Socially Optimal Mining Pools

Mining for Bitcoins is a high-risk high-reward activity. Miners, seeking to reduce their variance and earn steadier rewards, collaborate in pooling strategies where they jointly mine for Bitcoins. Whenever some pool participant is successful, the earned rewards are appropriately split among all pool participants. Currently a dozen of different pooling strategies (i.e., methods for distributing the rewards) are in use for Bitcoin mining. We here propose a formal model of utility and social welfare for Bitcoin mining (and analogous mining systems) based on the theory of discounted expected utility, and next study pooling strategies that maximize the social welfare of miners. Our main result shows that one of the pooling strategies actually employed in practice--the so-called geometric pay pool--achieves the optimal steady-state utility for miners when its parameters are set appropriately. Our results apply not only to Bitcoin mining pools, but any other form of pooled mining or crowdsourcing computations where the participants engage in repeated random trials towards a common goal, and where "partial" solutions can be efficiently verified

A comparative analysis of toluidine blue with frozen section in oral squamous cell carcinoma

Background:Surgical excision of the primary tumor with safe margins remains the mainstay of treatment for oral cavity squamous cell carcinoma (OSCC). The standard of care for assessment of intraoperative margins is frozen section histopathology. Unfortunately the facility is not available at most centers in limited resource countries. Toluidine blue, a metachromatic dye, has been well described in clinical identification of malignant and premalignant lesion in the oral cavity. Considering this we decided to explore intraoperative use of toluidine blue staining, in comparison with frozen sections, for the assessment of tumor-free margins. Methods: After obtaining clearance from the in-house ethical review committee, a prospective study was conducted at Aga Khan University Hospital, Karachi, from August 15, 2009 to March 14, 2010. A sample of 56 consenting Patients with biopsy-proven OSCC were included in the study, giving us 280 tumor margins. Margins were analyzed using toluidine blue staining and frozen section histopathology. A receiver operator curve (ROC) was then applied to compare assessment of margin status by toluidine blue and frozen section. Results: Of the 280 examined margins 11 stained positive with toluidine blue, three were positive on frozen section biopsy, and three were positive on final histopathology. Toluidine blue staining had sensitivity and specificity of 100% and 97%, respectively. The diagnostic accuracy of toluidine blue was found to be 97.1% with a positive predictive value (PPV) of 27.2% and a negative predictive value (NPV) of 100%. Conclusions: Toluidine blue can be used as an effective screening modality for the assessment of intraoperative margins in resource limited environments and reducing the number of frozen section biopsies performed. Further by providing real-time clinical information within minutes it can reduce indirect costs such as operating room time. It may also be used as an ad hoc for frozen section biopsies where frozen section facilities are available

Priority for the Worse Off and the Social Cost of Carbon

The social cost of carbon (SCC) is a monetary measure of the harms from carbon emission. Specifically, it is the reduction in current consumption that produces a loss in social welfare equivalent to that caused by the emission of a ton of CO2. The standard approach is to calculate the SCC using a discounted-utilitarian social welfare function (SWF)—one that simply adds up the well-being numbers (utilities) of individuals, as discounted by a weighting factor that decreases with time. The discounted-utilitarian SWF has been criticized both for ignoring the distribution of well-being, and for including an arbitrary preference for earlier generations. Here, we use a prioritarian SWF, with no time-discount factor, to calculate the SCC in the integrated assessment model RICE. Prioritarianism is a well-developed concept in ethics and theoretical welfare economics, but has been, thus far, little used in climate scholarship. The core idea is to give greater weight to well-being changes affecting worse off individuals. We find substantial differences between the discounted-utilitarian and non-discounted prioritarian SCC

Statement complementing the EFSA Scientific Opinion on application (EFSA‐GMO‐NL‐2009‐75) for placing on the market of genetically modified oilseed rape Ms8 × Rf3 × GT73 and subcombinations, which have not been authorised previously (i.e. Ms8 × GT73 and Rf3 × GT73) independently of their origin, for food and feed uses, import and processing, with the exception of isolated seed protein for food, under Regulation (EC) No 1829/2003), taking into consideration additional information

The EFSA Panel on Genetically Modified Organisms (GMO) previously assessed oilseed rape Ms8 × Rf3 × GT73 and its subcombinations Ms8 × GT73 and Rf3 × GT73 according to the scope as defined in the application EFSA‐GMO‐NL‐2009‐75, and was not in the position to complete the safety assessment of products rich in protein, such as rapeseed protein isolates or products of this nature in animal feeding. Following a mandate from the European Commission, the GMO Panel assessed a 28‐day toxicity study in mice with the glyphosate oxidoreductase (GOXv247) protein, provided to complement information related to application EFSA‐GMO‐NL‐2009‐75 for the placing on the market of oilseed rape Ms8 × Rf3 × GT73 and its subcombinations Ms8 × GT73 and Rf3 × GT73, for food and feed uses, import and processing, with the exception of isolated seed protein for food. The 28‐day toxicity study on Escherichia coli‐ produced GOXv247 protein did not show adverse effects in mice, at the gavage doses up to 1000 mg/kg body weight (bw) per day. Taking into account its previous assessment on EFSA‐GMO‐NL‐2009‐75 and the outcome of the 28‐day toxicity study in mice with the GOXv247 protein provided in this mandate, the GMO Panel, based on a weight of evidence approach, concludes that food and feed containing, consisting and produced from genetically modified oilseed rape Ms8 × Rf3 × GT73 and its sub combinations Ms8 × GT73 and Rf3 × GT73, are as safe as its conventional counterpart, according to the scope as defined in the application EFSA‐GMO‐NL‐2009‐75

Assessment of genetically modified maize MIR604 for renewal authorisation under Regulation (EC) No 1829/2003 (application EFSA‐GMO‐RX‐013)

Following the submission of application EFSA‐GMO‐RX‐013 under Regulation (EC) No 1829/2003 from Syngenta Crop Protection NV/SA, the EFSA Panel on Genetically Modified Organisms (GMO) was asked to deliver a scientific risk assessment on the data submitted in the context of the renewal of authorisation application for the insect‐resistant genetically modified maize MIR604, for food and feed uses, excluding cultivation within the EU. The data received in the context of this renewal application contained post‐market environmental monitoring reports, a systematic search and evaluation of literature, updated bioinformatic analyses, and additional documents or studies performed by or on behalf of the applicant. The GMO Panel assessed these data for possible new hazards, modified exposure or new scientific uncertainties identified during the authorisation period and not previously assessed in the context of the original application. Under the assumption that the DNA sequence of the event in maize MIR604 considered for renewal is identical to the corrected sequence of the originally assessed event, the GMO Panel concludes that there is no evidence in renewal application EFSA‐GMO‐RX‐013 for new hazards, modified exposure or scientific uncertainties that would change the conclusions of the original risk assessment on maize MIR604

Assessment of genetically modified oilseed rape GT73 for renewal authorisation under Regulation (EC) No 1829/2003 (application EFSA‐GMO‐RX‐002)

Following the submission of application EFSA‐GMO‐RX‐002 under Regulation (EC) No 1829/2003 from Monsanto Company, the Panel on Genetically Modified Organisms of EFSA (GMO) was asked to deliver a scientific risk assessment on the data submitted in the context of the renewal of authorisation application for the herbicide‐tolerant genetically modified oilseed rape GT73. The data received in the context of this renewal application contained post‐market environmental monitoring reports, a systematic search and evaluation of literature, updated bioinformatic analyses and additional documents or studies performed by or on behalf of the applicant. The GMO Panel assessed these data for possible new hazards, modified exposure or new scientific uncertainties identified during the authorisation period and not previously assessed in the context of the original application. Under the assumption that the DNA sequence of the event in oilseed rape GT73 considered for renewal of authorisation is identical to the sequence of the originally assessed event, the GMO Panel concludes that there is no evidence in renewal application EFSA‐GMO‐RX‐002 for new hazards, modified exposure or scientific uncertainties that would change the conclusions of the original risk assessment on oilseed rape GT73

Assessment of genetically modified maize MON 88017 for renewal authorisation under Regulation (EC) No 1829/2003 (application EFSA‐GMO‐RX‐014)

Following the submission of application EFSA‐GMO‐RX‐014 under Regulation (EC) No 1829/2003 from Monsanto Company the Panel on Genetically Modified Organisms of the European Food Safety Authority was asked to deliver a scientific risk assessment on the data submitted in the context of the renewal of authorisation application for the insect‐resistant and herbicide‐tolerant genetically modified maize MON 88017, for food and feed uses, excluding cultivation within the EU. The data received in the context of this renewal application contained post‐market environmental monitoring reports, a systematic search and evaluation of literature, updated bioinformatic analyses, and additional documents or studies performed by or on behalf of the applicant. The GMO Panel assessed these data for possible new hazards, modified exposure or new scientific uncertainties identified during the authorisation period and not previously assessed in the context of the original application. Under the assumption that the DNA sequence of the event in maize MON 88017 considered for renewal is identical to the sequence of the originally assessed event, the GMO Panel concludes that there is no evidence in renewal application EFSA‐GMO‐RX‐014 for new hazards, modified exposure or scientific uncertainties that would change the conclusions of the original risk assessment on maize MON 88017

Assessment of genetically modified maize MON 89034 for renewal authorisation under Regulation (EC) No 1829/2003 (application EFSA-GMO-RX-015)

Following the submission of application EFSA-GMO-RX-015 under Regulation (EC) No 1829/2003 from Bayer Agriculture BVBA, the EFSA Panel on Genetically Modified Organisms (GMO Panel) was asked to deliver a scientific risk assessment on the data submitted in the context of the renewal of authorisation application for the insect-resistant genetically modified maize MON 89034, for food and feed uses, excluding cultivation within the EU. The data received in the context of this renewal application contained post-market environmental monitoring reports, a systematic search and evaluation of literature, updated bioinformatic analyses and additional documents or studies performed by or on behalf of the applicant. The GMO Panel assessed these data for possible new hazards, modified exposure or new scientific uncertainties identified during the authorisation period and not previously assessed in the context of the original application. Under the assumption that the DNA sequence of the event in maize MON 89034 considered for renewal is identical to the sequence of the originally assessed event, the GMO Panel concludes that there is no evidence in renewal application EFSA-GMO-RX-015 for new hazards, modified exposure or scientific uncertainties that would change the conclusions of the original risk assessment on maize MON 89034

Statement complementing the EFSA Scientific Opinion on application (EFSA‐GMO‐UK‐2006‐34) for authorisation of food and feed containing, consisting of and produced from genetically modified maize 3272

Following a request from the European Commission, the GMO Panel assessed additional information related to the application for authorisation of food and feed containing, consisting of and produced from genetically modified (GM) maize 3272 (EFSA‐GMO‐UK‐2006‐34). The applicant conducted new agronomic, phenotypic and compositional analysis studies on maize 3272 and assessed the allergenic potential of AMY797E protein, addressing elements that remained inconclusive from previous EFSA opinion issued in 2013. The GMO Panel is of the opinion that the agronomic and phenotypic characteristics as well as forage and grain composition of maize 3272 do not give rise to food and feed safety, and nutritional concerns when compared to non‐GM maize. Considering the scope of this application and the characteristics of the trait introduced in this GM maize, the effect of processing and potential safety implications of specific food or feed products remain to be further investigated. Regarding the allergenic potential of AMY797E protein and considering all possible food and feed uses of maize 3272, the Panel concludes that the information provided does not fully address the concerns previously raised by the Panel in 2013. Owing to the nature and the knowledge available on this protein family, it is still unclear whether under specific circumstances the alpha‐amylase AMY797E has the capacity to sensitise certain individuals and to cause adverse effects. To further support the safety of specific products of maize 3272, the applicant provided thorough information relevant for the allergenicity assessment of dried distiller grains with solubles (DDGS), which is the main product of interest for importation into the EU. Having considered the information provided on this product, the Panel is of the opinion that under the specific conditions of use described by the applicant, DDGS produced from maize 3272 does not raise concerns when compared to DDGS from non‐GM maize

Identifying Signatures of Natural Selection in Tibetan and Andean Populations Using Dense Genome Scan Data

High-altitude hypoxia (reduced inspired oxygen tension due to decreased barometric pressure) exerts severe physiological stress on the human body. Two high-altitude regions where humans have lived for millennia are the Andean Altiplano and the Tibetan Plateau. Populations living in these regions exhibit unique circulatory, respiratory, and hematological adaptations to life at high altitude. Although these responses have been well characterized physiologically, their underlying genetic basis remains unknown. We performed a genome scan to identify genes showing evidence of adaptation to hypoxia. We looked across each chromosome to identify genomic regions with previously unknown function with respect to altitude phenotypes. In addition, groups of genes functioning in oxygen metabolism and sensing were examined to test the hypothesis that particular pathways have been involved in genetic adaptation to altitude. Applying four population genetic statistics commonly used for detecting signatures of natural selection, we identified selection-nominated candidate genes and gene regions in these two populations (Andeans and Tibetans) separately. The Tibetan and Andean patterns of genetic adaptation are largely distinct from one another, with both populations showing evidence of positive natural selection in different genes or gene regions. Interestingly, one gene previously known to be important in cellular oxygen sensing, EGLN1 (also known as PHD2), shows evidence of positive selection in both Tibetans and Andeans. However, the pattern of variation for this gene differs between the two populations. Our results indicate that several key HIF-regulatory and targeted genes are responsible for adaptation to high altitude in Andeans and Tibetans, and several different chromosomal regions are implicated in the putative response to selection. These data suggest a genetic role in high-altitude adaption and provide a basis for future genotype/phenotype association studies necessary to confirm the role of selection-nominated candidate genes and gene regions in adaptation to altitude