Mean Hα+[N ii]+[S ii] EW inferred for star-forming galaxies at z ∼ 5.1–5.4 using high-quality Spitzer /IRAC photometry

Recent Spitzer/InfraRed Array Camera (IRAC) photometric observations have revealed that rest-frame optical emission lines contribute significantly to the broad-band fluxes of high-redshift galaxies. Specifically, in the narrow redshift range z ∼ 5.1–5.4 the [3.6]–[4.5] colour is expected to be very red, due to contamination of the 4.5 μm band by the dominant Hα line, while the 3.6 μm filter is free of nebular emission lines. We take advantage of new reductions of deep Spitzer/IRAC imaging over the Great Observatories Origins Deep Survey-North+South fields (Labbé et al. 2015) to obtain a clean measurement of the mean Hα equivalent width (EW) from the [3.6]–[4.5] colour in the redshift range z = 5.1–5.4. The selected sources either have measured spectroscopic redshifts (13 sources) or lie very confidently in the redshift range z = 5.1–5.4 based on the photometric redshift likelihood intervals (11 sources). Our zphot = 5.1–5.4 sample and zspec = 5.10–5.40 spectroscopic sample have a mean [3.6]–[4.5] colour of 0.31 ± 0.05 and 0.35 ± 0.07 mag, implying a rest-frame EW (Hα+[N II]+[S II]) of 665 ± 53 and 707 ± 74 Å, respectively, for sources in these samples. These values are consistent albeit slightly higher than derived by Stark et al. at z ∼ 4, suggesting an evolution to higher values of the Hα+[N II]+[S II] EW at z > 2. Using the 3.6 μm band, which is free of emission line contamination, we perform robust spectral energy distribution fitting and find a median specific star formation rate of sSFR = 17+2−517−5+2 Gyr−1, 7+1−2×7−2+1× higher than at z ∼ 2. We find no strong correlation (<2σ) between the Hα+[N II]+[S II] EW and the stellar mass of sources. Before the advent of JWST, improvements in these results will come through an expansion of current spectroscopic samples and deeper Spitzer/IRAC measurements

Modification of a sonographic enthesitis score to differentiate between psoriatic arthritis and young healthy volunteers

Objectives: We aimed to describe sonographic structural and inflammatory changes in entheses of patients with recently diagnosed psoriatic arthritis (PsA), patients with established PsA, and young healthy volunteers, and to investigate whether the MAdrid Sonographic Enthesitis Index (MASEI) enables us to distinguish these groups in an extreme comparison. Method: New and established PsA patients and healthy volunteers (aged 20–30 years) were recruited. The triceps, quadriceps, patellar, Achilles and elbow extensor tendon insertion, and plantar fascia entheses were investigated sonographically for structural changes, erosions, calcifications, increased thickness, bursitis, and power Doppler (PD) signal according to the MASEI. Results: The study included 25 new and 25 established PsA patients, and 25 healthy volunteers. Increased thickness and PD signal in knee entheses were common for patients and healthy volunteers, while changes at other locations predominantly occurred in patients only. PD was recoded (1, one spot; 1.5, two or three spots; 2, confluent signal; 3, severe confluent signal) and thickness of knee entheses excluded. This resulted in different modified MASEI scores between PsA patients and young healthy controls: median (interquartile range) modified MASEI of 13 (10–22.5) in new PsA, 13.5 (9.5–18) in established PsA, and 3 (1–8.5) in healthy volunteers (p = 0.002). Conclusions: Structural ultrasound changes and PD in entheses are common in both new and established PsA and healthy controls. MASEI score did not differentiate PsA patients from young healthy volu

Mean H alpha plus [N II] plus [S II] EW inferred for star-forming galaxies at z similar to 5.1-5.4 using high-quality Spitzer/IRAC photometry

Recent Spitzer/InfraRed Array Camera (IRAC) photometric observations have revealed that rest-frame optical emission lines contribute significantly to the broad-band fluxes of high-redshift galaxies. Specifically, in the narrow redshift range z ∼ 5.1–5.4 the [3.6]–[4.5] colour is expected to be very red, due to contamination of the 4.5 μm band by the dominant Hα line, while the 3.6 μm filter is free of nebular emission lines. We take advantage of new reductions of deep Spitzer/IRAC imaging over the Great Observatories Origins Deep Survey-North+South fields (Labbé et al. 2015) to obtain a clean measurement of the mean Hα equivalent width (EW) from the [3.6]–[4.5] colour in the redshift range z = 5.1–5.4. The selected sources either have measured spectroscopic redshifts (13 sources) or lie very confidently in the redshift range z = 5.1–5.4 based on the photometric redshift likelihood intervals (11 sources). Our zphot = 5.1–5.4 sample and zspec = 5.10–5.40 spectroscopic sample have a mean [3.6]–[4.5] colour of 0.31 ± 0.05 and 0.35 ± 0.07 mag, implying a rest-frame EW (Hα+[N II]+[S II]) of 665 ± 53 and 707 ± 74 Å, respectively, for sources in these samples. These values are consistent albeit slightly higher than derived by Stark et al. at z ∼ 4, suggesting an evolution to higher values of the Hα+[N II]+[S II] EW at z > 2. Using the 3.6 μm band, which is free of emission line contamination, we perform robust spectral energy distribution fitting and find a median specific star formation rate of sSFR = 17+2−5 Gyr−1, 7+1−2× higher than at z ∼ 2. We find no strong correlation (<2σ) between the Hα+[N II]+[S II] EW and the stellar mass of sources. Before the advent of JWST, improvements in these results will come through an expansion of current spectroscopic samples and deeper Spitzer/IRAC measurements

Absence of ultrasound inflammation in patients presenting with arthralgia rules out the development of arthritis

Background: To decrease the burden of disease of rheumatoid arthritis (RA), patients at risk for RA need to be identified as early as possible, preferably when no clinically apparent synovitis can be detected. Up to now, it has been fairly difficult to identify those patients with arthralgia who develop inflammatory arthritis (IA), but recent studies using ultrasound (US) suggest that earlier detection is possible. We aimed to identify patients with arthralgia developing IA within 1year using US to detect subclinical synovitis at first consultation. Methods: In a multi-centre cohort study, we followed patients with arthralgia with at least two painful joints of the hands, feet or shoulders without clinical synovitis over 1year. Symptom duration was<1year, and symptoms were not explained by other conditions. At baseline and at 6 and 12months, data were collected for physical examinations, laboratory values and diagnoses. At baseline, we examined 26 joints ultrasonographically (bilateral metacarpophalangeal joints 2-5, proximal interphalangeal joints 2-5, wrist and metatarsophalangeal joints 2-5). Scoring was done semi-quantitatively on greyscale (GS; 0-3) and power Doppler (PD; 0-3) images. US synovitis was defined as GS≥2 and/or PD≥1. IA was defined as clinical soft tissue swelling. Sensitivity and specificity were used to assess the diagnostic value of US for the development of IA. Univariate logistic regression was used to analyse the association between independent variables and the incidence of IA. For multivariate logistic regression, the strongest variables (p<0.157) were selected. Missing values for independent variables were

The Lyman-Continuum Photon Production Efficiency ξ_ion of z ~ 4-5 Galaxies from IRAC-based Hα Measurements: Implications for the Escape Fraction and Cosmic Reionization

Interstellar matter and star formatio

THE LYMAN-CONTINUUM PHOTON PRODUCTION EFFICIENCY xi(ION) OF z similar to 4-5 GALAXIES FROM IRAC-BASED H alpha MEASUREMENTS: IMPLICATIONS FOR THE ESCAPE FRACTION AND COSMIC REIONIZATION

Galaxies represent one of the preferred candidate sources to drive the reionization of the universe. Even as gains are made in mapping the galaxy UV luminosity density to $z\gt 6$, significant uncertainties remain regarding the conversion to the implied ionizing emissivity. The relevant unknowns are the Lyman-continuum (LyC) photon production efficiency ${\xi }_{\mathrm{ion}}$ and the escape fraction f esc. As we show here, the first of these unknowns is directly measurable in z = 4–5 galaxies based on the impact the Hα line has on the observed IRAC fluxes. By computing a LyC photon production rate from the implied Hα luminosities for a broad selection of z = 4–5 galaxies and comparing this against the dust-corrected UV-continuum luminosities, we provide the first-ever direct estimates of the LyC photon production efficiency ${\xi }_{\mathrm{ion}}$ for the $z\geqslant 4$ galaxy population. We find $\,{\mathrm{log}}_{10}\,{\xi }_{\mathrm{ion}}/[\mathrm{Hz}\,{\mathrm{erg}}^{-1}]$ to have a mean value of ${25.27}_{-0.03}^{+0.03}$ and ${25.34}_{-0.02}^{+0.02}$ for sub-L* z = 4–5 galaxies adopting Calzetti and SMC dust laws, respectively. Reassuringly, both derived values are consistent with the standard assumed ${\xi }_{\mathrm{ion}}$'s in reionization models, with a slight preference for higher ${\xi }_{\mathrm{ion}}$'s (by ~0.1 dex) adopting the SMC dust law. High values of ${\xi }_{\mathrm{ion}}$ (~25.5–25.8 dex) are derived for the bluest galaxies ($\beta \lt -2.3$) in our samples, independent of dust law and consistent with results for a z = 7.045 galaxy. Such elevated values of ${\xi }_{\mathrm{ion}}$ would have important consequences, indicating that f esc cannot be in excess of 13% for standard assumptions about the faint-end cut-off to the LF and the clumping factor

Absence of ultrasound inflammation in patients presenting with arthralgia rules out the development of arthritis

\u3cp\u3eBACKGROUND: To decrease the burden of disease of rheumatoid arthritis (RA), patients at risk for RA need to be identified as early as possible, preferably when no clinically apparent synovitis can be detected. Up to now, it has been fairly difficult to identify those patients with arthralgia who develop inflammatory arthritis (IA), but recent studies using ultrasound (US) suggest that earlier detection is possible. We aimed to identify patients with arthralgia developing IA within 1 year using US to detect subclinical synovitis at first consultation.\u3c/p\u3e\u3cp\u3eMETHODS: In a multi-centre cohort study, we followed patients with arthralgia with at least two painful joints of the hands, feet or shoulders without clinical synovitis over 1 year. Symptom duration was &lt; 1 year, and symptoms were not explained by other conditions. At baseline and at 6 and 12 months, data were collected for physical examinations, laboratory values and diagnoses. At baseline, we examined 26 joints ultrasonographically (bilateral metacarpophalangeal joints 2-5, proximal interphalangeal joints 2-5, wrist and metatarsophalangeal joints 2-5). Scoring was done semi-quantitatively on greyscale (GS; 0-3) and power Doppler (PD; 0-3) images. US synovitis was defined as GS ≥ 2 and/or PD ≥ 1. IA was defined as clinical soft tissue swelling. Sensitivity and specificity were used to assess the diagnostic value of US for the development of IA. Univariate logistic regression was used to analyse the association between independent variables and the incidence of IA. For multivariate logistic regression, the strongest variables (p &lt; 0.157) were selected. Missing values for independent variables were imputed.\u3c/p\u3e\u3cp\u3eRESULTS: A total of 196 patients were included, and 159 completed 12 months of follow-up. Thirty-one (16%) patients developed IA, of whom 59% showed US synovitis at baseline. The sensitivity and specificity of US synovitis were 59% and 68%, respectively. If no joints were positive on US, negative predictive value was 89%. In the multivariate logistic regression, age (OR 1.1), the presence of morning stiffness for &gt; 30 minutes (OR 3.3) and PD signal (OR 3.4) were associated with incident IA.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: The presence of PD signal, morning stiffness for &gt; 30 minutes and age at baseline were independently associated with the development of IA. Regarding the value of US in the diagnostic workup of patients with early arthralgia at risk for IA, US did perform well in ruling out IA in patients who did not have US synovitis.\u3c/p\u3