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Open access

Finica Ivanov

Reproductive Parameters of Porcellium Collicola (Verhoeff, 1907) and Trachelipus Arcuatus (Buddelund, 1885) (Crustacea: Isopoda: Oniscidea) in South Romania

Porcellium collicola (Verhoeff, 1907) and Trachelipus arcuatus (Budde-Lund, 1885) (Crustacea: Isopoda: Oniscidea) are two terrestrial isopod species inhabiting the leaf litter of oak forests in South Romania. This paper presents the size of reproductive females, fecundity (the number of eggs for a female for a brood), fertility (the number of larvae or mancas per female) and the relationship between the number of eggs or mancas per brood pouch and the total body length of pregnant females. In Porcellium collicola populations' reproductive females had a total body length of 3.3 to 7.3 mm, average fecundity was 18.60±7.10 eggs per female and average number of mancas per female was 10.29±8.05. In Trachelipus arcuatus the total body length of reproductive females was between 9.80 - 16.60 mm and the average number of eggs per brood per female was 55.60±21.71. A direct correlation between the size of pregnant females and fecundity and fertility was established for Porcellium collicola.

Open access

V. Ivanov

Abstract

The paper discusses the aspects of building a system for color light effects in homes of the future using a FPGA-based embedded microprocessor. It is also discussed some opportunities for further development in order to improve the conditions of life of the inhabitants of the homes of the future.

Open access

Vladimir N. Ivanov

Abstract

This paper discusses the development of a complex device for Traffic Light Control. The device is based on a PicoBlaze microprocessor embedded in Spartan6 FPGA. Its benefits for the purposes of transport flows management are discussed.

Open access

Gheorghe Duca, Maria Nedealcov and Ivanov Ivanov

Abstract

Although it is considered that the socio-economic impact over the last decades on surface water quality is significant, the role of changing regional climate that is manifested by the intensification of desertification process is crucial. In this context, it is important to know the current trends of change in total runoff of surface of surface waters in the context of increase of desertification degree of the regional climate attested in recent years

Open access

Kaspars Ivanovs

Abstract

During the last century a large portion of small and medium-sized rivers in Latvia were channelized, hydroelectric power stations were also built, which led to changes in the hydrodynamic conditions, geomorphological structure, as well as a change in the fish fauna. Fish are an integral part of any community in natural or man-made bodies of water. They actively participate in maintaining the system, balancing/equilibrium, energy, substance transformation and biomass production. They are able to influence other organisms in the ecosystem in which they live. The aim of the paper “Pike distribution and feeding comparisons in natural and historically channelized river sections” is to find out what pike feed on in different environments in Latvian rivers, such as natural and straightened river sections, as well as what main factors determine the composition of their food. Several points were assessed during the course of the study: the impact of environmental conditions on the feeding habits and the distribution of pike; the general feeding habits of predators in Latvian rivers; the feeding differences of predators in natural and straightened river sections; and lastly, rhithral and pothamal habitats were compared. The study was based on data from 2014 and 2015 on fish fauna monitoring. During the study, 347 pike were collected from 136 plots using electrofishing method.

Open access

V. Bobrovs and G. Ivanovs

Comparison of Different Modulation Formats and their Compatibility with WDM Transmission System

In the work, the intensity and phase modulation methods are compared for different versions of the wavelength division multiplexing (WDM) system. Binary and multilevel code formats are evaluated numerically, with OptSim simulation software at the bit rate of 10 and 40 Gbit/s, using long-fiber spans and dispersion compensation technique. The problems to be overcome at exploitation of multiterabit WDM systems based on 40 Gbit/s optical transmissions are: chromatic dispersion (CD), polarization-mode dispersion (PMD), dispersion slope, and nonlinear effects of the transmission line. We have investigated the potentialities of modulation formats for 40 Gbit/s WDM networks where most of the listed problems are avoided. It is shown that Duobinary and differential phase shift keying (DPSK) modulation formats are perfectly suitable for ultra-high spectral efficient WDM systems and possess high resistance to dispersion and nonlinear optical effects (NOE).

Open access

N.G. Ivanov, L. Gyuzelev and A. Boneva

Abstract

On the basis of an improved method of determining the combustibility of tobacco comprehensive investigations were carried out of factors which influence combustibility. On the strength of statistical studies of the correlations, the following conclusions were drawn:

1. The most precise unit of measurement of the combustion of tobacco leaf is the product of “duration of combustion” and “amount of substances burnt” (secs. × mg).

2. The mineral components influence combustibility variously, K2O positively, Cl-, Na2O, Fe2O3 and P2O5 negatively, whilst SO4- -, SiO2, CaO and MgO have no influence.

3. The coefficients of combustibility suggested up till now, which are based solely on the composition of the mineral components, demonstrate only a very weak correlation.

4. Isolated groups of organic substances demonstrate no incisive correlation to combustibility.

5. The concentration of all organic substances in the volume unit, the “substance density”, shows a high, negative correlation to combustibility; the “porosity” of the leaf is also clearly correlated to combustibility.

6. Combustibility is influenced by the combined action of part of the inorganic components, the concentration of organic substances in the volume unit and the porosity of the leaf. The combustibility index (C.I.), which was ascertained on the strength of these combined actions, seems to be the most suitable indicator of combustibility.

Open access

Savelina Popovska and Ivan Ivanov

Abstract

Objective: The aim of this study was to examine the relationship between the immunohistochemical subtypes of invasive breast cancer and lymphatic vascularization.

Material and Method: One hundred and seventy nine cases of randomly selected invasive breast cancer patients, surgically treated between 2004 and 2007, were retrospectively studied. These were classified into steroid receptor positive (steroid receptor positive/ HER2 negative), triple positive (steroid receptor and HER2 positive), triple negative (steroid receptor and HER2 negative) and HER2 overexpressing (steroid receptor negative /HER2 positive) carcinomas. Appropriate immunostaining and in-situ hybridization techniques were applied and results were statistically analyzed.

Results: The median intra-tumor lymphatic vascular density and the median intra-tumor relative lymphatic vascular area were found to differ significantly among the studied groups of breast cancer (KW =49.8611; p<0.0001 and KW =21.5122; p=0.0001 respectively). There was no significant difference in the incidence rate of axillary node involvement among the studied groups of breast cancer (χ2=1.66; Df=3; p=0.6460).

Conclusion: The present study indicates that HER2 overexpressing breast carcinomas have a consistent increase of intra-tumor lymphatic vessel counts as compared to all other subtypes. It is suggested that the newly formed vessels are probably not the only essential factor for lymphogenic spread of HER2 overexpressing breast carcinomas as they are not related to an increased incidence of lymph node metastases compared to the other studied subgroups.

Open access

Mitko Ivanov Nikolov

Abstract

The research is taken on the vibroarc welding apparatus ENTON-60 equipped with an axial non-inertial vibrator in argon shield. The criteria used for assessing the flow of the electric arc process and the formation of weld overlay clad surfaces are: short circuit voltage, voltage at the start of arc combustion, short circuit amperage, and amperage at the end of arc combustion. Wire electrode‘s vibrating frequency is considered as an input variable of the cybernetic model. It has been found that amplitude of vibrations has a significant impact on the vibroarc process - voltage parameters and welding current ratio, as the minimum amperage of short circuit and the lowest voltage at the start of arc combustion is realized at 2 mm amplitude of vibrations.

Open access

Krastyu Ivanov Krastev

Abstract

To meet the verification requirements of the Enforcement Principle, every training organization may verify the results of the conducted training. Our research hypothesis is that by implementation of the proper self-assessment methods the final results of the military advisors mission training could be more objective, than by using the “classical” assessment methodology containing only the marks of the combat training instructors. Some research results of the military advisors teams’ mission readiness level are presented in the following paper.