bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconstruction of Sculptured Surfaces Using Coordinate Measuring Machines
Authors: Hsieh Yuan C. , Drake Samuel H. , Riesenfeld Richard F.
Published: March 2021

This paper presents a strategy for reverse engineering that uses a coordinate measuring machine to reconstruct three-dimensional sculptured surfaces. A rough initial model of the surface is generated manually. An iterative method is then used to refine the surface model. The reverse engineering is broken down into three phases: data acquisition, surface reconstruction and surface evaluation. For data acquisition, an exhaustive search algorithm is used to find a safe probe orientation in the vicinity of the target surface, and a coarse cell decomposition method is followed to manipulate the coordinate measuring machine in its work space. Surfaces are modeled by using the B-spline approximation technique, and position difference between the surface model and the measured data is used as a simple criterium to evaluate the quality of the reconstructed surface model.
On the Finite Screw System of the Third Order Associated With a Revolute-Revolute Chain
Authors: Huang Chintien
Published: March 2021

The finite displacements of the outermost body of a revolute-revolute chain are investigated. All the possible screws of the finite twists of the outermost body of an R-R chain are shown to form a screw system of the third order. The analytic expression of the screw system is given. The finite screw systems of special configurations of an R-R chain as well as the degenerate forms of the finite 3-system in infinitesimal kinematics and in displacing two points of a body are also discussed.
Layout of Extensional Surface Damping Treatment for Minimal Resonance Response
Authors: Wodtke Hans-Walter , Eschenauer Hans A. , Lamancusa John S.
Published: March 2021

The efficiency of using surface-mounted damping layers for noise-reduction of thin-walled (sheet metal) structures, largely depends on their distribution on the component. It is therefore attempted — by using FEM and Mathematical Programming (MP) procedures — to determine optimal layer distributions in such a way that the resonance amplitudes in a frequency interval become minimal. An approximation method based on damped single degree of freedom response functions is used for resonance tracking. Beams, circular plates and shallow spherical shells with unconstrained damping treatment are considered as application examples. It will be shown that an optimal layout of the layers can result in substantial reductions in sound radiation. These reductions result not only from an increase in damping and stiffness but may also be due to a modification of the vibration modeshapes.
A Multilevel Structural Approach to Optimal Earthquake-Resistant Structures
Authors: Thierauf Georg , Portillo-García Edwin
Published: March 2021

A new method for increasing of the ductility of seismic damaged structures is presented. The method combines efficient and well tested mathematical programming techniques with modern dynamic inelastic design concepts (explicit ductility balance). The results of this method are presented for reinforced concrete frames. The design variables are the longitudinal reinforcement and the cross-sectional dimensions at all member ends. A preliminary design is modified sequentially until the balance of ductility has reached a preselected distribution (optimization level II). Before the structural optimization starts, the actual ground motion is replaced by an equivalent one which contains only a few impulses and produces the same structural damage as the original earthquake (optimization level I). Based on this equivalent earthquake, the optimization problem can be solved and even direct methods for the time-integration of the non-linear dynamic equations can be included.
Application of Singular Value Decomposition for Static Equilibrium Analysis
Authors: Lew Jiann-Shiun
Published: March 2021

This paper presents an algorithm to determine the static equilibrium positions of general mechanical systems. The system generalized coordinates used in this paper are Cartesian coordinates. The Singular Value Decomposition (SVD) of the Jacobian matrix of constraints is used to separate the system coordinate space into the constraint space and the tangent space. This tangent space represents the system motion space and the coordinates corresponding to this space are chosen as independent coordinates. The coordinates corresponding to the constraint space are chosen as dependent coordinates. The sufficient and necessary condition for an equilibrium position is that the independent acceleration at this position is zero. This condition is used to develop an algorithm to find equilibrium positions. Examples will be used to demonstrate the algorithm developed in this paper.
Implementation of Decomposition Analysis in Optimal Design
Authors: Wagner Terrance C. , Papalambros Panos Y.
Published: March 2021

Decomposition analysis studies how one may explore systematically the decomposition of a given optimal design problem to a variety of decomposed formats that can be then treated by a specific decomposition method. This article presents the implementation of a decomposition analysis methodology introduced previously. The discussion focuses on the linking properties that can determine candidate partitions of the original problems. Suggestions are offered about how to define acceptable partitions. Examples illustrate the computational implementation of the methodology.
Approximation Concepts for the Decomposition-Based Optimization of Complex Mechanical Structures on Parallel Computers
Authors: Eschenauer Hans A. , Weinert Matthias
Published: March 2021

The present paper introduces a decomposition procedure for the optimization of complex mechanical structures, where the coupling structure of the generated subsystems is assumed to be non-hierarchical. Since the above decomposition procedure is suitable for a parallel solution, it is implemented on a parallel computer. The procedure is applied to the shape optimization of a shell of revolution.
Second Order Based Multidisciplinary Design Optimization Algorithm Development
Authors: Renaud J. E.
Published: March 2021

This paper reviews the effectiveness of a recently developed second order based multidisciplinary design optimization (MDO) algorithm in application to coupled engineering test problems. The second order based procedure significantly reduces the number of system analyses required for optimization as compared to first order based MDO procedures and single level optimization strategies. Based on these successes, this paper introduces a blueprint for an improved second order based MDO algorithm. The new algorithm is designed to provide additional design team compatibility and to exploit parallel computations during system optimization. The new algorithm introduces a modified non-hierarchic decomposition strategy (state space decomposition) that allows individual design teams to access the full design vector during concurrent subspace optimizations. Access to the the design vector in the new algorithm is now based on the local analyses capabilities of individual design teams. The coordination procedure of system approximation in the new algorithm will make use of second order global sensitivities. The new state space decomposition provides for the calculation of these sensitivities in parallel making use of local design data bases.
Closed-Form Primitives for Generating Volume Preserving Deformations
Authors: Chirikjian Gregory S.
Published: March 2021

In this paper, methods for generating closed-form expressions for locally volume preserving deformations of general volumes in three dimensional space are introduced. These methods potentially have applications to computer aided geometric design, the mechanics of materials, and realistic real-time simulation and animation of physical processes. In mechanics, volume preserving deformations are intimately related to the conservation of mass. The importance of this fact manifests itself in design, and in the realistic simulation of many physical systems. Whereas volume preservation is generally written as a constraint on equations of motion in continuum mechanics, this paper develops a set of physically meaningful basic deformations which are intrinsically volume preserving. By repeated application of these primitives, an infinite variety of deformations can be written in closed form.
Branch and Dead Position Problems of N-Bar Linkages
Authors: Ting Kwun-Lon
Published: March 2021

Based on the linkage rotatability theory, this article presents the first systematic and unified criteria to identify the existence of branch and dead positions of single closed-loop N-bar planar and spherical linkages or manipulators. It suggests that for any single-loop planar, spherical or even space linkages, the branch problem is irrelevant to the input conditions while the existence of dead positions depends on the type of kinematic chain and also the selection of the input links or joints. The proposed criteria and their simplicity are not affected by the type of applications nor by the use of coupler links as the input. They are also directly applicable to linkages with prism joints. Although the criteria are intended for computer use, the simplicity of these criteria allows one to develop geometric insight for graphic methods.
Parametric Deformations and Model Optimality in Concurrent Design
Authors: Rao J. R. Jagannatha , Chidambaram Bala
Published: March 2021

Concurrent modeling, as an emerging theme in engineering design research, also offers interesting new challenges in applied optimization. However, it is not always clear how best to construct mathematical models that represent such concurrent decision-making. In this paper, a class of engineering design problems, comprising analysis and synthesis tasks, is shown to be a two-player Stackelberg game with synthesis as the leader and analysis as the follower. Situations arising from a reversal of roles of the two tasks are studied and a Pareto model of a Design versus Analysis game is also investigated. Stackelberg games are then viewed in the larger context of concurrent design with design and manufacturing as two players. The potential benefits of such an approach are illustrated in the concurrent design of a stiffened plate structure.
Fractal Precision Models of Lathe-Type Turning Machines
Authors: Tumer Irem Y. , Srinivasan R. S. , Wood Kristin L. , Busch-Vishniac Ilene
Published: March 2021

The primary objective of this research is to develop surface models of machining processes to simulate machined surface profiles and analyze their structure. In this paper, fractal analysis is used to discover and characterize the variational pattern of turned surfaces. This analysis provides a means of explicitly stating the precision of a machining process. The results are used to further test the validity of the concept of fractal dimensions at tolerance scales and to establish a relation between surface models, experimental surfaces, and fractals. Based on these results, a more complete model of turning is available to designers for choosing process and design parameters and for comparing the precision between competing machining processes.
A Hybrid Shape Optimization Method Based on Implicit Differentiation and Node Removal Techniques
Authors: Shim P. Y. , Mannoochehri S.
Published: March 2021

This paper presents a hybrid shape optimal design methodology using an implicit differentiation approach for sensitivity analysis and a node removal technique for shape alteration. The approach presented attempts to overcome the weaknesses inherent in each individual technique. The basic idea is to combine the sensitivity analysis, which forms the analytical basis for the algorithm, and a node removal technique, which grossly modifies the shape without the need for a remeshing after each iteration. The sensitivity analysis is based on the finite element equilibrium equation and the implicit differentiation technique. It examines the effect positional changes of the boundary nodes have on the stress values. Using the sensitivity results, a sequential linear programming algorithm is utilized to determine optimum positions of the boundary nodes. These optimization results are provided as inputs to an algorithm that decides which boundary nodes should be removed. By removing boundary nodes, the boundary elements change to either a triangular or a non-existent type. This shape modification procedure starts from the boundary elements and moves toward the internal elements. Only two iterations of finite element analysis are required to modify one boundary layer. To maintain the structural integrity and the connectivity of the elements in the model, a connectivity check is performed after each iteration. Three design examples are given to illustrate the accuracy and the steps involved in the proposed optimal design methodology.
Information Management Support for Integrated Design Environments
Authors: Majumder Deeptendu , Rangan Ravi M. , Fulton Robert E.
Published: March 2021

This paper identifies key requirements for an advanced engineering design information management system. With the advent of information management technology and design automation, the definition of Computer Aided Design (CAD) systems has evolved beyond the realm of geometric data to include support for a very wide range of activities of an intelligent design agent — such as definition, manipulation and analyses of complex information models of a product. These information models represent not only conventional product data associated with typical CAD applications (FEM, NC, Geometric models, etc.), but also design information characterizing correlations between the requirements, function, behavior and form dimensions of the design. The new generation of CAD systems are expected to provide the designer with capabilities for defining, manipulating and reasoning with such models. These new functionalities are important to individual designers, as well as organizations as the need to manage information as a corporate asset is becoming a a critical facet of corporate strategies.

This paper explores these needs using design scenarios that trace the conceptual phases of design as well as the organization relevance to the design process. The first scenario deals with the innovative design of drilling applications for lunar environments, while the second scenario deals with the routine design of computer peripherals in a collaborative, multidisciplinary environment. These scenarios are used to elicit high level requirements, and subsequently the development of prototype systems. Preliminary results from the prototypes are presented herein.
Product Models in Simultaneous Engineering
Authors: Tegel Oliver
Published: March 2021

Simultaneous Engineering more and more becomes an important management instrument to shorten product development cycles. In addition, the tense cooperation between employees working in different departments or even different companies results in important synergy-effects.

To enable Simultaneous Engineering an infrastructure has to be build up far the handling of product data. Communication between the staff as well as communication between the CAX-Systems have to be managed efficiently, too. Product models adapted to the companies needs can push the efficiency of product development a step forward.
Designing the Future DDG 51 Class Computer Aided Design
Authors: Ouillette Joanne J.
Published: March 2021

The DDG 51 Class of AEGIS guided missile destroyers is the Navy’s premier surface combatant. Named for famed World War II hero. Admiral Arleigh Burke, these ships represent state-of-the-art technology. This 504 foot, 8,300 ton destroyer has been designed with improved seakeeping and survivability characteristics and carries the sophisticated AEGIS Weapon System. Derived from the Greek word meaning “shield”, AEGIS ships are the “shield of the fleet”. The Navy has commissioned the first two ships of the class. They have performed beyond expectation in rigorous at-sea trials designed to fully test combat capability.

The DDG 51 Class ships are replacing retiring fleet assets. In a decreasing Department of Defense (DoD) budget environment, however, acquisition costs must be reduced to continue to build capable warships. The Navy’s Destroyer Program Office is pursuing the implementation of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) technology to reduce costs without reducing ship’s capability.

Under Navy direction, the ship construction yards, Bath Iron Works and Ingalls Shipbuilding, are aggressively pursuing the transition to CAD-based design, construction, and life cycle support This effort also involves General Electric, the Combat System Engineering Agent. Building a three dimensional (3D) computer model of the ship prior to construction will facilitate the identification and resolution of interferences and interface problems that would otherwise go undetected until actual ship construction. This 3D database contains geometry and design data to support system design. Accurate construction drawings, fabrication sketches, and Numerical Control (NC) data can be extracted directly from the database to support construction at each shipyard. At completion of construction, a model representing the “as built” configuration will be provided as a lifetime support tool for each ship’s projected 40 year life.

The transition to CAD-based design and construction has applied fundamental concepts of the DoD’s Computer Aided Acquisition and Logistic Support (CALS) initiative. In addition to creating a 3D database representing ship design, the shipyards have developed a neutral file translator to exchange this data between Computervision and Calma CAD systems in operation at Bath Iron Works and Ingalls Shipbuilding respectively. This object oriented transfer capability ensures data is shared rather than duplicated. The CALS concepts of concurrent engineering and computer aided engineering analysis are being applied to design an upgrade to the ship that features the addition of a helicopter hanger. The CAD models are used as an electronic baseline from which to assess proposed modifications. Optimizing the design before the first piece of steel is cut will reduce construction costs and improve the quality of the ship.
A Logic-Based Mechanical System Constraint Model
Authors: Wu J. K. , Wang J. H. , Feng C. X. , Liu T. H.
Published: March 2021

This paper presents some initial developments in modeling design constraints of mechanical systems using predicate logic. This design constraint modeling method is to manage design changes in a concurrent engineering environment that has CAE and CAM applications. The design constraints are classified according to an object hierarchy of a mechanical system information model which has five levels object including: a mechanical system level, assembly level, and part level. The constraint relationships are defined and formally expressed using predicate logic. Feature fitting and against relationships between parts in the assembly level and relationships between features of a part in the part level have been illustrated in the paper.
Modeling Enterprise Information and Enabling Access Using Information Sharing Server
Authors: Karinathi R. , Jagannathan V. , Montan V. , Petro J. , Sobolewski M. , Raman R. , Trapp G. , Deng Stephen , Almasi G. , Li Xi
Published: March 2021

The engineering data of a large enterprise is typically distributed over a wide area and archived in a variety of databases and file systems. Access to such information is crucial to a team member, particularly in a concurrent engineering setting. However, this is not easy, because (1) a model of the relevant information is not available, and (2) there is no simple way to access the information without being knowledgeable about various computer data formats, file systems, and networks. However, in a concurrent engineering environment, there is every need to be aware of the perspectives of the other members of the team. We have developed a system called the Information Sharing Server (ISS) to enable access to diverse and distributed information within a corporation. Such data could be stored in different repositories such as databases (relational, object oriented, etc.) and file systems including those that contain multiple media (text, graphics, audio, etc.). The ISS maintains an enterprise model that is visible to the user. The modeling of the enterprise is done in a language called EXPRESS developed by the STEP consortium as an international standard. The ISS also stores mappings from the model to the actual data residing in the repositories. The ISS accepts requests from the user and converts them into requests specific to a repository. The request is then communicated to the repository over the network and the results are fetched back to the user. The ISS is currently integrated with engineering data of two domains: electrical and mechanical. Our paper describes the methodology of the ISS, the details of the implementation and extensions planned for the future. We believe the transparency offered by the ISS will make it a very useful tool for an engineer and make it very convenient to integrate heterogeneous legacy databases.
Integration of Knowledge-Based Systems and Heterogeneous Databases in Design Information Systems
Authors: Yang Yong , Sims Williams Jon H. , McMahon Chris A. , Pitt David J.
Published: March 2021

The process of design depends on the availability of both a variety of data and many different types of knowledge drawn from specialists. Most of the data is naturally stored in various databases while the knowledge can often be organised in Knowledge-based Systems (KBSs). A design support system is thus required to comprise a number of elements such as databases and knowledge-based systems, as well as conventional analytical modelling systems. In common with many software environments that have been developed over several years these elements tend to form autonomous islands based on perhaps different computers or data servers between which exchange of data is difficult. Even in the more recent expert system field, communication is limited between different advisory programs, or between such programs and the databases which they use for inference. One central issue in designing such a support system is to identify means by which multiple systems can co-operate in an inter-connected environment and share data which is distributed over heterogeneous databases. This paper describes an Interprocess Communication (IPC) based integration framework which is designed to facilitate dynamic and smooth data communication between the cooperating KBSs and databases within a design support system.
Investigating age, hearing loss, and background noise effects on speaker-targeted head and eye movements in three-way conversations
Authors: Lu Hao , McKinney Martin F. , Zhang Tao , Oxenham Andrew J.
Published: March 2021

Although beamforming algorithms for hearing aids can enhance performance, the wearer's head may not always face the target talker, potentially limiting real-world benefits. This study aimed to determine the extent to which eye tracking improves the accuracy of locating the current talker in three-way conversations and to test the hypothesis that eye movements become more likely to track the target talker with increasing background noise levels, particularly in older and/or hearing-impaired listeners. Conversations between a participant and two confederates were held around a small table in quiet and with background noise levels of 50, 60, and 70 dB sound pressure level, while the participant's eye and head movements were recorded. Ten young normal-hearing listeners were tested, along with ten older normal-hearing listeners and eight hearing-impaired listeners. Head movements generally undershot the talker's position by 10°–15°, but head and eye movements together predicted the talker's position well. Contrary to our original hypothesis, no major differences in listening behavior were observed between the groups or between noise levels, although the hearing-impaired listeners tended to spend less time looking at the current talker than the other groups, especially at the highest noise level.
Parity-Time symmetric system based on the thermoacoustic effect
Authors: Poignand Gaelle , Olivier Come , Penelet Guillaume
Published: March 2021

This paper deals with the experimental study of an acoustic Parity-Time (PT) symmetric system based on the thermoacoustic amplification process. Such a system is presented and consists of two acoustic units connected through side branches to a waveguide. One unit contains a thermoacoustic core that provides an acoustic gain which balances the thermal and viscous losses taking place in the second unit. Two control parameters are set to adjust the impedance of the two units and thereby achieve the PT-symmetry condition. The results show that a good balance between gain and loss is achieved within a frequency range from 45 Hz to 60 Hz. The spontaneous PT-symmetry breaking and the existence of exceptional points, which are characteristic of the behavior of PT-symmetric systems, are explored in this frequency range. Moreover, the distance between the two units is shown to be a control parameter to slightly shift the frequency at which the exceptional points occur.
Explainable machine learning determines effects on the sound absorption coefficient measured in the impedance tube
Authors: Stender Merten , Adams Christian , Wedler Mathies , Grebel Antje , Hoffmann Nobert
Published: March 2021

Measurements of acoustic properties of sound absorbing materials in impedance tubes show poor reproducibility, which was demonstrated in round robin tests. The impedance tube measurements are standardized but lack precise definitions of the actual measurement setup, specimen preparation, and other factors that introduce uncertainty in practice. In this paper, machine learning models identify those factors that mostly affect the sound absorption coefficient from a large data set of more than 3000 absorption spectra measured in one impedance tube. The specimens are manufactured from one polyurethane foam, and different cutting technologies, different operators, different specimen diameters, different specimen thicknesses, and two different approaches to mount the specimens in the impedance tube are considered. Explainable machine learning techniques allow the identification and quantification of the most influential factors and, furthermore, the frequency ranges that are the most affected by the choice of these setup factors. The results indicate that besides the specimen thickness, also the operator affects the absorption coefficient by a directional and non-random relationship. Hence, it needs to be controlled carefully. The method proves to be a promising pathway for knowledge discovery from acoustic measurement data using explainability approaches for machine learning models.
Acoustical modeling of the saxophone mouthpiece as a transfer matrix
Authors: Wang Song , Maestre Esteban , Scavone Gary
Published: March 2021

This paper proposes an acoustic model of the saxophone mouthpiece as a transfer matrix (TM). The acoustical influence of the mouthpiece is investigated, and the TM mouthpiece model is compared to previously reported mouthpiece representations, including cylindrical and lumped models. A finite element mouthpiece model is first developed, from which the TM model is derived, and both models are validated by input impedance measurements. The comparison of acoustic properties among different mouthpiece models shows that the TM mouthpiece is more accurate than the other two models, especially in preserving the high-frequency acoustic characteristics. The TM model also produces the best overall tuning of the first several impedance peaks when coupled to a measured saxophone impedance. The internal and radiated sound pressure are synthesized for an alto saxophone connected to different mouthpiece models by jointly modeling the input impedance and the radiation transfer function using recursive parallel filters. Differences are found among mouthpiece models in terms of oscillation thresholds, playing frequencies, spectral centroids, pressure waveforms, and bifurcation delays, which can be partially explained by differences in the tuning and high-frequency characteristics.
Les activités physiques et sportives dans les institutions juives françaises durant l’Entre-deux-guerres (1918–1939) : un éclectisme de pratiques et d’objectifs
Authors: Pénard Etienne , Gomet Doriane , Attali Michaël
Published: March 2021

Jusqu’aux années vingt, les Juifs de France restent hermétiques à la dynamique de développement des activités sportives dans la société française. Mais, confrontées à des vagues successives d’immigration et à une montée progressive de l’antisémitisme, les communautés juives développent dans l’entre-deux-guerres un ensemble de réseaux et d’organisations favorables au développement des activités corporelles. Le sport devient alors un outil au service de ces organisations juives, qui l’utilisent selon des modalités et objectifs parfois très différents. Ne partageant pas exactement les mêmes visions de l’individu à former ni les mêmes objectifs, elles ne parviennent pas à s’associer pour se constituer en une institution sportive juive commune, influente, structurante et stable dans l’hexagone. L’étude du développement du sport communautaire juif est finalement pertinente pour mettre en évidence les multiples fonctions et valeurs attribuées aux activités corporelles, elles-mêmes dépendantes des volontés, aspirations et débats politiques des communautés.
Smart cities built with smart materials
Authors: Napolitano Rebecca , Reinhart Wesley , Gevaudan Juan Pablo
Published: March 2021

Sensors and actuators that respond locally avoid overburdening data analysis networks
Tandem catalysis at nanoscale
Authors: Pei Chunlei , Gong Jinlong
Published: March 2021

Porous overcoatings help mediate coupled reactions
COVID-19 vaccination passports
Authors: Dye Christopher , Mills Melinda C.
Published: March 2021

As countries grow eager to reignite their economies and people increasingly yearn for mobility and normalcy in life, pressure is mounting for some form of COVID-19 health status certificate that would support these desires. There has already been an explosion of COVID-19 passport initiatives for domestic use and international travel. But scientific, legal, and ethical concerns abound with such documentation. Given the high stakes, what is the path forward?
Production of
l
-Theanine by Escherichia coli in the Absence of Supplemental Ethylamine
Authors: Hagihara Ryota , Ohno Shoto , Hayashi Mikiro , Tabata Kazuhiko , Endo Hirofumi
Published: March 2021

l
-Theanine is widely used in food additives and dietary supplements. Industrial production of
l
-theanine uses the toxic and highly flammable precursor ethylamine, raising production costs. In this study, we used
Escherichia coli
to engineer two biosynthetic pathways that produce
l
-theanine from glucose and ammonia in the absence of supplemental ethylamine. This study establishes a foundation for safely and economically producing
l
-theanine.
Functional Analysis of Phenazine Biosynthesis Genes in
Burkholderia
spp.
Authors: Hendry Samuel , Steinke Stephan , Wittstein Kathrin , Stadler Marc , Harmrolfs Kirsten , Adewunmi Yetunde , Sahukhal Gyan , Elasri Mohamed , Thomashow Linda , Weller David , Mavrodi Olga , Blankenfeldt Wulf , Mavrodi Dmitri
Published: March 2021

Although the production of phenazines in
Burkholderia
was first reported almost 70 years ago, the role these metabolites play in the biology of these economically important microorganisms remains poorly understood. Our results revealed that the phenazine biosynthetic pathway in
Burkholderia
has a complex evolutionary history, which likely involved horizontal gene transfers among several distantly related groups of organisms.
Ancient Antibiotics, Ancient Resistance
Authors: Waglechner Nicholas , Culp Elizabeth J. , Wright Gerard D.
Published: March 2021

As the spread of antibiotic resistance threatens our ability to treat infections, avoiding the return of a preantibiotic era requires the discovery of new drugs. While therapeutic use of antibiotics followed by the inevitable selection of resistance is a modern phenomenon, these molecules and the genetic determinants of resistance were in use by environmental microbes long before humans discovered them.
Membrane Topology of Pestiviral Nonstructural Protein 2 and Determination of the Minimal Autoprotease Domain
Authors: Walther T. , Fellenberg J. , Klemens O. , Isken O. , Tautz N.
Published: March 2021

Pestiviral NS2 is central to the regulation of RNA replication and virion morphogenesis via its autoprotease activity. This activity is temporally regulated by the cellular chaperone DNAJC14 as a cofactor: while free NS3 is required for RNA replication as a component of the viral replicase, only uncleaved NS2-3 supports virion morphogenesis.
Rare cause of paraparesis in a young man: cervico-dorsal neurenteric cysts associated with Klippel-Feil syndrome
Authors: Seth Raghav , Sinha Anindita , Singla Navneet , Chatterjee Debajyoti
Published: March 2021

Klippel-Feil syndrome is an entity presenting with short neck, low hairline and reduced range of motion of cervical spine. Neurenteric cyst is a congenital abnormality, in which mucus-secreting epithelium of the gastrointestinal tract is seen in the spinal axis. The association of a neurenteric cyst with Klippel-Feil syndrome has been reported very rarely. We report the case of a young man, affected by Klippel-Feil syndrome, who presented with bilateral paraplegia. Imaging of the spine revealed features suggestive of cervico-dorsal neurenteric cyst. Subsequently, surgical resection of the cysts was done, which resulted in resolution of the symptoms.
Diffuse encephalitic toxoplasmosis in HIV
Authors: Pearce Jasmine , Sheridan Ray , Shaw Johnathan , Senior Thomas
Published: March 2021

This case demonstrates an atypical radiological presentation of cerebral toxoplasmosis in a 62-year-old HIV-positive patient. The diagnosis is discussed alongside MRI imaging, laboratory results and treatment. Central nervous system toxoplasmosis is typically associated with ring enhancing lesions on neuroimaging with contrast, but the radiology for this patient shows diffuse white matter changes and ependymal enhancement, which would normally suggest an alternative diagnosis.
Recurrent vaginal cuff dehiscence after surgery for endometriosis: a technique for laparoscopic repair with an omental flap
Authors: Frank Gerard-Peter , Rhemrev Johann , Westerterp Marinke , English Jim
Published: March 2021

Vaginal evisceration is a rare but severe complication after hysterectomy or colpotomy and is generally successfully repaired by reapproximating healthy tissue edges of the vagina. Recurrent vaginal cuff dehiscence is problematic especially in sexually active women. We describe two cases of recurrent vaginal cuff dehiscence. The first patient had a hysterectomy for endometriosis. The second patient underwent laparoscopic excision of an endometriotic nodule at the vaginal vault. The vaginal cuff dehiscence was repaired by a laparoscopic approach employing an omental flap to enhance tissue healing. This closure technique turned out to be successful at follow-up in both cases. In case of recurrent vaginal cuff dehiscence, management options are limited. Our case report offers a laparoscopic treatment option by using an omental flap. This procedure can be used when conventional repair fails.
Delayed migration of soft tissue fillers in the periocular area masquerading as eyelid and orbital pathology
Authors: Lin Zhiheng , Dean Andrew , Rene Cornelius
Published: March 2021

Soft tissue fillers used for facial rejuvenation can cause complications. We present two cases of late migration of injected fillers mimicking other pathology in the periocular area. Case 1 is a 52-year-old woman referred with chronic bilateral upper lid swelling, mimicking blepharochalasis syndrome, 51/2years after undergoing injection of hyaluronic acid filler in both brows. Extensive blood investigations were normal. Bilateral, sequential upper lid biopsy revealed migrated hyaluronic acid filler, which was successfully treated with hyaluronidase. Case 2 is a 62-year-old woman who presented with a right lower lid mass 8 years after undergoing injection of polyalkylimide gel into both cheeks. CT scanning confirmed an intermediate density soft tissue mass overlying the inferior orbital rim. Histology from surgical excision reported chronic granulomatous inflammation due to migrated polyalkylimide gel. An awareness of late migration of fillers causing eyelid swelling and masses in the periocular area will prevent unnecessary investigations and facilitate prompt management.
Glaucoma diagnostic capabilities of macular vessel density on optical coherence tomography angiography: superficial versus deep layers
Authors: Lee Jin Yeong , Shin Joong Won , Song Min Kyung , Hong Ji Wook , Kook Michael S
Published: March 2021

Background/aims

To compare glaucoma diagnostic capabilities of superficial and deep macular vessel density (mVD) parameters in a series of healthy and open-angle glaucoma (OAG) eyes with central visual field (CVF) loss.

Methods

We consecutively enrolled 113 eyes of 113 patients with OAG and 47 eyes of 47 healthy participants in a retrospective manner. Superficial and deep mVDs were measured at foveal, parafoveal and perifoveal locations on optical coherence tomography (OCT) angiography. The macular ganglion cell-inner plexiform layer thickness (mGCIPLT) was measured on OCT as a reference standard. Glaucoma diagnostic capabilities of superficial and deep mVD parameters were assessed according to the glaucoma stage. Factors associated with the CVF mean sensitivity (MS) were evaluated using linear regression analyses in the OAG eyes.

Results

Glaucoma diagnostic capabilities of superficial perifoveal and parafoveal mVDs were significantly better than those of deep perifoveal and parafoveal mVDs, regardless of the glaucoma stage (both p<0.05). Both mGCIPLT and superficial parafoveal mVD were significantly associated with CVF MS (β-coefficients=10.567 and 21.147, respectively, both p<0.05), independent of age and glaucoma severity.

Conclusion

Superficial mVD parameters showed significantly greater glaucoma diagnostic capabilities and better correlation with CVF MS compared with deep mVD parameters.
Universal newborn hearing screening in South Africa: a single-centre study
Authors: Gina Ayanda , Bednarczuk Nadja F , Jayawardena Asitha , Rea Peter , Arshad Qadeer , Saman Yougan
Published: March 2021

Hearing screening for newborn babies is an established protocol in many high-income countries. Implementing such screening has yielded significant socioeconomic advantages at both an individual and societal level. This has yet to permeate low/middle-income countries (LMIC). Here, we illustrate how newborn hearing screening needs to be contextually adapted for effective utilisation and implementation in an LMIC. Specifically, this advocates the use of auditory brainstem testing as the first-line approach. We propose that such adaptation serves to maximise clinical efficacy and community participation at a reduced cost.
Economic burden of asthma in Singapore
Authors: Finkelstein Eric A , Lau Eden , Doble Brett , Ong Bennett , Koh Mariko Siyue
Published: March 2021

Background and objective

Up-to-date economic burden of asthma in Singapore is currently unknown.

Methods

We quantify the per capita and total annual costs of asthma for adults and children by level of symptom control (uncontrolled, partly controlled, and well controlled) via a cross-sectional online survey administered to a national web panel. Participants were asked about healthcare utilisation, days missed from work, and reduced productivity due to their symptoms. These values were then monetised and multiplied by prevalence estimates of adult and child asthmatics to generate total costs.

Results

A total of 300 adults and 221 parents of children with asthma were included in analysis. The total annual cost of adult asthma was estimated to be SGD 1.74 billion (US$1.25 billion) with 42% coming from the uncontrolled group, 45% from the partly controlled group, and 13% from the well-controlled group. For children, the total cost is SGD 0.35 billion (US$0.25 billion), with 64%, 26% and 10% coming from each group respectively. Combined, the annual economic burden of asthma in Singapore is SGD 2.09 billion (US$1.50 billion) with 79% due to productivity losses.

Conclusion

Poorly controlled asthma imposes a significant economic burden. Therefore, better control of disease has the potential to generate not only health improvements, but also medical expenditure savings and productivity gains.
Disentangling molecular and clinical stratification patterns in beta-galactosidase deficiency
Authors: Tebani Abdellah , Sudrié-Arnaud Bénédicte , Dabaj Ivana , Torre Stéphanie , Domitille Laur , Snanoudj Sarah , Heron Benedicte , Levade Thierry , Caillaud Catherine , Vergnaud Sabrina , Saugier-Veber Pascale , Coutant Sophie , Dranguet Hélène , Froissart Roseline , Al Khouri Majed , Alembik Yves , Baruteau Julien , Arnoux Jean-Baptiste , Brassier Anais , Brehin Anne-Claire , Busa Tiffany , Cano Aline , Chabrol Brigitte , Coubes Christine , Desguerre Isabelle , Doco-Fenzy Martine , Drenou Bernard , Elcioglu Nursel H , Elsayed Solaf , Fouilhoux Alain , Poirsier Céline , Goldenberg Alice , Jouvencel Philippe , Kuster Alice , Labarthe François , Lazaro Leila , Pichard Samia , Rivera Serge , Roche Sandrine , Roggerone Stéphanie , Roubertie Agathe , Sigaudy Sabine , Spodenkiewicz Marta , Tardieu Marine , Vanhulle Catherine , Marret Stéphane , Bekri Soumeya
Published: March 2021

Introduction

This study aims to define the phenotypic and molecular spectrum of the two clinical forms of β-galactosidase (β-GAL) deficiency, GM1-gangliosidosis and mucopolysaccharidosis IVB (Morquio disease type B, MPSIVB).

Methods

Clinical and genetic data of 52 probands, 47 patients with GM1-gangliosidosis and 5 patients with MPSIVB were analysed.

Results

The clinical presentations in patients with GM1-gangliosidosis are consistent with a phenotypic continuum ranging from a severe antenatal form with hydrops fetalis to an adult form with an extrapyramidal syndrome. Molecular studies evidenced 47 variants located throughout the sequence of the GLB1 gene, in all exons except 7, 11 and 12. Eighteen novel variants (15 substitutions and 3 deletions) were identified. Several variants were linked specifically to early-onset GM1-gangliosidosis, late-onset GM1-gangliosidosis or MPSIVB phenotypes. This integrative molecular and clinical stratification suggests a variant-driven patient assignment to a given clinical and severity group.

Conclusion

This study reports one of the largest series of b-GAL deficiency with an integrative patient stratification combining molecular and clinical features. This work contributes to expand the community knowledge regarding the molecular and clinical landscapes of b-GAL deficiency for a better patient management.
Energetic state and the continuum of migratory tactics in brown trout (Salmo trutta)
Authors: Birnie-Gauvin Kim , Larsen Martin H. , Aarestrup Kim
Published: March 2021

Alternative migratory tactics, like partial migration, are common in many taxa. The proximate and ultimate drivers underpinning these strategies are unclear, though factors like condition and energetic status have been posited as important predictors. We sampled and PIT-tagged 1882 wild brown trout (Salmo trutta) prior to the first so-called decision window and explored the links between migratory tactics (residency, autumn or spring migration) and body metrics (length and condition), lipids (triglycerides and cholesterol), and sex in 150 randomly selected individuals. We found that more females adopted the autumn and spring migration tactic than males, while more males adopted the residency tactic than females, likely reflecting sex-biased benefits in anadromy. We also found that autumn migrants were in poorer condition prior to the presumed first decision window than spring migrants and residents. Lastly, we found that both condition and cholesterol were positively correlated to the timing of migration, such that individuals in poorer condition and (or) with lower cholesterol migrated earlier. Collectively, these results suggest that energy depletion is an important factor in determining migratory strategy, including timing.
Process-based models for nitrogen dynamics in subsurface flow constructed wetlands: A state-of-the-art review
Authors: Tan Yee Yong , Tang Fu Ee , Saptoro Agus
Published: March 2021

In the last two decades, several process-based models had been developed to describe the transport and fate of contaminants in subsurface flow constructed wetlands (SSF CWs) under a variety of conditions. These models have become valuable tools to better design, control, and optimize the SSF CW system. Moreover, they can aid investigations on the effects of variables of interest on the system. While excellent review papers on these models have been published, the ability of the existing process-based models to simulate the nitrogen transformations in the SSF CWs have not been highlighted. Consequently, a critical review of the simulation of nitrogen transformation processes is desirable. This paper presents an overview of the available models that are capable of modelling the nitrogen dynamics in the SSF CWs. The existing process-based models can be mainly categorized as process-dedicated models and Gujer matrix models. A process-dedicated model is a feasible tool for design purposes. Meanwhile, the Gujer matrix model delivers valuable insights into scientific studies. In this paper, the existing models are summarized and critically discussed with regards to their capability and practicality in simulating the nitrogen dynamics in SSF CWs. Organic nitrogen, ammonium, and nitrate are the common nitrogen compounds considered in the process-based models of SSF CWs. Meanwhile, nitrite was frequently considered together with nitrate, owing to its low concentration in the effluent of SSF CWs. By comparison, ammonification, nitrification, denitrification, plant uptake, and ammonium adsorption are the typical nitrogen transformation and degradation processes found in the existing models, whereas ammonia volatilization processes are rarely found in the literature. Oxygen and organic matter are the major limiting reactants of nitrogen transformation and degradation processes in the modelling, and other factors such as microbial population, temperature, and pH are also considered. The recommendations and future research directions on the influence of microorganism distribution, resting period, oxygen release, ammonium adsorption, and plants are outlined.