1,291 research outputs found
Properties of the Ideal Ginzburg-Landau Vortex Lattice
The magnetization curves M(H) for ideal type-II superconductors and the
maximum, minimum, and saddle point magnetic fields of the vortex lattice are
calculated from Ginzburg-Landau theory for the entire ranges of applied
magnetic fields Hc1 <= H < Hc2 or inductions 0 <= B < Hc2 and Ginzburg-Landau
parameters sqrt(1/2) <= kappa <= 1000. Results for the triangular and square
flux-line lattices are compared with the results of the circular cell
approximation. The exact magnetic field B(x,y) and magnetization M(H, kappa)
are compared with often used approximate expressions, some of which deviate
considerably or have limited validity. Useful limiting expressions and
analytical interpolation formulas are presented.Comment: 11 pages, 8 figure
Variational theory of flux-line liquids
We formulate a variational (Hartree like) description of flux line liquids
which improves on the theory we developed in an earlier paper [A.M. Ettouhami,
Phys. Rev. B 65, 134504 (2002)]. We derive, in particular, how the massive term
confining the fluctuations of flux lines varies with temperature and show that
this term vanishes at high enough temperatures where the vortices behave as
freely fluctuating elastic lines.Comment: 10 pages, 1 postscript figur
Small-scale topology of solar atmosphere dynamics I: wave sources and wave diffraction
We study the small-scale topology of dynamical phenomena in the quiet-sun internet w ork atmosphere,using short-duration Fourier analysis of high-resolution filtergram sequences to obtain statistical estimates for the co-location probability of different fine-structure elements and wave modes. In this initial paper w e concentrate on the topology of short-duration Fourier amplitude maps for the photosphere and the simultaneously observed o verlying chromosphere. We find that these maps portray acomplex mix of global modes and locally excited w aveswhich necessitates a statistical approach. Variousaspects including mesoscale patterning indicate the presence of subsurface w avesources and of subsurface w avediffraction by convective inhomogeneities
On photospheric flows and chromospheric corks
Proper motions of granules are measured by local correlation tracking on a 4.5 h image
sequence obtained with the Swedish Vacuum Tower Telescope at La Palma. A 2arcsec spati l low-
pass filter is applied to obtain meso-scale flow patterns.We find that their characteristic lifetime
(1 /e value)has a lower limit of five to six hours.Comparison with a simultaneous co-spatial
sequence of chromospheric K 2V images shows that these flows sweep supergranulation cells clean
in about the s me period. A chromospheric "persistent flasher", seen during three hours in K 2V ,
migrates to the magnetic network as if it were photospheric cork
Exercise reduces sick leave in patients with non-acute non-specific low back pain: a meta-analysis
Approximate Analytical Solutions to the Initial Data Problem of Black Hole Binary Systems
We present approximate analytical solutions to the Hamiltonian and momentum
constraint equations, corresponding to systems composed of two black holes with
arbitrary linear and angular momentum. The analytical nature of these initial
data solutions makes them easier to implement in numerical evolutions than the
traditional numerical approach of solving the elliptic equations derived from
the Einstein constraints. Although in general the problem of setting up initial
conditions for black hole binary simulations is complicated by the presence of
singularities, we show that the methods presented in this work provide initial
data with and norms of violation of the constraint equations
falling below those of the truncation error (residual error due to
discretization) present in finite difference codes for the range of grid
resolutions currently used. Thus, these data sets are suitable for use in
evolution codes. Detailed results are presented for the case of a head-on
collision of two equal-mass M black holes with specific angular momentum 0.5M
at an initial separation of 10M. A straightforward superposition method yields
data adequate for resolutions of , and an "attenuated" superposition
yields data usable to resolutions at least as fine as . In addition, the
attenuated approximate data may be more tractable in a full (computational)
exact solution to the initial value problem.Comment: 6 pages, 5 postscript figures. Minor changes and some points
clarified. Accepted for publication in Phys. Rev.
Instanton Contribution to the Quark Form Factor
The nonperturbative effects in the quark form factor are considered in the
Wilson loop formalism. The properties of the Wilson loops with cusp
singularities are studied taking into account the perturbative and
nonperturbative contributions, where the latter are considered within the
framework of the instanton liquid model. For the integration path corresponding
to this form factor -- the angle with infinite sides -- the explicit expression
for the vacuum expectation value of the Wilson operator is found to leading
order. The calculations are performed in the weak-field limit for the instanton
vacuum contribution and compared with the one- and two-loop order results for
the perturbative part. It is shown that the instantons produce the powerlike
corrections to the perturbative result, which are comparable in magnitude with
the perturbative part at the scale of order of the inverse average instanton
size. It is demonstrated that the instanton contributions to the quark form
factor are exponentiated to high orders in the small instanton density
parameter.Comment: Version coincident with the journal publication. LaTeX, 15 pages, 1
figur
A prospective cohort study on Allium vegetable consumption, garlic supplement use, and the risk of lung carcinoma in The Netherlands
The association between the consumption of onions and leeks (vegetables belonging to the Allium genus), garlic supplements, and the risk of lung carcinoma was investigated in a large-scale prospective cohort study on diet and cancer in the Netherlands. The Netherlands Cohort Study was started in 1986 among 120,852 men and women, ages 55-69 years, by collecting information on usual diet and important life-style characteristics. After 3.3 years of follow-up, 550 incident lung carcinoma cases were observed. Information on Allium vegetable consumption was available for 484 lung carcinoma cases and 3123 members of a randomly sampled subcohort. In stratified analysis, a lower lung carcinoma risk was observed in the highest onion intake category [rate ratio (RR) = 0.65; 95% confidence interval, 0.45-0.95] compared to the lowest consumption category. After including other, dietary and nondietary, determinants of lung carcinoma in the multivariable models and using pack years for past and current smoking, instead of using smoking status categorized as never, ex-, and current smoking, the rate ratio in the highest intake category increased to 0.80 and was no longer significantly different from unity (95% confidence interval, 0.52-1.24). Leek consumption was not associated with risk for lung carcinoma (RR = 1.08; 95% confidence interval 0.80-1.45 in the highest intake category, compared to the lowest). No statistically significant trends in the rate ratios associated with increasing consumption of these vegetables were detected for lung carcinoma or the four histological subtypes. A higher lung carcinoma risk was observed for those subjects who used exclusively garlic supplements (RR = 1.78; 95% confidence interval, 1.08-2.92), compared to those not taking dietary supplements. A lower lung carcinoma risk was seen for those using garlic supplements together with any other supplement (RR = 0.93; 95% confidence interval 0.46-1.86) compared to those using any other supplement. In conclusion, we found no evidence of a relation between the consumption of onions or leeks and the risk of lung carcinoma or any of the histological subtypes. Garlic supplement use seems not associated with a lower risk of lung carcinoma
A prospective cohort study on consumption of alcoholic beverages in relation to prostate cancer incidence (The Netherlands).
Department of Epidemiology, Maastricht University, The Netherlands. [email protected] OBJECTIVES: To examine alcohol consumption in relation to prostate cancer incidence in the Netherlands Cohort Study. METHODS: At baseline in 1986, 58,279 men aged 55-69 years completed a self-administered questionnaire on diet, consumption of alcoholic beverages and other risk factors for cancer. For data processing and analyses the case-cohort approach was used. After 6.3 years of follow-up, 680 incident primary prostate cancer cases were available for analysis. RESULTS: In multivariate analyses adjusted for age, socioeconomic status and family history of prostate cancer, no association between total alcohol consumption, alcohol intake from beer and liquor and prostate cancer risk was found. Increased associations were found for alcohol from white wine and fortified wines compared to nondrinkers, but not for red wine. The RRs (95% CI) in the intake category of > or = 15 g/day were 3.3 (1.2-9.2) and 2.3 (1.2-4.7), respectively, after additional adjustment for total alcohol intake. There was, however, no significant trend in risk. Alcohol intake was more strongly related with localized than with advanced prostate tumors. CONCLUSION: Our results do not support an important role for alcohol in prostate cancer etiology. Nevertheless, for specific types of alcoholic beverages, particularly wines, a positive association was suggested which needs examination in further studies
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