ABSTRACT To date, the Burst Alert Telescope (BAT) onboard Swift has detected ∼1000 gamma-ray bursts (GRBs), of which ∼360 GRBs have redshift measurements, ranging from z = 0.03 to z = 9.38. We ...present the analyses of the BAT-detected GRBs for the past ∼11 years up through GRB 151027B. We report summaries of both the temporal and spectral analyses of the GRB characteristics using event data (i.e., data for each photon within approximately 250 s before and 950 s after the BAT trigger time), and discuss the instrumental sensitivity and selection effects of GRB detections. We also explore the GRB properties with redshift when possible. The result summaries and data products are available at http://swift.gsfc.nasa.gov/results/batgrbcat/index.html. In addition, we perform searches for GRB emissions before or after the event data using the BAT survey data. We estimate the false detection rate to be only one false detection in this sample. There are 15 ultra-long GRBs (∼2% of the BAT GRBs) in this search with confirmed emission beyond ∼1000 s of event data, and only two GRBs (GRB 100316D and GRB 101024A) with detections in the survey data prior to the starting of event data.
Numerous facets of scientific research implicitly or explicitly call for the estimation of probability densities. Histograms and kernel density estimates (KDEs) are two commonly used techniques for ...estimating such information, with the KDE generally providing a higher fidelity representation of the probability density function (PDF). Both methods require specification of either a bin width or a kernel bandwidth. While techniques exist for choosing the kernel bandwidth optimally and objectively, they are computationally intensive, since they require repeated calculation of the KDE. A solution for objectively and optimally choosing both the kernel shape and width has recently been developed by Bernacchia and Pigolotti (2011). While this solution theoretically applies to multidimensional KDEs, it has not been clear how to practically do so.
A method for practically extending the Bernacchia–Pigolotti KDE to multidimensions is introduced. This multidimensional extension is combined with a recently-developed computational improvement to their method that makes it computationally efficient: a 2D KDE on 105 samples only takes 1 s on a modern workstation. This fast and objective KDE method, called the fastKDE method, retains the excellent statistical convergence properties that have been demonstrated for univariate samples. The fastKDE method exhibits statistical accuracy that is comparable to state-of-the-science KDE methods publicly available in R, and it produces kernel density estimates several orders of magnitude faster. The fastKDE method does an excellent job of encoding covariance information for bivariate samples. This property allows for direct calculation of conditional PDFs with fastKDE. It is demonstrated how this capability might be leveraged for detecting non-trivial relationships between quantities in physical systems, such as transitional behavior.
•A multidimensional, fast, and robust kernel density estimation is proposed: fastKDE.•fastKDE has statistical performance comparable to state-of-the-science kernel density estimate packages in R.•fastKDE is demonstrably orders of magnitude faster than comparable, state-of-the-science density estimate packages in R.•A Python-based implementation of fastKDE is available at https://bitbucket.org/lbl-cascade/fastkde.
Outflows of ionized gas driven by active galactic nuclei (AGN) may significantly impact the evolution of their host galaxies. However, determining the energetics of these outflows is difficult with ...spatially unresolved observations that are subject to strong global selection effects. We present part of an ongoing study using Hubble Space Telescope and Apache Point Observatory spectroscopy and imaging to derive spatially resolved mass outflow rates and energetics for narrow-line region outflows in nearby AGN that are based on multi-component photoionization models to account for spatial variations in gas ionization, density, abundances, and dust content. This expanded analysis adds Mrk 3, Mrk 78, and NGC 1068, doubling our earlier sample. We find that the outflows contain total ionized gas masses of M ≈ 10(exp 5.5)-10(exp 7.5) M⨀ and reach peak velocities of v ≈ 800-2000 km s(exp -1). The outflows reach maximum mass outflow rates of M(sub OUT) ≈ 3-12 M⨀ yr(exp -1) and encompass total kinetic energies of E ≈ 10(exp 54)-10(exp 56) erg. The outflows extend to radial distances of r ≈ 0.1-3 kpc from the nucleus, with the gas masses, outflow energetics, and radial extents positively correlated with AGN luminosity. The outflow rates are consistent with in situ ionization and acceleration where gas is radiatively driven at multiple radii. These radial variations indicate that spatially resolved observations are essential for localizing AGN feedback and determining the most accurate outflow parameters.
The power of forecasts to advance ecological theory Lewis, Abigail S. L.; Rollinson, Christine R.; Allyn, Andrew J. ...
Methods in ecology and evolution,
March 2023, 2023-03-00, 20230301, 2023-03-01, Volume:
14, Issue:
3
Journal Article
Peer reviewed
Open access
Ecological forecasting provides a powerful set of methods for predicting short‐ and long‐term change in living systems. Forecasts are now widely produced, enabling proactive management for many ...applied ecological problems. However, despite numerous calls for an increased emphasis on prediction in ecology, the potential for forecasting to accelerate ecological theory development remains underrealized.
Here, we provide a conceptual framework describing how ecological forecasts can energize and advance ecological theory. We emphasize the many opportunities for future progress in this area through increased forecast development, comparison and synthesis.
Our framework describes how a forecasting approach can shed new light on existing ecological theories while also allowing researchers to address novel questions. Through rigorous and repeated testing of hypotheses, forecasting can help to refine theories and understand their generality across systems. Meanwhile, synthesizing across forecasts allows for the development of novel theory about the relative predictability of ecological variables across forecast horizons and scales.
We envision a future where forecasting is integrated as part of the toolset used in fundamental ecology. By outlining the relevance of forecasting methods to ecological theory, we aim to decrease barriers to entry and broaden the community of researchers using forecasting for fundamental ecological insight.
Oceanic uptake of anthropogenic carbon dioxide (CO₂) has acidified open-ocean surface waters by 0.1 pH units since preindustrial times. Despite unequivocal evidence of ocean acidification (OA) via ...open-oceanmeasurements for the past several decades, it has yet to be documented in near-shore and coral reef environments. A lack of long-term measurements from these environments restricts our understanding of the natural variability and controls of seawater CO₂-carbonate chemistry and biogeochemistry, which is essential to make accurate predictions on the effects of future OA on coral reefs. Here, in a 5-y study of the Bermuda coral reef, we show evidence that variations in reef biogeochemical processes drive interannual changes in seawater pH and Ωaragonitethat are partly controlled by offshore processes. Rapid acidification events driven by shifts toward increasing net calcification and net heterotrophy were observed during the summers of 2010 and 2011, with the frequency and extent of such events corresponding to increased offshore productivity. These events also coincided with a negative winter North Atlantic Oscillation (NAO) index, which historically has been associated with extensive offshore mixing and greater primary productivity at the Bermuda Atlantic Time-series Study (BATS) site. Our results reveal that coral reefs undergo natural interannual events of rapid acidification due to shifts in reef biogeochemical processes that may be linked to offshore productivity and ultimately controlled by larger-scale climatic and oceanographic processes.
With increasing mpox cases in Maricopa County, Arizona, the county's health department launched a survey on July 11, 2022, to gather eligibility and contact data and provide clinic information to ...those interested in JYNNEOS as postexposure prophylaxis (PEP) or expanded postexposure prophylaxis(PEP++). Survey data were matched to case and vaccination data. Overall, 343 of the 513 respondents (66.9%) who reported close contact with an mpox case patient received PEP and 1712 of the 3379 respondents (50.7%) who were unsure of their contact status received PEP++. This outreach intervention connected potential close contacts unknown to MCDPH with PEP or PEP++. (
2023;113(5):504-508. https://doi.org/10.2105/AJPH.2023.307224).
Full text
Available for:
CEKLJ, FSPLJ, ODKLJ, UL, VSZLJ
Active galactic nuclei (AGN) can launch outflows of ionized gas that may influence galaxy evolution, and quantifying their full impact requires spatially resolved measurements of the gas masses, ...velocities, and radial extents. We previously reported these quantities for the ionized narrow-line region outflows in six low-redshift AGN, where the gas velocities and extents were determined from Hubble Space Telescope long-slit spectroscopy. However, calculating the gas masses required multicomponent photoionization models to account for radial variations in the gas densities, which span ∼6 orders of magnitude. To simplify this method for larger samples with less spectral coverage, we compare these gas masses with those calculated from techniques in the literature. First, we use a recombination equation with three different estimates for the radial density profiles. These include constant densities, those derived from S ii, and power-law profiles based on constant values of the ionization parameter (U). Second, we use single-component photoionization models with power-law density profiles based on constant U, and allow U to vary with radius based on the O iii/Hβ ratios. We find that assuming a constant density of nH = 10(^2) cm(^−3) overestimates the gas masses for all six outflows, particularly at small radii where the outflow rates peak. The use of S ii marginally matches the total gas masses, but also overestimates at small radii. Overall, single-component photoionization models where U varies with radius are able to best match the gas mass and outflow rate profiles when there are insufficient emission lines to construct detailed models.
•Reactor performance and safety characteristics of ThN/UN composites are studied.•ThN has a very high thermal conductivity, which increases safety margin.•Several designs seem feasible from a ...neutronic and thermal hydraulic perspective.
The reactor performance and safety characteristics of mixed thorium mononitride (ThN) and uranium mononitride (UN) fuels in a pressurized water reactor (PWR) are investigated to discern the potential nonproliferation, waste, and accident tolerance benefits provided by this fuel form. This paper presents results from an initial screening of mixed ThN-UN fuels in normal PWR operating conditions and compares their reactor performance to UO2 in terms of fuel cycle length, reactivity coefficients, and thermal safety margin. ThN has been shown to have a significantly greater thermal conductivity than UO2 and UN. Admixture with a UN phase is required because thorium initially contains no fissile isotopes.
Results from this study show that ThN-UN mixtures exist that can match the cycle length of a UO2-fueled reactor by using 235U enrichments greater than 5% but less than 20% in the UN phase. Reactivity coefficients were calculated for UO2, UN, and ThN-UN mixtures, and it was found that the fuel temperature and moderator temperature coefficients of the nitride-based fuels fall within the acceptable limits specified by the AP1000 Design Control Document. Reduced soluble boron and control rod worth for these fuel forms indicates that the shutdown margin may not be sufficient, and design changes to the control systems may need to be considered. The neutronic impact of 15N enrichment on reactivity coefficients is also included. Due to the greatly enhanced thermal conductivity of the nitride-based fuels, the UN and ThN-UN fuels provide additional margin to fuel melting temperature relative to UO2.
Comprehensive training in robotic surgery Brook, Nicholas R; Dell’Oglio, Paolo; Barod, Ravi ...
Current opinion in urology,
2019-January, 2019-01-00, 20190101, 2019, Volume:
29, Issue:
1
Journal Article
PURPOSE OF REVIEWRobotic training in urology can be poorly structured, lack a basic skills foundation, and may not include teaching in important nontechnical human factor skills vital to the safe ...delivery of robotic care. Assessment of acquired skills is not routine. There is a need for structured and standardized curricular to deliver validated training and final assessment. The present reviews the current literature on training methods for robotic surgery, and examines the evidence for their effect on performance, where available.
RECENT FINDINGSThere is good evidence for the beneficial effect of dry lab simulators on robotic skills acquisition, but less for cadaveric and animal models. Two urological authorities have developed comprehensive curricula for robotic training that take a novice robotic surgeon through the full stages of robotic skills acquisition. These are in the early stages of development and validation but have stimulated the development of curricula in other specialties.
SUMMARYThe future landscape for robotic urology training is likely to include structured, mandated, and centralized training, possibly administered by urological organizations. There will be roles for telementoring, advanced education for robotic trainers, and regular revalidation of expert robotic surgeons.
Dark fermentative biohydrogen production in a thermophilic, xylose-fed (50 mM) fluidised bed reactor (FBR) was evaluated in the temperature range 55–70 °C with 5-degree increments and compared with a ...mesophilic FBR operated constantly at 37 °C. A significantly higher (p = 0.05) H2 yield was obtained in the thermophilic FBR, which stabilised at about 1.2 mol H2 mol−1 xylose (36% of the theoretical maximum) at 55 and 70 °C, and at 0.8 mol H2 mol−1 xylose at 60 and 65 °C, compared to the mesophilic FBR (0.5 mol H2 mol−1 xylose). High-throughput sequencing of the reverse-transcribed 16S rRNA, done for the first time on biohydrogen producing reactors, indicated that Thermoanaerobacterium was the prevalent active microorganism in the thermophilic FBR, regardless of the operating temperature. The active microbial community in the mesophilic FBR was mainly composed of Clostridium and Ruminiclostridium at 37 °C. Thermophilic dark fermentation was shown to be suitable for treatment of high temperature, xylose-containing wastewaters, as it resulted in a higher energy output compared to the mesophilic counterpart.
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•Thermophilic FBR (55–70 °C) yielded 1–2 fold more H2 than mesophilic FBR (37 °C).•Next-generation sequencing of cDNA was used for the first time on dark fermentation.•Thermoanaerobacterium dominated the active microbial community at 55–70 °C.•In the thermophilic FBR, Clostridium caused unstable H2 yield only at 65 °C.•At 37 °C, VFA accumulation and homoacetogenesis caused unstable H2 yield.
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