Mechanisms of Nausea and Vomiting: Current Knowledge and Recent Advances in Intracellular Emetic Signaling Systems

Nausea and vomiting are common gastrointestinal complaints that can be triggered by diverse emetic stimuli through central and/or peripheral nervous systems. Both nausea and vomiting are considered as defense mechanisms when threatening toxins/drugs/bacteria/viruses/fungi enter the body either via the enteral (e.g., the gastrointestinal tract) or parenteral routes, including the blood, skin, and respiratory systems. While vomiting is the act of forceful removal of gastrointestinal contents, nausea is believed to be a subjective sensation that is more difficult to study in nonhuman species. In this review, the authors discuss the anatomical structures, neurotransmitters/mediators, and corresponding receptors, as well as intracellular emetic signaling pathways involved in the processes of nausea and vomiting in diverse animal models as well as humans. While blockade of emetic receptors in the prevention of vomiting is fairly well understood, the potential of new classes of antiemetics altering postreceptor signal transduction mechanisms is currently evolving, which is also reviewed. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide potential answers.     

Measuring changes in water-related health and hygiene practices by developing-community households.

A population sample from a community in a developing urban area (Botshabelo), which obtains its treated water supply from a communal standpipe system, was subjected to a short Health and Hygiene Awareness and Education (HHA&E) programme to improve its practices on storing water in, and handling water from, storage containers at home. The problem was that the community's practices lead to the deterioration of the microbiological quality of the water in domestic storage containers. Measuring changes in the practices, as well as the microbiological quality of water in the containers, were the instruments used to determine whether the programme had a positive educational effect. This paper reports on selected elements of the practices measurement. Structured interviews, observations and statistical analyses assessed three variables--container hygiene, container storage and hand hygiene. Results indicated insignificant improvements in practices. This was supported by insignificant improvements in the microbiological water quality, that was still above health-safety limits. This implied that short-term "quick fix" HHA&E programmes would tend to be ineffective. Results also suggested that some negative water-hygiene habits may readily change (container hygiene and storage), while behaviour of a more personal nature, such as hand-washing, was not easily changed.     

A p‐Order signed integer‐valued autoregressive (SINAR(p)) model

In this article, we propose an extension of integer‐valued autoregressive INAR models. Using a signed version of the thinning operator, we define a larger class of ‐valued processes, called SINAR, which can have positive as well as negative correlations. Using a Markov chain method, conditions for stationarity and the existence of moments are investigated. In particular, it is shown that the autocorrelation function of any real‐valued AR process can be recovered with a SINAR process, which improves INAR modeling.     

First-order rounded integer-valued autoregressive (RINAR(1)) process

Abstract.  We introduce a new class of autoregressive models for integer-valued time series using the rounding operator. Compared with classical INAR models based on the thinning operator, the new models have several advantages: simple innovation structure, autoregressive coefficients with arbitrary signs, possible negative values for time series and possible negative values for the autocorrelation function. Focused on the first-order RINAR(1) model, we give conditions for its ergodicity and stationarity. For parameter estimation, a least squares estimator is introduced and we prove its consistency under suitable identifiability condition. Simulation experiments as well as analysis of real data sets are carried out to attest the model performance.     

聚口恶唑烷酮/异氰脲酸酯的低温合成与耐热性能

以2,4-二苯基甲烷二异氰酸酯(MDI-50)、环氧树脂(E-54)为原料,分别以Cr3+、Al Cl3和Al Cl3·HMPA为催化剂,在100℃合成了聚口恶唑烷酮/异氰脲酸酯。用红外光谱研究了异氰脲酸酯与口恶唑烷酮的反应历程,用热重分析表征了口恶唑烷酮/异氰脲酸酯的比例与耐热性能的关系。结果表明,3种催化剂首先快速催化氨基甲酸酯/脲基甲酸酯以及异氰脲酸酯三聚环的生成;口恶唑烷酮环逐渐形成,随着受热时间延长,氨基甲酸酯/脲基甲酸酯和异氰脲酸酯逐渐解聚与环氧反应转化为口恶唑烷酮环。材料的耐热性能随口恶唑烷酮含量的增加而增强,最大热失重温度较环氧树脂提高了50℃,达434℃,且750℃时的残炭率提高了3倍。