Cryopreservation of Pike Perch Sperm in Hatchery Conditions

Experiments were carried out on pike perch (Sander lucioperca L.) to find a method for stripping sperm without contamination by urine, to determine sperm concentration, and to fertilize large batches of eggs with cryopreserved sperm. Induced spawning technology for pike perch, an important predator fish species in Hungarian and central-eastern European pond aquaculture, has been developed only recently. Sperm cryopreservation can be an important tool for several reasons including the simplification of hatchery work and long-term preservation of genomes of males with high genetic value. In the present study, sperm was stripped without urine contamination, improving sperm quality, and large amounts of eggs were fertilized using 0.25 ml sperm, resulting in hatching percentages of 55±3% for 30-g batches of eggs and 87% for a 50-g batch

Cryopreservation of common carp sperm

Experiments were carried out to investigate the effect of five extenders (sucrose, glucose, fructose, KCl and a saline carp sperm extender) and two cryoprotectants (dimethyl-sulfoxide (DMSO) and methanol) on the cryopreservation of common carp sperm. Freezing of sperm using glucose extender and methanol as cryoprotectant resulted in the highest post-thaw motility, fertilization as well as hatching rates (63 ± 9%, 74 ± 15% and 67 ± 17% vs. 87 ± 5%, 84 ± 14% and 69 ± 14% using fresh sperm, respectively). In general, sugar-based extenders combined with methanol as cryoprotectant yielded higher motility, fertilization and hatching rates than ionic extenders in combination with DMSO. The jelly-like agglutination observed after thawing in samples frozen with sugar-based extenders did not reduce fertilization and hatching rates. Frozen–thawed sperm samples were able to successfully fertilize 10 g (8000) eggs

A magyarországi gazdálkodó szervezetek szoftverkörnyezetének empirikus vizsgálata

Ez a tanulmány egy kérdőíves felmérés eredményeire támaszkodva azt a kérdést vizsgálja, hogy a magyarországi gazdálkodó szervezetek üzleti tevékenységei milyen mértékben támogatottak különböző szoftveres megoldásokkal. A beérkezett 498 válasz egymástól jelentős mértékben eltérő mintázata és a szoftver-környezet egyes elemei között mutatkozó relatív alacsony korrelációja egy olyan, új értékelési rendszer kialakítását tette szükségessé. Az új elemzési eljárás képes az egyes gazdálkodó szervetek által rendszeresített szoftver-környezeteket a korábbi kutatásokban tapasztaltaknál részletesebben elemezni, de robosztus marad a válaszokban mutatkozó jelentős különbségekre. A korábban publikált elméleti eredményekre, valamint a kvantitatív kutatásokban bemutatott eljárások tapasztalataira építve ez az elemzési módszertan a feltáró faktorelemzésen (EFA) és a részben arra épülő konfirmatív faktorelemzésen (CFA) alapul. A kutatásomban igazolódott, hogy ezen mutatószám-rendszer be tudja tölteni más modellekben a magyarázó-változó szerepét, így objektív módon, kvantitatív eszközök segítségével mérhetővé vált az IKT-infrastruktúra az azt üzemeltető gazdálkodó szervezetekre gyakorolt hatása. Abstract: Based on the results of a questionnaire survey, the aim of this research is to investigate the extent to which the business activities of the for-profit organizations in Hungary are supported by various software solutions. The significantly different pattern of the 498 responses received and the relatively low correlation between each element of the software environment made necessary the development of a new evaluation system. The new method of analysis procedure can analyse the software environments for-profit organizations in Hungary more sophistically than in previous research, but it is robust for significant differences in the received answers of the questionnaire. Based on previously published theoretical results and methods used in quantitative research, this analytical methodology is based on the methods of exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). The research proved that this system of indicators can fulfil the role of an explanatory variable in other models, so the impact of the software-environment of the ICT infrastructure of the for-profit organizations in Hungary on their operators can be measured in an objective way, by using the quantitative tools

Ethnic Stereotypes and Preferences on Poverty Assistance

The authors introduce a simple model of public preferences on poverty assistance. Their focus is on the roles played by the socioeconomic status of a potential welfare recipient and the stereotypes about his/her ethnic group in shaping taxpayers’ preferences on appropriate assistance. The model assumes that status not only informs one about the recipient’s material needs but also sends noisy signals about his/her 'deservingness'. Ethnic stereotypes about work ethic, in turn, help to process those noisy signals. The authors show that the influence of stereotypes on welfare preferences tends to diminish as the status of a potential recipient approaches middle-class standards. Their model points to the potential of institutional and media framing of poverty assistance in the ethnicization of welfare preferences

Rotational and domain wall motion aftereffect in a patterned array of small particles

Aftereffect for magnetization processes by rotation and by domain wall motion was investigated on the same, single domain, two-state system of a square 2D (two-dimensional) array of garnet particles. Aftereffect measurements were performed magnetooptically. The particles are thermally stable, the particle energy is 10(-6) erg compared to the thermal energy of 10(-12) erg. No aftereffect of rotation switching of the system of "up" and "down" magnetized particles could be observed at room temperature. At increased temperatures thermally activated switching, very weakly depending on magnetic field, is observed. Each individual particle can be demagnetized into a metastable stripe domain structure. The barrier for DW (domain wall) motion is much lower than the barrier for rotation, and a significant aftereffect was measured on the same particles, demagnetized into a domain structure. The observed time dependence for DW aftereffect is exponential, M(t)/Ms=d* exp(-et), where d=0.04, and e=1/tau follows the increase of the magnetization with field, de/dH=0.021 /s/Oe

Investigation of the applicability of multi-operational logging machines in Hardwood stands

As a result of new developments in technology, harvesters may no longer be confined to softwood forests only. Several studies carried out in black locust, Turkey oak and beech stands have justified the use of these machines in hardwood stands. Evaluating the results of the cost and time analyses we concluded that harvesters are more efficient in several cases compared to traditional felling with chainsaws