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.

Prospects for Observing and Localizing Gravitational-Wave Transients with Advanced LIGO and Advanced Virgo

We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron-star systems, which are considered the most promising for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and 90% credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5 deg2 to 20 deg2 will require at least three detectors of sensitivity within a factor of ∼ 2 of each other and with a broad frequency bandwidth. Should the third LIGO detector be relocated to India as expected, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.

First isolation of Candida metapsilosis in Kuwait, an emerging global opportunistic pathogen

Invasive infections due to uncommon and rare yeast species are increasing worldwide in prevalence and are associated with high mortality rates. Here, we describe the first isolation and characterization of Candida metapsilosis cultured from the blood sample of a 10-year-old Saudi girl, who suffered from a neurodegenerative disorder, in Kuwait. The yeast isolate was identified by sequencing of ITS region and D1/D2 domains of rDNA. The report extends the geographic distribution of C. metapsilosis to the Middle East and highlights the emerging role of uncommon yeast species causing infections in susceptible hosts.

Management of Acute Pulmonary Embolism: Consensus Statement for Indian Patients

Pulmonary embolism (PE) is an important cause of morbidity and mortality among hospitalized patients. Although the exact epidemiology of PE is not known in India, Some of the studies show that more frequently it is missed and not managed appropriately leading to significant cardiovascular morbidity and mortality. Justification and purpose: Indian guidelines for the diagnosis and treatment of acute PE are not yet formulated. The objective of this consensus statement is to propose a diagnostic and management approach for acute PE in India.

PROCESS

A working group of 15 experts in the management of acute PE (cardiologists, pulmonologist, haematologist, emergency specialist and intensivists). This consensus statement makes recommendations for diagnosis and management for PE based on literature review, including Indian data.

Attitude of medical students towards occupational safety and health: a multi-national study

BACKGROUND

Work-related diseases contribute immensely to the global burden of diseases. Better understanding of attitudes of health care workers towards occupational safety and health (OSH) is important for planning.

OBJECTIVE

To assess the attitude of medical students towards OSH around the globe.

METHODS

A questionnaire assessing the attitude towards OSH was administered to medical and paramedical students of 21 Medical Universities across the globe. In the current study 1895 students, aged 18-36 years, from 17 countries were included. After having performed a principal components analysis, the associations of interest between the identified components and other socio demographic characteristics were assessed by multivariate linear regression.

RESULTS

Principal component analysis revealed 3 components. Students from lower and lower-middle-income countries had a more positive attitude towards OSH, but the importance of OSH was still rated higher by students from upper-income countries. Although students from Asian and African continents showed high interest for OSH, European and South-Central American students comparatively rated importance of OSH to be higher. Paramedical students had more positive attitude towards OSH than medical students.

CONCLUSION

The attitude of students from lower-income and lower-middle-income towards importance of OSH is negative. This attitude could be changed by recommending modifications to OSH courses that reflect the importance of OSH. Since paramedical students showed more interest in OSH than medical students, modifications in existing health care system with major role of paramedics in OSH service delivery is recommended.

Cytomegalovirus infection induces a stem cell phenotype in human primary glioblastoma cells: prognostic significance and biological impact

Glioblastoma (GBM) is associated with poor prognosis despite aggressive surgical resection, chemotherapy, and radiation therapy. Unfortunately, this standard therapy does not target glioma cancer stem cells (GCSCs), a subpopulation of GBM cells that can give rise to recurrent tumors. GBMs express human cytomegalovirus (HCMV) proteins, and previously we found that the level of expression of HCMV immediate-early (IE) protein in GBMs is a prognostic factor for poor patient survival. In this study, we investigated the relation between HCMV infection of GBM cells and the presence of GCSCs. Primary GBMs were characterized by their expression of HCMV-IE and GCSCs marker CD133 and by patient survival. The extent to which HCMV infection of primary GBM cells induced a GCSC phenotype was evaluated in vitro. In primary GBMs, a large fraction of CD133-positive cells expressed HCMV-IE, and higher co-expression of these two proteins predicted poor patient survival. Infection of GBM cells with HCMV led to upregulation of CD133 and other GSCS markers (Notch1, Sox2, Oct4, Nestin). HCMV infection also promoted the growth of GBM cells as neurospheres, a behavior typically displayed by GCSCs, and this phenotype was prevented by either chemical inhibition of the Notch1 pathway or by treatment with the anti-viral drug ganciclovir. GBM cells that maintained expression of HCMV-IE failed to differentiate into neuronal or astrocytic phenotypes. Our findings imply that HCMV infection induces phenotypic plasticity of GBM cells to promote GCSC features and may thereby increase the aggressiveness of this tumor.

Clinical validity of consultant technical skills assessment in the English National Training Programme for Laparoscopic Colorectal Surgery

Background

The English National Training Programme for Laparoscopic Colorectal Surgery introduced a validated objective competency assessment tool to accredit surgeons before independent practice. The aim of this study was to determine whether this technical skills assessment predicted clinical outcomes.

Methods

Established consultants, training in laparoscopic colorectal surgery, were asked to submit two operative videos for evaluation by two blinded assessors using the competency assessment tool. A mark of 2·7 or above was considered a pass. Clinical and oncological outcomes were compared above and below this mark, including regression analysis.

Results

Eighty-five consultant surgeons submitted 171 videos. Of these, 44 (25·7 per cent) were in the fail group (score less than 2·7). This low scoring group had more postoperative morbidity (25 versus 8·7 per cent; P = 0·005), including surgical complications (18 versus 6·3 per cent; P = 0·020) and fewer lymph nodes harvested (median 13 versus 18; P = 0·004). A score of less than 2·7 was an independent predictor of surgical complication, lymph node yield and distal resection margin clearance. Consultants with higher scores had performed similar numbers of laparoscopic colorectal operations (median 37 versus 40; P = 0·373) but more structured training operations (18 versus 9; P < 0·001).

Conclusion

An objective technical skills assessment provided a discriminatory tool with which to accredit laparoscopic colorectal surgeons.

PDZ domain-mediated protein interactions: therapeutic targets in neurological disorders

Protein-protein interactions are critical for cellular functioning, and their deregulation is involved in several diseases. Targeting these protein interacting domains could be a promising approach in drug designing. One such domain, the PDZ domain is encoded by several proteins of the nervous system in particular at the postsynaptic density site of neurons where they contribute to signal transduction pathways and neurotransmission. Since PDZ domains have well-defined binding sites, often corresponding to short amino acid motifs at the C-termini of target partner proteins, they provide promising targets for drug discovery. Viruses are art master in manipulating the signaling machinery of the cell they infect. Some of them such as rabies virus which promotes neuron survival by disrupting peculiar PDZ complexes can serve as a source of inspiration for the design of new neuroprotective drugs. This review highlights PDZ-mediated protein interactions in nervous system and their therapeutic potential.

"Is general surgery still relevant to the subspecialised trainee?" A 10 year comparison of general versus specialty surgical practice

BACKGROUND

The splintering of general surgery into subspecialties in the past decade has brought into question the relevance of a continued emphasis on traditional general surgical training. With the majority of trainees now expressing a preference to subspecialise early, this study sought to identify if the requirement for proficiency in managing general surgical conditions has reduced over the past decade through comparison of general and specialty surgical admissions at a tertiary referral center.

METHODS

A cross-sectional review of all surgical admissions at Cork University Hospital was performed at three individual time points: 2002, 2007 & 2012. Basic demographic details of both elective & emergency admissions were tabulated & analysed. Categorisation of admissions into specialty relevant or general surgery was made using International guidelines.

RESULTS

11,288 surgical admissions were recorded (2002:2773, 2007:3498 & 2012:5017), showing an increase of 81 % over the 10-year period. While growth in overall service provision was seen, the practice of general versus specialty relevant emergency surgery showed no statistically significant change in practice from 2002 to 2012 (p = 0.87). General surgery was mostly practiced in the emergency setting (84 % of all emergency admissions in 2012) with only 28 % elective admissions for general surgery. A reduction in length of stay was seen in both elective (3.62-2.58 bed days, p = 0.342) & emergency admissions (7.36-5.65, p = 0.026).

CONCLUSIONS

General surgical emergency work continues to constitute a major part of the specialists practice. These results emphasize the importance of general surgical training even for those trainees committed to sub-specialisation.

Retained weapon injuries: experience from a civilian metropolitan trauma service in South Africa

INTRODUCTION

Retained weapon (RW) injuries are uncommon, but there is no current consensus on the best management approach.

METHODS

We reviewed our experience of 102 consecutive patients with non-missile RWs in a high-volume metropolitan trauma service managed over a 10-year period.

RESULTS

Of the 102 patients, 95 were males (93%), 7 were females (7%), and median age was 24 (21-28) years. Weapons: 73% (74/102) knives, 17% (17/102) screwdrivers, 5% spears, 6% (6/102) others [axe (1), glass fragment (1), stick (1), sickle blade (1), wire (1) and stone (1)].

LOCATION

8% (8/102) head, 20% (20/102) in the face, 9% (9/102) neck, 14% (14/102) thorax, 25% (26/102) abdomen, 23% (23/102) upper limb, 2% (2/102) lower limb. Four per cent (4/102) were haemodynamically unstable and proceed immediately to the operating theatre for operative exploration and weapon extraction. Imagining: 88 (86%) plain radiographs, 65 (64%) non-contrast CT scans, 41 (40%) contrast CT angiography, 4 (4%) formal angiography. Seventy-two underwent simple extraction, and 29 underwent extract plus open operation. One patient absconded. Specialist surgeons involved in extraction: trauma surgeons (74), neurosurgeons (10), ophthalmic surgeons (11) and ENT surgeons (4). Overall, 92% (94/102) survived to discharge.

CONCLUSIONS

The vast majority of patients with RWs will be admitted in a stable condition and haemodynamic instability was almost exclusively seen in the anterior thorax. The most common site was the posterior abdomen. Detailed imagining should be used liberally in stable patients and unplanned extraction in an uncontrolled environment should be strongly discouraged.