Point Absorber Limits to Future Gravitational-Wave Detectors.

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.

Modeling circulating cavity fields using the discrete linear canonical transform.

Fabry-Perot cavities are central to many optical measurement systems. In high-precision experiments, such as aLIGO and AdVirgo, coupled cavities are often required, leading to complex optical behavior. We show, for the first time to our knowledge, that discrete linear canonical transforms (LCTs) can be used to compute circulating optical fields for cavities in which the optics have arbitrary apertures, reflectance and transmittance profiles, and shape. We compare the predictions of LCT models with those of alternative methods. To further highlight the utility of the LCT, we present a case study of point absorbers on the aLIGO mirrors and compare it with recently published results.

Mode matching error signals using radio-frequency beam shape modulation.

Precise mode matching is needed to maximize performance in coupled cavity interferometers such as Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO). In this paper, we present a new mode matching sensing scheme, to the best of our knowledge, that uses a single radio-frequency higher-order-mode sideband and single-element photodiodes. It is first-order insensitive to misalignment and can serve as an error signal in a closed loop control system for a set of mode matching actuators. We also discuss how it may be implemented in Advanced LIGO. The proposed mode matching error signal has been successfully demonstrated on a tabletop experiment, where the error signal increased the mode matching of a beam to a cavity to 99.9%.

Quantum-Enhanced Advanced LIGO Detectors in the Era of Gravitational-Wave Astronomy.

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).

Approaching the motional ground state of a 10-kg object.

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.

Effect of leg length on ROM, VJ and leg dexterity in dance.

We investigated the associations between leg length and specific ballet movements in different skill groups. Volunteers were from an undergraduate dance programme (n=18), a pre-professional school (n=43) and from an elite classical ballet company (n=45). Individual data were collected for anthropometry, vertical jump, leg dexterity, and leg active and passive ROM. ANCOVA identified both main effects as significant with regard to vertical jump (gender P<0.001 and skill P=0.017); leg length was also identified as a significant covariate (P=0.023). Analysis of leg dexterity identified no significant effects with gender, skill or leg length. Active and passive range of motion noted gender (P=0.001) and skill (P<0.001) differences. Leg length was found to be negatively associated with both active and passive ROM (P=0.002). In conclusion, the present data highlight the diverse and conflicting effects of leg length on fundamental ballet skills. The longer legs that benefit vertical jump have a negative influence on range of motion and leg dexterity except for highly skilled dancers, who through skill, seem to have overcome the effects of some of these dichotomies.

Two forms of elongation factor 1 alpha (EF-1 alpha O and 42Sp50), present in oocytes, but absent in somatic cells of Xenopus laevis.

We have purified and partially sequenced the EF-1 alpha protein from Xenopus laevis oocytes (EF-1 alpha O). We show that the two cDNA clones isolated by Coppared et al. (Coppard, N. J., K. Poulsen, H. O. Madsen, J. Frydenberg, and B. F. C. Clark. 1991. J. Cell Biol. 112:237-243) do not encode 42Sp50, as claimed by these authors, but two very similar forms of EF-1 alpha O (EF-1 alpha O and EF-1 alpha O1). 42Sp50 is the major protein component of a 42S nucleoprotein particle that is very abundant in previtellogenic oocytes of X. laevis, 42Sp50 differs from EF-1 alpha O not only by its amino acid sequence, but also by several properties already reported. In particular, 42Sp50 has a low EF-1 alpha activity. It is distributed uniformly in the cytoplasm of previtellogenic oocytes, in contrast to EF-1 alpha O which is concentrated in a small region of the cytoplasm, known as the mitochondrial mass or Balbiani body.

Gene expression in eukaryotes.

Gene expression in eukaryotes is influenced by a wide variety of mechanisms including the loss, amplification, and rearrangement of genes. Genes are differentially transcribed, and the RNA transcripts are variably utilized. Multigene families regulate the amount, the diversity, and the timing of gene expression. The present level of understanding of gene expression in eukaryotes is attributable mainly to biochemical methods rather than to traditional genetics. The new techniques that permit analysis and modification of purified genes of known function will identify both the control regions in eukaryotic genes as well as the molecules within cell that influence gene expression.

Developmental regulation of two 5S ribosomal RNA genes.

The developmental regulation of two kinds of Xenopus 5S RNA genes (oocyte and somatic types) can be explained by differences in the stability of protein-protein and protein-DNA interactions in a transcription complex that directs transcription initiation by RNA polymerase III. Dissociation of transcription factors from oocyte 5S RNA genes during development allows them to be repressed by chromatin assembly. In the same cells, somatic 5S RNA genes remain active because their transcription complexes are stable.

Asymmetric growth and development of the Xenopus laevis retina during metamorphosis is controlled by type III deiodinase.

During the metamorphosis of the Xenopus laevis retina, thyroid hormone (TH) preferentially induces ventral ciliary marginal zone (CMZ) cells to both increase their proliferation and give rise to ipsilaterally projecting ganglion cells. Here we show that dorsal CMZ cells express type III deiodinase (D3), an enzyme that inactivates TH. The dorsal CMZ cells can be induced to proliferate if deiodinase activity is inhibited. D3 or dominant-negative thyroid hormone receptor transgenes inhibit both TH-induced proliferation of the ventral CMZ cells and the formation of the ipsilateral projection. Thus, the localized expression of D3 in the dorsal CMZ cells accounts for the asymmetric growth of the frog retina.

Mapping functional regions of transcription factor TFIIIA.

Functional deletion mutants of the trans-acting factor TFIIIA, truncated at both ends of the molecule, have been expressed by in vitro transcription of a cDNA clone and subsequent cell-free translation of the synthetic mRNAs. A region of TFIIIA 19 amino acids or less, near the carboxyl terminus, is critical for maximal transcription and lies outside the DNA-binding domain. The elongated protein can be aligned over the internal control region (ICR) of the Xenopus 5S RNA gene with its carboxyl terminus oriented toward the 5' end of the gene and its amino terminus oriented toward the 3' end of the gene. The nine "zinc fingers" and the linkers that separate them comprise 80% of the protein mass and correspond to the DNA-binding domain of TFIIIA. The zinc fingers near the amino terminus of the protein contribute more to the overall binding energy of the protein to the ICR than do the zinc fingers near the carboxyl end. The most striking feature of TFIIIA is its modular structure. This is demonstrated by the fact that each zinc finger binds to just one of three short nucleotide sequences within the ICR.

A new rhythm library for testing automatic external defibrillators: performance of three devices.

A library of arrhythmias obtained from patients with cardiac arrest was developed. Such a data base will permit both in vitro testing of the rhythm analysis system of automatic external defibrillators before clinical field trials are conducted and comparison of devices. Defibrillators equipped with voice/electrocardiographic tape recorders and used in the prehospital defibrillation programs in Iowa and King County, Washington provided the rhythm source. From these recordings, segments of ventricular fibrillation with minimal artifact and a duration of greater than or equal to 6 s were selected. Segments of ventricular fibrillation (n = 102) were categorized by average peak amplitude as fine (1 to less than 3 mm), medium (3 to less than 7 mm), coarse (7 to less than 12 mm) and extra coarse (greater than or equal to 12 mm), and transcribed onto high fidelity videocassette tapes. Nonventricular fibrillation cardiac arrest rhythms (n = 144), which included wide complex idioventricular rhythms, ventricular and supraventricular tachycardias, asystole and artifact, were also transcribed. Automatic external defibrillators developed by three manufacturers reached a treat (shock) decision on 88 to 93% of the ventricular fibrillation rhythms and on 5 to 10% of the nonventricular fibrillation rhythms. The latter decisions were defined as false positive, though for many rapid nonventricular fibrillation rhythms, countershock may be the appropriate treatment response. There were no statistically significant differences among the three devices in the shock/no shock decisions. A variety of ventricular fibrillation arrhythmias and terminology to express the preclinical performance of automatic external defibrillators are defined. Three commercially available automatic external defibrillators appear to successfully identify ventricular fibrillation and nonventricular fibrillation rhythms.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro and in vivo analysis of the regulation of a transcription factor gene by thyroid hormone during Xenopus laevis metamorphosis.

A novel, basic region leucine zipper transcription factor (TH/bZIP) is dramatically up-regulated at the climax of metamorphosis in Xenopus laevis. It can be induced in tadpoles prematurely by thyroid hormone (TH) with kinetics that are intermediate between early and late Xenopus TH response genes. A small amount of early, cycloheximide-resistant up-regulation is observed, but the majority of TH/ bZIP mRNA accumulation occurs after 12 h of treatment in parallel with late response gene induction. There are two genomic TH/bZIP genes in the pseudotetraploid X. laevis genome that are coordinately regulated. They have highly conserved regulatory regions that contain two conserved, adjoining DR+4 thyroid response elements (TRE) in opposite orientation. The early/late TH induction kinetics has been reproduced in transient transfection assays. The secondary rise of transcriptional activity requires DNA regions other than the TREs and, therefore, the interaction of transcription factors other than the TH receptors. Finally, the regulatory region of the TH/bZIP gene has been used to drive green fluorescent protein in transgenic X. laevis tadpoles. Regulation of the transgene during spontaneous and induced metamorphosis mimics that of the endogenous TH/bZIP gene. The newly developed X. laevis transgenesis method has distinct advantages for the analysis of transcriptional regulatory elements over transient transfection assays and will be useful for further in vivo studies of TH-response gene regulation during development.

Enhanced auscultation with a new graphic display system.

BACKGROUND: To provide an objective method to support and teach auscultation, a new portable system (graphic display system) was evaluated for graphic display and printing of heart sounds. METHODS: Ninety-one patients from three institutions, with a variety of heart sound abnormalities, were studied by two examiners. A graphic recording was made in each and compared with the auscultatory findings. RESULTS: The findings of the graphic system confirmed the auscultatory impressions of both examiners in 77 (85%) of the 91 cases. Brief sound transients, such as split second sounds and ejection sounds, third heart sounds, and prosthetic opening and closing sounds, were all regularly recorded with the graphic system, often allowing resolution when examiners were in disagreement. Graphic recordings commonly were at variance with examiners in detecting fourth sounds, possibly because of examiners' difficulty in distinguishing these from split first sounds as well as limitations of the graphic system itself. High-pitched murmurs of low intensity (< grade 2), as exemplified by those of aortic and mitral regurgitation, were occasionally missed by the graphic system, probably because of baseline interference by background noise. CONCLUSIONS: The graphic display system can often provide more information than can be obtained by standard auscultation alone, especially in the detection of low-frequency and multiple sounds, and in the accurate timing of intervals. It is often unable to detect soft high-frequency murmurs. Permanent records allow for more objective comparison of the auscultatory findings of various examiners at different times. This system provides an excellent means by which auscultation skills may be taught or enhanced, especially since its speed and portability allow immediate feedback for comparison with auditory perceptions.

Combined Increases in Muscle-Strengthening Activity Frequency and Protein Intake Reveal Graded Relationship with Fat-Free Mass Percentage in U.S. Adults, NHANES (1999-2004).

BACKGROUND: Age-related loss of muscle mass and related ailments are of concern due to associations with disabilities and morbidity as well as constituting a substantial healthcare burden. Muscle-strengthening activities and adequate protein ingestion are recommended for all-age adults in an effort to stave off age-related muscle atrophy. Muscle building abilities decline with age but most research focuses on muscle wasting in the elderly. OBJECTIVES: To examine the independent and combined associations of protein intake (g∙kg-1∙day-1) and muscle-strengthening frequency (times∙week-1, MSF) on fat-free mass percentage (FFM%). DESIGN SETTING AND PARTICIPANTS: This cross-sectional analysis of a population-based sample with data from the non-institutionalized persons in the United States participating in the National Health and Nutrition Examination Survey (cycles 1999-2000, 2001-2002, 2003-2004) consisted of male (n=2,499) and female (n=2,373) participants 20-49 years of age for analyses. MEASUREMENTS: MSF was determined by self-report and protein intake was calculated from a 24-hour recall. Differences in FFM% from bioelectrical impedance analysis was estimated using multiple linear regression models controlling for education, race-ethnicity, standing height, and total Caloric intake. RESULTS: One unit increase in MSF or protein intake (ß-coefficient, ±E) was associated with significantly more FFM% in males (0.6±0.1%; 3.5±0.4%) and females (0.4±0.1%; 5.9±0.4%). Independent of protein intake, males and females with MSF=0 had mean ±SE FFM% of 74.4±0.4 and 60.7±0.3, respectively, while mean ±SE FFM% of males and females who met the recommendation of ≥2 times per week were 77.9±0.5 and 63.0±0.4. Independent of MSF, males and females with protein intakes below the recommended dietary allowance (RDA) of 0.8 g∙kg-1∙day-1 had mean ±SE FFM% of 74.0±0.6 and 58.2±0.6, respectively, while mean ±SE FFM% of those whose intakes exceeded the recommendation were 75.6±0.4 and 62.0±0.4. The subgroup with the highest mean ±SE FFM% (80.9 ±0.73) comprised males with MSF ≥2 times per week who also consumed >1.4 g∙kg-1∙day-1. CONCLUSION: The MSF-protein intake dose relationship with FFM% suggests that performing muscle-strengthening activities >2 times per week while consuming protein above the RDA may result in more fat-free mass and slow age-related losses of muscle mass.

Effect of furosemide on the renal excretion of digoxin.

Digoxin serum and urine levels were determined by radioimmunoassay in 6 subjects (4 patients with heart disease and 2 volunteers without heart disease) who had been maintained on oral digoxin (0.25 or 0.5 mg daily). Observations were made during a 3-day control period and then during 8 days of concomitant digoxin and oral furosemide (40 mg daily) therapy. Serum digoxin levels determined 10 and 24 hr after each dose of digoxin averaged 1.2+/-0.1 ng/ml (M+/-SE) during control and 1.3+/-0.1 during the last 3 days on digoxin and furosemide. The daily urinary excretion of digoxine averaged 51+/-6% of the oral dose during control and 52+/-6 during the entire period of furosemide administration. The renal clearance of digoxin and creatinine averaged 94+/-7 and 87+/-11 ml/min, respectively, during control; corresponding values were 88+/-8 and 85+/-9 for urine collections demonstrating a distinct diuretic effect of furosemide and 87+/-8 and 75+/-10 for urine collections not demonstrating such an effect during diuretic therapy. The results suggest that the diuretic effect of furosemide does not significantly affect the excretion of digoxin

Effect of sulfasalazine on digoxin bioavailability.

Low levels of digoxin were noted in a patient receiving digoxin and sulfasalazine (SSA). Discontinuation of SSA resulted in a significant increase in serum digoxin levels. To determine whether or not SSA consistently interfered with the therapeutic effect of digoxin, both drugs were administered to 10 normal subjects in a crossover study. Each received 2 doses of digoxin (0.5 mg, elixir): one dose given alone, and a second dose after 6 days of treatment with SSA. When digoxin was given with SSA, the average area under the serum digoxin curve fell from the control value of 8.79 ng-hr-ml(-1) to 6.66 ng-hr-ml(-1) (p less than 0.05), fell and total urinary excretion decreased from 278 mcg/10 days to 228 mcg/10 days (p less than 0.025). These changes suggest interference with the bioavailability of digoxin by SSA. Studies were conducted to determine whether SSA inhibited digoxin absorption by physically absorbing the glycoside from solution. In vitro tests failed to reveal any significant adsorptive properties for SSA.

Truncated exponential versus damped sinusoidal waveform shocks for transthoracic defibrillation.

Currently available transthoracic defibrillators use either a damped sinusoidal or truncated exponential (TE) waveform. Truncated exponential waveforms deliver a long pulse if the transthoracic impedance is high; it has been suggested that such a long pulse may be less effective for defibrillation. Our objective was to compare the ability of damped sinusoidal (DS) waveform shocks versus TE waveform shocks to terminate ventricular fibrillation (VF) and achieve survival from witnessed cardiac arrest. We retrospectively reviewed field-recorded electrocardiograms from 86 patients with witnessed VF, treated by prehospital personnel equipped with DS or TE waveform defibrillators. Forty-four patients received 130 shocks from TE defibrillators; 42 patients received 108 shocks from DS defibrillators. There were no significant differences in time from arrest to first shock (8.0 vs 8.1 minutes), nor were there any differences in the size of the communities involved. The shocks resulted in the following rhythms: organized rhythm: TE: 15 of 130 (12%), DS: 24 of 108 (22%), p = 0.10 (NS); persistent VF: TE: 85 of 130 (65%), DS: 45 of 108 (42%), p <0.01; asystole: TE: 30 of 130 (23%), DS: 39 of 108 (36%), p = NS; and survival to hospital discharge: TE: 5 of 44 (11%), DS: 8 of 42 (19%), p = NS. We conclude that DS waveforms terminated VF more frequently than TE, but there was no significant difference in resumption of an organized rhythm or survival. A prospective comparison of these 2 waveforms is needed.

Model ecosystem evaluation of the environmental impacts of the veterinary drugs phenothiazine, sulfamethazine, clopidol, and diethylstilbestrol.

Four veterinary drugs of dissimilar chemical structures were evaluated for environmental stability and penchant for bioaccumulation. The techniques used were (1) a model aquatic ecosystem (3 days) and (2) a model feedlot ecosystem (33 days) in which the drugs were introduced via the excreta of chicks or mice. The model feedlot ecosystem was supported by metabolism cage studies to determine the amount and the form of the drug excreted by the chicks or mice. Considerable quantities of all the drugs were excreted intact or as environmentally short-lived conjugates. Diethylstilbestrol (DES) and Clopidol were the most persistent molecules, but only DES bioaccumulated to any appreciable degree. Phenothiazine was very biodegradable; sulfamethazine was relatively biodegradable and only accumulated in the organisms to very low levels. Data from the aquatic model ecosystem demonstrated a good correlation between the partition coefficients of the drugs and their accumulation in the fish.