Nonlinear stability of mKdV breathers

Breather solutions of the modified Korteweg-de Vries equation are shown to be globally stable in a natural H^2 topology. Our proof introduces a new Lyapunov functional, at the H^2 level, which allows to describe the dynamics of small perturbations, including oscillations induced by the periodicity of the solution, as well as a direct control of the corresponding instability modes. In particular, degenerate directions are controlled using low-regularity conservation laws.Comment: 24 pp., submitte

Dynamics of complex-valued modified KdV solitons with applications to the stability of breathers

We study the long-time dynamics of complex-valued modified Korteweg-de Vries (mKdV) solitons, which are recognized because they blow-up in finite time. We establish stability properties at the H^1 level of regularity, uniformly away from each blow-up point. These new properties are used to prove that mKdV breathers are H^1 stable, improving our previous result, where we only proved H^2 stability. The main new ingredient of the proof is the use of a B\"acklund transformation which links the behavior of breathers, complex-valued solitons and small real-valued solutions of the mKdV equation. We also prove that negative energy breathers are asymptotically stable. Since we do not use any method relying on the Inverse Scattering Transformation, our proof works even under rough perturbations, provided a corresponding local well-posedness theory is available.Comment: 45 pages, we thank Yvan Martel for pointing us a gap in the previous version of this pape

Employment promotion measures and the quality of the job match for persons with disabilities

We evaluate the influence that employment promotion measures and labour market intermediation services addressed to disabled individuals have on the latter’s quality of the job match through the use of matching analysis techniques. Our focus is placed on two aspects of quality: the type of contract held (either permanent or temporary) and whether or not the individual is searching for another job. We find that those measures do not improve the quality of the job match. Implications for labour market policy are discussed.Disability, job matching, employment promotion, evaluation, matching analysis, permanent contract, job-to-job search.

Identification of students' mental models about the milk transformation in yogurt

A review of the scientific literature reveals that there are still few researches on the conceptions of secondary school students about chemical reactions involving microorganisms, especially those related to the mental models that students use in their explanations. This paper describes a study concerning the different mental models related to the milk transformation into yogurt with 83 students from a Spanish secondary school of 8th and 9th grade (13-16 years) developed in the framework of a research that intends to use the elaboration of this product as a context for the teaching and learning of chemical reactions through modeling approaches. In order to identify the mental models of the students, in this paper we consider the milk transformation into yogurt as a process in which its main components are: the entities involved (milk and bacteria), the interaction between them and the result (yogurt). A simplified school model of this process would involve students considering that bacteria use the sugar in milk to transform it into lactic acid through a chemical reaction to obtain the necessary energy. Using this scheme in interaction with the students' answers, the underlying mental models were identified. Although almost half of the students showed great difficulties explaining the process, five models have been identified. Students often consider the milk transformation into yogurt primarily as a physical process of agglutination or change of state. These models are far from a school model of reference in which the bacteria have a fundamental role in the transformation of milk into yogurt by a chemical reaction.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Study of the effects of in vivo telomere elongation mechanisms in cancer and aging

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Bioquímica. Fecha de lectura: 30-01-2020Short and dysfunctional telomeres are sufficient to induce a persistent DNA damage response at chromosome ends, which leads to the induction of senescence and/or apoptosis and trigger age-related pathologies including a group of diseases known as “telomere syndromes”, and shorter lifespans in mice and humans. In turn, maintenance of longer telomeres owing to telomerase overexpression in adult tissues delays aging and increases mouse longevity. This opens the possibility of using telomerase activation as a potential therapeutic strategy to rescue short telomeres both in telomere syndromes and in agerelated diseases. However, telomerase has been found re-activated in most of human cancers making telomerase therapy a potential risk in treating short telomere accumulation. In this regard, telomere elongation avoiding the overexpression of telomerase could be a safer answer to prevent short telomeres delaying or even avoiding short telomere related pathologies. Based on this, the first aim of this thesis is to test the safety of telomerase gene therapy in the context of a cancer prone mouse model. To this end, we treated a well stablished K-Ras mediated lung cancer mouse model with AAV9-Tert for telomerase overexpression. As control, we also treated mice with AAV9 vectors carrying a catalytically inactive form of Tert, known to inhibit endogenous telomerase activity. We found that overexpression of Tert does not accelerate the onset or progression of lung carcinomas, even when in the setting of a p53-null background. These findings indicate that telomerase activation by using AAV9-mediated Tert gene therapy has no detectable cancer-prone effects in the context of oncogene-induced mouse tumors. On the other hand, the second aim of this thesis is to address whether embryonic stem (ES) cells carrying telomeres elongated in the absence of genetic modifications could contribute to the formation of a healthy organism and whether these elongated telomeres may have any deleterious effects. In this regard, we generated mice in which 100% of their cells are derived from hyper-long telomere ES cells. We found that these mice have longer telomeres and less DNA damage with aging. Interestingly, they are leaner than normal due to lower body fat accumulation. They also show less metabolic aging as indicated by lower cholesterol and LDL levels, and by improved glucose and insulin tolerance. Importantly, mice with hyper-long telomeres have less cancer and show an increased longevity. These findings demonstrate that longer telomeres than normal in a given species are not deleterious but instead, show beneficial effects.La acumulación de telomeros cortos es suficiente para inducir una respuesta de daño persistente en el ADN, induciendo sensecencia y/o apoptosis. Este fenómeno es la principal causa de las patologías relacionadas con la edad, incluyendo un grupo de enfermedades conocidas como “síndromes teloméricos”, así como de una menor esperanza de vida tanto en ratones como en humanos. Consecuentemente, la sobreexpresión de telomerasa en adultos es capaz de retrasar el envejecimiento y aumentar la esperanza de vida en ratones, pudiendo usar esta enzima como una potencial estrategia terapéutica para tratar estas enfermedades. Sin embargo, la telomerasa se ha visto re-activada en la mayoría de cánceres humanos, haciendo de esta terapia un riesgo potencial a la hora de tratar las enfermedades relacionadas con los telómeros. A este respecto, la elongación de los telómeros evitando la sobreexpresión de telomerasa podría ser una forma más segura de tratar dichas patologías retrasando o incluso evitando la aparición de telómeros cortos. En base a esto, el primer objetivo de esta tesis es probar la seguridad de la terapia génica con telomerasa en el contexto de un modelo animal propenso a padecer cáncer. Para ello, hemos tratado un modelo de ratón muy establecido que desarrolla cáncer de pulmón con AAV9-Tert. Como control, también hemos tratado estos animales con vectores virales AAV9 que contienen una forma catalíticamente inactiva de Tert, conocida por inhibir la actividad telomerasa endógena. Los resultados de este ensayo mostraron que la sobreexpresión de Tert no es capaz de acelerar la aparición ni la progresión del cáncer de pulmón, incluso en un fondo genético que carece de p53. Este descubrimiento indica que la activación de telomerasa usando la terapia génica mediada por vectores AAV9 no tiene ningún efecto oncogénico en el cáncer de pulmón en ratones. Por otro lado, el segundo objetivo de esta tesis ha sido demostrar si células madre embrionarias poseedoras de telómeros elongados sin necesidad de modificaciones genéticas podrían contribuir a la formación de organimos sanos y si estos telómeros podrían tener algún efecto deletéreo. Por ello, fuimos capaces de generar ratones en los que el 100% de sus células derivan de las células madre con telómeros súper-largos. Encontramos que estos animales presentan telómeros más largos y menor daño en el ADN con la edad. Interesantemente, eran más delgados de lo normal debido a una menor acumulación de grasa corporal. También mostraron una menor edad metabólica indicada por bajos niveles de colesterol y LDL y por una mejorada tolerancia a la glucosa y la insulina. Importantemente, estos animales tienen menos cáncer y una mayor longevidad. Estos descrubrimientos demuestran que tener telómeros más largos de los habituales para una especie no es deletéreo, sino que presenta efectos beneficiosos

Prescriptive Analytics in Electricity Markets

Electricity markets are a clear example of a sector in which decision making plays a crucial role in its daily activity. Moreover, uncertainty is intrinsic to electricity markets and affects most of the tasks that agents operating in them must carry out. Many of these tasks involve decisions characterized by low risk and being addressed periodically. In this thesis, we refer to these tasks as iterative decisions. This thesis applies the aforementioned innovative frameworks for decision making under uncertainty using contextual information in iterative decision making tasks faced daily by electricity market agents.Decision making is critical for any business to survive in a market environment. Examples of decision making tasks are inventory management, resource allocation or portfolio selection. Optimization, understood as the scientific discipline that studies how to solve mathematical programming problems, can help make more efficient decisions in many of these situations. Particularly relevant, because of their frequency and difficulty, are those decisions affected by uncertainty, i.e., in which some of the parameters that precisely determine the optimization problem are unknown when the decision must be made. Fortunately, the development of information technologies has led to an explosion in the availability of data that can be used to assist decisions affected by uncertainty. However, most of the available historical data do not correspond to the unknown parameter of the problem but originate from other related sources. This subset of data, potentially valuable for obtaining better decisions, is called contextual information. This thesis is framed within a new scientific effort that seeks to exploit the potential of data and, in particular, of contextual information in decision making. To this end, in this thesis, we have developed mathematical frameworks and data-driven optimization models that exploit contextual information to make better decisions in problems characterized by the presence of uncertain parameters

Motive of the SL4SL_4-character variety of torus knots

In this paper, we compute the motive of the character variety of representations of the fundamental group of the complement of an arbitrary torus knot into $SL_4(k)$, for any algebraically closed field $k$. For that purpose, we introduce a stratification of the variety in terms of the type of a canonical filtration attached to any representation. This allows us to reduce the computation of the motive to a combinatorial problem.Comment: 35 pages. Note: download source for the output of all the strata as separate fil

Lessons learned from the approach to the COVID-19 pandemic in urban primary health care centres in Barcelona, Spain

The recently published article by de Sutter et al. reflects the transformation that the coronavirus epidemic has caused in our world. With the need to adapt to the novel reality, new challenges and tasks for primary healthcare (PC) professionals have arisen. We will present here how PC has dealt with the issues emerging as the aftermath of the disease in Barcelona, Spain

Development of Cal Poly’s Hybrid AC/DC House

The Hybrid House provides an example for what sustainable housing solutions could look like. It also functions as a potential solution to the current rural electrification issues many developing countries face. The use of a DC-DC MISO converter allows for combining multiple power sources into a single DC bus. The Hybrid House integrates the DC bus by employing the use of DC-DC converters for home use. This system may potentially improve the overall system efficiency by avoiding the losses associated with AC-DC converters. The use of the DC bus further leverages the Solar Panel renewable energy solution to become a more formidable power solution. This increased efficiency aligns with the overall goal of the Hybrid House which is to utilize mostly renewable energy in a home while still having the capability of integrating the grid power. Consequently, the Hybrid AC-DC House also offers an alternative solution for future sustainable house with improved reliabilit