Guideline concordance and antibiotic-associated adverse events between Veterans administration and non-Veterans administration dental settings: a retrospective cohort study

Background: Antibiotics prescribed as infection prophylaxis prior to dental procedures have the potential for serious adverse drug events (ADEs). However, the extent to which guideline concordance and different dental settings are associated with ADEs from antibiotic prophylaxis is unknown. Aim: The purpose was to assess guideline concordance and antibiotic-associated ADEs and whether it differs by VA and non-VA settings. Methods: Retrospective cohort study of antibiotic prophylaxis prescribed to adults with cardiac conditions or prosthetic joints from 2015 to 2017. Multivariable logistic regression models were fit to assess the impact of ADEs, guideline concordance and dental setting. An interaction term of concordance and dental setting evaluated whether the relationship between ADEs and concordance differed by setting. Results: From 2015 to 2017, 61,124 patients with antibiotic prophylaxis were identified with 62 (0.1%) having an ADE. Of those with guideline concordance, 18 (0.09%) had an ADE while 44 (0.1%) of those with a discordant antibiotic had an ADE (unadjusted OR: 0.84, 95% CI: 0.49-1.45). Adjusted analyses showed that guideline concordance was not associated with ADEs (OR: 0.78, 95% CI: 0.25-2.46), and this relationship did not differ by dental setting (Wald χ^2 p-value for interaction = 0.601). Conclusion: Antibiotic-associated ADEs did not differ by setting or guideline concordance.

Changes in antibiotic prescribing by dentists in the United States, 2012-2019

OBJECTIVES

Dentists prescribe 10% of all outpatient antibiotics in the United States and are the top specialty prescriber. Data on current antibiotic prescribing trends are scarce. Therefore, we evaluated trends in antibiotic prescribing rates by dentists, and we further assessed whether these trends differed by agent, specialty, and by patient characteristics.

DESIGN

Retrospective study of dental antibiotic prescribing included data from the IQVIA Longitudinal Prescription Data set from January 1, 2012 to December 31, 2019.

METHODS

The change in the dentist prescribing rate and mean days' supply were evaluated using linear regression models.

RESULTS

Dentists wrote >216 million antibiotic prescriptions between 2012 and 2019. The annual dental antibiotic prescribing rate remained steady over time (P = .5915). However, the dental prescribing rate (antibiotic prescriptions per 1,000 dentists) increased in the Northeast (by 1,313 antibiotics per 1,000 dentists per year), among oral and maxillofacial surgeons (n = 13,054), prosthodontists (n = 2,381), endodontists (n = 2,255), periodontists (n = 1,961), and for amoxicillin (n = 2,562; P < .04 for all). The mean days' supply significantly decreased over the study period by 0.023 days per 1,000 dentists per year (P < .001).

CONCLUSIONS

From 2012 to 2019, dental prescribing rates for antibiotics remained unchanged, despite decreases in antibiotic prescribing nationally and changes in guidelines during the study period. However, mean days' supply decreased over time. Dental specialties, such as oral and maxillofacial surgeons, had the highest prescribing rate with increases over time. Antibiotic stewardship efforts to improve unnecessary prescribing by dentists and targeting dental specialists may decrease overall antibiotic prescribing rates by dentists.

How decisions are made: Antibiotic stewardship in dentistry

BACKGROUND

We performed a preimplementation assessment of workflows, resources, needs, and antibiotic prescribing practices of trainees and practicing dentists to inform the development of an antibiotic-stewardship clinical decision-support tool (CDST) for dentists.

METHODS

We used a technology implementation framework to conduct the preimplementation assessment via surveys and focus groups of students, residents, and faculty members. Using Likert scales, the survey assessed baseline knowledge and confidence in dental providers' antibiotic prescribing. The focus groups gathered information on existing workflows, resources, and needs for end users for our CDST.

RESULTS

Of 355 dental providers recruited to take the survey, 213 (60%) responded: 151 students, 27 residents, and 35 faculty. The average confidence in antibiotic prescribing decisions was 3.2 ± 1.0 on a scale of 1 to 5 (ie, moderate). Dental students were less confident about prescribing antibiotics than residents and faculty (P < .01). However, antibiotic prescribing knowledge was no different between dental students, residents, and faculty. The mean likelihood of prescribing an antibiotic when it was not needed was 2.7 ± 0.6 on a scale of 1 to 5 (unlikely to maybe) and was not meaningfully different across subgroups (P = .10). We had 10 participants across 3 focus groups: 7 students, 2 residents, and 1 faculty member. Four major themes emerged, which indicated that dentists: (1) make antibiotic prescribing decisions based on anecdotal experiences; (2) defer to physicians' recommendations; (3) have limited access to evidence-based resources; and (4) want CDST for antibiotic prescribing.

CONCLUSIONS

Dentists' confidence in antibiotic prescribing increased by training level, but knowledge did not. Trainees and practicing dentists would benefit from a CDST to improve appropriateness of antibiotic prescribing.

Comparison of guideline concordant antibiotic prophylaxis in Veterans Affairs and non-Veterans Affairs dental settings among those with cardiac conditions or prosthetic joints

BACKGROUND

No research has been conducted to assess whether antibiotic prophylaxis prescribing differs by dental setting. Therefore, the goal of this study was to compare the prescribing of antibiotic prophylaxis in Veterans Affairs (VA) and non-Veterans Affairs settings.

METHODS

This was a retrospective study of veteran and non-veteran dental patients with cardiac conditions or prosthetic joints between 2015-2017. Multivariable log binomial regression analysis was conducted to compare concordant prescribing by setting with a sub-analysis for errors of dosing based on antibiotic duration (i.e., days prescribed).

RESULTS

A total of 61,124 dental visits that received a prophylactic antibiotic were included. Most were male (61.0%), and 55 years of age or older (76.2%). Nearly a third (32.7%) received guideline concordant prophylaxis. VA dental settings had a lower prevalence of guideline concordant prescribing compared to non-VA settings in unadjusted results (unadjusted prevalence ratio [uPR] = 0.92, 95% CI: 0.90-0.95). After adjustment, prevalence of guideline concordant prescribing was higher in those with prosthetic joints in the VA setting (adjusted prevalence ratio [aPR] = 1.73, 95% CI: 1.59-1.88), with no difference identified in those without a prosthetic joint (aPR = 0.99, 95% CI: 0.96-1.01). Concordance of dosing was higher in VA compared to non-VA settings (aPR = 1.11, 95% CI: 1.07-1.15).

CONCLUSIONS

VA has a higher prevalence of guideline concordant prescribing among those with prosthetic joints and when assessing dosing errors. Though the presence of an integrated electronic health record (EHR) may be contributing to these differences, other system or prescriber-related factors may be responsible. Future studies should focus on to what extent the integrated EHR may be responsible for increased guideline concordant prescribing in the VA setting.

Barriers to and facilitators of opioid prescribing by dentists in the United States: A qualitative study

BACKGROUND

Dentists in the United States frequently prescribe opioids for dental-related pain, although evidence shows superior efficacy of nonopioids for pain management. A national sample of US dentists was interviewed to understand the barriers and facilitators to opioid prescribing.

METHODS

Semistructured one-on-one telephone interviews were conducted with dentists sampled from the 6 regions of The National Dental Practice-Based Research Network. Responses were coded into the domains of the Capability, Opportunity and Motivation Model of Behavior. Potential behavior change interventions were identified for targeted themes.

RESULTS

Seventy-three interviews were qualitatively analyzed. Most of those interviewed were general dentists (86.3%) and on average (SD) were in practice for 24.3 (13.0) years. Ten themes were identified within the Capability, Opportunity and Motivation Model of Behavior. Dentists' knowledge of opioid risk, ability to identify substance use disorder behavior, and capability of communicating pain management plans to patients or following clinic policies or state and federal regulations were linked with judicious opioid prescribing. Dentists reported prescribing opioids if they determined clinical necessity or feared negative consequences for refusing to prescribe opioids.

CONCLUSIONS

Dentists' opioid decision making is influenced by a range of real-world practice experiences and patient and clinic factors. Education and training that target dentists' knowledge gaps and changes in dentists' practice environment can encourage effective communication of pain management strategies with patients and prescribing of nonopioids as first-line analgesics while conserving opioid use.

PRACTICAL IMPLICATIONS

Identified knowledge gaps in dentistry can be targets for education, clinical guidelines, and policy interventions to ensure safe and appropriate prescribing of opioids.

Search for Subsolar-Mass Binaries in the First Half of Advanced LIGO's and Advanced Virgo's Third Observing Run

We report on a search for compact binary coalescences where at least one binary component has a mass between 0.2  M_{⊙} and 1.0  M_{⊙} in Advanced LIGO and Advanced Virgo data collected between 1 April 2019 1500 UTC and 1 October 2019 1500 UTC. We extend our previous analyses in two main ways: we include data from the Virgo detector and we allow for more unequal mass systems, with mass ratio q≥0.1. We do not report any gravitational-wave candidates. The most significant trigger has a false alarm rate of 0.14  yr^{-1}. This implies an upper limit on the merger rate of subsolar binaries in the range [220-24200]  Gpc^{-3} yr^{-1}, depending on the chirp mass of the binary. We use this upper limit to derive astrophysical constraints on two phenomenological models that could produce subsolar-mass compact objects. One is an isotropic distribution of equal-mass primordial black holes. Using this model, we find that the fraction of dark matter in primordial black holes in the mass range 0.2  M_{⊙}<m_{PBH}<1.0  M_{⊙} is f_{PBH}≡Ω_{PBH}/Ω_{DM}≲6%. This improves existing constraints on primordial black hole abundance by a factor of ∼3. The other is a dissipative dark matter model, in which fermionic dark matter can collapse and form black holes. The upper limit on the fraction of dark matter black holes depends on the minimum mass of the black holes that can be formed: the most constraining result is obtained at M_{min}=1  M_{⊙}, where f_{DBH}≡Ω_{DBH}/Ω_{DM}≲0.003%. These are the first constraints placed on dissipative dark models by subsolar-mass analyses.

An experimental approach to analyze aerosol and splatter formations due to a dental procedure

Throughout 2020 and beyond, the entire world has observed a continuous increase in the infectious spread of the novel coronavirus (SARS-CoV-2) otherwise known as COVID-19. The high transmission of this airborne virus has raised countless concerns regarding safety measures employed in the working conditions for medical professionals. Specifically, those who perform treatment procedures on patients which intrinsically create mists of fine airborne droplets, i.e., perfect vectors for this and other viruses to spread. The present study focuses on understanding the splatter produced due to a common dentistry technique to remove plaque buildup on teeth. This technique uses a high-speed dentistry instrument, e.g., a Cavitron ultrasonic scaler, to scrape along the surface of a patient's teeth. This detailed understanding of the velocity and the trajectory of the droplets generated by the splatter will aid in the development of hygiene mechanisms to guarantee the safety of those performing these procedures and people in clinics or hospitals. Optical flow tracking velocimetry (OFTV) method was employed to obtain droplet velocity and trajectory in a two-dimensional plane. Multiple data collection planes were taken in different orientations around a model of adult mandibular teeth. This technique provided pseudo-three-dimensional velocity information for the droplets within the splatter developed from this high-speed dental instrument. These results indicated that within the three-dimensional splatter produced there were high velocities (1-2 m/s) observed directly below the intersection point between the front teeth and the scaler. The splatter formed a cone-shape structure that propagated 10-15 mm away from the location of the scaler tip. From the droplet trajectories, it was observed that high velocity isolated droplets propagate away from the bulk of the splatter. It is these droplets which are concerning for health safety to those performing the medical procedures. Using a shadowgraphy technique, we further characterize the individual droplets' size and their individual velocity. We then compare these results to previously published distributions. The obtained data can be used as a first step to further examine flow and transport of droplets in clinics/dental offices.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Silicate bonding of sapphire to SESAMs: adjustable thermal lensing for high-power lasers

Silicate bonding is a flexible bonding method that enables room-temperature bonding of many types of materials with only moderate flatness constraints. It is a promising approach for bonding components in high power laser systems, since it results in a thin and low-absorption interface layer between the bonded materials. Here we demonstrate for the first time silicate bonding of a sapphire window to a SEmiconductor Saturable Absorber Mirror (SESAM) and use the composite structure to mode-lock a high-power thin-disk laser. We characterize the fabricated devices both theoretically and experimentally and show how the thermally induced lens of the composite structure can be tuned both in magnitude and sign via the thickness of the sapphire window. We demonstrate mode-locking of a high-power thin-disk laser oscillator with these devices. The altered thermal lens allows us to increase the output power to 233 W, a 70-W-improvement compared to the results achieved with a state-of-the-art SESAM in the same cavity.

Computer simulation of the SARS-CoV-2 contamination risk in a large dental clinic

COVID-19, caused by the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) virus, has been rapidly spreading worldwide since December 2019, causing a public health crisis. Recent studies showed SARS-CoV-2's ability to infect humans via airborne routes. These motivated the study of aerosol and airborne droplet transmission in a variety of settings. This study performs a large-scale numerical simulation of a real-world dentistry clinic that contains aerosol-generating procedures. The simulation tracks the dispersion of evaporating droplets emitted during ultrasonic dental scaling procedures. The simulation considers 25 patient treatment cubicles in an open plan dentistry clinic. The droplets are modeled as having a volatile (evaporating) and nonvolatile fraction composed of virions, saliva, and impurities from the irrigant water supply. The simulated clinic's boundary and flow conditions are validated against experimental measurements of the real clinic. The results evaluate the behavior of large droplets and aerosols. We investigate droplet residence time and travel distance for different droplet diameters, surface contamination due to droplet settling and deposition, airborne aerosol mass concentration, and the quantity of droplets that escape through ventilation. The simulation results raise concerns due to the aerosols' long residence times (averaging up to 7.31 min) and travel distances (averaging up to 24.45 m) that exceed social distancing guidelines. Finally, the results show that contamination extends beyond the immediate patient treatment areas, requiring additional surface disinfection in the clinic. The results presented in this research may be used to establish safer dental clinic operating procedures, especially if paired with future supplementary material concerning the aerosol viral load generated by ultrasonic scaling and the viral load thresholds required to infect humans.

Potentially Inappropriate Medication Combination with Opioids among Older Dental Patients: A Retrospective Review of Insurance Claims Data

BACKGROUND

Opioid prescribing by dentists for older patients receiving medications with potential contraindications and the subsequent impact on acute care outcomes is not well described.

OBJECTIVES

Our objective of this paper was to evaluate the use of potentially inappropriate medication combinations (PIMCs) involving opioids prescribed by dentists according to the Beers Criteria and risks of 30-day emergency department (ED) visits and all-cause hospitalization among commercially insured dental patients ages 65 years and older.

METHODS

We conducted a retrospective cohort study of 40,800 older dental patient visits in which opioids were prescribed between 2011 and 2015 using the IBM MarketScan databases. Data collection from dental, medical, and pharmacy claims included information on the concurrent use of PIMCs and outcomes of all-cause acute care utilization over the 30-day period after dental encounters.

RESULTS

For the overall cohort, the median age was 69 years, and 45% were women. The prevalence of PIMCs per Beers Criteria was 10.4%. A total of 947 all-cause acute care events were observed in the 30 days post-dental visit. Patients with PIMCs involving opioids prescribed by dentists according to the Beers Criteria had higher rates of acute care use (3.3% vs 2.2%, p<0.001), which were associated with an increased risk of all-cause acute care utilization (adjusted risk ratio [RR] 1.23, 95% confidence interval [CI] 1.02-1.48). A dose-response relationship was seen with increasing oral morphine equivalents prescribed and increased acute care utilization (p<0.001).

CONCLUSION

A significant proportion of older patients receiving opioids at dental visits use psychotropic medications that in combination should be avoided according to the American Geriatric Society Beers Criteria.

GW190521: A Binary Black Hole Merger with a Total Mass of 150 M_{⊙}

On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85_{-14}^{+21}  M_{⊙} and 66_{-18}^{+17}  M_{⊙} (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65  M_{⊙}. We calculate the mass of the remnant to be 142_{-16}^{+28}  M_{⊙}, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is 5.3_{-2.6}^{+2.4}  Gpc, corresponding to a redshift of 0.82_{-0.34}^{+0.28}. The inferred rate of mergers similar to GW190521 is 0.13_{-0.11}^{+0.30}  Gpc^{-3} yr^{-1}.

Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is binary neutron star, neutron star-black hole, and binary black hole systems. The ability to localize the sources is given as a sky-area probability, luminosity distance, and comoving volume. The median sky localization area (90% credible region) is expected to be a few hundreds of square degrees for all types of binary systems during O3 with the Advanced LIGO and Virgo (HLV) network. The median sky localization area will improve to a few tens of square degrees during O4 with the Advanced LIGO, Virgo, and KAGRA (HLVK) network. During O3, the median localization volume (90% credible region) is expected to be on the order of 10 5 , 10 6 , 10 7 Mpc 3 for binary neutron star, neutron star-black hole, and binary black hole systems, respectively. The localization volume in O4 is expected to be about a factor two smaller than in O3. We predict a detection count of 1 - 1 + 12 ( 10 - 10 + 52 ) for binary neutron star mergers, of 0 - 0 + 19 ( 1 - 1 + 91 ) for neutron star-black hole mergers, and 17 - 11 + 22 ( 79 - 44 + 89 ) for binary black hole mergers in a one-calendar-year observing run of the HLV network during O3 (HLVK network during O4). We evaluate sensitivity and localization expectations for unmodeled signal searches, including the search for intermediate mass black hole binary mergers.

Search for Subsolar Mass Ultracompact Binaries in Advanced LIGO's Second Observing Run

We present a search for subsolar mass ultracompact objects in data obtained during Advanced LIGO's second observing run. In contrast to a previous search of Advanced LIGO data from the first observing run, this search includes the effects of component spin on the gravitational waveform. We identify no viable gravitational-wave candidates consistent with subsolar mass ultracompact binaries with at least one component between 0.2  M_{⊙}-1.0  M_{⊙}. We use the null result to constrain the binary merger rate of (0.2  M_{⊙}, 0.2  M_{⊙}) binaries to be less than 3.7×10^{5}  Gpc^{-3} yr^{-1} and the binary merger rate of (1.0  M_{⊙}, 1.0  M_{⊙}) binaries to be less than 5.2×10^{3}  Gpc^{-3} yr^{-1}. Subsolar mass ultracompact objects are not expected to form via known stellar evolution channels, though it has been suggested that primordial density fluctuations or particle dark matter with cooling mechanisms and/or nuclear interactions could form black holes with subsolar masses. Assuming a particular primordial black hole (PBH) formation model, we constrain a population of merging 0.2  M_{⊙} black holes to account for less than 16% of the dark matter density and a population of merging 1.0  M_{⊙} black holes to account for less than 2% of the dark matter density. We discuss how constraints on the merger rate and dark matter fraction may be extended to arbitrary black hole population models that predict subsolar mass binaries.

High Precision Detection of Change in Intermediate Range Order of Amorphous Zirconia-Doped Tantala Thin Films Due to Annealing

Understanding the local atomic order in amorphous thin film coatings and how it relates to macroscopic performance factors, such as mechanical loss, provides an important path towards enabling the accelerated discovery and development of improved coatings. High precision x-ray scattering measurements of thin films of amorphous zirconia-doped tantala (ZrO_{2}-Ta_{2}O_{5}) show systematic changes in intermediate range order (IRO) as a function of postdeposition heat treatment (annealing). Atomic modeling captures and explains these changes, and shows that the material has building blocks of metal-centered polyhedra and the effect of annealing is to alter the connections between the polyhedra. The observed changes in IRO are associated with a shift in the ratio of corner-sharing to edge-sharing polyhedra. These changes correlate with changes in mechanical loss upon annealing, and suggest that the mechanical loss can be reduced by developing a material with a designed ratio of corner-sharing to edge-sharing polyhedra.

Tests of General Relativity with GW170817

The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due to large extra dimensions. Finally, the polarization content of the gravitational wave signal is studied. The results of all tests performed here show good agreement with GR.

Assessment of the Appropriateness of Antibiotic Prescriptions for Infection Prophylaxis Before Dental Procedures, 2011 to 2015

Importance

Antibiotics are recommended before certain dental procedures in patients with select comorbidities to prevent serious distant site infections.

Objective

To assess the appropriateness of antibiotic prophylaxis before dental procedures using Truven, a national integrated health claims database.

Design, Setting, and Participants

Retrospective cohort study. Dental visits from 2011 to 2015 were linked to medical and prescription claims from 2009 to 2015. The dates of analysis were August 2018 to January 2019. Participants were US patients with commercial dental insurance without a hospitalization or extraoral infection 14 days before antibiotic prophylaxis (defined as a prescription with ≤2 days' supply dispensed within 7 days before a dental visit).

Exposures

Presence or absence of cardiac diagnoses and dental procedures that manipulated the gingiva or tooth periapex.

Main Outcomes and Measures

Appropriate antibiotic prophylaxis was defined as a prescription dispensed before a dental visit with a procedure that manipulated the gingiva or tooth periapex in patients with an appropriate cardiac diagnosis. To assess associations between patient or dental visit characteristics and appropriate antibiotic prophylaxis, multivariable logistic regression was used. A priori hypothesis tests were performed with an α level of .05.

Results

From 2011 to 2015, antibiotic prophylaxis was prescribed for 168 420 dental visits for 91 438 patients (median age, 63 years; interquartile range, 55-72 years; 57.2% female). Overall, these 168 420 dental visits were associated with 287 029 dental procedure codes (range, 1-14 per visit). Most dental visits were classified as diagnostic (70.2%) and/or preventive (58.8%). In 90.7% of dental visits, a procedure was performed that would necessitate antibiotic prophylaxis in high-risk cardiac patients. Prevalent comorbidities include prosthetic joint devices (42.5%) and cardiac conditions at the highest risk of adverse outcome from infective endocarditis (20.9%). Per guidelines, 80.9% of antibiotic prophylaxis prescriptions before dental visits were unnecessary. Clindamycin was more likely to be unnecessary relative to amoxicillin (odds ratio [OR], 1.10; 95% CI, 1.05-1.15). Prosthetic joint devices (OR, 2.31; 95% CI, 2.22-2.41), tooth implant procedures (OR, 1.66; 95% CI, 1.45-1.89), female sex (OR, 1.21; 95% CI, 1.17-1.25), and visits occurring in the western United States (OR, 1.15; 95% CI, 1.06-1.25) were associated with unnecessary antibiotic prophylaxis.

Conclusion and Relevance

More than 80% of antibiotics prescribed for infection prophylaxis before dental visits were unnecessary. Implementation of antimicrobial stewardship in dental practices is an opportunity to improve antibiotic prescribing for infection prophylaxis.

Constraining the p-Mode-g-Mode Tidal Instability with GW170817

We analyze the impact of a proposed tidal instability coupling p modes and g modes within neutron stars on GW170817. This nonresonant instability transfers energy from the orbit of the binary to internal modes of the stars, accelerating the gravitational-wave driven inspiral. We model the impact of this instability on the phasing of the gravitational wave signal using three parameters per star: an overall amplitude, a saturation frequency, and a spectral index. Incorporating these additional parameters, we compute the Bayes factor (lnB_{!pg}^{pg}) comparing our p-g model to a standard one. We find that the observed signal is consistent with waveform models that neglect p-g effects, with lnB_{!pg}^{pg}=0.03_{-0.58}^{+0.70} (maximum a posteriori and 90% credible region). By injecting simulated signals that do not include p-g effects and recovering them with the p-g model, we show that there is a ≃50% probability of obtaining similar lnB_{!pg}^{pg} even when p-g effects are absent. We find that the p-g amplitude for 1.4  M_{⊙} neutron stars is constrained to less than a few tenths of the theoretical maximum, with maxima a posteriori near one-tenth this maximum and p-g saturation frequency ∼70  Hz. This suggests that there are less than a few hundred excited modes, assuming they all saturate by wave breaking. For comparison, theoretical upper bounds suggest ≲10^{3} modes saturate by wave breaking. Thus, the measured constraints only rule out extreme values of the p-g parameters. They also imply that the instability dissipates ≲10^{51}  erg over the entire inspiral, i.e., less than a few percent of the energy radiated as gravitational waves.

Search for Subsolar-Mass Ultracompact Binaries in Advanced LIGO's First Observing Run

We present the first Advanced LIGO and Advanced Virgo search for ultracompact binary systems with component masses between 0.2  M_{⊙}-1.0  M_{⊙} using data taken between September 12, 2015 and January 19, 2016. We find no viable gravitational wave candidates. Our null result constrains the coalescence rate of monochromatic (delta function) distributions of nonspinning (0.2  M_{⊙}, 0.2  M_{⊙}) ultracompact binaries to be less than 1.0×10^{6}  Gpc^{-3}  yr^{-1} and the coalescence rate of a similar distribution of (1.0  M_{⊙}, 1.0  M_{⊙}) ultracompact binaries to be less than 1.9×10^{4}  Gpc^{-3}  yr^{-1} (at 90% confidence). Neither black holes nor neutron stars are expected to form below ∼1  M_{⊙} through conventional stellar evolution, though it has been proposed that similarly low mass black holes could be formed primordially through density fluctuations in the early Universe and contribute to the dark matter density. The interpretation of our constraints in the primordial black hole dark matter paradigm is highly model dependent; however, under a particular primordial black hole binary formation scenario we constrain monochromatic primordial black hole populations of 0.2  M_{⊙} to be less than 33% of the total dark matter density and monochromatic populations of 1.0  M_{⊙} to be less than 5% of the dark matter density. The latter strengthens the presently placed bounds from microlensing surveys of massive compact halo objects (MACHOs) provided by the MACHO and EROS Collaborations.

1630. Antibiotics Prescribed for Infection Prophylaxis Prior to Dental Procedures Are Frequently Unnecessary in the United States

Background

Antibiotics are recommended prior to certain dental procedures (“antibiotic prophylaxis”) in patients with select comorbidities to prevent serious distant site infections. Our objective was to assess the appropriateness of antibiotic prophylaxis by dentists using Truven, a national integrated medical, dental, and prescription (Rx) claims database of 350 commercial plans.

Methods

Cross-sectional study of 8.7 million adult dental visits in 2015. Antibiotic prophylaxis was defined as Rx with &lt;3 days supply dispensed within 7 days before a dental visit. Medical diagnoses were evaluated in medical/hospital claims from 2009 to 2015. Patients with hospitalizations and infection diagnoses 14 days prior to the Rx date were excluded. Appropriate antibiotic prophylaxis was defined as a dental visit with a procedure that manipulated the gingiva/tooth periapex in patients with an appropriate cardiac diagnosis. Chi Square and logistic regression were applied.

Results

In 2015, 30,726 antibiotics were prescribed for dental infection prophylaxis for 21,986 patients (mean age=58.6 + 15.0 years; 55.9% female). Amoxicillin (68.5%) and clindamycin (14.7%) were most common. 29,879 dental visits were associated with 69,639 dental codes ([CDTs]; range 1–14 CDTs/visit). Most dental visits were diagnostic (65.9% of visits with &gt;1 diagnostic CDT), preventative (53.0%), and restorative (11.2%). 98.4% of dental visits had an appropriate CDT for antibiotic prophylaxis. Comorbidities include orthopedic implants (45.4%) and cardiac diagnoses at the highest risk of infective endocarditis (22.2%). Per guidelines, 78.0% of dental visits with antibiotic prophylaxis were inappropriate. Amoxicillin was more likely to be inappropriate than other agents (OR=1.65; 95% CI: 1.55–1.76). Orthopedic implants (OR=3.35; 95% CI: 3.14–3.56), tooth implant procedures (OR=3.30; 95% CI: 2.48–4.39), females (OR=1.35; 95% CI: 1.27–1.43) and the western US (OR=1.22; 95% CI: 1.09–1.36) were associated with inappropriate prescribing.

Conclusion

Antibiotic prophylaxis is prescribed for indicated dental procedures, but is not appropriately limited to patients with cardiac diagnoses per guidelines. Implementing antimicrobial stewardship efforts in dental practices may be an opportunity to improve antibiotic prescribing for infection prophylaxis.

Disclosures

J. C. McGregor, Merck: Grant Investigator, Research grant.

Amorphous Silicon with Extremely Low Absorption: Beating Thermal Noise in Gravitational Astronomy

Amorphous silicon has ideal properties for many applications in fundamental research and industry. However, the optical absorption is often unacceptably high, particularly for gravitational-wave detection. We report a novel ion-beam deposition method for fabricating amorphous silicon with unprecedentedly low unpaired electron-spin density and optical absorption, the spin limit on absorption being surpassed for the first time. At low unpaired electron density, the absorption is no longer correlated with electron spins, but with the electronic mobility gap. Compared to standard ion-beam deposition, the absorption at 1550 nm is lower by a factor of ≈100. This breakthrough shows that amorphous silicon could be exploited as an extreme performance optical coating in near-infrared applications, and it represents an important proof of concept for future gravitational-wave detectors.

GW170817: Measurements of Neutron Star Radii and Equation of State

On 17 August 2017, the LIGO and Virgo observatories made the first direct detection of gravitational waves from the coalescence of a neutron star binary system. The detection of this gravitational-wave signal, GW170817, offers a novel opportunity to directly probe the properties of matter at the extreme conditions found in the interior of these stars. The initial, minimal-assumption analysis of the LIGO and Virgo data placed constraints on the tidal effects of the coalescing bodies, which were then translated to constraints on neutron star radii. Here, we expand upon previous analyses by working under the hypothesis that both bodies were neutron stars that are described by the same equation of state and have spins within the range observed in Galactic binary neutron stars. Our analysis employs two methods: the use of equation-of-state-insensitive relations between various macroscopic properties of the neutron stars and the use of an efficient parametrization of the defining function p(ρ) of the equation of state itself. From the LIGO and Virgo data alone and the first method, we measure the two neutron star radii as R_{1}=10.8_{-1.7}^{+2.0}  km for the heavier star and R_{2}=10.7_{-1.5}^{+2.1}  km for the lighter star at the 90% credible level. If we additionally require that the equation of state supports neutron stars with masses larger than 1.97  M_{⊙} as required from electromagnetic observations and employ the equation-of-state parametrization, we further constrain R_{1}=11.9_{-1.4}^{+1.4}  km and R_{2}=11.9_{-1.4}^{+1.4}  km at the 90% credible level. Finally, we obtain constraints on p(ρ) at supranuclear densities, with pressure at twice nuclear saturation density measured at 3.5_{-1.7}^{+2.7}×10^{34}  dyn cm^{-2} at the 90% level.

Silicon-Based Optical Mirror Coatings for Ultrahigh Precision Metrology and Sensing

Thermal noise of highly reflective mirror coatings is a major limit to the sensitivity of many precision laser experiments with strict requirements such as low optical absorption. Here, we investigate amorphous silicon and silicon nitride as an alternative to the currently used combination of coating materials, silica, and tantala. We demonstrate an improvement by a factor of ≈55 with respect to the lowest so far reported optical absorption of amorphous silicon at near-infrared wavelengths. This reduction was achieved via a combination of heat treatment, final operation at low temperature, and a wavelength of 2  μm instead of the more commonly used 1550 nm. Our silicon-based coating offers a factor of 12 thermal noise reduction compared to the performance possible with silica and tantala at 20 K. In gravitational-wave detectors, a noise reduction by a factor of 12 corresponds to an increase in the average detection rate by three orders of magnitude (≈12^{3}).

Dentists' prescribing of antibiotics and opioids to Medicare Part D beneficiaries: Medications of high impact to public health

BACKGROUND

Gaining a better understanding of dental prescribing can help identify opportunities for intervention regarding optimal medication use. The purpose of this study is to characterize opioid and antibiotic prescribing patterns of dentists in the United States for Medicare Part D beneficiaries.

METHODS

The authors conducted a retrospective cross-sectional analysis of national 2014 Medicare Part D Prescriber Public Use File data. Providers in the data set with dental-related disciplines were included (n = 99,797). Outcomes of interest were mean days' supply and mean number of claims reported per claim, beneficiary, and prescriber discipline.

RESULTS

Of the 6,724,372 dental prescription claims submitted, 3,947,848 (58.7%) and 1,312,796 (19.5%) were for antibiotics and opioids, respectively. Sixty-nine percent of dentists in the highest quartile of opioid prescribers were also in the highest quartile of antibiotic prescribers (r² = 0.7778; P < .01). The mean (standard deviation) days' supply per claim was 6.9 (5.3) days (range, 1-90 days) for antibiotics and 3.6 (2.0) days (range, 1-44.5 days) for opioids. Of the 33,348 dental providers who prescribed opioids, 18,971 (56.9%) prescribed a mean opioid days per claim greater than the recommended duration of 3 days for acute pain.

CONCLUSION

Opioids and antibiotics are the medications most prescribed by dentists. On the basis of national recommendations and results of studies from other countries, the length of therapy prescribed may be excessive. Further studies should be conducted to assess appropriateness of dental prescriptions.

PRACTICAL IMPLICATIONS

Dentistry should be considered for antibiotic and opioid stewardship interventions along with medicine.

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω_{0}^{T}<5.58×10^{-8}, Ω_{0}^{V}<6.35×10^{-8}, and Ω_{0}^{S}<1.08×10^{-7} at a reference frequency f_{0}=25  Hz.

GW170817: Implications for the Stochastic Gravitational-Wave Background from Compact Binary Coalescences

The LIGO Scientific and Virgo Collaborations have announced the event GW170817, the first detection of gravitational waves from the coalescence of two neutron stars. The merger rate of binary neutron stars estimated from this event suggests that distant, unresolvable binary neutron stars create a significant astrophysical stochastic gravitational-wave background. The binary neutron star component will add to the contribution from binary black holes, increasing the amplitude of the total astrophysical background relative to previous expectations. In the Advanced LIGO-Virgo frequency band most sensitive to stochastic backgrounds (near 25 Hz), we predict a total astrophysical background with amplitude Ω_{GW}(f=25  Hz)=1.8_{-1.3}^{+2.7}×10^{-9} with 90% confidence, compared with Ω_{GW}(f=25  Hz)=1.1_{-0.7}^{+1.2}×10^{-9} from binary black holes alone. Assuming the most probable rate for compact binary mergers, we find that the total background may be detectable with a signal-to-noise-ratio of 3 after 40 months of total observation time, based on the expected timeline for Advanced LIGO and Virgo to reach their design sensitivity.

First Search for Nontensorial Gravitational Waves from Known Pulsars

We present results from the first directed search for nontensorial gravitational waves. While general relativity allows for tensorial (plus and cross) modes only, a generic metric theory may, in principle, predict waves with up to six different polarizations. This analysis is sensitive to continuous signals of scalar, vector, or tensor polarizations, and does not rely on any specific theory of gravity. After searching data from the first observation run of the advanced LIGO detectors for signals at twice the rotational frequency of 200 known pulsars, we find no evidence of gravitational waves of any polarization. We report the first upper limits for scalar and vector strains, finding values comparable in magnitude to previously published limits for tensor strain. Our results may be translated into constraints on specific alternative theories of gravity.

Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

We present possible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron star systems, which are the most promising targets for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and [Formula: see text] credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5-[Formula: see text] requires at least three detectors of sensitivity within a factor of [Formula: see text] of each other and with a broad frequency bandwidth. When all detectors, including KAGRA and the third LIGO detector in India, reach design sensitivity, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.

Effects of transients in LIGO suspensions on searches for gravitational waves

This paper presents an analysis of the transient behavior of the Advanced LIGO (Laser Interferometer Gravitational-wave Observatory) suspensions used to seismically isolate the optics. We have characterized the transients in the longitudinal motion of the quadruple suspensions during Advanced LIGO's first observing run. Propagation of transients between stages is consistent with modeled transfer functions, such that transient motion originating at the top of the suspension chain is significantly reduced in amplitude at the test mass. We find that there are transients seen by the longitudinal motion monitors of quadruple suspensions, but they are not significantly correlated with transient motion above the noise floor in the gravitational wave strain data, and therefore do not present a dominant source of background noise in the searches for transient gravitational wave signals. Using the suspension transfer functions, we compared the transients in a week of gravitational wave strain data with transients from a quadruple suspension. Of the strain transients between 10 and 60 Hz, 84% are loud enough that they would have appeared above the sensor noise in the top stage quadruple suspension monitors if they had originated at that stage at the same frequencies. We find no significant temporal correlation with the suspension transients in that stage, so we can rule out suspension motion originating at the top stage as the cause of those transients. However, only 3.2% of the gravitational wave strain transients are loud enough that they would have been seen by the second stage suspension sensors, and none of them are above the sensor noise levels of the penultimate stage. Therefore, we cannot eliminate the possibility of transient noise in the detectors originating in the intermediate stages of the suspension below the sensing noise.

Should Student Evaluation of Teaching Play a Significant Role in the Formal Assessment of Dental Faculty? Two Viewpoints: Viewpoint 1: Formal Faculty Assessment Should Include Student Evaluation of Teaching and Viewpoint 2: Student Evaluation of Teaching Should Not Be Part of Formal Faculty Assessment

Student evaluation of teaching (SET) is often used in the assessment of faculty members' job performance and promotion and tenure decisions, but debate over this use of student evaluations has centered on the validity, reliability, and application of the data in assessing teaching performance. Additionally, the fear of student criticism has the potential of influencing course content delivery and testing measures. This Point/Counterpoint article reviews the potential utility of and controversy surrounding the use of SETs in the formal assessment of dental school faculty. Viewpoint 1 supports the view that SETs are reliable and should be included in those formal assessments. Proponents of this opinion contend that SETs serve to measure a school's effectiveness in support of its core mission, are valid measures based on feedback from the recipients of educational delivery, and provide formative feedback to improve faculty accountability to the institution. Viewpoint 2 argues that SETs should not be used for promotion and tenure decisions, asserting that higher SET ratings do not correlate with improved student learning. The advocates of this viewpoint contend that faculty members may be influenced to focus on student satisfaction rather than pedagogy, resulting in grade inflation. They also argue that SETs are prone to gender and racial biases and that SET results are frequently misinterpreted by administrators. Low response rates and monotonic response patterns are other factors that compromise the reliability of SETs.

GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral

On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4}  years. We infer the component masses of the binary to be between 0.86 and 2.26  M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60  M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28  deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8}  Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.

GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence

On August 14, 2017 at 10∶30:43 UTC, the Advanced Virgo detector and the two Advanced LIGO detectors coherently observed a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes, with a false-alarm rate of ≲1 in 27 000 years. The signal was observed with a three-detector network matched-filter signal-to-noise ratio of 18. The inferred masses of the initial black holes are 30.5_{-3.0}^{+5.7}M_{⊙} and 25.3_{-4.2}^{+2.8}M_{⊙} (at the 90% credible level). The luminosity distance of the source is 540_{-210}^{+130}  Mpc, corresponding to a redshift of z=0.11_{-0.04}^{+0.03}. A network of three detectors improves the sky localization of the source, reducing the area of the 90% credible region from 1160   deg^{2} using only the two LIGO detectors to 60  deg^{2} using all three detectors. For the first time, we can test the nature of gravitational-wave polarizations from the antenna response of the LIGO-Virgo network, thus enabling a new class of phenomenological tests of gravity.

GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2

We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10∶11:58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70 000 years. The inferred component black hole masses are 31.2_{-6.0}^{+8.4}M_{⊙} and 19.4_{-5.9}^{+5.3}M_{⊙} (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, χ_{eff}=-0.12_{-0.30}^{+0.21}. This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is 880_{-390}^{+450}  Mpc corresponding to a redshift of z=0.18_{-0.07}^{+0.08}. We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to m_{g}≤7.7×10^{-23}  eV/c^{2}. In all cases, we find that GW170104 is consistent with general relativity.

First Demonstration of Electrostatic Damping of Parametric Instability at Advanced LIGO

Interferometric gravitational wave detectors operate with high optical power in their arms in order to achieve high shot-noise limited strain sensitivity. A significant limitation to increasing the optical power is the phenomenon of three-mode parametric instabilities, in which the laser field in the arm cavities is scattered into higher-order optical modes by acoustic modes of the cavity mirrors. The optical modes can further drive the acoustic modes via radiation pressure, potentially producing an exponential buildup. One proposed technique to stabilize parametric instability is active damping of acoustic modes. We report here the first demonstration of damping a parametrically unstable mode using active feedback forces on the cavity mirror. A 15 538 Hz mode that grew exponentially with a time constant of 182 sec was damped using electrostatic actuation, with a resulting decay time constant of 23 sec. An average control force of 0.03 nN was required to maintain the acoustic mode at its minimum amplitude.

Upper Limits on the Stochastic Gravitational-Wave Background from Advanced LIGO's First Observing Run

A wide variety of astrophysical and cosmological sources are expected to contribute to a stochastic gravitational-wave background. Following the observations of GW150914 and GW151226, the rate and mass of coalescing binary black holes appear to be greater than many previous expectations. As a result, the stochastic background from unresolved compact binary coalescences is expected to be particularly loud. We perform a search for the isotropic stochastic gravitational-wave background using data from Advanced Laser Interferometer Gravitational Wave Observatory's (aLIGO) first observing run. The data display no evidence of a stochastic gravitational-wave signal. We constrain the dimensionless energy density of gravitational waves to be Ω_{0}<1.7×10^{-7} with 95% confidence, assuming a flat energy density spectrum in the most sensitive part of the LIGO band (20-86 Hz). This is a factor of ∼33 times more sensitive than previous measurements. We also constrain arbitrary power-law spectra. Finally, we investigate the implications of this search for the background of binary black holes using an astrophysical model for the background.

Directional Limits on Persistent Gravitational Waves from Advanced LIGO's First Observing Run

We employ gravitational-wave radiometry to map the stochastic gravitational wave background expected from a variety of contributing mechanisms and test the assumption of isotropy using data from the Advanced Laser Interferometer Gravitational Wave Observatory's (aLIGO) first observing run. We also search for persistent gravitational waves from point sources with only minimal assumptions over the 20-1726 Hz frequency band. Finding no evidence of gravitational waves from either point sources or a stochastic background, we set limits at 90% confidence. For broadband point sources, we report upper limits on the gravitational wave energy flux per unit frequency in the range F_{α,Θ}(f)<(0.1-56)×10^{-8}    erg cm^{-2} s^{-1} Hz^{-1}(f/25  Hz)^{α-1} depending on the sky location Θ and the spectral power index α. For extended sources, we report upper limits on the fractional gravitational wave energy density required to close the Universe of Ω(f,Θ)<(0.39-7.6)×10^{-8}  sr^{-1}(f/25  Hz)^{α} depending on Θ and α. Directed searches for narrowband gravitational waves from astrophysically interesting objects (Scorpius X-1, Supernova 1987 A, and the Galactic Center) yield median frequency-dependent limits on strain amplitude of h_{0}<(6.7,5.5,  and  7.0)×10^{-25}, respectively, at the most sensitive detector frequencies between 130-175 Hz. This represents a mean improvement of a factor of 2 across the band compared to previous searches of this kind for these sky locations, considering the different quantities of strain constrained in each case.

Determination of the refractive index and thickness of a hydroxide-catalysis bond between fused silica from reflectivity measurements

Hydroxide-catalysis bonding is a high precision jointing technique producing strong, transparent and thin bonds, the use of which in the delicate fused silica mirror suspensions of aLIGO have been instrumental in the first detections of gravitational radiation. More sensitive future gravitational wave detectors will require more accurate (ideally in situ) measurements of properties such as bond thickness. Here a non-destructive technique is presented in which the thickness and refractive index of a bond are determined from measurements of optical reflectivity. The reflectivity of a bond made between two fused silica discs using sodium silicate solution is less than 1⋅10^-3 after 3 months. The thickness decreases to a constant value of around 140 nm at its minimum and the refractive index increases from 1.36 to 1.45. This proves that as well as determination of bond thickness in situ this bonding technique is highly interesting for optical applications.

Characterization of transient noise in Advanced LIGO relevant to gravitational wave signal GW150914

On September 14, 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.

GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4_{-0.9}^{+0.7}×10^{-22}. The inferred source-frame initial black hole masses are 14.2_{-3.7}^{+8.3}M_{⊙} and 7.5_{-2.3}^{+2.3}M_{⊙}, and the final black hole mass is 20.8_{-1.7}^{+6.1}M_{⊙}. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440_{-190}^{+180}  Mpc corresponding to a redshift of 0.09_{-0.04}^{+0.03}. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.