112 research outputs found

    Proximally Compatible Mappings and Common Best Proximity Points

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    The purpose of this paper is to introduce and analyze a new idea of proximally compatible mappings and we extend some results of Jungck via proximally compatible mappings. Furthermore, we obtain common best proximity point theorems for proximally compatible mappings through two different ways of construction of sequences. In addition, we provide an example to support our main result.This work has been partially funded by Basque Government through Grant IT1207-19

    Some new results on f-contractions in 0-complete partial metric spaces and 0-complete metric-like spaces

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    Within this manuscript we generalize the two recently obtained results of O. Popescu and G. Stan, regarding the F-contractions in complete, ordinary metric space to 0-complete partial metric space and 0-complete metric-like space. As Popescu and Stan we use less conditions than D. Wardovski did in his paper from 2012, and we introduce, with the help of one of our lemmas, a new method of proving the results in fixed point theory. Requiring that the function F only be strictly increasing, we obtain for consequence new families of contractive conditions that cannot be found in the existing literature. Note that our results generalize and complement many well-known results in the fixed point theory. Also, at the end of the paper, we have stated an application of our theoretical results for solving fractional differential equations. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

    Electronic drive and acquisition system for mass spectrometry

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    The present invention discloses a mixed signal RF drive electronics board that offers small, low power, reliable, and customizable method for driving and generating mass spectra from a mass spectrometer, and for control of other functions such as electron ionizer, ion focusing, single-ion detection, multi-channel data accumulation and, if desired, front-end interfaces such as pumps, valves, heaters, and columns

    A quick, simplified approach to the evaluation of combustion rate from an internal combustion engine indicator diagram

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    In this paper a simplified procedure of an internal combustion engine in-cylinder pressure record analysis has been presented The method is very easy for programming and provides quick evaluation of the gas temperature and the rate of combustion. It is based on the consideration proposed by Hohenberg and Killman, but enhances the approach by involving the rate of heat transferred to the walls that was omitted in the original approach. It enables the evaluation of the complete rate Of heat released by combustion (often designated as gross heat release rate or fuel chemical energy release rate), not only the rate of heat transferred to the gas (which is often designated as net heat release rate). The accuracy of the method has been also analyzed and it is shown that the errors caused by the simplifications in the model are very small, particularly if the crank angle step is also small A several practical applications on recorded pressure diagrams taken from both spark ignition and compression ignition engine are presented as well

    Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent deet

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    <p>Abstract</p> <p>Background</p> <p>N,N-Diethyl-3-methylbenzamide (deet) remains the gold standard for insect repellents. About 200 million people use it every year and over 8 billion doses have been applied over the past 50 years. Despite the widespread and increased interest in the use of deet in public health programmes, controversies remain concerning both the identification of its target sites at the olfactory system and its mechanism of toxicity in insects, mammals and humans. Here, we investigated the molecular target site for deet and the consequences of its interactions with carbamate insecticides on the cholinergic system.</p> <p>Results</p> <p>By using toxicological, biochemical and electrophysiological techniques, we show that deet is not simply a behaviour-modifying chemical but that it also inhibits cholinesterase activity, in both insect and mammalian neuronal preparations. Deet is commonly used in combination with insecticides and we show that deet has the capacity to strengthen the toxicity of carbamates, a class of insecticides known to block acetylcholinesterase.</p> <p>Conclusion</p> <p>These findings question the safety of deet, particularly in combination with other chemicals, and they highlight the importance of a multidisciplinary approach to the development of safer insect repellents for use in public health.</p

    Functions of Intermittent Locomotion in Mustached Tamarins (Saguinus mystax)

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    Many animals interrupt their moving with brief pauses, which appear to serve several different functions. We examined the function of such intermittent locomotion in wild living mustached tamarins (Saguinus mystax), small arboreal New World primates that form mixed-species groups with saddleback tamarins (Saguinus fuscicollis). We investigated how different environmental and social factors affect pausing during locomotion and used these data to infer the function of this behavior. As measures of intermittent locomotion, we used percentage of time spent pausing and pause rate. We considered 3 possible functions that are not mutually exclusive: increased endurance, route planning, and antipredator vigilance. Mustached tamarins spent on average (mean ± SE) 55.1 ± 1.0% of time pausing, which makes effective resource exploitation more time consuming and needs to be outweighed by correspondingly large benefits. Percentage of time spent pausing decreased in larger mixed-species groups vs. smaller mixed-species groups and decreased with height and in monkeys carrying infants. It was not affected by sex, age, spatial arrangement, or single-species group size. Pause rate increased in individuals traveling independently compared to those traveling in file, but was not affected by other factors. The group size effect in mixed-species groups lends support to the notion that pausing during locomotion is an antipredator tactic that can be reduced in the increased safety of larger groups, but other results suggest that additional functions, particularly route planning, are also of great importance. Benefits in terms of predator confusion and group movement coordination are also likely to play a role and remain a topic for further research

    Impact of the COVID-19 Pandemic on the Clinical Learning Environment: Addressing Identified Gaps and Seizing Opportunities

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    The clinical learning environment (CLE) encompasses the learner’s personal characteristics and experiences, social relationships, organizational culture, and the institution’s physical and virtual infrastructure. During the COVID-19 pandemic, all four of these parts of the CLE have undergone a massive and rapid disruption. Personal and social communications have been limited to virtual interactions or shifted to unfamiliar clinical spaces because of redeployment. Rapid changes to the organizational culture required prompt adaptations from learners and educators in their complex organizational systems yet caused increased confusion and anxiety among them. A traditional reliance on a physical infrastructure for classical educational practices in the CLE was challenged when all institutions had to undergo a major transition to a virtual learning environment. However, disruptions spurred exciting innovations in the CLE. An entire cohort of physicians and learners underwent swift adjustments in their personal and professional development and identity as they rose to meet the clinical and educational challenges they faced due to COVID-19. Social networks and collaborations were expanded beyond traditional institutional walls and previously held international boundaries within multiple specialties. Specific aspects of the organizational and educational culture, including epidemiology, public health, and medical ethics, were brought to the forefront in health professions education, while the physical learning environment underwent a rapid transition to a virtual learning space. As health professions education continues in the era of COVID-19 and into a new era, educators must take advantage of these dynamic systems to identify additional gaps and implement meaningful change. In this article, health professions educators and learners from multiple institutions and specialties discuss the gaps and weaknesses exposed, opportunities revealed, and strategies developed for optimizing the CLE in the post–COVID-19 world

    Penetration of the Stigma and Style Elicits a Novel Transcriptome in Pollen Tubes, Pointing to Genes Critical for Growth in a Pistil

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    Pollen tubes extend through pistil tissues and are guided to ovules where they release sperm for fertilization. Although pollen tubes can germinate and elongate in a synthetic medium, their trajectory is random and their growth rates are slower compared to growth in pistil tissues. Furthermore, interaction with the pistil renders pollen tubes competent to respond to guidance cues secreted by specialized cells within the ovule. The molecular basis for this potentiation of the pollen tube by the pistil remains uncharacterized. Using microarray analysis in Arabidopsis, we show that pollen tubes that have grown through stigma and style tissues of a pistil have a distinct gene expression profile and express a substantially larger fraction of the Arabidopsis genome than pollen grains or pollen tubes grown in vitro. Genes involved in signal transduction, transcription, and pollen tube growth are overrepresented in the subset of the Arabidopsis genome that is enriched in pistil-interacted pollen tubes, suggesting the possibility of a regulatory network that orchestrates gene expression as pollen tubes migrate through the pistil. Reverse genetic analysis of genes induced during pollen tube growth identified seven that had not previously been implicated in pollen tube growth. Two genes are required for pollen tube navigation through the pistil, and five genes are required for optimal pollen tube elongation in vitro. Our studies form the foundation for functional genomic analysis of the interactions between the pollen tube and the pistil, which is an excellent system for elucidation of novel modes of cell–cell interaction

    Vigilance of mustached tamarins in single-species and mixed-species groups—the influence of group composition

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    Species that participate in mixed-species groups (MSG) may have complementary roles in antipredator strategies. We studied vigilance in mustached tamarins (Saguinus mystax), small arboreal primates that form stable mixed-species groups with saddleback tamarins (Saguinus fuscicollis), in order to examine how the direction of vigilance changes with different species group compositions and whether the division of labor between the two species can be confirmed. We did so by comparing quantitative and qualitative differences in vigilance behavior between same individuals in and out of association (case A); MSG and single-species groups of the same total group size from two different populations (case B); and MSG of the same group size but with a different ratio of conspecifics to heterospecifics (case C). We predicted that individuals would increase downward scanning when heterospecifics are absent or their percentage is low, but total vigilance would increase only in case A due to the group size effect. However, mustached tamarins increased total vigilance due to horizontal scanning in cases A and C, and the predictions were confirmed only in small-sized groups in case B. Thus, we found indications that associating tamarin species in MSG might complement each other in the direction of vigilance, but the division of labor alone does not satisfactorily explain all the findings. There appear to be other mechanisms at work that define how direction of vigilance changes with group size and species composition. Complementarity of species probably occurs due to species vertical stratification rather than differences in the direction of vigilance
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