Sensitivity of multi-product two-stage economic lotsizing models and their dependency on change-over and product cost ratio's

This study considers the production and inventory management problem of a two-stage semi-process production system. In case both production stages are physically connected it is obvious that materials are forced to flow. The economic lotsize depends on the holding cost of the end-product and the combined change-over cost of both production stages. On the other hand this 'flow shop' is forced to produce at the speed of the slowest stage. The benefit of this approach is the low amount of Work In Process inventory. When on the other hand, the involved stages are physically disconnected, a stock of intermediates acts as a decoupling point. Typically for the semi-process industry are high change-over costs for the process oriented first stage, which results in large lotsize differences for the different production stages. Using the stock of intermediates as a decoupling point avoids the complexity of synchronising operations but is an additional reason to augment the intermediate stock position. The disadvantage of this model is the high amount of Work-In-Process inventory. This paper proposes the 'synchronised planning model' realising a global optimum instead of the combination of two locally optimised settings. The mathematical model proves (for a two-stage single-product setting) that the optimal two-stage production frequency corresponds with the single EOQ solution for the first stage. A sensitivity study reveals, within these two-stage lotsizing models, the economical cost dependency on product and change-over cost ratio‟s. The purpose of this paper is to understand under which conditions the „joined setup‟ or the „two-stage individual eoq model‟ remain close to the optimal model. Numerical examples prove that the conclusions about the optimal settings remain valid when extending the model to a two-stage multi-product setting. The research reveals that two-stage individually optimized EOQ lotsizing should only be used when the end-product stage has a high added value and small change-over costs, compared to the first stage. Physically connected operations should be used when the end-product stage has a small added value and low change-over costs, or high added value and large change-over costs compared to the first production stage. The paper concludes with suggesting a practical common cycle approach to tackle a two-stage multi-product production and inventory management problem. The common cycle approach brings the benefit of a repetitive and predictable production schedule

Hurdles in investigating UVB damage in the putative ancient asexual Darwinula stevensoni (Ostracoda, Crustacea)

Ostracoda or mussel-shrimps are small, bivalved Crustacea. Because of their excellent fossil record and their broad variety of reproductive modes, ostracods are of great interest as a model group in ecological and evolutionary research. Here, we investigated damage and repair of one of the most important biological mutagens, namely UVB radiation in the putative ancient asexual ostracod Darwinula stevensoni from Belgium. We applied three different methods: the Polymerase Inhibition (PI) assay, Enzyme-Linked Immuno Sorbent Assay (ELISA) and dot blot. All three techniques were unsuccessful in quantifying UVB damage in D. stevensoni. Previous experiments have revealed that the valves of D. stevensoni provide an average UVB protection of approximate 60%. Thus, UVB damage could be too little to make quantitative experiments work. Additional variation between individual ostracods due to season and age most likely contributed further to the failure of the three used experimental approaches. In a second experiment, we investigated the influence of temperature on survival of D. stevensoni during UVB exposure. The estimated lethal UVB dose at 4°C was with 50 kJ/m2 significantly lower than at room temperature with 130 kJ/m2. This could either indicate adaptation to low temperatures and/or the presence of metabolic processes against UVB damage in D. stevensoni. These results could also explain why the estimated lethal UVB dose of D. stevensoni is similar to that of other non-marine ostracods where valves provide around 80% protection, although the valves of D. stevensoni provide less protection. If such metabolic processes can repair UVB damage fast, they might be an alternative explanation why we could not quantify UVB damage in D. stevensoni

The addition of bevacizumab to standard chemotherapy in breast cancer : which patient benefits the most?

Bevacizumab, a humanized monoclonal antibody directed against vascular endothelial growth factor, is an effective and well-tolerated treatment option for patients with breast cancer. Bevacizumab has demonstrated a gain in progression-free survival and a trend towards an overall survival benefit in various subgroups of breast cancer. Given the lack of a predictive biomarker, we performed a literature search with regard to efficacy and tolerability of bevacizumab in different subgroups of breast cancer patients and in different settings. In the metastatic setting, the efficacy of bevacizumab has been most extensively studied and demonstrated in patients with triple-negative breast cancer, the most difficult-to-treat population among patients with advanced disease and also the group with the biggest need for new treatment options. Overall, bevacizumab is well tolerated with very few serious adverse events. Bevacizumab is also an active and feasible treatment option for patients above 70 years of age

Auditory discrimination of rise and decay times

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Ostracod valves as efficient UV protection

One of the major consequences of climate change is the increase of ultraviolet radiation, especially UVB (280-315 nm). This has important consequences for organisms and ecosystems. In surface freshwater ecosystems with transparent water, UV can easily penetrate deeply. Here, we used three different experimental approaches to examine the response of non-marine ostracods and cladocerans to UVB radiation: estimating lethal doses, determining how much UVB is blocked by the valves, and analysing valve chemical compositions. For most investigated crustaceans, we found a strong correlation between the amount of UVB that is blocked by the valves and the lethal UVB doses. Most ostracod valves blocked between 60% and 80% of UVB radiation, thus providing effective shielding. Pigmented species from temporary habitats were best protected. These species also showed high lethal UVB doses of 110 kJ m 2 to 214 kJ m 2. In the waterflea Daphnia magna, valves only stopped ca 35% of UVB radiation, and the lethal dose was half that of the doses estimated for ostracods. Since there were no significant differences in chemical composition of the valves between the investigated species, other factors must be responsible for the observed differences, which remain to be identified

Primary intestinal type adenocarcinoma of the female genital tract, arisen from a tubulo-villous adenoma : case report

► An extremely rare neoplasm, especially in the absence of DES ► It's important to distinguish it from an adenocarcinoma from another location ► Little is known about the aetiology, several explanations have been postulated