The effect of dynamic lockdowns on public transport demand in times of COVID-19: Evidence from smartcard data.

Governments around the globe have taken different measures to tackle the COVID-19 pandemic, including the lockdown of people to decrease infections. The effect of such a strategy on transport demand is important not only for the current pandemic but also to understand changes in transport use and for future emergencies. We analyse a 2019-2020 database of smartcard data of trips from the city of Santiago, Chile, which followed a dynamic lockdown strategy in which its municipalities were temporarily restricted. We use this variation over time across municipalities to study the effect of lockdowns on public transportation using trips on buses and metro, accounting for the variation of municipalities that were under lockdown in a given day. We found a decrease of 72.3% at the beginning of the pandemic when schools suspended in-person classes, while the dynamic lockdowns reduced public transport demand by 12.1%. We also found that the effect of lockdowns decreased after the fifth week of their application, suggesting a short-term effectiveness of such policy to reduce mobility. Regarding sociodemographic effects, we found that lockdowns have a stronger impact on reducing public transport demand in municipalities with a larger proportion of the elderly population (2% additional reduction per 1% increase in the share of the elderly population) and high-income households (16% additional reduction for 1000 USD increase in GDP per capita).

[Amoniuria, urinary gap and osmolal in patients with moderate renal insufficiency]. / Amoniuria, gap urinario y osmolal en pacientes con insuficiencia renal moderada.

The chronic metabolic acidosis induces increase in the urinary ammonium production (NH4+u) like equalizer, reflected in major or measured minor, if the process is chronic or acute. The objective of the present work was to study the capacity of urinary acidification in patients with Failure Renal Chronic (FRC), stage II and III measuring NH4+u and to compare results with GAP urinary (GAPu), GAP urinary modified (GAPu mod), GAP Osmolal (GAPosm) and GAP Osmolal modified (GAPosm modif.) like indirect indices of amoniuria. Samples Venous/arterial blood and a draft fresh urine of 34 patients were analyzed. Statistically significant correlation was obtained (p < 0,003) between NH4+u ug/min/1.73m2 versus GAPu mmol/l (r = -0,4979) and GAPu mod mmol/l (- 0.5032), improving when NH4+u normatizó by creatinine (r = - 0.6793 and 0.6087 respectively, p < 0,0001). The GAPosm and GAPosm modif did not show significance at the time of evaluating NH4+u, contrary GAPu and GAPu mod would offer an indirect measurement of excretion of NH4+u, having given this last protein nutritional information. A value of p < 0.05 was considered statistically significant.