Representations in Density Dependent Hadronic Field Theory and compatibility with QCD sum-rules

Different representations of an effective, covariant theory of the hadronic interaction are examined. For this purpose we have introduced nucleon-meson vertices parametrized in terms of scalar combinations of hadronic fields, extending the conceptual frame of the Density Dependent Hadronic Field Theory. Nuclear matter properties at zero temperature are examined in the Mean Field Approximation, including the equation of state, the Landau parameters, and collective modes. The treatment of isospin channels in terms of QCD sum rules inputs is outlined.Comment: 23 pages, 6 PostScript figures, Revtex4 clas

A Pivotal Moment: Assessing Houston's Plan for Pension Reform

The Laura and John Arnold Foundation (LJAF) released "A Pivotal Moment: Assessing Houston's Plan for Pension Reform," a report that provides an in-depth analysis of the City of Houston's pension reform proposal currently pending in the Texas Legislature. The report finds that the proposal includes important changes that would help protect workers and taxpayers. The reform plan was developed following discussions between Mayor Sylvester Turner and the Houston Police Officers' Pension System, the Houston Municipal Employees Pension System, and the Houston Firefighters' Relief and Retirement Fund.LJAF Vice President Josh McGee and LJAF Sustainable Public Finance Analyst Paulina S. Diaz Aguirre co-authored the report after analyzing the city's proposal and conducting independent pension modeling. They say that it is incumbent on local leaders and state legislators to work together. "There are just a few weeks left in the 2017 session—and without the ability to make changes to the pension systems on its own—the city is running out of time," the report states. "Without changes, the debt could spiral into a full-scale financial crisis. The city cannot allow that to happen. Its financial future hangs in the balance and will be decided in large part in the next month."Houston currently owes $8.2 billion in pension debt—more than any other city in Texas. It does not have enough money to pay for nearly half of the retirement benefits workers have already earned. This unfunded liability threatens workers' retirement security and has a direct impact on city finances. During the past 10 years, the city has cut public safety positions even as spending on public safety has grown by hundreds of millions of dollars due to a 55 percent increase in pension costs.The proposal seeks to address critical flaws in the city's funding practices. Under the proposal, the city would lower its assumed rate of return on investments for all plans from 8 percent or more to 7 percent; reduce benefits for public workers; and implement a financial corridor provision that would cap the city's contributions to the pension plans.The financial corridor provision is a key element of the proposal. The provision would set a minimum and maximum city contribution rate for each plan. If the city were to hit or surpass the maximum, workers would be required to make additional benefit concessions to bring costs back under the cap. LJAF's analysis shows that this mechanism would provide substantial new protections for taxpayers but would also significantly increase workers' exposure to risk.The report states that the proposal's long-term impact on workers would depend on demographic trends and the plans' investment performance, two factors that would influence how often the city would hit the cap. For example, LJAF's modeling shows that there is a two in five (40 percent) chance that the city's contribution rate would hit the maximum for the police fund at least once by 2027. If the police plan were to earn less than 7 percent on its investments in the short or long term, contribution rates would hit the cap even sooner.If investment returns match the city's assumptions, there is roughly a one in three (33 percent) chance that contribution rates for members of the police plan would increase by five percentage points or more in the next decade. Given that members of the police plan—as well as members of the other plans—have already agreed to billions of dollars in concessions, McGee and Diaz Aguirre explain that the city has an obligation to uphold its end of the bargain. They state that the city should make payments on time and in full and should take steps—such as limiting investments in risky assets including real estate, private equity, and hedge funds—to protect workers.In addition, if the proposal is implemented, the report states that the city should also make good on its promise to provide a lump-sum payment to the two plans with the largest deficits—the police and municipal employees plans. The city has proposed issuing$1 billion in pension obligation bonds to cover the payments. To benefit financially, Houston would need to earn more in the market than it costs to borrow the money. Given the current market conditions, the spread between expected bond interest rates and expected returns is relatively small. Despite the fact that the bonds pose some risk, the report argues that they are a good-faith measure that reflects the city's commitment to upholding funding promises.The report concludes that, "In the short term, the proposal would place the pension plans—and the city—on firmer financial footing. The long-term impact would depend on how the changes are implemented." It also states that Houston should make further changes to establish a comprehensive, permanent solution to its pension problems. This would include creating retirement systems for new workers that are simpler and easier to manage such as a Defined Contribution plan or a Cash Balance plan

Characterisation of Eucalyptus grandis SWEET and SWI/SNF proteins during symbiosis with Pisolithus microcarpus

Eucalyptus grandis, an economically important bioenergy tree, is constantly bombarded by different fungal lifestyles seeking to acquire photosynthetically fixed sugar. How the plant immune system filters beneficial fungi from pathogenic is poorly understood. This thesis investigates two aspects of plant immunity: shuttling of sugar and interference by fungal effectors. Plant sugars are known to play a dual role in plant-microbe interactions: they can either feed the microbe with growth-limiting carbon or they can act as fuel for plant secondary metabolism and, subsequently, plant defence. In my first study I consider how hexose SWEET transporters respond at the transcriptomic level in E. grandis roots during challenge by different microbes covering the fungal lifestyles from pathogenic through mutualistic. Further, I characterise four E. grandis SWEET proteins that share sequence homology to previously identified SWEET proteins and determine their cellular localization, their sugar transport capabilities and their role in shuttling carbon during plant-microbe interactions. In the second part of my thesis, I investigate how a mutualistic fungus attempts to manipulate plant defences through the use of effector like proteins. Specifically, I characterise the role of Pisolithus albus MiSSP9.7, a highly induced secreted fungal protein of unknown function. I demonstrate that it interacts with a member of the SWI/SNF protein complex previously identified as being responsible for the regulation of plant hormone signalling pathways used in immune responses against microbes. Increased expression of SWI3D in E. grandis roots is tied to the colonisation process and may regulate a key aspect of plant immunity towards mutualistic fungi. Taken together, my work provides a better understanding of the controls used by plants to modulate plant-microbe interactions and the counter-measures utilized by fungi to overcome host immunity

On the smoothness of nonlinear system identification

We shed new light on the \textit{smoothness} of optimization problems arising in prediction error parameter estimation of linear and nonlinear systems. We show that for regions of the parameter space where the model is not contractive, the Lipschitz constant and $\beta$-smoothness of the objective function might blow up exponentially with the simulation length, making it hard to numerically find minima within those regions or, even, to escape from them. In addition to providing theoretical understanding of this problem, this paper also proposes the use of multiple shooting as a viable solution. The proposed method minimizes the error between a prediction model and the observed values. Rather than running the prediction model over the entire dataset, multiple shooting splits the data into smaller subsets and runs the prediction model over each subset, making the simulation length a design parameter and making it possible to solve problems that would be infeasible using a standard approach. The equivalence to the original problem is obtained by including constraints in the optimization. The new method is illustrated by estimating the parameters of nonlinear systems with chaotic or unstable behavior, as well as neural networks. We also present a comparative analysis of the proposed method with multi-step-ahead prediction error minimization

Landau parameters for isospin asymmetric nuclear matter based on a relativistic model of composite and finite extension nucleons

We study the properties of cold asymmetric nuclear matter at high density, applying the quark meson coupling model with excluded volume corrections in the framework of the Landau theory of relativistic Fermi liquids. We discuss the role of the finite spatial extension of composite baryons on dynamical and statistical properties such as the Landau parameters, the compressibility, and the symmetry energy. We have also calculated the low lying collective eigenfrequencies arising from the collisionless quasiparticle transport equation, considering both unstable and stable modes. An overall analysis of the excluded volume correlations on the collective properties is performed.Comment: 24 pages, 6 figure

Martín Doello Jurado and the teaching of paleontology in the university of Buenos Aires

Doello Jurado was, together with Florentino and Carlos Ameghino, Eduardo l. Holmberg and Ángel Gallardo, part of the last generation of naturalists that characterized the natural sciences in Argentina, mainly in the late 19th century. since young, he was interested in the history of the development of the natural sciences in our country. Ángel Gallardo, his master, designed him traveler naturalist of the national museum of natural History and in this way he started his studies on the marine invertebrates of our continental platform. Afterwards he was Director of the national museum of natural History, at that time in Perú 208 and in two years' time started the construction of the new building, presently in parque Centenario. He was professor of paleontology in the Faculty of exact and natural sciences of the university of Buenos Aires, and he incremented the collections travelling to different regions of the country. He bought several collections of fossils to the famous Krantz geological warehouse of Bonn and to the Geological Institutes of Bonn, Munich and Brunswick and provided plaster casts of Cenozoic fossil mammals from the Buenos Aires natural History museum. Doello Jurado was co-founder of the Argentine society of natural sciences, the Del Plata ornithological society and the journals Physis and El Hornero. He was also member of the national Academy of exact and natural sciences of Buenos Aires and the national Academy of sciences in Córdoba.Fil:Aguirre-Urreta, B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Camacho, H.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Anthropic reasoning in multiverse cosmology and string theory

Anthropic arguments in multiverse cosmology and string theory rely on the weak anthropic principle (WAP). We show that the principle, though ultimately a tautology, is nevertheless ambiguous. It can be reformulated in one of two unambiguous ways, which we refer to as WAP_1 and WAP_2. We show that WAP_2, the version most commonly used in anthropic reasoning, makes no physical predictions unless supplemented by a further assumption of "typicality", and we argue that this assumption is both misguided and unjustified. WAP_1, however, requires no such supplementation; it directly implies that any theory that assigns a non-zero probability to our universe predicts that we will observe our universe with probability one. We argue, therefore, that WAP_1 is preferable, and note that it has the benefit of avoiding the inductive overreach characteristic of much anthropic reasoning.Comment: 7 pages. Expanded discussion of selection effects and some minor clarifications, as publishe