ABSTRACT
The paper addresses the problem of a systematic frequency error occurring in semiconductor-laser frequency-synchronization circuits based on counting the beat note between the two lasers in a reference time interval using a high-frequency prescaler. Such synchronization circuits are suitable for operation in ultra-precise fiber-optic time-transfer links, used e.g. in time/frequency metrology. The error occurs when the power of the light coming from the reference laser, to which the second laser is synchronized, is below about -50 dBm to -40 dBm, depending on the details of particular circuit implementation. The error can reach tens of MHz if left out of consideration and does not depend on the frequency difference between the synchronized lasers. Its sign can be positive or negative, depending on the spectrum of the noise at the prescaler input and the frequency of the measured signal. In the paper we present the background of the systematic frequency error, discuss important parameters allowing for predicting the error value, and describe the simulation and theoretical models being helpful for designing and understanding operation of discussed circuits. The theoretical models presented here show good agreement with the experimental data, which demonstrates the usefulness of proposed methods. Implementing polarization scrambling to mitigate the effect of polarization misalignment of the lights of the lasers used was considered and the resulting penalty was determined.
ABSTRACT
Dermacentor reticulatus is widely distributed dangerous tick that usually lives in the river valleys, boggy forests, meadows, and wooded pastures. Tick populations from various regions may exhibit morphological differences. In our study we compared morphometric features of tarsus in larvae D. reticulatus from Polish and Slovakian populations. I tarsus width, III tarsus length, and length of dorsal setae of I tarsus were significantly higher in Polish populations. Indices of width to length of tarsus I and tarsus III were also significantly different in both populations. The other examined morphologic features were similar, what may result from the same environmental conditions of both populations.
Subject(s)
Dermacentor/anatomy & histology , Dermacentor/classification , Larva/anatomy & histology , Tarsus, Animal/anatomy & histology , Tarsus, Animal/parasitology , Animals , Host-Parasite Interactions , Larva/classification , Phenotype , Poland , Rabbits , Slovakia , Species Specificity , Weights and MeasuresABSTRACT
Light microscopy and scanning electron microscopy (SEM) studies show the differences in structure, number and topography of terminal setae in the palpal organ in different stages of Hyalomma marginatum marginatum Koch, 1844. The palpal organ contains eight terminal setae in larvae and nymphs, and ten setae in adults. The length of these setae increases in the course of post-embryonic development. Other setae on palpal segments also undergo quantitative and morphological changes.
Subject(s)
Ixodidae/ultrastructure , Sense Organs/ultrastructure , Animals , Insect Vectors , Ixodidae/growth & development , Larva/ultrastructure , Microscopy, Electron , Nymph/ultrastructureABSTRACT
Light and scanning electron microscopic studies showed the differences in morphology and in size of Haller's organ in larvae, nymphs and adults (females and males) of Hyalomma marginatum marginatum Koch, 1844. The length of the anterior pit setae increases during post-embryonic development. The localization of these setae is the same in all stages. Six setae (one porose seta, two grooved setae, two fine setae, one conical seta) contain anterior pit of various developmental stages. In nymphs and adults more numerous pores appear on the wall surface of porose seta than in the larval stage. The structure of the capsule roof also differs in various developmental stages. Haller's organ of Hyalomma m. marginatum shows great degree of morphological development which is connected with the complicated life cycle and feeding behaviour of this tick species.
