On the Optimal Dividend Problem for Insurance Risk Models with Surplus-Dependent Premiums

This paper concerns an optimal dividend distribution problem for an insurance company with surplus-dependent premium. In the absence of dividend payments, such a risk process is a particular case of so-called piecewise deterministic Markov processes. The control mechanism chooses the size of dividend payments. The objective consists in maximazing the sum of the expected cumulative discounted dividend payments received until the time of ruin and a penalty payment at the time of ruin, which is an increasing function of the size of the shortfall at ruin. A complete solution is presented to the corresponding stochastic control problem. We identify the associated Hamilton-Jacobi-Bellman equation and find necessary and sufficient conditions for optimality of a single dividend-band strategy, in terms of particular Gerber-Shiu functions. A number of concrete examples are analyzed

O sposobach finansowania działalności naukowo-dydaktycznej szkół wyższych w Polsce

Rozmowa z dr. hab. Zbigniewem Marciniakiem, prof. Uniwersytetu Warszawskiego, podsekretarzem stanu w Ministerstwie Nauki i Szkolnictwa Wyższego w latach 2010–201

Finite Matrix Groups over Nilpotent Group Rings

AbstractWe study groups of matricesSGLn(ZΓ) of augmentation one over the integral group ring ZΓ of a nilpotent group Γ. We relate the torsion ofSGLn(ZΓ) to the torsion of Γ. We prove that all abelianp-subgroups ofSGLn(ZΓ) can be stably diagonalized. Also, all finite subgroups ofSGLn(ZΓ) can be embedded into the diagonal Γn<SGLn(ZΓ). We apply matrix results to show that if Γ is nilpotent-by-(Π′-finite) then all finite Π-groups of normalized units in ZΓ can be embedded into Γ

Mechanics, Fatigue, and Fracture of Structural Joints

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On Extension Problem, Decomposing and Covering of Functions

In this chapter, we review some problems related to extension, decomposition and covering of functions. We mainly do not give proofs of the results stated here.Udostępnienie publikacji Wydawnictwa Uniwersytetu Łódzkiego finansowane w ramach projektu „Doskonałość naukowa kluczem do doskonałości kształcenia”. Projekt realizowany jest ze środków Europejskiego Funduszu Społecznego w ramach Programu Operacyjnego Wiedza Edukacja Rozwój; nr umowy: POWER.03.05.00-00-Z092/17-00

Fatigue fracture morphology of AISI H13 steel obtained by additive manufacturing

DEC-10/2021/IDUB/IV.2/EUROPIUM 030/RID/2018/19The paper focuses on researching the effect of fatigue loading on metallic structure, lifetime, and fracture surface topographies in AISI H13 steel specimens obtained by selective laser melting (SLM). The topography of the fracture surfaces was measured over their entire area, according to the entire total area method, with an optical three-dimensional surface measurement system. The fatigue results of the SLM 3D printed steel specimens were compared with those reported for conventionally manufactured 13H steel. The investigation also considers the roughness of the specimens’ side surface. Moreover, the fractographic evaluation conducted using scanning electron microscopy confirms that the predominant fracture mechanism is transgranular fracture. Microtomography done after mechanical loading also showed the influence of the stress level on the porosity distribution. Both fractographic and Micro-CT investigations confirm that higher stresses result in coarser and much more uniform porosity observed in fractured samples. These comprehensive quantitative and qualitative fracture analyses are beneficial to predict the failure conditions of SLM steel parts, especially in the case of fatigue damage. From the quantitative analysis of the H13 SLM-manufactured fracture surface topography, it was possible to conclude that the larger the loadings acting on the specimen, the rougher the fracture surface because the ductile fracture mode dominates. It has also been proven that the porosity degree changes along the length of the sample for the most stressed specimens.publishersversionepub_ahead_of_prin

Steered molecular dynamics of lipid membrane indentation by carbon and silicon-carbide nanotubes - the impact of indenting angle uncertainty

Due to the semi-liquid nature and uneven morphologies of biological membranes, indentation may occur in a range of non-ideal conditions. These conditions are relatively unstudied and may alter the physical characteristics of the process. One of the basic challenges in the construction of nanoindenters is to appropriately align the nanotube tip and approach the membrane at a perpendicular angle. To investigate the impact of deviations from this ideal, we performed non-equilibrium steered molecular dynamics simulations of the indentation of phospholipid membranes by homogeneous CNT and non-homogeneous SiCNT indenters. We used various angles, rates, and modes of indentation, and the withdrawal of the relative indenter out of the membrane in corresponding conditions was simulated

Solanum nigrum extract and solasonine affected hemolymph metabolites and ultrastructure of the fat body and the midgut in Galleria mellonella

Glycoalkaloids, secondary metabolites abundant in plants belonging to the Solanaceae family, may affect the physiology of insect pests. This paper presents original results dealing with the influence of a crude extract obtained from Solanum nigrum unripe berries and its main constituent solasonine on the physiology of Galleria mellonella (Lepidoptera). Both extract and solasonine applied in the nourishment changed the level of hemolymph metabolites such as sugars, polyols and proline, and ultrastructure of the fat body and the midgut cells. The extract and solasonine, tested in the same concentration found in the extract, decreased the proline level, while mannitol was under the limit of detection in the hemolymph. The extract increased the erythritol level in the hemolymph compared to control, enlarged the intracellular space in fat body cells, decreased cytoplasm and lipid droplets electron density. In the midgut, vacuolized areas of cytoplasm ap-peared with vast reticulum systems. Solasonine, tested with three concentrations, caused the decrease of cytoplasm electron density in both fat body and midgut cells. Obtained results high-lighted the disturbance of the midgut and the fat body due to glycoalkaloids and the potential role of hemolymph ingredients in its detoxification

Ból i cierpienie

Publikacja recenzowana / Peer-reviewed publicationZE WSTĘPU: W tym roku oddajemy do rąk Czytelników szczególnie uroczysty zeszyt cyklicznego wydawnictwa Krakowskiej Szkoły Wyższej „Acta Academiae Modrevianae”, na łamach którego zamieszczamy referaty wygłoszone na jubileuszowej sesji nt. „Ból i cierpienie” w 2007 roku