Freeze casting is a promising technique to fabricate porous materials with complex pore shapes and component geometries. This review is aimed to elaborate the fundamental principles of the porous ...microstructure evolution and critical factors that influence the fundamental physics involved in freeze casting of particulate suspensions. The discussion separately analyses homogeneous and directional freeze casting for both aqueous and non-aqueous systems. The effects of additives, freezing conditions, suspension solids loading and particle size on pore shape, size and morphology evolution are discussed. Special techniques based on modified freeze casting, such as freeze tape casting, double sided freeze casting and field directed freeze casting, are also included.
Summary Background Immobilisation predicts adverse outcomes in patients in the surgical intensive care unit (SICU). Attempts to mobilise critically ill patients early after surgery are frequently ...restricted, but we tested whether early mobilisation leads to improved mobility, decreased SICU length of stay, and increased functional independence of patients at hospital discharge. Methods We did a multicentre, international, parallel-group, assessor-blinded, randomised controlled trial in SICUs of five university hospitals in Austria (n=1), Germany (n=1), and the USA (n=3). Eligible patients (aged 18 years or older, who had been mechanically ventilated for <48 h, and were expected to require mechanical ventilation for ≥24 h) were randomly assigned (1:1) by use of a stratified block randomisation via restricted web platform to standard of care (control) or early, goal-directed mobilisation using an inter-professional approach of closed-loop communication and the SICU optimal mobilisation score (SOMS) algorithm (intervention), which describes patients’ mobilisation capacity on a numerical rating scale ranging from 0 (no mobilisation) to 4 (ambulation). We had three main outcomes hierarchically tested in a prespecified order: the mean SOMS level patients achieved during their SICU stay (primary outcome), and patient's length of stay on SICU and the mini-modified functional independence measure score (mmFIM) at hospital discharge (both secondary outcomes). This trial is registered with ClinicalTrials.gov ( NCT01363102 ). Findings Between July 1, 2011, and Nov 4, 2015, we randomly assigned 200 patients to receive standard treatment (control; n=96) or intervention (n=104). Intention-to-treat analysis showed that the intervention improved the mobilisation level (mean achieved SOMS 2·2 SD 1·0 in intervention group vs 1·5 0·8 in control group, p<0·0001), decreased SICU length of stay (mean 7 days SD 5–12 in intervention group vs 10 days 6–15 in control group, p=0·0054), and improved functional mobility at hospital discharge (mmFIM score 8 4–8 in intervention group vs 5 2–8 in control group, p=0·0002). More adverse events were reported in the intervention group (25 cases 2·8%) than in the control group (ten cases 0·8%); no serious adverse events were observed. Before hospital discharge 25 patients died (17 16% in the intervention group, eight 8% in the control group). 3 months after hospital discharge 36 patients died (21 22% in the intervention group, 15 17% in the control group). Interpretation Early, goal-directed mobilisation improved patient mobilisation throughout SICU admission, shortened patient length of stay in the SICU, and improved patients’ functional mobility at hospital discharge. Funding Jeffrey and Judy Buzen.
Precise comparisons of the fundamental properties of matter-antimatter conjugates provide sensitive tests of charge-parity-time (CPT) invariance, which is an important symmetry that rests on basic ...assumptions of the standard model of particle physics. Experiments on mesons, leptons and baryons have compared different properties of matter-antimatter conjugates with fractional uncertainties at the parts-per-billion level or better. One specific quantity, however, has so far only been known to a fractional uncertainty at the parts-per-million level: the magnetic moment of the antiproton, . The extraordinary difficulty in measuring with high precision is caused by its intrinsic smallness; for example, it is 660 times smaller than the magnetic moment of the positron. Here we report a high-precision measurement of in units of the nuclear magneton μ
with a fractional precision of 1.5 parts per billion (68% confidence level). We use a two-particle spectroscopy method in an advanced cryogenic multi-Penning trap system. Our result = -2.7928473441(42)μ
(where the number in parentheses represents the 68% confidence interval on the last digits of the value) improves the precision of the previous best measurement by a factor of approximately 350. The measured value is consistent with the proton magnetic moment, μ
= 2.792847350(9)μ
, and is in agreement with CPT invariance. Consequently, this measurement constrains the magnitude of certain CPT-violating effects to below 1.8 × 10
gigaelectronvolts, and a possible splitting of the proton-antiproton magnetic moments by CPT-odd dimension-five interactions to below 6 × 10
Bohr magnetons.
Although patients with sleep apnea (SA) are considered to be at increased risk for postoperative complications, evidence supporting increased risk of perioperative pulmonary morbidity is limited. The ...objective of this study, therefore, was to analyze perioperative demographics and pulmonary outcomes of patients with SA after orthopedic and general surgical procedures using a population-based sample. We hypothesized that SA is an independent risk factor for perioperative pulmonary complications, thus providing a basis for an increase in the utilization of resources, including intensive monitoring and development of strategies to prevent and treat these events.
National Inpatient Sample data for each year between 1998 and 2007 were accessed. Orthopedic and general surgical procedures were included and discharges with a diagnosis code for SA were identified. Patients with the diagnosis of SA were matched to those without the disease based on demographic variables using the propensity scoring method. Aspiration pneumonia, adult respiratory distress syndrome (ARDS), pulmonary embolism (PE), and the need for intubation and mechanical ventilation were the primary outcomes. Odds ratio (OR) and absolute risk reduction along with 95% confidence interval were reported.
We identified 2,610,441 entries for orthopedic and 3,441,262 for general surgical procedures performed between 1998 and 2007. Of those, 2.52% and 1.40%, respectively, carried a diagnosis of SA. Patients with SA developed pulmonary complications more frequently than their matched controls after both orthopedic and general surgical procedures, respectively (i.e., aspiration pneumonia: 1.18% vs 0.84% and 2.79% vs 2.05%; ARDS: 1.06% vs 0.45% and 3.79% vs 2.44%; intubation/mechanical ventilation: 3.99% vs 0.79% and 10.8% vs 5.94%, all P values <0.0001). Comparatively, PE was more frequent in SA patients after orthopedic procedures (0.51% vs 0.42%, P = 0.0038) but not after general surgical procedures (0.45% vs 0.49%, P = 0.22). SA was associated with a significantly higher adjusted OR of developing pulmonary complications after both orthopedic and general surgical procedures, respectively, with the exception of PE (OR for aspiration pneumonia: 1.41 1.35, 1.47 and 1.37 1.33, 1.41; for ARDS: 2.39 2.28, 2.51 and 1.58 1.54, 1.62; for PE: OR 1.22 1.15, 1.29 and 0.90 0.84, 0.97; for intubation/mechanical ventilation: 5.20 5.05, 5.37 and 1.95 1.91, 1.98).
SA is an independent risk factor for perioperative pulmonary complications. Our results may be used for hypothesis generation for clinical studies targeted to improve perioperative outcomes in this patient population.
Invariance under the charge, parity, time-reversal (CPT) transformation is one of the fundamental symmetries of the standard model of particle physics. This CPT invariance implies that the ...fundamental properties of antiparticles and their matter-conjugates are identical, apart from signs. There is a deep link between CPT invariance and Lorentz symmetry--that is, the laws of nature seem to be invariant under the symmetry transformation of spacetime--although it is model dependent. A number of high-precision CPT and Lorentz invariance tests--using a co-magnetometer, a torsion pendulum and a maser, among others--have been performed, but only a few direct high-precision CPT tests that compare the fundamental properties of matter and antimatter are available. Here we report high-precision cyclotron frequency comparisons of a single antiproton and a negatively charged hydrogen ion (H(-)) carried out in a Penning trap system. From 13,000 frequency measurements we compare the charge-to-mass ratio for the antiproton (q/m)p- to that for the proton (q/m)p and obtain (q/m)p-/(q/m)p − 1 =1(69) × 10(-12). The measurements were performed at cyclotron frequencies of 29.6 megahertz, so our result shows that the CPT theorem holds at the atto-electronvolt scale. Our precision of 69 parts per trillion exceeds the energy resolution of previous antiproton-to-proton mass comparisons as well as the respective figure of merit of the standard model extension by a factor of four. In addition, we give a limit on sidereal variations in the measured ratio of <720 parts per trillion. By following the arguments of ref. 11, our result can be interpreted as a stringent test of the weak equivalence principle of general relativity using baryonic antimatter, and it sets a new limit on the gravitational anomaly parameter of |α − 1| < 8.7 × 10(-7).
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
The Antiproton Decelerator (AD) facility of CERN began operation in 1999 to serve experiments for studies of CPT invariance by precision laser and microwave spectroscopy of antihydrogen (H¯) and ...antiprotonic helium (p¯He+) atoms. The first 12 years of AD operation saw cold H¯ synthesized by overlapping clouds of positrons (e+) and antiprotons (p¯) confined in magnetic Penning traps. Cold H¯ was also produced in collisions between Rydberg positronium (Ps) atoms and p¯. Ground-state H¯ was later trapped for up to ∼1000 s in a magnetic bottle trap, and microwave transitions excited between its hyperfine levels. In the p¯He+ atom, deep ultraviolet transitions were measured to a fractional precision of (2.3–5)×10−9 by sub-Doppler two-photon laser spectroscopy. From this the antiproton-to-electron mass ratio was determined as Mp¯/me=1836.1526736(23), which agrees with the p value known to a similar precision. Microwave spectroscopy of p¯He+ yielded a measurement of the p¯ magnetic moment with a precision of 0.3%. More recently, the magnetic moment of a single p¯ confined in a Penning trap was measured with a higher precision, as μp¯=−2.792845(12)μnucl in nuclear magnetons. Other results reviewed here include the first measurements of the energy loss (−dE/dx) of 1–100 keV p¯ traversing conductor and insulator targets; the cross sections of low-energy (<10 keV) p¯ ionizing atomic and molecular gas targets; and the cross sections of 5 MeV p¯ annihilating on various target foils via nuclear collisions. The biological effectiveness of p¯ beams destroying cancer cells was measured as a possible method for radiological therapy. New experiments under preparation attempt to measure the gravitational acceleration of H¯ or synthesize H¯+. Several other future experiments will also be briefly described.
Expertise in airway management is a vital skill for any provider caring for critically ill patients. A growing body of literature has identified the stark difference in periprocedural outcomes of ...elective intubation in the operating room when compared with emergency intubation in the ICU. A number of strategies to reduce the morbidity and mortality associated with airway management in the critically ill have been described. In this review, we provide an updated framework for airway assessment before direct laryngoscopy and video laryngoscopy, and use of newer pharmacologic agents; comment on current concepts in tracheal intubation in the ICU; and address human factors around critical decision-making during ICU airway management.
One of the fundamental properties of the proton is its magnetic moment, µp. So far µp has been measured only indirectly, by analysing the spectrum of an atomic hydrogen maser in a magnetic field. ...Here we report the direct high-precision measurement of the magnetic moment of a single proton using the double Penning-trap technique. We drive proton-spin quantum jumps by a magnetic radio-frequency field in a Penning trap with a homogeneous magnetic field. The induced spin transitions are detected in a second trap with a strong superimposed magnetic inhomogeneity. This enables the measurement of the spin-flip probability as a function of the drive frequency. In each measurement the proton's cyclotron frequency is used to determine the magnetic field of the trap. From the normalized resonance curve, we extract the particle's magnetic moment in terms of the nuclear magneton: μp = 2.792847350(9)μN. This measurement outperforms previous Penning-trap measurements in terms of precision by a factor of about 760. It improves the precision of the forty-year-old indirect measurement, in which significant theoretical bound state corrections were required to obtain µp, by a factor of 3. By application of this method to the antiproton magnetic moment, the fractional precision of the recently reported value can be improved by a factor of at least 1,000. Combined with the present result, this will provide a stringent test of matter/antimatter symmetry with baryons.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Lumbar drain placement with cerebrospinal fluid (CSF) drainage is an effective adjunct for reducing the risk of spinal cord ischemia in patients undergoing complex aortic aneurysm repair. However, ...lumbar drain placement is a challenging procedure with potential for significant complications. We sought to characterize complications of lumbar drain placement in a large, single-center experience of patients who underwent fenestrated or branched endovascular aneurysm repair (F/BEVAR).
All patients who underwent F/BEVAR and attempted lumbar drain placement from 2010 to 2019 were retrospectively reviewed. All lumbar drains were placed by four cardiovascular anesthesiologists who compose the complex aortic anesthesia team. Lumbar drain placement was guided by a set protocol and used whenever the aortic stent graft coverage was planned to extend more proximal than 40 mm above the celiac artery. Details relating to lumbar drain placement, management, and frequency and type of associated complications were characterized.
During the study period, 256 patients underwent F/BEVAR, of whom 100 (39%) were planned for lumbar drain placement. Successful placement occurred in 98 (98%) of the cases. All lumbar drains were placed before induction of general anesthesia, using fluoroscopy guidance in 28 cases (28%). The most common level of placement was L4-5 (n = 42 42%). The majority (n = 82 82%) were left in place ≤48 hours; 21% were removed during the first 24 hours, and 61% were removed between 24 and 48 hours. Nonfunctionality was the most common complication, occurring in 16 (16%) patients. Catheter dislodgment or fracture, CSF leak, and postdural puncture headache were observed in 4 (4%), 7 (7%), and 4 (4%) patients, respectively. The most common bleeding complication was the presence of asymptomatic blood in the CSF (n = 11 11%), whereas subarachnoid hemorrhage combined with intraventricular hemorrhage occurred in three patients (3%); none of these patients required surgical drainage or intervention. No infectious complications were observed.
Lumbar drain placement for CSF drainage is a commonly employed adjunct to prevent spinal cord ischemia in F/BEVAR. Our experience demonstrates that lumbar drain placement can be performed successfully but is associated with a significant rate of nonfunctionality and a diverse range of complications that, fortunately, do not commonly have significant long-term sequelae.
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Astrophysical observations indicate that there is roughly five times more dark matter in the Universe than ordinary baryonic matter
, and an even larger amount of the Universe's energy content is ...attributed to dark energy
. However, the microscopic properties of these dark components remain unknown. Moreover, even ordinary matter-which accounts for five per cent of the energy density of the Universe-has yet to be understood, given that the standard model of particle physics lacks any consistent explanation for the predominance of matter over antimatter
. Here we present a direct search for interactions of antimatter with dark matter and place direct constraints on the interaction of ultralight axion-like particles (dark-matter candidates) with antiprotons. If antiprotons have a stronger coupling to these particles than protons do, such a matter-antimatter asymmetric coupling could provide a link between dark matter and the baryon asymmetry in the Universe. We analyse spin-flip resonance data in the frequency domain acquired with a single antiproton in a Penning trap
to search for spin-precession effects from ultralight axions, which have a characteristic frequency governed by the mass of the underlying particle. Our analysis constrains the axion-antiproton interaction parameter to values greater than 0.1 to 0.6 gigaelectronvolts in the mass range from 2 × 10
to 4 × 10
electronvolts, improving the sensitivity by up to five orders of magnitude compared with astrophysical antiproton bounds. In addition, we derive limits on six combinations of previously unconstrained Lorentz- and CPT-violating terms of the non-minimal standard model extension
.
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