Stochastic Modelling and Optimisation of Internet Auction Processes

AbstractInternet auctions are an attractive mechanism for the exchange of goods at a non-fixed price point. The operation of these auctions can be run under a variety of parameters. In this paper, we provide a theoretical analysis of fixed time forward auctions in cases where a single bid or multiple bids are accepted in a single auction. A comparison of the economic benefits and the corresponding buyer and seller surpluses between the auctions where a single bid is accepted and the auctions where multiple bids are accepted is made. These models are verified through systematic simulation experiments, based on a series of operational assumptions, which characterise the arrival rate of bids, as well as the distribution from which the private values of buyers are sampled. Decision rules for optimising surplus under different auction fee structures are also given

Circulating human leucine-rich a-2-glycoprotein 1 mRNA and protein levels to detect acute appendicitis in patients with acute abdominal pain

Background Elevated levels of circulating plasma and urine leucine-rich-2-glycoprotein-1 (LRG1) protein has been found in patients with acute appendicitis (AA) and may be useful for diagnosis. This study aimed to investigate whether combined tests including circulating LRG1 mRNA levels improve the early diagnosis of AA. Methods Between December 2011 and October 2012, a prospective study was conducted on patients aged 18 years or older presenting to the ED with acute abdominal pain (< 7 days of symptom onset). Levels of whole blood LRG1 mRNA and plasma LRG1 protein taken from these patients within 24 h of arrival (mean 12.4 h) were analyzed. The primary outcome was AA. Results Eighty-four patients (40 (47.6%) with AA and 44 (52.4%) without AA; mean age 35 years; 41.6% males) were recruited. Median whole blood LRG1 mRNA and plasma LRG1 levels were higher in AA patients than in non-AA. Of 40 AA patients, 13 (32.5%) were diagnosed as complicated AA. In ROC analysis of LRG1 mRNA (normalized to GAPDH), LRG1 protein and Alvarado score for discriminating AA and non-AA, the areas under the curve (AUC) were 0.723, 0.742 and 0.805 respectively. The AUC of combination of normalized LRG1 mRNA, LRG1 protein and Alvarado score was 0.845. Conclusion A combination of modified whole blood LRG1 mRNA levels, plasma LRG1 protein and Alvarado score at the ED may be useful to diagnose simple and complicated AA from other causes of abdominal pain

Dusty starbursts masquerading as ultra-high redshift galaxies in JWST CEERS observations

Lyman Break Galaxy (LBG) candidates at z ≳ 10 are rapidly being identified in JWST/NIRCam observations. Due to the (redshifted) break produced by neutral hydrogen absorption of rest-frame UV photons, these sources are expected to drop out in the bluer filters while being well-detected in redder filters. However, here we show that dust-enshrouded star-forming galaxies at lower redshifts (z ≲ 7) may also mimic the near-infrared colors of z > 10 LBGs, representing potential contaminants in LBG candidate samples. First, we analyze CEERS-DSFG-1, a NIRCam dropout undetected in the F115W and F150W filters but detected at longer wavelengths. Combining the JWST data with (sub)millimeter constraints, including deep NOEMA interferometric observations, we show that this source is a dusty star-forming galaxy (DSFG) at z ≈ 5.1. We also present a tentative 2.6σ SCUBA-2 detection at 850 µm around a recently identified z ≈ 16 LBG candidate in the same field and show that, if the emission is real and associated with this candidate, the available photometry is consistent with a z ∼ 5 dusty galaxy with strong nebular emission lines despite its blue near-IR colors. Further observations on this candidate are imperative to mitigate the low confidence of this tentative emission and its positional uncertainty. Our analysis shows that robust (sub)millimeter detections of NIRCam dropout galaxies likely imply z ∼ 4 − 6 redshift solutions, where the observed near-IR break would be the result of a strong rest-frame optical Balmer break combined with high dust attenuation and 2 The CEERS collaboration strong nebular line emission, rather than the rest-frame UV Lyman break. This provides evidence that DSFGs may contaminate searches for ultra high-redshift LBG candidates from JWST observations