Optimizing the profit from a complex cascade of hydroelectric stations with recirculating water

In modern reversible hydroelectric power stations it is possible to reverse the turbine and pump water up from a downstream reservoir to an upstream one. This allows the use of the same volume of water repeatedly and was speci cally developed for hydro-electric stations operating with in- su cient water supply. Pumping water upstream is usually done at times of low demand for electricity, to build up reserves in order to be able to produce energy during peak hours, thus balancing the load and making a pro t on the price di erence. In this paper, we consider a branched model for hydroelectric power stations interacting in a complex cascade arrangement. The goal of this study is to provide guidance in decision-making aimed at maximizing the pro t. A detailed analysis is made of a simpler reservoir con guration, which indicates that even though the problem is nonlinear, a bang-bang type of control is optimal, where the power stations are operated at maximum rates of flow. Some simple relationships between price and timing of decisions are calculated directly. A numerical algorithm is also developed.This problem was brought by Redes Energéticas Nacionais to the 69th European Study Group with Industry, April 20–24, 2009, Departamento de Matemática da Universidade de Coimbra, Portugal. Andrei Korobeinikov and Mark McGuinness are very grateful to the organizers of the 69th ESGI for financial support and for their kind and generous hospitality. Andrei Korobeinikov and Mark McGuinness are supported by the Mathematics Applications132 Optimizing the profit from a complex cascade of hydroelectric stations with recirculating water Consortium for Science and Industry, funded by the Science Foundation Ireland Mathematics Initiative Grant 06/MI/005. Mark McGuinness also thanks OCCAM in Oxford for supporting his travels. Marta Pascoal is partially funded by the Portuguese FCT under project POSC/U308/1.3/NRE/04

Argentinian multicenter study on urinary tract infections due to <i>Streptococcus agalactiae</i> in adult patients

Introduction Streptococcus agalactiae (group B streptococcus, GBS) is a recognized urinary pathogen both in males and pregnant or non-pregnant women. Data regarding GBS serotypes recovered from urinary tract infections (UTIs) are scarce. The aim of this study was to describe the clinical and microbiological characteristics of UTIs caused by GBS in adult patients in Argentina. Methodology A prospective multicenter study involving 86 centers was conducted in Argentina between July 1st, 2014 and June 30th, 2015. Antimicrobial susceptibility and serotype distribution of GBS isolated from the urinary tract of adult patients were determined. Susceptibility tests were performed by the disk diffusion and/or agar dilution methods. Epidemiological and clinical characteristics of the patients were considered to identify associated comorbilities. Results Seven hundred and one GBS were sent to the reference laboratory in the above mentioned period, however, only 211 fulfilled our selection criteria (demographic data availability, underlying diseases reported, colony counts greater than 105 CFU/mL, single organism isolated from the urine sample). No penicillin-resistant GBS was found but fluoroquinolone resistance was high (12.8%), especially among GBS isolated from men and non-pregnant women. UTIs due to GBS were associated to underlying diseases in men and non-pregnant women, particularly diabetes mellitus. Most of the isolates showed serotypes Ia and III. Conclusions GBS are still susceptible to penicillin but fluoroquinolone resistance is a growing concern, at least in Argentina. There are underlying conditions that could be associated to urinary infections caused by GBS.Facultad de Ciencias Exacta

Screening assay for inhibitors of a recombinant Streptococcus pneumoniae UDP-glucose pyrophosphorylase

The UDP-glucose pyrophosphorylase of Streptococcus pneumoniae (GalUSpn) is absolutely required for the biosynthesis of capsular polysaccharide, the sine qua non virulence factor of pneumococcus. Since the eukaryotic enzymes are completely unrelated to their prokaryotic counterparts, we propose that the GalU enzyme is a critical target to fight the pneumococcal disease. A recombinant GalUSpn was overexpressed and purified. An enzymatic assay that is rapid, sensitive and easy to perform was developed. This assay was appropriate for screening chemical libraries for searching GalU inhibitors. This work represents a fundamental step in the exploration of novel antipneumococcal drugs.Fil: Zavala, Agustín. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; ArgentinaFil: Kovacec, Verónica Ivana. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; ArgentinaFil: Levín, Gustavo. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; ArgentinaFil: Moglioni, Albertina Gladys. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Miranda, Maria Victoria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: García, Ernesto. Consejo Superior de Investigaciones Científicas. Centro de Investigaciones Biológicas; EspañaFil: Bonofiglio, Laura. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mollerach, Marta Eugenia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Argentinian multicenter study on urinary tract infections due to Streptococcus agalactiae in adult patients

Introduction: Streptococcus agalactiae (group B streptococcus, GBS) is a recognized urinary pathogen both in males and pregnant or non-pregnant women. Data regarding GBS serotypes recovered from urinary tract infections (UTIs) are scarce. The aim of this study was to describe the clinical and microbiological characteristics of UTIs caused by GBS in adult patients in Argentina.Methodology: A prospective multicenter study involving 86 centers was conducted in Argentina between July 1st, 2014 and June 30th, 2015. Antimicrobial susceptibility and serotype distribution of GBS isolated from the urinary tract of adult patients were determined. Susceptibility tests were performed by the disk diffusion and/or agar dilution methods. Epidemiological and clinical characteristics of the patients were considered to identify associated comorbilities.Results: Seven hundred and one GBS were sent to the reference laboratory in the above mentioned period, however, only 211 fulfilled our selection criteria (demographic data availability, underlying diseases reported, colony counts greater than 105 CFU/mL, single organism isolated from the urine sample). No penicillin-resistant GBS was found but fluoroquinolone resistance was high (12.8%), especially among GBS isolated from men and non-pregnant women. UTIs due to GBS were associated to underlying diseases in men and non-pregnant women, particularly diabetes mellitus. Most of the isolates showed serotypes Ia and III.Conclusions: GBS are still susceptible to penicillin but fluoroquinolone resistance is a growing concern, at least in Argentina. There are underlying conditions that could be associated to urinary infections caused by GBS.Fil: Vigliarolo, Laura. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Arias, Bárbara Soledad. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; ArgentinaFil: Suarez, Mariana. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Van Haute, Evert. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; ArgentinaFil: Kovacec, Verónica Ivana. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; ArgentinaFil: Lopardo, Horacio Angel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Bonofiglio, Laura. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Mollerach, Marta Eugenia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin

Fluoroquinolone-resistant streptococcus agalactiae invasive isolates recovered in Argentina

Background: Streptococcus agalactiae or group B Streptococcus (GBS) is an important pathogen in neonates and nonpregnant individuals. Epidemiological studies of GBS resistance to fluoroquinolones (FQs) in Latin America are scarce. This study aimed to determine the local prevalence of FQ resistance in the frame of a national, prospective multicenter study of invasive GBS infections and to investigate mechanisms of resistance, serotype distribution, and clonal relationships among resistant isolates. Methods: From July 2014 to July 2015, 162 invasive GBS isolates were collected from 86 health care centers in 32 Argentinean cities. All isolates were screened for FQ nonsusceptibility using a five-disc scheme: Levofloxacin (LVX), ciprofloxacin, norfloxacin (NOR), ofloxacin, and pefloxacin (PF). LVX minimal inhibitory concentration (MIC) was determined by the agar dilution method. Sequencing of internal regions of gyrA and parC genes was performed. Capsular typing and genetic characterization of nonsusceptible isolates were assessed by latex agglutination, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing. Results: Twenty-four of one hundred sixty-two GBS isolates exhibited no inhibition zones to all tested FQs with an MIC range of 16-32 mg/L for LVX, and one isolate with MIC = 1 mg/L showed no inhibition zones around NOR and PF discs. In all resistant isolates, point mutations were detected in both genes. Serotype Ib was prevalent (88%). One PFGE type accounted for 84% of the FQ-resistant isolates and belonged to serotype Ib, sequence type 10. Conclusions: The prevalence of FQ resistance was 14.8% likely to be associated with dissemination of an ST10/serotype Ib clone. The unexpected high rate of resistance emphasizes the relevance for continuous surveillance of GBS epidemiology and antibiotic susceptibility.Fil: Arias, Bárbara Soledad. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Kovacec, Verónica Ivana. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Vigliarolo, Laura. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Suárez, Mariana. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Tersigni, Carina Laura. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Müller, Loana. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Lopardo, Horacio Angel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Bonofiglio, Laura. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Mollerach, Marta Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentin

Melting behaviour of waste glass cullet briquettes in soda-lime-silica container glass batch

The melting behaviour of representative container glass batch with and without the addition of 15wt % briquettes produced from waste cullet fine particles was investigated in the context of reducing both waste and glass melting energies. Carbonate raw material decomposition and reactions during melting were studied by DTA-TGA-MS. The decomposition kinetics of two batches, representing typical container glass batches with 0% and 15% briquette additions, were calculated by transformation degree based on the Ginstling-Brounstein and Arrhenius equations. High temperature phase transitions and fractions of silica reaction in each batch were obtained from X-ray diffractometry (XRD). The briquette additions accelerated the decomposition reactions and the silicate reaction kinetics by decreasing the activation energy for carbonate decomposition. Silica sand in the batch was shown to melt at lower temperatures with the addition of briquettes. Batch melting processes at different temperatures and briquette melting on top of the molten glass at high temperatures, were investigated by macroscopic investigations of sample cross-sections post-melting. The positive effects of briquette additions to container glass batches, in terms of increased melting rate and reduced batch reaction and decomposition temperatures, are supported by the results of this study

Argentinian multicenter study on urinary tract infections due to <i>Streptococcus agalactiae</i> in adult patients

Introduction Streptococcus agalactiae (group B streptococcus, GBS) is a recognized urinary pathogen both in males and pregnant or non-pregnant women. Data regarding GBS serotypes recovered from urinary tract infections (UTIs) are scarce. The aim of this study was to describe the clinical and microbiological characteristics of UTIs caused by GBS in adult patients in Argentina. Methodology A prospective multicenter study involving 86 centers was conducted in Argentina between July 1st, 2014 and June 30th, 2015. Antimicrobial susceptibility and serotype distribution of GBS isolated from the urinary tract of adult patients were determined. Susceptibility tests were performed by the disk diffusion and/or agar dilution methods. Epidemiological and clinical characteristics of the patients were considered to identify associated comorbilities. Results Seven hundred and one GBS were sent to the reference laboratory in the above mentioned period, however, only 211 fulfilled our selection criteria (demographic data availability, underlying diseases reported, colony counts greater than 105 CFU/mL, single organism isolated from the urine sample). No penicillin-resistant GBS was found but fluoroquinolone resistance was high (12.8%), especially among GBS isolated from men and non-pregnant women. UTIs due to GBS were associated to underlying diseases in men and non-pregnant women, particularly diabetes mellitus. Most of the isolates showed serotypes Ia and III. Conclusions GBS are still susceptible to penicillin but fluoroquinolone resistance is a growing concern, at least in Argentina. There are underlying conditions that could be associated to urinary infections caused by GBS.Facultad de Ciencias Exacta

Fluoroquinolone-Resistant <i>Streptococcus agalactiae</i> Invasive Isolates Recovered in Argentina

Background: Streptococcus agalactiae or group B Streptococcus (GBS) is an important pathogen in neonates and nonpregnant individuals. Epidemiological studies of GBS resistance to fluoroquinolones (FQs) in Latin America are scarce. This study aimed to determine the local prevalence of FQ resistance in the frame of a national, prospective multicenter study of invasive GBS infections and to investigate mechanisms of resistance, serotype distribution, and clonal relationships among resistant isolates. Methods: From July 2014 to July 2015, 162 invasive GBS isolates were collected from 86 health care centers in 32 Argentinean cities. All isolates were screened for FQ nonsusceptibility using a five-disc scheme: levofloxacin (LVX), ciprofloxacin, norfloxacin (NOR), ofloxacin, and pefloxacin (PF). LVX minimal inhibitory concentration (MIC) was determined by the agar dilution method. Sequencing of internal regions of gyrA and parC genes was performed. Capsular typing and genetic characterization of nonsusceptible isolates were assessed by latex agglutination, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing. Results: Twenty-four of one hundred sixty-two GBS isolates exhibited no inhibition zones to all tested FQs with an MIC range of 16–32 mg/L for LVX, and one isolate with MIC = 1 mg/L showed no inhibition zones around NOR and PF discs. In all resistant isolates, point mutations were detected in both genes. Serotype Ib was prevalent (88%). One PFGE type accounted for 84% of the FQ-resistant isolates and belonged to serotype Ib, sequence type 10. Conclusions: The prevalence of FQ resistance was 14.8% likely to be associated with dissemination of an ST10/serotype Ib clone. The unexpected high rate of resistance emphasizes the relevance for continuous surveillance of GBS epidemiology and antibiotic susceptibility.Facultad de Ciencias Exacta

Interaction of Copper-Based Nanoparticles to Soil, Terrestrial, and Aquatic Systems: Critical Review of the State of the Science and Future Perspectives

In the past two decades, increased production and usage of metallic nanoparticles (NPs) has inevitably increased their discharge into the different compartments of the environment, which ultimately paved the way for their uptake and accumulation in various trophic levels of the food chain. Due to these issues, several questions have been raised on the usage of NPs in everyday life and has become a matter of public health concern. Among the metallic NPs, Cu-based NPs have gained popularity due to their cost-effectiveness and multifarious promising uses. Several studies in the past represented the phytotoxicity of Cu-based NPs on plants. However, comprehensive knowledge is still lacking. Additionally, the impact of Cu-based NPs on soil organisms such as agriculturally important microbes, fungi, mycorrhiza, nematode, and earthworms are poorly studied. This review article critically analyses the literature data to achieve a more comprehensive knowledge on the toxicological profile of Cu-based NPs and increase our understanding of the effects of Cu-based NPs on aquatic and terrestrial plants as well as on soil microbial communities. The underlying mechanism of biotransformation of Cu-based NPs and the process of their penetration into plants has also been discussed herein. Overall, this review could provide valuable information to design rules and regulations for the safe disposal of Cu-based NPs into a sustainable environment

Convex hull calculations: a Matlab implementation and correctness proofs for the lrs-algorithm

This paper provides full Matlab -code and informal correctness proofs for the lexicographic reverse search algorithm for convex hull calculations. The implementation was tested on a 1993 486-PC for various small and some larger, partially highly degenerate combinatorial polytopes, one of which (a certain 13- dimensional 24 vertex polyhedron) occurs naturally in the study of a well known problem posed by Professor Graciano de Oliveira: see end of section 1