Chemical and physical defense traits in two sexual forms of opuntia robusta in Central Eastern Mexico

Sexually dimorphic plants provide an excellent opportunity for examining the differences in the extent of their defense against herbivores because they exhibit sex-related differences in reproductive investment. Such differences enable comparison of the sex with high reproduction expenses with the sex that expends less. The more costly sex is usually also better defended against herbivores. Generally, females are considered more valuable than hermaphrodites in terms of fitness; however, hermaphrodites are more valuable if they can produce seed by autonomous selfing, provided that the inbreeding depression is low and pollen is limited. We studied a gynodioecious population of Opuntia robusta from Central-Eastern Mexico, which has been reported to be trioecious, dioecious, or hermaphrodite, and addressed the following questions: 1) Is the hermaphrodite's reproductive output higher than the female's, and are hermaphrodites thus better defended? 2) Are plant tissues differentially defended? 3) Do trade-offs exist among different physical defense traits? and 4) among physical and chemical defense traits? We found that 1) hermaphrodites had a higher seed output and more spines per areola than females and that their spines contained less moisture. Non-reproductive hermaphrodite cladodes contained more total phenolic compounds (TPCs) than female ones. In addition, 2) hermaphrodite reproductive cladodes bore more spines than female cladodes, and 3) and 4) we found a negative relationship between spine number per areola and areola number per cladode and a positive relationship between spine number per areola per plant and TPC concentration per plant. Non-reproductive hermaphrodite cladodes contained a higher concentration of TPCs than female cladodes, and parental cladodes contained fewer TPCs than both reproductive and empty cladodes

Badania eksperymentalne sił w drążkach kierowniczych

The article presents the methodology and results of the studies of forces in the steering rods in real traffic situations. The particular attention was paid to the drive through the roadside, which is lowered in relation to the roadway. Such a situation is dangerous due to the road safety, because when returning from the roadside to the roadway, the torque of the steering wheel, regulated by the power steering, is so small that it helps the driver to perform too great turn of the steering wheel, so that the car can be found on the lane of the opposite direction or it can leave the roadway. The aim of this paper was to identify the distribution of forces in the rods and to propose suitable reversing of the power steering system with the use of these forces.W artykule przedstawiono metodykę i wyniki badań sił w drążkach kierowniczych, w rzeczywistych sytuacjach drogowych. Szczególną uwagę zwrócono na przejazd przez obniżone względem jezdni pobocze gruntowe. Sytuacja taka jest groźna z punktu widzenia bezpieczeństwa ruchu drogowego, ponieważ przy powrocie z pobocza na jezdnię moment na kierownicy, regulowany przez wspomaganie, jest na tyle mały, że ułatwia kierowcy wykonanie zbyt dużego obrotu kierownicą, wskutek czego samochód może się znaleźć na pasie do jazdy w przeciwnym kierunku lub opuścić jezdnię. Celem pracy była identyfikacja rozkładu sił w drążkach i zaproponowanie odpowiedniego przesterowania układu wspomagania przy wykorzystaniu tych sił

Performance of an electromagnetic lead/scintillating-fibre calorimeter for the H1 detector

The properties of final modules of a high resolution lead/scintillating-fibre calorimeter to upgrade the backward region of the H1 detector were studied with electrons in the energy range from 2-60 GeV. The electromagnetic calorimeter consists of scintillating fibres with a diameter of 0.5 mm embedded in a lead matrix. This small fibre radius, in combination with a lead-to-fibre ratio of 2.27:1, ensures excellent energy resolution which has been measured to be #sigma#/E=7.1%/#sq root#(E/GeV)+1.0%. The spatial resolution as a function of energy for impact points at the center of a cell is given by 4.4 mm/#sq root#(E/GeV)+1.0 mm. The time resolution was found to be better than 0.4 ns. (orig.)12 refs.Available from TIB Hannover: RA 2999(95-165) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman