An inventory model for multiple items assuming time-varying demands and limited storage

Producción CientíficaA model for inventory systems with multiple products is studied. Demands of items are time-dependent and follow power patterns. Shortages are allowed and fully back logged. For this inventory system, our findings provide the efficient inventory policy that helps decision-makers to obtain the initial inventory levels and the reorder points that maximize the profit per unit time. Moreover, when it is assumed that the warehouse used for the storage of products has a limited capacity, the optimal inventory policy is also developed. The model presented here extends some inventory systems studied by other authors. Numerical examples are introduced to illustrate the applicability of the theoretical results presented.Ministerio de Ciencia, Innovación y Universidades cofinanciado por la Comunidad Europea (FEDER) (project MTM2017-84150-P)Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

Optimal price and lot size for an EOQ model with full backordering under power price and time dependent demand

Producción CientíficaIn this paper, we address an inventory system where the demand rate multiplicatively combines the effects of time and selling price. It is assumed that the demand rate is the product of two power functions, one depending on the selling price and the other on the time elapsed since the last inventory replenishment. Shortages are allowed and fully backlogged. The aim is to obtain the lot sizing, the inventory cycle and the unit selling price that maximize the profit per unit time. To achieve this, two efficient algorithms are proposed to obtain the optimal solution to the inventory problem for all possible parameter values of the system. We solve several numerical examples to illustrate the theoretical results and the solution methodology. We also develop a numerical sensitivity analysis of the optimal inventory policy and the maximum profit with respect to the parameters of the demand function.Ministerio de Ciencia, Innovación y Universidades y Fondo Europeo de Desarrollo Regional (FEDER) - (Project MTM2017-84150-P

An inventory system with time-dependent demand and partial backordering under return on inventory investment maximization

Producción CientíficaIn this article, we study an inventory system for items that have a power demand pattern and where shortages are allowed. We suppose that only a fixed proportion of demand during the stock-out period is backordered. The decision variables are the inventory cycle and the ratio between the initial stock and the total quantity demanded throughout the inventory cycle. The objective is to maximize the Return on Inventory Investment (ROII) defined as the ratio of the profit per unit time over the average inventory cost. After analyzing the objective function, the optimal global solutions for all the possible cases of the inventory problem are determined. These optimal policies that maximize the ROII are, in general, different from those that minimize the total inventory cost per unit time. Finally, a numerical sensitivity analysis of the optimal inventory policy with respect to the system input parameters and some useful managerial insights derived from the results are presented.Ministerio de Ciencia, Innovación y Universidades - Fondo Europeo de Desarrollo Regional (project MTM2017-84150-P

Profitability index maximization in an inventory model with a price- and stock-dependent demand rate in a power-form

Producción CientíficaThis paper presents the optimal policy for an inventory model where the demand rate potentially depends on both selling price and stock level. The goal is the maximization of the profitability index, defined as the ratio income/expense. A numerical algorithm is proposed to calculate the optimal selling price. The optimal values for the depletion time, the cycle time, the maximum profitability index, and the lot size are evaluated from the selling price. The solution shows that the inventory must be replenished when the stock is depleted, i.e., the depletion time is always equal to the cycle time. The optimal policy is obtained with a suitable balance between ordering cost and holding cost. A condition that ensures the profitability of the financial investment in the inventory is established from the initial parameters. Profitability thresholds for several parameters, including the scale and the non-centrality parameters, keeping all the others fixed, are evaluated. The model with an isoelastic price-dependent demand is solved as a particular case. In this last model, all the optimal values are given in a closed form, and a sensitivity analysis is performed for several parameters, including the scale parameter. The results are illustrated with numerical examples.Ministerio de Ciencia, Innovación y Universidades y Fondo Europeo de Desarrollo Regional (FEDER) - (project MTM2017-84150-P

Optimal policy for multi-item systems with stochastic demands, backlogged shortages and limited storage capacity

Producción CientíficaIn this paper, an inventory model for multiple products with stochastic demands is developed. The scheduling period or inventory cycle is known and prescribed. Demands are independent random variables and they follow power patterns throughout the inventory cycle. For each product, an aggregate cycle demand is realized first and then the demand is released to the inventory system gradually according to power patterns within a cycle. These demand patterns express different ways of drawing units from inventory and can be a good approach to modelling customer demands in inventory systems. Shortages are allowed and they are fully backlogged. It is assumed that the warehouse where the items are stored has a limited capacity. For this inventory system, we determine the inventory policy that maximizes the expected profit per unit time. An efficient algorithmic approach is proposed to calculate the optimal inventory levels at the beginning of the inventory cycle and to obtain the maximum expected profit per unit time. This inventory model is applicable to on-line sales of a wide variety of products. In this type of sales, customers do not receive the products at the time of purchase, but sellers deliver goods a few days later. Also, this model can be used to represent inventories of products for in-shop sales when the withdrawal of items from the inventory is not at the purchasing time, but occurs in a period after the sale of the products. This inventory model extends various inventory systems studied by other authors. Numerical examples are introduced to illustrate the theoretical results presented in this work.Ministerio de Ciencia, Innovación y Universidades - Fondo Europeo de Desarrollo Regional (project MTM2017-84150-P

Second Look After Retromuscular Repair With the Combination of Absorbable and Permanent Meshes.

Objective: The aim of this study is to describe the macroscopic features and histologic details observed after retromuscular abdominal wall reconstruction with the combination of an absorbable mesh and a permanent mesh. Methods: We have considered all patients that underwent abdominal wall reconstruction (AWR) with the combination of two meshes that required to be reoperated for any reason. Data was extracted from a prospective multicenter study from 2012 to 2019.Macroscopic evaluation of parietal adhesions and histological analysis were carried out in this group of patients. Results: Among 466 patients with AWR, we identified 26 patients that underwent a reoperation after abdominal wall reconstruction using absorbable and permanent mesh. In eight patients, the reoperation was related to abdominal wall issues: four patients were reoperated due to recurrence, three patients required an operation for chronic mesh infection and one patient for symptomatic bulging. A miscellanea of pathologies was the cause for reoperation in 18 patients. During the second surgical procedures made after a minimum of 3 months follow-up, a fibrous tissue between the permanent mesh covering and protecting the peritoneum was identified. This fibrous tissue facilitated blunt dissection between the permanent material and the peritoneum. Samples of this tissue were obtained for histological examination. No case of severe adhesions to the abdominal wall was seen. In four cases, the reoperation could be carried out laparoscopically with minimal adhesions from the previous procedure. Conclusions: The reoperations performed after the combination of absorbable and permanent meshes have shown that the absorbable mesh acts as a protective barrier and is replaced by a fibrous layer rich in collagen. In the cases requiring new hernia repair, the layer between peritoneum and permanent mesh could be dissected without special difficulty. Few intraperitoneal adhesions to the abdominal wall were observed, mainly filmy, easy to detach, facilitating reoperations.post-print6360 K

Stepwise transversus abdominis muscle release for the treatment of complex bilateral subcostal incisional hernias.

Background Management of subcostal incisional hernias is particularly complicated due to their proximity to the costochondral limits in addition to the lack of aponeurosis on the lateral side of the abdomen. We present our results of posterior component separation through the same previous incision as a safe and reproducible technique for these complex cases. Methods We present a multicenter and prospective cohort of patients diagnosed with bilateral subcostal incisional hernias on either clinical examination or imaging based on computed tomography from 2014 to 2020. The aim of this investigation was to assess the outcomes of abdominal wall reconstruction for subcostal incisional hernias through a new approach. The outcomes reported were short- and long-term complications, including recurrence, pain, and bulging. Quality of life was assessed with the European Registry for Abdominal Wall Hernias Quality of Life score. Results A total of 46 patients were identified. All patients underwent posterior component separation. Surgical site occurrences occurred in 10 patients (22%), with only 7 patients (15%) requiring procedural intervention. During a mean follow-up of 18 (range, 6–62), 1 (2%) case of clinical recurrence was registered. In addition, there were 8 (17%) patients with asymptomatic but visible bulging. The European Registry for Abdominal Wall Hernias Quality of Life score showed a statistically significant decrease in the 3 domains (pain, restriction, and cosmetic) of the postoperative compared with the preoperative scores. Conclusion Posterior component separation technique for the repair of subcostal incisional hernias through the same incision is a safe procedure that avoids injury to the linea alba. It is associated with acceptable morbidity, low recurrence rate, and improvement in patients’ reported outcomes.pre-print371 K

Expression of p53 protein isoforms predicts survival in patients with multiple myeloma

Loss and/or mutation of the TP53 gene are associated with short survival in multiple myeloma, but the p53 landscape goes far beyond. At least 12 p53 protein isoforms have been identified as a result of a combination of alternative splicing, alternative promoters and/or alternative transcription site starts, which are grouped as α, β, γ, from transactivation domain (TA), long, and short isoforms. Nowadays, there are no studies evaluating the expression of p53 isoforms and its clinical relevance in multiple myeloma (MM). We used capillary nanoimmunoassay to quantify the expression of p53 protein isoforms in CD138‐purified samples from 156 patients with newly diagnosed MM who were treated as part of the PETHEMA/GEM2012 clinical trial and investigated their prognostic impact. Quantitative real‐time polymerase chain reaction was used to corroborate the results at RNA levels. Low and high levels of expression of short and TAp53β/γ isoforms, respectively, were associated with adverse prognosis in MM patients. Multivariate Cox models identified high levels of TAp53β/γ (hazard ratio [HR], 4.49; p < .001) and high‐risk cytogenetics (HR, 2.69; p < .001) as independent prognostic factors associated with shorter time to progression. The current cytogenetic‐risk classification was notably improved when expression levels of p53 protein isoforms were incorporated, whereby high‐risk MM expressing high levels of short isoforms had significantly longer survival than high‐risk patients with low levels of these isoforms. This is the first study that demonstrates the prognostic value of p53 isoforms in MM patients, providing new insights on the role of p53 protein dysregulation in MM biology

Transfer to the Local Stroke Center vs Direct Transfer to Endovascular Center of Acute Stroke Patients with Suspected Large Vessel Occlusion in the Catalan Territory (RACECAT): study protocol of a cluster randomized within a cohort trial

Rationale: Optimal pre-hospital delivery pathways for acute stroke patients suspected to harbor a large vessel occlusion (LVO) have not been assessed in randomized trials. Aim: To establish whether stroke subjects with RACE scale based suspicion of LVO evaluated by Emergency Medical Services in the field, have higher rates of favorable outcome when transferred directly to an Endovascular Center (EVT-SC), as compared to the standard transfer to the closest Local Stroke Center (Local-SC).Design: Multicenter, superiority, cluster randomized within a cohort trial with blinded endpoint assessment. Procedure: Eligible patients must be 18 or older, have acute stroke symptoms and not have an immediate life threatening condition requiring emergent medical intervention. They must be suspected to have intracranial LVO based on a pre-hospital RACE scale of ≥5, be located in geographical areas where the default health authority assigned referral stroke center is a non-thrombectomy capable hospital, and estimated arrival at a thrombectomy capable stroke hospital in less than 7 hours from time last seen well. Cluster randomization is performed according to a pre-established temporal sequence (temporal cluster design) with 3 strata: day/night, distance to the EVT-SC and week/week-end day. Study outcome: The primary endpoint is the modified Rankin Scale (mRS) score at 90 days. The primary safety outcome is mortality at 90 days. Analysis: The primary endpoint based on the modified intention-to-treat population is the distribution of modified Rankin Scale scores (mRS) at 90 days analyzed under a sequential triangular design. The maximum sample size is 1754 patients, with two planned interim analyses when 701 (40%) and 1227 patients have completed follow-up. Hypothesized common odds ratio is 1.35.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The trial is sponsored by the nonprofit foundation Fundació Privada Ictus Malaltia Vascular, beneficiary of an unrestricted grant by Medtronic. Trial sponsor: Fundació Privada Ictus Malaltia Vascular. Elisabeth Ortínez ([email protected]). Study sponsor and funders do not participate in the study design, collection, management, analysis and interpretation of data, writing of the report or the decision to submit results for publication

Prediction of peripheral neuropathy in multiple myeloma patients receiving bortezomib and thalidomide: a genetic study based on a single nucleotide polymorphism array

GEM (Grupo Español de MM)/PETHEMA (Programa para el Estudio de la Terapéutica en Hemopatías Malignas) cooperative study group.Bortezomib- and thalidomide-based therapies have significantly contributed to improved survival of multiple myeloma (MM) patients. However, treatment-induced peripheral neuropathy (TiPN) is a common adverse event associated with them. Risk factors for TiPN in MM patients include advanced age, prior neuropathy, and other drugs, but there are conflicting results about the role of genetics in predicting the risk of TiPN. Thus, we carried out a genome-wide association study based on more than 300 000 exome single nucleotide polymorphisms in 172 MM patients receiving therapy involving bortezomib and thalidomide. We compared patients developing and not developing TiPN under similar treatment conditions (GEM05MAS65, NCT00443235). The highest-ranking single nucleotide polymorphism was rs45443101, located in the PLCG2 gene, but no significant differences were found after multiple comparison correction (adjusted P =.1708). Prediction analyses, cytoband enrichment, and pathway analyses were also performed, but none yielded any significant findings. A copy number approach was also explored, but this gave no significant results either. In summary, our study did not find a consistent genetic component associated with TiPN under bortezomib and thalidomide therapies that could be used for prediction, which makes clinical judgment essential in the practical management of MM treatment.This work has been partially supported by grants of the Instituto de Salud Carlos III (ISCIII) (CP13/00080), ISCIII (PI12/02311), Red Temática de Investigación Cooperativa en Cáncer (RD12/0036/0069) (RD12/0036/0061), Ministerio de Economía y Competitividad/ Fondo Europeo de Desarrollo Regional (FEDER) “Una manera de hacer Europa” (Innocampus; CEI‐2010‐1‐0010), Asociación Española Contra el Cancer (GCB120981SAN), and Joan Rodes (JR 14/00016). M.E.S. is supported by the Miguel Servet program (CP13/00080) of the ISCIII (Ministerio de Economía y Competitividad).Peer Reviewe