To involvement the conformation of the adenine nucleotide translocase in opening the Tl+-induced permeability transition pore in Ca2+-loaded rat liver mitochondria

The conformation of adenine nucleotide translocase (ANT) has a profound impact in opening the mitochondrial permeability transition pore (MPTP) in the inner membrane. Fixing the ANT in 'c' conformation by phenylarsine oxide (PAO), tert-butylhydroperoxide (tBHP), and carboxyatractyloside as well as the interaction of 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) with mitochondrial thiols markedly attenuated the ability of ADP to inhibit the MPTP opening. We earlier found (Korotkov and Saris, 2011) that calcium load of rat liver mitochondria in medium containing TINO3 and KNO3 stimulated the Tl+-induced MPTP opening in the inner mitochondrial membrane. The MPTP opening as well as followed increase in swelling, a drop in membrane potential (Delta Psi(mito)), and a decrease in state 3, state 4, and 2,4-dinitrophenol-uncoupled respiration were visibly enhanced in the presence of PAO, tBHP, DIDS, and carboxyatractyloside. However, these effects were markedly inhibited by ADP and membrane-penetrant hydrophobic thiol reagent, N-ethylmaleimide (NEM) which fix the ANT in 'm' conformation. Cyclosporine A additionally potentiated these effects of ADP and NEM. Our data suggest that conformational changes of the ANT may be directly involved in the opening of the Tl+-induced MPTP in the inner membrane of Ca2+-loaded rat liver mitochondria. Using the Tl+-induced MPTP model is discussed in terms finding new transition pore inhibitors and inducers among different chemical and natural compounds. (C) 2016 Elsevier Ltd. All rights reserved.Peer reviewe

Social acceptability of a marine protected area: The case of Reunion Island

This paper examines variations in social acceptability of a Marine Protected Area (MPA) prior to implementation. The influence of a number of factors, including socio-economic characteristics, perception of coral resources state of health and attitudes towards non-compliance with regulations are analysed. During May 2006, 640 questionnaires were distributed to school children around Reunion Island, Western Indian Ocean, for completion by their parents, following an informal educational activity made in school. From a 73% (n = 469) response rate, results showed that 78% of participants were in favour of the MPA. Analysis further identified that those supportive of the MPA were generally from higher socio-professional categories, had a negative perception of the coral reef ecosystem's health and were not originally from Reunion. In contrast, locals (born in Reunion) from lower socio-professional categories or with no employment activity and having a positive perception of the health status of coral reefs offered no opinion on the MPA. Attitudes towards enforcement and compliance highlighted that SCUBA divers, fishers and jet skiers attributed a higher value to the protection of the coral reef environment through enforcement of MPA regulations than to their own use of the coral reef resource. When asked about the use of penalties to deter non-compliance, swimmers were awarded the lowest fines, followed by SCUBA divers, fishers then jet skiers being awarded the highest fines. Thus, the more severe the act of non-compliance by a resource user group was perceived to be, the more these users themselves disapproved of non-compliant behaviour and supported use of high penalties. The survey design through focusing on school children's parents, demonstrated a simple and cost-effective method for data collection while providing environmental education, which could be employed in similar case studies elsewhere

Toksičnost talija u humanoj populaciji

Thallium is a naturally occurring trace element, widely distributed in the earth’s crust, but at very low concentrations. It does not have a known biological use and does not appear to be an essential element for life. It has been considered one of the most toxic heavy metals. Occasionally, there are reports on thallium poisoning as results of suicide or murder attempt or accident. The main threat to humans is through occupational exposure, environmental contamination, and accumulation in food, mainly in vegetables grown on contaminated soil. Increasing use in emerging new technologies and demanding high-tech industry constantly raise concern about exposure risk to all living organisms. Thallium is considered a cumulative poison that can cause adverse health effects and degenerative changes in many organs. The effects are the most severe in the nervous system. The exact mechanism of thallium toxicity still remains unknown, although impaired glutathione metabolism, oxidative stress, and disruption of potassium-regulated homeostasis may play a role. The lack of data about mutagenic, carcinogenic, or teratogenic effects of thallium compounds in humans calls for further research.Talij je u prirodi široko rasprostranjen teški metal, prisutan u vrlo niskim koncentracijama pa ga stoga ubrajamo u elemente u tragovima. Budući da organizmima nije potreban ni u jednoj razvojnoj fazi, ne ubrajamo ga u grupu esencijalnih elemenata. Talij zbog njegovih svojstava ubrajamo među najtoksičnije teške metale. Povremeno se još uvijek pojavljuju slučajevi u kojima je talij upotrijebljen kao sredstvo za pokušaj ubojstva, odnosno samoubojstva, ali i slučajevi nenamjernog, slučajnog trovanja talijem. U današnje vrijeme potencijalna o asnost od trovanja talijem postoji zbog profesionalne izloženosti, izbijanja ekološke katastrofe ili zbog akumulacije u hranidbenim lancima, uglavnom zbog uzgoja hrane na onečišćenom tlu. Sve češća uporaba talija u visokotehnološkoj industriji kao odgovor na zahtjeve moderne tehnologije neprestano povećava rizik od izloženosti svih živih organizama štetnim utjecajima talija u okolišu. Talij ima izuzetno negativan učinak na različite organske sustave, a osobito na živčani sustav. Mehanizmi toksičnosti talija još uvijek nisu u potpunosti razjašnjeni, premda važnu ulogu imaju poremećaji metabolizma glutationa, oksidativni stres i narušavanje homeostaze posredovane ionima kalija. Nedostatak podataka o mutagenim, kancerogenim ili teratogenim učincima talija i njegovih spojeva u ljudi opravdava buduća istraživanja ovog vrlo toksičnog metala

Toksičnost talija u humanoj populaciji

Thallium is a naturally occurring trace element, widely distributed in the earth’s crust, but at very low concentrations. It does not have a known biological use and does not appear to be an essential element for life. It has been considered one of the most toxic heavy metals. Occasionally, there are reports on thallium poisoning as results of suicide or murder attempt or accident. The main threat to humans is through occupational exposure, environmental contamination, and accumulation in food, mainly in vegetables grown on contaminated soil. Increasing use in emerging new technologies and demanding high-tech industry constantly raise concern about exposure risk to all living organisms. Thallium is considered a cumulative poison that can cause adverse health effects and degenerative changes in many organs. The effects are the most severe in the nervous system. The exact mechanism of thallium toxicity still remains unknown, although impaired glutathione metabolism, oxidative stress, and disruption of potassium-regulated homeostasis may play a role. The lack of data about mutagenic, carcinogenic, or teratogenic effects of thallium compounds in humans calls for further research.Talij je u prirodi široko rasprostranjen teški metal, prisutan u vrlo niskim koncentracijama pa ga stoga ubrajamo u elemente u tragovima. Budući da organizmima nije potreban ni u jednoj razvojnoj fazi, ne ubrajamo ga u grupu esencijalnih elemenata. Talij zbog njegovih svojstava ubrajamo među najtoksičnije teške metale. Povremeno se još uvijek pojavljuju slučajevi u kojima je talij upotrijebljen kao sredstvo za pokušaj ubojstva, odnosno samoubojstva, ali i slučajevi nenamjernog, slučajnog trovanja talijem. U današnje vrijeme potencijalna o asnost od trovanja talijem postoji zbog profesionalne izloženosti, izbijanja ekološke katastrofe ili zbog akumulacije u hranidbenim lancima, uglavnom zbog uzgoja hrane na onečišćenom tlu. Sve češća uporaba talija u visokotehnološkoj industriji kao odgovor na zahtjeve moderne tehnologije neprestano povećava rizik od izloženosti svih živih organizama štetnim utjecajima talija u okolišu. Talij ima izuzetno negativan učinak na različite organske sustave, a osobito na živčani sustav. Mehanizmi toksičnosti talija još uvijek nisu u potpunosti razjašnjeni, premda važnu ulogu imaju poremećaji metabolizma glutationa, oksidativni stres i narušavanje homeostaze posredovane ionima kalija. Nedostatak podataka o mutagenim, kancerogenim ili teratogenim učincima talija i njegovih spojeva u ljudi opravdava buduća istraživanja ovog vrlo toksičnog metala

Essays in Development Economics, Case of Malawi

My dissertation focuses on two important aspects that affect micro-entrepreneurs in developing countries: electricity outages and saving constraints. In my first chapter, I study the impacts of infrastructure deficiencies on small business owners in the context of the electricity supply in Malawi - a country where power is very unreliable and only 25% of small businesses are even connected to the grid. Access to reliable electricity is a requirement for development. Yet, most research focuses only on the effects of the first stage - establishing connection to the grid. However, the quality provision is quite poor and existing customers experience frequent outages. Using high frequency data collected on 391 small businesses across the city of Blantyre, I document the following: (1) power outages are very frequent, occur on 67% of days and last on average for 6.6 hours; (2) outages do not affect an average business due to the fact that the majority are not even connected; (3) however, the effects are large for the sub-sample of businesses highly reliant on power (those with electrical appliances), and as a result of blackouts, those businesses lose 25% of daily profits compared to non-outage days; (4) the profit losses are permanent - there is no evidence of profit increases in the following days; (5) the income shock results in reduced total weekly household-level expenditures, and affected households spend 4.8% less for every outage experienced during the week. My results suggest that outages have limited average impacts on small business owners, but businesses relying on electricity to generate income are heavily affected. My second chapter is a pilot study for the first chapter, which informed the design and development of the main study. In this chapter, I study effects of electricity interruptions among market vendors across 5 markets in Lilongwe, Malawi. I overcome several empirical challenges associated with estimation of the effects. First, due to data limitations and heavy under-reporting of outage instances, I aggregate definition of an outage to a market level and use various constructions of outages definitions to verify the results. Second, I use a bootstrap method estimate clustered standard errors with a few clusters. To estimate the effects, I use the detailed logbooks kept by small businesses owners to study the short-term effects of blackouts on business outcomes. Since outages are so frequent, only 31% of market vendors select into electricity dependent operations. These businesses are affected by power outages and lose 7-16% of revenues on days of blackouts. Due to likely presence of measurement error in the independent variable, I conclude that the presented effects are lower bounds of the true impacts.The third chapter, co-authored with Jonathan Robinson (Associate Professor of economics, University of California at Santa Cruz) and Shilpa Aggarwal (Assistant Professor of Economics and Public Policy at Indian School of Business), focuses on the effects of provision of savings accounts to micro-entrepreneurs in a developing country. Labeling savings accounts for goals might increase savings for those goals but limit liquidity for other uses. We conduct a field experiment with small business owners in urban Malawi, in which we randomly offer people one or multiple labeled savings accounts - mobile money or simple lockboxes. Since access to a secure place to save is the same for those with one as with multiple accounts, any effect of the incremental account should be due to labeling. We show that (1) the savings products were popular, especially the box (95% of respondents used the box at least twice within 4 months compared to 53% in the mobile money group); (2) takeup of multiple lockboxes was high (66\% of those offered multiple boxes actually used it at least once) compared to 6% in mobile money groups; (3) total deposits across all saving sources were higher for the group with multiple boxes compared to the single box holders; that (4) the savings products had a number of effects on downstream outcomes, including increased labor supply in farming activities, increased spending on certaincategories such as holiday spending and school supplies for children; but that (5) there is no evidence that the labeled accounts limitedliquidity of money for non-labeled purposes, and we do not detect that mental accounting deterred households from using savings accountto deal with health shocks, even though about half of respondents reported that they were reluctant to withdraw from the account. Lastly,we conclude that mobile money technologies are not able to induce the same saving behaviors as lockboxes likely due to higher transactional costs

Universality and sharp matrix concentration inequalities

We show that, under mild assumptions, the spectrum of a sum of independent random matrices is close to that of the Gaussian random matrix whose entries have the same mean and covariance. This nonasymptotic universality principle both explains the phenomenon behind classical matrix concentration inequalities such as the matrix Bernstein inequality, and yields new sharp matrix concentration inequalities for general sums of independent random matrices when combined with the recent Gaussian theory of Bandeira, Boedihardjo, and Van Handel. As an application of our main results, we prove strong asymptotic freeness of a very general class of random matrix models with non-Gaussian, nonhomogeneous, and dependent entries.Comment: 56 page

Replication package for "Is Digital Credit Filling a Hole or Digging a Hole? Evidence from Malawi"

Brailovskaya, Valentina, Pascaline Dupas & Jonathan Robinson (2023). Is Digital Credit Filling a Hole or Digging a Hole? Evidence from Malawi. Economic Journal

Is Digital Credit Filling a Hole or Digging a Hole? Evidence from Malawi

Digital credit has expanded rapidly in Africa, mostly in the form of short-term, high-interest loans offered via mobile money. Loan terms are often opaque and consumer financial literacy is low, providing opportunities for predatory lending. A regression discontinuity analysis shows no negative effect of access to digital loans on financial well-being, but the majority of borrowers fail to repay on time and incur high late fees. We randomize exposure to a short phone-based financial literacy intervention. The intervention improved knowledge and marginally improved loan repayment but increased loan demand, increasing overall default risk

IFAD RESEARCH SERIES 33 - The impact of the adoption of CGIAR's improved varieties on poverty and welfare outcomes: a systematic review

This paper examines the impact of agricultural research on poverty and welfare by conducting a systematic review of experimental and quasi-experimental impact evaluations of improved varieties disseminated by CGIAR between 2007 and 2015. The analysis focuses on the adoption of improved seeds, and specifically yield-increasing varieties, examining their direct causal impact from uptake on crop productivity gains, increased income and poverty reduction. The paper finds that agricultural research and improved varieties have been effectively contributing to productivity gains, however more efforts are needed to improve the evidence base to validate the positive impacts and encourage donors to invest in this area of agricultural research