一株致猪胃溃疡大肠杆菌的分离鉴定

四川某猪场暴发保育猪与育肥猪水样腹泻,病理剖解可见胃黏膜大面积脱落、胃溃疡等症状,采集病死猪扁桃体与肠系膜淋巴结进行病毒检测;以肠内容物做寄生虫卵检测;选取其中一代表病例做细菌分离,经小鼠致死试验、仔猪回归试验确定病原菌,并对病原菌进行了形态学观察、生化鉴定、16SrDNA序列分析及药敏试验。结果显示,猪瘟病毒、伪狂犬病病毒等的检测结果为阴性;无寄生虫感染;从十二指肠内容物中分离到1株疑似致病性大肠杆菌,并命名为SCDC-1。用SCDC-1株人工感染健康仔猪成功复制出水样腹泻、胃溃疡病例。对SCDC-1株进行16SrDNA克隆测序,并与GenBank中的8株肠杆菌科和4株巴氏杆菌科菌株的16S基因进行同源性分析,发现SCDC-1株与大肠杆菌16S基因的相似性高达99.5%～99.9%。药敏试验结果显示,该病原菌仅对头孢曲松钠、头孢吡肟、丁胺卡那霉素敏感。试验结果证实,引起此次保育猪与育肥猪胃溃疡的主要病原为致病性大肠杆菌。     

Doubling Down: Inequality in Responsiveness and the Policy Preferences of Elected Officials

Is bias in responsiveness to constituents conditional on the policy preferences of elected officials? The scholarly conventional wisdom is that constituency groups who do not receive policy representation still obtain some level of responsiveness by legislators outside of the policy realm. In contrast, we present a theory of preference‐induced responsiveness bias where constituency responsiveness by legislators is associated with legislator policy preferences. Elected officials who favor laws that could disproportionately impact minority groups are also less likely to engage in nonpolicy responsiveness to minority groups. We conducted a field experiment in 28 US legislative chambers. Legislators were randomly assigned to receive messages from Latino and white constituents. If legislators supported voter identification laws, Latino constituents were less likely to receive constituency communications from their legislators. There are significant implications regarding fairness in the democratic process when elected officials fail to represent disadvantaged constituency groups in both policy and nonpolicy realms.     

DOES IMPRISONMENT ALTER THE LIFE COURSE? EVIDENCE ON CRIME AND EMPLOYMENT FROM A NATURAL EXPERIMENT

Ex‐prisoners consistently manifest high rates of criminal recidivism and unemployment. Existing explanations for these poor outcomes emphasize the stigmatizing effects of imprisonment on prisoners seeking postrelease employment as well as the deleterious effects of imprisonment on prisoners’ attitudes and capabilities. However, these explanations must be distinguished from selection effects in the criminal sentencing process, which also could explain some or all of these poor outcomes. To distinguish between criminogenic and selection explanations for ex‐prisoners’ postrelease experience, I analyze data from a natural experiment in which criminal cases were assigned randomly to judges with sizable sentencing disparities. Using these exogenous sentencing disparities, I produce unbiased estimates of the causal effects of imprisonment on the life course. The results of this analysis suggest that selection effects could be sufficiently large to account for prisoners’ poor postrelease outcomes because judges with large sentencing disparities in their use of imprisonment had similarly high caseload unemployment and criminal recidivism rates.     

In search of enduring information effects: Evidence from a ten-week panel experiment

The extent to which the electorate uses issue information to update their candidate evaluations over the course of political campaigns has often raised questions about citizen competence. Using a ten-week panel experiment designed to capture the low-information context of most congressional races this study contributes to our understanding of when and by what processes issue information produces enduring effects. Findings reveal that when voters need to assess an ideologically moderate candidate, they rely less on partisan cues but instead of storing issue information in long-term memory – either via a memory-based or on-line process – considerations in short-term memory remained one of the most powerful predictors of candidate evaluation, particularly when new issue information deviated from partisan norms.     

How best to open up local democracy? A randomised experiment to encourage contested elections and greater representativeness in English parish councils

Interventions aimed at increasing the supply and representativeness of elected officials range from facilitative to the formally authorised. This paper reports on a field experiment aimed at testing the effect of facilitative approaches at the local level based on a collaboration between parish councils and the research team. We randomly allocated 818 parish council clerks across five counties in Southern England, either to receive information and the opportunity for member training for recruitment, or not to receive this contact. We investigated the effect of this intervention on political recruitment. Despite evidence of an effect on use of social media, our results suggest that there are significant institutional and structural barriers to participation in local politics that cannot easily be overcome using facilitative measures.     

Are Poor Voters Indifferent to Whether Elected Leaders Are Criminal or Corrupt? A Vignette Experiment in Rural India

Although in theory elections are supposed to prevent criminal or venal candidates from winning or retaining office, in practice voters frequently elect and reelect such candidates. This surprising pattern is sometimes explained by reference to voters’ underlying preferences, which are thought to favor criminal or corrupt candidates because of the patronage they provide. This article tests this hypothesis using 2010 data from the Indian state of Uttar Pradesh, where one in four representatives in the state legislature have a serious criminal record and where political corruption is widespread. Contrary to the voter preference hypothesis, voters presented with vignettes that randomly vary the attributes of competing legislative candidates for local, state, and national office become much less likely to express a preference for candidates who are alleged to be criminal or corrupt. Moreover, voters’ education status, ethnicity, and political knowledge are unrelated to their distaste for criminal and venal candidates. The results imply that the electoral performance of candidates who face serious allegations likely reflects factors other than voters’ preferences for patronage, such as limited information about candidate characteristics or the absence of credible alternative candidates with clean records.     

How Much Disagreement is Good for Democratic Deliberation?

The ideal of deliberation requires that citizens engage in reasonable discussion despite disagreements. In practice, if their experience is to match this normative ideal, participants in an actual deliberation should prefer moderate disagreement to conflict-free discussion within homogeneous groups, and to conflict-driven discussion where differences are intractable. This article proposes a research design and methods for assessing the quality of a deliberative event based on the perceptions of the participants themselves. In a structured deliberative event, over 2,000 individuals were assigned to small groups composed of about 10 persons of varying levels of ideological difference to discuss health care reform in California. We find that participants experience higher satisfaction with deliberation under moderate ideological difference than when they are in homogeneous or in highly disparate groups. That moderate disagreement induces optimal deliberation is consistent with normative expectations and empirically demonstrates the deliberative quality of this event.     

Mobilizing party activism: A field experiment with party members and sympathizers

Electoral mobilization and persuasion are often characterized as two-stage processes, where parties activate their core supporters, who then mobilize and persuade larger shares of the electorate. While there is a lot of research on the second stage of this process, the mobilization and persuasion of the wider electorate by party activists, there is little causally identified evidence on whether party elites can encourage campaign activism among party members and sympathizers. To address this question, we conducted a randomized field experiment in cooperation with the Swiss Social Democratic Party in the context of the 2015 cantonal elections in Ticino. The experiment consisted of the randomized administration of telephone calls to members and strong supporters of the party, while their self-reported campaign activism and attitudes towards the campaign were measured in a two-wave online panel survey. Against expectations, we record null effects on various measures of campaign activism, including on the mobilization of relatives, and friends. The results raise questions about omitted variable bias in observational studies of party activism that consistently report large positive effects of party contact on the campaign activism of members and sympathizers.     

Long‐Run Labor Market Effects of the Job Corps Program: Evidence from a Nationally Representative Experiment

Job Corps is the nation's largest and most comprehensive career technical training and education program for at‐risk youth ages 16 to 24. Using the sample from a large‐scale experiment of the program from the mid‐1990s, this article uses tax data through 2015 (20 years later) to examine long‐term labor market impacts. The study finds some long‐term beneficial effects for the older students, with employment gains of 4 percentage points, 40 percent reductions in disability benefit receipt, and 10 percent increases in tax filing rates in 2015. For these students, program benefits exceeded program costs from the social perspective. This study is the first to establish that a national program for disconnected youth can produce long‐term labor market gains, and can be a positive investment made for society. The results suggest that intensive, comprehensive services that focus on developing both cognitive and noncognitive skills are important for improving labor market prospects for this population.     

The impact of after‐school programs on the routine activities of middle‐school students: Results from a randomized,controlled trial*

Research Summary Unsupervised after‐school time for adolescents is a concern for parents and policymakers alike. Evidence linking unsupervised adolescent socializing to problem behavior outcomes heightens this concern among criminologists. Routine activities theory suggests that, when youth peer groups congregate away from adult authority, both opportunity for and motivation to engage in deviant acts increase. After‐school programs are a possible solution to unsupervised teen socializing during afternoon hours and are much in demand. However, empirical research has yet to test the relationship between the availability of after‐school programs and youth routine activities. This study presents evidence from a multisite, randomized, controlled trial of an after‐school program for middle‐school students in an urban school district. Policy Implications Youth in the treatment group engaged in less unsupervised socializing after school than youth in the control group but not as much less as would be expected if the after‐school program was providing consistent supervision to youth who would otherwise be unsupervised. Additional analyses examined why the influence of the after‐school program was not more pronounced. We found that, although program attendance was related to decreases in unsupervised socializing, the program did not attract many delinquency‐prone youths who were unsupervised, which suggests that the students most in need of the program did not benefit. Furthermore, data obtained from a mid‐year activity survey revealed that youth in the study were highly engaged in a variety of after‐school activities. The addition of the after‐school program into the mixture of available activities had little effect on the frequency with which students participated in organized activities after school.