Transfusion thresholds and beyond

Comment on Liberal transfusion strategy improves survival in perioperative but not in critically ill patients. A meta-analysis of randomised trials. [Br J Anaesth. 2015

Mechanical weed control strategies for grain amaranth (Amaranthus cruentus L.)

Received: January 25th, 2022 ; Accepted: April 5th, 2022 ; Published: April 19th, 2022 ; Correspondence: [email protected], no herbicide is registered for grain amaranth in Europe, the United States and South America. Hence, weed control must be addressed with alternative methods. Field trials were conducted in 2018 and 2019 in Central Italy by comparing some mechanical weed control treatments in grain amaranth (Amaranthus cruentus L.). In 2018, the five treatments were: untreated control (T118), cutter hoeing (T218), flat share cuts and one central duck foot tine (T318), flat share cuts and two central duck foot tines (T418), and three duck foot tines (T518). In 2019, the five treatments were: untreated control (T119), three duck foot tines (T219), flex tine harrowing (T319), flex tine harrowing plus finger weeding with red fingers (T419), and finger weeding with red fingers (T520). In 2018, amaranth was a successful competitor against weeds from 40 days after emergence (10 true leaf stage, corresponding to BBCH code 15). The competitive ability was showed by excellent seed yields averaging 1.2 t ha-1 , for all treatments. This feature was also confirmed to some degree in 2019. However, seed yield in 2019 was more strongly influenced by treatment as well as by the lower emergence of plants. All the mechanical methods employed can be effectively used for weed control in grain amaranth. Treatments with the flex tine harrower and finger weeder negatively affected the plant density at harvest, necessitating further optimization. However, combined mechanical strategies proved the most effective, especially in controlling dicot weeds. There is a need to optimize strategies, with mechanical equipment, to anticipate and improve the ground cover of amaranth. These strategies include selecting optimal plant density and the correct distancing between the rows for easier mechanical control

Quantum dynamics of a high-finesse optical cavity coupled with a thin semi-transparent membrane

We study the quantum dynamics of the cavity optomechanical system formed by a Fabry-Perot cavity with a thin vibrating membrane at its center. We first derive the general multimode Hamiltonian describing the radiation pressure interaction between the cavity modes and the vibrational modes of the membrane. We then restrict the analysis to the standard case of a single cavity mode interacting with a single mechanical resonator and we determine to what extent optical absorption by the membrane hinder reaching a quantum regime for the cavity-membrane system. We show that membrane absorption does not pose serious limitations and that one can simultaneously achieve ground state cooling of a vibrational mode of the membrane and stationary optomechanical entanglement with state-of-the-art apparatuses.Comment: 14 pages, 7 figure

Quantum dynamics of a vibrational mode of a membrane within an optical cavity

Optomechanical systems are a promising candidate for the implementation of quantum interfaces for storing and redistributing quantum information. Here we focus on the case of a high-finesse optical cavity with a thin vibrating semitransparent membrane in the middle. We show that robust and stationary optomechanical entanglement could be achieved in the system, even in the presence of nonnegligible optical absorption in the membrane. We also present some preliminary experimental data showing radiation-pressure induced optical bistability.Comment: 6 pages, 2 figures. Work presented at the conference QCMC 2010 held on 19-23 July 2010 at the University of Queensland, Brisbane, Australi

Optomechanically induced transparency in membrane-in-the-middle setup at room temperature

We demonstrate the analogue of electromagnetically induced transparency in a room temperature cavity optomechanics setup formed by a thin semitransparent membrane within a Fabry-P\'erot cavity. Due to destructive interference, a weak probe field is completely reflected by the cavity when the pump beam is resonant with the motional red sideband of the cavity. Under this condition we infer a significant slowing down of light of hundreds of microseconds, which is easily tuned by shifting the membrane along the cavity axis. We also observe the associated phenomenon of electromagnetically induced amplification which occurs due to constructive interference when the pump is resonant with the blue sideband.Comment: 5 pages, 4 figure

Optomechanical sideband cooling of a thin membrane within a cavity

We present an experimental study of dynamical back-action cooling of the fundamental vibrational mode of a thin semitransparent membrane placed within a high-finesse optical cavity. We study how the radiation pressure interaction modifies the mechanical response of the vibrational mode, and the experimental results are in agreement with a Langevin equation description of the coupled dynamics. The experiments are carried out in the resolved sideband regime, and we have observed cooling by a factor 350 We have also observed the mechanical frequency shift associated with the quadratic term in the expansion of the cavity mode frequency versus the effective membrane position, which is typically negligible in other cavity optomechanical devices.Comment: 15 pages, 7 figure

Frequency noise cancellation in optomechanical systems for ponderomotive squeezing

Ponderomotive squeezing of the output light of an optical cavity has been recently observed in the MHz range in two different cavity optomechanical devices. Quadrature squeezing becomes particularly useful at lower spectral frequencies, for example in gravitational wave interferometers, despite being more sensitive to excess phase and frequency noise. Here we show a phase/frequency noise cancellation mechanism due to destructive interference which can facilitate the production of ponderomotive squeezing in the kHz range and we demonstrate it experimentally in an optomechanical system formed by a Fabry-P\'{e}rot cavity with a micro-mechanical mirror.Comment: 11 pages, 9 figures. Physical explanation expanded. Modified figure

Bloodstream infections in patients with rectal colonization by Klebsiella pneumoniae producing different type of carbapenemases: a prospective, cohort study

Objective: To investigate the hypothesis that intestinal colonization by different types of carbapenemase-resistant Klebsiella pneumoniae (CR-Kp) leads to different risks for bloodstream infections (BSI) caused by the same colonizing organism. Methods: Prospective observational study including consecutive CR-Kp rectal carriers admitted to the Pisa University Hospital (December 2018 to December 2019). Patients underwent rectal swabbing with molecular testing for the different carbapenemases at hospital admission and during hospitalization. Rectal carriers were classified as: NDM, KPC, VIM and OXA-48. The primary end point was the rate of BSI by the same colonizing organism in each study group. A multivariate logistic regression analysis was performed to identify factors independently associated with the risk for BSI by the colonizing organism. Results: Of 677 rectal carriers, 382/677 (56.4%) were colonized by NDM, 247/677 (36.5%) by KPC, 39/677 (5.8%) by VIM and 9/677 (1.3%) by OXA-48. Dissemination of NDM-Kp was mostly sustained by ST147, while KPC-Kp belonged to ST512. A higher rate of BSI was documented in NDM rectal carriers compared with KPC rectal carriers (59/382, 15.4% versus 20/247, 8.1%, p 0.004). Incidence rates of BSI per 100 patients/month were significantly higher in the NDM group (22.33, 95% CI 17.26-28.88) than in the KPC group (9.56, 95% CI 6.17-14.82). On multivariate analysis, multi-site extraintestinal colonization, solid organ transplantation, invasive procedures, intravascular device, admission to intensive care unit, cephalosporin, fluoroquinolones and NDM rectal colonization (OR 3.27, 95% CI 1.73-6.18, p < 0.001) were independently associated with BSI. Conclusions: NDM-Kp was associated with increased risk of BSI compared with KPC-Kp. This finding seems to be strongly related to the high-risk clone ST147

Evaluation of a New Software Version of the FloTrac/Vigileo (Version 3.02) and a Comparison with Previous Data in Cirrhotic Patients Undergoing Liver Transplant Surgery

Abstract: BACKGROUND: Reliable cardiac output monitoring is particularly useful in the cirrhotic patient undergoing liver transplant surgery, because cirrhosis of the liver is associated with a vasodilated and high output state, known as cirrhotic cardiomyopathy, that challenges the reliability of pulse contour cardiac output technology. The contractility of the ventricle in cirrhosis is impaired, which is tolerated even though the ejection fraction and cardiac output are elevated because of the low peripheral resistance. However, during surgery the cirrhotic patient can decompensate because of the physiological changes and stress of surgery. Recently, we showed that the FloTrac/Vigileo (TM) failed to perform in cirrhotic patients undergoing transplant surgery. In response, the company upgraded their software. Therefore, we have assessed the accuracy and reliability of this new third-generation (version 3.02) FloTrac/Vigileo algorithm software in the same setting. METHODS: The cardiac index was measured simultaneously by single-bolus thermodilution (CI(TD)), using a pulmonary artery catheter, and pulse contour analysis, using the FloTrac/Vigileo (CI(V)). Readings were made at 10 time points during and after liver transplant surgery in 21 patients. Comparisons with data from our 2009 study, which used second-generation (version 01.10) software, were also made. RESULTS: Our new data show that version 3.02 software significantly reduced the adverse effect on pulse contour cardiac output reading bias in low peripheral resistance states, and thus improves the overall precision and trending ability of the system. Regression analysis between CI(TD) and CI(V) showed that the correlation was moderate (r = 0.67, 95% confidence interval, 0.40 to 0.86). The Bland and Altman analysis showed that bias was 0.4 L.min(-1).m(-2), and the percentage error was 52% (95% confidence interval, 49% to 55%). Trending ability of the new software also was improved but was still well below the current benchmarks. CONCLUSION: The new software (version 3.02) provided substantial improvements over the previous versions with better overall precision and trending ability. Further algorithm refinements will increase this technology's reliability to be extensively used in the highly complex setting of cirrhotic patients undergoing liver transplantation. (Anesth Analg 2011; 113: 515-22