Symbolic and Competitive Racism on Campus

After a short hiatus, overt racism is on the rise again. Increases in reported racially motivated crime and violence have been noted all over the country. In the wider U.S. society, identifiable racial incidents have been estimated to have increased 55 percent from 1986 to 1987. According to the Community Relations Service (CRS), African Americans comprised two-thirds of the victims in the cases reported in 1987. Although this racial violence has taken various forms ranging from name-calling, vandalism, and cross-burning to actual physical assaults that result in casualties and death, these have not been isolated incidents but have their basis in the racism that underlines U.S. institutions. This resurgence is due, in no small part, to the increasing level of conservatism that has swept the country, making racial intolerance and conflict the order of the day

Trends and determinants of contraceptive method choice in Kenya

This paper uses data from the 1989, 1993 and 1998 Kenya Demographic and Health Surveys to examine trends and determinants of contraceptive method choice. The analysis, based on two-level multinomial regression models, shows that, across years, use of modern contraceptive methods, especially long-term methods is higher in the urban than rural areas, while the pattern is reversed for traditional methods. Use of barrier methods among unmarried women is steadily rising, but the levels remain disappointingly low, particularly in view of the HIV/AIDS epidemic in Kenya. One striking result from this analysis is the dramatic rise in the use of injectables. Of particular program relevance is the notably higher levels of injectables use among rural women, women whose partners disapprove of family planning, uneducated women and those less exposed to family planning media messages, compared to their counterparts with better service accessibility and family planning information exposure

Will a Black Hole Soon Emerge from SN 1997D ?

Observations combined with theoretical modeling of the light curve of the recently discovered supernova 1997D in NGC 1536 suggest that it might host a black hole formed in the aftermath of the explosion. We consider some observable consequences of a black hole in SN 1997D and estimate the late--time accretion luminosity of the material which falls back onto the hole. We find that this luminosity, decaying with a characteristic power--law dependence on time, may emerge above the emission of the envelope in just a few years. Its detection would thus provide unmistakable evidence for the presence of a black hole.Comment: 8 pages, LaTeX, aaspp4.sty style file (AASTEX package), 2 postscript figures (included). To appear in The Astrophysical Journal Letters (scheduled for August 1, 1998 issue, Vol. 502

Lack of Pattern Separation in Sensory Inputs to the Olfactory Bulb during Perceptual Learning.

Recent studies revealed changes in odor representations in the olfactory bulb during active olfactory learning (Chu et al., 2016; Yamada et al., 2017). Specifically, mitral cell ensemble responses to very similar odorant mixtures sparsened and became more distinguishable as mice learned to discriminate the odorants over days (Chu et al., 2016). In this study, we explored whether changes in the sensory inputs to the bulb underlie the observed changes in mitral cell responses. Using two-photon calcium imaging to monitor the odor responses of the olfactory sensory neuron (OSN) axon terminals in the glomeruli of the olfactory bulb during a discrimination task, we found that OSN inputs to the bulb are stable during discrimination learning. During one week of training to discriminate between very similar odorant mixtures in a Go/No-go task, OSN responses did not show significant sparsening, and the responses to the trained similar odorants did not diverge throughout training. These results suggest that the adaptive changes of mitral cell responses during perceptual learning are ensured by mechanisms downstream of OSN input, possibly in local circuits within olfactory bulb

Microbial D/H fractionation in extraterrestrial materials: application to micrometeorites and Mars

High D/H terrestrial alteration of micrometeorites is described and suggested to be a result of microbial isotopic fractionation by methanogens. Applications to other planetary materials, including martian meteorites, are also considered

The Low End of the Supermassive Black Hole Mass Function: Constraining the Mass of a Nuclear Black Hole in NGC 205 via Stellar Kinematics

Hubble Space Telescope (HST) images and spectra of the nucleated dwarf elliptical galaxy NGC 205 are combined with 3-integral axisymmetric dynamical models to constrain the mass (M_BH) of a putative nuclear black hole. This is only the second attempt, after M33, to use resolved stellar kinematics to search for a nuclear black hole with mass below 10^6 solar masses. We are unable to identify a best-fit value of M_BH in NGC 205; however, the data impose a upper limit of 2.2x10^4 M_sun (1sigma confidence) and and upper limit of 3.8x10^4 M_sun (3sigma confidence). This upper limit is consistent with the extrapolation of the M_BH-sigma relation to the M_BH < 10^6 M_sunregime. If we assume that NGC 205 and M33 both contain nuclear black holes, the upper limits on M_BH in the two galaxies imply a slope of ~5.5 or greater for the M_BH-sigma relation. We use our 3-integral models to evaluate the relaxation time (T_r) and stellar collision time (T_coll) in NGC 205; T_r~10^8 yr or less in the nucleus and T_coll~10^11 yr. The low value of T_r is consistent with core collapse having already occurred, but we are unable to draw conclusions from nuclear morphology about the presence or absence of a massive black hole.Comment: Latex emulateapj, 15 pages, 16 figures, Version accepted for Publication in ApJ, 20 July 2005, v628. Minor changes to discussion

Cryptoendolith communities in Antarctic dry valley region sandstones: Potential analogues of Martian life-forms

We are studying cryptoendolith-bearing Antarctic sandstones, to determine if the microbes alter the elemental composition of the rocks. If there is an effect, then it might be a tracer for the presence of micro-organisms in martian surface materials

Conservation of exon scrambling in human and mouse

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Biology, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 21-23).Exon scrambling is a phenomenon in which the exons of an mRNA transcript are spliced in an order inconsistent with that of the genome. In this thesis, I present a computational analysis of scrambled exons in human and mouse. RNA-seq data was mapped to the genome and all unaligned reads were subsequently mapped to a database of all possible exon-exon junctions. Eight conserved genes were found to undergo scrambled splicing in both species. In several cases, not only the gene was conserved, but the particular exons involved were conserved as well. Reading frame was preserved in just over half of the events, indicating that although some transcripts may be translated into protein, some may be non-functional or may play a regulatory role. The introns flanking scrambled exons were significantly longer than average, providing clues to the mechanism for this abnormal splicing pattern. The results of this study demonstrate that presence of scrambled transcripts in the cell is infrequent, but can be conserved over tens of millions of years of evolution, suggesting it has a biological function.by Monica L. Hamilton.S.M