On the estimation of on-hand stocks for base-stock policies and lost sales systems and its impact on service measures

[EN] This paper focuses on computing on-hand stock levels at the beginning of a replenishment cycle for a lost sales inventory system with periodic reviews and discrete demand. A base-stock policy is used for replenishments. The literature provides an Exact method which requires a huge computational effort, and two closed-form approximate methods that arise from the backordering case, the Non-stockout and the Bijvank & Johansen. In this paper we propose three new and closed-form approaches that explicitly consider the lost sales assumptions: the Adjusted Non-stockout, the Polar Opposite and the 1-Step methods. Existing and proposed methods are evaluated in terms of their accuracy when computing the cycle service level and the fill rate. In this sense, results show that the Bijvank & Johansen and 1-Step methods provide similar performance but present different behaviours in terms of under or over estimating service measures that have different implications on the design of stock policies.This work was supported by the European Regional Development Fund and Spanish Government (MINECO/FEDER, UE) under the project with reference [DPI2015-64,133-R].Cardós, M.; Guijarro, E.; Babiloni, E. (2017). On the estimation of on-hand stocks for base-stock policies and lost sales systems and its impact on service measures. International Journal of Production Research. 55(16):4680-4694. https://doi.org/10.1080/00207543.2017.1279759S46804694551

Fill Rate Estimation in Periodic Review Policies with Lost Sales Using Simple Methods

[EN] Purpose: The exact estimation of the fill rate in the lost sales case is complex and time consuming. However, simple and suitable methods are needed for its estimation so that inventory managers could use them. Design/methodology/approach: Instead of trying to compute the fill rate in one step, this paper focuses first on estimating the probabilities of different on-hand stock levels so that the fill rate is computed later. Findings: As a result, the performance of a novel proposed method overcomes the other methods and is relatively simple to compute. Originality/value: Existing methods for estimating stock levels are examined, new procedures are proposed and their performance is assessed.This work was supported by the European Regional Development Fund and Spanish Government (MINECO/FEDER, UE) under the project with reference DPI2015-64133-R.Cardós, M.; Guijarro, E.; Babiloni, E. (2016). Fill Rate Estimation in Periodic Review Policies with Lost Sales Using Simple Methods. Journal of Industrial Engineering and Management. 9(5):73-89. https://doi.org/10.3926/jiem.2063S73899

ABC classification of spare parts considering costs and service

[EN] This paper focuses on the multi-item problem where it is necessary to reach an overall stock availability of the spare parts while minimising involved costs. Over the last years, a number of authors have proposed a variety of approaches and provided different rules in order to classify items in ABC classes. An additional optimisation has to be performed in order to minimise the inventory cost while fulfilling a target service level. The proposed approach focuses on the characteristics of spare parts and optimises the inventory cost subject to the overall target fill rate by means of a closed form formula for calculating the fill rate of every item independently. This new method is validated with a dataset of spare parts of an airline company and clearly outperforms the alternative methods in terms of inventory cost reduction and ease of calculation. Extensions of our results are also indicated.S244255223-

Las rutas literarias: una estrategia de carácter competencial para la educación literaria dentro y fuera del aula

El desarrollo de una ruta literaria, desde un enfoque competencial, busca acercar a nuestros jóvenes a la educación literaria desde una perspectiva interdisciplinar en donde las competencias básicas educativas sean el referente en el proceso de enseñanza-aprendizaje. En nuestros planteamientos seguimos la idea de J. Culler, para el que en la lectura literaria existe un condicionante sociocultural que permite el reconocimiento de la marca literaria, la experiencia del mundo, y el aprendizaje de los códigos literarios y las relaciones de intertextualidad

Short communication: Using infrared ocular thermography as a tool to predict meat quality from lean cattle breeds prior to slaughter: Exploratory trial

Aim of study: To assess the potential of using infrared ocular thermography (IROT) as a tool to predict beef quality at the slaughterhouse.Area of study: The study was carried out in the Salteras’s slaughterhouse (Seville, Spain).Material and methods: Ocular temperature images were captured from 175 lean young bulls prior to slaughter. Carcasses were classified into three groups according to weight: ˂250 kg, 250-310 kg and ˃310 kg. IROT was measured just before slaughter and pH was measured 24 h later. Colour parameters (CIELAB space) were evaluated 48 h post-slaughter. Water holding capacity was evaluated at seven days after slaughter.Main results: IROT mean values were higher in heavier bulls (p<0.05), probably due to these animals appeared to movilize a greater blood flow, thus increasing ocular temperature. Furthermore, IROT showed a statistically significant correlation with both pH from light carcasses (r=0.66; p<0.001), and mean Hue value from all carcass weights (r=-0.22; p<0.05). A quadratic regression analysis accounting carcass weight as a continuous variable, found medium to strong fit values for pH (R2=0.52; RMSE=0.032; p<0.01) and medium fit values for H* (R2=0.41; RMSE=3.793; p<0.001), changing their relation with IROT depending on carcass weight.Research highlights: IROT showed potential to become a useful tool to assess pH in light carcasses and to assess H* in all carcasses of young bulls prior to slaughter, regardless their weight. However, further studies would be recommended under more variable pre-slaughter stress conditions

Microbial infection risk predicts antimicrobial potential of avian symbionts

Funding EM-R was financed by a predoctoral contract (PRE2018-085378) while the whole research group received funds from the projects CGL2017-83103-P, PID2020-117429GB-C21, and PID2020-117429GB-C22, funded by the Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación/10.13039/501100011033 and by “Fondo Europeo de Desarrollo Regional, a way of making Europe.” The research group also benefits from facilities, including accommodation, provided by the City Hall of Guadix, where a small lab to quickly process the samples was installed.Data availability statement Data used in this paper can be found in CSIC Institutional Repository: https://doi.org/10.20350/digitalCSIC/14748.Symbiotic bacteria on animal hosts can prevent pathogenic bacterial infections by several mechanisms. Among them, symbiotic bacteria can indirectly enhance host’s immune responses or, directly, produce antimicrobial substances against pathogens. Due to differences in life-style, different host species are under different risks of microbial infections. Consequently, if symbiotic bacteria are somewhat selected by genetically determined host characteristics, we would expect the antimicrobial properties of bacterial symbionts to vary among host species and to be distributed according to risk of infection. Here we have tested this hypothesis by measuring the antimicrobial ability of the bacterial strains isolated from the uropygial-gland skin of 19 bird species differing in nesting habits, and, therefore, in risk of microbial infection. In accordance with our predictions, intensity and range of antimicrobial effects against the indicator strains assayed varied among bird species, with hole-and open-nesters showing the highest and the lowest values, respectively. Since it is broadly accepted that hole-nesters have higher risks of microbial infection than open nesters, our results suggest that the risk of infection is a strong driver of natural selection to enhance immunocompetence of animals through selecting for antibiotic-producing symbionts. Future research should focus on characterizing symbiotic bacterial communities and detecting coevolutionary processes with particular antibiotic-producing bacteria within-host species.Ministerio de Ciencia e Innovación projects CGL2017-83103-P, PID2020-117429GB-C21, and PID2020-117429GB-C22European Regional Development FundAgencia Estatal de Investigación 10.13039/50110001103

De la comprensión lectora a la competencia literaria a través de la obra de Eliacer Cansino

Esta investigación parte de la hipótesis de que la comprensión lectora es un elemento clave para acceder a la marca literaria y desarrollar la competencia literaria de los adolescentes. La finalidad principal es analizar la relación entre los niveles de comprensión lectora de estudiantes de educación secundaria y su competencia literaria a partir de la obra de un autor de literatura infantil y juvenil como es Eliacer Cansino. Para ello, se ha empleado una metodología estadística basada en el razonamiento inductivo con un diseño cuantitativo, tomando como referencia una muestra de 264 estudiantes de tercero de educación secundaria de la bahía de Cádiz que respondieron a un cuestionario del que se han obtenido datos basados en la relación intertextual de la obra de Eliacer Cansino con textos de la literatura española vinculados al currículum escolar. Los resultados evidencian una necesidad de trabajar la comprensión lectora entre los estudiantes para facilitar el acceso al texto literario con el fin de desarrollar su competencia literaria

Retracción y fluencia de hormigón autocompactante de resistencia moderada

Los estudios sobre el hormigón autocompactante se han centrado en obtener las dosificaciones óptimas, pero hay desconocimiento acerca de su comportamiento a largo plazo, en especial en hormigones de resistencia moderada. Este trabajo estudia la fluencia y retracción de tres hormigones autocompactantes de resistencia moderada (resistencia característica aproximada de 25 MPa), cuya dosificación y propiedades mecánicas son casi iguales, pero que emplean cementos con distintos tipos de adición. En los tres casos se emplea filler calizo. El trabajo presenta los resultados de los ensayos de retracción y fluencia, que son comparados con las predicciones del Código Modelo CEB-FIP, del ACI Concrete Practice Manual y del Euro Code 2. Además también se ha obtenido el volumen total de poros y su distribución por tamaños mediante el ensayo de porosimetría por intrusión de mercurio