Patologia de sementes de cereais de inverno.

bitstream/item/128960/1/ID-38429-1987-LV-patologiasementescereaisinverno.pd

An axiomatic characterization of ensconcement-based contraction

In this article, we propose an axiomatic characterization for ensconcement-based contraction functions, belief base functions proposed by Williams. We relate this function with other kinds of base contraction functions.info:eu-repo/semantics/publishedVersio

On the search for the chiral anomaly in Weyl semimetals: The negative longitudinal magnetoresistance

Recently, the existence of massless chiral (Weyl) fermions has been postulated in a class of semi-metals with a non-trivial energy dispersion.These materials are now commonly dubbed Weyl semi-metals (WSM).One predicted property of Weyl fermions is the chiral or Adler-Bell-Jackiw anomaly, a chirality imbalance in the presence of parallel magnetic and electric fields. In WSM, it is expected to induce a negative longitudinal magnetoresistance (NMR), the chiral magnetic effect.Here, we present experimental evidence that the observation of the chiral magnetic effect can be hindered by an effect called "current jetting". This effect also leads to a strong apparent NMR, but it is characterized by a highly non-uniform current distribution inside the sample. It appears in materials possessing a large field-induced anisotropy of the resistivity tensor, such as almost compensated high-mobility semimetals due to the orbital effect.In case of a non-homogeneous current injection, the potential distribution is strongly distorted in the sample.As a consequence, an experimentally measured potential difference is not proportional to the intrinsic resistance.Our results on the MR of the WSM candidate materials NbP, NbAs, TaAs, TaP exhibit distinct signatures of an inhomogeneous current distribution, such as a field-induced "zero resistance' and a strong dependence of the `measured resistance" on the position, shape, and type of the voltage and current contacts on the sample. A misalignment between the current and the magnetic-field directions can even induce a "negative resistance". Finite-element simulations of the potential distribution inside the sample, using typical resistance anisotropies, are in good agreement with the experimental findings. Our study demonstrates that great care must be taken before interpreting measurements of a NMR as evidence for the chiral anomaly in putative Weyl semimetals.Comment: 13 pages, 6 figure

Testing the Equivalence of Regular Languages

The minimal deterministic finite automaton is generally used to determine regular languages equality. Antimirov and Mosses proposed a rewrite system for deciding regular expressions equivalence of which Almeida et al. presented an improved variant. Hopcroft and Karp proposed an almost linear algorithm for testing the equivalence of two deterministic finite automata that avoids minimisation. In this paper we improve the best-case running time, present an extension of this algorithm to non-deterministic finite automata, and establish a relationship between this algorithm and the one proposed in Almeida et al. We also present some experimental comparative results. All these algorithms are closely related with the recent coalgebraic approach to automata proposed by Rutten

Performance of robust estimators: Sampling, variables and dimensions

The use of data collected from market research and opinion surveys is common in social and business areas. Probability samples are usually the first option for data collection though they are quite often excluded due to the non existence of a suitable sampling frame. In addition to the lack of randomness of sample data, further problems are caused by inadequate sample representativeness for some population characteristics, limitations of the measuring instrument and occurrence of measurement errors. In these situations, robust statistical techniques can be a valid option for estimation purposes as they are not sensitive to sample biases. The main aim of this study is to evaluate the performance of robust estimators, particularly Huber M-estimator, Tukey's biweight and Least Trimmed Squares (LTS) estimators, when compared to the sample mean and median, and applied to different types of variables, diverse sampling methods and dimensions. Quantitative and qualitative ordinal Likert type variables with 4, 6 and 10 point were used. Samples were generated by stratified and quota methods, both with dimensions 50, 100 and 300. Results show the best behavior of the Huber and the Tukey's biweight estimators in most situations, particularly for quantitative variables, for both sample methods. The LTS estimator performed worse than any other estimator, being better solely in the case of ordinal variables with a 4 point scale, sharp skewness and high kurtosis.info:eu-repo/semantics/publishedVersio

Studies on brutal contraction and severe withdrawal

In this paper we present an axiomatic characterization for brutal contractions. Then we consider the particular case of the brutal contractions that are based on a bounded ensconcement and also the class of severe withdrawals which are based on bounded epis temic entrenchment relations that are defined by means of bounded ensconcements (using the procedure proposed by Mary-Anne Williams). We present axiomatic characterizations for each one of those classes of functions and investigate the interrelation among them.info:eu-repo/semantics/publishedVersio

Modified Bristow-Latarjet procedure for treatment of recurrent traumatic anterior glenohumeral dislocation

Retrospective case-control study of authors experience in the modified Bristow-Latarjet procedure for treatment of recurrent traumatic anterior glenohumeral dislocation with glenoid bone injury.info:eu-repo/semantics/publishedVersio

Emotional Experiences Among College Students Returning to Campus Amid the COVID-19 Pandemic

Introduction: Since the beginning of the COVID-19 pandemic, there have been over two million confirmed cases. Of those cases, the majority (57.4%) occurred among young adults aged 18–24 years old (CDC, 2021).Although existing research demonstrates that following recommended health behaviors (e.g., vaccinations, hand washing, social distancing) reduces the risk of contracting COVID-19,less research has explored the emotional experiences of young adults returning to campusduringtheCOVID19 pandemic. The experiences of young adults during this time frame are important to study as they are going through natural shifts in their lives. Changes due to COVID in their routines, education, employment have had significant effects on the emotional well-being of young adults. The long-term effects of these changes are unknown, but opinions and experiences of COVID-19 in the eyes of young adults can help us understand their willingness to engage in preventative health behaviors. Therefore, the purpose of the current study was to qualitatively explore the emotional experiences of college students as they returned back to campus in the Fall of 2020. Methods: Participants were college students (N=24) who participated in focus groups held in July and August 2020. Questions about COVID-19 experiences and returning to campus during a pandemic were discussed. Data were qualitatively analyzed for themes. Results: Participants expressed a variety of emotional experiences ranging from concern about themselves and others, to anxiety and uncertainty about COVID-related changes. A commonly expressed emotion was one of loss; loss of academic, social, and community experiences. Participants also expressed loss of control over their environments and fear regarding others’ behaviors. Stress and the challenge of coping with COVID-related demands was also frequently described. Despite many negative emotions, participants also expressed some degree of understanding and acceptance about needed changes and that they felt safe returning to campus. Discussion: Overall, results demonstrate that emotional experiences varied, and at times, was subjective. Loss was an underlying, common experience, especially for college students who have many diverse opportunities. Loss seemed to play a strong role in affecting others lives and other emotional experiences. Coping skills also varied, especially under conditions where participants felt stressed by the ongoing need to manage new skills and behaviors related to COVID-19. Overall, participants concern surrounding COVID-19 was for others and not themselves. Despite the myriad of emotions, students indicated that they felt safe returning to campus