The Proliferating and Malignant Proliferating Trichilemmal Cyst: An Anatomo-Clinical Study of Three Cases

<b><i>Background:</i></b> The proliferating and malignant proliferating trichilemmal cysts (MPTC) are rare adnexal tumors. We report 3 cases through which we will detail the anatomo-clinical characteristics of these tumors. <b><i>Cases:</i></b> Two patients, 60 and 56 years old, consulted for multiple scalp nodules, one of which had changed with the appearance of a central ulceration. The removal of the remaining scalp nodules was in favor of PTCs. The third patient presented with an ulcerative lesion occupying the vertex. Skin biopsy found trichilemmal-type keratinization associated with areas of necrosis concluding with a MPTC. <b><i>Discussion:</i></b> The PTC is a transitional form between the trichilemmal cyst (TC) and the MPTC. The increase in the size of a TC and ulceration are sufficient signals to suspect this evolution.

Peripheral Ossifying Fibroma: A Case Report

The gingiva is often considered as one of the most common sites of localized growths that are considered to be reactive rather than malignant in nature. Clinically, the majority of these lesions are difficult to identify, and therefore histopathology is useful in diagnosing these lesions as specific entities only on the basis of typical and consistent features. Focal gingival enlargements are quite frequent lesions in the oral cavity amounting to almost 3.1% of all oral tumors and 9.6% of gingival lesions. Peripheral ossifying fibroma (POF) is one of the reactive lesions that have typical histopathological features. Since the late 1940s, intraoral ossifying fibromas have been discussed in the literature. The term “Peripheral ossifying fibroma” is usually used to describe a fibroma of the gingiva which shows areas of calcification or ossification. They are usually classified as non-neoplastic enlargement of the gingiva. Many POFs are thought to develop initially as a pyogenic granuloma that undergoes fibrous maturation and subsequent calcification. However, many authors have suggested that rather than a transitional form of pyogenic granuloma or irritation fibroma, POF represents a separate clinical entity. Different lesions with clinical presentations similar to POF make it difficult to arrive at an appropriate diagnosis. Usually, the treatment of POF includes excision of the lesion surgically with minimal chances of recurrence. This paper describes a case report of a 32 year old female patient who reported growth on gingiva in the mandibular left anterior region of the mouth for three years.

Anatomy of Parahesperornis: Evolutionary Mosaicism in the Cretaceous Hesperornithiformes (Aves)

The Hesperornithiformes constitute the first known avian lineage to secondarily lose flight in exchange for the evolution of a highly derived foot-propelled diving lifestyle, thus representing the first lineage of truly aquatic birds. First unearthed in the 19th century, and today known from numerous Late Cretaceous (Cenomanian-Maastrichtian) sites distributed across the northern hemisphere, these toothed birds have become icons of early avian evolution. Initially erected as a taxon in 1984 by L. D. Martin, Parahesperornis alexi is known from the two most complete hesperornithiform specimens discovered to date and has yet to be fully described. P. alexi thus contributes significantly to our understanding of hesperornithiform birds, despite often being neglected in favor of the iconic Hesperornis. Here, we present a full anatomical description of P. alexi based upon the two nearly complete specimens in the collections of the University of Kansas Natural History Museum, as well as an extensive comparison to other hesperornithiform taxa. This study reveals P. alexi to possess a mosaic of basal and derived traits found among other hesperornithiform taxa, indicating a transitional form in the evolution of these foot-propelled diving birds. This study describes broad evolutionary patterns within the Hesperornithiformes, highlighting the significance of these birds as not only an incredible example of the evolution of ecological specializations, but also for understanding modern bird evolution, as they are the last known divergence of pre-modern bird diversification.

The body plan of Halszkaraptor escuilliei (Dinosauria, Theropoda) is not a transitional form along the evolution of dromaeosaurid hypercarnivory

The dromaeosaurid theropod Halszkaraptor escuilliei is characterized by several unusual features absent in other paravians, part of which has been interpreted as diagnostic of a novel lineage adapted to a semiaquatic ecology. Recently, these evolutionary and ecological interpretations have been challenged, and Halszkaraptor has been claimed to be a transitional form between non-dromaeosaurid maniraptoriforms and other dromaeosaurids: following that reevaluation, its peculiar body plan would represent the retention of several maniraptoran plesiomorphies, lost among other dromaeosaurids, and not an adaptation to a novel ecology. This alternative scenario is here carefully investigated and tested. It is shown that most statements supporting this scenario are based on misinterpretation of anatomical traits and bibliography. Once these statements have been corrected, character state transition optimization over a well-supported phylogenetic framework indicates that the large majority of the peculiar features of the Halszkaraptor lineage are derived novelties acquired by the latter after its divergence from the last ancestor shared with eudromaeosaurs, and thus are not maniraptoriform plesiomorphies. At least seven novelties of the Halszkaraptor lineage are convergently acquired with spinosaurids, and are integrated in semiaquatic adaptations: one of these is reported here for the first time. The amount of morphological divergence of Halszkaraptorinae from the ancestral dromaeosaurid condition is comparable to those of Microraptorinae and Velociraptorinae. Among extant taxa, the sawbills (Mergini, Anseriformes) show the closest ecomorphological similarity with the peculiar body plan inferred for Halszkaraptor. The halszkaraptorine bauplan is thus confirmed as a derived amphibious specialization, and does not represent a “transitional” stage along the evolution of dromaeosaurids.

Thermal Environment Analysis and Improvement on Isolated Cold Aisle Data Centers

Isolated cold aisle airflow distribution is a transitional form from non-isolated airflow distribution to closed cold aisle airflow distribution. With the increase of the power of racks, cooling failure may happen in the layout of the isolated cold aisle. This paper presents the study on cooling performance of the racks which are improved through bottom ventilating reform and adjustment. Inlet/outlet air temperature and mass flow rate of the racks are investigated in detail under conditions of various bottom ventilated areas and various porosities of the raised floor. The characteristics of airflow distribution are contrastively analyzed through calculating indexes of the thermal environment of data centers. Results show that adequate ventilation through the bottom of the racks is good for improvement of the state of airflow distribution. There is an optimization range (0.1–0.3 m and 0.05–0.15 m, respectively) of the ventilated area at the bottom of the racks. And high porosity (above 50%) of the ventilated area can reduce the inlet and outlet temperatures of the racks and the racks in different positions have a better temperature uniformity. In conclusion, bottom ventilation of racks is a feasible plan to improve airflow distribution, and schemes of ventilated area and porosity of corresponding raised floor should be designed respectively under consideration of the layout of racks and AC.