We study the dynamic consequences of lost sales when there is insufficient inventory to satisfy demand. Demand is assumed to be independently and identically distributed and drawn from a normal ...distribution. We consider the industrially popular order-up-to policy with unit lead time is used to make replenishment orders. In this scenario, we obtain expressions for the order and inventory distributions, allowing us to quantify the Bullwhip and Net Stock Amplification ratios. We show that both these metrics are equivalent. We also determine the mean inventory levels held, and the achieved fill rate. We do this when the lost sales are fully observable, and when the lost sales are unobservable.
Closed-loop supply chains, incorporating circular economic principles, play a key role in enhancing the sustainability of production systems and creating economic opportunities for firms. In today's ...business environment, characterized by frequent disruptions, these systems need to be both efficient and resilient to remain competitive. However, integrating efficiency and resilience is not a straightforward task. This manuscript discusses control engineering as a promising approach to understand closed-loop supply chain resilience. It enables the analysis of the propagation of disruptions (the ripple effect), thus aiding managerial decision-making. We use an example to demonstrate the potential of control theory in improving the resilience of closed-loop supply chains.
Multiagent system for intelligent Water Demand Management Ponte, Borja; de la Fuente, David; Pino, Raul ...
2013 International Conference on New Concepts in Smart Cities: Fostering Public and Private Alliances (SmartMILE),
2013-Dec.
Conference Proceeding
The pressures exerted by the scarcity of resources and the respect to the environment, among other reasons, have led to the enormous current importance of the Water Demand Management. This means ...satisfying the demand using the least amount of resources, so that a fundamental aspect is the hourly forecast of this variable. This paper applies modern Artificial Intelligence techniques in solving this problem. More specifically, we have developed a Multiagent System aimed at decision-making in the management, such that it determines the optimal hourly quantity of pumped water that minimizes the management cost. The developed structure relies on complex forecasting methods, such as ARIMA techniques and Neural Networks, coordinated with other intelligent agents. According to the results achieved, this is an interesting alternative to face the problem.
Epistasis is the interaction between different genes when expressing a certain phenotype. If epistasis involves more than two loci it is called high-order epistasis. High-order epistasis is an area ...under active research because it could be the cause of many complex traits. The most common way to specify an epistasis interaction is through a penetrance table.
This paper presents PyToxo, a Python tool for generating penetrance tables from any-order epistasis models. Unlike other tools available in the bibliography, PyToxo is able to work with high-order models and realistic penetrance and heritability values, achieving high-precision results in a short time. In addition, PyToxo is distributed as open-source software and includes several interfaces to ease its use.
PyToxo provides the scientific community with a useful tool to evaluate algorithms and methods that can detect high-order epistasis to continue advancing in the discovery of the causes behind complex diseases.
Purpose:
To describe the clinical and genetic characteristics (mutation in
RS1
gene) of a Spanish family with X-linked retinoschisis (XLRS) associated with retinitis punctata albescens (RPA).
...Methods:
The detailed ophthalmological examination included best corrected visual acuity (BCVA), colour and autofluorescence photography, fluorescein angiography, optical coherence tomography and electrophysiology tests. A next-generation sequencing (NGS) strategy was applied to the index patient, and then sequenced in an Illumina NextSeq500 system. Candidate variants considered to be disease-causing in the patient were confirmed and segregated in the family by Sanger sequencing.
Results:
We have studied three siblings of 54, 59 and 50 years old. Two of them presented with macular foveoschisis and a whitish mottling of the pigment epithelium in the peripheral and equatorial retina, while the other had macular atrophy. Electroretinography revealed a reduced b-wave, while a-wave remained unchanged. Mutation in
RS1
(c.98G>A; p.Trp33*) was identified as the cause of the disease.
Conclusion:
XLRS is a genetic disease that leads to irreversible visual loss. We describe an unusual phenotype manifestation of a known mutation.
BACKGROUND AND OBJECTIVEThe diagnosis of retinal dystrophies is complex and is based on complete ophthalmological study, genetic study and electrophysiological studies (EPS). In this study, we intend ...to evaluate the role of electrophysiological and medical tests in the diagnosis of retinal dystrophies. MATERIAL AND METHODSA retrospective observational study was conducted on 50 selected patients that attended the Neurophysiology Department of the University Hospital Virgen Macarena. An analysis was made of the variables that included, gender, age, referral hospital, reason for which the EPS was requested, applied EPS, genetic study, presumed diagnosis, and definitive diagnosis after EPS. A classification system was subsequently developed, which gives each case a value between 0 and 2, depending on the contribution of the electrophysiological tests to the final diagnosis. RESULTSThe mean age was 44.34 ±18.03 years (60% women). Retinitis pigmentosa (24%), optic neuropathy (12%), and Stargardt's disease (8%) were the most frequent diagnoses. The EPS modified the presumed diagnosis in 48% of the cases, confirmed the diagnosis in 44%, and did not provide any useful information in 8%. The contribution of the EPS was greater in patients seen in the HUVM and when requested by findings in the examination (P=.001). The false positives in the diagnosis of retinal dystrophy were 60% in patients not evaluated by the University Hospital Virgen Macarena. CONCLUSIONSElectrophysiological test and specialised management of patients with retinal dystrophies play an important role in the diagnosis of these conditions.
The diagnosis of retinal dystrophies is complex and is based on complete ophthalmological study, genetic study and electrophysiological studies (EPS). In this study, we intend to evaluate the role of ...electrophysiological and medical tests in the diagnosis of retinal dystrophies.
A retrospective observational study was conducted on 50 selected patients that attended the Neurophysiology Department of the University Hospital Virgen Macarena. An analysis was made of the variables that included, gender, age, referral hospital, reason for which the EPS was requested, applied EPS, genetic study, presumed diagnosis, and definitive diagnosis after EPS. A classification system was subsequently developed, which gives each case a value between 0 and 2, depending on the contribution of the electrophysiological tests to the final diagnosis.
The mean age was 44.34±18.03 years (60% women). Retinitis pigmentosa (24%), optic neuropathy (12%), and Stargardt's disease (8%) were the most frequent diagnoses. The EPS modified the presumed diagnosis in 48% of the cases, confirmed the diagnosis in 44%, and did not provide any useful information in 8%. The contribution of the EPS was greater in patients seen in the HUVM and when requested by findings in the examination (p=.001). The false positives in the diagnosis of retinal dystrophy were 60% in patients not evaluated by the University Hospital Virgen Macarena.
Electrophysiological test and specialized management of patients with retinal dystrophies play an important role in the diagnosis of these conditions.
El diagnóstico de las distrofias retinianas es complejo y se basa en estudio oftalmológico completo, estudio genético y los estudios electrofisiológicos (EEF). En este estudio pretendemos evaluar el papel de las pruebas electrofisiológicas y del médico solicitante en el diagnóstico de las distrofias de retina.
Estudio observacional retrospectivo. Se seleccionaron 50 pacientes atendidos en el Servicio de Neurofisiología del Hospital Universitario Virgen Macarena. Se valoró el sexo, la edad, el hospital de origen, motivo por el que se solicitó los EEF, diagnóstico de presunción tras examen oftalmológico, EEF realizados, estudio genético y el diagnóstico definitivo tras realización de EEF. Se elaboró un sistema de clasificación que otorga a cada caso un valor comprendido entre 0 y 2, en función de la contribución de las pruebas electrofisiológicas al diagnóstico final.
La edad media fue 44,34± 18,03 años (60% mujeres). Retinosis pigmentaria, neuropatía óptica y enfermedad de Stargardt fueron los diagnósticos más frecuentes. Los EEF modificaron el diagnóstico de presunción en el 48% de los casos, confirmaron el diagnóstico en el 44% y no aportaron información en el 8%. La contribución de los EEF fue mayor en pacientes atendidos en el Hospital Universitario Virgen Macarena y cuando se solicitaban por hallazgos en la exploración (p=0,001). Los falsos positivos para distrofia retiniana fueron del 60% en pacientes no valorados en dicho hospital.
Las pruebas electrofisiológicas y el manejo especializado de los pacientes con distrofias retinianas desempeñan un papel importante en el diagnóstico de estas patologías.
To assess the knocking properties of natural gas (NG) when it is used as fuel for vehicles is vital to optimize the design and functioning of their motors. Analytical efforts in this field are needed ...as the engines used to define it empirically are not available anymore, and existent mathematical algorithms yield different accuracy. The hybridization of gas-phase infrared spectrometry and partial least squares multivariate regression is presented first time to address the determination of the methane number (MN) of NG samples. It circumvents the need for the previous knowledge of the NG composition required to apply dedicated equations. The use of true NG samples to develop the models is also quite new in the field. Proof-of-concept studies were made with synthetic spectra and, then, a collection of liquefied NG samples for which MN values were computed by the National Physics Laboratory algorithm (NPL) from their sample composition were used to develop operative models. Additional validation was made with a collection of synthetic standard mixtures prepared for two European projects (EMRP LNG II and EMPIR LNG III) whose service methane numbers (SMN) were measured with an engine. The FTIR-PLS approach yielded statistically unbiased predictions with average standard errors around 0.4% MN when compared to the NPL-MN and SMN values, and standard deviations of the means ca. 1% MN. The approach is fast, cost effective as it involves standard instrumentation, and can be considered compliant with the green chemistry principles.
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•PLS regression and IR spectrometry successfully predict methane number of LNG.•Average errors are lower than 0.5% and standard deviation lower than 1%.•Predictions were statistically unbiased.•Exploratory studies using synthetic spectra and real spectra strongly agreed.
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