bluuebunny/crossref_metadata_2025 huggingface dataset:
Pseudo-Interference Stiffness Estimation in Gear Teeth Contact
Authors: Lee Geunho , Kazarounian Kazem , Koenig Herbert A.
Published: February 2021

One of the important factors in gear dynamic analysis is accurate estimation of the mesh stiffness. To accurately model the mesh stiffness characteristics, the Pseudo-Interference Stiffness Estimation (PISE) method is proposed. PISE draws upon the finite element analysis method. It also analyzes the non-linear, geometric based characteristics of the local contact region. Consequently, PISE is used to model the elastic deformation at the mesh regions and estimate the corresponding stiffnesses in the elastic region.

In this paper, as an example, PISE is applied to the two cylinders’ contact problem. Thus the PISE solution is compared with exact analytical solution which is readily available in literature. Subsequently, PISE is used to model the contact region and estimate the mesh stiffness of a gear system.
Compliant Parallel-Guiding Mechanisms
Authors: Derderian James M. , Howell Larry L. , Murphy Morgan D. , Lyon Scott M. , Pack Spencer D.
Published: February 2021

The rigid-link parallel-guiding (or parallelogram) mechanism is perhaps one of the simplest closed-loop mechanisms to analyze. Compliant parallel-guiding mechanisms, often called plate-spring mechanisms, are in common use in many applications. Advances in compliant mechanism modeling and synthesis have provided an opportunity to apply these mechanisms in an even wider range of uses. Unlike the rigid-link parallel-guiding mechanism which has a simple configuration defined by one kinematic chain, this paper reveals that twenty-eight compliant parallel-guiding mechanism configurations exist. Also, traditional plate spring mechanisms have been designed to function in the linear, small-deflection range and this paper describes a design approach that allows for deflections well into the non-linear range. The purpose of this paper is then threefold: i) identify all configurations of compliant parallel-guiding mechanisms, ii) provide a method for the design and analysis of compliant parallel-guiding mechanisms, and iii) provide experimental data to validate the above purposes. Additionally, the third purpose mentioned is important outside of the context of the parallel-guiding mechanism. The experimental results presented will help to validate the pseudo-rigid-body-model concept.
Analysis of Latching Systems in Deployers of Deployable Structures Using Generalized Yale Lock and Sequential Logic
Authors: Chew M. , Ho M. T.
Published: February 2021

Deployable structures can be erected from a folded configuration using a mechanism known as a deployer. Many latches are present in a deployer. These latches are coordinated in a logical and systematic manner to bring about the deployment of an associated deployable space structure. This article presents an investigation into the systematic analysis of the logical behavior of a latching system for a deployer on the MAST I flight experiment. Three approaches, a modification of the Generalized Yale Lock, Sequential Logic, and a combination of these two approaches — the Sequential Yale Lock, will be applied to the analysis and design of the latching system. A comparison of the approaches provides insight to the applicability of each of the approaches.
Spherical Four-Bar Linkage Mechanism for Continuous Passive Movement Rehabilitation Treatment of the Ankle
Authors: Ham Kealy R. , Erdman Arthur G. , Hong Boyang
Published: February 2021

Continuous passive movement (CPM) is an important process in the post-operative rehabilitation treatment of the knee. The two-dimensional, flexion/extension motion provided by CPM has been shown to have beneficial effects on tendon, cartilage, and ligament health via increased blood flow to the knee and surrounding tissues. Similarly, CPM may be useful in the rehabilitation of the ankle. However, the ball and socket joint of the ankle would benefit more from a three-dimensional spherical motion instead of the traditional two-dimensional, flexion/extension motion.

This study presents a four-bar linkage developed with the use of three dimensional mechanical modeling software. The linkage provides a spherical path of motion for the continuous passive movement of the ankle. This spherical CPM may ultimately be useful in the treatment of congenital musculoskeletal abnormalities, acquired joint disorders, and traumatic injury of the ankle.
A Study on the Grasp Synthesis Using the Line Geometry
Authors: Tsai Ming-June , Chen Fong-Zhi
Published: February 2021

The applications of line geometry to grasp analysis and synthesis is presented in this paper. Since most of the contact wrenches are of zero pitch, they can be described as lines. The geometrical representation of the linearly dependent lines can reduce the complexity of grasp research. The geometrical characteristics of rank 3 dependent line sets are discussed. The geometrical characteristics are then applied to the force closure grasp and grasp synthesis of a four-fingered hand. A new grasp model is derived to illustrate the application of line geometry to simplify grasp transformation.
Construction of a Six-Degrees-of-Freedom Parallel Manipulator With Three Planarly Actuated Links
Authors: Ben-Horin Ronen , Shoham Moshe
Published: February 2021

The construction of a new type of a six-degrees-of-freedom parallel robot is presented in this paper. Coordinated motion of three planar motors, connected to three fixed-length links, produces a six-degrees-of-freedom motion of an output link. Its extremely simple design along with much larger work volume make this high performance-to-simplicity ratio robot very attractive.
Dynamics and Control of an Adaptive Disk Suspension System Under Inertial Loading
Authors: Yang Li-Farn , Tzeng Rueih-Chir , Kuo Chun-Pao
Published: February 2021

A zero-stiffness suspension system featuring a noncircular disk is used as an application in counteracting gravity loads in ground-based structural testing. The dynamic behavior of this mechanism is analyzed in closed form, in which this mechanism is shown to be very sensitive to inertial properties of noncircular disk which can introduce inertial forces to trigger nonlinear dynamic behavior in the system, thereby degrading testing performance under such inertial loading. An adaptive feedforward control law is developed for eliminating these inertial effects upon the suspension system during dynamic testing. Under this control manipulation, the output signals of disk mechanism are regulated and tracked along the desired trajectories so that the error signals can vastly be reduced. Stability of the control system is investigated, and simulated-time histories of test articles under an active band-drive suspension system will also be presented to show the effectiveness of the present approach.
A Proposed Model for Stochastic Vibration Analysis of Gear Transmission Systems
Authors: Wang Y. , Zhang W.
Published: February 2021

A new mathematical model is presented for analyzing the vibration of gear transmission systems with consideration of the influence of the time-variant stiffness, loads, gear transmission errors. The gear transmission system is modeled as a non-linear, time-correlated and stationary stochastic system. The transmission errors of gears are decomposed into harmonic and random components in terms of the different characteristics of their spectrums. The random component is simulated by a second order Markov process. A simulation system for vibration analysis of gear transmission systems is then developed, based on this new model. The input to this system is a Guassian white noise process and harmonic errors, and the output is the rotational vibration acceleration of gears. Some experiments are conducted to verify the proposed model. By comparing the results generated from the simulation system with those from the experiments, the proposed model is found to reach a fairly good accuracy, and thus the model is useful in designing gear transmission systems with the objective to reduce the vibration and noise of the systems in operation.
A Methodology for the Configuration Synthesis of Machining Centers With Automatic Tool Changer
Authors: Yan Hong-Sen , Chen Fu-Chen
Published: February 2021

The purpose of this paper is to present a design methodology for the configuration synthesis of machining centers with automatic tool changer to meet the required topology and motion characteristics. According to the concept of coordinate systems, graph theory, generalization, specialization, and motion synthesis, this design methodology is proposed and computerized, and the machining centers with automatic tool changer up to eight links are synthesized. As the result, for the machining centers with drum type tool magazine, the numbers of configurations of machining centers with 6, 7, and 8 links are 2, 13, and 20, respectively. And, for the machining centers with linear type tool magazine, the numbers of configurations of machining centers with 5, 6, 7, and 8 links are 1, 5, 20, and 60, respectively. Furthermore, this work provides a systematic approach for synthesizing spatial open-type mechanisms with topology and motion requirements.
Accelerometer Calibration: The Importance of Considering Functionality
Authors: Strath Scott J. , Rowley Taylor W. , Cho Chi C. , Hyngstrom Allison , Swartz Ann M. , Keenan Kevin G. , Martinez Julian , Staudenmayer John W.
Published: February 2021

Purpose: To compare the accuracy and precision of a hip-worn accelerometer to predict energy cost during structured activities across motor performance and disease conditions. Methods: 118 adults self-identifying as healthy (n = 44) and those with arthritis (n = 23), multiple sclerosis (n = 18), Parkinson’s disease (n = 17), and stroke (n = 18) underwent measures of motor performance and were categorized into groups: Group 1, usual; Group 2, moderate impairment; and Group 3, severe impairment. The participants completed structured activities while wearing an accelerometer and a portable metabolic measurement system. Accelerometer-predicted energy cost (metabolic equivalent of tasks [METs]) were compared with measured METs and evaluated across functional impairment and disease conditions. Statistical significance was assessed using linear mixed effect models and Bayesian information criteria to assess model fit. Results: All activities’ accelerometer counts per minute (CPM) were 29.5–72.6% less for those with disease compared with those who were healthy. The predicted MET bias was similar across disease, −0.49 (−0.71, −0.27) for arthritis, −0.38 (−0.53, −0.22) for healthy, −0.44 (−0.68, −0.20) for MS, −0.34 (−0.58, −0.09) for Parkinson’s, and −0.30 (−0.54, −0.06) for stroke. For functional impairment, there was a graded reduction in CPM for all activities: Group 1, 1,215 CPM (1,129, 1,301); Group 2, 789 CPM (695, 884); and Group 3, 343 CPM (220, 466). The predicted MET bias revealed similar results across the Group 1, −0.37 METs (−0.52, −0.23); Group 2, −0.44 METs (−0.60, −0.28); and Group 3, −0.33 METs (−0.55, −0.13). The Bayesian information criteria showed a better model fit for functional impairment compared with disease condition. Conclusion: Using functionality to improve accelerometer calibration could decrease variability and warrants further exploration to improve accelerometer prediction of physical activity.
The Making of the 1976 Canada Cup: Power Plays, Hockey Diplomacy, and the Rise of Alan Eagleson
Authors: Scherer Jay
Published: February 2021

In 1976, amidst a period of détente in the Cold War, the Government of Canada officially hosted an inaugural open-play invitational ice hockey tournament. A detailed narration of these events, pieced together from archival sources, allows scholars to understand the negotiations to prepare the political terrain for the event, including efforts to secure the official endorsement of the International Ice Hockey Federation for a tournament sponsored by the Government of Canada in exchange for Canada’s return to international competition in 1977; the participation of various countries and their respective hockey governing bodies, especially the Soviet Union, in an international tournament featuring professional players; and an agreement with the North American professional hockey cartels, especially the National Hockey League, to allow star players to participate in the event. The success of the 1976 Canada Cup accelerated the commodification and commercialization of hockey both in North America and globally—a process that was increasingly driven by the interests and aspirations of the National Hockey League. At the center of this history is one increasingly powerful—and avaricious—character: Alan Eagleson.
129
I and
247
Cm in meteorites constrain the last astrophysical source of solar r-process elements
Authors: Côté Benoit , Eichler Marius , Yagüe López Andrés , Vassh Nicole , Mumpower Matthew R. , Világos Blanka , Soós Benjámin , Arcones Almudena , Sprouse Trevor M. , Surman Rebecca , Pignatari Marco , Pető Mária K. , Wehmeyer Benjamin , Rauscher Thomas , Lugaro Maria
Published: February 2021

The origin of r-process elements

Theoretical models predict that the synthesis of heavy elements by the rapid neutron capture process (r-process) occurs in extreme astrophysical environments such as neutron star mergers or some types of supernovae. Testing those predictions by comparing them with the isotopic record has been difficult. Côté
et al.
examined two r-process isotopes, iodine-129 and curium-247, both of which have half-lives of 15.6 million years. Therefore, their ratio remains constant even long after the nucleosynthesis event. The ratio of those isotopes at the time of Solar System formation is recorded in meteorites. Comparing this value with nuclear astrophysics calculations shows that the most likely source was moderately neutron-rich material ejected from a binary neutron star merger.

Science
, this issue p.
945
Tau: Enabler of diverse brain disorders and target of rapidly evolving therapeutic strategies
Authors: Chang Che-Wei , Shao Eric , Mucke Lennart
Published: February 2021

The many faces of tau

The protein tau is implicated in several brain disorders, including Alzheimer's disease, suggesting that it could be a target of therapeutics. However, because it is unclear how the pleiotropic roles of tau lead to neural pathology in different brain diseases, drug development remains challenging. Chang
et al.
review the possible mechanisms of tau in brain diseases and possible paths forward to improving research and drug development.

Science
, this issue p.
eabb8255
Reactive uptake of N
2
O
5
by atmospheric aerosol is dominated by interfacial processes
Authors: Galib Mirza , Limmer David T.
Published: February 2021

On the surface

The uptake and hydrolysis of N
2
O
5
from the atmosphere by aqueous aerosols was long thought to occur by solvation and subsequent hydrolysis in the bulk of the aerosol. However, this mechanistic hypothesis was unverifiable because of the fast reaction kinetics. Galib
et al.
used molecular simulations to show instead that the mechanism is the inverse: Interfacial hydrolysis is followed by solvation into the interior. Their reactive uptake model is consistent with some existing experimental observations.

Science
, this issue p.
921
Shulin packages axonemal outer dynein arms for ciliary targeting
Authors: Mali Girish R. , Ali Ferdos Abid , Lau Clinton K. , Begum Farida , Boulanger Jérôme , Howe Jonathan D. , Chen Zhuo A. , Rappsilber Juri , Skehel Mark , Carter Andrew P.
Published: February 2021

Ciliary motors locked closed by Shulin

Motile cilia and flagella are vital cellular organelles with functions that include setting up the left-right body axis, clearing airways of mucus, and driving single-cell movements. Cilia beating is powered by arrays of dynein motors, the key force generators being the outer dynein arm (ODA) complexes. Using the protozoan
Tetrahymena
, Mali
et al.
identified a factor, which they name Shulin, that binds newly synthesized ODAs. Cryo–electron microscopy revealed how Shulin locks the dynein motors together by shutting off motor activity and facilitating delivery of ODAs from the cytoplasm to their final position in the cilia.

Science
, this issue p.
910
Plitidepsin has potent preclinical efficacy against SARS-CoV-2 by targeting the host protein eEF1A
Authors: White Kris M. , Rosales Romel , Yildiz Soner , Kehrer Thomas , Miorin Lisa , Moreno Elena , Jangra Sonia , Uccellini Melissa B. , Rathnasinghe Raveen , Coughlan Lynda , Martinez-Romero Carles , Batra Jyoti , Rojc Ajda , Bouhaddou Mehdi , Fabius Jacqueline M. , Obernier Kirsten , Dejosez Marion , Guillén María José , Losada Alejandro , Avilés Pablo , Schotsaert Michael , Zwaka Thomas , Vignuzzi Marco , Shokat Kevan M. , Krogan Nevan J. , García-Sastre Adolfo
Published: February 2021

Hurting the virus by targeting the host

Many host proteins play a role in the life cycle of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and some are required for viral replication and translation. There are efforts toward finding drugs that target viral proteins, but a complementary approach is to target these required host proteins. White
et al.
explored the antiviral activity of the cyclic depsipeptide drug plitidepsin, which targets the hosts cell's translational machinery (see the Perspective by Wong and Damania). The authors show that in cells, the drug is substantially more potent than remdesivir against SARS-CoV-2, with limited cellular toxicity. Prophylactic treatment protected mice against SARS-CoV-2 infection, so further investigation of plitidepsin as a therapeutic is warranted.

Science
, this issue p.
926
; see also p.
884
The soul and its shell
Mr. Humble and Dr. Butcher: A Monkey's Head, the Pope's Neuroscientist, and the Quest to Transplant the Soul
Brandy Schillace
Simon and Schuster, 2021. 320 pp.
Authors: Lederer Susan E.
Published: February 2021

A neurosurgeon's audacious experiments raised ire from animal rights activists and interest from the Vatican
High-speed harvesting of random numbers
Authors: Fischer Ingo , Gauthier Daniel J.
Published: February 2021

A broad-area multimode laser can be made into a powerful random number generator
Clarity on the crackdown
Authors: Lodish Harvey , Chen Jianzhu , Sharp Phillip
Published: February 2021

Less than a month after his inauguration, U.S. President Biden moved to reverse policies that have deterred foreign students and high-skilled workers from coming to the United States. This is good news. The exchange of culture and knowledge drives innovation, which in turn builds the nation's economy and competitiveness on a global scale. But some countries, especially China, continue to present a dilemma when it comes to national security. In trying to strike a balance between preserving a culture of openness and protecting U.S. research, missteps can occur—and that can be detrimental to U.S. science.
Contagious Antibiotic Resistance: Plasmid Transfer among Bacterial Residents of the Zebrafish Gut
Authors: Loftie-Eaton Wesley , Crabtree Angela , Perry David , Millstein Jack , Baytosh Justin , Stalder Thibault , Robison Barrie D. , Forney Larry J. , Top Eva M.
Published: February 2021

To understand how antibiotic resistance plasmids end up in human pathogens, it is crucial to learn how, where, and when they are transferred and maintained in members of bacterial communities such as the gut microbiome. To gain insight into the network of plasmid-mediated antibiotic resistance sharing in the gut microbiome, we investigated the transferability and maintenance of a multidrug resistance plasmid among the culturable bacteria of the zebrafish gut.
Late Neoproterozoic–early Paleozoic basin evolution in the Cathaysia Block, South China: Implications of spatio-temporal provenance changes on the paleogeographic reconstructions in supercontinent cycles
Authors: Xue Er-Kun , Wang Wei , Zhou Mei-Fu , Pandit Manoj K. , Huang Si-Fang , Lu Gui-Mei
Published: February 2021

The role of the Cathaysia Block, South China, and its linkage with orogenesis in the Rodinia and Gondwana supercontinents remain unresolved because of uncertainties in its paleoposition in supercontinental reconstructions. The lithostratigraphic, geochronologic, geochemical (including isotopic), and paleocurrent data on late Neoproterozoic to early Paleozoic sub-basins in the Cathaysia Block reveal spatio-temporal, tectono-sedimentary, and provenance diversity that show linkages with previously adjacent terranes and orogens in East Gondwana. An abundance of siliceous and conglomeratic rocks, local unconformities, and pinch-out in certain layers indicate a late Cryogenian proximal deposition, late Ediacaran transgression, and Middle Cambrian uplift. Cryogenian to early Ordovician strata contain predominantly 1000–900 Ma (late Grenvillian age) detrital zircon population, whereas 1300–1050 Ma (early Grenvillian age) zircons are only dominant in strata earlier than late Ediacaran. Besides, 850–700 Ma zircons are the most prominent group in the Middle Cambrian strata along with an occasional increase in the 650–500 Ma (Pan-African age) zircons.

The Grenvillian age zircon groups exhibit significant sediment input from the eastern Indian terrane (990–950 Ma) and western Australia (1300–1050 Ma), underlining the fact that the Cathaysia Block was located between these two terranes in the northern part of East Gondwana. The diminishing contribution of early Grenvillian components in the late Ediacaran strata can be linked to the Pinjarra Orogeny (550–520 Ma), which led to uplift that blocked the transport of detritus from Australia. Middle Cambrian provenance variation with high abundance of 850–700 Ma components indicates the presence of intrinsic sediment from the Wuyishan terrane of South China. Given that the Cathaysia Block was a passive continental margin, this change was caused by the uplift of the southeastern Cathaysia Block, which was related to the far-field stress effects of the late phase of the Kuunga Orogeny (530–480 Ma). The decrease in abundance of early Grenvillian and Pan-African zircons in space implies that they were transported into the basins through independent drainage systems. This is consistent with the local and temporal variations in paleocurrent orientations during the Cambrian, further implying diverse and complex drainage systems in the southwestern Cathaysia Block during this period.
Facies interpretation and geochronology of diverse Eocene floras and faunas, northwest Chubut Province, Patagonia, Argentina
Authors: Gosses Justin , Carroll Alan R. , Bruck Benjamin T. , Singer Brad S. , Jicha Brian R. , Aragón Eugenio , Walters Andrew P. , Wilf Peter
Published: February 2021

The Eocene Huitrera Formation of northwestern Patagonia, Argentina, is renowned for its diverse, informative, and outstandingly preserved fossil biotas. In northwest Chubut Province, at the Laguna del Hunco locality, this unit includes one of the most diverse fossil floras known from the Eocene, as well as significant fossil insects and vertebrates. It also includes rich fossil vertebrate faunas at the Laguna Fría and La Barda localities. Previous studies of these important occurrences have provided relatively little sedimentological detail, and radioisotopic age constraints are relatively sparse and in some cases obsolete. Here, we describe five fossiliferous lithofacies deposited in four terrestrial depositional environments: lacustrine basin floor, subaerial pyroclastic plain, vegetated, waterlogged pyroclastic lake margin, and extracaldera incised valley. We also report several new 40Ar/39Ar age determinations. Among these, the uppermost unit of the caldera-forming Ignimbrita Barda Colorada yielded a 40Ar/39Ar age of 52.54 ± 0.17 Ma, ∼6 m.y. younger than previous estimates, which demonstrates that deposition of overlying fossiliferous lacustrine strata (previously constrained to older than 52.22 ± 0.22 Ma) must have begun almost immediately on the subsiding ignimbrite surface. A minimum age for Laguna del Hunco fossils is established by an overlying ignimbrite with an age of 49.19 ± 0.24 Ma, confirming that deposition took place during the early Eocene climatic optimum. The Laguna Fría mammalian fauna is younger, constrained between a valley-filling ignimbrite and a capping basalt with 40Ar/39Ar ages of 49.26 ± 0.30 Ma and 43.50 ± 1.14 Ma, respectively. The latter age is ∼4 m.y. younger than previously reported. These new ages more precisely define the age range of the Laguna Fría and La Barda faunas, allowing greatly improved understanding of their positions with respect to South American mammal evolution, climate change, and geographic isolation.
Latitudinal variability in the Quaternary development of the Eurasian ice sheets—Evidence from the marine domain
Authors: Hjelstuen Berit Oline , Sejrup Hans Petter
Published: February 2021

Here we present the first compilation of sediment volumes, sedimentation rates, and chronology of Quaternary sediment packages along the entire marine margin of the Eurasian ice sheets (EurIS; British–Irish, Kara–Barents Sea–Svalbard, and Fennoscandian). This compilation allows for a subdivision of the EurIS development into three phases (2.6–1.5 Ma, 1.5–0.78 Ma, and 0.78–0 Ma). At the start of the Quaternary, sedimentation rates increased, relative to pre-Quaternary rates, by an order of magnitude. This abruptness in rate change excludes tectonic raising of landmasses as the main factor, but more likely reflects climate change through increased glacial erosion. The sediment distribution data suggest that the Kara–Barents Sea–Svalbard Ice Sheet (KBSIS) already was quite large at the beginning of the Quaternary, and well before 1.5 Ma it extended to the shelf edge and coalesced with the Fennoscandian Ice Sheet (FIS), which prior to 1.5 Ma most likely was located near the coast. Large ice streams and intense glacial erosion characterized the KBSIS in the 1.5–0.78 Ma time period, whereas the FIS at that time extended farther out on the continental shelf. After 0.78 Ma, a north-south change in EurIS development occurred. In the FIS and the British–Irish Ice Sheet (BIIS), large ice streams developed and shelf-edge glaciations occurred nearly 1 m.y. later compared to the KBSIS. The FIS and BIIS also repetitively coalesced in the North Sea. A significant drop in sediment input along the KBSIS marine margin, to the lowest Quaternary level, suggests a less erosive KBSIS.
The Permian Monos Formation: Stratigraphic and detrital zircon evidence for Permian Cordilleran arc development along the southwestern margin of Laurentia (northwestern Sonora, Mexico)
Authors: Dobbs Stephen C. , Riggs Nancy R. , Marsaglia Kathleen M. , González-León Carlos M. , Cecil M. Robinson , Smith M. Elliot
Published: February 2021

The southwestern margin of Laurentia transitioned from a left-lateral transform margin to a convergent margin by middle Permian time, which initiated the development of a subduction zone and subsequent Cordilleran arc along western Laurentia. The displaced Caborca block was translated several hundred kilometers from southern California, USA, to modern Sonora, Mexico, beginning in Pennsylvanian time (ca. 305 Ma). The Monos Formation, a ∼600-m-thick assemblage of mixed bioclastic and volcaniclastic units exposed in northwestern Sonora, provides lithostratigraphic, petrographic, and geochronologic evidence for magmatic arc development associated with subduction by middle Permian time (ca. 275 Ma).

The Monos Formation was deposited in a forearc basin adjacent to a magmatic arc forming along the southwestern Laurentian margin. Detrital zircon U-Pb geochronology suggests that Permian volcanic centers were the primary source for the Monos Formation. These grains mixed with far-traveled zircons from both Laurentia and Gondwana. Zircon age spectra in the Monos Formation are dominated by a ca. 274 Ma population that makes up 65% of all analyzed grains. The remaining 35% of grains range from 3.3 Ga to 0.3 Ma, similar to age spectra from Permian strata deposited in the Paleozoic sequences in the western continental interior. An abundance of Paleozoic through early Neoproterozoic ages suggests that marginal Gondwanan sources from Mexico and Central America also supplied material to the basin.

The Monos Formation was deposited within tropical to subtropical latitudes, yet faunal assemblages are biosiliceous and heterotrophic. The lack of photozoan assemblages suggests that cold-water coastal upwelling combined with sedimentation from the Cordilleran arc and Laurentian continent promoted conditions more suitable for fauna resilient to biogeochemically stressed environments.

We propose that transform faulting and displacement of the Caborca block ceased by middle Permian time and a subduction zone developed along the southwestern margin of Laurentia as early as early Permian time. The Monos basin developed along the leading edge of the continent as a magmatic arc developed, and facies indicate a consistent shoaling trend over the span of deposition.
Long-term outcomes in children with absent pulmonary valve syndrome: it is not just fixing the heart
Authors: Torok Katalin , Brettle Elizabeth , Desai Tarak , Miller Paul , Khan Natasha , Stickey John , Nagakumar Prasad , Seale Anna
Published: February 2021

Objective

Absent pulmonary valve syndrome (APV) is a rare condition usually associated with tetralogy of Fallot (TOF). Some infants develop respiratory failure from bronchial compression and the long-term neurodevelopmental outcome is unknown. We aimed to investigate the outcomes of APV and the need for long-term ventilation (LTV).

Design, patients and setting

Retrospective single-centre review of patients diagnosed with APV between 2007 and 2017.

Outcome measures

Survival, neurological disability and postoperative LTV (≥3 months of non-invasive or invasive respiratory support).

Results

Thirty patients were identified, 22 (73%) of whom were prenatally diagnosed. Pregnancy was discontinued in one patient, while in utero death occurred in three. One was lost to follow-up. Of the remaining 25 liveborn, 21 had the classic TOF/APV. One baby died immediately after birth, while two patients had palliative care due to severe airway compression and inability to wean ventilation support. Surgical repair was performed in 21 of the 25 (84%) liveborn, with one awaiting surgery. Of those undergoing surgery, two patients died: one during surgery and the other due to severe airway malacia 5 months postsurgery. In the surgical group survival from birth at 1 and 5 years was 89% (95% CI 75% to 100%). Six (30%) patients required LTV postoperatively; all had surgery within the first 6 months of life. Learning and/or other physical difficulties were evident in 63%.

Conclusions

Majority of patients with APV are diagnosed antenatally. A third of those operated required LTV and over half had learning and/or other physical difficulties. Prospective studies are needed to identify prenatal factors that predict postnatal outcomes so parents can be counselled appropriately.
Genomic evolution and diverse models of systemic metastases in colorectal cancer
Authors: Chen Hai-Ning , Shu Yang , Liao Fei , Liao Xue , Zhang Hongying , Qin Yun , Wang Zhu , Luo Maochao , Liu Qiuluo , Xue Zhinan , Cao Minyuan , Zhang Shouyue , Zhang Wei-Han , Hou Qianqian , Xia Xuyang , Luo Han , Zhang Yan , Yang Lie , Hu Jian-Kun , Fu Xianghui , Liu Bo , Hu Hongbo , Huang Canhua , Peng Yong , Cheng Wei , Dai Lunzhi , Yang Li , Zhang Wei , Dong Biao , Li Yuan , Wei Yuquan , Xu Heng , Zhou Zong-Guang
Published: February 2021

Objective

The systemic spread of colorectal cancer (CRC) is dominated by the portal system and exhibits diverse patterns of metastasis without systematical genomic investigation. Here, we evaluated the genomic evolution of CRC with multiorgan metastases using multiregion sequencing.

Design

Whole-exome sequencing was performed on multiple regions (n=74) of matched primary tumour, adjacent non-cancerous mucosa, liver metastasis and lung metastasis from six patients with CRC. Phylogenetic reconstruction and evolutionary analyses were used to investigate the metastatic seeding pattern and clonal origin. Recurrent driver gene mutations were analysed across patients and validated in two independent cohorts. Metastatic assays were performed to examine the effect of the novel driver gene on the malignant behaviour of CRC cells.

Results

Based on the migration patterns and clonal origins, three models were revealed (sequential, branch-off and diaspora), which not only supported the anatomic assumption that CRC cells spread to lung after clonally expanding in the liver, but also illustrated the direct seeding of extrahepatic metastases from primary tumours independently. Unlike other cancer types, polyphyletic seeding occurs in CRC, which may result in late metastases with intermetastatic driver gene heterogeneity. In cases with rapid dissemination, we found recurrent trunk loss-of-function mutations inZFP36L2, which is enriched in metastatic CRC and associated with poor overall survival. CRISPR/Cas9-mediated knockout ofZFP36L2enhances the metastatic potential of CRC cells.

Conclusion

Our results provide genomic evidence for metastatic evolution and indicate that biopsy/sequencing of metastases may be considered for patients with CRC with multiorgan or late postoperative metastasis.
Influence of childhood socioeconomic position and ability on mid-life cognitive function: evidence from three British birth cohorts
Authors: McElroy Eoin , Richards Marcus , Fitzsimons Emla , Conti Gabriella , Ploubidis George B , Sullivan Alice , Moulton Vanessa
Published: February 2021

Background

Childhood socioeconomic position (SEP) is robustly associated with cognitive function later in life. However, it is unclear whether this reflects a direct relationship, or an indirect association via modifiable factors such as educational attainment and occupation. We sought to clarify these associations using retrospectively harmonised data from three ongoing British birth cohorts.

Methods

We analysed data from the 1946 National Survey of Health and Development (n=2283), the 1958 National Child Development Study (n=9385) and the 1970 British Cohort Study (n=7631). Retrospective harmonisation was used to derive equivalent indicators of cognition, SEP, education and occupation across the three cohorts. Structural equation modelling was used to examine the association between childhood SEP and mid-life cognitive function, via childhood cognitive ability, educational attainment and mid-life occupation.

Results

Across all three cohorts, no direct pathways were observed between childhood SEP and mid-life cognitive function. Rather, this association was indirect via the three temporally ordered mediators. In addition, the direct pathway between childhood cognition and adult cognitive function was weaker in the two younger studies.

Conclusions

Across three British birth cohorts, we found that the association between early life SEP and mid-life cognitive function was fully mediated by childhood cognitive ability, educational attainment and occupational status. Furthermore, the association between early cognitive ability and mid-life cognitive function has decreased in younger generations. Therefore, cognitive function in adulthood may be influenced by modifiable factors and societal change.
Incidence of psychological illness after coronavirus outbreak: a meta-analysis study
Authors: Fan Fang Cheng , Zhang Shu Yao , Cheng Yong
Published: February 2021

Background

The COVID-19 has had an enormous impact worldwide and is still spreading. Globally confirmed infections have surpassed 41.1 million, of which more than 1 million resulted in deaths. Considering the relationship between public health disasters and emotional disorders, it is essential to examine psychological well-being related to this pandemic.

Method

We performed a systematic search on psychological problems from PubMed to 10 October 2020, and conducted a meta-analysis using Comprehensive Meta-Analysis V.3 software.

Results

The results showed a 19.4% and 26.8% pooled incidence for depression and post-traumatic stress disorder (PTSD), respectively, during the SARS and Middle East Respiratory Syndrome (MERS)-related coronavirus outbreaks. However, overall prevalence of depression was somewhat higher at 27.0% during the COVID-19 period. The pooled incidence of PTSD during COVID-19 compared with SARS and MERS outbreaks, was lower, at 16.4%.

Conclusion

The results suggest that there are shared and distinct psychological responses following SARS, MERS and COVID-19, and show pessimistic estimates of a wide range of potentially upcoming psychological problems.
Dividing line between organ donation and euthanasia in a combined procedure
Authors: Bollen Jan , Vissers Kris , van Mook Walther
Published: February 2021

In this article, we want to reply to the recent article by Buturovic, to be able to correct some statements and allegations about this combined procedure. Organ donation after euthanasia is an extremely difficult procedure from an ethical point of view. On the one hand, we see a suffering patient who wants to die but who also wants to make an altruistic effort to donate his organs. On the other hand, we visualise a patient in need of an organ but who is wary of the fact that someone else needs to die in order to potentially receive a transplant organ. Healthcare professionals seem to walk a tightrope when balancing between the interests of the patients at these two extremes: while facilitating the dying patient’s last wish on the one hand and abiding by all regulations regarding donation and transplantation on the other. Yet, these physicians, nurses and transplant coordinators do their utmost best to keep a strict line between euthanasia and organ donation, to avoid any external pressure on the patient, and to respect his autonomy. They really make an utmost attempt to make the process bearable for the donating patient. However, undeniably the patient who is about to undergo organ donation after euthanasia is nevertheless confronted with dozens of feelings and thoughts. However, this does not imply that procedural safeguards are failing to disentangle organ donation from euthanasia.
The sensitivity and specificity of TOF-MRA compared with DSA in the follow-up of treated intracranial aneurysms
Authors: Xiang Sishi , Fan Fu , Hu Peng , Yang Kun , Zhai Xiaodong , Geng Jiewen , Ji Zhe , Lu Jie , Zhang Hongqi
Published: February 2021

Background

Time-of-flight magnetic resonance angiography (TOF-MRA) is widely used in detecting intracranial aneurysms (IA), but it is limited and controversial for use during follow-up to assess the outcome of interventional coiling or clipping surgery.

Methods

To evaluate the specificity and sensitivity of using TOF-MRA as an imaging follow-up for IA with different treatments. A total of 280 patients with 326 treated IA underwent simultaneous TOF-MRA and digital subtraction angiography (DSA) as follow-up imaging on the same day. All images were independently reviewed by two neurosurgeons and two radiologists. The consensus evaluation of intra-arterial DSA as a reference test was used to evaluate the result of aneurysm occlusions. The aneurysmal embolization status was assessed with two ratings involving complete or incomplete occlusions. We calculated the sensitivity, specificity, negative predictive value, and positive predictive value of three-dimensional-TOF-MRA to investigate the diagnostic performance.

Results

Overall sensitivity and specificity of TOF-MRA for diagnosing the remnant were 83.3% and 95.2%, respectively. The sensitivity and specificity of interventional therapy was 90.0% and 94.2%, respectively, while the clipping group showed sensitivity and specificity of 50.0% and 100%, respectively. For additional groups, involving coil only, stent-assisted, and flow diverter, the analysis of interventional therapy showed sensitivities and specificities of 100.0% and 90.1%, 66.7% and 95.1%, and 91.7% and 100%, respectively.

Conclusions

TOF-MRA can be used as a first-line noninvasive imaging modality during follow-up, especially for the patients treated with a pipeline embolization device and coils only. But it may not be enough for clipped aneurysms.
Insights into the pathogenesis of cerebral fusiform aneurysms: high-resolution MRI and computational analysis
Authors: Sabotin Ryan Phillip , Varon Alberto , Roa Jorge A , Raghuram Ashrita , Ishii Daizo , Nino Marco , Galloy Adam E , Patel Devanshee , Raghavan Madhavan L , Hasan David , Samaniego Edgar A
Published: February 2021

Background

Intracranial fusiform aneurysms are complex and poorly characterized vascular lesions. High-resolution magnetic resonance imaging (HR-MRI) and computational morphological analysis may be used to characterize cerebral fusiform aneurysms.

Objective

To use advanced imaging and computational analysis to understand the unique pathophysiology, and determine possible underlying mechanisms of instability of cerebral fusiform aneurysms.

Methods

Patients with unruptured intracranial aneurysms prospectively underwent imaging with 3T HR-MRI at diagnosis. Aneurysmal wall enhancement was objectively quantified using signal intensity after normalization of the contrast ratio (CR) with the pituitary stalk. Enhancement between saccular and fusiform aneurysms was compared, as well as enhancement characteristics of fusiform aneurysms. The presence of microhemorrhages in fusiform aneurysms was determined with quantitative susceptibility mapping (QSM). Three distinct types of fusiform aneurysms were analyzed with computational fluid dynamics (CFD) and finite element analysis (FEA).

Results

A total of 130 patients with 160 aneurysms underwent HR-MRI. 136 aneurysms were saccular and 24 were fusiform. Fusiform aneurysms had a significantly higher CR and diameter than saccular aneurysms. Enhancing fusiform aneurysms exhibited more enhancement of reference vessels than non-enhancing fusiform aneurysms. Ten fusiform aneurysms underwent QSM analysis, and five aneurysms showed microhemorrhages. Microhemorrhage-positive aneurysms had a larger volume, diameter, and greater enhancement than aneurysms without microhemorrhage. Three types of fusiform aneurysms exhibited different CFD and FEA patterns.

Conclusion

Fusiform aneurysms exhibited more contrast enhancement than saccular aneurysms. Enhancing fusiform aneurysms had larger volume and diameter, more enhancement of reference vessels, and more often exhibited microhemorrhage than non-enhancing aneurysms. CFD and FEA suggest that various pathophysiological processes determine the formation and growth of fusiform aneurysms.
American Society of Regional Anesthesia and Pain Medicine expert panel recommendations on point-of-care ultrasound education and training for regional anesthesiologists and pain physicians—part I: clinical indications
Authors: Haskins Stephen C , Bronshteyn Yuriy , Perlas Anahi , El-Boghdadly Kariem , Zimmerman Joshua , Silva Marcos , Boretsky Karen , Chan Vincent , Kruisselbrink Richelle , Byrne Melissa , Hernandez Nadia , Boublik Jan , Manson William Clark , Hogg Rosemary , Wilkinson Jonathan N , Kalagara Hari , Nejim Jemiel , Ramsingh Davinder , Shankar Hariharan , Nader Antoun , Souza Dmitri , Narouze Samer
Published: February 2021

Point-of-care ultrasound (POCUS) is a critical skill for all regional anesthesiologists and pain physicians to help diagnose relevant complications related to routine practice and guide perioperative management. In an effort to inform the regional anesthesia and pain community as well as address a need for structured education and training, the American Society of Regional Anesthesia and Pain Medicine (ASRA) commissioned this narrative review to provide recommendations for POCUS. The guidelines were written by content and educational experts and approved by the Guidelines Committee and the Board of Directors of the ASRA. In part I of this two-part series, clinical indications for POCUS in the perioperative and chronic pain setting are described. The clinical review addresses airway ultrasound, lung ultrasound, gastric ultrasound, the focus assessment with sonography for trauma examination and focused cardiac ultrasound for the regional anesthesiologist and pain physician. It also provides foundational knowledge regarding ultrasound physics, discusses the impact of handheld devices and finally, offers insight into the role of POCUS in the pediatric population.
Bronchiectasis severity correlates with outcome in patients with primary antibody deficiency
Authors: Periselneris Jimstan , Schelenz Silke , Loebinger Michael , Macedo Patricia , Adhya Zoe , Armstrong-James Darius , Kelleher W Peter
Published: February 2021

Bronchiectasis is a well-recognised complication of primary antibody deficiency (PAD) syndromes. Previous data suggest that mortality in common variable immune deficiency (CVID) is not associated with isolated bronchiectasis. A retrospective analysis of patients with CVID and specific antibody deficiency in two tertiary referral centres with lung disease was conducted. Severity of bronchiectasis at presentation was associated with mortality. Lower FEV1, colonisation with Pseudomonas aeruginosa and a diagnosis of COPD were also associated with mortality. Bronchiectasis is an important driver of mortality in patients with PAD syndromes.
Repeatability and sensitivity to change of non-invasive end points in PAH: the RESPIRE study
Authors: Swift Andrew J , Wilson Frederick , Cogliano Marcella , Kendall Lindsay , Alandejani Faisal , Alabed Samer , Hughes Paul , Shahin Yousef , Saunders Laura , Oram Charlotte , Capener David , Rothman Alex , Garg Pankaj , Johns Christopher , Austin Matthew , Macdonald Alistair , Pickworth Jo , Hickey Peter , Condliffe Robin , Cahn Anthony , Lawrie Allan , Wild Jim M , Kiely David G
Published: February 2021

End points that are repeatable and sensitive to change are important in pulmonary arterial hypertension (PAH) for clinical practice and trials of new therapies. In 42 patients with PAH, test–retest repeatability was assessed using the intraclass correlation coefficient and treatment effect size using Cohen’s d statistic. Intraclass correlation coefficients demonstrated excellent repeatability for MRI, 6 min walk test and log to base 10 N-terminal pro-brain natriuretic peptide (log10NT-proBNP). The treatment effect size for MRI-derived right ventricular ejection fraction was large (Cohen’s d 0.81), whereas the effect size for the 6 min walk test (Cohen’s d 0.22) and log10NT-proBNP (Cohen’s d 0.20) were fair. This study supports further evaluation of MRI as a non-invasive end point for clinical assessment and PAH therapy trials.

Trial registration number NCT03841344.