Experimental Evaluation of Three Designs of Electrodynamic Flexural Transducers.

Three designs for electrodynamic flexural transducers (EDFT) for air-coupled ultrasonics are presented and compared. An all-metal housing was used for robustness, which makes the designs more suitable for industrial applications. The housing is designed such that there is a thin metal plate at the front, with a fundamental flexural vibration mode at ∼50 kHz. By using a flexural resonance mode, good coupling to the load medium was achieved without the use of matching layers. The front radiating plate is actuated electrodynamically by a spiral coil inside the transducer, which produces an induced magnetic field when an AC current is applied to it. The transducers operate without the use of piezoelectric materials, which can simplify manufacturing and prolong the lifetime of the transducers, as well as open up possibilities for high-temperature applications. The results show that different designs perform best for the generation and reception of ultrasound. All three designs produced large acoustic pressure outputs, with a recorded sound pressure level (SPL) above 120 dB at a 40 cm distance from the highest output transducer. The sensitivity of the transducers was low, however, with single shot signal-to-noise ratio ( SNR ) ≃ 15 dB in transmit-receive mode, with transmitter and receiver 40 cm apart.

Clinical and microscopic characteristics of canine toxic epidermal necrolysis.

Canine toxic epidermal necrosis (TEN), a rare and life-threatening cutaneous drug reaction, traditionally has been described as full-thickness devitalization of the epidermis with minimal dermal inflammation; however, few reports detail the histologic findings. We characterize the clinical features and histologic variations of 3 canine TEN patients. Clinically, irregular erythematous and purpuric macules evolved into widespread and severely painful erosions. The number of eroded mucosae varied; however, periocular and perilabial mucocutaneous junctions frequently were affected. Thirteen of 17 biopsies were evaluated. Apoptosis at multiple epidermal levels was the most common pattern of epidermal necrosis (12/13 biopsies, 92%). In contrast, full-thickness coagulation necrosis was present less often (7/13 biopsies, 52%). Lymphocytic interface dermatitis was the predominant inflammatory pattern, and intraepidermal lymphocytes, along with fewer histiocytes, were present to some degree in all samples along with lymphocytic satellitosis of apoptotic keratinocytes. The sequence of changes points to lymphocyte-mediated keratinocyte apoptosis as an early step in lesion development with subsequent variation in progression to coagulation necrosis among patients. Histopathologic changes overlapped with those reported for erythema multiforme, in contrast to traditional histologic descriptions of canine TEN. A specific algorithm for assessment of drug causality in epidermal necrolysis (ALDEN) was applied for each patient; carprofen was associated with a probable score for causality in 1 dog. Clinicians should be encouraged to take multiple biopsies in TEN suspect cases as nearly 25% of all biopsies lacked epithelium and were not diagnostic.

Thymofibrolipoma in a labrador retriever.

While thymomas are uncommon but well-known mediastinal masses, collagen-rich variants are exceedingly rare. Thymofibrolipoma and sclerosing thymoma tumor variants have been recently recognized in medical pathology, and thymofibrolipoma has been only rarely reported in dogs. A cranial thoracic mass was identified in a 6-year-old Labrador Retriever that was characterized by robust collagenous stroma dissected by thin cords of cytokeratin-positive neoplastic epithelial cells and bordered by mildly pleomorphic epithelial cells with occasional lymphocytic aggregates and rare Hassall corpuscles. To the authors' knowledge, this is only the second report of thymofibrolipoma in veterinary medicine and the first to describe a variant with a mitotically active and relatively pleomorphic, adjacent thymic epithelial population.