415 research outputs found
Segregation, Racial Structure, and Neighborhood Violent Crime
Drawing on structural racism and urban disadvantage approaches, this article posits a broad influence of citywide racial residential segregation on levels of violent crime across all urban neighborhoods regardless of their racial/ethnic composition. Multilevel models based on data from the National Neighborhood Crime Study for 7,622 neighborhoods in 79 cities throughout the United States reveal that segregation is positively associated with violent crime for white and various types of nonwhite neighborhoods. Nonetheless, there is a lack of parity in violence across these types of communities reflecting the larger racialized social system in which whites are able to use their privileged position to reside in the most advantaged neighborhoods, while African-Americans and Latinos live in the most disadvantaged urban communities and therefore bear the brunt of urban criminal violence
LUD, a new protein domain associated with lactate utilization.
BackgroundA novel highly conserved protein domain, DUF162 [Pfam: PF02589], can be mapped to two proteins: LutB and LutC. Both proteins are encoded by a highly conserved LutABC operon, which has been implicated in lactate utilization in bacteria. Based on our analysis of its sequence, structure, and recent experimental evidence reported by other groups, we hereby redefine DUF162 as the LUD domain family.ResultsJCSG solved the first crystal structure [PDB:2G40] from the LUD domain family: LutC protein, encoded by ORF DR_1909, of Deinococcus radiodurans. LutC shares features with domains in the functionally diverse ISOCOT superfamily. We have observed that the LUD domain has an increased abundance in the human gut microbiome.ConclusionsWe propose a model for the substrate and cofactor binding and regulation in LUD domain. The significance of LUD-containing proteins in the human gut microbiome, and the implication of lactate metabolism in the radiation-resistance of Deinococcus radiodurans are discussed
A phase 1a/1b trial of CSF-1R inhibitor LY3022855 in combination with durvalumab or tremelimumab in patients with advanced solid tumors
Background LY3022855 is a recombinant, immunoglobulin, human monoclonal antibody targeting the colony-stimulating factor-1 receptor. This phase 1 trial determined the safety, pharmacokinetics, and antitumor activity of LY3022855 in combination with durvalumab or tremelimumab in patients with advanced solid cancers who had received standard anti-cancer treatments. Methods In Part A (dose-escalation), patients received intravenous (IV) LY3022855 25/50/75/100 mg once weekly (QW) combined with durvalumab 750 mg once every two weeks (Q2W) IV or LY3022855 50 or 100 mg QW IV with tremelimumab 75/225/750 mg once every four weeks. In Part B (dose-expansion), patients with non-small cell lung cancer (NSCLC) or ovarian cancer (OC) received recommended phase 2 dose (RP2D) of LY3022855 from Part A and durvalumab 750 mg Q2W. Results Seventy-two patients were enrolled (median age 61 years): PartA = 33, Part B = 39. In Part A, maximum tolerated dose was not reached, and LY3022855 100 mg QW and durvalumab 750 mg Q2W was the RP2D. Four dose-limiting equivalent toxicities occurred in two patients from OC cohort. In Part A, maximum concentration, area under the concentration-time curve, and serum concentration showed dose-dependent increase over two cycles of therapy. Overall rates of complete response, partial response, and disease control were 1.4%, 2.8%, and 33.3%. Treatment-emergent anti-drug antibodies were observed in 21.2% of patients. Conclusions LY3022855 combined with durvalumab or tremelimumab in patients with advanced NSCLC or OC had limited clinical activity, was well tolerated. The RP2D was LY3022855 100 mg QW with durvalumab 750 mg Q2W
The Chemical Composition Contrast between M3 and M13 Revisited: New Abundances for 28 Giant Stars in M3
We report new chemical abundances of 23 bright red giants of the globular
cluster M3, based on high-resolution spectra obtained with the Keck I
telescope. Combining these data with a previously-reported small sample of M3
giants obtained with the Lick 3m telescope, we compare [X/Fe] ratios for 28 M3
giants with 35 M13 giants, and with halo field stars. All three groups exhibit
C depletion with advancing evolutionary state beginning at the RGB bump region.
but the overall depletion in the clusters is larger than that of the field
stars. The behaviors of O, Na, Mg and Al are distinctively different among the
three stellar samples. Both M3 and M13 show evidence of high-temperature proton
capture synthesis from the ON, NeNa, and MgAl cycles, while there is no
evidence for such synthesis among halo field stars. But the degree of such
extreme proton-capture synthesis in M3 is smaller than it is in M13, and no
indication that O depletions are a function of advancing evolutionary state as
has been claimed for M13. We have also considered NGC 6752, for which Mg
isotopic abundances have been reported by Yong et al. (2003). Giants in NGC
6752 and M13 satisfy the same anticorrelation of O abundances with the ratio
(25Mg+26Mg)/24Mg. This suggests that these abundance ratios arose in the
ejected material of 3-6 solar mass cluster stars. It also suggests that the low
oxygen abundance seen among the most evolved M13 giants arose in hot-bottom O
to N processing in these same intermediate-mass cluster stars. Thus mixing is
required by the dependence of some abundance ratios on luminosity, but an
earlier nucleosynthesis process in a hotter environment than giants or
main-sequence stars is required by the variations previously seen in stars near
the main sequence.Comment: 55 pages, 18 figures, to be published in A
Modeling Mid-Ultraviolet Spectra. I. Temperatures of Metal-Poor Stars
Determining the properties of old stellar systems using evolutionary
population synthesis requires a library of reliable model stellar fluxes.
Empirical libraries are limited to spectra of stars in the solar neighborhood,
with nearly solar abundances and abundance ratios. We report here a first step
towards providing a flux library that includes nonsolar abundances, based on
calculations from first principles that are calibrated empirically. We have
started with main-sequence stars, whose light dominates the mid-ultraviolet
spectrum of an old stellar system. We have calculated mid-ultraviolet spectra
for the Sun and nine nearby, near-main-sequence stars spanning metallicities
from less than 1/100 solar to greater than solar, encompassing a range of
light-element abundance enhancements. We first determined temperatures of eight
of the stars by analyzing optical echelle spectra together with the
mid-ultraviolet. Both could be matched at the same time only when models with
no convective overshoot were adopted, and only when an approximate chromosphere
was incorporated near the surface of relatively metal-rich models. Extensive
modifications to mid-UV line parameters were also required, notably the manual
assignment of approximate identifications for mid-UV lines missing from
laboratory linelists. Without recourse to additional missing opacity, these
measures suffice to reproduce in detail almost the entire mid-UV spectrum of
solar-temperature stars up to one-tenth solar metallicity, and the region from
2900A to 3100A throughout the entire metallicity range. Ramifications for
abundance determinations in individual metal-poor stars and for age-metallicity
determinations of old stellar systems are briefly discussed, with emphasis on
the predictive power of the calculations.Comment: Proof revision -Minor changes to revised version submitted to
Astrophysical Journal May 1, 2001. 29 pages, 4 figures (Fig. 3 with 5 panels
and Fig. 4 with 6 panels). Figures 1 and 2 are .gif; postscript versions of
Figures 1 and 2 are available from
http://www.astro.virginia.edu/~rtr/uv/index.htm
High school boys' and girls' writing conceptions and writing self-efficacy beliefs : what is their role in writing performance?
ABSTRACT: This study investigated the conceptions about writing and writing self-efficacy beliefs held by high school students in relation to the studentsâ gender as well as their associations with writing achievement. The results show that female students have more sophisticated writing conceptions than their male counterparts but no gender differences were found in writing self-efficacy beliefs. In addition, results reveal that writing self-efficacy beliefs and gender play an important role in predicting writing performance and that writing performance is moderated by studentsâ writing conceptions. Educational implications and further research are discussed
WASP-107bâs Density Is Even Lower: A Case Study for the Physics of Planetary Gas Envelope Accretion and Orbital Migration
With a mass in the Neptune regime and a radius of Jupiter, WASP-107b presents a challenge to planet formation theories. Meanwhile, the planet's low surface gravity and the star's brightness also make it one of the most favorable targets for atmospheric characterization. Here, we present the results of an extensive 4 yr Keck/HIRES radial-velocity (RV) follow-up program of the WASP-107 system and provide a detailed study of the physics governing the accretion of the gas envelope of WASP-107b. We reveal that WASP-107b's mass is only 1.8 Neptune masses (M_b = 30.5 ± 1.7 M_â). The resulting extraordinarily low density suggests that WASP-107b has a H/He envelope mass fraction of >85% unless it is substantially inflated. The corresponding core mass of <4.6 M_â at 3Ï is significantly lower than what is traditionally assumed to be necessary to trigger massive gas envelope accretion. We demonstrate that this large gas-to-core mass ratio most plausibly results from the onset of accretion at gsim1 au onto a low-opacity, dust-free atmosphere and subsequent migration to the present-day a_b = 0.0566 ± 0.0017 au. Beyond WASP-107b, we also detect a second, more massive planet (M_c sin i = 0.36 ± 0.04MJ ) on a wide eccentric orbit (e _c = 0.28 ± 0.07) that may have influenced the orbital migration and spinâorbit misalignment of WASP-107b. Overall, our new RV observations and envelope accretion modeling provide crucial insights into the intriguing nature of WASP-107b and the system's formation history. Looking ahead, WASP-107b will be a keystone planet to understand the physics of gas envelope accretion
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