Racial Insularity at the Core: Contemporary American Racial Attitudes

Survey research scientists have been interested in American racial attitudes ever since the craft has achieved a reasonable degree of precision. White attitudes toward blacks constitute the longest running topic in survey research. However, as a result of dramatic and systematic changes in racial attitudes and because of the changing nature of race relations per se, there may be less agreement now about the structure of American racial values than at any time since World War II. This paper will provide a capsule presentation of the major findings of recent research on racial attitudes and a brief summary of the current controversies

Abundances and search for vertical stratification in the atmospheres of four HgMn stars

Using high resolution, high-S/N archival UVES spectra, we have performed a detailed spectroscopic analysis of 4 chemically peculiar HgMn stars (HD 71066, HD 175640, HD 178065 and HD 221507). Using spectrum synthesis, mean photospheric chemical abundances are derived for 22 ions of 16 elements. We find good agreement between our derived abundances and those published previously by other authors. For the 5 elements that present a sufficient number of suitable lines, we have attempted to detect vertical chemical stratification by analyzing the dependence of derived abundance as a function of optical depth. For most elements and most stars we find no evidence of chemical stratification with typical 3\sigma upper limits of \Delta\log N_elem/N_tot~0.1-0.2 dex per unit optical depth. However, for Mn in the atmosphere of HD 178065 we find convincing evidence of stratification. Modeling of the line profiles using a two-step model for the abundance of Mn yields a local abundance varying approximately linearly by ~0.7 dex through the optical depth range log \tau_5000=-3.6 to -2.8.Comment: 11 figures, 9 tables, table 6-9 (online material), accepted by MNRA

The magnetic Bp star 36 Lyncis, I. Magnetic and photospheric properties

This paper reports the photospheric, magnetic and circumstellar gas characteristics of the magnetic B8p star 36 Lyncis (HD 79158). Using archival data and new polarised and unpolarised high-resolution spectra, we redetermine the basic physical properties, the rotational period and the geometry of the magnetic field, and the photospheric abundances of various elements.}{Based on magnetic and spectroscopic measurements, we infer an improved rotational period of $3.83475\pm 0.00002$ d. We determine a current epoch of the longitudinal magnetic field positive extremum (HJD 2452246.033), and provide constraints on the geometry of the dipole magnetic field (i\geq 56\degr, $3210 {\rm G}\leq B_{\rm d}\leq 3930$ G, $\beta$ unconstrained). We redetermine the effective temperature and surface gravity using the optical and UV energy distributions, optical photometry and Balmer line profiles ($T_{\rm eff}=13300\pm 300$ K, $\log g=3.7-4.2$), and based on the Hipparcos parallax we redetermine the luminosity, mass, radius and true rotational speed ($L=2.54\pm 0.16 L_\odot, M=4.0\pm 0.2 M_\odot, R=3.4\pm 0.7 R_\odot, v_{\rm eq}=45-61.5$ \kms). We measure photospheric abundances for 21 elements using optical and UV spectra, and constrain the presence of vertical stratification of these elements. We perform preliminary Doppler Imaging of the surface distribution of Fe, finding that Fe is distributed in a patchy belt near the rotational equator. Most remarkably, we confirm strong variations of the H$\alpha$ line core which we interpret as due to occultations of the star by magnetically-confined circumstellar gas.Comment: Accepted by Astronomy and Astrophysic

A Computerized Mapping System for Forest Resource Management Planning

Large volumes of inventory data are collected and analyzed with the idea of developing resource management schemes for the future. Unless this inventory information is easily accessible, is of the type needed to make management decisions in accordance with current policy, and has a readily available updating system, the entire management plan often becomes a seldom, if ever, used document. This study deals with the application of several inventory collection and display techniques to assist in making rapid and accurate resource management decisions on a continuing basis. The objective of the study is to develop a comprehensive forest resource management plan for the U.S. Department of the Army, Corps of Engineers Philpott Reservoir Complex located on the Piedmont geomorphic province near Bassett, Virginia. Specifically the management plan is focused on increasing the value of the lands primarily for recreation and wildlife with the inclusion of other compatible uses where appropriate. A healthy and vigorous forest system is required in order to withstand the stresses imposed by man and nature. Therefore, a forest complex capable of supporting the planned recreation, wildlife, scenic attractiveness and other project uses must be maintained so as to yield the maximum social benefit and insure the ecologic integrity of the system

The magnetic Bp star 36 Lyncis, II. A spectroscopic analysis of its co-rotating disk

We report on the physical properties of the disk-like structure of B8 IIIp star 36 Lyncis from line syntheses of phase-resolved, high resolution spectra obtained from the IUE archives and from newly obtained ground-based H$\alpha$ spectra. This disk is highly inclined to the rotational axis and betrays its existence every half rotation cycle as one of two opposing sectors pass in front of the star. Although the disk absorption spectrum is at least ten times too weak to be visible in optical iron lines during these occultations, its properties can be readily examined in a large number of UV "iron curtain" lines because of their higher opacities. The analysis of the variations of the UV resonance lines brings out some interesting details about the radiative properties of the disks: (1) they are optically thick in the C IV and Si IV doublets, (2) the range of excitation of the UV resonance lines is larger at the primary occultation ($\phi$ = 0.00) than at the secondary one, and (3) the {\bf relative strengths of the absorption peaks} for the two occultations varies substantially from line to line. We have modeled the absorptions of the UV C IV resonance and H$\alpha$ absorptions by means of a simulated disk with opaque and translucent components. Our simulations suggest that a gap separates the star and the inner edge of the disk. The disk extends radially out to $\geq$10 R$_{*}$. The disk scale height perpendicular to the plane is $\approx$1R$_{*}$. However, the sector causing the primary occultation is about four times thicker than the opposite sector. The C IV scattering region extends to a larger height than the H$\alpha$ region does, probably because it results from shock heating far from the cooler disk plane.Comment: Accepted by Astronomy and Astrophysic

Optimizing SNR for multi-metabolite hyperpolarized carbon-13 MRI using a hybrid flip-angle scheme

Purpose: To improve the SNR of hyperpolarized carbon-13 MRI of [1-13C]pyruvate using a multispectral variable flip angle (msVFA) scheme in which the spectral profile and flip angle vary dynamically with time. Methods: Each image acquisition in a time-resolved imaging experiment used a unique spectrally varying RF pulse shape for msVFA. Therefore, the flip angle for every acquisition was optimized for pyruvate and each of its metabolites to yield the highest SNR across the acquisition. Multispectral VFA was compared with a spectrally varying constant flip-angle excitation model through simulations and in vivo. A modified broadband chemical shift-encoded gradient-echo sequence was used for in vivo experiments on six pregnant guinea pigs. Regions of interest placed in the placentae, maternal liver, and maternal kidneys were used as areas for SNR measurement. Results: In vivo experiments showed significant increases in SNR for msVFA relative to constant flip angle of up to 250% for multiple metabolites. Conclusion: Hyperpolarized carbon-13 imaging with msVFA excitation produces improved SNR for all metabolites in organs of interest

Discerning population connectivity and natal origins of Pacific herring (Clupea pallasi): inferences on population structure from otolith chemistry

Pacific herring, Clupea pallasi, undertake annual migrations between feeding and spawning grounds that link life stages, habitats, populations, communities, and ecosystems. However, movement patterns of these highly mobile fish are poorly understood. Declines in Pacific herring abundance and slow population recoveries in the absence of fishing pressure have elevated concerns over the status of this ecologically, economically, and culturally important species. Pacific herring spawn on substrate in nearshore habitats where eggs and larvae develop for approximately two weeks before hatching. Early development within discrete spawning grounds could facilitate the incorporation of distinctive chemical signatures within otoliths that could be used as intrinsic markers to trace movements and mixing among groups or regions. Identifying the direction and strength of connectivity among groups can reveal source populations and promote the development of population- and ecosystem-based management strategies that reflect ecologically relevant spatial scales. We applied otolith microchemistry data to: 1) test the utility of elemental signatures to distinguish the natal origins of larval herring; 2) evaluate inter-annual variation in natal signatures within spawning sites; and 3) assess the similarity of edge and natal signatures of adult herring within and among spawning sites. In 2015 and 2016, we sampled actively spawning adult herring and their offspring in the northern Salish Sea and across British Columbia, Canada. Otoliths were extracted, aged, and their elemental composition analyzed using laser ablation inductively coupled plasma mass spectrometry. Cohort-specific analyses were applied to assess consistency among elemental signatures and broader, age-specific movement patterns. Our analyses show that otolith elemental signatures of Pacific herring can provide insight into complex population structure at scales of 10s – 1000 kms to inform and enhance spatially-explicit approaches to conservation and management

Modeling black student academic performance in higher education

Recent research has noted differences in the predictive efficacy of educational attainment models produced for whites as opposed to blacks; and called for more resolution in the findings on blacks in advance of further comparative analyses. The National Study of Black College Students (NSBCS) is employed to develop a model that distinguishes between high- and low-performing black undergraduates attending public, four-year institutions. In the NSBCS sample ( N =695), discriminant function analysis identifies several institutional and student characteristics which are related to black students' educational outcomes. Specifically, students with both high occupational aspirations and high academic performances tend to be male, attend comparatively larger schools, and, to a lesser degree, be relatively well-adjusted upperclassmen. When academic performance is the sole issue, it is positively correlated with institutional quality, but the advantage belongs to black females. Contrary to the suggestions of previous research, black community sentiment did not have relationships with educational outcomes to the extent expected. These results suggest that future models of black educational attainment marry traditional Wisconsin-type measures with institutional and student attributes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43592/1/11162_2004_Article_BF00975106.pd