Alejandro Pisanty

Quantitative structure-activity relationships of competitive inhibitors of phosphoenolpyruvate carboxylase

The quantitative structure-activity relationships (QSAR) of all known competitive inhibitors of the enzyme phosphoenolpyruvate carboxylase from C4 plants were investigated by means of molecular mechanics, the semiempirical quantum chemical methods MNDO and AM1, and the Hansch approach. In the case of phosphoenolpyruvate analogues, the hydrophobicity and steric impediment of the combined cis and trans substituents, the bond distance to the cis substituent along with its volume, dipole moment, the distance between the phosphorus and the carbonyl carbon, and the net electric charges on the phosphate and substituent groups are the main factors that govern their binding to the active site. For the phosphoglycolate analogues, the difference in the HOMO-LUMO energies, the magnitudes of their dipole moments and their non-polar surfaces, and the distance between the phosphorus and the carbonyl carbon are the variables that control their binding to the active site. These results, in conjunction with a discriminant analysis, also suggest that these inhibitors can actually be divided into two groups, according to the way they presumably interact with the active site.

Electronic mailing lists and chemical research: a case study☆

Abstract The Computational Chemistry Electronic Mailing List is an electronic-mail-based discussion forum for issues related to computational chemistry and similar topics. The impact on the way its readers work in chemical research and teaching and how Internet is changing academic and professional practice is described.

Cluster method density of states for noble metals and comparison with photoemission spectra

Abstract The multiple scattering cluster method is used to calculate densities of states for Cu, Ag, and Au. The results compare favorably with experimental photoemission spectra. The method converges rapidly with the cluster size used for the calculation.

Network Neutrality Debates in Telecommunications Reform: Actors, Incentives, Risks

This work presents a summary of the debates about Network Neutrality in the legislative process of Mexico in 2013–2014. A major telecommunications law and market reform is taking place in the country and Network Neutrality is a useful test case to measure how convergent the legislation actually manages to be and to identify options that can be translated to other markets. It is of interest also because it occurs in the absence of any common-carriage tradition and at the same time as must-carry, must-offer provisions are being introduced for television for the first time. Network Neutrality has become a rallying cry for public demonstrations and other protests against the reform project. Major economic forces, ideological and political trends are described and interpreted with a view toward their generalization to other geographies and contexts.

Network Neutrality Under the Lens of Risk Management

An original approach to Network Neutrality is presented. Violations of Network Neutrality are considered as risk and a risk management framework to deal with such violations is presented. This framework can be used by different parties in varied environments for dealing with preventive as well as reactive action in the face of violations by Internet Service Providers and other infringing parties. The framework includes an identification of the forms of Network Neutrality violations, their weighting by likelihood and impact, and actions for risk avoidance, detection, mitigation, business continuity, contingency planning, and prevention. The actions are shown in a graduated-response order so that scaling up towards the resolution of conflict or controversy around Network Neutrality violations can be properly planned and executed.

The electronic structure of magnetic UTe

Abstract A novel analysis is presented for the electronic structure of UTe, pointing out the important contributions of uranium p and d states as well as tellurium d states not previously studied. Also found is the f-band splitting. Full analysis for both electron spins brings out uranium-f to tellurium-d bonding and shows peculiar d-electron features only recently measured.