3,685 research outputs found
Time domain add-drop multiplexing scheme enhanced using a saw-tooth pulse shaper
We experimentally demonstrate the use of saw-tooth optical pulses, which are shaped using a fiber Bragg grating, to achieve robust and high performance time-domain add-drop multiplexing in a scheme based on cross-phase (XPM) modulation in an optical fiber, with subsequent offset filtering. As compared to the use of more conventional pulse shapes, such as Gaussian pulses of a similar pulse width, the purpose-shaped saw-tooth pulses allow higher extinction ratios for the add and drop windows and significant improvements in the receiver sensitivity for the dropped and added channels
Generalized Quantile Treatment Effect: A Flexible Bayesian Approach Using Quantile Ratio Smoothing
We propose a new general approach for estimating the effect of a binary
treatment on a continuous and potentially highly skewed response variable, the
generalized quantile treatment effect (GQTE). The GQTE is defined as the
difference between a function of the quantiles under the two treatment
conditions. As such, it represents a generalization over the standard
approaches typically used for estimating a treatment effect (i.e., the average
treatment effect and the quantile treatment effect) because it allows the
comparison of any arbitrary characteristic of the outcome's distribution under
the two treatments. Following Dominici et al. (2005), we assume that a
pre-specified transformation of the two quantiles is modeled as a smooth
function of the percentiles. This assumption allows us to link the two quantile
functions and thus to borrow information from one distribution to the other.
The main theoretical contribution we provide is the analytical derivation of a
closed form expression for the likelihood of the model. Exploiting this result
we propose a novel Bayesian inferential methodology for the GQTE. We show some
finite sample properties of our approach through a simulation study which
confirms that in some cases it performs better than other nonparametric
methods. As an illustration we finally apply our methodology to the 1987
National Medicare Expenditure Survey data to estimate the difference in the
single hospitalization medical cost distributions between cases (i.e., subjects
affected by smoking attributable diseases) and controls.Comment: Published at http://dx.doi.org/10.1214/14-BA922 in the Bayesian
Analysis (http://projecteuclid.org/euclid.ba) by the International Society of
Bayesian Analysis (http://bayesian.org/
All-optical pulse reshaping and retiming systems incorporating pulse shaping fiber Bragg grating
This paper demonstrates two optical pulse retiming and reshaping systems incorporating superstructured fiber Bragg gratings (SSFBGs) as pulse shaping elements. A rectangular switching window is implemented to avoid conversion of the timing jitter on the original data pulses into pulse amplitude noise at the output of a nonlinear optical switch. In a first configuration, the rectangular pulse generator is used at the (low power) data input to a nonlinear optical loop mirror (NOLM) to perform retiming of an incident noisy data signal using a clean local clock signal to control the switch. In a second configuration, the authors further amplify the data signal and use it to switch a (low power) clean local clock signal. The S-shaped nonlinear characteristic of the NOLM results in this instance in a reduction of both timing and amplitude jitter on the data signal. The underlying technologies required for the implementation of this technique are such that an upgrade of the scheme for the regeneration of ultrahigh bit rate signals at data rates in excess of 320 Gb/s should be achievable
Novel Fiber Design for Wideband Conversion and Amplification in Multimode Fibers
We propose an operating principle to achieve broadband and highly tunable
mode conversion and amplification exploiting inter-modal four wave mixing in a
multimode fiber. A bandwidth of 30 nanometers is demonstrated by properly
designing a simple step-index silica fiber.Comment: Ecoc conference 201
Uncertainty and the Value of Diagnostic Information With Application to Axillary Lymph Node Dissection in Breast Cancer
In clinical decision making, it is common to ask whether, and how much, a diagnostic procedure is contributing to subsequent treatment decisions. Statistically, quantification of the value of the information provided by a diagnostic procedure can be carried out using decision trees with multiple decision points, representing both the diagnostic test and the subsequent treatments that may depend on the test\u27s results. This article investigates probabilistic sensitivity analysis approaches for exploring and communicating parameter uncertainty in such decision trees. Complexities arise because uncertainty about a model\u27s inputs determines uncertainty about optimal decisions at all decision nodes of a tree. We present the expected utility solution strategy for multistage decision problems in the presence of uncertainty on input parameters, propose a set of graphical displays and summarization tools for probabilistic sensitivity analysis in multistage decision trees, and provide an application to axillary lymph node dissection in breast cancer
- …