Artigos de revistas: "H21"

1

Fossati, Amedeo. "The Italian Tradition in Public Finance: An Annotated Bibliography of Mauro Fasiani". STUDI ECONOMICI, n.º 105 (maio de 2012): 5–122. http://dx.doi.org/10.3280/ste2011-105001.

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Mauro Fasiani's scholarly achievement still does not occupy its proper place in scientific debate, either in Italy or abroad. Thus, the enhancement of the scientific figure of Mauro Fasiani presents a very significant scientific interest, in order to finally put into perspective his contribution to the evolution of the theory of public finance not only in the Italian tradition in Public Finance but in the international context also. To that end the present paper is directed, within the limits that the aim is not to discuss Fasiani's scientific thought, but only to draw it to the attention of international scholars by making known the content of his work. JEL CODE: B13, B31, H1, H12, H21, H22, H24, H25, H26, H31, H32, H42, H43, H44, H50, H89

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Bumunang, Emmanuel W., Collins N. Ateba, Kim Stanford, Tim A. McAllister e Yan D. Niu. "Biofilm formation by South African non-O157 Shiga toxigenic Escherichia coli on stainless steel coupons". Canadian Journal of Microbiology 66, n.º 4 (abril de 2020): 328–36. http://dx.doi.org/10.1139/cjm-2019-0554.

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This study examined the biofilm-forming ability of six non-O157 Shiga-toxin-producing Escherichia coli (STEC) strains: O116:H21, wzx-Onovel5:H19, O129:H21, O129:H23, O26:H11, and O154:H10 on stainless steel coupons after 24, 48, and 72 h of incubation at 22 °C and after 168 h at 10 °C. The results of crystal violet staining revealed that strains O129:H23 and O154:H10 were able to form biofilms on both the submerged surface and the air–liquid interface of coupons, whereas strains O116:H21, wzx-Onovel5:H19, O129:H21, and O26:H11 formed biofilm only at the air–liquid interface. Viable cell counts and scanning electron microscopy showed that biofilm formation increased (p < 0.05) over time. The biofilm-forming ability of non-O157 STEC was strongest (p < 0.05) at 22 °C after 48 h of incubation. The strongest biofilm former regardless of temperature was O129:H23. Generally, at 10 °C, weak to no biofilm was observed for isolates O154:H10, O116:H21, wzx-Onovel5:H19, O26:H11, and O129:H21 after 168 h. This study found that temperature affected the biofilm-forming ability of non-O157 STEC strains. Overall, our data indicate a high potential for biofilm formation by the isolates at 22 °C, suggesting that non-O157 STEC strains could colonize stainless steel within food-processing facilities. This could serve as a potential source of adulteration and promote the dissemination of these potential pathogens in food.

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Keskimäki, Markku, Marjut Saari, Tarja Heiskanen e Anja Siitonen. "Shiga Toxin-Producing Escherichia coliin Finland from 1990 through 1997: Prevalence and Characteristics of Isolates". Journal of Clinical Microbiology 36, n.º 12 (1998): 3641–46. http://dx.doi.org/10.1128/jcm.36.12.3641-3646.1998.

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During the past 10 years Shiga toxin-producing Escherichia coli (STEC) has emerged as one of the most important causes of food-borne infections in industrialized countries. In Finland, with a population of 5.1 million, however, only four STEC O157:H7 infections were identified from 1990 through 1995; the occurrence of non-O157 STEC infections was unknown. In 1996, we established a national prospective study to determine the prevalence of STEC serotypes in feces of Finns with bloody diarrhea. During this enhanced 1-year study period eight sporadic cases of STEC infection were found; of them, only two were indigenously acquired O157:H7 infections. In 1997, O157 infections increased dramatically, with O157 strains causing 51 of all 61 STEC infections. Altogether 14 non-O157:H7 STEC strains were found in Finland in the 1990s: O26:H11 (four strains), O26:HNM (HNM indicates nonmotile), O2:H29, O91:H21, O91:H40, O101:HNM, O107:H27, O157:HNM, O165:H25, OX3:H21, and Rough:H49. All O157:H7 and O26:H11 isolates produced enterohemolysin, but seven of the other STEC strains did not. Most (n = 63) of the 71 STEC strains isolated carried the stx 2 gene only, five carried thestx 1 gene only, and three carried both genes. The eaeA gene was detected in all other isolates except five non-O157 strains. There were seven distinct pulsed-field gel electrophoresis (PFGE) genotypes among 57 O157 strains and three distinct PFGE types among four O26:H11 strains. The main PFGE type was found among 65% of all O157 isolates.

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Miko, Angelika, Karin Pries, Sabine Haby, Katja Steege, Nadine Albrecht, Gladys Krause e Lothar Beutin. "Assessment of Shiga Toxin-Producing Escherichia coli Isolates from Wildlife Meat as Potential Pathogens for Humans". Applied and Environmental Microbiology 75, n.º 20 (21 de agosto de 2009): 6462–70. http://dx.doi.org/10.1128/aem.00904-09.

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ABSTRACT A total of 140 Shiga toxin-producing Escherichia coli (STEC) strains from wildlife meat (deer, wild boar, and hare) isolated in Germany between 1998 and 2006 were characterized with respect to their serotypes and virulence markers associated with human pathogenicity. The strains grouped into 38 serotypes, but eight O groups (21, 146, 128, 113, 22, 88, 6, and 91) and four H types (21, 28, 2, and 8) accounted for 71.4% and 75.7% of all STEC strains from game, respectively. Eighteen of the serotypes, including enterohemorrhagic E. coli (EHEC) O26:[H11] and O103:H2, were previously found to be associated with human illness. Genes linked to high-level virulence for humans (stx 2, stx 2d, and eae) were present in 46 (32.8%) STEC strains from game. Fifty-four STEC isolates from game belonged to serotypes which are frequently found in human patients (O103:H2, O26:H11, O113:H21, O91:H21, O128:H2, O146:H21, and O146:H28). These 54 STEC isolates were compared with 101 STEC isolates belonging to the same serotypes isolated from farm animals, from their food products, and from human patients. Within a given serotype, most STEC strains were similar with respect to their stx genotypes and other virulence attributes, regardless of origin. The 155 STEC strains were analyzed for genetic similarity by XbaI pulsed-field gel electrophoresis. O103:H2, O26:H11, O113:H21, O128:H2, and O146:H28 STEC isolates from game were 85 to 100% similar to STEC isolates of the same strains from human patients. By multilocus sequence typing, game EHEC O103:H2 strains were attributed to a clonal lineage associated with hemorrhagic diseases in humans. The results from our study indicate that game animals represent a reservoir for and a potential source of human pathogenic STEC and EHEC strains.

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5

Milligan, Kevin, e Michael Smart. "An Estimable Model of Income Redistribution in a Federation: Musgrave Meets Oates". American Economic Journal: Economic Policy 11, n.º 1 (1 de fevereiro de 2019): 406–34. http://dx.doi.org/10.1257/pol.20160600.

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We develop a theory of cross-border income shifting in response to subnational personal taxation in a federation and examine its implications for the excess burden of personal taxes. We show how a properly chosen federal tax rate can offset the fiscal externality between states and facilitate decentralization, even in a heterogeneous federation where unitary taxation is suboptimal. Optimal taxes depend on the elasticities of national tax avoidance and of cross-state tax base shifting. We estimate these elasticities around a tax decentralization reform in Canada, finding both to be empirically relevant. We discuss the implications for optimal federalism. (JEL D31, H21, H23, H24, H26, H71, H77)

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Mora, Azucena, Cecilia López, Ghizlane Dhabi, Ana M. López-Beceiro, Luís E. Fidalgo, Eduardo A. Díaz, Carlos Martínez-Carrasco et al. "Seropathotypes, Phylogroups, Stx Subtypes, and Intimin Types of Wildlife-Carried, Shiga Toxin-Producing Escherichia coli Strains with the Same Characteristics as Human-Pathogenic Isolates". Applied and Environmental Microbiology 78, n.º 8 (3 de fevereiro de 2012): 2578–85. http://dx.doi.org/10.1128/aem.07520-11.

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ABSTRACTThe objectives of this study were to investigate the presence of Shiga toxin-producingEscherichia coli(STEC) strains in wildlife that have spread in Europe, living near human settlements; to analyze their epidemiological role in maintenance and transmission to domestic livestock; and to assess the potential health risk of wildlife-carried strains. STEC strains were recovered from 53% of roe deer, 8.4% of wild boars, and 1.9% of foxes sampled in the northwest of Spain (Galicia). Of the 40 serotypes identified, 21 were classified as seropathotypes associated with human disease, accounting for 81.5% of the wildlife-carried STEC strains, including the enterohemorrhagic serotypes O157:H7-D-eae-γ1, O26:[H11]-B1-eae-β1, O121:H19-B1-eae-ε1, and O145:[H28]-D-eae-γ1. None of the wildlife-carried strains belonged to the highly pathogenic serotype O104:H4-B1 from the recent Germany outbreak. Forty percent of wildlife-carried STEC strains shared serotypes, phylogroups, intimin types, and Stx profiles with isolates from human patients from the same geographic area. Furthermore, wildlife-carried strains belonging to serotypes O5:HNM-A, O26:[H11]-B1, O76:H19-B1, O145:[H28]-D, O146:H21-B1, and O157:H7-D showed pulsed-field gel electrophoresis (PFGE) profiles with >85% similarity to human-pathogenic STEC strains. We also found a high level of similarity among STEC strains of serotypes O5:HNM-A, O26:[H11]-B1, and O145:HNM-D of bovine (feces and beef) and wildlife origins. Interestingly, O146:H21-B1, the second most frequently detected serotype in this study, is commonly associated with human diarrhea and isolated from beef and vegetables sold in Galicia. Importantly, at least 3 STEC isolates from foxes (O5:HNM-A-eae-β1, O98:[H21]-B1-eae-ζ1, and O146:[H21]-B1) showed characteristics similar to those of human STEC strains. In conclusion, roe deer, wild boar, and fox in Galicia are confirmed to be carriers of STEC strains potentially pathogenic for humans and seem to play an important role in the maintenance of STEC.

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7

Bugarel, Marie, Lothar Beutin e Patrick Fach. "Low-Density Macroarray Targeting Non-Locus of Enterocyte Effacement Effectors (nle Genes) and Major Virulence Factors of Shiga Toxin-Producing Escherichia coli (STEC): a New Approach for Molecular Risk Assessment of STEC Isolates". Applied and Environmental Microbiology 76, n.º 1 (30 de outubro de 2009): 203–11. http://dx.doi.org/10.1128/aem.01921-09.

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ABSTRACT Rapid and specific detection of Shiga toxin-producing Escherichia coli (STEC) strains with a high level of virulence for humans has become a priority for public health authorities. This study reports on the development of a low-density macroarray for simultaneously testing the genes stx 1, stx 2, eae, and ehxA and six different nle genes issued from genomic islands OI-122 (ent, nleB, and nleE) and OI-71 (nleF, nleH1-2, and nleA). Various strains of E. coli isolated from the environment, food, animals, and healthy children have been compared with clinical isolates of various seropathotypes. The eae gene was detected in all enteropathogenic E. coli (EPEC) strains as well as in enterohemorrhagic E. coli (EHEC) strains, except in EHEC O91:H21 and EHEC O113:H21. The gene ehxA was more prevalent in EHEC (90%) than in STEC (42.66%) strains, in which it was unequally distributed. The nle genes were detected only in some EPEC and EHEC strains but with various distributions, showing that nle genes are strain and/or serotype specific, probably reflecting adaptation of the strains to different hosts or environmental niches. One characteristic nle gene distribution in EHEC O157:[H7], O111:[H8], O26:[H11], O103:H25, O118:[H16], O121:[H19], O5:H−, O55:H7, O123:H11, O172:H25, and O165:H25 was ent/espL2, nleB, nleE, nleF, nleH1-2, nleA. (Brackets indicate genotyping of the flic or rfb genes.) A second nle pattern (ent/espL2, nleB, nleE, nleH1-2) was characteristic of EHEC O103:H2, O145:[H28], O45:H2, and O15:H2. The presence of eae, ent/espL2, nleB, nleE, and nleH1-2 genes is a clear signature of STEC strains with high virulence for humans.

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8

Beaudry, Paul, Charles Blackorby e Dezsö Szalay. "Taxes and Employment Subsidies in Optimal Redistribution Programs". American Economic Review 99, n.º 1 (1 de fevereiro de 2009): 216–42. http://dx.doi.org/10.1257/aer.99.1.216.

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This paper explores how to optimally set taxes and transfers when taxation authorities are uninformed about individuals' value of time in both market and nonmarket activities; and can observe both market-income and time allocated to market employment. We show that optimal redistribution in this environment involves a cutoff wage whereby workers above the cutoff are taxed as they increase their income, while workers earning a wage below the cutoff receive an income supplement as they increase their income. Finally, we show that the optimal program transfers zero income to individuals who choose not to work. (JEL D31, H21, H23, H24)

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9

Gottardi, Piero, Atsushi Kajii e Tomoyuki Nakajima. "Optimal Taxation and Debt with Uninsurable Risks to Human Capital Accumulation". American Economic Review 105, n.º 11 (1 de novembro de 2015): 3443–70. http://dx.doi.org/10.1257/aer.20110576.

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We consider an economy where individuals face uninsurable risks to their human capital accumulation and analyze the optimal level of linear taxes on capital and labor income together with the optimal path of government debt. We show that in the presence of such risks, it is beneficial to tax both labor and capital and to issue public debt. We also assess the quantitative importance of these findings, and show that the benefits of government debt and capital taxes both increase with the magnitude of idiosyncratic risks and the degree of relative risk aversion. (JEL D52, H21, H24, H25, H63, J24)

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10

Ales, Laurence, Musab Kurnaz e Christopher Sleet. "Technical Change, Wage Inequality, and Taxes". American Economic Review 105, n.º 10 (1 de outubro de 2015): 3061–101. http://dx.doi.org/10.1257/aer.20140466.

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This paper considers the normative implications of technical change for tax policy design. A task-to-talent assignment model of the labor market is embedded into an optimal tax problem. Technical change modifies equilibrium wage growth across talents and the substitutability of talents across tasks. The overall optimal policy response is to reduce marginal income taxes on low to middle incomes, while raising those on middle to high incomes. The reform favors those in the middle of the income distribution, reducing their average taxes while lowering transfers to those at the bottom. (JEL D31, H21, H23, H24, J31, O33)

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11

Benhabib, Jess, e Bálint Szoőke. "Optimal Positive Capital Taxes at Interior Steady States". American Economic Journal: Macroeconomics 13, n.º 1 (1 de janeiro de 2021): 114–50. http://dx.doi.org/10.1257/mac.20180191.

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We generalize recent results of Bassetto and Benhabib (2006) and Straub and Werning (2019) in a neoclassical model with endogenous labor-leisure choice where all agents are allowed to save and accumulate capital. We provide a sufficient condition under which optimal redistributive capital taxes remain at their allowed upper bound forever, even if the resulting equilibrium trajectory converges to a unique steady state with positive and finite consumption, capital, and labor. We then provide an interpretation of our sufficient condition. Using recent evidence on wealth distribution in the United States, we argue that our sufficient condition is empirically plausible. (JEL D31, E21, H21, H23, H25, J22)

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12

Conesa, Juan Carlos, Sagiri Kitao e Dirk Krueger. "Taxing Capital? Not a Bad Idea After All!" American Economic Review 99, n.º 1 (1 de fevereiro de 2009): 25–48. http://dx.doi.org/10.1257/aer.99.1.25.

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We quantitatively characterize the optimal capital and labor income tax in an overlapping generations model with idiosyncratic, uninsurable income shocks and permanent productivity differences of households. The optimal capital income tax rate is significantly positive at 36 percent. The optimal progressive labor income tax is, roughly, a flat tax of 23 percent with a deduction of $7,200 (relative to average household income of $42,000). The high optimal capital income tax is mainly driven by the life-cycle structure of the model, whereas the optimal progressivity of the labor income tax is attributable to the insurance and redistribution role of the tax system. (JEL E13, H21, H24, H25)

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13

Miravete, Eugenio J., Katja Seim e Jeff Thurk. "One Markup to Rule Them All: Taxation by Liquor Pricing Regulation". American Economic Journal: Microeconomics 12, n.º 1 (1 de fevereiro de 2020): 1–41. http://dx.doi.org/10.1257/mic.20180155.

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Commodity taxation often involves uniform tax rates. We use alcohol laws that tax differentiated spirits with a comprehensive uniform markup to evaluate redistribution generated by such simple tax policy. We document preference heterogeneity among consumers, variation in product demand elasticities, and market power among producers with heterogeneous product portfolios. Relative to more flexible product-level markups recognizing demand heterogeneity and strategic price responses of firms, we find that the uniform markup underprices less elastic spirits, implicitly subsidizing low-income and less educated residents. The uniform markup grants additional market power to small specialized firms whose product positioning benefits from the policy.(JEL D12, H21, H23, H25, L43, L66)

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14

Morelli, Massimo, Huanxing Yang e Lixin Ye. "Competitive Nonlinear Taxation and Constitutional Choice". American Economic Journal: Microeconomics 4, n.º 1 (1 de fevereiro de 2012): 142–75. http://dx.doi.org/10.1257/mic.4.1.142.

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In an economy where agents have different productivities and mobility, we compare a unified nonlinear optimal taxation with the equilibrium taxation that would be chosen by two competing tax authorities if the same economy were divided into two states. The overall level of progressivity and redistribution is unambiguously lower under competitive taxation; the “rich” are always in favor of competing authorities, whereas the “poor” are always in favor of unified taxation; the preferences of the middle class depend on the initial conditions in terms of the distribution of abilities, the relative power of the various classes, and mobility costs. (JEL D72, H21, H23, H24)

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15

Mankiw, N. Gregory, e Matthew Weinzierl. "The Optimal Taxation of Height: A Case Study of Utilitarian Income Redistribution". American Economic Journal: Economic Policy 2, n.º 1 (1 de fevereiro de 2010): 155–76. http://dx.doi.org/10.1257/pol.2.1.155.

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Should the income tax include a credit for short taxpayers and a surcharge for tall ones? The standard utilitarian framework for tax analysis answers this question in the affirmative. Moreover, a plausible parameterization using data on height and wages implies a substantial height tax: a tall person earning $50,000 should pay $4,500 more in tax than a short person. One interpretation is that personal attributes correlated with wages should be considered more widely for determining taxes. Alternatively, if policies such as a height tax are rejected, then the standard utilitarian framework must fail to capture intuitive notions of distributive justice. (JEL D64, H21, H23, H24, J11)

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Cremer, Helmuth, Firouz Gahvari e Jean-Marie Lozachmeur. "Tagging and Income Taxation: Theory and an Application". American Economic Journal: Economic Policy 2, n.º 1 (1 de fevereiro de 2010): 31–50. http://dx.doi.org/10.1257/pol.2.1.31.

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We derive a set of analytical results for optimal income taxation with tags using quasilinear preferences and a Rawlsian social welfare function. Secondly, assuming a constant elasticity of labor supply and log-normality of the skills distribution, we analytically identify the winners and losers of tagging. Third, we prove that if the skills distribution in one group first-order stochastically dominates the other, tagging calls for redistribution from the former to the latter group. Finally, we calibrate our model to the US workers using gender as tag. Welfare implications are dramatic. Only male high-wage earners lose. Everyone else gains, some substantially. (JEL H21, H23, H24)

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Aronsson, Thomas, e Olof Johansson-Stenman. "Paternalism against Veblen: Optimal Taxation and Non-respected Preferences for Social Comparisons". American Economic Journal: Economic Policy 10, n.º 1 (1 de fevereiro de 2018): 39–76. http://dx.doi.org/10.1257/pol.20150369.

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This paper compares optimal nonlinear income tax policies of welfarist and paternalist governments, where the latter does not respect individual preferences regarding relative consumption. Consistent with previous findings, relative consumption concerns typically induce a welfarist government to increase the marginal tax rates to internalize positional externalities. Remarkably, the optimal marginal tax rules are often very similar in the paternalist case, where such externalities are not taken into account. We identify several cases where the marginal tax rules are indeed identical between the governments. Numerical simulations show that marginal and average tax levels and the overall redistribution are often also similar. (JEL D62, D72, H21, H23, H24)

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Kroft, Kory, Kavan Kucko, Etienne Lehmann e Johannes Schmieder. "Optimal Income Taxation with Unemployment and Wage Responses: A Sufficient Statistics Approach". American Economic Journal: Economic Policy 12, n.º 1 (1 de fevereiro de 2020): 254–92. http://dx.doi.org/10.1257/pol.20180033.

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We derive a sufficient statistics tax formula in a model that incorporates unemployment and endogenous wages to study the shape of the optimal income tax. Key sufficient statistics are the macro employment response to taxation, the micro and macro participation response to taxation, and the wage-moderating effect of tax progressivity. We empirically implement the tax formula by estimating the micro and macro elasticities using policy variation from the United States. Our results suggest that the optimal tax more closely resembles a negative income tax than an earned income tax credit relative to the case where unemployment and wage responses are ignored. (JEL E24, H21, H23, H24, H31, J22, J31)

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Piketty, Thomas, Emmanuel Saez e Stefanie Stantcheva. "Optimal Taxation of Top Labor Incomes: A Tale of Three Elasticities". American Economic Journal: Economic Policy 6, n.º 1 (1 de fevereiro de 2014): 230–71. http://dx.doi.org/10.1257/pol.6.1.230.

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This paper derives optimal top tax rate formulas in a model where top earners respond to taxes through three channels: labor supply, tax avoidance, and compensation bargaining. The optimal top tax rate increases when there are zero-sum compensation-bargaining effects. We present empirical evidence consistent with bargaining effects. Top tax rate cuts are associated with top one percent pretax income shares increases but not higher economic growth. US CEO “pay for luck” is quantitatively more prevalent when top tax rates are low. International CEO pay levels are negatively correlated with top tax rates, even controlling for firms' characteristics and performance. (JEL D31, H21, H24, H26, M12)

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Scheuer, Florian. "Entrepreneurial Taxation with Endogenous Entry". American Economic Journal: Economic Policy 6, n.º 2 (1 de maio de 2014): 126–63. http://dx.doi.org/10.1257/pol.6.2.126.

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I analyze the optimal taxation of profits and labor income under endogenous firm formation. Individuals differ in their skill and cost of setting up a firm, and can become workers or entrepreneurs. A tax system in which profits and labor income are subject to the same schedule uses general equilibrium effects through wages to indirectly redistribute across occupations. Optimal policies can involve low tax rates at the top and distortions of firms' input choices. However, these properties disappear under a differential treatment of profits and labor income. Then, redistribution is achieved directly through taxes and production efficiency is always optimal. (JEL H21, H24, H25, J24, L25, L26)

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Bettelheim, Karl A. "Non-O157 Verotoxin-Producing Escherichia coli: A Problem, Paradox, and Paradigm". Experimental Biology and Medicine 228, n.º 4 (abril de 2003): 333–44. http://dx.doi.org/10.1177/153537020322800402.

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The problems associated with identification and characterization of non-O157 verotoxin-producing Escherichia coli (VTEC) are discussed. The paradox of VTEC is that most reports of human illnesses are associated with serotypes such as O157:H7, O111:H– (nonmotile), O26:H11, and O113:H21, which are rarely found in domestic animals. However, those VTEC serotypes commonly found in domestic animals, especially ruminants, rarely cause human illnesses. When they cause human illnesses, the symptoms are similar to those caused by the serotypes E. coli O157:H7, O111:H–, O26:H11, and O113:H21. The impact of VTEC on human and animal health is also addressed. The VTEC and their toxicity are considered as a paradigm for emerging pathogens. The question on how such pathogens could arise from a basic commensal population is also addressed.

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Chetty, Raj. "Is the Taxable Income Elasticity Sufficient to Calculate Deadweight Loss? The Implications of Evasion and Avoidance". American Economic Journal: Economic Policy 1, n.º 2 (1 de julho de 2009): 31–52. http://dx.doi.org/10.1257/pol.1.2.31.

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Martin Feldstein's (1999) widely used taxable income formula for deadweight loss assumes the marginal social cost of evasion and avoidance equals the tax rate. This condition is likely to be violated in practice for two reasons. First, some of the costs of evasion and avoidance are transfers to other agents. Second, some individuals overestimate the costs of evasion and avoidance. In such situations, excess burden depends on a weighted average of the taxable income and total earned income elasticities, with the weight determined by the resource cost of sheltering income from taxation. This generalized formula implies the efficiency cost of taxing high income individuals is not necessarily large despite evidence that their reported incomes are highly sensitive to marginal tax rates. (JEL H21, H24, H26)

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Bielaszewska, Martina, Marina Fell, Lilo Greune, Rita Prager, Angelika Fruth, Helmut Tschäpe, M. Alexander Schmidt e Helge Karch. "Characterization of Cytolethal Distending Toxin Genes and Expression in Shiga Toxin-Producing Escherichia coli Strains of Non-O157 Serogroups". Infection and Immunity 72, n.º 3 (março de 2004): 1812–16. http://dx.doi.org/10.1128/iai.72.3.1812-1816.2004.

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ABSTRACT We identified cytolethal distending toxin and its gene (cdt) in 17 of 340 non-O157 Shiga toxin-producing Escherichia coli (STEC) strains (serotypes O73:H18, O91:H21, O113:H21, and O153:H18), all of which were eae negative. cdt is either chromosomal and homologous to cdt-V (serotypes O73:H18, O91:H21, and O113:H21) or plasmidborne and identical to cdt-III (serotype O153:H18). Among eae-negative STEC, cdt was associated with disease (P = 0.003).

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Zhang, Qiu Yang, Shu Qi Wang e Lan Wang. "Comparative Study on Wear of Hot-Working Die Steels". Applied Mechanics and Materials 331 (julho de 2013): 559–62. http://dx.doi.org/10.4028/www.scientific.net/amm.331.559.

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The wear behavior and wear mechanism of hot-working die steels H13 and H21 were studied using a pin-on-disc high-temperature wear machine. H21 steel presented higher wear resistance than H13 steel at 25 and 400°C. However the wear rate of H21 steel increased rapidly and was substantially higher than that of H13 steel under a load of 150 N or above at 200°C. Tribo-oxide layer possessing protective effect generated at 200 °C for H13 steel, but appeared at 400 °C for H21 steel with obviously lower amount than that of H13 steel due to relatively high alloy contents. Higher wear resistance of H21 steel is attributed to the undissolved carbides and high thermal strength.

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Batko, Kornelia M., e Andrzej Ślęzak. "Membrane Transport of Nonelectrolyte Solutions in Concentration Polarization Conditions: Hr Form of the Kedem–Katchalsky–Peusner Equations". International Journal of Chemical Engineering 2019 (1 de abril de 2019): 1–10. http://dx.doi.org/10.1155/2019/5629259.

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In this paper, the Kedem–Katchalsky equations in matrix form for nonhomogeneous ternary nonelectrolyte solutions were applied for interpretation of transport through the membrane mounted in horizontal plane. Coefficients Hijr, Hijr, and Hdetr=detHr (for nonhomogeneous solutions), Hij and Hdet=detH (for homogeneous solutions) (i, j ∈ {1, 2, 3}, r = A, B), ψij=HijA−HijB/Hij, and ψdet=HdetA−HdetB/Hdet were calculated on the basis of experimentally determined coefficients (Lp, σ1, σ2ω11, ω22, ω21, ω12, ζ1r, and ζ2r) for glucose in aqueous ethanol solutions and two configurations of the membrane system. From the calculations, it results that the values of coefficients H12r, H13r, H22r, H23r, H32r, H33r, and Hdetr depend nonlinearly on solution concentration as well as on a configuration of membrane system. Besides, the values of coefficients H21r, H12, H21, H22, H33r, and Hdet depend linearly on solution concentration. The value of coefficients H13, H23, and H33 do not depend on solution concentration. The coefficients ψ12, ψ13, ψ22 = ψ23, ψ32 = ψ33, and ψdet depend nonlinearly on solution concentration and for C¯1 ≈ 9.24 mol m−3 are equal to zero. For C¯1 < 9.24 mol m−3, the values of coefficients ψ12 and ψ13 are negative and for C¯1 > 9.23 mol m−3, positive. In contrast, the values of coefficients ψ22 = ψ23, ψ32 = ψ33, and ψdet for C¯1 < 9.24 mol m−3 are positive and for C¯1 > 9.24 mol m−3, negative. For ψ = 0, we can observe nonconvective state, in which concentration Rayleigh number reaches the critical value RC = 1691.09, for ψ<0 is convective state with convection directed straight down and for ψ>0 is convective state with convection directed straight up.

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Steele, Ken, Jason Waterman e Eugene Weinstein. "The oxygen H21 handheld". ACM SIGARCH Computer Architecture News 30, n.º 3 (junho de 2002): 3–4. http://dx.doi.org/10.1145/571666.571668.

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Li, Carmen, Dulmini Nanayakkara Sapugahawatte, Ying Yang, Kam Tak Wong, Norman Wai Sing Lo e Margaret Ip. "Multidrug-Resistant Streptococcus agalactiae Strains Found in Human and Fish with High Penicillin and Cefotaxime Non-Susceptibilities". Microorganisms 8, n.º 7 (16 de julho de 2020): 1055. http://dx.doi.org/10.3390/microorganisms8071055.

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Penicillin non-susceptible Streptococcus agalactiae (PEN-NS GBS) has been increasingly reported, with multidrug-resistant (MDR) GBS documented in Japan. Here we identified two PEN-NS GBS strains during our surveillance studies: one from a patient’s wound and the other from a tilapia. The patient’s GBS (H21) and fish GBS (F49) were serotyped and tested for antibiotic susceptibility. Whole-genome sequencing was performed to find the sequence type, antimicrobial resistance genes, and mutations in penicillin-binding proteins (PBPs) and fluoroquinolone (FQ) resistance genes. H21 and F49 belonged to ST651, serotype Ib, and ST7, serotype Ia, respectively. H21 showed PEN and cefotaxime minimum inhibitory concentrations (MICs) of 2.0 mg/L. F49 showed PEN MIC 0.5 mg/L. H21 was MDR with ermB, lnuB, tetS, ant6-Ia, sat4a, and aph3-III antimicrobial resistance genes observed. Alignment of PBPs showed the combination of PBP1B (A95D) and 2B mutations (V80A, S147A, S160A) in H21 and a novel mutation in F49 at N192S in PBP2B. Alignment of FQ-resistant determinants revealed mutation sites on gyrA, gyrB, and parC and E in H21. To our knowledge, this is the first report of GBS isolates with such high penicillin and cefotaxime MICs. This raises the concern of emergence of MDR and PEN-NS GBS in and beyond healthcare facilities.

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Shen, Songhai, Mariola Mascarenhas, Kris Rahn, James B. Kaper e Mohamed A. Karmal. "Evidence for a Hybrid Genomic Island in Verocytotoxin-Producing Escherichia coli CL3 (Serotype O113:H21) Containing Segments of EDL933 (Serotype O157:H7) O Islands 122 and 48". Infection and Immunity 72, n.º 3 (março de 2004): 1496–503. http://dx.doi.org/10.1128/iai.72.3.1496-1503.2004.

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ABSTRACT Genomic O island 122 (OI-122) of the verocytotoxin-producing Escherichia coli (VTEC) strain EDL933 contains four putative virulence genes, Z4321, Z4326, Z4332, and Z4333. However, strain CL3 (serotype O113:H21) contains only Z4321, not the other three genes. To determine whether Z4321 is part of a different genomic island in CL3, a region of 27,293 bp up- and downstream of Z4321 was sequenced and found to contain elements of two different EDL933 genomic islands (OI-48 and OI-122) and a Yersinia pestis-like hemolysin/adhesin gene cluster. The region contained OI-48 genes Z1635, Z1636, and Z1637 at the left terminus and Z1641, Z1642, Z1643, and Z1644 at the right. The middle portion consisted of OI-48 gene Z1640, which was separated into three fragments by genomic segments including the Y. pestis cluster and EDL933 OI-122 genes Z4322, Z4321, and Z4318. In a PCR investigation of 36 VTEC strains of different serotypes, intact Z1640 was present in strains of serotypes O157:H7, O26:H11, O103:H2, O111:NM, and O145:NM, which are associated with hemolytic uremic syndrome and outbreaks. In contrast, fragmented Z1640 was seen in strains of nonepidemic serotypes, such as O91:H21 and O113:H21, and in animal serotypes that have not been associated with human disease, indicating that Z1640 might be a virulence gene.

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Luck, Shelley N., Luminita Badea, Vicki Bennett-Wood, Roy Robins-Browne e Elizabeth L. Hartland. "Contribution of FliC to Epithelial Cell Invasion by Enterohemorrhagic Escherichia coli O113:H21". Infection and Immunity 74, n.º 12 (18 de setembro de 2006): 6999–7004. http://dx.doi.org/10.1128/iai.00435-06.

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ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O113:H21 can invade epithelial cells. In this study, we found that invasion but not adherence was inhibited by anti-FliCH21 specific antibodies. In addition, deletion of fliCH21 from EHEC O113:H21 resulted in an eightfold decrease in invasion that was restored upon transcomplementation with fliCH21 but not with fliCH6 . These results suggested that FliC plays an important role in the pathogenesis of infections caused by EHEC O113:H21 by allowing bacteria to penetrate the intestinal epithelium.

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Feng, Peter C. H., Sabine Delannoy, David W. Lacher, Luis Fernando dos Santos, Lothar Beutin, Patrick Fach, Marta Rivas, Elizabeth L. Hartland, Adrienne W. Paton e Beatriz E. C. Guth. "Genetic Diversity and Virulence Potential of Shiga Toxin-Producing Escherichia coli O113:H21 Strains Isolated from Clinical, Environmental, and Food Sources". Applied and Environmental Microbiology 80, n.º 15 (23 de maio de 2014): 4757–63. http://dx.doi.org/10.1128/aem.01182-14.

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ABSTRACTShiga toxin-producingEscherichia colistrains of serotype O113:H21 have caused severe human diseases, but they are unusual in that they do not produce adherence factors coded by the locus of enterocyte effacement. Here, a PCR microarray was used to characterize 65 O113:H21 strains isolated from the environment, food, and clinical infections from various countries. In comparison to the pathogenic strains that were implicated in hemolytic-uremic syndrome in Australia, there were no clear differences between the pathogens and the environmental strains with respect to the 41 genetic markers tested. Furthermore, all of the strains carried only Shiga toxin subtypes associated with human infections, suggesting that the environmental strains have the potential to cause disease. Most of the O113:H21 strains were closely related and belonged in the same clonal group (ST-223), but CRISPR analysis showed a great degree of genetic diversity among the O113:H21 strains.

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Eden, Maya. "Excessive Financing Costs in a Representative Agent Framework". American Economic Journal: Macroeconomics 8, n.º 2 (1 de abril de 2016): 215–37. http://dx.doi.org/10.1257/mac.20140147.

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This paper highlights a pecuniary externality that results in excessive financing costs. Firms borrow to finance purchases of an inelastically supplied input, bidding up its price. Since higher input prices necessitate more debt obligations, this leads to an increase in intermediation costs. A quantitative interpretation of the model suggests that it is optimal to tax financial intermediation by increasing the borrowing rate by 3 percentage points. (JEL E13, E44, G21, G32, H21, H25)

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Tokhi, A. Mohammad, J. S. M. Peiris, S. M. Scotland, G. A. Willshaw, H. R. Smith e T. Cheasty. "A longitudinal study of Vero cytotoxin producing Escherichia coli in cattle calves in Sri Lanka". Epidemiology and Infection 110, n.º 2 (abril de 1993): 197–208. http://dx.doi.org/10.1017/s0950268800068114.

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SUMMARYTwo cohorts of 10 and 16 calves were followed at weekly or fortnightly intervals from 4–28 and 1–9 weeks respectively to determine whether natural infection by Vero cytotoxin (VT) producing Escherichia coli (VTEC) occurred. Ninety-one of 171 (53%) faecal specimens were VTEC positive and 20–80% of animals at any given time excreted VTEC. Of 104 VTEC strains studied further, 6 different serogroups (O 22.H16; O 25.H5; O 49.H−; O 86.H26; O 88.H25; O 153.H12) and an untypable strain (O ?.H21) were identified. All strains belonging to the same serotype had identical profiles of reactivity with DNA probes to toxins VT1 or 2, LT1 or iI and a probe (CVD419) derived from a plasmid carried by enterohaemorrhagic Escherichia coli O 157.H7. Four of these serotypes were found in the faecal flora of the calves, taken as a group, throughout the 4-month study period. Sixty percent of the strains hybridized with the probe for VT1, 4% with the probe for VT2, and 36% with both probes. Faecal VTEC were significantly associated with overt diarrhoeal illness in animals < 10 weeks of age, but no characteristic profile of markers (serotype or hybridization pattern) in E. coli isolates was associated with diarrhoea. A serological response to VTl was detected in some animals, but faecal VT1 VTEC excretion persisted in spite of seroconversion. VTl seroconversion was not associated with diarrhoea. A serological response to VT2 was not detected even in those animals excreting VT2 VTEC in the faeces.

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Anderson, Kirk M., e Marion O. Harris. "Susceptibility of North Dakota Hessian Fly (Diptera: Cecidomyiidae) to 31 H Genes Mediating Wheat Resistance". Journal of Economic Entomology 112, n.º 5 (18 de maio de 2019): 2398–406. http://dx.doi.org/10.1093/jee/toz121.

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Abstract The agricultural landscape of North Dakota is changing. Corn and soybean are now commonplace, but once were rare. Spring sown wheat Triticum aestivum L. and durum wheat Triticum turgidum spp. durum continue to be dominant, but more winter-sown wheat is expected in the future. The presence of wheat in the landscape throughout much of the year will benefit populations of the Hessian fly, Mayetiola destructor (Say), which occurs throughout the state, sometimes in large numbers. Hessian fly is unusual among crop pests for which resources for plant resistance are well developed. On wheat genotypes expressing a single effective H resistance gene, 100% of larvae die before exhibiting any growth. Over 35 H genes in the public domain are available for crossing into elite cultivars. We explored the effectiveness of 31 Hessian fly resistance genes for a North Dakota Hessian fly population. Six genes—H4, H15, H21, H23, H26, and H29—caused 100% larval mortality. Seven others caused at least 80% mortality. Experimental data were used to address three additional questions. Do adult females avoid laying eggs on plants that will kill their offspring: Are neonate larvae able to detect resistance that will end up killing them? Do all 31 genes confer equal protection against larval-induced growth deficits? North Dakota wheat breeders have the necessary tools to create highly resistant wheat cultivars. So far, H genes have been deployed singly in cultivars. Advances in plant breeding will enable gene stacking, a more durable strategy over time.

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Treier, Andrea, Roger Stephan, Marc J. A. Stevens, Nicole Cernela e Magdalena Nüesch-Inderbinen. "High Occurrence of Shiga Toxin-Producing Escherichia coli in Raw Meat-Based Diets for Companion Animals—A Public Health Issue". Microorganisms 9, n.º 8 (21 de julho de 2021): 1556. http://dx.doi.org/10.3390/microorganisms9081556.

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Feeding pets raw meat-based diets (RMBDs) is becoming increasingly popular but comes with a risk of pathogenic bacteria, including Shiga toxin-producing Escherichia coli (STEC). In humans, STEC may cause gastrointestinal illnesses, including diarrhea, hemorrhagic colitis (HC), and the hemolytic uremic syndrome (HUS). The aim of this study was to evaluate commercially available RMBDs with regard to the occurrence of STEC. Of 59 RMBD samples, 59% tested positive by real-time PCR for the presence of Shiga toxin genes stx1 and/or stx2. STECs were recovered from 41% of the 59 samples, and strains were subjected to serotyping and virulence gene profiling, using whole genome sequencing (WGS)-based methods. Of 28 strains, 29% carried stx2a or stx2d, which are linked to STEC with high pathogenic potential. Twenty different serotypes were identified, including STEC O26:H11, O91:H10, O91:H14, O145:H28, O146:H21, and O146:H28, which are within the most common non-O157 serogroups associated with human STEC-related illnesses worldwide. Considering the low infectious dose and potential severity of disease manifestations, the high occurrence of STEC in RMBDs poses an important health risk for persons handling raw pet food and persons with close contact to pets fed on RMBDs, and is of concern in the field of public health.

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dos Santos, Luis Fernando, Kinue Irino, Tânia Mara Ibelli Vaz e Beatriz Ernestina Cabilio Guth. "Set of virulence genes and genetic relatedness of O113 : H21 Escherichia coli strains isolated from the animal reservoir and human infections in Brazil". Journal of Medical Microbiology 59, n.º 6 (1 de junho de 2010): 634–40. http://dx.doi.org/10.1099/jmm.0.015263-0.

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Escherichia coli strains of serotype O113 : H21 are commonly described as belonging to a Shiga toxin (Stx)-producing E. coli (STEC) pathotype worldwide. Albeit this STEC serotype is frequently identified among cattle and other domestic animals, to the best of our knowledge no human infections associated with STEC O113 : H21 have been registered in Brazil to date. Here, we report the virulence profile and genetic relatedness of a collection of O113 : H21 E. coli strains mainly isolated from the animal reservoir aimed at determining their potential as human pathogens. The strains from the animal reservoir (n=34) were all classified as STEC, whereas the few isolates recovered so far from human diarrhoea (n=3) lacked stx genes. Among the STEC, the stx 2d-activatable gene was identified in 85 % of the strains that also carried lpfA O113, iha, saa, ehxA, subAB, astA, cdt-V, espP, espI and epeA; the human strains harboured only lpfA O113, iha and astA. All the strains except one, isolated from cattle, were genetically classified as phylogenetic group B1. High mass plasmids were observed in 25 isolates, but only in the STEC group were these plasmids confirmed as the STEC O113 megaplasmid (pO113). Many closely related subgroups (more than 80 % similarity) were identified by PFGE, with human isolates clustering in a subgroup separate from most of the animal isolates. In conclusion, potentially pathogenic O113 : H21 STEC isolates carrying virulence markers in common with O113 : H21 clones associated with haemolytic uraemic syndrome cases in other regions were demonstrated to occur in the natural reservoir in our settings, and therefore the risk represented by them to public health should be carefully monitored.

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Beutin, Lothar, Angelika Miko, Gladys Krause, Karin Pries, Sabine Haby, Katja Steege e Nadine Albrecht. "Identification of Human-Pathogenic Strains of Shiga Toxin-Producing Escherichia coli from Food by a Combination of Serotyping and Molecular Typing of Shiga Toxin Genes". Applied and Environmental Microbiology 73, n.º 15 (8 de junho de 2007): 4769–75. http://dx.doi.org/10.1128/aem.00873-07.

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ABSTRACT We examined 219 Shiga toxin-producing Escherichia coli (STEC) strains from meat, milk, and cheese samples collected in Germany between 2005 and 2006. All strains were investigated for their serotypes and for genetic variants of Shiga toxins 1 and 2 (Stx1 and Stx2). stx 1 or variant genes were detected in 88 (40.2%) strains and stx 2 and variants in 177 (80.8%) strains. Typing of stx genes was performed by stx-specific PCRs and by analysis of restriction fragment length polymorphisms (RFLP) of PCR products. Major genotypes of the Stx1 (stx 1, stx 1c, and stx 1d) and the Stx2 (stx 2, stx 2d, stx 2-O118, stx 2e, and stx 2g) families were detected, and multiple types of stx genes coexisted frequently in STEC strains. Only 1.8% of the STEC strains from food belonged to the classical enterohemorrhagic E. coli (EHEC) types O26:H11, O103:H2, and O157:H7, and only 5.0% of the STEC strains from food were positive for the eae gene, which is a virulence trait of classical EHEC. In contrast, 95 (43.4%) of the food-borne STEC strains carried stx 2 and/or mucus-activatable stx 2d genes, an indicator for potential high virulence of STEC for humans. Most of these strains belonged to serotypes associated with severe illness in humans, such as O22:H8, O91:H21, O113:H21, O174:H2, and O174:H21. stx 2 and stx 2d STEC strains were found frequently in milk and beef products. Other stx types were associated more frequently with pork (stx 2e), lamb, and wildlife meat (stx 1c). The combination of serotyping and stx genotyping was found useful for identification and for assignment of food-borne STEC to groups with potential lower and higher levels of virulence for humans.

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Feng, Peter, Sabine Delannoy, David W. Lacher, Joseph M. Bosilevac e Patrick Fach. "Characterization and Virulence Potential of Serogroup O113 Shiga Toxin–Producing Escherichia coli Strains Isolated from Beef and Cattle in the United States". Journal of Food Protection 80, n.º 3 (15 de fevereiro de 2017): 383–91. http://dx.doi.org/10.4315/0362-028x.jfp-16-325.

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ABSTRACT Shiga toxin–producing Escherichia coli (STEC) of serotype O113:H21 have caused severe diseases but are unusual in that they do not produce the intimin protein required for adherence to intestinal epithelial cells. Strains of serogroup O113 are one of the most common STEC found in ground beef and beef products in the United States, but their virulence potential is unknown. We used a microarray to characterize 65 O113 strains isolated in the United States from ground beef, beef trim, cattle feces, and fresh spinach. Most were O113:H21 strains, but there were also nine strains of O113:H4 serotype. Although strains within the same serotype had similar profiles for the genes that were tested on the array, the profiles were distinct between the two serotypes, and the strains belonged to different clonal groups. Analysis by clustered regularly interspaced short palindromic repeat analysis showed that O113:H4 strains are conserved genetically, but the O113:H21 strains showed considerable polymorphism and genetic diversity. In comparison to the O113:H21 strains from Australia that were implicated in severe disease, the U.S. isolates showed similar genetic profiles to the known pathogens from Australia, suggesting that these may also have the potential to cause infections.

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Yurko, Amy, Christine Cheng e Marc Morris. "A New Examination of an Old Question: Is it Constitutional to Tax Marriage?" ATA Journal of Legal Tax Research 18, n.º 1 (1 de março de 2020): 19–41. http://dx.doi.org/10.2308/jltr-19-006.

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ABSTRACT In 2015, the U.S. Supreme Court recognized the fundamental right to marry in Obergefell v. Hodges. At the same time, the tax code commonly taxes married couples at a higher effective tax rate than their unmarried counterparts. We examine the constitutionality of the penalty on marriage, critically reviewing the justification for the penalty accepted in Johnson v. U.S. in 1976. Our evaluation of the tax system suggests that the marriage tax penalty violates due process and may violate equal protection and the First Amendment for some taxpayers. JEL Classifications: D15; H21; H24; H31; K34.

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Bumunang, Emmanuel W., Collins N. Ateba, Kim Stanford, Yan D. Niu, Y. Wang e Tim A. McAllister. "Activity of Bacteriophage and Complex Tannins against Biofilm-Forming Shiga Toxin-Producing Escherichia coli from Canada and South Africa". Antibiotics 9, n.º 5 (15 de maio de 2020): 257. http://dx.doi.org/10.3390/antibiotics9050257.

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Bacteriophages, natural killers of bacteria, and plant secondary metabolites, such as condensed tannins, are potential agents for the control of foodborne pathogens. The first objective of this study evaluated the efficacy of a bacteriophage SA21RB in reducing pre-formed biofilms on stainless-steel produced by two Shiga toxin-producing Escherichia coli (STEC) strains, one from South Africa and the other from Canada. The second objective examined the anti-bacterial and anti-biofilm activity of condensed tannin (CT) from purple prairie clover and phlorotannins (PT) from brown seaweed against these strains. For 24-h-old biofilms, (O113:H21; 6.2 log10 colony-forming units per square centimeter (CFU/cm2) and O154:H10; 5.4 log10 CFU/cm2), 3 h of exposure to phage (1013 plaque-forming units per milliliter (PFU/mL)) reduced (p ≤ 0.05) the number of viable cells attached to stainless-steel coupons by 2.5 and 2.1 log10 CFU/cm2 for O113:H21 and O154:H10, respectively. However, as biofilms matured, the ability of phage to control biofilm formation declined. In biofilms formed for 72 h (O113:H21; 5.4 log10 CFU/cm2 and O154:H10; 7 log10 CFU/cm2), reductions after the same duration of phage treatment were only 0.9 and 1.3 log10 CFU/cm2 for O113:H21 and O154:H10, respectively. Initial screening of CT and PT for anti-bacterial activity by a microplate assay indicated that both STEC strains were less sensitive (p ≤ 0.05) to CT than PT over a concentration range of 25–400 µg/mL. Based on the lower activity of CT (25–400 µg/mL), they were not further examined. Accordingly, PT (50 µg/mL) inhibited (p ≤ 0.05) biofilm formation for up to 24 h of incubation at 22 °C, but this inhibition progressively declined over 72 h for both O154:H10 and O113:H21. Scanning electron microscopy revealed that both SA21RB and PT eliminated 24 h biofilms, but that both strains were able to adhere and form biofilms on stainless-steel coupons at longer incubation times. These findings revealed that phage SA21RB is more effective at disrupting 24 than 72 h biofilms and that PT were able to inhibit biofilm formation of both E. coli O154:H10 and O113:H21 for up to 24 h.

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Nurbanasari, Meilinda, Panos Tsakiropoulos e Eric J. Palmiere. "Solidification Behaviour of a H21 Tool Steel". Advanced Materials Research 1043 (outubro de 2014): 159–64. http://dx.doi.org/10.4028/www.scientific.net/amr.1043.159.

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Solidification behaviour of a H21 tool steel has been studied. The aim of this work is to give better understanding of the as cast microstructure of the steel. The investigated H21 tool steel was made using induction vacuum furnace with air cooling. The microstructure observation was carried out using optical and electron microscopy. X ray diffraction and nanohardness were also used for phase and carbide identification. The results show that the as cast microstructure consisted of ferrite and coarse primary M6C carbide that is rich in tungsten. The nanohardness of ferrite was 5.1 ± 0.3 GPa and there was inhomogeneity in as cast microstructure, which is indicated by the nanohardness values from bulk grain to grain boundary precipitates varied between 4.8 to 8.9 GPa. Comparison between prediction and experimental results shows that the calculated phase diagram was not in agreement with the solidification microstructure of the H21 tool steel.

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Frankel, Alexander. "Taxation of Couples under Assortative Mating". American Economic Journal: Economic Policy 6, n.º 3 (1 de agosto de 2014): 155–77. http://dx.doi.org/10.1257/pol.6.3.155.

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I present a simple and tractable model of the optimal taxation of married couples, working off of the multidimensional screening framework of Armstrong and Rochet (1999). In particular, I study how the tax code varies with the degree of assortative mating. One result is that the “negative jointness” of marginal tax rates found in Kleven, Kreiner, and Saez (2007, 2009) for couples with uncorrelated earnings should be attenuated in the presence of assortative mating. When mating is sufficiently assortative, the optimal tax schedule is separable: an individual's taxes do not depend on his or her spouse's income. (JEL D82, H21, H24, J12)

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Li, Shanjun, Joshua Linn e Erich Muehlegger. "Gasoline Taxes and Consumer Behavior". American Economic Journal: Economic Policy 6, n.º 4 (1 de novembro de 2014): 302–42. http://dx.doi.org/10.1257/pol.6.4.302.

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Gasoline taxes can be employed to correct externalities from automobile use and to raise government revenue. Our understanding of the optimal gasoline tax and the efficacy of existing taxes is largely based on empirical analysis of consumer responses to gasoline price changes. In this paper, we examine directly how gasoline taxes affect gasoline consumption as distinct from tax-inclusive retail gasoline prices. We find robust evidence that consumers respond more strongly to gasoline tax changes under a variety of model specifications. We discuss two potential reasons for our main findings as well as their implications. (JEL D12, H21, H25, H31, L71, Q35)

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Scheuer, Florian, e Alexander Wolitzky. "Capital Taxation under Political Constraints". American Economic Review 106, n.º 8 (1 de agosto de 2016): 2304–28. http://dx.doi.org/10.1257/aer.20141081.

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This paper studies optimal dynamic tax policy under the threat of political reform. A policy will be reformed ex post if a large enough coalition of citizens supports reform; thus, sustainable policies are those that will continue to attract enough political support in the future. We find that optimal marginal capital taxes are either progressive or U-shaped, so that savings are subsidized for the poor and/or the middle class but are taxed for the rich. U-shaped capital taxes always emerge when individuals' political behavior is purely determined by economic motives. (JEL D12, D14, D31, D72, H21, H25)

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Cherchye, Laurens, Thomas Demuynck, Bram De Rock e Frederic Vermeulen. "Household Consumption When the Marriage Is Stable". American Economic Review 107, n.º 6 (1 de junho de 2017): 1507–34. http://dx.doi.org/10.1257/aer.20151413.

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We develop a novel framework to analyze the structural implications of the marriage market for household consumption. We define a revealed preference characterization of efficient household consumption when the marriage is stable. We characterize stable marriage with intrahousehold (consumption) transfers but without assuming transferable utility. Our revealed preference characterization generates testable conditions even with a single observation per household and heterogeneous individual preferences across households. The characterization also allows for identifying the intrahousehold decision structure (including the sharing rule) under the same minimalistic assumptions. An application to Dutch household data illustrates the usefulness of our theoretical results. (JEL D60, D63, H21, H23, I38)

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Lombardi, Gabrielle Maria Romeiro, Patricia Cardoso Andrade Navegantes, Carlos Henrique Pereira, Jales Mendes Oliveira Fonseca, Rafael Augusto da Costa Parrella, Fernanda Maria Rodrigues Castro, Mara Jane da Rocha, Daniela Oliveira Ornelas, Adriano Teodoro Bruzi e José Airton Rodrigues Nunes. "Heterosis in sweet sorghum". Pesquisa Agropecuária Brasileira 53, n.º 5 (maio de 2018): 593–601. http://dx.doi.org/10.1590/s0100-204x2018000500008.

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Abstract: The objective of this work was to evaluate the potential per se of male-sterile and fertility-restorer lines of sweet sorghum (Sorghum bicolor), as well as to detail the heterosis manifested for some traits directly or indirectly related to ethanol production, accumulation rate, and predictability. Evaluations were performed for 20 genotypes, of which 4 are fertility-restorer lines (R), 3 are male-sterile lines (A), and 12 are experimental hybrids (H) resulting from the partial diallel cross between lines A and R, besides a commercial hybrid CV198 used as a check, in four harvest seasons. The experiments were carried out in the municipalities of Lavras and Sete Lagoas, in the state of Minas Gerais, Brazil. The measured traits were plant height, green mass production, juice extraction, total soluble solids content, and megagrams of Brix per hectare. The male-sterile A1 and the fertility-restorer R1 and R3 lines show the best potential per se, considering all traits and their accumulation rate and predictability over harvest times. Heterosis is significant for all traits. The H11, H13, H14, H21, H22, and H33 hybrids are promising because of their better performance per se and higher heterosis.

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Blanco Crivelli, Ximena, María Paz Bonino, Mariana Soledad Sanin, Juan Facundo Petrina, Vilma Noelia Disalvo, Rosana Massa, Elizabeth Miliwebsky, Armando Navarro, Isabel Chinen e Adriana Bentancor. "Potential Zoonotic Pathovars of Diarrheagenic Escherichia coli Detected in Lambs for Human Consumption from Tierra del Fuego, Argentina". Microorganisms 9, n.º 8 (11 de agosto de 2021): 1710. http://dx.doi.org/10.3390/microorganisms9081710.

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Diarrheagenic Escherichia coli (DEC) pathovars impact childhood health. The southern region of Argentina shows the highest incidence of hemolytic uremic syndrome (HUS) in children of the country. The big island of Tierra del Fuego (TDF) in Argentina registered an incidence of five cases/100,000 inhabitants of HUS in 2019. This work aimed to establish the prevalence of STEC, EPEC, and EAEC in lambs slaughtered in abattoirs from TDF as well as to characterize the phenotypes and the genotypes of the isolated pathogens. The prevalence was 26.6% for stx+, 5.7% for eae+, and 0.27% for aagR+/aaiC+. Twelve STEC isolates were obtained and belonged to the following serotypes: O70:HNT, O81:H21, O81:HNT, O102:H6, O128ab:H2, O174:H8, and O174:HNT. Their genotypic profiles were stx1c (2), stx1c/ehxA (3), stx2b/ehxA (1), stx1c/stx2b (2), and stx1c/stx2/ehxA (4). Six EPEC isolates were obtained and corresponded to five serotypes: O2:H40, O32:H8, O56:H6, O108:H21, and O177:H25. All the EPEC isolates were bfpA- and two were ehxA+. By XbaI-PFGE of 17 isolates, two clusters were identified. By antimicrobial susceptibility tests, 8/12 STEC and 5/6 EPEC were resistant to at least one antibiotic. This work provides new data to understand the ecology of DEC in TDF and confirms that ovine are an important carrier of these pathogens in the region.

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Luck, Shelley N., Vicki Bennett-Wood, Rachael Poon, Roy M. Robins-Browne e Elizabeth L. Hartland. "Invasion of Epithelial Cells by Locus of Enterocyte Effacement-Negative Enterohemorrhagic Escherichia coli". Infection and Immunity 73, n.º 5 (maio de 2005): 3063–71. http://dx.doi.org/10.1128/iai.73.5.3063-3071.2005.

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ABSTRACT The majority of enterohemorrhagic Escherichia coli (EHEC) strains associated with severe disease carry the locus of enterocyte effacement (LEE) pathogenicity island, which encodes the ability to induce attaching and effacing lesions on the host intestinal mucosa. While LEE is essential for colonization of the host in these pathogens, strains of EHEC that do not carry LEE are regularly isolated from patients with severe disease, although little is known about the way these organisms interact with the host epithelium. In this study, we compared the adherence properties of clinical isolates of LEE-negative EHEC with those of LEE-positive EHEC O157:H7. Transmission electron microscopy revealed that LEE-negative EHEC O113:H21 was internalized by Chinese hamster ovary (CHO-K1) epithelial cells and that intracellular bacteria were located within a membrane-bound vacuole. In contrast, EHEC O157:H7 remained extracellular and intimately attached to the epithelial cell surface. Quantitative gentamicin protection assays confirmed that EHEC O113:H21 was invasive and also showed that several other serogroups of LEE-negative EHEC were internalized by CHO-K1 cells. Invasion by EHEC O113:H21 was significantly reduced in the presence of the cytoskeletal inhibitors cytochalasin D and colchicine and the pan-Rho GTPase inhibitor compactin, whereas the tyrosine kinase inhibitor genistein had no significant impact on bacterial invasion. In addition, we found that EHEC O113:H21 was invasive for the human colonic cell lines HCT-8 and Caco-2. Overall these studies suggest that isolates of LEE-negative EHEC may employ a mechanism of host cell invasion to colonize the intestinal mucosa.

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Philippon, Thomas. "Financiers versus Engineers: Should the Financial Sector be Taxed or Subsidized?" American Economic Journal: Macroeconomics 2, n.º 3 (1 de julho de 2010): 158–82. http://dx.doi.org/10.1257/mac.2.3.158.

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I study the allocation of human capital in an economy with production externalities, financial constraints, and career choices. Agents choose to become entrepreneurs, workers, or financiers. Entrepreneurship has positive externalities but requires the services of financiers. In the second best solution, the financial sector should be taxed in exactly the same way as the nonfinancial sector. When direct subsidies to investment and scientific education are not feasible, subsidizing the financial sector increases growth if externalities are driven by physical capital as in Paul M. Romer (1986), and decreases growth if externalities are driven by human capital as in Robert E. Lucas, Jr. (1988). (JEL E44, H21, H25, L26, O41)

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Karabarbounis, Marios. "A Road Map for Efficiently Taxing Heterogeneous Agents". American Economic Journal: Macroeconomics 8, n.º 2 (1 de abril de 2016): 182–214. http://dx.doi.org/10.1257/mac.20140274.

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This paper characterizes optimal labor income taxes that depend on age, household assets, and filing status (one or two earners) within a life-cycle model with heterogeneous, two-member households. The key innovation is a labor supply elasticity that varies endogenously among households. I find that tax distortions should be hump shaped in age, decrease in household assets, and be lower for joint relative to single filers. Age and assets act as complements within the optimal tax policy. Overall, a tax system using all three tags can increase consumption up to 6.4 percent and welfare up to 1.5 percent. (JEL D14, D91, H21, H24, J22, J31)

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Bilbiie, Florin O., Fabio Ghironi e Marc J. Melitz. "Monopoly Power and Endogenous Product Variety: Distortions and Remedies". American Economic Journal: Macroeconomics 11, n.º 4 (1 de outubro de 2019): 140–74. http://dx.doi.org/10.1257/mac.20170303.

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The inefficiencies related to endogenous product creation and variety under monopolistic competition are two-fold: one static—the mis-alignment between consumers and producers regarding the value of a new variety; and one dynamic—time variation in markups. When production factors (labor and physical capital ) are elastic and traded in competitive markets, further distortions appear. Appropriate taxation schemes can restore optimality if they preserve entry incentives. Quantitatively, the welfare costs of each distortion by itself amounts to 2 to 5 percent of consumption. But their overall cost when jointly present is greatly magnified, and generates up to a 25 percent welfare loss. (JEL D21, D43, H21, H25, H32, L13)

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