3,564 research outputs found

    Near-Infrared Survey of the GOODS-North Field: Search for Luminous Galaxy Candidates at z=>6.5

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    We present near-infrared (NIR; J & Ks) survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field. The publicly available imaging data were obtained using the MOIRCS instrument on the 8.2m Subaru and the WIRCam instrument on the 3.6m Canada-France-Hawaii Telescope (CFHT). These observations fulfill a serious wavelength gap in the GOODS-N data - i.e., lack of deep NIR observations. We combine the Subaru/MOIRCS and CFHT/WIRCam archival data to generate deep J and Ks band images, covering the full GOODS-N field (~169 sq. arcmin) to an AB magnitude limit of ~25 mag (3sigma). We applied z'-band dropout color selection criteria, using the NIR data generated here. We have identified two possible Lyman Break Galaxy (LBG) candidates at z\gtrsim6.5 with J\lesssim24.5. The first candidate is a likely LBG at z\sim6.5 based on a weak spectral feature tentatively identified as Lyalpha line in the deep Keck/DEIMOS spectrum, while the second candidate is a possible LBG at z\sim7 based on its photometric redshift. These z'-dropout objects, if confirmed, are among the brightest such candidates found so far. At z\gtrsim6.5, their star formation rate is estimated as 100-200 solar mass per year. If they continue to form stars at this rate, they assemble a stellar mass of ~5x10^10 solar mass after about 400 million years, becoming the progenitors of massive galaxies observed at z\sim5. We study the implication of the z'-band dropout candidates discovered here, in constraining the bright-end of the luminosity function and understanding the nature of high redshift galaxies.Comment: ApJ in press, minor text/reference update

    The Stellar Masses and Star Formation Histories of Galaxies at z ≈ 6: Constraints from Spitzer Observations in the Great Observatories Origins Deep Survey

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    Using the deep Spitzer Infrared Array Camera (IRAC) observations of the Great Observatories Origins Deep Survey (GOODS), we study the stellar masses and star formation histories of galaxies at z approx 6 based on the i_(775)-band dropout sample selected from the GOODS fields. In total, we derive stellar masses for 53 i_(775)-band dropouts that have robust IRAC detections. These galaxies have typical stellar masses of ~10^(10) M_⊙ and typical ages of a couple of hundred million years, consistent with earlier results based on a smaller sample of z ≈ 6 galaxies. The existence of such massive galaxies at z ≈ 6 can be explained by at least one set of N-body simulations of the hierarchical paradigm. We also study 79 i_(775)-band dropouts that are invisible in the IRAC data and find that they are typically less massive by a factor of 10. These galaxies are much bluer than those detected by the IRAC, indicating that their luminosities are dominated by stellar populations with ages ≾ 40 Myr. Based on our mass estimates, we derive a lower limit to the global stellar mass density at z ≈ 6, which is 1.1-6.7 × 10^6 M_⊙ Mpc^(-3). The prospect of detecting the progenitors of the most massive galaxies at yet higher redshifts is explored. We also investigate the implication of our results for reionization and find that the progenitors of the galaxies comparable to those in our sample, even in the most optimized (probably unrealistic) scenario, cannot sustain the reionization for a period longer than ~2 Myr. Thus most of the photons required for reionization must have been provided by other sources, such as the progenitors of the dwarf galaxies that are far below our current detection capability

    Analysis of margin classification systems for assessing the risk of local recurrence after soft tissue sarcoma resection

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    Purpose: To compare the ability of margin classification systems to determine local recurrence (LR) risk after soft tissue sarcoma (STS) resection. Methods: Two thousand two hundred seventeen patients with nonmetastatic extremity and truncal STS treated with surgical resection and multidisciplinary consideration of perioperative radiotherapy were retrospectively reviewed. Margins were coded by residual tumor (R) classification (in which microscopic tumor at inked margin defines R1), the R+1mm classification (in which microscopic tumor within 1 mm of ink defines R1), and the Toronto Margin Context Classification (TMCC; in which positive margins are separated into planned close but positive at critical structures, positive after whoops re-excision, and inadvertent positive margins). Multivariate competing risk regression models were created. Results: By R classification, LR rates at 10-year follow-up were 8%, 21%, and 44% in R0, R1, and R2, respectively. R+1mm classification resulted in increased R1 margins (726 v 278, P < .001), but led to decreased LR for R1 margins without changing R0 LR; for R0, the 10-year LR rate was 8% (range, 7% to 10%); for R1, the 10-year LR rate was 12% (10% to 15%) . The TMCC also showed various LR rates among its tiers (P < .001). LR rates for positive margins on critical structures were not different from R0 at 10 years (11% v 8%, P = .18), whereas inadvertent positive margins had high LR (5-year, 28% [95% CI, 19% to 37%]; 10-year, 35% [95% CI, 25% to 46%]; P < .001). Conclusion: The R classification identified three distinct risk levels for LR in STS. An R+1mm classification reduced LR differences between R1 and R0, suggesting that a negative but < 1-mm margin may be adequate with multidisciplinary treatment. The TMCC provides additional stratification of positive margins that may aid in surgical planning and patient education

    The Space Weather Threat to Situational Awareness, Communications, and Positioning Systems

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    A recent space weather headline has cast doubt in the minds of some as to whether space weather is the source of spacecraft anomalies, and thus, whether it is important in the design and operation of critical situational awareness, communications, and positioning systems. In this paper, we reiterate the evidence for the importance of space weather, its role in producing spacecraft and ground anomalies, and the threat it poses to critical systems. In addition, we report new studies broken down by anomaly types and suggest the sources of the anomalies (surface charging or interior charging). Finally, we suggest spacecraft charging and ground effects mitigation strategies for design and operations of systems critical to our modern civilization

    Vertical Distribution, Persistence, and Activity of Entomopathogenic Nematodes (Nematoda: Heterorhabditidae and Steinernematidae) in Alfalfa Snout Beetle- (Coleoptera: Curculionidae) Infested Fields

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    The vertical movement, persistence, and activity of four isolates of entomopathogenic nematodes, Heterorhabditis bacteriophora Poinar (Oswego), Heterorhabditis bacteriophora Poinar (NC), Steinernema carpocapsae (Weiser) (NY001),and an undescribed Steinernema species (NY008-2E), were evaluated for 24 mo at field locations in northern New York. Nematodes were released into three alfalfa fields naturally infested with alfalfa snout beetle, Otiorhynchus ligustici (L.). Each field differed in soil type and soil textural composition: silt loam, sandy loam, and loamy sand. Nematodes were recovered from soil using trap insects, Galleria mellonella larvae, and their vertical distribution was monitored at 5-cm intervals to depths of 20 cm for Steinernena species and 35 cm for Heterorhabditis species. All nematodes persisted (no significant reduction in percentage of infection of G. mellonella) for 6 mo after the initial application in all soil types. However, by the end of the second growing season (17 mo after application), all nematodes showed significant reductions in infection rates of G. mellonella except H. bacteriophora (Oswego) which showed high levels of infection for 24 mo. Nematode vertical movement was affected by soil type and varied by isolate. S. carpocapsae (NY00l)and Steinernema sp. (NY008-2E) remained primarily in soil depths <15 cm, whereas both heterorhabditids dispersed to soil depths of 35 cm. Vertical movement of H. bacteriophera (Oswego) was greatest in loamy sand and vertical movement of Steinernema sp. (NY008-2E) was greatest in sandy loam. Percentage of infection of G. mellonella by H. bacteriophora (Oswego) and S. carpocapsae (NY00l)was significantly correlated with rising soil temperatures in early spring. H. bacteriophora (Oswego) and S. carpocapsae (NYOOl)infected G. mellonella larvae in the field at soil temperatures between 15 and 18°C. Steinernema sp. (NY008-2E)infected G. mellonella larvae in the field at soil temperatures between 13 and 15°

    Lifelong behavioral and neuropathological consequences of repetitive mild traumatic brain injury

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    Objective: Exposure to repetitive concussion, or mild traumatic brain injury (mTBI), has been linked with increased risk of long-term neurodegenerative changes, specifically chronic traumatic encephalopathy (CTE). To date, preclinical studies largely have focused on the immediate aftermath of mTBI, with no literature on the lifelong consequences of mTBI in these models. This study provides the first account of lifelong neurobehavioral and histological consequences of repetitive mTBI providing unique insight into the constellation of evolving and ongoing pathologies with late survival. Methods: Male C57BL/6J mice (aged 2–3 months) were exposed to either single or repetitive mild TBI or sham procedure. Thereafter, animals were monitored and assessed at 24 months post last injury for measures of motor coordination, learning deficits, cognitive function, and anxiety-like behavior prior to euthanasia and preparation of the brains for detailed neuropathological and protein biochemical studies. Results: At 24 months survival animals exposed to r-mTBI showed clear evidence of learning and working memory impairment with a lack of spatial memory and vestibule-motor vestibulomotor deficits compared to sham animals. Associated with these late behavioral deficits there was evidence of ongoing axonal degeneration and neuroinflammation in subcortical white matter tracts. Notably, these changes were also observed after a single mTBI, albeit to a lesser degree than repetitive mTBI. Interpretation: In this context, our current data demonstrate, for the first time, that rather than an acute, time limited event, mild TBI can precipitate a lifelong degenerative process. These data therefore suggest that successful treatment strategies should consider both the acute and chronic nature of mTBI

    GOODS Spitzer IRAC Observations of High-z Galaxies

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    The Great Observatory Origins Deep Survey (GOODS) Spitzer Legacy Program has obtained ~23.2 hours of IRAC observations in the HDF-N and the CDF-S (~330 arcmin^2 in total), among which a sub-area of ~50 arcmin^2 in the HDF-N has been observed to a depth of ~72 hours. Utilizing these deep IRAC data, we study the stellar masses and star formation histories of galaxies at z ≈ 6. While some of the i-band dropouts selected by the GOODS ACS observations are detected by these IRAC observations, some of them are not. We find that the i_(775)-dropouts in the IRAC-detected sample typically have stellar masses of ~10^(10)M_⊙ and ages of a few hundred million years old, consistent with our earlier results based on a smaller sample in the HUDF. On the other hand, the i-dropouts in the IRAC-invisible sample are significantly younger and less massive. Using these results, we derive the lower limit of the global stellar density at z ≈ 6, and find that at least 0.2–1.1% of the stellar mass in our local universe has been locked in stars by z ≈ 6

    Anticipated Regret and Organ Donor Registration: a randomised controlled trial

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    Objective: To test whether simply asking people to rate the extent to which they anticipate feeling regret for not registering as an organ donor after death increases subsequent verified organ donor registration.&nbsp; Methods: 14,509 members of the general public (both registered and non-registered donors) were randomly allocated to 1 of 4 arms, each receiving different questionnaires. The no-questionnaire control (NQC) arm received a survey measuring demographics and whether or not they were registered organ donors. The questionnaire control (QC) arm completed the NQC questions plus questions regarding affective attitudes and intention to register as an organ donor. The theory of planned behaviour (TPB) questionnaire arm received the QC questionnaire, plus additional items measuring TPB variables. The anticipated regret (AR) arm received the TPB questionnaire, plus two additional items measuring anticipated regret. The main outcome measures were number of non-donor participants who subsequently registered six months later, as verified by the UK national transplant register.&nbsp; Results: Intention-to-treat (ITT) analysis in non-registered donors (N = 9,139) revealed the NQC arm were more likely to register as an organ donor (6.39%) compared to the AR (4.51%) arm.&nbsp; Conclusions: A brief anticipated regret intervention led to a decrease in registration. A potential reason is discussed in terms of questionnaire item content &ldquo;priming&rdquo; negative perceptions of organ donation. This is a methodological concern that needs to be addressed in studies that use similar interventions. Current controlled trials: www.controlled-trials.com number: ISRCTN922048897

    Greenhouse and Field Evaluations of Entomopathogenic Nematodes (Nematode: Heterorhabditidae and Steinernematidae) for Control of Cabbage Maggot (Diopters: Anthomyiidae) on Cabbage

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    Entomb pathogenic nematodes-Heterorhabditis bacteriophora Poinar (Oswego strain), Steinenema carpocapsae (Weiser) (NY001 strain), Steinemema carpocapsae (25 strain), Steinemema feltiae Filipjev (=Neoaplectana carpocapsae Weiser) (369 strain), Steinernema feltiae (27 strain), and Steinernema riobravus Cabanillas and Poinar (355 strain)-were examined for pathogenicity against cabbage maggot, Delia radicum (L.), larvae in the greenhouse and field. Applications (per plant) of 3,000 and 4,000 infective juveniles of S. feltiae (369 strain), 30,000 infective juveniles of H. bacteriophora (Oswego strain), and 300 and 30,000 infective juveniles of S. feltiae (27 strain) reduced the number of D. radicum that developed to pupae on potted cabbage plants. H. bacteriophora (Oswego) at applications of 3,000 and 30,000 infective juveniles per plant and S. feltiae (27 strain) at applications of 30,000 (but not 3,000) infective juveniles per plant significantly reduced root damage caused by larvae of D. radicum. Logarithmically increased dosages between 100 and 100,000 infective juveniles per plant of S. feltiae (27 strain) linearly reduced the number of D. radicum pupae that developed on potted cabbage plants and the damage caused to the roots by D. radicullarvae. Root and stem dry weights of cabbage plants infested with D. radicum were significantly greater for plants inoculated with 100,000 infective juveniles of S. feltiae (27 strain) than for plants not inoculated with nematodes. Nematode inoculation did not prevent significant losses in root or stem dry weights at dosages less than 100,000 infective juveniles per plant. Soil surface applications of 100,000 and 200,000 infective juveniles per plant of S. feltiae (27 strain) were more effective than subsurface applications in preventing damage by natural or augmented populations of D. radicum larvae on cabbage in the field. However, mortality rates of wax moth larvae exposed to soil samples treated with S. feltiae (27 strain) suggested that this nematode showed greater persistence when applied beneath rather than on the soil surfac
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