283 research outputs found
Free-Flight Experiments in LISA Pathfinder
The LISA Pathfinder mission will demonstrate the technology of drag-free test masses for use as inertial references in future space-based gravitational wave detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free flight about a test mass while measuring the acceleration of this primary test mass relative to a second reference test mass. Because the reference test mass is contained within the same spacecraft, it is necessary to apply forces on it to maintain its position and attitude relative to the spacecraft. These forces are a potential source of acceleration noise in the LISA Pathfinder system that are not present in the full LISA configuration. While LISA Pathfinder has been designed to meet it's primary mission requirements in the presence of this noise, recent estimates suggest that the on-orbit performance may be limited by this 'suspension noise'. The drift-mode or free-flight experiments provide an opportunity to mitigate this noise source and further characterize the underlying disturbances that are of interest to the designers of LISA-like instruments. This article provides a high-level overview of these experiments and the methods under development to analyze the resulting data
Effects of Expert Testimony and Interrogation Tactics on Perceptions of Confessions
Evidence obtained through the process of interrogation is frequently undermined by what can be perceived as overzealous interrogation tactics. Although the majority of psychologically oriented tactics are legally permissible, they nonetheless contribute to innocent suspects confessing to crimes they did not commit. The present study examined the effect of expert testimony and interrogation tactics on perceptions of a confession. 182 undergraduates read a transcript of a homicide trial that varied based on interrogation tactic: implicit threat of punishment (maximization) or leniency (minimization) and expert witness testimony (presence or absence of expert testimony). Analysis indicated that the type of interrogation tactic used in obtaining the confession affected participants\u27 perceptions of the coerciveness of the interrogation process
In-flight validation of Metis Visible-light Polarimeter Coronagraph on board Solar Orbiter
Context. The Metis coronagraph is one of the remote-sensing instruments of
the ESA/NASA Solar Orbiter mission. Metis is aimed at the study of the solar
atmosphere and solar wind by simultaneously acquiring images of the solar
corona at two different wavelengths; visible-light (VL) within a band ranging
from 580 nm to 640 nm, and in the HI Ly-alpha 121.6 +/- 10 nm ultraviolet (UV)
light. The visible-light channel includes a polarimeter with electro-optically
modulating Liquid Crystal Variable Retarders (LCVRs) to measure the linearly
polarized brightness of the K-corona to derive the electron density.
Aims. In this paper, we present the first in-flight validation results of the
Metis polarimetric channel together with a comparison to the on-ground
calibrations. It is the validation of the first use in deep space (with hard
radiation environment) of an electro-optical device: a liquid crystal-based
polarimeter.
Methods. We used the orientation of the K-corona's linear polarization vector
during the spacecraft roll maneuvers for the in-flight calibration.
Results. The first in-flight validation of the Metis coronagraph on-board
Solar Orbiter shows a good agreement with the on-ground measurements. It
confirms the expected visible-light channel polarimetric performance. A final
comparison between the first pB obtained by Metis with the polarized brightness
(pB) obtained by the space-based coronagraph LASCO and the ground-based
coronagraph KCor shows the consistency of the Metis calibrated results.Comment: 8 pages, 13 figures, 3 tables, pape
State space modelling and data analysis exercises in LISA Pathfinder
LISA Pathfinder is a mission planned by the European Space Agency to test the
key technologies that will allow the detection of gravitational waves in space.
The instrument on-board, the LISA Technology package, will undergo an
exhaustive campaign of calibrations and noise characterisation campaigns in
order to fully describe the noise model. Data analysis plays an important role
in the mission and for that reason the data analysis team has been developing a
toolbox which contains all the functionalities required during operations. In
this contribution we give an overview of recent activities, focusing on the
improvements in the modelling of the instrument and in the data analysis
campaigns performed both with real and simulated data.Comment: Plenary talk presented at the 9th International LISA Symposium, 21-25
May 2012, Pari
Exploring the role of respiratory microbiome in lung cancer: A systematic review
Giving the potential contribute in cancer initiation and progression, lung microbiota represents a promising topic in cancer research, although still unexplored. We performed a systematic literature search to identify clinical studies evaluating lung microbiota composition, its correlation with lung cancer patients’ clinico-pathological features and prognosis. Of the identified 370 studies, 21 were eligible and included. Although studies were heterogeneous, lung cancer resulted to be enriched in peculiar microbial communities, with differences in composition and diversity according to clinico-pathological parameters. Few studies explored how lung microbiota influences cancer outcome. In light of these findings and borrowing the suggestions coming from gut microbiota, we speculate that respiratory microbiome may influence pathogenesis, progression and outcome of lung cancer. Taking advantage of the experience of chronical lung diseases, prospective studies should be designed to evaluate lung microbiota changes throughout any phase of lung cancer course, particularly with the advent of immunotherapy as pivotal treatment
Beyond the required LISA free-fall performance: new LISA pathfinder results down to 20  μHz
In the months since the publication of the first results, the noise performance of LISA Pathfinder has improved because of reduced Brownian noise due to the continued decrease in pressure around the test masses, from a better correction of noninertial effects, and from a better calibration of the electrostatic force actuation. In addition, the availability of numerous long noise measurement runs, during which no perturbation is purposely applied to the test masses, has allowed the measurement of noise with good statistics down to 20  μHz. The Letter presents the measured differential acceleration noise figure, which is at (1.74±0.05)  fm s^{-2}/sqrt[Hz] above 2 mHz and (6±1)×10  fm s^{-2}/sqrt[Hz] at 20  μHz, and discusses the physical sources for the measured noise. This performance provides an experimental benchmark demonstrating the ability to realize the low-frequency science potential of the LISA mission, recently selected by the European Space Agency
A strategy to characterize the LISA-Pathfinder cold gas thruster system
The cold gas micro-propulsion system that will be used during the LISA-Pathfinder mission will be one of the most important component used to ensure the "free-fall" of the enclosed test masses. In this paper we present a possible strategy to characterize the effective direction and amplitude gain of each of the 6 thrusters of this system
In-flight thermal experiments for LISA pathfinder: simulating temperature noise at the inertial sensors
Thermal Diagnostics experiments to be carried out on board LISA Pathfinder (LPF) will yield a detailed characterisation of how temperature fluctuations affect the LTP (LISA Technology Package) instrument performance, a crucial information for future space based gravitational wave detectors as the proposed eLISA. Amongst them, the study of temperature gradient fluctuations around the test masses of the Inertial Sensors will provide as well information regarding the contribution of the Brownian noise, which is expected to limit the LTP sensitivity at frequencies close to 1 mHz during some LTP experiments. In this paper we report on how these kind of Thermal Diagnostics experiments were simulated in the last LPF Simulation Campaign (November, 2013) involving all the LPF Data Analysis team and using an end-to-end simulator of the whole spacecraft. Such simulation campaign was conducted under the framework of the preparation for LPF operations
The LISA pathfinder mission
ISA Pathfinder (LPF), the second of the European Space Agency's Small Missions for Advanced Research in Technology (SMART), is a dedicated technology validation mission for future spaceborne gravitational wave detectors, such as the proposed eLISA mission. LISA Pathfinder, and its scientific payload - the LISA Technology Package - will test, in flight, the critical technologies required for low frequency gravitational wave detection: it will put two test masses in a near-perfect gravitational free-fall and control and measure their motion with unprecedented accuracy. This is achieved through technology comprising inertial sensors, high precision laser metrology, drag-free control and an ultra-precise micro-Newton propulsion system. LISA Pathfinder is due to be launched in mid-2015, with first results on the performance of the system being available 6 months thereafter.
The paper introduces the LISA Pathfinder mission, followed by an explanation of the physical principles of measurement concept and associated hardware. We then provide a detailed discussion of the LISA Technology Package, including both the inertial sensor and interferometric readout. As we approach the launch of the LISA Pathfinder, the focus of the development is shifting towards the science operations and data analysis - this is described in the final section of the paper
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