Signatures of Chiral Dynamics in Low Energy Compton Scattering off the Nucleon

We present a projector formalism which allows to define dynamical polarizabilities of the nucleon from a multipole expansion of the nucleon Compton amplitudes. We give predictions for the energy dependence of these dynamical polarizabilities both from dispersion theory and from leading-one-loop chiral effective field theory. Based on the good agreement between the two theoretical frameworks, we conclude that the energy dependence of the dynamical polarizabilities is dominated by chiral dynamics, except in those multipole channels where the first nucleon resonance Delta(1232) can be excited. Both the dispersion theory framework and a chiral effective field theory with explicit Delta(1232) degrees of freedom lead to a very good description of the available low energy proton Compton data. We discuss the sensitivity of the proton Compton cross section to dynamical polarizabilities of different multipole content and present a fit of the static electric and magnetic dipole polarizabilities from low-energy Compton data up to omega=170 MeV, finding alpha_E=(11.04+-1.36)*10^(-4) fm^3, beta_M =(2.76-+1.36)*10^(-4) fm^3.Comment: 43 pages, 13 figure

Dispersion Theory and the Low Energy Constants for Neutral Pion Photoproduction

The relativistic amplitudes of pion photoproduction are evaluated by dispersion relations at t=const. The imaginary parts of the amplitudes are taken from the MAID model covering the absorption spectrum up to center-of-mass energies W = 2.2 GeV. For sub-threshold kinematics the amplitudes are expanded in powers of the two independent variables \nu and t related to energy and momentum transfer. Subtracting the loop corrections from this power series allows one to determine the counter terms of covariant baryon chiral perturbation theory. The proposed continuation of the amplitudes into the unphysical region provides a unique framework to derive the low-energy constants to any given order as well as an estimate of the higher order terms by global properties of the absorption spectrum.Comment: 13 pages, 6 figures, 5 table

Spin Polarizabilities of the Nucleon from Polarized Low Energy Compton Scattering

As guideline for forthcoming experiments, we present predictions from Chiral Effective Field Theory for polarized cross sections in low energy Compton scattering for photon energies below 170 MeV, both on the proton and on the neutron. Special interest is put on the role of the nucleon spin polarizabilities which can be examined especially well in polarized Compton scattering. We present a model-independent way to extract their energy dependence and static values from experiment, interpreting our findings also in terms of the low energy effective degrees of freedom inside the nucleon: The polarizabilities are dominated by chiral dynamics from the pion cloud, except for resonant multipoles, where contributions of the Delta(1232) resonance turn out to be crucial. We therefore include it as an explicit degree of freedom. We also identify some experimental settings which are particularly sensitive to the spin polarizabilities.Comment: 30 pages, 19 figure

Aging in Barnstable: Striving for High Livability in a Cape Cod Community

This report describes collaborative efforts undertaken by the Town of Barnstable Senior Services Division and the Center for Social and Demographic Research on Aging, within the Gerontology Institute at the McCormack Graduate School, University of Massachusetts Boston. Beginning in Fall 2014, these organizations partnered to conduct a study to investigate the needs, interests, preferences, and opinions of the Town’s older resident population, with respect to living and aging in Barnstable. The focus of this report was on two cohorts of Barnstable residents — those aged 50 to 59 (referred to as “Boomers”), and the cohort of individuals who are currently aged 60 and over (“Seniors”)

Cellular Uptake and Nuclear Delivery of Recombinant Adenovirus Penton Base

AbstractAn Ad2 capsid component, the penton base, expressed as recombinant protein, was found to be capable of affecting the entire entry pathway of adenovirion in HeLa cells, i.e., cell attachment, endocytosis, vesicular escape, intracytoplasmic movement, and translocation through the nuclear pore complex. Data with pentamerization-defective mutants suggested that none of these successive steps depended upon penton base pentamer status, indicating that the peptide domains responsible for these functions were carried by the monomer. Observations performed with wild-type (WT) and an integrin-binding-site double-mutant (K288E340) suggested that the penton base could enter the cell via an alternative, RGD- and LDV-independent, pathway. Of three mutants that were found to be defective in nuclear addressing in insect cells, only one, W165H, was also altered in nuclear transport in HeLa cells. The other two, W119H and RRR547EQQ, showed a WT pattern of nuclear localization in HeLa cells, suggesting that the region including tryptophan-119 and the basic signal at position 547 did not act as a nuclear localization signal in the human cell context. The integrity of cellular structures and the cytoskeleton seemed to be required for the vectorial movement and nuclear import of WT penton base, as suggested by experiments using permeabilized HeLa cells, isolated nuclear membranes, and cytoskeleton-targeted drugs

Needs Assessment for Littleton Elder and Human Services and the Council on Aging

This report describes efforts undertaken by the Town of Littleton Council on Aging, in partnership with the Center for Social and Demographic Research on Aging within the Gerontology Institute at the University of Massachusetts Boston, to investigate the needs, interests, preferences, and opinions of Littleton’s older population. The focus of this report was on two cohorts of Littleton residents—those aged 50 to 59 (referred to as “Boomers”), and the cohort of individuals who are currently aged 60 and over (“Seniors”). The content of this report is intended to inform the Town of Littleton, the Littleton Council on Aging and Senior Center, and organizations that provide services to older residents, as well as those who advocate for older people, and community members at large

The inhibition of assembly of HIV-1 virus-like particles by 3-O-(3',3'-dimethylsuccinyl) betulinic acid (DSB) is counteracted by Vif and requires its Zinc-binding domain

International audienceBackground: DSB, the 3-O-(3',3'dimethylsuccinyl) derivative of betulinic acid, blocks the last step of protease-mediated processing of HIV-1 Gag precursor (Pr55Gag), which leads to immature, noninfectious virions. When administered to Pr55Gag-expressing insect cells (Sf9), DSB inhibits the assembly and budding of membrane-enveloped virus-like particles (VLP). In order to explore the possibility that viral factors could modulate the susceptibility to DSB of the VLP assembly process, several viral proteins were coexpressed individually with Pr55Gag in DSB-treated cells, and VLP yields assayed in the extracellular medium.Results: Wild-type Vif (Vifwt) restored the VLP production in DSB-treated cells to levels observed in control, untreated cells. DSB-counteracting effect was also observed with Vif mutants defective in encapsidation into VLP, suggesting that packaging and anti-DSB effect were separate functions in Vif. The anti-DSB effect was abolished for VifC133S and VifS116V, two mutants which lacked the zinc binding domain (ZBD) formed by the four H(108)C(114)C(133)H(139) coordinates with a Zn atom. Electron microscopic analysis of cells coexpressing Pr55Gag and Vifwt showed that a large proportion of VLP budded into cytoplasmic vesicles and were released from Sf9 cells by exocytosis. However, in the presence of mutant VifC133S or VifS116V, most of the VLP assembled and budded at the plasma membrane, as in control cells expressing Pr55Gag alone.Conclusion: The function of HIV-1 Vif protein which negated the DSB inhibition of VLP assembly was independent of its packaging capability, but depended on the integrity of ZBD. In the presence of Vifwt, but not with ZBD mutants VifC133S and VifS116V, VLP were redirected to a vesicular compartment and egressed via the exocytic pathway

Assessing Current and Future Needs of Residents Aging in the Town of Andover

This report describes the collaborative efforts undertaken by the Town of Andover Division of Elder Services and the Center for Social and Demographic Research on Aging, within the McCormack Graduate School at the University of Massachusetts Boston. Beginning in Fall 2014, these organizations joined to conduct a needs assessment to investigate the needs, interests, preferences and opinions of the Town’s older resident population, with respect to aging in Andover. The focus of this report is on two cohorts of Andover residents—those who are age 50 to 59 (referred to as “Boomers”) and the cohort of individuals who are currently age 60 and older (“Seniors”). Within the older cohort of Seniors, we also conducted selected analyses on subgroups (e.g., ages 60 to 79; 60 to 69; 70 to 79; and 80 and older) to highlight important differences by age group. During this assessment, several research methods were utilized in order to sketch a multidimensional image of the Town’s older residents that could be used to plan and implement current and future services for older residents in Andover. We began the process by examining public data from the U.S. Census Bureau to describe basic demographic characteristics, as well as economic characteristics, disability status, and living situations of older people in the Town. Early in the project we invited Town residents to attend a community forum, to better understand how residents perceive current and future aging-related needs of the Town. We used information gathered at this meeting to develop a survey instrument to be administered to a randomly selected sample of residents from both age cohorts. We conducted two focus groups to obtain feedback from various stakeholders who regularly interact with older residents, regarding issues and concerns about aging in Andover. We conducted interviews with four key stakeholders to acquire input from local experts on the implications of the aging population, and the functioning of the Center at Punchard. We produced three maps depicting town resources that are perceived as assets to aging in place in Andover by older adult residents. Finally, we conducted a comparison of Senior Centers in three towns that are similar to Andover to assess how needs of older adults are met in other nearby communities. Collectively, the content of this report is intended to inform the Andover Division of Elder Services and the Center at Punchard, along with other offices within the Town with a stake in the aging of Andover, and organizations that provide services to older residents, as well as those who advocate for older people, and community members at large

Charm mass dependence of the weak Hamiltonian in chiral perturbation theory

Suppose that the weak interaction Hamiltonian of four-flavour SU(4) chiral effective theory is known, for a small charm quark mass m_c. We study how the weak Hamiltonian changes as the charm quark mass increases, by integrating it out within chiral perturbation theory to obtain a three-flavour SU(3) chiral theory. We find that the ratio of the SU(3) low-energy constants which mediate Delta I=1/2 and Delta I=3/2 transitions, increases rather rapidly with m_c, as \sim m_c ln (1/m_c). The logarithmic effect originates from "penguin-type" charm loops, and could represent one of the reasons for the Delta I=1/2 rule.Comment: 20 pages. v2: references and clarifications added, published versio