Neutral Gas Properties and Lyα\alpha Escape in Extreme Green Pea Galaxies

Mechanisms regulating the escape of Ly$\alpha$ photons and ionizing radiation remain poorly understood. To study these processes we analyze VLA 21cm observations of one Green Pea (GP), J160810+352809 (hereafter J1608), and HST COS spectra of 17 GP galaxies at $z<0.2$. All are highly ionized: J1608 has the highest [O III] $\lambda5007$/[O II] $\lambda3727$ for star-forming galaxies in SDSS, and the 17 GPs have [O III]/[O II] $\geq6.6$. We set an upper limit on J1608's HI mass of $\log M_{HI}/M_\odot=8.4$, near or below average compared to similar mass dwarf galaxies. In the COS sample, eight GPs show Ly$\alpha$ absorption components, six of which also have Ly$\alpha$ emission. The HI column densities derived from Ly$\alpha$ absorption are high, $\log N_{HI}/$cm$^{-2}=19-21$, well above the LyC optically thick limit. Using low-ionization absorption lines, we measure covering fractions (f_{\mbox{cov}}) of $0.1-1$, and find that f_{\mbox{cov}} strongly anti-correlates with Ly$\alpha$ escape fraction. Low covering fractions may facilitate Ly$\alpha$ and LyC escape through dense neutral regions. GPs with f_{\mbox{cov}}\sim1 all have low neutral gas velocities, while GPs with lower f_{\mbox{cov}}=0.2-0.6 have a larger range of velocities. Conventional mechanical feedback may help establish low f_{\mbox{cov}} in some cases, whereas other processes may be important for GPs with low velocities. Finally, we compare f_{\mbox{cov}} with proposed indicators of LyC escape. Ionizing photon escape likely depends on a combination of neutral gas geometry and kinematics, complicating the use of emission-line diagnostics for identifying LyC emitters.Comment: 21 pages, 11 figures, accepted for publication in Ap

Total Molecular Gas Masses of Planck - Herschel Selected Strongly Lensed Hyper Luminous Infrared Galaxies

We report the detection of CO(1 - 0) line emission from seven Planck and Herschel selected hyper luminous (LIR(8-1000um) > 10^13Lsun) infrared galaxies with the Green Bank Telescope (GBT). CO(1 - 0) measurements are a vital tool to trace the bulk molecular gas mass across all redshifts. Our results place tight constraints on the total gas content of these most apparently luminous high-z star-forming galaxies (apparent IR luminosities of LIR > 10^(13-14) Lsun), while we confirm their predetermined redshifts measured using the Large Millimeter Telescope, LMT (zCO = 1.33 - 3.26). The CO(1 - 0) lines show similar profiles as compared to Jup = 2 -4 transitions previously observed with the LMT. We report enhanced infrared to CO line luminosity ratios of = 110 (pm 22) Lsun(K km s^-1 pc^-2)^-1 compared to normal star-forming galaxies, yet similar to those of well-studied IR-luminous galaxies at high-z. We find average brightness temperature ratios of = 0.93 (2 sources), = 0.34 (5 sources), and = 0.18 (1 source). The r31 and r41 values are roughly half the average values for SMGs. We estimate the total gas mass content as uMH2 = (0.9 - 27.2) x 10^11(alphaCO/0.8)Msun, where u is the magnification factor and alphaCO is the CO line luminosity to molecular hydrogen gas mass conversion factor. The rapid gas depletion times are, on average, tau = 80 Myr, which reveal vigorous starburst activity, and contrast the Gyr depletion timescales observed in local, normal star-forming galaxies.Comment: published in MNRAS, 9pages, 5fig

Neutral Gas Properties and Lyα Escape in Extreme Green Pea Galaxies

Mechanisms regulating the escape of Lyα photons and ionizing radiation remain poorly understood. To study these processes, we analyze Very Large Array 21 cm observations of one Green Pea (GP), J160810+352809 (hereafter J1608), and Hubble Space Telescope Cosmic Origins Spectrograph (COS) spectra of 17 GP galaxies at . All are highly ionized: J1608 has the highest [O iii] λ5007/[O ii] λ3727 for star-forming galaxies in Sloan Digital Sky Survey, and the 17 GPs have [O iii]/[O ii] ≥ 6.6. We set an upper limit on J1608\u27s H i mass of , near or below average compared to similar-mass dwarf galaxies. In the COS sample, eight GPs show Lyα absorption components, six of which also have Lyα emission. The H i column densities derived from Lyα absorption are high, cm−2 = 19–21, well above the LyC optically thick limit. Using low-ionization absorption lines, we measure covering fractions () of 0.1–1 and find that strongly anticorrelates with Lyα escape fraction. Low covering fractions may facilitate Lyα and LyC escape through dense neutral regions. GPs with all have low neutral gas velocities, while GPs with lower have a larger range of velocities. Conventional mechanical feedback may help establish low in some cases, whereas other processes may be important for GPs with low velocities. Finally, we compare with proposed indicators of LyC escape. Ionizing photon escape likely depends on a combination of neutral gas geometry and kinematics, complicating the use of emission-line diagnostics for identifying LyC emitters

Registrar wellness in Botswana: Measuring burnout and identifying ways to improve wellness

Background. Burnout during registrar training is high, especially in resource-limited settings where stressors are intensified. Burnout leads to decreased quality of life for doctors, poor job and patient satisfaction, and difficulty retaining doctors.Objectives. Primary: to measure burnout among registrars working at Princess Marina Hospital in Gaborone, Botswana. Secondary: to determine factors contributing to burnout and identify potential wellness interventions.Methods. The validated Maslach Burnout Inventory was used to measure the degree of emotional exhaustion, depersonalisation and personal accomplishment. Work-related difficulties and potential wellness interventions were explored through multiple-choice and open-ended questions.Results. Of 40 eligible registrars, 20 (50%) completed the survey. High levels of burnout were reported for emotional exhaustion in 65% (13/20), depersonalisation in 45% (9/20), and personal accomplishment in 35% (7/20) of registrars. A high degree of burnout was reported by 75% (15/20) of registrars in one or more domains. In the previous 7 days, registrars worked an average of 77 hours, took 1.5 overnight calls, slept 5.7 hours per night, and 53% (10/19) had ≥1 of their patients die. Five (25%) registrars considered leaving Botswana to work in another country, which correlated with those with the highest degree of burnout. The most common frustrations included insufficient salary and limited medical resources. Suggested interventions included improved mentorship and wellness lectures.Conclusions. There is a high degree of burnout, especially emotional exhaustion, among registrars. Encouragingly, most registrars have a desire to work in Botswana after training. Future research on improving registrar wellness in low-resource settings is urgently needed

Optical Morphologies of Millijansky Radio Galaxies Observed by HST and in the VLA FIRST Survey

We report on a statistical study of the 51 radio galaxies at the millijansky flux level from the Faint Images of the Radio Sky at Twenty centimeters, including their optical morphologies and structure obtained with the Hubble Space Telescope. Our optical imaging is significantly deeper (~2 mag) than previous studies with the superior angular resolution of space-based imaging. We that find 8/51 (16%) of the radio sources have no optically identifiable counterpart to AB~24 mag. For the remaining 43 sources, only 25 are sufficiently resolved in the HST images to reliably assign a visual classification: 15 (60%) are elliptical galaxies, 2 (8%) are late-type spiral galaxies, 1 (4%) is an S0, 3 (12%) are point-like objects (quasars), and 4 (16%) are merger systems. We find a similar distribution of optical types with measurements of the Sersic index. The optical magnitude distribution of these galaxies peaks at I~20.7+-0.5 AB mag, which is ~3 mag brighter than the depth of our typical HST field and is thus not due to the WFPC2 detection limit. This supports the luminosity-dependent density evolutionary model, where the majority of faint radio galaxies typically have L*-optical luminosities and a median redshift of z~0.8 with a relatively abrupt redshift cut-off at z>~2. We discuss our results in the context of the evolution of elliptical galaxies and active galactic nuclei.Comment: 20 pages, 8 figures, 51 galaxy images, and 5 tables. Uses emulateapj.cls and natbib.sty. Accepted to ApJS. High resolution images are available upon reques

Marketing, the past and corporate heritage

Argues for a more expansive conceptualisation of the past’s relevance in, and for, marketing. Such a differentiated approach to the past is pregnant with possibilities in terms of advancing scholarship apropos temporal agency in marketing along with consumption practices. Symptomatic of this perspective is the increased mindfulness of the rich palate of past-related concepts. Significantly, the corporate heritage notion - because of its omni-temporal nature - represents a distinct and meaningful vector on the past by coalescing the past, present and future into a new type of temporality. As such, the authors reason this expansive conceptualisation of ‘the past-in-marketing’ is both timely and efficacious. Whilst sensitive of the importance of the historical method in marketing and the history of marketing scholarship and practice per se. This broader marketing approach to and of the past highlights the ideational and material manifestations of the past-in-the-present and an envisaged past-in-the future

The relationship between magnetic and electrophysiological responses to complex tactile stimuli

<p>Abstract</p> <p>Background</p> <p>Magnetoencephalography (MEG) has become an increasingly popular technique for non-invasively characterizing neuromagnetic field changes in the brain at a high temporal resolution. To examine the reliability of the MEG signal, we compared magnetic and electrophysiological responses to complex natural stimuli from the same animals. We examined changes in neuromagnetic fields, local field potentials (LFP) and multi-unit activity (MUA) in macaque monkey primary somatosensory cortex that were induced by varying the rate of mechanical stimulation. Stimuli were applied to the fingertips with three inter-stimulus intervals (ISIs): 0.33s, 1s and 2s.</p> <p>Results</p> <p>Signal intensity was inversely related to the rate of stimulation, but to different degrees for each measurement method. The decrease in response at higher stimulation rates was significantly greater for MUA than LFP and MEG data, while no significant difference was observed between LFP and MEG recordings. Furthermore, response latency was the shortest for MUA and the longest for MEG data.</p> <p>Conclusion</p> <p>The MEG signal is an accurate representation of electrophysiological responses to complex natural stimuli. Further, the intensity and latency of the MEG signal were better correlated with the LFP than MUA data suggesting that the MEG signal reflects primarily synaptic currents rather than spiking activity. These differences in latency could be attributed to differences in the extent of spatial summation and/or differential laminar sensitivity.</p

Deep 1.1 mm-wavelength imaging of the GOODS-South field by AzTEC/ASTE -- II. Redshift distribution and nature of the submillimetre galaxy population

We report the results of the counterpart identification and a detailed analysis of the physical properties of the 48 sources discovered in our deep 1.1mm wavelength imaging survey of the GOODS-South field using the AzTEC instrument on the Atacama Submillimeter Telescope Experiment (ASTE). One or more robust or tentative counterpart candidate is found for 27 and 14 AzTEC sources, respectively, by employing deep radio continuum, Spitzer MIPS & IRAC, and LABOCA 870 micron data. Five of the sources (10%) have two robust counterparts each, supporting the idea that these galaxies are strongly clustered and/or heavily confused. Photometric redshifts and star formation rates (SFRs) are derived by analyzing UV-to-optical and IR-to-radio SEDs. The median redshift of z~2.6 is similar to other earlier estimates, but we show that 80% of the AzTEC-GOODS sources are at z>2, with a significant high redshift tail (20% at z>3.3). Rest-frame UV and optical properties of AzTEC sources are extremely diverse, spanning 10 magnitude in the i- and K-band photometry with median values of i=25.3 and K=22.6 and a broad range of red colour (i-K=0-6). These AzTEC sources are some of the most luminous galaxies in the rest-frame optical bands at z>2, with inferred stellar masses of (1-30) x 10^{10} solar masses and UV-derived star formation rates of SFR(UV) > 10-1000 solar masses per year. The IR-derived SFR, 200-2000 solar masses per year, is independent of redshift or stellar mass. The resulting specific star formation rates, SSFR = 1-100 per Gyr, are 10-100 times higher than similar mass galaxies at z=0, and they extend the previously observed rapid rise in the SSFR with redshift to z=2-5. These galaxies have a SFR high enough to have built up their entire stellar mass within their Hubble time. We find only marginal evidence for an AGN contribution to the near-IR and mid-IR SEDs. (abridged)Comment: 31 pages including 14 figures, accepted for publication in the MNRAS. A higher quality Figure 1 is also included as Figure1.jp

A companion to a quasar at redshift 4.7

There is a growing consensus that the emergence of quasars at high redshifts is related to the onset of galaxy formation, suggesting that the detection of concentrations of gas accompanying such quasars should provide clues about the early history of galaxies. Quasar companions have been recently identified at redshifts up to $z \approx 3$. Here we report observations of Lyman-$\alpha$ emission (a tracer of ionised hydrogen) from the companion to a quasar at $z$=4.702, corresponding to a time when the Universe was less than ten per cent of its present age. We argue that most of the emission arises in a gaseous nebula that has been photoionised by the quasar, but an additional component of continuum light -perhaps quasar light scattered from dust in the companion body, or emission from young stars within the nebula- appears necessary to explain the observations. These observations may be indicative of the first stages in the assembly of galaxy-sized structures.Comment: 8 pages, 4 figures, plain LaTeX. Accepted for publication in Natur