the Middle Devonian, dated to approximately 393 Ma, and the oldest tetrapod body fossils are Late Devonian, approximately 373 Ma. Large tidal ranges could have fostered both the evolution of air-breathing organs in osteichthyans to facilitate breathing in oxygen-depleted tidal pools, and the development of weight-bearing tetrapod limbs to aid navigation within the intertidal zones. We find that tidal ranges over 4 m were present around areas of evolutionary significance for the origin of osteichthyans and the fish-tetrapod transition, highlighting the possible importance of tidal dynamics as a driver for these evolutionary processes

Long Wave Ultrasonic Characterization of Inclusions in Silicon Nitride

The size and material content of Fe and Si inclusions in Si3N4 have been measured by means of pulse-echo scattering of elastic waves in the frequency range 5 to 100 MHz. The inclusions were of 100 μm and 400 μm nominal diameters and were located 3 mm deep in the Si3N4. The electronic noise was reduced by signal averaging and, in some cases, the noise due to grain scattering was reduced by averaging over transducer position. The scattering amplitude A(ω) and the impulse function R(t) were obtained by a desensitized deconvolution of the reference waveform obtained by reflecting the transmitted pulse from the back surface of the sample in a defect-free region. Comparison of theory and experiment are given for A(ω) and estimates of flaw size and material content are presented