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.

Phonons, phase transitions and thermal expansion in LiAlO2: an ab initio density functional study

We have used the ab initio density functional theory technique to understand the phase transitions and structural changes in various high temperature/pressure phases of LiAlO₂. The electronic band structure as well as phonon spectra is calculated for various phases as a function of pressure. The phonon entropy used for the calculations of Gibbs free energy is found to play an important role in the phase stability and phase transitions among various phases. A sudden increase in the polyhedral bond lengths (Li/Al-O) signifies the change from the tetrahedral to octahedral geometry at high-pressure phase transitions. The activation energy barrier for the high-pressure phase transitions is calculated. The phonon modes responsible for the phase transition (upon heating) from high pressure phases to ambient pressure phases are identified. Moreover, ab initio lattice dynamics calculations in the framework of quasi-harmonic approximations are used to study the anisotropic thermal expansion behavior of γ-LiAlO₂.

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.

Is amalgamated ligno-bupivacaine an answer to complicated minor oral surgical anesthesia? A randomized split-mouth double-blind clinical trial

PURPOSE

The purpose of this study was to find a suitable anesthetic combination for complicated and protracted minor oral surgical procedures.

METHODS

Fifty patients with bilaterally impacted deep-seated mandibular third molars were included in this study and randomly divided on the basis of anesthetic used into two groups. Group A received 2% lignocaine with 1:200,000 adrenaline while in group B, amalgamated mixture of 2% lignocaine and 0.5% bupivacaine was used. The onset time, duration of anesthetic effect, supplementary injections, pain (during local anesthetic deposition, intra and postoperatively), and postoperative analgesia were the study parameters. Chi-square and unpaired t tests were used to compare means.

RESULTS

The onset time in both the groups was comparable and showed statistically significant difference between the duration of anesthetic effect with notable requirement of supplemental anesthetic injections in group A (54%) (p < 0.05). Pain scores also revealed a statistically significant intergroup difference (p < 0.05). Requirement of postoperative analgesics was delayed in group B.

CONCLUSIONS

The amalgamated mixture of lignocaine and bupivacaine had equivocally rational onset and provided a more profound and in-depth anesthesia especially in complicated and protracted minor oral surgical procedures. Though this mixture is widely used in other surgical fields, its efficacy still remains unexploited and undocumented in oral and maxillofacial surgical procedures.

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.

A prospective randomized trial comparing capecitabine-based chemoradiotherapy with 5-FU-based chemoradiotherapy in neoadjuvant setting in locally advanced carcinoma rectum

INTRODUCTION

Fluorouracil (FU)based chemoradiotherapy is regarded as a standard perioperative treatment in locally advanced rectal cancer. Capecitabine is an oral fluoropyrimidine that generates 5FU preferentially at the tumor site by exploiting the higher activity of the enzyme thymidine phosphorylase in tumor tissue compared with healthy tissue. As an oral agent, capecitabine can be administered in the outpatient setting, potentially providing FU exposure similar to a lowdose continuous infusion of 5FU.

AIMS AND OBJECTIVES

To compare capecitabine with 5FU, with regard to efficacy and toxicity when used in neoadjuvant setting along with radiotherapy for locally advanced carcinoma rectum.

MATERIALS AND METHODS

Thirty patients were enrolled, 14 in 5FU and 16 in capecitabine arm. All patients were planned for 45 Gy/25#/5 weeks pelvic radiotherapy followed by a boost of 5.4 Gy/3#/3 days. 5FU was prescribed at a dose of 500 mg/m2 #1-#5 and #21-#25 of RT and capecitabine was given at 1650 mg/m2 on RT days throughout the course of radiotherapy. A magnetic resonance imaging/computerized tomography scan was done at the start of treatment and 1 month after completion of treatment, followed by surgery. Toxicity was assessed weekly during treatment and on the first followup.

RESULTS

Response rates and toxicity profile of capecitabinebased cathode ray tube (CRT) was similar to 5FUbased CRT with nonsignificant P values.

CONCLUSION

Capecitabine may be used as an alternative in patients who do not tolerate 5FU.

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.

Divergent effects of glucose and fructose on hepatic lipogenesis and insulin signaling

Overconsumption of high-fat diet (HFD) and sugar-sweetened beverages are risk factors for developing obesity, insulin resistance, and fatty liver disease. Here we have dissected mechanisms underlying this association using mice fed either chow or HFD with or without fructose- or glucose-supplemented water. In chow-fed mice, there was no major physiological difference between fructose and glucose supplementation. On the other hand, mice on HFD supplemented with fructose developed more pronounced obesity, glucose intolerance, and hepatomegaly as compared to glucose-supplemented HFD mice, despite similar caloric intake. Fructose and glucose supplementation also had distinct effects on expression of the lipogenic transcription factors ChREBP and SREBP1c. While both sugars increased ChREBP-β, fructose supplementation uniquely increased SREBP1c and downstream fatty acid synthesis genes, resulting in reduced liver insulin signaling. In contrast, glucose enhanced total ChREBP expression and triglyceride synthesis but was associated with improved hepatic insulin signaling. Metabolomic and RNA sequence analysis confirmed dichotomous effects of fructose and glucose supplementation on liver metabolism in spite of inducing similar hepatic lipid accumulation. Ketohexokinase, the first enzyme of fructose metabolism, was increased in fructose-fed mice and in obese humans with steatohepatitis. Knockdown of ketohexokinase in liver improved hepatic steatosis and glucose tolerance in fructose-supplemented mice. Thus, fructose is a component of dietary sugar that is distinctively associated with poor metabolic outcomes, whereas increased glucose intake may be protective.

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.

Investigating anomalous thermal expansion of copper halides by inelastic neutron scattering and ab initio phonon calculations

We investigate the detailed lattice dynamics of copper halides, CuX (X = Cl, Br, and I), using neutron inelastic scattering measurements and ab initio calculations aimed at a comparative study of their thermal expansion behavior. We identify the low energy phonons which soften with pressure and are responsible for negative thermal expansion. The eigenvector analysis of these modes suggests that softening of the transverse-acoustic modes would lead to NTE in these compounds. The calculations are in very good agreement with our measurements of phonon spectra and thermal expansion behavior as reported in the literature. Our calculations at high pressure further reveal that a large difference in negative thermal expansion behavior in these compounds is associated with the difference in the unit cell volume.

Normal Tissue Complications following Hypofractionated Chest Wall Radiotherapy in Breast Cancer Patients and Their Correlation with Patient, Tumor, and Treatment Characteristics

INTRODUCTION

Normal tissue complications following chest wall radiotherapy (RT) are inevitable, and the long-term data on hypofractionation are still limited. To quantify the late effects of hypofractionated RT on cardiac, pulmonary, brachial plexus, and regional lymphatics and their correlation with patient, tumor, and treatment characteristics is the main objective of this study.

MATERIALS AND METHODS

Two hundred and sixteen breast cancer patients following mastectomy were treated with hypofractionated schedules either 40 Gy in 15 fractions or 42.5 Gy in 16 fractions. Common Toxicity Criteria version 3.0 was utilized to quantify the late effects of hypofractionation on cardiac, pulmonary, brachial plexus, and lymphedema at a maximum follow-up of 5 years.

RESULTS

Median follow-up was 42 months. Median age was 49 years. 14.8% developed ≥Grade (Gr) 2 late cardiac toxicity. 10.2% developed ≥Gr2 late pulmonary toxicity. There were 28.7% patients who developed ≥Gr2 lymphedema. Sixty-seven out of 216 patients had symptomatic brachial plexopathy at 5-year follow-up. Variables found to increase the incidence of these adverse events included smoking, hypertension, diabetes mellitus, body mass index ≥25, extent of axillary dissection, and use of supraclavicular field.

CONCLUSION

Hypofractionation leads to increased risk of normal tissue complications partly influenced by some patient- and treatment-related factors, but these were manageable and minimally disabling.

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.

Computerized Axial Tomography Findings in Children with Afebrile Seizures: A Hospital Based Study at Eastern Nepal

BACKGROUND

Computerized Tomography can be performed in resource limited areas where Magnetic Resonance Imaging is less practical. This study was conducted to find out the proportion of cases with abnormal CT scan and findings of CT scan in children with afebrile seizures in a resource limited area.

METHODS

This prospective study was conducted from 1st July 2009 to 31st March 2014 in a university hospital of Nepal. Patients (1 month to 20 years of age) presenting with history of afebrile seizure were included. Neuroimaging was prescribed; children were treated and followed-up as per standard guideline. Data were analyzed using SPSS 16.0.

RESULTS

There were 447 children with afebrile seizures included in the study. Male to female ratio was 1.6:1. Median age at presentation was 84 (interquartile range 36-144) months. CT scan was done in 321 (71.8%) cases. CT was abnormal in 143 cases, accounting for 32.0% out of total cases and 44.5% out of investigated cases. Among investigated cases, common CT findings were atrophy (13.4%), neurocysticercosis (12.1%), structural abnormalities (4.4%), stroke (3.7%), post-encephalitis changes (3.1%), nonspecific calcification (1.6%), tuberculoma (1.2%), tumor (0.9%), neurocutaneous syndromes (0.9%), hydrocephalus (0.9%) and other findings (2.2%).

CONCLUSIONS

In a resource limited area CT scan is a valuable alternative tool in evaluating a child with afebrile seizure. Majority of these children have remote symptomatic seizures and the underlying brain pathologies can be well detected by CT scan.

Clinico-anesthetic changes following administration of propofol alone and in combination of meperidine and pentazocine lactate in dogs

Aim:

The aim of this study is to find out the effect of propofol and its combination with meperidine and pentazocine lactate on certain clinico-anesthetic profiles in dogs.

Materials and Methods:

15 apparently healthy mongrel dogs of either sex of about 1 year of age were randomly divided into three groups of five dogs each. The animals of Group I were administered propofol intravenously alone “to effect,” whereas meperidine at 2 mg/kgb.wt. and pentazocine lactate at 2 mg/kg b.wt. were injected intramuscularly 15 min before propofol “to effect” in Groups II and III, respectively. Atropine sulfate at 0.04 mg/kgb.wt. was injected intramuscularly 20 min before each treatment. Rectal temperature, heart rate, respiration rate, and anesthetic indices were recorded before and at 5, 10, 20, 30, and 60 min of induction.

Results:

As compared to Group I, the animals of Groups II and III exhibited a significant decrease (p<0.05) in the level of rectal temperature, respiration rate, and heart rate. Duration of recumbency, time of standing, time of recovery as well as the duration of analgesia were longer in pentazocine lactate (Group III) followed by meperidine (Group II) as compared to propofol alone (Group I). Meperidine treated dogs showed defecation and muscle twitching during anesthesia.

Conclusion:

Meperidine and pentazocine are suitable opioids used in combination with propofol for achieving surgical anesthesia and helpful in reduction of propofol dose.

Immediate versus delayed aggressive physical therapy following buccal fat pad interposition in oral submucous fibrosis-a prospective study in Central India

PURPOSE

Oral submucous fibrosis is a disease of an Indian subcontinent with obscure aetiology and poorly treated with varying signs and symptoms. OSMF occurs at any age but is most commonly seen in teenagers and adults in the age ranging between 16 and 35 years. A number of surgical treatments have been used for the treatment of oral submucous fibrosis with unpredictable results.

PATIENTS AND METHOD

In this study, 220 patients were randomly divided into two groups with mouth opening less than 16 mm and evaluated with immediate and delayed aggressive physiotherapy with buccal fat pad interposition after fibrotomy. Group A (n = 110) patients underwent aggressive mouth opening exercise from the next postoperative day while in group B (n = 110), patients underwent physiotherapy 7th day postoperatively. Pain and discomfort, mucosalization, infection, flap dehiscence and necrosis were noted. Patients were followed for 1 year on a regular interval basis.

RESULTS

At the end of 1-year follow up, the post-operative mean mouth opening in group A was 38.63 mm and 34.19 mm in group B. In group A, the immediate physiotherapy results in mild to moderate pain and discomfort to the patients as compared to no apparent pain in the group B. The mean mucosalization time in group A and group B was 4.2 and 5.1 weeks, respectively. Postoperatively, all patients achieve satisfactory mouth opening.

CONCLUSION

Immediate aggressive physiotherapy yields a comparatively superior result than delayed physiotherapy with respect to mouth opening in 1 year of follow-up.

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.

Properties of the Binary Black Hole Merger GW150914

On September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected a gravitational-wave transient (GW150914); we characterize the properties of the source and its parameters. The data around the time of the event were analyzed coherently across the LIGO network using a suite of accurate waveform models that describe gravitational waves from a compact binary system in general relativity. GW150914 was produced by a nearly equal mass binary black hole of masses 36_{-4}^{+5}M_{⊙} and 29_{-4}^{+4}M_{⊙}; for each parameter we report the median value and the range of the 90% credible interval. The dimensionless spin magnitude of the more massive black hole is bound to be <0.7 (at 90% probability). The luminosity distance to the source is 410_{-180}^{+160}  Mpc, corresponding to a redshift 0.09_{-0.04}^{+0.03} assuming standard cosmology. The source location is constrained to an annulus section of 610  deg^{2}, primarily in the southern hemisphere. The binary merges into a black hole of mass 62_{-4}^{+4}M_{⊙} and spin 0.67_{-0.07}^{+0.05}. This black hole is significantly more massive than any other inferred from electromagnetic observations in the stellar-mass regime.