The performance of arm locking in LISA

For the laser interferometer space antenna (LISA) to reach it's design sensitivity, the coupling of the free running laser frequency noise to the signal readout must be reduced by more than 14 orders of magnitude. One technique employed to reduce the laser frequency noise will be arm locking, where the laser frequency is locked to the LISA arm length. This paper details an implementation of arm locking, studies orbital effects, the impact of errors in the Doppler knowledge, and noise limits. The noise performance of arm locking is calculated with the inclusion of the dominant expected noise sources: ultra stable oscillator (clock) noise, spacecraft motion, and shot noise. Studying these issues reveals that although dual arm locking [A. Sutton & D. A Shaddock, Phys. Rev. D 78, 082001 (2008).] has advantages over single (or common) arm locking in terms of allowing high gain, it has disadvantages in both laser frequency pulling and noise performance. We address this by proposing a hybrid sensor, retaining the benefits of common and dual arm locking sensors. We present a detailed design of an arm locking controller and perform an analysis of the expected performance when used with and without laser pre-stabilization. We observe that the sensor phase changes beneficially near unity-gain frequencies of the arm-locking controller, allowing a factor of 10 more gain than previously believed, without degrading stability. We show that the LISA frequency noise goal can be realized with arm locking and Time-Delay Interferometry only, without any form of pre-stabilization.Comment: 28 pages, 36 figure

Addressing Ethical Issues in Studying Men’s Traumatic Stress

Like many human experiences, traumatic stress is highly gendered. Over the past several decades, a sub-stantial number of empirical studies have explored ethical issues in traumatic stress research. However, these studies have typically reported female samples or failed to account for the influence of gender in their analyses of mixed-sex samples. By extension, ethical issues that are relevant to male participants in traumatic stress research are poorly understood. After briefly exploring why the vulnerabilities of male participants are under-explored in traumatic stress research, this article highlights many ethical issues that are important to address when men participate in traumatic stress research, concluding with some sugges-tions for how these might be taken up to advance the field

How linear features alter predator movement and the functional\ud response

In areas of oil and gas exploration, seismic lines have been reported to alter the movement patterns of wolves (Canis lupus). We developed a mechanistic first passage time model, based on an anisotropic elliptic partial differential equation, and used this to explore how wolf movement responses to seismic lines influence the encounter rate of the wolves with their prey. The model was parametrized using 5 min GPS location data. These data showed that wolves travelled faster on seismic lines and had a higher probability of staying on a seismic line once they were on it. We simulated wolf movement on a range of seismic line densities and drew implications for the rate of predator–prey interactions as described by the functional response. The functional response exhibited a more than linear increase with respect to prey density (type III) as well as interactions with seismic line density. Encounter rates were significantly higher in landscapes with high seismic line density and were most pronounced at low prey densities. This suggests that prey at low population densities are at higher risk in environments with a high seismic line density unless they learn to avoid them

Discrete Lie Advection of Differential Forms

In this paper, we present a numerical technique for performing Lie advection of arbitrary differential forms. Leveraging advances in high-resolution finite volume methods for scalar hyperbolic conservation laws, we first discretize the interior product (also called contraction) through integrals over Eulerian approximations of extrusions. This, along with Cartan's homotopy formula and a discrete exterior derivative, can then be used to derive a discrete Lie derivative. The usefulness of this operator is demonstrated through the numerical advection of scalar fields and 1-forms on regular grids.Comment: Accepted version; to be published in J. FoC

Evaluation of exercises taken from the Druker thesis of first grade reading materials of high interest level.

Thesis (Ed.M.)--Boston Universit

Subjective wellbeing in the Indian general population: a validation study of the Personal Wellbeing Index

© 2019, Springer Nature Switzerland AG. Purpose: The Personal Wellbeing Index (PWI) is a commonly used measure of life satisfaction that reflects a person’s level of subjective wellbeing (SWB). The present study aimed to establish the validity and reliability of the PWI in a large sample of Indian adults and describe their SWB. Methods: 2004 Indian adults completed a cross-sectional online survey, which was presented in English and included the PWI and demographic questions. The sample was split to assess the psychometric properties of the 7-item (n = 981) and 8-item (n = 937) versions of the PWI. Results: Both the 7- and 8-item versions of the PWI demonstrated adequate internal consistency (α =.89 and.88, respectively). The global means for both versions of the PWI (7-item = 74.43, 8-item = 73.82) were within the normative range for Western countries. Achieving in life had the lowest domain scores for both the 7-item (M = 70.51) and 8-item (M = 68.37) versions; the spirituality or religion domain had the highest domain score in the 8-item version (M = 78.84). Conclusion: The findings suggest that both the 7- and 8-item versions of the PWI are valid and reliable measures of life satisfaction for use in India. The global mean scores for both versions of the PWI were within the normative range for Western countries. In this study, Indians reported high levels of satisfaction with their spirituality or religion, suggesting this domain may be an important contributor of SWB; however, more research is needed to determine this

Dynamic evolution of the source volumes of gradual and impulsive solar flare emissions

This study compares flare source volumes inferred from impulsive hard X-rays and microwaves with those derived from density sensitive soft X-ray line ratios in the O VII spectrum. The data for this study were obtained with the SMM Hard X-Ray Burst Spectrometer, Earth-based radio observatories, and the SOLEX-B spectrometer on the P78-1 satellite. Data were available for the flares of 1980 April 8, 1980 May 9, and 1981 February 26. The hard X-ray/microwave source volume is determined under the assumption that the same electron temperature or power law index characterizes both the source of hard X-rays and the source of microwaves. The O VII line ratios yield the density and volume of the 2 X 10 to the 6th K plasma. For all three flares, the O VII source volume is found to be smallest at the beginning of the flare, near the time when the impulsive hard X-ray/microwave volume reaches its first maximum. At this time, the O VII volume is three to four orders of magnitude smaller than that inferred from the hard X-ray/microwave analysis. Subsequently, the O VII source volume increases by one or two orders of magnitude then remains almost constant until the end of the flare when it apparently increases again

A survey of befriending services for people with intellectual disabilities in the UK

Background: Individuals with intellectual disability (ID) may benefit from befriending services, which can help to widen their social networks and reduce social isolation. This study examined the characteristics and challenges encountered by befriending services in the United Kingdom and motivations and experiences of volunteers working with people with ID. // Methods: This is a cross-sectional study using two separate online surveys, one for befriending services and one for volunteers. // Results: Eight services and 58 volunteers (aged 15 to 72) responded to the survey. The two major issues faced by befriending services were related to funding and recruitment of volunteers. The most common volunteering motivation was “To give something back” (75.9%). While unemployed volunteers were more likely to be motivated by wanting to do something useful with their spare time (OR 3.62, 95% CI 1.09–12.05), young volunteers expressed wanting to gain work experience through volunteering (OR 11.37, 95% CI 1.31–98.59). Most volunteers reported that volunteering had a positive impact on them and would like to continue volunteering in the future. Both positive and negative volunteer experiences were explored. // Discussion: Volunteers experienced unique difficulties in interacting with service users with ID due to physical and cognitive barriers. More training and support could be provided to volunteers to help them manage these difficulties and to improve outcomes and experiences of both volunteers and individuals with ID. Policy guidance should be developed on how to set up high-quality befriending services for this group