1,034 research outputs found

    Surface properties of Galilean satellites from bistatic radar experiments

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    The icy moons of Jupiter were the first to show unusual radar backscatter behavior in Earth-based experiments. Studies of Europa, Ganymede, and Callisto revealed strong echoes and a reversed sense of circular polarization. No explanations were entirely satisfactory because of the difficult constraints imposed by the existing data. The (scalar) bidirectional coherence model predicts an opposition effect, or enhancement in the backscatter direction, resulting from coherent addition of backscatter from identical (but oppositely directed) ray paths. The mode decoupling model yields a similar, vector result in which the observed polarization properties of the backscattered wave can also be obtained. The possibilities were considered for conducting such experiments using the Galileo spacecraft. Both conventional oblique-forward bistatic experiments (to determine basic electrical and physical properties of the surface material on centimeter-meter scales) and near-backscatter experiments (to sample the enhanced backscatter lobe) were considered

    Stanford telemetry monitoring experiment on Lunar Explorer 35 Final report

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    Explorer 35 data analysis including occultation study and antenna pattern interpretation along with electromagnetic property experiment

    Scattering properties of Venus' surface

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    Radar backscatter functions Sigma-(carat)(sub 0)(phi) for incidence angles between 0 less than or equal to phi less than or equal to 4-10 deg were derived from Magellan altimetry radar echoes. The procedure includes constrained solution of a system of simultaneous equations for which the echo-spectrum and echo time profile are inputs. A practical and workable set of constraints was applied; optimization and improved results are expected as the analysis matures. The scattering functions yield information on small-scale surface structures (tens of centimeters to tens of meters) but averaged over hundreds of sq km. RMS surface slopes derived from fits of analytic functions to the Sigma-(carat)(sub 0)(phi) results were converted to map form and show patterns similar to those reported using other techniques. While all three forms are found on Venus, fit residuals imply that an exponential scattering function matches data better than either the Hagfors or Gaussian form in most areas, although the Hagfors function may be a better descriptor at some sites. Limited study of image data indicates that average backscatter cross section, and possibly its slope, can be derived at oblique angles (17 deg less than or equal to phi less than or equal to 45 deg). Offsets of the echo peak in altimetry spectra are surprisingly common and are loosely correlated with Venus topography, but no cause for this phenomenon was identified

    Bistatic-radar studies of the moon with Explorer 35. Part 2 - Methods of data reduction and reduced observations Final report

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    Bistatic-radar data reduction and Explorer 35 reflectivity and bandwidth tables with polarization spectr

    Assessing the Sensitivity of Different Life Stages for Sexual Disruption in Roach (Rutilus rutilus) Exposed to Effluents from Wastewater Treatment Works

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    Surveys of U.K. rivers have shown a high incidence of sexual disruption in populations of wild roach (Rutilus rutilus) living downstream from wastewater treatment works (WwTW), and the degree of intersex (gonads containing both male and female structural characteristics) has been correlated with the concentration of effluent in those rivers. In this study, we investigated feminized responses to two estrogenic WwTWs in roach exposed for periods during life stages of germ cell division (early life and the postspawning period). Roach were exposed as embryos from fertilization up to 300 days posthatch (dph; to include the period of gonadal sex differentiation) or as postspawning adult males, and including fish that had received previous estrogen exposure, for either 60 or 120 days when the annual event of germ cell proliferation occurs. Both effluents induced vitellogenin synthesis in both life stages studied, and the magnitude of the vitellogenic responses paralleled the effluent content of steroid estrogens. Feminization of the reproductive ducts occurred in male fish in a concentration-dependent manner when the exposure occurred during early life, but we found no effects on the reproductive ducts in adult males. Depuration studies (maintenance of fish in clean water after exposure to WwTW effluent) confirmed that the feminization of the reproductive duct was permanent. We found no evidence of ovotestis development in fish that had no previous estrogen exposure for any of the treatments. In wild adult roach that had previously received exposure to estrogen and were intersex, the degree of intersex increased during the study period, but this was not related to the immediate effluent exposure, suggesting a previously determined programming of ovotestis formation

    Limited tumor infiltration by activated T effector cells restricts the therapeutic activity of regulatory T cell depletion against established melanoma

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    Interference with inhibitory immunological checkpoints controlling T cell activation provides new opportunities to augment cancer immunotherapies. Whereas cytotoxic T lymphocyte–associated antigen-4 blockade has shown promising preclinical and clinical results, therapeutic CD4+CD25+ T reg cell depletion has failed to consistently enhance immune-based therapies. Using B16/BL6, a transplantable murine melanoma model, we show a dichotomy between the effects of T reg cell depletion on tumor rejection dependent on whether depletion occurs before (prophylactic) or after (therapeutic) tumor engraftment. Failure to promote rejection with therapeutic depletion is not related to lack of T reg cell depletion, to elimination of CD25+ effector T cells, or to a failure to enhance systemic antitumor T cell responses, but correlates with failure of effector cells to infiltrate the tumor and increase the intratumor ratio of effector T cell/T reg cell. Finally, systemic antitumor responses generated upon therapeutic T reg cell depletion are significantly stronger than those generated in the presence of T reg cells, and are capable of eliciting rejection of established tumors after transfer into immunoablated recipients receiving combination immunotherapy. The data demonstrate a dissociation between measurable systemic responses and tumor rejection during CD25-directed T reg cell depletion, and suggest an alternative, clinically applicable strategy for the treatment of established tumors

    Intensive Referral of Veterans to Mutual-Help Groups: A Mixed-Methods Implementation Evaluation

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    Community-based support group participation protects against substance use disorder (SUD) relapse, but referrals during treatment are inconsistently delivered and may not acknowledge barriers facing rural patients. This formative evaluation of a rural intensive referral intervention (RAIR) to community-based support groups for veterans seeking SUD treatment surveyed patients (N = 145) and surveyed and interviewed treatment staff (N = 28). Patients and staff did not differ significantly on quantitative ratings of the helpfulness of, or satisfaction with, seven RAIR components, but staff did not deliver the intervention consistently or as designed, citing two themes: lack of commitment and lack of resources

    Intensive Referral to Mutual-Help Groups: A Field Trial of Adaptations for Rural Veterans

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    Objective: A multisite field trial testing whether improved outcomes associated with intensive referral to mutual help groups (MHGs) could be maintained after the intervention was adapted for the circumstances and needs of rural veterans in treatment for substance use disorder (SUD). Methods: In three Veterans Affairs treatment programs in the Midwest, patients (N = 195) received standard referral (SR) or rural-adapted intensive referral (RAIR) and were measured at baseline and 6-month follow-up. Results: Both groups reported significant improvement at 6 months but no significant differences between SR and RAIR groups in MHG participation, substance use, addiction severity, and posttraumatic stress symptoms. Inconsistent delivery of the intervention resulted in only one-third of the RAIR group receiving the full three sessions, but this group reported significantly greater 6-month abstinence from alcohol than those receiving no sessions. Conclusion: Further research should explore implementation problems and determine whether consistent delivery of the intervention enhances 12-step facilitation. Practice implications: The addition of rural-specific elements to the original intensive referral intervention has not been shown to increase its effectiveness among rural veterans

    Clubbing masculinities: Gender shifts in gay men's dance floor choreographies

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    This is an Author's Accepted Manuscript of an article published in Journal of Homosexuality, 58(5), 608-625, 2011 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/00918369.2011.563660This article adopts an interdisciplinary approach to understanding the intersections of gender, sexuality, and dance. It examines the expressions of sexuality among gay males through culturally popular forms of club dancing. Drawing on political and musical history, I outline an account of how gay men's gendered choreographies changed throughout the 1970s, 80s, and 90s. Through a notion of “technologies of the body,” I situate these developments in relation to cultural levels of homophobia, exploring how masculine expressions are entangled with and regulated by musical structures. My driving hypothesis is that as perceptions of cultural homophobia decrease, popular choreographies of gay men's dance have become more feminine in expression. Exploring this idea in the context of the first decade of the new millennium, I present a case study of TigerHeat, one of the largest weekly gay dance club events in the United States

    DDO 43: A Prototypical Dwarf Irregular Galaxy?

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    We present sensitive and high resolution 21 cm observations of the dwarf irregular (dIm) galaxy DDO 43, in conjunction with optical broad and narrow band images in U, B, V, and Halpha. The observations are used to examine the relationship between its HI morphology and kinematics to past and present star formation. Optically, it is a small (R_25 = 990 pc), faint (M_B of -14.0) Im with a slightly boxy shape. In HI, DDO 43 has an extended (R_HI/R_Ho = 2.8) gas envelope. There is a high density ridge associated with the optical body of the galaxy, containing several higher density knots and lower density holes. The largest hole is ~850x530 pc. No expansion is detected, so it must be relatively old. The largest and potentially oldest (7-70 Myr) of the six identified star clusters is located at the western edge of the hole. Four of the other clusters are located near high density peaks. There are several HII regions, most of which are associated with peaks in the HI surface density. The overall star formation rate is average for its type. In many ways, DDO 43 is a very typical dwarf irregular galaxy. Its HI morphology is consistent with a history of episodes of localized star ormation that create holes and shells in the ISM, some of which can overlap. These features are located within the area of solid-body rotation in the galaxy; the lack of shear in these small systems allows such structures to persist for long periods of time.Comment: 50 pages, 22 figures, accepted by The Astronomical Journal, available at http://www.fiu.edu/~simpsonc/d43
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