The lifetimes of the 2(1)(+) and 4(1)(+) states of Po-208 were measured in the a-transfer reaction Pb-204(C-12, Be-8) Po-208 by gamma-ray spectroscopy utilizing the recoil distance Doppler shift method. The newly extracted transition strengths alongside ones of the decay of the 2(2)(+) state were compared to the results of large-scale shell-model calculations using an effective interaction derived from the realistic CD-Bonn nucleon-nucleon potential. The comparison indicates the importance of the quadrupole isovector excitations in the valence shell for a fine tuning of the two-body matrix elements of the shell-model interaction.

Plane (Platanus orientalis) is a popular park tree in Europe but is almost extinct in natural ecosystems, because of climate changes. In our study, two ecotypes of plane tree (Bulgarian and Italian) were submitted to moderately elevated temperature that occurs in summer. Our aim was to compare stress reactions, tolerance, and adaptability of these plants. Leaf age had a significant impact on the stress effects. For correct interpretation of the results, we investigated leaves at different positions from the apical bud, i.e., leaves of different age. We assessed their photosynthetic efficiency at room temperature and after treatment at moderately high temperature by simultaneous measurement of prompt and delayed chlorophyll fluorescence, as well as light reflection at 820 nm. For more precise interpretation of the obtained results we did principal component analysis. The two studied plane ecotypes showed different tolerance to the elevated temperature. Plants of Italian ecotype showed better adaptivity and developed advantageous photosynthetic characteristics, while Bulgarian ecotype was more affected. Plants of both ecotypes recovered from the heat stress.

The form factor and the density distribution of the He nucleus are calculated approximately using the Morse single-particle potential. The parameters are determined by fitting the theoretical charge form factor to the corresponding experimental data of the elastic electron scattering by 4He, which are extended to large values of the momentum transfer. The corrections due to the center of mass motion (in the fixed center of mass approach) and of the finite proton size have been taken into account. The calculations can be performed partly analytically and the results show a considerable im- provement with respect to those obtained with the oscillator shell model.

We have adopted an importance sampling iterative matrix diagonalization algorithm to compute a large scale shell model calculation of the yrast spectrum of 138Xe up to high spin thereby extending a previous calculation confined to low-lying angular momenta. An effective nucleon–nucleon interaction derived from the CD-Bonn nucleon-nucleon potential is used to compute energies, E2 transition probabilities, and occupation numbers. A satisfactory agreement with the experimental data is reached.

The intrinsic reaction mechanism of proton-induced composite particle pre-equilibrium emission is well known to be a statistical multistep process. However, until recently it was still not clear how important the competition between pickup and knockout is to produce a composite ejectile in the multistep sequence. An evaluation of recent ([Formula: see text]) results at incident energies from 65 to 160[Formula: see text]MeV and on representative target nuclei is presented. The virtue of analyzing power angular distributions to unravel the details of the reaction mechanism is discussed and future possible avenues of investigation are explored.

The pre-equilibrium proton induced emission of light complex nuclei with energies in the continuum has been studied comprehensively for many years. Double-differential cross sections and especially analyzing power distributions are typical of an intranuclear nucleon-nucleon multistep statistical reaction mechanism. The final stage of the reaction may be a result of a direct pickup or knockout of the ejectile. The discussion on this subject continues to be a hot topic for theoretical and experimental investigations. In this contribution results from the latest studies of the inclusive (~ p, α) reaction at 72 MeV incident energy on Zr to the continuum will be reported. The aim of the present investigation is to further develop the systematics of the dependence of the reaction mechanism on the target nucleus.

Experimental results are presented for the inclusive reaction $^{59}\mathrm{Co}(\stackrel{P\vec}{p},\ensuremath{\alpha})$ at an incident energy of 100 MeV. A theoretical analysis based on a statistical multistep mechanism indicates that the terminal step leading to emission of an $\ensuremath{\alpha}$ particle can be a pickup or knockout process and that both processes are very prominent. This is a conclusion which is in agreement with an earlier study of the $^{93}\mathrm{Nb}(\stackrel{P\vec}{p},\ensuremath{\alpha})$ reaction. This inspires an investigation of the reason why a mixture of knockout and pickup is present at an incident energy of 100 MeV, whereas at both higher and lower incident energies knockout appears to dominate for the target nucleus $^{93}\mathrm{Nb}$. It is found that the different dynamics of the two competing reaction mechanisms provide an explanation for the observed phenomenon. It is speculated that for $^{59}\mathrm{Co}$ at both lower and higher incident energies the trend is likely to be similar to that of $^{93}\mathrm{Nb}$.

Hypoxic events are known to cause substantial damage to the hippocampus, cerebellum and striatum. The impact of hypoxic shock on other brain parts is not sufficiently studied. Recent studies show that tripeptidyl peptidase I (TPPI) activity in fish is altered after a hypoxic stress pointing out at a possible enzyme involvement in response to hypoxia. Similar studies are not performed in mammals. In this work, the effect of sodium nitrite-induced acute hypoxic shock on the rat brain was studied at different post-treatment periods. Morphological changes in cerebral cortex, cerebellum, medulla oblongata, thalamus, mesencephalon and pons were assessed using silver-copper impregnation for neurodegeneration. TPPI activity was biochemically assayed and localized by enzyme histochemistry. Although less vulnerable to oxidative stress, the studied brain areas showed different histopathological changes, such as neuronal loss and tissue vacuolization, dilatation of the smallest capillaries and impairment of neuronal processes. TPPI activity was strictly regulated following the hypoxic stress. It was found to increase 12-24h post-treatment, then decreased followed by a slow process of recovery. The enzyme histochemistry revealed a temporary enzyme deficiency in all types of neurons. These findings indicate a possible involvement of the enzyme in rat brain response to hypoxic stress.

The pre-equilibrium proton induced emission of light complex nuclei with energies in the continuum has been studied comprehensively for many years. Double–differential cross sections and especially analyzing power distributions are typical of an intranuclear nucleon-nucleon multistep statistical reaction mechanism. The final stage of the reaction may be a result of a direct pickup or knockout of the ejectile. The discussion on this subject continues to be a hot topic for both theoretical and experimental investigations. In this paper the results from the latest studies of the inclusive (, α) reactions on 59 Co to the continuum will be reported. The formalism based on the statistical multistep direct emission formulation of Feshbach, Kerman and Koonin is found to give a reasonably good reproduction of cross section and analyzing power distributions at various emission energies. Special attention will be paid to the details of the calculations.

Recent results for the inclusive reaction 93 Nb(p ,α ) between incident energies of 65 and 160 MeV are shown to be consistent with a competition between knockout and pickup. The pre-equilibrium statistical multistep process terminates in either mechanism. The incident-energy dependence of the reaction reflects the dynamics of the participating reaction components. It is consequently not surprising to observe knockout to dominate at the lower and highest incident energies, with pickup very prominent in between.

Experimental results are presented for the inclusive reaction Co-59((p) over right arrow,alpha) at an incident energy of 100 MeV. A theoretical analysis based on a statistical multistep mechanism indicates that the terminal step leading to emission of an alpha particle can be a pickup or knockout process and that both processes are very prominent. This is a conclusion which is in agreement with an earlier study of the Nb-93((p) over right arrow,alpha) reaction. This inspires an investigation of the reason why a mixture of knockout and pickup is present at an incident energy of 100 MeV, whereas at both higher and lower incident energies knockout appears to dominate for the target nucleus Nb-93. It is found that the different dynamics of the two competing reaction mechanisms provide an explanation for the observed phenomenon. It is speculated that for Co-59 at both lower and higher incident energies the trend is likely to be similar to that of Nb-93.

The pre-equilibrium proton induced emission of light complex nuclei with energies in the continuum has been studied comprehensively for many years. Double-differential cross sections and especially analyzing power distributions are typical of an intranuclear nucleon-nucleon multistep statistical reaction mechanism. The final stage of the reaction may be a result of a direct pickup or knockout of the ejectile. The discussion on this subject continues to be a hot topic for both theoretical and experimental investigations. In this paper the results from the latest studies of the inclusive ((p) over right arrow, a) reactions on Co-59 to the continuum will be reported. The formalism based on the statistical multistep direct emission formulation of Feshbach, Kerman and Koonin is found to give a reasonably good reproduction of cross section and analyzing power distributions at various emission energies. Special attention will be paid to the details of the calculations.

Platanus orientalis is considered endangered species that is almost extinct in the natural ecosystems of Western Europe and, because of its hydrophilic habitat, may also be strongly affected by increasing water limitations in Eastern Europe. The effects of drought stress were studied and compared in young plane trees of two ecotypes from Bulgarian and Italian regions. The dynamics of drying and following re-watering was monitored in vivo by changes in activity of photosynthetic light phase reactions in leaves of 4-5 month old seedlings subject to controlled moderate water limiting regime for 12 days and subsequent recovery by controlled gradual irrigation for 10 days. The physiological state of photosynthetic machinery was estimated by analysis of signals of prompt and delayed chlorophyll a fluorescence measured in attached plane leaves by the Multifunctional Plant Efficiency Analyzer (Hansatech Instruments Ltd., UK). Prompt chlorophyll a fluorescence directly correlates to the redox state of the electron carriers in photosystem II at light conditions, while delayed fluorescence indicates rate constants of direct and back electron transport reactions within the same structure. The fluorometer allows simultaneous measurement of both prompt and delayed chlorophyll fluorescence signals that provide complementary information concerning the reactions in the photosynthetic light stage. We show that both donor and acceptor sides of photosystem II as well as intersystem electron transport are inhibited during drought stress. Moreover, the intersystem electron carriers appear to be the most sensitive part, indicated by strongly reduced size of their pool in the thylakoid membrane. The stress reaction of Bulgarian ecotype is expressed clearly. However, fluorescent parameters undergo partial recovery during re-watering. On the other hand, parameters in Italian ecotype exhibit weak changes during drought stress but the effect proceeds throughout the whole monitoring period.

Analyzing the changes that occur in the photosynthetic machinery of plants is one of the most informative approaches for evaluation of the plant physiological state, their stress reactions, productivity and the adaptive mechanisms that develop in order to protect the plant in a changing environment. An informative method for detection and analyzing of the photosynthetic process is measuring the chlorophyll a fluorescence emitted from leaves. Illumination of a plant sample induces a rise in the chlorophyll a fluorescence that draws characteristic induction curves which carry broad spectrum of data about every step of the photosynthetic process. Chlorophyll a fluorescence gives two types of signals – prompt (PF) and delayed chlorophyll fluorescence (DF). The Multifunctional Plant Efficiency Analyzer (MPEA), developed by Hansatech is constructed to measure both simultaneously in only one measurement, but as the initial steps of their kinetics overlap they cannot be recorded together while the sample is illuminated. Thus the apparatus is set to switch between light (recording of PF) and dark (recording of DF decay kinetics) conditions at specific periods of time. When the light is switched off during the dark period oxidation processes of the Photosystem II (PSII) reaction center occur which lowers the level of chlorophyll fluorescence. Thus when the light is put on again, the PF signal continues from a lower level. This phenomenon is called Dark Drops (DD) of chlorophyll fluorescence and it can be a valuable source of information. The aim of our study is to develop a new approach to collect and analyze the information from the Dark Drops and use it to investigate the changes in the photosynthetic process in leave samples of the plant Phaseolus vulgaris in normal conditions and in

The reaction mechanism of pre-equilibrium proton-induced alpha-particle emission from Nb-93 at an incident energy of 100 MeV was investigated with polarized projectiles. A formalism based on the statistical multistep direct emission model of Feshbach, Kerman, and Koonin was found to give a reasonably good reproduction of cross section and analyzing power angular distributions at various emission energies. Existing experimental distributions for the same reaction at an incident energy of 65 MeV were also analyzed with the same model. The incident-energy variation from 65 MeV up to 160 MeV was found to be consistent with the predictions of the basic model. However, whereas knockout of an alpha cluster is the dominant reaction mechanism in the final stage at the lowest and highest incident energies, at 100 MeV a pickup process competes with comparable intensity in yield.

The inclusive Nb-93((p) over right arrow,alpha) reaction to the continuum was investigated at an incident energy of 160 MeV. Emission-energy angular distributions for cross sections as well as analyzing powers were explored. A range of scattering angles from 15 degrees to 60 degrees (lab.) was covered and alpha-particle emission energies from approximate to 30 MeV to the kinematic limit were measured. As in our earlier work, the experimental distributions were compared with a multistep direct theory combined with a knockout reaction mechanism as the terminating step in the alpha-particle emission. Reasonable agreement between the theoretical predictions and the experimental double-differential cross section and analyzing-power angular distributions were obtained.

The pre-equilibrium proton induced emission of light complex nuclei with energies in the continuum has been studied comprehensively for many years. Double–differential cross sections and especially analyzing power distributions are typical of an intranuclear nucleon-nucleon multistep statistical reaction mechanism. The final stage of the reaction may be a result of a direct pickup or knockout of the ejectile. The discussion on this subject continues to be a hot topic for theoretical and experimental investigations. In this contribution we will report results about the cross section and analyzing power distributions for the Nb(~ p,α) reactions at 100 MeV incident energy to the continuum. A formalism based on the statistical multistep direct emission formulation of Feshbach, Kerman and Koonin is found to give a reasonably good reproduction of cross section and analyzing power distributions at various emission energies. The contribution of the pickup and knockout reaction mechanism for various proton energies is discussed in detail.

Lithium is extensively used in psychiatric practice for the prevention and treatment of manic-depressive disorders. However, neurotoxicity attributed to lithium salts within therapeutic doses was also reported in patients, manifested by transient or persistent neurological deficits. In this study, morphological changes were examined in rats treated acutely and chronically with lithium. Pathological changes were observed in different brain regions including cerebral cortex, cerebellum, medulla oblongata, mesencephalon, thalamus, and pons, using a silver–copper impregnation technique for neurodegeneration. Vacuolization of brain tissue with subsequent formation of spongiosis was the prominent morphological feature following lithium administration. The zones of spongiosis were irregularly distributed throughout the brain. More intensive compact areas with spongiform changes were found in the cerebral cortex and medulla oblongata. Less pronounced vacuolization was noted in the pons and thalamic region. The cerebellum and mesencephalon appeared least affected. Vacuolization in the cerebellar cortex was found at loci with Purkinje cells, but the classical picture of spongiosis was not apparent. Data indicate that both acute and chronic lithium intoxication accelerated neurodegenerative changes normally seen with normal brain aging.