1,732 research outputs found
Is the incidence of dementia declining?
No full textAction on preventative health could lower the risk of dementia for future generations, argues this report.
Executive summary
The world-wide projections of the prevalence of dementia in the coming decades have been a source of great concern to health systems and societies around the world. The World Alzheimer Report 2010 estimated that there were 36 million people with dementia in 2010, with an expected doubling every 20 years to nearly 115 million in 2050. These sobering figures are based on assumptions that the age-adjusted prevalence of dementia would remain constant and the population would continue to age at the current rate.
The assumption that the incidence of dementia will remain stable is now being put into question. There is emerging evidence to suggest that the incidence of dementia in older individuals may be declining. It appears that this change may be recent and has possibly occurred only in the last one to two decades. It may also be restricted so far to high income countries, although data from low and middle income countries are lacking.
The reasons for this change are not understood, but education, more stimulating environments and better control of vascular risk factors may have contributed. The data are still preliminary and more studies are needed to establish the extent of this change and understand its causes. It should be noted that the decline is not large enough to offset the increase in prevalence of dementia due to the ageing of the population and therefore investment and efforts to develop better treatments and care for people with dementia need to continue.
The fact that dementia rates are malleable is an encouraging finding but the reduction cannot be taken for granted as gains in population health can easily be lost if societies do not remain vigilant and continually proactive. These preliminary findings provide a strong argument for large scale Government investment in dementia-prevention strategies, which should start from early life
Effect of administration of intestinal anthelmintic drugs on haemoglobin: systematic review of randomised controlled trials
No full textObjective: To evaluate the effect of routine administration of intestinal anthelmintic drugs on haemoglobin.Design: Systematic review of randomised controlled trials.Data sources: Electronic databases and hand search of reviews, bibliographies of books, and abstracts and proceedings of international conferences.Study selection: Included studies were randomised or quasi-randomised controlled trials using an intestinal anthelmintic agent in the intervention group, in which haemoglobin was evaluated as an outcome measure. Trials in which treatment for schistosoma (praziquantel) was given exclusively to the intervention group were excluded.Results: The search identified 14 eligible randomised controlled trials. Data were available for 7829 subjects, of whom 4107 received an anthelmintic drug and 3722 received placebo. The pooled weighted mean difference (random effect model) of the change in haemoglobin was 1.71 (95% confidence interval 0.70 to 2.73) g/l (P<0.001; test for heterogeneity: Cochran Q=51.17, P<0.001; I2=61% (37% to 76%)). With the World Health Organization's recommended haemoglobin cut-offs of 120 g/l in adults and 110 g/l in children, the average estimated reduction in prevalence of anaemia ranged from 1.1% to 12.4% in adults and from 4.4% to 21.0% in children. The estimated reductions in the prevalence of anaemia increased with lower haemoglobin cut-offs used to define anaemia.Conclusions: Routine administration of intestinal anthelmintic agents results in a marginal increase in haemoglobin (1.71 g/l), which could translate on a public health scale into a small (5% to 10%) reduction in the prevalence of anaemia in populations with a relatively high prevalence of intestinal helminthiasis
Generalized Burgers equations and Euler–Painlevé transcendents. III
No full textIt was proposed earlier [P. L. Sachdev, K. R. C. Nair, and V. G. Tikekar, J. Math. Phys. 27, 1506 (1986); P. L. Sachdev and K. R. C. Nair, ibid. 28, 977 (1987)] that the Euler–Painlevé equations y(d2y/dη2)+a(dy/dη)2+f(η)y(dy/dη)+g(η)y2+b(dy/dη)+c=0 represent generalized Burgers equations (GBE's) in the same way as Painlevé equations represent the Korteweg–de Vries type of equations. The earlier studies were carried out in the context of GBE's with damping and those with spherical and cylindrical symmetry. In the present paper, GBE's with variable coefficients of viscosity and those with inhomogeneous terms are considered for their possible connection to Euler–Painleve equations. It is found that the Euler–Painlevé equation, which represents the GBE ut+uβux=(δ/2)g(t)uxx, g(t)=(1+t)n, β>0, has solutions, which either decay or oscillate at η=±∞, only when -1<n<1. The solutions are shocklike when η=1. On the other hand, they oscillate over the whole real line when n=-1. Furthermore, the solutions monotonically decay both at η=+∞ and η=-∞, that is, they have a single hump form if β≥βn=(1-n)/(1+n). For β<βn, the solutions have an oscillatory behavior either at η=+∞ or at η=-∞, or at η=+∞ and η=-∞. For β=βn, there exists a single parameter family of exact single hump solutions, similar to those found for the nonplanar Burgers equations in Paper II. Thus the parametric value β=βn seems to bifurcate the families of solutions, which remain bounded at η=±∞. Other GBE's considered here are also found to be reducible to Euler–Painlevé equations.The scope of these equations is broadened by relating them to a large number of nonlinear DE's selected from the compendia of Kamke [Differential Gleichungen : Lô sungsmethoden und Lô sungen (Akademische Verlagsgesellschaft, Leipzig, 1943)] and Murphy [Ordinary Differential Equations and their Solutions (Van Nostrand, Princeton, NJ, 1960)]. These latter equations arise from a wide range of physical applications and are of some historical interest as well. They are all special cases of a slightly generalized form of the Euler–painleve equation
Generalized Burgers equations and Euler–Painlevé transcendents. II
No full textIt was proposed earlier [P. L. Sachdev, K. R. C. Nair, and V. G. Tikekar, J. Math. Phys. 27, 1506 (1986)] that the Euler–Painlevé equation yy"+ay'2+f(x)yy'+g(x) y2+by'+c=0 represents the generalized Burgers equations (GBE's) in the same manner as Painlevé equations do the KdV type. The GBE was treated with a damping term in some detail. In this paper another GBE ut+uaux+Ju/2t =(gd/2)uxx (the nonplanar Burgers equation) is considered. It is found that its self-similar form is again governed by the Euler–Painlevé equation. The ranges of the parameter a for which solutions of the connection problem to the self-similar equation exist are obtained numerically and confirmed via some integral relations derived from the ODE's. Special exact analytic solutions for the nonplanar Burgers equation are also obtained. These generalize the well-known single hump solutions for the Burgers equation to other geometries J=1,2; the nonlinear convection term, however, is not quadratic in these cases. This study fortifies the conjecture regarding the importance of the Euler–Painlevé equation with respect to GBE's
Comparison of weight-for-height and BMI-for-age for estimating overnutrition burden in under-five population with high stunting prevalence
No full textBackground: Overnourished under-five children are anthropometrically classified as either being at possible risk of overweight, overweight or obese and defined so, when either weight-for-height or Body-Mass-Index-for-age (BMI-for-age) are >1SD to 2SD, >2SD to 3SD and >3SD, respectively of the analogous World Health Organization standards. Aim: To compare weight-for-height and BMI-for-age definitions for quantifying overnutrition burden. Methods: Theoretical consequences of ignoring age were evaluated by comparing, at varying height-for-age zscores, the age- and sex-specific cut-offs of BMI that would define overnutrition with these two metrics. Overnutrition prevalence was then compared in simulated populations (short, intermediate and tall) and real-life datasets from India. Results: In short (-2SD) children, the BMI cut-offs with weight-for-height criteria were lower in comparison to BMI-for-age till 7-8 months, but higher at later ages. In National Family Health Survey-4, India dataset (short population), overnutrition (>1SD) prevalence with weight-for-height was higher from 0-0.5 years (exclusive breastfeeding age), but lower at subsequent ages. The prevalence difference (weight-for-height - BMI-for-age) in 0.5-5 years was -2.26% (6.57% vs 8.83%); this attenuated in 0-5 years (-1.55%; 7.23% vs 8.78%). The discrepancy was maximal for stunted children and was lower in girls. A similar pattern, of lower magnitude, was observed for overweight (>2SD) comparison. In intermediate and tall populations, there were no meaningful differences. Conclusion: The two definitions produce cut-offs, and hence estimates of overnutrition, that differ with the age, sex, and height of under-five children. The relative invariance, with age and height, of BMI-for-age, favours its use
Strongly Correlated Metal Built from Sachdev-Ye-Kitaev Models
No full textProminent systems like the high-Tc cuprates and heavy fermions display intriguing features going beyond the quasiparticle description. The Sachdev-Ye-Kitaev (SYK) model describes a (0+1)D quantum cluster with random all-to-all four-fermion interactions among N fermion modes which becomes exactly solvable as N→∞, exhibiting a zero-dimensional non-Fermi-liquid with emergent conformal symmetry and complete absence of quasiparticles. Here we study a lattice of complex-fermion SYK dots with random intersite quadratic hopping. Combining the imaginary time path integral with real time path integral formulation, we obtain a heavy Fermi liquid to incoherent metal crossover in full detail, including thermodynamics, low temperature Landau quasiparticle interactions, and both electrical and thermal conductivity at all scales. We find linear in temperature resistivity in the incoherent regime, and a Lorentz ratio L≡(κρ/T) varies between two universal values as a function of temperature. Our work exemplifies an analytically controlled study of a strongly correlated metal.</p
Exact time-dependent flows for non-shallow water equations
No full textTwo classes of exact solutions of non-shallow water equations are found. The first class is governed after several transformations of the original system, by a third order non-linear ordinary differential equation which is singular at both ends of the interval of interest, and which describes flows between two intersecting planes. The second class is expressed in terms of incomplete Beta functions and delineates flows under a free surface which is a function of time only. The solutions are compared with those found earlier by Freeman (1972), Sachdev (1980), and Longuet-Higgins (1972)
Safety and Effectiveness of Smooth Incision Lenticular Keratomileusis (SILK™) Using the ELITA™ Femtosecond Laser System for Correction of Myopic and Astigmatic Refractive Errors [Response to Letter]
No full textMahipal S Sachdev,1 Rohit Shetty,2 Pooja Khamar,2 Raghav Malik,1 Brian L Schwam,3 Ying Wang,3 Hong Fu,3 Andrew P Voorhees,3 Michal Laron3 1Centre for Sight, New Delhi, India; 2Narayana Nethralaya Eye Hospital, Bangalore, India; 3Johnson & Johnson Surgical Vision, Inc., Milpitas, CA, USACorrespondence: Michal Laron, Johnson and Johnson Surgical Vision, Inc, 510 Cottonwood Drive, Milpitas, CA, 95035, USA, Tel +1 408 273 5802, Email [email protected]
Coronary microvascular dysfunction in male patients with Anderson-Fabry disease and the effect of treatment with alpha galactosidase A
No full textObjective: To measure coronary flow reserve (CFR), an index of microvascular function, in Anderson-Fabry disease (AFD) at baseline and after enzyme replacement therapy (ERT). Methods and results: Mean (SD) myocardial blood flow (MBF) at rest and during hyperaemia ( adenosine 140 mg/kg/min) was measured in 10 male, non-smoking patients (53.8 (10.9) years, cholesterol 5.5 (1.3) mmol/l) and in 24 age matched male, non-smoking controls (52.0 (7.6) years, cholesterol 4.5 (0.6) mmol/l) by positron emission tomography ( PET). Resting and hyperaemic MBF and CFR ( hyperaemic/resting MBF) were reduced in patients compared with controls ( 0.99 (0.17) v 1.17 (0.25) ml/g/ min, p< 0.05; 1.37 (0.32) v 3.44 (0.78) ml/g/ min, p< 0.0001; and 1.41 (0.39) v 3.03 (0.85), p< 0.0001, respectively). This coronary microvascular dysfunction was independent of cholesterol concentrations. PET was repeated in five patients after 10.1 (2.3) months of ERT; resting and hyperaemic MBF and CFR were unchanged after ERT ( 0.99 (0.16) v 0.99 ( 0.16) ml/g/ min; 1.56 (0.29) v 1.71 (0.3) ml/g/ min; and 1.6 (0.37) v 1.74 (0.28), respectively; all not significant). Conclusions: The results of the present study show that patients with AFD have very abnormal coronary microvascular function. These preliminary data suggest that ERT has no effect on coronary microvascular dysfunction. Further work is necessary to determine whether treatment at an earlier stage in the course of the disease may improve coronary microvascular function in patients with AFD
Instabilities induced by variation of Brunt–Väisälä frequency in compressible stratified shear flows
No full textThe stability characteristics of a Helmholtz velocity profile in a stably stratified, compressible fluid in the presence of a lower rigid boundary are studied. A jump in the Brunt-Väisälä frequency at a level different from the shear zone is introduced and the variation of the Brunt–Väisälä frequency with respect to the vertical coordinate in the middle layer of the three-layered model is considered. An analytic solution in each of the layers is obtained, and the dispersion relation is solved numerically for parameters relevant to the model. The effect of shear in the lowermost layer of the three-layered model for a Boussinesq fluid is discussed. The results are compared with the earlier studies of Lindzen and Rosenthal, and Sachdev and Satya Narayanan. In the present model, new unstable modes with larger growth rates are obtained and the most unstable gravity wave modes are found to agree closely with the observed ones at various heights
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