Near-Optimal Two-Pass Streaming Algorithm for Sampling Random Walks over Directed Graphs

For a directed graph G with n vertices and a start vertex u_start, we wish to (approximately) sample an L-step random walk over G starting from u_start with minimum space using an algorithm that only makes few passes over the edges of the graph. This problem found many applications, for instance, in approximating the PageRank of a webpage. If only a single pass is allowed, the space complexity of this problem was shown to be ??(n ? L). Prior to our work, a better space complexity was only known with O?(?L) passes. We essentially settle the space complexity of this random walk simulation problem for two-pass streaming algorithms, showing that it is ??(n ? ?L), by giving almost matching upper and lower bounds. Our lower bound argument extends to every constant number of passes p, and shows that any p-pass algorithm for this problem uses ??(n ? L^{1/p}) space. In addition, we show a similar ??(n ? ?L) bound on the space complexity of any algorithm (with any number of passes) for the related problem of sampling an L-step random walk from every vertex in the graph

Construction of the Initial Part of a Ion Linear Accelerator from Similar Short Cavities

The construction of the initial part of a normally conducting linac for hydrogen ion beams with a pulsed current of ~20 mA up to an energy of ~70 MeV is considered. The RFQ at a frequency of ~160 MHz accelerates ions to an energy of ~4 MeV. Further acceleration is carried out at a doubled frequency by short, up to $5\beta\lambda$, cavities, operating in the TM010 mode, with drift tubes. Focusing is carried out by doublets of quadrupole lenses placed between the cavities. The structure of the accelerating-focusing channel, with given beam parameters, with reserves provides both the conditions for stable longitudinal and transverse motion of particles, and reliable technical implementation. The main results of the simulations of particle dynamics and the main parameters of the elements of the channel are presented. The possibility of constructing an linac with a higher output energy is analyzed.Comment: in Russian languag

Fast Output Energy Regulation in a Medical Proton Linac

In proton therapy, depth scanning of the irradiated object is performed by changing the Output Energy (OE) of the accelerated beam. In pulsed linear accelerators, adjustment of the OE is usually by changing the amplitude and/or phase of the field in the accelerating elements from one RF pulse to another. The application of non-inertial traveling wave accelerating sections makes it possible to change quickly the phase of the accelerating field during the RF pulse. The phase of the field in the constant gradient section is determined both by the phase of the input RF signal and by the process of wave propagation in the dispersive structure. The calculation results of the traveling wave propagation in the accelerating structure when the phase of the input RF signal changes and the results of simulation the dynamics of particles confirm the change in the linac's OE during the RF pulse. The proposed method for regulation the OE makes it possible to increase in orders the speed of scanning the irradiated object by depth.Comment: in Russian languag

Human anti-D immunoglobulin preparations: potency standardisation milestones

Human anti-D immunoglobulin preparations derived from human immune plasma are much needed and highly effective for specific anti-D prevention of perinatal complications and treatment of primary immune thrombocytopenia. The effectiveness of immune suppression is a direct function of the active ingredient dose received with the medicinal product. To improve the accuracy of anti-D antibody quantification, it is recommended to use certified reference materials with values assigned in international units (IUs). The aim of this study was to analyse the main stages in the development of the international standards (ISs) for human anti-D immunoglobulin potency testing and to substantiate the need for a national standard for anti-Rho(anti-D) antibody quantification. The article describes the creation of the first and subsequent ISs, the procedure for establishing the IU equivalent for the anti-Rho(anti-D) antibody concentration, the characteristics of the raw materials and preparations used, and the anti-Rho(anti-D) antibody assay methods applied to certify the ISs. According to the study conclusions, it is necessary to develop and certify a national standard for the content of anti-Rho(anti-D) antibodies that will meet the requirements of the corresponding Russian regulations

Cord blood-derived neuronal cells by ectopic expression of SOX2 and c-MYC

The finding that certain somatic cells can be directly converted into cells of other lineages by the delivery of specific sets of transcrip- tion factors paves the way to novel therapeutic applications. Here we show that human cord blood (CB) CD133+ cells lose their hematopoietic signature and are converted into CB-induced neu- ronal-like cells (CB-iNCs) by the ectopic expression of the transcrip- tion factor Sox2, a process that is further augmented by the combination of Sox2 and c-Myc. Gene-expression analysis, immu- nophenotyping, and electrophysiological analysis show that CB- iNCs acquire a distinct neuronal phenotype characterized by the expression of multiple neuronal markers. CB-iNCs show the ability to fire action potentials after in vitro maturation as well as after in vivo transplantation into the mouse hippocampus. This system highlights the potential of CB cells and offers an alternative means to the study of cellular plasticity, possibly in the context of drug screening research and of future cell-replacement therapies

APPLICATION OF MATHEMATICAL METHOD PREDICTIONS FOR IDENTIFICATION OF PATTERNS RELATIONS MUTATIONS IN PROTEINS ENCEPHALITIS VIRUS AND A MANIFESTATION OF ITS PHENOTYPIC TRAITS

We studied the natural connections between the amino acid sequences of proteins C, prM, E and NS1 virus strains of tick-borne encephalitis (TBE) and their three phenotypic traits -neuroinvasiveness, thermal stability and thermoresistance. Coupling strength is assessed using measures of competitive sequence similarity of each strain with reference strains. For such purposes subsets of strain sections are chosen amino acid composition specifics of which can predict the value of a phenotypic trait of interest. The possibility to predict missing elements in data both in amino acid composition, and in target properties is demonstrated. The relationships between pairs of phenotypic traits of strains were evaluated

Comorbid disease in children and adolescents with perinatal HIV infection: A pilot study

Background. With the increased use of combination antiretroviral therapy, the mortality of people living with HIV has decreased significantly, which has led to an increase of comorbidity and secondary HIV-related pathology in both adults and also in children and adolescents living with HIV infection. The incidence of children and adolescents with HIV infection and those in the general population varies significantly.The aim. To assess the frequency and range of chronic comorbidities in children and adolescents with perinatal HIV infection Methods. We carried out an observational study. Data on the incidence of 161 children with perinatal HIV infection registered in the Irkutsk Regional AIDS Center were copied.Results. Overall incidence of tuberculosis (18633.5 per 100 000 children), diseases of the digestive system (24844.7 per 100 000 children), diseases of the eye and adnexa (28571.4 per 100 000 children), diseases of the nervous system (18012.4 per 100 000 children), mental and behavioral disorders (13,664.6 per 100 000 children) in children with perinatal HIV infection is the higher than in children of comparable age. The overall incidence values of the endocrine system diseases, eating and metabolic disorders, diseases of the ear and mastoid process, diseases of the circulatory system, diseases of the genitourinary system, as well as congenital disorders and chromosomal disorders in children and adolescents with and without perinatal HIV infection are comparable.Conclusion. The prevalence of diseases of the circulatory, respiratory and genitourinary systems in children with perinatal HIV infection is comparable to that in the corresponding population. Prevalence of tuberculosis, anemia, diseases of the gastrointestinal tract, diseases of the eye and adnexa, diseases of the nervous system, mental and behavioral disorders is higher compared to children not exposed to HIV

Some pharmacogenetic aspects of the <i>ABCB1</i> gene in lopinavir / ritonavir concentration variability in children with HIV infection: A pilot study

Polymorphic variants of the multidrug resistance gene (ABCB1 or MDR1) are associated with changes in the absorption and transport of drugs in the body. One of the substrates of the ABCB1 transporter is an antiretroviral drug from the class of protease inhibitors, lopinavir.   The aim. To research the effect of polymorphic variants C1236T and C3435T in the ABCB1 gene on the plasma concentration of lopinavir / ritonavir in children and adolescents living with HIV infection.   Methods. The genotypes of polymorphic variants of the ABCB1 gene were identified in 136 HIV infected children and adolescents; median age – 10 [7–12] years. The plasma concentration of lopinavir / ritonavir was measured from blood taken during the next scheduled appointment as part of dispensary observation at the Irkutsk Regional AIDS Centre using high performance liquid chromatography.   Results. The average duration of lopinavir/ritonavir use as part of an antiretroviral therapy was 55 months. Median viral load in patients was 1 [1–2.03] log 10  copies/ mL; the number of CD4 +  T cells – 38.36 %. The frequency of occurrence of the 3435T and 1236T alleles of the ABCB1 gene was ~50 %. In carriers of the 3435TT genotype, the median lopinavir concentrations 2 and 12 hours after drug intake were 5050.8 [3615.8–5847.7] and 2665.5 [216–4896.3] ng/mL, respectively. In carriers of the 1236TT genotype, median lopinavir concentrations 2 and 12 hours after drug intake were 4913.5 [3355.1–5733.7] and 3290.6 [159.1–4972.5] ng/mL, respectively.   Conclusions. The study did not reveal a significant relationship between the carriage of the C3435T and C1236T genotypes of the ABCB1 gene and the concentrations of lopinavir and ritonavir 2 and 12 hours after drug intake