The high frequency of phosphoinositide 3-kinase (PI3K) pathway alterations in cancer has led to a surge in the development of PI3K inhibitors. Many of these targeted therapies are currently in ...clinical trials and show great promise for the treatment of PI3K-addicted tumors. These recent developments call for a re-evaluation of the oncogenic mechanisms behind PI3K pathway alterations. This pathway is unique in that every major node is frequently mutated or amplified in a wide variety of solid tumors. Receptor tyrosine kinases upstream of PI3K, the p110 alpha catalytic subunit of PI3K, the downstream kinase, AKT, and the negative regulator, PTEN, are all frequently altered in cancer. In this review, we will examine the oncogenic properties of these genetic alterations to understand whether they are redundant or distinct and propose treatment strategies tailored for these genetic lesions.
We investigate the fraction of starbursts, starburst-active galactic nucleus (AGN) composites, Seyferts, and low-ionization narrow emission-line region galaxies (LINERs) as a function of infrared ...luminosity (L{sub IR}) and merger progress for approx500 infrared (IR)-selected galaxies. Using the new optical classifications afforded by the extremely large data set of the Sloan Digital Sky Survey, we find that the fraction of LINERs in IR-selected samples is rare (<5%) compared with other spectral types. The lack of strong IR emission in LINERs is consistent with recent optical studies suggesting that LINERs contain AGN with lower accretion rates than in Seyfert galaxies. Most previously classified IR-luminous LINERs are classified as starburst-AGN composite galaxies in the new scheme. Starburst-AGN composites appear to 'bridge' the spectral evolution from starburst to AGN in ULIRGs. The relative strength of the AGN versus starburst activity shows a significant increase at high IR luminosity. In ULIRGs (L{sub IR} > 10{sup 12} L{sub sun}), starburst-AGN composite galaxies dominate at early-intermediate stages of the merger, and AGN galaxies dominate during the final merger stages. Our results are consistent with models for IR-luminous galaxies where mergers of gas-rich spirals fuel both starburst and AGN, and where the AGN becomes increasingly dominant during the final merger stages of the most luminous IR objects.
With the rapid progress in metallicity gradient studies at high redshift, it is imperative that we thoroughly understand the systematics in these measurements. This work investigates how the NII/H ...alpha -ratio-based metallicity gradients change with angular resolution, signal to noise (S/N), and annular binning parameters. Two approaches are used: (1) we downgrade the high angular resolution integral-field data of a gravitationally lensed galaxy and re-derive the metallicity gradients at different angular resolution; (2) we simulate high-redshift integral field spectroscopy observations under different angular resolution and S/N conditions using a local galaxy with a known gradient. We find that the measured metallicity gradient changes systematically with angular resolution and annular binning. Seeing-limited observations produce significantly flatter gradients than higher angular resolution observations. There is a critical angular resolution limit beyond which the measured metallicity gradient is substantially different to the intrinsic gradient. This critical angular resolution depends on the intrinsic gradient of the galaxy and is < or =, slant0".02 for our simulated galaxy. We show that seeing-limited high-redshift metallicity gradients are likely to be strongly affected by resolution-driven gradient flattening. Annular binning with a small number of annuli produces a more flattened gradient than the intrinsic gradient due to weak line smearing. For three-annulus bins, a minimum S/N of ~5 on the NII line is required for the faintest annulus to constrain the gradients with meaningful errors.
We present adaptive optics-assisted integral field spectroscopy around the Hα or Hβ lines of 12 gravitationally lensed galaxies obtained with VLT/SINFONI, Keck/OSIRIS and Gemini/NIFS. We combine ...these data with previous observations and investigate the dynamics and star formation properties of 17 lensed galaxies at 1 < z < 4. Thanks to gravitational magnification of 1.4–90 times by foreground clusters, effective spatial resolutions of 40–700 pc are achieved. The magnification also allows us to probe lower star formation rates (SFRs) and stellar masses than unlensed samples; our target galaxies feature dust-corrected SFRs derived from Hα or Hβ emission of ∼0.8–40 M⊙ yr−1, and stellar masses M
* ∼ 4 × 108–6 × 1010 M⊙. All of the galaxies show velocity gradients, with 59 per cent consistent with being rotating discs and a likely merger fraction of 29 per cent, with the remaining 12 per cent classed as ‘undetermined’. We extract 50 star-forming clumps with sizes in the range 60 pc–1 kpc from the Hα (or Hβ) maps, and find that their surface brightnesses, Σclump and their characteristic luminosities, L
0, evolve to higher luminosities with redshift. We show that this evolution can be described by fragmentation on larger scales in gas-rich discs, and is likely to be driven by evolving gas fractions.
We present the first results of our pilot study of eight photometrically selected Lyman-continuum (LyC) emitting galaxy candidates from the COSMOS field and focus on their optical emission line ...ratios. Observations were performed in the H and K bands using the Multi-Object Spectrometer for Infra-Red Exploration (MOSFIRE) instrument at the Keck Observatory, targeting the O II, H β, and O III emission lines. We find that photometrically selected LyC emitting galaxy candidates have high ionization parameters, based on their high O III/O II ratios (O32), with an average ratio for our sample of 2.5 ± 0.2. Preliminary results of our companion Low-Resolution Imaging Spectrometer (LRIS) observations, targeting LyC and Ly α, show that those galaxies with the largest O32 are typically found to also be Ly α emitters. High O32 galaxies are also found to have tentative non-zero LyC escape fractions (fesc(LyC)) based on u band photometric detections. These results are consistent with samples of highly ionized galaxies, including confirmed LyC emitting galaxies from the literature. We also perform a detailed comparison between the observed emission line ratios and simulated line ratios from density bounded H II regions modelled using the photoionization code MAPPINGS V. Estimates of fesc(LyC) for our sample fall in the range from 0.0 to 0.23 and suggest possible tension with published correlations between O32 and fesc(LyC), adding weight to dichotomy of arguments in the literature. We highlight the possible effects of clumpy geometry and mergers that may account for such tension.
A binned likelihood for stochastic models Argüelles, C. A.; Schneider, A.; Yuan, T.
The journal of high energy physics,
06/2019, Volume:
2019, Issue:
6
Journal Article
Peer reviewed
Open access
A
bstract
Metrics of model goodness-of-fit, model comparison, and model parameter estimation are the main categories of statistical problems in science. Bayesian and frequentist methods that address ...these questions often rely on a likelihood function, which is the key ingredient in order to assess the plausibility of model parameters given observed data. In some complex systems or experimental setups, predicting the outcome of a model cannot be done analytically, and Monte Carlo techniques are used. In this paper, we present a new analytic likelihood that takes into account Monte Carlo uncertainties, appropriate for use in the large and small sample size limits. Our formulation performs better than semi-analytic methods, prevents strong claims on biased statements, and provides improved coverage properties compared to available methods.
We present a comprehensive observational study of the gas-phase metallicity of star-forming galaxies from z ~ 0 arrow right 3. We combine our new sample of gravitationally lensed galaxies with ...existing lensed and non-lensed samples to conduct a large investigation into the mass-metallicity (MZ) relation at z > 1. We apply a self-consistent metallicity calibration scheme to investigate the metallicity evolution of star-forming galaxies as a function of redshift. The lensing magnification ensures that our sample spans an unprecedented range of stellar mass (3 x 10 super(7) to 6 x 10 super(10) M sub(middot in circle)). We find that at the median redshift of z = 2.07, the median metallicity of the lensed sample is 0.35 dex lower than the local SDSS star-forming galaxies and 0.18 dex lower than the z ~ 0.8 DEEP2 galaxies. We also present the z ~ 2 MZ relation using 19 lensed galaxies. A more rapid evolution is seen between z ~ 1 arrow right 3 than z ~ 0 arrow right 1 for the high-mass galaxies (10 super(9.5) M sub(middot in circle) < Mlow * < 10 super(11) M sub(middot in circle)), with almost twice as much enrichment between z ~ 1 arrow right 3 than between z ~ 1 arrow right 0. We compare this evolution with the most recent cosmological hydrodynamic simulations with momentum-driven winds. We find that the model metallicity is consistent with the observed metallicity within the observational error for the low-mass bins. However, for higher masses, the model overpredicts the metallicity at all redshifts. The overprediction is most significant in the highest mass bin of 10 super(10)-10 super(11) M sub(middot in circle).
The electric field effect in ferromagnetic semiconductors enables switching of the magnetization, which is a key technology for spintronic applications. We demonstrated electric field—induced ...ferromagnetism at room temperature in a magnetic oxide semiconductor, (Ti,Co)O 2 , by means of electric double-layer gating with high-density electron accumulation (>10 14 per square centimeter). By applying a gate voltage of a few volts, a low-carrier paramagnetic state was transformed into a high-carrier ferromagnetic state, thereby revealing the considerable role of electron carriers in high-temperature ferromagnetism and demonstrating a route to room-temperature semiconductor spintronics.
We present the spatially resolved emission line ratio properties of a ~10 super(10) M sub(middot in circle) star-forming galaxy at redshift z = 1.03. This galaxy is gravitationally lensed as a ...triple-image giant arc behind the massive lensing cluster A 2667. The main image of the galaxy has magnification factors of 14 + or - 2.1 in flux and ~2 x 7 in area, yielding an intrinsic spatial resolution of 115-405 pc after adaptive optics correction with OSIRIS at KECK II. The Hubble Space Telescope morphology shows a clumpy structure and the Halpha kinematics indicates a large velocity dispersion with V sub(max)sin (i)/sigma ~ 0.73, consistent with high-redshift disk galaxies of similar masses. From the NII/Halpha line ratios, we find that the central 350 pc of the galaxy is dominated by star formation. The NII/Halpha line ratios are higher in the outer disk than in the central regions. Most noticeably, we find a blueshifted region of strong NII/Halpha emission in the outer disk. Applying our recent H II region and slow-shock models, we propose that this elevated NII/Halpha ratio region is contaminated by a significant fraction of shock excitation due to galactic outflows. Our analysis suggests that shocked regions may mimic flat or inverted metallicity gradients at high redshift.
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