Thiên tai là gì? Các công bố khoa học về Thiên tai

Root herbivores can indirectly affect aboveground herbivores by altering the food quality of the plant. However, it is largely unknown whether plant genotypes differ in their response to root herbivores, leading to variable defensive phenotypes. In this study, we investigated whether root-feeding insect larvae (Agriotes sp. larvae, wireworms) induce different responses in Plantago lanceolata plants from lines selected for low and high levels of iridoid glycosides (IG). In the absence of wireworms, plants of the “high-IG line” contained approximately twofold higher levels of total IG and threefold higher levels of catalpol (one of the IG) in leaves than plants from the “low-IG line,” whereas both lines had similar levels of IG in roots. In response to wireworms, roots of plants from both lines showed increased concentrations of catalpol. Leaves of “low-IG line” plants increased catalpol concentrations in response to wireworms, whereas catalpol concentrations of leaves of “high-IG line” plants decreased. In contrast, glucose concentrations in roots of “low-IG” plants decreased, while they increased in “high-IG” plants after feeding by wireworms. The leaf volatile profile differed between the lines, but was not affected by root herbivores. In the field, leaf damage by herbivores was higher in wireworm-induced compared to noninduced “low-IG” plants and lower in wireworm-induced compared to noninduced “high-IG” plants, despite induction of catalpol in leaves of the “low-IG” plants and reduction in “high-IG” plants. This pattern might arise if damage is caused mainly by specialist herbivores for which catalpol may act as feeding stimulant rather than as deterrent. The present study documents for the first time that intraspecific variation in plant defense affects the outcome of plant-mediated interactions between root and shoot herbivores.

Stable carbon isotopes were used together with molecular markers to constrain genetic relationships between sandstone extracts and potential source rocks in the pre-Tertiary in the Huanghua Depression, North China. Comparison of the extracts from Permo-Carboniferous terrigenous mudstones and Ordovician marine carbonates indicated that their prominent differences are in stable carbon isotopes, molecular markers and thermal maturity. Although the extracts of the Mesozoic and Lower Permian Xiashihezi Formation sandstones have some similar isotopic characteristics, molecular markers data provide a good correlation between the Upper Jurassic-Lower Creta-ceous oils and the Upper Carboniferous Taiyuan Formation mudstones, and between the Lower Permian Xiashihezi Formation oils and the Lower Permian mudstones. The results showed that the Upper Jurassic-Lower Cretaceous sandstone oils were derived chiefly from the Upper Carboniferous Taiyuan Formation terrigenous mudstones and that the Lower Permian Xiashihezi Formation oils were sourced from the Lower Permian Shanxi Formation and Xiashihezi Formation terrigenous mudstones.

Computational models of emotions have been thriving and increasingly popular since the 1990s. Such models used to be concerned with the emotions of individual agents when they interact with other agents. Out of the array of models for the emotions, we are going to devote special attention to the approach in Adamatzky’s Dynamics of Crowd-Minds. The reason it stands out, is that it considers the crowd, rather than the individual agent. It fits in computational intelligence. It works by mathematical simulation on a crowd of simple artificial agents: by letting the computer program run, the agents evolve, and crowd behaviour emerges. Adamatzky’s purpose is to give an account of the emergence of allegedly “irrational” behaviour. This is not without problem, as the irrational to one person may seem entirely rational to another, and this in turn is an insight that, in the history of crowd psychology, has affected indeed the competition among theories of crowd dynamics. Quite importantly, Adamatzky’s book argues for the transition from individual agencies to a crowd’s or a mob’s coalesced mind as so, and at any rate for coalesced crowd’s agency.

Circadian fluctuations in the activity of endogenous RNA polymerases were examined in the nuclei ofL v spinal ganglion neurocytes, spinal α-motoneurons, and in neurons of the sensorimotor and visual cortex of mice exposed to radiation in the zone of the Chernobyl power plant. The circadian organization of the functioning of the genetic apparatus of neurons in various compartments of the nervous system was altered in irradiated mice. A shift of the acrophases of nucleoplasmic and nucleolar labeling in the course of the 24-hour cycle was observed after a 40-day exposure under conditions of a high radioactive background. The degree of synchronization of the level of transcription of ribosomal and structural genes of the studied cell populations diminished. The mesors and amplitudes of circadian rhythms of chromatin matrix activity decreased. The status of the histone component of chromatin also changed in exposed animals.

We prove that, for an attractive potentialV(r) whose slope never changes sign, a necessary condition for the existence of bound states is that fdr |V(r) |1/2 π/2.

Peroxidase activity was determined in experimental compression-excoriation lesions and incision wounds of rat skin after different periods of vital time. The peroxidase enzyme was extracted from the tissues by homogenization in 0.5% cetyltrimethylammoniumbromide, and the enzyme activity was measured from the supernatant by o-dianisidine-H2O2 assay. In the blood of the rats a mean activity of approx. 5.26±1.11 U/g dry weight was observed. In the control specimens of the skin the activity was very low and generally below the detection limit of the methods used. In 30-min-old compression-excoriation lesions the mean peroxidase activity was 0.38±0.21 U/g dry weight. In lesions older than 30 min the activity started to increase rapidly. In 4-h-old compression-excoriation lesions it was 10 times higher than the 30-min level and was 40 times higher in 12-h-old lesions and 70–100 times higher in 1–3-day-old compression-excoriation lesions, respectively. In 30-min-old incision wounds the mean peroxidase activity was 0.65±0.37 U/g dry weight. The increase of the activity compared with the 30-min level was even faster in the incision wounds: in 4-h-old wounds the mean activity was 50 times higher, in 12-h-old wounds 200 times higher and in those of 1–5 days it was several hundreds of times higher. Compression-excoriation lesions made after death showed activity similar to the control specimens. Postmortem autolysis at +22°C resulted in a loss of the enzyme activity in 1-day-old compression-excoriation lesions so that after 3 days approx. 80% remained, and after 5 and 7 days approx. 40% was present. After 3 days of autolysis at +4°C, nearly 100% of the activity remained and approx. 90% was present after 5 and 7 days of autolysis. Increased peroxidase activity was also detectable in human vital excoriations in the specimens which were taken in autopsies several days postmortem.

In May 1918 Paul Ehrenfest received a monograph from Niels Bohr in which Bohr had used Ehrenfest’s adiabatic principle as an essential assumption for understanding atomic structure. Ehrenfest responded by inviting Bohr, whom he had never met, to give a talk at a meeting in Leiden in late April 1919, which Bohr accepted; he lived with Ehrenfest, his mathematician wife Tatyana, and their young family for two weeks. Albert Einstein was unable to attend this meeting, but in October 1919 he visited his old friend Ehrenfest and his family in Leiden, where Ehrenfest told him how much he had enjoyed and profited from Bohr’s visit. Einstein first met Bohr when Bohr gave a lecture in Berlin at the end of April 1920, and the two immediately proclaimed unbounded admiration for each other as physicists and as human beings. Ehrenfest hoped that he and they would meet at the Third Solvay Conference in Brussels in early April 1921, but his hope was unfulfilled. Einstein, the only physicist from Germany who was invited to it in this bitter postwar atmosphere, decided instead to accompany Chaim Weizmann on a trip to the United States to help raise money for the new Hebrew University in Jerusalem. Bohr became so overworked with the planning and construction of his new Institute for Theoretical Physics in Copenhagen that he could only draft the first part of his Solvay report and ask Ehrenfest to present it, which Ehrenfest agreed to do following the presentation of his own report. After recovering his strength, Bohr invited Ehrenfest to give a lecture in Copenhagen that fall, and Ehrenfest, battling his deep-seated self-doubts, spent three weeks in Copenhagen in December 1921 accompanied by his daughter Tanya and her future husband, the two Ehrenfests staying with the Bohrs in their apartment in Bohr’s new Institute for Theoretical Physics. Immediately after leaving Copenhagen, Ehrenfest wrote to Einstein, telling him once again that Bohr was a prodigious physicist, and again expressing the hope that he soon would see both of them in Leiden.

As centenarians are the most vulnerable social group among older adults, their quality of life (QoL) is of great significance for the realization of healthy aging and a harmonious society. The purpose of this cross-sectional study was to propose a multidimensional analysis of centenarians’ QoL to examine the factors associated with QoL. In the study, a factor analysis method, including exploratory factor analysis and confirmatory factor analysis, was used to uncover the latent structure of QoL and to monitor the dimension, reliability, and validity of the measurement scale. Structural equation model was performed to test the proposed hypotheses. Based on Lawton’s “the good life” theoretical framework, we constructed our QoL model with four dimensions: physical health, mental health, family and social relationships, and socioeconomic status. After the factor analysis, three main hypotheses were presented. The results of the final QoL model revealed that two hypotheses of the relationships between QoL and “physical health” and “socioeconomic status” were supported. This paper suggests that interventions related to improving functional health and living standard could enhance the QoL for centenarians.