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Planets with short orbital periods (roughly under 10 days) are common around stars like the Sun1,2. Stars expand as they evolve and thus we expect their close planetary companions to be engulfed, possibly powering luminous mass ejections from the host star3-5. However, this phase has never been directly observed. Here we report observations of ZTF SLRN-2020, a short-lived optical outburst in the Galactic disk accompanied by bright and long-lived infrared emission. The resulting light curve and spectra share striking similarities with those of red novae6,7-a class of eruptions now confirmed8 to arise from mergers of binary stars. Its exceptionally low optical luminosity (approximately 1035 erg s-1) and radiated energy (approximately 6.5 × 1041 erg) point to the engulfment of a planet of fewer than roughly ten Jupiter masses by its Sun-like host star. We estimate the Galactic rate of such subluminous red novae to be roughly between 0.1 and several per year. Future Galactic plane surveys should routinely identify these, showing the demographics of planetary engulfment and the ultimate fate of planets in the inner Solar System.
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Protoplanetary disks are known to possess a variety of substructures in the distribution of their millimetre-sized grains, predominantly seen as rings and gaps1, which are frequently interpreted as arising from the shepherding of large grains by either hidden, still-forming planets within the disk2 or (magneto-)hydrodynamic instabilities3. The velocity structure of the gas offers a unique probe of both the underlying mechanisms driving the evolution of the disk-such as movement of planet-building material from volatile-rich regions to the chemically inert midplane-and the details of the required removal of angular momentum. Here we report radial profiles of the three velocity components of gas in the upper layers of the disk of the young star HD 163296, as traced by emission from 12CO molecules. These velocities reveal substantial flows from the surface of the disk towards its midplane at the radial locations of gaps that have been argued to be opened by embedded planets4-7: these flows bear a striking resemblance to meridional flows, long predicted to occur during the early stages of planet formation8-12. In addition, a persistent radial outflow is seen at the outer edge of the disk that is potentially the base of a wind associated with previously detected extended emission12.
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BACKGROUND: Women living with HIV are a minority population with unique care needs. Rates of unintended pregnancy are higher among women living with HIV versus HIV negative women. However, uptake of contraception among women living with HIV including long-acting-reversible contraceptives (LARCs) remains low. This quality improvement project aimed to identify gaps in reproductive healthcare for women living with HIV attending Melbourne Sexual Health Centre (MSHC). METHODS: We performed a retrospective review of women living with HIV attending MSHC for HIV care February 2019-February 2020. Women aged over 45years were excluded. Primary outcomes included proportion using contraception, methods used and whether a sexual or reproductive health history had been taken in the past year. RESULTS: A total of 100 women were included, predominantly born overseas (Asia, 38%; sub-Saharan Africa, 34%). Of these, 5% were pregnant, 16% were trying to conceive and 1% were undergoing elective oocyte preservation. Of the remaining 74 women, 48.6% were using any form of contraception, including 17.6% women using less-effective methods (withdrawal and condoms), 6.8% using the combined oral contraceptive pill, 18.9% using LARCs and 5.4% using permanent methods. Sexual activity status was documented for 61% women, 1% declined to answer and not documented for 38% women. CONCLUSIONS: Rate of contraceptive use in this study was lower than previously reported among women living with HIV in Australia; however, our findings suggest contraceptive methods may be changing in light of undetectable equals untransmittable and increased fertility desires. Discussions regarding sexual activity and reproductive health were limited. Mechanisms to increase clinician-patient discourse regarding these important issues should be explored.
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Infecções por HIV , Saúde Sexual , Gravidez , Feminino , Humanos , Saúde Reprodutiva , Anticoncepção , Comportamento Sexual , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , Comportamento ContraceptivoRESUMO
We examine Adaptive Multi-Paddock (AMP) grazed with short grazing events and planned recovery periods and paired ranches using Conventional Continuous Grazing (CG) at low stock density on vegetation, water infiltration, and soil carbon across SE USA. Increased vegetation standing biomass and plant species dominance-diversity were measured in AMP grazed ranches. Invasive perennial plant species richness and abundance increased with AMP grazing in the south, while in the north they increased on CG grazed ranches. Percent bare ground was significantly greater in CG at the Alabama and Mississippi sites, no different at the Kentucky and mid-Alabama sites, and greater on AMP at the Tennessee pair. On average, surface water infiltration was higher on AMP than paired CG ranches. Averaged over all locations, soil organic carbon stocks to a depth of 1 m were over 13% greater on AMP than CG ranches, and standing crop biomass was >300% higher on AMP ranches. AMP grazing supported substantially higher livestock stocking levels while providing significant improvements in vegetation, soil carbon, and water infiltration functions. AMP grazing also significantly increased available forage nutrition for key constituents, and increased soil carbon to provide significant resource and economic benefits for improving ecological health, resilience, and durability of the family ranch.
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Carbono , Solo , Biomassa , Ecossistema , ÁguaRESUMO
Grassland soils are a large reservoir of soil carbon (C) at risk of loss due to overgrazing in conventional grazing systems. By promoting regenerative grazing management practices that aim to increase soil C storage and soil health, grasslands have the potential to help alleviate rising atmospheric CO2 as well as sustain grass productivity across a vast area of land. Previous research has shown that rotational grazing, specifically adaptive multi-paddock (AMP) grazing that utilizes short-duration rotational grazing at high stocking densities, can increase soil C stocks in grassland ecosystems, but the extent and mechanisms are unknown. We conducted a large-scale on-farm study on five "across the fence" pairs of AMP and conventional grazing (CG) grasslands covering a spectrum of southeast United States grazing lands. We quantified soil C and nitrogen (N) stocks, their isotopic and Fourier-transform infrared spectroscopy signatures as well as their distribution among soil organic matter (SOM) physical fractions characterized by contrasting mechanisms of formation and persistence in soils. Our findings show that the AMP grazing sites had on average 13% (i.e., 9 Mg C ha-1) more soil C and 9% (i.e., 1 Mg N ha-1) more soil N compared to the CG sites over a 1 m depth. Additionally, the stocks' difference was mostly in the mineral-associated organic matter fraction in the A-horizon, suggesting long-term persistence of soil C in AMP grazing farms. The higher N stocks and lower 15N abundance of AMP soils also point to higher N retention in these systems. These findings provide evidence that AMP grazing is a management strategy to sequester C in the soil and retain N in the system, thus contributing to climate change mitigation.
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Carbono , Solo , Carbono/análise , Ecossistema , Pradaria , Minerais , Nitrogênio/análise , Sudeste dos Estados UnidosRESUMO
Rangelands cover one third of the earth's land area, provide livelihoods for one billion persons, and most have been degraded by overgrazing of domestic livestock. Recent debate about best management practices often has centered on comparison of continuous grazing and rotational grazing. Resolution to this debate may lie in viewing rangelands as complex adaptive systems. We describe a spatially-structured, individual-based model of rangelands that embodies this perspective, and simulate forage dynamics and cattle production under semi-arid rangeland conditions typical of the southern Great Plains of the USA employing both continuous and rotational grazing. Relative "success" of simulated grazing schemes depended primarily on the evaluation metric used (e.g., rangeland ecological condition, sale weight of cattle, secondary production efficiency) and the particular manage scheme employed, and neither continuous nor rotational grazing schemes were uniformly more successful. Our results demonstrate that solution of the grazing systems debate is unlikely to be found in a single group of grazing schemes, but, rather, in adaptive management of feedbacks among system components. The present work provides an example of how modeling rangelands as complex adaptive systems can aid in the evaluation of management schemes.
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Gado , Animais , BovinosRESUMO
Many ranchers who practice rotational grazing have experienced economic and ecological benefits. However, the adoption rate of rotational grazing has stagnated. To identify major challenges faced by non-adopters of rotational grazing as well as factors that affect the perceptions about different challenges, we conducted a mail survey of 4250 eligible ranchers in North Dakota, South Dakota and Texas, USA. Key categories of information obtained included basic ranch information, rotational grazing adoption status, and related information. Among 875 respondents, 40.4% identified themselves as non-adopters and perceived labor and water source constraints as the two major challenges, followed by high initial investment costs. This indicates the need for technical support and educational programs to address producers' concerns in addition to the monetary support from government subsidy programs. Findings from logistic regression analyses further indicate that landowners with higher quality soil, relatively more grassland (in both acres and percentage) and more owned land, generally perceive lower barriers to choosing rotational grazing practices and, therefore, may be a suitable target group for more effective outreach efforts and public fund investments to enhance the adoption of beneficial rotational grazing practices.
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Solo , North Dakota , Inquéritos e Questionários , TexasRESUMO
Maintaining or enhancing the productive capacity and resilience of rangeland ecosystems is critical for the continued support of livelihoods and the ecosystem services that benefit society at large. While the benefits of multi-paddock grazing management have been evident for many years in many countries, it is extremely difficult if not impossible to adequately assess the consequences of the different combinations of management options possible when using multi-paddock management under constantly varying conditions on rangelands. To investigate grazing scenarios that would be impractical to conduct in the field we developed a simulation model to focus on addressing the impacts of different cattle grazing management options with multi-paddock management on ecological condition (EC) and profitability. Cattle ranching options are simulated over 25 years periods under varying levels of multi-paddock grazing management complexity at low to moderate stocking levels and fixed or variable stocking rates. We examine the likely ecological and economic effects of shortening grazing periods, lengthening recovery periods, using fixed versus adaptive operational decisions and increasing the number of paddocks in the grazing configuration. At initial stocking levels of up to at 70% of forage standing crop, both EC and profitability are increased with increasing number of paddocks. Shorter periods of grazing increase both EC and profitability while increasing recovery periods increases both EC and profitability initially but profitability decreases if recovery periods are too long. Both EC and profitability are positively related to number of paddocks used.
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Ração Animal , Criação de Animais Domésticos , Poaceae , Animais , Bovinos , Simulação por Computador , Conservação dos Recursos Naturais , Pradaria , Modelos Teóricos , TexasRESUMO
Maintaining or enhancing the productive capacity and resilience of rangeland ecosystems is critical for the continued support of people who depend on them for their livelihoods, especially in the face of climatic change. This is also necessary for the continued delivery of ecosystem services derived from rangelands for the broader benefit of societies around the world. Multi-paddock grazing management has been recommended since the mid-20th century as an important tool to adaptively manage rangelands ecosystems to sustain productivity and improve animal management. Moreover, there is much anecdotal evidence from producers that, if applied appropriately, multi-paddock grazing can improve forage and livestock production. By contrast, recent reviews of published rangeland-based grazing systems studies have concluded that, in general, field trials show no superiority of vegetation or animal production in multi-paddock grazing relative to continuous yearlong stocking of single-paddock livestock production systems. Our goal is to provide a framework for rangeland management decisions that support the productivity and resiliency of rangelands and then to identify why different perceptions exist among rangeland managers who have effectively used multi-paddock grazing systems and research scientists who have studied them. First, we discuss the ecology of grazed ecosystems under free-ranging herbivores and under single-paddock fenced conditions. Second, we identify five principles underpinning the adaptive management actions used by successful grazing managers and the ecological, physiological, and behavioral framework they use to achieve desired conservation, production, and financial goals. Third, we examine adaptive management principles needed to successfully manage rangelands subjected to varying environmental conditions. Fourth, we describe the differences between the interpretation of results of grazing systems research reported in the scientific literature and the results reported by successful grazing managers; we highlight the shortcomings of most of the previously conducted grazing systems research for providing information relevant for rangeland managers who aim to achieve desired environmental and economic goals. Finally, we outline knowledge gaps and present testable hypotheses to broaden our understanding of how planned multi-paddock grazing management can be used at the ranching enterprise scale to facilitate the adaptive management of rangelands under dynamic environmental conditions.
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Agricultura/métodos , Conservação dos Recursos Naturais/métodos , Gado , Animais , Ecossistema , HerbivoriaRESUMO
Background: Measurement of two grazing management's influence on pasture productivity, soil food web structure, soil organic carbon and soil microbial respiration efficiency was conducted on five southeastern US, across-the-fence ranch pairs to compare adaptive multi-paddock grazing (AMP) management, using short grazing events with planned, adaptive recovery periods, to conventional grazing (CG) management, with continuous grazing at low stock density. Methodology: A point-in-time experimental field analysis was conducted to compare five AMP or CG ranch pairs to better understand the influence of grazing management on (a) standing crop biomass productivity; (b) soil food web community population, structure and functionality; (c) soil organic carbon accrual; and d) soil-C (CO2) respiration kinetics. Results: AMP grazing systems outperformed CG systems by generating: (a) 92.68 g m-2 more standing crop biomass (SCB), promoting 46% higher pasture photosynthetic capacity (Two sample Mann-Whitney; Z = 6.1836; no DF in MW; p = 6.26 × 10-10; Effect size = 0.35) (b) a strong positive linear relationship of SCB with fungal biomass (R = 0.9915; F(1,3) = 175.35; p = 0.015); fungal to bacterial (F:B) biomass ratio (R = 0.9616; F(1,3) = 36.75; p = 0.009) and a soil food web proxy (R = 0.9616; F(1,3) = 36.75; p = 0.009) and a concurrent very strong inverse relationship with bacteria biomass (R = -0.946; F(1,3) = 25.56; p = 0.015); (c) significant predator/prey interactions with an inverse relationship with bacterial population biomass (R = - 0.946; F(1,3) = 25.56; p = 0.015) and a positive relationship with total protozoa enumeration (R = 0.9826; F(1,3) = 83.68; p = 0.003) when compared to SCB; (d) a 19.52% reduction in soil C (CO2) respiration rates (Two sample t-test; T = -2.3581; DF = 52.3541; p = 0.0221; Effect size = 0.59); and (e) a 20.6% increase in soil organic carbon (SOC) in the top 10 cm of soil profile (Two sample Mann-Whitney; Z = 2.6507; no DF in MW; p = 0.008; Effect size = 0.24). Rancher conversion to AMP grazing strategies would appear to regenerate soil food web population, structure, diversity and biological functionality helping to improve: carbon flow into plant biomass, buildup of soil carbon, predator/prey nutrient cycling and soil microbial respiration efficiency while offering improved climate resilience and a strategy to increase the capture and storage of atmospheric CO2 in soils of the world's rangeland.
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Carbono , Solo , Solo/química , Carbono/análise , Cadeia Alimentar , Taxa Respiratória , Dióxido de Carbono/análise , BactériasRESUMO
This study compares the testing rates of bacterial sexually transmitted infections (STIs) among HIV-positive men who have sex with men (MSM) attending two HIV clinics in Melbourne. Data on STI testing over a 12-month period were obtained for all HIV-positive MSM who attended the clinics between January and March 2006. Screening rates for bacterial STIs were significantly higher at a sexual health clinic (n = 254) compared with an infectious diseases clinic (n = 351), whether this was measured according to: at least one STI test being performed for chlamydia, gonorrhoea or syphilis (69% vs. 38%, P < 0.01); serological testing for syphilis alone (67% vs. 34%, P < 0.01); or 'complete' STI screening for pharyngeal gonorrhoea, urethral chlamydia, anal gonorrhoea, anal chlamydia and syphilis (41% vs. 6%, P < 0.01). Substantial differences in STI testing rates among HIV-positive MSM may exist between HIV clinical services depending on the measures in place that promote STI screening.
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Instituições de Assistência Ambulatorial , Infecções por HIV/complicações , Infecções por HIV/prevenção & controle , Homossexualidade Masculina , Auditoria Médica/estatística & dados numéricos , Doenças Bacterianas Sexualmente Transmissíveis/diagnóstico , Doenças Bacterianas Sexualmente Transmissíveis/prevenção & controle , Austrália , Infecções por HIV/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Bacterianas Sexualmente Transmissíveis/epidemiologiaRESUMO
This project used Fricke dosimeters to determine the dose rates at multiple locations in a Co pool irradiator. Fricke dosimetry is widely accepted as a chemical dosimetry method to measure radiation absorbed dose due to its simple recipe, linear response, wide dose range, good reproducibility, ease of measurements, and low operational cost. Calibration measurements were used to determine a molar extinction coefficient of 2,185 +/- 14 L mol cm at 303 nm and 25 degrees C; the molar extinction coefficient is comparable to values from the published literature. The Fricke dosimeters measured the dose rate of a National Institute of Standards and Technology-traceable calibrated gamma radiation field to within 1.2% of the calibrated value. The pool irradiator had the largest dose rates near the middle of the torpedo, with dose rate decreasing as one moved towards the bottom or top of the torpedo. The dose rate across the torpedo is not uniform at each level, because of the non-uniform distribution of source activity around the irradiator. Relative error in the Fricke dosimeter dose rate measurements ranged from 1-2%. The dose rates mapped in this project can be used to plan bulk sample irradiation, although dosimetry measurements should still be obtained to confirm delivered dose.
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Radioisótopos de Cobalto , Doses de Radiação , Radiometria/métodos , Desenho de Equipamento , Radiometria/instrumentação , Radiometria/estatística & dados numéricosRESUMO
Following removal of a superconducting wiggler that has a maximum magnetic-field of 7 T in a high-energy synchrotron facility, sufficient lead shielding was placed upstream of the removal point in the normal-conducting electron storage ring to account for any radiation sources from the upstream components. As is customary in such cases, when vacuum has been breached, there is a period of time required for vacuum re-conditioning of the ring. During this re-conditioning phase, poor vacuum contributes to gas bremsstrahlung formation that typically is visualized as an increase in overall radiation exposure from standard operating conditions. However, in this case, new radiation patterns emerged and persisted throughout the re-commissioning phase. Subsequently, additional shielding was then placed upstream but still failed to resolve the source of radiation. The radiation source point consisted of two distinct components: a point parallel to the position originally covered by the wiggler and a strong forward-directed peak (i.e., bremsstrahlung). The only feedback mechanism to track the beam position is the beam position monitors (BPM's). BPM's were located forward and aft of the parallel source point. The BPM's suggested that the beam was in the correct position. To investigate the elevated radiation level, commercial photographic film was used as a monitoring ruler and the focal point of the radiation source was clearly identified using this novel approach. The silver halide grain contained within the film emulsion possessed sufficient cross section and was activated from Ag to Ag, which has a half-life of 2.39 min and emits easily detectable radiation. Further, the exposed film is ready for reuse after 25 min due to the short half-life of Ag. The proposed method proved to be an easy, economic, and effective approach to rapidly and qualitatively identify the location of the beam losses.
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Aceleradores de Partículas/instrumentação , Fotografação/instrumentação , Proteção Radiológica/instrumentação , Elétrons , Humanos , Lesões por Radiação/prevenção & controle , Proteção Radiológica/métodos , Compostos de Prata/química , Síncrotrons/instrumentaçãoRESUMO
OBJECTIVES: To determine the attitudes of male and female patients to the use of chaperones during genital examination within a sexually transmitted diseases clinic. STUDY DESIGN: An anonymous, self-completed questionnaire was administered to patients attending the Melbourne Sexual Health Centre, Australia, between September and October 2006. RESULTS: The participation rate among male and female patients was 60% (166 of 276) and 73% (153 of 210), respectively. Among male patients, only 7.3% and 6.0% expressed a desire for a chaperone when being examined by a male and female practitioner, respectively. Among female patients, 26.8% desired a chaperone if they were going to be examined by a male practitioner when compared with 5.5% for a female practitioner (P <0.001). Around one-third of male and female patients indicated they would feel uncomfortable having a chaperone present and this did not vary by the sex of the practitioner (P >0.48). For female patients being examined by a male practitioner, the desire for a chaperone was associated with having had a previous cervical smear (odds ratio, OR = 0.35, 95% CI: 0.12-0.98, P = 0.04) and feeling comfortable about the presence of a chaperone present (OR = 28.9; 95% CI: 11.1-75.0; P <0.001), but not age (P = 0.16) or previous genital examination (OR = 0.55, 95% CI: 0.21-1.45, P = 0.2). CONCLUSIONS: In a sexual health setting, female patients undergoing genital examination by a male clinician should be asked whether they would like a chaperone to be present.
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Doenças dos Genitais Femininos/diagnóstico , Doenças dos Genitais Masculinos/diagnóstico , Exame Físico/métodos , Exame Físico/psicologia , Instituições de Assistência Ambulatorial , Atitude , Feminino , Pesquisas sobre Atenção à Saúde , Humanos , Masculino , Satisfação do Paciente , Relações Médico-Paciente , Fatores Sexuais , Infecções Sexualmente Transmissíveis , Inquéritos e QuestionáriosRESUMO
OBJECTIVES: To examine the current practice and attitudes of Australian sexual health practitioners towards the use of chaperones for genital examinations. METHODS: In July 2006, an anonymous, self-completed questionnaire was mailed to members of the Australasian Chapter of Sexual Health Medicine. RESULTS: Of the 166 questionnaires sent to practitioners, 110 (66%) were returned completed. Of the 110 respondents, only 9% and 19% reported that their clinic routinely provided chaperones for all male and female genital examinations, respectively. Among practitioners whose services did not offer chaperones routinely, chaperones were offered with a mean frequency of 19% for female examinations and 8% for male examinations (P = 0.01). Compared to female practitioners, significantly more male practitioners thought a chaperone was important for medico-legal purposes when examining females (72% v. 53%, P < 0.05). Compared to male practitioners, significantly more female practitioners thought a chaperone was sometimes important for patient support when examining male patients (52% v. 26%, P < 0.001). Only 39% (n = 18) of male practitioners and 36% (n = 23) of female practitioners felt that resources spent on chaperones were justified by the benefits they provided. CONCLUSIONS: Despite only a minority of practitioners offering chaperones to patients or using them during examinations, many feel they are important for medico-legal reasons and as support for the patient. Best practice may be for services to routinely offer a chaperone and record instances where an offer is declined. This provides patients with choice and practitioners with some level of protection.