Comparison of relativity theories with observer-independent scales of both velocity and length/mass

We consider the two most studied proposals of relativity theories with observer-independent scales of both velocity and length/mass: the one discussed by Amelino-Camelia as illustrative example for the original proposal (gr-qc/0012051) of theories with two relativistic invariants, and an alternative more recently proposed by Magueijo and Smolin (hep-th/0112090). We show that these two relativistic theories are much more closely connected than it would appear on the basis of a naive analysis of their original formulations. In particular, in spite of adopting a rather different formal description of the deformed boost generators, they end up assigning the same dependence of momentum on rapidity, which can be described as the core feature of these relativistic theories. We show that this observation can be used to clarify the concepts of particle mass, particle velocity, and energy-momentum-conservation rules in these theories with two relativistic invariants.Comment: 21 pages, LaTex. v2: Andrea Procaccini (contributing some results from hia Laurea thesis) is added to the list of authors and the paper provides further elements of comparison between DSR1 and DSR2, including the observation that both lead to the same formula for the dependence of momentum on rapidit

The reduction of selenium(IV) by hydrogen sulfide in aqueous solutions

The rates for the reduction of Se(IV) by sulfides were measured in NaCl solutions as a function of pH (2-10), temperature (10-40°C) and ionic strength (I=0.01-1M). The pseudo first-order rate constant (logk 1) showed a complex dependence on pH with values decreasing from pH 2 to a minimum at pH 4.5, then increasing from pH 5.5 to a maximum near pH 8 and decreasing again at pH higher than 8. The values of the overall kinetic constant (k) calculated from the values of k 1/[H 2S] T can be determined from equations: logk=-0.15pH-1355.5/T+0.44I0.5+7.74 for the pH range 2-4.5 (σ=±0.16), logk=0.28pH-1090.9/T+0.60I0.5+4.68 for the pH range 5.5-7.6 (σ=±0.10) and logk=-0.50pH-1572.1/T+0.45I0.5+12.67 for the pH range 7.7-10 (σ=±0.05), from 10 to 40°C and from 0.01 to 1M ionic strength. The effect of pH and ionic strength on the reaction suggests that the reactions in natural waters are due to the following interactions: H2SeO3+H2S↔products HSeO3-+H2S↔products HSeO3-+HS-↔products while under strong alkaline conditions (pH>9) a fourth contribution by SeO32-+HS-↔products is also possible. The overall rate expression over the entire pH range investigated can be determined from (H 2A=H 2SeO 3; HA=HSeO 3 -; A=SeO 3 2-) k=(kH2S-H2A[H+]3+kH2S-HAKHA[H+]2+kHS-HAKHAK1s[H+]+kHS-AKHAKAK1s)/{([H+]2+KHA[H+]+KAKHA)([H+]+K1s)} where kH2S-H2A=2409±566M-1min-1, kH2S-HA=464±233M-1min-1, k HS-HA=4190±573M -1min -1 and k HS-A=650±382M -1min -1 and K HA, K A and K 1s are the dissociation constants of selenous acid and hydrogen sulfide. Kinetic runs in natural freshwater samples and natural seawater have confirmed results obtained in simple NaCl solutions suggesting that this reaction may play an important role under anoxic and hypoxic conditions. Sulfide concentrations under these conditions may range from micromolar to millimolar level and Se(IV) half times are in the order of a few hours to minutes, respectively. © 2011 Elsevier Ltd

COVID-19-related death in patients with alcohol or substance use disorders.

BACKGROUND People with substance or alcohol use disorders (SUDs/AUDs) are likely to be more vulnerable to COVID-19 infection than the general population, but the evidence of COVID-19-related mortality in these patients is unclear. OBJECTIVES The aim of the study was to verify whether patients with AUD and SUD have a higher mortality rate for COVID-19-related mortality compared to the general population. METHOD We performed a follow-up study to assess mortality in 2020 in a cohort of patients diagnosed for the first time with AUDs or SUDs at the Public Health Services in the metropolitan area of Bologna (Northern Italy) from 2009 to 2019. RESULTS SUDs/AUDs patients present an excess mortality with respect to the general population for all causes of death and for COVID-19-related mortality. CONCLUSIONS Our data support the need for prevention strategies in SUDs/AUDs patients such as vaccinations

L’unica riforma necessaria per il Mes

L’Italia è rimasto il solo paese a non aver sottoscritto la riforma del Meccanismo europeo di stabilità (Mes) e si moltiplicano le pressioni, interne ed esterne, perché provveda a farlo

Mes, una riforma che persevera negli errori. Un appello di economisti e giuristi

L’Italia non deve avallare un meccanismo che riproduce le logiche del passato, che si sono rivelate clamorosamente sbagliate. Inoltre accettare questa riforma significherebbe ridurre gli interventi innovativi decisi per fronteggiare la pandemia a un’eccezione, in attesa di tornare appena possibile a politiche che minacciano la stessa sopravvivenza dell’Unione