GENERATION OF TRIANGULAR MESHES FOR COMPLEX DOMAINS ON THE PLANE

Many physical phenomena can bc modelcd by partial diffcrcntial cąuations. The dcvclopmcnt of numcrical methods bascd on the spatial subdivision of a domain into fmitc clcmcnts immcdiatcly cxtcnded interests to the tasks of generating a mesh. With the availability of vcrsatilc field solv- crs and powerful computcrs, the simulations of cver inereasing gcometrical and physical com- plcxity arc attempted. At somc point the main bottleneck becomcs the mesh generation itsclf.The papcr prcsents a dctailcd description of the triangular mcsh gcneration schcmc on the piane bascd upon the Dclaunay triangulation. A mcsh generator should be fully automatic and simplify input data as much as possible. It should offer rapid gradation from smali to large sizes of elcmcnts. The generated mcsh must be always valid and of good quality. Ali thesc rcquiremcnts were taken into account during the selection and elaboration of utilized algorithms.Successive chapters describe procedures connected with the specification of a modeled domain, gcneration and triangulation of boundary vertices, introducing inner nodes, improving the quality of the crcated mcsh, and renumbering of vertices

Tree Structures for Adaptive Control Space in 3D Meshing

The article presents a comparison of several octree- and kd-tree-based structuresused for the construction of control space in the process of anisotropicmesh generation and adaptation. The adaptive control space utilized by theauthors supervises the construction of meshes by providing the required metricinformation regarding the desired shape and size of elements of the mesh ateach point of the modeled domain. Comparative tests of these auxiliary structureswere carried out based on different versions of the tree structures withrespect to computational and memory complexity as well as the quality of thegenerated mesh. Analysis of the results shows that kd-trees (not present inthe meshing literature in this role) offer good performance and may becomea reasonable alternative to octree structures

DEFINITION AND INTERPOLATION OF DISCRETE METRIC FOR MESH GENERATION ON 3D SURFACES

The article concerns the problem of a definition of the control space from a set of discretedata (metric description gathered from different sources) and its influence on the efficiency ofthe generation process with respect to 2D and 3D surface meshes. Several methods of metricinterpolation between these discrete points are inspected, including an automated selectionof proper method. Some aspects of the procedures of creation and employment of the meshcontrol space based on the discrete set of points are presented. The results of using differentvariations of these methods are also included

Preparation of Control Space for Remeshing of Polygonal Surfaces

The subject of the article concerns the issues of remeshing, transforming a polygonal mesh into a triangular mesh adapted to surface. From the initial polygonal mesh the curvature of surface and boundary is retrieved and used to calculate a metric tensor varying in three-dimensional space. In the proposed approach the curvature is computed using local approximation of surfaces and curves on the basis of vertices of the polygonal mesh. An essential part of the presented remeshing procedure is creation of a control space structure based on the retrieved discrete data. The subsequent process of remeshing is then supervised by the contents of this auxiliary structure. The article presents various aspects related to the procedure of initialization, creation and adjusting the control space structure

Tree-based Control Space Structures for Discrete Metric Sources in 3D Meshing

This article compares the different variations of the octree and kd-tree structures used to create a control space based on a set of discrete metric point-sources. The control space thus created supervises the generation of the mesh providing efficient access to the required information on the desired shape and size of the mesh elements at each point of the discretized domain. Structures are compared in terms of computational and memory complexity as well as regarding the accuracy of the approximation of the set of discrete metric sources in the created control space structure

HSP Transcript and Protein Accumulation in Brassinosteroid Barley Mutants Acclimated to Low and High Temperatures

In temperature stress, the main role of heat-shock proteins (HSP) is to act as molecular chaperones for other cellular proteins. However, knowledge about the hormonal regulation of the production of the HSP is quite limited. Specifically, little is known about the role of the plant steroid hormones—brassinosteroids (BR)—in regulating the HSP expression. The aim of our study was to answer the question of how a BR deficit or disturbances in its signaling affect the accumulation of the HSP90, HSP70, HSP18, and HSP17 transcripts and protein in barley growing at 20C (control) and during the acclimation of plants at 5 C and 27 C. In barley, the temperature of plant growth modified the expression of HSPs. Furthermore, the BR-deficient mutants (mutations in the HvDWARF or HvCPD genes) and BR-signaling mutants (mutation in the HvBRI1 gene) were characterized by altered levels of the transcripts and proteins of the HSP group compared to the wild type. The BR-signaling mutant was characterized by a decreased level of the HSP transcripts and heat-shock proteins. In the BR-deficient mutants, there were temperature-dependent cases when the decreased accumulation of the HSP70 and HSP90 transcripts was connected to an increased accumulation of these HSP. The significance of changes in the accumulation of HSPs during acclimation at 27 C and 5 C is discussed in the context of the altered tolerance to more extreme temperatures of the studied mutants (i.e., heat stress and frost, respectively)

Diverse Stomatal Behaviors Mediating Photosynthetic Acclimation to Low Temperatures in Hordeum vulgare

Photosynthetic acclimation to cold conditions is an important factor influencing freezing tolerance of plants. Photosynthetic enzyme activities increase as part of a photochemical mechanism underlying photosynthetic acclimation to low temperatures. Additionally, a non-photochemical mechanism may be activated to minimize photooxidative damage. The aim of this study was to test the hypothesis that differences in stomatal conductance in Hordeum vulgare plants with contrasting freezing tolerances induce various strategies for photosynthetic acclimation to cold stress. Different stomatal behaviors during the prehardening step resulted in diverse plant reactions to low-temperature stress. Plants with a relatively low freezing tolerance exhibited decreased stomatal conductance, resulting in decreased photochemical activity, faster induction of the non-photochemical mechanism, and downregulated expression of two Rubisco activase (RcaA) splicing variants. In contrast, plants with a relatively high freezing tolerance that underwent a prehardening step maintained the stomatal conductance at control level and exhibited delayed photochemical activity and RcaA expression decrease, and increased Rubisco activity, which increased net photosynthetic rate. Thus, in barley, the induction of photoinhibition avoidance (i.e., non-photochemical photoacclimation mechanism) is insufficient for an effective cold acclimation. An increase in cold-induced net photosynthetic rate due to open stomata is also necessary

Plasma membrane ATPase and the aquaporin HvPIP1 in barley brassinosteroid mutants acclimated to high and low temperature

The integral parts of the cell membranes are the functional proteins, which are crucial for cell life. Among them, proton-pumping ATPase and aquaporins appear to be of particular importance. There is some knowledge about the effect of the temperature during plant growth, including stress-inducing temperatures, on the accumulation of the membrane proteins: plasma membrane H+-ATPase and aquaporins, but not much is known about the effect of the phytohormones (i.e. brassinosteroids (BR)) on control of accumulation of these proteins. The aim of our study was to answer the question of how a BR deficit and disturbances in the BR perception/signalling affect the accumulation of plasma membrane H+-ATPase (PM H+-ATPase), the aquaporin HvPIP1 transcript and protein in barley growing at 20 °C and during its acclimation at 5 °C and 27 °C. For the studies, the BR-deficient mutant 522DK (derived from the wild-type Delisa), the BR-deficient mutant BW084 and the BR-signalling mutant BW312 and their wild-type Bowman were used. Generally, temperature of growth was significant factor influencing on the level of the accumulation of the H+-ATPase and HvPIP1 transcript and the PM H+-ATPase and HvPIP1 protein in barley leaves. The level of the accumulation of the HvPIP1 transcript decreased at 5 °C (compared to 20 °C), but was higher at 27 °C than at 20 °C in the analyzed cultivars. In both cultivars the protein HvPIP1 was accumulated in the highest amounts at 27 °C. On the other hand, the barley mutants with a BR deficiency or with BR signalling disturbances were characterised by an altered accumulation level of PM H+-ATPase, the aquaporin HvPIP1 transcript and protein (compared to the wild types), which may suggest the involvement of brassinosteroids in regulating PM H+-ATPase and aquaporin HvPIP1 at the transcriptional and translational levels

Systemic treatment of patients with advanced pancreatic cancer — is there still a place for gemcitabine in the first-line setting? Experience of Polish oncology centers

Introduction. Despite some progress in the treatment of patients with pancreatic cancer, it is still a malignancy with a poor prognosis, which results from its rapid local growth with a tendency to infiltrate surrounding tissues and metastasize, and late diagnosis at the advanced stage. The use of multi-drug regimens and modern targeted therapies did not completely eliminate the use of gemcitabine in monotherapy, which is a therapeutic option mainly in patients with poor performance status, ineligible for more advanced therapies. This study aimed to evaluate the results of treatment with single-agent gemcitabine in everyday clinical practice in Poland and to attempt to identify the predictors of obtaining long-term responses resulting from this treatment.  Material and methods. A retrospective analysis of 167 patients with advanced pancreatic cancer treated with single-agent gemcitabine in five oncology centers in Poland in the years 2017–2022 was conducted. Gemcitabine was used as monotherapy at an initial dose of 1000 mg/m2 of body surface area (BSA) weekly, 7 times in an 8-week cycle, then 3 times in a 4-week cycle.  Results. Median overall survival (OS) in the entire group of patients was 6.1 months (range — 0.2–32.3 months), and median progression-free survival (PFS) was 4.2 months (range — 0.2–31.3 months). A group of 60 patients was identified as “long responders” (LR), with a response of at least 6 months and a group of 107 as “short responders” (SR). Median PFS in the LR group was 9.15 months (range — 6.0–31.3 months) and in the SR group, it was 3.2 months (range — 0.2–5.8 months). Median OS was 11.6 months (range — 5.9–30.8) and 3.8 months (range — 0.2–32.3 months), respectively. In multivariate analysis, the likelihood of achieving at least a 6-month response (LR) was assessed using a logistic regression model. The model takes into account four variables: the neutrophil/lymphocyte (NLR) ratio, liver metastases, sex, and Hb level. Conclusions. The obtained results confirm that gemcitabine monotherapy is still useful in the first-line treatment of patients with advanced and metastatic pancreatic adenocarcinoma. An appropriate selection of patients for this treatment may improve the results while maintaining lower toxicity compared to combined treatment.

Neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and systemic immune-inflammation index as clinical predictive and prognostic markers in patients with advanced pancreatic cancer receiving gemcitabine monotherapy

Introduction. Pancreatic cancer is characterized by an increasing incidence and still poor prognosis despite the availability of various therapeutic options, currently including single- and multi-drug chemotherapy as well as molecularly targeted therapy. Therefore, appropriate qualification for particular therapies, based mainly on clinical and histological factors, is extremely important. Inflammatory status, associated with cancer development, justifies the search for prognostic markers related to the immune system, which could be additional factors facilitating selection of appropriate therapy. This study aimed at assessing the prognostic value of the neutrophil-to-lymphocyte ratio (NLR), plateletto- lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) in patients with advanced pancreatic cancer undergoing gemcitabine monotherapy.  Material andmethods. A retrospective analysis of blood morphological parameters was performed in 167 patients with advanced pancreatic cancer treated with gemcitabine monotherapy in the first line in five oncology centers in Poland in the years 2017–2022. The NLR, PLR, and SII were calculated, and cut-off points between high and low values were defined. Clinical parameters and their distribution were assessed depending on the overall survival (OS) value equal to or greater than or less than median OS. The distribution of patients within OS intervals in relation to the categories of inflammatory markers was assessed.  Results. The median age of patients was 71 years, the majority were women (58%), with clinical stage IV (57%), and with dominant location of metastases in the liver (42.5%). The median NLR was 2.69 (range 0.5–36.65), PLR 146.54 (range 18.53–1118.57), and SII 784.75 (range 79.86–10622.67). The cut-off points were defined as 4.5625 for the NLR [125 patients (75.8%) with a value less than and 40 patients (24.3%) with a value equal to or greater], 150 for the PLR [87 (52.7%)/ 78 (47.3%)], and 897.619 for the SII [96 (58.2%)/69 (41.8%)]. Comparing the groups with OS longer than or equal to the median and OS shorter than the median, statistically significant differences were found in relation to body mass index (BMI) (p = 0.02), baseline stage (p < 0.001), and location of metastases (p < 0.001). There were statistically significantly more NLR and SII values below the cut-off points in patients with survival at least equal to median OS. Concerning the PLR, no statistically significant differences were found between groups determined by OS value.  Conclusions. We demonstrated the relationship between indicators calculated on the basis of blood count parameters and treatment results. It may indicate the predictive and prognostic importance of indices reflecting immune system status, which can be a valuable addition to the clinical criteria included in prognostic models.