RESEARCH ON THE FRACTAL STATISTICAL CHARACTERISTICS AS POSSIBLE PROGNOSTIC PARAMETERS FOR EARTHQUAKES, GENERATED IN THE SEISMIC ZONE OF VRANCEA, IN THE PERIOD BETWEEN 01.08.2016 AND 30.12.2016

Using fractal analysis is an excellent alternative method for decode the seismic noise structure. Fractal analysis of microseismic noise could also be an appropriate method to detect earthquake indicators. The scientific goal is to detect standard signals, based on different earthquakes’ focal mechanisms, separating the "individual" behavior of the elements of the monitoring systems.The method for describing low-frequency microseismic noise from the network of seismic stations in a seismically active region of the Vrancea used. Seismic records of twenty-three broadband stations were analyzed, situated at distances of 20 to 500 km from the Vrancea earthquakes whit magnitudes Mw=5.7 and Mw=5.6 on September 23 and December 27, 2016, respectively. The daily assessment values of three multifractal parameters (characteristics of the multifractal singularity spectra of the waveform) from each station used for the description.The present paper is a continuation of previous work [Oynakov et al., 2019], where the effects of synchronization in the low-frequency microseismic field were found before the Vrancea earthquake with magnitude Mp=5.6 on October 28, 2019.The study shows that the noise coherence measure increased for stations, closer to the epicenter. However, the question of the source of this coherence remains open.Using fractal analysis is an excellent alternative method for decode the seismic noise structure. Fractal analysis of microseismic noise could also be an appropriate method to detect earthquake indicators. The scientific goal is to detect standard signals, based on different earthquakes’ focal mechanisms, separating the "individual" behavior of the elements of the monitoring systems.The method for describing low-frequency microseismic noise from the network of seismic stations in a seismically active region of the Vrancea used. Seismic records of twenty-three broadband stations were analyzed, situated at distances of 20 to 500 km from the Vrancea earthquakes whit magnitudes Mw=5.7 and Mw=5.6 on September 23 and December 27, 2016, respectively. The daily assessment values of three multifractal parameters (characteristics of the multifractal singularity spectra of the waveform) from each station used for the description.The present paper is a continuation of previous work [Oynakov et al., 2019], where the effects of synchronization in the low-frequency microseismic field were found before the Vrancea earthquake with magnitude Mp=5.6 on October 28, 2019.The study shows that the noise coherence measure increased for stations, closer to the epicenter. However, the question of the source of this coherence remains open

Probabilistic seismic hazard map for Bulgaria as a basis for a new building code

A seismic hazard map proposed as part of a new building code for Bulgaria is presented here on basis of the recommendations in EUROCODE 8. <P> Seismic source zones within an area of about 200 km around Bulgaria were constructed considering seismicity, neotectonic and geological development. The most time consuming work was to establish a homogeneous earthquake catalogue out of different catalogues. <P> The probabilistic seismic hazard assessment in terms of intensities is performed following Cornell (1968) with the program EQRISK (see McGuire, 1976), modified by us for use of intensities. To cope with the irregular isoseismals of the Vrancea intermediate depth earthquakes a special attenuation factor is introduced (Ardeleanu et al., 2005), using detailed macroseismic maps of three major earthquakes. <P> The final seismic hazard is the combination of both contributions, of zones with crustal earthquakes and of the Vrancea intermediate depth earthquakes zone. Calculations are done for recurrence periods of 95, 475 and 10 000 years

Pattern electroretinography as an objective method for study the visual analyzer function in patients with diabetes mellitus with initial diabetic retinopathy

Цел: Целта на нашето проучване е да се изследва обективно функцията на зрителния анализатор чрез патерна електроретинография (ПЕРГ) при пациенти със захарен диабет (ЗД) с начална диабетна ретинопатия (ДР) и получените резултати да се сравнят с контролната група, както и според типа на диабета.Материал и методика: Изследвана е група от 81 човека (162 очи), от които 47 здрави лица (контроли) - 94 очи. Пациентите със ЗД са 34 (68 очи), от които със ЗД тип 1 са 11 лица и 23 са с тип 2 ЗД. Извършена е ПЕРГ. Основните показатели, които са отчетени при анализа на резултатите са латентни времена и амплитуди, отразяващи се на конфиrурацията на вълновите форми.Резултати: При сравнителния анализ на стойностите на компонентите на ПЕРГ с контролната група, както и според типа ЗД, се установиха значителни различия. При сравнителния анализ на стойностите на компонентите на ПЕРГ между пациенти със ЗД с ДР и контроли се установи, че двете групи статистически се различават по амплитудите на всички компоненти на ПЕРГ при всички отвеждания при 15o и 30o.При латентностите сигнификантни различия се установиха при компонент Р50 при всички отвеждания при 15o и 30o. Пациентите със ЗД имат сигнификантно по-удължени латентности и по-ниски амплитуди, в сравнение с контролната група. При сравнителния анализ според типа ЗД, сигнификантни различия се получиха при амплитуден компонент P50-N95 при 15o и30o при дясно око, което потвърждава асиметричното засягане на очите при ЗД. Амплитудите на ПЕРГ при ЗД тип 2 са сигнификантно по-ниски от тези на пациентите със ЗД тип 1.Заключение: ПЕРГ би могла да се използва като обективен метод за регистриране на ранни изменения във функцията на зрителния анализатор (ЗА) като усложнение на З)J,. Също така и за проследяване на промените в динамика, тъй като изследването е неинвазивно, безвредно, по-бързо, повторяемо и обективно, по-евтино в сравнение с флуоресцеиновата ангиография (ФА), оптината кохерентна томография (ОСТ) и ангио-ОСТ.Aim: The aim of the study was to examine objectively the visual analyzer function by pattern electroretinography (PERG) in patients with diabetes mellitus (DM) with initial diabetic retinopathy (DR) and to compare the results with the control group as well as according to the type of diabetes. Material and methods: A group of 81 people (162 eyes) were studied. Patients with DM were 34 (68 eyes), 11 patients with type 1 DM and 23 with type 2 DM. The control group consisted of 47 healthy individuals (94 eyes). PERG was performed. The main variables that were considered in the results analysis were the latency and amplitudes, reflecting the configuration of the wave forms.Results: The comparative analysis of PERG components between patients with DM with DR and controls as well as according to the type of DM demonstrated significant differences. In latencies, significant differences were found for component P50 at all electrode positions at 15o and 30o. Patients with DM had significantly longer latencies and lower amplitudes compared to the control group. In the comparative analysis according to the type of DM, significant differences were found in amplitude component P50-N95 at 15o and 30o in the right eye, which confirms the asymmetrical eye involvement in DM. The PERG amplitudes in type 2 DM were significantly lower than those of type 1 DM patients.Conclusion: PERG could be used as an objective method for registration of early changes in the visual analyzer function as a DM complication. Also, to monitor the changes in dynamics as it is non-invasive, harmless, faster, and less expensive than fluorescein angiography (FA), OCT and angio-OCT

Association of the coronary artery disease risk gene GUCY1A3 with ischaemic events after coronary intervention

Aim: A common genetic variant at the GUCY1A3 coronary artery disease locus has been shown to influence platelet aggregation. The risk of ischaemic events including stent thrombosis varies with the efficacy of aspirin to inhibit platelet reactivity. This study sought to investigate whether homozygous GUCY1A3 (rs7692387) risk allele carriers display higher on-aspirin platelet reactivity and risk of ischaemic events early after coronary intervention. Methods and results: The association of GUCY1A3 genotype and on-aspirin platelet reactivity was analysed in the genetics substudy of the ISAR-ASPI registry (n = 1678) using impedance aggregometry. The clinical outcome cardiovascular death or stent thrombosis within 30 days after stenting was investigated in a meta-analysis of substudies of the ISAR-ASPI registry, the PLATO trial (n = 3236), and the Utrecht Coronary Biobank (n = 1003) comprising a total 5917 patients. Homozygous GUCY1A3 risk allele carriers (GG) displayed increased on-aspirin platelet reactivity compared with non-risk allele (AA/AG) carriers [150 (interquartile range 91–209) vs. 134 (85–194) AU⋅min, P 203 AU⋅min; 29.5 vs. 24.2%, P = 0.02). Homozygous risk allele carriers were also at higher risk for cardiovascular death or stent thrombosis (hazard ratio 1.70, 95% confidence interval 1.08–2.68; P = 0.02). Bleeding risk was not altered. Conclusion: We conclude that homozygous GUCY1A3 risk allele carriers are at increased risk of cardiovascular death or stent thrombosis within 30 days after coronary stenting, likely due to higher on-aspirin platelet reactivity. Whether GUCY1A3 genotype helps to tailor antiplatelet treatment remains to be investigated

Temporal characteristics of some aftershock sequences in Bulgaria

We apply statistical analysis to study the temporal distribution of aftershocks in aftershock sequences of five earthquakes which occurred in Bulgaria. We use the maximum likelihood method to estimate the parameters of the modified Omori formula for aftershock sequences which is directly based on a time series. We find that: the maximum likelihood estimates of the parameter p show a regional variation, with lower values of the decay rate in North Bulgaria; the modified Omori formula provides an appropriate representation of temporal variation of the aftershock activity in North Bulgaria; the aftershock sequences in South Bulgaria are best modeled by the combination of an ordinary aftershock sequence with secondary aftershock activity. A plot of the cumulative number of events versus the frequency-linearized time t clearly demonstrates a transition from aftershock to foreshock activity prior to the second 1986 Strazhitsa (North Bulgaria) earthquake

Seismic hazard assessment for the Sofia area

The capital of Bulgaria, Sofia, is situated in the center of the so-called Sofia area. This is the most populated industrial and cultural region of Bulgaria that faces considerable earthquake risk. We apply a version of machine code EQRISK for hazard assessment of the Sofia area according to the Cornell-McGuire approach. The probabilistic seismic hazard analysis is based on a simplified seismogenic model, which is derived from seismic zoning of Bulgaria. We show, using a Monte Carlo approach, that uncertainties in seismic input have a relatively small effect on the PSHA output, especially when compared with uncertainties associated with the attenuation relationship. Our PSHA map shows that a 103 annual probability of the PGA exceeds 0.3 g in much of the Sofia are

Temporal characteristics of some aftershock sequences in Bulgaria

We apply statistical analysis to study the temporal distribution of aftershocks in aftershock sequences of five earthquakes which occurred in Bulgaria. We use the maximum likelihood method to estimate the parameters of the modified Omori formula for aftershock sequences which is directly based on a time series. We find that: the maximum likelihood estimates of the parameter p show a regional variation, with lower values of the decay rate in North Bulgaria; the modified Omori formula provides an appropriate representation of temporal variation of the aftershock activity in North Bulgaria; the aftershock sequences in South Bulgaria are best modeled by the combination of an ordinary aftershock sequence with secondary aftershock activity. A plot of the cumulative number of events versus the frequency-linearized time t clearly demonstrates a transition from aftershock to foreshock activity prior to the second 1986 Strazhitsa (North Bulgaria) earthquake

Seismic hazard assessment for the Sofia area

The capital of Bulgaria, Sofia, is situated in the center of the so-called Sofia area. This is the most populated industrial and cultural region of Bulgaria that faces considerable earthquake risk. We apply a version of machine code EQRISK for hazard assessment of the Sofia area according to the Cornell-McGuire approach. The probabilistic seismic hazard analysis is based on a simplified seismogenic model, which is derived from seismic zoning of Bulgaria. We show, using a Monte Carlo approach, that uncertainties in seismic input have a relatively small effect on the PSHA output, especially when compared with uncertainties associated with the attenuation relationship. Our PSHA map shows that a 10–3 annual probability of the PGA exceeds 0.3 g in much of the Sofia are