Frustration, or the competition between interacting components of a network, is often responsible for the emergent complexity of many-body systems. For instance, frustrated magnetism is a hallmark of ...poorly understood systems such as quantum spin liquids, spin glasses, and spin ices, whose ground states can be massively degenerate and carry high degrees of quantum entanglement. Here, we engineer frustrated antiferromagnetic interactions between spins stored in a crystal of up to 16 trapped ¹⁷¹Yb⁺ atoms. We control the amount of frustration by continuously tuning the range of interaction and directly measure spin correlation functions and their coherent dynamics. This prototypical quantum simulation points the way toward a new probe of frustrated quantum magnetism and perhaps the design of new quantum materials.
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.
The optical design and performance of the recently opened 13A biological small‐angle X‐ray scattering (SAXS) beamline at the 3.0 GeV Taiwan Photon Source of the National Synchrotron Radiation ...Research Center are reported. The beamline is designed for studies of biological structures and kinetics in a wide range of length and time scales, from angstrom to micrometre and from microsecond to minutes. A 4 m IU24 undulator of the beamline provides high‐flux X‐rays in the energy range 4.0–23.0 keV. MoB4C double‐multilayer and Si(111) double‐crystal monochromators (DMM/DCM) are combined on the same rotating platform for a smooth rotation transition from a high‐flux beam of ∼4 × 1014 photons s−1 to a high‐energy‐resolution beam of ΔE/E ≃ 1.5 × 10−4; both modes share a constant beam exit. With a set of Kirkpatrick–Baez (KB) mirrors, the X‐ray beam is focused to the farthest SAXS detector position, 52 m from the source. A downstream four‐bounce crystal collimator, comprising two sets of Si(311) double crystals arranged in a dispersive configuration, optionally collimate the DCM (vertically diffracted) beam in the horizontal direction for ultra‐SAXS with a minimum scattering vector q down to 0.0004 Å−1, which allows resolving ordered d‐spacing up to 1 µm. A microbeam, of 10–50 µm beam size, is tailored by a combined set of high‐heat‐load slits followed by micrometre‐precision slits situated at the front‐end 15.5 m position. The second set of KB mirrors then focus the beam to the 40 m sample position, with a demagnification ratio of ∼1.5. A detecting system comprising two in‐vacuum X‐ray pixel detectors is installed to perform synchronized small‐ and wide‐angle X‐ray scattering data collections. The observed beamline performance proves the feasibility of having compound features of high flux, microbeam and ultra‐SAXS in one beamline.
The optical design and performance of the BioSAXS beamline at the Taiwan Photon Source are reported
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.
Two-dimensional (2D) materials have been studied extensively as monolayers, vertical or lateral heterostructures. To achieve functionalization, monolayers are often patterned using soft lithography ...and selectively decorated with molecules. Here we demonstrate the growth of a family of 2D materials that are intrinsically patterned. We demonstrate that a monolayer of PtSe
can be grown on a Pt substrate in the form of a triangular pattern of alternating 1T and 1H phases. Moreover, we show that, in a monolayer of CuSe grown on a Cu substrate, strain relaxation leads to periodic patterns of triangular nanopores with uniform size. Adsorption of different species at preferred pattern sites is also achieved, demonstrating that these materials can serve as templates for selective self-assembly of molecules or nanoclusters, as well as for the functionalization of the same substrate with two different species.
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
Worldwide, some 240 million people have chronic hepatitis B virus (HBV), with the highest rates of infection in Africa and Asia. Our understanding of the natural history of HBV infection and the ...potential for therapy of the resultant disease is continuously improving. New data have become available since the previous APASL guidelines for management of HBV infection were published in 2012. The objective of this manuscript is to update the recommendations for the optimal management of chronic HBV infection. The 2015 guidelines were developed by a panel of Asian experts chosen by the APASL. The clinical practice guidelines are based on evidence from existing publications or, if evidence was unavailable, on the experts’ personal experience and opinion after deliberations. Manuscripts and abstracts of important meetings published through January 2015 have been evaluated. This guideline covers the full spectrum of care of patients infected with hepatitis B, including new terminology, natural history, screening, vaccination, counseling, diagnosis, assessment of the stage of liver disease, the indications, timing, choice and duration of single or combination of antiviral drugs, screening for HCC, management in special situations like childhood, pregnancy, coinfections, renal impairment and pre- and post-liver transplant, and policy guidelines. However, areas of uncertainty still exist, and clinicians, patients, and public health authorities must therefore continue to make choices on the basis of the evolving evidence. The final clinical practice guidelines and recommendations are presented here, along with the relevant background information.
ABSTRACT
We report the phase-connected timing ephemeris, polarization pulse profiles, Faraday rotation measurements, and Rotating-Vector-Model (RVM) fitting results of 12 millisecond pulsars (MSPs) ...discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST survey (CRAFTS). The timing campaigns were carried out with FAST and Arecibo over 3 yr. 11 of the 12 pulsars are in neutron star–white dwarf binary systems, with orbital periods between 2.4 and 100 d. 10 of them have spin periods, companion masses, and orbital eccentricities that are consistent with the theoretical expectations for MSP–Helium white dwarf (He WD) systems. The last binary pulsar (PSR J1912−0952) has a significantly smaller spin frequency and a smaller companion mass, the latter could be caused by a low orbital inclination for the system. Its orbital period of 29 d is well within the range of orbital periods where some MSP–He WD systems have shown anomalous eccentricities, however, the eccentricity of PSR J1912−0952 is typical of what one finds for the remaining MSP–He WD systems.
A new group of thin film metallic glasses (TFMGs) have been reported to exhibit properties different from conventional crystalline metal films, though their bulk forms are already well-known for high ...strength and toughness, large elastic limits, and excellent corrosion and wear resistance because of their amorphous structure. In recent decades, bulk metallic glasses have gained a great deal of interest due to substantial improvements in specimen sizes. In contrast, much less attention has been devoted to TFMGs, despite the fact that they have many properties and characteristics, which are not readily achievable with other types of metallic or oxide films. Nevertheless, TFMGs have been progressively used for engineering applications and, thus, deserve to be recognized in the field of thin film coatings. This article will thus discuss both properties and applications of TFMGs including a review of solid-state amorphization upon annealing, the glass-forming ability improvement due to thin film deposition, and mechanical properties, including residual stress, hardness and microcompression, adhesion, and wear resistance. Potential applications and simulations will also be discussed.
Ultrahigh energy neutrinos are interesting messenger particles since, if detected, they can transmit exclusive information about ultrahigh energy processes in the Universe. These particles, with ...energies above 10 super(16)eV , interact very rarely. Therefore, detectors that instrument several gigatons of matter are needed to discover them. The ARA detector is currently being constructed at the South Pole. It is designed to use the Askaryan effect, the emission of radio waves from neutrino-induced cascades in the South Pole ice, to detect neutrino interactions at very high energies. With antennas distributed among 37 widely separated stations in the ice, such interactions can be observed in a volume of several hundred cubic kilometers. Currently three deep ARA stations are deployed in the ice, of which two have been taking data since the beginning of 2013. In this article, the ARA detector "as built" and calibrations are described. Data reduction methods used to distinguish the rare radio signals from overwhelming backgrounds of thermal and anthropogenic origin are presented. Using data from only two stations over a short exposure time of 10 months, a neutrino flux limit of 1.5x10 super(-6)GeV/cm super(2)/s/sr is calculated for a particle energy of 10 super(18)eV , which offers promise for the full ARA detector.
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