Classical parking functions are defined as the parking preferences for $n$ cars driving (from west to east) down a one-way street containing parking spaces labeled from $1$ to $n$ (from west to ...east). Cars drive down the street toward their preferred spot and park there if the spot is available. Otherwise, the car continues driving down the street and takes the first available parking space, if such a space exists. If all cars can park using this parking rule, we call the $n$-tuple containing the cars' parking preferences a parking function.
In this paper, we introduce a generalization of the parking rule allowing cars whose preferred space is taken to first proceed up to $k$ spaces west of their preferred spot to park before proceeding east if all of those $k$ spaces are occupied. We call parking preferences which allow all cars to park under this new parking rule $k$-Naples parking functions of length $n$. This generalization gives a natural interpolation between classical parking functions, the case when $k=0$, and all $n$-tuples of positive integers $1$ to $n$, the case when $k\geq n-1$. Our main result provides a recursive formula for counting $k$-Naples parking functions of length $n$. We also give a characterization for the $k=1$ case by introducing a new function that maps $1$-Naples parking functions to classical parking functions, i.e. $0$-Naples parking functions. Lastly, we present a bijection between $k$-Naples parking functions of length $n$ whose entries are in weakly decreasing order and a family of signature Dyck paths.
A sulfonated graphene catalyst was designed and tested in the acetylation of glycerol. The catalyst was synthesized using graphite as starting material and comprised three stages, which included: (i) ...synthesis the graphene oxide by means of a modified Hummers method, (ii) reduction with ascorbic acid, and (iii) functionalization of the material with sulfanilic acid by in situ diazotization. Structural, morphological and chemical properties were characterized by SEM, XRD, and FT-IR spectroscopy. The acidity was determined by elemental analysis. The catalytic properties of catalyst in the glycerol acetylation were studied and compared with a commercial sulfonic resin, i.e. Amberlyst® 15. The sulfonated graphene presents attractive features in the catalytic transformation of glycerol, allowing for significant increase in the reaction rate at low temperature, and achieving at optimum activity and greater selectivity towards triacetin.
Beer is one of the oldest and most known alcoholic beverages whose organoleptic characteristics are the attributes that the consumer seeks, which is why it is essential to ensure proper quality ...control of the final product. Fourier transform mid-infrared (FT-MIR) spectroscopy coupled with multivariate analysis can be an alternative to traditional methods to predict quality parameters in craft beer. This study aims to develop prediction models based on FT-MIR spectroscopy to simultaneously quantify quality parameters (color, specific gravity, alcohol volume, bitterness, turbidity, pH, and total acidity) in craft beer. Additionally, principal component analysis (PCA) was applied, and it was possible to classify craft beer samples according to their style. Partial least squares (PLS1) developed the best predictive model by obtaining higher R
c (0.9999) values and lower standard error of calibration (SEC: 0.01-0.11) and standard error of prediction (SEP: 0.01-0.14) values in comparison to the models developed with the other algorithms. Specific gravity could not be predicted due to the low variability in the values. Validation and prediction with external samples confirmed the predictive capacity of the developed model. By making a comparison to traditional techniques, FT-MIR coupled with multivariate analysis has a higher advantage, since it is rapid (approximately 6 min), efficient, cheap, and eco-friendly because it does not require the use of solvents or reagents, representing an alternative to simultaneously analyzing quality parameters in craft beer.
Classical antibacterial drugs were designed to target specific bacterial properties distinct from host human cells to maximize potency and selectivity. These designs were quite effective as they ...could be easily derivatized to bear next-generation drugs. However, the rapid mutation of bacteria and their associated acquired drug resistance have led to the rise of highly pathogenic superbug bacterial strains for which treatment with first line drugs is no match. More than ever, there is a dire need for antibacterial drug design that goes beyond conventional standards. Taking inspiration by the body’s innate immune response to employ its own supply of labile copper ions in a toxic attack against pathogenic bacteria, which have a very low Cu tolerance, this review article examines the feasibility of Cu-centric strategies for antibacterial preventative and therapeutic applications. Promising results are shown for the use of Cu-containing materials in the hospital setting to minimize patient bacterial infections. Studies directed at disrupting bacterial Cu regulatory pathways elucidate new drug targets that can enable toxic increase of Cu levels and perturb bacterial dependence on iron. Likewise, Cu intracellular chelation/prochelation strategies effectively induce bacterial Cu toxicity. Cu-based small molecules and nanoparticles demonstrate the importance of the Cu ions in their mechanism and display potential synergism with classical drugs.
Tropical forests on karstic relief (tropical karst forest) are among the most species-rich biomes. These forests play pivotal roles as global climate regulators and for human wellbeing. Their ...long-term conservation could be central to global climate mitigation and biodiversity conservation. In Mexico, karst landscapes occupy 20% of the total land surface and are distributed mainly in the southeast of the country, along the eastern slope, and in the Yucatan Peninsula. Within each of these areas, the following types of karst occur: coastal karst, plain karst, hill karst, and mountain karst (low, medium, high). Mountain karst cover 2.07% of Mexico's land surface and are covered by tropical rainforests, montane cloud forests, and tropical deciduous forests. These are probably one of the most diverse biomes in Mexico. However, the mountain karst forests of Mexico have received little attention, and very little is known about their diversity. Here, we evaluated the vascular plant species richness within the mountain karst forests of Mexico. We assembled the first, largest, and most comprehensive datasets of Mexican mountain karst forest species, from different public databases (CONABIO, GBIF, IBdata-UNAM), which included a critical review of all data. We compiled a list of the families, genera, and species present within the mountain karst forests of Mexico. Taxa that best characterize these forests were identified based on their spatial correlation with this biome. We explored biodiversity patterns, identifying areas with the highest species richness, endemism centers, and areas of relatively low sampling intensity. We found that within the mountain karst forests of Mexico there are representatives of 11,771 vascular plant species (253 families and 2,254 genera), ca. 50% of the Mexican flora. We identified 372 species endemic to these forests. According to preliminary IUCN red list criteria, 2,477 species are under some category of conservation risk, of which 456 (3.8%) are endangered. Most of the Mexican mountain karst forests have been extensively explored and six allopatric, species-rich areas were identified. Compared to other regions in the world, the mountain karst forests of Mexico are one of the most diverse biomes. They contain more species than some entire montane systems in Mexico such as Sierra Madre Oriental, and Sierra Madre del Sur. Also, the mountain karst forests of Mexico are most diverse than similar forests of South America and Asia, even if considering the effect of different sampling areas. The fact that mountain karst forests are embedded in areas of high biotic diversity, probably contributes to their great floristic diversity. Thus, the mountain karst forests of Mexico are an important source of diversity and shelters a large percentage of the Mexican flora.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
6.
Parking Functions: Choose Your Own Adventure Carlson, Joshua; Christensen, Alex; Harris, Pamela E. ...
The College mathematics journal,
09/2021, Letnik:
52, Številka:
4
Journal Article
Recenzirano
In this short adventure, we simulate for the reader the twists and turns that encompass the research process. Sometimes, we cruise through obstacles with maximum productivity. Other times, we seem to ...exhaust our resources and it feels like no more progress can be made. Ultimately, the journey is never over as we continue to find new paths to explore. These paths can sometimes take us down unexpected roads, which can lead to interesting connections. Many researchers have experienced this. Thus, the connections of parking functions to other fields are plenty. For instance, parking functions have been studied on graphs in 4. Alternatively, in 15, parking functions have been connected to volumes of Pitman-Stanley polytopes. Moreover, generalizations abound and all that is left is more time to enumerate them and discover their properties. We are counting on you to continue on the quest to solve parking problems.
La flexibilidad de volumen es utilizada en el presente artículo para determinar la capacidad de respuesta ante cambios en los factores de deterioro de un producto perecedero en las etapas de una ...cadena de suministro; el objetivo principal de este estudio es evaluar el impacto que tiene esta estrategia sobre dos indicadores claves para el desempeño de la red como lo son los costos logísticos y el nivel de servicio. La investigación involucra el funcionamiento de una red de distribución de Papaya conformada por un productor y un detallista, la cual es simulada a través de Dinámica de Sistemas. Se logra establecer que una política de flexibilidad de volumen mejora notablemente indicadores como el nivel de servicio y los costos considerados en el estudio; sin embargo, utilizar esta estrategia implica asumir un mayor costo de almacenamiento de inventario y un costo adicional de aumento de capacidad.
Este artículo da cuenta del estado de la producción de conocimiento científico que se ha venido desarrollando entre el deporte y la discapacidad en Colombia en función de dos aspectos: 1) el ...componente didáctico, que se enfoca en lo referido a los modos de relación entre partícipes, modelos de intervención, procesos evaluativos y, en general, el rol de los docentes o entrenadores. 2) Los propósitos formativos que se han venido priorizando. Para esto, se realizó una búsqueda en diferentes bases de datos aplicando como criterio de inclusión principal que fueran artículos publicados en revistas colombianas reconocidas. Los artículos seleccionados se sometieron a una matriz de análisis categorial para el proceso interpretativo correspondiente. Como conclusiones se destacan la necesidad de fortalecer el componente educativo en las propuestas de intervención y el papel relevante que tiene y podrá tener el deporte en el abordaje de la discapacidad.
Scientific evidence is not clear regarding the use of antimicrobial mouth rinse before dental extraction to reduce bacteremia. We tested the null hypothesis that there would be no difference in the ...incidence of bacteremia following dental extractions in patients treated with or without chlorhexidine.
We conducted a meta-analysis following the recommendations proposed by PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The data sources Pubmed, Cochrane, Web of Science, Science Direct, Scopus, and Ovid MD were searched until April 30, 2017. (chlorhexidine) AND (bacteremia OR bacteraemia) AND (extraction OR removal) were used as key words in a free-text search. Published meeting abstracts were searched. The references of each article were reviewed. We only included randomized controlled clinical trials. There were no restrictions regarding language or date of publication. The outcome measure was the incidence of the bacteremia measured within the first ten minutes post-extraction. Two reviewers independently undertook the risk of bias assessment and data extraction. A fixed-effects inverse variance weighted meta-analysis was conducted.
Out of 18 studies, eight eligible trials with 523 participants were selected, 267 in the experimental group and 256 in the control group: risk ratio = 0.882 (95% confidence interval 0.799 to 0.975; p = 0.014), heterogeneity I2 = 13.07%, and p = 0.33. The number needed to treat was 16 (95% CI 7-Infinity).
Approximately 12% of bacteremia cases can be prevented if a population is exposed to chlorhexidine. CRD42016046586.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Accurate trajectory tracking is a paramount objective when a mobile robot must perform complicated tasks. In high-speed movements, time delays appear when reaching the desired position and ...orientation, as well as overshoots in the changes of orientation, which prevent the execution of some tasks. One of the aspects that most influences the tracking performance is the control system of the actuators of the robot wheels. It usually implements PID controllers that, in the case of low-cost robots, do not yield a good tracking performance owing to friction nonlinearity, hardware time delay and saturation. We propose to overcome these problems by designing an advanced process control system composed of a PID controller plus a prefilter combined with a Smith predictor, an anti-windup scheme and a Coulomb friction compensator. The contribution of this article is the motor control scheme and the method to tune the parameters of the controllers. It has been implemented in a well-known low-cost small mobile robot and experiments have been carried out that demonstrate the improvement achieved in the performance by using this control system.
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