On the constraints violation in forward dynamics of multibody systems

It is known that the dynamic equations of motion for constrained mechanical multibody systems are frequently formulated using the Newton-Euler’s approach, which is augmented with the acceleration constraint equations. This formulation results in the establishment of a mixed set of partial differential and algebraic equations, which are solved in order to predict the dynamic behavior of general multibody systems. The classical resolution of the equations of motion is highly prone to constraints violation because the position and velocity constraint equations are not fulfilled. In this work, a general and comprehensive methodology to eliminate the constraints violation at the position and velocity levels is offered. The basic idea of the described approach is to add corrective terms to the position and velocity vectors with the intent to satisfy the corresponding kinematic constraint equations. These corrective terms are evaluated as function of the Moore-Penrose generalized inverse of the Jacobian matrix and of the kinematic constraint equations. The described methodology is embedded in the standard method to solve the equations of motion based on the technique of Lagrange multipliers. Finally, the effectiveness of the described methodology is demonstrated through the dynamic modeling and simulation of different planar and spatial multibody systems. The outcomes in terms of constraints violation at the position and velocity levels, conservation of the total energy and computational efficiency are analyzed and compared with those obtained with the standard Lagrange multipliers method, the Baumgarte stabilization method, the augmented Lagrangian formulation, the index-1 augmented Lagrangian and the coordinate partitioning method.The first author expresses his gratitude to the Portuguese Foundation for Science and Technology through the PhD grant (PD/BD/114154/2016). This work has been supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.info:eu-repo/semantics/publishedVersio

Tests of multiple molecular markers for the identification of Great Spotted and Syrian Woodpeckers and their hybrids

Great Spotted and Syrian Woodpeckers (Dendrocopos major and D. syriacus) are known to hybridize in nature; however, the extent of this phenomenon is not known due to difficulties in hybrid detection based on plumage analyses. Here, we tested five markers (one mitochondrial and four nuclear) and a set of six microsatellite loci for the identification of these two Woodpeckers and their hybrids. Sequencing of DNA from 26 individuals of both Woodpeckers from different parts of their ranges: one allopatric (D. major; Norway) and two sympatric (Poland and Bulgaria) showed that both species can be clearly separated based on all sequence markers. The highest number of fixed nucleotide sites were found in the mtDNA control region and intron 5 of the transforming growth factor. Analyses of microsatellite data distinguished the two species, but all loci showed a large number of common alleles and their utility in identifying hybrids is therefore doubtful. According to the DNA sequence analyses, 2 out of 18 specimens within the sympatric range in Poland were identified as possible hybrids, most probably paternal backcrosses. Moreover, both hybrids are from synantropic populations (settled in cities), whereas none of the D. major sampled in forests and in its allopatric range (Norway) showed signs of an intermixed genotype. Further research on hybridization and introgression in woodpeckers is undoubtedly needed and could be useful for understanding ecological and ethological interactions among these species, particularly for D. syriacus, which is relatively rare in Europe

The influence of subglacial lake discharge on Thwaites Glacier ice-shelf melting and grounding-line retreat

The retreat of the Antarctic Ice Sheet is conventionally attributed to increased ocean melting of ice shelves, potentially enhanced by internal instability from grounding lines near retrograde bed slopes. Ocean melting is enhanced by increased intrusion of modified Circumpolar Deep Water (mCDW) into ice shelf cavities. Upwelling from the release of subglacial meltwater can enhance mCDW’s melting ability, though its efficacy is not well understood and is not represented in current ice sheet loss projections. Here we quantify this process during an exceptional subglacial lake drainage event under Thwaites Glacier. We found that the buoyant plume from the subglacial discharge temporarily doubled the rate of ocean melting under Thwaites, thinning the ice shelf. These events likely contributed to Thwaites’ rapid thinning and grounding line retreat during that period. However, simulations and observations indicate that a steady subglacial water release would more efficiently enhance basal melt rates at Thwaites, with melt rate increasing like the square root of the subglacial discharge. Thus, it remains unclear whether increased subglacial flooding events provide a stabilizing influence on West Antarctic ice loss by reducing the impact of subglacial water on ocean melting, or a destabilizing influence by triggering rapid changes at the grounding zone

A uniform, quality controlled Surface Ocean CO2 Atlas (SOCAT)

A well documented, publicly available, global data set of surface ocean carbon dioxide (CO2) parameters has been called for by international groups for nearly two decades. The Surface Ocean CO2 Atlas (SOCAT) project was initiated by the international marine carbon science community in 2007 with the aim of providing a comprehensive, publicly available, regularly updated, global data set of marine surface CO2, which had been subject to quality control (QC). Many additional CO2 data, not yet made public via the Carbon Dioxide Information Analysis Center (CDIAC), were retrieved from data originators, public websites and other data centres. All data were put in a uniform format following a strict protocol. Quality control was carried out according to clearly defined criteria. Regional specialists performed the quality control, using state-of-the-art web-based tools, specially developed for accomplishing this global team effort. SOCAT version 1.5 was made public in September 2011 and holds 6.3 million quality controlled surface CO2 data points from the global oceans and coastal seas, spanning four decades (1968–2007). Three types of data products are available: individual cruise files, a merged complete data set and gridded products. With the rapid expansion of marine CO2 data collection and the importance of quantifying net global oceanic CO2 uptake and its changes, sustained data synthesis and data access are priorities

Body composition and Hashimoto disease

Background. Body weight or BMI do not provide any information about the content of muscle tissue, water content, body fat and its distribution in the body. Thyroid dysfunction is associated with a change in body weight, but also its composition regardless of physical activity. Objective. The aim of the study was to compare the body composition of female patients diagnosed with Hashimoto's disease (HD) and the body composition of healthy women who have never been treated before due to thyroid diseases. Materials and methods. The study involved 47 women diagnosed with Hashimoto disease (HD) and 65 women declaring good health. Body mass and height and body composition analysis using bioelectrical impedance analysis were performed using the TANITA multi-frequency segmental body composition analyzer. Variables having a distribution similar to the normal distribution were analyzed by the analysis of variance (ANOVA), otherwise the Kruskal-Wallis test was used. Results. Women with Hashimoto disease were characterized by significantly higher values of body weight, and thus BMI index, than healthy women (respectively 73.64 kg vs. 64.36 kg, p <0.0001; 27.65 kg/m2 vs. 23.95 kg/m2, p <0.001).The problem of excess body fat in the body statistically significantly more often affected women with Hashimoto disease than healthy women (44.7% vs. 13.8%, p <0.001). Conclusions. The results regarding the weight and composition of the patients treated for thyroid disease indicate the need for further in-depth analyses. Even small abnormalities of the thyroid function in the range of reference values may result in the development of many adverse changes in the body

Assessment of caffeine intake with food by Polish females and males

Background. Caffeine is the most widespread psychoactive substance in the world. With long-term consumption of caffeinated beverages, there is a high probability of overtaking on caffeine. Objective. The aim of the study was to estimate the consumption of caffeine in the daily caffeine intake of Polish consumers, determine the caffeinated products in the intake of this substance. Materials and methods. The survey was completed by 433 respondents living in Poland. The research tool was the electronic questionnaire, which consisted of: a) questions about personal data and measurement anthropometric and the level of physical activity and smoking; b) questions regarding the portion size and frequency of consumption of coffee, tea, cocoa, chocolate, energy drinks and colacarbonated beverages. Results. The main sources of caffeine in the respondents' diet include: coffee (Me 43.64 mg/d) and tea (Me 37.60 mg/d). Approximately 20% of respondents exceeded the threshold of daily caffeine intake (safety level for children and adolescents up to 3 mg/kg b.w, for adults up to 5.7 mg/kg b.w), considered safe. Conclusions. Respondents who have crossed the safe dose of caffeine intake, should limit the consumption of products being its main source (coffee