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The Birnbaum-Saunders (BS) model is a life distribution with interesting properties and applications in several fields. This has transformed the BS model in an important research focus in recent decades. However, the sum of BS (BSsum) independent random variables does not follow a BS distribution. By means of the BSsum distribution, we can monitor the lifetime of products subject to failures using a quality control chart. Classic procedures for control charts assume normality in the distribution of the data. Nevertheless, one of the main characteristics of the lifetimes is that them generally follow asymmetric distributions. Therefore, if we want to monitor these lifetimes, we must consider control charts for asymmetric distributions, such as it is the case of the BS distribution. The monitoring of the lifetimes is carried out generally by the accumulated lifetime or the lifetime average until than a number of failures occurs. Thus, by using the BSsum distribution, we develop, implement and apply a new methodology for control charts based on the BS distribution.El modelo Birnbaum-Saunders (BS) es una distribución de vida que tiene propiedades interesantes y aplicaciones en varias áreas. Esto la ha convertido en un foco de investigación importante en el último tiempo. Sin embargo, la suma de variables aleatorias independientes BS (BSsum) no sigue una distribución BS. A través de la distribución BSsum, se pueden monitorear los tiempos de vida de productos expuestos a fallas mediante una carta de control de calidad. Los procedimientos clásicos de cartas de control suponen normalidad en la distribución de los datos. No obstante, una de las características principales de los tiempos de vida es que éstos generalmente siguen distribuciones asimétricas. Por tanto, si se quiere monitorear estos tiempos, se deben considerar cartas de control para distribuciones asimétricas, como es el caso de la distribución BS. El monitoreo de los tiempos de vida se realiza generalmente mediante el tiempo acumulado o el tiempo promedio hasta la ocurrencia de cierto número de fallas. Entonces, usando la distribución BSsum, desarrollamos, implementamos y aplicamos una nueva metodología para cartas de control basada en la distribución BS.

The ferric-uptake regulatory (fur) regulates iron metabolism in Staphylococcus aureus. Fur binds to a region on the fhu operon called the fur box.

The monitoring of trees is crucial for the management of large areas of forest cultivations, but this process may be costly. However, remotely sensed data offers a solution to automate this process. In this work, we used two neural network methods named You Only Look Once (YOLO) and Mask R-CNN to overcome the challenging tasks of counting, detecting, and segmenting high dimensional Red–Green–Blue (RGB) images taken from unmanned aerial vehicles (UAVs). We present a processing framework, which is suitable to generate accurate predictions for the aforementioned tasks using a reasonable amount of labeled data. We compared our method using forest stands of different ages and densities. For counting, YOLO overestimates 8.5% of the detected trees on average, whereas Mask R-CNN overestimates a 4.7% of the trees. For the detection task, YOLO obtains a precision of 0.72 and a recall of 0.68 on average, while Mask R-CNN obtains a precision of 0.82 and a recall of 0.80. In segmentation, YOLO overestimates a 13.5% of the predicted area on average, whereas Mask R-CNN overestimates a 9.2%. The proposed methods present a cost-effective solution for forest monitoring using RGB images and have been successfully used to monitor ∼ 146 , 500 acres of pine cultivations. [ABSTRACT FROM AUTHOR]

The three genes in the iron-hydroxamate uptake system in Staphylococcus aureus appear to code for an ATP-binding protein and two ferrichrome permeases. The operon resembles an ATP-binding cassette transporter and it is specific for iron-bound siderophores.

Copyright of APUNTES - Journal of Cultural Heritage Studies is the property of Pontificia Universidad Javeriana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The behavioural diagnostics of bearings play an essential role in the management of several rotation machine systems. However, current diagnostic methods do not deliver satisfactory results with respect to failures in variable speed rotational phenomena. In this paper, we consider the Shannon entropy as an important fault signature pattern. To compute the entropy, we propose combining stationary wavelet transform and singular value decomposition. The resulting feature extraction method, that we call stationary wavelet singular entropy (SWSE), aims to improve the accuracy of the diagnostics of bearing failure by finding a small number of high-quality fault signature patterns. The features extracted by the SWSE are then passed on to a kernel extreme learning machine (KELM) classifier. The proposed SWSE-KELM algorithm is evaluated using two bearing vibration signal databases obtained from Case Western Reserve University. We compare our SWSE feature extraction method to other well-known methods in the literature such as stationary wavelet packet singular entropy (SWPSE) and decimated wavelet packet singular entropy (DWPSE). The experimental results show that the SWSE-KELM consistently outperforms both the SWPSE-KELM and DWPSE-KELM methods. Further, our SWSE method requires fewer features than the other two evaluated methods, which makes our SWSE-KELM algorithm simpler and faster. [ABSTRACT FROM AUTHOR]

In order to understand how galaxies form and evolve, the measurement of the parameters related to their morphologies and also to the way they interact is one of the most relevant requirements. Due to the huge amount of data that is generated by surveys, the morphological and interaction analysis of galaxies can no longer rely on visual inspection. For dealing with such issue, new approaches based on machine learning techniques have been proposed in the last years with the aim of automating the classification process. We tested Deep Learning using images of galaxies obtained from CANDELS to study the accuracy achieved by this tool considering two different frameworks. In the first, galaxies were classified in terms of their shapes considering five morphological categories, while in the second, the way in which galaxies interact was employed for defining other five categories. The results achieved in both cases are compared and discussed. [ABSTRACT FROM PUBLISHER]

At present the companies that provide telecommunications services need to establish service level agreements with customers to agree and set the quality of services to offer. To establish service level agreements allow for multiple benefits to customers and service providers. There are a lot of existing initiatives for standardization of those agreements in various scenarios, but these have a high complexity and apply them to networks of entities that provide telecommunications services in non-commercial way would be complex and the tools to manage such agreements are generally proprietary software. In this article it is established a proposal to be applied to non-commercial networks that allows to manage service level agreements at the execution stage. To check out the operation of the proposal a software was developed, that is also showed up in this article. [ABSTRACT FROM AUTHOR]

In this work, we theoretically study the spin-dependent transport in a magnetic tunnel junction (MTJ). Using a simple model and ballistic transport, the magnetic polarization of the tunneling current on this system is studied by focusing on the tunneling of s and d electrons. We investigate the tunneling of these electrons through potential barriers, which represents the insulating layer between the ferromagnetic electrodes. We also examine how the conductance depends on voltage applied between the electrodes and on the effective mass of the electrons. The conductance is controlled by the transmission coefficient of the tunnel effect, and qualitatively it is known that tunneling probability of the d electrons is lower than the s electrons. We also estimate the effect of the tunneling magnetoresistance (TMR) and it is strongly influenced by the effective mass of the electrons. The s electrons do not contribute significantly to the TMR. [ABSTRACT FROM PUBLISHER]

This work presents the development of MABAP, a decision support system based on the agent technology that helps in solving the problem of berth allocation for ships within a port. The Berth Allocation Problem (BAP) regards the logistics involved in planning and controlling the berthing of vessels. A software architecture in terms of agents is presented; Berths and Ships representing the actors in the system, BerthRequest and BerthPlanner as representatives of ships and berths in the planning process, and finally the Dock and Central agents representing the dock or pier. The architecture modeling was done using PASSI methodology for the design of agent-oriented systems, and the implementation was done in JADE, a Java- based development environment for multiagent systems. To validate the resulting support system, tests were carried out in which the user can choose different port- policy scenarios, ranging from maximizing vessels throughput to maximize berths use. [ABSTRACT FROM AUTHOR]

We solve a novel inventory-locationmodel with a stochastic capacity constraint based on a periodic inventory control (ILM-PR) policy. The ILM-PR policy implies several changes with regard to other previousmodels proposed in the literature, which consider continuous review as their inventory policy. One of these changes is the inclusion of the undershoot concept, which has not been considered in previous ILM models in the literature. Based on ourmodel, we are able to design a distribution network for a two-level supply chain, addressing both warehouse location and customer assignment decisions, whilst taking into consideration several aspects of inventory planning, in particular, evaluating the impact of the inventory control review period on the network configuration and system costs. Because the model is a very hard-to solve combinatorial nonlinear optimisation problem, we implemented two heuristics to solve it, namely, Tabu Search and Particle Swarm Optimisation. These approaches were tested over small instances in which they were able to find the optimal solution in just a few seconds. Because the model is a new one, a set of medium-size instances is provided that can be useful as a benchmark in future research. The heuristics showed a good convergence rate when applied to those instances. The results confirmthat decisionmaking over the inventory control policy has effects on the distribution network design. [ABSTRACT FROM AUTHOR]

The balanced academic curriculum problem consists in the assignation of courses to academic periods satisfying all the load limits and prerequisite constraints. In this paper, we present the design of a solution to the balanced academic curriculum problem based on the ACO metaheuristic, in particular via the Best-Worst Ant System. We provide an experimental evaluation which illustrates the effectiveness of the proposed approach on a set of classic benchmarks as well as on real instances. [ABSTRACT FROM AUTHOR]

Copyright of La Revista Latinoamericana de Metalurgia y Materiales, RLMM is the property of Universidad Simon Bolivar, Departmento de Ciencia de los Materiales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Salud Pública de México is the property of Instituto Nacional de Salud Publica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BSTRACT. Transient, two-dimensional solutions are developed which describe the movement and distribution of a conservative substance in a stream-aquifer system. The solutions are obtained by solving sequentially the groundwater flow and mass transport equations. A variational approach in conjunction with the finite element method is used to solve the groundwater flow equation. Galerkin's approach coupled with the finite element method is used to solve the mass transport equation. Linear approximated triangular elements and a centered scheme of numerical integration are employed to calculate the hydraulic head distribution and the concentration of solute in the flow region. The linear approximation used to define the concentration function within each element is not appropriate for cases involving steep concentration gradients. For such cases, higher order approximations are necessary to assure the continuity of gradients across interelemental boundaries. Numerical examples that illustrate the applicability of the model are presented. [ABSTRACT FROM AUTHOR]

BSTRACT. The response of stream-unconfined aquifer systems to localized recharge is investigated by means of a two-dimensional finite element model. A variational approach is used in conjunction with the finite element method to solve the ground water flow equation. Linear approximated triangular elements are used to calculate the hydraulic head distribution in the flow region. The Crank-Nicholson centered scheme of numerical integration is employed to approximate the time derivative in the flow equation. A computer program is developed to calculate the hydraulic head distribution in the flow region. Solutions provided by the finite element model should prove useful in the evaluation of quantitative and qualitative changes in aquifer systems due to natural or artificial recharge. In addition, they should prove useful in the study of irrigation and drainage problems. [ABSTRACT FROM AUTHOR]

Identifies a chromosomal locus containing three consecutive open reading frames in Staphylococcus aureus to investigate iron uptake. Molecular characterization of the iron-hydroxamate uptake system in S. aureus; Role of the fhu operon; Impaired ferrichrome-iron uptake shown by the fhuBeta mutant strain.

Background and Aims Cellular and animal models investigating extremely low frequency magnetic fields (ELF-MF) have reported promotion of leukocyte-endothelial interactions, angiogenesis, myofibroblast and keratinocyte proliferation, improvement of peripheral neuropathy and diabetic wound healing. In humans, it has also been reported that systemic exposure to ELF-MF stimulates peripheral blood mononuclear cells, promoting angiogenesis and healing of chronic leg ulcers. The aim of the study was to investigate the effect of exposing different blood volumes to specific ELF-MFs (120 Hz sinusoidal waves of 0.4–0.9 mT RMS) to induce healing of diabetic foot ulcers (DFUs). Methods Twenty six diabetic patients with non-responsive DFUs were divided into two exposure groups to receive treatment and record healing time. The forearm group, exposed to ELF-MF 2 h/day, twice weekly (3.6 l of blood/session); and the thorax group, exposed 25 min/day, 2 times/week (162.5 l of blood/session). Treatment period was 100 days or upon complete healing. Ulcer recurrences and adverse effects were investigated during short-term (<1 year) and long-term (3.4–7.8 years) follow-up. Results Mean healing time was 61.48 ± 33.08 days in the forearm group and 62.56 ± 29.33 days for the thorax group. No adverse effects or ulcer recurrences in the original ulcer site were reported during treatment, the short-term follow-up period or the long-term follow-up period in both groups. Conclusions Healing time was independent of the amount of blood exposed to ELF-MF used in this trial. ELF-MFs are effective and safe and could be applied to non-healing DFUs in conjunction with other preventive interventions to reduce DFUs complications. [ABSTRACT FROM AUTHOR]