Nem um tostão da previdência social : o caso das bóias-frias idosas no semi-árido irrigado

Inclui notas explicativas e bibliográficas

How Escherichia coli can bias the results of molecular cloning: Preferential selection of defective genomes of hepatitis C virus during the cloning procedure

Cloned PCR products containing hepatitis C virus (HCV) genomic fragments have been used for analyses of HCV genomic heterogeneity and protein expression. These studies assume that the clones derived are representative of the entire virus population and that subsets are not inadvertently selected. The aim of the present study was to express HCV structural proteins. However, we found that there was a strong cloning selection for defective genomes and that most clones generated initially were incapable of expressing the HCV proteins. The HCV structural region (C-E1-E2-p7) was directly amplified by long reverse transcription–PCR from the plasma of an HCV-infected patient or from a control plasmid containing a viable full-length cDNA of HCV derived from the same patient but cloned in a different vector. The PCR products were cloned into a mammalian expression vector, amplified in Escherichia coli, and tested for their ability to produce HCV structural proteins. Twenty randomly picked clones derived from the HCV-infected patient all contained nucleotide mutations leading to absence or truncation of the expected HCV products. Of 25 clones derived from the control plasmid, only 8% were fully functional for polyprotein synthesis. The insertion of extra nucleotides in the region just upstream of the start codon of the HCV insert led to a statistically significant increase in the number of fully functional clones derived from the patient (42%) and from the control plasmid (72–92%). Nonrandom selection of clones during the cloning procedure has enormous implications for the study of viral heterogeneity, because it can produce a false spectrum of genomic diversity. It can also be an impediment to the construction of infectious viral clones.

Evolution of codon usage bias in Drosophila

We first review what is known about patterns of codon usage bias in Drosophila and make the following points: (i) Drosophila genes are as biased or more biased than those in microorganisms. (ii) The level of bias of genes and even the particular pattern of codon bias can remain phylogenetically invariant for very long periods of evolution. (iii) However, some genes, even very tightly linked genes, can change very greatly in codon bias across species. (iv) Generally G and especially C are favored at synonymous sites in biased genes. (v) With the exception of aspartic acid, all amino acids contribute significantly and about equally to the codon usage bias of a gene. (vi) While most individual amino acids that can use G or C at synonymous sites display a preference for C, there are exceptions: valine and leucine, which prefer G. (vii) Finally, smaller genes tend to be more biased than longer genes. We then examine possible causes of these patterns and discount mutation bias on three bases: there is little evidence of regional mutation bias in Drosophila, mutation bias is likely toward A+T (the opposite of codon usage bias), and not all amino acids display the preference for the same nucleotide in the wobble position. Two lines of evidence support a selection hypothesis based on tRNA pools: highly biased genes tend to be highly and/or rapidly expressed, and the preferred codons in highly biased genes optimally bind the most abundant isoaccepting tRNAs. Finally, we examine the effect of bias on DNA evolution and confirm that genes with high codon usage bias have lower rates of synonymous substitution between species than do genes with low codon usage bias. Surprisingly, we find that genes with higher codon usage bias display higher levels of intraspecific synonymous polymorphism. This may be due to opposing effects of recombination.

Effects of passage history and sampling bias on phylogenetic reconstruction of human influenza A evolution

In this paper we determine the extent to which host-mediated mutations and a known sampling bias affect evolutionary studies of human influenza A. Previous phylogenetic reconstruction of influenza A (H3N2) evolution using the hemagglutinin gene revealed an excess of nonsilent substitutions assigned to the terminal branches of the tree. We investigate two hypotheses to explain this observation. The first hypothesis is that the excess reflects mutations that were either not present or were at low frequency in the viral sample isolated from its human host, and that these mutations increased in frequency during passage of the virus in embryonated eggs. A set of 22 codons known to undergo such “host-mediated” mutations showed a significant excess of mutations assigned to branches attaching sequences from egg-cultured (as opposed to cell-cultured) isolates to the tree. Our second hypothesis is that the remaining excess results from sampling bias. Influenza surveillance is purposefully biased toward sequencing antigenically dissimilar strains in an effort to identify new variants that may signal the need to update the vaccine. This bias produces an excess of mutations assigned to terminal branches simply because an isolate with no close relatives is by definition attached to the tree by a relatively long branch. Simulations show that the magnitude of excess mutations we observed in the hemagglutinin tree is consistent with expectations based on our sampling protocol. Sampling bias does not affect inferences about evolution drawn from phylogenetic analyses. However, if possible, the excess caused by host-mediated mutations should be removed from studies of the evolution of influenza viruses as they replicate in their human hosts.

Neighboring base composition and transversion/transition bias in a comparison of rice and maize chloroplast noncoding regions.

The correspondence between the transversion/transition ratio and the neighboring base composition in chloroplast DNA is examined. For 18 noncoding regions of the chloroplast genome, alignments between rice (Oryza sativa) and maize (Zea mays) were generated by two different methods. Difficulties of aligning noncoding DNA are discussed, and the alignments are analyzed in a manner that reduces alignment artifacts. Sequence divergence is < 10%, so multiple substitutions at a site are assumed to be rare. Observed substitutions were analyzed with respect to the A+T content of the two immediately flanking bases. It is shown that as this content increases, the proportion of transversions also increases. When both the 5'- and 3'-flanking nucleotides are G or C (A+T content of 0), only 25% of the observed substitutions are transversions. However, when both the 5'- and 3'-flanking nucleotides are A or T (A+T content of 2), 57% of the observed substitutions are transversions. Therefore, the influence of flanking base composition on substitutions, previously reported for a single noncoding region, is a general feature of the chloroplast genome.

Interval bias in 2AFC detection tasks: sorting out the artifacts

Proportion correct in two-alternative forcedchoice (2AFC) detection tasks often varies when the stimulus is presented in the first or in the second interval.Reanalysis of published data reveals that these order effects (or interval bias) are strong and prevalent, refuting the standard difference model of signal detection theory. Order effects are commonly regarded as evidence that observers use an off-center criterion under the difference model with bias. We consider an alternative difference model with indecision whereby observers are occasionally undecided and guess with some bias toward one of the response options. Whether or not the data show order effects, the two models fit 2AFC data indistinguishably, but they yield meaningfully different estimates of sensory parameters. Under indeterminacy as to which model governs 2AFC performance, parameter estimates are suspect and potentially misleading. The indeterminacy can be circumvented by modifying the response format so that observers can express indecision when needed. Reanalysis of published data collected in this way lends support to the indecision model. We illustrate alternative approaches to fitting psychometric functions under the indecision model and discuss designs for 2AFC experiments that improve the accuracy of parameter estimates, whether or not order effects are apparent in the data.

What We Don't Know Can Hurt Us: Clinical Inference Bias and Constructed Memories of Sexual Abuse.

The false memory/recovered memory debate, research regarding the malleability of memory, and the current lack of methods for validating recovered memories all support the view that heightened care is required of therapists dealing with clients whom they suspect have been sexually abused. The judgmental heuristics that underlie the major clinical inference biases of confirmatory bias, biased covariation, base rate fallacies, and schematic processing errors are all relevant to the processes leading to therapist-client constructions of memories of sexual abuse. Suggestions for minimizing each of these biases are offered. Personal motivations of the client and client suggestibility are factors that may contribute to the construction of memories of sexual abuse, and suggestions for minimizing the impact of these motivations are offered. In conclusion, general suggestions for minimizing the impact of clinical inference biases within the sexual abuse treatment context are summarized.

Difference Blindness vs. Bias Awareness: Why Law Firms with the Best of Intentions Have Failed to Create Diverse Partnerships

This Article uses the example of BigLaw firms to explore the challenges that many elite organizations face in providing equal opportunity to their workers. Despite good intentions and the investment of significant resources, large law firms have been consistently unable to deliver diverse partnership structures - especially in more senior positions of power. Building on implicit and institutional bias scholarship and on successful approaches described in the organizational behavior literature, we argue that a significant barrier to systemic diversity at the law firm partnership level has been, paradoxically, the insistence on difference blindness standards that seek to evaluate each person on their individual merit. While powerful in dismantling intentional discrimination, these standards rely on an assumption that lawyers are, and have the power to act as, atomistic individuals - a dangerous assumption that has been disproven consistently by the literature establishing the continuing and powerful influence of implicit and institutional bias. Accordingly, difference blindness, which holds all lawyers accountable to seemingly neutral standards, disproportionately disadvantages diverse populations and normalizes the dominance of certain actors - here, white men - by creating the illusion that success or failure depends upon individual rather than structural constraints. In contrast, we argue that a bias awareness approach that encourages identity awareness and a relational framework is a more promising way to promote equality, equity, and inclusion.

Examining the relationship among genes, attention bias to emotion, and depression in youth

The investigation of biologically initiated pathways to psychological disorder is critical to advance our understanding of mental illness. Research has suggested that attention bias to emotion may be an intermediate trait for depression associated with biologically plausible candidate genes, such as the serotonin transporter (5-HTTLPR) and catechol-o-methyl-transferase (COMT) genes, yet there have been mixed findings in regards to the precise direction of effects. The experience of recent stressful life events (SLEs) may be an important, yet currently unstudied, moderator of the relationship between genes and attention bias as SLEs have been associated with both gene expression and attention to emotion. Additionally, although attention biases to emotion have been studied as a possible intermediate trait associated with depression, no study has examined whether attention biases within the context of measured genetic risk lead to increased risk for clinical depressive episodes over time. Therefore, this research investigated both whether SLEs moderate the link between genetic risk (5-HTTLPR and COMT) and attention bias to emotion and whether 5-HTTLPR and COMT moderated the relationship between attention biases to emotional faces and clinical depression onset prospectively across 18 months within a large community sample of youth (n= 467). Analyses revealed a differential effect of gene. Youth who were homozygous for the low expressing allele of 5-HTTLPR (S/S) and had experienced more recent SLEs within the last three months demonstrated preferential attention toward negative emotional faces (angry and sad). However, youth who were homozygous for the high expressing COMT genotype (Val/Val) and had experienced more recent SLEs showed attentional avoidance of positive facial expressions (happy). Additionally, youth who avoided negative emotion (i.e., anger) and were homozygous for the S allele of the 5-HTTLPR gene were at greater risk for prospective depressive episode onset. Increased risk for depression onset was specific to the 5-HTTLPR gene and was not found when examining moderation by COMT. These findings highlight the importance of examining risk for depression across multiple levels of analysis, such as combined genetic, environmental, and cognitive risk, and is the first study to demonstrate clear evidence of attention biases to emotion functioning as an intermediate trait predicting depression.

Quality of pharmaceutical advertising and gender bias in medical journals (1998-2008): a review of the scientific literature

Objective: To review the scientific literature on pharmaceutical advertising aimed at health professionals in order to determine whether gender bias has decreased and the quality of information in pharmaceutical advertising has improved over time. Methods: We performed a content analysis of original articles dealing with medical drug promotion (1998-2008), according to quality criteria such as (a) the number, validity and accessibility of bibliographic references provided in pharmaceutical advertising and (b) the extent to which gender representations were consistent with the prevalence of the diseases. Databases: PUBMED, Medline, Scopus, Sociological Abstract, Eric and LILACS. Results: We reviewed 31 articles that analyzed advertising in medical journals from 1975-2005 and were published between 1998 and 2008. We found that the number of references used to support pharmaceutical advertising claims increased from 1975 but that 50% of these references were not valid. There was a tendency to depict men in paid productive roles, while women appeared inside the home or in non-occupational social contexts. Advertisements for psychotropic and cardiovascular drugs overrepresented women and men respectively. Conclusions: The use of bibliographic references increased between 1998 and 2008. However, representation of traditional male-female roles was similar in 1975 and 2005. Pharmaceutical advertisements may contribute to reinforcing the perception that certain diseases are associated with the most frequently portrayed sex.

The high-bias stability of monatomic chains

For the metals Au, Pt and Ir it is possible to form freely suspended monatomic chains between bulk electrodes. The atomic chains sustain very large current densities, but finally fail at high bias. We investigate the breaking mechanism, that involves current-induced heating of the atomic wires and electromigration forces. We find good agreement of the observations for Au based on models due to Todorov and co-workers. The high-bias breaking of atomic chains for Pt can also be described by the models, although here the parameters have not been obtained independently. In the limit of long chains the breaking voltage decreases inversely proportional to the length.

Evaluating Taphonomic Bias in a Storm-Disturbed Carbonate Platform: Effects of Compositional and Environmental Factors in Lower Jurassic Brachiopod Accumulations (Eastern Subbetic Basin, Spain)

In order to evaluate taxonomic and environmental control on the preservation pattern of brachiopod accumulations, sedimentologic and taphonomic data have been integrated with those inferred from the structure of brachiopod accumulations from the easternmost Lower Jurassic Subbetic deposits in Spain. Two brachiopod communities (Praesphaeroidothyris and Securina communities) were distinguished showing a mainly free-lying way of life in soft-bottom habitats. Three taphofacies are discriminated based on proportion of disarticulation, fragmentation, packing, and shell filling. Taphofacies 1 is represented by thinly fragmented, dispersed brachiopod shells in wackestone beds. Taphofacies 2 is spatially restricted to small lenses where shells are poorly fragmented, rarely disarticulated, usually void filled, and highly packed. Taphofacies 3 is represented by mud or cement filled, loosely packed, articulated brachiopods forming large pocket-like structures. Temporal and spatial averaging were minimally involved in taphofacies 2 and 3. It is interpreted that patchy preservation implies preservation of primary original patchiness of brachiopod communities on the seafloor. The origin of shell-rich taphofacies (2 and 3) is related to rapid burial due to episodic storm activity, while shell-poor taphofacies 1 records background conditions. The nature and comparative diversity of these taphofacies underscores the importance of rapid burial for shell beds preservation. Differences in preservation between taphofacies 2 and 3 are mainly related to environmental criteria, most importantly storm energy and water depth. In contrast, the taxonomic-specific pattern of the communities is a subordinate element of control, controlling only minor within-taphofacies differences in preservation.