3,383 research outputs found
On the molecules of numerical semigroups, Puiseux monoids, and Puiseux algebras
A molecule is a nonzero non-unit element of an integral domain (resp.,
commutative cancellative monoid) having a unique factorization into
irreducibles (resp., atoms). Here we study the molecules of Puiseux monoids as
well as the molecules of their corresponding semigroup algebras, which we call
Puiseux algebras. We begin by presenting, in the context of numerical
semigroups, some results on the possible cardinalities of the sets of molecules
and the sets of reducible molecules (i.e., molecules that are not
irreducibles/atoms). Then we study the molecules in the more general context of
Puiseux monoids. We construct infinitely many non-isomorphic atomic Puiseux
monoids all whose molecules are atoms. In addition, we characterize the
molecules of Puiseux monoids generated by rationals with prime denominators.
Finally, we turn to investigate the molecules of Puiseux algebras. We provide a
characterization of the molecules of the Puiseux algebras corresponding to
root-closed Puiseux monoids. Then we use such a characterization to find an
infinite class of Puiseux algebras with infinitely many non-associated
reducible molecules.Comment: 21 pages, 2 figure
Second-order Democratic Aggregation
Aggregated second-order features extracted from deep convolutional networks
have been shown to be effective for texture generation, fine-grained
recognition, material classification, and scene understanding. In this paper,
we study a class of orderless aggregation functions designed to minimize
interference or equalize contributions in the context of second-order features
and we show that they can be computed just as efficiently as their first-order
counterparts and they have favorable properties over aggregation by summation.
Another line of work has shown that matrix power normalization after
aggregation can significantly improve the generalization of second-order
representations. We show that matrix power normalization implicitly equalizes
contributions during aggregation thus establishing a connection between matrix
normalization techniques and prior work on minimizing interference. Based on
the analysis we present {\gamma}-democratic aggregators that interpolate
between sum ({\gamma}=1) and democratic pooling ({\gamma}=0) outperforming both
on several classification tasks. Moreover, unlike power normalization, the
{\gamma}-democratic aggregations can be computed in a low dimensional space by
sketching that allows the use of very high-dimensional second-order features.
This results in a state-of-the-art performance on several datasets
Evaluation of Linked Determinants Between Diabetes and Caries
Dental caries and diabetes mellitus, represent two chronic diseases of public health that present statistics of high prevalence worldwide. One of the main problems that affect these conditions is demography, since the least developed countries are those that have less access to public health services and are limited by the economic costs that represent the treatments. In this work is presented the univariate analysis, of a set of demographic determinants obtained from the National Health and Nutrition Examination Surveys (NHANES), in order to identify those that present the most significant information related to estimation of these diseases. According to the results, the age of the subjects is the main determinant describing the simultaneous presence of these diseases, obtaining an area under the curve (AUC) value ≥ 0.846, concluding that age can be used as tool for their preventive diagnosis
Environmentally friendly analysis of emerging contaminants by pressurized hot water extraction-stir bar sorptive extraction-derivatization and gas chromatography-mass spectrometry
This work describes the development, optimiza-
tion, and validation of a new method for the simultaneous
determination of a wide range of pharmaceuticals (beta-
blockers, lipid regulators
...
) and personal care products
(fragrances, UV filters, phthalates
...
) in both aqueous and
solid environmental matrices. Target compounds were
extracted from sediments using pressurized hot water ex-
traction followed by stir bar sorptive extraction. The first
stage was performed at 1,500 psi during three static extrac-
tion cycles of 5 min each after optimizing the extraction
temperature (50
–
150 °C) and addition of organic modifiers
(% methanol) to water, the extraction solvent. Next, aqueous
extracts and water samples were processed using polydime-
thylsiloxane bars. Several parameters were optimized for
this technique, including extraction and desorption time,
ionic strength, presence of organic modifiers, and pH. Fi-
nally, analytes were extracted from the bars by ultrasonic
irradiation using a reduced amount of solvent (0.2 mL) prior
to derivatization and gas chromatography
–
mass spectrome-
try analysis. The optimized protocol uses minimal amounts
of organic solvents (<10 mL/sample) and time (
≈
8 h/sam-
ple) compared to previous ex
isting methodologies. Low
standard deviation (usually below 10 %) and limits of de-
tection (sub-ppb) vouch for the applicability of the method-
ology for the analysis of target compounds at trace levels.
Once developed, the method was applied to determin
DESARROLLO CONCEPTUAL DE LA PROMOCIÓN DE LA SALUD EN LOS LUGARES DE TRABAJO
Introduction: Health promotion, from an integrated, intersection and interdisciplinary viewpoint, has been slowly developed in the workplace. The promotion of health in workplaces (PSHW) as a strategy is oriented towards contributing to the integrated attention to workers, involving all determining factors to optimize the health and safety conditions in the workplace involving workers, directors and the organization as a whole. Due to the complexity posed by structural processes, such as globalization and its effects on the working processes and life of people at current times, this strategy becomes a challenge to be implemented in several different labor settings. Objectives: To analyze the bibliography and documentary references in relation to health promotion in workplaces. Methodology: By means of a bibliographic revision, in scientific databases and sites related to the field of interest, the conceptual development of health in workplaces will be analyzed. Descriptors used for searching were the following: Promotion of health, work, and work environment. Results: The bibliographic search showed that the promotion of health in the workplace is a potentially integrating strategy, generating policies and actions of the organization leading to the enhancement of working conditions, as well as all other factors implied in workers‟ health status. Conclusions: Organizations nowadays should assure a balance between the compliance with their objectives and the needs of the health of workers, through an efficient PSHW program, with the objective of continuously improving their quality of life, which can be affected by changes in the labor setting as the result of new technologies and the nature of work. The application of strategies is limited, according to the revision made.Introducción: La promoción de la salud, desde su perspectiva integral, intersectorial e interdisciplinaria, se viene desarrollando tímidamente en los entornos del trabajo. La promoción de la salud en los lugares de trabajo-PSLT, como estrategia, se orienta a contribuir en la atención al trabajador de forma integral e involucrando todos los factores determinantes en la optimización de las condiciones de la salud y seguridad en los lugares de trabajo, implicando a los trabajadores, directivos y a la organización de manera integral. Ante la complejidad que involucra procesos estructurales como la globalización y sus efectos en los procesos de trabajo y vida de las personas en la actualidad, esta estrategia se convierte en un desafío por desarrollar en los diversos escenarios laborales. Objetivos: Analizar la producción bibliográfica y documental relacionada con la promoción de la salud en los lugares de trabajo. Metodología: Mediante revisión bibliográfica, en bases de datos científicas y en sites relacionados con el área, se analizará el desarrollo conceptual de la promoción de la salud en los lugares de trabajo. Los descriptores utilizados para la búsqueda fueron: promoción de la salud, trabajo, ambiente de trabajo. Resultados: La búsqueda bibliográfica mostró que la promoción de la salud en los lugares de trabajo es una estrategia potencial integradora, generadora de políticas y acciones de la organización, encaminadas a mejorar las condiciones de trabajo, y demás factores que intervienen en la salud de los trabajadores. Conclusiones: las organizaciones en la actualidad, deben garantizar un equilibrio entre el cumplimiento de sus objetivos y necesidades de salud de los trabajadores, mediante un programa eficaz de PSLT, con el objetivo de mejorar continuamente su calidad de vida, la cual se puede ver afectada por los cambios del entorno laboral debido a las nuevas tecnologías y la naturaleza del trabajo. La aplicación de la estrategia es limitada, de acuerdo a la revisión realizada
Engineering transketolase to accept both unnatural donor and acceptor substrates and produce α‐hydroxyketones
A narrow substrate range is a major limitation in exploiting enzymes more widely as catalysts in synthetic organic chemistry. For enzymes using two substrates, the simultaneous optimisation of both substrate specificities is also required for the rapid expansion of accepted substrates. Transketolase (TK) catalyses the reversible transfer of a C2‐ketol unit from a donor substrate to an aldehyde acceptor and suffers the limitation of narrow substrate scope for industrial applications. Herein, TK from Escherichia coli was engineered to accept both pyruvate, as a novel donor substrate, and unnatural acceptor aldehydes, including propanal, pentanal, hexanal and 3‐formylbenzoic acid (FBA). Twenty single‐mutant variants were first designed and characterised experimentally. Beneficial mutations were then recombined to construct a small library. Screening of this library identified the best variant with a 9.2‐fold improvement in the yield towards pyruvate and propionaldehyde, relative to wild‐type (WT). Pentanal and hexanal were used as acceptors to determine stereoselectivities of the reactions, which were found to be higher than 98% enantiomeric excess (ee) for the S configuration. Three variants were identified to be active for the reaction between pyruvate and 3‐FBA. The best variant was able to convert 47% of substrate into product within 24 h, whereas no conversion was observed for WT. Docking experiments suggested a cooperation between the mutations responsible for donor and acceptor recognition, which would promote the activity towards both the acceptor and donor. The variants obtained have the potential to be used for developing catalytic pathways to a diverse range of high‐value products
FUS-DDIT3 Prevents the Development of Adipocytic Precursors in Liposarcoma by Repressing PPARγ and C/EBPα and Activating eIF4E
FUS-DDIT3 is a chimeric protein generated by the most common chromosomal translocation t(12;16)(q13;p11) linked to liposarcomas, which are characterized by the accumulation of early adipocytic precursors. Current studies indicate that FUS-DDIT3- liposarcoma develops from uncommitted progenitors. However, the precise mechanism whereby FUS-DDIT3 contributes to the differentiation arrest remains to be elucidated. METHODOLOGY/PRINCIPAL FINDINGS: Here we have characterized the adipocyte regulatory protein network in liposarcomas of FUS-DITT3 transgenic mice and showed that PPARgamma2 and C/EBPalpha expression was altered. Consistent with in vivo data, FUS-DDIT3 MEFs and human liposarcoma cell lines showed a similar downregulation of both PPARgamma2 and C/EBPalpha expression. Complementation studies with PPARgamma but not C/EBPalpha rescued the differentiation block in committed adipocytic precursors expressing FUS-DDIT3. Our results further show that FUS-DDIT3 interferes with the control of initiation of translation by upregulation of the eukaryotic translation initiation factors eIF2 and eIF4E both in FUS-DDIT3 mice and human liposarcomas cell lines, explaining the shift towards the truncated p30 isoform of C/EBPalpha in liposarcomas. Suppression of the FUS-DDIT3 transgene did rescue this adipocyte differentiation block. Moreover, eIF4E was also strongly upregulated in normal adipose tissue of FUS-DDIT3 transgenic mice, suggesting that overexpression of eIF4E may be a primary event in the initiation of liposarcomas. Reporter assays showed FUS-DDIT3 is involved in the upregulation of eIF4E in liposarcomas and that both domains of the fusion protein are required for affecting eIF4E expression. CONCLUSIONS/SIGNIFICANCE: Taken together, this study provides evidence of the molecular mechanisms involve in the disruption of normal adipocyte differentiation program in liposarcoma harbouring the chimeric gene FUS-DDIT3.Research in ISG group is supported partially by FEDER and by MEC (SAF2006-03726), Junta de Castilla y León (CSI03A05), FIS (PI050087, PI050116), Fundación de Investigación MMA, Federación de Cajas de Ahorro Castilla y León (I Convocatoria de Ayudas para Proyectos de Investigación Biosanitaria con Células Madre), CDTEAM project (CENIT-Ingenio 2010) and MEC Consolider-Ingenio 2010 (Ref. CSD2007-0017).Research in ISG group is supported partially by FEDER and by MEC (SAF2006-03726 and PETRI N° 95-0913.OP), Junta de Castilla y León (CSI03A05), FIS (PI050087, PI050116), Fundación de Investigación MMA, Federación de Cajas de Ahorro Castilla y León (I Convocatoria de Ayudas para Proyectos de Investigación Biosanitaria con Células Madre), CDTEAM project (CENIT-Ingenio 2010) and MEC Consolider-Ingenio 2010 (Ref. CSD2007-0017). MSM is supported by the Ramon y Cajal Scientific Spanish Program, Fondo Investigacion Sanitaria (FIS PI04-1271), Junta de Castilla y León (SA085A06) and Fundación Manuel Solorzano, University of Salamanca.Peer reviewe
A new small-bodied azhdarchoid pterosaur from the Lower Cretaceous of England and its implications for pterosaur anatomy, diversity and phylogeny
BACKGROUND: Pterosaurs have been known from the Cretaceous sediments of the Isle of Wight (southern England, United Kingdom) since 1870. We describe the three-dimensional pelvic girdle and associated vertebrae of a small near-adult pterodactyloid from the Atherfield Clay Formation (lower Aptian, Lower Cretaceous). Despite acknowledged variation in the pterosaur pelvis, previous studies have not adequately sampled or incorporated pelvic characters into phylogenetic analyses. METHODOLOGY/PRINCIPAL FINDINGS: The new specimen represents the new taxon Vectidraco daisymorrisae gen. et sp. nov., diagnosed by the presence of a concavity posterodorsal to the acetabulum and the form of its postacetabular process on the ilium. Several characters suggest that Vectidraco belongs to Azhdarchoidea. We constructed a pelvis-only phylogenetic analysis to test whether the pterosaur pelvis carries a useful phylogenetic signal. Resolution in recovered trees was poor, but they approximately matched trees recovered from analyses of total evidence. We also added Vectidraco and our pelvic characters to an existing total-evidence matrix for pterosaurs. Both analyses recovered Vectidraco within Azhdarchoidea. CONCLUSIONS/ SIGNIFICANCE: The Lower Cretaceous strata of western Europe have yielded members of several pterosaur lineages, but Aptian pterosaurs from western Europe are rare. With a pelvis length of 40 mm, the new animal would have had a total length of c. 350 mm, and a wingspan of c. 750 mm. Barremian and Aptian pterodactyloids from western Europe show that small-bodied azhdarchoids lived alongside ornithocheirids and istiodactylids. This assemblage is similar in terms of which lineages are represented to the coeval beds of Liaoning, China; however, the number of species and specimens present at Liaoning is much higher. While the general phylogenetic composition of western European and Chinese communities appear to have been approximately similar, the differences may be due to different palaeoenvironmental and depositional settings. The western Europe pterodactyloid record may therefore be artificially low in diversity due to preservational factors
Construct and face validity of SINERGIA laparoscopic virtual reality simulator
Purpose
Laparoscopic techniques have nowadays become a gold standard in many surgical procedures, but they imply a more difficult learning skills process. Simulators have a fundamental role in the formative stage of new surgeons. This paper presents the construct and face validity of SINERGIA laparoscopic virtual reality simulator in order to decide whether it can be considered as an assessment tool.
Methods
Twenty people participated in this study, 14 were novices and 6 were experts. Five tasks of SINERGIA were included in the study: coordination, navigation, navigation and touch, precise grasping and coordinate traction. For each one of these tasks, a certain number of metrics are automatically recorded. All subjects accomplished each task only once and filled in two questionnaires. A statistical analysis was made and results from both groups were compared with the Mann–Whitney U-test, considering significant differences when P ≤ 0.05. Internal consistency of the system has been analyzed with the Cronbach’s alpha test.
Results
Novices and experts positively rated SINERGIA characteristics. At least one of the evaluated metrics of each exercise presented significant differences between both groups. Nevertheless, all metrics under study gave a better punctuation to the executions accomplished by experts (lower time, higher efficiency, fewer errors. . .) than to those made by novices.
Conclusion
SINERGIA laparoscopic virtual reality simulator is able to discriminate subjects according to their level of experience in laparoscopic surgery; therefore, it can be used within a training program as an assessment too
Updating known distribution models for forecasting climate change impact on endangered species
To plan endangered species conservation and to design adequate management programmes, it is necessary to predict their
distributional response to climate change, especially under the current situation of rapid change. However, these
predictions are customarily done by relating de novo the distribution of the species with climatic conditions with no regard
of previously available knowledge about the factors affecting the species distribution. We propose to take advantage of
known species distribution models, but proceeding to update them with the variables yielded by climatic models before
projecting them to the future. To exemplify our proposal, the availability of suitable habitat across Spain for the endangered
Bonelli’s Eagle (Aquila fasciata) was modelled by updating a pre-existing model based on current climate and topography to
a combination of different general circulation models and Special Report on Emissions Scenarios. Our results suggested that
the main threat for this endangered species would not be climate change, since all forecasting models show that its
distribution will be maintained and increased in mainland Spain for all the XXI century. We remark on the importance of
linking conservation biology with distribution modelling by updating existing models, frequently available for endangered
species, considering all the known factors conditioning the species’ distribution, instead of building new models that are
based on climate change variables only.Ministerio de Ciencia e Innovación and FEDER (project CGL2009-11316/BOS
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