Quantum noise of non-ideal Sagnac speed meter interferometer with asymmetries

The speed meter concept has been identified as a technique that can potentially provide laser-interferometric measurements at a sensitivity level which surpasses the Standard Quantum Limit (SQL) over a broad frequency range. As with other sub-SQL measurement techniques, losses play a central role in speed meter interferometers and they ultimately determine the quantum noise limited sensitivity that can be achieved. So far in the literature, the quantum noise limited sensitivity has only been derived for lossless or lossy cases using certain approximations (for instance that the arm cavity round trip loss is small compared to the arm cavity mirror transmission). In this article we present a generalised, analytical treatment of losses in speed meters that allows accurate calculation of the quantum noise limited sensitivity of Sagnac speed meters with arm cavities. In addition, our analysis allows us to take into account potential imperfections in the interferometer such as an asymmetric beam splitter or differences of the reflectivities of the two arm cavity input mirrors. Finally,we use the examples of the proof-of-concept Sagnac speed meter currently under construction in Glasgow and a potential implementation of a Sagnac speed meter in the Einstein Telescope (ET) to illustrate how our findings affect Sagnac speed meters with meter- and kilometre-long baselines.Comment: 22 pages, 8 figures, 1 table, (minor corrections and changes made to text and figures in version 2

Experimental demonstration of coupled optical springs

Optical rigidity will play an important role in improving the sensitivity of future generations of gravitational wave (GW) interferometers, which employ high laser power in order to reach and exceed the standard quantum limit. Several experiments have demonstrated the combined effect of two optical springs on a single system for very low-weight mirror masses or membranes. In this paper we investigate the complex interactions between multiple optical springs and the surrounding apparatus in a system of comparable dynamics to a large-scale GW detector. Using three 100 g mirrors to form a coupled cavity system capable of sustaining two or more optical springs, we demonstrate a number of different regimes of opto-mechanical rigidity and measurement techniques. Our measurements reveal couplings between each optical spring and the control loops that can affect both the achievable increase in sensitivity and the stability of the system. Hence this work establishes a better understanding of the realisation of these techniques and paves the way to their application in future GW observatories, such as upgrades to Advanced LIGO

Exploring English speaking Muslim women's first-time maternity experiences: a qualitative longitudinal interview study

Background: Muslim women of child-bearing age make up a fair part of the UK society, however, literature addressing their health needs or experiences of health services have not been extensively researched. The term ‘Muslim’ is often combined with ethnic group identity, rather than used to refer to people distinguished by beliefs or affiliations. Muslim women commonly observe certain religious and cultural practices during their maternity journey. The little research there is in this area suggests that more could be done from a service provision perspective to support Muslim women through this significant life event. The aim of this study was to investigate Muslim women’s perceived needs and the factors that influence their health seeking decisions when engaging with maternity services located in North-West of England. Methods: The study used longitudinal semi-structured interviews with seven English-speaking first-time pregnant Muslim women receiving maternity care in North-West of England. Total of 21 interview; each woman was interviewed during the antenatal (29 to 40 weeks of pregnancy), immediate postnatal (within the first 2 months after birth) and later postnatal (4 months after birth) period. Audio-recorded interviews were transcribed and thematically analysed using Braun & Clark (2006) as a guide to forming a systematic approach to handling raw data. Results: Muslim women associated most aspects of the maternity journey with their religious beliefs. Religion was not the primary reason for them becoming pregnant, yet it was an aspiration for them becoming mothers. Emerging themes include: 1) a spiritual perspective; 2) expression of religious requirements; 3) perceptions of healthcare professionals. Religious values and practices provided a positive resource for women during their maternity journey. They described how healthcare professionals approached their needs, while highlighting their concerns of the negative presentation of Muslims in Western media. Conclusion: Muslim women need to feel confident to express their needs within a maternity setting. Lack of awareness amongst healthcare professionals around religious values and how Muslim women may feel when expressing their needs can inhibit them getting optimal care that acknowledges their needs. The study concludes that educating healthcare professionals about Muslim women’s worldview would enhance the quality of maternity care for Muslim women

The failure of suicide prevention in primary care: family and GP perspectives - a qualitative study

Background Although Primary care is crucial for suicide prevention, clinicians tend to report completed suicides in their care as non-preventable. We aimed to examine systemic inadequacies in suicide prevention from the perspectives of bereaved family members and GPs.Methods Qualitative study of 72 relatives or close friends bereaved by suicide and 19 General Practitioners who have experienced the suicide of patients.Results Relatives highlight failures in detecting symptoms and behavioral changes and the inability of GPs to understand the needs of patients and their social contexts. A perceived overreliance on anti-depressant treatment is a major source of criticism by family members. GPs tend to lack confidence in the recognition and management of suicidal patients, and report structural inadequacies in service provision.Conclusions Mental health and primary care services must find innovative and ethical ways to involve families in the decision-making process for patients at risk of suicide

Born into adversity: psychological distress in two birth cohorts of second-generation Irish children growing up in Britain

This work was supported by the Medical Research Council (MRC), in the form of a fellowship awarded to J.D.-M. (grant no. G0701595/1).

Candidates for a possible third-generation gravitational wave detector: comparison of ring-Sagnac and sloshing-Sagnac speedmeter interferometers

Speedmeters are known to be quantum non-demolition devices and, by potentially providing sensitivity beyond the standard quantum limit, become interesting for third generation gravitational wave detectors. Here we introduce a new configuration, the sloshing-Sagnac interferometer, and compare it to the more established ring-Sagnac interferometer. The sloshing-Sagnac interferometer is designed to provide improved quantum noise limited sensitivity and lower coating thermal noise than standard position meter interferometers employed in current gravitational wave detectors. We compare the quantum noise limited sensitivity of the ring-Sagnac and the sloshing-Sagnac interferometers, in the frequency range, from 5 Hz to 100 Hz, where they provide the greatest potential benefit. We evaluate the improvement in terms of the unweighted noise reduction below the standard quantum limit, and by finding the range up to which binary black hole inspirals may be observed. The sloshing-Sagnac was found to give approximately similar or better sensitivity than the ring-Sagnac in all cases. We also show that by eliminating the requirement for maximally-reflecting cavity end mirrors with correspondingly-thick multi-layer coatings, coating noise can be reduced by a factor of approximately 2.2 compared to conventional interferometers

Looking Beyond the Provision of Injecting Equipment to People Who Use Anabolic Androgenic Steroids: Harm Reduction and Behavior Change Goals for UK Policy

Understanding of the choices and motivations of people who use anabolic androgenic steroids (AAS) for muscular enhancement has increased greatly in the past thirty years, along with understanding of a wide range of health harms associated with this form of drug use in the community. During this period the predominant public health intervention for this population in the UK has consistently remained the provision of injecting equipment to prevent blood borne virus (BBV) transmission. The study explored the health professionals’ and other stakeholders’ perceptions on: whether the current UK public health response is sufficient to address the needs of people who use AAS, and if not, what other needs they might have. This included an exploration of whether there were gaps in harm reduction strategies or other behavioral outcomes and interventions that were needed. Interviews with 27 stakeholders who provide support to people who use AAS in a variety of roles established consensus on the need for a range of interventions to reduce harm and risk in those that choose to use AAS, to prevent initiation, to motivate and support cessation, and to prevent relapse. Study findings indicate that while providing sterile injecting equipment remains essential, it should be considered a bare minimum. The challenge is to develop and deliver a range of harm reduction interventions that look beyond BBV prevention to provide appropriate support to who choose to use AAS at all points in their cycles of use and ultimately for those choosing the temporary or permanent cessation of use

Smart Charging Technologies for Portable Electronic Devices

In this article we describe our efforts of extending demand-side control concepts to the application in portable electronic devices, such as laptop computers, mobile phones and tablet computers. As these devices feature built-in energy storage (in the form of batteries) and the ability to run complex control routines, they are well-suited for the implementation of smart charging concepts. We developed simple hardware and software based prototypes of smart charging controllers for a laptop computer that steer the charging process depending on the frequency of the electricity grid and in case of the software implementation also based on the battery charge status. If similar techniques are incorporated into millions of devices in UK households, this can contribute significantly to the stability of the electricity grid, help to mitigate the short-term power production fluctuations from renewable energy sources and avoid the high cost of building and maintaining conventional power plants as standby reserve