Confirming the Stereotype: How Stereotype Threat, Performance Feedback, and Academic Identification affect Identity and Future Performance

This study investigates the post-performance effects of stereotype threat. Undergraduate students (N = 130) classified as either strongly- or weakly- identified with academics were told a diagnostic anagram task either typically shows poorer performance for their gender (stereotype threat) or no gender differences (no stereotype threat), and received arbitrary positive or negative feedback on an initial task. They later performed a second anagram task. Results indicate a 2-way interaction between stereotype threat and academic identification among those who received negative feedback. Negative feedback under stereotype threat did not harm performance for participants strongly-identified with academics, but did harm performance for participants weakly-identified with academics. This same 2-way interaction within the negative feedback condition also predicted post-feedback levels of identification as a college student, though it did not seem to affect post-feedback levels of academic identification. Strongly-identified participants receiving negative feedback identified less as a college student if they were under stereotype threat while weakly-academically identified participants identified more. Levels of post-feedback identification as a college student negatively predicted performance

Chemosynthetic communities in the deep sea : ecological studies

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 1989Deep-sea benthic communities dependent on chemosynthetic primary production are associated with areas of active venting of chemically-modified seawater. Patterns in the distribution of species that occur at hydrothermal vents can be used to predict locations of the vent sites. Patterns in the distributions of species among vents along ridge segments are used to identify the spatial scales over which biological and physical processes operate to control community composition. Within a vent, a zonation in species distributions correlates with gradients of temperature and water chemistry. Along a given ridge segment, vent communities share the same species pool, but the relative abundance of each species varies from one site to another. On a basin-wide scale, the fauna of vent communities represent biological continua, where gradual morphological and genetic differentiation in species is correlated with increasing distance between vent sites. Differentiation of distinctive faunals assemblages at vents occursat a global scale. Populations of species at vents are established and maintained through recruitment of larval stages. To study recruitment processes at vent sites, slate panels were placed at and near vent sites on the seafloor for varying lengths of time. Size distributions of animals on retrieved panels suggest that recruitment is an intermittent or continuous process rather than a single episodic event. Recruitment of vent-associated species was greater on panels placed within vent communities compared to panels placed adjacent to these communities, a pattern consistent with the observed maintenance of communities in discrete regions of hydrothermal flux. The trophic structure of chemosynthetic communities can be complex. Primary production by chemoautotrophic bacteria can take place within host tissues of some invertebrates as well as on surfaces and in the water column and subsurface conduits. Carbon and nitrogen isotopic compositions of host tissues can be used to demonstrate the dependence of symbiont species on chemosynthetically-derived organic material. From the patterns in the isotopic compositions of vent and seep symbionts, potential sources of inorganic carbon are identified. Deep-water dissolved inorganic carbon serves as a large, isotopically buffered pool of inorganic carbon used by tubeworms and bivalves at hydrothermal communities of Juan de Fuca, Gorda, Guaymas Basin, East Pacific Rise, Galapagos, and Marianas vents. Variability in tubeworm carbon isotopic compositions at seeps may be attributed to significant contributions of isotopically variable DIC in seep effluents. Isotopic techniques are also used to explore trophic relationships among a variety of heterotrophic and symbiont-containing fauna at Hanging Gardens on the East Pacific Rise and at Marianas vents. Carbon isotopic measurements suggest that free-living bacteria are important sources of food at both sites. Nitrogen isotopic analyses show that the Marianas community may be simpler in trophic structure than the Hanging Gardens community. The biomass of most known vent sites is conspicuously dominated by large invertebrates with symbiotic bacteria. At vent sites on the Mid-Atlantic Ridge, large swarms of shrimp dominate the biomass. There is no evidence for endosymbionts in these shrimp, based on analyses of morphology, stable isotopes, lipopolysaccharides and ribulose- l, 5-bisphosphate carboxylase activity. Instead, the shrimp appear to be normal heterotrophs, grazing on free-living microorganisms associated with black smoker chimneys. High bacterial productivity within the sulfide matrix of the chimneys must be required to sustain the shrimp populations. Hydrothermal vent environments exhibit some of the most extreme gradients of temperature and chemistry found in the biosphere. Many of the animals that colonize vent sites exhibit adaptations that allow them to exist in such an unusual environment. A novel eye in shrimp from Mid-Atlantic Ridge vents is described. The eye, comprised of a pair of large organs within the cephalothorax, contains a visual pigment but lacks image-forming optics. The eye appears to be adapted for detection of low-level illumination and is suggested to have evolved in response to a source of radiation associated with the environment of hydrothermal vents. An electronic camera was used to detect light emitted from high-temperature (350°C) plumes that rise from the orifice of black smoker chimneys on the Endeavour Segment of the Juan de Fuca Ridge. Calculations suggest that thermal radiation from hot water may account for most of the light detected and that this light may be sufficient for geothermally-drive photosynthesis by bacteria.Portions of this dissertation were supported by grants from NSF, ONR, Sea Grant, and the WHOI Ocean Ventures Fund, by the WHOI Education Office, the WHOI Biology Department, and an NSF graduate fellowship

Reporting Rape: Stigmatizing Reactions to Survivors Who Seek Accountability

Rape survivors face stigma when disclosing their experiences. We hypothesized that a rape survivor who formally reports their rape would experience more stigma than one who does not, and that this effect will be stronger when the perceiver is a man or low in support for sexual consent. Across two studies using self-report, observational, and psychophysiological measures, we found that a reporting survivor was seen more negatively than an identical survivor who did not report their rape. Men and those low in support for sexual consent also responded more negatively to the survivor. Implications of these findings are discussed

Not all Inequalities are Created Equal: Inequality Frames and Threat among Advantaged Groups

The way we understand an inequality can depend on small differences in how the inequality is described. This research focuses on one subtle but potentially powerful difference in how inequalities are described: advantage vs. disadvantage framing. When an inequality is described using an advantage frame (e.g., “men have higher wages than women”), it puts the focus on the advantages held by the advantaged group. In contrast, when an inequality is described using a disadvantage frame (e.g., “women have lower wages than men”), it puts the focus on the disadvantages faced by the disadvantaged group. This dissertation investigates the hypothesis that when advantaged by an illegitimate inequality, individuals will avoid using advantage frames. I hypothesize that this will occur because focusing on one’s unfair advantages is more threatening that focusing on another’s unfair disadvantages. In four pilot studies and seven experiments (N = 2,669), I found tentative support for these hypotheses: In Studies 1-3, I found evidence that when advantaged by an inequality (but not when disadvantaged by an inequality), individuals were less likely to use advantage frames when the inequality they were describing was illegitimate (vs. legitimate). This suggests that individuals may avoid using advantage frames when their group is illegitimately favored in order to avoid focusing on their unfair advantages. Studies 4-7 investigated the role of threat in how individuals advantaged by illegitimate inequalities use and respond to inequality frames. I found that advantage frames prompted more cardiovascular threat than disadvantage frames among Whites preparing to discuss illegitimate racial inequality. However, I did not find concrete evidence for the two theorized mechanisms behind this threat, nor did I find direct evidence that threat influences which inequality frames individuals choose to use when describing the illegitimate inequalities. This research helps illuminate the potentially large effects of small linguistic differences in our descriptions of inequality. It also highlights the subtle ways that those who are advantaged by inequality may shift their descriptions of inequality to avoid challenges to their position

Discrimination and Perceived Cultural Mismatch Increase Status-Based Identity Uncertainty

Periods of social mobility, such as attending college, can challenge one’s status-based identity, leading to uncertainty around one’s status in society. Status uncertainty is associated with poorer well-being and academic outcomes. Little is known, however, about what experiences lead to status uncertainty. The current longitudinal study investigated discrimination experiences and cultural mismatch as predictors of status uncertainty. We propose that discrimination indirectly predicts increased status uncertainty by increasing perceived cultural mismatch with the university. Participants were Latinx college students, all of whom were low-income and/or first generation to college. Discrimination experiences were measured at the end of participants’ first year. Cultural mismatch and status uncertainty were measured at the end of Year 2. Status uncertainty was measured again at the end of Year 3. Results indicated that students who experienced more frequent discrimination felt more cultural mismatch 1 year later, and, in turn, reported increased status uncertainty over the following year

Hyperon-nucleon scattering and hyperon masses in the nuclear medium

We analyze low-energy hyperon-nucleon scattering using an effective field theory in next-to-leading order. By fitting experimental cross sections for laboratory hyperon momenta below 200 MeV/c and using information from the hypertriton we determine twelve contact-interaction coefficients. Based on these we discuss the low-density expansion of hyperon mass shifts in the nuclear medium.Comment: 10 pages, 2 figure

Chiral SU(3) Symmetry and Strangeness

In this talk we review recent progress on the systematic evaluation of the kaon and antikaon spectral functions in dense nuclear matter based on a chiral SU(3) description of the low-energy pion-, kaon- and antikaon-nucleon scattering data.Comment: 9 pages, 4 figures, invited talk given by M.F.M.L. at the SQM2001 conferenc

Safety Study of an Antimicrobial Peptide Lactocin 160, Produced by the Vaginal Lactobacillus rhamnosus

Objective. To evaluate the safety of the antimicrobial peptide, lactocin 160. Methods. Lactocin 160, a product of vaginal probiotic Lactobacillus rhamnosus 160 was evaluated for toxicity and irritation. An in vitro human organotypic vaginal-ectocervical tissue model (EpiVaginal) was employed for the safety testing by determining the exposure time to reduce tissue viability to 50% (ET-50). Hemolytic activity of lactocin160 was tested using 8% of human erythrocyte suspension. Susceptibility of lactobacilli to lactocin160 was also studied. Rabbit vaginal irritation (RVI) model was used for an in vivo safety evaluation. Results. The ET-50 value was 17.5 hours for lactocin 160 (4.9 hours for nonoxynol 9, N9). Hemolytic activity of lactocin 160 was 8.2% (N9 caused total hemolysis). Lactobacilli resisted to high concentrations of peptide preparation. The RVI model revealed slight vaginal irritation. An average irritation index grade was evaluated as “none.” Conclusions. Lactocin 160 showed minimal irritation and has a good potential for intravaginal application

Mechanisms of biofilm inhibition and degradation by antimicrobial peptides

Many bacteria live as biofilms to cope with unfavourable surroundings. Biofilms start from (i) a planktonic stage, (ii) initial adhesion to surfaces and (iii) formation of sessile micro-colonies that secrete extracellular polymeric substance (EPS), leading to bacterial resistance to antibiotics. Antimicrobial peptides (AMPs) are extensively studied with regard to planktonic bacteria but much less so with regard to biofilm formation. In the present study, we investigated how the above three steps are affected by the properties of the AMPs using a series of peptides composed of six lysines and nine leucines, which differ in their sequences and hence their biophysical properties. Treatment with bactericidal peptides at non-inhibitory concentrations resulted in reduced biofilm growth, for some starting from 25 nM which is 0.2 and 0.4% of their minimum inhibitory concentration (MIC 6.3 and 12.5 μM, respectively), continuing in a dose-dependent manner. We suggest that reduced bacterial adhesion to surfaces and decreased biofilm growth are due to the peptide's ability to coat either the biomaterial surface or the bacterium itself. Degradation of established biofilms by bactericidal and non-bactericidal peptides, within 1 h of incubation, occurs by either killing of embedded bacteria or detachment of live ones. In addition to shedding light on the mechanism of biofilm inhibition and degradation, these data may assist in the design of anti-biofilm AMPs

Safety of Log Transportation After Regulation and Training in the State of Georgia, USA

Mechanical failure rates observed in highway accidents involving logging tractor-trailers have fallen significantly since Georgia subjected these vehicles to random roadside inspections. This improvement is attributed to both the regulation and the training efforts aimed at the log trucking community immediately before and after the implementation of the rules