645 research outputs found
Advertiser Learning in Direct Advertising Markets
Direct buy advertisers procure advertising inventory at fixed rates from
publishers and ad networks. Such advertisers face the complex task of choosing
ads amongst myriad new publisher sites. We offer evidence that advertisers do
not excel at making these choices. Instead, they try many sites before settling
on a favored set, consistent with advertiser learning. We subsequently model
advertiser demand for publisher inventory wherein advertisers learn about
advertising efficacy across publishers' sites. Results suggest that advertisers
spend considerable resources advertising on sites they eventually abandon -- in
part because their prior beliefs about advertising efficacy on those sites are
too optimistic. The median advertiser's expected CTR at a new site is 0.23%,
five times higher than the true median CTR of 0.045%.
We consider how pooling advertiser information remediates this problem.
Specifically, we show that ads with similar visual elements garner similar
CTRs, enabling advertisers to better predict ad performance at new sites.
Counterfactual analyses indicate that gains from pooling advertiser information
are substantial: over six months, we estimate a median advertiser welfare gain
of \$2,756 (a 15.5% increase) and a median publisher revenue gain of \$9,618 (a
63.9% increase)
DOES BETA-ALANINE SUPPLEMENTATION POTENTIATE MUSCLE PERFORMANCE FOLLOWING 6 WEEKS OF BLOOD FLOW RESTRICTION OR TRADITIONAL RESISTANCE TRAINING?
International Journal of Exercise Science 16(2): 999-1011, 2023. We aimed to compare the effects of beta-alanine on Traditional Resistance Training (TRAD) or Blood Flow Restriction Training (BFR). Methods: 19 subjects were randomly allocated to a Placebo (n = 10) or beta-alanine (n = 9) group. Subjects from both groups were trained unilaterally (unilateral arm curl) for six weeks, and each arm was trained using a different paradigm (BFR or TRAD). One repetition maximum (1RM) test measurements were performed before and after the strength training program. Work output was accessed as the total weight lifted (repetitions × weight lifted × sets) for the entire strength training program. Results: 1RM or total weight lifted was not increased by beta-alanine supplementation. However, the TRAD-trained arm showed a significantly increased 1RM and total weight lifted compared to the BFR arm (p \u3c 0.05). Conclusion: We conclude that in the short-term (6 weeks) and following the current experimental conditions, beta-alanine does not benefit BFR or TRAD in terms of total weight lifted (volume of training) or maximal strength (1RM)
Future market segments for hybrid maize in East Africa
The current seed product market segmentation by the Consultative Group on International Agricultural Research (CGIAR) for maize in East Africa includes four segments, which differ by agro-ecological zone and maturity class. However, considering the lengthy period required to produce a variety, from initial design to commercial production, a critical question should be asked: what are future segments that should be considered in discussions on current breeding investments? Video-based product concept testing (VPCT) is a novel approach for gathering insights from farmers about their varietal preferences to inform future market segmentation. This brief explains the conceptual and methodological underpinnings of VPCT. We present an application of the tool in hybrid maize. Seven new product concepts (representing potential future market segments) were identified based on discussions with breeders, seed companies and farmers, which we labelled: home use, intercropping, drought avoidance, nutritious, feed (yellow), green maize and food and fodder. These future concepts, together with the resilient benchmark product concept (the current breeding target), were evaluated through triadic comparisons with 2400 farmers in Kenya and Uganda. In Uganda, the drought avoidance concept ranked high, while in Kenya the intercropping concept stood out. Concept testing provides a strong case for new investments to integrate agronomic practices and preferences of farmers into breeding, on-farm testing and seed systems. Future work will estimate the implications of increased availability (and uptake) of these future segments on the current segmentation
CYP450 phenotyping and metabolite identification of quinine by accurate mass UPLC-MS analysis: a possible metabolic link to blackwater fever
BACKGROUND: The naturally occurring alkaloid drug, quinine is commonly used for the treatment of severe malaria. Despite centuries of use, its metabolism is still not fully understood, and may play a role in the haemolytic disorders associated with the drug. METHODS: Incubations of quinine with CYPs 1A2, 2C9, 2C19, 2D6, and 3A4 were conducted, and the metabolites were characterized by accurate mass UPLC-MS(E) analysis. Reactive oxygen species generation was also measured in human erythrocytes incubated in the presence of quinine with and without microsomes. RESULTS: The metabolites 3-hydroxyquinine, 2’-oxoquininone, and O-desmethylquinine were observed after incubation with CYPs 3A4 (3-hydroxyquinine and 2’-oxoquininone) and 2D6 (O-desmethylquinine). In addition, multiple hydroxylations were observed both on the quinoline core and the quinuclidine ring system. Of the five primary abundance CYPs tested, 3A4, 2D6, 2C9, and 2C19 all demonstrated activity toward quinine, while 1A2 did not. Further, quinine produced robust dose-dependent oxidative stress in human erythrocytes in the presence of microsomes. CONCLUSIONS: Taken in context, these data suggest a CYP-mediated link between quinine metabolism and the poorly understood haemolytic condition known as blackwater fever, often associated with quinine ingestion
Paracrine signalling events in embryonic stem cell renewal mediated by affinity targeted nanoparticles
AbstractStem cell growth and differentiation is controlled by intrinsic and extrinsic factors. The latter includes growth factors, which are conventionally supplied in vitro in media exchanged daily. Here, we illustrate the use of affinity targeted biodegradable nanoparticles to mediate paracrine stimulation as an alternative approach to sustain the growth and pluripotency of mouse embryonic stem cells. Leukaemia Inhibitory Factor (LIF) was encapsulated in biodegradable nanoparticles and targeted to the cell surface using an antibody to the oligosaccharide antigen SSEA-1. Sustained release of LIF from nanoparticles composed of a solid Poly(lactide-co-glycolic acid) polyester or a hydrogel-based liposomal system, we term Nanolipogel, replenished once after each cell passage, proved as effective as daily replenishment with soluble LIF for maintenance of pluripotency after 5 passages using 104-fold less LIF. Our study constitutes an alternative paradigm for stem cell culture, providing dynamic microenvironmental control of extrinsic bioactive factors benefiting stem cell manufacturing
Innovative sea surface monitoring with GNSS-REflectometry aboard ISS: overview and recent results from GEROS-ISS
GEROS-ISS (GEROS hereafter) stands for GNSS REflectometry, Radio Occultation and Scatterometry onboard the International Space Station. It is a scientific experiment, proposed to the European Space Agency (ESA) in 2011 for installation aboard the ISS. The main focus of GEROS is the dedicated use of signals from the currently available Global Navigation Satellite Systems (GNSS) for remote sensing of the System Earth with focus to Climate Change characterisation. The GEROS mission idea and the current status are briefly reviewed.Peer ReviewedPostprint (author's final draft
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
Fístula buco-nasal decorrente de exodontia: relato de caso/ Oronasal fistula due tooth extraction: case report
A fístula buco-nasal é uma comunicação patológica de trajeto epitelizado entre as cavidades bucal e nasal, gerando alterações fonéticas e passagem de alimentos sólidos e líquidos para o interior da cavidade nasal, advindo inflamação, que poderá se propagar para a faringe, trompa de Eustáquio e até́ ao ouvido médio. Ela ocorre frequentemente em pacientes portadores de fissura palatina, e sua associação com exodontia é incomum.
Hot, rocky and warm, puffy super-Earths orbiting TOI-402 (HD 15337)
Context: The Transiting Exoplanet Survey Satellite (TESS) is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V = 9.1 K1 dwarf also known as HD 15337, and found two transiting signals with periods of 4.76 and 17.18 days and radii of 1.90 and 2.21 R⊕, respectively. This star was observed prior to the TESS detection as part of the radial-velocity (RV) search for planets using the HARPS spectrometer, and 85 precise RV measurements were obtained before the launch of TESS over a period of 14 yr.
Aims: In this paper, we analyse the HARPS RV measurements in hand to confirm the planetary nature of these two signals.
Methods: HD 15337 happens to present a stellar activity level similar to the Sun, with a magnetic cycle of similar amplitude and RV measurements that are affected by stellar activity. By modelling this stellar activity in the HARPS radial velocities using a linear dependence with the calcium activity index log(RHK′), we are able, with a periodogram approach, to confirm the periods and the planetary nature of TOI-402.01 and TOI-402.02. We then derive robust estimates from the HARPS RVs for the orbital parameters of these two planets by modelling stellar activity with a Gaussian process and using the marginalised posterior probability density functions obtained from our analysis of TESS photometry for the orbital period and time of transit.
Results: By modelling TESS photometry and the stellar host characteristics, we find that TOI-402.01 and TOI-402.02 have periods of 4.75642 ± 0.00021 and 17.1784 ± 0.0016 days and radii of 1.70 ± 0.06 and 2.52 ± 0.11 R⊕ (precision 3.6 and 4.2%), respectively. By analysing the HARPS RV measurements, we find that those planets are both super-Earths with masses of 7.20 ± 0.81 and 8.79 ± 1.68 M⊕ (precision 11.3 and 19.1%), and small eccentricities compatible with zero at 2σ.
Conclusions: Although having rather similar masses, the radii of these two planets are very different, putting them on different sides of the radius gap. By studying the temporal evolution under X-ray and UV (XUV) driven atmospheric escape of the TOI-402 planetary system, we confirm, under the given assumptions, that photo-evaporation is a plausible explanation for this radius difference. Those two planets, being in the same system and therefore being in the same irradiation environment are therefore extremely useful for comparative exoplanetology across the evaporation valley and thus bring constraints on the mechanisms responsible for the radius gap
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