The Orevkov invariant of an affine plane curve

We show that although the fundamental group of the complement of an algebraic affine plane curve is not easy to compute, it possesses a more accessible quotient, which we call the Orevkov invariant.Comment: 20 page

Monoenergetic positron conversion in heavy ion fragments

Conversion processes in light nuclei with transition energies above the e+, e- pair creation threshold are investigated within an analytical framework. In particular, we evaluate the ratio of electron transition probabilities from the negative energy continuum into the atomic K shell and into the positive energy continuum, respectively. The possible role of monoenergetic positron conversion with respect to the striking peak structures observed in e+ spectra from very heavy collision systems is examined

Losing the error related negativity (ERN): an indicator for willed action

When people make errors in a discrimination task, a negative-going waveform can be observed in scalp-recorded EEG that has been coined the error-related negativity (ERN). We hypothesized that the ERN only occurs with slips, that is unwilled action errors, but not if an error is committed willingly and intentionally. We investigated the occurrence of the ERN in a choice reaction time task that has been shown to produce an ERN and in an error simulation task where subjects had to fake errors while the EEG was recorded. We observed a loss of the ERN when errors were committed in willed actions but not in unwilled actions thus supporting the idea that the production of the ERN is tied to slips in unwilled actions but not mistakes in willed actions

Genetic variability among Beauveria brongniartii (Saccardo) Petch isolates fromvarious geographical and host origins based on AFLP analysis

The entomopathogenic hyphomycete Beauveria brongniartii is a promising candidate for biocontrol of economically important agricultural and forest pests. Assessment of genetic relatedness of this species appears to be essential to gain insight into the monitoring of such biocontrol products. Distinction of Beauveria spp. strains with different virulence to target organisms revealed to be a serious constraint in the development of successful biocontrol using these important species. Thus, there is a need to find ways to monitor these strains when applied to natural agents. We have used amplified fragment length polymorphism (AFLPs) markers to estimate genetic variations among fourteen isolates (ten B. brongniartii, two B. bassiana (BALSAMO) VUILLEMIN and two Nomuraea rileyi (FARLOW) SAMSON) obtained from different geographical origins and hosts with differing virulence to scarabs. Seven different AFLP primer combinations yielded a total of 229 AFLP fragments comprised between 30 (EcoRI-ACA/Tru1l-C) to 57 (EcoRI-AAG/Tru1l-CTT) AFLP markers with an average of 54 amplified fragments per primer combination. Fragment size varied between 50-541 base pairs (bp) among the ten B. brongniartii isolates analysed in this study achieving a good resolution between the isolates. The cluster analysis based on genetic distance values clustered all isolates at above 0.40 similarity and demonstrated that some B. brongniartii isolates from distinct geographical origins and various hosts showed a greater genetic variability

Infestation levels of Varroa destructor in local honey bees of Jordan

To determine Varroa mite infestation levels in Jordan, a survey covering 180 colonies of two bee types (Apis m. syriaca and Apis m. syriaca hybrids) from six locations of 4 climatic zones was conducted during August, 8 month after the last treatment. Sampled colonies had 8-10 frames covered with bees and 3-4 brood frames. Levels of infestation were determined on both adult worker bees and in sealed worker brood cells. Two-way ANOVA showed no significant differences due to bee type with average adult bee infestation of 10.9 % and 13.1 % on hybrid and local bee types, respectively. Average infestation levels in sealed brood worker cells were 37.6 % and 32.5 % in hybrid and local bee types, respectively. Differences in infestation levels on adult bees were significant due to location and ranged between 6.9 - 18.6 % in Daba’a (Desert climate) and Jerash (Dry Mediterranean), respectively. In sealed worker brood cells infestation levels ranged between 15.7 - 84.7 % in Baqa (Dry Mediterranean) and Jerash, respectively. This indicates clearly that the usual scheduled Varroa control practice by a single chemical treatment in autumn could be insufficient. Therefore, to prevent damages or even losses of colonies, including diagnosis of infestation rates as part of integrated Varroa management is highly recommended

Reproduction of Varroa destructor in sealed worker bee brood cells of Apis mellifera carnica and Apis mellifera syriaca in Jordan

The reproduction of the honey bee mite, Varroa destructor in sealed worker bee brood cells represents an important factor for the population development of this parasite in honey bee colonies. In this study, the relative infestation levels of worker brood cells, mite fertility (mites that lay at least one egg) and reproductive rate (number of viable adult daughters per mother mite) of Varroa mite in worker brood cells of Apis m. carnica and Apis m. syriaca were compared in fall 2003 and summer 2004 at two locations in Jordan. The relative infestation levels in sealed worker brood cells ranged from 23 – 32 % in fall and 19 – 28 % in summer. The average fertility of Varroa mite ranged between 90 - 98% in colonies of A. m. carnica and between 88 - 96 % in A. m. syriaca with minor differences between colonies and locations. The number of total progeny of fertile mites in worker brood cells was 4.0 in both bee races. The reproductive rate was high with 2.7 and 2.6 in both honey bee races. The post-capping period of the worker brood cells differs only slightly between both bee races and between locations (284.4 h on average, n = 4,000). Our data reveal surprisingly high mite fertility and reproductive rates in both honeybee races under Mediterranean conditions of Jordan. The possible physiological background of Varroa reproduction and the impact of mite fertility on the development of Varroa tolerance are discussed