Modelling of railway ballast and sub-ballast layers structure and properties considering ambient air factors and train traffic load

Disertacijos darbo aktualumas yra susijęs su sistemos „riedmuo–kelias“ esamų skaitinių modelių ir projektavimo normų tobulinimu. Rengiant darbą buvo kompleksiškai ištirtos geležinkelio kelio konstrukcijai įrengti naudojamų mineralinių medžiagų fizinės ir mechaninės savybės. Kiekybiškai įvertinta technologinių procesų įtaka šių savybių kaitai. Nustatytos atskirų geležinkelio kelio konstrukcijos sluoksnių savybės veikiant didžiausiai riedmenų ašies apkrovai ir skirtingai aplinkos oro temperatūrai bei drėgmei. Šiam tikslui pasiekti išanalizuoti mokslo darbai, atliktas skaitinis modeliavimas ir eksperimentiniai tyrimai. Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai, santrauka anglų kalba ir 7 priedai. Įvadiniame skyriuje pateikta tiriamoji problema, darbo aktualumas ir tyrimų objektas. Formuluojamas darbo tikslas ir uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos. Pirmajame skyriuje išanalizuoti mokslo darbai, susieti su geležinkelio kelio konstrukcijai įrengti naudojamų medžiagų savybėmis ir jų įtaka geležinkelio kelio konstrukcijos eksploataciniams rodikliams. Nagrinėjami sistemos „riedmuo–kelias“ modeliai ir destruktyviųjų veiksnių įtaka geležinkelio kelio konstrukcijos eksploataciniams rodikliams. Aptariami naudojami būdai ir priemonės, skirti išlaikyti ir atstatyti geležinkelio kelio konstrukcijos eksploatacinius rodiklius. Antrajame skyriuje pateikiamas aplinkos oro veiksnių įtakos geležinkelio kelio konstrukcijos elgsenai nustatymo ir vertinimo metodas. Sudaryti geležinkelio kelio konstrukcijos hidroterminio režimo ir riedmenų apkrovų įtakos geležinkelio kelio konstrukcijai skaitiniai modeliai. Trečiajame skyriuje pateikiami eksperimentinių tyrimų, kurių metu buvo ištirtos geležinkelio kelio konstrukcijai įrengti naudojamų mineralinių medžiagų fizinės ir mechaninės savybės, rezultatai. Šiame skyriuje pateikiami geležinkelio kelio konstrukcijose vykstančių fizikinių procesų ir geležinkelio kelio deformacijų rezultatai. Sukurti skaitiniai modeliai ir iš jų gauti rezultatai leidžia patobulinti jau esamus skaitinius modelius ir patikslinti geležinkelio kelio projektavimo metodiką, kurioje įvertinta daugiau destruktyviųjų veiksnių. Disertacijos tema paskelbti 4 straipsniai: vienas – mokslo žurnale, įtrauktame į Thomson Reuters Web of Science duomenų bazę ir turinčiame citavimo rodiklį, du – mokslo žurnaluose, referuojamuose kitų tarptautinių duomenų bazių leidiniuose, vienas – tarptautinės konferencijos leidinyje, referuojamame Thomson Reuters duomenų bazėje Proceedings

RhoA Drives T-Cell Activation and Encephalitogenic Potential in an Animal Model of Multiple Sclerosis

T-cells are known to be intimately involved in the pathogenesis of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). T-cell activation is controlled by a range of intracellular signaling pathways regulating cellular responses such as proliferation, cytokine production, integrin expression, and migration. These processes are crucial for the T-cells’ ability to mediate inflammatory processes in autoimmune diseases such as MS. RhoA is a ubiquitously expressed small GTPase well described as a regulator of the actin cytoskeleton. It is essential for embryonic development and together with other Rho GTPases controls various cellular processes such as cell development, shaping, proliferation, and locomotion. However, the specific contribution of RhoA to these processes in T-cells in general, and in autoreactive T-cells in particular, has not been fully characterized. Using mice with a T-cell specific deletion of the RhoA gene (RhoAfl/flLckCre+), we investigated the role of RhoA in T-cell development, functionality, and encephalitogenic potential in EAE. We show that lack of RhoA specifically in T-cells results in reduced numbers of mature T-cells in thymus and spleen but normal counts in peripheral blood. EAE induction in RhoAfl/flLckCre+ mice results in significantly reduced disease incidence and severity, which coincides with a reduced CNS T-cell infiltration. Besides presenting reduced migratory capacity, both naïve and autoreactive effector T-cells from RhoAfl/flLckCre+ mice show decreased viability, proliferative capacity, and an activation profile associated with reduced production of Th1 pro-inflammatory cytokines. Our study demonstrates that RhoA is a central regulator of several archetypical T-cell responses, and furthermore points toward RhoA as a new potential therapeutic target in diseases such as MS, where T-cell activity plays a central role

Determination and evaluation of railway aggregate sub-ballast gradation and other properties variation

The use of high quality aggregate mixture, proper technological parameters of laying and compacting as well as the required thickness of the mixture ensures railway sub-ballast layer properties. In this paper gradation, den­sity and water permeability of 49 produced random samples of aggregate sub-ballast (ASB) mixture which were taken from the stockpile in the plant and from the uncompacted railway layer are investigated. The statistical parameters of the ASB mixture quality indicators and histograms with theoretical curves of normal distribution are presented as well. Their conformity to normal distribution was tested through the use of skewness, kurtosis, Pearson, Shapiro-Wilk and Kolmogorov-Smirnov methods. Regression analysis was employed to determine the dependence of standard deviation of percent passing on the mean percent passing through the sieves. In this paper a new method of determining the homo­geneity of ASB according to the variation of gradation using the maximum standard deviation value of this dependence was employed. The minimum size n was calculated with the permissible relative error of 5%, 10%, 15% and 20%. The obtained research findings revealed that due to segregation processes the homogeneity of ASB mixture from the point of its production to application has decreased by about 38%. First published online: 20 Apr 201

DNMT1 regulates expression of MHC class I in post-mitotic neurons

Abstract Major Histocompability Complex I (MHC-I) molecules present cellularly derived peptides to the adaptive immune system. Generally MHC-I is not expressed on healthy post-mitotic neurons in the central nervous system, but it is known to increase upon immune activation such as viral infections and also during neurodegenerative processes. MHC-I expression is known to be regulated by the DNA methyltransferase DNMT1 in non-neuronal cells. Interestingly DNMT1 expression is high in neurons despite these being non-dividing. This suggests a role for DNMT1 in neurons beyond the classical re-methylation of DNA after cell division. We thus investigated whether DNMT1 regulates MHC-I in post-mitotic neurons. For this we used primary cultures of mouse cerebellar granule neurons (CGNs). Our results showed that knockdown of DNMT1 in CGNs caused upregulation of some, but not all subtypes of MHC-I genes. This effect was synergistically enhanced by subsequent IFNγ treatment. Overall MHC-I protein level was not affected by knockdown of DNMT1 in CGNs. Instead our results show that the relative MHC-I expression levels among the different MHC subtypes is regulated by DNMT1 activity. In conclusion, we show that while the mouse H2-D1/L alleles are suppressed in neurons by DNMT1 activity under normal circumstances, the H2-K1 allele is not. This finding is particularly important in two instances. One: in the context of CNS autoimmunity with epitope presentation by specific MHC-I subtypes where this allele specific regulation might become important; and two: in amyotropic lateral sclerosis (ALS) where H2-K but not H2-D protects motor neurons from ALS astrocyte-induced toxicity in a mouse model of ALS

Research of distorted vehicle magnetic signatures recognitions, for length estimation in real traffic conditions

Reliable cost-effective traffic monitoring stations are a key component of intelligent transportation systems (ITS). While modern surveillance camera systems provide a high amount of data, due to high installation price or invasion of drivers’ personal privacy, they are not the right technology. Therefore, in this paper we introduce a traffic flow parameterization system, using a built-in pavement sensing hub of a pair of AMR (anisotropic magneto resistance) magnetic field and MEMS (micro-electromechanical system) accelerometer sensors. In comparison with inductive loops, AMR magnetic sensors are significantly cheaper, have lower installation price and cause less intrusion to the road. The developed system uses magnetic signature to estimate vehicle speed and length. While speed is obtained from the cross-correlation method, a novel vehicle length estimation algorithm based on characterization of the derivative of magnetic signature is presented. The influence of signature filtering, derivative step and threshold parameter on estimated length is investigated. Further, accelerometer sensors are employed to detect when the wheel of vehicle passes directly over the sensor, which cause distorted magnetic signatures. Results show that even distorted signatures can be used for speed estimation, but it must be treated with a more robust method. The database during the real-word traffic and hazard environmental condition was collected over a 0.5-year period and used for method validation.Lietuvos Mokslo Taryba | Ref. S-MIP-21-3

High-speed multiplane structured illumination microscopy of living cells using an image-splitting prism

Descloux A, Mueller M, Navikas V, et al. High-speed multiplane structured illumination microscopy of living cells using an image-splitting prism. Nanophotonics. 2020;9(1):143-148.Super-resolution structured illumination microscopy (SR-SIM) can be conducted at video-rate acquisition speeds when combined with high-speed spatial light modulators and sCMOS cameras, rendering it particularly suitable for live-cell imaging. If, however, three-dimensional (3D) information is desired, the sequential acquisition of vertical image stacks employed by current setups significantly slows down the acquisition process. In this work, we present a multiplane approach to SR-SIM that overcomes this slowdown via the simultaneous acquisition of multiple object planes, employing a recently introduced multiplane image splitting prism combined with highspeed SIM illumination. This strategy requires only the introduction of a single optical element and the addition of a second camera to acquire a laterally highly resolved 3D image stack. We demonstrate the performance of multiplane SIM by applying this instrument to imaging the dynamics of mitochondria in living COS-7 cells