The Laser Interferometer Gravitational Wave Observatory (LIGO) has been directly detecting gravitational waves from compact binary mergers since 2015. We report on the first use of squeezed vacuum ...states in the direct measurement of gravitational waves with the Advanced LIGO H1 and L1 detectors. This achievement is the culmination of decades of research to implement squeezed states in gravitational-wave detectors. During the ongoing O3 observation run, squeezed states are improving the sensitivity of the LIGO interferometers to signals above 50 Hz by up to 3 dB, thereby increasing the expected detection rate by 40% (H1) and 50% (L1).
Really cool mirrors
Cooling objects to low temperature can increase the sensitivity of sensors and the operational performance of most devices. Removing most of the thermal vibrations—or phonons—such ...that the object reaches its motional quantum ground state has been achieved but typically with tiny, nanoscale objects. Using the suspended mirrors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) that form a 10-kg optomechanical oscillator, Whittle
et al.
demonstrate the ability to cool such a large-scale object to nearly the motional ground state. An upgrade to LIGO with such a modification could increase its sensitivity and range to gravitational waves but also extend studies of quantum mechanics to large-scale objects.
Science
, abh2634, this issue p.
1333
A 10-kg mechanical oscillator, the mirror of LIGO, is cooled to near its motional quantum ground state.
The motion of a mechanical object, even a human-sized object, should be governed by the rules of quantum mechanics. Coaxing them into a quantum state is, however, difficult because the thermal environment masks any quantum signature of the object’s motion. The thermal environment also masks the effects of proposed modifications of quantum mechanics at large mass scales. We prepared the center-of-mass motion of a 10-kilogram mechanical oscillator in a state with an average phonon occupation of 10.8. The reduction in temperature, from room temperature to 77 nanokelvin, is commensurate with an 11 orders-of-magnitude suppression of quantum back-action by feedback and a 13 orders-of-magnitude increase in the mass of an object prepared close to its motional ground state. Our approach will enable the possibility of probing gravity on massive quantum systems.
Abstract
Background
Clinical guidelines recommend engaging patients in shared decision making for common orthopedic procedures; however, limited work has assessed what is occurring in practice. This ...study assessed the quality of shared decision making for elective hip and knee replacement and spine surgery at four network-affiliated hospitals.
Methods
A cross-sectional sample of 875 adult patients undergoing total hip or knee joint replacement (TJR) for osteoarthritis or spine surgery for lumbar herniated disc or lumbar spinal stenosis was selected. Patients were mailed a survey including measures of Shared Decision Making (SDMP scale) and Informed, Patient-Centered (IPC) decisions. We examined decision-making across sites, surgeons, and conditions, and whether the decision-making measures were associated with better health outcomes. Analyses were adjusted for clustering of patients within surgeons.
Results
Six hundred forty-six surveys (74% response rate) were returned with sufficient responses for analysis. Patients who had TJR reported lower SDMP scores than patients who had spine surgery (2.2 vs. 2.8;
p
< 0.001). Patients who had TJR were more likely to make IPC decisions (OA = 70%, Spine = 41%;
p
< 0.001). SDMP and IPC scores varied widely across surgeons, but the site was not predictive of SDMP scores or IPC decisions (all
p
> 0.09). Higher SDMP scores and IPC decisions were associated with larger improvements in global health outcomes for patients who had TJR, but not patients who had spine surgery.
Conclusions
Measures of shared decision making and decision quality varied among patients undergoing common elective orthopedic procedures. Routine measurement of shared decision making provides insight into areas of strength across these different orthopedic conditions as well as areas in need of improvement.
This plenary volume from the Sixth International Congress on Qualitative Inquiry (2010) highlights the variety of roles played by qualitative researchers in addressing global communities in crisis. ...It shows how qualitative researchers can bridge gaps in cultural and linguistic understanding to address issues of disparity in race, ethnicity, gender, and environment in the interests of global social justice and human rights. Authored by many of the world's leading qualitative researchers, the signature articles in this volume point qualitative researchers toward a research stance of ethics, meaning, and advocacy.
High-quality optical resonant cavities require low optical loss, typically on the scale of parts per million. However, unintended micron-scale contaminants on the resonator mirrors that absorb the ...light circulating in the cavity can deform the surface thermoelastically and thus increase losses by scattering light out of the resonant mode. The point absorber effect is a limiting factor in some high-power cavity experiments, for example, the Advanced LIGO gravitational-wave detector. In this Letter, we present a general approach to the point absorber effect from first principles and simulate its contribution to the increased scattering. The achievable circulating power in current and future gravitational-wave detectors is calculated statistically given different point absorber configurations. Our formulation is further confirmed experimentally in comparison with the scattered power in the arm cavity of Advanced LIGO measured by in situ photodiodes. The understanding presented here provides an important tool in the global effort to design future gravitational-wave detectors that support high optical power and thus reduce quantum noise.
Qualitative researchers are increasingly being called upon to become human rights advocates, to help individuals and communities honor the sanctity of life, and to promote the core values of privacy, ...justice, freedom, peace, and human dignity. In this volume of plenary papers from the Fifth International of Qualitative Inquiry in 2009, leading qualitative researchers show the various dimensions of the human rights work being done by scholar/activists in the social sciences, education, health care, social services, cultural studies, and other fields.
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