Dynamic regulation of the tryptophan operon: A modeling study and comparison with experimental data

A mathematical model for regulation of the tryptophan operon is presented. This model takes into account repression, feedback enzyme inhibition, and transcriptional attenuation. Special attention is given to model parameter estimation based on experimental data. The model's system of delay differential equations is numerically solved, and the results are compared with experimental data on the temporal evolution of enzyme activity in cultures of Escherichia coli after a nutritional shift (minimal + tryptophan medium to minimal medium). Good agreement is obtained between the numeric simulations and the experimental results for wild-type E. coli, as well as for two different mutant strains.

Improved and customized secondary optics for photo-voltaic concentrators

In this contribution the line flow method is applied to an optimized secondary optics in a photovoltaic concentration system where the primary optics is already defined and characterized. This method is a particular application of photic field theory. This method uses the parameterization of a given primary optics, including actual tolerances of the manufacturing process. The design of the secondary optics is constrained by the selection of primary optics and maximizes the concentration at a previously specified collection area. The geometry of the secondary element is calculated by using a virtual source, which sends light in a first concentration step. This allows us to calculate the line flow for this specific case. This concept allows designing more compact and efficient secondary optics of photovoltaic systems.

Study and evaluation of several cache replacement policies on a commercial MIPS Processor

Actualmente, el rendimiento de los computadores es un tema candente. Existen importantes limitaciones físicas y tecnológicas en los semiconductores de hoy en día, por lo que se realiza un gran esfuerzo desde las universidades y la industria para garantizar la continuidad de la ley de Moore. Este proyecto está centrado en el estudio de la cache y la jerarquía de memoria, uno de los grandes temas en la materia. Para ello, hemos escogido MIPSfpga, una plataforma hardware abierta de Imagination Technologies, lo que nos ha permitido implementar y testear diferentes políticas de reemplazamiento como prueba de concepto, demostrando, además, las bondades de la plataforma.

The Museum/School Partnership: A New Role for Art Museums in K-5 Art Education

For nearly thirty years, the arts have been poorly represented in public school classrooms due to tight budgets, state mandates, and a belief that the arts are not essential to education. In this paper, I will investigate the absence of focused art education curriculum in K-5 classrooms across the United States’ public school system, explain the advantages of reinstating art as a basic subject in the classroom curriculum, and advocate for a more active art museum role in public school elementary art education. The art museum may be in the ideal position to help develop and facilitate programming in K-5 classrooms. By placing teams of art museum professionals in public school classrooms, art museums can establish a prominent role in the museum/school relationship and can help ensure that children have adequate access to art education. The outcome would be children who have greater academic and personal successes throughout their lives.

Academie to atelier : the artistic education of American women in nineteenth-century Paris

This paper puts forth an alternate reading of the artistic climate in late nineteenth-century Paris than that which has traditionally been suggested. I propose that the expansion of creative opportunity during this time reveals a climate of communal support, consent, and progressive reform for women artists, rather than a struggle to undermine central (masculine) control, as many scholars have claimed. Specifically, I explore the work of American expatriates living in Paris, including but not limited to Cecilia Beaux, Anna Klumpke, Alice Kellogg, and Ellen Day Hale. The birth of the private academy in Paris offered women the chance to develop their artistic ability and assert their independence. The Académie Julian in particular provided a comparatively accepting and progressive environment where American women studying abroad could study from the nude model, receive proper training, and explore their full creative potential. Through an examination of a) these women’s self-portraits, and b) depictions of them painted by their contemporaries – both male and female – I further investigate the artistic education of American women in the highly-gendered cultural milieu of late nineteenth-century France.

Self-heating and deicing conductive cement. Experimental study and modeling

This research studies the self-heating produced by the application of an electric current to conductive cement pastes with carbonaceous materials. The main parameters studied were: type and percentage of carbonaceous materials, effect of moisture, electrical resistance, power consumption, maximum temperature reached and its evolution and ice melting kinetics are the main parameters studied. A mathematical model is also proposed, which predicts that the degree of heating is adjustable with the applied voltage. Finally, the results have been applied to ensure that cementitious materials studied are feasible to control ice layers in transportation infrastructures.

Kinetic study and thermal decomposition behavior of viscoelastic memory foam

A systematic investigation of the thermal decomposition of viscoelastic memory foam (VMF) was performed using thermogravimetric analysis (TGA) to obtain the kinetic parameters, and thermogravimetric analysis coupled to Fourier Transformed Infrared Spectrometry (TGA-FTIR) and thermogravimetric analysis coupled to Mass Spectrometry (TGA-MS) to obtain detailed information of evolved products on pyrolysis and oxidative degradations. Two consecutive nth-order reactions were employed to correlate the experimental data from dynamic and isothermal runs performed at three different heating rates (5, 10 and 20 K/min) under an inert atmosphere. On the other hand, for the kinetic study of the oxidative decomposition, the data from combustion (synthetic air) and poor oxygen combustion (N2:O2 = 9:1) runs, at three heating rates and under dynamic and isothermal conditions, were correlated simultaneously. A kinetic model consisting of three consecutive reactions presented a really good correlation in all runs. TGA-FTIR analysis showed that the main gases released during the pyrolysis of VMF were determined as ether and aliphatic hydrocarbons, whereas in combustion apart from the previous gases, aldehydes, amines and CO2 have also been detected as the main gases. These results were confirmed by the TGA-MS.

A system of ethicks: Of morall phylosophy in generall & in speciall

This hardcover volume contains manuscript copies of Charles Morton's "A System of Ethicks," "Pneumatics. Or a treatise of the Rev'd Mr. Charles Morton about ye Nature of Spirit," "Appendix of the Souls of Brutes," "Some Theological Questions Answd," and a one-page list "Texts of Scripture to prove if ye head of Christ &c." copied by Harvard student Ebenezer Williams in February 1707/8.