6,850 research outputs found

    Leisure activity for dementia prevention. More work to be done.

    Get PDF
    Dementia prevention is a worldwide priority because of the aging population, devastating consequences for patients and families, and the drain on societal resources. In the absence of disease-modifying therapies, there is interest in lifestyle factors that might prevent or delay the onset of dementia. Chief among these is leisure activity, conceptualized as pursuits undertaken for relaxation or pleasure after completion of essential chores and occupational responsibilities. Leisure activity invokes the cornerstones of cognitive reserve: mental activity, physical activity, and social engagement

    Reed-Muller codes for random erasures and errors

    Full text link
    This paper studies the parameters for which Reed-Muller (RM) codes over GF(2)GF(2) can correct random erasures and random errors with high probability, and in particular when can they achieve capacity for these two classical channels. Necessarily, the paper also studies properties of evaluations of multi-variate GF(2)GF(2) polynomials on random sets of inputs. For erasures, we prove that RM codes achieve capacity both for very high rate and very low rate regimes. For errors, we prove that RM codes achieve capacity for very low rate regimes, and for very high rates, we show that they can uniquely decode at about square root of the number of errors at capacity. The proofs of these four results are based on different techniques, which we find interesting in their own right. In particular, we study the following questions about E(m,r)E(m,r), the matrix whose rows are truth tables of all monomials of degree ≀r\leq r in mm variables. What is the most (resp. least) number of random columns in E(m,r)E(m,r) that define a submatrix having full column rank (resp. full row rank) with high probability? We obtain tight bounds for very small (resp. very large) degrees rr, which we use to show that RM codes achieve capacity for erasures in these regimes. Our decoding from random errors follows from the following novel reduction. For every linear code CC of sufficiently high rate we construct a new code Câ€ČC', also of very high rate, such that for every subset SS of coordinates, if CC can recover from erasures in SS, then Câ€ČC' can recover from errors in SS. Specializing this to RM codes and using our results for erasures imply our result on unique decoding of RM codes at high rate. Finally, two of our capacity achieving results require tight bounds on the weight distribution of RM codes. We obtain such bounds extending the recent \cite{KLP} bounds from constant degree to linear degree polynomials

    Comparing and characterizing some constructions of canonical bases from Coxeter systems

    Full text link
    The Iwahori-Hecke algebra H\mathcal{H} of a Coxeter system (W,S)(W,S) has a "standard basis" indexed by the elements of WW and a "bar involution" given by a certain antilinear map. Together, these form an example of what Webster calls a pre-canonical structure, relative to which the well-known Kazhdan-Lusztig basis of H\mathcal{H} is a canonical basis. Lusztig and Vogan have defined a representation of a modified Iwahori-Hecke algebra on the free Z[v,v−1]\mathbb{Z}[v,v^{-1}]-module generated by the set of twisted involutions in WW, and shown that this module has a unique pre-canonical structure satisfying a certain compatibility condition, which admits its own canonical basis which can be viewed as a generalization of the Kazhdan-Lusztig basis. One can modify the parameters defining Lusztig and Vogan's module to obtain other pre-canonical structures, each of which admits a unique canonical basis indexed by twisted involutions. We classify all of the pre-canonical structures which arise in this fashion, and explain the relationships between their resulting canonical bases. While some of these canonical bases are related in a trivial fashion to Lusztig and Vogan's construction, others appear to have no simple relation to what has been previously studied. Along the way, we also clarify the differences between Webster's notion of a canonical basis and the related concepts of an IC basis and a PP-kernel.Comment: 32 pages; v2: additional discussion of relationship between canonical bases, IC bases, and P-kernels; v3: minor revisions; v4: a few corrections and updated references, final versio

    List Decoding of Matrix-Product Codes from nested codes: an application to Quasi-Cyclic codes

    Get PDF
    A list decoding algorithm for matrix-product codes is provided when C1,...,CsC_1,..., C_s are nested linear codes and AA is a non-singular by columns matrix. We estimate the probability of getting more than one codeword as output when the constituent codes are Reed-Solomon codes. We extend this list decoding algorithm for matrix-product codes with polynomial units, which are quasi-cyclic codes. Furthermore, it allows us to consider unique decoding for matrix-product codes with polynomial units

    Anxiety and depression in young and middle aged hypertensive and normotensive subjects

    Get PDF
    This study examined the effects of essential hypertension on measures of anxiety and depression for two age groups of hypertensive (free from hypertension-related pathology and/or cardiovascular disease) and normotensive subjects. Hypertensive subjects had significantly higher State Anxiety scores and Zung Depression scores than did normotensive subjects. These differences between the blood pressure groups were due largely to the scores of the younger hypertensive subjects. The results of the present study are consistent with previous results from our laboratory that have found that younger hypertensives differed (relative to controls) from middle aged hypertensives on measures, such as, symptoms reported on the Cornell Medical Index and WAIS Performance scores. The results of the present study were discussed within the context of age associated differences in response to hypertension and factors that might account for these differences

    Re-theorizing the “Structure–Agency” Relationship: Figurational Theory, Organizational Change and the Gaelic Athletic Association

    Get PDF
    This article illustrates how the figurational sociology associated with Norbert Elias provides an alternative theoretical framework for explaining the relationship between, ‘individualorganization- society’ and organizational change, and in so doing transverses what is conceived as a false dichotomy between structure and agency. Through an historical case study of the Gaelic Athletic Association in Ireland, the ‘individual-organization-society’ relationship is conceptualized as overlapping figurations and organizational change is explained as figurational dynamics—the shifting social interdependencies between the individuals and groups comprising an organization, between that organization and other organizations, between social groups on a higher level of integration and competition. In tandem with this, the article illustrates how changes in the sources of power and identity are connected with these figurational dynamics

    Mid-Infrared Emission from E+A Galaxies in the Coma Cluster

    Full text link
    We have used ISO to observe at 12ÎŒ\mum seven E+A galaxies plus an additional emission line galaxy, all in the Coma cluster. E+A galaxies lacking narrow emission lines have 2.2ÎŒ\mum to 12ÎŒ\mum flux density ratios or limits similar to old stellar populations (typical of early-type galaxies). Only galaxies with emission lines have enhanced 12ÎŒ\mum flux density. Excess 12ÎŒ\mum emission is therefore correlated with the presence of on-going star formation or an active galactic nucleus (AGN). By comparing the current star formation rates with previous rates estimated from the Balmer absorption features, we divide the galaxies into two groups: those for which star formation has declined significantly following a dramatic peak ∌\sim 1 Gyr ago; and those with a significant level of ongoing star formation or/and an AGN. There is no strong difference in the spatial distribution on the sky between these two groups. However, the first group has systemic velocities above the mean cluster value and the second group below that value. This suggests that the two groups differ kinematically. Based on surveys of the Coma cluster in the radio, the IRAS sources, and galaxies detected in Hα\alpha emission, we sum the far infrared luminosity function of galaxies in the cluster. We find that star formation in late type galaxies is probably the dominant component of the Coma cluster far infrared luminosity. The presence of significant emission from intracluster dust is not yet firmly established. The member galaxies also account for most of the far infrared output from nearby rich clusters in general.Comment: AAS Latex, accepted for publication in Ap

    Comparison of Relativistic Nucleon-Nucleon Interactions

    Get PDF
    We investigate the difference between those relativistic models based on interpreting a realistic nucleon-nucleon interaction as a perturbation of the square of a relativistic mass operator and those models that use the method of Kamada and Gl\"ockle to construct an equivalent interaction to add to the relativistic mass operator. Although both models reproduce the phase shifts and binding energy of the corresponding non-relativistic model, they are not scattering equivalent. The example of elastic electron-deuteron scattering in the one-photon-exchange approximation is used to study the sensitivity of three-body observables to these choices. Our conclusion is that the differences in the predictions of the two models can be understood in terms of the different ways in which the relativistic and non-relativistic SS-matrices are related. We argue that the mass squared method is consistent with conventional procedures used to fit the Lorentz-invariant cross section as a function of the laboratory energy.Comment: Revtex 13 pages, 5 figures, corrected some typo

    Extracts from cerrado plants as antioxidant agents on in vitro embryo production.

    Get PDF
    Proceedings of the 31st Annual Meeting of the Brazilian Embryo Technology Society (SBTE); Cabo de Santo Agostinho, PE, Brazil, August 17th to 19th, 2017. Abstract
    • 

    corecore