Raziskovanje udorov na kraških območjih z uporabo integriranih geofizikalnih metod: primer iz okrožja Conghua, mesta Guangzhou, Kitajska

Integrated geophysical methods were used to investigate the geological conditions of karst collapses in Aotou, Conghua District, Guangzhou City. Based on audio frequency magnetotelluric (AMT) soundings, high-density electric signals and microtremors, a series of features, including the soil structure and thickness, faults, and hidden karst, were detected from shallow to deep subsurface regions in three-dimensional (3-D) space. These were then compared with geologic and drilling data. The measurements of micro-vibrations and high-density electric signals revealed that the strata in the collapsed area consists of clay and medium-grain sand, which is approximately 8–15 m thick and arranged as a multiple-element structure. The AMT soundings uncovered a hidden structure in the subsurface, which lies at the core of a syncline and adjacent to a contact zone between soluble limestone and non-soluble granite. Combined with the geologic data, the survey using the high-density electric method also showed that the study area hosts the Shidengzi Formation from the Datang Stage of the lower Carboniferous, which contain carbonaceous micrite and dolomitic limestone, locally intercalated with thin quartz siltstone, with well-developed karst. Collectively, the soil structure, hidden structure in the subsurface, and karst development provide the primary conditions for collapses. The main triggering factors for the karst collapses are seasonal variations in groundwater levels and excessive groundwater withdrawals. These results can provide guidance for the selection and application of geophysical methods for the examination of this issue in other areas with similar geology.Pri raziskovanju geoloških razmer za pojav udorov na območju krasa v Aotouju, okrožju Conghua, mesta Guangzhou so bile uporabljene integrirane geofizikalne metode. Z uporabo avdiofrekvenčnih magnetno teluričnih (AMT) sondiranj, visokofrekvenčnih električnih signalov in mikrotremorjev smo zaznali razne elemente v podzemlju, kot so debelina in struktura prsti, prelomi in nepoznani podzemni prostori. Izsledki so bili primerjani s podatki geoloških kartiranj in napravljenih vrtin. Meritve mikrovibracij in električnih signalov so razkrile, da so formacije na območju udorov sestavljene iz gline in srednje zrnatega peska, v skupni debelini približno 8‒15 m. Magnetno telurično sondiranje je pod površjem razkrilo neznano strukturo, ki leži na jedru sinklinale ob stiku med topnim apnencem in netopnim granitom. Skupaj z geološkimi podatki je metoda z električnimi signali pokazala, da področje študije zajema formacijo Shidengzi, stopnje Datang iz spodnjega Karbona, ki vsebuje mikritni in dolomitni apnenec, ki se lokalno izmenjuje s tankimi plastmi kremenovega meljevca. Na tem območju je nastal dobro razviti kras. Ugodna sestava prsti, neznane strukture pod površjem in zakrasevanje zagotavljajo dobre razmere za nastanek udorov. Glavni dejavniki udora kraških območij so sezonska nihanja nivojev podzemne vode in čezmerna črpanja podtalnice. Pridobljeni izsledki zagotavljajo smernice za izbor in uporabo ustreznih geofizikalnih metod za raziskovanje teh težav v drugih regijah s podobno geologijo

Present Situation Research on Axial Flow Displacement Theory During Cementing

It is well known that displacing drilling fluid effectively is the premise to obtain good cementing quality. During cementing axial flow is the major way to displace annular drilling fluid. So we put emphasis on the research of axial flow displacement theory. At present axial flow displacement theory mainly focuses on three aspects: displacement theory study based on wall shear stress; displacement theory study based on the numerical simulation technique for the displacement interface stability; displacement theory study based on laboratory experiments. In this paper, we analyzes the present research situation and their respective advantages and defects of the above mentioned three aspects in displacement theory. We put forward that infinitesimal mechanical analysis for displacement interface and numerical simulation technology for the interface stability should combine organically. In order to achieve good cementing effect, we should stress on the research and measurement of profile displacement efficiency and put the interface moving steadily as a prerequisite. As a result, our research can lay a fundamental the future development of axial flow displacement theory.Key words: Axial flow; Displacement theory; Wall shear stress; Interface stability; Displacement efficienc

LightGrad: Lightweight Diffusion Probabilistic Model for Text-to-Speech

Recent advances in neural text-to-speech (TTS) models bring thousands of TTS applications into daily life, where models are deployed in cloud to provide services for customs. Among these models are diffusion probabilistic models (DPMs), which can be stably trained and are more parameter-efficient compared with other generative models. As transmitting data between customs and the cloud introduces high latency and the risk of exposing private data, deploying TTS models on edge devices is preferred. When implementing DPMs onto edge devices, there are two practical problems. First, current DPMs are not lightweight enough for resource-constrained devices. Second, DPMs require many denoising steps in inference, which increases latency. In this work, we present LightGrad, a lightweight DPM for TTS. LightGrad is equipped with a lightweight U-Net diffusion decoder and a training-free fast sampling technique, reducing both model parameters and inference latency. Streaming inference is also implemented in LightGrad to reduce latency further. Compared with Grad-TTS, LightGrad achieves 62.2% reduction in paramters, 65.7% reduction in latency, while preserving comparable speech quality on both Chinese Mandarin and English in 4 denoising steps.Comment: Accepted by ICASSP 202

Use of redundant exclusion PCR to identify a novel Bacillus thuringiensis Cry8 toxin gene from pooled genomic DNA

With the aim of optimizing the cloning of novel genes from a genomic pool containing many previously identified, homologous, genes we designed a redundant exclusion PCR technique. In RE-PCR a pair of generic amplification primers are combined with additional primers that are designed to specifically bind to redundant, unwanted genes that are a subset of those copied by the amplification primers. During RE-PCR the specific primer blocks amplification of the full length redundant gene. Using this method we managed to clone a number of cry8 or cry9 toxin genes from a pool of Bacillus thuringiensis genomic DNA while excluding amplicons for cry9Da, cry9Ea and cry9Eb. The method proved very efficient at increasing the number of rare genes in the resulting library. One such rare, and novel, cry8-like gene was expressed and the encoded toxin was shown to be toxic to Anomola corpulenta

Diversity and soil chemical properties jointly explained the basal area in karst forest

IntroductionPlant diversity and soil chemical properties are important factors affecting the plant growth. We sought to compare the explanatory rates of diversity and soil chemical properties in explaining the variation of basal area in karst forests, and also sought to compare the relative importance of the niche complementarity and mass ratio hypotheses.MethodsOn the basis of linear regression and structural equation modelling, we examined the correlation between the basal area of plant communities and species diversity, functional diversity, phylogenetic diversity, the community-weighted mean (CWM) of traits, and soil chemical properties, using data obtained from 35 monitoring plots in southwest China.ResultsSpecies, functional, and phylogenetic diversities were all significantly correlated with the basal area of the plant community, among the indices of which, Faith’s phylogenetic diversity was found to have the greatest explanatory power for basal area. These plant diversity indices can better explain the variation in basal area than the CWM of traits, suggesting the niche complementarity hypothesis is more applicable than the mass ratio hypothesis. Moreover, soil chemical properties also have an equal important impact. Different chemical properties were found to show significant positive correlations with basal area, and their total effects on basal area were shown to be greater than the CWM of traits.DiscussionAttention should be paid to diversity and soil chemical properties. This study provides theoretical guidance for understanding biodiversity maintenance mechanisms and protecting karst forests

A natural hybrid of a Bacillus thuringiensis Cry2A toxin implicates Domain I in specificity determination

A PCR-RFLP method was used to identify cry2A toxin genes in a collection of 300 strains of Bacillus thuringiensis. From 81 genes identified, the vast majority appeared to be cry2Aa or cry2Ab, however three showed a different pattern and were subsequently cloned and sequenced. The gene cloned from strain HD395 was named cry2Ba2. Since the proteins encoded by the genes cloned from LS5115-3 and DS415 shared >95% sequence identity with existing toxins their genes were named cry2Aa17 and cry2Ab29 respectively by the toxin nomenclature committee. Despite this overall similarity these two toxins resembled natural hybrids, with Cry2Ab29 resembling Cry2Ab for the majority of the protein but then showing identity to Cry2Aa for the last 66 amino acids. For Cry2Aa17, Domains II and III most closely resembled Cry2Aa (99% identity) whilst Domain I was identical to that of Cry2Ab. The toxicity of the recombinant toxins was tested against Aedes aegypti and Spodoptera exigua, and it was found that the toxicity profile of Cry2Aa17 more closely matched the profile of Cry2Ab than that of Cry2Aa, thus implicating Domain I in specificity determination. This association of Domain I with toxicity was confirmed when hybrids were made between Cry2Aa and Cry2Ab

Spatial Patterns and Drivers of Microbial Taxa in a Karst Broadleaf Forest

Spatial patterns and drivers of soil microbial communities have not yet been well documented. Here, we used geostatistical modeling and Illumina sequencing of 16S rRNA genes to explore how the main microbial taxa at the phyla level are spatially distributed in a 25-ha karst broadleaf forest in southwest China. Proteobacteria, dominated by Alpha- and Deltaproteobacteria, was the most abundant phylum (34.51%) in the karst forest soils. Other dominating phyla were Actinobacteria (30.73%), and Acidobacteria (12.24%). Soil microbial taxa showed spatial dependence with an autocorrelation range of 44.4–883.0 m, most of them within the scope of the study plots (500 m). An increasing trend was observed for Alphaproteobacteria, Deltaproteobacteria, and Chloroflexi from north to south in the study area, but an opposite trend for Actinobacteria, Acidobacteira, and Firmicutes was observed. Thaumarchaeota, Bacteroidetes, Gemmatimonadetes, and Verrucomicrobia had patchy patterns, Nitrospirae had a unimodal pattern, and Latescibacteria had an intermittent pattern with low and high value strips. Location, soil total phosphorus, elevation, and plant density were significantly correlated with main soil bacterial taxa in the karst forest. Moreover, the total variation in soil microbial communities better explained by spatial factors than environmental variables. Furthermore, a large part of variation (76.8%) was unexplained in the study. Therefore, our results suggested that dispersal limitation was the primary driver of spatial pattern of soil microbial taxa in broadleaved forest in karst areas, and other environmental variables (i.e., soil porosity and temperature) should be taken into consideration

Rice Protein Extracted by Different Methods Affects Cholesterol Metabolism in Rats Due to Its Lower Digestibility

To elucidate whether the digestibility is responsible for the hypocholesterolemic action of rice protein, the effects of rice proteins extracted by alkali (RP-A) and α-amylase (RP-E) on cholesterol metabolism were investigated in 7-week-old male Wistar rats fed cholesterol-free diets for 3 weeks. The in vitro and in vivo digestibility was significantly reduced by RP-A and RP-E as compared to casein (CAS). The digestibility was lower in RP-E than that of RP-A. Compared with CAS, the significant cholesterol-lowering effects were observed in rats fed by RP-A and RP-E. Fecal excretion of bile acids was significantly stimulated by RP-E, but not by RP-A. The apparent cholesterol absorption was more effectively inhibited by RP-E than RP-A because more fecal neutral sterols were excreted in rats fed RP-E. There was a significant correlation between protein digestibility and cholesterol absorption (r = 0.8662, P < 0.01), resulting in a significant correlation between protein digestibility and plasma cholesterol level (r = 0.7357, P < 0.01) in this study. The present study demonstrates that the digestibility of rice protein affected by extraction method plays a major role in the modulation of cholesterol metabolism. Results suggest that the hypocholesterolemic action induced by rice protein with lower digestibility primarily contribute to the inhibition of cholesterol absorption