GW190521: First Measurement of Stimulated Hawking Radiation from Black Holes

Being the most massive binary black hole merger event observed to date, GW190521 is in a class of its own. The exceptionally loud ringdown of this merger makes it an ideal candidate to search for gravitational wave echoes, a proposed smoking gun for the quantum structure of black hole horizons. We perform an unprecedented multi-pronged search for echoes via two well-established and independent pipelines: a template-based search for stimulated emission of Hawking radiation, or Boltzmann echoes, and the model-agnostic coherent WaveBurst (cWB) search. Stimulated Hawking radiation from the merger is expected to lead to post-merger echoes at horizon mode frequency of $\sim 50$ Hz (for quadrupolar gravitational radiation), repeating at intervals of $\sim 1$ second, due to partial reflection off Planckian quantum structure of the horizon. A careful analysis using dynamic nested sampling yields a Bayesian evidence of $7\pm 2$ (90% confidence level) for this signal following GW190521, carrying an excess of $10^{+9}_{-7}\%$ in gravitational wave energy, relative to the main event. Similarly, the reconstructed waveform of the first echo in cWB carries an energy excess of $13^{+16}_{-7}\%$. Accounting for the "look-elsewhere" effects, we estimate a p-value for false detection probability of $5.1 \times 10^{-3}$ (or 2.6$\sigma$) using cWB pipeline, although the verdict on the co-localization of the post-merger echo and the main event in the sky is inconclusive. While the current evidence for stimulated Hawking radiation does not reach the gold standard of $5\sigma$, our findings are in line with expectations for stimulated Hawking radiation at current detector sensitivities. The next generation of gravitational wave observatories can thus draw a definitive conclusion on the quantum nature of black hole horizons

Vortex formation and dissolution in sheared sands

Using digital image correlation, we track the displacement fluctuations within a persistent shear band in a dense sand specimen bounded by glass walls undergoing plane strain compression. The data evidences a clear, systematic, temporally recurring pattern of vortex formation, dissolution, and reformation throughout macroscopic softening and critical state regimes. During softening, locally affine deformation zones are observed at various locations along the shear band, which we argue to be kinematic signatures of semi-stable force chains. Force chain collapse then occurs, inducing vortex formation. Local jamming at the conflux of opposing displacements between adjacent vortices arrests the vortices, providing an avenue for potential new force chains to form amidst these jammed regions. The process repeats itself temporally throughout the critical state. The pattern further correlates with fluctuations in macroscopic shear stress. We characterize the nature of the observed vortices, as they are different in our sands comprised of irregular shaped particles, as compared to previous observations from experiments and numerical simulations which involved circular or rounded particles. The results provide an interesting benchmark for behavior of non-circular/non-spherical particles undergoing shear.National Science Foundation (U.S.) (grant CMMI-0748284)University of Southern CaliforniaUniversity of Southern California Women in Science and Engineering (WiSE) Progra

Antioxidant effects of proanthocyanidin from grape seed on hepatic tissue injury in diabetic rats

Objective(s): Diabetes plays an important role in the induction of the liver injury. Grape seed proanthocyanidin (GSP) have a wide range of medicinal properties against oxidative stress. In this study we evaluated antioxidant effects of GSP on liver in streptozotocin-induced diabetic rats. Materials and Methods: Thirty male Sprague-Dawley rats were divided into three groups: control, untreated diabetic and diabetic rats treated with GSP. Diabetes was induced in rats by intraperitoneal injection of streptozotocin (50 mg/kg). GSP were administered via oral gavage (200 mg/kg) for 4 weeks. Results: GSP produced significant hepatoprotective effects by decreasing activities of serum aminotransferases and alkaline phosphatase, and decreasing liver malondialdehyde and bilirubin (P<0.05) levels. It increased liver superoxide dismutase, catalase and glutathione peroxidase activities and albumin level (P<0.05). Administration of GSP significantly ameliorated structural changes induced in liver of diabetic rats. Conclusion: GSP have protective effects against hepatic tissue injury due to antioxidant properties

Epidemiological Patterns of Road Traffic Crashes During the Last Two Decades in Iran: A Review of the Literature from 1996 to 2014

Context: Despite considerable attention given to health statistics of road traffic crashes (RTCs), the epidemiological aspects of injuries resulting from RTCs are not fully understood in Iran and other developing countries. The aim of this review was to study the epidemiological pattern and issues arising due to RTCs in Iran. Evidence Acquisition: The scope of this study involves data from a broad range of published literature on RTCs in Iran. Data collection for this study was conducted by searching for keywords such as traffic accidents, traffic crashes, motorcycle accidents, motorcycle crashes, motorcycle injury, motor vehicle injury, motor vehicle crashes and motor vehicle accidents, Iran and Iranian in various databases such as Embase, PubMed, Google Scholar, Scopus, Magiran, Iranian scientific information database (SID) and IranMedex. Results: This study comprised of 95 articles. It is evident from this review that a large number of severe RTCs occur due to collision of two or more vehicles and most of the victims are males aged between 30 and 39 years. Male pedestrian, drivers and passengers are more likely to be severely injured in comparison to females. One of the most prevalent causes of death among adults involved in the RTCs are head injuries and the majority of deaths occur prior to hospitalization. Mortality rates for RTCs are higher in summer, especially during midnight among all age groups. The most common individual and environmental risk factors associated with RTCs include lack of attention, getting trapped in the car, listening to music, fatigue and sleepiness, duration and distance and negligence of seatbelt usage while driving. Conclusions: The findings of the current study will be beneficial in prevention of RTCs and its associated complications and hence will be vital for policy makers, health service managers and stakeholders

Emotional and behavioral problems of single parent vs. Two parent children: Imam Khomeini charity

Background: The aim of this survey is to compare the emotional and behavioral problems of children with only one parent versus those from two-parent families. We analyzed behavioral problems such as aggression, delinquency and socialization issues, as well as emotional problems such as depression, anxiety, and somatic complaints. Methods: Using a multi-stage cluster sampling, 10 of the 20 geographic regions covered by Imam Khomeini Charity were selected. Using systematic random sampling, 460 families with children aged 4-18 years were selected. All children were evaluated using the Child Behavior Check List (CBCL) to determine behavioral and emotional problems. Logistic regression tests were conducted to measure the effects variables, including age, gender, number of parents in the family, psychiatric history of each child and history of parental psychiatric treatment, on the internalizing, externalizing and total CBCL scores. A cut-off score of 64 was used to convert raw scores. Results: No differences were observed in CBCL subscales between single-parent children vs. children of two-parent families. Conclusion: Regarding the two-parent families among the study population, the results could not be generalized. As these families have qualified for assistance, the father cannot manage the family because of his disability, such as physical or mental problems. This minimizes the effect of having a father in a two-parent family, rendering them similar to single-parent families. Thus, differences were not observed between the two types of families. Further studies are necessary to compare single-parent families with two-parent families among the community. © 2008, Tehran University of Medical Sciences. All rights reserved

Previous tonsillectomy modifies odds of tonsil and base of tongue cancer

BACKGROUND: Tonsillectomy is a commonly performed surgical procedure that involves removal of the palatine tonsils. The purpose of this study is to examine the association between previous tonsillectomy and odds of oropharyngeal squamous cell carcinoma (OPSCC) in a large population-based case-control study. We hypothesise that previous tonsillectomy is associated with a decreased odds of tonsil cancer with no impact on the odds of developing base of tongue (BOT) cancer. METHODS: This was a population-based, frequency-matched case-control study with multinomial logistic regression, including 1378 controls, 108 BOT cancer cases, and 198 tonsil cancer cases. Demographic and risk factor data were collected using a structured questionnaire during an in-home visit conducted by trained nurse-interviewers. The human papillomavirus (HPV) tumour status was determined through Luminex-based multiplex PCR and p16 status by immunohistochemistry. RESULTS: Previous tonsillectomy was associated with a nearly two-fold increased odds of BOT cancer (OR=1.95, 95% CI 1.25-3.06, P=0.003) and a large decrease in the odds of tonsil cancer (OR=0.22, 95% CI 0.13-0.36, P<0.001). When HPV status was considered, tonsillectomy was associated with a decreased odds of HPV-positive tonsil cancer (OR=0.17, 95% CI 0.08-0.34, P<0.001) and an increased risk of HPV-positive BOT cancer (OR=2.46, 95% CI 1.22-4.95, P=0.012). When p16 status was considered, tonsillectomy was associated with an increased odds of p16-positive BOT cancer (OR=2.24, 95% CI 1.16-4.35, P=0.017) and a decreased odds of p16-positive tonsil cancer (OR=0.14, 95% CI 0.07-0.31, P<0.001). CONCLUSIONS: Previous tonsillectomy modifies the odds of both tonsil and BOT cancer, with decreased odds of tonsil cancer and increased odds of BOT cancer. A history of previous tonsillectomy may play a role in OPSCC risk stratification when considered along with other covariates such as sexual history, smoking status, and age

Assessment of the Linkages and Leakages in a Cloud-Based Computing Collaboration among Construction Stakeholders

The uniqueness of the construction industry can be understood in the large volumes of information in terms of paper works, processes, and communication disseminated daily. The voluminous information requires close coordination which cloud based systems offer. The aim of this research is to assess the linkages and leakages in a cloud-based computing collaboration among construction stakeholders. A purposive sampling technique was used in selecting the participants of the study. A questionnaire based instrument was distributed to eighty (80) construction stakeholder in Lagos State, Nigeria. The data collected was analyzed using SPSS v.21. Statistical tools such as frequencies, stacked bars, mean scores, factor analysis, and analysis of variance (ANOVA) were used in the study. The result of the study revealed that construction stakeholders rarely utilize cloud-based technologies for their construction processes. Construction professionals that access cloud based technologies, do so with their smart mobile phones, laptops, and tablet. The study classified the leakages that exist in the use of cloud-based technologies as securitybased factors, cloud-based infrastructure factors, and cloud-based benefits deficiency based factors. In conclusion, the study revealed that the linkages in the use of cloudbased technologies include knowledge sharing, remote access of back-office activities and engendering collaboration among construction stakeholders. It was recommended that construction stakeholders should leverage on the benefits cloud-based technologies has to offer in today’s competitive economy. Construction stakeholdersshould be adequately informed on the available cloud-based computing technologies and the additions it can bring into the construction process. Cloud computing technology vendors should improve on the security and privacy features of the platform for adequate protection of building data

Prognostic significance of non-HPV16 genotypes in oropharyngeal squamous cell carcinoma

Recent studies have found that cases with oropharyngeal squamous cell carcinoma (OPSCC) positive for HPV16 genotype have better overall survival compared with cases positive for other HPV genotypes. We sought to further replicate these studies and determine if this relationship is modified by expression of p16 tumor suppressor protein