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Ke Wang - One of the best experts on this subject based on the ideXlab platform.

  • persistence and extinction of a stochastic Single Specie model under regime switching in a polluted environment
    Journal of Theoretical Biology, 2010
    Co-Authors: Ke Wang
    Abstract:

    Abstract This is a continuation of our paper [Liu, M., Wang, K., 2010. Persistence and extinction of a stochastic Single-Specie model under regime switching in a polluted environment, J. Theor. Biol. 264, 934–944]. Taking both white noise and colored noise into account, a stochastic Single-Species model under regime switching in a polluted environment is studied. Sufficient conditions for extinction, stochastic nonpersistence in the mean, stochastic weak persistence and stochastic permanence are established. The threshold between stochastic weak persistence and extinction is obtained. The results show that a different type of noise has a different effect on the survival results.

Burhenne Matthias - One of the best experts on this subject based on the ideXlab platform.

  • Biotestsystem mit Bodenalgen zur ökotoxikologischen Bewertung von Schwermetallen und Pflanzenschutzmitteln am Beispiel von Cadmium und Isoproturon
    Humboldt-Universität zu Berlin Mathematisch-Naturwissenschaftliche Fakultät I, 2000
    Co-Authors: Burhenne Matthias
    Abstract:

    Biotests sind für die toxikologische Bewertung von Chemikalien, Pflanzenschutzmitteln und schadstoffbelasteten Gewässern oder Böden von besonderer Bedeutung, da sie Auskünfte über die biologische Wirksamkeit eines Stoffes auf Organismen geben. Bislang gibt es für die ökotoxikologische Bewertung, insbesondere von Chemikalien und Pflanzenschutzmitteln, für die autotrophe Organismenebene neben verschiedenen Biotests mit höheren Pflanzen den DIN 28 692 Biotest "Wachstumshemmtest mit den Süßwasseralgen Scenedesmus subspicatus und Selenastrum capricornutum", der auch als OECD 201 Biotest "Algal, Growth Inhibition Test" vorliegt. Dieser aquatische Biotest wird nur mit einer Süßwasseralgenart durchgeführt und trotzdem zunehmend für die Bewertung von belasteten Böden und Sedimenten eingesetzt. Untersuchungen über aquatische Biotests, die Bodenalgen als Testorganismen nutzen, oder Boden-Biotests mit Bodenalgen gibt es nur vereinzelt. Ein Biotestsystem, das sowohl aus einem aquatischen als auch aus einem terrestrischen Biotest besteht und mehrere Bodenalgenarten als Testorganismen nutzt, existiert bisher nicht. Dieses wurde in vorliegender Arbeit entwickelt und an dem Schwermetall Cadmium als Cadmiumchlorid und dem Herbizid Arelon, Wirkstoff Isoproturon erprobt. Um Bodenalgen, die keine Resistenzen oder Toleranzen gegenüber Schadstoffen aufweisen, als Testorganismen nutzen zu können, wurden aus unbelasteten Böden Algen isoliert, Klonkulturen erstellt und die Arten bestimmt. Dies führte zu einer Sammlung mit 35 Algenarten. Aus den in die Bodenalgensammlung aufgenommenen Arten wurden Xanthonema tribonematoides, Stichococcus bacillaris, Klebsormidium flaccidum, Xanthonema montanum und Chlamydomonas noctigama für das Testsystem ausgewählt. Zusätzlich zu diesen wurde die Süßwasseralge Scenedesmus subspicatus als Referenzalge ausgewählt. Mit diesen Algen wurde der Gel-Biotest, bestehend aus einem flüssigen gelartigen Medium, das die Kontaminationspfade im Wasser nachbildet, und ein Boden-Biotest mit einem naturnahen sorptionsschwachen Boden entwickelt, der die Kontaminationspfade über Gas-, Wasser- und Festphase im Boden nachbildet. Bei der Erprobung dieses Biotestsystems mit Cadmiumchlorid und Isoproturon zeigte sich, daß Bodenalgen gegenüber Cadmiumchlorid im Gel-Biotest eine geringe bis mittlere Sensibilität aufwiesen. Im Boden-Biotest lag eine sehr geringe Sensibilität vor, wie dies auch bei anderen Bodenorganismengruppen in Biotests festgestellt wurde. Dies kann mit der Sorption der Cadmiumionen im Boden erklärt werden und dem damit geringen für die Organismen bioverfügbaren Cadmiumionenanteil. Für Isoproturon lag sowohl im Gel- als auch im Boden-Biotest eine hohe Sensibilität der Bodenalgen vor. Erstaunlich war, daß die Sensibilität in beiden Biotests nahezu identisch war, obwohl Isoproturon in sorptionsschwachen Böden zu ca. 30 % adsorbiert wird. Im Vergleich zur Sensibilität von Scenedesmus subspicatus waren die Bodenalgen bei Cadmiumchlorid bis auf zwei Ausnahmen um den Faktor 5 bis 10 unsensibler. Die Bodenalge Klebsormidium flaccidum besaß eine vergleichbare Sensibilität und Xanthonema montanum war um den Faktor 20 unsensibler. Für Isoproturon konnten keine Unterschiede in der Sensibilität zwischen Scenedesmus subspicatus und den geprüften Bodenalgen ermittelt werden, außer bei Stichococcus bacillaris, die um den Faktor 5 unempfindlicher war. Das entwickelte miniaturisierte Biotestsystem eignet sich dazu, differenzierte Aussagen über das ökotoxische Potential von Stoffen auf Bodenalgen und der Süßwasseralge Scenedesmus subspicatus zu erhalten. Durch den Einsatz von zwei unterschiedlichen Testsubstraten (Flüssigmedium und naturnaher Boden) werden der Einfluß dieser Substrate sowie die daraus resultierenden Kontaminationspfade der Teststoffe und ihre ökotoxikologische Wirkung auf Algen feststellbar und vergleichbar. Ein Normenentwurf des Biotestsystems wurde inzwischen in das "Technical Committee 190 - Soil Quality" der International Standards Organization (ISO) eingereicht.Biotests are an important device to assess the toxicity of chemicals, pesticides, polluted water, and soils because they can provide direct information about the influence of a compound on the organism level. Besides various biotests using higher plants there is only the DIN 28 692 biotest "Growth-inhibition test using fresh water algae Scenedesmus subspicatus and Selenastrum capricornutum" (DIN 28 692) also known as the OECD 201 biotest "Algal, Growth Inhibition Test" which is currently available for an ecotoxicological assessment of chemicals such as pesticides on the autotrophic organism level. This aquatic biotest is based on a Single Specie of fresh water algae and is increasingly applied to evaluate polluted soils and sediments. There is almost no information on aquatic biotests which are using soil algae as test organisms instead. A more comprehensive biotest system which actually combines aquatic and terrestric biotests using several soil algae Species as test organisms has not been reported, yet. Thus, a biotest system was developed and subsequently evaluated by using cadmium (cadmium chloride) as a heavy metal, and the herbicide arelon containing isoproturon as the active ingredient. Soil algae were isolated from unpolluted soil in order to obtain test organisms which are not resistant or tolerant to pollutants. The algae isolates were then cultivated, and subsequently identified. A total of 35 algae Species was collected. Algae Species used in the biotest system were Xanthonema tribonematoides, Stichococcus bacillaris, Klebsormidium flaccidum, Xanthonema montanum, Chlamydomonas noctigama. In addition, the fresh water Specie Scenedesmus subspicatus served as a reference algae. Based on these different algae Species a gel biotest using liquid gel medium was developed to investigate the contamination path via water, and also a soil biotest with a pre-treated soil of low sorption capacity was deviced to simulate the contamination path through gas, water, and solid phase. The evaluation of the biotest system using cadmium chloride and isoproturon did reveal that soil algae have had only low to medium sensitivity to cadmium chloride in the gel biotest. Algae sensitivity in the soil biotest was very low which was in accordance with data from other biotests using different soil organisms. The weak response of the algae was most likely caused by the sorption of the cadmium ions to the soil matrix what may have decreased the bioavailability of cadmium. In comparison, soil algae were very sensitive to isoproturon in both, the gel biotest and the soil biotest. Both biotests indicated almost identical sensitivities of the tested soil algae which was surprising since 30 % of the isoproturon was sorbed even in soils with a low sorption capacity. Soil algae when compared to the water algae Scenedesmus subspicatus were generally 5 to 10-fold less sensitive to cadmium chloride. Only Klebsormidium flaccidum has proved to have a similar sensitivity as Scenedesmus subspicatus had, whereas Xanthonema montanum was about 20-fold less sensitive. With isoproturon, however, no differences in sensitivity could be seen between Scenedesmus subspicatus and the tested soil algae, except Stichococcus bacillaris which was about 5-fold less sensitive. The biotest system as developed in this study has shown to be suitable for obtaining valuable information about ecotoxicological effects of chemicals on soil and water algae. Since the biotest system consists of two different test media (liquid gel and soil) it is possible to determine ecotoxicological effects on algae in both, water and soil. A first draft of the developed biotest system has been submitted to the "Technical Committee 190 - Soil Quality" of the International Standards Organization (ISO) for review

Iregui C., Carlos Arturo - One of the best experts on this subject based on the ideXlab platform.

  • Estructura histológica normal de la piel del perro (estado del arte)
    Universidad de La Salle. Revistas. Revista de Medicina Veterinaria., 2017
    Co-Authors: Castellanos I., Giovanna Clarena, Rodríguez T. Gersain, Iregui C., Carlos Arturo
    Abstract:

    The skin is one of the largest organs of the body, and it has multiple functions: metabolic, temperature regulator, sensibility, and protection. The skin is formed by three layers: epidermis, dermis and hypodermis; the annexed ones are found in the dermis: hair follicles, sebaceous glands, sweat glands; the nails are found in the appendix. Although the skin structure in domestic animals is similar, there are variations among Species and even in a Single Specie related to epidermal thickness, dermal thickness, types and arrangements of hair follicles, and annexed structures. Knowing that Skin’s diseases are common in clinic practices in small animals, this article will review the normal histology structure of dog’s skin in order to know the changes in skin’s diseases in this Specie.La piel es uno de los órganos más extensos del cuerpo y cumple múltiples funciones: metabólicas, de termorregulación, sensibilidad y protección; está formada por tres capas: la epidermis, la dermis y la hipodermis; en la dermis se encuentran los anexos: folículos pilosos, glándulas sebáceas y glándulas sudoríparas; dentro de los apéndices se encuentran las uñas. Aunque la arquitectura de la piel en los animales domésticos es muy similar, existen variaciones entre eSpecies y aun dentro de un mismo individuo en cuanto al espesor de la epidermis y la dermis, las clases y la disposición de los folículos pilosos y las estructuras anexas. Teniendo en cuenta que las enfermedades dermatológicas son muy frecuentes en la práctica clínica con pequeños animales, en el presente artículo se revisan los aspectos histológicos normales de la piel del perro para poder comprender los cambios que ocurren en la enfermedad dermatológica en esta eSpecie

Winckler Christoph - One of the best experts on this subject based on the ideXlab platform.

  • Single or mixed: Comparing behaviour of Single- and multi-Species groups of young cattle and broiler chickens on pasture
    2021
    Co-Authors: Schanz Lisa, Hintze Sara, Hübner Severin, Barth Kerstin, Winckler Christoph
    Abstract:

    The practice of keeping two or more Species together has received little attention in research. Here we present a first explorative study comparing behaviour on pasture in multi-Species groups of cattle and broiler chickens to Single-Species groups. In four 6-week cycles, two Single-Species groups (ten cattle and approximately 55 broilers, respectively)and one multi-Species group (ten cattle with approximately 55 broilers) were observed on pasture. Twice a week, once in the morning and once in the evening, ten animals per Species and group were directly observed using focal animal sampling for 6 minutes each. Behaviours including e.g. feeding, locomotion and interactions were recorded as frequencies or durations. Inter-observer-agreement between two independent observers was moderate to high. Due to the small sample size (n = 4 cycles) we present our results descriptively. Cattle in multi-Species groups spent on average 20 % ± 39 (mean, sd) of the time lying, while the percentage of lying time amounted to 30 % ± 42 in Single Species groups. Broilers in multi-Species groups were out of sight (i.e., in hut)for 16 % ± 32 of the time and broilers in Single-Species groups for 25 % ± 36. Cattle in multi-Species groups were feeding 63 % ± 41 (Single-Specie groups: 60 % ± 42), standing 9 % ± 2 (6 % ± 2) of their time and interacting with conspecifics 7 ± 13 (6 ± 13) times per hour. Broilers in multi-Species groups were lying 19 % ± 30 (Single Species groups: 14 % ± 29) and foraging 50 % ± 36 (48 % ± 36) of their time and performed comfort behaviour 2 ± 5 (1 ± 5)times per hour. While we cannot draw conclusions based on statistical differences, these first findings indicate that animals in mixed groups may influence the behaviour of the other Species. For example, broilers may perceive cattle as structural elements of the pasture and therefore spent more time outside and less time in the hut than broilers in Single-Species groups. Cattle in multi-Species groups may be lying less than cattle in Single-Species groups, due to the activity of the broilers. However, further research is necessary to confirm these first results and to investigate the reasons for such differences

Castellanos I., Giovanna Clarena - One of the best experts on this subject based on the ideXlab platform.

  • Estructura histológica normal de la piel del perro (estado del arte)
    Universidad de La Salle. Revistas. Revista de Medicina Veterinaria., 2017
    Co-Authors: Castellanos I., Giovanna Clarena, Rodríguez T. Gersain, Iregui C., Carlos Arturo
    Abstract:

    The skin is one of the largest organs of the body, and it has multiple functions: metabolic, temperature regulator, sensibility, and protection. The skin is formed by three layers: epidermis, dermis and hypodermis; the annexed ones are found in the dermis: hair follicles, sebaceous glands, sweat glands; the nails are found in the appendix. Although the skin structure in domestic animals is similar, there are variations among Species and even in a Single Specie related to epidermal thickness, dermal thickness, types and arrangements of hair follicles, and annexed structures. Knowing that Skin’s diseases are common in clinic practices in small animals, this article will review the normal histology structure of dog’s skin in order to know the changes in skin’s diseases in this Specie.La piel es uno de los órganos más extensos del cuerpo y cumple múltiples funciones: metabólicas, de termorregulación, sensibilidad y protección; está formada por tres capas: la epidermis, la dermis y la hipodermis; en la dermis se encuentran los anexos: folículos pilosos, glándulas sebáceas y glándulas sudoríparas; dentro de los apéndices se encuentran las uñas. Aunque la arquitectura de la piel en los animales domésticos es muy similar, existen variaciones entre eSpecies y aun dentro de un mismo individuo en cuanto al espesor de la epidermis y la dermis, las clases y la disposición de los folículos pilosos y las estructuras anexas. Teniendo en cuenta que las enfermedades dermatológicas son muy frecuentes en la práctica clínica con pequeños animales, en el presente artículo se revisan los aspectos histológicos normales de la piel del perro para poder comprender los cambios que ocurren en la enfermedad dermatológica en esta eSpecie