33 research outputs found
Accurately predicting the escape fraction of ionizing photons using restframe ultraviolet absorption lines
The fraction of ionizing photons that escape high-redshift galaxies
sensitively determines whether galaxies reionized the early universe. However,
this escape fraction cannot be measured from high-redshift galaxies because the
opacity of the intergalactic medium is large at high redshifts. Without methods
to indirectly measure the escape fraction of high-redshift galaxies, it is
unlikely that we will know what reionized the universe. Here, we analyze the
far-ultraviolet (UV) H I (Lyman series) and low-ionization metal absorption
lines of nine low-redshift, confirmed Lyman continuum emitting galaxies. We use
the H I covering fractions, column densities, and dust attenuations measured in
a companion paper to predict the escape fraction of ionizing photons. We find
good agreement between the predicted and observed Lyman continuum escape
fractions (within ) using both the H I and ISM absorption lines. The
ionizing photons escape through holes in the H I, but we show that dust
attenuation reduces the fraction of photons that escape galaxies. This means
that the average high-redshift galaxy likely emits more ionizing photons than
low-redshift galaxies. Two other indirect methods accurately predict the escape
fractions: the Ly escape fraction and the optical [O III]/[O II] flux
ratio. We use these indirect methods to predict the escape fraction of a sample
of 21 galaxies with rest-frame UV spectra but without Lyman continuum
observations. Many of these galaxies have low escape fractions (\%), but 11 have escape fractions \%. The methods presented here will
measure the escape fractions of high-redshift galaxies, enabling future
telescopes to determine whether star-forming galaxies reionized the early
universe.Comment: Accepted for publication in A&A. 12 pages, 5 figure
Successful desensitization with human insulin in a patient with an insulin allergy and hypersensitivity to protamine: a case report
<p>Abstract</p> <p>Introduction</p> <p>Insulin allergy may occur in patients treated with subcutaneous applications of insulin preparations. Besides additives in the insulin preparation such as protamine, cresol, and phenol, the insulin molecule itself may be the cause of the allergy. In the latter case, therapeutic options are rare.</p> <p>Case presentation</p> <p>A 68-year-old man with poorly controlled type 2 diabetes mellitus received different insulin preparations subcutaneously while on oral medication. Six to eight hours after each subcutaneous application, he developed pruritic plaques with a diameter of >15 cm at the injection sites that persisted for several days. Allergologic testing revealed positive reactions against every insulin preparation and against protamine. Investigation of serum samples demonstrated IgG antibodies against human and porcine insulin. We treated the patient with human insulin using an ultra-rush protocol beginning with 0.004 IU and a rapid augmentation in dose up to 5 IU. Therapy was accompanied by antihistamine therapy. Subsequent conversion to therapy with glargine insulin (6 IE twice daily) was well-tolerated.</p> <p>Conclusion</p> <p>As reported in this case, desensitization with subcutaneously administered human insulin using an ultra-rush protocol in patients with an insulin allergy may present an easy form of therapy that is successful within a few days.</p
CLASSY VII Ly\alpha\ Profiles: The Structure and Kinematics of Neutral Gas and Implications for LyC Escape in Reionization-Era Analogs
Lyman-alpha line profiles are a powerful probe of ISM structure, outflow
speed, and Lyman continuum escape fraction. In this paper, we present the
Ly line profiles of the COS Legacy Archive Spectroscopic SurveY, a
sample rich in spectroscopic analogs of reionization-era galaxies. A large
fraction of the spectra show a complex profile, consisting of a double-peaked
Ly emission profile in the bottom of a damped, Ly absorption
trough. Such profiles reveal an inhomogeneous interstellar medium (ISM). We
successfully fit the damped Ly absorption (DLA) and the Ly
emission profiles separately, but with complementary covering factors, a
surprising result because this approach requires no Ly exchange between
high- and low- paths. The combined distribution
of column densities is qualitatively similar to the bimodal distributions
observed in numerical simulations. We find an inverse relation between
Ly peak separation and the [O III]/[O II] flux ratio, confirming that
the covering fraction of Lyman-continuum-thin sightlines increases as the
Ly peak separation decreases. We combine measurements of Ly
peak separation and Ly red peak asymmetry in a diagnostic diagram which
identifies six Lyman continuum leakers in the CLASSY sample. We find a strong
correlation between the Ly trough velocity and the outflow velocity
measured from interstellar absorption lines. We argue that greater vignetting
of the blueshifted Ly peak, relative to the redshifted peak, is the
source of the well-known discrepancy between shell-model parameters and
directly measured outflow properties. The CLASSY sample illustrates how
scattering of Ly photons outside the spectroscopic aperture reshapes
Ly profiles as the distances to these compact starbursts span a large
range.Comment: 40 pages, 19 figures, 5 tables, submitted to ApJ, comments welcom
The Low-Redshift Lyman Continuum Survey. Unveiling the ISM properties of low- Lyman continuum emitters
Combining 66 ultraviolet (UV) spectra and ancillary data from the
Low-Redshift Lyman Continuum Survey (LzLCS) and 23 LyC observations by earlier
studies, we form a statistical sample of star-forming galaxies at
to study the role of the cold interstellar medium (ISM) gas in the leakage of
ionizing radiation. We first constrain the massive star content (ages and
metallicities) and UV attenuation, by fitting the stellar continuum with a
combination of simple stellar population models. The models, together with
accurate LyC flux measurements, allow to determine the absolute LyC photon
escape fraction for each galaxy (). We measure the
equivalent widths and residual fluxes of multiple HI and low-ionization state
(LIS) lines, and the geometrical covering fraction adopting the picket-fence
model. The spans a wide range, with a median (0.16,
0.84 quantiles) of 0.04 (0.02, 0.20), and 50 out of the 89 galaxies detected in
the LyC. The HI and LIS line equivalent widths scale with the UV luminosity and
attenuation, and inversely with the residual flux of the lines. The HI and LIS
residual fluxes are correlated, indicating that the neutral gas is spatially
traced by the LIS transitions. We find the observed trends of the absorption
lines and the UV attenuation are primarily driven by the covering fraction. The
non-uniform gas coverage demonstrates that LyC photons escape through
low-column density channels in the ISM. The equivalent widths and residual
fluxes of the UV lines strongly correlate with : strong
LyC leakers show weak absorption lines, low UV attenuation, and large
Ly equivalent widths. We finally show that simultaneous UV absorption
line and dust attenuation measurements can predict, on average, the escape
fraction of galaxies and the method can be applied to galaxies across a wide
redshift range.Comment: 30 pages, 16 figures, 3 tables; accepted for publication in Astronomy
and Astrophysics on December 16, 2021. Tables A1 to A4 are part of the LzLCS
science products and will be publicly available in a dedicated websit
The Clinical Variability of Maternally Inherited Diabetes and Deafness Is Associated with the Degree of Heteroplasmy in Blood Leukocytes
Context: Maternally inherited diabetes and deafness (MIDD) is a rare form of diabetes with a matrilineal transmission, sensorineural hearing loss, and macular pattern dystrophy due to an A to G transition at position 3243 of mitochondrial DNA (mtDNA) (m.3243A>G). The phenotypic heterogeneity of MIDD may be the consequence of different levels of mutated mtDNA among mitochondria in a given tissue.
Objective: The aim of the present study was thus to ascertain the correlation between the severity of the phenotype in patients with MIDD and the level of heteroplasmy in the blood leukocytes.
Participants: The GEDIAM prospective multicenter register was initiated in 1995. Eighty-nine Europid patients from this register, with MIDD and the mtDNA 3243A>G mutation, were included. Patients with MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) or with mitochondrial diabetes related to other mutations or to deletions of mtDNA were excluded.
Results: A significant negative correlation was found between levels of heteroplasmy and age of the patients at the time of sampling for molecular analysis, age at the diagnosis of diabetes, and body mass index. After adjustment for age at sampling for molecular study and gender, the correlation between heteroplasmy levels and age at the diagnosis of diabetes was no more significant. The two other correlations remained significant. A significant positive correlation between levels of heteroplasmy and HbA1c was also found and remained significant after adjustment for age at molecular sampling and gender.
Conclusions: These results support the hypothesis that heteroplasmy levels are at least one of the determinants of the severity of the phenotype in MIDD.
Heteroplasmy levels are at least one of the determinants of the severity of the phenotype of maternally inherited diabetes and deafness
Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations
We derive constraints on the thermal and ionization states of the intergalactic medium (IGM) at redshift ≈ 9.1 using new upper
limits on the 21-cm power spectrum measured by the LOFAR radio telescope and a prior on the ionized fraction at that redshift
estimated from recent cosmic microwave background (CMB) observations. We have used results from the reionization simulation
code GRIZZLY and a Bayesian inference framework to constrain the parameters which describe the physical state of the IGM.
We find that, if the gas heating remains negligible, an IGM with ionized fraction 0.13 and a distribution of the ionized regions
with a characteristic size 8 h−1 comoving megaparsec (Mpc) and a full width at half-maximum (FWHM) 16 h−1 Mpc is
ruled out. For an IGM with a uniform spin temperature TS 3 K, no constraints on the ionized component can be computed. If
the large-scale fluctuations of the signal are driven by spin temperature fluctuations, an IGM with a volume fraction 0.34 of
heated regions with a temperature larger than CMB, average gas temperature 7–160 K, and a distribution of the heated regions
with characteristic size 3.5–70 h−1 Mpc and FWHM of 110 h−1 Mpc is ruled out. These constraints are within the 95 per cent
credible intervals. With more stringent future upper limits from LOFAR at multiple redshifts, the constraints will become tighter
and will exclude an increasingly large region of the parameter space
Clinical Characteristics and Diagnostic Criteria of Maturity-Onset Diabetes Of The Young (MODY) due to Molecular Anomalies of the HNF1A Gene
Context: The diagnosis of maturity-onset diabetes of the young type 3 (MODY3), associated with HNF1A molecular abnormalities, is often missed.Objective: The objective of the study was to describe the phenotypes of a large series of MODY3 patients and to reassess parameters that may improve its diagnosis. Design, Setting, and Patients: This retrospective multicenter study included 487 unrelated patients referred because of suspicion of MODY3. Genetic analysis identified 196 MODY3 and 283 non-MODY3 cases. Criteria associated with MODY3 were assessed by multivariate analysis. The capacity of the model to predict MODY3 diagnosis was assessed by the area under the receiver-operating characteristic curve and was further validated in an independent sample of 851 patients (165 MODY3 and 686 non-MODY3). Results: In the MODY3 patients, diabetes was revealed by clinical symptoms in 25% of the cases and was diagnosed by screening in the others. Age at diagnosis of diabetes was more than 25 yr in 40% of the MODY3 patients. There was considerable variability and overlap of all assessed parameters in MODY3 and non-MODY3 patients. The best predictive model was based on criteria available at diagnosis of diabetes, including age, body mass index, number of affected generations, presence of diabetes symptoms, and geographical origin. The area under the curve of the receiver-operating characteristic analysis was 0.81. When sensitivity was set to 90%, specificity was 49%. Conclusions: Differential diagnosis between MODY3 and early-onset type 2 diabetes remains difficult. Whether the proposed model will improve the pick-up rate of MODY3 diagnosis needs to be confirmed in independent populations
Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR
A new upper limit on the 21 cm signal power spectrum at a redshift of z ≈ 9.1 is presented, based on 141 h of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally smooth gain-calibration, Gaussian Process Regression (GPR) foreground mitigation and optimally weighted power spectrum inference. Previously seen ‘excess power’ due to spectral structure in the gain solutions has markedly reduced but some excess power still remains with a spectral correlation distinct from thermal noise. This excess has a spectral coherence scale of 0.25–0.45 MHz and is partially correlated between nights, especially in the foreground wedge region
Unexpected worsening of progressive multifocal leucoencephalopathy following COVID-19 pneumonia.
Progressive multifocal leucoencephalopathy is a serious side effect of natalizumab, a humanized monoclonal antibody approved for the treatment of multiple sclerosis. Here, we report a case of unexpected worsening of natalizumab-related progressive multifocal leucoencephalopathy following COVID-19. After natalizumab discontinuation, a slight neurological improvement was observed, but, two months later the patient was admitted to the hospital because of neurological deterioration and COVID-19 mild pneumonia. Except for SARS-CoV-2 infection, no other potential factors of neurological worsening were identified. Thus, we pose the hypothesis that SARS-CoV-2 was instrumental in the progressive multifocal leucoencephalopathy deterioration
The origin of the escape of Lyman
Context. Identifying the physical mechanisms driving the escape of Lyman continuum (LyC) photons is crucial for the search of Lyman continuum emitter (LCE) candidates.
Aims. To understand the physical properties involved in the leakage of LyC photons, we investigate the connection between the H