164 research outputs found
Impact of multi-micronutrient fortified rice on hemoglobin, iron and vitamin A status of Cambodian schoolchildren : a double-blind cluster-randomized controlled trial
In Cambodia, micronutrient deficiencies remain a critical public health problem. Our objective was to evaluate the impact of multi-micronutrient fortified rice (MMFR) formulations, distributed through a World Food Program school-meals program (WFP-SMP), on the hemoglobin concentrations and iron and vitamin A (VA) status of Cambodian schoolchildren. The FORISCA-UltraRice+NutriRice study was a double-blind, cluster-randomized, placebo-controlled trial. Sixteen schools participating in WFP-SMP were randomly assigned to receive extrusion-fortified rice (UltraRice Original, UltraRice New (URN), or NutriRice) or unfortified rice (placebo) six days a week for six months. Four additional schools not participating in WFP-SMP were randomly selected as controls. A total of 2440 schoolchildren (6-16 years old) participated in the biochemical study. Hemoglobin, iron status, estimated using inflammation-adjusted ferritin and transferrin receptors concentrations, and VA status, assessed using inflammation-adjusted retinol-binding protein concentration, were measured at the baseline, as well as at three and six months. Baseline prevalence of anemia, depleted iron stores, tissue iron deficiency, marginal VA status and VA deficiency were 15.6%, 1.4%, 51.0%, 7.9%, and 0.7%, respectively. The strongest risk factors for anemia were hemoglobinopathy, VA deficiency, and depleted iron stores (all p < 0.01). After six months, children receiving NutriRice and URN had 4 and 5 times less risk of low VA status, respectively, in comparison to the placebo group. Hemoglobin significantly increased (+0.8 g/L) after three months for the URN group in comparison to the placebo group; however, this difference was no longer significant after six months, except for children without inflammation. MMFR containing VA effectively improved the VA status of schoolchildren. The impact on hemoglobin and iron status was limited, partly by sub-clinical inflammation. MMFR combined with non-nutritional approaches addressing anemia and inflammation should be further investigated
Sediment wave-induced channel evolution following the 2006 avulsion of the Suncook River in Epsom, New Hampshire
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2008.Includes bibliographical references (p. 83-91).Large volumes of sediment can be released into a river when an avulsion carves a new channel in the landscape. Gilbert (1917) described the evolution of a similar pulse of material from mining along the Sacramento River, California as a sediment wave. Sediment waves are transient accumulations of sand and gravel that locally increase the elevation of the bed and reduce the transport capacity of the channel, and diffuse and translate down the channel over time. The Suncook River in Epsom, New Hampshire, avulsed in May 2006. This event created a new channel and mobilized approximately 100,000 m3 of sand into the river in a period of 12 to 24 hours (Perignon, 2007; Wittkop et al., 2007). In April 2007, a new channel formed through a meander bend downstream of the site of the first avulsion, where sediments mobilized the year before had increased the bed elevation by one meter. We propose that the material released in 2006 is traveling down the channel as a sediment wave, increasing the elevation of the bed and driving avulsions. The purpose of this study is to model the evolution of a sediment wave in the Suncook River in order to understand how it can increase the risk of floods and avulsions in the system over time. We developed a mathematical model using the equations of Lisle et al. (1997, 2001) to observe the evolution of the sediment wave under bankfull conditions. We found that the wave evolved mostly through diffusion and showed minimal translation downstream. These findings suggest that the risk of avulsions will be contained near the center of mass of the sediment wave, which we place near the site of the 2007 meander cutoff. Likewise, the diffusive nature of the wave implies that the river could reach a new equilibrium profile with no restoration work and without significantly affecting populated areas downstream.by Mariela C. Perignon.S.M
Longitudinal study assessing the return of chloroquine susceptibility of Plasmodium falciparum in isolates from travellers returning from West and Central Africa, 2000-2011.
BACKGROUND: Chloroquine (CQ) was the main malaria therapy worldwide from the 1940s until the 1990s. Following the emergence of CQ-resistant Plasmodium falciparum, most African countries discontinued the use of CQ, and now promote artemisinin-based combination therapy as the first-line treatment. This change was generally initiated during the last decade in West and Central Africa. The aim of this study is to describe the changes in CQ susceptibility in this African region, using travellers returning from this region as a sentinel system. METHODS: The study was conducted by the Malaria National Reference Centre, France. The database collated the pfcrtK76T molecular marker for CQ susceptibility and the in vitro response to CQ of parasites from travellers' isolates returning from Senegal, Mali, Ivory Coast or Cameroon. As a proxy of drug pressure, data regarding CQ intake in febrile children were collated for the study period. Logistic regression models were used to detect trends in the proportions of CQ resistant isolates. RESULTS: A total of 2874 parasite isolates were genotyped between 2000-2011. The prevalence of the pfcrt76T mutant genotype significantly decreased for Senegal (from 78% to 47%), Ivory Coast (from 63% to 37%), Cameroon (from 90% to 59%) and remained stable for Mali. The geometric mean of the 50% inhibitory concentration (IC50) of CQ in vitro susceptibility and the proportion of resistant isolates (defining resistance as an IC50 value > 100 nM) significantly decreased for Senegal (from 86 nM (59%) to 39 nM (25%)), Mali (from 84 nM (50%) to 51 nM (31%)), Ivory Coast (from 75 nM (59%) to 29 nM (16%)) and Cameroon (from 181 nM (75%) to 51 nM (37%)). Both analyses (molecular and in vitro susceptibility) were performed for the 2004-2011 period, after the four countries had officially discontinued CQ and showed an accelerated decline of the resistant isolates for the four countries. Meanwhile, CQ use among children significantly deceased in this region (fixed effects slope = -0.3, p < 10-3). CONCLUSIONS: An increase in CQ susceptibility following official withdrawal of the drug was observed in travellers returning from West and Central African countries. The same trends were observed for molecular and in vitro analysis between 2004-2011 and they correlated to the decrease of the drug pressure
Are Realized Volatility Models Good Candidates for Alternative Value at Risk Prediction Strategies?
The Effect of Monetary Policy on Bank Wholesale Funding
We study how monetary policy affects the funding composition of the banking sector. When monetary tightening reduces the retail deposit supply owing to, for example, a decrease in bank reserves or in money demand, banks try to substitute the deposit outflows with more wholesale funding in order to mitigate the policy impact on their lending. Banks have varying degrees of accessibility to wholesale funding sources because of financial frictions, and those banks that are large or that have a greater reliance on wholesale funding increase their wholesale funding more. As a result, monetary tightening increases both the reliance on and the concentration of wholesale funding within the banking sector, indicating that monetary tightening could increase systemic risk. Our findings also suggest that introducing liquidity requirements can bolster monetary policy transmission through the bank lending channel by limiting the funding substitution of large banks
Analysis of the May 2006 Suncook River avulsion in Epsom, New Hampshire
Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2007.Cataloged from PDF version of thesis.Includes bibliographical references (pages 60-66).Avulsions, or rapid changes in the location of a river, usually occur in environments such as deltas, floodplains, and alluvial fans where net-deposition can raise the bed of the river above its floodplain. Avulsions are less frequent in transient landscapes, such as New England, where topography and hydrography are still responding to recent glaciation. One of these rare avulsions occurred during a 100-year flood on the Suncook River, Epsom, NH, between May 14 and 15,2006. We studied the Suncook River event to develop a model for the drivers of avulsions in transient landscapes. We suggest that a strong substrate in the parent channel, such as bedrock or immobile boulders, can facilitate an avulsion by preventing incision and driving water overbank. Easily erodible substrates in the path of the new channel can also contribute to avulsions by allowing a knickpoint to migrate quickly upstream and create a channel with a more favorable slope during a single flood. Based on Slingerland and Smith's (2004) model, we also propose that a low water-surface slope in the parent channel could be a direct driver for avulsions. In the Suncook River, this low water-surface slope was created in the backwater of a small mill dam in the parent channel. A 200-year flood that occurred in the Suncook River in 1936 did not create an avulsion. We suggest that ice floats could have damaged the dam and increased the water-surface slope of the parent channel, making an avulsion less favorable and reducing the depth of water flowing overbank. The topography in the path of the 2006 avulsion, which was lowered by activity in a sand pit starting in the 1960s, probably prevented water from finding a new path. We believe that these anthropogenic modifications directly contributed to the occurrence of the May 2006 avulsion in the Suncook River. These conditions are common throughout New England, and could increase the risk of avulsions in the region.by Mariela C. Perignon.S.B
Option Pricing with Scheduled and Unscheduled News Flows.
In this paper, we develop alternative models to price derivative securities when the underlying asset may be subject to jumps. These models allow for two kinds of jumps: scheduled jumps which are caused by information for which the disclosure data is known in advance (e.g. earnings announcements) and unscheduled jumps which are caused by information for which neither the disclosure date nor the informational content is known in advance by market participants (e.g. mergers, new strategic decisions).PRICES ; FINANCIAL MARKET
Evolution of Market Uncertainty around Earnings Announcements.
This paper investigates, theoretically and empirically, the dynamic of the implied volatility (ISD) around earnings announcements dates. The volatility implied in option prices can be interpreted as the market's expected level of volatility over the remaining life of the option. In this framework the paper proposes a theoretical model of the evolution of the ISD that takes into accound two well-known features of the instantaneous volatility: volatility clustering and the leverage effect. The model indicates that the ISD should decrease after an earnings announcement except after a bad news where it should be stable or even increase. An empirical investigation is conducted on the Swiss market over the period 1989-1998.The results confirm the main implications of the theoretical model.UNCERTAINTY ; INCOME ; FINANCIAL MARKET
How do Illiquid Assets Improce Portfolio Performance? The Case of Bordeaux Wine.
Using a large sample of auctions results of prestigious Bordeaux wines, we provide an analysis of the price formation of wine through auctions sales. Estimating an hedonic price function, we identify the most relevant characteristics influencing the price of Bordeaux wines during auctions sales. The Repeat-Sale Regression (RSR) methodology is used to construct a wine index for the period January 1994-June 1997. We compare the evolution of wine price with several financial indices. We finally study the impact of an investment in wine on the risk-return characteristics of a diversified portfolio of a risk-averse investor.FINANCIAL MARKET ; AUCTIONS
Demand for Football and Intra-Match Winning Probability: an Essay on the Glorious Uncertainty of Sports.
The aims of this study are (i) to identify the main determinants of the demand for French Premiere Division football matches using all matches played during the 1997/1998 season, (ii) to estimate a team-specific probability of success, and (iii) to propose an updating process for the intra-match winning probability.RISK ; UNCERTAINTY ; SPORTS
- …
