A study to determine the effectiveness of cleanliness measures by mothers in preparation for handling of feeding their infants

Thesis (M.S.)--Boston Universit

Optically pumped 1.3 μm room-temperature InAs quantum-dot micro-disk lasers directly grown on (001) silicon

Direct integration of high-performance laser diodes on silicon will dramatically transform the world of photonics, expediting the progress toward low-cost and compact photonic integrated circuits (PICs) on the mainstream silicon platform. Here, we report, to the best of our knowledge, the first 1.3 μm room-temperature continuous-wave InAs quantum-dot micro-disk lasers epitaxially grown on industrial-compatible Si (001) substrates without offcut. The lasing threshold is as low as hundreds of microwatts, similar to the thresholds of identical lasers grown on a GaAs substrate. The heteroepitaxial structure employed here does not require the use of an absorptive germanium buffer and/or dislocation filter layers, both of which impede the efficient coupling of light from the laser active regions to silicon waveguides. This allows for full compatibility with the extensive silicon-on-insulator (SOI) technology. The large-area virtual GaAs (on Si) substrates can be directly adopted in various mature in-plane laser configurations, both optically and electrically. Thus, this demonstration represents a major advancement toward the commercial success of fully integrated silicon photonics

1.3-μm InAs quantum-dot micro-disk lasers on V-groove patterned and unpatterned (001) silicon

We report comparison of lasing dynamics in InAs quantum dot (QD) micro-disk lasers (MDLs) monolithically grown on V-groove patterned and planar Si (001) substrates. TEM characterizations reveal abrupt interfaces and reduced threading dislocations in the QD active regions when using the GaAs-on-V-grooved-Si template. The improved crystalline quality translates into lower threshold power in the optically pumped continuous-wave MDLs. Concurrent evaluations were also made with devices fabricated simultaneously on lattice-matched GaAs substrates. Lasing behaviors from 10 K up to room temperature have been studied systematically. The analyses spotlight insights into the optimal epitaxial scheme to achieve low-threshold lasing in telecommunication wavelengths on exact Si (001) substrates

Plan estratégico de marketing de precios y canales de los Juegos Panamericanos 2019

Los Juegos Panamericanos es uno de los eventos deportivos más importantes del mundo, pues convoca a más de 6000 deportistas, y captura la atención de más de un millón de personas. Durante el 2019, este evento se desarrollará en la ciudad de Lima, constituyendo un reto para el país, tanto a nivel socioeconómico como deportivo. En ese sentido, la presente tesis propone una estrategia de precios y canales que busca no solo maximizar la venta de entradas disponibles, sino también asegurar la asistencia del público de todos los estratos sociales y edades. Se propone una estrategia de valor compartido, donde la política de precios aparte de tomar en cuenta el aspecto transaccional de la venta de entradas, también considera el componente de las relaciones con el público; dado que las entradas constituyen un elemento visible con los espectadores. Para la elaboración de la estrategia, se definieron rangos de precios iniciales tomando como referencia la información de la industria de entretenimiento y eventos similares como las Olimpiadas de Londres 2012 y los Juegos Panamericanos Toronto 2015. Seguidamente, se contrastaron los rangos con la disposición a pagar de los potenciales espectadores, mediante el estudio cuantitativo Bus Express Ipsos. Finalmente, se ajustaron los rangos analizando la distribución de las zonas de cada recinto asignado para el desarrollo del evento. En base a lo anterior, la tesis propone precios diferenciados para la inauguración (de S/ 60 a S/ 480) y clausura del evento (de S/ 30 a S/ 240); asimismo, precios diferenciados por preferencias deportivas de parte de los potenciales espectadores (tres planes con escalas de precios de S/20 a S/ 240), por rango de edades (precio a pagar equivalente a la edad, para el público de 12 a 18 años; y tarifas preferenciales para adultos mayores y niños) y por fases de las competencias (mayores precios en la fase final). Con relación a los puntos de venta, se propone los canales online y físico para asegurar la cobertura al público potencial.The Pan American Games is one of the most important sporting events in the world, as it attracts more than 6000 athletes, and captures the attention of more than one million people. During 2019, this event will take place in the city of Lima, constituting a challenge for the country, both at the socioeconomic and sports levels. In this sense, this thesis proposes a price and channel strategy that seeks not only to maximize the sale of available tickets, but also to ensure the attendance of the public of all social strata and ages. A strategy of shared value is proposed, where the pricing policy, apart from taking into account the transactional aspect of ticket sales, also considers the component of relations with the public; since the entrances constitute a visible element with the spectators. For the elaboration of the strategy, initial price ranges were defined taking as reference information from the entertainment industry and similar events such as the London 2012 Olympics and the Toronto 2015 Pan American Games. Next, the ranges were contrasted with the willingness to pay of the potential spectators, through the quantitative study Bus Express Ipsos. Finally, the ranges were adjusted by analyzing the distribution of the zones of each enclosure assigned for the development of the event. Based on the above, the thesis proposes differentiated prices for the inauguration (from S / 60 to S / 480) and closing of the event (from S / 30 to S / 240); also, prices differentiated by sports preferences from potential spectators (three plans with price scales from S / 20 to S / 240), by age range (price to pay equivalent to age, for the public from 12 to 18) years, and preferential rates for seniors and children) and by phases of the competitions (higher prices in the final phase). Regarding the points of sale, online and physical channels are proposed to ensure coverage to the potential public.Tesi

1.3 μm submilliamp threshold quantum dot micro-lasers on Si

As a promising integration platform, silicon photonics need on-chip laser sources that dramatically improve capability, while trimming size and power dissipation in a cost-effective way for volume manufacturability. Currently, direct heteroepitaxial growth of III–V laser structures on Si using quantum dots as the active region is a vibrant field of research, with the potential to demonstrate low-cost, high-yield, long-lifetime, and high-temperature devices. Ongoing work is being conducted to reduce the power consumption, maximize the operating temperature, and switch from miscut Si substrates toward the so-called exact (001) Si substrates that are standard in microelectronics fabrication. Here, we demonstrate record-small electrically pumped micro-lasers epitaxially grown on industry standard (001) silicon substrates. Continuous-wave lasing up to 100°C was demonstrated at 1.3 μm communication wavelength. A submilliamp threshold of 0.6 mA was achieved for a micro-laser with a radius of 5 μm. The thresholds and footprints are orders of magnitude smaller than those previously reported lasers epitaxially grown on Si

Temperature characteristics of epitaxially grown InAs quantum dot micro-disk lasers on silicon for on-chip light sources

Engineering and Applied Science

Characterization of the genetic determinants of context-specific DNA methylation in primary monocytes

To better understand inter-individual variation in sensitivity of DNA methylation (DNAm) to immune activity, we characterized effects of inflammatory stimuli on primary monocyte DNAm (n = 190). We find that monocyte DNAm is site-dependently sensitive to lipopolysaccharide (LPS), with LPS-induced demethylation occurring following hydroxymethylation. We identify 7,359 high-confidence immune-modulated CpGs (imCpGs) that differ in genomic localization and transcription factor usage according to whether they represent a gain or loss in DNAm. Demethylated imCpGs are profoundly enriched for enhancers and colocalize to genes enriched for disease associations, especially cancer. DNAm is age associated, and we find that 24-h LPS exposure triggers approximately 6 months of gain in epigenetic age, directly linking epigenetic aging with innate immune activity. By integrating LPS-induced changes in DNAm with genetic variation, we identify 234 imCpGs under local genetic control. Exploring shared causal loci between LPS-induced DNAm responses and human disease traits highlights examples of disease-associated loci that modulate imCpG formation