Knowledge Of Limits Research Articles

Enhanced performance and robustness in anti-lock brake systems using barrier function-based integral sliding mode control

Abstract In anti-lock brake systems (ABS), the primary goal of the controller is to maximize vehicle deceleration by maintaining the slip ratio at an optimal level. This work presents a fresh approach that enhances ABS performance by integrating a sliding mode controller with a barrier function. This method combines integral sliding mode control with adaptive laws informed by barrier functions, effectively managing external disturbances and uncertainties in inertia. A significant benefit of this approach is that it does not require prior knowledge of the upper limits of these uncertainties and disturbances, thanks to the barrier function-based sliding mode control. The system state is initially aligned with the switching manifold, ensuring robust compensation for any uncertainties and disturbances right from the start of braking. During the sliding mode phase, dynamic properties are finely tuned to ensure that the system’s performance remains consistent. The effectiveness and reliability of the proposed controller have been demonstrated through numerical simulations conducted in MATLAB/Simulink, proving its capability across a range of road conditions.

Patterns of caffeine consumption among medical undergraduates in Secunderabad, Telangana, India.

Caffeine products are increasingly found in a wide range of products that abuse of the substance may be unnoticed. Introduction of new energy drinks has led to an increase in consumption of caffeine in the last few decades. Caffeine is a cognitive booster and has physically enhancing effects, leading to its higher consumption across various age groups. The objective of this study was to determine patterns of caffeine consumption and to determine the knowledge and awareness of side effects and safety limits of caffeine consumption among medical undergraduate students. A cross-sectional study was conducted from December 2021 to February 2022 in the Department of Community Medicine at a tertiary care institute, Secunderabad, Telangana, India, among 560 medical undergraduate students of all academic years. A predesigned, pretested, semistructured questionnaire was administered. The mean age of the study population was 19.09 years, and female preponderance (61.2%) was noted. The average self-reported caffeine consumption was 151.3 mg/day. The average caffeine consumption was found to be higher among males (174 mg/day) as compared to females (137 mg/day). The average consumption of caffeine during exam time was higher than the daily ceiling limit, >300 mg/day, in 38.1% of students, which was statistically significant (P = 0.015). Caffeine consumption during times of stress increased among medical students, which is an unfavorable sign as the majority of the times, medical students in future have to deal with physically and emotionally stressful situations during work hours.

Assessment of different forecasting strategies for the breaking load resistance in notched specimens 3d-printed in PLA using additive manufacturing (FFF) technology

The introduction of fused deposition modelling in the industrial sector to produce functional components in thermoplastic materials, such as PLA, requires knowledge of the performance limits of such elements during the design phase. Predicting the breaking load resistance of notched specimens is essential to evaluate the mechanical performance of components manufactured using this technology. This study compares different methodologies based on the critical distance criterion (TCD) for predicting the static breaking strength of printed notched specimens made with Fused Filament Fabrication (FFF) technology using PLA material. Specimens with different topologies of V-notches were printed according to a standardized configuration. Various analysis techniques were applied to determine the breaking strength of each specimen. By comparing the results obtained with experimental data to assess their accuracy and reliability, it has been demonstrated that these methodologies, coupled with the concept of equivalent elastic material (EMC), can be useful for predicting static breaking load.

Upper thermal tolerance and population implications for the Magdalena River stingray Potamotrygon magdalenae.

Knowledge of thermal tolerance limits provides important clues to the capacity of a species to withstand acute and chronic thermal changes. Climate models predict the increase and intensification of events such as heat waves, therefore understanding the upper thermal limits that a species can tolerate has become of utmost importance. We measured the upper thermal tolerance of the endemic Magdalena river stingray Potamotrygon magdalenae acclimated to experimental conditions, and then used critical thermal methodology to find the temperature at which an organism reaches a critical endpoint where locomotory activity becomes disorganized and the animal loses its ability to escape from conditions that will promptly lead to its death. We also describe the behavioral response of individuals to acute thermal stress and infer the possible consequences of temperature increases in the habitats of P. magdalenae populations. There were no significant differences between sexes in temperature tolerance or behavior. The critical thermal maximum (39°C) was 5.9°C above the maximum recorded temperature for the study area. Although P. magdalenae was tolerant to high temperature and currently is not living at its upper thermal limit, its survival in Guarinocito Pond will be threatened if temperatures continue to increase, considering the warming scenarios predicted for tropical regions due to climate change, even including short-term climate phenomena such as El Niño.

Knowledge of Direct Oral Anticoagulants (DOACS) and Limits of Their Prescription: Survey of Cardiologists, Intensivists, Neurologists and Pulmonologists in Senegal

Knowledge of Direct Oral Anticoagulants (DOACS) and Limits of Their Prescription: Survey of Cardiologists, Intensivists, Neurologists and Pulmonologists in Senegal

Ethical standards in pediatrics: who is a “good pediatrician”?

This article discusses the issues of modern ethical standards in pediatrics, considers the essence of the concept “a good pediatrician”. The key components of the practical professional activity of a pediatrician, such as honesty and integrity, reliability and responsibility, respect for others, compassion and sensitivity, self-improvement, self-awareness and knowledge of the professional limits of providing medical care, connections and cooperation, altruism and protection the interests of the patient and members of his/her family are considered by the authors. Information is provided regarding the basic ethical principles, duties and competencies of the practical professional activity of a pediatrician in the American healthcare system and the ethical principles of a doctor’s activity in Ukraine. The standards of behavior of a pediatrician are described, according to which he can be evaluated both by medical students, residents and colleagues, as well as by parents, which is necessary for providing quality medical care to children and adolescents. The reasons for the formation of conflict situations in the pediatrician’s practice and approaches to their effective resolution are considered, as well as the role of confidentiality and collegiality.

Upper limits of financial risk measures of various degrees of catastrophicity

The question of assessing the magnitude of risks using certain risk measures presents one of the most important problems of modern finance. However, many modern risk measures require considerable effort at times and, in practice, the investor would have sufficient knowledge of the upper limits of those risks. Comparing them with their risk appetite, an investor, in the case when the upper limits of risk measures would fit into their risk appetite, could assess this risk as acceptable to themselves. Only if the upper limit of the appropriate risk measure exceeded their risk appetite would there be a need for a detailed assessment of the appropriate risk measure. The aim of this paper is to consider upper limits first for known risk measures such as value at risk, VaR, and expected deficit or notional value at risk of ES. Next, upper limits are obtained for the risk measures VaR to the degree of t, VaR(t ) and ES to the degree of t, ES(t ) introduced by the author into scientific use. Also, using the results of V. Hürlimann, representations for maximum values of risk measures VaR(t ) and ES(t ) . The method of obtaining the described results is the application of certain representations of all these risk measures, the application of P. Chebyshev’s inequalities, as well as the results of V. Hürlimann. As a result of the study, descriptions have been proposed for the upper limits, expressing them only after a few first moments of the loss distribution law. The author concludes that the study of the upper limits of important risk measures of scientific interest has practical value for the express assessment of relevant risks.

Root relative water content is a potential signal for impending mortality of a subtropical conifer during extreme drought stress.

Adaptation to future climates characterized by more frequent severe droughts requires enhanced mechanistic understanding of tree mortality. However, our knowledge of the physiological limits to withstand extreme drought, and how the coordination between water and carbon traits enhances survival, is still limited. Potted seedlings of Pinus massoniana were dehydrated to three target droughts (percentage loss of stem hydraulic conductivity of ca. 50%, 85%, and 100%; PLC50 , PLC85 and PLC100 ) and then relieved from these target droughts by fully rewatering. Predawn and midday water potentials (Ψ), relative water content (RWC), PLC and nonstructural carbohydrates (NSC) were monitored. During drought, Ψ and RWC declined as PLC increased. Root RWC declined more rapidly than other organ RWCs, particularly after PLC50 stress. All organ NSC concentrations were above predrought values. During rewatering, water trait recovery declined as drought increased, with no mortality at PLC50 but 75% mortality at PLC85 . The observed stem hydraulic recovery at PLC50 following rewatering was not correlated to NSC dynamics. Collectively, our results highlighted the primary role of hydraulic failure in Pinus massoniana seedling mortality by assessing mortality threshold and links among water status and water supply. Root RWC can be considered as a potential warning signal of P. massoniana mortality.

Levels of autotrophy and heterotrophy in mesophotic corals near the end photic zone

Mesophotic corals live at ~30-150 m depth and can sustain metabolic processes under light-limited conditions by enhancing autotrophy through specialized photoadaptations or increasing heterotrophic nutrient acquisition. These acclimatory processes are often species-specific, however mesophotic ecosystems are largely unexplored and acclimation limits for most species are unknown. This study examined mesophotic coral ecosystems using a remotely operated vehicle (Ashmore Reef, Western Australia at 40–75m depth) to investigate the trophic ecology of five species of scleractinian coral (from genera Leptoseris, Pachyseris, and Craterastrea) using stable isotope analyses (δ13C and δ15N) of host and symbiont tissues and protein concentration. Trophic strategies were analyzed between species and between overall corals sampled above and below the end-photic point, where light is only 1% of surface irradiance. Results showed species-specific differences in resource use. Leptoseris hawaiiensis, L. scabra, and P. speciosa had similar Δ13C values (δ13C host - δ13C symbiont) approaching zero (< 0.5 ‰) which indicated greater dependence on symbiont autotrophy. In contrast, Leptoseris glabra and Craterastrea levis had higher Δ13C values (1.4 to 3.5 ‰) which indicated a greater reliance on external carbon sources. The latter two species also demonstrated tight nitrogen recycling within the holobiont, exhibiting low Δ15N values (host δ15N - symbiont δ15N =< 0.5 ‰), compared to more autotrophic species (Δ15N = >1.2 ‰). Some species demonstrated the ability to maintain metabolic processes despite substantially reduced light availability (0.5 – 2% of surface irradiance). This research challenges our knowledge of acclimation limits for many scleractinian corals and contributes novel information for Ashmore Reef, the Western Australia region and mesophotic ecosystems in general, and critically examines common methods used to interpretate trophic ecology with bulk stable isotopes δ13C and δ15N.

Topoedaphic constraints on woody plant cover in a semi-arid grassland

The proliferation of unpalatable woody plants at the expense of perennial grasses in recent decades has challenged our ability to manage rangelands. While there is substantial research documenting shrub proliferation, we know little about the maximum potential shrub cover for a given topoedaphic setting. To better understand the environmental controls over and constraints on shrub cover, we used high spatial resolution imagery to classify cover of a shrub (Prosopis velutina, velvet mesquite) proliferating in a Sonoran Desert grassland in southern Arizona, USA and explored how maximum shrub cover varies across ecological sites and topoedpahic settings. While the upper limit of shrub cover at the continental-scale is constrained by mean annual precipitation (MAP), our results show that this maxima has a wide range variously dictated by elevation, slope inclination/aspect, soil texture, and rainfall re-distribution. Within the watershed, maximum potential shrub cover ranged from < 3% to 45% with the magnitude and direction of topoedaphic influences varying significantly between landscape components. For example, topoedaphic properties enhanced precipitation (PPT) effectiveness and elevated maximum shrub cover above what might be predicted based on MAP alone on some ecological sites, but reduced PPT effectiveness and constrained shrub cover to levels below what would be predicted from MAP on other sites. Knowledge of upper limits of shrub cover at the within-watershed scale will strengthen dynamic vegetation models, serve as a basis to better design field and modeling experiments and decision support tools, and provide a spatial context indicators for prioritizing conservation/land management goals and objectives.

Characterization of the thermal death time landscape for Enchytraeus albidus

The influence of non-stressing temperatures on life-history traits of enchytraeids (e.g. growth and reproduction) is well described in the literature, but less is known about the influence of stressful temperatures, especially at the high end of the scale. In light of predicted climate changes, where the frequency and intensity of extreme weather events are increasing, it is important to provide detailed knowledge of the thermal limits of species. Experiments leading to a comprehensive understanding of species´ Thermal Death Time (TDT) landscape are particularly valuable because this allows modelling and predicting mortality under dynamic thermal scenarios. In static assays, we determined TDT50 of adult worms at a range of temperatures showing that 50% mortality (TDT50) was reached by exposure to 35.5 °C for only 6 min, whereas TDT50 at 31 °C was 257 min. By fitting the TDT curve to the measurements, we described the influence of temperature on the rate of injury accumulation leading to 50% mortality. Based on injury accumulation rates derived from static assays, we predicted the TDT50 in dynamic assays of various temperature ramping rates with high precision. Additional experiments showed that eggs and juveniles had the same sensitivity to high temperature as adult worms. Combined with previous research, our results show that E. albidus has a wide thermal niche in which survival is possible, from ca. − 25 to + 35 °C. However, exposure time is of the essence for surviving stressful temperatures in the high and low temperature ranges. We discuss that the wide thermal niche of E. albidus may partly explain how this species has become so widely distributed, from the temperate coastal climate in northern Spain to the high Arctic in Svalbard.

LANGUAGES OF WISDOM. TYPOLOGY AND EXAMPLES FROM DIFFERENT TIMES AND CULTURES

The article focuses on wisdom as a particular ‘anonymous discourse’ in the various varieties that make up the typology of wisdom languages. The following overlapping types are distinguished: (1) wisdom sayings without justification – wisdom sayings with justification, (2) wisdom based on optimism and wisdom based on pessimism, (3) wisdom as intellectual cognition and wisdom as moral instruction, (4) wisdom from knowledge and as knowledge, wisdom that follows from knowledge of knowledge limits and wisdom as ignorance that follows from knowledge of ignorance. Examples are given from the Bible, European and Chinese traditions, past and present, and fiction, including Leo Tolstoy, Karl May, and St. Exupery

A review of lethal thermal tolerance among freshwater mussels (Bivalvia: Unionida) within the North American faunal region

Freshwater mussels of the order Unionida are currently one of the most imperiled groups of organisms in the North American faunal region. Accurate risk assessments and development of effective management strategies for remaining populations require knowledge of thermal limits in the face of increasing surface water temperature due to climate change and various anthropogenic factors. We conducted a systematic literature review of unionid mussels (order Unionida, families Margaritiferidae and Unionidae) in the North American faunal region to (1) summarize lethal thermal tolerance data by life stage and taxonomy, (2) discuss ecological and climate change implications of existing lethal tolerance data, and (3) identify needs for future research. We identified lethal tolerance estimates for only 28 of 302 species in the families Unionidae and Margaritiferidae. The mean acute median lethal temperatures were 32.8 °C for glochidia (19 species), 35.0 °C for juveniles (13 species), and 36.3 °C for adults (4 species). Generally, glochidia were less tolerant than juveniles or adults of the same species—but there were several exceptions. Generally, Amblemini had the highest acute and chronic thermal tolerance of all tribes followed by Anodontini, Pleurobemini, Lampsilini, and Quadrilini. Acclimation temperature affected lethal tolerance endpoints in less than half (52 of 145) of comparisons within species. Lethal tolerance data for additional species, combined with a comprehensive database of in situ surface water temperatures, would be useful for modeling the frequency and duration of lethal limit exceedance in North America and identifying populations currently living at or near their upper lethal limits.

Colour vision changes in patients with pressure differences across the lamina cribrosa

AbstractThe retinal nerve fibre layer (RNFL) thickness parameters describe the integrity of retinal ganglion cells (RGC) and their axons and can be affected in pathological processes involving the optic nerve. Glaucoma and papilledema are two conditions where RGCs and hence RNFL, are damaged due to the pressure differences across the lamina cribrosa. The latter separates the intraocular and intracranial pressure compartments. In glaucoma, the intraocular pressure (IOP) is elevated and in papilledema, the intracranial pressure is elevated. When intracranial pressure is managed, papilledema patients can recover without significant loss of RGC. Conversely irreversible RGC loss can occur in severe cases.Subtle, functional changes that are often not detected clinically can remain following recovery. The detection of such changes require sensitive functional tests and a knowledge of normal age limits for the stimulus attribute investigated.Results of preliminary studies designed to assess how colour vision and rod and cone mediated flicker sensitivity recover in papilledema will be reported for a number of patients. Following recovery, the results often reveal binocular summation effects, even when the differences between the two eyes remain significant. Patients classed clinically as fully recovered continue to show small differences between the two eyes, even when the measured binocular thresholds are within the expected age limits.In summary, the preliminary findings from this investigation show how various attributes of vision are affected during the early stages of the disease and after treatment and recovery from late stage of severe papilledema with loss of RGCs.

Designing for downsizing: Home-based barriers and facilitators to reduce portion sizes for children.

Evidence confirms that parents know that they should limit non-core foods for their children since these tend to be high in energy density (HED), fat, salt and sugar. However, it is unclear how knowledge of portion size limits, such as the 100 kcal guide from Public Health England are applied in practice. To observe in real-time children’s home food environment related to portion control and to explore with parents their reported portion size strategies, a mixed methods study was designed. Families with children aged 1–5 years were recruited (n = 21) to a three-part study: (1) to complete questionnaires and interviews on household food intake and portion control; (2) to report daily food intake for 4 days (n = 13) for one parent and their child(ren); (3) to observe home-based food provisioning via videorecording during dinner, breakfast and snack time (n = 6). Although the problem of large portion sizes of HED foods was recognised by mothers, strategies to downsize portions were not necessarily applied at home, as revealed in home observations and diaries. A mismatch between what was observed at home, what was reported in food diaries and what was said in interviews became apparent for some families. Mothers reported the need for greater support and guidance to downsize HED foods since they relied on pre-packaging as a guide to intake. Education and engagement were identified as important parameters for downsizing by mothers. One strategy which could be explored and applied by manufacturers is packaging design to faciliate the 100 kcal guidance using physical and engaging ways to assist parents in downsizing HED foods for their children. To facilitate effective government communication, innovative packaging design can be used to convey clear guidance and to tailor portion size messages for children. Packaging design, alongside government recommendations, can support parents’ goals to achieve healthy eating and can reinforce guidance for portion norms through innovation involving learning, playful engagement, and interaction.

Effect of Capacitor Voltage Ripples on Submodule Active Power Control Limits of Cascaded Multilevel Converters

In the operation of cascaded H-bridge converters and modular multilevel converters with energy storage or renewable power resources, unbalanced active power distribution among the submodules (SMs) is unavoidable. Depending on the operating conditions, there are certain upper and lower limits on the active power that can be processed by a single SM or a subset of SMs. The control system needs to restrict the SM power references to these limits, hence, accurate knowledge of the power limits is important. In existing methods to derive the power limits, the SM capacitor voltages are assumed to have negligible ripples, whereas in practice the ripples can be considerable. This article analyzes the effect of capacitor voltage ripples on the SM active power control limits and highlights the importance of considering the ripple effect. A methodology is proposed to accurately incorporate capacitor voltage ripples in the derivation of SM active power control limits. Simulation and experimental results are provided to evaluate the effectiveness of the proposed methodology.

Predicting global terrestrial biomes with the LeNet convolutional neural network

Abstract. A biome is a major regional ecological community characterized by distinctive life forms and principal plants. Many empirical schemes such as the Holdridge life zone (HLZ) system have been proposed and implemented to predict the global distribution of terrestrial biomes. Knowledge of physiological climatic limits has been employed to predict biomes, resulting in more precise simulation; however, this requires different sets of physiological limits for different vegetation classification schemes. Here, we demonstrate an accurate and practical method to construct empirical models for biome mapping: a convolutional neural network (CNN) was trained by an observation-based biome map, as well as images depicting air temperature and precipitation. Unlike previous approaches, which require assumption(s) of environmental constrain for each biome, this method automatically extracts non-linear seasonal patterns of climatic variables that are relevant in biome classification. The trained model accurately simulated a global map of current terrestrial biome distribution. Then, the trained model was applied to climate scenarios toward the end of the 21st century, predicting a significant shift in global biome distribution with rapid warming trends. Our results demonstrate that the proposed CNN approach can provide an efficient and objective method to generate preliminary estimations of the impact of climate change on biome distribution. Moreover, we anticipate that our approach could provide a basis for more general implementations to build empirical models of other climate-driven categorical phenomena.

Morphometry of Fetal Liver From Human Fetuses Between 12-36 Weeks Gestational Age.

Background of the studyTo assess the prenatal development of the human liver between 12-36 weeks of gestational age by measuring morphometric parameters using conventional autopsy and to evaluate the morphometric parameters of the human fetus and its liver and their correlation to predict the gestation age.Materials & methodsThe present study was conducted in the Department of Anatomy, All India Institute of Medical Sciences, Rishikesh, India, on 33 normal fetuses of gestational age 12-36 weeks collected from the Department of Obstetrics and Gynecology of the same institute. which were classified into five groups: A (12-16 weeks), B (17-21 weeks), C (22-26 weeks), D (27-31 weeks), and E (32-36 weeks). The parameters measured were liver weight, liver volume, transverse diameter, sagittal diameter, vertical length, length, and width of all four lobes of the liver, i.e., right, left, caudate and quadrate lobe. Also, general morphometric parameters of the fetuses were measured like fetal body weight, crown-rump length, crown-heel length, biparietal diameter, head circumference, chest circumference, abdominal circumference, hand length, foot length, inner inter-canthal distance, outer inter-canthal distance. The obtained data were statistically analyzed using ANOVA, and Pearson’s correlation was assessed.ResultsThere was a statistically significant increase amongst all the fetal general parameters and parameters of liver except bi-parietal diameter, p-value <0.001. The bi-parietal diameter was weakly statistically significant correlated with all other parameters except with chest circumference, crown-heel length, length and width of caudate lobe, and the width of the quadrate lobe and left lobe where it was statistically non-significant.ConclusionBi-parietal diameter is a statistically non-significant parameter to calculate gestation age. The knowledge of morphological features and normal limits of dimensions of the liver with respect to gestational age is a reliable reference to help to prevent misdiagnosis of various pathological conditions of the liver like cirrhosis, hepatomegaly, fetal anemia, intrauterine growth retardation, congenital anomalies like Down's Syndrome, etc.

Toward an optimized design of the LNG production process: Measurement and modeling of the solubility limits of p-xylene in methane and methane + ethane mixtures at low temperature

Accurate knowledge of the solubility limits of impurities in LNG allows an optimized design of the purification units installed upstream of the liquefaction train and the prevention of solid formation in the main cryogenic heat exchanger that would reduce the performance of the heat exchanger, increase maintenance operations and cause potential safety problems. The solubility of p-xylene in methane and in methane + ethane (5 and 10% mole fraction of ethane) has been measured at p = 5 MPa from T = 183 down to T = 123 K. The experimental results have been obtained by a static-analytic method with analysis of the fluid phase samples by gas chromatography. Solubility of p-xylene in methane and methane + ethane mixtures has been measured for the first time in this temperature range. The obtained data have been modelled by the Soave-Redlich-Kwong (SRK) cubic Equations of State (EoS), tuning pure component parameters, alpha functions, and binary interaction parameters, considering thermodynamic constraints. A robust multi-phase flash algorithm was established for vapor-liquid-liquid-solid (VLLSE) equilibrium by applying phase stability analysis. The revamped thermodynamic methods and data allow accurate prediction of the multiple phase boundaries that can be present when cooling a typical natural gas mixture.

Introduction: Limits of Knowledge – Knowledge of Limits: The Productiveness of Ignorance, Non-Knowledge, and Agnotology

Introduction: Limits of Knowledge – Knowledge of Limits: The Productiveness of Ignorance, Non-Knowledge, and Agnotology