1,193 research outputs found

    Reynolds and Mach number simulation of Apollo and Gemini re-entry and comparison with flight

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    Reynolds and Mach numbers simulation of Apollo and Gemini reentry compared with flight dat

    Morphology, growth characteristics and oestrogen-binding capacity of DMBA-induced mammary tumours from ovariectomized rats.

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    The morphology of 20 mammary adenocarcinomas induced by 7,12-dimethylbenz(a)anthracene (DMBA) in Sprague-Dawley rats was compared with their growth characteristics and oestrogen-binding capacity following ovariectomy. The capacity to bind (3H)oestradiol-17B did not appear to be related to the growth characteristics, time of appearance after DMBA administration, or time between ovariectomy and assay for specific oestrogen-binding proteins. Furthermore, different tumours appeared to have oestrogen-binding capacities unrelated to the percentage of neoplastic cells within the tumour, amount of inflammation, mast cell infiltration, or the presence of fluid-filled cysts. The only morphological features which appeared to be correlated with oestrogen-binding capacity were the number of mitoses and the lipid content of the tumour; that is, the oestrogen-binding capacity tended to be lower in tumours with moderate or large numbers of mitoses and in tumours with much lipid in the epithelial cells. Six of the 19 adenocarcinomas found prior to sacrifice either continued growing or remained static following ovariectomy, while the others underwent regression. In 5 of the regressing tumours a new growth phase was observed, usually beginning 2 months after ovariectomy. Tumours other thus osteosarcoma as well as fibroadenomas and Zymbal-gland tumours

    Supply chain forecasting when information is not shared

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    The operations management literature is abundant in discussions on the benefits of information sharing in supply chains. However, there are many supply chains where information may not be shared due to constraints such as compatibility of information systems, information quality, trust and confidentiality. Furthermore, a steady stream of papers has explored a phenomenon known as Downstream Demand Inference (DDI) where the upstream member in a supply chain can infer the downstream demand without the need for a formal information sharing mechanism. Recent research has shown that, under more realistic circumstances, DDI is not possible with optimal forecasting methods or Single Exponential Smoothing but is possible when supply chains use a Simple Moving Average (SMA) method. In this paper, we evaluate a simple DDI strategy based on SMA for supply chains where information cannot be shared. This strategy allows the upstream member in the supply chain to infer the consumer demand mathematically rather than it being shared. We compare the DDI strategy with the No Information Sharing (NIS) strategy and an optimal Forecast Information Sharing (FIS) strategy in the supply chain. The comparison is made analytically and by experimentation on real sales data from a major European supermarket located in Germany. We show that using the DDI strategy improves on NIS by reducing the Mean Square Error (MSE) of the forecasts, and cutting inventory costs in the supply chain

    Judgement and supply chain dynamics

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    Forecasting demand at the individual stock-keeping-unit (SKU) level often necessitates the use of statistical methods, such as exponential smoothing. In some organizations, however, statistical forecasts will be subject to judgemental adjustments by managers. Although a number of empirical and ‘laboratory’ studies have been performed in this area, no formal OR modelling has been conducted to offer insights into the impact such adjustments may have on supply chain performance and the potential development of mitigation mechanisms. This is because of the associated dynamic complexity and the situation-specific nature of the problem at hand. In conjunction with appropriate stock control rules, demand forecasts help decide how much to order. It is a common practice that replenishment orders may also be subject to judgemental intervention, adding further to the dynamic system complexity and interdependence. The system dynamics (SD) modelling method can help advance knowledge in this area, where mathematical modelling cannot accommodate the associated complexity. This study, which constitutes part of a UK government funded (EPSRC) project, uses SD models to evaluate the effects of forecasting and ordering adjustments for a wide set of scenarios involving: three different inventory policies; seven different (combinations of) points of intervention; and four different (combinations of) types of judgmental intervention (optimistic and pessimistic). The results enable insights to be gained into the performance of the entire supply chain. An agenda for further research concludes the paper

    Longitudinal Profiles of Girls' Irritable, Defiant and Antagonistic Oppositional Symptoms: Evidence for Group Based Differences in Symptom Severity

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    Three subdimensions of ODD symptoms have been proposed -angry/irritable (IR), argumentative/defiant (DF) and antagonism (AN). This study tested whether longitudinal symptom trajectories could be identified by these subdimensions. Group-based trajectory analysis was used to identify developmental trajectories of IR, DF and AN symptoms. Multi-group trajectory analysis was then used to identify how subdimension trajectories were linked together over time. Data were drawn from the Pittsburgh Girls Study (PGS; N = 2450), an urban community sample of girls between the ages of five--eight at baseline. We included five waves of annual data across ages five-13 to model trajectories. Three trajectories were identified for each ODD subdimension: DF and AN were characterized by high, medium and low severity groups; IR was characterized by low, medium stable, and high increasing groups. Multi-trajectory analysis confirmed these subdimensions were best linked together based on symptom severity. We did not identify girls' trajectory groups that were characterized predominantly by a particular subdimension of ODD symptoms. Membership in more severe symptom groups was significantly associated with worse outcomes five years later. In childhood and early adolescence girls with high levels of ODD symptoms can be identified, and these youth are characterized by a persistently elevated profile of IR, DF and AN symptoms. Further studies in clinical samples are required to examine the ICD-10 proposal that ODD with irritability is a distinct or more severe form of ODD

    Gravitational detection of a low-mass dark satellite at cosmological distance

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    The mass-function of dwarf satellite galaxies that are observed around Local Group galaxies substantially differs from simulations based on cold dark matter: the simulations predict many more dwarf galaxies than are seen. The Local Group, however, may be anomalous in this regard. A massive dark satellite in an early-type lens galaxy at z = 0.222 was recently found using a new method based on gravitational lensing, suggesting that the mass fraction contained in substructure could be higher than is predicted from simulations. The lack of very low mass detections, however, prohibited any constraint on their mass function. Here we report the presence of a 1.9 +/- 0.1 x 10^8 M_sun dark satellite in the Einstein-ring system JVAS B1938+666 at z = 0.881, where M_sun denotes solar mass. This satellite galaxy has a mass similar to the Sagittarius galaxy, which is a satellite of the Milky Way. We determine the logarithmic slope of the mass function for substructure beyond the local Universe to be alpha = 1.1^+0.6_-0.4, with an average mass-fraction of f = 3.3^+3.6_-1.8 %, by combining data on both of these recently discovered galaxies. Our results are consistent with the predictions from cold dark matter simulations at the 95 per cent confidence level, and therefore agree with the view that galaxies formed hierarchically in a Universe composed of cold dark matter.Comment: 25 pages, 7 figures, accepted for publication in Nature (19 January 2012

    Seizure burden and neurodevelopmental outcome in neonates with hypoxic-ischemic encephalopathy.

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    Aim: To examine the relationship between electrographic seizures and long-term outcome in neonates with hypoxic-ischemic encephalopathy (HIE). Method: Full-term neonates with HIE born in Cork University Maternity Hospital from 2003 to 2006 (pre-hypothermia era) and 2009 to 2012 (hypothermia era) were included in this observational study. All had early continuous electroencephalography monitoring. All electrographic seizures were annotated. The total seizure burden and hourly seizure burden were calculated. Outcome (normal/abnormal) was assessed at 24 to 48 months in surviving neonates using either the Bayley Scales of Infant and Toddler Development, Third Edition or the Griffiths Mental Development Scales; a diagnosis of cerebral palsy or epilepsy was also considered an abnormal outcome. Results: Continuous electroencephalography was recorded for a median of 57.1 hours (interquartile range 33.5-80.5h) in 47 neonates (31 males, 16 females); 29 out of 47 (62%) had electrographic seizures and 25 out of 47 (53%) had an abnormal outcome. The presence of seizures per se was not associated with abnormal outcome (p=0.126); however, the odds of an abnormal outcome increased over ninefold (odds ratio [OR] 9.56; 95% confidence interval [95% CI] 2.43-37.67) if a neonate had a total seizure burden of more than 40 minutes (p=0.001), and eightfold (OR: 8.00; 95% CI: 2.06-31.07) if a neonate had a maximum hourly seizure burden of more than 13 minutes per hour (p=0.003). Controlling for electrographic HIE grade or treatment with hypothermia did not change the direction of the relationship between seizure burden and outcome. Interpretation: In HIE, a high electrographic seizure burden is significantly associated with abnormal outcome, independent of HIE severity or treatment with hypothermia

    A standardised assessment scheme for conventional EEG in preterm infants

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    Objective: To develop a standardised scheme for assessing normal and abnormal electroencephalography (EEG) features of preterm infants. To assess the interobserver agreement of this assessment scheme. Methods: We created a standardised EEG assessment scheme for 6 different post-menstrual age (PMA) groups using 4 EEG categories. Two experts, not involved in the development of the scheme, evaluated this on 24 infants <32 weeks gestational age (GA) using random 2 hour EEG epochs. Where disagreements were found, the features were checked and modified. Finally, the two experts independently evaluated 2 hour EEG epochs from an additional 12 infants <37 weeks GA. The percentage of agreement was calculated as the ratio of agreements to the sum of agreements plus disagreements. Results: Good agreement in all patients and EEG feature category was obtained, with a median agreement between 80% and 100% over the 4 EEG assessment categories. No difference was found in agreement rates between the normal and abnormal features (p = 0.959). Conclusions: We developed a standard EEG assessment scheme for preterm infants that shows good interobserver agreement. Significance: This will provide information to Neonatal Intensive Care Unit (NICU) staff about brain activity and maturation. We hope this will prove useful for many centres seeking to use neuromonitoring during critical care for preterm infants

    The ISLANDS project I: Andromeda XVI, An Extremely Low Mass Galaxy not Quenched by Reionization

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    Based on data aquired in 13 orbits of HST time, we present a detailed evolutionary history of the M31 dSph satellite Andromeda XVI, including its life-time star formation history, the spatial distribution of its stellar populations, and the properties of its variable stars. And XVI is characterized by prolonged star formation activity from the oldest epochs until star formation was quenched ~6 Gyr ago, and, notably, only half of the mass in stars of And XVI was in place 10 Gyr ago. And XVI appears to be a low mass galaxy for which the early quenching by either reionization or starburst feedback seems highly unlikely, and thus, is most likely due to an environmental effect (e.g., an interaction), possibly connected to a late infall in the densest regions of the Local Group. Studying the star formation history as a function of galactocentric radius, we detect a mild gradient in the star formation history: the star formation activity between 6 and 8 Gyr ago is significantly stronger in the central regions than in the external regions, although the quenching age appears to be the same, within 1 Gyr. We also report the discovery of 9 RR Lyrae stars, 8 of which belong to And XVI. The RR Lyrae stars allow a new estimate of the distance, (m-M)0= 23.72+/-0.09 mag, which is marginally larger than previous estimates based on the tip of the red giant branch.Comment: Accepted for publication on Ap
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