We develop a model which couples the flow in a discrete fracture to a deformable porous medium. To account for the discrete representation of the fracture, a dimensionally-reduced fluid flow model is ...proposed. The fluid flow model incorporates both a reduced permeability of the fracture walls due to the skin effect, and a slip of fluid flowing along the permeable fracture walls. Biot's model for poroelastic media is coupled to a fracture flow model based on a thin-film approximation of the compressible Navier-Stokes equations. The fracture flow model incorporates a fluid entry resistance parameter to relate the leak-off through the fracture walls to a pressure jump across the fracture walls, and the Beavers-Joseph-Saffman slip rate coefficient to represent the fluid slip along the fracture walls. The numerical model is based on a thermodynamic framework in which all energy storage and dissipative mechanisms in the problem are identified, including the mechanisms related to the interface effects. The thermodynamic framework is employed to solve the nonlinear coupled problem up to a specified energy range through a Picard iteration technique and to study the model and its results. Studies are presented for a range of fluid entry resistance parameters and Beavers-Joseph-Saffman slip rate coefficients, showing the capability of the model to simulate skin and slip effects in a dimensionally-reduced fracture setting.
•A discrete fracture is coupled to a deformable poroelastic medium.•Fluid slip and fluid entry resistance effects on the fracture walls are incorporated.•A thin-film flow model based on the Navier-Stokes equations is proposed.•A thermodynamic framework for the coupled problem is presented.•The nonlinear coupled problem is solved using a Picard iteration technique.
We conducted the phase III double-blind European Organisation for Research and Treatment of Cancer (EORTC) 1325/KEYNOTE-054 trial to evaluate pembrolizumab versus placebo in patients with resected ...high-risk stage III melanoma. On the basis of 351 recurrence-free survival (RFS) events at a 1.25-year median follow-up, pembrolizumab prolonged RFS (hazard ratio HR, 0.57;
< .0001) compared with placebo. This led to the approval of pembrolizumab adjuvant treatment by the European Medicines Agency and US Food and Drug Administration. Here, we report an updated RFS analysis at the 3.05-year median follow-up.
A total of 1,019 patients with complete lymph node dissection of American Joint Committee on Cancer Staging Manual (seventh edition; AJCC-7), stage IIIA (at least one lymph node metastasis > 1 mm), IIIB, or IIIC (without in-transit metastasis) cutaneous melanoma were randomly assigned to receive pembrolizumab at a flat dose of 200 mg (n = 514) or placebo (n = 505) every 3 weeks for 1 year or until disease recurrence or unacceptable toxicity. The two coprimary end points were RFS in the overall population and in those with programmed death-ligand 1 (PD-L1)-positive tumors.
Pembrolizumab (190 RFS events) compared with placebo (283 RFS events) resulted in prolonged RFS in the overall population (3-year RFS rate, 63.7%
44.1% for pembrolizumab
placebo, respectively; HR, 0.56; 95% CI, 0.47 to 0.68) and in the PD-L1-positive tumor subgroup (HR, 0.57; 99% CI, 0.43 to 0.74). The impact of pembrolizumab on RFS was similar in subgroups, in particular according to AJCC-7 and AJCC-8 staging, and
mutation status (HR, 0.51 99% CI, 0.36 to 0.73
0.66 99% CI, 0.46 to 0.95 for V600
wild type).
In resected high-risk stage III melanoma, pembrolizumab adjuvant therapy provided a sustained and clinically meaningful improvement in RFS at 3-year median follow-up. This improvement was consistent across subgroups.
To develop active nonprecious metal-based electrocatalysts for the oxygen evolution reaction (OER), a limiting reaction in several emerging renewable energy technologies, a deeper understanding of ...the activity of the first row transition metal oxides is needed. Previous studies of these catalysts have reported conflicting results on the influence of noble metal supports on the OER activity of the transition metal oxides. Our study aims to clarify the interactions between a transition metal oxide catalyst and its metal support in turning over this reaction. To achieve this goal, we examine a catalytic system comprising nanoparticulate Au, a common electrocatalytic support, and nanoparticulate MnO x , a promising OER catalyst. We conclusively demonstrate that adding Au to MnO x significantly enhances OER activity relative to MnO x in the absence of Au, producing an order of magnitude higher turnover frequency (TOF) than the TOF of the best pure MnO x catalysts reported to date. We also provide evidence that it is a local rather than bulk interaction between Au and MnO x that leads to the observed enhancement in the OER activity. Engineering improvements in nonprecious metal-based catalysts by the addition of Au or other noble metals could still represent a scalable catalyst as even trace amounts of Au are shown to lead a significant enhancement in the OER activity of MnO x .
We present the observed pulsation spectra of all known noninteracting ZZ Ceti stars (hydrogen atmosphere white dwarf variables DAVs) and examine changes in their pulsation properties across the ...instability strip. We confirm the well-established trend of increasing pulsation period with decreasing effective temperature across the ZZ Ceti instability strip. We do not find a dramatic order-of-magnitude increase in the number of observed independent modes in ZZ Ceti stars, traversing from the hot to the cool edge of the instability strip; we find that the cool DAVs have one more mode on average than the hot DAVs. We confirm the initial increase in pulsation amplitude at the blue edge and find strong evidence of a decline in amplitude prior to the red edge. We present the first observational evidence that ZZ Ceti stars lose pulsation energy just before pulsations shut down at the empirical red edge of the instability strip.
Salmonella paratyphi A rates, Asia Ochiai, R Leon; Wang, XuanYi; von Seidlein, Lorenz ...
Emerging infectious diseases,
11/2005, Letnik:
11, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Little is known about the causes of enteric fever in Asia. Most cases are believed to be caused by Salmonella enterica serovar Typhi and the remainder by S. Paratyphi A. We compared their incidences ...by using standardized methods from population-based studies in China, Indonesia, India, and Pakistan.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Kepler and TESS Observations of PG 1159-035 Oliveira da Rosa, Gabriela; Kepler, S. O.; Córsico, Alejandro H. ...
The Astrophysical journal,
09/2022, Letnik:
936, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Abstract
PG 1159-035 is the prototype of the PG 1159 hot (pre-)white dwarf pulsators. This important object was observed during the Kepler satellite K2 mission for 69 days in 59 s cadence mode and by ...the TESS satellite for 25 days in 20 s cadence mode. We present a detailed asteroseismic analysis of those data. We identify a total of 107 frequencies representing 32
ℓ
= 1 modes, 27 frequencies representing 12
ℓ
= 2 modes, and eight combination frequencies. The combination frequencies and the modes with very high
k
values represent new detections. The multiplet structure reveals an average splitting of 4.0 ± 0.4
μ
Hz for
ℓ
= 1 and 6.8 ± 0.2
μ
Hz for
ℓ
= 2, indicating a rotation period of 1.4 ± 0.1 days in the region of period formation. In the Fourier transform of the light curve, we find a significant peak at 8.904 ± 0.003
μ
Hz suggesting a surface rotation period of 1.299 ± 0.002 days. We also present evidence that the observed periods change on timescales shorter than those predicted by current evolutionary models. Our asteroseismic analysis finds an average period spacing for
ℓ
= 1 of 21.28 ± 0.02 s. The
ℓ
= 2 modes have a mean spacing of 12.97 ± 0.4 s. We performed a detailed asteroseismic fit by comparing the observed periods with those of evolutionary models. The best-fit model has
T
eff
= 129, 600 ± 11 100 K,
M
*
= 0.565 ± 0.024
M
⊙
, and
log
g
=
7.41
−
0.54
+
0.38
, within the uncertainties of the spectroscopic determinations. We argue for future improvements in the current models, e.g., on the overshooting in the He-burning stage, as the best-fit model does not predict excitation for all of the pulsations detected in PG 1159-035.
In this work, we explore the interplay between manganese oxide (MnO x ) nanomaterials and a glassy carbon (GC) support in catalyzing the oxygen reduction reaction (ORR) in an alkaline environment. ...Initially, we characterize the ORR activity of bare GC electrodes as a function of heat treatments in air, and find that ORR activity increases with increasing temperature up to 500 °C. Modification of GC with size-selected 1 nm MnO x nanoparticles prior to the 500 °C heat treatment yields a highly porous GC (pGC) structure, devoid of MnO x . This pGC sample exhibits the highest ORR performance of the bare carbon electrodes reaching an onset potential of 0.75 V vs the reversible hydrogen electrode (RHE) and a complete 2-electron reduction of oxygen to peroxide. Having established ORR activity of bare GC electrodes, we deposit size-selected 14 nm MnO nanoparticles onto the GC and pGC electrodes and then incite phase changes in MnO through heat treatments in air. Electrochemical characterization of the resulting electrodes reveals that MnO nanoparticles offer no improvement in the ORR onset potential over bare GC or pGC and only slightly increase the number of electrons transferred. By contrast, thermal oxidation of MnO nanoparticles to Mn3O4 at 500 °C, confirmed by Mn L-edge X-ray absorption spectroscopy, results in an improved ORR onset potential of 0.80 V and a 4-electron reduction of oxygen. Thus at low overpotentials, where GC and pGC were inactive for the ORR, MnO x sites must contribute to all steps of the reaction. The catalyst’s estimated specific activity of 3700 μA·cm–2 cat at 0.75 V compares favorably with specific activities of Pt/C as well as the best nonprecious metal catalysts. This establishes Mn3O4 as another MnO x phase with high activity for the ORR.
We present the detection of non-radial oscillations in a hot, helium-atmosphere white dwarf using 78.7 days of nearly uninterrupted photometry from the Kepler space telescope. With an effective ...temperature >30,000 K, PG 0112+104 becomes the hottest helium-atmosphere white dwarf known to pulsate. The rich oscillation spectrum of low-order g-modes includes clear patterns of rotational splittings from consecutive sequences of dipole and quadrupole modes, which can be used to probe the rotation rate with depth in this highly evolved stellar remnant. We also measure a surface rotation rate of 10.17404 hr from an apparent spot modulation in the K2 data. With two independent measures of rotation, PG 0112+104 provides a remarkable test of asteroseismic inference.
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