Tests of General Relativity with GW170817.

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

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

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

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

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

GW170817: Measurements of Neutron Star Radii and Equation of State.

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

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

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

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

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

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.

Short stature in Saudi Arabia: etiologic profile in adult endocrine clinic.

BACKGROUND: To determine causes of short stature (SS) in adult endocrine service at a Saudi Arabian tertiary center. METHODS: A retrospective analysis was made of data from 104 subjects who were primarily evaluated for causes of SS in the endocrinology unit of King Khalid University Hospital Riyadh from January 1 997 to December 2006. RESULTS: Growth hormone deficiency (GHD) and normal variant short stature (NVSS) were the leading causes of SS contributing 90 subjects (86%; 43% for each), followed by celiac disease in 4 subjects (4%). Other etiologies of short stature included primary hypothyroidism, diabetes mellitus, and Turner's syndrome (2% each). CONCLUSION: We conclude that GHD and NVSS are the commonest causes of SS in Saudi Arabia. In view of the need to differentiate the two major etiologies, it is suggested that growth hormone stimulatory tests be conducted on all patients with SS associated with delayed bone age. Further prospective study in a larger population is needed to characterize this finding.

Graves' disease in Saudi Arabia: a ten-year hospital study.

OBJECTIVE: To determine clinical manifestation and mode of treatment of Graves' disease at King Khalid University Hospital Riyadh, Saudi Arabia. METHODS: A retrospective study of all cases of Graves' disease diagnosed at the hospital in the period between January 1995 and December 2004, who received a minimum of two years treatment were included in the study. RESULTS: A total of 194 patients were seen with female: male ratio of 2.9:1 and mean age of 32 +/- 0.9 years. Sixty nine percent of the patients had positive thyroid antibodies. Palpitations, tremors, weight loss and nervousness were the most common presenting manifestations. Forty nine percent of patients were treated with radioiodine, 38% with antithyroid drugs, and 13% underwent subtotal thyroidectomy. CONCLUSION: Clinical manifestations of Graves' disease in our patients distinctly differed from those reported in the West and Pacific Islanders with notable rarity of pretibial myxoedema and hyperpigmentation respectively. We also noted higher male to female ratio and an increasing utility of radioactive iodine therapy while use of antithyroid drugs and surgery are declining.

Growth hormone deficiency short stature in a third world adult endocrine clinic: usefulness of clonidine test in its diagnosis.

BACKGROUND: Short stature (SS) can be treatable; yet the diagnostic value of a simple test in correctly identifying the two common etiologies in developing countries, viz., growth hormone deficiency (GHD) and normal variant short stature (NVSS), has not been reported in a typical third world population. OBJECTIVES: The aim of the study was to evaluate the reliability of clonidine test in differentiating short stature caused by GHD from NVSS. SETTINGS AND DESIGN: Data of subjects evaluated for growth hormone deficiency SS at a Saudi Arabian university hospital were retrospectively reviewed. MATERIALS AND METHODS: Clonidine and insulin tolerance tests (ITT) were conducted on 60 subjects aged 12 years and above with SS, while peak stimulated growth hormone cut off value of < 10 microg/l was used to diagnose GHD. STATISTICAL ANALYSIS: Sensitivity and specificity for clonidine test and ITT were computed, while receiver operator characteristic (ROC) curves were constructed from the results in order to assess the diagnostic usefulness of the two tests. Mann-Whitney test was used to determine level of significance. RESULTS: Clonidine test showed superior sensitivity and specificity, viz., 81% and 82%, as against 65% and 59% for ITT respectively. Overall, the efficiency of clonidine test in correctly differentiating short stature caused by GHD from NVSS was higher, viz., 90%, compared to ITT's 77%. CONCLUSIONS: Clonidine test proved to be an excellent test for initial assessment of GHD and may be used as a screening test for short stature in third world countries.

Hirsutism in Saudi females of reproductive age: a hospital-based study.

BACKGROUND: Hirsutism among women of fertile age is commonly seen in clinical practice, but the pattern of the disease in Saudi Arabs has not been studied. The aim of the study was to determine the clinical, biochemical and etiologic features of hirsutism in Saudi females. METHODS: 101 Saudi Arab women presenting with hirsutism at King Khalid University Hospital, Riyadh, Saudi Arabia, from 1 January 2000 to 31 December 2005 were prospectively assessed using the recently approved diagnostic guidelines for hyperandrogenic women with hirsutism. RESULTS: Polycystic ovary syndrome (PCOS) was the cause of hirsutism in 83 patients (82%) followed by idiopathic hirsutism (IH) in 11 patients (11%). Others causes of hirsutism included late onset congenital adrenal hyperplasia in 4 patients (4%), microprolactinoma in 2 (2%) and Cushingâs syndrome in 1 (1%) patient. Age at presentation of PCOS was 24.5+/-6.6 years (mean+/-SD) and 51% of the subjects were obese. Furthermore, 74 (89%) of patients with PCOS had an oligo/anovulatory cycle while the remaining 9 patients (11%) maintained normal regular menstrual cycle. Luteinizing hormone and total testosterone were significantly higher in patients with PCOS than in those with IH (P<.05). CONCLUSIONS: The present data show PCOS to be the commonest cause of hirsutism in our clinical practice and PCOS is prominent amongst young obese females. However, further studies on a larger scale are needed to verify our findings.

Treatment of Graves' hyperthyroidism--prognostic factors for outcome.

OBJECTIVE: To determine whether clinical and biochemical features of Graves' disease at presentation predict response to medical and radioiodine treatment. METHODS: We carried out a retrospective 10-year study of 194 consecutive Saudi subjects with Graves' disease who were treated with antithyroid drugs, radioiodine therapy, or both, between January 1995 and December 2004 at King Khalid University Hospital, Riyadh, Saudi Arabia. RESULTS: At diagnosis, the mean age was 32 +/- 0.9 years. Only 26% of patients had successful outcome after a course of antithyroid medication. None of the clinical or biochemical factors were associated with a favorable outcome of antithyroid treatment. One dose of radioiodine [13-15 mCi (481-555 MBq)] cured hyperthyroidism in 83% of patients. Presence of ophthalmopathy at presentation was shown to be a significant contributing factor to failure to respond to a single dose of radioiodine (odds ratio, 6.4; 95% CI, 1.51-24.4; p<0.01). Failure of radioiodine treatment was also associated with higher serum free T3 concentration at presentation (p=0.003). CONCLUSION: In patients with Graves' hyperthyroidism, radioiodine treatment is associated with higher success rate than antithyroid drugs. A dose of 13-15 mCi (481-555 MBq) seems to be practical and effective, and should be considered as first line therapy. Patients with high free T3 concentration and, those with ophthalmopathy at presentation were more likely to fail radioiodine treatment. A higher dose of radioiodine may be advisable in such patients.

[Place and results of frozen section analysis in the management of malignant and borderline ovarian tumors]. / Place et résultats de l'examen extemporané dans la stratégie chirurgicale des tumeurs épithéliales malignes et à la limite de la malignité de l'ovaire.

The management of ovarian tumors discovered during laparoscopy depends equally on the surgeon and the pathologist. Thus, the surgeon will undergo a more or less radical surgery depending on frozen section analysis (FSA),which depends mainly on the pathologist's skills, the histopathologic type and the volume and the localization of the tumor. The accuracy of FSA is higher in ovarian cancer than in borderline tumor. In patients treated initially with a laparoscopic approach, if the FSA demonstrates the presence of an invasive carcinoma, a conversion to laparotomy should be performed in order to complete the surgical staging. If the FSA demonstrates the presence of a borderline tumor, an exclusive laparoscopic approach could be discussed.

Thermal enhancement of oxaliplatin-induced inhibition of cell proliferation and cell cycle progression in human carcinoma cell lines.

Hyperthermia is used to treat intraperitoneal colorectal carcinomatosis. In this setting, the molecular effects of oxaliplatin and hyperthermia, in combination and alone, were deciphered in ovarian and colon cancer cells. The combined antiproliferative effects of hyperthermia and oxaliplatin (Eloxatine) on human IGROV-1 ovarian carcinoma, Caco-2 and HT-29 colon carcinoma cell lines were investigated by cell viability test, cell cycle analysis and modulation of expression of cell cycle-related proteins. Oxaliplatin inhibited growth of all cell lines in a dose-dependent manner. The efficacy of the drug was markedly enhanced by concurrent exposure to mild heat shock (1 h, 42 degree C). In IGROV-1 cells, a low concentration (15 microg/ml) of oxaliplatin in combination with hyperthermia induced a transient G2/M arrest. In both colon carcinoma cell lines, a G1/S arrest with a reduction of the G0/G1 population occurred. In IGROV-1 and Caco-2 cells, growth arrest was accompanied by apoptosis as suggested by the appearance of sub-G1 population. Time-course changes of cell cycle regulatory proteins levels revealed accumulation of cyclins A and B as well as of cdc2 and cdk2 upon exposure of IGROV-1 cells to hyperthermia and oxaliplatin. In this cell line, p53 appeared to be implicated in both G2/M arrest and apoptosis. G1/S arrest of HT-29 cells was linked to up-regulation of cyclin E and p27(Kip1) and accumulation of the hypophosphorylated form of pRB, whereas in Caco-2 cells only the hyperphosphorylated form was detected as well as a down-regulation of the proto-oncogene c-myc. Taken together, the results of these in vitro studies suggest that hyperthermia and oxaliplatin might elicit antiproliferative effects by modulating the expression of cell cycle regulatory proteins through different signalling pathways.

Clinical outcome after laparoscopic pure management of borderline ovarian tumors: results of a series of 34 patients.

BACKGROUND: The aim of this study was to assess clinical outcome after laparoscopic treatment of borderline ovarian tumor (BOT). PATIENTS AND METHODS: Thirty-four patients treated initially and/or for recurrent disease using a laparoscopic approach for BOT from 1984 to January 2002. RESULTS: Thirty-four patients underwent laparoscopic pure treatment (without conversion by laparotomy and/or reassessment surgery by laparotomy) for BOT. Conservative treatment was performed in 31 (91%) patients. Median follow-up time was 45 months (range 6-228). Six (17%) patients recurred (in the remaining ovary following conservative surgery in five patients and in the peritoneum in one patient). Two port-site metastases were observed. None of the patients had recurrent disease in the form of ovarian carcinoma. Nine spontaneous pregnancies were observed in six patients from a group of 15 patients desiring pregnancy. All patients are alive today and disease-free. CONCLUSION: These results seem to demonstrate that laparoscopic treatment can be safely performed in young patients with early stage BOT. Such a procedure is then feasible, but should be evaluated in patients with BOT and peritoneal implants.

Are nodal metastases in ovarian cancer chemoresistant lesions? Analysis of nodal involvement in 105 patients treated with preoperative chemotherapy.

BACKGROUND: To report the rates of nodal involvement in epithelial ovarian cancer (EOC) in patients who underwent initial lymphadenectomy (before chemotherapy) and patients who underwent lymphadenectomy after chemotherapy. STUDY DESIGN: The rates of nodal involvement in 205 patients with EOC who underwent complete bilateral pelvic and para-aortic lympadenectomy between 1985 and 2001 were analyzed: 100 women underwent this surgical procedure before chemotherapy (initial surgery) and 105 at the end of chemotherapy (second-look surgery for 77 patients with 6 courses of a platinum-based regimen) or during chemotherapy (interval debulking surgery for 28 patients with 3 courses of a platinum-based regimen containing paclitaxel). RESULTS: The overall frequency of lymph-node involvement was 35% (35/100) in patients treated with initial surgery, 54% (15/28) in the interval debulking surgery group and 36% (28/77) in the second-look surgery group. In patients with Stage III disease, the rates of nodal involvement in patients treated with initial surgery, interval debulking surgery (with paclitaxel-based regimen) and second-look surgery were respectively: 53% (15/28), 58% (15/26) and 48% (20/42). The rates of nodal involvement in patients who underwent lymphadenectomy prior to or after chemotherapy were not statistically different whatever the stage of the disease. Adding paclitaxel to the platinum-based regimen does not seem to improve node sterilization rates. CONCLUSIONS: The rates of nodal involvement seem to be similar in patients treated before or after chemotherapy. Such results suggest that nodal metastases are not as chemosensitive as peritoneal lesions. However, further studies are needed to evaluate the therapeutic value of lymphadenectomy in patients with nodal involvement.

Value of routine follow-up procedures for patients with stage I/II cervical cancer treated with combined surgery-radiation therapy.

BACKGROUND: The aim of this study was to determine the value of routine follow-up for the detection of recurrence in patients treated for cervical cancer. PATIENTS AND METHODS: From 1986 to 1998, 583 women with stage I and II cervical carcinoma were treated with combined surgery-radiation therapy. After treatment, follow-up was based on clinical examination, a systematic Pap smear and radiography (chest X-ray and abdomino-pelvic ultrasonography). RESULTS: Forty-five patients had recurrence observed with a delay > or = 6 months following the end of treatment. Thirty-eight patients had symptoms and seven were asymptomatic at the time of their recurrence. Among asymptomatic patients only two recurrences were diagnosed following routine examinations. Survival is similar in asymptomatic and symptomatic recurrent patients. CONCLUSIONS: In conclusion, follow-up of patients treated for cervical cancer based on routine Pap smears and systematic radiography does not permit earlier detection of recurrence and does not increase survival.