On-line coloring of IsI_s-free graphs

International audienceAn on-line vertex coloring algorithm receives vertices of a graph in some externally determined order. Each new vertex is presented together with a set of the edges connecting it to the previously presented vertices. As a vertex is presented, the algorithm assigns it a color which cannot be changed afterwards. The on-line coloring problem was addressed for many different classes of graphs defined in terms of forbidden structures. We analyze the class of $I_s$-free graphs, i.e., graphs in which the maximal size of an independent set is at most $s-1$. An old Szemerédi's result implies that for each on-line algorithm A there exists an on-line presentation of an $I_s$-free graph $G$ forcing A to use at least $\frac{s}{2}χ ^{(G)}$ colors. We prove that any greedy algorithm uses at most $\frac{s}{2}χ^{(G)}$ colors for any on-line presentation of any $I_s$-free graph $G$. Since the class of co-planar graphs is a subclass of $I_5$-free graphs all greedy algorithms use at most $\frac{5}{2}χ (G)$ colors for co-planar $G$'s. We prove that, even in a smaller class, this is an almost tight bound

On-line coloring of IsI_s-free graphs

An on-line vertex coloring algorithm receives vertices of a graph in some externally determined order. Each new vertex is presented together with a set of the edges connecting it to the previously presented vertices. As a vertex is presented, the algorithm assigns it a color which cannot be changed afterwards. The on-line coloring problem was addressed for many different classes of graphs defined in terms of forbidden structures. We analyze the class of $I_s$-free graphs, i.e., graphs in which the maximal size of an independent set is at most $s-1$. An old Szemerédi's result implies that for each on-line algorithm A there exists an on-line presentation of an $I_s$-free graph $G$ forcing A to use at least $\frac{s}{2}χ ^{(G)}$ colors. We prove that any greedy algorithm uses at most $\frac{s}{2}χ^{(G)}$ colors for any on-line presentation of any $I_s$-free graph $G$. Since the class of co-planar graphs is a subclass of $I_5$-free graphs all greedy algorithms use at most $\frac{5}{2}χ (G)$ colors for co-planar $G$'s. We prove that, even in a smaller class, this is an almost tight bound

Biologically Active Compounds in Stizolophus balsamita Inflorescences: Isolation, Phytochemical Characterization and Effects on the Skin Biophysical Parameters

Three germacranolides, as well as five flavonoids, natural steroid and simple phenolic compounds, were isolated from the inflorescence of Stizolophus balsamita growing in Iran. The paper presents active compounds found for the first time in the inflorescence of this species. The flavonoids, simple phenolic compounds and natural steroids have been isolated for the first time in the genus Stizolophus. The MTT assay was employed to study in vitro cytotoxic effects of the taxifolin against human fibroblasts. We also evaluate the possible biological properties/cosmetic effects of Stizolophus balsamita extract and taxifolin on the human skin. Sixty healthy Caucasian adult females with no dermatological diseases were investigated. We evaluate the effects of S. balsamita extract and taxifolin on skin hydration and transepidermal water loss (TEWL). It was revealed that S. balsamita extract might decrease TEWL level and fixed the barrier function of the epidermis. The presence of bioactive phytochemical constituents in S. balsamita inflorescences makes them a valuable and safe source for creating new cosmetics and medicines

Analysis of Cosmetic Products Containing <i>Serratula coronata</i> Herb Extract

Phytoecdysteroids exert significant anti-inflammatory effects, which makes them valuable ingredients in pharmaceutical and cosmetic products. However, data on their use in cosmetics are limited. Here, a new formulation with the extract of the Serratula coronata herb containing phytoecdysteroids was developed. The aim of this study was to perform physicochemical characteristics and evaluate the safety of the creams with S. coronata. Chromatography was used to detect the dominant phytoecdysteroids in the extract. The chemical and physical description of the creams was performed using the following parameters: viscosity, pH, and stability. The microbiological purity (pharmacopoeial methods) and transdermal permeability (Raman spectroscopy) were assessed to ensure the safety of the plant extracts used in the creams. The study confirmed the presence of phytoecdysteroid fractions of the S. coronata herb in the creams (20-hydroxyecdysone, polypodine B, and ajugasterone C). The results indicated that the cosmetics containing the S. coronata extract were chemically and microbiologically stable, thereby contributing to their safety. Their effectiveness is the result of transdermal permeability of 20-hydroxyecdysone. In this study, we demonstrated the importance of the S. coronata extract as a source of bioactive phytoecdysteroids and proved that the extract’s characteristics may make it the key ingredient of safe and stable skincare products that support the treatment of various inflammatory skin diseases. These results were a continuation of those presented in our earlier publication

Impact of the work environment on patients safety as perceived by nurses in Poland-a cross-sectional study

Numerous studies have found that organizational features connected with the work environment of nurses have a significant influence on patients’ safety. The aim of this research was to capture nurses’ opinions about patients’ safety and discern relationships with work environment characteristics. This cross-sectional study surveyed 1825 nurses. The research used questionnaire consisting of four parts: (1) covered The Practice Environment Scale of the Nursing Work Index (PES-NWI); (2) assessed the quality of nursing care and care safety; (3) contained information on the most recent duty served by the nurses and (4) captured social and demographic data of participants. The research identified strong association between patient safety assessment and work environment of nurses in the aspect of employment adequacy, cooperation between nurses and doctors, support for nurses from the managing staff, the possibility to participate in the management as well as professional promotion of nurses employed in the hospital (p &lt; 0.001). Nurses rated patient safety higher when responsible for a smaller number of patients. Work environment factors such as proper staffing, good cooperation with doctors, support from the management, as well as professional independence are significantly related to nurses’ assessment of patients’ safety

Milky Sap of Greater Celandine (Chelidonium majus L.) and Anti-Viral Properties

The milky juice of the greater celandine herb has been used in folk medicine and in homeopathy for treatment of viral warts for years. However, classical medicine fails to use properties of celandine herbs in treatment of diseases induced by papilloma viruses. Nevertheless, dermatological outpatient clinics are regularly visited by patients reporting efficacy of milky sap isolated from celandine herb in treatment of their own viral warts. Authors of this report decided to analyze the respective world literature in order to critically evaluate the potential for treatment of viral dermal warts using the milky sap of celandine. Moreover, the case of a 4-year old boy was presented, the parents of whom applied the milky sap of celandine on viral warts on hands. Thus, Ch. majus may be a potential therapeutic modality for skin warts, especially in a young patients, where conventional therapy may be difficult to apply