Cygnus X-1 contains a 21-solar mass black hole-Implications for massive star winds.

The evolution of massive stars is influenced by the mass lost to stellar winds over their lifetimes. These winds limit the masses of the stellar remnants (such as black holes) that the stars ultimately produce. We used radio astrometry to refine the distance to the black hole x-ray binary Cygnus X-1, which we found to be [Formula: see text] kiloparsecs. When combined with archival optical data, this implies a black hole mass of 21.2 ± 2.2 solar masses, which is higher than previous measurements. The formation of such a high-mass black hole in a high-metallicity system (within the Milky Way) constrains wind mass loss from massive stars.

A rapidly changing jet orientation in the stellar-mass black-hole system V404 Cygni.

Powerful relativistic jets are one of the main ways in which accreting black holes provide kinetic feedback to their surroundings. Jets launched from or redirected by the accretion flow that powers them are expected to be affected by the dynamics of the flow, which for accreting stellar-mass black holes has shown evidence for precession1 due to frame-dragging effects that occur when the black-hole spin axis is misaligned with the orbital plane of its companion star2. Recently, theoretical simulations have suggested that the jets can exert an additional torque on the accretion flow3, although the interplay between the dynamics of the accretion flow and the launching of the jets is not yet understood. Here we report a rapidly changing jet orientation-on a time scale of minutes to hours-in the black-hole X-ray binary V404 Cygni, detected with very-long-baseline interferometry during the peak of its 2015 outburst. We show that this changing jet orientation can be modelled as the Lense-Thirring precession of a vertically extended slim disk that arises from the super-Eddington accretion rate4. Our findings suggest that the dynamics of the precessing inner accretion disk could play a role in either directly launching or redirecting the jets within the inner few hundred gravitational radii. Similar dynamics should be expected in any strongly accreting black hole whose spin is misaligned with the inflowing gas, both affecting the observational characteristics of the jets and distributing the black-hole feedback more uniformly over the surrounding environment5,6.

Early Intervention for Diabetes in Medical and Surgical Inpatients Decreases Hyperglycemia and Hospital-Acquired Infections: A Cluster Randomized Trial.

OBJECTIVE: To investigate if early electronic identification and bedside management of inpatients with diabetes improves glycemic control in noncritical care. RESEARCH DESIGN AND METHODS: We investigated a proactive or early intervention model of care (whereby an inpatient diabetes team electronically identified individuals with diabetes and aimed to provide bedside management within 24 h of admission) compared with usual care (a referral-based consultation service). We conducted a cluster randomized trial on eight wards, consisting of a 10-week baseline period (all clusters received usual care) followed by a 12-week active period (clusters randomized to early intervention or usual care). Outcomes were adverse glycemic days (AGDs) (patient-days with glucose <4 or >15 mmol/L [<72 or >270 mg/dL]) and adverse patient outcomes. RESULTS: We included 1,002 consecutive adult inpatients with diabetes or new hyperglycemia. More patients received specialist diabetes management (92% vs. 15%, P < 0.001) and new insulin treatment (57% vs. 34%, P = 0.001) with early intervention. At the cluster level, incidence of AGDs decreased by 24% from 243 to 186 per 1,000 patient-days in the intervention arm (P < 0.001), with no change in the control arm. At the individual level, adjusted number of AGDs per person decreased from a mean 1.4 (SD 1.6) to 1.0 (0.9) days (-28% change [95% CI -45 to -11], P = 0.001) in the intervention arm but did not change in the control arm (1.8 [2.0] to 1.5 [1.8], -9% change [-25 to 6], P = 0.23). Early intervention reduced overt hyperglycemia (55% decrease in patient-days with mean glucose >15 mmol/L, P < 0.001) and hospital-acquired infections (odds ratio 0.20 [95% CI 0.07-0.58], P = 0.003). CONCLUSIONS: Early identification and management of inpatients with diabetes decreased hyperglycemia and hospital-acquired infections.

Prolonged and Continuous Measurement of Kidney Oxygenation in Conscious Rats.

A relative deficiency in kidney oxygenation, i.e., renal hypoxia, may contribute to the initiation and progression of acute and chronic kidney disease. A critical barrier to investigate this is the lack of methods allowing measurement of the partial pressure of oxygen in kidney tissue for long periods in vivo. We have developed, validated, and tested a novel telemetric method that can do this. Here we provide details on the calibration, implantation, implementation for data recording, and reuse of this telemetry-based technology for measurement of medullary tissue oxygen tension in conscious, unrestrained rats. This technique provides an important additional tool for investigating the impact of renal hypoxia in biology and pathophysiology.

Telemetry-based oxygen sensor for continuous monitoring of kidney oxygenation in conscious rats.

The precise roles of hypoxia in the initiation and progression of kidney disease remain unresolved. A major technical limitation has been the absence of methods allowing long-term measurement of kidney tissue oxygen tension (Po2) in unrestrained animals. We developed a telemetric method for the measurement of kidney tissue Po2 in unrestrained rats, using carbon paste electrodes (CPEs). After acute implantation in anesthetized rats, tissue Po2 measured by CPE-telemetry in the inner cortex and medulla was in close agreement with that provided by the "gold standard" Clark electrode. The CPE-telemetry system could detect small changes in renal tissue Po2 evoked by mild hypoxemia. In unanesthetized rats, CPE-telemetry provided stable measurements of medullary tissue Po2 over days 5-19 after implantation. It also provided reproducible responses to systemic hypoxia and hyperoxia over this time period. There was little evidence of fibrosis or scarring after 3 wk of electrode implantation. However, because medullary Po2 measured by CPE-telemetry was greater than that documented from previous studies in anesthetized animals, this method is presently best suited for monitoring relative changes rather than absolute values. Nevertheless, this new technology provides, for the first time, the opportunity to examine the temporal relationships between tissue hypoxia and the progression of renal disease.

A fully implantable telemetry system for the chronic monitoring of brain tissue oxygen in freely moving rats.

The ability to monitor tissue oxygen concentration in a specific region of the brain in a freely moving animal could provide a new paradigm in neuroscience research. We have developed a fully implantable telemetry system for the continuous and chronic recording of brain tissue oxygen (PO(2,BR)) in conscious animals. A telemetry system with a sampling rate of 2kHz was combined with a miniaturized potentiostat to amperiometrically detect oxygen concentration with carbon paste electrodes. Wireless power was employed to recharge the telemeter battery transcutaneously for potential lifetime monitoring. Rats were implanted with the telemeter in the peritoneal cavity and electrodes stereotaxically implanted into the brain (striatum or medulla oblongata). While the animals were living in their home cages the sensitivity to changes in oxygen was validated by repeatedly altering the inspired oxygen (10%, 100%, respectively) or a pharmacological stimulus (carbonic anhydrase inhibitor: acetazolamide 50mg/kg IP). Basal level of PO(2,BR) was monitored for 3weeks and showed good overall stability and good correlation to movement such as grooming. During hypoxia, PO(2,BR) decreased significantly by -51%±2% from baseline, whereas it increased by 34%±3% during hyperoxia. Following the systemic administration of acetazolamide, PO(2,BR) increased by 38%±4%. We propose this new technology provides a robust method to measure changes in oxygen concentration in specific areas of the brain, in conscious freely moving rats. The ability to track long term changes with disease progression or drug treatment may be enabled.

A high bandwidth fully implantable mouse telemetry system for chronic ECG measurement.

We report on the development of a novel system that enables the wireless transmission of high-bandwidth physiological data from a freely moving mouse. The system employs inductive power transfer (IPT) to continuously power a battery-less transmitter using an array of overlapping planar coils placed under the animal. This arrangement provides a minimum of 20 mW at all locations and orientations across the mouse cage by selecting a coil which will sufficiently power the transmitter. Coil selection is performed by feedback control across the 2.4 GHz wireless link. A device was constructed utilizing this novel IPT system and was used to capture high-fidelity electrocardiogram (ECG) signal sampled at 2 kHz in mice. Various attributes of the ECG signal such as QT, QRS, and PR intervals could be obtained with a high degree of accuracy. This system potentially provides lifetime continuous high bandwidth measurement of physiological signals from a fully implanted telemeter in a freely moving mouse.

Evaluation of the impact of implementation of a Medical Assessment and Planning Unit on length of stay.

OBJECTIVE: The Medical Assessment and Planning Unit (MAPU) model provides a multidisciplinary and 'front end loading' approach to acute medical care. The objective of this study was to evaluate the impact of a 10-bed MAPU in Royal Melbourne Hospital (RMH) on hospital length of stay. METHODS: A pre-post study design was used. Cases were defined as all general medical patients admitted to the RMH between 1 August 2003 and 31 January 2004. MAPU patients were defined as general medical patients who had been discharged from RMH MAPU unit as part of their RMH inpatient admission. Historical controls were defined as all general medical patients admitted to the RMH between 1 August 2002 and 31 January 2003. RESULTS: There was a reduction in median length of stay that did not reach statistical significance. During the study period, median emergency department length of stay for MAPU patients was 10.3 h compared with 13.2 h for non-MAPU patients who were admitted directly to general wards. CONCLUSIONS: The reductions in length of stay are likely to be of clinical significance at the emergency department (ED) level. The MAPU model also contributes to providing care appropriate care for older admitted patients.

Torrential upper gastrointestinal bleeding from 'downhill' oesophageal varices complicating long term central venous access for total parenteral nutrition.

Oesophageal varices usually develop in the setting of portal hypertension secondary to chronic liver disease. However, superior vena cava (SVC) obstruction can result in 'downhill' varices forming in the upper oesophagus. A case of torrential upper gastrointestinal bleeding from SVC obstruction due to chronic central venous access for home total parenteral nutrition is described. It is suggested that in patients presenting with gastrointestinal bleeding in the setting of SVC obstruction, 'downhill' varices should be suspected. The current literature is discussed regarding management of such varices. It is recommended that endoscopic variceal surveillance be carried out in patients with known SVC obstruction.

Exciton migration in rigid-rod conjugated polymers: an improved Förster model.

The dynamics of interchain and intrachain excitation energy transfer taking place in a polyindenofluorene endcapped with perylene derivatives is explored by means of ultrafast spectroscopy combined with correlated quantum-chemical calculations. The experimental data indicate faster exciton migration in films with respect to solution as a result of the emergence of efficient channels involving hopping between chains in close contact. These findings are supported by theoretical simulations based on an improved Forster model. Within this model, the rates are expressed according to the Fermi golden rule on the basis of (i) electronic couplings that take account of the detailed shape of the excited-state wave functions (through the use of a multicentric monopole expansion) and (ii) spectral overlap factors computed from the simulated acceptor absorption and donor emission spectra with explicit coupling to vibrations (considered within a displaced harmonic oscillator model); inhomogeneity is taken into account by assuming a distribution of chromophores with different conjugation lengths. The calculations predict faster intermolecular energy transfer as a result of larger electronic matrix elements and suggest a two-step mechanism for intrachain energy transfer with exciton hopping along the polymer backbone as the limiting step. Injecting the calculated hopping rates into a set of master equations allows the modeling of the dynamics of exciton transport along the polyindenofluorene chains and yields ensemble-averaged energy-transfer rates in good agreement with experiment.