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.

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.

Tests of General Relativity with GW150914

The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion of a compact-object binary in the large-velocity, highly nonlinear regime, and to witness the final merger of the binary and the excitation of uniquely relativistic modes of the gravitational field. We carry out several investigations to determine whether GW150914 is consistent with a binary black-hole merger in general relativity. We find that the final remnant's mass and spin, as determined from the low-frequency (inspiral) and high-frequency (postinspiral) phases of the signal, are mutually consistent with the binary black-hole solution in general relativity. Furthermore, the data following the peak of GW150914 are consistent with the least-damped quasinormal mode inferred from the mass and spin of the remnant black hole. By using waveform models that allow for parametrized general-relativity violations during the inspiral and merger phases, we perform quantitative tests on the gravitational-wave phase in the dynamical regime and we determine the first empirical bounds on several high-order post-Newtonian coefficients. We constrain the graviton Compton wavelength, assuming that gravitons are dispersed in vacuum in the same way as particles with mass, obtaining a 90%-confidence lower bound of 10^{13}  km. In conclusion, within our statistical uncertainties, we find no evidence for violations of general relativity in the genuinely strong-field regime of gravity.

GW150914: Implications for the Stochastic Gravitational-Wave Background from Binary Black Holes

The LIGO detection of the gravitational wave transient GW150914, from the inspiral and merger of two black holes with masses ≳30M_{⊙}, suggests a population of binary black holes with relatively high mass. This observation implies that the stochastic gravitational-wave background from binary black holes, created from the incoherent superposition of all the merging binaries in the Universe, could be higher than previously expected. Using the properties of GW150914, we estimate the energy density of such a background from binary black holes. In the most sensitive part of the Advanced LIGO and Advanced Virgo band for stochastic backgrounds (near 25 Hz), we predict Ω_{GW}(f=25  Hz)=1.1_{-0.9}^{+2.7}×10^{-9} with 90% confidence. This prediction is robustly demonstrated for a variety of formation scenarios with different parameters. The differences between models are small compared to the statistical uncertainty arising from the currently poorly constrained local coalescence rate. We conclude that this background is potentially measurable by the Advanced LIGO and Advanced Virgo detectors operating at their projected final sensitivity.

GW150914: The Advanced LIGO Detectors in the Era of First Discoveries

Following a major upgrade, the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January 2016. With a strain sensitivity of 10^{-23}/sqrt[Hz] at 100 Hz, the product of observable volume and measurement time exceeded that of all previous runs within the first 16 days of coincident observation. On September 14, 2015, the Advanced LIGO detectors observed a transient gravitational-wave signal determined to be the coalescence of two black holes [B. P. Abbott et al., Phys. Rev. Lett. 116, 061102 (2016)], launching the era of gravitational-wave astronomy. The event, GW150914, was observed with a combined signal-to-noise ratio of 24 in coincidence by the two detectors. Here, we present the main features of the detectors that enabled this observation. At full sensitivity, the Advanced LIGO detectors are designed to deliver another factor of 3 improvement in the signal-to-noise ratio for binary black hole systems similar in mass to GW150914.

Observation of Gravitational Waves from a Binary Black Hole Merger

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

EGFR and HER-2/neu Expression in Gallbladder Carcinoma: An Institutional Experience

BACKGROUND

Gallbladder cancer (GBC) is the most common malignancy of the biliary tract in India. Despite the recent advancement in the understanding of the cancer biology, the disease still remains a therapeutic challenge with poor prognosis and low survival. Surgery is the primary modality of treatment and rest of the modalities are basically adjuvant in nature. This study was performed to evaluate the epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor-2 HER-2/neu) expression in GBC.

METHODS

The present study was prospective and done in tertiary super-specialty institute of northern India. This was a pilot study, and at the time of completion, 29 samples were found suitable which were later submitted for EGFR and HER-2/neu evaluation. The sample includes both cases of GBC (n=18) and cholecystitis (n=11) as control. (Table 1) After performing necessary processing, slides were incubated with primary antibody (EGFR) ready to use (RTU) BioGenex, India and HER-2/neu dilution 1:600, Dakopatts (Denmark). Then slides were incubated with secondary antibody (Real Envision Detection Kit, Dakopatts, Denmark). Finally in mounted slides, cell membrane staining was used to assess positivity for EGFR and HER-2/neu.

RESULTS

EGFR was positive in 21/29 (72.41%) overall, out of which 14/18 (77.78%) positive in cases and 7/11 (63.64%) positive in control. (Table 1, 3)(Figure 2). For HER-2/neu, it was positive in 21/29 (72.41%) overall, just like in EGFR mentioned above, but positive 12/18 (66.67%) in cases and 9/11 (81.82%) in control respectively.

CONCLUSION

Despite the efforts by many investigators, GBC continues to represent a major challenge in oncology. Surgical resection remains the only curative treatment for this disease. The roles of radiation, chemoradiation, and chemotherapy in neoadjuvant and adjuvant settings remained to be defined in prospective studies. With further studies based on molecular understanding and developing new targeted therapies, we will be in better position to manage GBC and increase the survival rate.

Assessment of left ventricular function by noninvasive methods

The possibility of evaluating left ventricular function by noninvasive methods is discussed in detail. The methods that are considered are electrocardiograph, phonocardiography, apex cardiography, sphygmography, impedance cardiography, electrokymography, and echocardiography. Following a brief section of 'definitions', each method is described in detail including technical problems, difficulties, and results. The systolic time intervals and the stress tests are briefly discussed. Based on modern experimental studies, the stress test should include both an electro- and a phonocardiogram. In the latter, one would measure the amplitude of the first heart sound as an index of contractility. The conclusion is that combined methods give the best results. They are electrocardiography, phonocardiography, impedance cardiography, and echocardiography. An alternative, dictated by technical problems, is to use at first phonocardiography and impedance plus electrocardiography; then echocardiography plus electrocardiography; and then, if indicated, a stress test might complete the study; the latter should include both an electrocardiogram and a phonocardiogram.

CBCT: a revolutionary diagnostic aid for endodontic dilemmas

Successful management of endodontic problems is reliant on diagnostic imaging techniques to provide critical information about the teeth under investigation, and their surrounding anatomy. Until recently, most of this core information was obtained from conventional radiographs. The introduction of cone-beam computed tomography (CBCT) specifically dedicated to imaging the maxillofacial region heralds a true paradigm shift from a two dimensional (2D) to a three dimensional (3D) approach to data acquisition and image reconstruction. CBCT systems provide small field of view images at low dose with sufficient spatial resolution for applications in endodontic diagnosis, treatment guidance, and post treatment evaluation. CBCT has been the subject of unparalleled levels of independent research in dental imaging in the area of endodontics. It gives the edge of 3D imaging at lower radiation level in comparison to conventional CT and has helped to treat endodontic cases with external resoption, root canal variations and apical periodontitis providing the size, site and extent accurately. This paper reviews the fundamentals of CBCT and presents the applications of this imaging system in contemporary endodontic practice.

Effect of dentin powder on setting time of mineral trioxide aggregate: an in vitro study

AIM

Mineral trioxide aggregate (MTA) is a biomaterial with numerous clinical applications in the field of endodontics. The properties of this material come closest to the requirements of an ideal endodontic repair material. Delayed setting time though may limit the use of MTA in endodontic procedures. Many chemical based additives have influenced the setting time of MTA. The aim of this paper was to evaluate the effect of a natural additive in the form of human dentin powder on setting properties of ProRoot MTA (Dentsply/Tulsa Dental, Tulsa, OK).

METHODS

Thirty extracted human teeth were taken to obtain fine dentin powder. The methodology used to obtain dentin powder for the present study was same as performed by Haapsalo et al. The specimens were divided into two groups. The samples were placed in standardized stainless steel ring moulds. The setting time of MTA alone and in equal proportions with dentin powder as an additive was evaluated using Vicats apparatus.

RESULTS

MTA mixed with dentin powder showed faster setting time (70 minutes) in comparison to MTA without dentin powder (120 minutes) (P<0.5).

CONCLUSION

Although MTA is an ideal retrograde material with increased efficacy due to reduced setting on addition of dentin powder. A combination of MTA with dentin powder might be a viable option in procedures where fast setting of the MTA is critical.

Hospital and Community Isolates of Uropathogens and their Antibiotic Sensitivity Pattern from a Tertiary Care Hospital in North West India

Background:

Urinary tract infection remains one of the most common infections, both in the community and in the hospital. The causative pathogen profile varies from region to region, but Escherichia coli (E. coli) remains the most common causative pathogen. The sensitivity of uropathogens to different drugs varies in different areas, and changes with time. This necessitates periodic studies of the causative uropathogens and their antibiotic sensitivity pattern.

Aim:

To investigate the profile of common uropathogens and assess their antibiotic sensitivity patterns to commonly used antimicrobial agents.

Materials and Methods:

Analysis of all urine specimens submitted for culture and sensitivity was carried out over a 1-year period in a tertiary care hospital in North West India. Urine culture was done by a semi-quantitative method. Antibiotic sensitivity was done on bacterial isolates according to the Clinical and Laboratory Standards Institute CLSI guidelines for disc diffusion susceptibility test. Data was analysed for significance using Chi square test.

Results:

Of a total of 6348 urine specimens received over the 1-year study period, 41.8% (2653) of the urine samples were culture positive. The most common bacterial isolate was E. coli (45.7%, 1103/2412), followed by Coagulase-negative Staphylococci (18.6%, 449/2412) and Klebsiella species (8.3%, 199/2412). The Candida species’ isolation rate was 10.3% (277/2689). The uropathogens displayed a very high level of resistance to fluroquinolones 70.3% (1084/1542)[Inpatient Department (IPD) – 70.5%(572/812), Outpatient Department (OPD) – 70.2%(512/730)] and cephalosporins 75.1%(1158/1542)[IPD – 73.8%(599/812), OPD – 76.6%(559/730)], whereas resistance to nitrofurantoin 19.8%(305/1542) [ IPD – 23.9%, OPD – 15.2%(111/730)], amikacin 32.4%(573/1769) [IPD – 36.1%(235/934), OPD – 28.1%(235/835)] and cephoperazone + sulbactam combination 22%(349/1583) [IPD – 26.2%(244/914), OPD – 15.8%(105/669)] was low.

Conclusion:

Empiric selection of antimicrobial agents should be based on the antibiotic sensitivity pattern of the uropathogens prevalent in that area, which is derived from epidemiological studies carried out in that environment.

Aspergilloma coexisting with idiopathic pulmonary fibrosis: a rare occurrence

Fungal ball (mycetoma/aspergilloma) is a saprophytic fungal infection that colonizes pre-existing lung cavities. Reported literature suggests its development in cystic lesions/cavitation associated with tuberculosis, sarcoidosis, bronchiectasis, lung abscess, and cavitating neoplasm to name a few. Coexistence of aspergilloma with idiopathic pulmonary fibrosis (IPF) has not been reported in literature so far, to the best of our knowledge. We hereby report the case of a 55-year-old female with IPF having fungal ball.