La pedagogía de la investigación en la escuela secundaria y la implementación de Recorridos de Estudio e Investigación en matemática Otero, Maria Rita; Llanos, Viviana Carolina; Gazzola Bascougnet, María Paz En este trabajo se presentan resultados de una enseñanza por REI en la escuela secundaria, basada en la pedagogía de la investigación y del cuestionamiento del mundo, propuesta por Chevallard en la Teoría Antropológica de lo Didáctico (TAD). Se analizan protocolos para mostrar la actividad matemática del grupo de estudio. Se discuten algunos logros y se señalan ciertos obstáculos relativos a la implementación del REI y a la magnitud del cambio que es necesario realizar en la institución escuela secundaria.; In this paper some results related to teaching based on pedagogy of research and world questioning using Paths of Study and Research (PSR) at secondary school are presented. e framework of the Anthropological eory of Didactic (ATD) is used. Some protocols showing the mathematical activity of the study group are analyzed. Some achievements and obstacles related to the implementation of Paths of Study and Research (PSR) at secondary school are discussed, also, the challenges of the necessary changes in the secondary school are considered.

El diario Clarín y la "campaña antiargentina": la construcción de un consenso en torno a las violaciones a los derechos humanos Iturralde, Micaela Este artigo propõe uma indagação acerca do tratamento informativo e da linha editorial realizada pelo jornal diário argentino Clarín, sobre violações de direitos humanos cometidas na Argentina durante o regime militar 1976-1983. O texto está centrado na análise da conjuntura que começa em 1977 e continua em 1978, quando os militares iniciam uma campanha pública dizendo que há uma “campanha anti-argentina” e que as queixas de organismos internacionais pelo quadro dentro da Argentina eram, na realidade, interpretadas como parte da “ameaça subversiva” que se operava desde o interior do país, assim como do próprio exterior. Considerando que a omissão informativa que caracteriza a denúncia de uma “campanha anti-argentina” se refere diretamente à questão da repressão militar, consideramos também que as construções discursivas e representações criadas e difundidas por Clarín neste contexto - caracterizadas por uma adesão total à chamada “luta anti-subversiva” e pela exaltação nacionalista e patriótica (e êxito) em torno da Copa do Mundo de Futebol de 1978 -, constituíram o modo com que o jornal abordou o tema das violações dos direitos humanos.; En este artículo nos proponemos indagar el tratamiento informativo y editorial otorgado por el diario Clarín a las violaciones a los derechos humanos cometidas en la Argentina por el régimen militar que gobernó entre 1976 y 1983. Nos abocaremos al análisis de la coyuntura que se abre en 1977 y se extiende durante todo 1978, cuando se vuelve recurrente en las intervenciones públicas de los militares la denuncia de una supuesta “campaña antiargentina”, en la que los reclamos internacionales por la situación nacional fueron interpretados como parte de la “amenaza subversiva” que operaba desde el interior y el exterior. Dado que la omisión informativa que caracteriza la denuncia de una “campaña antiargentina” refiere directamente a la cuestión de la represión estatal, consideramos que las construcciones discursivas y representaciones creadas y difundidas por Clarín en este contexto, caracterizadas por una adhesión total a la llamada “lucha antisubversiva” y por la exaltación nacionalista y patriótica y el exitismo en torno al Mundial de Fútbol, constituyeron el modo en que el diario abordó el tema de las violaciones a los derechos humanos.

The relationship of clinical, cognitive and social measures in schizophrenia: A preliminary finding combining measures in probands and relatives Huepe, David; Riveros, Rodrigo; Manes, Facundo Francisco; Couto, Juan Blas Marcos; Hurtado, Esteban; Cetkovich Bakmas, Marcelo Gustavo; Escobar, Maria; Vergara, Viviana; Parrao, Teresa; Ibanez Barassi, Agustin Mariano This study examines performance of schizophrenia patients, unaffected relatives and controls in social cognition, cognitive and psychiatric scales looking for possible markers of vulnerability in schizophrenia. Performance of schizophrenia patients from multiplex families, first-degree relatives, and matched controls was compared and, subsequently, discriminant analysis method was used for identifying the best predictors for group membership. By using Multigroup Discriminant Analyses on the three groups, the best predictors were PANSS, Premorbid Adjustment Scale, Faux Pas test, and a face/emotion categorizing task. This model obtained 82% correct global classification, suggesting that the combination of psychiatric scales and neuropsychological/ social cognition tesks are the best approach for characterizing this disease. Although preliminary, our results suggest that social cognition tasks are robust markers of schizophrenia family impairments, and that combining clinical, social and neuropsychological measures is the best approach to asses patients and relatives vulnerability.

The role of vision in auditory distance perception Calcagno, Esteban; Abregú, Ezequiel Lucas; Eguia, Manuel Camilo; Vergara, Ramiro Oscar In humans, multisensory interaction is an important strategy for improving the detection of stimuli of different nature and reducing the variability of response. It is known that the presence of visual information affects the auditory perception in the horizontal plane (azimuth), but there are few researches that study the influence of vision in the auditory distance perception. In general, the data obtained from these studies are contradictory and do not completely define the way in which visual cues affect the apparent distance of a sound source. Here psychophysical experiments on auditory distance perception in humans are performed, including and excluding visual cues. The results show that the apparent distance from the source is affected by the presence of visual information and that subjects can store in their memory a representation of the environ- ment that later improves the perception of distance.

Abundance and diversity of tintinnids (planktonic ciliates) under contrasting levels of productivity in the Argentine Shelf and Drake Passage Santoferrara, Luciana Fernanda; Alder, Viviana Andrea The relationship between the abundance and diversity of tintinnids and the concentration of chlorophyll a (Chla) was contrasted between neritic and oceanic waters of the SW Atlantic during autumn and summer. Chla and tintinnid abundance and biomass reached maximum values (17.53μgL -1, 2.76×10 3ind.L -1, and 6.29μgCL -1, respectively) in shelf waters during summer, and their mean values generally differed by one order of magnitude between environments. Peaks in species richness (13) and Shannon diversity index (2.12) were found in the shelf-ocean boundary, but both variables showed nonsignificant differences between areas. Species richness correlated significantly with both Chla and abundance. Such relationships, which followed a negative linear or quadratic function in the shelf and a positive linear function in oceanic waters, are thought to reflect either the competitive dominance of one species or a relatively wide spectrum of tintinnid size-classes, respectively.

Dolor crónico, legitimidad y clausura: experiencias y saberes sobre la migraña del Mónaco, Romina Laura Este artículo analiza, desde una perspectiva socio-antropológica, las percepciones y experiencias de personas con un tipo de dolor de cabeza crónico, que los profesionales de la salud y los pacientes denominan migraña. El trabajo de campo se llevó a cabo en un hospital público de la Ciudad de Buenos Aires, donde se realizaron entrevistas a médicos neurólogos y personas con esta dolencia. Combinando la perspectiva fenomenológica con el interaccionismo simbólico propongo indagar cómo la percepción y las experiencias con el dolor influyen en la constitución de sí mismo, de la corporalidad y de las interacciones con los otros. Asimismo, se observan algunas particularidades de la migraña que la diferencian de otras dolencias crónicas y que condicionan los modos en que los pacientes se relacionan con su entorno. En primer lugar, carece de condiciones fácticas de verificación y no tiene una etiología precisa ni un tratamiento eficaz. En segundo lugar, se tiende a vincular esta dolencia con excusas, mentiras y manipulación. A partir de esto surgen cuestiones que vinculan el padecimiento con falta de legitimidad, angustia, aperturas y clausuras del yo que influyen en las relaciones de quienes padecen consigo mismos y con los otros.

Evaluación del desempeño de modelos de dispersión de contaminantes aplicados a cañones urbanos; Evaluation of the performance of atmospheric dispersion models applied to urban street canyons Venegas, Laura Esperanza; Mazzeo, Nicolas Antonio En los cañones urbanos, frecuentemente, se presentan concentraciones de contaminantes en aire varias veces superiores a la contaminación de fondo urbana. En este trabajo, se comparan valores de concentraciones de monóxido de carbono (CO) en aire medidas dentro de un cañón urbano con las estimadas mediante algunos modelos de dispersión atmosférica aplicables a procesos que se verifican en los cañones: STREET, STREET-BOX, OSPM y AEOLIUS. Se presenta la evaluación para condiciones de sotavento, barlovento y para direcciones intermedias del viento. En la comparación, se utilizaron los valores horarios de concentraciones de CO en aire medidas durante un año en el interior de un cañón urbano de Göttinger Strässe (Hannover, Alemania) y en el techo de un edificio lindero, de velocidad y dirección del viento observadas en el techo del mismo edificio y de flujo de tránsito vehicular en la calle del cañón. Para evaluar cuantitativamente el desempeño de los modelos, se calcularon los valores medios observados y estimados, el desvío, el error cuadrático medio y el error fraccional para las direcciones de viento correspondientes a sotavento, barlovento e intermedias. Los resultados generados por el modelo STREET con una constante empírica k=7 (valor del modelo original), subestimaron las concentraciones observadas, obteniéndose un mejor desempeño con k= 12,1. El modelo STREET-BOX es adecuado para condiciones de sotavento y direcciones intermedias, pero presenta diferencias importantes con las concentraciones observadas a barlovento. En general, los resultados aportados por los modelos OSPM y AEOLIUS fueron los que menos se apartaron de los valores observados.; Air pollutant concentrations inside street canyons are usually several times background concentrations in urban areas. In this paper, carbon monoxide (CO) concentrations observed in a street canyon are compared with estimated values obtained using four atmospheric dispersion models: STREET, STREET-BOX, OSPM and AEOLIUS. Results for leeward, windward and intermediate wind directions are analyzed. Data used in the model evaluation include one year of hourly CO concentrations measured inside a street canyon of Göttinger Strässe (Hannover, Germany) and at the roof of a nearby building, wind speed and direction data registered at the roof of the nearby building and traffic flow in the street. Each model performance was evaluated for leeward, windward and intermediate wind directions. Results obtained with the STREET model considering the empirical constant k=7 (default value), underestimated observed concentrations. A better performance of the STREET model was obtained with k= 12.1. The STREET-BOX model gave acceptable results for leeward and intermediate wind directions. The results of this model showed great differences with observed windward concentration values. In general, the concentrations estimated by OSPM and AEOLIUS showed the best agreement with observed values.

An analysis of 332 fatalities infected with pandemic 2009 influenza A (H1N1) in Argentina. Balanzat, Ana M.; Hertlein, Christian; Apezteguia, Carlos; Bonvehi, Pablo; Cámera, Luis; Gentile, Angela; Rizzo, Oscar; Gómez Carrillo, Manuel; Coronado, Fatima; Azziz Baumgartner, Eduardo; Chávez, Pollyanna R.; Widdowson, Marc Alain Background: The apparent high number of deaths in Argentina during the 2009 pandemic led to concern that the influenza A H1N1pdm disease was different there. We report the characteristics and risk factors for influenza A H1N1pdm fatalities. Methods: We identified laboratory-confirmed influenza A H1N1pdm fatalities occurring during June-July 2009. Physicians abstracted data on age, sex, time of onset of illness, medical history, clinical presentation at admission, laboratory, treatment, and outcomes using standardize questionnaires. We explored the characteristics of fatalities according to their age and risk group. Results: Of 332 influenza A H1N1pdm fatalities, 226 (68%) were among persons aged <50 years. Acute respiratory failure was the leading cause of death. Of all cases, 249 (75%) had at least one comorbidity as defined by Advisory Committee on Immunization Practices. Obesity was reported in 32% with data and chronic pulmonary disease in 28%. Among the 40 deaths in children aged <5 years, chronic pulmonary disease (42%) and neonatal pathologies (35%) were the most common co-morbidities. Twenty (6%) fatalities were among pregnant or postpartum women of which only 47% had diagnosed co-morbidities. Only 13% of patients received antiviral treatment within 48 hours of symptom onset. None of children aged <5 years or the pregnant women received antivirals within 48 h of symptom onset. As the pandemic progressed, the time from symptom-onset to medical care and to antiviral treatment decreased significantly among case-patients who subsequently died (p<0.001). Conclusion: Persons with co-morbidities, pregnant and who received antivirals late were over-represented among influenza A H1N1pdm deaths in Argentina, though timeliness of antiviral treatment improved during the pandemic.

Anomalous magnetization enhancement and frustration in the internal magnetic order on (Fe0.69Co0.31)B0.4 nanoparticles Molina Concha, Belén; Zysler, Roberto Daniel; Romero, Héctor We have studied the internal magnetic order of 3-nm (Fe0.69Co0.31)0.6B0.4 amorphous nanoparticles. These nanoparticles were dispersed in a non-magnetic matrix (non-interacting nanoparticles) to contrast them with the powder samples, where strong interparticle interactions are present. In similar fashion to the bulk alloy, this system exhibits a saturation magnetization maximum as a function of Fe composition near 69 at% Fe for the powder and dispersed samples at all temperatures. The saturation magnetization (MS) of the dispersed sample shows anomalous behavior, revealing frustration in the internal magnetic order of the particles. Unexpectedly, the MS of the non-interacting sample at low temperatures is larger than the corresponding bulk alloy or the calculated value of MS for the same Fe-Co composition. By contrast, the powder sample has low MS values and it is approximately constant in temperature.

Influence of network dynamics on the spread of sexually transmitted diseases Risau Gusman, Sebastian Luis Network epidemiology often assumes that the relationships defining the social network of a population are static. The dynamics of relationships is only taken indirectly into account by assuming that the relevant information to study epidemic spread is encoded in the network obtained, by considering numbers of partners accumulated over periods of timeroughly proportional to the infectious period of the disease. On the other hand, models explicitly including social dynamics are often too schematic to provide a reasonable representation of a real population, or so detailed that no general conclusions can be drawn from them. Here, wepresent a model of social dynamics that is general enough so its  parameters can be obtained by fitting data from surveys about sexual behaviour, but that can still be studied analytically, using mean-field techniques. This allows us to obtain some general results about epidemic spreading. We show that using accumulated network data to estimate the static epidemic threshold lead to a significant underestimation of that threshold. We also show that, for a dynamic network, the relative epidemic threshold is an increasing function of the infectious period of the disease, implying that the static value is a lower bound to the real threshold. A practical example is given of how to apply the model to the study of a real population.

Physicochemical and structural properties of amaranth protein isolates treated with high pressure Condes, María Cecilia; Speroni Aguirre, Francisco José; Mauri, Adriana Noemi; Añon, Maria Cristina The effects of high pressure (HP) (200, 400 and 600 MPa) on physicochemical and structural properties of amaranth proteins treated at different protein concentrations (1, 5 and 10% w/v) were studied. HP provoked denaturation of amaranth proteins which were very sensitive to HP treatment, achieving almost complete denaturation (93%) at 400 MPa. After HP, the resistant structures from glutenins, globulin-11S and globulin-P exhibited an increased thermal stability while those from albumins and globulin-7S exhibited a decrease of thermal stability. Increasing intensities of HP treatments provoked the disappearance of electrophoretic bands with molecular mass higher than 45 kDa, together with changes in the polypeptides fractions of low molecular weight. HP treatments induced the formation of insoluble aggregates and the dissociation of soluble aggregates. Protein concentration modulated the effects of HP on amaranth proteins. These modified proteins could present improved functional properties.

Galaxy triplets in Sloan Digital Sky Survey Data Release 7 - I. Catalogue O'Mill, Ana Laura; Duplancic Videla, Maria Fernanda; Garcia Lambas, Diego Rodolfo; Valotto, Carlos Alberto; Sodré Laerte, Jr We present a new catalogue of galaxy triplets derived from the Sloan Digital Sky Survey Data Release 7. The identification of systems was performed considering galaxies brighter than M_r=-20.5 and imposing constraints over the projected distances, radial velocity differences of neighbouring galaxies and isolation. To improve the identification of triplets we employed a data pixelization scheme, which allows to handle large amounts of data as in the SDSS photometric survey. Using spectroscopic and photometric data in the redshift range 0.01

Microbivalves from the Monte Leon Formation (Early Miocene), Patagonia, Argentina Griffin, Miguel; Pastorino, Roberto Santiago Guido Three new species (Mysella donaciformis n. sp., Cosa helianthea n. sp., and Lissarca saraballentae n. sp.) of small bivalves are described from early Miocene rocks in southern Patagonia. The outcrops lie along the coast of the province of Santa Cruz, within the boundaries of the Monte León National Park. The fossil-rich rocks exposed there at the base of the coastal cliff are included in the Punta Entrada Member of the Monte León Formation. This stratigraphic unit has been dated as early Miocene. It was probably deposited in a tidally-influenced near-shore and fully marine environment. The affinities of these small mollusks lie with taxa known to occur in other areas of the Southern Ocean, such as Antarctica, Australia, and New Zealand. The dispersal of these mollusks across vast expanses of water by means of rafting on drifting kelp is discussed.

Invasive non-native species of fish in Upper Paraná river Basin, Brazil: variations of caloric content in Cichla kelberi Espinola, Luis Guillermo; Júlio Junior, H. F; Benedito, E The allocation of assimilated energy may be influenced by seasonal changes, growth, and reproductive cycle of fish, food consumption and environmental conditions. The objective of this research was to evaluate the energetic variations of Cichla kelberi in the upper Paraná River floodplain, analyzing the caloric content in muscles, gonadosomatic index (GSI), and the condition factor between assessed systems, sex, and stage of gonadal maturation. The results obtained in the present study permit assuring that this is a species that efficiently converts the resources of the environment into energy. Although presenting higher condition factor in the environment where there is a greater ease in getting food (Paraná subsystem), the energy identified in the muscles was the same in both subsystems. During the process of gonadal maturation there is optimization in energy accumulation in the muscles of females, before and after reproductive period, and somatic growth occurs significantly when the individual is not reproducing. Further detailed studies on ecological mechanisms influencing the success of the species, as the presence of competitors and preference for native preys, are needed to implement effective management measures aimed at preventing that the species proliferation in the environment is even more damaging to local biodiversity.

Electrocatalysis: Fundamentals and Applications Zinola, Carlos F.; Martins, María Elisa; Pastor Tejera, E.; Pimenta Neves, Newton Electrocatalysis is a special field in Electrochemistry that hasgained a special growth after the late eighties due to theapplication of new hybrid techniques. However, most of theapplications have run for academic purposes but not fortechnical uses in the industry. Nowadays, the application ofnew concepts of electrocatalysis for industrial electrochemi-cal processes has appeared as a necessity and not only attract-ing attention for chemists but for engineers. Therefore,industrial electrocatalytic processes have only been presentedin the literature from the chemical engineering point of viewwith few further electrochemical explanations and mainlyduring the late seventies. The design and preparation of anelectrocatalyst (electrodes for technological uses) are basedon new concepts such as a controlled surface roughness,atomic topographic profiles, defined catalytic centre sites,atomic rearrangements, and phase transitions in the courseof the electrochemical reactions.

Importancia del autoabastecimiento energético: Impactos directos e indirectos sobre el crecimiento Recalde, Marina Yesica Este trabajo presenta un abordaje teórico de las implicancias directas, dados los límites biofísicos de la economía, e indirectas, por intermedio del impacto en la balanza comercial, de la falta de abastecimiento local. Como caso de estudio se analiza la situación actual del sistema energético argentino, y la existencia de ambas limitaciones a raíz de la caída del grado de autoabastecimiento energético y las crecientes demandas de importación de recursos energéticos. Los resultados del análisis muestran que la falta de abastecimiento local requerirá de importaciones crecientes de energía para sustentar el crecimiento económico, particularmente en el caso de países en desarrollo como Argentina. Esta situación ejerce una presión sobre la balanza de pagos, tal como lo predice la Ley de Thirwall, aún más importante atendiendo a la estructura de las importaciones y exportaciones locales. Se desprende de las conclusiones la importancia de la política energética tendiente al autoabastecimiento nacional.

Association between BoLA-DRB3 and somatic cell count in Holstein cattle from Argentina Baltian, Laura Rosana; Ripoli, María Verónica; Sanfilippo, S.; Takeshima, S. N.; Aida, Y.; Giovambattista, Guillermo Different studies have proved that the resistance/susceptibility to mastitis is genetically determined. The major histocompatibility complex in cows is known as bovine lymphocyte antigen (BoLA). Genes from the BoLA have been associated with the occurrence of infectious diseases such as mastitis and leukosis, especially the BoLA-DRB gene. The object of the present study was to detect associations between BoLA-DRB3 alleles and somatic cell count (SCC), as an indicator of resistance/ susceptibility to mastitis in Holstein cattle (N = 123) from La Pampa, Argentina. Fisher's exact test and Woolf- Haldane odds ratio were applied to study the association between SCC and BoLA-DRB3 allele frequencies. Significant association was noted between BoLA-DRB3.2*23 and *27 alleles (p <0.05) and protective or susceptibility effects, respectively. In addition, alleles BoLA-DRB3.2*20 and *25 exhibit suggestive association with high SCC (p < 0.1). These results were partially in agreement with data reported from Japanese Holstein cattle, but differed from those published by other authors. A possible explanation for the contrasting results could be that the mastitis is a multifactor disease caused by different pathogens. Moreover, most of the studies were carried out using PCR-RFLP method, which has less resolution than PCR-SBT because PCR-RFLP defined alleles included more than one sequenced alleles.

CD137 differentially regulates innate and adaptive immunity against Mycobacterium tuberculosis Fernández Do Porto, Darío Augusto; Jurado, Javier Oscar; Pasquinelli, Virginia; Alvarez, Ivana Belén; Aspera, Romina Haydeé; Musella, Rosa María; García, Verónica Edith Protective immunity against Mycobacterium tuberculosis is primarily mediated by the interaction of antigen-specific T cells and antigen presenting cells, which often depends on the interplay of cytokines produced by these cells. Costimulatory signals represent a complex network of receptor-ligand interactions that qualitatively and quantitatively influence immune responses. Thus, here we investigated the function of CD137 and CD137L, molecules known to have a central role in immune regulation, during human tuberculosis (TB). We demonstrated that M. tuberculosis antigen stimulation increased both CD137 and CD137L expression on monocytes and NK cells from TB patients and healthy donors, but only up-regulated CD137 on T lymphocytes. Blockage of the CD137 pathway enhanced the levels of interferon (IFN)-γ and tumor necrosis factor (TNF)-α produced by monocytes and NK against M. tuberculosis. In contrast, CD137 blockage significantly decreased the specific degranulation of CD8(+) T cells and the percentage of specific IFN-γ and TNF-α producing lymphocytes against the pathogen. Furthermore, inhibition of the CD137 pathway markedly increased T-cell apoptosis. Taken together, our results demonstrate that CD137:CD137L interactions regulate the innate and adaptive immune response of the host against M. tuberculosis.

Imaging nanometer-sized α-synuclein aggregates by superresolution fluorescence localization microscopy Roberti, Maria Julia; Fölling, Jonas; Celej, Maria Soledad; Bossi, Mariano Luis; Jovin, Thomas M.; Jares, Elizabeth Andrea The morphological features of alpha-synuclein (AS) amyloid aggregation in vitro and in cells were elucidated at the nanoscale by far-field subdiffraction fluorescence localization microscopy. Labeling AS with rhodamine spiroamide probes allowed us to image AS fibrillar structures by fluorescence stochastic nanoscopy with an enhanced resolution at least 10-fold higher than that achieved with conventional, diffraction-limited techniques. The implementation of dual-color detection, combined with atomic force microscopy, revealed the propagation of individual fibrils in vitro. In cells, labeled protein appeared as amyloid aggregates of spheroidal morphology and subdiffraction sizes compatible with in vitro supramolecular intermediates perceived independently by atomic force microscopy and cryo-electron tomography. We estimated the number of monomeric protein units present in these minute structures. This approach is ideally suited for the investigation of the molecular mechanisms of amyloid formation both in vitro and in the cellular milieu.

Size and shape variation in late Holocene projectile points of southern Patagonia: A geometric morphometry study Charlin, Judith Emilce; González José, Rolando Since the beginning of systematic archaeological studies in southern Patagonia (Argentina and Chile), projectile points have played an important role as cultural markers. A sequence of projectile point types was established according to their changes in size and shape. These stone tools, along with others cultural evidences, sensed to differentiate a series of "cultural periods," which were, for decades, the frame of reference to understand the cultural evolution in southernmost Patagonia. Although later researches have questioned several of these assumptions, the classical typology of projectile points continued in use until the present day. The goal of this work is to evaluate size and shape variation in two late Holocene projectile point types, known as Fell. Bird, or Magallanes IV and V points or Patagónicas and Ona points, respectively. These two types are compared using geometric morphometries and multivariate statistical analyses. The reliability in the discrimination between types is tested at the light of reduction. The analyses have shown a major incidence of reduction on shape rather than on size, and on blade rather than on stem. However, in average, types IV and V can be distinguished in terms of size, and stem shape despite reduction. Thus, even though successive cycles of use, damage and resharpening have a great influence over size and shape of projectile points, resharpening techniques are specific enough to maintain the differences of size and shape between types, a pattern that is probably related with functional requirements.; Desde los comienzos de los estudios arqueológicos sistemáticos en el sur de la Patagonia (Argentina y Chile), en la década de los 30’s, las puntas de proyectil han jugado un rol importante como marcadores culturales. De acuerdo con sus cambios en tamaño y forma, se estableció una secuencia de tipos morfológicos de puntas de proyectil. Estos instrumentos Uticos, junto con otras evidencias culturales, sirvieron para diferenciar una serie de “períodos culturales”, los cuales fueron, por décadas, el marco de referencia para entender la evolución cultural en el extremo austral de Patagonia meridional. A pesar de que las investigaciones posteriores han criticado varios de los supuestos básicos con los cuales se construyó esta periodizáción, la tipología clásica continúa en uso hasta hoy. El objetivo del presente trabajo es evaluar la variaciones en tamaño y forma en dos tipos de puntas de proyectil del Holoceno Tardío conocidos como Fell, Bird o Magallanes IV y V, o puntas Patagónicas y Onus, respectivamente. Éstos se consideraron como tipos diagnósticos para distinguir los Períodos IV y V en la secuencia regional de ocupación propuesta por Junius Bird. Aquí se comparan ambos tipos mediante análisis de morfometría geométrica y estadística multivariada. Se prueba la confiabilidad en la discriminación entre tipos a la luz de la reducción. La consideración del tamaño y la forma de las puntas de proyectil como variables independientes, gracias a las técnicas de la morfometría geométrica, ha permitido evaluar la incidencia relativa de la reducción sobre ambas variables, y también en relación con las diferentes partes que componen la punta de proyectil. Los análisis han mostrado una mayor incidencia de la reducción sobre la forma que sobre el tamaño, y sobre el borde que sobre el pedúnculo. Sin embargo, a pesar de los cambios morfométricos producto de la reducción, los tipos IV y V pueden distinguirse, en promedio, en base al tamaño y a la forma del pedúnculo. En consecuencia, si bien los sucesivos ciclos de uso, desgaste y reutilización tienen una gran influencia sobre el tamaño y la forma de las puntas de proyectil, las técnicas de reutilización son lo suficientemente específicas para mantener las diferencias de tamaño y forma entre tipos, probablemente en relación con demandas funcionales.