513 research outputs found
Strategic motivators and expected benefits from e-Commerce in traditional organisations
This paper aims to identify the strategic motivators and expected benefits related to the implementation of e-commerce infrastructures in traditional “brick and mortar” organisations. Despite the fact that the clearest benefit from e-commerce might be expected to come from contribution to corporate profits, either from an increase of sales or reduction of costs, but this may not be the case. The literature suggests that there are different ways in which the potential benefits can be assessed. These ways are directly related to the evolution of e-commerce. This research has chosen six representative organisations from different sectors to explore their rationales for their e-commerce strategies. One of the main benefits reported is to increase the focus on the customer and improving internal communications. Additionally, obtaining competitive advantage was found to be a powerful motivator, despite the fact that the recent academic literature suggests that this is very difficult to achieve
CD30-positive primary cutaneous lymphoproliferative disorders: molecular alterations and targeted therapies
Primary cutaneous CD30-positive T-cell lymphoproliferative disorders are the second most common subgroup of cutaneous T-cell lymphomas. They include two clinically different entities with some overlapping features and borderline cases: lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Molecular studies of primary cutaneous anaplastic large cell lymphoma reveal an increasing level of heterogeneity that is associated with histological and immunophenotypic features of the cases and their response to specific therapies. Here, we review the most significant genetic, epigenetic and molecular alterations described to date in primary cutaneous CD30-positive T-cell lymphoproliferative disorders, and their potential as therapeutic targets
Primary Involvement of Pharynx and Peyer's Patch in Inhalational and Intestinal Anthrax
Bacillus anthracis causes three forms of anthrax: inhalational, gastrointestinal, and cutaneous. Anthrax is characterized by both toxemia, which is caused by secretion of immunomodulating toxins (lethal toxin and edema toxin), and septicemia, which is associated with bacterial encapsulation. Here we report that, contrary to the current view of B. anthracis pathogenesis, B. anthracis spores germinate and establish infections at the initial site of inoculation in both inhalational and cutaneous infections without needing to be transported to draining lymph nodes, and that inhaled spores establish initial infection in nasal-associated lymphoid tissues. Furthermore, we found that Peyer's patches in the mouse intestine are the primary site of bacterial growth after intragastric inoculation, thus establishing an animal model of gastrointestinal anthrax. All routes of infection progressed to the draining lymph nodes, spleen, lungs, and ultimately the blood. These discoveries were made possible through the development of a novel dynamic mouse model of B. anthracis infection using bioluminescent non-toxinogenic capsulated bacteria that can be visualized within the mouse in real-time, and demonstrate the value of in vivo imaging in the analysis of B. anthracis infection. Our data imply that previously unrecognized portals of bacterial entry demand more intensive investigation, and will significantly transform the current perception of inhalational, gastrointestinal, and cutaneous B. anthracis pathogenesis
Memória de som de piano em formato de rolo: a coleção Hazen
The Hazen family's collection of 489 piano rolls is a magnificent example of preservation and maintenance of the sound memory of a time not so long ago. At the end of the 19th and beginning of the 20th century, autopianos, pianolas and electric pianos began to become popular and burst into many bourgeois homes in Europe and America. Hazen, the main seller, and distributor of pianos in Spain, began with the sale and marketing of these instruments and the repertoire for their execution: the piano rolls. All kinds of melodies were recorded on these media, with Beethoven's Symphonies being some of the most common titles in the present collection. Although Hazen supplied piano rolls of all kinds and styles, especially relevant were those that made up the catalog of Victoria and Best, a subsidiary of the former for sale and export to Latin America, with a repertoire more suited to those latitudes. Currently, both libraries of certain importance and private owners of this type of media are focusing their efforts on the digitization of these materials for a better preservation of the documentary musical heritage and for its dissemination through new devices.La colección de rollos de pianola de la familia Hazen, compuesta por 489 ejemplares, es un magnífico ejemplo de conservación y mantenimiento de la memoria sonora de un tiempo no tan lejano. A finales del XIX y principios del XX, comenzaron a popularizarse los autopianos, las pianolas y los pianos eléctricos que irrumpieron en muchos hogares burgueses de Europa y América. La casa Hazen, principal vendedora y distribuidora de pianos en España, empezó con la venta y comercialización de estos instrumentos y también del repertorio para su ejecución: los rollos de pianola. Todo tipo de melodías fueron grabadas en estos soportes siendo las Sinfonías de Beethoven algunos de los títulos más presentes en la colección que nos ocupa. Aunque la casa Hazen suministró con las pianolas rollos de toda clase y estilo, fueron especialmente relevantes los que conformaban el catálogo de la casa Victoria y también de Best, filial de la primera para su venta y exportación a Latinoamérica, con un repertorio más adecuado a esas latitudes. Actualmente, tanto las bibliotecas de cierta importancia como los poseedores particulares de este tipo de soportes, están enfocando sus esfuerzos hacia la digitalización de estos materiales para una mejor conservación del patrimonio musical documental y para la difusión del mismo a través de nuevos dispositivos.A coleção de rolos de piano da família Hazen, composta por 489 exemplares, é um magnífico exemplo de conservação e manutenção da memória sonora de tempos não tão distantes. No final do século 19 e início do século 20, os autopianos, pianos e pianos elétricos começaram a se tornar populares, explodindo em muitos lares burgueses na Europa e na América. A casa Hazen, principal vendedora e distribuidora de pianos em Espanha, começou com a venda e comercialização destes instrumentos e também do repertório para a sua execução: rolos de pianola. Todos os tipos de melodias foram gravadas nesses suportes, sendo as Sinfonias de Beethoven alguns dos títulos mais presentes na coleção em mãos. Embora a casa Hazen fornecesse rolos de todos os tipos e estilos com os pianos de mesa, aqueles que compunham o catálogo da casa Victoria e também da Best, subsidiária da primeira para venda e exportação para a América Latina, com um repertório mais adequado para essas latitudes. Atualmente, tanto as bibliotecas de alguma importância quanto os proprietários particulares desse tipo de mídia estão concentrando seus esforços na digitalização desses materiais para melhor preservação do patrimônio musical documental e para sua divulgação por meio de novos dispositivos
Modulation strategy to minimize the reactive power in the AC-link of isolated three-port DC-DC converters
[EN] The isolated three-port DC-DC converter is of interest for hybrid energy storage systems due to its advantages of the bidirectional power flow control, step-up and step-down the voltage, and the operation under soft-switching mode. The conventional control of the power flow is carried out using a phase-shift between the voltages at the transformer terminals, which can generate high reactive power due to circulating current on the AC-link of the converter, and high efficiencies only in a limited operating range. To increase the performance over the whole operating range, this work proposes a modulation strategy that extends the soft-switching region and minimizes reactive power. This strategy applies a pulse width on the higher voltage DC port, maintaining traditional square wave modulation on the opposite port. To validate the strategy, results are presented for different power transfer scenarios.[ES] El convertidor CC-CC de tres puertos aislados es de interés para los sistemas de almacenamiento de energía híbridos por su capacidad para controlar los flujos de energía de manera bidireccional, aumentar y disminuir la tensión y la operación con conmutación suave. El control convencional del flujo de energía se realiza aplicando un desfase entre las tensiones a bornes del transformador, lo que puede generar una elevada potencia reactiva debida a la corriente de circulación en el enlace de CA del convertidor, consiguiéndose rendimientos elevados sólo en un rango de operación limitado. Para aumentar el rendimiento en todo el rango de operación, este trabajo propone una estrategia de modulación que extiende la región de conmutación suave y minimiza la potencia reactiva. Esta estrategia aplica un ancho de pulso en el puerto de mayor tensión de CC, manteniendo la modulación tradicional de onda cuadrada en el puerto opuesto. Para validar la estrategia, se presentan resultados para diferentes escenarios de transferencia de potencia.Este trabajo fue soportado por la Secretaría de Ciencia y Técnica de la Universidad Nacional de Río Cuarto, Argentina (SeCyT, UNRC), la Agencia Nacional de Promoción Científica y Tecnológica (FONCyT, Argentina), la Red MEIHAPER CYTED y el proyecto PIN 04/I240 de la Universidad Nacional del Comahue.Troviano, M.; Piris-Botalla, LE.; Oggier, G. (2021). Estrategia de modulación para minimizar la potencia reactiva en el enlace de CA de convertidores CC-CC de tres puertos aislados. Revista Iberoamericana de Automática e Informática industrial. 18(4):347-359. https://doi.org/10.4995/riai.2021.14612OJS347359184Bai, H., Mi, C., 2008. Eliminate reactive power and increase system efficiency of isolated bidirectional dual-active-bridge dc-dc converters using novel dual-phase-shift control. IEEE Transactions on Power Electronics 23 (6), 2905-2914. https://doi.org/10.1109/TPEL.2008.2005103Biswas, I., Kastha, D., Bajpai, P., 2021. Small signal modeling and decoupled controller design for a triple active bridge multiport dc-dc converter. IEEE Transactions on Power Electronics 36 (2), 1856-1869. https://doi.org/10.1109/TPEL.2020.3006782Chien, L.-J., Chen, C.-C., Chen, J.-F., Hsieh, Y.-P., 2014. Novel three-port converter with high-voltage gain. IEEE Transactions on Power Electronics 29 (9), 4693-4703. https://doi.org/10.1109/TPEL.2013.2285477Choi, M.-E., Kim, S.-W., Seo, S.-W., 2012. Energy management optimization in a battery/supercapacitor hybrid energy storage system. IEEE Transactions on Smart Grid 3 (1), 463-472. https://doi.org/10.1109/TSG.2011.2164816De Doncker, R., D.M., D., M.H., K., 1991. A threephase soft-switched highpowerdensity dc/dc converter for high-power applications. IEEE Transactions on Industry Applications 27 (1), 63 -73. https://doi.org/10.1109/28.67533Duarte, J., Hendrix, M., Simoes, M., 2007. Three-port bidirectional converter for hybrid fuel cell systems. IEEE Transactions on Power Electronics 22 (2), 480 -487. https://doi.org/10.1109/TPEL.2006.889928Hajiaghasi, S., Salemnia, A., Hamzeh, M., 2019. Hybrid energy storage system for microgids applications: A review. Journal of Energy Storage 21, 543-570. https://doi.org/10.1016/j.est.2018.12.017Kim, S. Y., Song, H.-S., Nam, K., 2012. Idling port isolation control of threeport bidirectional converter for evs. IEEE Transactions on Power Electronics 27 (5), 2495 -2506. https://doi.org/10.1109/TPEL.2011.2172225McDonough, M., 2015. Integration of inductively coupled power transfer and hybrid energy storage system: A multiport power electronics interface for battery-powered electric vehicles. IEEE Transactions on Power Electronics 30 (11), 6423-6433. https://doi.org/10.1109/TPEL.2015.2422300Mendis, N., Muttaqi, K., Perera, S., 2014. Management of battery-supercapacitor hybrid energy storage and synchronous condenser for isolated operation of pmsg based variable-speed wind turbine generating systems. IEEE Transactions on Smart Grid 5 (2), 944-953. https://doi.org/10.1109/TSG.2013.2287874Nguyen, D., Fujita, G., Ta, M. C., 2017. A new soft-switching strategy for three-port converter to be applied in ev application. In: 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia). pp. 1126-1131. https://doi.org/10.1109/IFEEC.2017.7992199Oggier, G., Garcia, G., Oliva, A., 2009. Switching control strategy to minimize dual active bridge converter losses. IEEE Transactions on Power Electronics 24 (7), 1826 -1838. https://doi.org/10.1109/TPEL.2009.2020902Oggier, G., Garcia, G., Oliva, A., 2011. Modulation strategy to operate the dual active bridge dc-dc converter under soft switching in the whole operating range. IEEE Transactions on Power Electronics 26 (4), 1228-1236. https://doi.org/10.1109/TPEL.2010.2072966Oggier, G., Garcia, G., Oliva, A., 2013. Analysis of the influence of switching related parameters in the dab converter under soft-switching. Latin American Applied Research 43 (2), 121-129.Oggier, G., Piris-Botalla, L. E., Garcia, G., 2010. Soft-switching analysis for three-port bidirectional dc-dc converters. In: Industry Applications Conference. INDUSCON 9th IEEE/IAS. pp. 1-6. https://doi.org/10.1109/INDUSCON.2010.5740014Piris-Botalla, L., Oggier, G., Airabella, A., Garcia, G., 2012. Analysis and evaluation of power switch losses for three-port bidirectional dc-dc converter. In: International Conference on Industrial Technology (ICIT), 2012 IEEE. pp. 950-955. https://doi.org/10.1109/ICIT.2012.6210061Piris-Botalla, L., Oggier, G., Airabella, A., Garcia, G., 2013. Power losses evaluation of a bidirectional three-port dc-dc converter for hybrid electric system. International Journal of Electrical Power and Energy Systems (58), 1-8. https://doi.org/10.1016/j.ijepes.2013.12.021Piris Botalla, L., Oggier, G., Garrido, D., Garcia, G., 2016. Auxiliary inductances design of a bidirectional three-port dc-dc converter. IEEE Latin America Transactions 14 (6), 2582-2587. https://doi.org/10.1109/TLA.2016.7555222Piris-Botalla, L., Oggier, G. G., Airabella, A. M., García, G. O., 2016. Extending the soft-switching operating range of a bidirectional three-port dc-dc converter. Revista Iberoamericana de Autom'atica e Inform'atica Industrial 13 (1), 127-134. https://doi.org/10.1016/j.riai.2015.04.007Piris-Botalla, L., Oggier, G. G., Garcia, G. O., 2017. Extending the power transfer capability of a three-port dc-dc converter for hybrid energy storage systems. IET Power Electronics 10 (13), 1687-1697. https://doi.org/10.1049/iet-pel.2016.0422Purgat, P., Bandyopadhyay, S., Qin, Z., Bauer, P. G., 2020. Zero voltage switching criteria of triple active bridge converter. IEEE Transactions on Power Electronics, 1-1. https://doi.org/10.1109/TPEL.2020.3027785Saadatizadeh, Z., Babaei, E., Blaabjerg, F., Cecati, C., 2021. Three-port high step-up and high step-down dc-dc converter with zero input current ripple. IEEE Transactions on Power Electronics 36 (2), 1804-1813. https://doi.org/10.1109/TPEL.2020.3007959Sharma, A., Sharma, S., 2019. Review of power electronics in vehicle-to-grid systems. Journal of Energy Storage 21, 337-361. https://doi.org/10.1016/j.est.2018.11.022Sun, Y., Pei, W., Jia, D., Zhang, G., Wang, H., Zhao, L., Feng, Z., 2020. Application of integrated energy storage system in wind power fluctuation mitigation. Journal of Energy Storage 32 (101835). https://doi.org/10.1016/j.est.2020.101835Tao, H., Duarte, J., Hendrix, M., 2008a. Three-port triple-half-bridge bidirectional converter with zero-voltage switching. IEEE Transactions on Power Electronics 23 (2), 782 -792. https://doi.org/10.1109/TPEL.2007.915023Tao, H., Kotsopoulos, A., Duarte, J., Hendrix, M., 2008b. Transformer-coupled multiport zvs bidirectional dc-dc converter with wide input range. IEEE Transaction on Power Electronics 23, 771-781. https://doi.org/10.1109/TPEL.2007.915129Wang, L., Wang, Z., Li, H., 2012. Asymmetrical duty cycle control and decoupled power flow design of a three-port bidirectional dc-dc converter for fuel cell vehicle application. IEEE Transactions on Power Electronics 27 (2), 891-904. https://doi.org/10.1109/TPEL.2011.2160405Wu, H., Sun, K., Ding, S., Xing, Y., 2013. Topology derivation of nonisolated three-port dc-dc converters from dic and doc. IEEE Transactions on Power Electronics 28 (7), 3297-3307. https://doi.org/10.1109/TPEL.2012.2221746Wu, Y., Mahmud, M. H., Christian, S., Fantino, R. A., Gomez, R. A., Zhao, Y., Balda, J. C., 2020. A 150-kw 99% efficient all silicon carbide triple-active-bridge converter for solar-plus-storage systems. IEEE Journal of Emerging and Selected Topics in Power Electronics, 1-1. https://doi.org/10.1109/JESTPE.2020.3044572Ye, Y., Nian, H., Kong, L., Zheng, D., 2019. Efficiency optimization strategy of three port triple active bridge dc-dc converter. In: 2019 22nd International Conference on Electrical Machines and Systems (ICEMS). pp. 1-6. https://doi.org/10.1109/ICEMS.2019.8921669Zhao, C., Round, S., J.W., K., 2008. An isolated three-port bidirectional dc-dc converter with decoupled power flow management. IEEE Transactions on Power Electronics 23 (5), 2443 -2453. https://doi.org/10.1109/TPEL.2008.2002056Zhou, H., Bhattacharya, T., Tran, D., Siew, T., Khambadkone, A., 2011. Composite energy storage system involving battery and ultracapacitor with dynamic energy management in microgrid applications. IEEE Transactions on Power Electronics 26 (3), 923-930. https://doi.org/10.1109/TPEL.2010.209504
AUTOESTIMA EN ESTUDIANTES DE MEDICINA DE LA UNIVERSIDAD NACIONAL DE ASUNCION, PARAGUAY
Introducción: Autoestima puede ser definida como el desarrollo de la convicción de que uno es competente para vivir y merece la felicidad, es por tanto capaz de enfrentar la vida con confianza, benevolencia y optimismo lo cual ayuda a alcanzar las metas. Materiales y método: Fue un estudio observacional descriptivo con corte transverso con muestreo no probabilístico de casos consecutivos que se realizó de mayo a junio del 2016 a estudiantes de medicina de la Universidad Nacional de Asunción. Se incluyó a todos los estudiantes que aceptaron participar voluntariamente. Resultados: Se incluyó a 75 sujetos. 60% fue del sexo femenino con edades comprendidas entre 18 y 28 años y una media de 22±2 años. El 48% presenta autoestima elevada, el 18,7% autoestima baja y el 33,3% autoestima baja. Discusión: La prevalencia de autoestima baja en nuestro estudio fue mayor a la encontrada en una población similar donde el 24,5% mostraba puntajes acordes a baja autoestima en contraste con el 33,3% de nuestro estudio. Estos resultados pueden ser explicados por las altas prevalencias de ansiedad, depresión, estresores psicosociales y estrés académico propios de esta población
Molecular analysis of pancreatic cystic neoplasm in routine clinical practice
BACKGROUND
Cystic pancreatic lesions consist of a wide variety of lesions that are becoming
increasingly diagnosed with the growing use of imaging techniques. Of these,
mucinous cysts are especially relevant due to their risk of malignancy. However,
morphological findings are often suboptimal for their differentiation. Endoscopic
ultrasound fine-needle aspiration (EUS-FNA) with molecular analysis has been
suggested to improve the diagnosis of pancreatic cysts.
AIM
To determine the impact of molecular analysis on the detection of mucinous cysts
and malignancy.
METHODS
An 18-month prospective observational study of consecutive patients with
pancreatic cystic lesions and an indication for EUS-FNA following European
clinical practice guidelines was conducted. These cysts included those > 15 mm
with unclear diagnosis, and a change in follow-up or with concerning features in
which results might change clinical management. EUS-FNA with cytological,
biochemical and glucose and molecular analyses with next-generation sequencing
were performed in 36 pancreatic cysts. The cysts were classified as mucinous and
non-mucinous by the combination of morphological, cytological and biochemical
analyses when surgery was not performed. Malignancy was defined as cytology
positive for malignancy, high-grade dysplasia or invasive carcinoma on surgical
specimen, clinical or morphological progression, metastasis or death related to
neoplastic complications during the 6-mo follow-up period. Next-generation
sequencing results were compared for cyst type and malignancy.
RESULTS
Of the 36 lesions included, 28 (82.4%) were classified as mucinous and 6 (17.6%) as
non-mucinous. Furthermore, 5 (13.9%) lesions were classified as malignant. The
amount of deoxyribonucleic acid obtained was sufficient for molecular analysis in
25 (69.4%) pancreatic cysts. The amount of intracystic deoxyribonucleic acid was
not statistically related to the cyst fluid volume obtained from the lesions.
Analysis of KRAS and/or GNAS showed 83.33% [95% confidence interval (CI):
63.34-100] sensitivity, 60% (95%CI: 7.06-100) specificity, 88.24% (95%CI: 69.98-100)
positive predictive value and 50% (95%CI: 1.66-98.34) negative predictive value (P
= 0.086) for the diagnosis of mucinous cystic lesions. Mutations in KRAS and
GNAS were found in 2/5 (40%) of the lesions classified as non-mucinous, thus
recategorizing those lesions as mucinous neoplasms, which would have led to a
modification of the follow-up plan in 8% of the cysts in which molecular analysis
was successfully performed. All 4 (100%) malignant cysts in which molecular
analysis could be performed had mutations in KRAS and/or GNAS, although they
were not related to malignancy (P > 0.05). None of the other mutations analyzed
could detect mucinous or malignant cysts with statistical significance (P > 0.05).
CONCLUSION
Molecular analysis can improve the classification of pancreatic cysts as mucinous
or non-mucinous. Mutations were not able to detect malignant lesion
Organizational perceptions of e-commerce: Re-assessing the benefits
This paper reports on preliminary findings from a wider and more in-depth study of six traditional organizations from different sectors that have successfully introduced e-commerce initiatives. The research adopted a case study approach, within which a questionnaire, identifying 16 generic benefits synthesized from the literature, was administered. The organizations were also asked to characterize whether e-commerce was strategic for them or not. The findings suggest that those organizations that perceived e-commerce to be strategic tended to consider intangible benefits as more important than tangible benefits, indicating perhaps a move away from the traditional view of e-commerce as a marketing driver to increase or create sales. Those organizations perceiving e-commerce as non-strategic rated the tangible benefits in much the same way as the strategic organizations, but rated the intangibles lower. Also it was found that e-commerce was important as a communication tool, not only with customers, as might be expected, but also with staff within the organization. The value of intra-organizational e-commerce was also found to be important, perhaps more than previously thought, as was its use in communicating and disseminating knowledge. The findings also reflect the importance of the sector and environment of the organization in determining their perceptions of e-commerce
Testing one-body density functionals on a solvable model
There are several physically motivated density matrix functionals in the
literature, built from the knowledge of the natural orbitals and the occupation
numbers of the one-body reduced density matrix. With the help of the equivalent
phase-space formalism, we thoroughly test some of the most popular of those
functionals on a completely solvable model.Comment: Latex, 16 pages, 4 figure
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