Plan de negocio para un nuevo canal de ventas para el sector retail mediante el uso de c?digos QR en estaciones de transporte masivo en Lima

Se ha identificado una oportunidad de negocio que permitir?a satisfacer la necesidad de abastecerse de productos para el consumo sin invertir mayor tiempo en ello, adem?s de realizar las compras en tiempos improductivos del consumidor, tiempos aproximados a 10 minutos en los que un ciudadano espera en un paradero de transporte p?blico. La oportunidad de negocio plantea redirigir los esfuerzos publicitarios de los supermercados hacia canales que rentabilicen efectivamente esta inversi?n y sea medible con el incremento de compras para el supermercado. Esta oportunidad de negocio correlaciona los siguientes aspectos: Supermercados interesados en mayor penetraci?n en los canales electr?nicos, poblaci?n familiarizada con el uso de aplicaciones m?viles, tecnolog?a existente innovadora en el rubro de canales electr?nicos e inter?s por el desarrollo de nuevas Start Ups en el Per?

Zinc Intake and Biochemical Markers of Bone Turnover in Type 1 Diabetes

OBJECTIVE—To examine the relationship between Zn nutritive status and biochemical markers of bone turnover in type 1 diabetes

Efecto de la temperatura y pH sobre la actividad y estabilidad de pectinasas producidas por Bacillus spp.

    Las pectinasas se encuentran ampliamente distribuidas en la naturaleza, como por ejemplo en productos de desecho, y su utilidad industrial es de gran importancia. En la presente investigación se trata de establecer algunos parámetros cinéticos a nivel de laboratorio para la producción de pectinasas por Bacillus spp. Se aisló y seleccionó cultivos puros de Bacillus spp. productores de la enzima a partir de muestras de tierra de cultivo de papa y naranja en medio agar nutritivo con sales y pectina como sustrato, se incubó y se realizó la lectura agregando alícuotas de una solución de lugol y aquellos cultivos que presentaban mayor halo de hidrólisis de pectina fueron seleccionados. Estos cultivos se sembraron en medio líquido nutritivo más sales y pectina y se incubaron por 24 – 48 horas; luego se centrifugaron y se obtuvo el sobrenadante denominado extracto crudo de pectinasa (ECP), el cual sirvió para realizar los ensayos de actividad y estabilidad del ECP a pHs y temperaturas variables.  Se encontró que el pH y temperatura de máxima actividad del ECP está alrededor de 6,5 y 35°C, respectivamente. El ECP es estable a pH 6,5 y 8,5 a 35°C por 120 minutos, lo mismo es cierto a temperatura de 50°C hasta por 129 minutos y pierde su estabilidad a 70°C a los 120 minutos.Palabras clave: Bacillus, pectinasas, pH, temperatura, actividad y estabilidad

A Model for Solving the Optimal Water Allocation Problem in River Basins with Network Flow Programming When Introducing Non-Linearities

[EN] The allocation of water resources between different users is a traditional problem in many river basins. The objective is to obtain the optimal resource distribution and the associated circulating flows through the system. Network flow programming is a common technique for solving this problem. This optimisation procedure has been used many times for developing applications for concrete water systems, as well as for developing complete decision support systems. As long as many aspects of a river basin are not purely linear, the study of non-linearities will also be of great importance in water resources systems optimisation. This paper presents a generalised model for solving the optimal allocation of water resources in schemes where the objectives are minimising the demand deficits, complying with the required flows in the river and storing water in reservoirs. Evaporation from reservoirs and returns from demands are considered, and an iterative methodology is followed to solve these two non-network constraints. The model was applied to the Duero River basin (Spain). Three different network flow algorithms (Out-of-Kilter, RELAX-IVand NETFLO) were used to solve the allocation problem. Certain convergence issues were detected during the iterative process. There is a need to relate the data from the studied systems with the convergence criterion to be able to find the convergence criterion which yields the best results possible without requiring a long calculation time.We thank the Spanish Ministry of Economy and Competitivity (Comision Interministerial de Ciencia y Tecnologia, CICYT) for funding the projects INTEGRAME (contract CGL2009-11798) and SCARCE (program Consolider-Ingenio 2010, project CSD2009-00065). We also thank the European Commission (Directorate-General for Research & Innovation) for funding the project DROUGHT-R&SPI (program FP7-ENV-2011, project 282769). And last, but not least, to the Fundacion Instituto Euromediterraneo del Agua with the project "Estudio de Adaptaciones varias del modelo de optimizacion de gestiones de recursos hidricos Optiges".Haro Monteagudo, D.; Paredes Arquiola, J.; Solera Solera, A.; Andreu Álvarez, J. (2012). A Model for Solving the Optimal Water Allocation Problem in River Basins with Network Flow Programming When Introducing Non-Linearities. Water Resources Management. 26(14):4059-4071. https://doi.org/10.1007/s11269-012-0129-7S405940712614Ahuja R, Magnanti T, Orlin J (1993) Network flows: theory, algorithms and applications. Prentice Hall, New YorkAndreu J, Capilla J, Sanchís E (1996) AQUATOOL, a generalized decision-support system for water resources planning and operational management. J Hydrol 177:269–291Bersetkas D (1985) A unified framework for primal-dual methods in minimum cost network flows problems. Math Program 32:125–145Bersetkas D, Tseng P (1988) The relax codes for linear minimum cost network flow problems. Ann Oper Res 13:125–190Bersetkas D, Tseng P (1994) RELAX-IV: A faster version of the RELAX code for solving minimum cost flow problems. Completion Report under NSFGrant CCR-9103804. Dept. of Electrical Engineering and Computer Science, MIT, BostonChou F, Wu C, Lin C (2006) Simulating multi-reservoir operation rules by network flow model. ASCE Conf Proc 212:33Chung F, Archer M, DeVries J (1989) Network flow algorithm applied to California aqueduct simulation. J Water Resour Plan Manag 115:131–147Ford L, Fulkerson D (1962) Flows in networks. Princeton University Press, PrincetonFredericks J, Labadie J, Altenhofen J (1998) Decision support system for conjunctive stream-aquifer management. J Water Resour Plan Manag 124:69–78Harou JJ, Medellín-Azuara J, Zhu T et al (2010) Economic consequences of optimized water management for a prolonged, severe drought in California. Water Resour Res 46:W05522Hsu N, Cheng K (2002) Network Flow Optimization Model for Basin-Scale Water Supply Planning. J Water Resour Plan Manag 128:102–112Ilich N (1993) Improvement of the return flow allocation in the Water Resources Management Model of Alberta Environment. Can J Civ Eng 20:613–621Ilich N (2009) Limitations of network flow algorithms in river basin modeling. J Water Resour Plan Manag 135:48–55Kennington JL, Helgason RV (1980) Algorithms for network programming. John Wiley and Sons, New YorkKhaliquzzaman, Chander S (1997) Network flow programming model for multireservoir sizing. J Water Resour Plan Manag 123:15–21Kuczera G (1989) Fast Multireservoir Mulltiperiod Linear Programming Models. Water Resour Res 25:169–176Kuczera G (1993) Network linear programming codes for water-supply headworks modeling. J Water Resour Plan Manag 119:412–417Labadie J (2004) Optimal operation of multireservoir systems: state-of-the-art review. J Water Resour Plan Manag 130:93–111Labadie J (2006) MODSIM: river basin management decision support system. In: Singh W, Frevert D (eds) Watershed models. CRC, Boca Raton, pp 569–592Labadie J, Baldo M, Larson R (2000) MODSIM: decision support system for river basin management. Documentation and user manual. Dept. Of Civil Engineering, CSU, Fort CollinsManca A, Sechi G, Zuddas P (2010) Water supply network optimisation using equal flow algorithms. Water Resour Manag 24:3665–3678MMA (2000) Libro blanco del agua en España. Ministerio de Medio Ambiente, Secretaría general Técnica, Centro de PublicacionesMMA (2008) Confederación Hidrográfica del Duero. Memoria 2008. http://www.chduero.es/Inicio/Publicaciones/tabid/159/Default.aspx . Last accessed 25 June 2012Perera B, James B, Kularathna M (2005) computer software tool REALM for sustainable water allocation and management. J Environ Manag 77:291–300Rani D, Moreira M (2010) Simulation-optimization modeling: a survey and potential application in reservoir systems operation. Water Resour Manag 24:1107–1138Reca J, Roldán J, Alcaide M, López R, Camacho E (2001a) Optimisation model for water allocation in deficit irrigation systems I. Description of the model. Agric Water Manag 48:103–116Reca J, Roldán J, Alcaide M, López R, Camacho E (2001b) Optimisation model for water allocation in deficit irrigation systems II. Application to the Bembézar irrigation system. Agric Water Manag 48:117–132Sechi G, Zuddas P (2008) Multiperiod hypergraph models for water systems optimization. Water Resour Manag 22:307–320Sun H, Yeh W, Hsu N, Louie P (1995) Generalized network algorithm for water-supply-system optimization. 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Bone mineral density in vocational and professional ballet dancers

Summary: According to existing literature, bone health in ballet dancers is controversial. We have verified that, compared to controls, young female and male vocational ballet dancers have lower bone mineral density (BMD) at both impact and non-impact sites, whereas female professional ballet dancers have lower BMD only at non-impact sites. Introduction: The aims of this study were to (a) assess bone mineral density (BMD) in vocational (VBD) and professional (PBD) ballet dancers and (b) investigate its association with body mass (BM), fat mass (FM), lean mass (LM), maturation and menarche. Methods: The total of 152 VBD (13 ± 2.3 years; 112 girls, 40 boys) and 96 controls (14 ± 2.1 years; 56 girls, 40 boys) and 184 PBD (28 ± 8.5 years; 129 females, 55 males) and 160 controls (27 ± 9.5 years; 110 female, 50 males) were assessed at the lumbar spine (LS), femoral neck (FN), forearm and total body by dual-energy X-ray absorptiometry. Maturation and menarche were assessed via questionnaires. Results: VBD revealed lower unadjusted BMD at all anatomical sites compared to controls (p < 0.001); following adjustments for Tanner stage and gynaecological age, female VBD showed similar BMD values at impact sites. However, no factors were found to explain the lower adjusted BMD values in VBD (female and male) at the forearm (non-impact site), nor for the lower adjusted BMD values in male VBD at the FN. Compared to controls, female PBD showed higher unadjusted and adjusted BMD for potential associated factors at the FN (impact site) (p < 0.001) and lower adjusted at the forearm (p < 0.001). Male PBD did not reveal lower BMD than controls at any site. Conclusions: both females and males VBD have lower BMD at impact and non-impact sites compared to control, whereas this is only the case at non-impact site in female PBD. Maturation seems to explain the lower BMD at impact sites in female VBD

Reliable quantification of the potential for equations based on spot urine samples to estimate population salt intake: protocol for a systematic review and meta-analysis.

BACKGROUND: Methods based on spot urine samples (a single sample at one time-point) have been identified as a possible alternative approach to 24-hour urine samples for determining mean population salt intake. OBJECTIVE: The aim of this study is to identify a reliable method for estimating mean population salt intake from spot urine samples. This will be done by comparing the performance of existing equations against one other and against estimates derived from 24-hour urine samples. The effects of factors such as ethnicity, sex, age, body mass index, antihypertensive drug use, health status, and timing of spot urine collection will be explored. The capacity of spot urine samples to measure change in salt intake over time will also be determined. Finally, we aim to develop a novel equation (or equations) that performs better than existing equations to estimate mean population salt intake. METHODS: A systematic review and meta-analysis of individual participant data will be conducted. A search has been conducted to identify human studies that report salt (or sodium) excretion based upon 24-hour urine samples and spot urine samples. There were no restrictions on language, study sample size, or characteristics of the study population. MEDLINE via OvidSP (1946-present), Premedline via OvidSP, EMBASE, Global Health via OvidSP (1910-present), and the Cochrane Library were searched, and two reviewers identified eligible studies. The authors of these studies will be invited to contribute data according to a standard format. Individual participant records will be compiled and a series of analyses will be completed to: (1) compare existing equations for estimating 24-hour salt intake from spot urine samples with 24-hour urine samples, and assess the degree of bias according to key demographic and clinical characteristics; (2) assess the reliability of using spot urine samples to measure population changes in salt intake overtime; and (3) develop a novel equation that performs better than existing equations to estimate mean population salt intake. RESULTS: The search strategy identified 538 records; 100 records were obtained for review in full text and 73 have been confirmed as eligible. In addition, 68 abstracts were identified, some of which may contain data eligible for inclusion. Individual participant data will be requested from the authors of eligible studies. CONCLUSIONS: Many equations for estimating salt intake from spot urine samples have been developed and validated, although most have been studied in very specific settings. This meta-analysis of individual participant data will enable a much broader understanding of the capacity for spot urine samples to estimate population salt intake

Introduction to celebrating Latin American talent in chemistry

In celebration of the excellence and breadth of Latin American research achievements across the chemical sciences, we are delighted to present an introduction to the themed collection, Celebrating Latin American talent in chemistry. [Image: see text