A Balanced Budget View on Forming Giant Planets by Pebble Accretion

Pebble accretion refers to the assembly of rocky planet cores from particles whose velocity dispersions are damped by drag from circumstellar disc gas. Accretion cross-sections can approach maximal Hill-sphere scales for particles whose Stokes numbers approach unity. While fast, pebble accretion is also lossy. Gas drag brings pebbles to protocores but also sweeps them past; those particles with the largest accretion cross-sections also have the fastest radial drift speeds and are the most easily drained out of discs. We present a global model of planet formation by pebble accretion that keeps track of the disc's mass budget. Cores, each initialized with a lunar mass, grow from discs whose finite stores of mm-cm sized pebbles drift inward across all radii in viscously accreting gas. For every 1 $M_\oplus$ netted by a core, at least 10 $M_\oplus$ and possibly much more are lost to radial drift. Core growth rates are typically exponentially sensitive to particle Stokes number, turbulent Mach number, and solid surface density. This exponential sensitivity, when combined with disc migration, tends to generate binary outcomes from 0.1-30 AU: either sub-Earth cores remain sub-Earth, or explode into Jupiters, with the latter migrating inward to varying degrees. When Jupiter-breeding cores assemble from mm-cm sized pebbles, they do so in discs where such particles drain out in $\sim$10$^5$ yr or less; such fast-draining discs do not fit mm-wave observations.Comment: Accepted to MNRA

Effect of collecting duct histology on renal cell cancer outcome.

PURPOSE: Collecting duct renal cell carcinoma is a rare entity. Recent surgical series of the condition showed conflicting results. We used an American population based data set to compare the survival experience of patients with collecting duct vs clear cell renal cell carcinoma. MATERIALS AND METHODS: Cases of collecting duct and clear cell renal cell carcinoma were identified in the Surveillance, Epidemiology and End Results program (2001 to 2005). Demographic and pathological characteristics at diagnosis were compared. Differences in disease specific survival were compared with univariate and multivariate Cox regression analysis. RESULTS: A total of 160 collecting duct renal cell carcinoma cases were present in the database from 2001 to 2005. In that time 33,252 clear cell renal cell carcinoma cases were diagnosed. Collecting duct renal cell carcinoma was more common in black than in white patients (23% vs 9%, p <0.001). Collecting duct renal cell carcinoma was more commonly T3+ than T2/T1 (33% vs 18%, p <0.001) and metastatic than regional/local (28% vs 17%, p = 0.001). Nephrectomy rates were similar (84% and 78%, p = 0.06). The 3-year disease specific survival rate was 58% and 79% for collecting duct and clear cell renal cell carcinoma, respectively. On multivariate analysis there was an increased mortality risk in patients with collecting duct vs clear cell renal cell carcinoma (HR 2.42, 95% CI 1.72-3.39, p = 0.001). CONCLUSIONS: Compared to patients with clear cell renal cell carcinoma those with collecting duct renal cell carcinoma have higher stage and are more often black. Even after adjusting for demographic, surgical and pathological factors disease specific survival is significantly worse in patients with collecting duct rather than clear cell renal cell carcinoma. Further research into the biology of this rare tumor is required to explain these results

Ectopy on a single 12‐lead ECG, incident cardiac myopathy, and death in the community

BackgroundAtrial fibrillation and heart failure are 2 of the most common diseases, yet ready means to identify individuals at risk are lacking. The 12-lead ECG is one of the most accessible tests in medicine. Our objective was to determine whether a premature atrial contraction observed on a standard 12-lead ECG would predict atrial fibrillation and mortality and whether a premature ventricular contraction would predict heart failure and mortality.Methods and resultsWe utilized the CHS (Cardiovascular Health) Study, which followed 5577 participants for a median of 12&nbsp;years, as the primary cohort. The ARIC (Atherosclerosis Risk in Communities Study), the replication cohort, captured data from 15&nbsp;792 participants over a median of 22&nbsp;years. In the CHS, multivariable analyses revealed that a baseline 12-lead ECG premature atrial contraction predicted a 60% increased risk of atrial fibrillation (hazard ratio, 1.6; 95% CI, 1.3-2.0; P&lt;0.001) and a premature ventricular contraction predicted a 30% increased risk of heart failure (hazard ratio, 1.3; 95% CI, 1.0-1.6; P=0.021). In the negative control analyses, neither predicted incident myocardial infarction. A premature atrial contraction was associated with a 30% increased risk of death (hazard ratio, 1.3; 95% CI, 1.1-1.5; P=0.008) and a premature ventricular contraction was associated with a 20% increased risk of death (hazard ratio, 1.2; 95% CI, 1.0-1.3; P=0.044). Similarly statistically significant results for each analysis were also observed in ARIC.ConclusionsBased on a single standard ECG, a premature atrial contraction predicted incident atrial fibrillation and death and a premature ventricular contraction predicted incident heart failure and death, suggesting that this commonly used test may predict future disease

A balanced budget view on forming giant planets by pebble accretion

Pebble accretion refers to the assembly of rocky planet cores from particles whose velocity dispersions are damped by drag from circumstellar disc gas. Accretion cross-sections can approach maximal Hill-sphere scales for particles whose Stokes numbers approach unity. While fast, pebble accretion is also lossy. Gas drag brings pebbles to protocores but also sweeps them past; those particles with the largest accretion cross-sections also have the fastest radial drift speeds and are the most easily drained out of discs. We present a global model of planet formation by pebble accretion that keeps track of the disc’s mass budget. Cores, each initialized with a lunar mass, grow from discs whose finite stores of mm–cm-sized pebbles drift inward across all radii in viscously accreting gas. For every 1 M_⊕ netted by a core, at least 10 M_⊕ and possibly much more are lost to radial drift. Core growth rates are typically exponentially sensitive to particle Stokes number, turbulent Mach number, and solid surface density. This exponential sensitivity, when combined with disc migration, tends to generate binary outcomes from 0.1 to 30 au: either sub-Earth cores remain sub-Earth, or explode into Jupiters, with the latter migrating inward to varying degrees. When Jupiter-breeding cores assemble from mm–cm-sized pebbles, they do so in discs where such particles drain out in ∼10^5 yr or less; such fast-draining discs do not fit mm-wave observations

Order within disorder: the atomic structure of ion-beam sputtered amorphous tantala (a-Ta2O5)

Amorphous tantala (a-Ta2O5) is a technologically important material often used in high-performance coatings. Understanding this material at the atomic level provides a way to further improve performance. This work details extended X-ray absorption fine structure measurements of a-Ta2O5 coatings, where high-quality experimental data and theoretical fits have allowed a detailed interpretation of the nearest-neighbor distributions. It was found that the tantalum atom is surrounded by four shells of atoms in sequence; oxygen, tantalum, oxygen, and tantalum. A discussion is also included on how these models can be interpreted within the context of published crystalline Ta 2O5 and other a-T2O5 studies

LNK suppresses interferon signaling in melanoma.

LNK (SH2B3) is a key negative regulator of JAK-STAT signaling which has been extensively studied in malignant hematopoietic diseases. We found that LNK is significantly elevated in cutaneous melanoma; this elevation is correlated with hyperactive signaling of the RAS-RAF-MEK pathway. Elevated LNK enhances cell growth and survival in adverse conditions. Forced expression of LNK inhibits signaling by interferon-STAT1 and suppresses interferon (IFN) induced cell cycle arrest and cell apoptosis. In contrast, silencing LNK expression by either shRNA or CRISPR-Cas9 potentiates the killing effect of IFN. The IFN-LNK signaling is tightly regulated by a negative feedback mechanism; melanoma cells exposed to IFN upregulate expression of LNK to prevent overactivation of this signaling pathway. Our study reveals an unappreciated function of LNK in melanoma and highlights the critical role of the IFN-STAT1-LNK signaling axis in this potentially devastating disease. LNK may be further explored as a potential therapeutic target for melanoma immunotherapy