Broken Mirror Symmetry of Tracer's Trajectories in Turbulence.

Topological properties of physical systems play a crucial role in our understanding of nature, yet their experimental determination remains elusive. We show that the mean helicity, a dynamical invariant in ideal flows, quantitatively affects trajectories of fluid elements: the linking number of Lagrangian trajectories depends on the mean helicity. Thus, a global topological invariant and a topological number of fluid trajectories become related, and we provide an empirical expression linking them. The relation shows the existence of long-term memory in the trajectories: the links can be made of the trajectory up to a given time, with particles positions in the past. This property also allows experimental measurements of mean helicity.

Comparison of multimedia and printed patient education tools for patients with osteoporosis: a 6-month randomized controlled trial.

We conducted a randomized controlled trial to compare the efficacy of adding a video tool to a printed booklet on osteoporosis. Both strategies were effective in increasing knowledge and decreasing decisional conflict. There was no difference in the measured outcomes between the intervention and control groups. Patient preferences and learning styles are key factors in deciding a presentation format when educating patients with osteoporosis. INTRODUCTION: Innovative approaches to patient education about self-management in osteoporosis may improve outcomes. METHODS: We conducted a randomized controlled trial to compare the efficacy of adding a multimedia patient education tool involving video modeling to a printed educational booklet on osteoporosis. Participants were post-menopausal women with osteoporosis. We assessed osteoporosis knowledge, decisional conflict, self-efficacy, and effectiveness in disease management at baseline, immediately post-intervention, and at 3 and 6 months. Linear regression models were used to explore changes in outcomes at 6 months with respect to baseline characteristics. RESULTS: Two hundred and twenty-five women were randomized, 111 to receive the multimedia tool in addition to the booklet and 114 to receive the booklet alone. Knowledge and decisional conflict scores significantly improved in both groups at all post-intervention assessment points, but with no significant differences in score changes between the groups. Self-efficacy and disease management effectiveness showed no significant changes from baseline. In the entire cohort, younger age was associated with better effectiveness in disease management and Hispanic women had greater gains in knowledge at 6 months compared to White women. Women with limited health literacy who had received the multimedia tool in addition to the printed materials had higher decisional conflict than those who received printed materials alone. CONCLUSION: Both multimedia and printed tools increased knowledge and decreased decisional conflict to the same extent, neither of the educational materials proved to be better than the other. For women with limited health literacy, receiving the booklet alone was more effective in reducing decisional conflict after 6 months, than adding the multimedia tool.

A simplified and versatile calibration method for multi-camera optical systems in 3D particle imaging.

This article describes a stereoscopic multi-camera calibration method that does not require any optical model. It is based on a measure of the light propagation within the measurement volume only instead of modeling its entire path up to the sensors. The calibration uses simple plane by plane transformations which allow us to directly link pixel coordinates to light rays. The appeal of the proposed method relies on the combination of its simplicity of implementation (it is particularly easy to apply in any sophisticated optical imaging setup), its versatility (it can easily handle index-of-refraction gradients, as well as complex optical arrangements), and its accuracy {we show that the proposed method gives better accuracy than commonly used techniques, based on Tsai's simple pinhole camera model [R. Tsai, J. Rob. Autom. 3, 323 (1987)], while its numerical implementation remains extremely simple}. Based on ideas that have been available in the fluid mechanics community, this method is a compact turn-key algorithm that can be implemented with open-source routines.

Estimating two-point statistics from derivatives of a signal containing noise: Application to auto-correlation functions of turbulent Lagrangian tracks.

This article describes a method for calculating moments and correlation functions of signal derivatives, which were rid of experimental noise without the use of filtering operations. The method is based on the computation of the ensemble-average of different time (or spatial) increments of the signal. The hypotheses are that the noise is white and not correlated with the signal; however, the method is also shown to work with colored noise. The method is first developed, considering white noise, and benchmarked with synthetic trajectories containing noise with variable signal-to-noise ratios. It is then tested on experimental trajectories in the context of Lagrangian tracking of particles in turbulent flows, either containing a short-correlated noise or a colored noise.

Equilibrium position of a rigid sphere in a turbulent jet: A problem of elastic reconfiguration.

The position of floating spheres trapped within an immersed turbulent water jet is investigated. Using the self-similarity properties of the jet velocity profile, the equilibrium problem is formulated in a rescaled space where the sphere is static and deformable. This approach is found to be related to a problem of elastic reconfiguration where elasticity arises here from the geometry of the flow instead of an actual deformation of a body.

Stochastic dynamics of particles trapped in turbulent flows.

The long-time dynamics of large particles trapped in two nonhomogeneous turbulent shear flows is studied experimentally. Both flows present a common feature, a shear region that separates two colliding circulations, but with different spatial symmetries and temporal behaviors. Because large particles are less and less sensitive to flow fluctuations as their size increases, we observe the emergence of a slow dynamics corresponding to back-and-forth motions between two attractors, and a super-slow regime synchronized with flow reversals when they exist. Such dynamics is substantially reproduced by a one-dimensional stochastic model of an overdamped particle trapped in a two-well potential, forced by a colored noise. An extended model is also proposed that reproduces observed dynamics and trapping without potential barrier: the key ingredient is the ratio between the time scales of the noise correlation and the particle dynamics. A total agreement with experiments requires the introduction of spatially nonhomogeneous fluctuations and a suited confinement strength.

Long-term memory in experiments and numerical simulations of hydrodynamic and magnetohydrodynamic turbulence.

We analyze time series stemming from experiments and direct numerical simulations of hydrodynamic and magnetohydrodynamic turbulence. Simulations are done in periodic boxes, but with a volumetric forcing chosen to mimic the geometry of the flow in the experiments, the von Kármán swirling flow between two counterrotating impellers. Parameters in the simulations are chosen to (within computational limitations) allow comparisons between the experiments and the numerical results. Conducting fluids are considered in all cases. Two different configurations are considered: a case with a weak externally imposed magnetic field and a case with self-sustained magnetic fields. Evidence of long-term memory and 1/f noise is observed in experiments and simulations, in the case with weak magnetic field associated with the hydrodynamic behavior of the shear layer in the von Kármán flow, and in the dynamo case associated with slow magnetohydrodynamic behavior of the large-scale magnetic field.

Chaotic mixing in effective compressible flows.

We study numerically joint mixing of salt and colloids by chaotic advection and how salt inhomogeneities accelerate or delay colloid mixing by inducing a velocity drift V(dp) between colloids and fluid particles as proposed in recent experiments [J. Deseigne et al., Soft Matter 10, 4795 (2014)]. We demonstrate that because the drift velocity is no longer divergence free, small variations to the total velocity field drastically affect the evolution of colloid variance σ(2) = 〈C(2)〉-〈C〉(2). A consequence is that mixing strongly depends on the mutual coherence between colloid and salt concentration fields, the short time evolution of scalar variance being governed by a new variance production term P = -〈C(2)∇ · V(dp)〉/2 when scalar gradients are not developed yet so that dissipation is weak. Depending on initial conditions, mixing is then delayed or enhanced, and it is possible to find examples for which the two regimes (fast mixing followed by slow mixing) are observed consecutively when the variance source term reverses its sign. This is indeed the case for localized patches modeled as Gaussian concentration profiles.

Stachydrine in Leonurus cardiaca, Leonurus japonicus, Leonotis leonurus: detection and quantification by instrumental HPTLC and 1H-qNMR analyses.

Stachydrine ((2S)-1,1-dimethylpyrrolidinium-2-carboxylic acid) may be regarded as an essential active principle of the aerial parts of Leonurus japonicus Houtt. (Leonuri herba, yimucao; Chin.Ph., DAB) which are used in TCM and Kampo for the treatment of various gynaecological and cardiovascular disorders. Medically and botanically closely related Lamioideae drugs are the fruits of L. japonicus (Leonuri fructus, chongweizi; Chin.Ph.), the aerial parts of European Leonurus cardiaca L. (Leonuri cardiacae herba; Ph.Eur.) as well as the aerial parts of their South African relative Leonotis leonurus (L.) R.Br. (Leonotis leonuri herba). Regarding L. cardiaca, stachydrine might be an exceptionally interesting constituent as Dragendorff-positive substances like stachydrine were found to be enriched in an antiarrhythmic L. cardiaca refined extract, which was most recently developed via bioassay guided fractionation. The few pharmacological publications on this betaine do indeed describe cardiovascular, hypotensive, and tissue protective effects. However, its pharmacopeial analytics poses a severe difficulty, as it does not contain any chromophoric group suitable for customary HPLC-UV detection. For quality control of yimucao according to Chin.Ph. the entirety of its N-containing compounds is photometrically quantified after Reinecke's complexation. Unfortunately, this method suffers from a relatively low reproducibility. Since no reliable quantification method for stachydrine is available up to now, a highly reproducible instrumental HPTLC method was newly developed, using postchromatographic derivatization by Vágújfalvi reagent, thus changing non absorbing stachydrine into a detectable derivative at 517 nm, and an automatic HPTLC system with scanner and analysis software (winCATS). This method was shown to be precise with respect to concentration and yielded highly reproducible data over numerous inter-day repetitions. Not only did the independent evaluation of the scanned HPTLC sheets for stachydrine peak area and height result in almost identical values for all samples, but also the results of a parallel-developed direct quantitative 1H-NMR procedure using its N-CH3 singlet delta 3.03 ppm in comparison with the singlet of the two vinylic protons of the internal standard maleic acid at delta 6.18 ppm were always within the standard deviation of the HPTLC data. These measurements of 12 drug samples revealed stachydrine contents (w/w) of 0.2 to 1.0% for the L. japonicus aerial parts, 0.6 to 1.5 % for the L. cardiaca aerial parts, 6.7% for the antiarrhythmic refined extract of L. cardiaca, and 0.3% for the aerial parts of Leonotis leonurus, while both L. japonicus and L. cardiaca fruits contained, on average, 0.2 %. Furthermore, stachydrine was found for the first time as a constituent of L. japonicus and L. cardiaca fruits as well as Leonotis leonurus. Methodically, instrumental HPTLC may be a powerful tool for quality assurance for stachydrine containing plants and herbal drugs, especially for industrial routine protocols.

Clustering of finite-size particles in turbulence.

We investigate experimentally the spatial distributions of heavy and neutrally buoyant particles of finite size in a fully turbulent flow. Because their Stokes number (i.e., the ratio of the particle viscous relaxation time to a typical flow time scale) is close to unity, one may expect both classes of particles to aggregate in specific flow regions. This is not observed. Using a Voronoï analysis we show that neutrally buoyant particles sample turbulence homogeneously, whereas heavy particles do cluster. These results show that several dimensionless numbers are needed in the modeling (and understanding) of the behavior of particles entrained by turbulent motions.

Bromoanaindolone, a novel antimicrobial exometabolite from the cyanobacterium Anabaena constricta.

A new brominated indole alkaloid, designated as bromoanaindolone, was isolated from culture media of the cyanobacterium Anabaena constricta and was identified as 6-bromo-3-hydroxy-3-methyl-indol-2-one with a slight excess of the (3R) enantiomer. The molecular structure was elucidated on the basis of IR, MS and NMR data. This extracellular metabolite of A. constricta possessed antimicrobial (anticyanobacterial and antibacterial) activity in different test systems, such as suspension and porous matrix tests.

Chaotic dynamos generated by a turbulent flow of liquid sodium.

We report the observation of several dynamical regimes of the magnetic field generated by a turbulent flow of liquid sodium (VKS experiment). Stationary dynamos, transitions to relaxation cycles or to intermittent bursts, and random field reversals occur in a fairly small range of parameters. Large scale dynamics of the magnetic field result from the interactions of a few modes. The low dimensional nature of these dynamics is not smeared out by the very strong turbulent fluctuations of the flow.

Generation of a magnetic field by dynamo action in a turbulent flow of liquid sodium.

We report the observation of dynamo action in the von Kármán sodium experiment, i.e., the generation of a magnetic field by a strongly turbulent swirling flow of liquid sodium. Both mean and fluctuating parts of the field are studied. The dynamo threshold corresponds to a magnetic Reynolds number R(m) approximately 30. A mean magnetic field of the order of 40 G is observed 30% above threshold at the flow lateral boundary. The rms fluctuations are larger than the corresponding mean value for two of the components. The scaling of the mean square magnetic field is compared to a prediction previously made for high Reynolds number flows.

Transport of magnetic field by a turbulent flow of liquid sodium.

We study the effect of a turbulent flow of liquid sodium generated in the von Kármán geometry, on the localized field of a magnet placed close to the frontier of the flow. We observe that the field can be transported by the flow on distances larger than its integral length scale. In the most turbulent configurations, the mean value of the field advected at large distance vanishes. However, the rms value of the fluctuations increases linearly with the magnetic Reynolds number. The advected field is strongly intermittent.

Induction, helicity, and alpha effect in a toroidal screw flow of liquid gallium.

We investigate experimentally induction mechanisms in a screw flow of gallium in a toroidal channel. The flow is nonstationary and operated in a spin-down regime: the channel (and fluid) are initially set into solid body rotation; as the channel is stopped the fluid is set into strong helical motion by diverters located inside the channel. In this study, we put a particular emphasis on the induction generated by these helical motions, which are expected to develop over the entire range of turbulent scales. We apply an external magnetic field either perpendicular to the channel axis parallel to it. At large scales the nonlinear induction mechanisms are associated with the Parker stretch and twist effect and with the expulsion due to overall rotation. Induction mechanisms can also originate in the small scale helicity as in the alpha induction effect of mean-field magnetohydrodynamics. Our measurements yield an upper bound for the alpha coefficient, significantly lower than estimates based on dimensional analysis. We discuss the consequences of our observations for the engineering of homogeneous dynamos in the laboratory.

Cefditoren pivoxil versus cefpodoxime proxetil for community-acquired pneumonia: results of a multicenter, prospective, randomized, double-blind study.

BACKGROUND: According to recently issued treatment guidelines, appropriate empiric choices for ambulatory patients with community-acquired pneumonia (CAP) are a macrolide, doxycycline (for patients aged > or = 8 years), or an oral beta-lactam agent with good activity against pneumococci. OBJECTIVE: This study was designed to compare cefditoren pivoxil, a new beta-lactam, with cefpodoxime proxetil, a beta-lactam with an established role in the treatment of CAP. METHODS: This was a multicenter, prospective, randomized, double-blind study conducted in the United States and South Africa. Ambulatory patients with a diagnosis of CAP were randomized to 14 days of treatment with cefditoren 200 or 400 mg BID or cefpodoxime 200 mg BID. Assessments of clinical cure and pathogen eradication were conducted at 2 visits during treatment, 1 posttreatment visit (s48 hours after completion of treatment), and 1 follow-up visit (7-14 days after completion of treatment). The development of resistant pathogens was assessed at the follow-up visit but not thereafter. The relative cost of treatment was not assessed. RESULTS: The study enrolled 851 patients. Comparable clinical cure rates were observed among evaluable patients in the 3 treatment groups at both the posttreatment and followup visits: at the posttreatment visit, cure rates were 90.5% (162/179) for cefditoren 200 mg, 89.7% (148/165) for cefditoren 400 mg, and 92.2% (153/166) for cefpodoxime 200 mg; at the follow-up visit, they were a respective 88.4% (160/181), 87.2% (143/164), and 90.4% (151/167). Of the 171 strains of Streptococcus pneumoniae isolated before treatment, 22 (12.9%) had reduced susceptibility to penicillin, 5 (2.9%) of them penicillin resistant (minimum inhibitory concentration > or = 2 microg/mL). At the posttreatment visit, the overall eradication rates of pathogens isolated from microbiologically evaluable patients were 88.7% (134/151), 89.9% (134/149), and 95.7% (134/140) in the respective treatment groups (P = 0.031, cefditoren 200 mg vs cefpodoxime). Eradication rates of S pneumoniae were 93.8% (45/48), 95.7% (45/47), and 95.6% (43/ 45) in the respective treatment groups; those of Haemophilus influenzae were 90.2% (46/51), 97.7% (43/44), and 97.4% (37/38). The rates of resolution and/or improvement in clinical signs and symptoms were comparable between groups. The study drugs were well tolerated, with 1.7%, 2.5%, and 1.4% of patients in the respective groups discontinuing study drug prematurely due to a treatment-related adverse event, the majority of these associated with the digestive system. CONCLUSION: The results of this study suggest that cefditoren may have a role in the treatment of CAP in ambulatory patients.

The alcohol use disorders identification test: an aid to recognition of alcohol problems in primary care patients.

BACKGROUND: Misuse of alcohol is associated with a range of medical problems. Fortunately, a simple pencil-and-paper measure, the Alcohol Use Disorders Identification Test, can effectively and efficiently screen for early-stage alcohol abuse as well as provide the physician information that can assist in brief intervention. OBJECTIVE: The objective of this article is to briefly summarize research published on the Alcohol Use Disorders Identification Test and suggest its potential role in brief intervention in primary care settings. METHODS: Scientific literature on the Alcohol Use Disorders Identification Test though 2000 was reviewed and synthesized to address issues relevant to use of the test in primary health care settings. RESULTS: The Alcohol Use Disorders Identification Test is quite sensitive and specific and compares favorably with alternative self-report screens for alcohol problems.

The behavioral risks and life circumstances of adolescent mothers involved with older adult partners.

OBJECTIVE: To investigate behavioral risks and life circumstances of adolescent mothers with older (> or =5 years) adult (> or =20 years old) vs. similar-aged (+/-2 years) male partners at 12 months' postpartum. METHODS: Nine hundred thirty-one adolescent females were interviewed after delivery and were mailed surveys to complete at 12 months' postpartum. Analysis by chi(2) and t test was used to identify differences in behavioral risks (planned repeated pregnancy, substance use, and intimate partner violence) and life circumstances (financial status, school enrollment, and social support) for adolescent mothers with older adult vs similar-aged partners. Additional stratified analyses were conducted to evaluate the extent to which living with an adult authority figure or being with the father of her infant born 12 months previously might alter observed relationships. RESULTS: At 12 months following delivery, 184 adolescent mothers (20%) reported having an older adult partner, whereas 312 (34%) had a similar-aged partner. The remaining adolescent mothers (n = 239) were excluded from further analyses. Adolescent mothers with older adult partners were significantly less likely to be employed or enrolled in school and were more likely to report planned repeated pregnancies. These adolescent mothers also received less social support. No differences were observed in intimate partner violence or the mother's substance use. Adolescent mothers with older adult partners who did not live with an adult authority figure seemed to be at greatest risk. CONCLUSIONS: The negative educational and financial impact of coupling with an older vs. similar-aged partner seems greater for those mothers who no longer reside with an adult authority figure. These adolescent mothers are also at greater risk of planned rapid repeated pregnancy. Given their limited educational attainment and family support, a subsequent pregnancy may place these young women at considerable financial and educational disadvantage.

Backward supercontinuum emission from a filament generated by ultrashort laser pulses in air.

Backward emission of the supercontinuum from a light filament induced by high-intensity femtosecond laser pulses propagating in air has been observed to be enhanced compared with linear Rayleigh-Mie scattering. This enhancement is interpreted as a nonlinear scattering process onto longitudinal refractive-index changes induced by the laser pulse itself. The spectral dependence of the supercontinuum angular distribution is also investigated.

Pregnant adolescents: experiences and behaviors associated with physical assault by an intimate partner.

OBJECTIVE: To better understand the experiences and behaviors of battered pregnant adolescents and the characteristics of their intimate partners. METHODS: As part of a longitudinal multiracial/ethnic study of drug use among pregnant and parenting adolescents, 724 adolescents < or = 18 years of age completed face-to-face interviews on the postpartum unit between April 1994 and February 1996. Adolescent mothers reported on demographic characteristics, social support and peer contact, level of substance use before and during pregnancy, nonconforming behaviors, and both lifetime and concurrent exposure to violence. Information about the father of her baby included his level of substance use, gang and police involvement, and intimate partner violence. Chi-square and Student's t tests were used to identify victim, partner, and relationship characteristics associated with being assaulted by the father of her baby during the preceding year. RESULTS: Eighty-six (11.9%) adolescents reported being physically assaulted by the fathers of their babies. Assaulted adolescents were significantly more likely than nonassaulted adolescents to have been exposed to other forms of violence over the same 12-month period, including verbal abuse, assault by family members, being in a fight where someone was badly hurt, reporting fear of being hurt by other teens, witnessing violence perpetrated on others, and carrying a weapon for protection. A history of nonconforming behavior and frequent or recent substance use was more common among both battered adolescents and their perpetrator partners. The age and race/ethnicity of the pregnant adolescent and the length of her relationship with the father of her baby were not associated with assault status. CONCLUSIONS: Pregnant adolescents who are assaulted by intimate partners appear to live in violence-prone environments and to have partners who engage in substance use and other nonconforming behaviors. Comprehensive assessments are critical for all adolescent females at risk of assault, and direct questions about specific behaviors or situations must be used.