A large discontinuity in the mid-twentieth century in observed global-mean surface temperature

Data sets used to monitor the Earth's climate indicate that the surface of the Earth warmed from approximately 1910 to 1940, cooled slightly from approximately 1940 to 1970, and then warmed markedly from approximately 1970 onward. The weak cooling apparent in the middle part of the century has been interpreted in the context of a variety of physical factors, such as atmosphere-ocean interactions and anthropogenic emissions of sulphate aerosols. Here we call attention to a previously overlooked discontinuity in the record at 1945, which is a prominent feature of the cooling trend in the mid-twentieth century. The discontinuity is evident in published versions of the global-mean temperature time series, but stands out more clearly after the data are filtered for the effects of internal climate variability. We argue that the abrupt temperature drop of approximately 0.3 degrees C in 1945 is the apparent result of uncorrected instrumental biases in the sea surface temperature record. Corrections for the discontinuity are expected to alter the character of mid-twentieth century temperature variability but not estimates of the century-long trend in global-mean temperatures.     

Potent ulcerogenic actions of platelet-activating factor on the stomach

Platelet-activating factor (PAF) is an endogenous phospholipid which has been implicated as a mediator of allergic and inflammatory processes. It is synthesized and released by neutrophils, platelets, macrophages, monocytes, basophils and endothelial cells, and is a potent platelet-aggregating agent, a vasodilator, increases vascular permeability, stimulates neutrophil aggregation and degranulation and induces release of lysosomal enzymes. A role for PAF in the hypotension associated with endotoxin shock and in necrotizing enterocolitis has recently been suggested. As there is an association between septic shock and acute gastric damage, we propose that PAF is an endogenous mediator of ulceration in the stomach. Indeed, as reported here, intravenous (i.v.) infusion of PAF to rats, at doses of 20-200 pmol per kg per min, resulted in the formation of extensive haemorrhagic erosions in the gastric mucosa. The ulcerogenic actions of PAF are not attributable solely to its hypotensive actions and were not mediated via effects on platelets or cyclooxygenase products, nor via histamine H1, H2 or alpha-adrenergic receptors. PAF is the most potent gastric ulcerogen yet described and its endogenous release may underlie or contribute to certain forms of gastric ulceration.     

Acetylcholine receptor-aggregating factor is similar to molecules concentrated at neuromuscular junctions

The basal lamina in the synaptic cleft of the vertebrate skeletal neuromuscular junction contains molecules that direct the formation of synaptic specializations in regenerating axons and muscle fibres. We have undertaken a series of experiments aimed at identifying and characterizing the molecules responsible for the formation of one of these specializations, the aggregates of acetylcholine receptors (AChRs) in the muscle fibre plasma membrane. We began by preparing an insoluble, basal lamina-containing fraction from Torpedo californica electric organ, a tissue which has a far higher concentration of cholinergic synapses than muscle, and showing that this fraction caused AChRs on cultured chick myotubes to aggregate. A critical step is learning whether or not the electric organ factor is similar to the receptor-aggregating molecule in the basal lamina at the neuromuscular junction. The importance of this problem is emphasized by reports that clearly non-physiological agents, such as positively charged latex beads, can cause AChR aggregation on cultured muscle cells. We have already shown that Torpedo muscle contains an AChR-aggregating factor similar to that of electric organ, although in much lower amounts. Here we demonstrate, using monoclonal antibodies, that the AChR-aggregating factor in our extracts of electric organ is, in fact, antigenically related to molecules concentrated in the synaptic cleft at the neuromuscular junction.     

高性能Nd－Fe－B永磁合金

研究了干磨和湿磨，烧结和后烧工艺对磁体性能及氧含量的影响．磁体的氧含量主要来源于制粉阶段．干磨工艺磁体氧含量比湿磨磁体氧含量少一半多．合理的烧结与后烧工艺对磁体氧含量影响不大．合金锭中α－Ｆｅ的减少可改善磁体性能．Ｎｄ１４．５Ｆｅ７９Ｂ６．５磁体性能为ｉＨｃ＝６９６ｋＡ／ｍ，Ｂｒ＝１．３９Ｔ，（ＢＨ）ｍａｘ＝３６８ｋＪ／ｍ３．     

Functional genomics reveals genes involved in protein secretion and Golgi organization

Yeast genetics and in vitro biochemical analysis have identified numerous genes involved in protein secretion. As compared with yeast, however, the metazoan secretory pathway is more complex and many mechanisms that regulate organization of the Golgi apparatus remain poorly characterized. We performed a genome-wide RNA-mediated interference screen in a Drosophila cell line to identify genes required for constitutive protein secretion. We then classified the genes on the basis of the effect of their depletion on organization of the Golgi membranes. Here we show that depletion of class A genes redistributes Golgi membranes into the endoplasmic reticulum, depletion of class B genes leads to Golgi fragmentation, depletion of class C genes leads to aggregation of Golgi membranes, and depletion of class D genes causes no obvious change. Of the 20 new gene products characterized so far, several localize to the Golgi membranes and the endoplasmic reticulum.