Fast radio bursts (FRBs) are millisecond-duration radio transients
of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star ...magnetospheres
or relativistic shocks far from the central energy source
. Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters
or variable polarization angles in some other apparently one-off events
. Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks.
Gravitational waves are expected to be radiated by supermassive black hole binaries formed during galaxy mergers. A stochastic superposition of gravitational waves from all such binary systems would ...modulate the arrival times of pulses from radio pulsars. Using observations of millisecond pulsars obtained with the Parkes radio telescope, we constrained the characteristic amplitude of this background, Ac,yr, to be <1.0 × 10–15 with 95% confidence. This limit excludes predicted ranges for Ac,yr from current models with 91 to 99.7% probability. We conclude that binary evolution is either stalled or dramatically accelerated by galactic-center environments and that higher-cadence and shorter-wavelength observations would be more sensitive to gravitational waves.
Background
Delirium is common in elderly patients after surgery and is associated with poor outcomes. This study aimed to investigate the impact of intraoperative dexmedetomidine on the incidence of ...delirium in elderly patients undergoing major surgery.
Methods
This was a randomized double‐blind placebo‐controlled trial. Elderly patients (aged 60 years or more) scheduled to undergo major non‐cardiac surgery were randomized into two groups. Patients in the intervention group received a loading dose of dexmedetomidine 0·6 μg/kg 10 min before induction of anaesthesia followed by a continuous infusion (0·5 μg per kg per h) until 1 h before the end of surgery. Patients in the control group received volume‐matched normal saline in the same schedule. The primary outcome was the incidence of delirium during the first 5 days after surgery. Delirium was assessed with the Confusion Assessment Method (CAM) for non‐ventilated patients and CAM for the Intensive Care Unit for ventilated patients.
Results
In total, 309 patients who received dexmedetomidine and 310 control patients were included in the intention‐to‐treat analysis. The incidence of delirium within 5 days of surgery was lower with dexmedetomidine treatment: 5·5 per cent (17 of 309) versus 10·3 per cent (32 of 310) in the control group (relative risk (RR) 0·53, 95 per cent c.i. 0·30 to 0·94; P = 0·026). The overall incidence of complications at 30 days was also lower after dexmedetomidine (19·4 per cent (60 of 309) versus 26·1 per cent (81 of 310) for controls; RR 0·74, 0·55 to 0·99, P = 0·047).
Conclusion
Intraoperative dexmedetomidine halved the risk of delirium in the elderly after major non‐cardiac surgery. Registration number: ChiCTR‐IPR‐15007654 (
www.chictr.org.cn).
Antecedentes
El delirio después de la cirugía es frecuente en los pacientes de edad avanzada y se asocia con malos resultados. El objetivo de este estudio fue investigar el impacto de la administración intraoperatoria de dexmedetomidina en la incidencia de delirio en pacientes mayores sometidos a operaciones de cirugía mayor.
Métodos
Se trataba de un ensayo aleatorizado, doble ciego y controlado con placebo. Un total de 620 pacientes mayores (60 años o más) fueron programados para ser sometidos a intervenciones (no cardiacas) de cirugía mayor y se aleatorizaron a dos grupos. Los pacientes en el grupo de intervención recibieron una dosis de carga de dexmedetomidina (0,6 μg/kg, 10 minutos antes de la inducción anestésica) seguida de una infusión continua (0,5 μg/kg/h) hasta 1 h antes de la finalización de la cirugía. Los pacientes del grupo control recibieron el mismo volumen de suero salino siguiendo la misma pauta. El resultado principal era la incidencia de delirio durante los primeros 5 días postoperatorios. Para la valoración del delirio se utilizó el método para la evaluación de la confusión (Confusion Assessment Method, CAM) en pacientes no intubados y el CAM‐UCI para los pacientes intubados.
Resultados
En total, 309 pacientes que recibieron dexmedetomidina y 310 del grupo control se incluyeron en el análisis por intención de tratar. La incidencia de delirio durante los primeros 5 días tras la cirugía fue inferior en presencia de tratamiento con dexmedetomidina que en ausencia del mismo: 5,5% (17/309) versus 10,3% (32/310); riesgo relativo (RR) 0,53, i.c. del 95% 0,30‐0,94, P = 0,026. La incidencia global de complicaciones a los 30 días excluyendo el delirio también fue inferior en presencia que en ausencia de tratamiento con dexmedetomidina (19,4% (60/309) versus 26,1% (81/301), RR 0,74, i.c. del 95% 0,55‐0,99, P = 0,047).
Conclusión
La administración intraoperatoria de dexmedetomidina reduce la presencia de delirio en los pacientes mayores tras cirugía mayor no cardiaca.
In this RCT, intraoperative infusion of dexmedetomidine was found to reduce the rate of postoperative delirium and surgery‐related complications. The shortcomings of previous studies, such as study design and sample size, were amended, providing more robust evidence for clinical practice.
Halved the rate of delirium
Abstract Understanding the jitter noise resulting from single-pulse phase and shape variations is important for the detection of gravitational waves using pulsar timing arrays. We present ...measurements of the jitter noise and single-pulse variability of 12 millisecond pulsars that are part of the International Pulsar Timing Array sample using the Five-hundred-meter Aperture Spherical radio Telescope. We find that the levels of jitter noise can vary dramatically among pulsars. A moderate correlation with a correlation coefficient of 0.57 between jitter noise and pulse width is detected. To mitigate jitter noise, we perform matrix template matching using all four Stokes parameters. Our results reveal a reduction in jitter noise ranging from 6.7% to 39.6%. By performing longitude-resolved fluctuation spectrum analysis, we identify periodic intensity modulations in 10 pulsars. In PSR J0030+0451, we detect single pulses with energies more than 10 times the average pulse energy, suggesting the presence of giant pulses. We also observe a periodic mode-changing phenomenon in PSR J0030+0451. We examine the achievable timing precision by selecting a subset of pulses with a specific range of peak intensity, but no significant improvement in timing precision is achievable.
Experimental realization of a universal set of quantum logic gates is the central requirement for the implementation of a quantum computer. In an 'all-geometric' approach to quantum computation, the ...quantum gates are implemented using Berry phases and their non-Abelian extensions, holonomies, from geometric transformation of quantum states in the Hilbert space. Apart from its fundamental interest and rich mathematical structure, the geometric approach has some built-in noise-resilience features. On the experimental side, geometric phases and holonomies have been observed in thermal ensembles of liquid molecules using nuclear magnetic resonance; however, such systems are known to be non-scalable for the purposes of quantum computing. There are proposals to implement geometric quantum computation in scalable experimental platforms such as trapped ions, superconducting quantum bits and quantum dots, and a recent experiment has realized geometric single-bit gates in a superconducting system. Here we report the experimental realization of a universal set of geometric quantum gates using the solid-state spins of diamond nitrogen-vacancy centres. These diamond defects provide a scalable experimental platform with the potential for room-temperature quantum computing, which has attracted strong interest in recent years. Our experiment shows that all-geometric and potentially robust quantum computation can be realized with solid-state spin quantum bits, making use of recent advances in the coherent control of this system.
Highlights • Baicalin prevents depressive-like behaviors induced by CORT. • Baicalin reverses the increased mRNA and protein expression of SGK1 in the hippocampus induced by CORT. • Baicalin ...increases the hippocampal protein expression of 11β-HSD2, GRα and BDNF in CORT-treated mice.
The NAD(+)-dependent deacetylase, sirtuin 1 (SIRT1), has been recently been suspected to have a role in tumorigenesis. We investigated the expression of SIRT1 in pancreatic cancer and the effect of ...SIRT1-targeted RNA interference (RNAi) on cell proliferation and tumor formation in a pancreatic cancer cell line, PANC1. The expression of SIRT1 was investigated in 49 specimens of pancreatic cancer and adjacent normal pancreatic tissues. SIRT1 was overexpressed in pancreatic cancer tissues at both the mRNA and protein levels, with increased SIRT1 positivity associated with tumors from patients over 60 years old, tumors larger than 4 cm, higher TNM (extent of tumor (T), the extent of spread to lymph nodes (N), and presence of distant metastasis (M)) stage or the presence of lymph node or hepatic metastases. The PANC-1 was stably transfected with a SIRT1 small hairpin RNA (shRNA) expression plasmid and compared with untransfected and PANC-1-negative RNAi cells. Proliferation of PANC-1-SIRT1-RNAi cells was significantly reduced, accompanied by increased rates of apoptosis, G1 arrest and senescence. Furthermore, FOXO3a expression was markedly upregulated in PANC-1-SIRT1-RNAi cells, but no significant difference in p53 expression was observed. The invasive ability of PANC-1-SIRT1-RNAi cells was markedly reduced in vitro, which was linked to increased E-cadherin and reduced-MMP expression. Additionally, PANC-1-SIRT1-RNAi cells had a significantly reduced capacity to form tumors in vivo compared with untransfected and PANC-1-negative RNAi cells. These results suggest that SIRT1 may promote cell proliferation and tumor formation in pancreatic cancer, and downregulation of SIRT1 using shRNA could provide a novel therapeutic treatment.
Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances
. It has long been speculated that magnetars are the engine powering ...repeating bursts from FRB sources
, but no convincing evidence has been collected so far
. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft γ-ray bursts
. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft γ-ray/hard-X-ray flare
. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-γ-ray repeater (SGR) bursts were detected in γ-ray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.
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