Analytic Perturbation Theory: A New Approach to the Analytic Continuation of the Strong Coupling Constant αS\alpha_S into the Timelike Region

The renormalization group applied to perturbation theory is ordinarily used to define the running coupling constant in the spacelike region. However, to describe processes with timelike momenta transfers, it is important to have a self-consistent determination of the running coupling constant in the timelike region. The technique called analytic perturbation theory (APT) allows a consistent determination of this running coupling constant. The results are found to disagree significantly with those obtained in the standard perturbative approach. Comparison between the standard approach and APT is carried out to two loops, and threshold matching in APT is applied in the timelike region.Comment: 16 pages, REVTeX, 7 postscript figure

On relativization of the Sommerfeld-Gamow-Sakharov factor

The Sommerfeld-Gamow-Sakharov factor is considered for the general case of arbitrary masses and energies. It is shown that the scalar triangular one-loop diagram gives the Coulomb singularity in radiative corrections at the threshold. The singular part of the correction is factorized at the complete Born cross section regardless of its partial wave decomposition. Different approaches to generalize the factor are discussed.Comment: 9 pages, 4 figures; references and discussion are extende

The Adler Function for Light Quarks in Analytic Perturbation Theory

The method of analytic perturbation theory, which avoids the problem of ghost-pole type singularities and gives a self-consistent description of both spacelike and timelike regions, is applied to describe the "light" Adler function corresponding to the non-strange vector channel of the inclusive decay of the $\tau$ lepton. The role of threshold effects is investigated. The behavior of the quark-antiquark system near threshold is described by using a new relativistic resummation factor. It is shown that the method proposed leads to good agreement with the ``experimental'' Adler function down to the lowest energy scale.Comment: 13 pages, one ps figure, REVTe

The Gross--Llewellyn Smith Sum Rule in the Analytic Approach to Perturbative QCD

We apply analytic perturbation theory to the Gross--Llewellyn Smith sum rule. We study the $Q^2$ evolution and the renormalization scheme dependence of the analytic three-loop QCD correction to this sum rule, and demonstrate that the results are practically renormalization scheme independent and lead to rather different $Q^2$ evolution than the standard perturbative correction possesses.Comment: 17 pages, 9 eps figures, REVTe

Infrared Properties of QCD from Dyson-Schwinger equations

I review recent results on the infrared properties of QCD from Dyson-Schwinger equations. The topics include infrared exponents of one-particle irreducible Green's functions, the fixed point behaviour of the running coupling at zero momentum, the pattern of dynamical quark mass generation and properties of light mesons.Comment: 47 pages, 19 figures, Topical Review to be published in J.Phys.G, v2: typos corrected and some references adde

Radiative corrections to the cross section of e−+p→ν+ne^-+p\to \nu+n and the crossed processes

Born cross section and the radiative corrections to its lowest order are considered in the frame work of QED with structureless nucleons including the emission of virtual and real photons. Result is generalized to take into account radiative corrections in higher orders of perturbation theory in the leading and next-to leading logarithmic approximation. Crossing processes are considered in the leading approximation.Comment: 11 pages, 1 figur

Тромботическая окклюзия у пациентов с острым ишемическим инсультом

Currently, reperfusion therapy is the main method of treating patients with ischemic stroke (IS). The safety and efficacy of systemic thrombolytic therapy with a recombinant tissue plasminogen activator in patients with IS within 3 hours, and then 4.5 hours after the onset of symptoms of the disease was demonstrated in the NINDS (1995) and ECASS III (2008) studies. In 2018, based on the results of five studies, clear indications were formulated for performing thrombectomy (TE) in patients with IS, which involve the detection of thrombosis of a large stroke-associated artery. Given the continuous growth in the number of the adult population, which constitutes the bulk of patients with IS, information on the prevalence of patients with thrombotic occlusion of cerebral arteries, who are potential candidates for TE, may be important for regional vascular centers.Aim of study. To describe IS patients admitted within the 6-hour “therapeutic window”.Materials and methods. The study included 145 patients with cerebral IS who were admitted within the first 6 hours after the onset of symptoms of the disease. All patients underwent computed tomographic (CT) angiography in order to verify the occlusion of the cerebral artery.Results. In our study, a correlation was established between the NIHSS severity of IS and the likelihood of verification of stroke-related artery thrombosis by CT angiography, but in 32.6% of patients with severe stroke (NIHSS at least score 14), no thrombotic occlusion was detected, and in 13% of patients with a clinic of mild acute cerebrovascular accident (NIHSS no more than 6), on the contrary, thrombotic occlusion was detected. Mortality in patients with verified thrombotic occlusion of the cerebral artery was higher than in patients without it (38% versus 10.5%, p<0.001). Such a significant difference in the mortality rate was due to the initially more severe stroke (NIHSS at admission 17 [10; 23] versus 5 [2; 10], p><0.001) in patients with thrombotic occlusion of a stroke-related artery, as well as a higher incidence of severe swallowing disorders (30% versus 9.5%, p ><0.002), which are a risk factor for pneumonia, as well as a higher frequency of such a comorbid background as chronic kidney disease and atrial fibrillation (30% versus 13.7%, p=0.018% and 58% versus 29.5%, p=0.001, respectively). CONCLUSION 1. Thrombosis of the cerebral stroke-associated artery was detected in 34.5% of patients with ischemic stroke who were admitted within the first 6 hours from the onset of the disease. 2. The main reason for the failure to perform thrombectomy in patients with ischemic stroke admitted within the 6-hour therapeutic window is the lack of verification of stroke-related artery thrombosis using computed tomographic angiography. Due to thrombosis at a different location (other than thrombosis of the internal carotid artery and / or M1 segment of the middle cerebral artery), 10% of patients with verified thrombosis did not meet the currently existing selection criteria for thrombectomy. Keywords: ischemic stroke, reperfusion therapy, cerebral artery thrombosis, cryptogenic stroke>˂0.001). Such a significant difference in the mortality rate was due to the initially more severe stroke (NIHSS at admission 17 [10; 23] versus 5 [2; 10], p˂0.001) in patients with thrombotic occlusion of a stroke-related artery, as well as a higher incidence of severe swallowing disorders (30% versus 9.5%, p˂0.002), which are a risk factor for pneumonia, as well as a higher frequency of such a comorbid background as chronic kidney disease and atrial fibrillation (30% versus 13.7%, p=0.018% and 58% versus 29.5%, p=0.001, respectively).Conclusion. 1. Thrombosis of the cerebral stroke-associated artery was detected in 34.5% of patients with ischemic stroke who were admitted within the first 6 hours from the onset of the disease. 2. The main reason for the failure to perform thrombectomy in patients with ischemic stroke admitted within the 6-hour therapeutic window is the lack of verification of stroke-related artery thrombosis using computed tomographic angiography. Due to thrombosis at a different location (other than thrombosis of the internal carotid artery and / or M1 segment of the middle cerebral artery), 10% of patients with verified thrombosis did not meet the currently existing selection criteria for thrombectomy. В настоящее время реперфузионная терапия является основным методом лечения пациентов с ишемическим инсультом (ИИ). Безопасность и эффективность системной тромболитической терапии при помощи рекомбинантного тканевого активатора плазминогена у пациентов с ИИ в пределах 3 часов, а в последующем 4,5 часа от начала симптомов заболевания была продемонстрирована в исследованиях NINDS (1995) и ECASS III (2008). В 2018 году, основываясь на результатах пяти исследований, были сформулированы четкие показания для выполнения тромбэктомии (ТЭ) у пациентов с ИИ, которые подразумевают выявление тромбоза крупной инсульт-связанной артерии. В условиях непрерывного роста числа взрослого населения, составляющего основную массу пациентов с ИИ, информация о распространенности больных с тромботической окклюзией церебральных артерий, являющихся потенциальными претендентами для выполнения ТЭ, может быть важной для региональных сосудистых центров.Цель исследования. Охарактеризовать пациентов с ИИ, поступающих в 6-часовом «терапевтическом окне».Материал и методы. В исследование включены 145 пациентов с церебральным ИИ, поступивших в первые 6 часов от начала развития симптомов заболевания. Всем пациентам с целью верификации окклюзии церебральной артерии выполняли компьютерную томографическую (КТ) ангиографию.Результаты. В нашем исследовании была установлена корреляция между тяжестью ИИ по шкале NIHSS и вероятностью верификации при помощи КТ-ангиографии тромбоза инсульт-связанной артерии, но у 32,6% пациентов с клиникой тяжелого инсульта (NIHSS не менее 14 баллов) не было выявлено тромботической окклюзии, а у 13% пациентов с клиникой легко протекающего острого нарушения мозгового кровообращения (NIHSS не более 6 баллов), напротив, тромботическая окклюзия была выявлена. Летальность у пациентов с верифицированной тромботической окклюзией церебральной артерии была статистически значимо выше, чем у пациентов без таковой (38% против 10,5%, р<0,001). Столь значительная разница между показателями летальности была обусловлена исходно более тяжелым инсультом (оценка по NIHSS при поступлении 17 [10; 23] против 5 [2; 10], p><0,001, статистически значимо) у больных с тромботической окклюзией инсульт-связанной артерии, а также большей частотой статистически значимых грубых расстройств глотания (30% против 9,5%, p><0,002, статистически значимо), являющихся фактором риска развития пневмонии и такого коморбидного фона, как хроническая болезнь почек и фибрилляция предсердий (30% против 13,7%, р=0,018 и 58% против 29,5%, р=0,001 соответственно). Выводы 1. Тромбоз церебральной инсульт-связанной артерии выявлен у 34,5% пациентов с ишемическим инсультом, поступающих в первые 6 часов от начала заболевания. 2. Основной причиной невыполнения тромбэктомии у пациентов с ишемическим инсультом, поступивших в 6-часовом «терапевтическом окне», является отсутствие верификации тромбоза инсульт-связанной артерии при помощи компьютерной томографической ангиографии. По причине тромбоза другой локализации (отличной от тромбоза внутренней сонной артерии и/или М1 сегмента средней мозговой артерии) 10% пациентов с верифицированным тромбозом не соответствовали существующим в настоящее время критериям отбора для выполнения тромбэктомии. Ключевые слова: ишемический инсульт, реперфузионная терапия, тромбоз мозговой артерии, криптогенный инсульт>˂ 0,001). Столь значительная разница между показателями летальности была обусловлена исходно более тяжелым инсультом (оценка по NIHSS при поступлении 17 [10; 23] против 5 [2; 10], p˂ 0,001, статистически значимо) у больных с тромботической окклюзией инсульт-связанной артерии, а также большей частотой статистически значимых грубых расстройств глотания (30% против 9,5%, p˂ 0,002, статистически значимо), являющихся фактором риска развития пневмонии и такого коморбидного фона, как хроническая болезнь почек и фибрилляция предсердий (30% против 13,7%, р=0,018 и 58% против 29,5%, р=0,001 соответственно).Выводы. 1. Тромбоз церебральной инсульт-связанной артерии выявлен у 34,5% пациентов с ишемическим инсультом, поступающих в первые 6 часов от начала заболевания. 2. Основной причиной невыполнения тромбэктомии у пациентов с ишемическим инсультом, поступивших в 6-часовом «терапевтическом окне», является отсутствие верификации тромбоза инсульт-связанной артерии при помощи компьютерной томографической ангиографии. По причине тромбоза другой локализации (отличной от тромбоза внутренней сонной артерии и/или М1 сегмента средней мозговой артерии) 10% пациентов с верифицированным тромбозом не соответствовали существующим в настоящее время критериям отбора для выполнения тромбэктомии.

Ten years of the Analytic Perturbation Theory in QCD

The renormalization group method enables one to improve the properties of the QCD perturbative power series in the ultraviolet region. However, it ultimately leads to the unphysical singularities of observables in the infrared domain. The Analytic Perturbation Theory constitutes the next step of the improvement of perturbative expansions. Specifically, it involves additional analyticity requirement which is based on the causality principle and implemented in the K\"allen--Lehmann and Jost--Lehmann representations. Eventually, this approach eliminates spurious singularities of the perturbative power series and enhances the stability of the latter with respect to both higher loop corrections and the choice of the renormalization scheme. The paper contains an overview of the basic stages of the development of the Analytic Perturbation Theory in QCD, including its recent applications to the description of hadronic processes.Comment: 26 pages, 9 figures, to be published in Theor. Math. Phys. (2007

The use of extra-budgetary education programmes for the purpose of increase of motivation of teachers of higher educational institutions

The article discusses the necessity of using extra-budgetary education programmes for the purpose of improving the incentives and remuneration of employees of higher educational institutions. Analyzed industry statistics. The authors propose a number of measures for the organization of extra-budgetary funding of the educational process and improvement of system of motivation of scientific and pedagogical workers

Incentives the work to teaching staff as the factor influencing the quality of the educational process

In the article considers the methods of to higher educational institutions teachers’ labor. Analyzed forms of incentives that improve the quality of teachers work. Conclusions are drawn about the need to match the motivational expectations of scientific and pedagogical workers to the methods of the higher educational institutions compensatory policy