Measurement scales on the continuum

In a seminal article in 1946, S. S. Stevens noted that the numerical measures then in common use exhibited three admissible groups of transformations: similarity, affine, and monotonic. Until recently, it was unclear what other scale types are possible. For situations on the continuum that are homogeneous (that is, objects are not distinguishable by their properties), the possibilities are essentially these three plus another type lying between the first two. These types lead to clearly described classes of structures that can, in principle, be incorporated into the classical structure of physical units. Such results, along with characterizations of important special cases, are potentially useful in the behavioral and social sciences.     

Topographic forcing of the atmosphere and a rapid change in the length of day

During June to September 1992, a special campaign was held to measure rapid changes in Earth's rotation rate and to relate these measurements to variations in the atmosphere's angular momentum, due principally to changes in zonal winds. A strong rise in both length of day and atmospheric momentum during a particular 6-day subperiod is documented, and this example of a short-period perturbation is identified with a specific regional coupling mechanism. Mountain torques within the southern tropics appear to account for most of the rapid momentum transfer between the solid Earth and atmosphere, with those across South America especially important.     

Bovine ceroid-lipofuscinosis: pathology of blindness

Five Devon cattle with suspected ceroid-lipofuscinosis and aged between 19 and 39 months of age were humanely slaughtered and subjected to post-mortem examination. There was severe atrophy of the cerebrum, particularly of the occipital cortex. Microscopy also showed severe atrophy of the retina with complete loss of photoreceptor cells, even in the youngest animal examined. Histopathologically the disease was characterised by accumulation of a fluorescent lipopigment in neurones, including those of the retina and a severe astrocytosis. The disease, which is characterised by the accumulation of subunit c of mitochondrial ATP synthase, is similar to that extensively described in South Hampshire sheep except that the retinal lesions were more severe. In contrast, tremors were not noted in the cattle. The clinical history and similarity to the disease in sheep and other species indicated inheritance was as an autosomal recessive trait.     

Cogeneration of electric energy and nitric oxide

A solid electrolyte fuel cell operating on ammonia fuel has been constructed and tested. The yield of nitric oxide can exceed 60 percent with simultaneous electric energy production. Two dimensionless numbers have been identified which govern the product selectivity and power output of this fuel cell. The cell appears to be a promising candidate for nitric acid and electric energy cogeneration.     

猪Delta冠状病毒的流行病学调查及M基因序列分析

为了解猪Delta冠状病毒(Porcine deltacoronavirus,PDCoV)在发生腹泻疫情猪群中的感染情况,根据PDCoV M基因的保守序列设计了一对检测引物,建立了猪Delta冠状病毒的的检测方法,其最低核酸检测限量为3.92×10~3 copies/μL,特异性和灵敏度均较好。利用该方法对2015—2017年上海周边猪场的518份猪腹泻粪便样品进行检测,检测出25份PDCoV阳性样品,阳性感染率达4.8%。在所检出的阳性样本中,PDCoV与猪嵴病毒(Porcine kobuvirus,PKV)和猪星状病毒(Porcine astrovirus,PAstV)的混合感染率较高,分别为40%和48%;PDCoV与猪流行性腹泻病毒(Porcine epidemic diarrhea virus,PEDV)混合感染率为8.0%,未检测到PDCoV与猪传染性胃肠炎病毒(Transmissible gastroenteritis virus,TEGV)混合感染的样本。随机选取10份PDCoV阳性样本,对扩增的M基因片段同源性进行分析,结果发现,10份样品中核苷酸同源性达95.0%—99.6%,与GenBank登录的PDCoV毒株的同源性为96.1%—100%,说明目前流行的PDCoV毒株的遗传差异不大,该研究可为了解PDCoV流行情况提供参考依据。