A comprehensive assessment of risk factors for falls in middle-aged adults: co-ordinated analyses of cohort studies in four countries

© 2019, International Osteoporosis Foundation and National Osteoporosis Foundation. Summary: We identified demographic, health and lifestyle factors associated with falls in adults aged 50–64 years from Australia, The Netherlands, Great Britain and Ireland. Nearly all factors were associated with falls, but there were differences between countries and between men and women. Existing falls prevention programs may also benefit middle-aged adults. Introduction: Between ages 40–44 and 60–64 years, the annual prevalence of falls triples suggesting that middle age may be a critical life stage for preventive interventions. We aimed to identify demographic, health and lifestyle factors associated with falls in adults aged 50–64 years. Methods: Harmonised data were used from four population-based cohort studies based in Australia (Australian Longitudinal Study on Women’s Health, n = 10,641, 51–58 years in 2004), Ireland (The Irish Longitudinal Study on Ageing, n = 4663, 40–64 years in 2010), the Netherlands (Longitudinal Ageing Study Amsterdam, n = 862, 55–64 years in 2012–13) and Great Britain (MRC National Survey of Health and Development, n = 2987, 53 years in 1999). Cross-sectional and prospective associations of 42 potential risk factors with self-reported falls in the past year were examined separately by cohort and gender using logistic regression. In the absence of differences between cohorts, estimates were pooled using meta-analysis. Results: In cross-sectional models, nearly all risk factors were associated with fall risk in at least one cohort. Poor mobility (pooled OR = 1.71, CI = 1.34–2.07) and urinary incontinence (OR range = 1.53–2.09) were consistently associated with falls in all cohorts. Findings from prospective models were consistent. Statistically significant interactions with cohort and sex were found for some of the risk factors. Conclusion: Risk factors known to be associated with falls in older adults were also associated with falls in middle age. Compared with findings from previous studies of older adults, there is a suggestion that specific risk factors, for example musculoskeletal conditions, may be more important in middle age. These findings suggest that available preventive interventions for falls in older adults may also benefit middle-aged adults, but tailoring by age, sex and country is required

Should prevention of falls start earlier? Co-ordinated analyses of harmonised data on falls in middle-aged adults across four population-based cohort studies

© 2018 Peeters et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The prevalence of risk factors for falls increases during middle-age, but the prevalence of falls in this age-range is often overlooked and understudied. The aim was to calculate the prevalence of falls in middle-aged adults (aged 40–64 years) from four countries. Data were from four population-based cohort studies from Australia (Australian Longitudinal Study on Women’s Health, n = 10556, 100% women, 51–58 years in 2004), Ireland (The Irish Longitudinal Study on Ageing, n = 4968, 57.5% women, 40–64 years in 2010), the Netherlands (Longitudinal Aging Study Amsterdam, n = 862, 51.6% women, 55–64 years in 2012–13) and Great Britain (MRC National Survey of Health and Development, n = 2821, 50.9% women, 53 years in 1999). In each study, falls assessment was based on recall of any falls in the past year. The prevalence of falls was calculated for the total group, for each country, for men and women separately, and for 5-year age-bands. The prevalence was higher in Australia (27.8%, women only) and the Netherlands (25.1%) than in Ireland (17.6%) and Great Britain (17.8%, p<0.001). Women (27.0%) had higher prevalences than men (15.2%, p<0.001). The prevalence increased from 8.7% in 40–44 year olds to 29.9% in 60–64 year olds in women, and from 14.7% in 45–49 year olds to 15.7% in 60–64 year olds in men. Even within 5-year age-bands, there was substantial variation in prevalence between the four cohorts. Weighting for age, sex and education changed the prevalence estimates by less than 2 percentage points. The sharp increase in prevalence of falls in middle-age, particularly among women supports the notion that falls are not just a problem of old age, and that middle-age may be a critical life stage for preventive interventions

Low temperature properties of holographic condensates

In the current work we study various models of holographic superconductors at low temperature. Generically the zero temperature limit of those models are solitonic solution with a zero sized horizon. Here we generalized simple version of those zero temperature solutions to small but non-zero temperature T. We confine ourselves to cases where near horizon geometry is AdS^4. At a non-zero temperature a small horizon would form deep inside this AdS^4 which does not disturb the UV physics. The resulting geometry may be matched with the zero temperature solution at an intermediate length scale. We understand this matching from separation of scales by setting up a perturbative expansion in gauge potential. We have a better analytic control in abelian case and quantities may be expressed in terms of hypergeometric function. From this we calculate low temperature behavior of various quatities like entropy, charge density and specific heat etc. We also calculate various energy gaps associated with p-wave holographic superconductor to understand the underlying pairing mechanism. The result deviates significantly from the corresponding weak coupling BCS counterpart.Comment: 17 Page

Early-Time Energy Loss in a Strongly-Coupled SYM Plasma

We carry out an analytic study of the early-time motion of a quark in a strongly-coupled maximally-supersymmetric Yang-Mills plasma, using the AdS/CFT correspondence. Our approach extracts the first thermal effects as a small perturbation of the known quark dynamics in vacuum, using a double expansion that is valid for early times and for (moderately) ultrarelativistic quark velocities. The quark is found to lose energy at a rate that differs significantly from the previously derived stationary/late-time result: it scales like T^4 instead of T^2, and is associated with a friction coefficient that is not independent of the quark momentum. Under conditions representative of the quark-gluon plasma as obtained at RHIC, the early energy loss rate is a few times smaller than its late-time counterpart. Our analysis additionally leads to thermally-corrected expressions for the intrinsic energy and momentum of the quark, in which the previously discovered limiting velocity of the quark is found to appear naturally.Comment: 39 pages, no figures. v2: Minor corrections and clarifications. References added. Version to be published in JHE

On semiclassical approximation for correlators of closed string vertex operators in AdS/CFT

We consider the 2-point function of string vertex operators representing string state with large spin in AdS_5. We compute this correlator in the semiclassical approximation and show that it has the expected (on the basis of state-operator correspondence) form of the strong-coupling limit of the 2-point function of single trace minimal twist operators in gauge theory. The semiclassical solution representing the stationary point of the path integral with two vertex operator insertions is found to be related to the large spin limit of the folded spinning string solution by a euclidean continuation, transformation to Poincare coordinates and conformal map from cylinder to complex plane. The role of the source terms coming from the vertex operator insertions is to specify the parameters of the solution in terms of quantum numbers (dimension and spin) of the corresponding string state. Understanding further how similar semiclassical methods may work for 3-point functions may shed light on strong-coupling limit of the corresponding correlators in gauge theory as was recently suggested by Janik et al in arXiv:1002.4613.Comment: 19 pages, 1 figure; minor corrections, references added, footnote below eq. (4.5) adde

Holographic three-point functions of semiclassical states

We calculate the holographic three-point functions in N = 4 super-Yang-Mills theory in the case when two of the operators are semiclassical and one is dual to a supergravity mode. We further discuss the transition to the regime when all three operators are semiclassical.Comment: 17 pages, 3 figures; v2: refs. added, discussion in sec. 2.1 expanded; v3: misprint in (2.28) corrected, published versio

On the spectral problem of N=4 SYM with orthogonal or symplectic gauge group

We study the spectral problem of N=4 SYM with gauge group SO(N) and Sp(N). At the planar level, the difference to the case of gauge group SU(N) is only due to certain states being projected out, however at the non-planar level novel effects appear: While 1/N-corrections in the SU(N) case are always associated with splitting and joining of spin chains, this is not so for SO(N) and Sp(N). Here the leading 1/N-corrections, which are due to non-orientable Feynman diagrams in the field theory, originate from a term in the dilatation operator which acts inside a single spin chain. This makes it possible to test for integrability of the leading 1/N-corrections by standard (Bethe ansatz) means and we carry out various such tests. For orthogonal and symplectic gauge group the dual string theory lives on the orientifold AdS5xRP5. We discuss various issues related to semi-classical strings on this background.Comment: 25 pages, 3 figures. v2: Minor clarifications, section 5 expande

Holographic current correlators at finite coupling and scattering off a supersymmetric plasma

By studying the effect of the order(\alpha'^3) string theory corrections to type IIB supergravity, including those corrections involving the Ramond-Ramond five-form field strength, we obtain the corrected equations of motion of an Abelian perturbation of the AdS_5-Schwarzschild black hole. We then use the gauge theory/string theory duality to examine the coupling-constant dependence of vector current correlators associated to a gauged U(1) sub-group of the global R-symmetry group of strongly-coupled N=4 supersymmetric Yang-Mills theory at finite temperature. The corrections induce a set of higher-derivative operators for the U(1) gauge field, but their effect is highly suppressed. We thus find that the order(\alpha'^3) corrections affect the vector correlators only indirectly, through the corrected metric. We apply our results to investigate scattering off a supersymmetric Yang-Mills plasma at low and high energy. In the latter regime, where Deep Inelastic Scattering is expected to occur, we find an enhancement of the plasma structure functions in comparison with the infinite 't Hooft coupling result.Comment: 38 pages, 6 figures, minor clarifications added, typos corrected, references adde

d+idd+id Holographic Superconductors

A holographic model of $d+id$ superconductors based on the action proposed by Benini, Herzog, and Yarom [arXiv:1006.0731] is studied. This model has a charged spin two field in an AdS black hole spacetime. Working in the probe limit, the normalizable solution of the spin two field in the bulk gives rise to a $d+id$ superconducting order parameter at the boundary of the AdS. We calculate the fermion spectral function in this\ superconducting background and confirm the existence of fermi arcs for non-vanishing Majorana couplings. By changing the relative strength $\gamma$ of the $d$ and $id$ condensations, the position and the size of the fermi arcs are changed. When $\gamma =1$, the spectrum becomes isotropic and the spectral function is s-wave like. By changing the fermion mass, the fermi momentum is changed. We also calculate the conductivity for these holographic $d+id$ superconductors where time reversal symmetry has been broken spontaneously. A non-vanishing Hall conductivity is obtained even without an external magnetic field.Comment: 24 pages,17 figures, Add more discussions on hall conductivity, two new figures, Matched with published versio