Usable error message presentation in the World Wide Web: Do not show errors right away

Online form validation can be performed in several ways. This article discusses two empirical studies with 77 and 90 participants, which have found evidence that the best way of presenting error messages is to provide the erroneous fields after users have completed the whole form. Immediate error feedback recommended by the International Organization for Standardization (ISO) showed the worst performance in these studies. Where presented with immediate feedback, users often simply ignored the messages on the screen and continued completing the form as if nothing happened. These results lead to the postulation of the "Modal Theory of Form Completion”: Users are in either "Completion” or "Revision Mode” when filling out online forms. These modes affect the users' way of interaction with the system: During Completion Mode the users' disposition to correct mistakes is reduced, therefore error messages are often ignore

Quantitative dynamic modeling of transcriptional networks of embryonic stem cells using integrated framework of Pareto optimality and energy balance

Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 252-256).Embryonic Stem Cells (ESCs) are pluripotent and thus are considered the "cell type of choice". ESCs exhibit several phenotypic traits (e.g., proliferation, differentiation, apoptosis, necrosis, etc.) and when differentiated into a particular lineage they can perform an array of functions (e.g., protein secretion, detoxification, energy production). Typically, these cellular objectives compete against each other because of thermodynamic, stoichiometric and mass balance constraints. Analysis of transcriptional regulatory networks and metabolic networks in ESCs thus requires both a nonequilibrium thermodynamic and mass balance framework for designing and understanding complex ESC network approach as well as an optimality approach which can take cellular objectives into account simultaneously. The primary goal of this thesis was to develop an integrated energy and mass balance-based multi objective framework for a transcriptional regulatory network model for ESCs. The secondary goal was to utilize the developed framework for large-scale metabolic flux profiling of hepatic and ESC metabolic networks. Towards the first aim we first developed a complete dynamic pluripotent network model for ESCs which integrates several different master regulators of pluripotency such as transcription factors Oct4, Sox2, Nanog, Klf4, Nacl, Rexl, Daxl, cMyc, and Zfp281, and obtained the dynamic connectivity matrix between various pluripotency related gene promoters and transcription factors. The developed model fully describes the self-renewal state of embryonic stem cells.(cont.) Next, we developed a transcriptional network model framework for ESCs that incorporates multiobjective optimality-based energy balance analysis. This framework predicts cofactor occupancy, network architecture and feedback memory of ESCs based on energetic cost. The integrated nonequilibrium thermodynamics and multiobjective-optimality network analysis-based approach was further utilized to explain the significance of transcriptional motifs defined as small regulatory interaction patterns that regulate biological functions in highly interacting cellular networks. Our results yield evidence that dissipative energetics is the underlying criteria used during evolution for motif selection and that biological systems during transcription tend towards evolutionary selection of subgraphs which produces minimum specific heat dissipation, thereby explaining the frequency of some motifs. Significantly, the proposed energetic hypothesis uncovers a mechanism for environmental selection of motifs, provides explanation for topological generalization of subgraphs into complex networks and enables identification of new functionalities for rarely occurring motifs. Towards the secondary goal, we have developed a multiobjecive optimization-based approach that couples the normalized constraint with both energy and flux balance-based metabolic flux analysis to explain certain features of metabolic control of hepatocytes, which is relevant to the response of hepatocytes and liver to various physiological stimuli and disease states. We also utilized this approach to obtain an optimal regimen for ESC differentiation into hepatocytes.(cont.) The presented framework may establish multiobjective optimality-based thermodynamic analysis as a backbone in designing and understanding complex network systems, such as transcriptional, metabolic and protein interaction networks.by Marco A. Avila.Ph.D

Efecto de diferentes niveles de proteína en dietas para pollos de engorda

Se llevaron a cabo tres experimentos con pollos de engorda de 1-9 semanas de edad con objeto de estudiar el efecto de diferentes niveles de proteína sobre la ganancia de peso y la eficiencia alimenticia. Los resultados en el experimento l indicaron que es factible en dietas sorgo + soya suplementadas con metionína reducir el nivel de proteína para la fase de iniciación (23 a 20%) y en la fase de finalización (20 a 18%) sin que sea necesaria la suplementación adicional a las dietas con los aminoácidos lisina y metionina. Los datos en el experimento 2 mostraron que durante la iniciación es factible reducir la proteína a 18% en dietas sorgo + soya suplementadas con metionina; durante la fase de finalización dietas con 16% suplementadas o no con lisina y metionina afectan negativamente (P 0.05) de la ganancia de peso o la eficiencia alimenticia

Mesoscopic 3D Charge Transport in Solution-Processed Graphene-Based Thin Films: A Multiscale Analysis

Graphene and related 2D material (GRM) thin films consist of 3D assembly of billions of 2D nanosheets randomly distributed and interacting via van der Waals forces. Their complexity and the multiscale nature yield a wide variety of electrical characteristics ranging from doped semiconductor to glassy metals depending on the crystalline quality of the nanosheets, their specific structural organization ant the operating temperature. Here, the charge transport (CT) mechanisms are studied that are occurring in GRM thin films near the metal-insulator transition (MIT) highlighting the role of defect density and local arrangement of the nanosheets. Two prototypical nanosheet types are compared, i.e., 2D reduced graphene oxide and few-layer-thick electrochemically exfoliated graphene flakes, forming thin films with comparable composition, morphology and room temperature conductivity, but different defect density and crystallinity. By investigating their structure, morphology, and the dependence of their electrical conductivity on temperature, noise and magnetic-field, a general model is developed describing the multiscale nature of CT in GRM thin films in terms of hopping among mesoscopic bricks, i.e., grains. The results suggest a general approach to describe disordered van der Waals thin films

Composición química del aceite esencial de las hojas de Cymbopogon nardus y Cymbopogon citratus

El aceite esencial de hojas de Cymbopogon nardus y Cymbopogon citratus fue obtenido por destilación por arrastre con vapor de agua y analizado por cromatografía de gases de alta resolución (CGAR) y cromatografía de gases de alta resolución acoplado a espectrometría de masas (CGAR-EM) la composición química del aceite esencial de las partes aéreas de Citronela (Cymbopogon nardus) y Limoncillo (Cymbopogon citratus) cultivados en Caquetá. En el aceite esencial de C. nardus predominó citronelal (26%), geraniol (14%), elemol (9.9%), germacreno D-4-ol (6.5), citronelol (6.1%) y acetato de geranilo (5.6%), mientras que en el de C. citratos predominó geranial (49.7%), neral (30.5%) y â-mirceno (12.2%). El aceite esencial de C. citratus es menos denso y más ácido que el de C. nardus, en tanto que ambos aceites son dextro-rotatorios. De otro lado, se registran los espectros IR y UV de ambos aceites esenciales

Maternal-fetal complications in patients suffering from Turner syndrome: A report of two cases with oocyte donation

El Síndrome de Turner (ST) es la patología más frecuente que compromete los cromosomas sexuales, es causada por la ausencia completa o parcial del cromosoma X. Las implicaciones reproductivas de estos pacientes que se constituyen en infertilidad por una falla ovárica prematura y disgenesia gonadal, sugieren que el manejo indicado es la donación de óvulos asociada con la generación de embriones in vitro y su posterior transferencia, previa preparación endometrial. En este artículo se informan dos casos de ST manejados con ovodonación y sus implicaciones clínicas en el embarazo: Desproporción cefalo-pélvica por talla baja, complicaciones cardiovasculares que generan linfedema, lesiones aórticas y preeclampsia.Turner’s syndrome (TS) is the most frequent pathology compromising the sexual chromosomes, being caused by the complete or partial absence of chromosome X. The reproductive implications for these patients (i.e. infertility caused by early ovarian failure and gonad disgenesis) have suggested that the indicated management for this condition lies in anonymous ovodonation, followed by embryos being produced in vitro and their subsequent transfer, after suitable endometrial preparation. This article reports oocyte donation to two patients suffering from TS and their clinical implications for pregnancy: cephalo-pelvic imbalance due to small maternal size and cardiovascular complications producing lymphoedema, aortic dissection and preeclampsy

Effect of cover crop on carbon distribution in size and density separated soil aggregates

Increasing soil organic carbon (SOC) stocks in agricultural soils can contribute to stabilizing or even lowering atmospheric greenhouse gas (GHG) concentrations. Cover crop rotation has been shown to increase SOC and provide productivity benefits for agriculture. Here we used a split field design to evaluate the short-term effect of cover crop on SOC distribution and chemistry using a combination of bulk, isotopic, and spectroscopic analyses of size-and density-separated soil aggregates. Macroaggregates (\u3e250 µm) incorporated additional plant material with cover crop as evidenced by more negative δ13C values (−25.4%∘ with cover crop compared to −25.1%∘without cover crop) and increased phenolic (plant-like) resonance in carbon NEXAFS spectra. Iron EXAFS data showed that the Fe pool was composed of 17–21% Fe oxide with the remainder a mix of primary and secondary minerals. Comparison of oxalate and dithionite extractions suggests that cover crop may also increase Fe oxide crystallinity, especially in the dense (\u3e2.4 g cm−3) soil fraction. Cover crop δ13C values were more negative across density fractions of bulk soil, indicating the presence of less processed organic carbon. Although no significant difference was observed in bulk SOC on a mass per mass basis between cover and no cover crop fields after one season, isotopic and spectroscopic data reveal enhanced carbon movement between aggregates in cover crop soil

Clinical relevance of biomarkers in cholangiocarcinoma: critical revision and future directions

Cholangiocarcinoma (CCA) is a malignant tumour arising from the biliary system. In Europe, this tumour frequently presents as a sporadic cancer in patients without defined risk factors and is usually diagnosed at advanced stages with a consequent poor prognosis. Therefore, the identification of biomarkers represents an utmost need for patients with CCA. Numerous studies proposed a wide spectrum of biomarkers at tissue and molecular levels. With the present paper, a multidisciplinary group of experts within the European Network for the Study of Cholangiocarcinoma discusses the clinical role of tissue biomarkers and provides a selection based on their current relevance and potential applications in the framework of CCA. Recent advances are proposed by dividing biomarkers based on their potential role in diagnosis, prognosis and therapy response. Limitations of current biomarkers are also identified, together with specific promising areas (ie, artificial intelligence, patient-derived organoids, targeted therapy) where research should be focused to develop future biomarkers