Approximation of Jacobian Inverse Kinematics Algorithms: Differential Geometric vs. Variational Approach

This paper addresses the approximation problem of Jacobian inverse kinematics algorithms for redundant robotic manipulators. Specifically, we focus on the approximation of the Jacobian pseudo inverse by the extended Jacobian algorithm. The algorithms are defined as certain dynamic systems driven by the task space error, and identified with vector field distributions. The distribution corresponding to the Jacobian pseudo inverse is non-integrable, while that associated with the extended Jacobian is integrable. Two methods of devising the approximating extended Jacobian algorithm are examined. The first method is referred to as differential geometric, and relies on the approximation of a non-integrable distribution (in fact: a codistribution) by an integrable one. As an alternative, the approximation problem has been formulated as the minimization of an approximation error functional, and solved using the methods of the calculus of variations. Performance of the obtained extended Jacobian inverse kinematics algorithms has been compared by means of computer simulations involving the kinematics model of the 7 dof industrial manipulator POLYCRANK. It is concluded that the differential geometric method offers a rapid, while the variational method a systematic tool for solving inverse kinematic problems.     

Delivery of Nucleotide Sugars to the Mammalian Golgi: A Very Well (un)Explained Story

Nucleotide sugars (NSs) serve as substrates for glycosylation reactions. The majority of these compounds are synthesized in the cytoplasm, whereas glycosylation occurs in the endoplasmic reticulum (ER) and Golgi lumens, where catalytic domains of glycosyltransferases (GTs) are located. Therefore, translocation of NS across the organelle membranes is a prerequisite. This process is thought to be mediated by a group of multi-transmembrane proteins from the SLC35 family, i.e., nucleotide sugar transporters (NSTs). Despite many years of research, some uncertainties/inconsistencies related with the mechanisms of NS transport and the substrate specificities of NSTs remain. Here we present a comprehensive review of the NS import into the mammalian Golgi, which consists of three major parts. In the first part, we provide a historical view of the experimental approaches used to study NS transport and evaluate the most important achievements. The second part summarizes various aspects of knowledge concerning NSTs, ranging from subcellular localization up to the pathologies related with their defective function. In the third part, we present the outcomes of our research performed using mammalian cell-based models and discuss its relevance in relation to the general context.     

Comprehensive Approach for Porous Materials Analysis Using a Dedicated Preprocessing Tool for Mass and Heat Transfer Modeling

The paper presents a comprehensive, newly developed software – poROSE(poROus materials examination SoftwarE) for the qualitative and quantitative assessment of porous materials and analysis methodologies developed by the authors as a solution for emerging challenges. A low porosity rock sample was analyzed and thanks to the developed and implemented methodologies in poROSE software, the main geometrical properties were calculated. A tool was also used in preprocessing part of the computational analysis to prepare a geometrical representation of the porous material. The basic functions as elimination of blind pores in the geometrical model were completed and the geometrical model was exported for CFD software. As a result, it was possible to carry out calculations of the basic properties of the analyzed porous material sample. The developed tool allows to carry out quantitative and qualitative analysis to determine the most important properties characterized porous materials. In presented tool the input data can be images from X-ray computed tomography(CT), scanning electron microscope(SEM) or focused ion beam with scanning electron microscope(FIB-SEM) in grey level. A geometric model developed in the proper format can be used as an input to modeling mass, momentum and heat transfer, as well as, in strength or thermo-strength analysis of any porous materials. In this example, thermal analysis was carried out on the skeleton of rock sample. Moreover, thermal conductivity was estimated using empirical equations.     

Processing relative humidity data using discrete Fourier transform to control strain in art objects

Sustainable management of cultural heritage collections requires tools that, on the one hand, quantitatively relate risk of damage to environmental impacts and, on the other hand, can be easily used by conservation professionals and decision makers in heritage buildings or buildings housing collections. This paper explains how continual processing of ambient relative humidity (RH) data monitored in museums or historical buildings is used to assess quantitatively the climate‐induced physical damage risk to art objects. The software continually decomposes RH data into a set of elementary sinusoidal RH fluctuations using discrete Fourier transform. The user needs to provide basic characterisation of objects in the collection. Then each elementary sinusoidal RH fluctuation is transformed, using the precalculated database, into an elementary strain fluctuation experienced by the object. The complete strain history is calculated by the superposition of all elementary strain fluctuations. The risk of damage can be assessed by comparing strain against a critical level selected—the damage criterion. Wooden panels have been selected to illustrate the approach, and its reliability was demonstrated by comparison with the strain versus time histories obtained by full finite element modelling. The proposed approach based on the analysis of moisture response of objects is significant progress to current practices of evaluating climate parameters themselves.     

Insights on boron impact on structural characteristics in epitaxially grown BGaN

Journal of Materials Science - It is shown that MOCVD growth allows to obtain BGaN epitaxial layers at growth temperature (Tgr) between 840 and 1090 °C. It is found that morphology of...     

Bioactive compound levels and sensory quality of partially skimmed organic yoghurts: Effects of the milk treatment,production season and starter culture*

The aim of the study was to assess the physicochemical properties, texture, colour and sensory quality of organic yoghurts with regard to the milk treatment (raw milk obtained directly from organic farms, partially skimmed and heat‐treated in the laboratory vs organic milk purchased in the shop that was pasteurised in a dairy), production season and starter culture. The yoghurts produced on the basis of bulk milk obtained from farms during the spring/summer season proved to be of greater nutritional value and had higher content of bioactive whey proteins, except for β‐lactoglobulin, and lipophilic vitamins than retail milk.     

Hypertensive Effect of Downregulation of the Opioid System in Mouse Model of Different Activity of the Endogenous Opioid System

The opioid system is well-known for its role in modulating nociception and addiction development. However, there are premises that the endogenous opioid system may also affect blood pressure. The main goal of the present study was to determine the impact of different endogenous opioid system activity and its pharmacological blockade on blood pressure. Moreover, we examined the vascular function in hyper- and hypoactive states of the opioid system and its pharmacological modification. In our study, we used two mouse lines which are divergently bred for high (HA) and low (LA) swim stress-induced analgesia. The obtained results indicated that individuals with low endogenous opioid system activity have higher basal blood pressure compared to those with a hyperactive opioid system. Additionally, naloxone administration only resulted in the elevation of blood pressure in HA mice. We also showed that the hypoactive opioid system contributes to impaired vascular relaxation independent of endothelium, which corresponded with decreased guanylyl cyclase levels in the aorta. Together, these data suggest that higher basal blood pressure in LA mice is a result of disturbed mechanisms in vascular relaxation in smooth muscle cells. We believe that a novel mechanism which involves endogenous opioid system activity in the regulation of blood pressure will be a promising target for further studies in hypertension development.