Recognizing classical ballet steps using plase space constraints

Thesis (M.S.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1995.Includes bibliographical references (leaves 64-68).by Lee Winston Campbell.M.S

Visual classification of co-verbal gestures for gesture understanding

Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2001.Includes bibliographical references (leaves 86-92).A person's communicative intent can be better understood by either a human or a machine if the person's gestures are understood. This thesis project demonstrates an expansion of both the range of co-verbal gestures a machine can identify, and the range of communicative intents the machine can infer. We develop an automatic system that uses realtime video as sensory input and then segments, classifies, and responds to co-verbal gestures made by users in realtime as they converse with a synthetic character known as REA, which is being developed in parallel by Justine Cassell and her students at the MIT Media Lab. A set of 670 natural gestures, videotaped and visually tracked in the course of conversational interviews and then hand segmented and annotated according to a widely used gesture classification scheme, is used in an offline training process that trains Hidden Markov Model classifiers. A number of feature sets are extracted and tested in the offline training process, and the best performer is employed in an online HMM segmenter and classifier that requires no encumbering attachments to the user. Modifications made to the REA system enable REA to respond to the user's beat and deictic gestures as well as turntaking requests the user may convey in gesture.(cont.) The recognition results obtained are far above chance, but too low for use in a production recognition system. The results provide a measure of validity for the gesture categories chosen, and they provide positive evidence for an appealing but difficult to prove proposition: to the extent that a machine can recognize and use these categories of gestures to infer information not present in the words spoken, there is exploitable complementary information in the gesture stream.by Lee Winston Campbell.Ph.D

Osteoblast-Restricted Disruption of the Growth Hormone Receptor in Mice Results in Sexually Dimorphic Skeletal Phenotypes

Growth hormone (GH) exerts profound anabolic actions during postnatal skeletal development, in part, through stimulating the production of insulin-like growth factor-1 (IGF-1) in liver and skeletal tissues. To examine the requirement for the GH receptor (GHR) in osteoblast function in bone, we used Cre-LoxP methods to disrupt the GHR from osteoblasts, both in vitro and in vivo. Disruption of GHR from primary calvarial osteoblasts in vitro abolished GH-induced signaling, as assessed by JAK2/STAT5 phosphorylation, and abrogated GH-induced proliferative and anti-apoptotic actions. Osteoblasts lacking GHR exhibited reduced IGF-1-induced Erk and Akt phosphorylation and attenuated IGF-1-induced proliferation and anti-apoptotic action. In addition, differentiation was modestly impaired in osteoblasts lacking GHR, as demonstrated by reduced alkaline phosphatase staining and calcium deposition. In order to determine the requirement for the GHR in bone in vivo, we generated mice lacking the GHR specifically in osteoblasts (ΔGHR), which were born at the expected Mendelian frequency, had a normal life span and were of normal size. Three week-old, female ΔGHR mice had significantly reduced osteoblast numbers, consistent with the in vitro data. By six weeks of age however, female ΔGHR mice demonstrated a marked increase in osteoblasts, although mineralization was impaired; a phenotype similar to that observed previously in mice lacking IGF-1R specifically in osteoblasts. The most striking phenotype occurred in male mice however, where disruption of the GHR from osteoblasts resulted in a feminization of bone geometry in 16 week-old mice, as observed by μCT. These results demonstrate that the GHR is required for normal postnatal bone development in both sexes. GH appears to serve a primary function in modulating local IGF-1 action. However, the changes in bone geometry observed in male ΔGHR mice suggest that, in addition to facilitating IGF-1 action, GH may function to a greater extent than previously appreciated in establishing the sexual dimorphism of the skeleton

Near-infrared spectroscopy in NGC 7538

The characterisation of the stellar population toward young high-mass star-forming regions allows to constrain fundamental cluster properties like distance and age. These are essential when using high-mass clusters as probes to conduct Galactic studies. NGC 7538 is a star-forming region with an embedded stellar population only unearthed in the near-infrared. We present the first near-infrared spectro-photometric study of the candidate high-mass stellar content in NGC 7538. We obtained H and K spectra of 21 sources with both the multi-object and long-slit modes of LIRIS at the WHT, and complement these data with sub-arcsecond JHKs photometry of the region using the imaging mode of the same instrument. We find a wide variety of objects within the studied stellar population of NGC 7538. Our results discriminate between a stellar population associated to the HII region, but not contained within its extent, and several pockets of more recent star formation. We report the detection of CO bandhead emission toward several sources as well as other features indicative of a young stellar nature. We infer a spectro-photometric distance of 2.7+-0.5 kpc, an age spread in the range 0.5-2.2 Myr and a total mass ~1.7x10^3 Msun for the older population.Comment: 11 pages, 8 figures, 1 table, accepted by A&

Dynamics of trimming the content of face representations for categorization in the brain

To understand visual cognition, it is imperative to determine when, how and with what information the human brain categorizes the visual input. Visual categorization consistently involves at least an early and a late stage: the occipito-temporal N170 event related potential related to stimulus encoding and the parietal P300 involved in perceptual decisions. Here we sought to understand how the brain globally transforms its representations of face categories from their early encoding to the later decision stage over the 400 ms time window encompassing the N170 and P300 brain events. We applied classification image techniques to the behavioral and electroencephalographic data of three observers who categorized seven facial expressions of emotion and report two main findings: (1) Over the 400 ms time course, processing of facial features initially spreads bilaterally across the left and right occipito-temporal regions to dynamically converge onto the centro-parietal region; (2) Concurrently, information processing gradually shifts from encoding common face features across all spatial scales (e.g. the eyes) to representing only the finer scales of the diagnostic features that are richer in useful information for behavior (e.g. the wide opened eyes in 'fear'; the detailed mouth in 'happy'). Our findings suggest that the brain refines its diagnostic representations of visual categories over the first 400 ms of processing by trimming a thorough encoding of features over the N170, to leave only the detailed information important for perceptual decisions over the P300

Profiting from Mean-Reverting Yield Curve Trading Strategies

Published in Journal of Fixed Income, 2006, 15 (4), 20-33. https://doi.org/10.3905/jfi.2006.627836</p

JAM-A regulates permeability and inflammation in the intestine in vivo

Recent evidence has linked intestinal permeability to mucosal inflammation, but molecular studies are lacking. Candidate regulatory molecules localized within the tight junction (TJ) include Junctional Adhesion Molecule (JAM-A), which has been implicated in the regulation of barrier function and leukocyte migration. Thus, we analyzed the intestinal mucosa of JAM-A–deficient (JAM-A−/−) mice for evidence of enhanced permeability and inflammation. Colonic mucosa from JAM-A−/− mice had normal epithelial architecture but increased polymorphonuclear leukocyte infiltration and large lymphoid aggregates not seen in wild-type controls. Barrier function experiments revealed increased mucosal permeability, as indicated by enhanced dextran flux, and decreased transepithelial electrical resistance in JAM-A−/− mice. The in vivo observations were epithelial specific, because monolayers of JAM-A−/− epithelial cells also demonstrated increased permeability. Analyses of other TJ components revealed increased expression of claudin-10 and -15 in the colonic mucosa of JAM-A−/− mice and in JAM-A small interfering RNA–treated epithelial cells. Given the observed increase in colonic inflammation and permeability, we assessed the susceptibility of JAM-A−/− mice to the induction of colitis with dextran sulfate sodium (DSS). Although DSS-treated JAM-A−/− animals had increased clinical disease compared with controls, colonic mucosa showed less injury and increased epithelial proliferation. These findings demonstrate a complex role of JAM-A in intestinal homeostasis by regulating epithelial permeability, inflammation, and proliferation

Resumen del taller sobre el uso de la reacción en cadena de la polimerasa (PCR) para distinguir entre Trypanosoma cruzi y tripanosoma rangeli

This workshop on the use of the polymerase chain reaction (PCR) to detect and differentiate T. cruziand T. rangeli had as its main purpose the transfer of this technology to laboratories in Colombia. To demonstrate this technique, we used clinical samples or isolates obtained from endemic areas of Colombia. In order to evaluate the possible effect of different culture media components on the sensitivity of PCR, analyses were performed on trypanosomes that were grown in different culture media. The DNA was extracted from these cells by boiling, Geneclean, and hypotonic Iysis. The DNA was amplified using a conserved 22 synthetic oligonucleotide sequence within the tandemly repeated mini-exon gene from T. cruzi and T. rangel;. The two organisms were distinguished by the electrophoretic mobilities of their respective amplification products. The confirmation of the identity of the PCR products was obtained using species-specific probes from intergenic regions. Hybridisation was visualised by the NBT colour reaction. From a total of 28 samples analysed, 17 identifications were in agreement with their prior identification. From 5 unknown samples, three were identified as T. rangeli and two as mixed infections. We obtained only two ambiguous identificationscaused by contamination in samples or PCR reaction. Only two samples could not be identified by PCR because of DNA extraction problems. The results from this workshop support the potential of the PCR technique as a usefuI additional tool for the detection and diagnosis of Chagas' disease in Colombia.Este taller se realizó con el propósito de transferir la tecnología de la reacción en cadena de la polimerasa (PCR) para la detección de T. cruzi y T. rangeli a laboratorios en Colombia involucrados en el diagnóstico y estudios epidemiológicos de la enfermedad de Chagas. Para demostración de la técnica se utilizaron muestras clínicas y epidemiológicas de áreas endémicas colombianas. En los ensayos se emplearon muestras de tripanosomas provenientes de diferentes medios de cultivo para evaluar el posible efecto de los componentes de estos medios sobre la sensibilidad del PCR. Se hizo extracción de ADN utilizando los métodos de ebullición, lisis hipotónica y geneclean. El ADN se amplificó utilizando oligonucleótidos sintéticos, correspondientes a una secuencia conservada de 22 nucleótidos dentro de un gen mini-exón. Los dos organismos fueron distinguidos por las movilidades electroforéticas de sus respectivos productos de amplificación, confirmando su identidad con sondas intergénicas específicas de especie, marcadas con digoxigenina dUTP. La hibridación se visualizó con la reacción de color del NBT. De un total de 28 muestras analizadas, se lograron 17 identificaciones que coincidieron con la clasificación original. De cinco muestras desconocidas, tres fueron identificadas como T. rangeli y dos como infecciones mixtas. Se presentaron resultados ambiguos en dos muestras, ocasionados por contaminación en el PCR. Solamente dos muestras no se pudieron identificar mediante PCR por problemas en la extracción del ADN de la muestra. Teniendo en cuenta estos resultados preliminares se abre la posibilidad de utilizar esta técnica como una herramienta útil o método adicional a las técnicas de rutina para detectar y diagnosticar la enfermedad de Chagas en Colombia