1,391 research outputs found
A first step to accelerating fingerprint matching based on deformable minutiae clustering
Fingerprint recognition is one of the most used biometric
methods for authentication. The identification of a query fingerprint requires
matching its minutiae against every minutiae of all the fingerprints
of the database. The state-of-the-art matching algorithms are costly, from
a computational point of view, and inefficient on large datasets. In this
work, we include faster methods to accelerating DMC (the most accurate
fingerprint matching algorithm based only on minutiae). In particular,
we translate into C++ the functions of the algorithm which represent the
most costly tasks of the code; we create a library with the new code and
we link the library to the original C# code using a CLR Class Library
project by means of a C++/CLI Wrapper. Our solution re-implements
critical functions, e.g., the bit population count including a fast C++
PopCount library and the use of the squared Euclidean distance for calculating
the minutiae neighborhood. The experimental results show a
significant reduction of the execution time in the optimized functions of
the matching algorithm. Finally, a novel approach to improve the matching
algorithm, considering cache memory blocking and parallel data processing,
is presented as future work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Fatigue crack nucleation in metallic materials
The process of fatigue crack nucleation in metallic materials is reviewed placing emphasis in results derived for pure FCC metals with wavy slip behavior. The relationship between Persistent Slip Bands (PSB`s) and crack initiation will be examined for both single crystals and polycrystals, including the conditions for inter- and transgranular crack nucleation and their connection to type of loading, crystallography and slip geometry. The latter has been found to be an important parameter in the nucleation of intergranular cracks in polycrystals subjected to high strain fatigue, whereby primary slip bands with long slip lengths impinging on a grain boundary produce intergranular crack nucleation under the right conditions. Recent results related to intergranular crack nucleation in copper bicrystals and crack nucleation in Cu/Sapphire interfaces indicate that this mechanism controls crack nucleation in those simpler systems as well. Furthermore, it is found that under multiple slip conditions the crack nucleation location is controlled by the presence of local single slip conditions and long slip lengths for a particular Burgers vector that does not have to be in the primary slip system
Favoreciendo en los alumnos la reflexión del quehacer en relación al aprendizaje de las matemáticas
Esta estrategia está encaminada a favorecer la modificación de la conducta del alumno como resultado de una profunda reflexión. Para promover en los alumnos el aprendizaje y el cambio de conducta pertinente, nos auxiliamos de estrategias de evaluación. Estas forman parte de la evaluación integral que debe hacer el estudiante camino de convertirse en exitoso, independiente y autosuficiente. Una “Bitácora de Reflexión” es usada en actividades, individuales y colectivas, con la intención de favorecer la revisión de lo hecho que afecta el desempeño y el aprovechamiento, se trata de que el alumno, detecte la(s) causa(s), pues si no lo hace, difícilmente pondrá solución a su situación y la probabilidad de que la historia se repita será muy alta. Se trata de detectar, usando la bitácora como ayuda, el problema y generar alternativas viables y lógicas de solución, las cuales deberán ser monitoreadas por los propios alumnos, lo que facilitará el desarrollo de conductas de autorregulación y de autonomía ya que el estudiante es libre de elegir entre la autoeficacia y la pseudo- eficacia o ineficacia. De esto se desprende un plan de acción para las futuras dos o tres semanas, mismo que será evaluado en la siguiente bitácora de reflexión. La congruencia entre el plan de acción y las conductas serán los objetivos de cada bitácora, la cual se alcanza después de varios intentos de elaboración de dicha bitácora, por lo que apelar a la paciencia y disposición del profesor será indispensable
Padina ditristromatica and Padina pavonicoides (Dictyotales, Phaeophyceae): two new records for the marine benthic flora of the Mediterranean Spanish coasts
Padina distristromatica Ni-Ni-Win & H. Kawai and Padina pavonicoides Ni-Ni-Win & H. Kawai, two species recently described from the Mediterranean Sea, are reported for the first time from the coasts of the Iberian Peninsula, and the former also from the Balearic Islands. In this paper new data are provided for both species, especially cell dimensions. The indusium features, which are proposed as new taxonomical character for P. distristromatica, as well as the lack of stolon-like structures in this species, are considered useful features for distinguishing P. distristromatica from P. pavonica. A distribution map of both species in the Spanish coasts is also provided
The lipid droplet protein DHRS3 is a regulator of melanoma cell state
Lipid droplets are fat storage organelles composed of a protein envelope and lipid rich core. Regulation of this protein envelope underlies differential lipid droplet formation and function. In melanoma, lipid droplet formation has been linked to tumor progression and metastasis, but it is unknown whether lipid droplet proteins play a role. To address this, we performed proteomic analysis of the lipid droplet envelope in melanoma. We found that lipid droplet proteins were differentially enriched in distinct melanoma states; from melanocytic to undifferentiated. DHRS3, which converts all-trans-retinal to all-trans-retinol, is upregulated in the MITFLO/undifferentiated/neural crest-like melanoma cell state and reduced in the MITFHI/melanocytic state. Increased DHRS3 expression is sufficient to drive MITFHI/melanocytic cells to a more undifferentiated/invasive state. These changes are due to retinoic acid mediated regulation of melanocytic genes. Our data demonstrate that melanoma cell state can be regulated by expression of lipid droplet proteins which affect downstream retinoid signaling
Computed tomography porosity and spherical indentation for determining cortical bone millimetre-scale mechanical properties
The cortex of the femoral neck is a key structural element of the human body, yet there is not a reliable metric for predicting the mechanical properties of the bone in this critical region. This study explored the use of a range of non-destructive metrics to measure femoral neck cortical bone stiffness at the millimetre length scale. A range of testing methods and imaging techniques were assessed for their ability to measure or predict the mechanical properties of cortical bone samples obtained from the femoral neck of hip replacement patients. Techniques that can potentially be applied in vivo to measure bone stiffness, including computed tomography (CT), bulk wave ultrasound (BWUS) and indentation, were compared against in vitro techniques, including compression testing, density measurements and resonant ultrasound spectroscopy. Porosity, as measured by micro-CT, correlated with femoral neck cortical bone’s elastic modulus and ultimate compressive strength at the millimetre length scale. Large-tip spherical indentation also correlated with bone mechanical properties at this length scale but to a lesser extent. As the elastic mechanical properties of cortical bone correlated with porosity, we would recommend further development of technologies that can safely measure cortical porosity in vivo. Introductio
N, P, K nutrition differentially affects the incidence and severity of the attack of pests and diseases in plants
Objective: To document and analyze relevant results reported on the relationships kept by the essential elements, nitrogen (N), phosphorus (P), and potassium (K) with biotic stress factors in higher plants.
Design/methodology/approach: A bibliographic analysis was carried out using keywords related to the concepts of nutrient relationship with phytopathogens, plant fertilization and nutrition and biotic stress. Subsequently, the most relevant articles on N, P, and K and their relationship with pests and diseases were selected and analyzed.
Results: The elements N, P, and K affect the development of pests on plants. Fertilization with N tend to increase the presence of pests, while fertilization with P and K decreases it. However, this cannot be generalized for all crops or pests.
Limitations/implications of the study: Research on the effects of N, P, and K on the incidence of phytopathogens is limited and in most cases the mechanisms that determine such relashionship are not described.
Findings/conclusions: Fertilization with N causes a higher incidence of pests and diseases in plants, while fertilization with P and K can contribute to reduce their incidence. However, due to the great diversity of responses, these statements are not applicable to all cases and depend on other factors such as the crop and the pest present in the agroecosystem. It is required to carry out studies that make it possible to clarify exactly how these essential elements influence the development of diseases in different crops, and thus be able to make nutrition recommendations in which limiting biotic factors are taken into account
Evaluation of trypanocidal properties of ferrocenyl and cyrhetrenyl N-acylhydrazones with pendant 5-nitrofuryl group
Four N-acylhydrazones of general formulae [R1-C(O)-NH-N=C(R2)(5-nitrofuryl)] with (R1 = ferrocenyl or cyrhetrenyl and R2 = H or Me) are synthesized and characterized in solution and in the solid-state. Comparative studies of their stability in solution under different experimental conditions and their electrochemical properties are reported. NMR studies reveal that the four compounds are stable in DMSO‑d6 and complementary UV-Vis studies confirm that they also exhibit high stability in mixtures DMSO:H2O at 37 °C. Electrochemical studies show that the half-wave potential of the nitro group of the N-acylhydrazones is smaller than that of the standard drug nifurtimox and the reduction process follows a self-protonation mechanism. In vitro studies on the antiparasitic activities of the four complexes and the nifurtimox against Trypanosoma cruzi and Trypanosoma brucei reveal that: i) the N-acylhydrazones have a potent inhibitory growth activity against both parasites [EC50 in the low micromolar (in T. cruzi) or even in the nanomolar (in T. brucei) range] and ii) cyrhetrenyl derivatives are more effective than their ferrocenyl analogs. Parallel studies on the L6 rat skeletal myoblast cell line have also been conducted, and the selectivity indexes determined. Three of the four N-acylhydrazones showed higher selectivity towards T. brucei than the standard drug nifurtimox. Additional studies suggest that the organometallic compounds are bioactivated by type I nitroreductase enzymes.</p
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