1,653 research outputs found
Pleba\'nski-Demia\'nski-like solutions in metric-affine gravity
We consider a (non--Riemannian) metric--affine gravity theory, in particular
its nonmetricity--torsion sector ``isomorphic'' to the Einstein--Maxwell
theory. We map certain Einstein--Maxwell electrovacuum solutions to it, namely
the Pleba\'nski--Demia\'nski class of Petrov type D metrics.Comment: 12 pages of a LaTeX-fil
Independent Component Analysis to Detect Clustered Microcalcification Breast Cancers
The presence of clustered microcalcifications is one of the earliest signs in breast cancer detection. Although there exist many studies broaching this problem, most of them are nonreproducible due to the use of proprietary image datasets. We use a known subset of the currently largest publicly available mammography database, the Digital Database for Screening Mammography (DDSM), to develop a computer-aided detection system that outperforms the
current reproducible studies on the same mammogram set. This proposal is mainly based on the use of extracted image features obtained by independent component analysis, but we also study the inclusion of the patient's age as a nonimage feature which requires no human expertise. Our system achieves an average of 2.55 false positives per image at a sensitivity of 81.8% and 4.45 at a sensitivity of 91.8% in diagnosing the BCRP_CALC_1 subset of DDSM
Pyrite oxidation processes in surface systems: acidifying potential and its interest in minesoils reclamation
[Resumen] Se analizan los mecanismos de oxidaciĂłn de pirita, considerando las diferentes vĂas de evoluciĂłn admitidas en la bibliografĂa, la influencia de las condiciones del medio (Eh, pH, microorganismos, etc.), la naturaleza de los productos formados y su potencial acidificante en distintas condiciones. Como ejemplo se presentan datos obtenidos en el estudio de dos explotaciones mineras en rocas anfibolĂticas ricas en sulfuros de las proximidades de Santiago de Compostela. Se concluye la necesidad del conocimiento de estos procesos para una mejor planificaciĂłn de las medidas de control del impacto ambiental en suelos, aguas y organismos, asĂ como de los procedimientos mĂĄs adecuados para la recuperaciĂłn de escombreras y «suelos de mina».[Abstract] Some aspects of pyrite oxidation mechanism such as the evolution pathways recognized in the literature, the influence of environmental conditions (Eh, pH, microorganism, etc.), nature of formed products and acidifying potential under different conditions are revised. As an example, the results obtained in a study of two mines in sulphide rich amphibolitic rocks near Santiago de Compostela, are included. It is concluded the need of the knowledge of these processes in order to improve the planification of the methods to control environmental iropacts in soils, waters and organisms, as well as to establish the most suitable procedures for waste materials and minesoils reclamation
Composite absorbing potentials
The multiple scattering interferences due to the addition of several
contiguous potential units are used to construct composite absorbing potentials
that absorb at an arbitrary set of incident momenta or for a broad momentum
interval.Comment: 9 pages, Revtex, 2 postscript figures. Accepted in Phys. Rev. Let
A Characterization of the Diffuse Galactic Emissions in the Anticenter of the Galaxy
Using the Archeops and WMAP data, we perform a study of the anticenter Galactic diffuse emissionsâthermal dust, synchrotron, free-free, and anomalous emissionsâat degree scales. The high-frequency data are used to infer the thermal dust electromagnetic spectrum and spatial distribution allowing us to precisely subtract this component at lower frequencies. After subtraction of the thermal dust component, a mixture of standard synchrotron and free-free emissions does not account for the residuals at these low frequencies. Including the all-sky 408âMHz Haslam data we find evidence for anomalous emission with a spectral index of â2.5 in units. However, we are not able to provide coclusion regarding the nature of this anomalous emission in this region. For this purpose, data between 408âMHz and 20âGHz covering the same sky region are needed
Five Years Measuring the Muck: Evaluating Interannual Variability of Nutrient Loads from Tidal Flooding
Due to sea level rise, tidal flooding is now common in low-lying coastal systems around the world. Yet, the contribution of tidal flooding to non-point source nutrient loads and their impact on the quality of adjacent waters remains poorly constrained. Here, we quantified dissolved nutrient loading and Enterococcus abundance during annual autumnal king tides (i.e., perigean spring tides), between 2017 and 2021, in a sub-watershed of the lower Chesapeake Bay. To calculate nutrient loading from tidal flooding, we used geospatial inundation depths from a street-level hydrodynamic model to estimate floodwater volumes during each of the five sampling events and the difference between nutrient concentrations in floodwater and pre-flood measurements. Results showed that dissolved nutrient concentrations were higher in floodwaters than in estuarine waters and resulted in dissolved nitrogen and phosphorus loads that reached 58.4âĂâ103 kg and 14.4âĂâ103 kg, respectively. We compared our load estimates to the tributary-specific total and land-based federal allocations (i.e., total maximum daily loads (TMDL)) for total nitrogen (TN) and total phosphorus (TP). Even the more conservative calculations indicate that inputs of dissolved nutrients during a single tidal flooding event can exceed 100% of the annual load allocation. Additionally, more than 80% of the floodwater samples collected each year showed Enterococcus abundance that exceeded the threshold for recreational water use in Virginia (104 MPN 100 mlâ1). Failing to account for non-point source loading of nutrients and contaminants from tidal flooding as sea level rises could result in worsening eutrophication and deterioration of coastal economies and the health of coastal communities around the world
Effects of Tidal Flooding on Estuarine Biogeochemistry: Quantifying Flood-Driven Nitrogen Inputs in an Urban, Lower Chesapeake Bay Sub-Tributary
Sea level rise has increased the frequency of tidal flooding even without accompanying precipitation in many coastal areas worldwide. As the tide rises, inundates the landscape, and then recedes, it can transport organic and inorganic matter between terrestrial systems and adjacent aquatic environments. However, the chemical and biological effects of tidal flooding on urban estuarine systems remain poorly constrained. Here, we provide the first extensive quantification of floodwater nutrient concentrations during a tidal flooding event and estimate the nitrogen (N) loading to the Lafayette River, an urban tidal sub-tributary of the lower Chesapeake Bay (USA). To enable the scale of synoptic sampling necessary to accomplish this, we trained citizen-scientist volunteers to collect 190 flood water samples during a perigean spring tide to measure total dissolved N (TDN), dissolved inorganic N (DIN) and phosphate concentrations, and Enterococcus abundance from the retreating ebb tide while using a phone application to measure the extent of tidal inundation. Almost 95% of Enterococcus results had concentrations that exceeded the standard established for recreational waters (104 MPN 100 mLâ1). Floodwater dissolved nutrient concentrations were higher than concentrations measured in natural estuarine waters, suggesting floodwater as a source of dissolved nutrients to the estuary. However, only DIN concentrations were statistically higher in floodwater samples than in the estuary. Using a hydrodynamic model to calculate the volume of water inundating the landscape, and the differences between the median DIN concentrations in floodwaters and the estuary, we estimate that 1,145 kg of DIN entered the Lafayette River during this single, blue sky, tidal flooding event. This amount exceeds the annual N load allocation for overland flow established by federal regulations for this segment of the Chesapeake Bay by 30%. Because tidal flooding is projected to increase in the future as sea levels continue to rise, it is crucial we quantify nutrient loading from tidal flooding in order to set realistic water quality restoration targets for tidally influenced water bodies
Supersymmetric minisuperspace with non-vanishing fermion number
The Lagrangean of supergravity is dimensionally reduced to one
(time-like) dimension assuming spatial homogeneity of any Bianchi type within
class A of the classification of Ellis and McCallum. The algebra of the
supersymmetry generators, the Lorentz generators, the diffeomorphism generators
and the Hamiltonian generator is determined and found to close. In contrast to
earlier work, infinitely many physical states with non-vanishing even fermion
number are found to exist in these models, indicating that minisuperspace
models in supergravity may be just as useful as in pure gravity.Comment: 4 page
Darunavir/Cobicistat/Emtricitabine/Tenofovir Alafenamide Versus Dolutegravir/Abacavir/Lamivudine in Antiretroviral-Naive Adults (SYMTRI): A Multicenter Randomized Open-Label Study (PReEC/RIS-57)
Background. Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) is the reference for combination therapy
based on protease inhibitors due to its efficacy, tolerability, and convenience. Head-to-head randomized comparisons between
D/C/F/TAF and combination therapy based on integrase inhibitors in antiretroviral-naive patients are lacking.
Methods. Adult (>18 years old) human immunodeficiency virus-infected antiretroviral-naive patients (HLA-Bâ5701 negative
and hepatitis B virus negative), with viral load (VL) â„500 c/mL, were centrally randomized to initiate D/C/F/TAF or dolutegravir/
abacavir/lamivudine (DTG/3TC/ABC) after stratifying by VL and CD4 count. Clinical and analytical assessments were performed
at weeks 0, 4, 12, 24, and 48. The primary endpoint was VL <50 c/mL at week 48 in the intention-to-treat (ITT)-exposed population
(US Food and Drug Administration snapshot analysis, 10% noninferiority margin).
Results. Between September 2018 and 2019, 316 patients were randomized and 306 patients were included in the ITT-exposed
analysis (151 D/C/F/TAF and 155 DTG/3TC/ABC). Almost all (94%) participants were male and their median age was 35 years.
Forty percent had a baseline VL >100 000 copies/mL, and 13% had <200 CD4 cells/ÎŒL. Median weight was 73 kg and median body
mass index was 24 kg/m2
. At 48 weeks, 79% (D/C/F/TAF) versus 82% (DTG/3TC/ABC) had VL <50 c/mL (difference, â2.4%; 95%
confidence interval [CI], â11.3 to 6.6). Eight percent versus four percent experienced virologic failure but no resistance-associated
mutations emerged. Four percent versus six percent had drug discontinuation due to adverse events. In the per-protocol analysis,
94% versus 96% of patients had VL <50 c/mL (difference, â2%; 95% CI, â8.1 to 3.5). There were no differences in CD4 cell count or
weight changes.
Conclusions. We could not demonstrate the noninferiority of D/C/F/TAF relative to DTG/ABC/3TC as initial antiretroviral
therapy, although both regimens were similarly well tolerated
Technical Note: A new device for cervical insemination of sheep - design and field test1
Deep semen deposition, avoiding retrograde flow, lesions and stress, has proved to be very important in the success of sheep AI. The objective of the present study was to develop a new, suitable antiretrograde flow device for sheep cervical AI (DARIO) that enables deep deposition of semen into the cervix without any modifications to the procedures currently used, and to compare the fertility, fecundity, and prolificacy rates between DARIO and a traditional catheter. Field tests were performed on 16 farms actively participating in the non-profit National Association of Rasa Aragonesa Breeders genetic selection scheme and where sheep management was similar. A total of 242 AI lots were considered, including 1, 299 ewes; 126 lots (662 ewes) were inseminated using DARIO, and 116 lots (637 ewes) using a traditional commercially-available catheter (control group). Several factors affecting AI results were included in the model for mean comparison between DARIO and control groups (farm and ram as random factors; catheter, year and photoperiod as fixed effects; catheter vó photoperiod interaction). The type of catheter had a significant effect on fertility (P < 0.01) and fecundity rates (P < 0.01) but no significant effect was detected on the prolificacy rate (P = 0.45). For fertility rate (percentage of ewes lambing after AI), means ± SE for DARIO and control groups were 59.44 ± 2.13% and 49.60 ± 2.48%, respectively; for fecundity rates, means ± SE for DARIO and control groups were 0.99 ± 0.04 and 0.82 ± 0.05 lambs/inseminated ewe, respectively, and, for prolificacy rates, means ± SE for DARIO and control groups were 1.68 ± 0.04 and 1.63 ± 0.04 lambs/ewe lambing, respectively. Fertility rate was greater in the decreasing photoperiod (P = 0.01). Significant effects were found for both year (P < 0.05) and farm (P < 0.01) on fertility, fecundity, and prolificacy rates. Neither ram nor catheter vó photoperiod showed any significant effects on the variables investigated (P > 0.05). Overall, the use of DARIO instead of the traditional commercially-available catheter increased both fertility and fecundity rates; the marginal mean differences were 9.05 pregnant ewes per 100 inseminated and 0.15 lambs per inseminated ewe, respectively
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