Explore the vast range of titles available.

The rotation of a star and the revolutions of its planets are not necessarily aligned. This article reviews the measurement techniques, key findings, and theoretical interpretations related to the obliquities (spin–orbit angles) of planet-hosting stars. The best measurements are for stars with short-period giant planets, which have been found on prograde, polar, and retrograde orbits. It seems likely that dynamical processes such as planet–planet scattering and secular perturbations are responsible for tilting the orbits of close-in giant planets, just as those processes are implicated in exciting orbital eccentricities. The observed dependence of the obliquity on orbital separation, planet mass, and stellar structure suggests that in some cases, tidal dissipation damps a star’s obliquity within its mainsequence lifetime. The situation is not as clear for stars with smaller or wider-orbiting planets. Although the earliest measurements of such systems tended to find low obliquities, some glaring exceptions are now known in which the star’s rotation is misaligned with respect to the coplanar orbits of multiple planets. In addition, statistical analyses based on projected rotation velocities and photometric variability have found a broad range of obliquities for F-type stars hosting compact multiple-planet systems. The results suggest it is unsafe to assume that stars and their protoplanetary disks are aligned. Primordial misalignments might be produced by neighboring stars or more complex events that occur during the epoch of planet formation.

We review the use of young low mass stars and protostars, or young stellar objects (YSOs), as tracers of star formation. Observations of molecular clouds at visible, infrared, radio and X-ray wavelengths can identify and characterize the YSOs populating these clouds, with the ability to detect deeply embedded objects at all evolutionary stages. Surveys with the Spitzer, Herschel, XMM-Newton and Chandra space telescopes have measured the spatial distribution of YSOs within a number of nearby (<2.5 kpc) molecular clouds, showing surface densities varying by more than three orders of magnitude. These surveys have been used to measure the spatially varying star formation rates and efficiencies within clouds, and when combined with maps of the molecular gas, have led to the discovery of star-forming relations within clouds. YSO surveys can also characterize the structures, ages, and star formation histories of embedded clusters, and they illuminate the relationship of the clusters to the networks of filaments, hubs and ridges in the molecular clouds from which they form. Measurements of the proper motions and radial velocities of YSOs trace the evolving kinematics of clusters from the deeply embedded phases through gas dispersal, providing insights into the factors that shape the formation of bound clusters. On 100 pc scales that encompass entire star-forming complexes, Gaia is mapping the young associations of stars that have dispersed their natal gas and exist alongside molecular clouds. These surveys reveal the complex structures and motions in associations, and show evidence for supernova driven expansions. Remnants of these associations have now been identified by Gaia, showing that traces of star-forming structures can persist for a few hundred million years.

In this review/tutorial we explore planetary nebulae as a stage in the evolution of low-to-intermediate-mass stars, as major contributors to the mass and chemical enrichment of the interstellar medium, and as astrophysical laboratories. We discuss many observed properties of planetary nebulae, placing particular emphasis on element abundance determinations and comparisons with theoretical predictions. Dust and molecules associated with planetary nebulae are considered as well. We then examine distances, binarity, and planetary nebula morphology and evolution. We end with mention of some of the advances that will be enabled by future observing capabilities.

Magnetohydrodynamic (MHD) turbulence is a crucial component of the current paradigms of star formation, dynamo theory, particle transport, magnetic reconnection, and evolution of structure in the interstellar medium (ISM) of galaxies. Despite the importance of turbulence to astrophysical fluids, a full theoretical framework based on solutions to the Navier–Stokes equations remains intractable. Observations provide only limited line-of-sight information on densities, temperatures, velocities, and magnetic field strengths, and therefore directly measuring turbulence in the ISM is challenging. A statistical approach has been of great utility in allowing comparisons of observations, simulations, and analytic predictions. In this review article, we address the growing importance of MHD turbulence in many fields of astrophysics and review statistical diagnostics for studying interstellar and interplanetary turbulence. In particular, we will review statistical diagnostics and machine learning algorithms that have been developed for observational data sets in order to obtain information about the turbulence cascade, fluid compressibility (sonic Mach number), and magnetization of fluid (Alfvénic Mach number). These techniques have often been tested on numerical simulations of MHD turbulence, which may include the creation of synthetic observations, and are often formulated on theoretical expectations for compressible magnetized turbulence. We stress the use of multiple techniques, as this can provide a more accurate indication of the turbulence parameters of interest. We conclude by describing several open-source tools for the astrophysical community to use when dealing with turbulence.

Awake breast surgery combines the reduction of hospitalization, postoperative stress, and postoperative lymphopenia, furthermore local anaesthesia and peripheral nerve block provide better analgesia during glandular displacement techniques, as during oncoplastic and axillary surgery. COVID-19 outbreak determined a strong effect on clinical practice worldwide1 and novel approach as awake breast surgery could combine fast track surgery and cross-infection reduction with an optimization of resources and resource optimization in terms of spaces and economic savings with shorter hospital stays.Fast track awake breast surgery provides a reduction of operative room time length of stay and potentially surgical treatment for a wider number of oncological patients.Costa et al proposed, to perform regional anaesthesia for breast procedures, a combination of three techniques: Pecs II block to cover muscles, axilla and lateral cutaneous branches of intercostal nerves (reliably from T2 to T4), erector spinae block block to cover lateral cutaneous branches from T4 to T7 and parasternal block or transversus thoracic muscle plane block to cover anterior cutaneous branches.The introduction of erector spinae block in breast surgery, represents an alternative to general anaesthesia and locoregional conventional techniques, like epidural anaesthesia or paravertebral block in oncological breast surgery, especially in high-risk patients.Santonastaso et al, wonder if the secret to obtaining perfect anaesthesia/analgesia for radical mastectomy procedures associated with sentinel lymph node biopsy, when we need to avoid general anaesthesia, could be the association of multiple techniques between Pecs, Serratus Anterior Block and Erector Spinae Block. More randomized trials are required to provide a certain answer to this question.ReferencesVanni G, Pellicciaro M, Materazzo M, et al. Awake breast cancer surgery: strategy in the beginning of COVID-19 emergency. Breast Cancer 2021;28:137–144.Costa F, Strumia A, Remore LM, Pascarella G, Del Buono R, Tedesco M, et al. Breast surgery analgesia: another perspective for PROSPECT guidelines. Anaesthesia 2020;75:1404–5.Santonastaso D, Dechiara A, Bagaphou CT, Cittadini A, Marsigli F, Russo E, Agnoletti V. Erector spinae plane block associated to serratus anterior plane block for awake radical mastectomy in a patient with extreme obesity. Minerva Anestesiologica 2021 June;87(6):734–6.

University of Nebraska Medical Center, USAInadequate perioperative pain control delays postoperative mobilization, and may lead to development of chronic postoperative pain, amplified cardiac and pulmonary complications, and increased morbidity and mortality.1 Even though opioids are still widely used,2 more information on their misuse, limitations and side-effects is becoming available, including risk of dependence and opioid-induced hyperalgesia (OIH).3 Multimodal analgesia has been defined as the use of two or more analgesics or techniques that target different mechanisms or pathways in the nociceptive system.4 As drugs are combined, lower doses of each class can be given, thereby lowering the side effects of each individual drug, but increasing overall efficacy.5,6 Drugs commonly used in this framework include acetaminophen, non-steroidal anti-inflammatory drugs (NSAID) or cyclo-oxygenase-2 inhibitors, dexamethasone, gabapentin, clonidine, dexmedetomidine, intravenous lidocaine, magnesium and ketamine. When timed correctly, however, regional anesthesia remains the best and most powerful opioid-sparing technique for many indications.ReferencesGerbershagen HJ, Aduckathil S, van Wijck AJ, et al. Pain intensity on the first day after surgery: a prospective cohort study comparing 179 surgical procedures. Anesthesiology 2013;118:934–44.Ladha KS, Patorno E, Huybrechts KF, et al. Variations in the Use of Perioperative Multimodal Analgesic Therapy. Anesthesiology 2016;124:837–45.Wu CL, Raja SN. Treatment of acute postoperative pain. Lancet 2011;377:2215–25.Manworren RC. Multimodal pain management and the future of a personalized medicine approach to pain. AORN J 2015;101:308–14; quiz 15–8.Kehlet H, Dahl JB. The value of ‘multimodal’ or ‘balanced analgesia’ in postoperative pain treatment. Anesth Analg 1993;77:1048–56.Buvanendran A, Kroin JS. Multimodal analgesia for controlling acute postoperative pain. Curr Opin Anaesthesiol 2009;22:588–93.

Labor is one of the most intense and painful conditions requiring analgesia.1 Neuraxial anesthesia is the gold standard to provide effective, safe and reliable pain relief during labor and delivery.2 Numerous neuraxial techniques exist such as spinal anesthesia, traditional epidural (EPL), combined spinal-epidural (CSE) and dural puncture epidural (DPE).3 Over time, various refinements have been made to optimize the efficacy of the traditional labor epidural. Modifications include the type of neuraxial technique chosen, local anesthetic (LA) concentration and volume, varying strategies for initiation and maintenance of analgesia with different pump delivery systems and addition of adjuncts to LA (most commonly lipophilic opioids).4 The simplest but likely least used technique is spinal anesthesia. This single shot technique is used when rapid onset of analgesia is required, and delivery is expected to occur within an hour (of administration).3 Although quick and effective, there is no means to supplement analgesia once the spinal effect wears off and in the event that anesthesia is required a repeat single shot spinal, epidural or general aesthesia may be necessary.3 Lumbar epidural is the gold standard against which other pain relief measures are evaluated for labor analgesia. 2 The epidural space is identified with the loss of resistance technique and a catheter is inserted into the epidural space. Local anesthetic (with or without adjuvants) is delivered to the epidural space via the catheter.3 Epidural medication can be administered in various ways: manual boluses by the physician, continuous infusion (CEI), patient controlled epidural anesthesia (PCEA), programmed intermittent epidural boluses (PIEB) or a combination of these.4 Although safe and reliable, time to onset of analgesia is relatively slow.5 There may be limited sacral spread of medication, resulting in inadequate analgesia in the second stage of labor. Repeated epidural top-ups may result in large volumes of local anesthetic being given which increases the risk of motor blockade.6 7 In the CSE technique, the dura is intentionally punctured to allow administration of intrathecal medication. The epidural space is located with the loss of resistance technique. Thereafter, a small gauge spinal needle is used to puncture the dura in a needle-through-needle technique. Free flow of cerebrospinal fluid (CSF) confirms correct identification of both the spinal and epidural spaces and accurate midline placement. Intrathecal medication is administered before insertion of the epidural catheter. Maintenance analgesia is provided via the catheter. CSE has a much faster onset time and provides a reliable sacral block due to intrathecal medication when compared to EPL.8 The rate of unilateral and inadequate blocks is lower and fewer physician top-ups are required. This is possibly due to translocation of epidural medication to the intrathecal space via the dural puncture.3 Although CSE allows for rapid pain relief, the sudden decrease in maternal catecholamines may result in uterine hypertonus and fetal bradycardia.9 Other side effects such as maternal hypotension and pruritis may also occur.10 Due to the intrathecal medication, the epidural catheter cannot be immediately tested to exclude intrathecal, intravascular or malpositioned catheters.The DPE was first described by Suzuki et al .11 in a cohort of abdominal surgery patients. As with CSE, the epidural space is located with the loss of resistance technique. The dura is then punctured with a small gauge spinal needle, but no intrathecal medication is administered. It is hypothesised that medication administered in the epidural space will move via the dural puncture into the intrathecal space allowing for faster onset of analgesia, better sacral spread, less unilateral block and lower rate of motor block compared to EPL.6 As no intrathecal medication is given the unwanted side effects such as uterine hypertonus, fetal bradycardia, maternal hypotension and pruritis are minimized.9 12 As the dura is punctured and CSF visualised, confirmation of midline placement is made and a test dose can be administered to rule out an intrathecal or intravascular catheter if desired.13 Thus, the DPE technique proposed to offer the ‘best of both worlds’ providing most of the benefits of the CSE technique without the unwanted side effects, but a faster and more reliable block when compared to EPL. However, the benefits have not consistently been confirmed in the literature when DPE is compared to EPL or CSE due to heterogenous results.Three reviews conducted in 2018 and 2019 by Layera et al.14, Gunaydin et al.15 and Heesen et al.13 were unable to provide clear evidence of benefit when DPE was compared to EPL. However, some helpful conclusions could be drawn. DPE offered a more reliable benefit if a 25 gauge(G) spinal needle was used as opposed to the smaller 26G and 27G needles. This was shown by Cappiello et al.6 and Chau et al.16 with significantly decreased onset times, improved sacral block, decreased unilateral block and decreased top-ups in the DPE groups. A 27G needle for the dural puncture was used in two trials. Firstly, Thomas et al.12 found no difference in quality of analgesia evidenced by no difference in catheter manipulation rates, sacral root sparing, unilateral block, peak block level, number of top-up doses and LA consumption. A higher incidence of dry taps also occurred. In contrast, Yadav et al.17 observed some benefits noting lower visual analogue scale (VAS) scores at 5 and 10 minutes (p<0.008), faster onset time and improved analgesia quality (p<0.05). However, there was no difference in the time to first top up request, LA consumption and duration of labor.17 Wilson et al.5 used a 26G needle for dural puncture. They found although time to VAS <10 was shorter in the DPE group, the percentage of patients with adequate labor analgesia at 10 minutes did not differ between groups.5 No differences in complications or post dural puncture headaches (PDPH) were noted in any studies, however due to small sample sizes, complications occurring less frequently may not have been identified.14 All trials used varying types, concentrations and volumes of LA which made comparison of results challenging.14 Three additional randomized control trials have been conducted since these reviews, but again heterogenous results were found. Two of the trials have incorporated the use of PIEB delivery systems found to be more effective18 and possibly better suited for use with DPB. The proposed mechanism is that during the administration of a LA bolus, pressure within the epidural space will increase thus facilitating movement of medication into the intrathecal space.Song et al.19 compared 3 groups: DPE combined with PIEB, EPL combined with CEI and EPL combined with PIEB including a total of 116 patients. A 25G needle was used for dural puncture. The primary outcome was time to adequate analgesia. As hypothesized, faster onset of analgesia and lower LA consumption was noted in the DPE + PIEB group. Reliable sacral block was also achieved. The incidence of side effects including pruritis, PDPH and maternal hypotension were comparable in all groups. Despite these findings, no difference in maternal satisfaction was found. Unfortunately, due to the lack of a fourth group (EPL and PIEB) in this study, the effect of the PIEB itself is unclear. The extent to which the DPE alone contributed to the favourable outcomes cannot be isolated from the possible effect of the PIEB.20 Bakhet21conducted a study comparing EPL, DPE and CSE combined with a loading dose followed by PCEA in 120 parturients. A 25G needle was used for dural puncture. Primary outcome was mean hourly LA consumption. CSE outperformed both DPE and EPL with regards to LA consumption, time to onset of analgesia, numeric pain rating scale (NPRS) and time to achieve T10 block. There were no significant differences between the DPE and EPL for these observations. Occurrence of motor blockade, side effects and maternal satisfaction were comparable amongst all three groupsMost recently, Tan et al.22 has reported results from a double-blinded randomized controlled trial comparing DPE to EPL in 132 obese parturients. They suggested that the DPE technique may be useful in this patient population as the dural puncture would confirm midline placement resulting in a lower failed epidural rate. Dural puncture was made with a 25G spinal needle and after an initial loading dose, PIEB with a PCEA function provided maintenance analgesia. The primary outcome was a composite of: (1) asymmetrical block, (2) epidural top-ups, (3) catheter adjustments, (4) catheter replacement and (5) failed conversion to regional anesthesia for cesarean section. No significant difference was found for the primary composite outcome between the two groups. However, the authors acknowledge that the confidence intervals were wide and contained potentially clinically relevant differences. There were also no differences in the secondary outcomes including motor block, LA consumption, top-ups, side effects and maternal satisfaction.One possible explanation for continued conflicting results may be that the mechanisms determining flux through the meninges rely on multiple factors. The size of the dural hole is an important determinant as shown by Bernards et al.23, where more morphine and lidocaine crossed the dural orifice when the dura was pierced with an 18G versus 24G needle. This would explain why less favourable results were seen in some studies with 26G and 27G spinal needles.5 12 Other important factors include: total epidural drug mass and inherent rate of drug transfer through intact meninges.14 23 24 25 A greater effect is seen with medications with an inherently slow diffusion rate. Studies using lower volumes and concentrations of LA also had less favourable outcomes.12 22 Higher injectate pressures generated