bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation of a Relational Database Approach to a Multidisciplinary Conceptual Design for the HSCT
Authors: Hall Neil S. , Fulton Robert E.
Published: February 2021

New aerospace designs will incorporate new concepts as a result of advances made in the scientific and engineering technologies. These new concepts will afford the aircraft designer with an interesting and somewhat envious dilemma. The aircraft designer will have unprecedented flexibility in design concepts. However, this new flexibility will often be paralleled in ever increasing design complexity. Aircraft such as the High Speed Civil Transport (HSCT) will provide a design environment which will require the efficient use of new technologies in an arena which has historically proven to have stringent performance and cost goals which must be met in order to result in a successful design. The complexity of the HSCT design will dictate a close multidisciplinary effort requiring large amounts of data exchange. Moreover, with the enormous development costs associated with such a design, corporate teaming is essential. It is critical to the success of the HSCT and future aircraft design that a new approach be taken toward the management and exchange of information. A top-down data management design structure should be developed and implemented in the early stages in order to optimize the design process. A small scale multidisciplinary relational database management design has been developed for the HSCT in order to gain a better understanding of how efficient data management can optimize the aircraft design process.
Choosing Between Manual and Automated Methods for Assembly Operations: A Systematic Procedure
Authors: Mital Anil , Pennathur Arunkumar
Published: February 2021

Product assembly is a major consideration when designing products for manufacture as the method of assembly (manual, hybrid, or automated) often dictates, among other things the design of components, the assembly process and associated tooling. The choice of assembly method is, on the other hand, frequently dictated by technical and economic considerations. If the technical and economic considerations favor one method over the other, the decision-making is straight forward. However, when a product can be assembled either manually or with the assistance of automated equipment, the designer is confronted with the decision to choose between the two methods. This article provides a systematic procedure for choosing the assembly method in the event both manual and automated assembly methods are technically feasible.
Computer Considerations for Advanced Robotics
Authors: Kapoor Chetan , Pettus Nathan , Hooper Rich , Tesar Delbert
Published: February 2021

Mechanical systems for manufacturing in the past have represented monolithic, dedicated machines which remain expensive and inflexible relative to product changes due to market demands. It is the goal of the Robotics Research Group at the University of Texas at Austin (UTRRG) to develop a complete generalized modular architecture for intelligent machines (robots). This paper discusses the various issues involved in the design and selection of system controller hardware, servo controller hardware, real-time software, operating systems, and the software design methodologies. These constructs are required for the realization of a revolutionary, advanced intelligent flexible manufacturing system which offers the same success potential as that of a personal computer.
A Programming Technique for Multifunctional Use of Industrial Robots
Authors: Balkan Tuna
Published: February 2021

In this study, a software is developed in order to use an industrial robot, specifically an arc welding robot, as a palletizing robot by using programming codes of a FANUC ARC Mate Sr. on a FANUC R-G2 controller environment. The software performs all standard palletizing options of a material handling robot in the same category without requirement of any optional built-in software. In addition, multiplication and division can be performed without any optional software for these functions, by using standard addition and subtraction software. Thus, with the algorithm of the developed software, an industrial robot for a certain application may be used for palletizing without any extra cost for optional software.
Workspace Cusp Locations, and Simplified Workspace Boundary Equations for General RRR Regional Structures of Manipulators
Authors: Riley Peregrine E. J. , Torfason Louis E.
Published: February 2021

General, complex geometry forms of RRR regional structures are often avoided due to the presence of inner boundaries within the workspace which tend to complicate robot guidance. Despite the added complexity, certain RRR geometries may have useful applications as they contain large workspace regions where four alternate configurations may be used to reach a given spatial location. Cusp points often appear on the workspace boundaries of general RRR regional structures, and determining their precise location may be useful for both design and guidance purposes.

A twelfth degree polynomial equation in the outer joint variable is derived which defines the location of non-trivial cusps in the workspace.

A new closed form workspace boundary equation is derived in the outer joint variable and x coordinate of the toroidal surface generated by rotation of the two outer revolutes. If the outer joint variable is incremented, a quadratic in x is formed at each step which enables a very efficient determination of the workspace boundaries while also providing the coordinates of the boundary on the toroidal surface.
An Efficient Algorithm to Determine the Intersection of Simple Polygons for Robot Path Planning
Authors: Miao S. , Howard D.
Published: February 2021

This paper presents an efficient algorithm for determining the intersection of two simple polygons. The proposed algorithm is based on the idea of searching for the vertices of the intersection polygon vertex by vertex along the boundary in a clockwise direction. This method finds the intersection polygon vertices and their order in one pass. The algorithm almost eliminates the need for testing whether candidate vertices are inside both polygons and the sorting stage is no longer needed.
A Numerical Method and Automatic Generation for Determining the Assemblage Configurations of Complex Planar Linkages Based on the Ordered Single-Opened-Chains
Authors: Hui-Ping Shen , Ting-Li Yang
Published: February 2021

This paper presents a simple numerical evaluation method for solving all possible assembly configurations on an any position of the input link of some complex planar linkages according to the structural theory of mechanism based on the ordered Single-Opened-Chains (S.O.Cs). This method can simultaneously checks on whether the input link is a crank of the linkage. This paper also discovers that full-cycle ratability (F.C.R) of a linkage depends on not only the length of links of the linkage but also the different assembly configurations of the linkage after analysis of assemblage configurations.

The illustration for solution and analysis of assembly configurations of a complex planar linkage is given in detail.

This paper provides the actual assembly of linkages and the optimization of structure synthesis of linkages with some important information.
Optimal Sensor Location in Motion Control of Flexibly Supported Long Reach Manipulators
Authors: Mavroidis Constantinos , Dubowsky Steven , Thomas Kevin
Published: February 2021

Long reach manipulator systems (LRMS) can perform tasks in difficult to reach locations. They use a small and fast manipulator mounted on a large flexible structure that can vibrate, degrading the system performance. Control methods that use strain measurements of the flexible structure have been proposed to control the system’s position in spite of the supporting structure’s vibrations using a model of the structure that relates strains to displacements. Here the minimum number of strain sensors needed to accomplish this control and their optimal locations on the flexible supporting structure are determined. These locations have been selected to achieve high measurement resolution, to maximize the computational robustness and to minimize the error in the identification of the structure’s strain-displacement model. The results are validated with simulations and experiments using a six degree of freedom laboratory LRMS.
The Forward Position Problem of Two Puma-Type Robots Manipulating a Bennett Linkage Payload
Authors: Pennock Gordon R. , Mattson Keith G.
Published: February 2021

This paper presents a solution to the forward position problem of two PUMA-type robots manipulating a Bennett linkage payload. The orientation of a specified payload link is described by a sixth-order polynomial and a specified angular joint displacement in the wrist subassembly of one of the robots is described by a second-order polynomial. A solution technique, based on orthogonal transformation matrices with dual number elements, is used to obtain closed-form solutions for the remaining unknown angular joint displacements in the wrist subassembly of each robot. The paper shows that, for a given set of robot input angles, twenty-four assembly configurations of the robot-payload system are possible. The polynomials provide insight into these configurations, and also reveal stationary configurations of the system. The paper emphasizes that insight into the kinematic geometry of the system is essential in developing the forward position solution. Graphical methods are presented which provide insight into the geometry, and a check of the analytical approach. For illustrative purposes, a numerical example of the two robots manipulating a Bennett linkage is included in this paper to demonstrate the importance of the polynomials and the closed-form solutions.
On the Geometry of Spatial Polygons and Screw Polygons
Authors: Mavroidis Constantinos , Roth Bernard
Published: February 2021

In this paper we study spatial polygons which are closed figures composed of ordered sets of lines and their common normals. It is shown how to solve for up to six of the parameters which define a polygon’s geometry, after all the other parameters are specified. It is also shown that when screws are used instead of lines, the resulting figures, called screw polygons, can be analyzed in order to determine up to twelve parameters, provided all the other parameters which define the screws and the screw polygon are known. Finally, it is pointed out that these results have many potential uses in kinematics.
Determination of Translation Component of Screw Axis From Double-Exposure Holographic Interferograms
Authors: Sanchez L. A. , Zurek A. D. , Griffis J. A.
Published: February 2021

In mechanism design, it is often necessary to accurately measure the relative motions produced by an assembly of rigid bodies connected by joints. A number of analytical tools exist for the theoretical kinematic analysis of the relative motions produced by such an assembly. However, a relatively limited number of corresponding experimental methods for handling such motions exist. Optical methods are especially useful because they do not require that the measurement system touch the assembly being analyzed. A photo-optical method, holographic interferometry, is presented for the experimental determination of finite screw displacements. The purpose of this paper is to show how double-exposure holographic interferograms can be used to provide information about screw axes for general motions of an object in three-dimensional space. This investigation deals with the translation component of a screw axis and categorizes the fringe patterns resulting from in-plane and out-of-plane translations and their combinations. The resulting screw axis for each special displacement case is computed.
Workspace of Four-Degree-of-Freedom Manipulators
Authors: Abdel-Malek Karim , Yeh Harn-Jou
Published: February 2021

An analytical method is presented to obtain all boundary surfaces to the accessible output set of four degree-of-freedom serial manipulators. The method is applicable to all manipulators that comprise combinations of prismatic and revolute joints. Position constraints of the end-effector of such mechanisms are formulated using the Denavit-Hartenberg representation. Examining the Jacobian of the underlying mechanism using a row-rank deficiency method yields sets of first-order singularities. These sets of singularities are substituted into the position constraint equations yielding parametric surfaces upon which the manipulator looses at least one degree of mobility. Singular curves are determined by intersecting singular surfaces. Due to the complexity of intersecting parametric singular surfaces, the resultant singular curves are numerically computed. Bifurcation points are identified and tangents are computed. Singular surfaces are partitioned into sub-surfaces that are studied for existence inside the accessible output set using a proposed perturbation technique. The result is a number of sub-surfaces that envelop the accessible output set. The theory presented is validated using a four-degree-of-freedom example.
Parametric Study of Platform Manipulators
Authors: Ji Zhiming
Published: February 2021

Multi-loop parallel structures of platform manipulators present challenge to their design analysis. For studying the workspace of the 3-6 class of platforms, we developed the “vertex space” concept in (Ji, 1994). This paper extends the “vertex space” concept to other structures for analyzing and comparing their workspaces. We classify the vertices of the platform manipulators into types A and B. The platform manipulators are then divided into four groups based on their vertex types. Design parameters in platform manipulators are studied in terms of their functions and effects to vertex spaces and workspace.
Synthesis of Planar RR Dyads by Constraint Manifold Projection
Authors: Larochelle Pierre M.
Published: February 2021

In this paper we present the constraint manifold of the planar RR dyad. The constraint manifold is an analytical representation of the workspace of the dyad. We then derive a technique, utilizing the constraint manifold, for performing the dimensional synthesis of planar RR dyads for approximate rigid body guidance through n positions. Finally, we present the implementation of the design methodology in the software VISSYN and discuss its use in a design case study.
A Closed Form Method for Backtracking From a Modified Burmester Curve to a Set of Precision Positions
Authors: Watkins Derek , Nisbett J. Keith
Published: February 2021

A method is presented, in the context of Burmester theory, which backtracks from a modified set of poles to a set of precision positions which is likely to satisfy the original precision position tolerances. The motivation is to provide a means of manipulating the Burmester curves into desired regions by moving the poles rather than the precision positions directly. The procedure correlates a movement of a pole to a new set of precision positions which are determined to be more than likely nearest to the original set of precision positions. By checking the most likely precision positions, it is not necessary to check the remaining infinite possible sets of precision positions. Thus, even though it is theoretically impossible to backtrack from four poles to a unique set of precision positions, with this method it is practically possible to do so.
Closed-Form Displacement Analysis of SDOF 8 Link Mechanisms
Authors: Almadi Abdulaziz N. , Dhingra Anoop K. , Kohli Dilip
Published: February 2021

This paper presents closed-form solutions to the displacement analysis problem of planar 8-link mechanisms with a single degree of freedom (SDOF). The degrees of I/O polynomials as well as the number of possible assembly configurations for all 71 8-link mechanisms resulting from 16 8-link kinematic chains are presented. Three numerical examples illustrating the applicability of the successive elimination procedure to the displacement analysis of 8-link mechanisms are presented. The first example deals with the determination of I/O polynomial for an 8-link mechanism containing no four-bar loops. The second and third examples, address in detail, some of the problems associated with the conversion of transcendental loop-closure equations into an algebraic form using tangent half-angle substitutions. These examples illustrate how extraneous roots can get introduced during the displacement analysis of mechanisms, and how one can derive an I/O polynomial devoid of the extraneous roots. Extensions of the proposed approach to the displacement analysis of SDOF spherical 8-link mechanisms is also presented.
Inertia Effects in Cardan-Joint Operation
Authors: Fischer Ian S.
Published: February 2021

The inertia effects occurring in a Cardan-type universal joint operated at speed are considered in the calculation of dynamic force and torque reactions. A dual-number formulation has been used so that manufacturing and installation tolerances can be considered.
Case Studies and a Note on the Degrees-of-Freedom in Compliant Mechanisms
Authors: Ananthasuresh G. K. , Howell Larry L.
Published: February 2021

The presence of compliant members in a mechanism makes the determination of its degrees-of-freedom out of reach of the traditional Grübler’s formula, as this formula does not account for the additional mobility allowed by compliance. Recent research efforts have led to a generalization of Grübler’s formula that encompasses compliant mechanisms as well. The objective of this work is to apply the formula to a set of practical compliant devices, and further clarify and simplify the approach. This is accomplished as follows: i) The concept of “virtual rigid segments” is introduced to facilitate the identification of the segment compliance of distributed segments with forces applied to them. ii) The motion of compliant devices is interpreted by identifying the inputs equal in number to the calculated possible degrees of freedom. iii) A wide variety of case studies are presented to illustrate the method of application and the value of the approach.
Constraint Manifold Synthesis of Planar Linkages
Authors: Murray A. P. , McCarthy J. M.
Published: February 2021

This paper formulates the design theory of planar four-bar linkages using the planar form of dual quaternions known as planar quaternions. The set of positions reachable by the floating link of a dyad is a quadratic algebraic surface called a constraint manifold. Determining the coefficients of the quadratic form defining this manifold is equivalent to setting the design parameters of the linkage. If the task of the linkage is specified as geometric constraints on the location of the floating link, then algebraic constraints are obtained on the quaternion components. We seek the coefficients of the constraint manifold that satisfies these constraints. The result is an algebraic formulation that is symmetric in its characterization of the linkage and task, and provides a versatile tool for the formulation and solution of linkage design problems.
Trajectory Planning Methods for Conservative Motion of Redundant Manipulators
Authors: Chyu Younker , Song Shin-Min
Published: February 2021

The extra degrees of freedom of a redundant manipulator can be used to improve dexterity, to avoid singularity and to optimize certain performance criterion such as energy consumption. However, the motion of a redundant manipulator is usually not conservative while it is tracking a repetitive task. That is, it requires re-calculation of its motion at each increment in a repetitive task. Therefore, conservative motion has been a research topic of redundant manipulators. In this paper, two trajectory-planning methods based on the pseudo-inverse method and Euler Taylor-series are presented. These two methods enable us to obtain a convergent configuration(s) after repetitive motion cycles and the motions become conservative after the manipulator reaches the convergent configuration(s). The required number of iterations could be exceedingly large for certain trajectories. Two methods which are able to efficiently identify the convergent configuration(s) are also presented. This study is based on a three-linked planar manipulator tracking four trajectories: circles, ellipses, squares and line segments.
Simulation and Design of Two-Degree-of-Freedom Underactuated Mechanical Fingers
Authors: Laliberté Thierry , Gosselin Clément M.
Published: February 2021

The design of underactuated mechanical fingers is addressed in this article. The objective of the research is to design a robust mechanical hand capable of performing industrial tasks involving the grasping of a wide variety of objects with large forces. To this end, the taxonomy of the grasps is first reviewed. Then, the principle of underactuation — which leads to shape adaptation of the hands — is introduced and a review of the existing underactuated mechanical hands is provided. Architectures of two-degree-of-freedom underactuated fingers are then proposed and a simulation tool is designed to analyze their behavior. It is shown that underactuation is a very promising avenue when only grasping is required (no manipulation). Simulation results are given and discussed in order to illustrate the usefulness of the simulator and general design guidelines are proposed. Finally, a design of an underactuated finger is presented as an example. The design presented here demonstrates that the use of underactuation can lead to versatile grasping capabilities with reduced complexity.
Analysis and Synthesis of Underactuated Force Generating Mechanisms
Authors: Gosselin Clément M.
Published: February 2021

In this paper, the analysis and synthesis of underactuated mechanisms used to generate prescribed external forces is addressed. The main objective of the article is to introduce the concept of mechanism synthesis for force generation, as opposed to motion generation. Underactuated mechanisms are first defined and their analysis is formulated. Then, passive mechanisms obtained from architectures of parallel manipulators are introduced and the analysis is repeated for this particular class of mechanisms. The synthesis problem is then formulated for passive mechanisms and for mechanisms with actuators, in a general framework. Finally, simple examples of the analysis and synthesis of passive mechanisms are given in order to illustrate the concepts.
Modeling, Simulation and Realization of an Autonomous Six Legged Walking Machine
Authors: Bührle Peter , Cordes Stefan
Published: February 2021

In the following paper, the realization of a six legged walking machine is presented, using the benefits of a dynamic simulation of an abstracted model. In order to ensure the success of such a complex system, the suitability of single components (geometry, drives, gears, control algorithm) as well as of the entire system has to be examined in the pre-manufacturing phase. For that reason the walking machine is modeled as a multibody system and simulated in a developed program package, taking the dynamics of the drives into consideration. In a second part, the realization of the robot is described, presenting the used drives, sensors and control architecture.
Stability Analysis of Multi-Bar Elastic Linkage Mechanisms
Authors: Xianmin Zhang , Caoweiqing Liu Hongzhao
Published: February 2021

An important question facing a designer is wether a certain machine system will have a stable operating condition. In this paper, the distributions of the critical running speeds of flexible linkage mechanisms are investigated theoretically by utlizing the Floquet theory. The explicit relationships between the critical running speeds and the average frequencies of the linkage mechanisms in a period are presented. The relationships are suitable for the linkage mechanisms with all links considered as elastic members and having large number of elastic degrees of freedom. Numerical verifications for the relationships are provided.
A New Method for Full Shaking Force Balancing of Planar Linkages by a Few Finite Positions
Authors: Yang Ting-Li , Zhang Ming , Jin Qiong
Published: February 2021

A new method called “Finite Position Method” is presented in this paper. By means if this method, it is easy to obtain the condition for full shaking force balancing of planar linkages (FSFBPL), to derive the counter theorem and the minimum number of counterweights. The balancing condition could be generated easily via establishing and solving a system of linear equations using a few finite position data of the linkage. The basic principle of this method could be expanded to the study for balancing theory of the spatial linkages.
Compensatory Trunk Movements in Naturalistic Reaching and Manipulation Tasks in Chronic Stroke Survivors
Authors: Jayasinghe Shanie A.L. , Wang Rui , Gebara Rani , Biswas Subir , Ranganathan Rajiv
Published: February 2021

Impairment of arm movements poststroke often results in the use of compensatory trunk movements to complete motor tasks. These compensatory movements have been mostly observed in tightly controlled conditions, with very few studies examining them in more naturalistic settings. In this study, the authors quantified the presence of compensatory movements during a set of continuous reaching and manipulation tasks performed with both the paretic and nonparetic arm (in 9 chronic stroke survivors) or the dominant arm (in 20 neurologically unimpaired control participants). Kinematic data were collected using motion capture to assess trunk and elbow movement. The authors found that trunk displacement and rotation were significantly higher when using the paretic versus nonparetic arm (P = .03). In contrast, elbow angular displacement was significantly lower in the paretic versus nonparetic arm (P = .01). The reaching tasks required significantly higher trunk compensation and elbow movement than the manipulation tasks. These results reflect increased reliance on compensatory trunk movements poststroke, even in everyday functional tasks, which may be a target for home rehabilitation programs. This study provides a novel contribution to the rehabilitation literature by examining the presence of compensatory movements in naturalistic reaching and manipulation tasks.
New U.K. funding agency aims to tackle innovative research
Authors: O'Grady Cathleen
Published: February 2021

Like ARPA in the United States, ARIA will fund risky ideas. But some worry that fledgling agency lacks a focus.
Shifting ground
Authors: Rosen Julia
Published: February 2021

Fleets of radar satellites are measuring movements on Earth like never before.
Illuminating tremors in the deep
Authors: Wilcock William
Published: February 2021

Telecommunication cables on the seafloor monitor seismic activity
Copper- and cobalt-rich, ultrapotassic bittern brines responsible for the formation of the Nkana-Mindola deposits, Zambian Copperbelt
Authors: Davey James , Roberts Stephen , Wilkinson Jamie J.
Published: February 2021

The Central African Copperbelt (CACB) is Earth’s largest repository of sediment-hosted copper and cobalt. The criticality of these elements in battery technology and electricity transmission establishes them as fundamental components of the carbon-free energy revolution, yet the nature and origin of the hydrothermal fluids responsible for ore formation in the CACB remain controversial. Here, we present microthermometric, scanning electron microscopy and laser ablation–inductively coupled plasma–mass spectrometry analyses of fluid inclusions from the Nkana-Mindola deposits in Zambia. We find that base metal concentrations vary by one to two orders of magnitude between “barren” and “ore” fluids, with concomitant distinctions in major salt chemistry. Primary fluid inclusions, hosted by pre- to synkinematic mineralized quartz veins, are characterized by high homogenization temperatures (∼200–300 °C) and salinities, with K/Na >0.8 and elevated metal concentrations (102 to 103 ppm Cu and Co). Conversely, barren, postkinematic vein quartz contains lower homogenization temperature (∼110–210 °C) and lower-salinity primary inclusions, characterized by K/Na <0.8 with low metal contents (<102 ppm Cu and Co). We propose a model in which high-temperature, sulfate-deficient, metalliferous, potassic residual brines, formed during advanced evaporation of CaCl2-rich, mid-Neoproterozoic seawater, were responsible for ore formation. During basin closure, lower-temperature, halite-undersaturated fluids interacted with evaporites and formed structurally controlled, sodic metasomatism. Reconciliation of these fluid chemistries and base metal concentrations with reported alteration assemblages from a majority of Zambian Copperbelt deposits suggests highly evolved, residual brines were critical to the formation of this unique metallogenic province.
Timeout procedure in paediatric surgery: effective tool or lip service? A randomised prospective observational study
Authors: Muensterer Oliver J , Kreutz Hendrik , Poplawski Alicia , Goedeke Jan
Published: February 2021

Background

For over a decade, the preoperative timeout procedure has been implemented in most paediatric surgery units. However, the impact of this intervention has not been systematically studied. This study evaluates whether purposefully introduced errors during the timeout routine are detected and reported by the operating team members.

Methods

After ethics board approval and informed consent, deliberate errors were randomly and clandestinely introduced into the timeout routine for elective surgical procedures by a paediatric surgery attending. Errors were randomly selected among wrong name, site, side, allergy, intervention, birthdate and gender items. The main outcome measure was how frequent an error was reported by the team and by whom.

Results

Over the course of 16 months, 1800 operations and timeouts were performed. Errors were randomly introduced in 120 cases (6.7%). Overall, 54% of the errors were reported; the remainder went unnoticed. Errors were pointed out most frequently by anaesthesiologists (64%), followed by nursing staff (28%), residents-in-training (6%) and medical students (1%).

Conclusion

Errors in the timeout routine go unnoticed by the team in almost half of cases. Therefore, even if preoperative timeout routines are strictly implemented, mistakes may be overlooked. Hence, the timeout procedure in its current form appears unreliable. Future developments may be useful to improve the quality of the surgical timeout and should be studied in detail.
Radiological dynamics and SITC-defined resistance types of advanced melanoma during anti-PD-1 monotherapy: an independent single-blind observational study on an international cohort
Authors: Bai Xue , Kim Michelle , Kasumova Gyulnara , Si Lu , Tang Bixia , Cui Chuanliang , Yang Xiaoling , Wei Xiaoting , Cohen Justine , Lawrence Donald , Freedman Christine , Fadden Riley , Rubin Krista , Sharova Tatyana , Frederick Dennie , Flaherty Keith , Sullivan Ryan , Guo Jun , Boland Genevieve
Published: February 2021

Background

Although the Society for Immunotherapy of Cancer (SITC) Immunotherapy Resistance Taskforce recently defined primary and secondary resistance to anti-programmed cell death protein 1 (anti-PD-1) therapy, there is lack of real-world data regarding differences in these resistance subtypes with respect to radiological dynamics and clinical manifestations.

Methods

We performed single-blind re-evaluations of radiological images by independent radiologists on a retrospectively assembled cohort of patients with advanced melanoma (n=254, median follow-up 31 months) receiving anti-PD-1 monotherapy at Massachusetts General Hospital and Peking University Cancer Hospital. Radiological characteristics and timing at multiple crucial time points were analyzed and correlated with each other and with survival. Primary and secondary resistance was defined as per the SITC Immunotherapy Resistance Taskforce definitions.

Results

The most significant target lesion measurement change took place within the first 3 months after anti-PD-1 initiation. Patients with stable disease with versus without tumor shrinkage at the initial evaluation exhibited distinct disease trajectory, as the rate of further upgrade to a partial or complete remission (CR/PR) was 44% and 0%, respectively. Eleven per cent of PR patients ultimately achieved a CR. In multivariate analyses, deeper response depth was independently associated with a more limited progression pattern, fewer involved organs, lower tumor burden, slower growth rate at disease progression (PD) (all p≤0.001), and longer post-progression survival (PPS) (bivariate analysis, p=0.005). Compared with primary resistance, secondary resistance was associated with less widespread PD pattern, lower tumor burden and slower tumor growth (all p≤0.001). Patients with secondary resistance were less likely to receive further systemic therapy (28% vs 57%, p<0.001) yet had significantly better PPS (HR 0.503, 95% CI 0.288 to 0.879, p=0.02).

Conclusions

Radiological dynamics were variable, yet significantly correlated with survival outcomes. SITC-defined primary and secondary resistance are distinct clinical manifestations in patients with melanoma, suggesting the possibility of resistance-type-based therapeutic decision-making and clinical trial design, once further validated by future prospective studies.
Doughnut vertebroplasty for circumferential aggressive vertebral hemangiomas
Authors: Roscop Cecile , Gariel Florent , Kieser David Christopher , Bouyer Benjamin , Gille Olivier , Marnat Gaultier , Berge Jerome
Published: February 2021

Background

To assess the feasibility, safety and efficacy of a percutaneous doughnut vertebroplasty of circumferential aggressive vertebral hemangiomas (VHs).

Methods

We retrospectively reviewed our prospectively collected database of patients with VHs treated with vertebroplasty between January 2009 and January 2018. Patient demographics, clinical presentations and procedural details were recorded. All patients underwent preoperative computed tomography (CT) and magnetic resonance imaging (MRI). All vertebroplasties were performed under conscious sedation in the prone position, predominantly using biplane fluoroscopic guidance. A clinical and imaging evaluation (early CT scan and MRI) as well as a final follow-up clinical assessment was performed.

Results

Twenty-two patients with aggressive VHs who underwent circumferential vertebroplasty with cementation of the entire vertebral body and at least one posterior hemi-arch were included (six males, mean age 53 years). At 3 months follow-up, nine patients (41%) had complete, 11 (50%) had partial and two (9%) had no resolution of pain. Nine of 14 patients had a decrease in venous swelling on MRI. No complications were observed. Five patients (23%) underwent adjunctive surgery within 1 year for persistence or worsening of neurological symptoms. Clinical and radiographic improvements were maintained to final follow-up.

Conclusions

Doughnut vertebroplasty offers a mini-invasive, safe and effective treatment of aggressive circumferential VHs. This technique improves pain in over 90% of patients as well as a reduction in radicular and neurological symptoms associated with a tendency to regression of the compressive epidural venous component of these lesions.
Balloon guide catheter improvements in thrombectomy outcomes persist despite advances in intracranial aspiration technology
Authors: Blasco Jordi , Puig Josep , Daunis-i-Estadella Pepus , González Eva , Fondevila Monso Juan Jose , Manso Xabier , Oteros Rafael , Jimenez-Gomez Elvira , Bravo Rey Isabel , Vega Pedro , Murias Eduardo , Jimenez Jose Maria , López-Rueda Antonio , Renú Arturo , Aixut Sonia , Chirife Chaparro Oscar , Rosati Santiago , Moreu Manuel , Remollo Sebastian , Aguilar Tejedor Yeray , Terceño Mikel , Mosqueira Antonio , Nogueira Raul G , San Roman Luis
Published: February 2021

Background

First-pass effect (FPE) has been established as a key metric for technical success and strongly correlates with better clinical outcomes. Most data supporting improved outcomes with the use of a balloon guide catheter (BGC) predate the advent of last-generation large-bore intracranial aspiration catheters. We aim to evaluate the impact of BGC in FPE and clinical outcomes in a large cohort of patients treated with contemporary technology.

Methods

Patients were recruited from the prospectively ongoing ROSSETTI registry. This registry includes all consecutive patients with anterior circulation large-vessel occlusion (LVO) from 10 comprehensive stroke centers in Spain. Demographic, clinical, angiographic, and clinical outcome data were compared between BGC and non-BGC groups. FPE was defined as the achievement of mTICI2c–3 after a single device pass.

Results

426 patients were included out of which 271 (63.62%) used BCG. BGC-treated patients had higher FPE rate (45.8% vs 27.7%; P<0.001), higher final mTICI ≥2 c recanalization rate (76.8% vs 50.3%, respectively; P<0.001), shorter procedural time [median (IQR), 30 (19–58) vs 43 (33–71) min; P<0.001], higher NIHSS difference from admission to 24 hours [median (IQR), 8 (2–12) vs 3 (0–10); P=0.001], and lower mortality rate (17.6% vs 29.8%, P=0.026) compared with non-BGC patients. BGC use was an independent predictor of FPE (OR 2.197, 95% CI 1.436 to 3.361; P<0.001), and excellent clinical outcome at 3 months (OR 0.34, 95% CI 0.17 to 0.68; P=0.002).

Conclusions

Our results support the benefit of BGC use on angiographic and clinical outcomes in anterior circulation LVO ischemic stroke remain significant even when considering recent improvements in intracranial aspiration technology.
Stream diatom assemblages in an Arctic catchment: diversity and relationship to ecosystem-scale primary production
Authors: Riley Breena , Seekell David
Published: February 2021

We quantified benthic diatom diversity in streams in the Miellajokka catchment, about 200 km north of the Arctic circle in Sweden. Beta diversity among sites was related to local-scale environmental heterogeneity (occurring on the order of 1 km or less), and its magnitude was equal (Sørensen Index = 0.62) to levels previously reported for rivers on regional environmental gradients across hundreds of kilometres of Arctic Fennoscandia. Species turnover was the dominant (77%) component of beta diversity in the Miellajokka catchment. Small, stress-tolerant taxa dominated the assemblages, and there were no clear patterns of functional class among sites. Site ordinates from non-metric dimensional scaling were most strongly correlated with flood frequency (r = 0.83) and water temperature (r = 0.89), which was higher in harsh tundra sites than below treeline. Additionally, site ordinates were correlated (r = 0.83) with ecosystem-scale gross primary production — indicative of a link between diatom diversity and ecosystem function. Our results advance understanding of patterns diatom diversity in Arctic streams by quantifying local-scale variation that is understudied in this region, and by identifying the consequences of this local-scale diversity for an ecosystem-scale process.
Effect of replacing barley silage with calcium oxide-treated barley straw on rumen fermentation, rumen microbiota, nutrient digestibility, and growth performance of finishing beef cattle
Authors: Stehr Katelyn R. , Terry Stephanie A. , Ribeiro Gabriel O. , Gruninger Robert J. , Penner Gregory B. , McKinnon John , Gibb Darryl , McAllister Tim A.
Published: February 2021

Effect of calcium oxide (CaO) treatment of barley straw and salt on rumen fermentation, microbiota, digestibility, growth, and carcass quality of cattle was assessed. A replicated 4 × 4 Latin square metabolism experiment was conducted using eight heifers fed a wheat finishing diet with barley silage (B-SIL), barley straw (B-S), or 5.0% CaO-treated barley straw (CaOS) with or without NaCl (CaOS-NS). Growth over 115 d was assessed using 75 individually housed steers fed the above diets and an additional diet (I-CaOS), where CaO was added to straw just before feeding. There was no effect (P ≥ 0.08) of diet on rumen fermentation, digestibility, or carcass quality, although CaO decreased (P < 0.001) maximum pH and retained Na was decreased (P < 0.05) by CaOS-NS. Rumen bacterial abundance was altered (P ≤ 0.05) by diet. The average daily gain (ADG) of B-SIL and CaOS-NS steers was 14.1% greater (P ≤ 0.05) than BS and CaOS steers, whereas the gain:feed of CaOS-NS steers was 14.2% greater (P ≤ 0.05) than B-S and CaOS steers. Steers fed I-CaO had similar ADG and gain:feed to other treatments. CaO-treated straw without NaCl could replace barley silage in wheat diets, without compromising digestibility or growth in steers.
Considerations of variability and power for long-term monitoring of stream fish assemblages
Authors: George Scott D. , Stich Daniel S. , Baldigo Barry P.
Published: February 2021

Little attention has been given to optimizing statistical power for monitoring stream fish assemblages. We explored the relationship between temporal variability and statistical power using 34 metrics from fish community data collected annually at six sites over 10 years via electrofishing. Metric variability differed by the life stage and group of species considered, use of abundance or mass data, and data standardization technique. Lower variability was associated with community data, abundance data, and time-based standardizations, while greater variability was associated with young-of-the-year data, mass data, and area-based standardizations. Simulation-based power analysis indicated metric choice, and to a lesser degree, monitoring design (annual, biennial, endpoints, or haphazard sampling) influenced power to detect change. Across a fixed number of surveys (N = 60), endpoints sampling performed best. The N needed to detect change was heavily dependent upon metric choice for all monitoring designs, with the most biologically specific metrics requiring greater N. Large savings in effort and resource expenditure can be obtained utilizing biologically relevant metrics that are robust to temporal noise within an appropriate sampling design.
Impact of Platelet Glycoprotein Ia/IIa C807T Gene Polymorphisms on Coronary Artery Aneurysms of KD Patients
Authors: Li Wei , Pi Lei , Yuan Jia , Gu Xueping , Wang Zhouping , Liu Yunfeng , Deng Qiulian , Wang Yanfei , Huang Ping , Zhang Li , Gu Xiaoqiong
Published: February 2021

Background. Kawasaki disease (KD) is a systemic vasculitis of unknown etiology in children. Coronary artery abnormalities are the most common complications of KD. Recent evidence showed that genetic polymorphisms may lead to susceptibility to KD. Genetic variants in platelet glycoprotein have been reported to be associated with coronary artery disease. The aim of the present study is to investigate the correlation between the role of platelet glycoprotein and coronary artery aneurysms in KD patients. Methods. We did a case-control study that enrolled 818 KD patients and 1401 healthy children with the same age and sex from January 2013 to December 2016. Analysis of single-nucleotide polymorphism (rs1126643) of the platelet glycoprotein Ia/IIa C807T was performed by multiplex polymerase chain reactions in this study. Results. A significant difference in the genotype distribution between KD cases and controls was observed for the glycoprotein Ia/IIa C807T (rs1126643) polymorphism (

p
=
0.026

). Compared with the healthy children, the rs1126643T allele carriers had odds ratio (OR) of 0.63 for developing KD (TT vs. CC: adjusted OR = 0.62, 95% confidence interval (CI) = 0.43–0.88,

p
=
0.0078

; TT vs. CT/CC: adjusted OR = 0.63, 95% CI = 0.44–0.889,

p
=
0.0093

). Furthermore, we also found that children less than 60 months of age and female patients with rs1126643 T allele carriers had an adjusted OR of 0.66 (95% CI = 0.46–0.95) for noncoronary artery aneurysm patients (

p
=
0.0242

). Single-nucleotide polymorphism rs1126643 TT seems to represent a protective factor against KD in coronary artery aneurysm formation in multivariate analysis. Conclusions. The platelet glycoprotein Ia/IIa T allele carriers may have a protective effect on the risk of coronary artery aneurysms of KD patients, especially in females and children aged less than 60 months. These results may provide evidence for platelet glycoprotein Ia/IIa gene polymorphisms in the pathogenesis of KD patients.
Aspects of Semiclassical Black Holes: Development and Open Problems
Authors: Yosifov Alexander Y.
Published: February 2021

The current work is a review, dedicated to the study of semiclassical aspects of black holes. We begin by briefly looking at the main statements of general relativity. We then consider the Schwarzschild, Kerr, and Reissner-Nordstrom black hole solutions and discuss their geometrical properties. Later, the thermodynamic nature of black holes is established. In light of this, we formulate the information loss problem and present the most promising approaches for addressing it with emphasis on introducing low-energy quantum corrections to the classical general relativity picture. Finally, in the context of multimessenger astronomy, we look at naked singularities as possible gravitational collapse endstates and their role in the unitarity of quantum mechanics and discuss their observational prospects.
Identification of Chemical Composition and Metal Determination of Retama raetam (Forssk) Stem Constituents Using ICP-MS, GC-MS-MS, and DART-MS
Authors: Al-Onazi Wedad , Al-Mohaimeed Amal M. , Amina Musarat , El-Tohamy Maha F.
Published: February 2021

This study aims to investigate the chemical constituents of the stem of Retama raetam growing in Saudi Arabia. The organic and inorganic composition of ethanol extract of R. raetam stem has been explored using direct analysis in real time-mass spectrometry (DART-MS), gas chromatography-mass spectrometry (GC-MS), and inductively coupled plasma-mass spectrometry (ICP-MS). Analysis conducted by DART-MS and GC-MS reveals the presence of several interesting organic constituents identified as 2,4-di-tert-butylphenol, sparteine, benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, methyl ester, phthalic acid, 1-octadecanol, squalene, argentamin, 2,4-di-tert-butylphenol, sparteine, benzene propanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, methyl ester, phthalic acid, 1-octadecanol, squalene, argentamin, and hentriacontane in the ethanol extract of the R. raetam stem. The ICP-MS analysis of stem extract showed the presence of a significant amount of important inorganic elements including aluminum, chlorine, calcium, bromine magnesium, phosphorus, scandium, and chromium. The current study complements other R. raetam extract investigations carried out in the past and provides the additional data for the future research studies.
A Direct and Sensitive Method for Determination of 5-Fluorouracil in Colorectal Cancer Cells: Evaluating the Effect of Stromal Cell on Drug Resistance of Cancer Cells
Authors: Xu Fengjing , Wang Zhipeng , Song Xinhua , Zhang Mengwei , Cui Lili , Liu Yanping , Yan Hongxia , Gao Shouhong , Liu Yan , Chen Wansheng
Published: February 2021

Fibroblasts in the stroma play a critical role in tumor evolution. In this study, we assessed the influence of colonic fibroblasts on colon cancer cells treated with 5-fluorouracil (5-FU), and mouse colon cancer cell lines MC38 and colonic fibroblasts NIH3T3 were used in this study. A sensitive and rapid UHPLC-MS/MS method for the quantitation of 5-FU from the cell and their medium has been successfully developed and validated. The cells were lysed with methanol, and the mixture was evaporated and then redissolved to extract intracellular 5-FU. The analysis was performed on UHPLC-MS/MS using an Atlantis T3-C18 column (3 μm, 2. 1 ∗ 100 mm) and gradient elution with acetonitrile and 0.1% formic acid in water. Method validation included the following parameters: the matrix effect range 88.82%–93.64% and the recovery range 93.52%–94.56%. The intraday and interday precision and accuracy were <11% and within ±6%, and the stability, specificity, carry-over, dilution effect, and linearity all conformed to the criteria. The method was applied to detect the concentration of 5-FU inside cells and cell culture medium. The preliminary results present that NIH3T3 could enhance the drug resistance of MC38 to 5-FU with a decreased intracellular concentration of 5-FU in MC38, which showed a positive relationship with NIH3T3 number.