Comparing "challenge-based" and "code-based" internet voting verification implementations

Internet-enabled voting introduces an element of invisibility and unfamiliarity into the voting process, which makes it very different from traditional voting. Voters might be concerned about their vote being recorded correctly and included in the final tally. To mitigate mistrust, many Internet-enabled voting systems build verifiability into their systems. This allows voters to verify that their votes have been cast as intended, stored as cast and tallied as stored at the conclusion of the voting period. Verification implementations have not been universally successful, mostly due to voter difficulties using them. Here, we evaluate two cast as intended verification approaches in a lab study: (1) "Challenge-Based" and (2) "Code-Based". We assessed cast-as-intended vote verification efficacy, and identified usability issues related to verifying and/or vote casting. We also explored acceptance issues post-verification, to see whether our participants were willing to engage with Internet voting in a real election. Our study revealed the superiority of the code-based approach, in terms of ability to verify effectively. In terms of real-life Internet voting acceptance, convenience encourages acceptance, while security concerns and complexity might lead to rejection

Effects of Acacia seyal and biochar on soil properties and sorghum yield in agroforestry systems in South Sudan

We studied the effects of Acacia seyal Del. intercropping and biochar soil amendment on soil physico-chemical properties and sorghum (Sorghum bicolor L.) yields in a two-year field experiment conducted on a silt loam site near Renk in South Sudan. A split-plot design with three replications was used. The main factor was tree-cropping system (dense acacia + sorghum, scattered acacia + sorghum, and sole sorghum) and biochar (0 and 10 Mg ha(-1)) was the subplot factor. The two acacia systems had lower soil pH, N and higher C/N ratios compared to the sole sorghum system. Biochar significantly increased soil C, exchangeable K+ contents, field capacity and available water content, but reduced soil exchangeable Ca2+ and effective CEC, and had no effect on soil pH. Acacia intercropping significantly reduced sorghum grain yields while biochar had no significant effect on sorghum yields. The land equivalent ratio (LER) for sorghum yield was 0.3 for both acacia systems in 2011, with or without biochar, but increased in 2012 to 0.6 for the scattered acacia system when combined with biochar. The reduction in sorghum yields by the A. seyal trees was probably due to a combination of competition for water and nutrients and shading. The lack of a yield response to biochar maybe due to insufficient time or too low a dosage. Further research is needed to test for the effects of tree intercropping and biochar and their interactions on soil properties and crop yields in drylands.Peer reviewe

Enterocolitis necrotizante en recién nacidos ingresados en el Servicio de Neonatología del Hospital Escuela "Carlos Roberto Huembes" en el período comprendido de Enero 2011 a Diciembre 2013

La enterocolitis necrotizante en el recién nacido presenta un amplio espectro de manifestaciones clínicas, caracterizándose principalmente por la tríada de distensión abdominal, sangramiento gastrointestinal y neumatosis intestinal. A pesar del avance en el cuidado intensivo neonatal, persiste como una enfermedad grave, que afecta habitualmente al recién nacido pretérmino, especialmente de muy bajo peso

Engrais : atout ou menace pour l'agriculture

Selon les données disponibles, la population mondiale devrait dépasser le chiffre de 6,5 milliards d'habitants d'ici à l'an 2000. C'est dans les pays en développement que la croissance démographique devrait être la plus forte. Pour pouvoir nourrir convenablement cette population, il faudrait que la production agricole représente environ le double de celle de 1980. Peut-on atteindre cet objectif sans un recours accru aux engrais ? Quelle attitude adopter face aux risques désormais largement associés à l'usage des engrais ? Dans les pays possédant des systèmes agricoles très évolués, l'expérience a montré qu'au cours des cent dernières années,l'accroissement des rendements était imputable pour 60 % et plus à l'utilisation d'engrais minéraux et, dans une certaine mesure, de fumures, en fonction des disponibilités. Les engrais minéraux et organiques ont non seulement contribué à accroître les rendements mais aussi à améliorer la qualité de l'alimentation et à poser les bases d'un développement agricole au sens le plus large. Les bénéfices résultant d'une utilisation efficace des engrais ont été ressentis à l'échelle des économies nationales comme à l'échelle du simple agriculteur. En ce qui concerne les pays en développement, il faut tout d'abord prendre conscience du fait que l'agriculture doit être prioritaire si l'on vise à atteindre l'autosuffisance alimentaire et à assurer la prospérité de la nation. Ce n'est pas en établissant d'abord les bases d'une industrie lourde que l'on satisfera les besoins alimentaires des hommes qui font fonctionner les machines. En outre, il est nécessaire que l'entreprise agricole soit orientée vers la recherche du profit afin de stimuler les agriculteurs. A cette fin, l'introduction des engrais est peut-être le facteur dont l'impact immédiat est le plus fort dans la plupart des pays en développement. Si, dans les pays industrialisés, il est prouvé que l'usage abusif d'engrais est dangereux pour l'homme et pour l'environnement, les pays en développement, au contraire, gagneraient à en employer davantage, à condition toutefois de le faire de manière judicieuse et efficace. En règle générale, dans les régions humides et notamment dans les zones tropicales et subtropicales où vit la majorité de la population, la plupart des sols sont pauvres en substances nutritives. Les éléments qu'ils contiennent permettent habituellement 2 à 3 ans d'exploitation suivis de 20 à 30 années de jachère. Certains partisans de l'agriculture dite durable pensent que différents types de fumures et de paillis organiques suffiraient à remédier à ce problème. Toutefois, on ne pourrait jamais disposer de fumier en quantité suffisante et il ne serait pas non plus possible de cultiver suffisamment de légumineuses sans amendement considérable du sol. Qu'en est-il de la productivité des sols qui ont subi l'application d'engrais pendant de longues périodes? Leur structure est elle détruite? Il semble que les parcelles de Broadbalk appartenant au Centre expérimental de Rothamsted au Royaume-uni, sur lesquelles on applique des engrais chimiques depuis 1843, soient aujourd'hui plus productives que jamais. Un sol portant des cultures rentables et qui reçoit des engrais est beaucoup moins susceptible de s'éroder dans les pentes qu'un même sol portant des cultures dont la croissance est médiocre. Le couvert d'une plante disposant de substances nutritives suffisantes est plus développé et son système radiculaire, plus étendu, possède un pouvoir d'agrégation plus important. La plante est ainsi mieux protégée contre les agressions dues au vent et à l'eau. Les effets résiduels de la production organique accrue jouent également un rôle important dans l'amélioration de l'agrégation du sol favorisée par l'augmentation des résidus organiques frais. Les physiologistes soulignent le rôle des végétaux dans la purification de l'air. En effet, les végétaux absorbent le dioxyde de carbone (CO2) de l'atmosphère pour la photosynthèse des hydrates de carbone et rejettent de l'oxygène (O2). Selon un auteur, un champ de mais produisant 6 300 kg de grain à l'hectare absorbe environ 18,5 tonnes de CO2 présent dans l'atmosphère et fournit quelque 15 tonnes d'O2, soit une quantité suffisante pour couvrir les besoins de 30 personnes pendant un an. L'augmentation de la production végétale au moyen des engrais présente un avantage certain lorsque l'on connaît les quantités croissantes de CO2 rejetées dans l'atmosphère par les activités humaines. Quels risques l'utilisation généralisée des engrais présente-t-elle pour l'environnement ? On parle généralement d'eutrophisation des eaux de surface, de potentiel de toxicité des composés azotés (NO3) présents en grande quantité dans les nappes souterraines et les eaux de surface, de dommages aux cultures et aux sols par la destruction du cycle naturel de l'azote. Cependant, l'utilisation judicieuse des engrais offre des bénéfices potentiels considérables, tout en minimisant les risques. Les opinions émises dans cette tribune libre n'engagent que leurs auteurs. Elles ne sauraient être attribuées au CTA.Selon les données disponibles, la population mondiale devrait dépasser le chiffre de 6,5 milliards d'habitants d'ici à l'an 2000. C'est dans les pays en développement que la croissance démographique devrait être la plus forte. Pour pouvoir..

Fertilizers - a benefit or a hazard to agriculture?

R J Olembo Professor R J Olembo Is a Kenyan geneticist currently serving at the United Nations Environment Programme as Deputy Assistant Executive Director. Before joining UNEP, he held academic positions at Makerere University, Uganda and the University of Nairobi where he was Professor of Botany. Current data indicate that the world population will reach over 6.5 billion by the year 2000 and that the Increase will be greatest In the developing countries. So, to feed the growing population adequately, food production needs to be approximately doubled from the 1980 output. Can this be achieved without increased use of fertilizers? And if fertilizers are necessary, what about the risks now widely associated with fertilizer use In the mind of the public In Europe and North America? Experience in countries with highly developed agricultural systems over the last 100 years or so has shown that 60% and more of increased yields are due to the use of mineral fertilizers and to some extent manures, where these are readily available. In addition to increased yields inorganic and organic fertilizers have done much to improve the quality of food and have provided the preconditions for agricultural development in the broadest sense. An efficient use of fertilizers has proved to be highly advantageous to the economies of the various countries no less than to the individual farmer. Where developing countries are concerned, it should be realized that agriculture must come first in the path to national prosperity and in their plans for food self-sufficiency. Establishment of a heavy industry base first will not meet the nutritional needs of the people manning the machines. It is further necessary that the entire agricultural enterprise be profit motivated to provide incentive to the farmers concerned. Introduction of fertilizer has perhaps greater immediate impact than any other input for effecting the latter objective in most farming situations of the developing world. While there is demonstrable evidence in industrialized countries that excessive fertilizer use may cause hazards to human health and to the environment, the case in the developing world is that more could be used beneficially. That is providing it is always used in an efficient and judicious manner. In general, most soils in humid regions of the world, especially those in subtropical and tropical areas where a majority of the people live are poor in nutrients. Inherent nutrient supplies commonly will allow only 2-3 years economic cropping followed by 20-30 years bush fallow. Some proponents of the so-called sustainable agriculture think that the situation can be corrected simply on the basis of different types of organic manures and mulches. But quantities of manure required would not be available, nor would it be possible to grow sufficient amounts of legumes without extensive soil amendments. What about the productivity of soils which have been subjected to long periods of fertilizer treatment? Is the structure of the soils destroyed? It has been said that the Broadbalk plots of Rothamsted Experimental Station in the UK, on which chemical fertilizers have been applied since 1843, are more productive today than at any time in the recorded past. The aggregated action from enhanced root proliferation and greater amount of decaying residues from well fertilized crops have been reported to help make soils more friable, tillable and receptive to water. The type of farming practiced in the highly developed countries of the world would be quite impossible today without fertilizers. More than 20 years ago, it was established that, depending on soil conditions and type of crop, the yield foregone would range from modest to severe even in the first year fertilizer was excluded. Productivity foregone by totally excluding. fertilizer use would have to be made up by bringing more land under the plough, land that should never be cultivated because, using it in this fashion would add to environmental damage. A well fertilized soil supporting a thriftily growing crop is much less prone to erosion in sloping positions than a corresponding soil supporting a poor crop. The greater surface canopy and the greater binding action of a more prolific root system accompanying the crop that enjoys adequate nutrition provide protection against adverse water and wind action. The residual effects of the greater organic production are significant, too, in the improved soil aggregation imparted by the larger quantity of fresh organic return. Physiologists stress the role of living plants in air purification, absorbing CO2 from the atmosphere for use in the photosynthesis of carbohydrates and releasing O2. One source has estimated that some 18.5 short tonnes of CO2 is removed from the atmosphere over a maize field producing 6300kg grain/ha as approximately 15 tonnes of oxygen is realized, enough oxygen for about 30 people for a year. Stimulated vegetative production with the aid of fertilizers clearly means a real bonus as we take inventory of the increasing amounts of CO2 that man's activities are releasing into the atmosphere. How serious is the impact of widespread fertilizer use on the environment? The most commonly cited hazards are the eutrophication of surface waters the toxicity potentials of high NO3 levels in the ground and surface waters, crop damage, and damage to soils by destruction of the natural N cycle. If fertilizers are used judiciously, these risks are negligible while the potential benefits are considerable. The views expressed are those of the author and do not necessarily reflect those of CTA.R J Olembo Professor R J Olembo Is a Kenyan geneticist currently serving at the United Nations Environment Programme as Deputy Assistant Executive Director. Before joining UNEP, he held academic positions at Makerere University, Uganda and the..

Institutional aspects of sanitary and phytosanitary issues in ECOWAS trade

The Economic Community of West African States (ECOWAS) has accepted trade liberalization and globalization as important policy directions. West African trade with Europe and the United States is already much greater than trade with other developed countries or intra-regional trade, although trading with developed countries may entail considerable difficulties due to trade regulations and the need to conform to Sanitary and Phytosanitary (SPS) standards. There is generally a low level of awareness of quality standards among produce exporters in West Africa. SPS focal points are not established in all countries, which makes it difficult for exporters to check on standards and requirements. Frequent changes to standards, excessive procedural requirements, high costs for testing and certification, and a lack of transparency in the application of standards combine to compromise the ability of many countries to comply effectively with SPS. Many West African countries have not upgraded their national SPS systems in response to the introduction of the SPS Agreement, leading to differences between local and international standards that makes meeting standards difficult for firms that do business in multiple markets. There also is insufficient testing capability to meet the needs for international trade and a lack of regional coordination. Standards application is not enforced in a number of countries, but others have set up institutions for testing, certification, and quality control of both domestic products and imported goods. The effectiveness of these agencies often is weak due to inadequate equipment, a dearth of skilled technical personnel, inability to assess risks, inadequate laboratory accreditation, and a lack of enforcement

Institutional aspects of sanitary and phytosanitary issues in ECOWAS trade

The Economic Community of West African States (ECOWAS) has accepted trade liberalization and globalization as important policy directions. West African trade with Europe and the United States is already much greater than trade with other developed countries or intra-regional trade, although trading with developed countries may entail considerable difficulties due to trade regulations and the need to conform to Sanitary and Phytosanitary (SPS) standards. There is generally a low level of awareness of quality standards among produce exporters in West Africa. SPS focal points are not established in all countries, which makes it difficult for exporters to check on standards and requirements. Frequent changes to standards, excessive procedural requirements, high costs for testing and certification, and a lack of transparency in the application of standards combine to compromise the ability of many countries to comply effectively with SPS. Many West African countries have not upgraded their national SPS systems in response to the introduction of the SPS Agreement, leading to differences between local and international standards that makes meeting standards difficult for firms that do business in multiple markets. There also is insufficient testing capability to meet the needs for international trade and a lack of regional coordination. Standards application is not enforced in a number of countries, but others have set up institutions for testing, certification, and quality control of both domestic products and imported goods. The effectiveness of these agencies often is weak due to inadequate equipment, a dearth of skilled technical personnel, inability to assess risks, inadequate laboratory accreditation, and a lack of enforcement