Heavy- to light-meson transition form factors

Semileptonic heavy -> heavy and heavy -> light meson transitions are studied as a phenomenological application of a heavy-quark limit of Dyson-Schwinger equations. Employing two parameters: E, the difference between the mass of the heavy meson and the effective-mass of the heavy quark; and Lambda, the width of the heavy-meson Bethe-Salpeter amplitude, we calculate f_+(t) for all decays on their entire kinematically accessible t-domain. Our study favours f_B in the range 0.135-0.17 GeV and with E=0.44 GeV and 1/Lambda = 0.14 fm we obtain f_+^{B pi}(0) = 0.46. As a result of neglecting 1/m_c-corrections, we estimate that our calculated values of \rho^2 = 0.87 and f_+^{DK}(0)=0.62 are too low by approximately 15%. However, the bulk of these corrections should cancel in our calculated values of Br(D -> \pi l nu)/Br(D -> K l nu)=0.13 and f_+^{D pi}(0)/f_+^{DK}(0) = 1.16.Comment: 26 pages, 3 figures, REVTE

A consistent treatment for pion form factors in space-like and time-like regions

We write down some relevant matrix elements for the scattering and decay processes of the pion by considering a quark-meson vertex function. The pion charge and transition form factors $F_\pi$, $F_{\pi\gamma}$, and $F_{\pi\gamma^*}$ are extracted from these matrix elements using a relativistic quark model on the light-front. We found that, the form factors $F_\pi$ and $F_{\pi\gamma}$ in the space-like region agree well with experiment. Furthermore, the branching ratios of all observed decay modes of the neutral pion, that are related to the form factors $F_{\pi\gamma}$ and $F_{\pi\gamma^*}$ in the time-like region, are all consistent with the data as well. Additionally, $F_\pi$ in the time-like region, which deals with the nonvalence contribution, is also discussed.Comment: 24 pages, 6 figures, to appear in Phys. Rev.

Electromagnetic form factors in the light-front formalism and the Feynman triangle diagram: spin-0 and spin-1 two-fermion systems

The connection between the Feynman triangle diagram and the light-front formalism for spin-0 and spin-1 two-fermion systems is analyzed. It is shown that in the limit q+ = 0 the form factors for both spin-0 and spin-1 systems can be uniquely determined using only the good amplitudes, which are not affected by spurious effects related to the loss of rotational covariance present in the light-front formalism. At the same time, the unique feature of the suppression of the pair creation process is maintained. Therefore, a physically meaningful one-body approximation, in which all the constituents are on their mass-shells, can be consistently formulated in the limit q+ = 0. Moreover, it is shown that the effects of the contact term arising from the instantaneous propagation of the active constituent can be canceled out from the triangle diagram by means of an appropriate choice of the off-shell behavior of the bound state vertexes; this implies that in case of good amplitudes the Feynman triangle diagram and the one-body light-front result match exactly. The application of our covariant light-front approach to the evaluation of the rho-meson elastic form factors is presented.Comment: corrected typos in the reference

Arterial Obstruction on Computed Tomographic or Magnetic Resonance Angiography and Response to Intravenous Thrombolytics in Ischemic Stroke

BACKGROUND AND PURPOSE: Computed tomographic angiography and magnetic resonance angiography are used increasingly to assess arterial patency in patients with ischemic stroke. We determined which baseline angiography features predict response to intravenous thrombolytics in ischemic stroke using randomized controlled trial data. METHODS: We analyzed angiograms from the IST-3 (Third International Stroke Trial), an international, multicenter, prospective, randomized controlled trial of intravenous alteplase. Readers, masked to clinical, treatment, and outcome data, assessed prerandomization computed tomographic angiography and magnetic resonance angiography for presence, extent, location, and completeness of obstruction and collaterals. We compared angiography findings to 6-month functional outcome (Oxford Handicap Scale) and tested for interactions with alteplase, using ordinal regression in adjusted analyses. We also meta-analyzed all available angiography data from other randomized controlled trials of intravenous thrombolytics. RESULTS: In IST-3, 300 patients had prerandomization angiography (computed tomographic angiography=271 and magnetic resonance angiography=29). On multivariable analysis, more extensive angiographic obstruction and poor collaterals independently predicted poor outcome (P1 indicates benefit) in patients with (odds ratio, 2.07; 95% confidence interval, 1.18-3.64; P=0.011) versus without (odds ratio, 0.88; 95% confidence interval, 0.58-1.35; P=0.566) arterial obstruction (P for interaction 0.017). CONCLUSIONS: Intravenous thrombolytics provide benefit to stroke patients with computed tomographic angiography or magnetic resonance angiography evidence of arterial obstruction, but the sample was underpowered to demonstrate significant treatment benefit or harm among patients with apparently patent arteries. CLINICAL TRIAL REGISTRATION: URL: http://www.isrctn.com. Unique identifier: ISRCTN25765518

Non-Leptonic Decays of B Mesons and Strong Coupling Constants

Non-leptonic decays of B mesons into two mesons or meson resonances are studied on the basis of two versions of simple pole-dominance models involving scalar, vector, pseudoscalar and axial-vector poles. The results are compared with those obtained from the usual factorization model and used to obtain information on strong coupling constants between B meson and one light or one charmed meson, respectively. These coupling constants are compared to results from various QCD sum rule calculations.Comment: Latex file 35 pages, including 3 figure

Covariant Light-Front Approach for s-wave and p-wave Mesons: Its Application to Decay Constants and Form Factors

We study the decay constants and form factors of the ground-state s-wave and low-lying p-wave mesons within a covariant light-front approach. Numerical results of the form factors for transitions between a heavy pseudoscalar meson and an s-wave or p-wave meson and their momentum dependence are presented in detail. In particular, form factors for heavy-to-light and B to D** transitions, where D** denotes generically a p-wave charmed meson, are compared with other model calculations. The experimental measurements of the decays B^- to D** pi^- and B to D D**_s are employed to test the decay constants of D**_s and the B to D** transition form factors. The heavy quark limit behavior of the decay constants and form factors is examined and it is found that the requirement of heavy quark symmetry is satisfied. The universal Isgur-Wise (IW) functions, one for s-wave to s-wave and two for s-wave to p-wave transitions, are obtained. The values of IW functions at zero recoil and their slope parameters can be used to test the Bjorken and Uraltsev sum rules.Comment: 59 pages, 6 figures. Version to appear in Phys. Rev. D. Changes are: (i) D_s to phi transition form factors are discussed and compared with the recent FOCUS measurements and (ii) zero mode effects are clarifie

Ward Identities, B-> \rho Form Factors and |V_ub|

The exclusive FCNC beauty semileptonic decay B-> \rho is studied using Ward identities in a general vector meson dominance framework, predicting vector meson couplings involved. The long distance contributions are discussed which results to obtain form factors and |V_ub|. A detailed comparison is given with other approaches.Comment: 30 pages+four postscript figures, an Appendix adde

Indicators of Quality of Life in Women with Favorable and Unfavorable Course of Breast Cancer

В работе показаны результаты сравнительного анализа показателей качества жизни у женщин, больных злокачественным новообразованием молочной железы, c благоприятным и неблагоприятным течением болезни. В группу с благоприятным течением болезни включались женщины, больные раком молочной железы, в случае наступления полной ремиссии; стабилизации болезни. В группу женщин с неблагоприятным течением рака молочной железы включались пациенты в случае генерализации процесса, рецидива, прогрессии опухоли. У всей выборки женщин оценивались показатели качества жизни с помощью методики SF‑36. Всего в исследовании приняли участие 202 женщины с диагнозом рака молочной железы. Результаты сравнительного анализа показали отсутствие достоверных различий в показателях качества жизни между группой женщин, больных раком молочной железы, с благоприятным течением заболевания и группой женщин с неблагоприятным течением болезни.The paper shows the results of a comparative analysis of quality of life indicators in women with malignant neoplasm of the breast, with a favorable and unfavorable course of the disease. The group with a favorable course of the disease included women with breast cancer, in case of complete remission; stabilization of the disease. The group of women with an unfavorable course of breast cancer included patients in the case of generalization of the process, relapse, tumor progression. Quality of life indicators were assessed in the entire sample of women using the SF‑36 technique. A total of 202 women with a diagnosis of breast cancer participated in the study. The results of the comparative analysis showed the absence of significant differences in quality of life indicators between a group of women with breast cancer with a favorable course of the disease and a group of women with an unfavorable course of the disease.Исследование выполнено за счет гранта Российского научного фонда №21-18-00434, https://rscf.ru/project/21-18-00434

Peculiarities of tourism in a state of war

Стаття присвячена визначенню особливостей функціонування туристичної галузі в умовах війни на основі трансформаційних перетворень туризму в Україні під час війни 2022 року. Актуальність дослідження полягає в необхідності розвитку туризму як однієї з основних галузей економіки під час війни та після її завершення. Мета статті – розробити рекомендації, спрямовані на відновлення туристичної галузі, яка постраждала внаслідок воєнних дій в Україні. Для досягнення поставленої мети визначено важливість туристичного ринку України для сусідніх країн, проаналізовано його поточний стан та встановлено особливості функціонування в умовах війни. За результатами аналізу досвіду держав, які незважаючи на воєнний конфлікт відродили туристичну галузь, розроблено рекомендації, що спрямовані на розвиток туризму в Україні. В процесі дослідження використовувалися загальнонаукові методи, такі як аналіз, синтез, порівняння, індукція та дедукція. За результатами дослідження встановлено, що туризм в Україні є дуже обмеженим та залежним від стабільності в країні. В зв’язку з воєнними діями, які продовжуються в ряді областей, він має певні особливості, пов’язані з безпекою українських та іноземних громадян: формування туристичних маршрутів з урахуванням наявності бомбосховищ, планування туристичних мандрівок відповідно до дії комендантської години, дотримання заборон в різних регіонах України. Не дивлячись на складну ситуацію в державі, туризм продовжує функціонувати. Для його відновлення в післявоєнний період необхідно включити розвиток туризму в програми післявоєнного відновлення, вести перемовини зі світовими готельними мережами щодо їх виходу в Україну, підготувати масштабну маркетингову кампанію для зовнішніх ринків, розробити туристичні програми місцями військової слави Збройних сил України, відновити зруйновану та пошкоджену туристичну інфраструктуру, просувати нестандартні формати туризму, відкривати туристичні національні офіси в розвинених країнах світу. Практичне значення дослідження полягає в можливості застосовувати запропоновані напрями розвитку туризму туристичними компаніями, що відновлюватимуть свою діяльність в післявоєнний період.The article is devoted to determination of features of functioning of tourism industry in the conditions of war on the basis of transformations of tourism in Ukraine during the war 2022. The relevance of the study lies in the need to develop tourism as one of the main sectors of the economy during and after the war. The aim of the article is to develop recommendations aimed at restoring the tourism industry affected by the war in Ukraine. In order to achieve the objectives, the importance of the tourist market of Ukraine for the neighboring countries has been determined, its current state has been analyzed and the peculiarities of functioning in war conditions have been established. By results of the analysis of experience of the states which, despite the military conflict, have revived the tourist industry, the recommendations directed on development of tourism in Ukraine were worked out. General scientific methods such as analysis, synthesis, comparison, induction and deduction were used during the study. According to the results of the study, it was found that tourism in Ukraine is very limited and dependent on stability in the country. Due to the military activities that are ongoing in a number of areas, it has certain peculiarities related to the safety of Ukrainian and foreign citizens: the formation of tourist routes taking into account the presence of bomb shelters, planning tourist trips in accordance with the curfew, compliance with bans in different regions of Ukraine. Despite the difficult situation in the state, tourism continues to function. To restore it in the post-war period it is necessary to include tourism development in the post-war reconstruction programs, negotiate with global hotel chains on their entry to Ukraine, prepare large-scale marketing campaign for foreign markets, develop tourist programs by places of military glory of the Armed Forces of Ukraine, renew the destroyed and damaged tourist infrastructure, promote non-standard formats of tourism, open national tourist offices in developed countries. Practical value of the research consists in possibility of application of directions of development of tourism by the tourist companies resuming their activity in the post-war period

Severe course of diabetic ketoacidosis due to new coronavirus infection in older children (clinical cases)

The risk of severe type I diabetes mellitus in children with new coronavirus infection (COVID-19) is extremely high, which is associated with a high risk of intracranial hypertension, cerebral edema and multiple organ dysfunction syndrome. On the example of a clinical case, the features of the course of diabetic ketoacidosis and intensive care measures in children with COVID-19 were considered. The main data of the history and clinical and laboratory examination are reflected, special attention is paid to the applied aspects of therapy, it was noted that with a severe course of a new coronavirus infection and diabetic ketoacidosis, the risk of developing cerebral injury, acute kidney injury and thromboembolic complications is quite high, which may require artificial lung ventilation for the purpose of cerebral protection, renal replacement therapy and the use of anticoagulants. The new coronavirus infection is a risk factor for the severe course of diabetic ketoacidosis in children with type I diabetes, regardless of the age of the child, which is the basis for clinical alertness in order to timely identify and treat potential life-threatening complications