Underwater channel estimation exploiting multipath feature morphology.

Real-time accurate channel estimation has been an ongoing challenge because of diverse oceanic events that cause rapid fluctuations of high-energy multipath activity across the delay spread. This work leverages current compressed sensing and sparse optimization techniques with topological signal processing to improve estimation time and localize channel estimation to salient parts of the delay spread. This work improves the estimation time by tracking the channel as a union of overlapping multipath and other scattering events, which are modeled as "feature braids" in the delay-time domain. A channel feature braid may be intuitively visualized as the topologically connected trajectory of a group of channel delay taps, which represent the support of dominant or persistent scattering events, e.g., surface bounce multipath scattering. We present algorithms that harness support-constrained mixed norm optimization techniques to track the evolving support of channel feature braids. We validate our channel feature tracking algorithm independently in experimental field data as well as BELLHOP channel simulations across a diversity of oceanic conditions. This work shows that braiding used in estimation can improve estimation time and track high-energy events that develop within the delay vs time channel representation.

The Electric and Magnetic Fields Instrument Suite and Integrated Science (EMFISIS): Science, Data, and Usage Best Practices.

We provide a post-mission assessment of the science and data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation on the NASA Van Allen Probes mission. An overview of important scientific results is presented, covering all of the key wave modes and DC magnetic fields measured by EMFISIS. Discussion of the data products, which are publicly available, follows to provide users with guidance on characteristics and known issues of the measurements. We present guidance on the correct use of derived products, in particular, the wave-normal analysis (WNA) which yields fundamental wave properties such as polarization, ellipticity, and Poynting flux. We also give information about the plasma density derived from measuring the upper hybrid line in the inner magnetosphere.

Assessment of whole blood coagulation with a microfluidic dielectric sensor.

Essentials ClotChip is a novel microsensor for comprehensive assessment of ex vivo hemostasis. Clinical samples show high sensitivity to detecting the entire hemostatic process. ClotChip readout exhibits distinct information on coagulation factor and platelet abnormalities. ClotChip has potential as a point-of-care platform for comprehensive hemostatic analysis. SUMMARY: Background Rapid point-of-care (POC) assessment of hemostasis is clinically important in patients with a variety of coagulation factor and platelet defects who have bleeding disorders. Objective To evaluate a novel dielectric microsensor, termed ClotChip, which is based on the electrical technique of dielectric spectroscopy for rapid, comprehensive assessment of whole blood coagulation. Methods The ClotChip is a three-dimensional, parallel-plate, capacitive sensor integrated into a single-use microfluidic channel with miniscule sample volume (< 10 µL). The ClotChip readout is defined as the temporal variation in the real part of dielectric permittivity of whole blood at 1 MHz. Results The ClotChip readout exhibits two distinct parameters, namely, the time to reach a permittivity peak (Tpeak ) and the maximum change in permittivity after the peak (Δεr,max ), which are, respectively, sensitive towards detecting non-cellular (i.e. coagulation factor) and cellular (i.e. platelet) abnormalities in the hemostatic process. We evaluated the performance of ClotChip using clinical blood samples from 15 healthy volunteers and 12 patients suffering from coagulation defects. The ClotChip Tpeak parameter exhibited superior sensitivity at distinguishing coagulation disorders as compared with conventional screening coagulation tests. Moreover, the ClotChip Δεr,max parameter detected platelet function inhibition induced by aspirin and exhibited strong positive correlation with light transmission aggregometry. Conclusions This study demonstrates that ClotChip assesses multiple aspects of the hemostatic process in whole blood on a single disposable cartridge, highlighting its potential as a POC platform for rapid, comprehensive hemostatic analysis.

In vitro characterization of SynthoPlate™ (synthetic platelet) technology and its in vivo evaluation in severely thrombocytopenic mice.

Essentials Platelet transfusion suffers from availability, portability, contamination, and short shelf-life. SynthoPlate™ (synthetic platelet technology) can resolve platelet transfusion limitations. SynthoPlate™ does not activate resting platelets or stimulate coagulation systemically. SynthoPlate™ significantly improves hemostasis in thrombocytopenic mice dose-dependently. SUMMARY: Background Platelet transfusion applications face severe challenges, owing to the limited availability and portability, high risk of contamination and short shelf-life of platelets. Therefore, there is significant interest in synthetic platelet substitutes that can provide hemostasis while avoiding these issues. Platelets promote hemostasis by injury site-selective adhesion and aggregation, and propagation of coagulation reactions on their membranes. On the basis of these mechanisms, we have developed a synthetic platelet technology (SynthoPlate™) that integrates platelet-mimetic site-selective 'adhesion' and 'aggregation' functionalities via heteromultivalent surface decoration of lipid vesicles with von Willebrand factor-binding, collagen-binding and active platelet integrin glycoprotein (GP) IIb-IIIa-binding peptides. Objective To evaluate SynthoPlate for its effects on platelets and plasma in vitro, and for systemic safety and hemostatic efficacy in severely thrombocytopenic mice in vivo. Methods In vitro, SynthoPlate was evaluated with aggregometry, fluorescence microscopy, microfluidics, and thrombin and fibrin generation assays. In vivo, SynthoPlate was evaluated for systemic safety with prothrombin and fibrin assays on plasma, and for hemostatic effects on tail-transection bleeding time in severely thrombocytopenic (TCP) mice. Results SynthoPlate did not aggregate resting platelets or spontaneously promote coagulation in plasma, but could amplify the recruitment and aggregation of active platelets at the bleeding site, and thereby site-selectively enhance fibrin generation. SynthoPlate dose-dependently reduced bleeding time in TCP mice, to levels comparable to those in normal mice. SynthoPlate has a reasonable circulation residence time, and is cleared mostly by the liver and spleen. Conclusion The results demonstrate the promise of SynthoPlate as a synthetic platelet substitute in transfusion treatment of platelet-related bleeding complications.

Note: Measuring capacitance and inductance of a helical resonator and improving its quality factor by mutual inductance alteration.

Narrow bandwidth and high voltage radio frequency (RF) is an essential requirement for stable confinement of ions within a RF trap and helical resonators are commonly used for that purpose. Effective capacitance and inductance of a helical resonator are estimated by measuring resonant frequencies for different external loads. Load capacitance of an ion trap can be estimated from this method and a resonator can be constructed for desired resonant frequency. We demonstrate a very simple method to achieve higher Q-factor of a resonator by optimizing mutual separation between the primary antenna and helical coil. We also formulate a set of analytical equations for calculating overall inductance, resistance, and Q-factor of a loaded helical resonator.

In vitro evaluation and in vivo demonstration of a biomimetic, hemocompatible, microfluidic artificial lung.

Despite the promising potential of microfluidic artificial lungs, current designs suffer from short functional lifetimes due to surface chemistry and blood flow patterns that act to reduce hemocompatibility. Here, we present the first microfluidic artificial lung featuring a hemocompatible surface coating and a biomimetic blood path. The polyethylene-glycol (PEG) coated microfluidic lung exhibited a significantly improved in vitro lifetime compared to uncoated controls as well as consistent and significantly improved gas exchange over the entire testing period. Enabled by our hemocompatible PEG coating, we additionally describe the first extended (3 h) in vivo demonstration of a microfluidic artificial lung.

Synthesis and evaluation of substituted 4(3H)-quinazolone derivatives for antimicrobial and antiacetylcholinesterase activities. Part 3.

The synthesis of some new 6,8-dibromo-2-N-(N-arylcarbamoyl) carbamoylmethylthio-3-aryl-4(3H)-quinazolone derivatives is described. The synthesized derivatives were screened for their antibacterial, antifungal and antiacetylcholinesterase activities in vitro. Most of the compounds exhibited interesting antimicrobial activities. The relation between this and their chemical structure has been studied.

Note: reliable and reusable ultrahigh vacuum optical viewports.

We report a simple technique for the realization of ultrahigh vacuum optical viewports. The technique relies on using specially designed thin copper knife-edges and using a thin layer of Vacseal(®) on tip of the knife-edges between the optical flat and the ConFlat(®) (CF) flange. The design of the windows is such that it gives uniform pressure on the flat without breaking it. The assembled window is a complete unit, which can be mounted directly onto a CF flange of the vacuum chamber. It can be removed and reused without breaking the window seal. The design is reliable as more than a dozen such windows have survived several bake out and cooling cycles and have been leak tested up to 10(-11) Torr l/s level with a commercial Helium leak detector. The advantages of this technique are ease of assembly and leak proof sealing that survives multiple temperature cycling making the windows reliable and reusable.

Simple alignment technique for polarisation maintaining fibres.

We describe a simple technique for rapid alignment of input state of polarisation with respect to the preferred axis of polarisation maintaining fibres. In this technique a combination of a half-wave and a quarter-wave plate is used to turn the polarisation of incoming beam and to compensate for stress-induced perturbation of polarisation states in a laid-out fibre, respectively. The angular alignment technique is tested with temperature excursion on the fibre. The technique is easy to implement, affordable, and gives quick and accurate alignment.

[A rapid method for determination of oil in lecithins (author's transl)]. / Schnellmethode zur Bestimmung des Olanteils in Lecithin

A rapid method for routine determination of oil in commercial lecithins and similar phospholipid samples has been worked out. This based on the observation that under the described experimental conditions 1 g of phospholipids is completely adsorbed on 45 g silica gel which has previously been disactivated by the addition of 15% water. The lecithin sample is filtered in ethereal solution through a column filled with disactivated silica gel which is subsequently washed with a little ether. The combined ether eluates are evaporated to dryness invacuo and the residue weighed. This residue is the oil part of the sample and is constituted of mono-, di-, and triglycerides, free fatty acids, sterols and their derivatives. The duration for one such determination is about 20 min.

Synthesis of some new hydrazone derivatives as biologically active agents.

A series of [4-(6H/bromo-4-oxo-2-phenyl-3(4H)-quinazolinyl)phenoxy]acetic acid (1,2-dihydro-1-H/methyl-2-oxo-3H-indol-3-ylidene)hydrazides (VII1-16) were synthesised by condensing 1-H/methyl-5-substituted indoline-2,3-diones with [4-(6H/bromo-4-oxo-2-phenyl-3(4H)-quinazolinyl) phenoxy]acetic acid hydrazides (IV1-2) which in turn were obtained by reacting ethyl [4-(6H/bromo-4-oxo-2-phenyl-3(4H)-quinazolinyl)phenoxy]acetates (III1-2) with hydrazine hydrate. All the synthesised compounds (VIII1-16) were screened for their antibacterial, acetylcholinesterase enzyme inhibitory and antiviral activities.

Middle aortic syndrome as a cause of heart failure in children and its management.

Two cases of middle aortic syndrome in children are described along with two other cases reported earlier. In childhood, this disease may present as incipient or overt cardiac failure. Surgical treatment should be undertaken based on an objective assessment of the severity of the stricture and after taking into account the future growth of the child.