581 research outputs found
PAGaN I: Multi-Frequency Polarimetry of AGN Jets with KVN
Active Galactic Nuclei (AGN) with bright radio jets offer the opportunity to
study the structure of and physical conditions in relativistic outflows. For
such studies, multi-frequency polarimetric very long baseline interferometric
(VLBI) observations are important as they directly probe particle densities,
magnetic field geometries, and several other parameters. We present results
from first-epoch data obtained by the Korean VLBI Network (KVN) within the
frame of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We
observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129
GHz in dual polarization mode. Our observations constrain apparent brightness
temperatures of jet components and radio cores in our sample to K
and K, respectively. Degrees of linear polarization are
relatively low overall: less than 10%. This indicates suppression of
polarization by strong turbulence in the jets. We found an exceptionally high
degree of polarization in a jet component of BL Lac at 43 GHz, with 40%. Assuming a transverse shock front propagating downstream along the
jet, the shock front being almost parallel to the line of sight can explain the
high degree of polarization.Comment: 14 pages, 17 figures, 4 tables. To appear in JKAS (received 2015 July
27; accepted 2015 October 25). Note the PAGaN II companion paper by J. Oh et
a
PAGaN II: The Evolution of AGN Jets on Sub-Parsec Scales
We report first results from KVN and VERA Array (KaVA) VLBI observations
obtained in the frame of our Plasma-physics of Active Galactic Nuclei (PAGaN)
project. We observed eight selected AGN at 22 and 43 GHz in single polarization
(LCP) between March 2014 and April 2015. Each source was observed for 6 to 8
hours per observing run to maximize the coverage. We obtained a total of
15 deep high-resolution images permitting the identification of individual
circular Gaussian jet components and three spectral index maps of BL Lac, 3C
111 and 3C 345 from simultaneous dual-frequency observations. The spectral
index maps show trends in agreement with general expectations -- flat core and
steep jets -- while the actual value of the spectral index for jets shows
indications for a dependence on AGN type. We analyzed the kinematics of jet
components of BL Lac and 3C 111, detecting superluminal proper motions with
maximum apparent speeds of about . This constrains the lower limits of the
intrinsic component velocities to and the upper limits of the angle
between jet and line of sight to 20. In agreement with global jet
expansion, jet components show systematically larger diameters at larger
core distances , following the global relation , albeit within
substantial scatter.Comment: 13 pages, 15 figures, 4 tables. To appear in JKAS (received 2015
August 31; accepted 2015 October 15). Note the PAGaN I companion paper by
J.-Y. Kim et a
Effect of Octreotide Injection on Postoperative Drainage After Neck Dissection: A Preliminary Report of a Prospective, Matched Case-Control Study
Objectives Somatostatin inhibits lymph production and reduces lymph flow into the lymphatic duct. We hypothesized that octreotide, a long-acting somatostatin analog, would reduce drainage after neck dissection (ND) by reducing the overall lymphatic flow in the neck as well as thoracic duct flow. Methods From 2012 to 2014, total 123 patients who had undergone left-sided comprehensive ND, were divided into an octreotide group (49 patients) and a control group (74 patients). Seventeen patients from the octreotide group and 17 from the control group were individually matched by age (±10 years), sex, body mass index (±1 kg/m2), type of cancer, surgeon, and the extent of surgery. These 34 patients were finally included in the study. Results The total fluid drainage volume (540.9 mL vs. 707.9 mL) and drainage volume during the period of octreotide use (the first 5 postoperative days) (461.1 mL vs. 676.4 mL) were significantly lower in the octreotide group. The duration of drain placement (6.3 days vs. 9.4 days) was also shorter in the octreotide group. In the octreotide group, the mean triglyceride concentration in the drainage fluid was significantly lower than that in the control group (43.1 mg/dL vs. 88.8 mg/dL). There was no complication associated with the use of octreotide. Conclusion Our study has shown that postoperative octreotide injections reduce postoperative drainage and the duration of drain placement. Further studies with larger patient populations are warranted to confirm these results and to evaluate the clinical benefits for patients
Conformal Language Modeling
We propose a novel approach to conformal prediction for generative language
models (LMs). Standard conformal prediction produces prediction sets -- in
place of single predictions -- that have rigorous, statistical performance
guarantees. LM responses are typically sampled from the model's predicted
distribution over the large, combinatorial output space of natural language.
Translating this process to conformal prediction, we calibrate a stopping rule
for sampling different outputs from the LM that get added to a growing set of
candidates until we are confident that the output set is sufficient. Since some
samples may be low-quality, we also simultaneously calibrate and apply a
rejection rule for removing candidates from the output set to reduce noise.
Similar to conformal prediction, we prove that the sampled set returned by our
procedure contains at least one acceptable answer with high probability, while
still being empirically precise (i.e., small) on average. Furthermore, within
this set of candidate responses, we show that we can also accurately identify
subsets of individual components -- such as phrases or sentences -- that are
each independently correct (e.g., that are not "hallucinations"), again with
statistical guarantees. We demonstrate the promise of our approach on multiple
tasks in open-domain question answering, text summarization, and radiology
report generation using different LM variants
Preoperative Subclinical Hyperthyroidism in Patients With Papillary Thyroid Carcinoma
ObjectivesNumerous studies have reported the effects of subclinical hyperthyroidism on the cardiovascular system, osteoporosis, and metabolic syndrome. However, there are few studies examining the relationships between subclinical hyperthyroidism and thyroid cancer. The aim of this study was to investigate the relationships between preoperative subclinical hyperthyroidism and clinicopathological characteristics in patients with papillary thyroid carcinoma (PTC) in terms of thyroid-stimulating hormone (TSH) levels and TSH receptor antibody (TRAb) values.MethodsBetween January 2001 and December 2007, 462 patients were eligible for analysis in our study; we compared the clinicopathological characteristics of 39 preoperative subclinical hyperthyroidism patients with those of 423 euthyroid patients.ResultsThere were no statistical differences between the 2 groups with respect to age, male to female ratio, primary tumor size, extrathyroidal extension (ETE), multifocality, lymph node metastasis, TNM and AMES stages, recurrence, and survival, despite significant difference in TSH concentrations between the 2 groups. In the evaluation for TRAb, primary tumor size was significantly larger in patients with normal TRAb than in patients with elevated TRAb. When the patients were subdivided into 4 categories according to TRAb values (15.0%), tumor size and ETE were significantly different. However, we could not find linear relationships in the increase or decrease of TRAb values.ConclusionThe results of our study suggest that subclinical hyperthyroidism is not independently associated with tumor aggressiveness and prognosis in PTC in spite of reduced TSH levels and increased TRAb values as compared with euthyroid patients
First results from the HAYSTAC axion search
The axion is a well-motivated cold dark matter (CDM) candidate first
postulated to explain the absence of violation in the strong interactions.
CDM axions may be detected via their resonant conversion into photons in a
"haloscope" detector: a tunable high- microwave cavity maintained at
cryogenic temperature, immersed a strong magnetic field, and coupled to a
low-noise receiver.
This dissertation reports on the design, commissioning, and first operation
of the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC), a new detector
designed to search for CDM axions with masses above . I
also describe the analysis procedure developed to derive limits on axion CDM
from the first HAYSTAC data run, which excluded axion models with two-photon
coupling , a
factor of 2.3 above the benchmark KSVZ model, over the mass range .
This result represents two important achievements. First, it demonstrates
cosmologically relevant sensitivity an order of magnitude higher in mass than
any existing direct limits. Second, by incorporating a dilution refrigerator
and Josephson parametric amplifier, HAYSTAC has demonstrated total noise
approaching the standard quantum limit for the first time in a haloscope axion
search.Comment: Ph.D. thesis. 346 pages, 58 figures. A few typos corrected relative
to the version submitted to ProQues
Early Response Assessment after Intraarterial Therapy Using 3D Quantitative Tumor Enhancement Analysis
PURPOSE Liver metastases from renal cell carcinoma (RCC) are not uncommon in
the course of disease. However, data about tumor response to intraarterial
therapy (IAT) are scarce. This study assessed whether changes of enhancing
tumor volume using quantitative European Association for the Study of the
Liver (qEASL) on magnetic resonance imaging (MRI) and computed tomography (CT)
can evaluate tumor response and predict overall survival (OS) early after
therapy. METHODS AND MATERIALS Fourteen patients with liver metastatic RCC
treated with IAT (transarterial chemoembolization: n= 9 and yttrium-90: n= 5)
were retrospectively included. All patients underwent contrast-enhanced
imaging (MRI: n= 10 and CT: n= 4) 3 to 4 weeks pre- and posttreatment.
Response to treatment was evaluated on the arterial phase using Response
Evaluation Criteria in Solid Tumors (RECIST), World Health Organization,
modified RECIST, EASL, tumor volume, and qEASL. Paired t test was used to
compare measurements pre- and post-IAT. Patients were stratified into
responders (≥65% decrease in qEASL) and nonresponders (<65% decrease in
qEASL). OS was evaluated using Kaplan-Meier curves with log-rank test and the
Cox proportional hazard model. RESULTS Mean qEASL (cm3) decreased from 93.5 to
67.2 cm3 (P= .004) and mean qEASL (%) from 63.1% to 35.6% (P= .001). No
significant changes were observed using other response criteria. qEASL was the
only significant predictor of OS when used to stratify patients into
responders and nonresponders with median OS of 31.9 versus 11.1 months (hazard
ratio [HR], 0.43; 95% confidence interval [CI], 0.19-0.97; P= .042) for qEASL
(cm3) and 29.9 versus 10.2 months (HR, 0.09; 95% CI, 0.01-0.74; P= .025) for
qEASL (%). CONCLUSION Three-dimensional (3D) quantitative tumor analysis is a
reliable predictor of OS when assessing treatment response after IAT in
patients with RCC metastatic to the liver. qEASL outperforms conventional non-
3D methods and can be used as a surrogate marker for OS early after therapy
Renal Cell Carcinoma Metastatic to the Liver: Early Response Assessment after Intraarterial Therapy Using 3D Quantitative Tumor Enhancement Analysis
AbstractPURPOSELiver metastases from renal cell carcinoma (RCC) are not uncommon in the course of disease. However, data about tumor response to intraarterial therapy (IAT) are scarce. This study assessed whether changes of enhancing tumor volume using quantitative European Association for the Study of the Liver (qEASL) on magnetic resonance imaging (MRI) and computed tomography (CT) can evaluate tumor response and predict overall survival (OS) early after therapy.METHODS AND MATERIALSFourteen patients with liver metastatic RCC treated with IAT (transarterial chemoembolization: n= 9 and yttrium-90: n= 5) were retrospectively included. All patients underwent contrast-enhanced imaging (MRI: n= 10 and CT: n= 4) 3 to 4 weeks pre- and posttreatment. Response to treatment was evaluated on the arterial phase using Response Evaluation Criteria in Solid Tumors (RECIST), World Health Organization, modified RECIST, EASL, tumor volume, and qEASL. Paired t test was used to compare measurements pre- and post-IAT. Patients were stratified into responders (≥65% decrease in qEASL) and nonresponders (<65% decrease in qEASL). OS was evaluated using Kaplan-Meier curves with log-rank test and the Cox proportional hazard model.RESULTSMean qEASL (cm3) decreased from 93.5 to 67.2 cm3 (P= .004) and mean qEASL (%) from 63.1% to 35.6% (P= .001). No significant changes were observed using other response criteria. qEASL was the only significant predictor of OS when used to stratify patients into responders and nonresponders with median OS of 31.9 versus 11.1 months (hazard ratio [HR], 0.43; 95% confidence interval [CI], 0.19-0.97; P= .042) for qEASL (cm3) and 29.9 versus 10.2 months (HR, 0.09; 95% CI, 0.01-0.74; P= .025) for qEASL (%).CONCLUSIONThree-dimensional (3D) quantitative tumor analysis is a reliable predictor of OS when assessing treatment response after IAT in patients with RCC metastatic to the liver. qEASL outperforms conventional non-3D methods and can be used as a surrogate marker for OS early after therapy
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