ABSTRACT
We examined the status of the first metacarpal bone whose shape, fetal and post-natal development correspond to those of the thumb proximal phalanx. Galen already described this, circa 170 CE. Our radiographic data confirm that the pre-axial (radial or anterior) side of the hand matures, later than the post-axial (ulnar or posterior) side, both, pre- and post-natally. A new perspective on thumb primate and human ontogeny is discussed and comparative observations on the Evolutionary Development (EvoDevo) of the thumb and the first toe are proposed along with a nomenclature honoring Galen's original roposition.
Se analiza el estado del primer metacarpiano cuya forma y desarrollo embrionario, fetal y postnatal corresponde a los de la primera falange del pulgar. Galeno notó que éste era la primera falange del pulgar cerca de 170 DC. Esto no es un simple cambio de nomenclatura, ya que da una nueva luz a los problemas evolutivos de ontogenia (EvoDevo). Nuestros datos radiográficos confirman que el lado radial (anterior o pre-axial) de la mano madura, pre y post-natalmente, mas tardíamente que el lado cubital (posterior o post-axial). Se discuten nuevas perspectivas sobre la ontogenia y filogenia humana y de primates, y se proponen estudios comparativos del desarrollo del pulgar y del ortejo mayor.
Subject(s)
Humans , Male , Adolescent , Female , Infant, Newborn , Infant , Child, Preschool , Child , Finger Phalanges/growth & development , Metacarpal Bones/growth & development , Thumb/growth & development , Bone Development , Developmental Biology , Finger Phalanges , Metacarpal Bones , ThumbABSTRACT
One of the main issues in radiology is image analysts and report. The two stages of this process are the extraction of the information from the image and the diagnostic exercise. This paper is a theoretical analysis of image interpretation from a quantitative perspective, using information theory and Bayesian inference, and relating it to the concepts of evidence based medicine. It is concluded that the amount of information is dependent on the previous state of knowledge and the acquaintance with the clinical history and complementary exams. The three determined stages of the diagnostic process are a priori, conditioned by the image and a posteriori analyses. The first stage is related to the degree of information and knowledge of the case. The second stage is dependent on the conditional probability for the presence of image signs of the disease and it is thus directly dependent on the sensitivity and specificity of the exam. The third stage is dependent of the previous stages, that in the simplest case can be expressed in function of the odds or likelihood ratios. These three stages allow to reach a decision about the usefulness of a given exam and they orient the questions that a given image may answer. They also orient the research on image analysis for an adequate decision making, minimizing diagnostic uncertainty.
Subject(s)
Humans , Radiography , Bayes Theorem , Decision Theory , Decision Making , Evidence-Based Medicine , Models, Statistical , Models, TheoreticalABSTRACT
There are two vectors of Chagas disease in Chile: Triatoma infestans and Mepraia spinolai. We studied the feeding behavior of these species, looking for differences which could possibly explain the low impact of the latter species on Chagas disease. Both species used thermal cues to locate their feeding source and consumed a similar volume of blood which was inversely related to the body weight before the meal and directly related to the time between meals. The average time between bites were 6.24 and 10.74 days. The average bite of M. spinolai lasted 9.68 min, significantly shorter than the 19.46 min for T. infestans. Furthermore, while T. infestans always defecated on the host, this behavior was observed in M. spinolai in only one case of 27 (3.7 per cent). The delay between the bites and defecation was very long in M. spinolai and short in T. infestans. These differences may affect the reduced efficiency of transmission of Chagas infection by M. spinolai.
Subject(s)
Animals , Chagas Disease/transmission , Feeding Behavior , Insect Vectors/physiology , Triatominae/physiology , Body Weight , Chile , Defecation , Insect Bites and Stings , Triatoma/physiologyABSTRACT
El árbol bronquial de los mamíferos presenta un diseño que se ha asociado con un adecuado flujo de gases a los alvéolos, una mínima producción de entropía en la mecánica respiratoria y con un mínimo costo en materia y energía. Sin embargo, la vía aérea constituye sólo parte del sistema respiratorio y como tal su geometría debe ajustarse a la función de todo el sistema resolviendo el problema de distribuir un volumen de aire inspirado en una gran superficie, dispuesta en un volumen acotado. Así, la topología bronquial exhibe las características de ocupar espacio con su ramificación progresiva y una reducción del diámetro de los bronquios que se ha asociado a una geometría fractal. En este trabajo se caracteriza la topología del árbol bronquial de Rattus norvegicus mediante su dimensión fractal y se compara con otros mamíferos de distinto tamaño: Oryctolagus cuniculli y Homo sapiens. Se estudia además el efecto de la escala para verificar la autosimilitud. Los resultados demuestran una geometría fractal de la vía aérea de las tres especies, que se mantiene a distintas escalas y son una demostración directa de este tipo de geometría. La topología se mantiene invariante en las tres especies, con dimensiones fractales entre 1,57 y 1,59. Los resultados coinciden con otros estudios realizados en la vía aérea, la superficie alveolar, la ventilación y la perfusión pulmonar. Se discuten las consecuencias de este tipo de geometría en el pulmón