Basic mathematical function libraries for scientific computation

Ada packages implementing selected mathematical functions for the support of scientific and engineering applications were written. The packages provide the Ada programmer with the mathematical function support found in the languages Pascal and FORTRAN as well as an extended precision arithmetic and a complete complex arithmetic. The algorithms used are fully described and analyzed. Implementation assumes that the Ada type FLOAT objects fully conform to the IEEE 754-1985 standard for single binary floating-point arithmetic, and that INTEGER objects are 32-bit entities. Codes for the Ada packages are included as appendixes

A discrete Fourier transform for virtual memory machines

An algebraic theory of the Discrete Fourier Transform is developed in great detail. Examination of the details of the theory leads to a computationally efficient fast Fourier transform for the use on computers with virtual memory. Such an algorithm is of great use on modern desktop machines. A FORTRAN coded version of the algorithm is given for the case when the sequence of numbers to be transformed is a power of two

Acoustic resonances and sound scattering by a shear layer

The energy reflection coefficient is evaluated numerically for plane waves incident on a plane shear layer having a linear velocity profile. The shear layer is found to exhibit no resonances and no Brewster angles. The behavior of the reflection coefficient depends crucially on the parameter tau, a nondimensional measure of the disturbance Strouhal number with respect to the disturbance Mach number in the mean flow direction. For moderate values of tau, the amplified reflection regime degenerates into the total reflection one, whereas in the ordinary reflection regime the variation of the reflection coefficient with tau depends on whether or not the corresponding vortex sheet has a Brewster angle. The results indicate that caution should be exercised in uncritically modeling a finite thickness shear layer by a corresponding vortex sheet

Queuing theory models for computer networks

A set of simple queuing theory models which can model the average response of a network of computers to a given traffic load has been implemented using a spreadsheet. The impact of variations in traffic patterns and intensities, channel capacities, and message protocols can be assessed using them because of the lack of fine detail in the network traffic rates, traffic patterns, and the hardware used to implement the networks. A sample use of the models applied to a realistic problem is included in appendix A. Appendix B provides a glossary of terms used in this paper. This Ames Research Center computer communication network is an evolving network of local area networks (LANs) connected via gateways and high-speed backbone communication channels. Intelligent planning of expansion and improvement requires understanding the behavior of the individual LANs as well as the collection of networks as a whole

Intensity prediction model based on machine learning for regional earthquake early warning

Seismic intensity plays a crucial role in influencing the decision-making process of users utilizing earthquake early warning systems (EEWs) upon receiving warning information. Improving intensity warnings’ speed and accuracy is vital. We present a straightforward and dependable model for predicting intensity, which is based only on location and magnitude information. We use the catalog of intensity data from the Japan Meteorological Agency (JMA) released as a dataset, totaling 944,877 intensity instances. To address the issue of imbalanced dataset distribution, we employ the Synthetic Minority Over-Sampling Technique (SMOTE) as a means to improve this situation. Considering the distribution of high intensity data and the importance of features in the model, we construct and jointly apply intensity prediction models for magnitude below 5.7 and above 5.7, respectively. Further, we analyze the robustness of the model by adding random errors for magnitude and location information. We test the transfer capability of the proposed model with four earthquake events in China. Further, we use 466 seismic events (20,542 intensity instances) without published intensity data from the Kyoshin network (K-NET) as the application dataset. We simulate the phenomenon of underestimation of large earthquakes and overestimation of small earthquakes, which is used to analyze the possible application of the proposed model to EEWs. The findings indicate that the model achieves an accuracy of 97.77% when subjected to a magnitude error of 0.3 and a location error of 0.2°. Finally, we analyze the timeliness of the proposed model with a magnitude 7.4 event in 2022.The paper is supported by the National Natural Science Foundation of China 52278313, and Project to Attract Foreign Experts G2023133018L

Plant Glutathione Biosynthesis: Diversity in Biochemical Regulation and Reaction Products

In plants, exposure to temperature extremes, heavy metal-contaminated soils, drought, air pollutants, and pathogens results in the generation of reactive oxygen species that alter the intracellular redox environment, which in turn influences signaling pathways and cell fate. As part of their response to these stresses, plants produce glutathione. Glutathione acts as an anti-oxidant by quenching reactive oxygen species, and is involved in the ascorbate–glutathione cycle that eliminates damaging peroxides. Plants also use glutathione for the detoxification of xenobiotics, herbicides, air pollutants (sulfur dioxide and ozone), and toxic heavy metals. Two enzymes catalyze glutathione synthesis: glutamate–cysteine ligase, and glutathione synthetase. Glutathione is a ubiquitous protective compound in plants, but the structural and functional details of the proteins that synthesize it, as well as the potential biochemical mechanisms of their regulation, have only begun to be explored. As discussed here, the core reactions of glutathione synthesis are conserved across various organisms, but plants have diversified both the regulatory mechanisms that control its synthesis and the range of products derived from this pathway. Understanding the molecular basis of glutathione biosynthesis and its regulation will expand our knowledge of this component in the plant stress response network

Differential elevation of matrix metalloproteinase expression in women exposed to levonorgestrel-releasing intrauterine system for a short or prolonged period of time

peer reviewedBACKGROUND: The levonorgestrel-releasing intrauterine system (LNG-IUS) is an effective contraceptive and has many non-contraceptive health benefits. However, it is commonly associated with irregular endometrial bleeding. Metalloproteinases contribute to extracellular matrix (ECM) remodelling and regulate bleeding during the menstrual cycle. Enhanced metalloproteinase expression participates in the pathogenesis of breakthrough bleeding. Thus the objective of this study was to compare matrix metalloproteinase (MMP) expression in endometrium during luteal phase and in short-term (1 month) and long-term (> or =6 months) LNG-IUS users. METHODS: MMP expression was analysed by semi-quantitative RT-PCR and immunohistochemistry. Gelatinase activity was determined by gelatin zymography. RESULTS: MMP-1, -2, -3, -7, -9 and -12 mRNAs levels were increased, whereas that of MMP-26 was decreased in the endometrium of LNG-IUS users. MMP-1, -2, -3, -7 and -9 were localized by immunohistochemistry in all biopsies in the short-term group but in only 0-27% in the control group. The incidence of positive immunostaining for MMP-2 and -3 decreased significantly in the long-term compared with short-term LNG-IUS users. MMP-26 was localized in all biopsies from the control group but in only 14 and 25% from the short- and long-term LNG-IUS groups, respectively. In both LNG groups, the numbers of macrophages (the major source of MMP-12) was increased. CONCLUSIONS: MMP-1, active MMP-2, MMP-3, MMP-7, MMP-9 and MMP-12 are more prevalent in the short-term LNG-IUS group, suggesting their important contribution to ECM breakdown and transient bleeding. The decrease in the percentage of women expressing MMP-2 and -3 might contribute to the decreased occurrence of unwanted spotting and bleeding in long-term LNG-IUS users

Thermal and radio-oxidation of epoxy coatings

Degradation induced by thermal (50-110 °C) and radio-oxidation of low T g epoxy-amine networks has been studied. It has been found that oxidation leads mainly to amide groups formation at the vicinity of tertiary amines whatever ageing conditions (thermal or radio-oxidation at 200 Gy h -1 ). In addition, some species as acids, peracids or formates have been revealed indicating a chain scission process. Physical modifications as T g decrease and soluble fraction increase due to chain scission process, have been correlated with chemical modifications

Radio emission and particle acceleration in plerionic supernova remnants

Plerionic supernova remnants exhibit radio emission with remarkably flat spectral indices ranging from $\alpha=0.0$ to $\alpha=-0.3$. The origin of very hard particle energy distributions still awaits an explanation, since shock waves generate particle distributions with synchrotron spectra characterized by $\alpha\le-0.5$. Acceleration of high energy leptons in magnetohydrodynamic turbulence instead may be responsible for the observed hard spectra. This process is studied by means of relativistic test particle calculations using electromagnetic fields produced by three-dimensional simulations of resistive magnetohydrodynamical turbulence. The particles receive power-law energy spectra $N(\gamma)\propto \gamma^{-s}$ with $s$ ranging from 1.2 to 1.6, i.e. particle spectra that are required to explain the radio emission of plerions.Comment: 8 pages, 7 Figures, to be published in A&