Antibiotic susceptibilities of Pseudomonas aeruginosa isolates derived from patients with cystic fibrosis under aerobic, anaerobic, and biofilm conditions

Recent studies have determined that Pseudomonas aeruginosa can live in a biofilm mode within hypoxic mucus in the airways of patients with cystic fibrosis (CF). P. aeruginosa grown under anaerobic and biofilm conditions may better approximate in vivo growth conditions in the CF airways, and combination antibiotic susceptibility testing of anaerobically and biofilm-grown isolates may be more relevant than traditional susceptibility testing under planktonic aerobic conditions. We tested 16 multidrug-resistant isolates of P. aeruginosa derived from CF patients using multiple combination bactericidal testing to compare the efficacies of double and triple antibiotic combinations against the isolates grown under traditional aerobic planktonic conditions, in planktonic anaerobic conditions, and in biofilm mode. Both anaerobically grown and biofilm-grown bacteria were significantly less susceptible (P < 0.01) to single and combination antibiotics than corresponding aerobic planktonically grown isolates. Furthermore, the antibiotic combinations that were bactericidal under anaerobic conditions were often different from those that were bactericidal against the same organisms grown as biofilms. The most effective combinations under all conditions were colistin (tested at concentrations suitable for nebulization) either alone or in combination with tobramycin (10 mu g ml(-1)), followed by meropenem combined with tobramycin or ciprofloxacin. The findings of this study illustrate that antibiotic sensitivities are dependent on culture conditions and highlight the complexities of choosing appropriate combination therapy for multidrug-resistant P. aeruginosa in the CF lung.

Speaking for others: The pros and cons of group advocates using collective language

We examined how rhetorical style affects evaluations of group advocates, and how these evaluations are moderated by group identification. University students were given a letter to the editor defending student welfare. The argument was either constructed using personal language ('I believe') or collective language ('we believe'). Furthermore, the letter was either attributed to an official advocate (president of the student union) or an unofficial advocate (a rank-and-file member of the student body). Consistent with the social identity perspective, participants who showed strong identification as a university student thought that the group would feel better represented by official advocates using collective rather than personal language. Low identifiers, however, did not rate the rhetorical styles differently on representativeness. Furthermore, low identifiers (but not high identifiers) rated official advocates as more likable and more effective when they used personal rather than collective language. The discussion focuses on the conflict low identifiers might feel between (a) needing to homogenize with other group members in order to maximize the influence and political effectiveness of their message at the collective level, and (b) protecting themselves against categorization threat.

Perceptions of self and group in the context of a threatened national identity: A field study

Previous research indicates that people who are highly identified with their groups tend to remain committed to them under threat. This study examines the generalizability, of this effect to (a) a real-life context involving the perception that others view the ingroup (Australians) as intolerant of minorities and (b) various dimensions of social identification. The sample comprised 213 respondents to a random mail survey. Perceived threat was inversely related to self-stereotyping (i.e. perceptions of self-ingroup similarity), but only for individuals with weak subjective ties to other group members. Threat perceptions were also predictive of enhanced judgments of within-group variability on threat-relevant dimensions, particularly for individuals with weaker ingroup ties. Various strategies for coping with a threatened social identity are linked to different facets of social identification.

Perceptions of the intergroup structure and anti-Asian prejudice among white Australians

Subjective intergroup beliefs and authoritarianism were assessed in a field study (N=255) of White Australians' anti-Asian stereotyping and prejudice. A social identity analysis of intergroup prejudice was adopted, such that perceptions of the intergroup structure (instability, permeability, legitimacy and higher ingroup status) were proposed as predictors of higher prejudice (blatant and covert) and less favorable stereotyping. Consistent with the social identity approach, both independent and interacting roles for sociostructural predictors of Anti-Asian bias were observed, even after demographic and personality variables were controlled. For example, perceived legitimacy was associated with higher prejudice when White Australians' status position relative to Asian Australians was valued. Moreover, when participants evaluated Whites' position as unstable and high status or legitimate, perceptions of permeable intergroup boundaries were associated with anti-Asian bias. The present findings demonstrate status protection responses in advantaged group members in a field setting, lending weight to the contention that perceptions of sociostructural threat interact to predict outgroup derogation. Implications for theories of intergroup relations are discussed.

Normative influence and rational conflict decisions: Group norms and cost-benefit analyses for intergroup behavior

The present paper articulates a model in which ingroup and outgroup norms inform 'rational' decision-making (cost-benefit analysis) for conflict behaviors. Norms influence perceptions of the consequences of the behavior, and individuals may thus strategically conform to or violate norms in order to acquire benefits and avoid costs. Two studies demonstrate these processes in the context of conflict in Quebec. In the first study, Anglophones' perceptions of Francophone and Anglophone norms for pro-English behaviors predicted evaluations of the benefits and costs of the behaviors, and these cost-benefit evaluations in turn mediated the norm-intention links for both group norms. In the second study, a manipulated focus on supportive versus hostile ingroup and outgroup norms also predicted cost-benefit evaluations, which mediated the norm-intention relationships. The studies support a model of strategic conflict choices in which group norms inform, rather than suppress, rational expectancy value processes. Implications for theories of decision-making and normative influence are discussed.

Interconvertibility of single-rail optical qubits

We show how to convert between partially coherent superpositions of a single photon with the vacuum by using linear optics and postselection based on homodyne measurements. We introduce a generalized quantum efficiency for such states and show that any conversion that decreases this quantity is possible. We also prove that our scheme is optimal by showing that no linear optical scheme with generalized conditional measurements, and with one single-rail qubit input, can improve the generalized efficiency. (c) 2006 Optical Society of America.

Dynamic breast MRI: Image registration and its impact on enhancement curve estimation

A novel algorithm for performing registration of dynamic contrast-enhanced (DCE) MRI data of the breast is presented. It is based on an algorithm known as iterated dynamic programming originally devised to solve the stereo matching problem. Using artificially distorted DCE-MRI breast images it is shown that the proposed algorithm is able to correct for movement and distortions over a larger range than is likely to occur during routine clinical examination. In addition, using a clinical DCE-MRI data set with an expertly labeled suspicious region, it is shown that the proposed algorithm significantly reduces the variability of the enhancement curves at the pixel level yielding more pronounced uptake and washout phases.