439 research outputs found
On the Power Spectrum Density of Gamma Ray Bursts
Gamma ray bursts (GRBs) are known to have short-time variability and
power-law behavior with the index -1.67 in the power spectrum density.
Reanalyzing the expanded data, we have found a) the power-law comes from the
global profile of the burst and not from the self-similar shots nor rapid
fluctuations in the luminosity profile. b) The power indices vary from burst to
burst and the value -1.67 is given simply as the mean value of the
distribution; there is no systematic correlation among GRBs to yield the power
law.Comment: 10 pages, 4 figures, submitted to ApJ Letter
Fundamental precision limit of a Mach-Zehnder interferometric sensor when one of the inputs is the vacuum
In the lore of quantum metrology, one often hears (or reads) the following
no-go theorem: If you put vacuum into one input port of a balanced Mach-Zehnder
Interferometer, then no matter what you put into the other input port, and no
matter what your detection scheme, the sensitivity can never be better than the
shot noise limit (SNL). Often the proof of this theorem is cited to be in Ref.
[C. Caves, Phys. Rev. D 23, 1693 (1981)], but upon further inspection, no such
claim is made there. A quantum-Fisher-information-based argument suggestive of
this no-go theorem appears in Ref. [M. Lang and C. Caves, Phys. Rev. Lett. 111,
173601 (2013)], but is not stated in its full generality. Here we thoroughly
explore this no-go theorem and give the rigorous statement: the no-go theorem
holds whenever the unknown phase shift is split between both arms of the
interferometer, but remarkably does not hold when only one arm has the unknown
phase shift. In the latter scenario, we provide an explicit measurement
strategy that beats the SNL. We also point out that these two scenarios are
physically different and correspond to different types of sensing applications.Comment: 9 pages, 2 figure
Is ChatGPT the Future of Causal Text Mining? A Comprehensive Evaluation and Analysis
Causality is fundamental in human cognition and has drawn attention in
diverse research fields. With growing volumes of textual data, discerning
causalities within text data is crucial, and causal text mining plays a pivotal
role in extracting meaningful patterns. This study conducts comprehensive
evaluations of ChatGPT's causal text mining capabilities. Firstly, we introduce
a benchmark that extends beyond general English datasets, including
domain-specific and non-English datasets. We also provide an evaluation
framework to ensure fair comparisons between ChatGPT and previous approaches.
Finally, our analysis outlines the limitations and future challenges in
employing ChatGPT for causal text mining. Specifically, our analysis reveals
that ChatGPT serves as a good starting point for various datasets. However,
when equipped with a sufficient amount of training data, previous models still
surpass ChatGPT's performance. Additionally, ChatGPT suffers from the tendency
to falsely recognize non-causal sequences as causal sequences. These issues
become even more pronounced with advanced versions of the model, such as GPT-4.
In addition, we highlight the constraints of ChatGPT in handling complex
causality types, including both intra/inter-sentential and implicit causality.
The model also faces challenges with effectively leveraging in-context learning
and domain adaptation. We release our code to support further research and
development in this field
A case of lung abscess successfully treated by transbronchial drainage using a guide sheath
A 51-year-old man was diagnosed with colon cancer in September 2011, and a solitary pulmonary nodule was detected by computed tomography (CT) scan. We performed a transbronchial biopsy with endobronchial ultrasonography using a guide sheath (GS) and diagnosed lung metastasis of colon cancer. The patient experienced remittent fever after the biopsy in spite of intravenous antibiotic therapies. Moreover, his CT scan showed a large lung abscess at the biopsy site. We performed transbronchial drainage using a GS as salvage therapy. The bloody pus was successfully aspirated, and chest X-ray following the procedure showed dramatic shrinkage of the abscess
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