139 research outputs found
Low-Temperature Crystallization of Amorphous Silicate in Astrophysical Environments
We construct a theoretical model for low-temperature crystallization of
amorphous silicate grains induced by exothermic chemical reactions. As a first
step, the model is applied to the annealing experiments, in which the samples
are (1) amorphous silicate grains and (2) amorphous silicate grains covered
with an amorphous carbon layer. We derive the activation energies of
crystallization for amorphous silicate and amorphous carbon from the analysis
of the experiments. Furthermore, we apply the model to the experiment of
low-temperature crystallization of amorphous silicate core covered with an
amorphous carbon layer containing reactive molecules. We clarify the conditions
of low-temperature crystallization due to exothermic chemical reactions. Next,
we formulate the crystallization conditions so as to be applicable to
astrophysical environments. We show that the present crystallization mechanism
is characterized by two quantities: the stored energy density Q in a grain and
the duration of the chemical reactions \tau . The crystallization conditions
are given by Q > Q_{min} and \tau < \tau _{cool} regardless of details of the
reactions and grain structure, where \tau _{cool} is the cooling timescale of
the grains heated by exothermic reactions, and Q_{min} is minimum stored energy
density determined by the activation energy of crystallization. Our results
suggest that silicate crystallization occurs in wider astrophysical conditions
than hitherto considered.Comment: 9 figures, accepted for publication in Astrophysical
The Fab portion of immunoglobulin G contributes to its binding to Fcγ receptor III
Most cells active in the immune system express receptors for antibodies which mediate a variety of defensive mechanisms. These receptors interact with the Fc portion of the antibody and are therefore collectively called Fc receptors. Here, using high-speed atomic force microscopy, we observe interactions of human, humanized, and mouse/human-chimeric immunoglobulin G1 (IgG1) antibodies and their cognate Fc receptor, FcγRIIIa. Our results demonstrate that not only Fc but also Fab positively contributes to the interaction with the receptor. Furthermore, hydrogen/deuterium exchange mass spectrometric analysis reveals that the Fab portion of IgG1 is directly involved in its interaction with FcγRIIIa, in addition to the canonical Fc-mediated interaction. By targeting the previously unidentified receptor-interaction sites in IgG-Fab, our findings could inspire therapeutic antibody engineering
The Primary Aldosteronism Surgical Outcome Score for the Prediction of Clinical Outcomes After Adrenalectomy for Unilateral Primary Aldosteronism
MINI: Clinical remission after unilateral adrenalectomy to treat unilateral primary aldosteronism is achieved in less than half of patients. A linear discriminant model with 6 presurgical predictors of clinical remission was used to build a 25-point prediction score of postsurgical clinical outcomes. The prediction score was integrated into a user-friendly online tool which can be used in a clinical setting to differentiate patients who are likely to be clinically cured after surgery from those who will need continuous surveillance after surgery due to remnant hypertension. OBJECTIVE: To develop a prediction model for clinical outcomes after unilateral adrenalectomy for unilateral primary aldosteronism. SUMMARY BACKGROUND DATA: Unilateral primary aldosteronism is the most common surgically curable form of endocrine hypertension. Surgical resection of the dominant overactive adrenal in unilateral primary aldosteronism results in complete clinical success with resolution of hypertension without antihypertensive medication in less than half of patients with a wide between-center variability. METHODS: A linear discriminant analysis model was built using data of 380 patients treated by adrenalectomy for unilateral primary aldosteronism to classify postsurgical clinical outcomes. The total cohort was then randomly divided into training (280 patients) and test (100 patients) datasets to create and validate a score system to predict clinical outcomes. An online tool (Primary Aldosteronism Surgical Outcome predictor) was developed to facilitate the use of the predictive score. RESULTS: Six presurgical factors associated with complete clinical success (known duration of hypertension, sex, antihypertensive medication dosage, body mass index, target organ damage, and size of largest nodule at imaging) were selected based on classification performance in the linear discriminant analysis model. A 25-point predictive score was built with an optimal cut-off of greater than 16 points (accuracy of prediction = 79.2%; specificity = 84.4%; sensitivity = 71.3%) with an area under the curve of 0.839. CONCLUSIONS: The predictive score and the primary aldosteronism surgical outcome predictor can be used in a clinical setting to differentiate patients who are likely to be clinically cured after surgery from those who will need continuous surveillance after surgery due to persistent hypertension
The First Very Long Baseline Interferometry Image of 44 GHz Methanol Maser with the KVN and VERA Array (KaVA)
We have carried out the first very long baseline interferometry (VLBI)
imaging of 44 GHz class I methanol maser (7_{0}-6_{1}A^{+}) associated with a
millimeter core MM2 in a massive star-forming region IRAS 18151-1208 with KaVA
(KVN and VERA Array), which is a newly combined array of KVN (Korean VLBI
Network) and VERA (VLBI Exploration of Radio Astrometry). We have succeeded in
imaging compact maser features with a synthesized beam size of 2.7
milliarcseconds x 1.5 milliarcseconds (mas). These features are detected at a
limited number of baselines within the length of shorter than approximately 650
km corresponding to 100 Mlambda in the uv-coverage. The central velocity and
the velocity width of the 44 GHz methanol maser are consistent with those of
the quiescent gas rather than the outflow traced by the SiO thermal line. The
minimum component size among the maser features is ~ 5 mas x 2 mas, which
corresponds to the linear size of ~ 15 AU x 6 AU assuming a distance of 3 kpc.
The brightness temperatures of these features range from ~ 3.5 x 10^{8} to 1.0
x 10^{10} K, which are higher than estimated lower limit from a previous Very
Large Array observation with the highest spatial resolution of ~ 50 mas. The 44
GHz class I methanol maser in IRAS 18151-1208 is found to be associated with
the MM2 core, which is thought to be less evolved than another millimeter core
MM1 associated with the 6.7 GHz class II methanol maser.Comment: 19 pages, 3 figure
Computed Tomography and Adrenal Venous Sampling in the Diagnosis of Unilateral Primary Aldosteronism
Unilateral primary aldosteronism is the most common surgically correctable form of endocrine hypertension and is usually differentiated from bilateral forms by adrenal venous sampling (AVS) or computed tomography (CT). Our objective was to compare clinical and biochemical postsurgical outcomes of patients with unilateral primary aldosteronism diagnosed by CT or AVS and identify predictors of surgical outcomes. Patient data were obtained from 18 internationally distributed centers and retrospectively analyzed for clinical and biochemical outcomes of adrenalectomy of patients with surgical management based on CT (n=235 patients, diagnosed from 1994-2016) or AVS (526 patients, diagnosed from 1994-2015) using the standardized PASO (Primary Aldosteronism Surgical Outcome) criteria. Biochemical outcomes were highly different according to surgical management approach with a smaller proportion in the CT group achieving complete biochemical success (188 of 235 [80%] patients versus 491 of 526 [93%], P<0.001) and a greater proportion with absent biochemical success (29 of 235 [12%] versus 10 of 526 [2%], P<0.001). A diagnosis by CT was associated with a decreased likelihood of complete biochemical success compared with AVS (odds ratio, 0.28; 0.16-0.50; P<0.001). Clinical outcomes were not significantly different, but the absence of a postsurgical elevated aldosterone-to-renin ratio was a strong marker of complete clinical success (odds ratio, 14.81; 1.76-124.53; P=0.013) in the CT but not in the AVS group. In conclusion, patients diagnosed by CT have a decreased likelihood of achieving complete biochemical success compared with a diagnosis by AVS
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