Role of thermal heating on the voltage induced insulator-metal transition in VO2.

We show that the main mechanism for the dc voltage or dc current induced insulator-metal transition in vanadium dioxide VO(2) is due to local Joule heating and not a purely electronic effect. This "tour de force" experiment was accomplished by using the fluorescence spectra of rare-earth doped micron sized particles as local temperature sensors. As the insulator-metal transition is induced by a dc voltage or dc current, the local temperature reaches the transition temperature indicating that Joule heating plays a predominant role. This has critical implications for the understanding of the dc voltage or dc current induced insulator-metal transition and has a direct impact on applications which use dc voltage or dc current to externally drive the transition.

Multiscroll attractors by switching systems.

In this paper, we present a class of three-dimensional dynamical systems having multiscrolls which we call unstable dissipative systems (UDSs). The UDSs are dissipative in one of its components but unstable in the other two. This class of systems is constructed with a switching law to display various multiscroll strange attractors. The multiscroll strange attractors result from the combination of several unstable "one-spiral" trajectories by means of switching. Each of these trajectories lies around a saddle hyperbolic stationary point. Thus, we describe how a piecewise-linear switching system yields multiscroll attractors, symmetric or asymmetric, with chaotic behavior.

Quartz resonators for penning traps toward mass spectrometry on the heaviest ions.

We report on cyclotron frequency measurements on trapped 206,207Pb+ ions by means of the non-destructive Fourier-transform ion-cyclotron-resonance technique at room temperature. In a proof-of-principle experiment using a quartz crystal instead of a coil as a resonator, we have alternately carried out cyclotron frequency measurements for 206Pb+ and 207Pb+ with the sideband coupling method to obtain 21 cyclotron-frequency ratios with a statistical uncertainty of 6 × 10-7. The mean frequency ratio R¯ deviates by about 2σ from the value deduced from the masses reported in the latest Atomic Mass Evaluation. We anticipate that this shift is due to the ion-ion interaction between the simultaneously trapped ions (≈100) and will decrease to a negligible level once we reach single-ion sensitivity. The compactness of such a crystal makes this approach promising for direct Penning-trap mass measurements on heavy and superheavy elements.

A quartz amplifier for high-sensitivity Fourier-transform ion-cyclotron-resonance measurements with trapped ions.

Single-ion sensitivity is obtained in precision Penning-trap experiments devoted to light (anti)particles or ions with low mass-to-charge ratios, by adding an inductance coil to an amplifier connected to the trap, both operated at 4 K. However, single-ion sensitivity has not been reached on heavy singly or doubly charged ions. In this publication, we present a new system to reach this point, based on the use of a quartz crystal as an inductance, together with a newly developed broad-band (BB) amplifier. We detect the reduced-cyclotron frequency of 40Ca+ ions stored in a 7-tesla open-ring Penning trap. By comparing the detected electric signal obtained with the BB amplifier and the fluorescence signal obtained by collecting the photons emitted by a trapped ion cloud, we show a detection limit below 110 ions. Adding the crystal, the electrical signal increases by a factor of about 30 at room temperature, which combined with the measured equivalent resistance and voltage noise, proves the feasibility of the system to reach single-ion sensitivity at 4 K.

Phase and rheological behavior of the polymerizable surfactant CTAVB and water.

The phase and rheological behaviors of the polymerizable surfactant, cetyltrimethylammonium benzoate (CTAVB), and water as a function of surfactant concentration and temperature are investigated here. The critical micelle concentration (cmc) and the (cmc(2)), as well as the Krafft temperature (T(K)), are reported. A large highly viscous micellar solution region and hexagonal- and lamellar-phase regions were identified. The micellar solutions exhibit shear thickening in the dilute regime, below the overlapping or entanglement concentration. At higher concentrations, wormlike micelles form and the solutions show strong viscoelasticity and Maxwell behavior in the linear regime and shear banding flow in the nonlinear regime. The linear viscoelastic regime is analyzed with the Granek-Cates model, showing that the relaxation is controlled by the kinetics of reformation and scission of the micelles. The steady and unsteady responses in the nonlinear regime are compared with the predictions of the Bautista-Manero-Puig (BMP) model. Model predictions follow the experimental data closely.

Pro-contractile effects of perivascular fat in health and disease.

Perivascular adipose tissue (PVAT) is now recognized as an active player in vascular homeostasis. The expansion of PVAT in obesity and its possible role in vascular dysfunction have attracted much interest. In terms of the regulation of vascular tone and blood pressure, PVAT has been shown to release vasoactive mediators, for instance, angiotensin peptides, reactive oxygen species, chemokines and cytokines. The secretory profile of PVAT is altered by obesity, hypertension and other cardiovascular diseases, leading to an imbalance between its pro-contractile and anti-contractile effects. PVAT adipocytes represent an important source of the mediators, but infiltrating immune cells may become more important under conditions of hypoxia and inflammation. This review describes recent advances in the effects of PVAT on the regulation of vascular tone, highlighting the evidence for a pro-contractile action in health and disease. The role of the endothelium, vascular smooth muscle, immune cells and probably perivascular nerves in PVAT function is also discussed. LINKED ARTICLES: This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

First Report of Gladiolus Rust Caused by Uromyces transversalis in Michoacán, México.

During October 2005, rust lesions were observed on leaves of gladiolus (Gladiolus sp.) plants being grown for flower production in a 20-ha field in eastern Michoacán, México. Disease incidence was near 100% in the field. Five symptomatic plants were collected on 11 and 25 October 2005, from each of 10 farms for further examination. Uredinia were scattered, orange, elliptical to irregular, and arranged transversely across the leaf. The sori were covered by the epidermis initially and later were erumpent and pulverulent. Urediniospores were bright yellow gold, ovate to oblong, and measured 15 × 19 µm (average). The urediniospore wall was hyaline and minutely echinulate. Telia were scattered, dark brown, elliptical, arranged transversely across the leaf, and were covered by the epidermis. Teliospores were irregularly pyriform, ovate, irregular or angular, light to dark brown with a conical or truncate apex and measured 17 × 23 µm (average). The teliospore wall measured 1 µm (average) thick at the sides and 3 µm (average) thick at the apex. Pedicels were light yellow and measured as much as 60 × 3 µm (average). On the basis of these characters, the rust was identified as Uromyces transversalis (Thüm.) G. Winter (1). To our knowledge this is the first report of U. transversalis causing gladiolus rust in Michoacán, México. Originally reported from Africa, the disease has been reported from Argentina, Brazil, southern Europe, and Oceania (1). Gladiolus rust caused by Uromyces transversalis is a quarantine disease for Europe and the United States. There have been unpublished reports of interceptions of this rust on cut flowers of gladiolus going from México into the United States (1). References: (1) J. R. Hernández. Invasive Fungi. Gladiolus Rust. Systematic Botany and Mycology Laboratory, Online publication. ARS, USDA, 2004.

Low vibration high numerical aperture automated variable temperature Raman microscope.

Raman micro-spectroscopy is well suited for studying a variety of properties and has been applied to a wide range of areas. Combined with tuneable temperature, Raman spectra can offer even more insights into the properties of materials. However, previous designs of variable temperature Raman microscopes have made it extremely challenging to measure samples with low signal levels due to thermal and positional instabilities as well as low collection efficiencies. Thus contemporary Raman microscope has found limited applicability to probing the subtle physics involved in phase transitions and hysteresis. This paper describes a new design of a closed-cycle, Raman microscope with full polarization rotation. High collection efficiency, thermal stability, and mechanical stability are ensured by both deliberate optical, cryogenic, and mechanical design. Measurements on two samples, Bi2Se3 and V2O3, which are challenging due to low thermal conductivities, low signal levels, and/or hysteretic effects, are measured with previously undemonstrated temperature resolution.

Search for superconductivity in micrometeorites.

We have developed a very sensitive, highly selective, non-destructive technique for screening inhomogeneous materials for the presence of superconductivity. This technique, based on phase sensitive detection of microwave absorption is capable of detecting 10(-12) cc of a superconductor embedded in a non-superconducting, non-magnetic matrix. For the first time, we apply this technique to the search for superconductivity in extraterrestrial samples. We tested approximately 65 micrometeorites collected from the water well at the Amundsen-Scott South pole station and compared their spectra with those of eight reference materials. None of these micrometeorites contained superconducting compounds, but we saw the Verwey transition of magnetite in our microwave system. This demonstrates that we are able to detect electro-magnetic phase transitions in extraterrestrial materials at cryogenic temperatures.

[How much are hand injuries worth?]. / ¿Cuánto valen las lesiones de la mano?

Hand injuries are some of the most commonly treated injuries at trauma emergency services. Their treatment may be costly and even more so when inappropriate treatment results in complications. The amount paid for the treatment of this kind of injuries may increase dramatically if one considers the direct costs (medical care) and the indirect costs (compensation-loss of profits) resulting from the severity of damage and its sequelae. The objective of this paper is to reveal certain figures that help measure the economic impact that these injuries represent and find ways to optimize resources, minimize costs and improve the care of these patients.

Phase behavior of the Pluronic P103/water system in the dilute and semi-dilute regimes.

The detailed temperature-composition phase diagram of the P103/water system in the dilute and semidilute regions is reported here using density and ultrasound velocity measurements, differential scanning calorimetry (DSC), rheometry and dynamic (DLS) and static light scattering (SLS). These techniques allow a precise determination of the critical micellar temperature (CMT), the sphere-to-rod micellar transition temperature (GMT) and the cloud point temperature (CPT) as a function of concentration. DLS and SLS measurements were employed to gain information on unimers and aggregate sizes and on the transition from spherical-to-rod micelles.

Variation of some secondary metabolites in juvenile stages of three plant species from tropical rain forest.

Results from qualitative and quantitative evaluation of some chemical constituents, particularly phenols and volatile terpenes, from juvenile stages of three primary species belonging to the perennial rain forest are presented. The degree of infection and the time of the year were taken into account. TLC, GC, and simple chemical methods were used to estimate differences among components. Biological assays were conducted to evaluate fungicide potential of the extracts from studied plants. In general terms, the results show significant differences in the chemical composition of the species studied (Nectandra ambigens, Omphalea oleifera, andLicaria alata) related to the time of the year and the degree of infection. These differences can be related as well to their intrinsic resistance to infection and ability to grow to the adult stage.

Optical implementation of the fractional Hilbert transform for two-dimensional objects.

The classical Hilbert transform can be implemented optically as a spatial-filtering process, whereby half the Fourier spectrum is pi-phase shifted. Recently the Hilbert transform was generalized. The generalized version, called the fractional Hilbert transform, is quite easy to implement optically if the input is one dimensional. Here we show how to implement the fractional Hilbert transform for two-dimensional inputs. Hence the new transform is now suitable for image processing.

Internal mammary compartment: window to the mediastinum.

PURPOSE: To determine the role of internal mammary ultrasonography (US) in assessment of the mediastinum. MATERIALS AND METHODS: In 66 patients (age range, 2 days to 18 years old; mean age 6.5 years) US imaging with spectral and color Doppler was used to examine the internal mammary region. Forty-four patients were suspected to have mediastinal masses; 22, vascular abnormalities. RESULTS: Five patients had abnormal internal mammary arterial flow (reversed in one). Internal mammary vein flow was reversed or absent in 10 patients with vein obstruction or Glenn shunts. Eight of 23 patients with lymphoma had internal mammary adenopathy. None of six patients with infectious mediastinal adenopathy and no patients with other benign mediastinal masses or vascular abnormalities had visualized internal mammary nodes. CONCLUSION: US and Doppler imaging of the internal mammary vessels and nodes provide valuable information about the nature of mediastinal masses and vascular disease. Flow pattern in the internal mammary vessels may elucidate abnormalities of central vessels.