Physiological conditions influencing regenerative potential of stem cells

Stem cells are being used in the treatment of cardivovascular diseases. Here, we review the physiologic and pathologic conditions that impact the regenerative potential of stem cells in the treatment of cardiovascular diseases which include the influence of donor age and the presence of metabolic syndromes. We will also discuss strategies such as pretreatment of the recipient tissue or autologous or allogeneic stem cells by growth factors or drugs and by providing a synthetic scaffold and genetic modifications that impact the regenerative potential of stem cells. Finally, we will evaluate the current state of treatment of acute or chronic cardiovascular diseases with allogeneic stem cells

The 3^3He(e, e′'d)p Reaction in qω\omega-constant Kinematics

The cross section for the $^3$He(e, e$'$d)p reaction has been measured as a function of the missing momentum $p_m$ in q$\omega$ -constant kinematics at beam energies of 370 and 576 MeV for values of the three-momentum transfer $q$ of 412, 504 and 604 \mevc. The L(+TT), T and LT structure functions have been separated for $q$ = 412 and 504 \mevc. The data are compared to three-body Faddeev calculations, including meson-exchange currents (MEC), and to calculations based on a covariant diagrammatic expansion. The influence of final-state interactions and meson-exchange currents is discussed. The $p_m$-dependence of the data is reasonably well described by all calculations. However, the most advanced Faddeev calculations, which employ the AV18 nucleon-nucleon interaction and include MEC, overestimate the measured cross sections, especially the longitudinal part, and at the larger values of $q$. The diagrammatic approach gives a fair description of the cross section, but under(over)estimates the longitudinal (transverse) structure function.Comment: 17 pages, 7 figure

The Impact of Quantitative Easing and Capital Requirements on Bank Lending: an Econometric Analysis

One of the key problems of the current financial crisis is weak bank lending growth. Shortages of capital, low liquidity buffers and weak demand for bank lending have been identified as possible contributors to bank lending weakness. Given that credit booms and busts have important implications for both monetary and financial stability, policymakers acted swiftly to shore up bank lending growth by supporting demand for lending through unconventional monetary policy and by establishing a macroprudential policy framework to limit future imbalances within the financial system. While the rationales for the use of unconventional monetary policy and the establishment of a macroprudential policy framework are different, they both target, directly or indirectly, bank lending growth to achieve their objectives. The main contribution of this thesis is to estimate the impact of quantitative easing and macroprudential policy on bank lending growth by using a non-publicly available bank panel dataset of UK banks since the late 1980s. This dataset was constructed by the Bank of England by merging Bank of England balance sheet and income statement data (including sectoral lending) with FSA regulatory returns data on capital (including bank-specific capital requirements). Differently from other research, we are able to estimate our relationships using data spanning two business cycles and to study the impact of these policies on various types of sectoral lending. We find that these new policies are non-neutral from a bank lending perspective, even though to a different extent. In particular, we find that quantitative easing in the UK has a positive impact on bank lending even though not particularly large. There is evidence that these effects may have been more important for small rather than large banks. Moreover, we also find that the effect of QE may have been smaller during the financial crisis because of lower capital ratios in the banking system. We show that changes in capital requirements (a possible macroprudential tool) affect bank capital decisions as banks try to maintain a constant buffer above capital requirements. As banks change their capital structure, bank lending growth is affected. However, there is heterogeneity in the reaction to changes in capital requirements, as large banks do not change their lending behaviour following a regulatory shock. We also provide preliminary evidence that banks respond to a regulatory shock by reducing their exposure to riskier assets in order to decrease their risk weighted assets and boost their regulatory capital ratio by reducing lending to private non-financial corporations. These findings have important policy implications. First, quantitative easing in the UK is effective in increasing bank lending growth but our simulations suggest that the amount of gilts purchased by the Bank of England may not be enough to provide a significant stimulus to bank lending growth. Moreover, these purchases may have been less effective during the crisis period because of capital constraints in the banking sector. These results suggest that larger asset purchases are needed to significantly increase bank lending and that the effect of asset purchases can be magnified by further strengthening banks' capital positions. Second, capital requirements may be an effective macroprudential policy tool and could be used by new macroprudential regulators to reduce bank lending growth in boom times in order to contain systemic risk. However, these effects may be smaller than initially envisaged as large banks seem insensitive to policy changes. There may be various reasons why these banks do not react to changes in capital requirements. For example, large banks' better access to capital markets may allow these banks to operate with smaller capital buffers. Moreover, if large banks do not react to capital requirements because of their systemic importance (e.g. because the threat of default is not credible), changes in the structure of the financial system may be necessary to enhance the impact of macroprudential policy

The Impact of Quantitative Easing and Capital Requirements on Bank Lending: an Econometric Analysis

One of the key problems of the current financial crisis is weak bank lending growth. Shortages of capital, low liquidity buffers and weak demand for bank lending have been identified as possible contributors to bank lending weakness. Given that credit booms and busts have important implications for both monetary and financial stability, policymakers acted swiftly to shore up bank lending growth by supporting demand for lending through unconventional monetary policy and by establishing a macroprudential policy framework to limit future imbalances within the financial system. While the rationales for the use of unconventional monetary policy and the establishment of a macroprudential policy framework are different, they both target, directly or indirectly, bank lending growth to achieve their objectives. The main contribution of this thesis is to estimate the impact of quantitative easing and macroprudential policy on bank lending growth by using a non-publicly available bank panel dataset of UK banks since the late 1980s. This dataset was constructed by the Bank of England by merging Bank of England balance sheet and income statement data (including sectoral lending) with FSA regulatory returns data on capital (including bank-specific capital requirements). Differently from other research, we are able to estimate our relationships using data spanning two business cycles and to study the impact of these policies on various types of sectoral lending. We find that these new policies are non-neutral from a bank lending perspective, even though to a different extent. In particular, we find that quantitative easing in the UK has a positive impact on bank lending even though not particularly large. There is evidence that these effects may have been more important for small rather than large banks. Moreover, we also find that the effect of QE may have been smaller during the financial crisis because of lower capital ratios in the banking system. We show that changes in capital requirements (a possible macroprudential tool) affect bank capital decisions as banks try to maintain a constant buffer above capital requirements. As banks change their capital structure, bank lending growth is affected. However, there is heterogeneity in the reaction to changes in capital requirements, as large banks do not change their lending behaviour following a regulatory shock. We also provide preliminary evidence that banks respond to a regulatory shock by reducing their exposure to riskier assets in order to decrease their risk weighted assets and boost their regulatory capital ratio by reducing lending to private non-financial corporations. These findings have important policy implications. First, quantitative easing in the UK is effective in increasing bank lending growth but our simulations suggest that the amount of gilts purchased by the Bank of England may not be enough to provide a significant stimulus to bank lending growth. Moreover, these purchases may have been less effective during the crisis period because of capital constraints in the banking sector. These results suggest that larger asset purchases are needed to significantly increase bank lending and that the effect of asset purchases can be magnified by further strengthening banks' capital positions. Second, capital requirements may be an effective macroprudential policy tool and could be used by new macroprudential regulators to reduce bank lending growth in boom times in order to contain systemic risk. However, these effects may be smaller than initially envisaged as large banks seem insensitive to policy changes. There may be various reasons why these banks do not react to changes in capital requirements. For example, large banks' better access to capital markets may allow these banks to operate with smaller capital buffers. Moreover, if large banks do not react to capital requirements because of their systemic importance (e.g. because the threat of default is not credible), changes in the structure of the financial system may be necessary to enhance the impact of macroprudential policy

Remoción de plaguicidas MCPA e Imazapic de solución acuosa con materiales carbonosos

El objetivo general de este trabajo se orienta a la búsqueda de alternativas simples y accesibles para la remediación de aguas contaminadas, teniendo en cuenta que la presencia de contaminantes emergentes en nuestros recursos hídricos, tales como fármacos y pesticidas, es motivo de preocupación para la salud y seguridad ambiental. Se realizaron estudios de adsorción de dos pesticidas: MCPA (ácido 4-cloro-2-metil fenoxiacético) e Imazapic (ácido 2-[4,5-dihidro-4-metil-4-(1-metiletil)-5-oxo-1H-imidazol-2-il]-5-metil-3-piridin carboxílico), en dos diferentes tipos de material carbonoso. Fueron utilizados dos tipos de carbón activado, cada uno con diferentes características físicas y químicas, CAT-Ox 4 sulfuro de hidrógeno, adquirido en pellets de 4mm y CARBOPAL MB 4S (Donau). Se realizaron diferentes experimentos en batch de los herbicidas MCPA e Imazapic sobre dos tipos de carbón activado, CAT y CARBOPAL, bajo diferentes condiciones. Ambos materiales parecen ser muy efectivos removiendo estos contaminantes, pero CAT parece tener una mayor capacidad. Ambos pesticidas siguen cinéticas de adsorción de pseudo segundo orden en ambos materiales, lo que indicaría una mayor contribución de quimisorción con formación de monocapa. La capacidad de adsorción (qe) de herbicidas es significativamente influenciada por el valor de pH. En el presente estudio, ambos pesticidas tienen una disminución en la capacidad de adsorción cuando se utilizan condiciones básicas debido a que la superficie de los carbones están cargadas negativamente y en estas condiciones los herbicidas se encuentran en forma aniónica. Además, diferentes modelos fueron analizados para predecir propiedades de cada proceso de adsorción. MCPA se adapta al modelo teórico de Langmuir en ambos materiales. Debido a esto, se predice un proceso de quimisorción con la formación de una monocapa. Por otro lado, Imazapic se adapta al modelo GAB sobre CAT y CARBOPAL, con la formación de multicapas. La capacidad de adsorción es muy alta, por lo que ambos materiales pueden ser usados como método efectivo y de bajo costo para remover MCPA e Imazapic de recursos acuosos.Trabajo presentado por el Centro de Estudio de Compuestos Orgánicos (CEDECOR

The 4^4He(e,e′p)(e,e'p) Cross Section at Large Missing Energy

The $(e,e'p)$ reaction on $^{4}{He}$ nuclei was studied in kinematics designed to emphasize effects of nuclear short-range correlations. The measured cross sections display a peak in the kinematical regions where two-nucleon processes are expected to dominate. Theoretical models incorporating short-range correlation effects agree reasonably with the data.Comment: 4 pages LaTeX, using espcrc1.sty and wrapfig.sty (included), two figures. Talk presented by J. Templon at the 15th Int. Conf. on Few-Body Problems in Physics, Groningen, The Netherlands, 22-26 July, 199

Meson Exchange Currents in (e,e'p) recoil polarization observables

A study of the effects of meson-exchange currents and isobar configurations in $A(\vec{e},e'\vec{p})B$ reactions is presented. We use a distorted wave impulse approximation (DWIA) model where final-state interactions are treated through a phenomenological optical potential. The model includes relativistic corrections in the kinematics and in the electromagnetic one- and two-body currents. The full set of polarized response functions is analyzed, as well as the transferred polarization asymmetry. Results are presented for proton knock-out from closed-shell nuclei, for moderate to high momentum transfer.Comment: 44 pages, 18 figures. Added physical arguments explaining the dominance of OB over MEC, and a summary of differences with previous MEC calculations. To be published in PR

Quaiselastic scattering from relativistic bound nucleons: Transverse-Longitudinal response

Predictions for electron induced proton knockout from the $p_{1/2}$ and $p_{3/2}$ shells in $^{16}$O are presented using various approximations for the relativistic nucleonic current. Results for the differential cross section, transverse-longitudinal response ($R_{TL}$) and left-right asymmetry $A_{TL}$ are compared at $|Q^2|=0.8$ (GeV/c)$^2$ corresponding to TJNAF experiment 89-003. We show that there are important dynamical and kinematical relativistic effects which can be tested by experiment.Comment: 10 pages, including 2 figures. Removed preliminary experimental data from the figure

Analysis of Meson Exchange and Isobar Currents in (e,e'p) Reactions from O-16

An analysis of the effects of meson exchange and isobar currents in exclusive (e,e'p) processes from O-16 under quasi-free kinematics is presented. A model that has probed its feasibility for inclusive quasi-elastic (e,e') processes is considered. Sensitivity to final state interactions between the outgoing proton and the residual nucleus is discussed by comparing the results obtained with phenomenological optical potentials and a continuum nuclear shell-model calculation. The contribution of the meson-exchange and isobar currents to the response functions is evaluated and compared to previous calculations, which differ notably from our results. These two-body contributions cannot solve the puzzle of the simultaneous description of the different responses experimentally separated. Copyright 1999 by The American Physical SocietyComment: 5 pages, plus 3 PS figures. To be published in Phys. Rev. C Updated figure