A Fixed Algorithm of Ambiguity among the Network RTK Reference Stations

In the face of a complex observation environment, the solution of the reference station of the ambiguity of network real-time kinematic (RTK) will be affected. The joint solution of multiple systems makes the ambiguity dimension increase steeply, which makes it difficult to estimate all the ambiguity. In addition, when receiving satellite observation signals in the environment with many occlusions, the received satellite observation values are prone to gross errors, resulting in obvious deviations in the solution. In this paper, a new network RTK fixation algorithm for partial ambiguity among the reference stations is proposed. It first estimates the floating-point ambiguity using the robust extended Kalman filtering (EKF) technique based on mean estimation, then finds the optimal ambiguity subset by the optimized partial ambiguity solving method. Finally, fixing the floating-point solution by the least-squares ambiguity decorrelation adjustment (LAMBDA) algorithm and the joint test of ratio (R-ratio) and bootstrapping success rate index solver. The experimental results indicate that the new method can significantly improve the fixation rate of ambiguity among network RTK reference stations and thus effectively improve the reliability of positioning results.

Mechanical Stress Effects on 550 °C Hot Corrosion Propagation Rates in Precipitation Hardened Ni-Base Superalloys: CMSX-4, CM247LC DS and IN6203DS

Combinations of temperature, stress and hot corrosion may cause environmentally-assisted cracking in precipitation-hardened Ni-base superalloys, which is little understood. This research aims to increase current understanding by investigating the effects of mechanical stress on the hot corrosion propagation rate during corrosion-fatigue testing of CMSX-4, CM247LC DS and IN6203DS. The parameters used during the tests included a high R-ratio, high frequency, and a temperature of 550 °C. The results showed CMSX-4 experienced a predictable increase in the hot corrosion rate, CM247LC DS also experienced increased rates, but no obvious trend was apparent; whilst IN6203DS showed no evidence of an increased rate. These different behaviours appear to be a result of an interaction between the mechanical stress and microstructural features, which include gamma-prime volume fractions in both the matrix and eutectic regions, along with the distribution of the eutectic structure. The different behaviours in the hot corrosion propagation rate subsequently affected the respective corrosion fatigue results, with both CMSX-4 and CM247LC DS experiencing fracture but with significantly more scatter involved in the CM247LC DS results. All IN6203DS corrosion-fatigue specimens completed the respective tests without fracture and showed no evidence of cracking. It, therefore, appears that precipitation hardened Ni-base superalloys, which are susceptible to environmentally-assisted cracking, also experience increased hot corrosion propagation rates.

Hematopoietic mosaic chromosomal alterations in the New England Centenarian Study

Mosaic chromosomal alterations (mCAs) are structural alterations that include deletions, duplications, or copy-neutral loss of heterozygosity. mCAs are reported to be associated with survival, age, cancer, and cardiovascular disease. Previous studies of mCAs in large population-based cohorts (UK Biobank, MGBB, BioBank Japan, and FinnGen) have demonstrated a steady increase of mCAs as people age. The distribution of mCAs in centenarians and their offspring is not well characterized. We applied MOsaic CHromosomal Alteration (MoChA) caller on 2298 genome-wide genotype samples of 1582 centenarians, 443 centenarians’ offspring, and 273 unrelated controls from the New England Centenarian Study (NECS). Integrating Log R ratio and B-allele frequency (BAF) intensities with genotype phase information, MoChA employs a Hidden Markov Model to detect mCA-induced deviations in allelic balance at heterozygous sites consistent with genotype phase in the DNA microarray data. We analyzed mCAs spanning over 100 k base pairs, with an estimated cell fraction less than 50%, within samples with genome-wide BAF phase concordance across phased heterozygous sites less than 0.51, and with LOD score of more than 10 for the model based on BAF and genotype phase. Our analysis showed that somatic mCAs increase with older age up to approximately 102 years, but the prevalence of the subjects with mCAs tend to decrease after that age, thus suggesting that accumulation of mCAs is less prevalent in long-lived individuals. We also used Poisson regression to show that centenarians and their offspring tend to accumulate less mCA (RR = 0.63, p=0.045) compared to the controls.

White Blood Cell Scintigraphy for Fracture-Related Infection: Is Semiquantitative Analysis of Equivocal Scans Accurate?

Purpose: White blood cell (WBC) scintigraphy is considered the gold-standard nuclear imaging technique for diagnosing fracture-related infection (FRI). Correct interpretation of WBC scans in FRI is important since a false positive or false negative diagnosis has major consequences for the patient in terms of clinical decision-making. The European Association of Nuclear Medicine (EANM) guideline for correct analysis and interpretation of WBC scans recommends semiquantitative analysis of visually equivocal scans. Therefore, this study aims to assess the diagnostic accuracy of semiquantitative analysis of visually equivocal WBC scans for diagnosing FRI. Methods: A retrospective single-center study was performed in consecutive patients who received WBC scintigraphy in the diagnostic work-up for FRI between February 2012 and January 2017. All the visually equivocal scans were analysed using semiquantitative analysis by comparing leukocyte uptake in the manually selected suspected infection focus with the contralateral bone marrow (L/R ratio). Cut-off points for a ‘positive’ scan result of >0%, >10% and >20% leukocyte increase between the early and late scans were used in separate analyses. The discriminative ability was quantified by calculating the sensitivity, specificity and diagnostic accuracy. Results: In total, 153 WBC scans were eligible for inclusion. After visual assessment of all the scans, 28 visually equivocal scans were included. Dichotomization of the ratios using the cut-off of >0% resulted in a sensitivity of 30%, a specificity of 45% and a diagnostic accuracy of 40%. The >10% cut-off point resulted in a sensitivity of 18%, a specificity of 82% and a diagnostic accuracy of 66%. The >20% cut-off point resulted in a sensitivity of 0%, a specificity of 89% and a diagnostic accuracy of 67%. Conclusion: Semiquantitative analysis of visually equivocal WBC scans is insufficient for correctly diagnosing FRI.

Integer Ambiguity Fixation Based on SC-PAR Algorithm

In terms of quality control of ambiguity estimation, the common partial ambiguity fixation algorithm is improved, and the SC-PAR (Single frequency Combined Partial Ambiguity Resolution) algorithm is proposed. After the algorithm fails to fix the full ambiguity, it filters the ambiguity subset step by step according to the number of continuous satellite lock epochs, satellite elevation angle, satellite signal-to-noise ratio, geometric precision factor, ambiguity variance and ambiguity precision attenuation factor, and searches Optimal ambiguity subset. According to the R-ratio value and the success rate index, the search results are jointly tested, and the remaining subsets are corrected with the subsets that pass the test. The results show that compared with the FAR and conventional PAR algorithms, the fixed rate of the SC-PAR algorithm is increased by 65.01% and 27.97%, respectively, and the accuracy is also significantly improved.

Improving the growth of cempaka (Elmerillia ovalis) seedlings to accelerate ex situ plantation

Cempaka tree (Elmerillia ovalis), best known as a multipurpose tree species, is mostly used for the building of luxurious traditional houses of the Toraja and Minahasa Tribe as well as for religious sculptures. Due to the specific qualifications, the cempaka wood demands gradually increase, while the populations in nature drastically decrease. On the other hand, early seedling growth encounters many obstacles such as recalcitrant seeds, slow growth, and sensitivity to leaf disease. This study aimed to improve the quality of the seedling prepared for a higher survival rate when planted in the field. This research was conducted at the nursery of the Bogor Forest Research and Development Centre, Indonesia. The factorial experiment was conducted in a completely randomized design, consisting of two factors: wood vinegar as a growth stimulant and media composition, in three replications. The stimulant factor consisted of two levels: the addition of wood vinegar (1.5 %) and (control), and the media composition factor consisted of four levels: (a) soil 100%, (b) soil: cocopeat rice husks (6: 3: 1), (c) soil: rice husks (1:1), and (d) soil: manure (2:1). The observed parameters were seedling height, diameter, root/shoot ratio, seedling quality index (SQI). The best growth of cempaka seedlings resulted in treatments of wood vinegar in combination with soil media mixed with manure. Seedlings in this treatment height 58.93 cm, 6.8 mm diameter, S/R ratio 3.61, and 1.26 SQI, respectively, better than the others. The best treatment also gives the 12 months seedlings absence of leaf disease.

About Strong Dependence of the Complexity of Analysis of the Random 3-CNF Formulas on the Ratio of Number of Clauses to the Number of Variables

The results of a computational experiment on the assessment of the complexity of proving the unsatisfiability of random 3-CNF logical formulas are presented. The dependence of the complexity of this proving on the R-ratio of the number of clauses to the number of variables is demonstrated. The computational experiment was carried out for the range of the N-number of variables from 256 to 512. An exponential dependence of the median complexity of proving the unsatisfiability of formulas on the number of variables was revealed for each of R value: 4.3, 4.6, 5.0, 5.5, 6.0. A formula is constructed that approximates the results of the experiment. According to this formula the exponential component of the median complexity of the analysis of random 3-CNF is estimated as 2 to the power N / (8.4R-17.8).

Productivitatea fitoplanctonului fluviului Nistru și lacului de acumulare Dubăsari în condițiile impactului factorilor naturali și antropici

The article presents the results on the study of productivity of phytoplankton and destruction of organic matter in the Dniester River and Dubasari reservoir in 2020. The values of primary production in Dniester River varied during the vegetation period within the limits of 0.81-3.79 gO2/m-2 24h, and of the destruction of organic substances between 3.9-45.12 gO2/m-2 24h. In the Dubasari reservoir, the primary production of phytoplankton was significantly influenced by the hydrochemical and hydrobiological state of the waters from the middle sector of the Dniester River and varied within 0.572.82 gO2/m-2 24h. The values of destruction of organic substances exceeded the values of primary production and registering values between 2.1623.66 gO2/m-2 24h. The seasonal and spatial fluctuations of phytoplankton primary production values in Dniester river and Dubasari reservoir are followed by successions of phytoplankton structure, changes in nutrient concentrations and oscillations of water transparency values. The values of destruction of organic substances were higher than primary production values. The A/R ratio reflect a negative balance of formation of organic substances in Dniester River and Dubasari reservoir.

Internal Management Integration Policies and School-Community Relations in Tertiary Institutions in Rivers State

The study investigated internal management integration policies and school-community relations in Tertiary Institutions in Rivers State. Two research questions and two hypotheses guided the study. The study adopted correlational design. The population of the study is 1,071 respondents. A sample of 535 respondents was drawn using simple random sampling technique. Two sets of instruments were used for data collection. The first was titled: ‘Internal Management Integration Policies Questionnaire and the second was School-Community Relations Questionnaire. The reliability of 0.83 was determined with Cronbach Statistics. Out of 535 copies of questionnaire administered, 508 were properly filled and retrieved which represented 95% return rate. The Research questions were answered using Pearson Product Moment Correlation (PPMC) while Hypotheses were tested using r-ratio at 0.05 level of significance. The finding among others are that high positive relationship exists between award of contracts to community members and school-community relations and the null hypothesis of no significant relationship between award of contracts to community members and school-community relations is rejected. It was concluded that internal management integration policies have high positive relationship to school-community relations in Tertiary Institutions in Rivers State. It was recommended among others that higher institutions’ administration should give full implementation to local content laws during the award of contracts in the school environment. Keywords: Internal, management, Integration, Policies, School-Community.