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Frontiers of Computer Science 2024年第3期18卷 133-141页

作者： Yongjie YANG Dinko dimitrov Chair of Economic Theory Saarland UniversitySaarbrücken 66123Germany

We consider GROUP CONTROL BY ADDING INDIVIDUALS(GCAI)in the setting of group identification for two procedural rules-the consensus-start-respecting rule and the liberal-start-respecting *** is known that GCAI for both rules are NP-hard,but whether they are fixed-parameter tractable with respect to the number of distinguished individuals remained *** resolve both open problems in the *** addition,we strengthen the NP-hardness of GCAI by showing that,with respect to the natural parameter the number of added individuals,GCAI for both rules are W[2]-***,the W[2]-hardness for the liberal-startrespecting rule holds even when restricted to a very special case where the qualifications of individuals satisfy the so-called consecutive ones ***,for the consensus-startrespecting rule,the problem becomes polynomial-time solvable in this special *** also study a dual restriction where the disqualifications of individuals fulfill the consecutive ones property,and show that under this restriction GCAI for both rules turn out to be polynomial-time *** reductions for showing W[2]-hardness also imply several algorithmic lowerbounds.

关键词： group control by adding individuals group identification parameterized complexity consecutive ones property FPT W-hard

Approximations of the Fractional Integral and Numerical Solutions of Fractional Integral Equations

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Communications on Applied Mathematics and Computation 2021年第3期3卷 545-569页

作者： Yuri dimitrov Department of Mathematics and Physics University of Forestry1756 SofiaBulgaria Institute of Mathematics and Informatics Bulgarian Academy of Sciences1113 SofiaBulgaria

In the present paper,we derive the asymptotic expansion formula for the trapezoidal approximation of the fractional *** use the expansion formula to obtain approximations for the fractional integral of ordersα,1+α,2+α,3+αand 4+α.The approximations are applied for computation of the numerical solutions of the ordinary fractional relaxation and the fractional oscillation equations expressed as fractional integral equations.

关键词： Fractional integral Trapezoidal approximation Fractional integral equation Finite-difference scheme

EXISTENCE OF SOLUTIONS OF nTH-ORDER NONLINEAR DIFFERENCE EQUATIONS WITH GENERAL BOUNDARY CONDITIONS

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Acta Mathematica Scientia 2020年第1期40卷 226-236页

作者： Alberto CABADA Nikolay dimitrov Departamento de Estatística Análise Matemática e OptimizaciónInstituto de MatemáticasFacultade de MatemáticasUniversidade de Santiago de CompostelaSantiago de CompostelaGaliciaSpain Depatment of Mathematics University of RuseRuse 7000Bulgaria

The aim of this paper is to prove the existence of one or multiple solutions of nonlinear difference equations coupled to a general set of boundary *** to do this,we construct a discrete operator whose fixed points coincide with the solutions of the problem we are looking ***,we introduce a strong positiveness condition on the related Green's function that allows us to construct suitable cones where to apply adequate fixed point *** we have the general existence result,we deduce,as a particular case,the existence of solutions of a second order difference equation with nonlocal perturbed Dirichlet conditions.

关键词： difference equation multiplicity of solutions Green's function positive solutions parameter dependence

Statistical Estimation of the Shannon Entropy

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Acta Mathematica Sinica,English Series 2019年第1期35卷 17-46页

作者： Alexander BULINSKI Denis dimitrov Steklov Mathematical Institute of Russian Academy of Sciences and Department of Mathematics and Mechanics Lomonosov Moscow State UniversityMoscow 119234Russia

The behavior of the Kozachenko–Leonenko estimates for the(differential) Shannon entropy is studied when the number of i.i.d. vector-valued observations tends to infinity. The asymptotic unbiasedness and L^2-consistency of the estimates are established. The conditions employed involve the analogues of the Hardy–Littlewood maximal function. It is shown that the results are valid in particular for the entropy estimation of any nondegenerate Gaussian vector.

关键词： Shannon differential entropy Kozachenko-Leonenko estimates Hardy-Littlewood maxi-mal function analogues asymptotic unbiasedness and L^2-consistency Gaussian vectors

Noncanonical antibody strategy for broad and potent neutralization of influenza virus

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Cellular & Molecular Immunology 2021年第7期18卷 1615-1617页

作者： Jordan D.dimitrov Centre de Recherche des Cordeliers INSERMSorbonne UniversitéUniversitéde ParisF-75006ParisFrance

Pathogens with high levels of genetic variability,such as HIV-1 and influenza virus,evade the immune system by constantly changing their proteins vulnerable to neutralization by antibodies Consequently,these highly evolvable viruses are notoriously elusive targets for *** rare cases,infection of humans with HIV-1 or influenza virus results in production of antibodies that can neutralize a very broad spectrum of viral *** antibodies are referred to as broadly neutralizing.

关键词： influenza antibodies neutral

EXISTENCE OF SOLUTIONS OF NONLOCAL PERTURBATIONS OF DIRICHLET DISCRETE NONLINEAR PROBLEMS

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Acta Mathematica Scientia 2017年第4期37卷 911-926页

作者： Alberto CABADA Nikolay D.dimitrov Instituto de Matemdticas Facultade de MatemdticasUniversidade de Santiago de Compostela15782 Santiago de CompostelaSpain Department of Mathematical Analysis University of Rousse7017 RousseBulgaria

This paper is devoted to the study of second order nonlinear difference equations. A Nonlocal Perturbation of a Dirichlet Boundary Value Problem is considered. An exhaustive study of the related Green＇s function to the linear part is done. The exact expression of the function is given, moreover the range of parameter for which it has constant sign is obtained. Using this, some existence results for the nonlinear problem are deduced from monotone iterative techniques, the classical Krasnoselski fixed point theorem or by application of recent fixed point theorems that combine both theories.

关键词： Dirichlet boundary value problem nonlocal perturbations Green's function parameter dependence

Mechanochemical Synthesis and Characterization of Nanocrystalline Copper-Cobalt Ferrites

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Acta Metallurgica Sinica(English Letters) 2015年第3期28卷 367-372页

作者： Nikolay Velinov Dimitar dimitrov Kremena Koleva Krassimir Ivanov Ivan Mitov Institute of Catalysis Bulgarian Academy of Sciences Department of Chemistry Agricultural University

Nanocrystalline copper-cobalt ferrites with composition Cu_（1-x）Co_xFe_2O_4,where x = 0.2 and 0.8,were synthesized by mechanochemical treatment of co-precipitated *** ferrite powders were characterized by XRD and Mossbauer *** proved obtaining of spinel ferrites with crystallite size smaller than 10 *** of crystallite size of samples with increasing of mechanochemical treatment duration was established,*** properties of obtained ferrites were tested in reactions of oxidation of CO,methanol and dimethyl *** catalytic activity of nanocrystalline copper-cobalt ferrites toward CO and CH_3OH（about 100% conversions of CO and CH_3OH at 160 ℃）and moderate activity toward（CH_3）_2O oxidation were *** results obtained revealed that the Co/Cu atomic ratio is an important factor determinant the behavior of catalysts toward methanol and DME oxidation.

关键词： Mechanochemical synthesis Nanocrystalline Ferrites Mossbauer spectroscopy Catalysis

Microbial symphony orchestrated by mucosal IgA

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Cellular & Molecular Immunology 2022年第4期19卷 456-457页

作者： Alejandra Reyes-Ruiz Jordan D.dimitrov Centre de Recherche des Cordeliers INSERMCNRSSorbonne UniversitéUniversitéde Paris75006ParisFrance

The ability of an organism to handle the beauty and cruelty of existence is largely due to a complex network of molecular and cellular interactions and processes named the immune *** components of this network are antibodies(Abs)that have key roles in immune defense and *** biological functions of Abs include neutralizing pathogens by blocking functionally important molecules and/or to eliciting lethal effector functions by bridging the recognition of pathogens with binding to different innate immune receptors.

关键词： bridging neutral network

Cyclic patterns of incidence rate for skin malignant melanoma:association with heliogeophysical activity

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第6期9卷 489-495页

作者： Borislav D.dimitrov Mariana I.RACHKOVA Penka A.ATANASSOVA BORDANI Alzano Lombardo(BG)24022ItalyDepartment of Social Medicine and Health ManagementMedical UniversityPlovdiv 4000Bulgaria ASSON-93 Research Co. Mount ProspectILL 60056USA Department of Neurology Medical UniversityPlovdiv 4000Bulgaria

Background： Our previous studies revealed cyclicity in the incidence rate of skin malignant melanoma （SMM; ICD9, Dx： 172） in the Czech Republic （period T=7.50～7.63 years）, UK （T= 11.00 years） and Bulgaria （T= 12.20 years）. Incidences com- pared with the sunspot index Rz （lag-period dT=＋2, ＋4, ＋6, ＋ 10 or ＋ 12 years） have indicated that maximal rates are most likely to appear on descending slopes of the ;ll-year solar cycle, i.e., out of phase. We summarized and explored more deeply these cyclic variations and discussed their possible associations with heliogeophysical activity （HGA） components exhibiting similar cyclicity. Methods： Annual incidences of SMM from 5 countries （Czech Republic, UK, Bulgaria, USA and Canada） over various time spans during the years 1964-1992 were analyzed and their correlations with cyclic Rz （sunspot number） and aa （planetary geomagnetic activity） indices were summarized. Periodogram regression analysis with trigonometric approximation and phase-correlation analysis were applied. Results： Previous findings on SMM for the Czech Republic, UK and Bulgaria have been validated, and cyclic patterns have been revealed for USA （T=8.63 years, P〈0.05） and Canada （Ontario, T=9.91 years, P〈0.10）. Also, various ＇hypercycles＇ were established （T=45.5, 42.0, 48.25, 34.5 and 26.5 years, respectively） describing long-term cyclic incidence patterns. The association of SMM for USA and Canada with Rz （dT=＋6 and ＋7 years, respectively） and aa （dT=-10 and ＋9 years, respectively） was described. Possible interactions of cyclic non-photic influences （UV irradiation, Schumann resonance signal, low-frequency geomagnetic fluctuations） with brain waves absorbance, neuronal calcium dynamics, neuro-endocrine axis modulation, melatonin/serotonin disbalance and skin neuro-immunity impairment as likely causal pathways in melanoma appearance, were also discussed. Conclusion： The above findings on cyclicity and temporal association of SMM with cyclic environmental factors

关键词： Melanoma incidence Cyclicity Heliogeophysical activity (HGA) Forecasting Skin neurobiology