Simple Overload Research Articles

Vanadium Redox Flow Battery Stack Balancing to Increase Depth of Discharge Using Forced Flow Attenuation

Vanadium redox flow batteries are gaining great popularity in the world due to their long service life, simple (from a technological point of view) capacity increase and overload resistance, which hardly affects the service life. However, these batteries have technical problems, namely in balancing stacks with each other in terms of volumetric flow rate of electrolyte. Stack power depends on the speed of the electrolyte flow through the stack. Stacks are connected in parallel by electrolytes to increase battery power. If one of the stacks has a lower hydrodynamic resistance, the volume of electrolytes passing through it increases, which leads to a decrease in the efficiency of the remaining stacks in the system. This experimental study was conducted on a 10 kW uninterruptible power supply system based on two 5 kW stacks of all-vanadium redox flow batteries. It was demonstrated that forced flow attenuation in a circuit with low hydrodynamic resistance leads to an overall improvement in the system operation.

O-ring-induced transverse aortic constriction (OTAC) is a new simple method to develop cardiac hypertrophy and heart failure in mice

Suture-based transverse aortic constriction (TAC) in mice is one of the most frequently used experimental models for cardiac pressure overload-induced heart failure. However, the incidence of heart failure in the conventional TAC depends on the operator’s skill. To optimize and simplify this method, we proposed O-ring-induced transverse aortic constriction (OTAC) in mice. C57BL/6J mice were subjected to OTAC, in which an o-ring was applied to the transverse aorta (between the brachiocephalic artery and the left common carotid artery) and tied with a triple knot. We used different inner diameters of o-rings were 0.50 and 0.45 mm. Pressure overload by OTAC promoted left ventricular (LV) hypertrophy. OTAC also increased lung weight, indicating severe pulmonary congestion. Echocardiographic findings revealed that both OTAC groups developed LV hypertrophy within one week after the procedure and gradually reduced LV fractional shortening. In addition, significant elevations in gene expression related to heart failure, LV hypertrophy, and LV fibrosis were observed in the LV of OTAC mice. We demonstrated the OTAC method, which is a simple and effective cardiac pressure overload method in mice. This method will efficiently help us understand heart failure (HF) mechanisms with reduced LV ejection fraction (HFrEF) and cardiac hypertrophy.

A history of the Groovy programming language

This paper describes the history of the Groovy programming language. At the time of Groovy’s inception, Java was a dominant programming language with a wealth of useful libraries. Despite this, it was perceived by some to be evolving slowing and to have shortcomings for scripting, rapid prototyping and when trying to write minimalistic code. Other languages seemed to be innovating faster than Java and, while overcoming some of Java’s shortcomings, used syntax that was less familiar to Java developers. Integration with Java libraries was also non-optimal. Groovy was created as a complementary language to Java—its dynamic counterpart. It would look and feel like Java but focus on extensibility and rapid innovation. Groovy would borrow ideas from dynamic languages like Ruby, Python and Smalltalk where needed to provide compelling JVM solutions for some of Java’s shortcomings. Groovy supported innovation through its runtime and compile-time metaprogramming capabilities. It supported simple operator overloading, had a flexible grammar and was extensible. These characteristics made it suitable for growing the language to have new commands (verbs) and properties (nouns) specific to a particular domain, a so called Domain Specific Language (DSL). While still intrinsically linked with Java, over time Groovy has evolved from a niche dynamic scripting language into a compelling mainstream language. After many years as a principally dynamically-typed language, a static nature was added to Groovy. Code could be statically type checked or when dynamic features weren’t needed, they could be turned off entirely for Java-like performance. A number of nuances to the static nature came about to support the style of coding used by Groovy developers. Many choices made by Groovy in its design, later appeared in other languages (Swift, C#, Kotlin, Ceylon, PHP, Ruby, Coffeescript, Scala, Frege, TypeScript and Java itself). This includes Groovy’s dangling closure, Groovy builders, null-safe navigation, the Elvis operator, ranges, the spaceship operator, and flow typing. For most languages, we don’t know to what extent Groovy played a part in their choices. We do know that Kotlin took inspiration from Groovy’s dangling closures, builder concept, default it parameter for closures, templates and interpolated strings, null-safe navigation and the Elvis operator. The leadership, governance and sponsorship arrangements of Groovy have evolved over time, but Groovy has always been a successful highly collaborative open source project driven more by the needs of the community than by a vision of a particular company or person.

Simulation of the delay effect after applying a simple overload on alloys of aluminum 2024T351 using the Willemborg model

The structures in service are subjected to loads whose amplitude varies most often over time. These differences in loading cycle levels will have a direct impact on the propagation of cracks that can lead to accelerations or slowdowns in the propagation speed of these cracks. Indeed, the delay of the propagation of a crack produced by the application of a simple overload depends on several parameters, such as the material, the loading, the geometry of the specimen and the environment. In this paper, we will try to master more light only on the influence of the loading parameters such as the load ratio, the overload rate on crack propagation, the propagation speed, the number of delay cycle, using the AFGROW calculation code and the willenbourg model, which describes the delay after applying overloads.

Volume incompliance and transfusion are essential for transfusion-associated circulatory overload: a novel animal model.

BACKGROUNDTransfusion‐associated circulatory overload (TACO) is the predominant complication of transfusion resulting in death. The pathophysiology is poorly understood, but inability to manage volume is associated with TACO, and observational data suggest it is different from simple cardiac overload due to fluids. We developed a two‐hit TACO animal model to assess the role of volume incompliance (“first‐hit”) and studied whether volume overload (“second‐hit”) by red blood cell (RBC) transfusion is different compared to fluids (Ringer's lactate [RL]).MATERIALS AND METHODSMale adult Lewis rats were stratified into a control group (no intervention) or a first hit: either myocardial infarction (MI) or acute kidney injury (AKI). Animals were randomized to a second hit of either RBC transfusion or an equal volume of RL. A clinically relevant difference was defined as an increase in left ventricular end‐diastolic pressure (ΔLVEDP) of +4.0 mm Hg between the RBC and RL groups.RESULTSIn control animals (without first hit) LVEDP was not different between infusion groups (Δ + 1.6 mm Hg). LVEDP increased significantly more after RBCs compared to RL in animals with MI (Δ7.4 mm Hg) and AKI (Δ + 5.4 mm Hg), respectively. Volume‐incompliant rats matched clinical TACO criteria in 92% of transfused versus 25% of RL‐infused animals, with a greater increase in heart rate and significantly higher blood pressure.CONCLUSIONTo our knowledge, this is the first animal model for TACO, showing that a combination of volume incompliance and transfusion is essential for development of circulatory overload. This model allows for further testing of mechanistic factors as well as therapeutic approaches.

Bidirectional Crosstalk between Kidney and Lung

Data reported recently suggest that acute kidney injury (AKI) is a systemic disease that adversely affects the function of other organs—including the heart, lung, liver, brain and immune system—which is related to the high mortality rate of affected patients. Kidney and lung function are closely related in both health and disease. Data support deleterious bidirectional crosstalk between the lung and kidney. AKI is a common complication in patients with acute respiratory distress syndrome, and has been reported to exert adverse effects on the lungs. Mortality rates for AKI combined with acute lung injury (ALI) can be up to 80% in critically ill patients. Although AKI-associated ALI presents clinically as increased pulmonary edema, the mechanism of AKI-associated ALI extends beyond simple volume overload. Data from animal studies suggest that AKI-induced pulmonary edema is related to both cardiogenic edema (due to elevated hydrostatic pressure) and non-cardiogenic edema (due to pulmonary endothelial and epithelial cell injury caused by inflammation, oxidative stress, and apoptosis). ALI with mechanical ventilation causes a decline in renal hemodynamic function and apoptosis. Elucidation of the mechanisms of kidney–lung crosstalk would facilitate development of effective therapies and reduce the mortality rate of AKI combined with respiratory failure. Keywords: Acute kidney injury; Respiratory distress syndrome, Adult; Acute lung injury 중심 단어: 급성 ì‹ ë¶€ì „; 급성 호흡곤란증후군; 급성 폐 손상

Peri-Implantitis and Biofilm: Inescapable Bio-Linkage

Dental Implants have changed the face of dentistry over the last three decades. Dental implants have become increasingly common for the management of tooth loss. In the late 1970’s, a Swedish orthopedist named Per-Ingvar Branemark introduced what he termed osseointegrated implants to dental practice [1]. A dental implant is a titanium screw which is placed into bone to replace missing teeth. The implant mimics the root of a tooth in function. It is not only biocompatible, but actually fuses to bone by osseointegration. The growth of osseointegrated implants symbolizes one of the most significant breakthroughs in current dental practice in the oral rehabilitation of partially or fully edentulous patients [2]. As with most treatment procedures in dentistry today, dental implants not only involve scientific discovery, research and understanding, but also application in clinical practice. Dental plaque represents a classic example of both a biofilm and a microbial community, in that it displays emergent properties, i.e., plaque displays properties that are more than the sum of its constituent members [3], and microbial communities are ubiquitous in nature and usually exist attached to a surface as a spatially organized biofilm. Pathogens of the subgingival microbiota can interact with host tissues even without direct tissue penetration, and the subgingival microbiota accumulate on the oral cavity to form an adherent layer of plaque with the characteristics of a biofilm. Dental biofilm forms via an ordered sequence of events, resulting in structured and functionally organized species rich microbial community and modern molecular biological techniques have identified about 1000 different bacterial species in the dental biofilm, twice as many as can be cultured. Peri-implantitis is a sitespecific infectious disease that causes an inflammatory process in soft tissues, and bone loss around an osseointegrated implant in function. The aetiology of the implant infection is conditioned by the status of the tissue surrounding the implant, implant design, degree of roughness, external morphology, and excessive mechanical load. The microorganisms most commonly associated with implant failure are spirochetes and mobile forms of Gram-negative anaerobes, unless the origin is the result of simple mechanical overload. Diagnosis is based on changes of color in the gingiva, bleeding and probing depth of periimplant pockets, suppuration, X-ray, and gradual loss of bone height around the tooth. Treatment will differ depending upon whether it is a case of peri-implant mucositis or peri-implantitis. The management of implant infection should be focused on the control of infection, the detoxification of the implant surface, and regeneration of the alveolar bone [4].

Management of peri-implantitis

Peri-implantitis is a site-specific infectious disease that causes an inflammatory process in soft tissues, and bone loss around an osseointegrated implant in function. The etiology of the implant infection is conditioned by the status of the tissue surrounding the implant, implant design, degree of roughness, external morphology, and excessive mechanical load. The microorganisms most commonly associated with implant failure are spirochetes and mobile forms of Gram-negative anaerobes, unless the origin is the result of simple mechanical overload. Diagnosis is based on changes of color in the gingiva, bleeding and probing depth of peri-implant pockets, suppuration, X-ray, and gradual loss of bone height around the tooth. Treatment will differ depending upon whether it is a case of peri-implant mucositis or peri-implantitis. The management of implant infection should be focused on the control of infection, the detoxification of the implant surface, and regeneration of the alveolar bone. This review article deals with the various treatment options in the management of peri-implantitis. The article also gives a brief description of the etiopathogenesis, clinical features, and diagnosis of peri-implantitis.

Impact of Retransmission Mechanism on SIP Overload: Stability Condition and Overload Control

SIP (Session Initiation Protocol) has been widely adopted as a signaling protocol to establish, modify and terminate media sessions between end-users in the Internet. SIP introduces a retransmission mechanism to ensure the reliability of its real-time message delivery. However, retransmission can make server overload worse, leading to server crashes in SIP-based carrier networks (e.g. Skype). In order to study the impact of retransmission mechanism on SIP overload, in this paper, we create a discrete time fluid model to describe the queuing dynamics of an overloaded SIP server. Then we derive a sufficient stability condition that a SIP server can handle the overload effectively under the retransmission mechanism. Fluid model allows us to run fluid-based Matlab simulation directly to evaluate the overload performance. Event-driven OPNET simulation was also conducted to validate our fluid model. Our simulation results demonstrate that: (1) the sufficient stability bound is quite tight. The bound indicates that effective CPU utilization as low as 20% can still lead to an unstable system after a short period of demand burst or a temporary server slowdown. Resource over-provisioning is not a viable solution to the server crash problem; (2) by satisfying the stability condition, the initial queue size introduced by a transient overload can avoid a system crash. Such stability condition can help the operator to determine whether and when to activate overload control mechanism in case of heavy load. A simple overload control solution is also proposed.

Instance chains

Type classes have found a wide variety of uses in Haskell programs, from simple overloading of operators (such as equality or ordering) to complex invariants used to implement type-safe heterogeneous lists or limited subtyping. Unfortunately, many of the richer uses of type classes require extensions to the class system that have been incompletely described in the research literature and are not universally accepted within the Haskell community. This paper describes a new type class system, implemented in a prototype tool called ilab , that simplifies and enhances Haskell-style type-class programming. In ilab , we replace overlapping instances with a new feature, instance chains , allowing explicit alternation and failure in instance declarations. We describe a technique for ascribing semantics to type class systems, relating classes, instances, and class constraints (such as kind signatures or functional dependencies) directly to a set-theoretic model of relations on types. Finally, we give a semantics for ilab and describe its implementation.

Protection system against overload and distributed denial of service attacks

Detection of overload and protection from denial of service attacks is a common problem in information system servers. Such situation may be the result of simple overload, such as increased service request rate during peak hours, or a malicious distributed attack originating from many computers. This article describes a solution to this problem, focusing on protection mechanisms against both natural and malicious overload, based on analysing the queue of requests – which, as described in this paper, is chosen to be unlimited. Furthermore, detection and protection scheme against blocking and crash-bug exploiting attacks is presented.

Effect of tensile cracking on diffusivity of mortar: 3D numerical modelling

Durability of concrete structures can be severely affected by the presence of cracks, whatever is the cause of these cracks: early-age, thermal loading, shrinkage, or a simple mechanical overloading. The paper gives a method and a 3D numerical tool to estimate and predict in a short time the influence of tensile cracks on HTO diffusivity of mortar. Firstly, the methodology adopted to model the mechanical behavior of mortar under 1D tensile loading and its diffusivity at different strains taking into account the 3D description of the material is presented. Then the methodology is applied and validated on a specific mortar that has been previously studied experimentally in the literature. The hydration model CEMHYD3D is used to generate a 3D numerical microstructure of w/c = 0.4 portland cement paste and a mesostructure of mortar. The voxelized images are then transferred from CEMHYD3D to a finite element code in order to simulate 1D tensile behavior of the mortar and its diffusivity before and after the mechanical loading. The outcomes of the FE simulation at the microscale (cement paste) is used as input data at the mesoscale (mortar) modelling. HTO concentration distribution in the whole cracked mesostructure according to the three directions is obtained. Cracks appear as preferential pathways for the penetration of HTO. Diffusion coefficients in the steady state are calculated for uncracked and cracked mortars. The increase rate of diffusivity for a cube of mortar with 6.25 mm per side is quantified for different strain values corresponding to different crack states. An increase by a factor of 1–8.4 times is found. The modelling results are then successfully validated by comparison to experimental data.

Systematic reviews – do they ‘work’ in informing decision-making around health inequalities?

The question of ‘what works’ is a fundamental one not only for politicians and policy makers who need to devise or implement policies on everything from reducing juvenile crime to increasing the national wealth, but it is also fundamental for citizens on the receiving end of interventions. The observation that some things work better than others (and other things work not at all) is commonplace. So is scepticism among the public and professionals about grand claims for the effectiveness of policies, particularly given our understanding that modest interventions normally have modest effects. Whilst research can help in informing decisions about what works, conflicting research findings, and simple information overload often simply cloud the issue. Literature reviews may be designed to solve (or at least address) the problems of information management, but these reviews may themselves conflict. Take, for example, literature reviews of the effectiveness of mentoring in young people to reduce anti-social behaviour. The findings of reviews may conflict not just because of differences in inclusion criteria but because authors appraise and synthesize information on the outcomes differently (for example, not differentiating between more and less objective sources of outcome data, which vary in the extent to which they are prone to bias). Moreover, the outcomes themselves – stated satisfaction with the service, higher self-esteem, or a reduc

Atherosclerosis: A redox-sensitive lipid imbalance suppressible by cyclopentenone prostaglandins

Disorders concerning the metabolism of plasma and intracellular lipids are hallmarks of atherosclerosis. However, failures in proper control of intracellular cholesterol balance, rather than simple cholesterol overloading due to augmented uptake, could fuel atherogenesis. Therefore, the understanding of atherosclerosis-associated lipid alterations, which feed an inflammatory microenvironment in the arterial wall, requires the meticulous investigation of several aspects of lipid synthesis, uptake and export from cells. In this regard, the presence of reactive cysteines in transcription factors and key enzymes of lipid metabolism may dictate cholesterol accumulation, and therefore the progression of vascular disease. The strong inhibitory effect of cysteine-reactant anti-inflammatory cyclopentenone prostaglandins (CP-PGs) over atherosclerosis progression in vivo (LipoCardium technology) symbolizes a new concept of atherosclerosis and its treatment. Results from this laboratory and those from other research groups have unraveled a novel facet in prostaglandin research in that CP-PGs may act as redox signals that guide lipid metabolism in atherosclerosis. By modifying enzymes ( e.g., HMG-CoA reductase, ACAT and cholesteryl ester hydrolases) and transcription factors ( e.g., NF-κB and Keap1) involved in inflammation and lipid metabolism, CP-PGs (especially those of A-series) induce pivotal changes in glutathione and lipid metabolism that completely arrest atherosclerosis progression. Hence, pharmacological manipulation of lipid metabolism by CP-PGs may be a novel and invaluable strategy for treating atherosclerosis. Also, a better understanding of why CP-PGs do not resolve inflammation physiologically may explain many unsolved questions and yield insights into atherogenesis and its termination.

Pressure Sensitive Nonassociative Plasticity Model for DRA Composites

Discontinuously reinforced aluminum (DRA) is currently used where design considerations include specific stiffness, tailorable coefficient of thermal expansion, or wear resistance. Plastic deformation plays a role in failures due to low cycle fatigue or simple ductile overload. DRA is known to exhibit pressure dependent yielding. Plastic deformation in metals is widely regarded to be incompressible, or very nearly so. A continuum plasticity model is developed that includes a Drucker–Prager pressure dependent yield function, plastic incompressibility via a nonassociative Prandtl–Reuss flow rule, and a generalized Armstrong–Frederick kinematic hardening law. The model is implemented using a return mapping algorithm with backward Euler integration for stability and the Newton method to determine the plastic multiplier. Material parameters are characterized from uniaxial tension and uniaxial compression experimental results. Model predictions are compared to experimental results for a nonproportional compression–shear load path. The tangent stiffness tensor is nonsymmetric because the flow rule is not associated with the yield function, which means that the commonly used algorithms that require symmetric matrices cannot be used with this material model. Model correlations with tension and compression loadings are excellent. Model predictions of shear and nonproportional compression–shear loadings are reasonably good. The nonassociative flow rule could not be validated by comparison of the plastic strain rate direction with the yield function and the flow potential due to scatter in the experimental results. The model is capable of predicting the material response obtained in the experiments, but additional validation is necessary for the condition of high hydrostatic pressure.

The Pathophysiology of Patellofemoral Pain

Fundamental to rational, safe, and effective treatment for any orthopaedic condition is an accurate understanding of the etiology of the symptoms. The decades-old paradigm of a pure structural and biomechanical explanation for the genesis of patellofemoral pain is giving way to one in which biologic factors are being given more consideration. It is increasingly evident that a variable mosaic of possible pathophysiologic processes, often caused by simple overload, best accounts for the etiology of patellofemoral pain in most patients. Inflamed synovial lining and fat pad tissues, retinacular neuromas, increased intraosseous pressure, and increased osseous metabolic activity of the patella all have been documented as contributing to the perception of anterior knee pain. Considered together, these processes can be characterized as loss of tissue homeostasis and can be seen as providing a new and alternative explanation for the conundrum of anterior knee pain. Certain high loading conditions of the patellofemoral joint can be of sufficient magnitude to induce the symptomatic loss of tissue homeostasis so that, once initiated, they may persist indefinitely. From this new biologic perspective, it clinically matters little what structural factors may be present in a given joint (such as chondromalacia, patellar tilt or a Q angle above a certain value) if the pain free condition of tissue homeostasis is safely achieved and maintained. Level V (expert opinion). See the Guidelines for Authors for a complete description of levels of evidence.

The Effect of Negative Stress Ratio Load History on High Cycle Fatigue Threshold

Abstract The objective of this research was to measure the load history effects of negative stress ratio loading on the high cycle fatigue (HCF) crack growth threshold of Ti-6Al-4V. Previous work has shown an increase in the HCF threshold that is dependent on the Kmax during the low cycle fatigue loading that nucleated a crack. The increase in fatigue limit was attributed to an overload effect from the LCF loading and was quantified through the use of a simple overload model. On the contrary, evidence from R = −1 testing suggests that negative overloads, referred to as underloads, may reduce this Kmax load history effect and even lower the threshold below long crack values. To investigate this further, smooth and notched Ti-6Al-4V specimens were pre-loaded in fatigue below their endurance limit at stresses expected to nucleate cracks in approximately 10 million and 100 000 cycles, respectively, and at stress ratios of −3.5 and −3, respectively. Although the smooth specimens could not be monitored for crack nucleation, the notched specimens allowed the use of an infrared damage detection system to monitor the localized region at the notch root for indications of crack nucleation. These cracked specimens were then heat tinted, and several were also stress relieved to remove load history effects. All of the preloaded specimens were then HCF step tested to determine the fatigue limit stress or threshold. Although the smooth bars showed little effect due to the preloading at negative R, the threshold results on the notched specimens that developed measurable cracks seem to show competing effects of underloading and Kmax overloading, dependent somewhat on precrack length. The specimens with smaller cracks nucleated at R = −3 tend to have a reduced HCF threshold compared to the conventional long crack threshold. Short crack effects and load-history effects are quantitatively explained with the aid of a Kitagawa diagram with an El Haddad short crack correction.

Projectile impact—A major cause for fracture of flat glass

Impact is the largest single cause of the fracture of glass objects, although thermal stresses and simple overloading, including pressure loading, also contribute to glass failures. Impact fractures of glass may be caused by either the glass object contacting a hard surface, such as when champagne glasses are thrown into a stone fireplace, or by a projectile striking the glass, such as a baseball encountering a window or a stone striking an auto windshield. In every instance, the impact fracture of glass appears to occur instantaneously, accompanied by an acoustic outburst of discernible magnitude. For these reasons, many glass impact fractures, particularly those of beverage containers, are attributed erroneously to explosions.

Predictions of fatigue crack growth in aluminium alloy 2024–T351 using constraint factors

A substantial portion of the service life of aerospace structures is characterised by highly variable loading conditions. Prediction of the fatigue life of flawed structural components requires an adequate description of the transient behaviour of the fatigue crack growth rate following a change in loading conditions. Prediction of fatigue crack growth following the application of single tensile overloads was performed using a modified strip-yield model. A plastic constraint factor, α, was incorporated into the model. Initially it was assumed that α was constant throughout the crack growth process. Then a variable constraint factor was introduced. The modified strip-yield model was used to investigate the effects of using a constant and variable constraint factor in the prediction of simple overload fatigue crack growth tests performed on aluminium alloy 2024–T351. Results from constant amplitude fatigue tests, for different thickness, R-ratio and stress level, were used to develop an empirical constraint factor equation. This equation was subsequently used in the prediction of the overload fatigue tests. Improved simulations were obtained compared to the use of a constant constraint factor. Furthermore, additional improvements in the prediction of overload retardation effects were obtained by activating a constraint-loss regime ( α=1.0 or plane stress conditions) immediately after the overload. The constraint factor remained equal to one until the crack grew out of the overload plastic zone, after which α would revert back to the value calculated from the constraint equation.

Experimental study of vascularized bone grafts in rat: Effect of mechanical loading on bone dynamics

We studied the etiology of postoperative hypertrophy of vascularized bone grafts in a murine experimental model. Syngeneic grafting of revascularized ulna to rat tibia was performed with (group 1) or without (group 2) mechanical loading. The effect of simple overloading on intact bone was studied by segmental resection of the radius (group 3). Bone dynamics were examined by histomorphological measurements. Significant hypertrophy was observed in the early postoperative period in both groups 1 and group 2. After the initial phase, bone growth continued and extensive remodeling was observed in group 1, while marked bone resorption was observed in group 2. Adaptive remodeling was also observed in group 3 after surgery, but was slower than that in groups 1 and 2. Early hypertrophy of vascularized grafts did not correspond to mechanical loading. These results suggest that mechanical loading is the principal factor responsible for remodeling in vascularized bone grafts for their adaptation to a new environment.