reCAPTCHA: human-based character recognition via Web security measures     

von Ahn L  Maurer B  McMillen C  Abraham D  Blum M 《Science (New York, N.Y.)》2008,321(5895):1465-1468

CAPTCHAs (Completely Automated Public Turing test to tell Computers and Humans Apart) are widespread security measures on the World Wide Web that prevent automated programs from abusing online services. They do so by asking humans to perform a task that computers cannot yet perform, such as deciphering distorted characters. Our research explored whether such human effort can be channeled into a useful purpose: helping to digitize old printed material by asking users to decipher scanned words from books that computerized optical character recognition failed to recognize. We showed that this method can transcribe text with a word accuracy exceeding 99%, matching the guarantee of professional human transcribers. Our apparatus is deployed in more than 40,000 Web sites and has transcribed over 440 million words.  相似文献   

High Embryonic Recovery Rates with In vivo and Ex vivo Techniques in the Bitch     

MR Luz  CC de Holanda  JJ Pereira  PMC Freitas  AEP Salgado  J Di Giorgio Giannotti  SB de Oliveira  NS Teixeira  CR de Freitas Guaitolini 《Reproduction in domestic animals》2011,46(4):724-727

The embryonic collection techniques in dogs present a vast methodological variation and low recovery rates. The objectives were to compare and describe two techniques as to the recovery of canine embryos, on the 12th day after the first mating or artificial insemination. Embryos were recovered through uterine horn flushing in vivo, before performing the ovariohysterectomy (OHE) (Group 1; n = 9) or ex vivo, immediately after the OHE (Group 2; n = 9). In total, 43 and 47 embryonic structures were recovered in Groups 1 and 2, respectively. There was no significant difference (p > 0.05) between groups on recovery rates (72.8% and 81.0%, respectively). We inferred that both in vivo and ex vivo techniques allow a high rate of embryonic recovery; in the collection technique prior to the OHE, it is essential to carefully handle the reproductive system during the trans‐surgical period and that the 12th day (D12) after the first mating/artificial insemination is an efficient option for the high recovery rate of morulae and blastocysts.  相似文献   

Ceramide biogenesis is required for radiation-induced apoptosis in the germ line of C. elegans     

Deng X  Yin X  Allan R  Lu DD  Maurer CW  Haimovitz-Friedman A  Fuks Z  Shaham S  Kolesnick R 《Science (New York, N.Y.)》2008,322(5898):110-115

Ceramide engagement in apoptotic pathways has been a topic of controversy. To address this controversy, we tested loss-of-function (lf) mutants of conserved genes of sphingolipid metabolism in Caenorhabditis elegans. Although somatic (developmental) apoptosis was unaffected, ionizing radiation-induced apoptosis of germ cells was obliterated upon inactivation of ceramide synthase and restored upon microinjection of long-chain natural ceramide. Radiation-induced increase in the concentration of ceramide localized to mitochondria and was required for BH3-domain protein EGL-1-mediated displacement of CED-4 (an APAF-1-like protein) from the CED-9 (a Bcl-2 family member)/CED-4 complex, an obligate step in activation of the CED-3 caspase. These studies define CEP-1 (the worm homolog of the tumor suppressor p53)-mediated accumulation of EGL-1 and ceramide synthase-mediated generation of ceramide through parallel pathways that integrate at mitochondrial membranes to regulate stress-induced apoptosis.  相似文献   

Connected to death: the (unexpurgated) mitochondrial pathway of apoptosis     

Spierings D  McStay G  Saleh M  Bender C  Chipuk J  Maurer U  Green DR 《Science (New York, N.Y.)》2005,310(5745):66-67

The mitochondrial pathway of apoptosis in vertebrates is dependent on the process of mitochondrial outer membrane permeabilization (MOMP), which leads to the release of proteins from the mitochondrial intermembrane space into the cytosol. "Upstairs" of this event are the Bcl-2 family proteins that regulate and mediate MOMP; "downstairs" is the activation of caspases that orchestrate the dismantling of the cell. In the Connections Map database at Science's Signal Transduction Knowledge Environment (STKE), the pathways that define the mitochondrial pathway of apotosis are illustrated, with the bulk of control occurring "upstairs" of MOMP.  相似文献   

Macroecology: the division of food and space among species on continents   总被引：2，自引：0，他引：2  

Brown JH  Maurer BA 《Science (New York, N.Y.)》1989,243(4895):1145-1150

Analyses of statistical distributions of body mass, population density, and size and shape of geographic range offer insights into the empirical patterns and causal mechanisms that characterize the allocation of food and space among the diverse species in continental biotas. These analyses also provide evidence of the processes that couple ecological phenomena that occur on disparate spatial and temporal scales-from the activities of individual organisms within local populations to the dynamics of continent-wide speciation, colonization, and extinction events.  相似文献   

"RIGHT-HANDEDNESS" IN WHITE RATS     

Tsai LS  Maurer S 《Science (New York, N.Y.)》1930,72(1869):436-438

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Effect of Estradiol and Progesterone on Metabolic Biomarkers in Healthy Bitches     

A Tvarijonaviciute  JD Carrillo‐Sanchez  JJ Ceron 《Reproduction in domestic animals》2013,48(3):520-524

The aim of this study was to evaluate the possible association between hormonal changes that occur during oestrus and biomarkers related with glucose metabolism (glucose and insulin), lipid metabolism (lipidic profile and BChE) and adipokines (adiponectin and ghrelin) in healthy bitches. For this purpose, we measured these analytes in serum of bitches, at two times: before (T1) and after (T2) the LH peak that were established according to progesterone concentrations. Increased levels of total cholesterol (p < 0.01), high density lipoprotein cholesterol (HDL‐C) (p < 0.01), low density lipoprotein cholesterol (LDL‐C) (p < 0.01), adiponectin (p < 0.01) and ghrelin (p < 0.05) were observed at T2 in comparison with T1. No statistically significant changes were observed in serum glucose, insulin, homoeostasis model assessment for insulin sensitivity (HOMA), triglycerides and BChE. When all data of T1 and T2 were pooled, serum adiponectin showed positive correlation with progesterone (r = 0.353; p = 0.022) and HDL‐C (r = 0.307; p = 0.048), and negative with insulin (r = ?0.429; p = 0.005), HOMA (r = ?0.446; p = 0.003) and BChE (r = ?0.522; p < 0.001). Ghrelin showed negative correlation with estradiol (r = ?0.701; p = 0.004). BChE was negatively correlated with estradiol (r = ?0.441; p = 0.018) and glucose (r = ?0.343; p = 0.028), and positively with insulin (r = 0.460; p = 0.003) and HOMA (r = 0.505; p < 0.001). In conclusion, changes in metabolic biomarkers occur in bitches after LH peak, characterized by increased lipids (total cholesterol, HDL cholesterol and LDL cholesterol) without changes in BChE activity, and increased adiponectin and ghrelin concentrations, without significant changes in glucose and insulin.  相似文献   

Oestrous Synchronization,Ovarian Superovulation and Intraspecific Transfers From a Closed Breeding Colony of Inbred SLA Miniature Pigs     

JJ Arlaud  L Baker  RL Williams  AJ French 《Reproduction in domestic animals》2010,45(6):951-958

The inbred SLA miniature pig is a unique animal model developed for organ transplantation studies and pre‐clinical experimental purposes. Reported oestrous synchronization and superovulation treatments were examined in two SLA haplotypes (AA and DD) to allow collection of embryos for both practical embryo transfer and experimental technologies from a closed breeding colony. Pre‐puberal miniature pigs were poor responders to oestrous synchronization treatments, while post‐puberal sows were equivalent to commercial sows. Following superovulation, the ovulation number (corpora .hemorrhagica) was higher (p < 0.05) in the cycling sows when compared with non‐cycling sows. Ovulations were equivalent to commercial pre‐puberal gilts and non‐cycling sows (p > 0.05). No difference in ovulation number between haplotypes was observed, which differs from the previous report (DD>AA). Collection of zygotes for pronuclear injection was the highest in the non‐cycling post‐puberal miniature pig group (p < 0.05), although significantly lower when compared with the commercial pig treatment groups (p < 0.05). The incidence of cystic endometrial hyperplasia in our colony was equivalent to rates observed in commercial pigs. Pronuclear visualization following centrifugation was the highest in the non‐cycling miniature sow group and approximates to about 25% of ovulations and about half the rate observed in the commercial pigs (50%). Miniature pig embryos transferred between SLA haplotypes and transfer of DD embryos to commercial pigs resulted in live births at a higher efficiency than previously reported. This study demonstrates the feasibility of undertaking assisted reproductive technologies in a closed breeding colony of inbred SLA miniature pigs without compromise to the breeding programmes.  相似文献   

Multivariate correlations between imagery and field measurements across scales: comparing pixel aggregation and image segmentation     

Jason W. Karl  Brian A. Maurer 《Landscape Ecology》2010,25(4):591-605

To successfully use remotely-sensed data in landscape-level management, questions as to the relevance of image data to landscape patterns and optimal scales of analysis must be addressed. Object-based image analysis, segmenting images into homogeneous regions called objects, has been suggested for increasing accuracy of remotely-sensed products, but little research has gone into determining image object size with regard to scaling of ecosystem properties. We looked at how segmentation of high-resolution Ikonos and medium-resolution Landsat images into successively coarser objects affected multivariate correlations between image data and eight percent-cover measurements of a sagebrush ecosystem. We also looked at changes in correlation as imagery was aggregated into larger square pixels. We found similar canonical correlations between field and image data at the finest scales, but higher for image segmentation than pixel aggregation for both images when scale increased. For image segmentation, correlations between the canonical variables and original field variables were invariant with respect to size of the image objects, suggesting linear scaling of vegetation cover in our study system. We detected a scaling threshold with the Ikonos segmentation and confirmed with a semi-variogram of the sample data. Below the threshold interpretation of the canonical variables was consistent: scale levels differed primarily in the amount of detail portrayed. Above the threshold, meaning of the canonical variables changed. This approach proved useful for evaluating overall utility of images to address an objective, and identified scaling limits for analysis. Selection of appropriate scale for analysis will ultimately depend on the objective being considered.  相似文献   

Correlation between Fusarium head blight severity and DON content in triticale as revealed by phenotypic and molecular data          下载免费PDF全文

Thomas Miedaner  Rasha Kalih  Maren S. Großmann  Hans P. Maurer 《Plant Breeding》2016,135(1):31-37

Fusarium head blight (FHB) in triticale (× Triticosecale Wittmack) results in yield losses and mycotoxin contamination, for example, by deoxynivalenol (DON). This study aimed to analyse the correlation between FHB severity and DON content in a DH population of 146 entries across environments. Additionally, Fusarium damaged kernel (FDK) rating, heading stage and plant height were recorded. Highly significant (P < 0.001) genotypic variances were found throughout, but also significant (P < 0.001) genotype–environment interaction variances occurred. Correlation between FHB severity and heading stage or plant height was low (r = 0.144 and r = ?0.153, P < 0.10). A prediction of DON content from FHB severity or FDK rating is not possible caused by low correlations (r = 0.315 and 0.572, respectively, P < 0.001). A common quantitative trait locus (QTL) for all FHB‐related traits was found on wheat chromosome 2A being of minor importance for FHB severity, but of high importance for DON content and FDK rating. Another QTL on rye chromosome 5R was more important for FHB severity. In conclusion, DON content has to be measured in triticale after selection for FHB severity to gain for healthy and mycotoxin‐reduced feed.  相似文献