1,227 research outputs found

    Effects of drip irrigation on the yield of strawberry plants grown under arable conditions

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    ArticleThe study investigated the effects of drip irrigation on the yield of ‘Honeoye’ strawberry plants for commercial purposes grown under arable conditions throughout the harvest season. The plants were irrigated at irregular intervals depending on natural precipitation. Crop yields and fruit parameters (diameter, length, individual weight, count per plant) were compared on several harvest dates. Statistical analysis has shown that irrigation has a significant impact on yield and fruit parameters. The irrigated plants yielded more strawberries, which also had a larger diameter, length, and individual weight

    A Galactic O2 If*/WN6 star possibly ejected from its birthplace in NGC3603

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    In this work I report the discovery of a new Galactic O2 If*/WN6 star, a rare member of the extremely massive hydrogen core-burning group of stars that due its high intrinsic luminosity (close to the Eddington limit), possess an emission-line spectrum at the beginning of their main-sequence evolution, mimicking the spectral appearance of classical WR stars. The new star is named WR42e and is found in isolation at 2.7 arcmin (about 6 pc) from the core of the star-burst cluster NGC3603. From the computed E(B-V) color excess and observed visual magnitude it was possible to estimate its absolute visual magnitude as MV =-6.3 mag, which is a value similar to those obtained by other researchers for stars of similar spectral type both, in the Galaxy and in the Large Magellanic Cloud. Considering the derived absolute visual magnitude, we computed a bolometric stellar luminosity of about 3.2x106 Lsun. Finally, the mass of the new O2If*/WN6 star was estimated by comparing its observed magnitudes and colors with those of other probable NGC3603 cluster members, founding that the WR42e initial mass possibly exceeds 100 Msun.Comment: Accepted for publication on MNRAS Letter

    Colorectal cancer in relation to postmenopausal estrogen and estrogen plus progestin in the Women’s Health Initiative clinical trial and observational study

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    Background: Colorectal cancer incidence was reduced among women assigned to active treatment in the Women’s Health Initiative (WHI) estrogen plus progestin randomized trial, but the interpretation was obscured by an associated later stage of diagnosis. In contrast the estrogen-alone trial showed no incidence reduction or differential stage at diagnosis. Here, data from the WHI observational study are considered, in conjunction with colorectal cancer mortality data from the hormone therapy trials, in an attempt to clarify postmenopausal hormone therapy effects. Participants and Methods: Postmenopausal women aged 50-79 at WHI enrollment. Estrogen-alone analyses include 21,552 and 10,739 women who were post-hysterectomy from the observational study and clinical trial respectively. Estrogen plus progestin analyses include 32,084 and 16,608 observational study and clinical trial women with uterus. Colorectal cancers were verified by central medical and pathology report review. Results: Hazard ratios (95% confidence intervals) from the WHI observational study were 0.80 (0.53 to 1.20) for estrogen and 1.15 (0.74 to 1.79) for estrogen plus progestin, with respectively 168 and 175 women diagnosed with colorectal cancer. Delayed diagnosis with estrogen plus progestin is not evident in the observational study. No protective effect on colorectal cancer mortality in the estrogen plus progestin trial is seen over an 8-year intervention and follow-up period. Conclusion: Hazard ratio patterns in the WHI clinical trial and observational study do not provide strong evidence of a clinically important colorectal cancer benefit with either estrogen-alone or estrogen plus progestin over 7-8 years of treatment and follow-up

    Hormone replacement therapy after surgery for stage 1 or 2 cutaneous melanoma

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    A total of 206 women were followed for a minimum of 5 years after primary melanoma surgery to establish if hormone replacement therapy (HRT) adversely affected prognosis. In all, 123 had no HRT and 22 have died of melanoma; 83 had HRT for varying periods and one has died of melanoma. After controlling for known prognostic factors, we conclude that HRT after melanoma does not adversely affect prognosis

    Insulin Resistance and Cancer-Specific and All-Cause Mortality in Postmenopausal Women: The Women\u27s Health Initiative

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    © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For permissions, please email: [email protected]. BACKGROUND: Insulin resistance has been proposed as a mediator of the increased cancer incidence and mortality associated with obesity. However, prior studies included limited cancer deaths and had inconsistent findings. Therefore, we evaluated insulin resistance and cancer-specific and all-cause mortality in postmenopausal women participating in the Women\u27s Health Initiative (WHI). METHODS: Eligible were a subsample of 22 837 WHI participants aged 50-79 years enrolled at 40 US clinical centers from 1993 to 1998 who had baseline fasting glucose and insulin levels. Baseline insulin resistance was measured by the homeostasis model assessment of insulin resistance (HOMA-IR). Cancers were verified by central medical record review and deaths verified by medical record and death certificate review enhanced by National Death Index queries. Cox proportional hazards regression models were used to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for cancer-specific and all-cause mortality. All statistical tests were two-sided. RESULTS: During a median of 18.9 years of follow-up, 1820 cancer deaths and 7415 total deaths occurred. Higher HOMA-IR quartile was associated with higher cancer-specific mortality (Q4 vs Q1, HR = 1.26, 95% CI = 1.09 to 1.47; Ptrend = .003) and all-cause mortality (Q4 vs Q1, HR = 1.63, 95% CI = 1.51 to 1.76; Ptrend \u3c .001). A sensitivity analysis for diabetes status did not change findings. Among women with body mass index less than 25 kg/m2, higher HOMA-IR quartile was associated with higher cancer mortality (Fine and Gray, P = .004). CONCLUSIONS: High insulin resistance, as measured by HOMA-IR, identifies postmenopausal women at higher risk for cancer-specific and all-cause mortality who could potentially benefit from early intervention

    The origin of the runaway high-mass X-ray binary HD153919/4U1700-37

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    Based on its Hipparcos proper motion, we propose that the high-mass X-ray binary HD153919/4U1700-37 originates in the OB association Sco OB1. At a distance of 1.9 kpc the space velocity of 4U1700-37 with respect to Sco OB1 is 75 km/s. This runaway velocity indicates that the progenitor of the compact X-ray source lost about 7 Msun during the (assumed symmetric) supernova explosion. The system's kinematical age is about 2 +/- 0.5 million years which marks the date of the supernova explosion forming the compact object. The present age of Sco OB1 is <8 Myr; its suggested core, NGC 6231, seems to be somewhat younger (~5 Myr). If HD153919/4U1700-37 was born as a member of Sco OB1, this implies that the initially most massive star in the system terminated its evolution within 30 Msun. With these parameters the evolution of the binary system can be constrained.Comment: 6 pages, latex, 3 embedded ps figures, to appear in A&

    Whole Earth Telescope observations of the hot helium atmosphere pulsating white dwarf EC 20058-5234

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    We present the analysis of a total of 177h of high-quality optical time-series photometry of the helium atmosphere pulsating white dwarf (DBV) EC 20058-5234. The bulk of the observations (135h) were obtained during a WET campaign (XCOV15) in July 1997 that featured coordinated observing from 4 southern observatory sites over an 8-day period. The remaining data (42h) were obtained in June 2004 at Mt John Observatory in NZ over a one-week observing period. This work significantly extends the discovery observations of this low-amplitude (few percent) pulsator by increasing the number of detected frequencies from 8 to 18, and employs a simulation procedure to confirm the reality of these frequencies to a high level of significance (1 in 1000). The nature of the observed pulsation spectrum precludes identification of unique pulsation mode properties using any clearly discernable trends. However, we have used a global modelling procedure employing genetic algorithm techniques to identify the n, l values of 8 pulsation modes, and thereby obtain asteroseismic measurements of several model parameters, including the stellar mass (0.55 M_sun) and T_eff (~28200 K). These values are consistent with those derived from published spectral fitting: T_eff ~ 28400 K and log g ~ 7.86. We also present persuasive evidence from apparent rotational mode splitting for two of the modes that indicates this compact object is a relatively rapid rotator with a period of 2h. In direct analogy with the corresponding properties of the hydrogen (DAV) atmosphere pulsators, the stable low-amplitude pulsation behaviour of EC 20058 is entirely consistent with its inferred effective temperature, which indicates it is close to the blue edge of the DBV instability strip. (abridged)Comment: 19 pages, 8 figures, 5 tables, MNRAS accepte

    The planetary system host HR\,8799: On its λ\lambda Bootis nature

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    HR\,8799 is a λ\lambda Bootis, γ\gamma Doradus star hosting a planetary system and a debris disk with two rings. This makes this system a very interesting target for asteroseismic studies. This work is devoted to the determination of the internal metallicity of this star, linked with its λ\lambda Bootis nature (i.e., solar surface abundances of light elements, and subsolar surface abundances of heavy elements), taking advantage of its γ\gamma Doradus pulsations. This is the most accurate way to obtain this information, and this is the first time such a study is performed for a planetary-system-host star. We have used the equilibrium code CESAM and the non-adiabatic pulsational code GraCo. We have applied the Frequency Ratio Method (FRM) and the Time Dependent Convection theory (TDC) to estimate the mode identification, the Brunt-Va\"is\"al\"a frequency integral and the mode instability, making the selection of the possible models. When the non-seismological constraints (i.e its position in the HR diagram) are used, the solar abundance models are discarded. This result contradicts one of the main hypothesis for explaining the λ\lambda Bootis nature, namely the accretion/diffusion of gas by a star with solar abundance. Therefore, according to these results, a revision of this hypothesis is needed. The inclusion of accurate internal chemical mixing processes seems to be necessary to explain the peculiar abundances observed in the surface of stars with internal subsolar metallicities. The use of the asteroseismological constraints, like those provided by the FRM or the instability analysis, provides a very accurate determination of the physical characteristics of HR 8799. However, a dependence of the results on the inclination angle ii still remains. The determination of this angle, more accurate multicolour photometric observations, and high resolution spectroscopy can definitively fix the mass and metallicity of this star.Comment: 11 pages, 10 figures. Accepted for publication in MNRA
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