The phonological heritage of the scientists of the XX century: a linguistic and historiographical review

A great attention is paid to the linguistic-historiographic analysis of the works of the Moscow, Prague and Saint Petersburg phonological schools’ representatives, which were dedicated to the problem of the language phonemic syste

Resonant ion-pair formation in electron recombination with HF^+

The cross section for resonant ion-pair formation in the collision of low-energy electrons with HF^+ is calculated by the solution of the time-dependent Schrodinger equation with multiple coupled states using a wave packet method. A diabatization procedure is proposed to obtain the electronic couplings between quasidiabatic potentials of ^1Sigma^+ symmetry for HF. By including these couplings between the neutral states, the cross section for ion-pair formation increases with about two orders of magnitude compared with the cross section for direct dissociation. Qualitative agreement with the measured cross section is obtained. The oscillations in the calculated cross section are analyzed. The cross section for ion-pair formation in electron recombination with DF^+ is calculated to determine the effect of isotopic substitution.Comment: 12 pages, 12 figure

Reactions of C+ + Cl-, Br-, and I--A comparison of theory and experiment.

Rate constants for the reactions of C+ + Cl-, Br-, and I- were measured at 300 K using the variable electron and neutral density electron attachment mass spectrometry technique in a flowing afterglow Langmuir probe apparatus. Upper bounds of <10-8 cm3 s-1 were found for the reaction of C+ with Br- and I-, and a rate constant of 4.2 ± 1.1 × 10-9 cm3 s-1 was measured for the reaction with Cl-. The C+ + Cl- mutual neutralization reaction was studied theoretically from first principles, and a rate constant of 3.9 × 10-10 cm3 s-1, an order of magnitude smaller than experiment, was obtained with spin-orbit interactions included using a semiempirical model. The discrepancy between the measured and calculated rate constants could be explained by the fact that in the experiment, the total loss of C+ ions was measured, while the theoretical treatment did not include the associative ionization channel. The charge transfer was found to take place at small internuclear distances, and the spin-orbit interaction was found to have a minor effect on the rate constant

ОСОБЛИВОСТІ ПЕРОКСИДНОГО ОКИСНЕННЯ ЛІПІДІВ У СИРОВАТЦІ КРОВІ Й ГОМОГЕНАТАХ ТКАНИН ЩУРІВ ЗА УМОВ КОМБІНОВАНОГО ВПЛИВУ СТРЕСОВИХ ЧИННИКІВ

The aim of the work. To analyze the level of active products of thiobarbituric acid in blood and homogenate of rat tissues under the condition of stress factors and their combination.. Materials and Methods. The experiments were conducted on 54 white non-linear male rats weighing 200–220 g. Animals were divided into 5 groups: 1 – control group (n = 6), 2 – chronic exposure to tobacco smoke (n = 12), 3 – chronic black leaf tea intoxication (n = 12), 4 – chronic immobilization stress (n = 12), 5 – combined influence of stress factors (n = 12). The principle of determining the content of TBA-active products (TBA-AP) is based on the fact that at high temperature in acidic medium malonic dialdehyde reacts with thiobarbituric acid, forming a trimethin complex. Results and Discussion. Chronic exposure to tobacco smoke is accompanied by activation of lipid peroxidation, in particular, the maximum changes in the content of TBA-AP are observed in the lung homogenate (3.5 times), in chronic intoxication with black tea – in the myocardial homogenate (3.5 times), with immobility – in the stomach homogenate (2.9 times) relative to the control group. With the combined effect of stressors, more pronounced changes are observed relative to the isolated effect of each factor: in the heart (6.9 times), in the lungs (6.3 times), in the stomach (6.6 times) and in periodontium (in 5.1 times) relative to the control group. Conclusions. The combined effect of stressors causes the activation of free radical oxidation processes, which is characterized by changes in TBA reactants, in particular, more pronounced changes are observed relative to the isolated effect of each factor relative to the control group.Мета роботи. Проаналізувати рівень активних продуктів тіобарбітурової кислоти в крові й гомогенаті тканин щурів за умови дії стресових чинників та їх комбінації. Матеріали і методи. Досліди проведено на 54 білих статевозрілих нелінійних щурах-самцях масою 200–220 г. Тварин поділили на 5 груп: перша – контрольна група (n=6), друга – хронічний вплив тютюнового диму (n=12), третя – хронічна інтоксикація чорним листковим чаєм (n=12), четверта – хронічний іммобілізаційний стрес (n=12), п’ята – комбінований вплив стресових чинників (n=12). Принцип визначення вмісту ТБК-активних продуктів (ТБК-АП) ґрунтується на тому, що при високій температурі в кислому середовищі малоновий діальдегід реагує з тіобарбітуровою кислотою, утворюючи триметиновий комплекс. Результати й обговорення. Хронічний вплив тютюнового диму супроводжується активацією пероксидації ліпідів, зокрема максимальні зміни вмісту ТБК-АП спостерігали у гомогенаті легень (у 3,5 раза), при хронічній інтоксикації чорним чаєм – у гомогенаті міокарда (у 3,5 раза), при іммобілізаційному стресі – в гомогенаті шлунка (у 2,9 раза) відносно контрольної групи. За умови комбінованого впливу стресових чинників більш вираженими були зміни відносно ізольованого впливу кожного чинника: у серці (в 6,9 раза), у легенях (в 6,3 раза), у шлунку (в 6,6 раза) та у пародонті (в 5,1 раза) відносно контрольної групи. Висновки. Комбінований вплив стресових факторів зумовлює активацію процесів вільнорадикального окиснення, що характеризується змінами ТБК-реактантів, зокрема спостерігають більш виражені зміни відносно ізольованого впливу кожного чинника щодо контрольної групи

Probiotics for Preterm Infants: a strain specific systematic review and network meta-analysis

Several randomised controlled trials (RCTs) on the use of probiotics to reduce morbidity and mortality in preterm infants have provided inconsistent results. Whilst meta-analyses that group all of the used strains together, suggest efficacy, it is not possible to determine the most effective strain which is more relevant to the clinician. We therefore used a network meta-analysis (NMA) approach in order to identify strains with greatest efficacy

Observations of H3+ in the Diffuse Interstellar Medium

Surprisingly large column densities of H3+ have been detected using infrared absorption spectroscopy in seven diffuse cloud sightlines (Cygnus OB2 12, Cygnus OB2 5, HD 183143, HD 20041, WR 104, WR 118, and WR 121), demonstrating that H3+ is ubiquitous in the diffuse interstellar medium. Using the standard model of diffuse cloud chemistry, our H3+ column densities imply unreasonably long path lengths (~1 kpc) and low densities (~3 cm^-3). Complimentary millimeter-wave, infrared, and visible observations of related species suggest that the chemical model is incorrect and that the number density of H3+ must be increased by one to two orders of magnitude. Possible solutions include a reduced electron fraction, an enhanced rate of H2 ionization, and/or a smaller value of the H3+ dissociative recombination rate constant than implied by laboratory experiments.Comment: To be published in Astrophysical Journal, March 200

Scattering matrix approach to the dissociative recombination of HCO+ and N2H+

We present a theoretical study of the indirect dissociative recombination of linear polyatomic ions at low collisional energies. The approach is based on the computation of the scattering matrix just above the ionization threshold and enables the explicit determination of all diabatic electronic couplings responsible for dissociative recombination. In addition, we use the multi-channel quantum-defect theory to demonstrate the precision of the scattering matrix by reproducing accurately ab initio Rydberg state energies of the neutral molecule. We consider the molecular ions N2H+ and HCO+ as benchmark systems of astrophysical interest and improve former theoretical studies, which had repeatedly produced smaller cross sections than experimentally measured. Specifically, we demonstrate the crucial role of the previously overlooked stretching modes for linear polyatomic ions with large permanent dipole moment. The theoretical cross sections for both ions agree well with experimental data over a wide energy range. Finally, we consider the potential role of the HOC+ isomer in the experimental cross sections of HCO+ at energies below 10 meV

Enhanced cosmic-ray flux toward zeta Persei inferred from laboratory study of H3+ - e- recombination rate

The H3+ molecular ion plays a fundamental role in interstellar chemistry, as it initiates a network of chemical reactions that produce many interstellar molecules. In dense clouds, the H3+ abundance is understood using a simple chemical model, from which observations of H3+ yield valuable estimates of cloud path length, density, and temperature. On the other hand, observations of diffuse clouds have suggested that H3+ is considerably more abundant than expected from the chemical models. However, diffuse cloud models have been hampered by the uncertain values of three key parameters: the rate of H3+ destruction by electrons, the electron fraction, and the cosmic-ray ionisation rate. Here we report a direct experimental measurement of the H3+ destruction rate under nearly interstellar conditions. We also report the observation of H3+ in a diffuse cloud (towards zeta Persei) where the electron fraction is already known. Taken together, these results allow us to derive the value of the third uncertain model parameter: we find that the cosmic-ray ionisation rate in this sightline is forty times faster than previously assumed. If such a high cosmic-ray flux is indeed ubiquitous in diffuse clouds, the discrepancy between chemical models and the previous observations of H3+ can be resolved.Comment: 6 pages, Nature, in pres