Competitive Targeted Marketing

In this paper, we consider two firms diffusing incompatible technologies and their decision of consumer targeting. The technology adoption is made in two steps. First, once the firms sell their products to their respective targeted consumer, the technology is diffused successively by word-of-mouth communication from the initial consumer to other consumers linked along the network. Then, in the second step, each consumer imitates the technology the neighbors use which fares better, and through this process of imitation, the technology distribution keeps evolving until it reaches the long-run steady state. We demonstrate that the early entrant chooses the minmax location when firms are myopic in the sense that they do not take the imitation possibility into account. If firms consider the possibility of imitation, the best target will tend towards a hub, although the minmax principle in general keeps valid in the sense that it should be the minmax location after considering imitation

Plutonium in Soils from Northeast China and Its Potential Application for Evaluation of Soil Erosion

Surface and soil core samples from northeast China were analyzed for Pu isotopes. The measured Pu-240/Pu-239 atomic ratios and Pu239 + 240/Cs-137 activity ratios revealed that the global fallout is the dominant source of Pu and Cs-137 at these sites. Migration behavior of Pu varying with land type and human activities resulted in different distribution of Pu in surface soils. A sub-surface maximum followed by exponential decline of Pu239 + 240 concentrations was observed in an undisturbed soil core, with a total Pu239 + 240 inventory of 86.9 Bq/m(2) and more than 85% accumulated in 0 similar to 20 cm layers. While only half inventory of Pu was obtained in another soil core and no sub-surface maximum value occurred. Erosion of topsoil in the site should be the most possible reason for the significantly lower Pu inventory, which is also supported by the reported Cs-137 profiles. These results demonstrated that Pu could be applied as an ideal substitute of Cs-137 for soil erosion study in the future.</p

Performance of Papanicolaou Testing and Detection of Cervical Carcinoma In Situ in Participants of Organized Cervical Cancer Screening in South Korea

BACKGROUND: The present study measured the performance of the Papanicolaou (Pap) test and detection of cervical carcinoma in situ (CIS) and cancer in participants of organized cervical cancer screening in South Korea, and examined differences in the proportion of CIS according to socio-demographic factors. METHODS: Data were obtained from the National Cancer Screening Program and National Health Insurance Cancer Screening Program databases. We analyzed data from 4,072,997 screenings of women aged 30 years or older who underwent cervical cancer screening by Pap test between January 1, 2005 and December 31, 2006. We calculated the performances of the Pap test and compared that according to socio-demographic factors. RESULTS: The positivity rate for all screenings was 6.6%. The cancer detection rate (CDR) and interval cancer rate (ICR) were 0.32 per 1,000 screenings, and 0.13 per 1,000 negative screenings, respectively. About 63.4% of screen-detected CIS+ cases (CIS or invasive cervical cancer) were CIS. The CDR and ICR, and percentage of CIS among all CIS+ were significantly different by age group and health insurance status. The odds ratios of CDR and ICR were higher for Medical Aid Program (MAP) recipients compared with National Health Insurance (NHI) beneficiaries. The likelihood of a detected CIS+ case to be CIS was significantly lower among MAP recipients than among NHI beneficiaries. CONCLUSIONS: The difference in performance of cervical cancer screening among different socio-demographic groups may indicate an important influence of socio-demographic factors on preventive behavior. The findings of the study support the critical need for increasing efforts to raise awareness and provide more screening in at-risk populations, specifically low-income groups

Malaria parasites regulate the duration of the intra-erythrocytic cycle via serpentine receptor 10 and coordinate development with host daily rhythms

Malaria parasites complete their intra-erythrocytic developmental cycle (IDC) in multiples of 24 h suggesting a circadian basis, but the mechanism controlling this periodicity is unknown. Combining in vivo and in vitro approaches utilizing rodent and human malaria parasites, we reveal that: (i) 57% of Plasmodium chabaudi genes exhibit daily rhythms in transcription; (ii) 58% of these genes lose transcriptional rhythmicity when the IDC is out-of-synchrony with host rhythms; (iii) 6% of Plasmodium falciparum genes show 24 h rhythms in expression under free-running conditions; (iv) Serpentine receptor 10 (SR10) has a 24 h transcriptional rhythm and disrupting it in rodent malaria parasites shortens the IDC by 2-3 h; (v) Multiple processes including DNA replication, and the ubiquitin and proteasome pathways, are affected by loss of coordination with host rhythms and by disruption of SR10. Our results reveal malaria parasites are at least partly responsible for scheduling the IDC and coordinating their development with host daily rhythms

(Q)SAR Modelling of Nanomaterial Toxicity - A Critical Review

There is an increasing recognition that nanomaterials pose a risk to human health, and that the novel engineered nanomaterials (ENMs) in the nanotechnology industry and their increasing industrial usage poses the most immediate problem for hazard assessment, as many of them remain untested. The large number of materials and their variants (different sizes and coatings for instance) that require testing and ethical pressure towards non-animal testing means that expensive animal bioassay is precluded, and the use of (quantitative) structure activity relationships ((Q)SAR) models as an alternative source of hazard information should be explored. (Q)SAR modelling can be applied to fill the critical knowledge gaps by making the best use of existing data, prioritize physicochemical parameters driving toxicity, and provide practical solutions to the risk assessment problems caused by the diversity of ENMs. This paper covers the core components required for successful application of (Q)SAR technologies to ENMs toxicity prediction, and summarizes the published nano-(Q)SAR studies and outlines the challenges ahead for nano-(Q)SAR modelling. It provides a critical review of (1) the present status of the availability of ENMs characterization/toxicity data, (2) the characterization of nanostructures that meets the need of (Q)SAR analysis, (3) the summary of published nano-(Q)SAR studies and their limitations, (4) the in silico tools for (Q)SAR screening of nanotoxicity and (5) the prospective directions for the development of nano-(Q)SAR models

Dynamic relocalization of NHERF1 mediates chemotactic migration of ovarian cancer cells toward lysophosphatidic acid stimulation

NHERF1/EBP50 (Na+/H+ exchanger regulating factor 1; Ezrin-binding phosphoprotein of 50 kDa) organizes stable protein complexes beneath the apical membrane of polar epithelial cells. By contrast, in cancer cells without any fixed polarity, NHERF1 often localizes in the cytoplasm. The regulation of cytoplasmic NHERF1 and its role in cancer progression remain unclear. In this study, we found that, upon lysophosphatidic acid (LPA) stimulation, cytoplasmic NHERF1 rapidly translocated to the plasma membrane, and subsequently to cortical protrusion structures, of ovarian cancer cells. This movement depended on direct binding of NHERF1 to C-terminally phosphorylated ERM proteins (cpERMs). Moreover, NHERF1 depletion downregulated cpERMs and further impaired cpERM-dependent remodeling of the cell cortex, suggesting reciprocal regulation between these proteins. The LPA-induced protein complex was highly enriched in migratory pseudopodia, whose formation was impaired by overexpression of NHERF1 truncation mutants. Consistent with this, NHERF1 depletion in various types of cancer cells abolished chemotactic cell migration toward a LPA gradient. Taken together, our findings suggest that the high dynamics of cytosolic NHERF1 provide cancer cells with a means of controlling chemotactic migration. This capacity is likely to be essential for ovarian cancer progression in tumor microenvironments containing LPA