Reprezentace znalostí v hlubokých neuronových sítích

Convolutional neural networks (CNNs) are known to outperform humans in numerous image classification and object detection tasks. They also excel at captioning, image segmentation, and feature extraction. CNNs are precise at recognition and generalize well, yet analyzing their decision-making process remains challenging. A means to study their internal knowledge representation provide the so-called heat maps and their variants like the saliency, SmoothGrad, and Grad-CAM maps. The techniques such as t-SNE, UMAP, and ivis can, on the other hand, help visualize the multi-dimensional features formed in different convolutional layers. Inspired by the results obtained when analyzing the capabilities of CNNs, we introduce two novel size-reduction algorithms: Iterative Top Cut and Iterative Feature Top Cut. Both algorithms successively remove the layers of a CNN starting from its top until a stopping criterion is activated. The stopping criteria involve the model's performance and the formed internal knowledge representation. In particular, the Iterative Top Cut method exceeds our expectations by shrinking some models, such as EfficientNetV2S, up to 3.15 times while preserving their accuracy on the Cars-196 dataset. Moreover, the algorithm generalizes well and proves to be stable. 1Při řešení mnohých úloh z oblasti klasifikace obrázků a detekce objektů překonávají konvoluční neuronové sítě (CNN sítě) lidské schopnosti. CNN sítě vynikají i při vytváření titulků, segmentaci obrázků a při extrakci příznaků. Modely CNN sítí jsou mimořádně přesné při rozpoznávání obrázků a extrahované znalosti dobře zobecňují, nicméně analýza jejich rozhodovacího procesu zůstává problematická. Vhodný prostředek k analýze interní reprezentace znalostí v CNN sítích představují takzvané "heat maps" (teplotní mapy) a jejich varianty, například typu "saliency maps" (charakteristické mapy), SmoothGrad a Grad-CAM. Techniky t-SNE, UMAP a ivis používané pro redukci dimenzionality pak podporují snadnou vizualizaci vícerozměrných příznaků vytvořených v jednotlivých kon- volučních vrstvách CNN sítí. Na základě výsledků získaných při vyhodnocování vlastností CNN modelů, jsme na- vrhli dva nové algoritmy pro prořezávání předučených CNN sítí: "Iterative Top Cut" a "Iterative Feature Top Cut". Oba algoritmy postupně odstraňují koncové vrstvy CNN sítí, dokud není aktivováno ukončovací kritérium algoritmu. Ukončovací kritéria berou v úvahu dosahovanou přesnost CNN sítě a kvalitu vytvořené interní reprezentace znalostí. Vynikajících výsledků dosahuje zejména metoda "Iterative Top Cut", která je schopná zredukovat velikost...Katedra teoretické informatiky a matematické logikyDepartment of Theoretical Computer Science and Mathematical LogicFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Lidar Mapping of Near-Surface Aerosol Fields

Near-surface atmospheric measurements over urban or industrial areas aimed at assisting the air-quality monitoring attain increasing societal significance due to the strong and direct impact of aerosol pollutions in the low troposphere on the human health. In this chapter, we present experimental results on lidar mapping of aerosol fields over the city of Sofia (Bulgaria), its suburbs and adjacent towns and villages, obtained during an extensive 7-month experimental campaign in 2015. The measurements are conducted by scanning observation zones in horizontal and vertical directions using lidar systems developed at the Institute of Electronics, Bulgarian Academy of Sciences. Based on the aerosol backscattering profiles retrieved at different azimuth or elevation angles, two-dimensional color-coded sector maps of the near-surface aerosol density are obtained, overlaid on the topological map of the Sofia region. The analysis of the lidar maps shows good correlation between the aerosol density distribution and the locations of important sources of aerosol pollutions in the zones of observation, such as city streets with intense traffic, industrial facilities, densely populated residential districts, etc. The results reported demonstrate that aerosol lidar mapping could be regarded as an effective approach for accurate and reliable determination of the density, spatial distribution, and temporal dynamics of close-to-ground aerosols, covering broad urban areas. Possibilities of incorporating synergistically lidar mapping technologies into municipal air-quality monitoring systems are also discussed

Chapter Lidar Mapping of Near-Surface Aerosol Fields

Near-surface atmospheric measurements over urban or industrial areas aimed at assisting the air-quality monitoring attain increasing societal significance due to the strong and direct impact of aerosol pollutions in the low troposphere on the human health. In this chapter, we present experimental results on lidar mapping of aerosol fields over the city of Sofia (Bulgaria), its suburbs and adjacent towns and villages, obtained during an extensive 7-month experimental campaign in 2015. The measurements are conducted by scanning observation zones in horizontal and vertical directions using lidar systems developed at the Institute of Electronics, Bulgarian Academy of Sciences. Based on the aerosol backscattering profiles retrieved at different azimuth or elevation angles, two-dimensional color-coded sector maps of the near-surface aerosol density are obtained, overlaid on the topological map of the Sofia region. The analysis of the lidar maps shows good correlation between the aerosol density distribution and the locations of important sources of aerosol pollutions in the zones of observation, such as city streets with intense traffic, industrial facilities, densely populated residential districts, etc. The results reported demonstrate that aerosol lidar mapping could be regarded as an effective approach for accurate and reliable determination of the density, spatial distribution, and temporal dynamics of close-to-ground aerosols, covering broad urban areas. Possibilities of incorporating synergistically lidar mapping technologies into municipal air-quality monitoring systems are also discussed

Blood parasite infections in a wild population of ravens (Corvus corax) in Bulgaria

Shurulinkov P, Spasov L, Stoyanov G, Chakarov N. Blood parasite infections in a wild population of ravens (Corvus corax) in Bulgaria. Malaria journal. 2018;17(33): 33.Background: Blood parasites have been studied intensely in many families of avian hosts, but corvids, a particularly cosmopolitan family, remain underexplored. Haemosporidian parasites of the common raven (Corvus corax) have not been studied, although it is the largest, most adaptable, and widespread corvid. Genetic sequence data from parasites of ravens can enhance the understanding of speciation patterns and specificity of haemosporidian parasites in corvids, and shed light how these hosts cope with parasite pressure. Methods: A baited cage trap was used to catch 86 ravens and a nested PCR protocol was used to amplify a 479 bp fragment of the haemosporidian cytochrome b gene from the samples. The obtained sequences were compared with the MalAvi database of all published haemosporidian lineages and a phylogenetic tree including all detected raven parasites was constructed. An examination of blood smears was performed for assessment of infection intensity. Results: Twenty blood parasite lineages were recovered from ravens caught in a wild population in Bulgaria. The prevalence of generalist Plasmodium lineages was 49%, and the prevalence of Leucocytozoon lineages was 31%. Out of 13 detected Leucocytozoon lineages six were known from different corvids, while seven others seem to be specific to ravens. A phylogenetic reconstruction suggests that Leucocytozoon lineages of ravens and other corvids are not monophyletic, with some groups appearing closely related to parasites of other host families. Conclusions: Several different, morphologically cryptic groups of Leucocytozoon parasites appear to infect corvids. Ravens harbour both generalist corvid Leucocytozoon as well as apparently species-specific lineages. The extraordinary breeding ecology and scavenging lifestyle possibly allow ravens to evade vectors and have relatively low blood parasite prevalence compared to other corvids

First survey on the invasive Pond slider (Trachemys scripta) in Bulgaria: historic development and current situation

Crvenouha kornjača (Trachemys scripta) postala je popularni ljubimac u Bugarskoj od 1990. Kroz godine sve veći broj jedinki zabilježen je i u divljini. Iako su negativni učinci na izvornim kornjače su opsežno studirao negdje drugdje, nema posebne studije (osim kratkih izvješća) obratili invaziju T. scripta u Bugarskoj. Ova studija se temelji na više od 25 godina praćenja na terenu i predstavlja prvi izvor detaljne informacije o raspodjeli Pond klizača u Bugarskoj. Ukupno 293 UTM (10 × 10 km) kvadrata sa staništa pogodna za slatkovodne kornjače ispitano. Prikupili smo 64 zapisa za 173 osoba, od 19 UTM kvadrata. Od svih promatranih osoba, samo dvije su od nominirati podvrste - ostatak pripada T. Š. elegans. U našem istraživanju je uočeno samo jednoga djeteta. Do danas nije uspješno leženja zabilježena, iako su registrirani uspješni overwinterings. Mi smo razgovarali o raznim mjere ublažavanja koje se moraju brzo pokrenut ograničiti buduće izdanje Ribnjak klizača i za uklanjanje ne-izvornih uzoraka s bugarskim ekosustava. Akcije su zahtijevali posebno da se izbjegne potencijalne epidemiološko događaja uzrokovanih parazitima s vrlo smrtonosnim učinkom na autohtonim vrstama. Takve pojave potencijalno mogu imati veći utjecaj na autohtone vrste kornjača jezerce od raznih oblika natjecanja s T. scripta.Pond sliders (Trachemys scripta) have become a popular pet in Bulgaria since 1990. Through the years a number of released specimens were observed in the wild. Although the negative effects on native turtles have been studied extensively elsewhere, no specific studies (besides brief reports) have addressed the invasion of T. scripta in Bulgaria. The present study is based on over 25 years of field monitoring and represents the first source of detailed information on the distribution of the Pond slider in Bulgaria. A total of 293 UTM (10×10 km) squares with habitats suitable for freshwater turtles were surveyed. We collected 64 records for 173 individuals, from 19 UTM squares. From all observed individuals, only two were from the nominate subspecies – the rest belong to T. s. elegans. In our study only one subadult was observed. To date no successful hatching has been recorded, although successful overwinterings have been registered. We discuss various mitigation measures that must be rapidly initiated to limit future release of Pond sliders and to remove the non-native specimens from the Bulgarian ecosystems. Actions are demanded especially to avoid the potential epizootic events caused by parasites with highly lethal effect on native species. Such outbreaks might potentially have greater impact on the native pond turtle species than various forms of competition with T. scripta

KINETIC MODELING ON AMIDE HYDROLYSIS, DRUG RELEASE AND MUCOSAL PERMEATION OF INDOMETHACIN IN THE COMPOSITION OF SELECTED SEMISOLID VEHICLES

The present study aims to reveal the role of a semi-solid vehicle in the composition of Indomethacin dosage forms for their physical and chemical stability, in vitro and ex vivo behavior. Three types of hydrogels and emulgels were prepared with gelling agents Methylcellulose 2%, Poloxamer 407 20% and Carbomer 940 1%. Each preparation was observed for physical and chemical stability at 5°C and 25°C within 3 months. Test formulations, along with USP standard Indomethacin gel and combined marked product Indextol,were subjected to in vitro drug release test and ex vivo permeation study, using porcine intestinal mucosa on Franz diffusion cell. A hypothesis was built to predict steady-state plasma concentration (Css) of Indomethacin for each formulation following mucosal administration. Results revealed sustained chemical stability of all emulgels for the period observed and significantly lower chemical stability of the corresponding hydrogels. Methylcellulose hydrogel (at both temperatures) and emulgel (at 25°C) showed signs of phase separation, while all other formulations kept their physical appearance for the duration of the study. Methylcellulose emulgel along with Poloxamer 407 hydrogel showed highest cumulative drug release in 12 hours (58.01% and 55.00%, respectively). Same formulations exhibited also highest drug permeation rate (Jss) through mucosa (10.55 µg.cm-2.h-1 and 13.20 µg.cm-2.h-1, respectively) and highest predicted value of plasma concentration (Css up to 100.49 µg.l-1 and 125.71 µg.l-1, respectively), whereas highest drug deposition in mucosal tissue was detected for Poloxamer 407 emulgel (2.1 mg.cm-3)

Neurotoxicity of cancer agents

Невротоксичните ефекти на химиотерапията се появяват относително често и са причина за модификация на дозата на медикаментите - дозолимитираща токсичност. Рискът от развитие на невротоксичност се увеличава с повишаване на приложената доза и за разлика от миелотоксичността (основния ограничаващ фактор при повечето химиотерапевтични режими), която може да бъде преодоляна с растежни фактори или трансплантация на костен мозък, няма стандартно поведение, което да я ограничи.Противотуморните препарати водят до два типа токсичност - периферна невротоксичност, състояща се основно от периферна невропатия и централна невротоксичност, която включва от незначителни когнитивни увреждания и дефицити до енцефалопатия с деменция или дори кома.Не съществуват утвърдени алгоритми за поведения и профилактика на невротоксичността, причинена от противотуморните препарати. Поведението основно се свежда до редукция на дозата или отлагане във времето на приложението, особено при пациенти, които са с по-висок риск от развитие на невротоксични странични ефекти. На този етап не съществуват невропротективни агенти, които се препоръчват за стандартна употреба при развитие на невротоксичност.Neurotoxic side effects of chemotherapy occur frequently and are often a reason to limit the dose of chemotherapy. Chemotherapy dosing is often limited due to a frequently occurring side effect of the treatment - neurotoxic. The risk of neurotoxicity is increased by the possibility of higher dose usage, since bone marrow toxicity (the major limiting factor in most chemotherapeutic regimens) can be overcome with growth factors or bone marrow transplantation.Chemotherapy may cause both peripheral neurotoxicity, consisting mainly of a peripheral neuropathy, and central neurotoxicity, ranging from minor cognitive deficits to encephalopathy with dementia or even coma. Neurotoxicity caused by the chemotherapy can be of two types - peripheral, mainly consisting of peripheral neuropathy and central, from minor cognitive deficits through encephalopathy with dementia to even coma.Data management and neuroprotective agents are still in discussion and there are no current accepted guidelines yet. Management mainly consists of cumulative dose-reduction or lower dose-intensities, especially in patients who are at higher risk to develop neurotoxic side effects. None of the specific neuroprotective agents can be recommended in daily practice for standard use at the moment, and further studies are needed to confirm their beneficial effects

Search for Single Top Production at LEP

Single top production in e+e- annihilations is searched for in data collected by the L3 detector at centre-of-mass energies from 189 to 209 GeV, corresponding to a total integrated luminosity of 634 pb-1. Investigating hadronic and semileptonic top decays, no evidence of single top production at LEP is obtained and upper limits on the single top cross section as a function of the centre-of-mass energy are derived. Limits on possible anomalous couplings, as well as on the scale of contact interactions responsible for single top production are determined