On the Accuracy of Nielsen Homescan Data

Researchers use Nielsen Homescan data, which provide detailed food-purchase information from a panel of U.S. households, to address a variety of important research topics. However, some question the credibility of the data since the data are self-recorded and the recording process is time-consuming. Matching purchase records from 2004 Homescan data with data obtained from a large grocery retailer, it is evident that quantities purchased are reported more accurately in Homescan than are prices. Many of the price differences may be driven by the way Nielsen imputes prices: when available, Nielsen uses store-level prices instead of the actual price paid by the household. There are also differences by household type in the tendency to make mistakes that are correlated with demographic variables. However, the fraction of variance explained by the documented recording errors is in line with other research data sets for which cross-validation studies have been conducted.Nielsen, Homescan, scanner data, validation study, Agricultural and Food Policy, Consumer/Household Economics, Demand and Price Analysis, Institutional and Behavioral Economics,

Some Basic Properties of Low Quality Two-Phase Turbulent Flow

This Is an exploratory study dealing with the effect of gas bubbles on the turbulence Intensity of the liquid in a two-phase flow. Distributions of time-mean and fluctuating velocities were measured in a two - dimensional channel. These were measured for single-phase flow and on the two sides of a bubble layer, which simulated the two-phase flow. In single-phase flow the distribution of the time-mean velocities agrees well with other data, while the distribution of the Intensity of turbulence Is lower than expected. The measurements of the time-mean velocity and turbulence Intensity across the bubble layer revealed that they are discontinuous at that point. This supports the hypothesis that the presence of bubbles in liquid flows tends to lower the intensity of turbulence

Internal relaxation time in immersed particulate materials

We study the dynamics of the solid to liquid transition for a model material made of elastic particles immersed in a viscous fluid. The interaction between particle surfaces includes their viscous lubrication, a sharp repulsion when they get closer than a tuned steric length and their elastic deflection induced by those two forces. We use Soft Dynamics to simulate the dynamics of this material when it experiences a step increase in the shear stress and a constant normal stress. We observe a long creep phase before a substantial flow eventually establishes. We find that the typical creep time relies on an internal relaxation process, namely the separation of two particles driven by the applied stress and resisted by the viscous friction. This mechanism should be relevant for granular pastes, living cells, emulsions and wet foams

Effect of high-flow nasal therapy on dyspnea, comfort, and respiratory rate

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Procalcitonin levels in candidemia versus bacteremia: A systematic review

open7BackgroundProcalcitonin (PCT) is a biomarker used to assess systemic inflammation, infection, and sepsis and to optimize antimicrobial therapies. Its role in thein the differential diagnosis between candidemia and bacteremia is unclear. The aim of this systematic review was to summarize the current evidence about PCT values for differentiating candidemia from bacteremia.MethodsPubMed and EMBASE were searched for studies reporting data on the diagnostic performance of serum PCT levels in intensive care unit (ICU) or non-ICU adult patients with candidemia, in comparison to patients with bacteremia.ResultsWe included 16 studies for a total of 45.079 patients and 785 cases of candidemia. Most studies claimed to report data relating to the use of PCT values for differentiating between candidemia and bacteremia in septic patients in the intensive care unit. However, the studies identified were all retrospective, except for one secondary analysis of a prospective dataset, and clinically very heterogeneous and involved different assessment methods. Most studies did show lower PCT values in patients with candidemia compared to bacteremia. However, the evidence supporting this observation is of low quality and the difference seems insufficiently discriminative to guide therapeutic decisions. None of the studies retrieved actually studied guidance of antifungal treatment by PCT. PCT may improve diagnostic performance regarding candidemia when combined with other biomarkers of infection (e.g., beta-d-glucan) but more data is needed.ConclusionsPCT should not be used as a standalone tool for the differential diagnosis between candidemia and bacteremia due to limited supporting evidence.openCortegiani A.; Misseri G.; Ippolito M.; Bassetti M.; Giarratano A.; Martin-Loeches I.; Einav S.Cortegiani, A.; Misseri, G.; Ippolito, M.; Bassetti, M.; Giarratano, A.; Martin-Loeches, I.; Einav, S

Procalcitonin levels in candidemia versus bacteremia: A systematic review

Background: Procalcitonin (PCT) is a biomarker used to assess systemic inflammation, infection, and sepsis and to optimize antimicrobial therapies. Its role in the in the differential diagnosis between candidemia and bacteremia is unclear. The aim of this systematic review was to summarize the current evidence about PCT values for differentiating candidemia from bacteremia. Methods: PubMed and EMBASE were searched for studies reporting data on the diagnostic performance of serum PCT levels in intensive care unit (ICU) or non-ICU adult patients with candidemia, in comparison to patients with bacteremia. Results: We included 16 studies for a total of 45.079 patients and 785 cases of candidemia. Most studies claimed to report data relating to the use of PCT values for differentiating between candidemia and bacteremia in septic patients in the intensive care unit. However, the studies identified were all retrospective, except for one secondary analysis of a prospective dataset, and clinically very heterogeneous and involved different assessment methods. Most studies did show lower PCT values in patients with candidemia compared to bacteremia. However, the evidence supporting this observation is of low quality and the difference seems insufficiently discriminative to guide therapeutic decisions. None of the studies retrieved actually studied guidance of antifungal treatment by PCT. PCT may improve diagnostic performance regarding candidemia when combined with other biomarkers of infection (e.g., beta-D-glucan) but more data is needed. Conclusions: PCT should not be used as a standalone tool for the differential diagnosis between candidemia and bacteremia due to limited supporting evidence

Constitutive Nucleosome Depletion and Ordered Factor Assembly at the GRP78 Promoter Revealed by Single Molecule Footprinting

Chromatin organization and transcriptional regulation are interrelated processes. A shortcoming of current experimental approaches to these complex events is the lack of methods that can capture the activation process on single promoters. We have recently described a method that combines methyltransferase M.SssI treatment of intact nuclei and bisulfite sequencing allowing the representation of replicas of single promoters in terms of protected and unprotected footprint modules. Here we combine this method with computational analysis to study single molecule dynamics of transcriptional activation in the stress inducible GRP78 promoter. We show that a 350–base pair region upstream of the transcription initiation site is constitutively depleted of nucleosomes, regardless of the induction state of the promoter, providing one of the first examples for such a promoter in mammals. The 350–base pair nucleosome-free region can be dissected into modules, identifying transcription factor binding sites and their combinatorial organization during endoplasmic reticulum stress. The interaction of the transcriptional machinery with the GRP78 core promoter is highly organized, represented by six major combinatorial states. We show that the TATA box is frequently occupied in the noninduced state, that stress induction results in sequential loading of the endoplasmic reticulum stress response elements, and that a substantial portion of these elements is no longer occupied following recruitment of factors to the transcription initiation site. Studying the positioning of nucleosomes and transcription factors at the single promoter level provides a powerful tool to gain novel insights into the transcriptional process in eukaryotes