A global evaluation of IMERG precipitation occurrence using SMAP detected soil moisture change

A globally consistent ground validation method for remotely sensed precipitation products is crucial for building confidence in these products. This study develops a new methodology to validate the IMERG precipitation products through the use of SMAP soil moisture changes as a proxy for precipitation occurrence. Using a standard 2x2 contingency table method, preliminary results provide confidence in SMAP’s ability to be utilized as a validation tool for IMERG as results are comparable to previous validation studies. However, the method allows for an overestimate of false alarm frequency due to light precipitation events that can evaporate before the subsequent SMAP overpass and changes in overpass-to-overpass SMAP soil moisture that are within the range of SMAP uncertainty. To counter these issues, a 3x3 contingency table is used to reduce noise and extract more signal from the detection method. Through the use of this novel approach, the validation method produces a global mean POD of 0.64 and global mean FAR of 0.40, the first global-scale ground validation skill scores for the IMERG products. Advancing the method to validate precipitation quantity and the development of a real-time validation for the IMERG Early product are the crucial next developments.

Intracranial bruit: Charles Warlow’s challenge revisited

Over 20 years ago, Charles Warlow, the founding editor of Practical Neurology, offered a copy of his stroke textbook to anyone diagnosing an intracranial arteriovenous malformation by auscultation of the skull alone. This article examines the possible diagnostic value of intracranial bruit in terms of the 2×2 contingency table for diagnostic tests and recounts an historical case.

Stability of Dependencies of Contingent Subgroups with Merged Groups: Vaccination Case Study

The answers to extreme phenomena both in nature and in business sectors are the constructions of the distribution of random variables with extreme values. Another area in which appropriate theoretical research is conducted regarding the influence of suppressor (third) variables in categorical data. When examining dependencies in PivotTables, we often find it necessary to merge data into larger sets (e.g., due to a greater number of theoretical frequencies lower than their critical value). A phenomenon many exist wherein the partial relation is stronger than the zero relation. For example, in such a combination, instability may occur, which indicates contingent subgroups with the merged group. The dependence of dependencies is practically manifested because the data of contingent subgroups indicate inconsistent (inverted) conclusions compared to the associated group. For this reason, this paper aimed to find the critical ratios of partial probabilities in the contingency table of subgroups of the original variables, and to determine the conditions of result consistency and contingency stability, including the proof. For practical use and for the ease of repeating the proposed procedure, the solution is based on a case study that compares the effectiveness of vaccination.

Identification of Inhomogeneous Temperature on Stainless Steel using Statistical Analysis

Corrosion in stainless steel, abbreviated as SS, is still an exciting topic to study. Even though SS is a corrosion resistance material, this property will be degraded when exposed to high temperatures for a long time because of σ phase, such as a Fe-Cr compound, formation. The presence of this phase can be observed using a special chemical etchant solution that will give five specific colours to this phase: light brown, dark brown, bluish brown, light blue, and dark blue. In this study, the specimen sample is from ASTM A297. Furthermore, the metallography process is carried out to obtain microstructure images that describe the σ phase. Here, two grains were taken as objects to discretize with one of them was around the specimen sample center and the other was close to the boundary with the environment. The discretization resulted in a 2 x 5 frequency table, called contingency table, that is analysed by the independence χ2-test. The contingency table is also represented geometrically in cartesian. The study shows that two grains were not independent. The grain which was around the specimen sample center contained many σ phases dominated by light blue colour (43%). In other words, the prolonged heating did not give homogeneous corrosion level.

Evaluation of the Different Methods to Detect Salmonella in Poultry Feces Samples

Salmonella is one of the most common causes of food-borne outbreaks and infection worldwide. The gold standard detection method of Salmonella is cultivation. With time-consuming cultivation, there is a need to investigate rapid and accurate processes. The study evaluated different approaches to detect Salmonella in poultry feces samples. Poultry farm feces samples from 21 cities in Iran were collected from January 2016 to December 2019. Microbiological cultures, serological assays, and multiplex PCR (m-PCR) were used to detect and characterize Salmonella spp. isolates. Serological assays and m-PCR were used to determine the serogroups A, B, C1, C2, D1, E, H, and FliC. The m-PCR was used for the detection of seven Salmonella serovars and a chi-square test was performed to compare the discriminatory power of the methods. Out of 2300 poultry feces samples, 173 (7.5%) and 166 (7.2%) samples were detected as Salmonella spp. by cultivation and m-PCR, respectively. The sensitivity of the molecular method was equal to cultivation at 0.96 (CI = 95%). Assessment of H antigenic subgroups showed the same for both m-PCR and serological tests. Therefore, the matching rate of the two methods for detection of all H antigenic subgroups was 100%. Thus, the relationship between the results obtained from both methods was significant in the contingency table test (P < 0.01). The PCR-based approach confirmed the detection of Salmonella in a shorter period (24–36 hours) compared to the conventional microbiological approach (3–8 days).