The SYMPLICITY HTN-3 randomized, blinded, sham-controlled trial confirmed the safety of renal denervation (RDN), but did not meet its primary efficacy endpoint. Prior RDN studies have demonstrated ...significant and durable reductions in blood pressure. This analysis investigated factors that may help explain these disparate results.
Patients with resistant hypertension were randomized 2 : 1 to RDN (n = 364) or sham (n = 171). The primary endpoint was the difference in office systolic blood pressure (SBP) change at 6 months. A multivariable analysis identified predictors of SBP change. Additional analyses examined the influence of medication changes, results in selected subgroups and procedural factors. Between randomization and the 6-month endpoint, 39% of patients underwent medication changes. Predictors of office SBP reduction at 6 months were baseline office SBP ≥ 180 mmHg, aldosterone antagonist use, and non-use of vasodilators; number of ablations was a predictor in the RDN group. Non-African-American patients receiving RDN had a significantly greater change in office SBP than those receiving sham; -15.2 ± 23.5 vs. -8.6 ± 24.8 mmHg, respectively (P = 0.012). Greater reductions in office and ambulatory SBP, and heart rate were observed with a higher number of ablations and energy delivery in a four-quadrant pattern.
Post hoc analyses, although derived from limited patient cohorts, reveal several potential confounding factors that may partially explain the unexpected blood pressure responses in both the sham control and RDN groups. These hypothesis-generating data further inform the design of subsequent research to evaluate the potential role of RDN in the treatment of resistant hypertension. CLINICALTRIALS.GOV IDENTIFIER: NCT01418261.
Context.
The interaction between dust, ice, and gas during the formation of stars produces complex organic molecules. While observations indicate that several species are formed on ice-covered dust ...grains and are released into the gas phase, the exact chemical interplay between solid and gas phases and their relative importance remain unclear.
Aims.
Our goal is to study the interplay between dust, ice, and gas in regions of low-mass star formation through ice- and gas-mapping and by directly measuring gas-to-ice ratios. This provides constraints on the routes that lead to the chemical complexity that is observed in solid and gas phases.
Methods.
We present observations of gas-phase methanol (CH
3
OH) and carbon monoxide (
13
CO and C
18
O) at 1.3 mm towards ten low-mass young protostars in the Serpens SVS 4 cluster from the SubMillimeter Array (SMA) and the Atacama Pathfinder EXperiment (APEX) telescope. We used archival data from the Very Large Telescope (VLT) to derive abundances of ice H
2
O, CO, and CH
3
OH towards the same region. Finally, we constructed gas-ice maps of SVS 4 and directly measured CO and CH
3
OH gas-to-ice ratios.
Results.
The SVS 4 cluster is characterised by a global temperature of 15 ± 5 K. At this temperature, the chemical behaviours of CH
3
OH and CO are anti-correlated: larger variations are observed for CH
3
OH gas than for CH
3
OH ice, whereas the opposite is seen for CO. The gas-to-ice ratios (
N
gas
/
N
ice
) range from 1–6 for CO and 1.4 × 10
−4
–3.7 × 10
−3
for CH
3
OH. The CO gas-maps trace an extended gaseous component that is not sensitive to the effect of freeze-out. Because of temperature variations and dust heating around 20 K, the frozen CO is efficiently desorbed. The CH
3
OH gas-maps, in contrast, probe regions where methanol is predominantly formed and present in ices and is released into the gas phase through non-thermal desorption mechanisms.
Conclusions.
Combining gas- and ice-mapping techniques, we measure gas-to-ice ratios of CO and CH
3
OH in the SVS 4 cluster. The CH
3
OH gas-to-ice ratio agrees with values that were previously reported for embedded Class 0/I low-mass protostars. We find that there is no straightforward correlation between CO and CH
3
OH gas with their ice counterparts in the cluster. This is likely related to the complex morphology of SVS 4: the Class 0 protostar SMM 4 and its envelope lie in the vicinity, and the outflow associated with SMM 4 intersects the cluster. This study serves as a pathfinder for future observations with ALMA and the
James Webb
Space Telescope (JWST) that will provide high-sensitivity gas-ice maps of molecules more complex than methanol. Such comparative maps will be essential to constrain the chemical routes that regulate the chemical complexity in star-forming regions.
Summary
Achalasia of the cardia is associated with an increased risk of esophageal carcinoma. The real burden of achalasia at the malignancy genesis is still a controversial issue. Therefore, there ...are no generally accepted recommendations on follow-up evaluation for achalasia patients. This study aims to estimate the risk of esophageal adenocarcinoma and squamous cell carcinoma in achalasia patients. We searched for association between carcinoma and esophageal achalasia in databases up to January 2017 to perform a systematic review and meta-analysis. A total of 1,046 studies were identified from search strategy, of which 40 were selected for meta-analysis. A cumulative number of 11,978 esophageal achalasia patients were evaluated. The incidence of squamous cell carcinoma was 312.4 (StDev 429.16) cases per 100,000 patient-years at risk. The incidence of adenocarcinoma was 21.23 (StDev 31.6) cases per 100,000 patient-years at risk. The prevalence for esophageal carcinoma was 28 carcinoma cases in 1,000 esophageal achalasia patients (CI 95% 2, 39). The prevalence for squamous cell carcinoma was 26 cases in 1,000 achalasia patients (CI 95% 18, 39) and for adenocarcinoma was 4 cases in 1,000 achalasia patients (CI 95% 3, 6).The absolute risk increase for squamous cell carcinoma was 308.1 and for adenocarcinoma was 18.03 cases per 100,000 patients per year. To the best of our knowledge, this is the first meta-analysis estimating the burden of achalasia as an esophageal cancer risk factor. The high increased risk rate for cancer in achalasia patients points to a strict endoscopic surveillance for these patients. Also, the increased risk for developing adenocarcinoma in achalasia patients suggests fundoplication after myotomy, to avoid esophageal reflux and Barret esophagus, a known risk factor for adenocarcinoma.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This work presents a physicochemical study of frozen amorphous methane (at 16 K) under bombardment by medium-mass ions (15.7 MeV
16
O
5+
) with implications for icy bodies in the outer Solar System ...exposed to the action of cosmic rays and energetic particles. The experiment was performed at the Grand Accélérateur National d'Ions Lourds (GANIL) located in Caen, France. The results demonstrate that irradiation of CH
4
-containing ices by swift medium mass ions with delivered energy covering both stopping power regimes until its implantation on ice (
i.e.
electronic and nuclear) leads to the production of many hydrocarbons, such as C
2
H
2
, C
2
H
4
, C
2
H
6
, and C
3
H
8
(the most abundant daughter species produced). Values for the effective dissociation cross section of CH
4
and the average value for the effective formation cross-sections of its daughter species were about 10
−14
cm
2
and 10
−15
cm
2
, respectively. The half-life of methane ice in the presence of swift medium mass ions extrapolated to some outer Solar System environments is estimated to be around 10
6
years. The measured sputtering yield of methane due to incoming swift ions was about 7.30 × 10
5
molecules per impact. Such parameters can be used as models to estimate the amount of CH
4
and other molecular species desorbed from the icy surfaces that are constantly being incorporated to the gaseous atmosphere in the vicinity of these outer Solar System bodies due to the presence of energetic particles and cosmic rays.
We reported results for ion irradiation of CH
4
ice with implications for abundance of molecular species in icy objects in the outer Solar System.
Abstract
We present an analysis of multiwavelength observations of the dark globule DC 314.8–5.1, using data from the Gaia optical, Two Micron All Star Survey near-infrared, and Wide-field Infrared ...Survey Explorer mid-infrared surveys, dedicated imaging with the Spitzer Space Telescope, and X-ray data obtained with the Swift X-Ray Telescope (XRT). The main goal was to identify possible pre-main-sequence stars (PMSs) and young stellar objects (YSOs) associated with the globule. For this, we studied the infrared colors of all point sources within the boundaries of the cloud. After removing sources with nonstellar spectra, we investigated the Gaia parallaxes for the YSO candidates and found that none are physically related to DC 314.8–5.1. In addition, we searched for X-ray emission from PMSs with Swift-XRT, and found no 0.5–10 keV emission down to a luminosity level ≲10
31
erg s
−1
, typical of a PMS with mass ≥2
M
⊙
. Our detailed inspection therefore supports a very young, “prestellar core” evolutionary stage for the cloud. Based on archival Planck and IRAS data, we moreover identify the presence of hot dust, with temperatures ≳100 K, in addition to the dominant dust component at 14 K, originating with the associated reflection nebula.
The physical evolution of young stellar objects (YSOs) is accompanied by an enrichment of the molecular complexity, mainly triggered by the heating and energetic processing of astrophysical ices. In ...this paper, a study of how the ice column density varies across the protostellar evolution has been performed. Tabulated data of H2O, CO2, CH3OH, and HCOOH observed by ground- and space-based telescopes toward 27 early-stage YSOs were taken from the literature. The observational data show that ice column density and spectral index ( ), used to classify the evolutionary stage, are well correlated. A 2D continuum radiative transfer simulation containing bare and ice-covered grains at different levels of cosmic-ray processing were used to calculate the spectral energy distributions in different angle inclinations between face-on and edge-on configurations. The H2O:CO2 ice mixture was used to address the H2O and CO2 column density variation, whereas CH3OH and HCOOH are by-products of the virgin ice after energetic processing. The simulated spectra were used to calculate the ice column densities of YSOs in an evolutionary sequence. As a result, the models show that the ice column density variation of HCOOH with can be justified by envelope dissipation and energetic processing of ice. On the other hand, the ice column densities are mostly overestimated in the cases of H2O, CO2 and CH3OH, even though the physical and cosmic-ray processing effects are taken into account.
Soft X-rays are an important agent for chemical processing in the Solar System and in the interstellar medium. The photolysis and photodesorption processes of H
2
O-rich ices triggered by soft X-rays ...was, experimentally, addressed in this paper. The experiments were performed at the Brazilian synchrotron facility LNLS/CNPEN employing broadband radiation (from 6 to 2000 eV; mainly soft X-rays and a small fraction of VUV) in solid samples at temperatures of 20 and 80 K. The icy samples were monitored by infrared spectroscopy. We determined the effective destruction cross section (in the order 10
−18
cm
2
) as well as the formation cross section for the new species produced after the irradiation. Among them, we list OCN
−
, CO, CO
3
, CH
3
OH, H
2
O
2
, HCOO
−
, NH
4
+
, HCONH
2
and CH
3
HCO, mostly formed in the experiment at 80 K. The chemical equilibrium stage was characterized and molecular abundances were quantified. In addition, we discuss a methodology to estimate the amount of unknown species in the ice produced by photolysis. The samples reach chemical equilibrium at fluences around 2-3 × 10
18
cm
−2
. Timescales for reaching chemical equilibrium in space environments illuminated by X-rays were given, as well as the desorption yields induced by X-rays. The astrophysical implication on the surface chemistry and desorption processes at the moon Enceladus are provided.
Soft X-rays are an important agent for chemical processing in the Solar System and in the interstellar medium.
ABSTRACT
The survival of astrophysical ices in star-forming regions depends on the suitability of temperature, density and radiation conditions. In this article, the role of the interstellar ...radiation field (ISRF) on ices in Elias 29 is addressed. This object is the most luminous protostar in the ρ Oph E molecular cloud and is surrounded by many young stellar objects only a few arcmin distant. In addition, two other bright BV stars (S1 and HD 147889) enhance the external irradiation in Elias 29. This study was carried out using the Monte Carlo radiative transfer code radmc-3d assuming internal and external irradiation. As result, we found that HD 147889 dominates the ISRF, rather than the closest protostars, and contributes to enhancing the external irradiation by 44 times the standard value. Furthermore, remarkable effects are observed in the far-infrared (FIR) spectrum, as well as in the near-infrared (near-IR) image. Additionally, the snowline positions of volatile compounds, such as CO, O2, N2 and CH4, are redefined to a toroidal-shaped morphology in the envelope, with low far-ultraviolet (FUV) flux (10−7erg cm−2 s−1). In such a scenario, the formation of complex molecules as the result of hydrogenation or oxygenation of volatile species is expected to be severely affected.
Context.
Interstellar and circumstellar ices are largely composed of frozen water. Therefore, it is important to derive fundamental parameters for H
2
O ice such as absorption and scattering ...opacities, for which accurate complex refractive indexes are needed.
Aims.
The primary goal of the work presented here is to derive ice-grain opacities based on accurate H
2
O ice complex refractive indexes at low temperatures and to assess the impact this has on the derivation of water ice column densities and porosity in space.
Methods.
We used the
optool
code to derive ice-grain scattering and absorption opacity values based on new and previously reported mid-infrared (mid-IR) complex refractive index measurements of H
2
O ice, primarily in its amorphous form, but not exclusively. Next, we used those opacities in the
RADMC-3D
code to run a radiative transfer simulation of a protostellar envelope containing H
2
O ice, which was then used to calculate water ice column densities.
Results.
We found that the real refractive index in the mid-IR of H
2
O ice at 30 K is ~14% lower than previously reported in the literature. This has a direct impact on the ice column densities derived from the simulations of embedded protostars. Additionally, we found that ice porosity plays a significant role in the opacity of icy grains and that the H
2
O libration mode can be used as a diagnostic tool to constrain the porosity level. Finally, the refractive indexes presented here allowed us to estimate a grain size detection limit of 18 μm based on the 3 μm band, whereas the 6 μm band allowed us to trace grain sizes larger than 20 μm.
Conclusions.
Based on radiative transfer simulations using new mid-IR refractive indexes, we conclude that H
2
O ice leads to more absorption of infrared light than previously estimated. This implies that the 3 and 6 μm bands remain detectable in icy grains with sizes larger than 10 μm. Finally, we also propose that the H
2
O ice libration band can be used as a diagnostic tool to constrain the porosity level of the interstellar ice, in addition to the OH dangling bond, which is now routinely used for this purpose.
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