| 1. |
- Adrian-Martinez, S., et al.
(författare)
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A first search for coincident gravitational waves and high energy neutrinos using LIGO, Virgo and ANTARES data from 2007
- 2013
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :6
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.
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| 2. |
- Evans, P. A., et al.
(författare)
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Swift Follow-up Observations of Candidate Gravitational-wave Transient Events
- 2012
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Ingår i: The Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 203:2
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Tidskriftsartikel (refereegranskat)abstract
- We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.
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| 3. |
- Aasi, J., et al.
(författare)
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Einstein@Home all-sky search for periodic gravitational waves in LIGO S5 data
- 2013
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Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 87:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents results of an all-sky search for periodic gravitational waves in the frequency range [50, 1190] Hz and with frequency derivative range of similar to[-20, 1.1] x 10(-10) Hz s(-1) for the fifth LIGO science run (S5). The search uses a noncoherent Hough-transform method to combine the information from coherent searches on time scales of about one day. Because these searches are very computationally intensive, they have been carried out with the Einstein@Home volunteer distributed computing project. Postprocessing identifies eight candidate signals; deeper follow-up studies rule them out. Hence, since no gravitational wave signals have been found, we report upper limits on the intrinsic gravitational wave strain amplitude h(0). For example, in the 0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with h(0) greater than 7.6 x 10(-25) at a 90% confidence level. This search is about a factor 3 more sensitive than the previous Einstein@Home search of early S5 LIGO data.
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| 4. |
- Aasi, J., et al.
(författare)
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Parameter estimation for compact binary coalescence signals with the first generation gravitational-wave detector network
- 2013
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Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 88:6
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Tidskriftsartikel (refereegranskat)abstract
- Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and in the calibration of the detectors. Here we report such measurements on a selection of simulated signals added either in hardware or software to the data collected by the two LIGO instruments and the Virgo detector during their most recent joint science run, including a "blind injection'' where the signal was not initially revealed to the collaboration. We exemplify the ability to extract information about the source physics on signals that cover the neutron-star and black-hole binary parameter space over the component mass range 1M(circle dot)-25M(circle dot) and the full range of spin parameters. The cases reported in this study provide a snapshot of the status of parameter estimation in preparation for the operation of advanced detectors.
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| 5. |
- Aasi, J., et al.
(författare)
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Search for gravitational waves from binary black hole inspiral, merger, and ringdown in LIGO-Virgo data from 2009-2010
- 2013
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Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 87:2
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Tidskriftsartikel (refereegranskat)abstract
- We report a search for gravitational waves from the inspiral, merger and ringdown of binary black holes (BBH) with total mass between 25 and 100 solar masses, in data taken at the LIGO and Virgo observatories between July 7, 2009 and October 20, 2010. The maximum sensitive distance of the detectors over this period for a (20, 20)M-circle dot coalescence was 300 Mpc. No gravitational wave signals were found. We thus report upper limits on the astrophysical coalescence rates of BBH as a function of the component masses for nonspinning components, and also evaluate the dependence of the search sensitivity on component spins aligned with the orbital angular momentum. We find an upper limit at 90% confidence on the coalescence rate of BBH with nonspinning components of mass between 19 and 28M(circle dot) of 3:3 x 10(-7) mergers Mpc(-3) yr(-1).
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| 6. |
- Aasi, J., et al.
(författare)
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The characterization of Virgo data and its impact on gravitational-wave searches
- 2012
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 1361-6382 .- 0264-9381. ; 29:15
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Tidskriftsartikel (refereegranskat)abstract
- Between 2007 and 2010 Virgo collected data in coincidence with the LIGO and GEO gravitational-wave (GW) detectors. These data have been searched for GWs emitted by cataclysmic phenomena in the universe, by non-axisymmetric rotating neutron stars or from a stochastic background in the frequency band of the detectors. The sensitivity of GW searches is limited by noise produced by the detector or its environment. It is therefore crucial to characterize the various noise sources in a GW detector. This paper reviews the Virgo detector noise sources, noise propagation, and conversion mechanisms which were identified in the three first Virgo observing runs. In many cases, these investigations allowed us to mitigate noise sources in the detector, or to selectively flag noise events and discard them from the data. We present examples from the joint LIGO-GEO-Virgo GW searches to show how well noise transients and narrow spectral lines have been identified and excluded from the Virgo data. We also discuss how detector characterization can improve the astrophysical reach of GW searches.
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| 7. |
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| 8. |
- Hellgren, R, et al.
(författare)
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Comparison of handheld ultrasound and automated breast ultrasound in women recalled after mammography screening
- 2017
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 58:5, s. 515-520
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Tidskriftsartikel (refereegranskat)abstract
- Automated breast volume scanner (ABVS) is an ultrasound (US) device with a wide scanner that sweeps over a large area of the breast and the acquired transverse images are sent to a workstation for reconstruction and review. Whether ABVS is as reliable as handheld US is, however, still not established. Purpose To compare the sensitivity and specificity of ABVS to handheld breast US for detection of breast cancer, in the situation of recall after mammography screening. Material and Methods A total of 113 women, five with bilateral suspicious findings, undergoing handheld breast US due to a suspicious mammographic finding in screening, underwent additional ABVS. The methods were assessed for each breast and each detected lesion separately and classified into two categories: breasts with mammographic suspicion of malignancy and breasts with a negative mammogram. Results Twenty-six cancers were found in 25 women. In the category of breasts with a suspicious mammographic finding (n = 118), the sensitivity of both handheld US and ABVS was 88% (22/25). The specificity of handheld US was 93.5% (87/93) and ABVS was 89.2% (83/93). In the category of breasts with a negative mammography (n = 103), the sensitivity of handheld US and ABVS was 100% (1/1). The specificity of handheld US was 100% (102/102) and ABVS was 94.1% (96/102). Conclusion ABVS can potentially replace handheld US in the investigation of women recalled from mammography screening due to a suspicious finding. Due to the small size of our study population, further investigation with larger study populations is necessary before the implementation of such practice.
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| 9. |
- Pradat, P., et al.
(författare)
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Long-term follow-up of the hepatitis CHENCORE cohort: response to therapy and occurrence of liver-related complications
- 2007
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Ingår i: Journal of Viral Hepatitis. - : Wiley. - 1365-2893 .- 1352-0504. ; 14:8, s. 556-563
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Tidskriftsartikel (refereegranskat)abstract
- The aims of the study were to verify the longterm effect of time on viral clearance in hepatitis C virus (HCV) patients and to find out factors possibly associated with disease progression. A total of 1641 patients recruited from eight European centres in 1996-1.997 were re-analysed 5-7 years after inclusion. The occurrence of decompensated cirrhosis, hepatocellular carcinoma (HCC) and liver transplantation was analysed in relation to different host and viral factors. Ninety-three per cent of the HCV patients who had cleared the virus (spontaneously or after antiviral therapy) remained HCV-RNA-negative during follow up and may be considered as 'cured'. Among patients who were sustained responders at inclusion, 2.3% developed liver complications during follow up, and 31% of non-responders did. Advanced age at infection and presence of the human leucocyte antigen (HLA) DRBI*1201-3 allele were possibly associated with a higher rate of progression to decompen- sated cirrhosis or HCC. Decompensated cirrhosis might be further associated with male gender, non-response to previous therapy, and lack of FILA DRBI*1301 allele, whereas HCC seems to be associated with the presence of the HLA DQ02 allele. Long-term follow up of HCV patients indicates that virological response persists over time and is associated with a very low incidence of liver complications. Advanced age at inclusion. advanced age at infection, viral genotype 1, non-response to previous therapy and possibly some specific HLA alleles are factors independently associated with a faster rate of progression towards liver complications. The large proportion of patients lost to follow up stresses the need for a strengthened and optimized management of HCV patients.
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| 10. |
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| 11. |
- Hellgren, R, et al.
(författare)
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The association between breast cancer risk factors and background parenchymal enhancement at dynamic contrast-enhanced breast MRI
- 2020
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 61:12, s. 1600-1607
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Tidskriftsartikel (refereegranskat)abstract
- Background parenchymal enhancement (BPE) of normal tissue at breast magnetic resonance imaging is suggested to be an independent risk factor for breast cancer. Its association with established risk factors for breast cancer is not fully investigated. Purpose To study the association between BPE and risk factors for breast cancer in a healthy, non-high-risk screening population. Material and Methods We measured BPE and mammographic density and used data from self-reported questionnaires in 214 healthy women aged 43–74 years. We estimated odds ratios for the univariable association between BPE and risk factors. We then fitted an adjusted model using logistic regression to evaluate associations between BPE (high vs. low) and risk factors, including mammographic breast density. Results The majority of women had low BPE (84%). In a multivariable model, we found statistically significant associations between BPE and age ( P = 0.002) and BMI ( P = 0.03). We did find a significant association between systemic progesterone medication and BPE, but due to small numbers, the results should be interpreted with caution. The adjusted odds ratio for high BPE was 3.1 among women with density D (compared to B) and 2.1 for density C (compared to B). However, the association between high BPE and density was not statistically significant. We did not find statistically significant associations with any other risk factors. Conclusion Our study confirmed the known association of BPE with age and BMI. Although our results show a higher likelihood for high BPE with increasing levels of mammographic density, the association was not statistically significant.
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| 12. |
- Saracco, A, et al.
(författare)
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Bolus compared with continuous infusion of microbubble contrast agent using real-time contrast harmonic imaging ultrasound in breast tumors
- 2009
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 50:8, s. 854-859
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Tidskriftsartikel (refereegranskat)abstract
- Background: Contrast-enhanced ultrasound (CEUS) has gained interest because of its ability to gather vascular information in various organs. There is still a matter of debate concerning its value in breast lesions. The method of choice on how to administer the contrast agent varies depending on the organ to be studied. Infusion of microbubbles is used in echocardiography, while bolus administration is the preferred technique for abdominal organs. Purpose: To compare—in equal doses—bolus versus continuous infusion of microbubbles, using real-time contrast harmonic imaging in breast tumors. Material and Methods: A total of 29 female patients (mean age 54 years) with either clear malignant or benign findings in the breast or axilla were included. Contrast harmonic imaging (CHI US) was performed with a Philips iU22 using an L9-3 MHz linear probe, especially designed for this purpose. A low mechanical index (0.06–0.07) was used to avoid massive destruction of the microbubbles. A dose of 2.4 ml of Sono Vue was first infused intravenously over 1 min with an infusion pump. After 10 min, the same dose was injected as a bolus over 2 s, followed by a flush of 10 ml of saline solution. Contrast uptakes by the tumors were recorded 2 min from the moment of injection, with both methods for each patient. Results: Bolus administration of contrast agent provided a sharply demarcated enhancement and wash-out pattern for all lesions. The continuous infusion of the same contrast agent failed to show any wash-in/wash-out or time-to-peak/peak intensity phenomena in all cases. Conclusion: CEUS using real-time harmonic imaging in order to evaluate breast tumors should be performed with bolus administration of contrast agent in order to achieve better intensity/time curve outcomes.
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| 13. |
- Saracco, A, et al.
(författare)
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Contrast-enhanced ultrasound using real-time contrast harmonic imaging in invasive breast cancer: comparison of enhancement dynamics with three different doses of contrast agent
- 2015
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 56:1, s. 34-41
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Tidskriftsartikel (refereegranskat)abstract
- In the last few years new potential applications have been developed for contrast-enhanced ultrasound (CEUS) and the management of breast diseases, but there is still some debate concerning the optimal dose to evaluate breast lesions, especially as a diagnostic tool. Purpose To compare different CEUS doses of injected contrast agent in order to establish an optimal dose for the diagnosis of invasive breast cancer. Material and Methods In Group A we compared the bolus dose of 1.2 mL vs. 2.4 mL and in Group B we compared the bolus dose of 2.4 mL vs. 4.8 mL (26 and 25 invasive carcinomas, respectively). CEUS was performed in real-time contrast harmonic imaging (CHI) using a L9-3 MHz probe. All examinations were recorded in a contrast side/side imaging mode loop for 120 s. Wash-in and wash-out patterns of the contrast agent were analyzed with advanced US quantification software and kinetic curves were used for statistical analysis. Results In Group B (2.4 mL vs. 4.8 mL), more and stronger correlation was found among kinetic parameters (area under the curve, P < 0.00001; lognormal model parameters, μ, P = 0.0007 and σ, P < 0.0001; mean transit time, P < 0.0001; model-based wash-out ratios, W21m, P = 0.0002; W50m, P = 0.0001; time-to-peak, P = 0.005) as compared to Group A (1.2 mL vs. 2.4 mL). Conclusion The optimal way to evaluate kinetic features of invasive breast tumors using real-time CEUS is with an injection of contrast agent of either 2.4 mL or 4.8 mL.
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| 14. |
- Saracco, A, et al.
(författare)
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Differentiation between benign and malignant breast tumors using kinetic features of real-time harmonic contrast-enhanced ultrasound
- 2012
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 53:4, s. 382-388
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Tidskriftsartikel (refereegranskat)abstract
- Contrast-enhanced ultrasound (CEUS) has gained interest because of its ability to gather vascular information in diverse organs. There is still a subject of debate concerning its value in breast lesions, especially as a differential diagnostic tool. Purpose To investigate whether kinetic parameters of CEUS can differentiate between malignant and benign breast lesions. Material and Methods We evaluated 75 malignant and 21 benign lesions in the breast or axilla. Contrast harmonic imaging (CHI) US was performed after the injection of a bolus dose of 2.4 mL of Sono Vue® (Bracco, Milano, Italy). The following parameters were calculated for kinetic analysis: initial slope, time to peak enhancement, wash-out ratios W21 and W50 (relative decrease in signal intensity from the peak enhancement to 21 s and 50 s, respectively). Results A significant difference was found between the benign and malignant lesions in time-to-peak ( P value <0.05) and wash-out ratios W21 ( P value <0.001) and W50 ( P value <0.001). The mean time-to-peak was 9.3 s for malignant and 14.6 s for benign lesions. The mean signal drop from peak to signal intensity measured at 50 s was 85% for malignant and 66% for benign lesions. There was no difference in absolute values of peak signal intensity and initial slope. The most significant difference between standardized benign and malignant wash-out curves was found at 21 s but statistical significance was reached in the range of 14–50 s. Conclusion Real-time CEUS can evolve into a new non-invasive option for differentiate malignant from benign breast lesions.
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| 15. |
- Szabo, BK, et al.
(författare)
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Adjunctive diagnostic value of targeted electrical impedance imaging to conventional methods in the evaluation of breast lesions
- 2005
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 46:8, s. 782-790
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To determine the diagnostic accuracy of targeted electrical impedance imaging in characterizing breast lesions, and to evaluate whether lesion size, depth and histopathology affect the diagnosis. Material and Methods: A total of 137 women with 145 lesions (79 malignant and 66 benign) found by palpation or mammography were prospectively enrolled in this study. The patients were examined by means of clinical breast examination, mammography, ultrasonography, and electrical impedance imaging with TransScan TS2000. A level of suspicion (LOS) post-processing algorithm (v2.67) was used for TS2000 lesion assessment. Imaging findings were correlated with cytologic ( n = 54) and histologic diagnoses ( n = 91). Patients with benign lesions were followed up for a mean of 36 months. Results: TS2000 showed a high sensitivity (86%) which did not differ significantly from that of mammography (87%) and ultrasonography (US) (75%). The specificity of TS2000 (49%) was significantly lower compared to mammography (97%, P<0.0001) and US (100%, P<0.0001). The additive use of TS2000 to mammography and US yielded no significant increase in sensitivity (97%), but the decrease in specificity was significant (46%, P<0.0001). Diagnostic effectiveness of TS2000 (Az = 0.68), as measured by the area under the ROC curve, was significantly lower than for mammography (Az = 0.93, P<0.0001) and for US (Az = 0.91, P<0.0001). When using TS2000 in addition to mammography and US (Az = 0.86), a significant impairment was found ( P = 0.0003). Conclusion: The role of targeted electrical impedance imaging as an adjunct to mammography and ultrasonography in the diagnosis of breast lesions is not justified by the result of this study.
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| 16. |
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