Arch Height Index, Arch Rigidity Index and Arch Stiffness Values in a Symptomatic Population

BACKGROUND: Normative studies on the Arch Height Index (AHI), Arch Rigidity Index (ARI), and arch stiffness have primarily focused on healthy populations, with little consideration of pathology. The purpose of this study was to create a normative sample of the aforementioned measurements in a pathological sample and to identify relationships between arch structure measurements and pathology. METHODS: AHI was obtained bilaterally at 10% and 90% weightbearing conditions using the Arch Height Index Measurement System (AHIMS). ARI and arch stiffness were calculated using AHI measurements. Dependent t-tests compared right and left, dominant and non-dominant, and injured and non-injured limbs. Measurements of the dominant foot were compared between sexes using independent t-tests. Relationships between arch stiffness and age, sex, and AHI were examined using the coefficient of determination (R2). One-way ANOVAs were used to determine differences between arch structure measurements and number of pathologies or BMI. RESULTS: A total of 110 participants reported either one (n=55), two (n=38), or three or more (n=17) pathologies. Plantar fasciitis (n=31) and hallux valgus (n=28) were the most commonly reported primary concerns. AHI, ARI, and arch stiffness did not differ between limbs for any comparisons, nor between sexes. Between subgroups of BMI and number of pathologies, no differences exist in AHI or ARI; however, BMI was found to have an impact on AHI (10%WB) and arch stiffness (p<.05). Arch stiffness showed a weak relationship to AHI, where a higher AHI was associated with a stiffer arch (R2=0.06). CONCLUSIONS: Normative AHI, ARI and arch stiffness values were established in a pathological sample with a large incidence of plantar fasciitis and hallux valgus. Findings suggest relationships between arch stiffness and both BMI and arch height; however, few trends were noted in AHI and ARI. Determining relationships between arch structure and pathology is helpful for both clinicians and researchers.

Characterization of Hoek–Brown constant mi of quasi-isotropic intact rock using rigidity index approach

An accurate determination of Hoek–Brown constant mi is of great significance in the estimation of the failure criteria of brittle rock materials. So far, different approaches such as rigidity index method (R-index), uniaxial compressive strength-based method, and tensile strength-based method, and the combination of these two methods (combination based method) have been proposed to calculate the value of mi. This paper aims to thoroughly review the previously existing methods to calculate the value of mi and make comparison between the obtain results to propose the new material constants that provide the best fit with the experimental data. In order to fulfill this goal, a large number of data for different quasi-isotropic intact rock types from the literature were collected and statistically analyzed. Additionally, based on rock types, new material constants are introduced for igneous, sedimentary, and metamorphic rocks. The obtained results proves that for different rock groups (igneous, sedimentary, and metamorphic rocks), R-index method provides the best fit with the experimental data among the others, and it is also independent of rock type. Interestingly enough, there is significant differences in the predicted mi values using different methods, which is more probably due to the quantity and quality of data used in the statistical analysis.

Constitutional Rigidity Matters: A Veto Players Approach

Constitutional amendment rules have traditionally been considered the most important part of a constitution. Nevertheless, recent empirical analyses argue that constitutional amendment rules do not matter at all. This dispute is due to the misuse of independent and dependent variables and inappropriate methodology. Using the Veto Players approach to measure constitutional rigidity, this article proposes a new index covering ninety-four democratic countries. It starts by explaining the underlying logic of the veto players approach and describing the specific derivation of the rules for the construction of the rigidity index, which aggregates all institutional provisions in a logically consistent way. It then explains why the lack of constitutional rigidity is a necessary but not sufficient condition for significant constitutional amendments in democratic countries. Finally, the author creates a new dataset on the significance of constitutional amendments and estimates the appropriate (heteroskedastic) model, which corroborates the theoretical expectations and demonstrates that more significant amendments lead to a better fit.

Verification of Flange Rigidity Index for Standard Flanges Using Finite Element Analysis

A flange connection consists of the flange, gasket, bolts, and pipe. In a flange design stage, the flange rigidity index is checked to ensure the leak tightness of the flange connection. Technically, the flange rigidity index was theoretically derived by the function of flexure induced into the flange by both bolt tension and internal pressure. However, some of the factors used to calculate the flange rigidity index were determined by regression formulas. On the other hand, the rotation angle of the flange is also limited to determine the allowable bolt pre-tension. To better understand the flange rigidity index, flange rigidity index and flange rotation angle were compared. The flange rotation angle was calculated using Finite Element Analysis (FEA). For the evaluation model, NPS 3, 6, 12, 18, 24 for classes 150, 300, 600, 900, 1500 integral-type flanges were selected. Typical gasket seating and operating conditions were considered in this study. In gasket seating condition, the required minimum bolt load was applied. In operating condition, internal pressure and uniform temperature were simultaneously applied to the FEA model. From the analysis results, it was concluded that the specified flange rigidity indexes may underestimate the leak tightness for lower pressure and large flange types.

The Effect of Added Weight on Foot Anthropometry in Pregnant Women and Nulligravida Women

Background Foot anthropometry is altered by pregnancy. It is unknown if these changes are due to increased bodyweight and/or hormonal concentrations. The purpose of our study was to examine the effect of added weight on foot anthropometry in pregnancy. Methods Fifteen primigravid women and 13 nulliparous controls participated. Controls were matched to pregnant women based on self-reported pre-pregnancy weight. After informed consent, data were collected on pregnant participants in each trimester and post-partum. Foot length, width, arch index, arch height index, arch rigidity index, and arch drop were assessed. Subsequently, pregnant participants in their first two trimesters donned a weighted pack such that total weight difference from pre-pregnancy weight was 124N. Foot measurements were repeated. Third trimester participants were only measured without a pack as they were at full-pregnancy weight. In post-partum, bodyweight plus pack-weight equaled third trimester weight. For control participants, bodyweight plus pack-weight equaled third trimester weight of the pregnant participant to whom they were matched. A MANOVA was performed with the independent variables of trimester, weight condition, and leg. Tukey post-hoc analyses were performed when appropriate (α=0.05). Results Arch drop increased by 18% (p=0.007) and arch rigidity index decreased by 1% (p=0.001) while weighted across both pregnant and control groups. Increase in foot length and width and decrease in arch height index with added weight was only greater in pregnant participants compared to the control participants (p<0.05). Conclusions Adding weight produced changes in arch drop and arch rigidity index. Weight plus pregnancy was related to further alterations in anthropometry. Increased pregnancy hormone concentrations likely affect foot anthropometry in primigravid women.

Ecological Quality of Natural Waters from of Kharkiv Urban Springs

Purpose. Estimation of ecological safety of spring waters of the city of Kharkiv. Methods. Field research, atomic absorption spectrophotometry, analytical methods for studying water quality indicators. Results. Natural water samples were analyzed on the following parameters: pH, electrical potential, nitrate content, chlorides, ammonia, transparency, turbidity, and water hardness. The highest values of the content of nitrates, nitrites, as well as the level of alkalinity and rigidity were found in a sample from the Kholodnogorsk spring. In the water from the Zhukovsky spring the high content of chlorides is found, which is one and a half times higher than the concentration in water from other city springs. In the water from the Glyboky Yar spring the lowest mineralization of water was detected, and in the water from the Sarzhin Yar spring - the highest of the studied samples of water from the natural springs of Kharkiv. However, all identified pollutant concentrations except for the rigidity index is not dangerous for a person, because they are not exceeded by the MAC. The results of research on water samples from the Sarzhin Yar spring and from the spring in Yunost park (Kholodnogorsk source) in 2019, compared to the results of a similar study conducted in 2015. It was determined that in the water from the Sarzhin Yar spring the rigidity index increased 3.4 times, and in the sample from the spring in Yunost park (Kholodnogorsk spring) almost 6 times. Conclusions. It is determined that in the territory of the city of Kharkiv, water from the Zhukovskii spring in the Kyivskiy district is fully suitable for consumption, because its chemical composition is fully in line with the sanitary norms that apply to drinking spring waters. The value of the level of hardness of water in all samples, except Zhukovsky spring, indicate that the normative value exceeds 2-3 times. The rigidity of drinking water that exceeds the MAC may adversely affect human health. Therefore, the only ecologically safe, among the investigated, can be considered water from the Zhukovsky spring (Kievskiy district in Kharkiv). For other sources, it is recommended to modernize the water collection sites for the population, reconstruct the system of water supply for the supply of water from these sources, as well as to introduce additional stages of their treatment on the way to the consumer.