Effects of Zoledronate During Simulated Weightlessness on Bone Structure and Mechanics

Spaceflight causes astronauts to experience an unbalanced level of bone remodeling favoring resorption. The combination of an antiresorptive drug and weightlessness may have negative effects on the mechanical and structural properties of bone by increasing elastic stiffness but diminishing plasticity. At 16 weeks of age, skeletally postpubescent male mice (n = 32, C57BL/6) were evenly divided and subcutaneously given either zoledronate (45 µg/kg) or vehicle (saline, same volume). Three days postinjection, half of each group were divided to undergo 3 weeks of hindlimb unloading or act as a control undergoing normal ambulation (n = 8 for each of the 4 groups). Ex vivo µCT assays showed zoledronate preserving cancellous mineral, bone, and cortical bone. Hindlimb unloading reduced cortical bone. Three-point bending of the femoral mid-shaft showed zoledronate increased stiffness, ultimate force, and total energy (+28%, +17%, +15%, respectively). Hindlimb unloading reduced stiffness but increased postyield displacement, a measurement of plasticity (-29%, +20%, respectively). The combined treatment resulted in increased stiffness, with zoledronate not modulating the hindlimb unloading main effect on postyield displacement. Though stiffness increased, contrary to the hypothesis, the combination of zoledronate and hindlimb unloading did not result in a decreased plasticity

Pulpits and Platforms: The Role of the Church in Determining Protest among Black Americans

This article further specifies the relationship between church-based resources, group identification and political activism among black Americans. Previous research indicates that political communication within churches and activism within the church serve to motivate political participation. Our research suggests that, net of relevant controls, activism within the church does not significantly increase protest politics. A key determinant of protest participation is attending a church that exhibits a politicized church culture, and this effect is contingent upon educational attainment and membership in secular organizations.Hence, the church serves as a crucial context for the dissemination of political messages and exposure to opportunities for protest only for those black Americans with relatively low educational achievement and organizational involvement. Group identification has no effect on protest participation

Bioinformatic Comparison of Genes in the Leucine Biosynthesis Pathway of \u3cem\u3eEscherichia coli\u3c/em\u3e to \u3cem\u3eMeiothermus ruber\u3c/em\u3e

We predict that Mrub_1905 and Mrub_1906 encode the enzyme 2-isopropylmalate synthase (Mrub_1906 DNA coordinates complement(1965044..1966603) Mrub_1905 DNA coordinates complement(1963455..1965041)), which is the first step of the leucine biosynthesis pathway (KEGG map number 00290). It catalyzes the conversion of (2S)-2-isopropylmalate to 2-isopropylmaleate. The E. coli K12 MG1655 ortholog is predicted to be b0074, which has the gene identifier leuA. We predict that Mrub_1846 encodes the enzyme 3-isopropylmalate dehydrogenase (DNA coordinates complement(1903909..1904961)), which is the third step of the leucine biosynthesis pathway (KEGG map number 00290). It catalyzes the conversion of (2R,3S)-3-isopropylmalate to (2S)-2-isopropyl-3-oxosuccinate. The E. coli K12 MG1655 ortholog is predicted to be b0073, which has the gene identifier leuB. We predict that Mrub_1850 encodes for 3-isopropylmalate dehydratase (DNA coordinates complement(1906426..1907850)), the large subunit of the heteromeric enzyme, which is the second step of the leucine biosynthesis pathway (KEGG map number 00290). It catalyzes the conversion of (2S)-2-isopropylmalate to (2R,3S)-3-isopropylmalate. The E. coli K12 MG1655 ortholog is predicted to be b0072, which has the gene identifier leuC. We predict that Mrub_1847 encodes the enzyme isopropylmalate isomerase (DNA coordinates complement(1904975..1905580)), the small subunit of the heteromeric enzyme, which is the second step of the leucine biosynthesis pathway (KEGG map number 00290). It catalyzes the conversion of (2S)-2-isopropylmalate to (2R,3S)-3-isopropylmalate. The E. coli K12 MG1655 ortholog is predicted to be b0071, which has the gene identifier leuD

Stray Light Modeling of the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM)

This paper describes an integrated stray light model of each Science Instrument (SI) in the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) and the Optical Telescope Element Simulator (OSIM), the light source used to characterize the performance of ISIM in cryogenic-vacuum tests at the Goddard Space Flight Center (GSFC). We present three cases where this stray light model was integral to solving questions that arose during the testing campaign - 1) ghosting and coherent diffraction from hardware surfaces in the Near Infrared Imager and Slitless Spectrograph (NIRISS) GR700XD grism mode, 2) ghost spots in the Near Infrared Camera (NIRCam) GRISM modes, and 3) scattering from knife edges of the NIRCam focal plane array masks

Countdown to the Future

At the NASA Ames Research Center in California, the next generation of space biologists are working to understand the effects of long duration space flight on model organisms, and are developing ways to protect the health of future astronauts

Approximating the inspiral of test bodies into Kerr black holes

We present a new approximate method for constructing gravitational radiation driven inspirals of test-bodies orbiting Kerr black holes. Such orbits can be fully described by a semi-latus rectum $p$, an eccentricity $e$, and an inclination angle $\iota$; or, by an energy $E$, an angular momentum component $L_z$, and a third constant $Q$. Our scheme uses expressions that are exact (within an adiabatic approximation) for the rates of change ($\dot{p}$, $\dot{e}$, $\dot{\iota}$) as linear combinations of the fluxes ($\dot{E}$, $\dot{L_z}$, $\dot{Q}$), but uses quadrupole-order formulae for these fluxes. This scheme thus encodes the exact orbital dynamics, augmenting it with approximate radiation reaction. Comparing inspiral trajectories, we find that this approximation agrees well with numerical results for the special cases of eccentric equatorial and circular inclined orbits, far more accurate than corresponding weak-field formulae for ($\dot{p}$, $\dot{e}$, $\dot{\iota}$). We use this technique to study the inspiral of a test-body in inclined, eccentric Kerr orbits. Our results should be useful tools for constructing approximate waveforms that can be used to study data analysis problems for the future LISA gravitational-wave observatory, in lieu of waveforms from more rigorous techniques that are currently under development.Comment: 15 pages, 5 figures, submitted to PR

Bupropion Reduces Some of the Symptoms of Marihuana Withdrawal in Chronic Marihuana Users: A Pilot Study

Bupropion’s (Zyban® SR) effectiveness to treat symptoms experienced in marihuana withdrawal was tested in a double-blind, placebo-controlled study with chronic, heavy marihuana users. Participants maintained their usual marihuana intake until Quit Day after which they were required to cease intake of THC products for 14 days. A Withdrawal Discomfort Score revealed that for 7 days immediately following cessation, placebo-treated subjects reported more symptoms than bupropion-treated subjects. Self-reported craving for marihuana increased for the placebo-treated group but not for those treated with bupropion. Measures of sleep and cognitive performance were not different between the two groups. Participants in the bupropion treatment arm were more likely to complete the study than those randomized to the placebo arm (50% completion for bupropion vs. 33% completion for placebo). These results suggest that bupropion may be useful for alleviating marihuana withdrawal symptoms and be useful in subject retention during long-term cessation programs