Variation of the synarcual in the California Ray, Raja inornata (Elasmobranchii: Rajidae)

Seven juvenile specimens of Raja inornata were CT scanned and digitally modeled to examine the variation of synarcual morphology with changing size. The synarcual is a highly variable skeletal element across batoids with great potential for use in phylogenetic studies. Results show that as R. inornata increases in body size, the synarcual becomes more elongate and laterally compressed. Projections of the synarcual become more pronounced with increasing size as well. The synarcual of R. inornata is narrower than that of R. erinacea. There appears to be a correlation between median crest width and synarcual spine size. Also, in the context of higher-level batoid phylogenetics, the morphologically ventral position of the u-shaped lateral stay is considered primitive

Cadaveric and Chart Retrospective on Shoulder Variation: Morphology and Pain

Osteopathic Manipulative Treatment (OMT) is a category of several types of manual techniques used by osteopathic physicians. According to the osteopathic tradition, structure and function are intimately related. This project examined the relationship between shoulder structure and function in an osteopathic framework, with a specific goal to understand how the structure of the acromion affects the development of shoulder injuries. For the first part of this project, cadaveric dissections were performed and muscle diameters were taken of structures within the subacromial space. The second part of this project assessed the efficacy of OMT in shoulder somatic dysfunction for patients treated at Philadelphia College of Osteopathic Medicine (PCOM)

Plastination Procedure @ PCOM: Current Practice and Future Uses

Introduction: Since its invention by German anatomist Gunther von Hagens, the process of forced-impregnation plastination of organic specimens has become the standard for the preservation of biological tissue specimens. This practice serves as the most practical method to preserve these specimens for study and is utilized at PCOM regularly for this purpose. During the steps of plastination, aqueous and lipid tissues are replaced by a curable polymer to produce plastinates that do not decompose, can be handled without gloves, and retain most characteristics of the original specimens. For decades, PCOM used this method to prepare a permanent teaching collection in support of medical education. In the last five years, the lab has been reactivated and prepares specimens for allied health professional education, enrichment of the Doctor of Osteopathy curriculum, and outreach at regional institutions (e.g., The Franklin Institute, The Nebinger School, etc.). Objectives: The purpose of this poster is to inform the PCOM community of current plastination practices and suggest future uses. Methods: To prepare specimens for plastination, they must be preserved in fixative. We currently dissect and stage all tissues after the fixative process. Dissections are prepared by work-study students at PCOM who have completed the relevant anatomy course (interested students please contact Dr. Claeson). After fixation, tissues are dehydrated in progressively more concentrated washes of cold-temperature acetone (-20ºC) until concentration is between 98-100%. After dehydration, they are placed into a silicone polymer bath and brought to room temperature. The room temperature bath technique is the primary deviation from von Hagen (1977). Once at room temperature in the bath, vacuum pressure is used to replace the acetone that fills each cell with silicone. A hardening agent is then administered to finish the process. Results & Conclusions: Current initiatives have included building a collection of heart specimens to support a cardiac workshop which pairs anatomy and physiology. Most recently, a brain anatomy collection is being built. Brain specimens include axial cross sections, whole and half brains, and pathological specimens. These specimens are currently used at many outreach events and will be incorporated into a featured anatomy series as part of the medical school curriculum. Future research initiatives may also begin via current practices

Conus medullaris termination in adult females

Objective: The primary objective of this study was to determine the termination level of the spinal cord in a sample population of adult female cadavers. Introduction: The conus medullaris represents the tapered, distal-most end of the spinal cord. It tends to be found somewhere between the L1-L2 lumbar vertebrae and can sometimes be higher or lower. Studies report the conus medullaris can be found anywhere from the lower third of T11 to the upper third of L3 with the average termination point around the lower third of L1. We aim to describe the level of conus medullaris termination in a sample of female cadavers. Methods: Twenty-four female cadavers were dissected as part of the Doctor of Osteopathic Medicine curriculum at the Philadelphia College of Osteopathic Medicine. The end of the conus medullaris was defined as the point where tapering ends distal to the last branches of the posterior nerve rootlets. Using the articulation of the 12th rib as a landmark the termination of the conus medullaris was noted to be either at the level of an intervertebral disc or vertebral body. In the latter cases the vertebral body was divided into upper, middle, and lower thirds. Results: Conus Medullaris termination ranged from the T12-L1 intervertebral disc to the L2-L3 intervertebral disc. The L1-L2 intervertebral disc was the most common termination point with 42% of cadavers demonstrating spinal cord termination at this level. Conclusions: These results demonstrate that there is variation of spinal cord termination, which can play a role in lumbar punctures, spinal anesthesia, and obstetric anesthesia. Due to the risk of cord damage it is imperative to perform any sort of anesthetic procedure fully below the level of L3 in the L3-L4 space or L4-L5 space. An epidural injection above the level of L3 may cause severe spinal cord damage if there is dural puncture and an anatomical variant in which the conus medullaris extends to the L3 level

Giant lasing effect in magnetic nanoconductors

We propose a new principle for a compact solid-state laser in the 1-100 THz regime. This is a frequency range where attempts to fabricate small size lasers up till now have met severe technical problems. The proposed laser is based on a new mechanism for creating spin-flip processes in ferromagnetic conductors. The mechanism is due to the interaction of light with conduction electrons; the interaction strength, being proportional to the large exchange energy, exceeds the Zeeman interaction by orders of magnitude. On the basis of this interaction, a giant lasing effect is predicted in a system where a population inversion has been created by tunneling injection of spin-polarized electrons from one ferromagnetic conductor to another -- the magnetization of the two ferromagnets having different orientations. Using experimental data for ferromagnetic manganese perovskites with nearly 100% spin polarization we show the laser frequency to be in the range 1-100 THz. The optical gain is estimated to be of order 10^7 cm^{-1}, which exceeds the gain of conventional semiconductor lasers by 3 or 4 orders of magnitude. A relevant experimental study is proposed and discussed.Comment: 4 pages, 3 figure

Revision of the Eocene \u27Platyrhina\u27 species from the Bolca Lagerstätte (Italy) reveals the first panray (Batomorphii: Zanobatidae) in the fossil record

The fossil-Lagerstätte of Bolca (Italy) is well known for the diversity and exquisite preservation of its bony and cartilaginous fishes documenting tropical shallow-water marine environments associated with coral reefs in the western Tethys during the early Eocene. In this study, the taxonomic, systematic and phylogenetic position of two batoid species traditionally assigned to the living thornback ray genus Platyrhina is re-evaluated. †Platyrhina bolcensis Heckel, 1851 is recognized as a separate species of the Platyrhinidae because of its plate-like antorbital cartilage with an irregular outline and a small horn on the nasal capsules. Also, the rostral cartilage does not reach the anterior border of the disc. Support for the placement of this species within the new genus †Eoplatyrhina gen. nov. is based on a combination of morphological and meristic features (e.g. nasal capsules at right angles to the rostrum; large space between the hyomandibulae and mandibular arch; approximately 132 vertebral centra; 15–16 rib pairs; 81–87 pectoral radials; 18–21 pelvic radials; short, straight and stout claspers; 40–50 caudal-fin radials; thorns absent). A second species, †Platyrhina egertoni (De Zigno, 1876), is more closely related to the living panray Zanobatus than Platyrhina and is assigned here to †Plesiozanobatus gen. nov. because of a combination of characters that support its placement within the family Zanobatidae (tail stout and short, distinctly demarcated from disc; two dorsal fins and complete caudal fin; small dermal denticles and scattered thorns covering disc and tail; rostral cartilage absent; nasal capsules without horn-like processes; mesopterygium absent). The systematic position of a third taxon, †Platyrhina gigantea (Blainville, 1818), is currently impossible to establish due to the poor preservation of the only known specimen, and therefore we propose to consider it a nomen dubium. Palaeoecological and biogeographic features of the Eocene platyrhinids and zanobatids from Bolca are also discussed

A Synoptic Review of the Eocene (Ypresian) Cartilaginous Fishes (Chondrichthyes: Holocephali, Elasmobranchii) of the Bolca Konservat-Lagerstätte, Italy

Here, we review and discuss the records and taxonomy of the Ypresian (Eocene) chondrichthyans from the famous Bolca Konservat-Lagerstätte in northeastern Italy. Despite the outstanding diversity and the numerous studies focusing on the actinopterygian faunas from Pesciara and Monte Postale, the current knowledge about the systematics, taxonomy and phylogenetic relationships of the cartilaginous fishes from these Eocene sites remains elusive and largely inadequate. The celebrated Eocene Bolca Lagerstätte has yielded several exquisitely preserved articulated remains of chondrichthyan fishes in which delicate structures and soft tissues are preserved, as well as isolated teeth. The cartilaginous fish assemblage of Bolca comprises at least 17 species-level taxa belonging to 10 families in 6 orders, including selachians (Carcharhiniformes, Lamniformes), batoids (Torpediniformes, Myliobatiformes, Rajiformes) and holocephalans (Chimaeriformes). The occurrence of holocephalans represented by an isolated fin-spine of the chimeroid Ischyodus in the Bolca assemblage is reported here for the first time and represents the first record of chimeroids in the Eocene of Italy and also southern Europe. The Bolca chondrichthyan assemblage is remarkably different from those of other contemporaneous Boreal or Tethyan deposits, suggesting that its taxonomic composition is largely influenced by the palaeoenvironmental context. However, this synoptic review also highlights the importance of detailed revisions of all chondrichthyan remains from the Bolca Konservat-Lagerstätten

A New Species of the Neopterygian Fish Enchodus from the Duwi Formation, Campanian, Late Cretaceous, Western Desert, Central Egypt

The neopterygian fish Enchodus was a widespread, speciose genus consisting of approximately 30 recognized species that were temporally distributed from the late Early Cretaceous through the Paleocene. Many Enchodus specimens are fragmentary cranial remains or isolated dental elements, as is the case for previously reported occurrences in Egypt. Here, we present the most complete specimen of Enchodus recovered from the Late Cretaceous of northeast Africa. The specimen was collected from the upper Campanian Duwi Formation, near the village of Tineida (Dakhla Oasis, Western Desert, Egypt). The new species, Enchodus tineidae sp. nov., consists of right and left dentaries, a partial ectopterygoid, and other cranial bones. The size of the specimen places it into the upper body-size range for the genus. The palatine tooth, an element often useful for diagnosing Enchodus to the species level, is not preserved, but a combination of other cranial characters supports the referral of this specimen to Enchodus. In particular, the dentary preserves three symphysial rostroventral prongs and two tooth rows, the lateral of which consists of small denticles, whereas the medial row comprises large, mediolaterally-compressed teeth. The rostral-most tooth exhibits the highest crown, whereas the rest of the teeth are of lower, variable crown heights. The eight robust, caudal-most medial-row teeth are distributed in a cluster pattern never before observed in Enchodus. Additionally, the dentary and preopercle are both without dermal ornamentation, and the mandibular sensory canal is closed. Phylogenetic analysis recovers this new species as the sister species to E. dirus from North America. Along with previously described materials from Israel, Jordan, Syria, Lebanon, Italy, Morocco, and Libya, this specimen represents a thirteenth species from the northwestern Tethyan geographic distribution of Enchodus