A functional central limit theorem for a modulated network of infinite-server queues

International audienc

Influence of nontrophic interactions between benthic invertebrates on river sediment processes: a microcosm study

The main objective of this study was to measure the impact of benthic invertebrate diversity on river sediment processes. We quantified the effects of interactions between three taxa (asellids, chironomid larvae, and tubificid worms). The impacts of different taxa richness treatments were measured on sediment reworking, O2 concentrations, bacterial abundances, and numbers of active bacteria in slow filtration sand–gravel columns. The coefficients of sediment reworking measured in multitaxa treatments were lower than those predicted from one-taxon treatments. The interactions among invertebrates also significantly reduced O2 concentrations in sediments. These results were probably due to interactions between the different sediment structures produced by each taxon (tubes, macropores, and fecal pellets) that modified water flow and associated microbial activities in the interstitial habitat. The stimulation of aerobic microbial processes with two- and three-taxa treatments, whereas one-taxon treatments could increase or decrease O2 consumption in columns, indicates that interactions among invertebrates limited the variability of the system functioning. We suggest that, beyond a small number of detritivorous taxa, a threshold effect on bioturbation process and microbial activities was produced by animals in the experimental system. Finally, the interactions between taxa played a significant role in microbial processes in the system studied

The Cost Impact of Spam Filters: Measuring the Effect of Information System Technologies in Organizations

More than 70% of global e-mail traffic consists of unsolicited and commercial direct marketing, also known as spam. Dealing with spam incurs high costs for organizations, prompting efforts to try to reduce spam-related costs by installing spam filters. Using modern econometric methods to reduce the selection bias of installing a spam filter, we deploy a unique data setting implemented at a German university to measure the costs associated with spam and the costs savings of spam filters. The applied methodological framework can easily be transferred to estimate the effect of other IS technologies (e.g., SAP) implemented in organizations. Our findings indicate that central IT costs are of little relevance since the majority of spam costs stem from employees who spend working time identifying and deleting spam. The working time losses caused by spam are approximately 1,200 minutes per employee per year; these costs could be reduced by roughly 35% through the installation of a spam filter mechanism. The individual efficiency of a spam filter installation depends on the amount of spam that is received and on the level of knowledge about spam.propensity score matching, treatment effects, spam filter, spam

Latest clinical recommendations on valproate use for migraine prophylaxis in women of childbearing age. Overview from European Medicines Agency and European Headache Federation

Migraine is a common and burdensome neurological condition which affects mainly female patients during their childbearing years. Valproate has been widely used for the prophylaxis of migraine attacks and is also included in the main European Guidelines. Previous (2014) European recommendations on limiting the use of valproate in women of childbearing age did not achieve their objective in terms of limiting the use of valproate in women of childbearing age and raising awareness regarding the hazardous effect of valproate to children exposed in utero. The teratogenic and foetotoxic effects of valproate are well documented, and more recent studies show that there is an even greater neurodevelopmental risk to children exposed to valproate in the womb. The latest 2018 European review from the European Medicines Agency, with the active participation of the European Headache Federation, concluded that not enough has been done to mitigate the risks associated with in utero exposure to valproate. The review called for more extensive restrictions to the conditions for prescribing, better public awareness, and a more effective education campaign in migrainous women

Predicting inspection outcomes and evaluating port state control targeting using random forests

This study uses global inspection data of 790k inspections and 1.5 million deficiencies (2013 to 2021) which is complemented by 500k incidents and ship particulars of 132k unique vessels. The results show that over 70% of ships that had very serious and serious incidents (2020 to 2021) were not inspected and only 2.5% were detained. The global averages of percentage of inspections without deficiencies is around 50% with high variability across the port state control (PSC) regimes (2013 to 2021). Since there is ample room for improvement to target risky vessels for inspection, it is not recommended to continue with the status quo of the industry by using detention alone as proxy to target future risk. Instead, the study develops 13 prediction models for detention and deficiency types using ML methods by evaluating over 400 risk factors. The results vary across the endpoint of interest but overall, the normal random forests variants outperform the other variants. The top 5 most influential covariates towards prediction are found to be the size of the vessel (GRT), age, previous number of deficiencies within 365 days prior to the inspection, the year of existence of the beneficial owner and safety manager company. These prediction models can be combined with incident type models to enhance targeting of risky vessels and reduce future incidents compared to the current status quo of 70% false negative events

Predicting detention and deficiencies using random forests

The aim of this exploration study is to predict detention and twelve deficiency types which can be used to enhance port state control targeting as well as domain awareness for coastal administrations. A total of 234 combinations of random forest variants are explored evaluating over 400 covariates. The study uses a comprehensive and unique, global inspection dataset of over 200k inspections and 400k deficiencies (2014 to 2019) and out of sample data from 2020 to 2021 for evaluation. The results show that based on the used data, normal random forests outperform other variants and overall detention has the highest decile lift with 3 or higher compared to random selection. This is followed by the deficiency groups safety of navigation, certificates and qualification and the Maritime Labor Convention. Deficiencies related to newer areas such as MARPOL Annex VI, ballast water treatment and anti-fouling are more difficult to predict and are also more difficult to detect compared to other areas where detection often depend on the training and background of inspectors. Future work will evaluate further model variants and evaluate inspection policies by filtering out high risk vessels that were missed

Visualization of differences across port state control regimes by means of correspondence analysis

This article is based on a combined dataset of 183,819 port state control (PSC) inspections from various port state control regimes around the world. In theory, there should be no differences in treatments of inspections to determine if a vessel is substandard or not no matter where the inspection was performed. This article uses correspondence analysis in order to investigate whether there are differences and if so, visualizes them for easier interpretation. The results of this analysis confirm that treatment of vessels across port state control regimes differ although some groupings of regimes across the ownership groups can be found. Association can be found between the Paris MoU and the Viña del Mar Agreement and between the Caribbean MoU and the Indian Ocean MoU while the USCG and AMSA are always apart from the rest. With respect to the distribution of deficiency codes towards regimes, only areas such as structural safety, radio communications or safety and cargo operational areas show similarities while ISM related deficiencies only show strong association with one regime. The differences clearly show that there is room for harmonization across port state control inspections in all inspection areas. Harmonization could be achieved by increasing cooperation amongst the regimes. A good starting point would be the acceleration of the harmonization of inspection procedures, combined training of port state control officers and the use of combined datasets across regimes, in particular in the concept of the development of the Global Integrated Ship Information System (GISIS) of the International Maritime Organization (IMO)

ELSID-diabetes study-evaluation of a large scale implementation of disease management programmes for patients with type 2 diabetes. Rationale, design and conduct : a study protocol

Background: Diabetes model projects in different regions of Germany including interventions such as quality circles, patient education and documentation of medical findings have shown improvements of HbA1c levels, blood pressure and occurrence of hypoglycaemia in before-after studies (without control group). In 2002 the German Ministry of Health defined legal regulations for the introduction of nationwide disease management programs (DMP) to improve the quality of care in chronically ill patients. In April 2003 the first DMP for patients with type 2 diabetes was accredited. The evaluation of the DMP is essential and has been made obligatory in Germany by the Fifth Book of Social Code. The aim of the study is to assess the effectiveness of DMP by example of type 2 diabetes in the primary care setting of two German federal states (Rheinland-Pfalz and Sachsen-Anhalt). Methods/Design: The study is three-armed: a prospective cluster-randomized comparison of two interventions (DMP 1 and DMP 2) against routine care without DMP as control group. In the DMP group 1 the patients are treated according to the current situation within the German-Diabetes-DMP. The DMP group 2 represents diabetic care within ideally implemented DMP providing additional interventions (e.g. quality circles, outreach visits). According to a sample size calculation a sample size of 200 GPs (each GP including 20 patients) will be required for the comparison of DMP 1 and DMP 2 considering possible drop-outs. For the comparison with routine care 4000 patients identified by diabetic tracer medication and age (> 50 years) will be analyzed. Discussion: This study will evaluate the effectiveness of the German Diabetes-DMP compared to a Diabetes-DMP providing additional interventions and routine care in the primary care setting of two different German federal states