547 research outputs found
Study of permeability characteristics of membranes Quarterly reports, 9 Nov. 1967 - 9 Apr. 1968
Permeability characteristics and transport properties of membranes for salt water conversion, and experiment design
Study of permeability characteristics of membranes Quarterly report, 9 Feb. - 9 May 1969
Permeability characteristics of membrane
Study of permeability characteristics of membranes Quarterly report, 9 May - 9 Aug. 1969
Demineralizing gear pump system with mixed bed ion exchange columns for salt and volume transport experimen
Study of permeability characteristics of membranes Quarterly report
Permeability characteristics of cation-exchange membranes based on transport measurement
Study of permeability characteristics of membranes Quarterly progress report, 9 Apr. - 9 Aug. 1968
Electrochemical cell constructed to measure membrane transport propertie
The impact of freight transport capacity limitations on supply chain dynamics
We investigate how capacity limitations in the transportation system affect the dynamic behaviour of supply chains. We are interested in the more recently defined, 'backlash' effect. Using a system dynamics simulation approach, we replicate the well-known Beer Game supply chain for different transport capacity management scenarios. The results indicate that transport capacity limitations negatively impact on inventory and backlog costs, although there is a positive impact on the 'backlash' effect. We show that it is possible for both backlog and inventory to simultaneous occur, a situation which does not arise with the uncapacitated scenario. A vertical collaborative approach to transport provision is able to overcome such a trade-off. © 2013 Taylor & Francis
The value of nonlinear control theory in investigating the underlying dynamics and resilience of a grocery supply chain
In an empirical context, a method to use nonlinear control theory in the dynamic analysis of supply chain resilience is developed and tested. The method utilises block diagram development, transfer function formulation, describing function representation of nonlinearities and simulation. Using both ‘shock’ or step response and ‘filter’ or frequency response lenses, a system dynamics model is created to analyse the resilience performance of a distribution centre replenishment system at a large grocery retailer. Potential risks for the retailer’s resilience performance include the possibility of a mismatch between supply and demand, as well as serving the store inefficiently and causing on-shelf stock-outs. Thus, resilience is determined by investigating the dynamic behaviour of stock and shipment responses. The method allows insights into the nonlinear system control structures that would not be evident using simulation alone, including a better understanding of the influence of control parameters on dynamic behaviour, the identification of inventory offsets potentially leading to ‘drift’, the impact of nonlinearities on supply chain performance and the minimisation of simulation experiments
A Tale of Three Cities : OmegaCAM discovers multiple sequences in the color-magnitude diagram of the Orion Nebula Cluster
Reproduced with permission from Astronomy & Astrophysics, © 2017 ESO. Published by EDP Sciences.As part of the Accretion Discs in H with OmegaCAM (ADHOC) survey, we imaged in r, i and H-alpha a region of 12x8 square degrees around the Orion Nebula Cluster. Thanks to the high-quality photometry obtained, we discovered three well-separated pre-main sequences in the color-magnitude diagram. The populations are all concentrated towards the cluster's center. Although several explanations can be invoked to explain these sequences we are left with two competitive, but intriguing, scenarios: a population of unresolved binaries with an exotic mass ratio distribution or three populations with different ages. Independent high-resolution spectroscopy supports the presence of discrete episodes of star formation, each separated by about a million years. The stars from the two putative youngest populations rotate faster than the older ones, in agreement with the evolution of stellar rotation observed in pre-main sequence stars younger than 4 Myr in several star forming regions. Whatever the final explanation, our results prompt for a revised look at the formation mode and early evolution of stars in clusters.Peer reviewedFinal Published versio
Cerebral cavernous malformations associated to meningioma: High penetrance in a novel family mutated in the PDCD10 gene
Multiple familial meningiomas occur in rare genetic syndromes, particularly neurofibromatosis type 2. The association of meningiomas and cerebral cavernous malformations (CCMs) has been reported in few patients in the medical literature. The purpose of our study is to corroborate a preferential association of CCMs and multiple meningiomas in subjects harbouring mutations in the PDCD10 gene (also known as CCM3). Three members of an Italian family affected by seizures underwent conventional brain Magnetic Resonance Imaging (MRI) with gadolinium contrast agent including gradient echo (GRE) imaging. The three CCM-causative genes were sequenced by Sanger method. Literature data reporting patients with coexistence of CCMs and meningiomas were reviewed. MRI demonstrated dural-based meningioma-like lesions associated to multiple parenchymal CCMs in all affected individuals. A disease-causative mutation in the PDCD10 gene (p.Gln112PhefsX13) was identified. Based on neuroradiological and molecular data as well as on literature review, we outline a consistent association between PDCD10 mutations and a syndrome of CCMs with multiple meningiomas. This condition should be considered in the differential diagnosis of multiple/familial meningioma syndromes. In case of multiple/familial meningioma the use of appropriate MRI technique may include GRE and/or susceptibility-weighted imaging (SWI) to rule out CCM. By contrast, proper post-gadolinium scans may aid defining dural lesions in CCM patients and are indicated in PDCD10-mutated individuals
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