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Introduction Widespread white matter abnormalities and alterations in glutamate levels have been reported in patients with schizophrenia. We hypothesized that alterations in white matter integrity and glutamate levels in individuals at clinical high risk (CHR) for psychosis are associated with the subsequent development of psychosis. Methods Participants included 33 antipsychotic naive CHR (Female 7/Male 26, Age 19.55 (4.14) years) and 38 healthy controls (Female 10/Male 28, Age 20.92 (3.37) years). Whole brain diffusion tensor imaging for fractional anisotropy (FA) and right frontal white matter proton magnetic resonance spectroscopy for glutamate levels were acquired. CHR participants were clinically followed for 2 years to determine conversion to psychosis. Results CHR participants that transitioned to psychosis (N = 7, 21%) were characterized by significantly lower FA values in the posterior thalamic radiation compared to those who did not transition and healthy controls. In the CHR group that transitioned to psychosis only, positive exploratory correlations between glutamate levels and FA values of the posterior thalamic radiation and the retrolenticular part of the internal capsule and a negative correlation between glutamate levels and the cingulum FA values were found. Conclusion The results of the present study highlight that alterations in white matter structure and glutamate are related with the conversion to psychosis.

Risk calculators for prediction of conversion of Clinical High-Risk (CHR) individuals to syndromal psychosis have recently been developed and have generated considerable clinical use and research interest. Predictor variables in these calculators have been clinical rather than biological, and our goal was to incorporate a neurochemical imaging measure into this framework and assess its impact on prediction. We combined striatal glutamate 1H MRS data with the SIPS symptoms identified by the Columbia Risk Calculator as having the greatest predictive value in order to develop an imaging-based risk calculator for conversion to psychosis. We evaluated the calculator in 19 CHR individuals, 7 (36.84%) of whom converted to syndromal psychosis during the 2-year follow up. The receiver operating characteristic (ROC) curve for the logistic model including only striatal glutamate and visual perceptual abnormalities showed an AUC = 0.869 (95% CI = [0.667, 1.000]) and AUCoa = 0.823, with sensitivity of 0.714, specificity of 0.917, positive predictive value of 0.833, and negative predictive value of 0.846. These results represent modest improvements over each of the individual ROC curves based on either striatal glutamate or visual perceptual abnormalities alone. The preliminary model building and evaluation presented here in a small CHR sample suggests that the approach of incorporating predictive imaging measures into risk classification is not only feasible but offers the potential of enhancing risk assessment.

Bubble size distribution (BSD) is a factor that is well known for influencing the performance of many industrial processes, such as froth flotation. The most commonly used method for measuring bubble size consists of processing photographs of the bubbles. However, the source code of the algorithms for performing the image processing has been seldom published. This article addresses the above by presenting a comprehensive open-source software for processing images of bubbles, allowing researchers to quantify BSD. This software - Bubble Analyser - includes a standard image processing algorithm that was tested against manually segmented images, showing errors under 5% in the calculation of the Sauter mean diameter, the most common descriptor of BSD. Additionally, Bubble Analyser has been designed to easily incorporate new segmentation algorithms developed by other researchers, in order to expand the software capabilities, allow for algorithm comparisons, and foster collaboration in research.

Introduction Recent studies have observed that patients with treatment-resistant schizophrenia as well as patients with schizophrenia who do not respond within a medication trial exhibit excess activity of the glutamate system. In this study we sought to replicate the within-trial glutamate abnormality and to investigate the potential for structural differences and treatment-induced changes to improve identification of medication responders and non-responders. Methods We enrolled 48 medication-naive patients in a 4-week trial of risperidone and classified them retrospectively into responders and non-responders using clinical criteria. Proton magnetic resonance spectroscopy and T1-weighted structural MRI were acquired pre- and post-treatment to quantify striatal glutamate levels and several measures of subcortical brain structure. Results Patients were classified as 29 responders and 19 non-responders. Striatal glutamate was higher in the non-responders than responders both pre- and post-treatment (F1,39 = 7.15, p = .01). Volumetric measures showed a significant group x time interaction (t = 5.163, Conclusions Combining anatomic measures with glutamate levels offers the potential to enhance classification of responders and non-responders to antipsychotic medications as well as to provide mechanistic understanding of the interplay between neuroanatomical and neurochemical changes induced by these medications. Ethical statement The study was approved by the Ethics and Scientific committees of the Instituto Nacional de Neurologia y Neurocirugia in Mexico City. All participants over 18 years fully understood and signed the informed consent; in case the patient was under 18 years, informed consent was obtained from both parents. Participants did not receive a stipend.

Liberation is a key driver in all mineral separation processes as it limits the maximum possible grade for a given recovery. In flotation, this is further complicated by the fact that it is surface exposure of the floatable minerals that determines the ultimate performance. Liberation, grade and surface exposure are commonly quantified using Scanning Electron Microscopy coupled to Energy Dispersive X-ray spectroscopy (SEM/EDX) analysis of polished sections. The intrinsically 2D nature of this technique can result in significant sampling errors and stereological effects that can affect the quantification of the ore’s textural characteristics. X-ray microCT (XMT) is an imaging method that can non-invasively and non-destructively delineate ore fragments in 3D, thus providing an alternative method that eliminates the need for stereological corrections and readily provides surface exposure. A methodology and automated algorithm were developed for extracting this information from images of closely packed particles. By dividing these particles into classes based on both their surface exposure and grade, the extent to which there is preferential breakage of the particles can be assessed—an important consideration if sufficient surface liberation for good flotation performance is to be achieved at coarser particle sizes. Using low energy scanning simple 3D mineral maps can be obtained via XMT, allowing for the assessment of liberation and surface exposure for each mineral species. The methodology was tested on low grade porphyry copper ore as this is representative of the most commonly treated ore types for copper production.

Background Abnormally elevated levels of gamma-aminobutyric acid (GABA) in the medial prefrontal cortex (mPFC) have been reported in antipsychotic-free patients with schizophrenia. Whether such GABA elevations are also present in other brain regions and persist after antipsychotic treatment has not been previously investigated. Methods Twenty-eight antipsychotic-naive patients with first-episode psychosis (FEP) and 18 healthy control subjects completed the study. Following baseline proton magnetic resonance spectroscopy scans targeting the mPFC and a second region, the dorsal caudate, patients with FEP were treated with oral risperidone for 4 weeks at an initial dose of 1 mg/day that was titrated as necessary based on clinical judgment. After the 4-week treatment period, both groups were brought back to undergo outcome magnetic resonance spectroscopy scans, which were identical to the scans conducted at baseline. Results At baseline, higher GABA levels were found both in the mPFC and in the dorsal caudate of patients with FEP compared with healthy control subjects. Following 4 weeks of antipsychotic treatment, GABA levels in patients with FEP decreased relative to baseline in the mPFC, but decreased only at the trend level relative to baseline in the dorsal caudate. For either brain region, GABA levels at 4 weeks or posttreatment did not differ between patients with FEP and healthy control subjects. Conclusions The results of the present study documented elevations of GABA levels both in the mPFC and, for the first time, in the dorsal caudate of antipsychotic-naive patients with FEP, which normalized in both regions following 4 weeks of antipsychotic treatment.

AimTo estimate the fraction of hospitalizations and deaths from COVID-19 attributable to chronic diseases due to poor nutrition and smoking in Mexico.MethodsWe used data from the Mexican surveillance system of COVID-19. We considered six chronic diseases (obesity, COPD, hypertension, diabetes, cardiovascular disease, and chronic kidney disease) to define a multimorbidity variable: no diseases, 1 disease, 2 diseases, or 3 or more diseases. We calibrated the database using bias quantification methods to consider the undiagnosed cases of chronic diseases. To estimate the risks of hospitalization and death due to chronic diseases, we fitted Poisson regression models with robust standard errors, adjusting for possible confounders. Using these risks, we calculated attributable fractions using the population attributable fraction (PAF).ResultsChronic diseases accounted for to 25.4% (24.8%, 26.1%), 28.3% (27.8%, 28.7%) and 15.3% (14.9%,15.7%) of the hospitalizations among adults below 40 years, 40 to 59, and 60 years and older respectively (95% CI). For COVID-19-related deaths, 50.1% (48.6%, 51.5%), 40.5% (39.7%, 41.3%), and 18.7% (18.0%, 19.5%) were attributable to chronic diseases in adults under 40 years, 40 to 59, and 60 years and older, respectively.ConclusionChronic diseases linked to malnutrition and tobacco use contributed to a higher burden of hospitalization and deaths from COVID-19 in Mexico, particularly among younger adults. Medical and structural interventions to curb chronic disease incidence and facilitate disease control are urgently needed.

In areas where the ambient temperature (AT) is above the thermo neutral (TN) zone of pigs, significant changes within a 24-h period occur, differently affecting the availability of amino acids (AA) within the same day. An experiment was conducted to analyze the serum concentrations (SC) of free AA in pigs exposed to diurnal variations in AT. Six pigs (27.1 ±1.3kg body weight) implanted with a thermometer to register the body temperature (BT) at 15-min intervals were used. Blood samples were collected on the last 3 d of the 14-d study, at 0700h (lowest AT), 1200h (mild HS), and 1600h (severe HS). The pigs received 1.2kg/d of an AA-supplemented, wheat-soybean meal diet, in two equal meals (0700 and 1900h). The AT and BT, recorded at 0700, 1200, and 1600h was: 30.6, 38.6, 41.1°C, and 38.2, 39.5, 40.3°C, respectively. The BT was significantly correlated (P < 0.001) with the AT. The SC (μM/mL) of Ile, Lys, Met, Val, Ala, Asn, and Pro were higher (P ≤ 0.01); Arg, Phe, Glu, and Tyr tended to be higher (P ≤ 0.10); but Cys was lower (P < 0.05) at 1200h than at 0700h. Lys was higher, Cys and Tyr were lower (P < 0.05), and Ile and Val tended to be higher (P ≤ 0.10) at 1600h than at 0700h. Serum Arg, Ile, Phe, Ala, Asn, Gln, Pro, Ser, and Tyr were lower (P < 0.05), and Leu and Val tended to be lower at 1600h than at 1200h. These data demonstrate that AT directly alters the BT of pigs, and that diurnal variations in AT differently affect their SC and availability of AA for growth.

This paper studies whether or not the distribution of the length of hospital stay data follows power-law probability. For hospitals differing in size and specialization, our evidence shows that length of stay is well fitted by power-law density, independently of hospital size. Moreover, failure rates differ across hospitals and are independent of hospital size and specialization.

This study analyzed the lipid profiles of two acid-tolerant mutants (M1 and M5) and a wild-type (WT) strain of Chlorella saccharophila. Six main types of compounds were identified in the lipid fractions: hydrocarbons, FAMEs (after transesterification of TAGs), free fatty acids, terpenes, sterols and fatty alcohols. Compared with the M1 and M5 mutant lines, the WT strain presented the highest relative abundance of hydrocarbons (73.63%), while the relative abundance of fatty acid methyl esters (FAMEs) obtained were higher in the M1 (28.39%) and M5 (29.17%) mutants than in the WT strain. High-value lipids, including terpenes and fatty alcohols, were also detected in higher proportions in the M1 and M5 mutants than in the WT strain, while sterols were only detected in the M1 and M5 mutants. These results show that C. saccharophila and its acid-tolerant mutants are a rich source of lipids with potential industrial applications.

Spanish Abstract: Este trabajo pretende contribuir a la mejora y modernizacion del Derecho de sociedades en Ecuador a traves de una serie de propuestas de reforma que han sido realizadas teniendo en cuenta las principales tendencias internacionales en materia de sociedades, asi como las particularidades juridicas, economicas e institucionales de Ecuador. En segundo lugar, y habida cuenta de que las caracteristicas de las empresas, el mercado de valores y el sistema judicial ecuatorianos presentan elementos comunes a otros paises de la comunidad iberoamericana, este documento tambien pretende ser de utilidad para otros paises de la region interesados en reformar su normativa societaria. Finalmente, y a traves del analisis economico, comparado y funcional que subyace en este trabajo, el presente articulo tambien pretende contribuir al objetivo que, desde los inicios del Instituto Iberoamericano de Derecho y Finanzas, ha constituido la principal razon de ser de esta institucion: la promocion de la mejora y modernizacion del debate academico y legislativo en la comunidad iberoamericana con la finalidad ultima de contribuir al diseno de un entorno regulatorio e institucional que favorezca el emprendimiento, la innovacion, la financiacion de empresas y el crecimiento economico. English Abstract: This paper seeks to provide some policy recommendations for the improvement and modernization of corporate law in Ecuador. These proposals have been based on the international literature and the particular features of Ecuador (that is, a country with many micro and small companies, state-owned enterprises, underdeveloped capital markets, unsophisticated courts, among other aspects). Secondly, since the legal, economic and institutional features of Ecuador can be found in other Latin American countries, this paper also seeks to be helpful to other countries in the region planning to reform their corporate laws. Finally, this paper seeks to contribute to the improvement and internationalization of the academic and policy debate in Ibero-America, with the ultimate purpose of advocating for legal and institutional reforms that can promote entrepreneurship, innovation, access to finance, and economic growth.

As one of the copper recovery processes, hydrometallurgy has gain impact due to its ability to process ore with average low grades at competitive prices compared with other metallurgical processes. Among hydrometallurgical processes the leaching stage, a process that is characterized by its significant temporal and spatial scale of operation, is critical. In spite of extensive developments in instrumentation in pyrometullurgical and concentrators plants, developments in heap leaching instrumentation has not reached the required level for a fully automated control system and furthermore for a stable operation. Computational tools, such us dynamic simulators, can help operators achieve the best performance of the heap using the available instrumentation. This paper presents the development and implementation of an integrated dynamic simulator and a decision support system (DSS) for hydrometallurgical processes with emphasis in heap leaching process. The dynamic simulator uses two dimensional models of fluid transport, transport of solutes and dissolution of copper in the leaching heap, to analyse the effects produced in the variables of interest, such as the consumption of acid, copper concentration in the PLS (Pregnant Leach Solution) and leaching times. The DSS, which is connected to the real time plant information system, gathers the information by sensors and laboratory analyses to perform an automatic on-line parameter estimation of the process and makes predictions to recommend to the operator both curing and leaching rates. Results show that the DSS achieves the identification and prediction with less than 6% of error, allowing the metallurgist to predict the leaching behaviour and take decisions with better information.

Treatment of new tuberculosis (TB) cases in Directly Observed Treatment Short Course (DOTS) programmes is believed to be the most valuable strategy for TB control. The aim of this study is to describe the experience of diagnosed cases of TB in a district hospital situated in a rural zone of Ethiopia and of “transferred out” TB cases from the hospital to their local health facilities using the DOTS programme spanning a period of 8years. Data collection was obtained by using a TB register book in a rural district hospital from 2004 to 2011. The collected information included the type of TB, age, HIV status, and treatment outcomes using standardized definitions; 6459 patients with all forms of TB were diagnosed. Twenty-eight percent were smear-positive pulmonary TB (PTB) cases, 28.97% were smear-negative PTB cases, and 42.8% were extra-pulmonary TB (EPTB). The global “transferred out” rate was 78.5% (5073/6459); the “transferred out” rate after diagnosis at hospital and before starting DOTS was 72.6% (4689/6459), and after finishing the intensive phase and admission was 21.8% (385/1770). The proportion of total cases “transferred out” in smear-negative PTB cases (70.2%) was less than smear-positive PTB cases (79.2%) (odd ratio [OR]: 0.81; 95% confidence interval [CI]: 0.76–0.87) and was higher in EPTB cases (83.3%) (OR: 1.15; 95% CI: 1.05–1.19). The percentage of “transferred out” after hospital admission was higher in HIV-positive cases (16.8%) than in HIV-negative cases (8.5%) (OR: 2.13; 95% CI: 1.28–3.53). In conclusion, district hospitals are still important facilities for the diagnosis of TB cases, particularly EPTB.

The main aim of this work is to achieve reproducing by means of a simulation study the behaviour of the daily inpatient activity and the length of the inpatient stay in Galician public hospitals. Another important issue is studying how the number of beds in the hospital affects inpatient activity, the length of the stays and, consequently, the waiting list. In order to simulate the daily inpatient activity we have fitted a normal distribution to real inpatient activity data observed in 2009, whereas the Parzen-Rosenblatt estimator has been considered for estimating non-parametrically the stay length distribution in the same period. Moreover, the effect of the number of beds on inpatient activity has been modelled by means of a linear regression model where the number of beds is the covariate and the median of daily inpatient activity is the response.A simulation study is also presented to show the practical behaviour of these procedures in two different scenarios: firstly, assuming that the effect of the number of beds does not exist, and then assuming that the number of hospital beds has a 'linear' influence on inpatient activity. In this way, the proposed study turns into an aid for analysing and modifying a complex hospital system, allowing consideration of far more detail and providing more reliable results than would otherwise be possible. Furthermore, it allows us to examine the drop in waiting list numbers due to new-bed allocations in a simple way. © 2011 Elsevier Ltd.

Train-based systems are the principal means of public transportation in many of the world's cities, and continue to grow in the face of rising demand. Expanding infrastructure is costly, however, and at a certain point becomes unsustainable. When this occurs the only feasible solution is to improve the management system. This can be done using on line approaches, such as pre-programming schedules that use historic information, or online approaches that employ system status information obtained during operation. In this paper the metro system is partitioned into sub-systems each of them associated to an agent based predictive controller in charge of local optimization. Each controller has its own state estimator that gives online information of the subsystem. By means of communication between agents the optimization of the whole metro system is achieved. The reduction in waiting times can be greater than 20%, depending on the ridership of the line.

As one of the alternative technological paths for copper recovery, hydrometallurgy has experienced high use intensity and a significant impact due to its ability to process ore with average and low grades at competitive prices compared to other metallurgical paths. In spite of instrumentation in pyrometullurgical and concentrators plants, developments in agglomeration and heap leaching instrumentation has not reached the required level for a fully automated control system. Variables such as agglomerates moisture content, size, shape, flowability, and internal and superficial moisture in heaps are difficult to measure in real time hindering the implementation of an automated control system. Since closing an automated feedback loop is not possible, a novel and powerful Hydrometallurgical Decision Support System (HDSS) has been developed that recommends control actions to operators of primary and fine crushing, agglomeration and heap leaching in an integrated manner. Also, the HDSS, which is connected to the real time plant information system, gathers the information by sensors and laboratory analyses to suggest to the metallurgist both curing and leaching rates, and if he approves, this new rates will be informed on the leaching operators interface. The HDSS main goal is to stabilize and increase the plant production while minimizing the energy consumption. To assess the HDSS performance, different strategies commonly used by the operators against the HDSS recommendations have been simulated. Results show that the HDSS achieves the proposed goal, decreasing the overall specific energy consumption and stabilizing the plant operation.

Urban Metro rail systems are subject to high and growing demand as the populations of major cities increase. A point may be reached where improving system management using advanced control is more attractive than expanding the network. Control schemes for strengthening system performance and therefore user satisfaction typically involve measuring certain system state variables such as the numbers of passengers aboard trains and waiting at stations. Given the high cost of installing the necessary sensors, an alternative methodology is proposed for online estimation of the two variables using a moving horizon optimization approach. Experiments performed on a dynamic simulator show that the variable values can be inferred by measuring only train dwell times and passengers entering stations, data on which are generally accessible without major investment. The level of accuracy of the estimates generated by the methodology is high enough to enable a model-based controller implemented in a real Metro system to achieve significant performance improvements.

The software development process is usually affected by many risk factors that may cause the loss of control and failure, thus which need to be identified and mitigated by project managers. Software development companies are currently improving their process by adopting internationally accepted practices, with the aim of avoiding risks and demonstrating the quality of their work. This paper aims to develop a method to identify which risk factors are more influential in determining project outcome. This method must also propose a cost effective investment of project resources to improve the probability of project success. To achieve these aims, we use the probability of success relative to cost to calculate the efficiency of the probable project outcome. The definition of efficiency used in this paper was proposed by researchers in the field of education. We then use this efficiency as the fitness function in an optimization technique based on genetic algorithms. This method maximizes the success probability output of a prediction model relative to cost. The optimization method was tested with several software risk prediction models that have been developed based on the literature and using data from a survey which collected information from in-house and outsourced software development projects in the Chilean software industry. These models predict the probability of success of a project based on the activities undertaken by the project manager and development team. The results show that the proposed method is very useful to identify those activities needing greater allocation of resources, and which of these will have a higher impact on the projects success probability. Therefore using the measure of efficiency has allowed a modular approach to identify those activities in software development on which to focus the project's limited resources to improve its probability of success. The genetic algorithm and the measure of efficiency presented in this paper permit model independence, in both prediction of success and cost evaluation.

Toxic brown fish meal that caused severe gizzard erosion in broiler chicks was used as the sole protein source in starter diets for Nile tilapia. Brown fish meal was assayed using 4-day-old broiler chicks to test its toxicity. Growth performance was compared among fish fed diets containing three levels of toxic brown fish meal and a control diet which contained non-toxic fish meal. Fish fed the diets containing the toxic fish meal exhibited reduced growth and protein utilization. Fish fed the nontoxic fish meal diet had significantly better weight gain (WG), 98.88 mg/day, specific growth rate (SGR), 5.30%/day, protein efficiency ratio (PER), 2.60, and apparent net nitrogen utilization (ANNU), 43.33%, than those fed the diets containing the toxic fish meal, named 1, 2 and 3, respectively, which showed WG 66.75, 57.94, and 62.04 mg/day, SGR 4.75, 4.53, and 4.65%/day, PER 2.06, 2.20, and 2,27, and ANNU 33.89, 37.17 and 37.34. There were no significant differences among dietary treatments in survival and Nile tilapia fry fed diets containing toxic brown fish meal did not have any detectable signs of macroscopic or microscopic pathology.

The aim of this paper is to shed additional light on the determinants of budget transparency in local governments. Our work is based on a Likert-type survey questionnaire specifically designed to measure budget transparency in small municipalities. The questionnaire is based on the IMF's revised Code of Good Practices on Fiscal Transparency (2007). Results from 33 Galician municipalities are used to assess its internal consistency and to test a battery of hypotheses on the determinants of budget transparency. While several previous findings of the literature are confirmed, some new results are also obtained.

The introduction of the new Simplified Stock Corporation in Colombia in 2008 has changed the closely-held-entity landscape in the region by displacing backward-looking notions imbedded in traditional Company Laws in Latin America. The SAS revolution has been so profound that during 2010 (the second year after the entity was legally adopted) there was an increase of more than 100% in the number of incorporations of this type of company in comparison with the previous year. At the same time, the overall number of business entities created in that same period was augmented by more than 25%. This paper suggests that a simple, but comprehensive, change in the legal framework can significantly contribute to the formalization of thousands of enterprises that otherwise would remain in absolute informality. Empirical observation reveals that such an overhaul in the Company Law infrastructure significantly impacts economic development. In fact, the new regularized business entities can be identified through mercantile publicity, and their degree of observance of the law, whether by paying taxes or abiding by labor regulations has risen markedly in Colombia. Above all, these new simplified corporations have access to credit and are given the opportunity to grow beyond the typically crippling micro-enterprise size.

In this essay we make two major claims. The first is that public legislatures should think seriously about giving maximum effect to the principle of freedom of contract in company law. This would not only give corporate lawyers the tool they need to provide legal services that match the needs of the current global business community, but also encourage legal experimentation. The second claim is that corporate lawyers in common law systems are more open to legal change and innovation than their civil law colleagues. The difference seems to lie in the more experimental nature of common law compared to civil law systems.

In December of 2008, the Congress of the Republic of Colombia enacted a law (1258) creating a new form of hybrid-business entity referred to as the Simplified Stock Corporation (SAS). Following a liberalizing approach in corporate law, this act reduced all formalities for incorporation to a simple registration before a mercantile public registry. It also ameliorated expenses associated with the formation and operation of boards of directors, fiscal auditors, management structure and other formalistic requirements. This paper provides an analytical framework concerning the legal system of directors and officers provided for under Law 1258 of 2008 for the SAS. It focuses specifically on the duties applicable to managers and directors as well as the liabilities in which they may incur pursuant to the statutory provisions. Special attention is given also to the new regulation regarding shadow directors (managers de facto). According to this system, any person who is not a director or officer of the corporation, but interferes in its management or direction, shall incur in the same liabilities and penalties applicable to the latter. Such extrapolation of the legal regime applicable to directors and officers is intended to prevent third parties who intrude in the corporation’s affairs from avoiding the liabilities that normally arise for those who have management responsibilities in the corporation.

Lack of a significant separation between ownership and control in Latin American companies imposes a necessary departure from applicable principles of corporate governance designed for market systems. Therefore, it may prove difficult, for instance, to adopt US norms, in the region due to well-known systemic differences. Corporate governance principles that deal with tensions arising from opportunistic behavior of directors and officers vis-a-vis shareholders may be less important in this region than those principles relating to potential expropriation of minority shareholders or other forms of oppression and reaping of private benefits by block-holders. It is acknowledged that systems in which block holding prevails allow minority stockholders to free ride on controlling shareholders' efforts to monitor management. The emphasis on corporate governance principles in Latin America should be placed not only on directors' duties, but also on the effective protection of minority shareholders and other stakeholders against the undue appropriation of corporate assets by block-holders. Above all, a determining factor for poor corporate governance in this region relates to the prevailing weakness of the legal infrastructure and, specifically, the comparative lack of enforceability. A comprehensive legal catalogue of minority shareholders' rights may be of little value without efficient remedies and procedures ensuring their effective application. This problem can be partially dealt with by the appropriate reallocation of judicial or quasi-judicial powers to specialized administrative agencies. Nevertheless, the effectiveness of legal reform will be limited, in general, by local culture, politics, equity ownership structures and rule of law considerations.

Colombia was one of the first countries in the world to adopt a law on electronic commerce (Law 527 of 1999). However, not many things have changed ever since in the procedural scenario in that country. The notarial function has a long-standing tradition in Colombia as well as in other Latin American countries. The continental European legacy of this institution has crafted an important part of the local legal culture, usually characterized by veneration to the authenticity of all kinds of documents. The large number of civil and commercial transactions subject to the formality of a public deed granted before a notary public is both costly and inefficient. Apart from economical reasons, there are theoretical justifications to the continuity of the notarial function. It is said to provide legal certainty due to the authenticity regarding the subscribing parties and their signatures. The main legal obstacle in this respect is related to the subsistence of civil and commercial regulations providing for the mandatory requirement of public deeds before notaries for several acts and contracts. These legal provisions maintain the traditional civil law approach, whereby a solemnity is required for certain important contracts to be proved in the event of conflict between the parties. Said formalistic approach denies all legal effect to such contracts if they have not been granted before a notary public. The local legal culture has been influenced by these traditional definitions to a high extent. This particular influence is notable within the judicial circuits in which reverence to the paper formality is still the general rule. The enactment of Law 527 of 1999 on electronic commerce offers an unparalleled opportunity to challenge old fashion constructions related to the law of contracts. It is clear that the most difficult legal problems in this respect could be dealt with by the amendment of all subsisting civil or commercial provisions establishing the requirement of public deed. Data messages electronically signed could be an appropriate alternative to the traditional public deeds. Their registration for public record should not be a problem either. Naturally, such filing requirements would also have to be performed by electronic means. Most importantly, an appropriate diffusion of these new legal criteria will be necessary. This educational objective will have to be particularly attained within the judicial community. This objective is of paramount importance in light of the legal certainty requirement. Electronic evidences presented in any judicial proceeding will have to be duly acknowledged and given the appropriate weight in accordance with the new law. It is also predictable that the initial application of these new developments will take place in the arbitration circles.