Studies in local marketing

Wie in het winkelcentrum om de hoek goed rondkijkt, zal merken dat verschillende winkels hun assortiment hebben aangepast aan de specifieke behoeften van de buurt. Veel jonge gezinnen met kinderen? De schappen met babyvoedsel en luiers zullen uitpuilen. Maar ook zal een winkelier in een dure villabuurt andere merkartikelen aanbieden en een andere verkoopstrategie volgen dan zijn collega in een wijk met veel lage inkomens. In een meer verfijnde vorm heet deze strategie ‘local marketing’. Met behulp van interviews en enquêtes onderzocht Albert van Dijk hoe Nederlandse supermarkten local marketing toepassen. De resultaten daarvan verwerkte hij in een model waarmee winkeliers, winkelbedrijven en ook fabrikanten de effecten van local marketing beter kunnen voorspellen. Bron: RUG nieuws

INIBIZIONE DELL' ALDOSO REDUTTASI DA EMIACETALI

L'aldoso reduttasi (alditol:NADP oxidoreductase, EC 1.1.1.21) (AR) è un enzima citosolico monomerico, appartenente alla famiglia delle aldo-cheto reduttasi, in grado di agire su aldeidi sia aromatiche che alifatiche. Esso catalizza la prima tappa (che è anche quella limitante) della via dei polioli, che consiste nella riduzione NADPH-dipendente del glucosio in sorbitolo. La seconda tappa della suddetta via, catalizzata dalla sorbitolo deidrogenasi, converte il sorbitolo in fruttosio, in una reazione NAD+-dipendente. In condizioni fisiologiche, la via dei polioli coinvolge meno del 3% del glucosio totale presente nella cellula, poiché la quasi totalità dello zucchero viene fosforilato dalla esochinasi, che lo convoglia nella via glicolitica. In condizioni di iperglicemia, come nel caso dei soggetti diabetici, una quota di di glucosio diventa substrato dell'aldoso reduttasi e il flusso di glucosio attraverso la via dei polioli può interessare percentuali fino al 30%. del glucosio totale L’aumento di flusso attraverso la via dei polioli è considerato dannoso per una serie di ragioni: la prima riguarda l'accumulo di sorbitolo all'interno della cellula, che causa uno squilibrio osmotico tale da richiamare acqua dall'esterno, con gravi alterazioni del normale equilibrio elettrolitico. La seconda riguarda l’aumento della produzione di fruttosio che , essendo un agente glicante addirittura migliore del glucosio stesso, può indurre fenomeni di glicazione proteica. Infine, l’aumento del consumo di NADPH ad opera dell’AR determina una riduzione delle difese antiossidanti della cellula. Queste alterazioni metaboliche correlate con l’aumentato flusso attraverso la via dei polioli sono considerate responsabili dell’insorgenza delle cosiddette complicanze diabetiche, che includono cataratta, neuropatie, nefropatie e retinopatie. Per questo l’AR è da tempo considerata un bersaglio per l’identificazione di inibitori che possano portare allo sviluppo di farmaci contro le complicanze del diabete. Sebbene il glucosio rappresenti uno dei substrati di AR più rilevanti dal punto di vista fisiopatologico, la reazione di riduzione catalizzata dall’enzima mostra ancora alcuni aspetti non completamente chiariti. Tra questi, l’apparente cooperatività negativa che è stata osservata con questo substrato e che è stata ascritta all’esistenza di più forme enzimatiche. Il lavoro sperimentale riportato in questa tesi ha fatto uso sia di AR ricombinante umana. I risultati ottenuti indicano che le strutture emiacetaliche degli aldosi esercitano un effetto modulatorio sulla riduzione della forma aldeidica libera catalizzata dall’AR e che questo effetto è in grado di dare spiegazione dell’apparente negatività cooperativa osservata per l’enzima

Water resource monitoring systems and the role of satellite observations

Spatial water resource monitoring systems (SWRMS) can provide valuable information in support of water management, but current operational systems are few and provide only a subset of the information required. Necessary innovations include the explicit description of water redistribution and water use from river and groundwater systems, achieving greater spatial detail (particularly in key features such as irrigated areas and wetlands), and improving accuracy as assessed against hydrometric observations, as well as assimilating those observations. The Australian water resources assessment (AWRA) system aims to achieve this by coupling landscape models with models describing surface water and groundwater dynamics and water use. A review of operational and research applications demonstrates that satellite observations can improve accuracy and spatial detail in hydrological model estimation. All operational systems use dynamic forcing, land cover classifications and a priori parameterisation of vegetation dynamics that are partially or wholly derived from remote sensing. Satellite observations are used to varying degrees in model evaluation and data assimilation. The utility of satellite observations through data assimilation can vary as a function of dominant hydrological processes. Opportunities for improvement are identified, including the development of more accurate and higher spatial and temporal resolution precipitation products, and the use of a greater range of remote sensing products in a priori model parameter estimation, model evaluation and data assimilation. Operational challenges include the continuity of research satellite missions and data services, and the need to find computationally-efficient data assimilation techniques. The successful use of observations critically depends on the availability of detailed information on observational error and understanding of the relationship between remotely-sensed and model variables, as affected by conceptual discrepancies and spatial and temporal scaling

Travelling as a Risky Business

Travelling is risky business as confirmed by empirical research that differs from country to country. The crime level is determined by the complexity of the economic, social, and cultural factors. In developing countries, property crime is stimulated by poverty. In more prosperous countries, opportunities lead to a higher level of crime rate. There is a need to have detailed sound criminological information in a standardized format

Use of Gravity Recovery and Climate Experiment terrestrial water storage retrievals to evaluate model estimates by the Australian water resources assessment system

Terrestrial water storage (TWS) estimates retrieved from the Gravity Recovery and Climate Experiment (GRACE) satellite mission were compared to TWS modeled by the Australian Water Resources Assessment (AWRA) system. The aim was to test whether differences could be attributed and used to identify model deficiencies. Data for 2003-2010 were decomposed into the seasonal cycle, linear trends and the remaining de-trended anomalies before comparing. AWRA tended to have smaller seasonal amplitude than GRACE. GRACE showed a strong (>15 mm yr -1) drying trend in northwest Australia that was associated with a preceding period of unusually wet conditions, whereas weaker drying trends in the southern Murray Basin and southwest Western Australia were associated with relatively dry conditions. AWRA estimated trends were less negative for these regions, while a more positive trend was estimated for areas affected by cyclone Charlotte in 2009. For 2003-2009, a decrease of 7-8 mm yr -1 (50-60 km 3 yr -1) was estimated from GRACE, enough to explain 6%-7% of the contemporary rate of global sea level rise. This trend was not reproduced by the model. Agreement between model and data suggested that the GRACE retrieval error estimates are biased high. A scaling coefficient applied to GRACE TWS to reduce the effect of signal leakage appeared to degrade quantitative agreement for some regions. Model aspects identified for improvement included a need for better estimation of rainfall in northwest Australia, and more sophisticated treatment of diffuse groundwater discharge processes and surface-groundwater connectivity for some regions

TeV Gamma-rays from accreting magnetars in massive binaries

We consider the neutron star (NS) of the magnetar type inside the massive binary system. We determine the conditions under which the matter from the stellar wind can penetrate the inner magnetosphere of the magnetar. At some distance from the NS surface, the magnetic pressure can balance the gravitational pressure of the accreting matter creating very turbulent, magnetized transition region. It is suggested that this region provides good conditions for acceleration of electrons to relativistic energies. These electrons lose energy on the synchrotron process and the Inverse Compton (IC) scattering of the radiation from the nearby massive stellar companion, producing high energy radiation from the X-rays up to $\sim$TeV $\gamma$-rays. The primary $\gamma$-rays can be farther absorbed in the stellar radiation developing the IC $e^\pm$ pair cascade. We calculate the synchrotron X-ray emission from primary electrons and secondary $e^\pm$ pairs and the IC $\gamma$-ray emission from the cascade process. It is shown that the quasi-simultaneous observations of the TeV $\gamma$-ray binary system LSI +61 303 in the X-ray and the TeV $\gamma$-ray energy ranges can be explained in such an accreting magnetar model.Comment: 5 pages, 1 figure, 1 table, submitted to MNRA

Spray-dried animal plasma in the diet of weanling piglets: influence on growth performance and underlying mechanisms

Gesproeidroogd bloedplasma, spray-dried animal plasma (SDAP), is een bijproduct van slachterijen. Het plasma dat verkregen is van geslachte varkens of runderen wordt gesproeidroogd en kan gebruikt worden voor de productie van zowel humane voedingsmiddelen als diervoeders. In veel experimenten die beschreven staan in de literatuur is aangetoond dat SDAP in voeders voor gespeende biggen aanzienlijke positieve effecten kan hebben op de voeropname en groei na spenen. In een meta analyse, werd uit 68 vergelijkingen tussen SDAP bevattende voeders en controle voeders geconcludeerd dat de door SDAP veroorzaakte groei- en voeropnameverbetering respectievelijk 26.8 % en 24.5 % bedroegen. Twee experimenten uit de literatuur gaven aan dat SDAP in speenvoer speendiarree kan verminderen. Het doel van het onderzoek dat in dit proefschrift staat beschreven was om meer te weten te komen over het werkingsmechanisme van de groei- en gezondheidsbevorderende eigenschappen van SDAP in speenvoeders. Uit dit proefschrift kan geconcludeerd worden dat SDAP positieve effecten heeft op de groei en gezondheid van gespeende biggen. Deze effecten zijn groter bij biggen die gehouden worden onder suboptimale omstandigheden en/of onder hoge infectiedruk en in voeders zonder anti microbiële groeibevorderaars (AMGB). Dit proefschrift geeft aan dat bij het werkingsmechanisme van SDPP effecten op de darmflora zijn betrokken. Het lijkt er echter op dat deze effecten meer een invloed op pathogene bacteriën betreffen dan dat het een algemeen antibacterieel effect betreft dat leidt tot nutriëntbesparing ten gunste van de gastheer, zoals dit beschreven is voor AMGB. Perspectieven voor succesvolle toepassing kunnen vooral verwacht worden op darmniveau bij zoogdieren met een niet optimaal functionerend immuunsysteem, zoals pasgeborenen en in gevallen waarbij antibioticumbehandeling niet mogelijk is zoals bijvoorbeeld bij een verbod op AMGB of bij multiresistente bacterië

Forecasting dryland vegetation condition months in advance through satellite data assimilation

Dryland ecosystems are characterised by rainfall variability and strong vegetation response to changes in water availability over a range of timescales. Forecasting dryland vegetation condition can be of great value in planning agricultural decisions, drought relief, land management and fire preparedness. At monthly to seasonal time scales, knowledge of water stored in the system contributes more to predictability than knowledge of the climate system state. However, realising forecast skill requires knowledge of the vertical distribution of moisture below the surface and the capacity of the vegetation to access this moisture. Here, we demonstrate that contrasting satellite observations of water presence over different vertical domains can be assimilated into an eco-hydrological model and combined with vegetation observations to infer an apparent vegetation-accessible water storage (hereafter called accessible storage). Provided this variable is considered explicitly, skilful forecasts of vegetation condition are achievable several months in advance for most of the world’s drylands.This research was supported through ARC Discovery grant DP140103679. We thank Professor Michael L. Roderick and Professor Jeffery P. Walker for their kind help and suggestions in data analysis. This research was undertaken with the assistance of resources and services from the National Computational Infrastructure (NCI), which is supported by the Australian Government

On the Use of Adaptive Ensemble Kalman Filtering to Mitigate Error Misspecifications in GRACE Data Assimilation

The ensemble Kalman filter (EnKF) has been proved as a useful algorithm to mergecoarse-resolution Gravity Recovery and Climate Experiment (GRACE) data with hydrologic model results.However, in order for the EnKF to perform optimally, a correct forecast error covariance is needed. TheEnKF estimates this error covariance through an ensemble of model simulations with perturbed forcingdata. Consequently, a correct specification of perturbation magnitude is essential for the EnKF to workoptimally. To this end, an adaptive EnKF (AEnKF), a variant of the EnKF with an additional componentthat dynamically detects and corrects error misspecifications during the filtering process, has been applied.Due to the low spatial and temporal resolutions of GRACE data, the efficiency of this method could bedifferent than for other hydrologic applications. Therefore, instead of spatially or temporally averaging theinternal diagnostic (normalized innovations) to detect the misspecifications, spatiotemporal averaging wasused. First, sensitivity of the estimation accuracy to the degree of error in forcing perturbations wasinvestigated. Second, efficiency of the AEnKF for GRACE assimilation was explored using two syntheticand one real data experiment. Results show that there is considerable benefit in using this method toestimate the forcing error magnitude and that the AEnKF can efficiently estimate this magnitude.Ashkan Shokri acknowledges the support from Monash University in the form of a Monash Graduate Scholarship (MGS) and Monash International Postgraduate Research Scholarship (MIPRS). Valentijn Pauwels was supported through an ARC Future Fellowship Grant (FT130100545). The research is supported through an ARC Discovery Grant (DP140103679). This research is also supported in part by the Monash eResearch Centre and eSolutions-Research Support Services through the use of the Monash Campus HPC Cluster

"Rotterdam econometrics": publications of the econometric institute 1956-2005

This paper contains a list of all publications over the period 1956-2005, as reported in the Rotterdam Econometric Institute Reprint series during 1957-2005