Multimodal and retro-mode imaging in sclerochoroidal calcification: A case report

We present a case report on sclerochoroidal calcification (SCC), a rare condition involving calcium pyrophosphate deposits in the posterior pole of the eye in a 70-year-old patient. We provide an account of the clinical presentation and its appearance in multimodal images, using color fundus photography, swept-source optical coherence tomography (SS-OCT), ocular ultrasound, and the novel retro-mode imaging (RMI) technique. Visual acuity was 20/25 in the right eye (OD) and 20/20 in the left eye (OS). Color fundus photography revealed yellowish deposits located in the upper temporal arcade of both eyes. SS-OCT demonstrated masses of scleral origin. Ocular ultrasounds confirmed the calcification of these masses. RMI detected hyper-reflective images with marked superficial elevation. Systemic laboratory results did not detect any abnormalities, leading to the diagnosis of bilateral idiopathic SCC.

Retro-mode imaging for the diagnosis of optic disc drusen: a case series

OBJECTIVE

We aimed to compare the detectability of optic disc drusen (ODD), using various non-invasive imaging techniques, including the novel retro-mode imaging (RMI), as well as to analyze the morphological characteristics of ODD on RMI.

METHODS

This study involved seven patients with bilateral ODD, totaling 14 eyes. Multimodal imaging techniques, including multicolor fundus photography (MC), near-infrared reflectance (NIR), green and blue light fundus autofluorescence (G-FAF and B-FAF, respectively), and RMI were used to examine the eyes. FAF was used as the primary method of identifying ODD, and each method's detection rate was compared by two observers. Quantitative measurements of ODD included the number of ODD visualized by the RMI technique, the perimeter (P) and area (A) of ODD were identified.

RESULTS

The average age of the patients included was 49.28 ± 23.16 years, with five of the seven being men. RMI was able to detect ODD in all cases, with a sensitivity of 100%, compared to MC (sensitivity 60.71%), NIR (sensitivity 60.71%), B-FAF (sensitivity 100%), G-FAF (sensitivity 100%). RMI was the only imaging technique capable of assessing ODD morphology and quantifying ODD.

CONCLUSIONS

RMI is a promising imaging modality for diagnosing superficial ODD, providing valuable information on the distribution, location, and size of ODD. We suggest the incorporation of RMI as a complementary tool for diagnosing and monitoring ODD in combination with other multimodal imaging methods.

A rare intraocular foreign body resulting from a workplace accident

A 54-year-old man presented to the ophthalmic emergency department of our center with eye pain and blurred vision in his right eye following a workplace accident. Examination revealed a penetrating corneal injury with the presence of an intraocular foreign body (IOFB) involving the corneoscleral limbus, perforating the cornea, iris, anterior lens capsule, and lens. Immediate surgical intervention was carried out with the extraction of the IOFB, identified as an 8mm mussel shell fragment, and the removal of the resulting traumatic cataract. Both preoperative and postoperative examinations showed an attached retina with no signs of retinal tears or vitreous hemorrhage. Appropriate management in this case, along with the timely identification of the agent, led to favorable outcomes despite the size of the intraocular foreign body.

Chronotype delay and sleep disturbances shaped by the Antarctic polar night

Chronotype is a reliable biomarker for studying the influence of external zeitgebers on circadian entrainment. Assessment of chronotype variation in participants exposed to extreme photoperiods may be useful to investigate how changes in light-dark cycle modulate the circadian system. This study aimed to examine chronotype and sleep changes during a winter campaign at the Argentine Antarctic station Belgrano II. A sample of 82 men who overwintered in Antarctica completed the Munich Chronotype Questionnaire during March (daylight length: 18.6 h), May (daylight length: 2.8 h), July (daylight length: 0 h), September (daylight length: 14.5 h), November (daylight length: 24 h). The main results showed a decrease in sleep duration and a delay in chronotype and social jetlag during the polar night, highlighting the influence of social cues and the impact of the lack of natural light on circadian rhythms.

Turbulence suppression by cardiac-cycle-inspired driving of pipe flow

Flows through pipes and channels are, in practice, almost always turbulent, and the multiscale eddying motion is responsible for a major part of the encountered friction losses and pumping costs1. Conversely, for pulsatile flows, in particular for aortic blood flow, turbulence levels remain low despite relatively large peak velocities. For aortic blood flow, high turbulence levels are intolerable as they would damage the shear-sensitive endothelial cell layer2-5. Here we show that turbulence in ordinary pipe flow is diminished if the flow is driven in a pulsatile mode that incorporates all the key features of the cardiac waveform. At Reynolds numbers comparable to those of aortic blood flow, turbulence is largely inhibited, whereas at much higher speeds, the turbulent drag is reduced by more than 25%. This specific operation mode is more efficient when compared with steady driving, which is the present situation for virtually all fluid transport processes ranging from heating circuits to water, gas and oil pipelines.

Stably stratified Taylor-Couette flows

Stably stratified Taylor-Couette flow has attracted much attention due to its relevance as a canonical example of the interplay among rotation, stable stratification, shear and container boundaries, as well as its potential applications in geophysics and astrophysics. In this article, we review the current knowledge on this topic, highlight unanswered questions and propose directions for future research. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal Philosophical transactions paper (Part 2)'.

Quantitative 1H Nuclear Magnetic Resonance Assay for the Rapid Detection of Pyrazinamide Resistance in Mycobacterium tuberculosis from Sputum Samples

Tuberculosis (TB), caused by Mycobacterium tuberculosis, is one of the 10 leading killer diseases in the world. At least one-quarter of the population has been infected, and there are 1.3 million deaths annually. The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains challenges TB treatments. One of the drugs widely used in first- and second-line regimens is pyrazinamide (PZA). Statistically, 50% of MDR and 90% of XDR clinical strains are resistant to PZA, and recent studies have shown that its use in patients with PZA-resistant strains is associated with higher mortality rates. Therefore, the is an urgent need for the development of an accurate and efficient PZA susceptibility assay. PZA crosses the M. tuberculosis membrane and is hydrolyzed to its active form, pyrazinoic acid (POA), by a nicotinamidase encoded by the pncA gene. Up to 99% of clinical PZA-resistant strains have mutations in this gene, suggesting that this is the most likely mechanism of resistance. However, not all pncA mutations confer PZA resistance, only the ones that lead to limited POA production. Therefore, susceptibility to PZA may be addressed simply by its ability to form, or not, POA. Here, we present a nuclear magnetic resonance method to accurately quantify POA directly in the supernatant of sputum cultures collected from TB patients. The ability of the clinical sputum culture to hydrolyze PZA was determined, and the results were correlated with the results of other biochemical and molecular PZA drug susceptibility assays. The excellent sensitivity and specificity values attained suggest that this method could become the new gold standard for the determination of PZA susceptibility.

Combined H-N Cross-Polarization and Carbonyl Detection NMR Spectroscopy Allow to Record High-Resolution, High-Sensitivity Spectra of Alpha-Synuclein in Bacterial Cells

Studies of intrinsically disordered proteins (IDPs) under physiological conditions by conventional NMR methods based on proton detection are severely limited by fast proton amide solvent exchange. Carbon detection has been proposed as a solution to the exchange problem but is hampered by low sensitivity. Here, we present a protocol combining proton-nitrogen cross-polarization and carbonyl detection to record high-resolution and high-sensitivity NMR spectra of IDPs under physiological conditions. The protocol describes a step-by-step method to register high-quality N-CO correlation spectrum of alpha-synuclein in E.coli bacterial cells at 37 °C.

Urine 1H-NMR Metabolomics to Discriminate Neurocysticercosis Patients from Healthy Controls: An Exploratory Study

The diagnosis of neurocysticercosis (NCC) is principally based on neuroimaging (magnetic resonance imaging or computed tomography), instrumentation that is scarcely available in the rural regions where Taenia solium transmission, primarily occurs due to poor sanitation conditions. Immunological assays for antigen or antibody detection complement the neuroimaging approach. However, no field-applicable assays to diagnose viable NCC or to guide the referral of cases for neuroimaging or for appropriate management are available. We performed an exploratory study on urine and serum samples using 1H-nuclear magnetic resonance (NMR)-based metabolomics to discriminate NCC patients (n = 14) from healthy control subjects (n = 22). Metabolic profiles demonstrated a discrimination between the urines of NCC patients and noninfected control subjects with a moderate predictive accuracy (R2 = 0.999, Q2 = 0.434). NMR metabolomics analysis has been proven useful in depicting biomarkers linked to other infectious diseases, various types of cancer, and other disorders. Our results, albeit preliminary, open a door to the development of better methods for detecting NCC through the identification of biomarkers participating in disturbed metabolic pathways.

Measuring the 3J HNHa coupling by a simple 2D-intra-HNCA IP/AP-E.COSY with simultaneous encoding of 15N chemical shift and 1J HaCa evolution

The ³J coupling values are commonly used in biomolecular NMR to extract structural information. Here we present a novel intra HNCA IP/AP E.COSY pulse sequence that allows to measure ³J H^NH^a coupling constants by a simple and rapid two-dimensional ¹H-¹⁵N correlation experiment where the ¹⁵N frequency is encoded at the same time as the ¹J H^aC^a coupling evolution. The advantage with respect to the conventional 3D HNCA E.COSY pulse sequence is the dimensionality reduction to a simple 2D experiment, which decreases acquisition time and facilitates data analysis. The performance of this new experiment is demonstrated with an ubiquitin sample at 500 MHz.

Transcervical Foley Balloon Plus Vaginal Misoprostol versus Vaginal Misoprostol Alone for Cervical Ripening in Nulliparous Obese Women: A Multicenter, Randomized, Comparative-Effectiveness Trial

OBJECTIVE

Nulliparous obese women are at increased risk of labor induction and cesarean delivery (CD). We sought to determine whether the combination of a transvaginal Foley balloon plus misoprostol prostaglandin E1 (PGE1) is superior to misoprostol alone in reducing the risk for CD.

STUDY DESIGN

We undertook a multicenter, open-label, comparative-effectiveness randomized clinical trial of nulliparous obese women with unfavorable cervix (Bishop's score ≤ 6) undergoing labor induction from January 2016 to June 2018 at three tertiary centers. Those at <32 weeks' gestation, premature rupture of membranes, stillbirth, and major fetal anomalies were excluded. Women were randomized 1:1 to either a combination of Foley balloon and misoprostol or misoprostol alone. Once Bishop's score was >6, further management was deferred to treating physicians. Primary outcome was the rate of CD. Secondary maternal outcomes included duration of induction-to-delivery interval, occurrence of tachysystole, clinical chorioamnionitis, need for operative vaginal delivery, as well as a composite of maternal morbidity (postpartum endometritis, surgical-site infection, venous thromboembolism, need for transfusion, intensive care unit admission, and maternal death). Secondary neonatal outcomes included need for neonatal intensive care unit admission, transient tachypnea of the newborn, respiratory distress syndrome, meconium aspiration syndrome, culture-proven sepsis, neonatal seizures, and a composite of neonatal morbidity (Apgar's score ≤7 at 5 minutes, umbilical artery cord pH ≤7.10, birth injury, perinatal death). With the rate of CD rate being 53% at Children's Memorial Herman Hospital among nulliparous obese women who underwent induction of labor at ≥32 weeks and met our inclusion criteria; 250 women (125 women per group) were required to answer the study question. All analyses were by intention to treat.

RESULTS

Of the 236 women randomized, 113 (48%) were allocated to group 1 (combined Foley and PGE1) and 123 (52%) to group 2 (PGE1 alone). The rate of CD was similar between the groups (45 vs. 43%, p = 0.84, relative risk [RR]: 1.03, 95% CI: 0.75-1.42). There was no difference in the occurrence of tachysystole that resulted in fetal heart rate abnormalities between the groups (8.8 vs. 16.2%, p = 0.09, RR: 0.54, 95% CI: 0.27-1.11). The total duration of the induction-to-delivery interval was also similar between the groups (24.8 ± 13.8 vs. 24.5 ± 14.0 hours, p = 0.87) regardless of the mode of delivery. No differences were seen in the indications for CD and secondary maternal or neonatal outcomes.

CONCLUSION

In this trial of nulliparous obese women undergoing labor induction, cervical ripening with combined Foley balloon and PGE1 resulted in similar CD rates than ripening with vaginal PGE1 alone.

KEY POINTS

· Nulliparous obese women are at increased risk for cesarean delivery.. · Combined intravaginal misoprostol-Foley balloon versus misoprostol alone resulted in similar rates of cesarean delivery.. · Further research is warranted to determine the optimal cervical ripening strategy in this population..

Pure Shift Nuclear Magnetic Resonance: a New Tool for Plant Metabolomics

Nuclear Magnetic Resonance (NMR) is one of the most powerful tools used in metabolomics. It stands as a highly accurate and reproducible method that not only provides quantitative data but also permits structural identification of the metabolites present in complex mixtures. Metabolic profiling by ¹H NMR has proven useful in the study of various types of plant scenarios, which include the evaluation of crop conditions, harvest and post- harvest treatments, metabolic phenotyping, metabolic pathways, gene regulation, identification of biomarkers, chemotaxonomy, quality control, denomination of origin, among others. However, signal overlapping of the large number of resonances with expanded J-coupling multiplicities complicates the spectra analysis and its interpretation, and represents a limitation for classical ¹H NMR profiling. In the last decade, novel NMR broadband homonuclear decoupling techniques through which multiplet signals collapse into single resonance lines - commonly called Pure Shift methods - have been developed to overcome the spectra resolution problem inherent to ¹H NMR classical spectra. Here a step-by-step protocol of the plant extract preparation and the procedure to record optimal Pure Shift PSYCHE and SAPPHIRE-PSYCHE spectra in three different plant matrices - Vanilla plant leaves, potato tubers (S. tuberosum), and Cape gooseberries (P. peruviana) - is presented. The effect of the gain in resolution in metabolic identification, correlation analysis and multivariate analyses, as compared against classical spectra, is discussed.

NMR-based leaf metabolic profiling of V. planifolia and three endemic Vanilla species from the Peruvian Amazon

The fruit of Vanilla planifolia is broadly preferred by the agroindustry and gourmet markets due to its refined flavor and aroma. Peruvian Vanilla has been proposed as a possible source for genetic improvement of existing Vanilla cultivars, but, little has been done to facilitate comprehensive studies of these and other Vanilla. Here, a nuclear magnetic resonance (NMR) metabolomic platform was developed to profile for the first time the leaves - organ known to accumulate vanillin putative precursors - of V. planifolia and those of Peruvian V. pompona, V. palmarum, and V. ribeiroi, with the aim to determine metabolic differences among them. Analysis of the NMR spectra allowed the identification of thirty-six metabolites, twenty-five of which were quantified. One-way ANOVA and post-hoc Tukey test revealed that these metabolites changed significantly among species, whilst multivariate-analyses allowed the identification of malic and homocitric acids, together with two vanillin precursors, as relevant metabolic markers for species differentiation.

Study of the Acetylation Pattern of Chitosan by Pure Shift NMR

Chitosan is a biodegradable, antibacterial, and nontoxic biopolymer used in a wide range of applications including biotechnology, pharmacy, and medicine. The physicochemical and biological properties of chitosan have been associated with parameters such as the degree of polymerization (DP) and the fraction of acetylation (F_A). New methods are being developed to yield chitosans of specific acetylation patterns, and, recently, a correlation between biological activity and the distribution of the acetylated units (P_A: pattern of acetylation) has been demonstrated. Although there are numerous well-established methods for the determination of DP and F_A values, this is not the case for P_A. The methods available are either not straightforward or not sensitive enough, limiting their use for routine analysis. In this study, we demonstrate that by applying HOmodecoupled Band-Selective (HOBS) decoupling NMR on signals assigned by multidimensional Pure Shift NMR methods, P_A can be easily and accurately determined on various chitosan samples. This novel methodology-easily implemented for routine analysis-could become a standard for chitosan P_A assessment. In addition, by applying Spectral Aliased Pure Shift HSQC, the analysis was enhanced with the determination of triads.

Morphological and metabolic profiling of a tropical-adapted potato association panel subjected to water recovery treatment reveals new insights into plant vigor

Potato (Solanum tuberosum L.) is one of the world's most important crops, but it is facing major challenges due to climatic changes. To investigate the effects of intermittent drought on the natural variability of plant morphology and tuber metabolism in a novel potato association panel comprising 258 varieties we performed an augmented block design field study under normal irrigation and under water-deficit and recovery conditions in Ica, Peru. All potato genotypes were profiled for 45 morphological traits and 42 central metabolites via nuclear magnetic resonance. Statistical tests and norm of reaction analysis revealed that the observed variations were trait specific, that is, genotypic versus environmental. Principal component analysis showed a separation of samples as a result of conditional changes. To explore the relational ties between morphological traits and metabolites, correlation-based network analysis was employed, constructing one network for normal irrigation and one network for water-recovery samples. Community detection and difference network analysis highlighted the differences between the two networks, revealing a significant correlational link between fumarate and plant vigor. A genome-wide association study was performed for each metabolic trait. Eleven single nucleotide polymorphism (SNP) markers were associated with fumarate. Gene Ontology analysis of quantitative trait loci regions associated with fumarate revealed an enrichment of genes regulating metabolic processes. Three of the 11 SNPs were located within genes, coding for a protein of unknown function, a RING domain protein and a zinc finger protein ZAT2. Our findings have important implications for future potato breeding regimes, especially in countries suffering from climate change.

Mycobacterium tuberculosis ribosomal protein S1 (RpsA) and variants with truncated C-terminal end show absence of interaction with pyrazinoic acid

Pyrazinamide (PZA) is an antibiotic used in first- and second-line tuberculosis treatment regimens. Approximately 50% of multidrug-resistant tuberculosis and over 90% of extensively drug-resistant tuberculosis strains are also PZA resistant. Despite the key role played by PZA, its mechanisms of action are not yet fully understood. It has been postulated that pyrazinoic acid (POA), the hydrolyzed product of PZA, could inhibit trans-translation by binding to Ribosomal protein S1 (RpsA) and competing with tmRNA, the natural cofactor of RpsA. Subsequent data, however, indicate that these early findings resulted from experimental artifact. Hence, in this study we assess the capacity of POA to compete with tmRNA for RpsA. We evaluated RpsA wild type (WT), RpsA ∆A438, and RpsA ∆A438 variants with truncations towards the carboxy terminal end. Interactions were measured using Nuclear Magnetic Resonance spectroscopy (NMR), Isothermal Titration Calorimetry (ITC), Microscale Thermophoresis (MST), and Electrophoretic Mobility Shift Assay (EMSA). We found no measurable binding between POA and RpsA (WT or variants). This suggests that RpsA may not be involved in the mechanism of action of PZA in Mycobacterium tuberculosis, as previously thought. Interactions observed between tmRNA and RpsA WT, RpsA ∆A438, and each of the truncated variants of RpsA ∆A438, are reported.

Backbone chemical shift assignment of macrophage infectivity potentiator virulence factor of Trypanosoma cruzi

Chagas disease is a trypanosomiasis disease inflicted by Trypanosoma cruzi parasite. In Latin America, at least 10 million people are infected and annually, 10,000 casualties are deplored. Macrophage infectivity potentiator protein is one of the major virulence factors secreted by T. cruzi (TcMIP) in order to infect its host but little is known about its mechanism of action. Studies confer TcMIP an important role in the extracellular matrix transmigration and basal lamina penetration. Here, we report the backbone ¹H, ¹³C, and ¹⁵N resonance assignment of TcMIP and the comparison of the secondary structure obtained against reported X-ray crystallography data.

Predicting Steady Shear Rheology of Condensed-Phase Monomolecular Films at the Air-Water Interface

Predicting the non-Newtonian shear response of soft interfaces in biophysical systems and engineered products has been compromised by the use of linear (Newtonian) constitutive equations. We present a generalized constitutive equation, with tractable material properties, governing the response of Newtonian and non-Newtonian interfaces subjected to a wide range of steady shear. With experiments spanning six decades of shear rate, we capture and unify divergent reports of shear-thinning behavior of monomolecular films of the lipid dipalmitoylphosphatidylcholine, the primary constituent of mammalian cell walls and lung surfactant, at near-physiological packing densities.

NMR-based metabolic study of fruits of Physalis peruviana L. grown in eight different Peruvian ecosystems

The berry of Physalis peruviana L. (Solanaceae) represents an important socio-economical commodity for Latin America. The absence of a clear phenotype renders it difficult to trace its place of origin. In this study, Cape gooseberries from eight different regions within the Peruvian Andes were profiled for their metabolism implementing a NMR platform. Twenty-four compounds could be unequivocally identified and sixteen quantified. One-way ANOVA and post-hoc Tukey test revealed that all of the quantified metabolites changed significantly among regions: Bambamarca I showed the most accumulated significant differences. The coefficient of variation demonstrated high phenotypic plasticity for amino acids, while sugars displayed low phenotypic plasticity. Correlation analysis highlighted the closely coordinated behavior of the amino acid profile. Finally, PLS-DA revealed a clear separation among the regions based on their metabolic profiles, accentuating the discriminatory capacity of NMR in establishing significant phytochemical differences between producing regions of the fruit of P. peruviana L.

Surface shear viscosity as a macroscopic probe of amyloid fibril formation at a fluid interface

Amyloidogenesis of proteins is of wide interest because amyloid structures are associated with many diseases, including Alzheimer's and type II diabetes. Dozens of different proteins of various sizes are known to form amyloid fibrils. While there are numerous studies on the fibrillization of insulin induced by various perturbations, shearing at fluid interfaces has not received as much attention. Here, we present a study of human insulin fibrillization at room temperature using a deep-channel surface viscometer. The hydrodynamics of the bulk flow equilibrates in just over a minute, but the proteins at the air-water interface exhibit a very slow development during which the surface (excess) shear viscosity deduced from a Newtonian surface model increases slightly over a period of a day and a half. Then, there is a very rapid increase in the surface shear viscosity to effectively unbounded levels as the interface becomes immobilized. Atomic force microscopy shows that fibrils appear at the interface after it becomes immobilized. Fibrillization in the bulk does not occur until much later. This has been verified by concurrent atomic force microscopy and circular dichroism spectroscopy of samples from the bulk. The immobilized interface has zero in-plane shear rate, however due to the bulk flow, there is an increase in the strength of the normal component of the shear rate at the interface, implicating this component of shear in the fibrillization process ultimately resulting in a thick weave of fibrils on the interface. Real-time detection of fibrillization via interfacial rheology may find utility in other studies of proteins at sheared interfaces.

Shear-induced amyloid fibrillization: the role of inertia

Agitation of protein is known to induce deleterious effects on protein stability and structure, with extreme agitation sometimes resulting in complete aggregation into amyloid fibrils. Many mechanisms have been proposed to explain how protein becomes unstable when subjected to flow, including alignment of protein species, shear-induced unfolding, simple mixing, or fragmentation of existing fibrils to create new seeds. Here a shearing flow was imposed on a solution of monomeric human insulin via a rotating Couette device with a small hydrophobic fluid interface. The results indicate that even very low levels of shear are capable of accelerating amyloid fibril formation. Simulations of the flow suggest that the shear enhances fibrillization kinetics when flow inertia is non-negligible and the resulting meridional circulation allows for advection of bulk protein to the hydrophobic interface.

Flow-induced 2D protein crystallization: characterization of the coupled interfacial and bulk flows

Two-dimensional crystallization of the protein streptavidin, crystallizing below a biotinylated lipid film spread on a quiescent air-water interface is a well studied phenomenon. More recently, 2D crystallization induced by a shearing interfacial flow has been observed at film surface pressures significantly lower than those required in a quiescent system. Here, we quantify the interfacial and bulk flow associated with 2D protein crystallization through numerical modeling of the flow along with a Newtonian surface model. Experiments were conducted over a wide range of conditions resulting in a state diagram delineating the flow strength required to induce crystals for various surface pressures. Through measurements of the velocity profile at the air-water interface, we found that even in the cases where crystals are formed, the macroscopic flow at the interface is well described by the Newtonian model. However, the results show that even in the absence of any protein in the system, the viscous response of the biotinylated lipid film is complicated and strongly dependent on the strength of the flow. This observation suggests that the insoluble lipid film plays a key role in flow-induced 2D protein crystallization.

Early stages of bone fracture healing: formation of a fibrin-collagen scaffold in the fracture hematoma

This work is concerned with the sequence of events taking place during the first stages of bone fracture healing, from bone breakup until the formation of early fibrous callus (EFC). The latter provides a scaffold over which subsequent remodeling processes will eventually result in successful bone repair. Specifically, some mathematical models are proposed to estimate the time required for (1) the formation immediately after fracture of a fibrin clot, described in terms of a phase transition in a polymerization process, and (2) the onset of EFC which is produced when fibroblasts arising from differentiation of chemotactically recruited mesenchymal stem cells remodel a previous fibrin clot by releasing a collagen matrix over it. An attempt has been made to keep models as simple as possible, so that a explicit dependence of the estimates obtained on relevant biochemical parameters involved is obtained.

Suppression of cooling by strong magnetic fields in white dwarf stars

Isolated cool white dwarf stars more often have strong magnetic fields than young, hotter white dwarfs, which has been a puzzle because magnetic fields are expected to decay with time but a cool surface suggests that the star is old. In addition, some white dwarfs with strong fields vary in brightness as they rotate, which has been variously attributed to surface brightness inhomogeneities similar to sunspots, chemical inhomogeneities and other magneto-optical effects. Here we describe optical observations of the brightness and magnetic field of the cool white dwarf WD 1953-011 taken over about eight years, and the results of an analysis of its surface temperature and magnetic field distribution. We find that the magnetic field suppresses atmospheric convection, leading to dark spots in the most magnetized areas. We also find that strong fields are sufficient to suppress convection over the entire surface in cool magnetic white dwarfs, which inhibits their cooling evolution relative to weakly magnetic and non-magnetic white dwarfs, making them appear younger than they truly are. This explains the long-standing mystery of why magnetic fields are more common amongst cool white dwarfs, and implies that the currently accepted ages of strongly magnetic white dwarfs are systematically too young.

Confined rotating convection with large Prandtl number: centrifugal effects on wall modes

Thermal convection in a rotating cylinder with a radius-to-height aspect ratio of Γ=4 for fluids with large Prandtl number is studied numerically. Centrifugal buoyancy effects are investigated in a regime where the Coriolis force is relatively large and the onset of thermal convection is in the so-called wall modes regime, where pairs of hot and cold thermal plumes ascend and descend in the cylinder sidewall boundary layer, forming an essentially one-dimensional pattern characterized by the number of hot and cold plume pairs. In our numerical study, we use the physical parameters corresponding to aqueous mixtures of glycerine with mass concentration in the range of 60%-90% glycerine and a Rayleigh number range that extends from the threshold for wall modes up to values where the bulk fluid region is also convecting. The study shows that for the range of Rayleigh numbers considered, the local variations in viscosity due to temperature variation in the flow are negligible. However, the mean viscosity, which varies faster than exponentially with variations in the percentage of glycerine, leads to a faster than exponential increase in the Froude number for a fixed Coriolis force, and hence an enhancement of the centrifugal buoyancy effects with significant dynamical consequences, which are detailed.

Rapidly rotating cylinder flow with an oscillating sidewall

We present numerical simulations of a flow in a rapidly rotating cylinder subjected to a time-periodic forcing via axial oscillations of the sidewall. When the axial oscillation frequency is less than twice the rotation frequency, inertial waves in the form of shear layers are present. For very fast rotations, these waves approach the form of the characteristics predicted from the linearized inviscid problem first studied by Lord Kelvin. The driving mechanism for the inertial waves is the oscillating Stokes layer on the sidewall and the corner discontinuities where the sidewall meets the top and bottom end walls. A detailed numerical and theoretical analysis of the internal shear layers is presented. The system is physically realizable, and attractive because of the robustness of the Stokes layer that drives the inertial waves but beyond that does not interfere with them. We show that the system loses stability to complicated three-dimensional flow when the sidewall oscillation displacement amplitude is very large (of the order of the cylinder radius), but this is far removed from the displacement amplitudes of interest, and there is a large range of governing parameters which are physically realizable in experiments in which the inertial waves are robust. This is in contrast to many other physical realizations of inertial waves where the driving mechanisms tend to lead to instabilities and complicate the study of the waves. We have computed the response diagram of the system for a large range of forcing frequencies and compared the results with inviscid eigenmodes and ray tracing techniques.

Effect of elongational flow on ferrofuids under a magnetic field

To set up a mathematical model for the flow of complex magnetic fluids, noninteracting magnetic particles with a small volume or an even point size are typically assumed. Real ferrofluids, however, consist of a suspension of particles with a finite size in an almost ellipsoid shape as well as with particle-particle interactions that tend to form chains of various lengths. To come close to the realistic situation for ferrofluids, we investigate the effect of elongational flow incorporated by the symmetric part of the velocity gradient field tensor, which could be scaled by a so-called transport coefficient λ(2). Based on the hybrid finite-difference and Galerkin scheme, we study the flow of a ferrofluid in the gap between two concentric rotating cylinders subjected to either a transverse or an axial magnetic field with the transport coefficient. Under the influence of a transverse magnetic field with λ(2)=0, we show that basic state and centrifugal unstable flows are modified and are inherently three-dimensional helical flows that are either left-winding or right-winding in the sense of the azimuthal mode-2, which is in contrast to the generic cases. That is, classical modulated rotating waves rotate, but these flows do not. We find that under elongational flow (λ(2)≠0), the flow structure from basic state and centrifugal instability flows is modified and their azimuthal vorticity is linearly changed. In addition, we also show that the bifurcation threshold of the supercritical centrifugal unstable flows under a magnetic field depends linearly on the transport coefficient, but it does not affect the general stabilization effect of any magnetic field.

Bifurcations with imperfect SO(2) symmetry and pinning of rotating waves

Rotating waves are periodic solutions in SO(2) equivariant dynamical systems. Their precession frequency changes with parameters and it may change sign, passing through zero. When this happens, the dynamical system is very sensitive to imperfections that break the SO(2) symmetry and the waves may become trapped by the imperfections, resulting in steady solutions that exist in a finite region in parameter space. This is the so-called pinning phenomenon. In this study, we analyse the breaking of the SO(2) symmetry in a dynamical system close to a Hopf bifurcation whose frequency changes sign along a curve in parameter space. The problem is very complex, as it involves the complete unfolding of high codimension. A detailed analysis of different types of imperfections indicates that a pinning region surrounded by infinite-period bifurcation curves appears in all cases. Complex bifurcational processes, strongly dependent on the specifics of the symmetry breaking, appear very close to the intersection of the Hopf bifurcation and the pinning region. Scaling laws of the pinning region width and partial breaking of SO(2) to Z m are also considered. Previous as well as new experimental and numerical studies of pinned rotating waves are reviewed in the light of the new theoretical results.

Symmetry-breaking Hopf bifurcations to 1-, 2-, and 3-tori in small-aspect-ratio counterrotating Taylor-Couette flow

The nonlinear dynamics of Taylor-Couette flow in a small-aspect-ratio wide-gap annulus in the counterrotating regime is investigated by solving the full three-dimensional Navier-Stokes equations. The system is invariant under arbitrary rotations about the axis, reflection about the annulus midplane, and time translations. A systematic investigation is presented both in terms of the flow physics elucidated from the numerical simulations and from a dynamical system perspective provided by equivariant normal form theory. The dynamics are primarily associated with the behavior of the jet of angular momentum that emerges from the inner cylinder boundary layer at about the midplane. The sequence of bifurcations as the differential rotation is increased consists of an axisymmetric Hopf bifurcation breaking the reflection symmetry of the basic state leading to an axisymmetric limit cycle with a half-period-flip spatiotemporal symmetry. This undergoes a Hopf bifurcation breaking axisymmetry, leading to quasiperiodic solutions evolving on a 2-torus that is setwise symmetric. These undergo a further Hopf bifurcation, introducing a third incommensurate frequency leading to a 3-torus that is also setwise symmetric. On the 3-torus, as the differential rotation is further increased, a saddle-node-invariant-circle bifurcation takes place, destroying the 3-torus and leaving a pair of symmetrically related 2-tori states on which all symmetries of the system have been broken.

Addendum to "Two-fluid confined flow in a cylinder driven by a rotating endwall"

In a recent paper [Phys. Rev. E 85, 016308 (2012)], we reported on numerical simulations of swirling two-phase flows in which for cases where the viscosity of the upper fluid is sufficiently smaller than that of the lower fluid, a small region of reversed flow is present on the interface. In this Brief Report, we show that the reported reversed flow is grid converged and comment further on its physical origin.

A comparison of vital registration and reproductive-age mortality survey in Bukidnon, Philippines, 2008

OBJECTIVE

To determine the accuracy of reported maternal deaths for 2008 in a province in the Philippines.

METHODS

A reproductive-age mortality survey (RAMOS) was conducted to identify deaths of women aged 15-49 years from Bukidnon, Philippines, in 2008. Sources included various health and community reporting units. Verbal autopsies were carried out to ascertain maternal deaths.

RESULTS

The survey found 58 pregnancy-related deaths in 2008, of which 52 were maternal deaths. Of the 52, 14 were found in local civil registries but 4 were not classified as maternal deaths. No single reporting unit identified all deaths. Local civil registries provided an estimated maternal mortality ratio (MMR) of 49 per 100000 live births. The present RAMOS estimated an MMR of 209 (95% confidence interval, 191-226) per 100000 live births.

CONCLUSION

Official reports led people using the data to believe that the MMR in the province was on track for Millennium Development Goal 5 (to reduce MMR by three-quarters by 2015). The present survey showed that local civil registries missed three-quarters of all maternal deaths. All countries engaged in addressing maternal mortality reduction should consider similar approaches to improve data quality.

Influence of an inhomogeneous internal magnetic field on the flow dynamics of a ferrofluid between differentially rotating cylinders

The influence of a magnetic field on the dynamics of the flow of a ferrofluid in the gap between two concentric, independently rotating cylinders is investigated numerically. The Navier-Stokes equations are solved using a hybrid finite difference and Galerkin method. We show that the frequently used assumption that the internal magnetic field within a ferrofluid is equal to the external applied field is only a leading-order approximation. By accounting for the ferrofluid's magnetic susceptibility, we show that a uniform externally imposed magnetic field is modified by the presence of the ferrofluid within the annulus. The modification to the magnetic field has an r(-2) radial dependence and a magnitude that scales with the susceptibility. For ferrofluids typically used in laboratory experiments of the type simulated in this paper, the modification to the imposed magnetic field can be substantial. This has significant consequences on the structure and stability of the basic states, as well as on the bifurcating solutions.

Two-fluid confined flow in a cylinder driven by a rotating end wall

The flow of two immiscible fluids completely filling an enclosed cylinder and driven by the rotation of the bottom end wall is studied numerically. The simulations are in parameter regimes where there is significant advection of angular momentum, i.e., the disk rotation rate is fast compared to the viscous diffusion time. We consider two classes of scenarios. The first consists of cases that are straightforward to reproduce in physical experiments where only the rotation rate and the viscosity ratio of the fluids are varied. Then we isolate different forces acting on the system such as inertia, surface tension, and gravity by studying variations in individual governing parameters. The viscosity ratio determines how quickly the upper fluid equilibriates dynamically to the flow in the lower fluid and plays a major role in determining how vortex lines are bent in the neighborhood of the interface between the two fluids. This in turn determines the structure of the interfacial layer between the two swirling fluids, which is responsible for the flow in the upper fluid. The simulations show that even when there is significant interfacial deformation, both the dynamics and the equilibrium flow are dominated by vortex bending rather than vortex stretching. The simulations show that for the range of immiscible fluids considered, surface tension effects are significant. Increased surface tension reduces the degree to which the interface is deformed and the limit of zero surface tension is not an appropriate approximation.

Slow passage through resonance

The slow passage problem through a resonance is considered. As a model problem, we consider a damped harmonically forced oscillator whose forcing frequency is slowly ramped linearly in time. The setup is similar to the familiar slow passage through a Hopf bifurcation problem, where for slow variations of the control parameter, oscillations are delayed until the parameter has exceeded the critical value of the static-parameter problem by an amount that is the difference between the Hopf value and the initial value of the parameter. In sharp contrast, in the resonance problem there is an early onset of resonance, setting in when the ramped forcing frequency is midway between its initial value and the natural frequency for resonance in the unforced problem; we term this value the jump frequency. Numerically, we find that the jump frequency is independent of the system's damping coefficient, and so we also consider the undamped problem, which is analytically tractable. The analysis of the undamped problem confirms the numerical results found in the damped problem that the maximal amplitude obtained at the jump frequency scales as A~ε(-1/2), ε being the ramp rate, and that the jump frequency is midway between the initial frequency at the start of the ramp and the natural frequency of the unforced problem.

[Ectopic thyroid: a report of a case and review of the literature]

Ectopic thyroid is the presence of thyroid tissue outside its normal cervical seat. It results from abnormal embryological development. We report the case of an ectopic lingual thyroid found during maneuvers of intubation in a patient of 56 years old. The examination found a rhonchopathy with sleep apnea syndrome and sleep in a sitting position. Endoscopy showed a posterior lingual tumour. The cervical echography showed an absent thyroid in the normal place. Scintigraphy, computed tomography and magnetic resonance imaging confirmed the diagnosis of ectopic lingual thyroid position. The treatment consisted of surgical excision by cervical route after a safety tracheotomy.

Optimal harmonic response in a confined Bödewadt boundary layer flow

The Bödewadt boundary layer flow on the stationary bottom end wall of a finite rotating cylinder is very sensitive to perturbations and noise. Axisymmetric radial waves propagating inward have been observed experimentally and numerically before the appearance of spiral three-dimensional instabilities. In this study, the sensitivity and response of the finite Bödewadt flow to a harmonic modulation of the rotation rate are analyzed. A comprehensive exploration of response to variations in the amplitude and frequency of the forcing has been carried out. There are sharply delineated linear- and nonlinear-response regimes, with a sharp transition between them at moderate amplitudes. The periodic forcing leads to a steady-streaming flow, even in the linear-response regime, and to a period-doubling bifurcation in the nonlinear regime. Frequency response curves at different forcing amplitudes over a wide range of frequencies have been computed and used to identify the frequency band that excites the axisymmetric radial waves and the forcing frequency that elicits the strongest response. Finally, we have shown that the axisymmetric waves always decay to the steady basic state when the harmonic modulation is suppressed, and conclude that the experimentally observed persistent circular waves are not self-sustained.

Protein crystallization at the air/water interface induced by shearing bulk flow

We have observed 2D protein crystallization under conditions where in the absence of flow, crystallization fails to occur. Even under conditions where crystallization does occur in quiescent systems, we have found that flow can accelerate the crystallization process. By interrogating the flow responsible for this enhanced crystallization, we have correlated the enhancement with large shear in the plane of the interface. Some possible mechanisms for why interfacial shear can enhance the crystallization process are proposed.

Effects of shearing flow with inertia on monolayer mesoscale structure

In an experimental flow system capable of imparting a well-controlled shear-rate distribution with inertia to a monolayer consisting of coexisting phases, we have studied the resulting phase morphology and domain fragmentation. These evolve on distinct time scales: the viscous time associated with the viscosity in the bulk and the Marangoni stress and the fragmentation/relaxation time associated with the phase morphology. A relationship between the microstructure (line tension) and macroflow (shear rate) determining the meso length scale of the coexisting phase domains has been deduced from dimensional analysis and was found to correlate well with the quantitative experimental observations.

Symmetry breaking via global bifurcations of modulated rotating waves in hydrodynamics

The combined experimental and numerical study finds a complex mechanism of Z(2) symmetry breaking involving global bifurcations for the first time in hydrodynamics. In addition to symmetry breaking via pitchfork bifurcation, the Z(2) symmetry of a rotating wave that occurs in Taylor-Couette flow is broken by a global saddle-node-infinite-period (SNIP) bifurcation after it has undergone a Neimark-Sacker bifurcation to a Z(2)-symmetric modulated rotating wave. Unexpected complexity in the bifurcation structure arises as the curves of cyclic pitchfork, Neimark-Sacker, and SNIP bifurcations are traced towards their apparent merging point. Instead of symmetry breaking due to a SNIP bifurcation, we find a more complex mechanism of Z(2) symmetry breaking involving nonsymmetric two-tori undergoing saddle-loop homoclinic bifurcations and complex dynamics in the vicinity of this global bifurcation.

Three-dimensional modes in a periodically driven elongated cavity

Three-dimensional instability modes of the periodic flow in a rectangular cavity driven by the harmonic sliding oscillation of its floor are explored experimentally. Theory for a cavity with infinite span predicts two synchronous modes and a quasiperiodic traveling-wave mode as primary transitions from two-dimensional to three-dimensional flow for different combinations of floor oscillation amplitude and frequency. Previously, only one of the two synchronous modes had been found experimentally. Here, we provide experimental details of both synchronous modes and a quasiperiodic mode. All three modes appear in the parameter regimes predicted by the theory; however, in the finite-span experiments, the traveling wave nature of the quasiperiodic mode is replaced by a nonpropagating mode with spatial features similar to those of the traveling mode.

Influence of coexisting phases on the surface dilatational viscosity of Langmuir monolayers

Monolayer hydrodynamics are usually described in terms of a Newtonian constitutive relationship. However, this macroscopic view fails to account for small-scale coexisting phase domains, which are generally present in the monolayer and appear to have profound macroscopic effects. Here, we provide direct evidence of these effects, consisting of Brewster angle microscopy images of the monolayer, space- and time-resolved interfacial velocity measurements, and comparisons with predictions based on the Navier-Stokes equations together with the classic model for a Newtonian interface.

Molecular Modelling Approaches to the Design of Acetylcholinesterase Inhibitors: New Challenges for the Treatment of Alzheimers Disease

The interest for acetylcholinesterase as a target for the palliative treatment of Alzheimer's disease has been renewed in the last years owing to the evidences that support the role of this enzyme in accelerating the aggregation and deposition of the beta-amyloid peptide. A large amount of structural information on the acetylcholinesterase enzyme and of its complexes with inhibitors acting at the catalytic site, the peripheral binding site, or both is now available. Based on that, molecular modelling studies can be intensively used to decipher the molecular determinants that mediate the relationship between chemical structure and inhibitory potency. In turn, this knowledge can be exploited to design new compounds leading to more effective cholinergic strategies. At this point, inhibitors able to interact at the peripheral binding site are of particular relevance, as they might disrupt the interactions between the enzyme acetylcholinesterase and the beta-amyloid peptide. Therefore, these compounds might not only ameliorate the cholinergic deficit, but also be capable of slowing down the progression of the disease.

Flow-induced patterning of Langmuir monolayers

Insoluble monolayers on water have been patterned at the macroscopic scale (i.e., at the centimeter scale of the flow apparatus) as well as the mesoscopic scale (i.e., down to the micron scale resolvable via optical microscopy). The macroscopic patterning at the air/water interface results from a hydrodynamic instability leading to a steadily precessing flow pattern. The velocity field is measured, and the associated shear stress at the interface is shown to be locally amplified by the flow pattern. The resulting hydrodynamic effects on two different monolayer systems are explored: (1) the pattern in a model monolayer consisting of micron-size, surface-bound particles is visualized to show that the particles are concentrated into isolated regions of converging flow with high shear, and (2) Brewster angle microscopy of a Langmuir monolayer (vitamin K1) shows not only that the monolayer is patterned at the macroscopic scale but also that the localized high-shear flow further patterns the monolayer at the mesoscale.

Open surgical wounds: how does Aquacel compare with wet-to-dry gauze?

OBJECTIVE

To compare the healing rates of a hydrofibre dressing (Aquacel) and normal wet-to-dry gauze in the treatment of open surgical wounds.

METHOD

Fifty patients with open surgical wounds were randomized to receive either saline-moistened gauze or Aquacel. The rate of wound healing was measured as ml/day (deep wounds) or cm2/day (superficial wounds) at each dressing change until an investigator blinded to the patient group diagnosed the wounds as having healed or the patient was withdrawn from the study.

RESULTS

Of the 50 patients, seven were withdrawn from the study after the first evaluation. Of the remaining 43 patients, 21 had been randomly allocated to the gauze group and 22 to the Aquacel group. For deep wounds, a mean change in the wound healing rate of 1.9 +/- 1.3 cm3/day was reported for the gauze group and 2.9 +/- 2.3 cm3/day for the Aquacel group. These results approach statistical significance (p = 0.082). For superficial wounds, the mean change in the healing rate was 1.6 +/- 1.5 cm2/day for the gauze group and 1.9 +/- 2.2 cm2/day for the Aquacel group, but this was not statistically significant.

CONCLUSION

Aquacel appears to be at least as effective as wet-to-dry gauze in the healing of open surgical wounds.

Small aspect ratio Taylor-Couette flow: onset of a very-low-frequency three-torus state

The nonlinear dynamics of Taylor-Couette flow in a small aspect ratio annulus (where the length of the cylinders is half of the annular gap between them) is investigated by numerically solving the full three-dimensional Navier-Stokes equations. The system is invariant to arbitrary rotations about the annulus axis and to a reflection about the annulus half-height, so that the symmetry group is SO(2)xZ2. In this paper, we systematically investigate primary and subsequent bifurcations of the basic state, concentrating on a parameter regime where the basic state becomes unstable via Hopf bifurcations. We derive the four distinct cases for the symmetries of the bifurcated orbit, and numerically find two of these. In the parameter regime considered, we also locate the codimension-two double Hopf bifurcation where these two Hopf bifurcations coincide. Secondary Hopf bifurcations (Neimark-Sacker bifurcations), leading to modulated rotating waves, are subsequently found and a saddle-node-infinite-period bifurcation between a stable (node) and an unstable (saddle) modulated rotating wave is located, which gives rise to a very-low-frequency three-torus. This paper provides the computed example of such a state, along with a comprehensive bifurcation sequence leading to its onset.

Tangent double Hopf bifurcation in a differentially rotating cylinder flow

A tangent double Hopf bifurcation has been found in a rotating cylinder flow driven by the counter-rotation of the top endwall. The codimension-3 tangent double Hopf point has been located using linear stability analysis. The nonlinear analysis of the multiple solutions in a neighborhood of this bifurcation point is performed by numerical solutions of the three-dimensional Navier-Stokes equations. At the tangent double Hopf point, two rotating waves and an unstable modulated rotating wave bifurcate simultaneously. A center manifold/normal form analysis is also performed, which is in very good agreement with both the linear and nonlinear computations. By a detailed exploration of the nonlinear flow, we have unraveled the complex dynamics generated by the mode competition, which is organized by the codimension-3 tangent double Hopf bifurcation.

Noise-induced enhancement of chemical reactions in nonlinear flows

Motivated by the problem of ozone production in atmospheres of urban areas, we consider chemical reactions of the general type: A+B-->2C, in idealized two-dimensional nonlinear flows that can generate Lagrangian chaos. Our aims differ from those in the existing work in that we address the role of transient chaos versus sustained chaos and, more importantly, we investigate the influence of noise. We find that noise can significantly enhance the chemical reaction in a resonancelike manner where the product of the reaction becomes maximum at some optimal noise level. We also argue that chaos may not be a necessary condition for the observed resonances. A physical theory is formulated to understand the resonant behavior. (c) 2002 American Institute of Physics.

Evaluation of a Philippine community based rehabilitation programme

In 1991, the Philippine Department of Health implemented a Philippine Model of the World Health Organisation's Community Based Rehabilitation Programme initiative in pilot areas. The objective of this study was to explore whether, after seven years of operation, the Programme had actually been implemented as planned. The study was conducted in one pilot area in Rosario, La Union, a rural district of Luzon. The research used audit methodology to compare planned services with actual services. The main audit techniques used were record review, in-depth personal interview and focus group discussions. The study showed that such a programme, if properly organised and managed, can meet the needs of the people with disabilities who need rehabilitation. The Community Based Rehabilitation Programme represents a simple cost-effective approach for the delivery of disability prevention and rehabilitation services, particularly in rural areas that have little access to such services.