There is an immediate need for a high-density genetic map of cotton anchored with fiber genes to facilitate marker-assisted selection (MAS) for improved fiber traits. With this goal in mind, genetic mapping with a new set of microsatellite markers [comprising both simple (SSR) and complex (CSR) sequence repeat markers] was performed on 183 recombinant inbred lines (RILs) developed from the progeny of the interspecific cross Gossypium hirsutum L. cv. TM1 x Gossypium barbadense L. Pima 3-79. Microsatellite markers were developed using 1557 ESTs-containing SSRs (> or = 10 bp) and 5794 EST-containing CSRs (> or = 12 bp) obtained from approximately 14,000 consensus sequences derived from fiber ESTs generated from the cultivated diploid species Gossypium arboreum L. cv AKA8401. From a total of 1232 EST-derived SSR (MUSS) and CSR (MUCS) primer-pairs, 1019 (83%) successfully amplified PCR products from a survey panel of six Gossypium species; 202 (19.8%) were polymorphic between the G. hirsutum L. and G. barbadense L. parents of the interspecific mapping population. Among these polymorphic markers, only 86 (42.6%) showed significant sequence homology to annotated genes with known function. The chromosomal locations of 36 microsatellites were associated with 14 chromosomes and/or 13 chromosome arms of the cotton genome by hypoaneuploid deficiency analysis, enabling us to assign genetic linkage groups (LG) to specific chromosomes. The resulting genetic map consists of 193 loci, including 121 new fiber loci not previously mapped. These fiber loci were mapped to 19 chromosomes and 11 LG spanning 1277 cM, providing approximately 27% genome coverage. Preliminary quantitative trait loci analysis suggested that chromosomes 2, 3, 15, and 18 may harbor genes for traits related to fiber quality. These new PCR-based microsatellite markers derived from cotton fiber ESTs will facilitate the development of a high-resolution integrated genetic map of cotton for structural and functional study of fiber genes and MAS of genes that enhance fiber quality.
The relationships between changes in choroidal vasculature and the severity of diabetic retinopathy (DR) remain unclear. We assessed choroidal changes in diabetic patients by measuring choroidal vascularity index (CVI) in conjunction with DR stage. In this study, patients with diabetes and healthy controls were retrospectively analyzed. Subjects were divided into seven groups as follows: Healthy controls, no DR, mild/moderate non-proliferative DR (NPDR), severe NPDR, proliferative DR (PDR), panretinal photocoagulation-treated DR, and clinically significant macular edema. The mean CVI values in the above groups were 69.08, 67.07, 66.28, 66.20, 63.48, 65.38, and 66.28, respectively. The eyes of diabetic patients exhibited a significantly lower CVI value than those of healthy controls even without DR. The PDR group exhibited a significantly lower CVI value than the healthy control, no DR, and mild/moderate NPDR groups. Age, sex, disease duration, glycated hemoglobin, fasting blood sugar, or intraocular pressure had no correlation with CVI. In multivariate regression analysis, thicker subfoveal choroid and thinner central retina were significantly associated with higher CVI values. These findings carefully suggest that changes in choroidal vasculature could be the primary event in diabetes even where there is no DR.
While there is a growing literature on investigating the Internet clickstream data collected for a single site, such datasets are inherently incomplete because they generally do not capture shopping behavior across multiple websites. A customer's visit patterns at one or more other sites may provide relevant information about the timing and frequency of his or her future visit patterns at the site of interest. We develop a stochastic timing model of cross-site visit behavior to understand how to leverage information from one site to help explain customer behavior at another. To this end, we incorporate two sources of association in browsing patterns: one for the observable outcomes (i.e., arrival times) of two timing processes and the other for the latent visit propensities across a set of competing sites. This proposed multivariate timing mixture model can be viewed as a generalization of the univariate exponential-gamma model. In our empirical analysis, we show that a failure to account for both sources of association not only leads to poor fit and forecasts, but also generates systematically biased parameter estimates. We highlight the model's ability to make accurate statements about the future behavior of the “zero class” (i.e., previous nonvisitors to a given site) using summary information (i.e., recency and frequency) from past visit patterns at a competing site.Internet browsing behavior, data integration, multivariate duration models, customer acquisition
The aim of the study was to evaluate the effect of sex and age on the thickness of the retinal layer in normal eyes using spectral-domain optical coherence tomography (SD-OCT).Fifty healthy subjects between the ages of 20 and 80 had their retinal layers measured using SD-OCT at Seoul St. Mary's Hospital. Mean thickness and volume were measured for 9 retinal layers in the fovea, the pericentral ring, and the peripheral ring. The differences of sex- and age-related thickness and volume in each retinal layer were analyzed.The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), and outer plexiform layer (OPL) were thinnest in the fovea area, whereas the outer nuclear layer (ONL), photoreceptor layer (PHL), and retinal pigment epithelium (RPE) were thickest at similar locations. Mean thickness of the RNFL, GCL, IPL, and OPL was significantly greater in men than women. However, mean thickness of the ONL was greater in women than in men. When compared between patients < 30 years and > 60 years of age, the thickness and volume of peripheral RNFL, GCL, and pericentral and peripheral IPL were significantly larger in the younger group than the older group. Conversely, the thickness and volume of foveal INL and IR were larger in the older group than in the younger group.The thickness and volume of the retinal layer in normal eyes significantly vary depending on age and sex. These results should be considered when evaluating layer analysis in retinal disease.
The authors develop a general parametric modeling framework for bidding behavior in Internet auctions. Toward this end, they incorporate four key components of the bidding process under their framework: whether people bid on an auction, (if so) who bids, when they bid, and how much they bid over the entire sequence of bids in an auction. This integrated framework is based on a single, latent, time-varying construct of consumer willingness to bid, which bidders have and update for a particular auction item over the course of the auction duration. Using a database of notebook auctions from one of the largest Internet auction sites in Korea, the authors demonstrate that this general (yet parsimonious) model captures the key behavioral aspects of bidding behavior. Furthermore, the authors provide a valuable tool for managers at auction sites to conduct their customer relationship management efforts, which require them to evaluate the ”goodness” of the listed auction items (whether people bid) and the goodness of the potential bidders (who bids, when they bid, and how much they bid).
Ocular toxoplasmosis is a disease caused by the infection with Toxoplasma gondii through congenital or acquired routes. Once the parasite reaches the retina, it proliferates within host cells followed by rupture of the host cells and invasion into neighboring cells to make primary lesions. Sometimes the restricted parasite by the host immunity in the first scar is activated to infect another lesion nearby the scar. Blurred vision is the main complaint of ocular toxoplasmic patients and can be diagnosed by detection of antibodies or parasite DNA. Ocular toxoplasmosis needs therapy with several combinations of drugs to eliminate the parasite and accompanying inflammation; if not treated it sometimes leads to loss of vision. We describe here clinical features and currently available chemotherapy of ocular toxoplasmosis.
A novel strain was isolated, Pseudomonas stutzeri CJ38, that enabled direct transformation of maltose to trehalose. In comparison with others reported to date, CJ38 provided a novel trehalose synthase (TSase) without any byproduct, including glucose. Activity analysis, using either maltose or trehalose as a substrate, showed a reversible reaction. There was also no detectable activity of related enzymes with liquid starch and maltooligosaccharides as substrates. Using a malPQ-negative host and MacConkey medium, the TSase gene was cloned in Escherichia coli from CJ38. The resulting sequence contained an open reading frame consisted of 689 amino acids with a calculated molecular mass of 76 kDa. A search for related sequences in various gene and protein data banks revealed a novel family of enzymes that was predicted putatively as a glycosidase or TSase family, with no biochemical evidence. The recombinant enzyme exhibited a high activity toward the substrate maltose, about 50-fold higher than the parent strain and resulted in a high conversion yield (72%) at a relatively high substrate concentration (20%). These results provided the possibility that the strain was effectively used as a potential biocatalyst for the production of trehalose from maltose in a one-step reaction.
The authors model how to measure consumer willingness to pay (WTP) from an English or ascending first-price auction based on two general bidding premises: no bidder bids more than her WTP, and no bidder allows a rival bidder to win at a price that she is willing to beat (Haile and Tamer 2003). In other words, a "no regret" rule in bidding is proposed. Other than that, no other restrictive assumptions on maximands or behavior of bidders in a competitive auction context are imposed. WTP is modeled as having two components: a pure product feature component and one based on the auction market environment. The latter includes bidder experience, seller reputation, and measures for competition among bidders and among items. The proposed model is general enough to include "buy it now" (BIN) (equivalent to a posted price) auction mechanism.The authors use data of notebook auctions from one of the largest Internet auction sites in Korea. They find that most product characteristics matter in the expected ways. Other primary findings are as follows: (1) WTP declines as more similar items are concurrently listed with the focal item; there is an additional effect if these similar items also belong to the same brand. Therefore, market thickness matters for consumer WTP. (2) More extensive site-surfing and bidding histories lead to lower WTP, implying that search costs and experience matter in bidding. As specific substantive benefits, the authors demonstrate how sellers can calculate changes in WTP, and hence the expected revenue, as the number of concurrently available similar items varies.Key words: internet auctions, bidder willingness-to-pay, bidder competition, item competition, econometric models.Auctions on the Internet are a booming enterprise. From a managerial perspective, two recent trends are worth noting. First, the Internet auction market appears to have matured enough that managers are beginning to ask whether auction data can be used to estimate consumer valuations for various products. As a recent report indicated, "For years, eBay Inc. has let its users buy and sell almost anything. Now it wants to become the blue book for just about everything … Recently, eBay stepped up the program with two deals that show how the San Jose, Calif., company's data could end up as the basis for guides used to determine fair market prices for items that may never be purchased or sold on the site itself … eBay is making the push at a time with its site has grown monstrously large, with enough auctions of items across various categories that the company says it can provide representative market prices" (Wall Street Journal, December 8, 2003). Second, there is a growing interest in understanding the impact of competition among auction items on bidder behavior. These two managerial concerns form the core research questions of our paper.In measuring consumer valuations from auction data, there are three major issues to be resolved: (1) How to separate out the impact of auction market environment from pure productbased con...
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