The Value of "Value Pricing" of Roads: Second-Best Pricing and Product Differentiation

Some road-pricing demonstrations use an approach called "value pr icing", in which travelers can choose between a free but congested roadway and a priced roadway. Recent research has uncovered a potentially serious problem for such demonstrations: in certain models, second-best tolls are far lower than those typically charged, and the welfare gains from profit maximization are small or even negative. That research, however , assumes that all travelers are identical, and it therefore neglects the benefits of product differentiation, by which people with different values of time can choose a suitable cost/quality combination. Using a model with two user groups, we find that accounting for heterogeneity in value of time is important in evaluating constrained policies, and improves the relative performance of policies that offer differential prices. Nevertheless, for most of the reasonable range of heterogeneity, second-best pricing produces far fewer benefits than pricing both roadways optimally, and profit-maximizing tolls are so high that over all welfare is reduced from the no-toll baseline.

I piani settoriali a scala urbana

Il contributo propone un focus su alcuni strumenti di settore che affrontano specifiche tematiche alla scala urbana, con particolare riferimento agli strumenti per la tutela della qualità ambientale e per il governo della mobilità. Si evidenziano, in entrambi i casi, le significative interrelazioni tra problematiche ambientali e scelte relative all’evoluzione/trasformazione dei contesti urbani e al governo della mobilità e la conseguente necessità di una più stretta integrazione tra strumenti generali e settoriali, difficilmente conseguibile attraverso il solo coordinamento a posteriori tra strumenti elaborati separatamente e sulla base di approcci settoriali

Health + Equality + School Engagement: Scenarios USA Reinvents Sex Education

This issue of Quality/Calidad/Qualité highlights the experience of Scenarios USA,3 an innovative nonprofit program that has integrated a gender and rights perspective -- and a critical thinking approach -- into curricula, while fostering new pedagogies and greater awareness among teachers. Scenarios USA approaches sexual health not as a stand-alone issue but as intertwined with young people's overall lives and agency. As such, the organization's "sex ed" work is part of a broader strategy of fostering self-expression, leadership, and advocacy among youth, especially among those living in marginalized communities.Instead of teaching adolescents about contraceptive methods, Scenarios has them thinking and writing about gender norms, power dynamics, and intimate relationships in their own lives

Un processo per la qualità paesaggistica

Il saggio sintetizza il processo metodologico proposto come esito della ricerca PRIN "Scenari di paesaggio nel piano urbanistico locale". La ricerca muove dalla constatazione della mancanza di modelli di riferimento, nel nostro paese, per il trattamento degli aspetti paesaggistici a livello locale, e in particolare negli strumenti urbanistici comunali, e della difficoltà nell'adeguamento ai nuovi piani paesaggistici regionali. Si sviluppa ed illustra, attraverso un caso studio, un processo di analisi, valutazione dello stato e delle dinamiche, proposta di scenari progettuali, valutazione degli stessi scenari e coinvolgimento delle popolazioni nelle scelte. Il processo presenta alcune proposte di innovazione ed è concretamente illustrato nei diversi passaggi

Way-out to the Gravitino problem in intersecting D-brane Pati-Salam models

We discuss the gravitino problem in contest of the Exotic see-saw mechanism for neutrinos and Leptogenesis, UV completed by intersecting D-branes Pati-Salam models. In the Exotic see-saw model, supersymmetry is broken at high scales $M_{SUSY}>10^{9}\, \rm GeV$ and this seems in contradiction with gravitino bounds from inflation and baryogenesis. However, if gravitino is the Lightest Stable Supersymmetric Particle, it will not decay into other SUSY particles, avoiding the gravitino problem and providing a good Cold Dark Matter. Gravitini are Super Heavy Dark Particles and they can be produced by non-adiabatic expansion during inflation. Intriguingly, from bounds on the correct abundance of dark matter, we also constrain the neutrino sector. We set a limit on the exotic instantonic coupling of $<10^{-2}\div 10^{-3}$. This also sets important constrains on the Calabi-Yau compactifications and on the string scale. This model strongly motivates very high energy DM indirect detection of neutrini and photons of $10^{11}\div 10^{13}\, \rm GeV$: gravitini can decay on them in a cosmological time because of soft R-parity breaking effective operators.Comment: Name, Affiliations and email of M.K. are corrected, Version accepted by Mod.Phys.Lett.