•Exchange between pore and bottom water with sediment affects authigenic REE in the Labrador Sea (LS).•REE-based correction allows reconstruction of past bottom water ϵNd signatures.•Evidence for ...lack of southern sourced water in the LS through the last 35 ka.•Glacial LS bottom waters were less radiogenic than today with ϵNd = −16 ± 1.•Similarity to Nordic Seas ϵNd record suggests uninterrupted supply of overflow waters.
Deep waters of the Labrador Sea (LS) are important contributors to the Atlantic Meridional Overturning Circulation, but their water mass structure has been highly variable and sensitive to climatic changes on different time scales. The LS is also an area of intense exchange of rare earth elements (REE) between seawater and the underlying sediments, which complicates the reconstruction of past deep water provenance based on radiogenic neodymium (Nd) isotopes. Most notably, Northwest Atlantic Bottom Water exchanges Nd with Archaean age Laurentian detritus, resulting in a significant shift to less radiogenic Nd isotope signatures before it enters the North Atlantic to form the deep part of North Atlantic Deep Water. Here we show that the authigenic fractions of LS core top sediments carry Nd isotope signatures intermediate between bottom water and detritus and thus reflect pore waters that incorporate a mixture of both signatures.
We furthermore find that detrital imprints on pore waters led to shifts of REE patterns in the authigenic fraction towards detrital signatures in the past during times of enhanced supply of glacially eroded material from Hudson Bay to the LS, as recorded by radiogenic lead isotopes. This allows an estimation of the intensity of past benthic REE exchange inside the LS.
We exploit variations in the mid REE enrichment in the authigenic phase to propose a correction to one LS Nd isotope record for detrital imprints originating from pore water exchange. The corrected ϵNd signatures are argued to more accurately reflect those of past bottom waters. This correction results in past LS bottom water signatures of −16 ± 1 during MIS 2 and 3, considerably less radiogenic than today. This implies that no southern sourced waters advanced into the LS during the last 35 ka and instead supports continuous bottom water sourcing from the Nordic Seas. It thus seems likely that LS bottom waters supplied unradiogenic Nd to abyssal Glacial North Atlantic Bottom Water in the Northwest Atlantic, as was previously hypothesized.
Multisystem inflammatory syndrome in children (MIS‐C) associated with coronavirus disease 2019 (COVID‐19) has been described to partially overlap with Kawasaki disease (KD) with regard to clinical ...symptoms, but they are unlikely to share the same disease entity. We conducted a systematic review and meta‐analysis to characterize the laboratory parameters of MIS‐C compared with those of KD and Kawasaki disease shock syndrome (KDSS). Databases were searched for studies on laboratory parameters of MIS‐C (hematology, inflammatory markers, cardiac markers, and biochemistry) through May 31, 2021. Twelve studies with 3073 participants yielded 969 MIS‐C patients. In terms of hematology, MIS‐C patients had lower levels of leukocytes, absolute lymphocyte count and platelet count (PLT) than KD patients and had similar absolute neutrophil count (ANC) and hemoglobin (Hb) levels. In terms of inflammatory markers, MIS‐C patients had higher levels of C‐reactive protein, D‐dimer and ferritin than KD patients and had similar levels of procalcitonin and erythrocyte sedimentation rate (ESR). In terms of cardiac markers, MIS‐C patients had higher CPK levels than KD patients. The levels of N‐terminal pro‐brain natriuretic peptide, troponin and aspartate aminotransferase were not significantly different between MIS‐C and KD patients. In terms of biochemistry, MIS‐C patients had lower levels of albumin, sodium and alanine aminotransferase and higher levels of creatinine than KD patients. In addition, MIS‐C patients had lower levels of PLT, Hb and ESR and higher levels of ANC than KDSS patients. Measurement of laboratory parameters might assist clinicians with accurate evaluation of MIS‐C and further mechanistic research.
Robotic-assisted, endoscopic transforaminal lumbar interbody fusion (RE-TLIF) is a promising, minimally invasive surgical option for degenerative lumbar spondylosis/spondylolisthesis; however, ...outcomes data and efficacy are limited, especially in multilevel disease. Here, we present the first reported series of patients that underwent either single or multilevel RE-TLIF.
A retrospective review was performed on 23 consecutive patients who underwent a single level or multilevel RE-TLIF by a single surgeon. Variables included demographics, perioperative results, pain scores, and functional outcome scores.
Eighteen patients (78.3 %) underwent single level RE-TLIF and 5 patients (21.7 %) underwent multilevel RE-TLIF. The median reduction of visual analog scale (VAS) for low back pain (LBP) of all subjects was 6 (IQR = 4.5, 6.5) with no significant difference between single level and multilevel RE-TLIF (p = 0.565). The median reduction of VAS for leg pain of all subjects 7 (IQR = 6, 8) with no significant difference between single level and multilevel RE-TLIF (p = 0.702). Median blood loss was 25 cc (IQR = 25, 25) and 50 cc (IQR = 25, 100) for single and multilevel RE-TLIF, respectively (p = 0.025), whereas median length of stay was 1 (IQR = 1, 1; mean = 1.0 ± 00.18) days and 1 (IQR = 1, 2; mean = 1.4 ± 00.54) days, respectively (p = 0.042). One major complication was observed requiring reoperation for demineralized bone matrix migration resulting in an L5 radiculopathy.
Single and multi-level RE-TLIF appears to be a safe and efficacious approach with comparable outcomes to open and other minimally invasive approaches. Additionally, we observed favorable accuracy in robot-assisted pedicle screw, endoscope, and interbody device placement.
Learning manipulation skills from open surgery provides more flexible access to the organ targets in the abdomen cavity and this could make the surgical robot working in a highly intelligent and ...friendly manner. Teaching by demonstration (TbD) is capable of transferring the manipulation skills from human to humanoid robots by employing active learning of multiple demonstrated tasks. This work aims to transfer motion skills from multiple human demonstrations in open surgery to robot manipulators in robot-assisted minimally invasive surgery (RA-MIS) by using TbD. However, the kinematic constraint should be respected during the performing of the learned skills by using a robot for minimally invasive surgery. In this article, we propose a novel methodology by integrating the cognitive learning techniques and the developed control techniques, allowing the robot to be highly intelligent to learn senior surgeons' skills and to perform the learned surgical operations in semiautonomous surgery in the future. Finally, experiments are performed to verify the efficiency of the proposed strategy, and the results demonstrate the ability of the system to transfer human manipulation skills to a robot in RA-MIS and also shows that the remote center of motion (RCM) constraint can be guaranteed simultaneously. Note to Practitioners -This article is inspired by limited access to the manipulation of laparoscopic surgery under a kinematic constraint at the point of incision. Current commercial surgical robots are mostly operated by teleoperation, which is representing less autonomy on surgery. Assisting and enhancing the surgeon's performance by increasing the autonomy of surgical robots has fundamental importance. The technique of teaching by demonstration (TbD) is capable of transferring the manipulation skills from human to humanoid robots by employing active learning of multiple demonstrated tasks. With the improved ability to interact with humans, such as flexibility and compliance, the new generation of serial robots becomes more and more popular in nonclinical research. Thus, advanced control strategies are required by integrating cognitive functions and learning techniques into the processes of surgical operation between robots, surgeon, and minimally invasive surgery (MIS). In this article, we propose a novel methodology to model the manipulation skill from multiple demonstrations and execute the learned operations in robot-assisted minimally invasive surgery (RA-MIS) by using a decoupled controller to respect the remote center of motion (RCM) constraint exploiting the redundancy of the robot. The developed control scheme has the following functionalities: 1) it enables the 3-D manipulation skill modeling after multiple demonstrations of the surgical tasks in open surgery by integrating dynamic time warping (DTW) and Gaussian mixture model (GMM)-based dynamic movement primitive (DMP) and 2) it maintains the RCM constraint in a smaller safe area while performing the learned operation in RA-MIS. The developed control strategy can also be potentially used in other industrial applications with a similar scenario.
Authigenic phases in lake sediments hold the potential to record changes in the isotope compositions of past lake water, potentially yielding valuable information on secular changes in continental ...weathering patterns and rates, including over past glacial cycles.
Here, different leaching approaches are investigated with the aim of extracting Sr, Nd, Pb, and Be hosted in authigenic Fe-Mn (oxy)hydroxide sediment phases for precise isotope measurements. Elemental Al/Mn, Ca/Mn, and P/Mn ratios obtained via a mild reductive leach agree well with the composition of marine authigenic Fe-Mn phases. For core top sediments, leached Sr isotope compositions obtained with this leach agree well with the composition of lake water. The Be and Nd isotope compositions of core top leachates are consistent with the spatial variability observed in the water column. Due to high concentrations in Fe-Mn phases, leachate compositions are dominated by authigenic Be, Sr, Nd, and Pb, even in cases when as much as 40% of leached phases (by mass) are non-authigenic. These lines of evidence suggest that the mild reductive leach successfully extracts the modern lake isotope composition from modern sediments in terms of the isotope systems investigated. We further show that the leaching method is also reliable for older sediments (<340 ka): leached paleo-Sr isotope compositions are consistent between the current and previous interglacial periods, as well as for glacial periods. This suggests that reconstructed water isotope compositions are not affected by early diagenetic processes, instead reflecting environmental factors around the lake that determine the composition of weathering fluxes. Although more difficult to assess for Be, Nd, and Pb due to the heterogeneity of modern lake water, the data we present indicate the overall robustness of the leaching approach.
These promising results open up lakes as archives for paleo-weathering reconstructions. Given that marine reconstructions face some important limitations (e.g., integration of basin-wide changes in weathering processes, long residence times for Sr, etc.Fe), lake records provide an avenue to improve our understanding of changes in regional weathering processes over glacial-interglacial timescales. The mild reductive leach used here may also be useful for meteoric Be studies in marine shelf settings, to prevent leaching of terrestrial sedimentary Fe-Mn oxy(hydroxide) phases.
There is increasing concern with anthropogenic greenhouse gas emissions that ocean warming, in concert with summer and winter precipitation changes, will induce anoxia in multiple ocean basins, such ...as in the Mediterranean Sea. Although the hydrological changes in the eastern Mediterranean are quite well constrained, quantitative evidence of changes in sea surface temperature (SST) and winter rainfall in the western Mediterranean across the past interglacials is relatively scarce. In this study, we use a combination of trace element (Ba/Ca and Mg/Ca) and stable oxygen isotope composition of planktonic foraminifera from a sediment core located off the Golo River, Corsica (northern Tyrrhenian Sea) to reconstruct variations in SSTs and sea surface salinities (SSS) during the Holocene (MIS 1) and warm periods of the past two interglacials (MIS 5, 7). We also analyse PMIP3 model simulations for the mid-Holocene to investigate the mechanism for moisture transport in the western Mediterranean. Our Mg/Ca-SSTs, Ba/Ca-salinity and derived δ18O-seawater records suggest that the warm periods of the past interglacials were characterized by high river discharge and lower SSS in the northern Tyrrhenian Sea. Since this region is ideally located on the trajectory of wintertime storm tracks across the North Atlantic into the Mediterranean Sea and is also outside the influence of the ITCZ-controlled summer monsoon rains, we suggest enhanced winter rainfall during the past interglacials. Our analysis of PMIP3 model simulations for mid-Holocene also support increased south-westerly moisture transport into the western Mediterranean originating from the North Atlantic. We also find evidence that long-term amplitude of the salinity decrease tightly follows eccentricity. We suggest that these hydrologic changes in the western Mediterranean, and the northern Mediterranean borderlands as a whole, were a contributing factor, together with local cyclogenesis and African summer monsoon rainfall, to basin-wide anoxia in the past. Our findings offer new constraints to the amplitude and cause of winter rainfall changes in the Mediterranean during past warm periods.
•A review on modelling, design, and control of cable-driven mechanism for surgical robots is given.•A review on modelling, design, and control of fluidic actuator for surgical robots is introduced.•A ...review on modelling, design, and control of smart materials for surgical robots is presented.•A review on modelling, design, and control of magnetic actuators for surgical robots is provided.•Discussion and recommendation for the future use are given.
Robot-assisted surgeries have been integrated and leading to a paradigm shift in surgical fields. With the emergence of Minimally Invasive Surgery (MIS), especially Natural Orifice Transluminal Endoscopic Surgery (NOTES), there are various benefits such as a minimization of side effects, enhancement of precise surgical procedures, and faster recovery after the surgery that patients can take from. However, in order to effectively employ and exploit surgical robots, numerous technical challenges need to be addressed. Among these, actuators play a vital role. To provide deeper understanding on current actuators-driven surgical robot, this study will comprehensively review on four main types of transmission systems namely cable-driven mechanism, flexible fluidic actuators, smart material actuators, and magnetic actuators, in terms of conceptual designs, modelling, and control as well as their advantages and disadvantages. Profound discussions and recommendations for the future of actuators-driven surgical robots will be also pointed out to give the roadmap in the surgical field.
A unique index-record of Last Interglacial (Marine Isotope Stage 5e MIS5e) relative sea level (RSL) and wave climate history in South-east Australia is presented from Robbins Island, in western Bass ...Strait. This is applied to interpret the wider MIS5e coastal evidence around Bass Strait. At Robbins Island, the combination of low wave and wind energy, a tide-modified regime and a sand supply resulted in the shoreline progradation throughout MIS5e. This preserved a time-series of paleo-sea level across a 7 km wide strandplain (Remarkable Banks). After a highstand, MIS5e RSL attained a stillstand of +5.75 ± 0.5 m above modern mean sea level during 126 to ∼119 ka BP. The MIS5e RSL interpretation is underpinned by modern analogues and hydrodynamic modelling of waves, tides and currents. A high resolution LiDAR Digital Elevation Model (DEM) supported by morpho-sedimentary studies, ground-penetration radar (GPR) surveys and a geochronology based upon Optically Stimulated Luminescence (OSL) methods were used to define the proxy RSL record. The observed RSL history was compared to modelled RSL history that accounted for the theoretical fall in RSL (regression) throughout MIS5e, due to the Glacio-Isostatic Adjustment (GIA) forcing.
Three stages of RSL change occurred during MIS 5e: (i) RSL fall during phase 1 from ∼129 to 126 ka BP, and during phase 3 between ∼118 and 114 ka BP.; and, (ii) a multi-millennial stillstand during the intervening phase 2 from 126 to ∼119 ka BP. The stillstand departure from GIA theory, points unambiguously to persistent polar meltwater contributions to sea level of ∼2 m from 126 to 119 ka BP, where the component of RSL fall due to GIA was balanced by the RSL rise from meltwater. The potential contributions of paleo wave climate (direction) and boundary current histories were reconstructed from across all Bass Strait sites to determine an RSL budget. In addition, the paleo wave climate history allowed the triangulation of directional ocean wave synoptic sources and identified a 5° poleward shift in the Subtropical Ridge during MIS5e.
•The full MIS5e relative sea level (RSL) history is presented from a uniquely preserved strandplain, as an index RSL curve for the region.•A novel application of defining paleo-wave climate changes with the relative sea-level record to identify climate shifts.•MIS5e polar meltwater contributions of ∼2m between 126 to 119 ka BP are defined from the difference between observed and modeled RSL due to the Glacio-Isostatic Adjustment.•The index sea-level and wave climate records are applied to sites around Bass Strait to interpret the regional sea-level and climate signals, including shifts in the Subtropical Ridge.•A sea-level budget approach is used to estimate the contribution of dynamic sea-level contributions to the MIS5e record that may have occurred due to boundary current variability.