Takayasu arteritis: criteria for surgical intervention should not be ignored.

Takayasu aortoarteritis is a rare, chronic granulomatous panarteritis with significant morbidity amongst young patients. Current challenges include a lack of awareness about the condition, delays in diagnosis due to its varied presentation, and suboptimal methods for assessing disease activity. The development of noninvasive imaging including magnetic resonance angiography and positron emission tomography is aiding earlier diagnosis. Early initiation of immunosuppressive treatment is crucial to control active inflammation and minimize arterial injury. Recent studies investigating biological agents such as tumour necrosis factor- α antagonists are encouraging. Surgical revascularization should only be undertaken following careful consideration, as restenosis is common. The indications for considering intervention include uncontrolled hypertension due to renal artery stenosis, severe symptomatic coronary artery or cerebrovascular disease, severe aortic regurgitation, stenotic or occlusive lesions resulting in critical limb ischemia, and aneurysms at risk of rupture. In these cases, the risk benefit ratio for intervention is good. Open surgery, at present, has better outcomes compared to endovascular techniques. However, technological advances in endovascular treatment are continually improving. Controlling disease activity prior to and following revascularization is key to preventing complications. A multidisciplinary approach to the diagnosis and management of Takayasu arteritis is essential to achieve satisfactory patient outcomes

A Differential Positioning System Using Modulation Correlation of Signals of Opportunity

Global Navigation Satellite Systems (GNSS) have become the positioning systems of choice for many applications. However, GNSS signals are susceptible to obstruction, interference and jamming. Therefore, to maximize robustness and integrity, it is necessary to employ a dissimilar positioning technology that can operate independently and back-up GNSS. One such technology exploits ‘signals of opportunity’ – signals that are designed for purposes other than navigation. This paper presents a system that uses amplitude modulation (AM) radio broadcasts in the medium frequency (MF) band. At these frequencies, the predominant ground-wave propagation mode offers better coverage in remote areas and over sea than is achievable with higher frequency signals. The system is differential and operates by correlating modulation information between the reference and user receivers. A system of this form mitigates the deterioration in and around buildings encountered in prior systems and can provide absolute position using fewer signals than a system using only carrier phase. The system presented in this paper uses generalized cross correlation to obtain time difference of arrival measurements that are subsequently used for position determination. Preliminary results indicate the system provides a robust position solution. Moreover, the system offers the potential to be combined with carrier phase measurements to achieve enhanced performance, while the modulation correlation technique is readily extendable to other types of signal

A New Differential Positioning Method using Modulation Correlation of Signals of Opportunity

Global Navigation Satellite Systems (GNSS) have become the positioning systems of choice for many applications. However, GNSS signals are susceptible to obstruction, interference and jamming. Therefore, to maximize robustness and integrity, it is necessary to employ a dissimilar positioning technology that can operate independently and back-up GNSS. One such technology exploits 'signals of opportunity' - signals that are designed for purposes other than navigation.This paper presents a system that uses amplitude modulation (AM) radio broadcasts in the medium frequency (MF) band. At these frequencies, the predominant ground-wave propagation mode offers better coverage in remote areas and over sea than is achievable with higher frequency signals.The system is differential and operates by correlating modulation information between the reference and user receivers. A system of this form mitigates the deterioration in and around buildings encountered in prior systems and can provide absolute position using fewer signals than a system using only carrier phase.The system presented in this paper uses generalized cross correlation to obtain time difference of arrival measurements that are subsequently used for position determination. Preliminary results indicate the system provides a robust position solution. Moreover, the system offers the potential to be combined with carrier phase measurements to achieve enhanced performance, while the modulation correlation technique is readily extendable to other types of signal

Using a Microwave Sensor as an Online Indicator of Neurological Impairment during Surgical Procedures

Lactate is known to be an indicator of neurological impairment during aortic aneurysm surgery. It is suggested that analysis of cerebrospinal fluid (CSF) removed during such surgery could provide useful information in this regard. Medical professionals find the prospect of online detection of such analytes exciting, as current practice is time consuming and leads to multiple invasive procedures. Advancing from the current laboratory based analysis techniques to online methods could provide the basis for improved treatment regimes, better quality of care, and enhanced resource efficiency within hospitals. Accordingly, this article considers the use of a low power microwave sensor to detect varying lactate concentrations. Microwave sensors provide a rapid non-invasive method of material analysis, which is robust, cost-effective, and has huge potential for a wide range of biomedical applications

Non Invasive Microwave Sensor for the Detection of Lactic Acid in Cerebrospinal Fluid (CSF)

This research involves the use of a low power microwave sensor for analysis of lactic acid in cerebrospinal fluid (CSF), an indicator of neurological impairment during aortic aneurysm surgery which could provide the basis for improved treatment regimes and better quality of care with more efficient use of resources. This paper presents initial work using standard lactate curves in water followed by lactate in “synthetic CSF”. A multi-modal spectral signature has been defined for lactate, forming the basis for subsequent development of microwave sensor platform that is able to detect concentrations of lactic acid in CSF of volumes less than 1m

Real-Time Monitoring of Bodily Fluids Using a Novel Electromagnetic Wave Sensor

The use of a novel low power electromagnetic sensor for real-time detection of lactate in cerebrospinal fluid (CSF) is investigated. CSF holds key indicators relating to a patient’s future health. A multipurpose sensor platform is currently being developed with the capability to detect the concentration of materials in volumes =1 ml. This paper presents results from a microwave cavity resonator designed and created for this purpose, using varying concentrations of lactate in water. The work demonstrates the feasibility of monitoring bodily fluids in real-time. Such advancements are essential for improved and cost-effective delivery of healthcare services to patients

A New Differential Positioning Technique Applicable to Generic FDMA Signals of Opportunity

A differential positioning technique is proposed that is capable of exploiting the many radio frequency (RF) signals that are transmitted using frequency division multiple access (FDMA). The technique is designed to operate on ‘signals of opportunity’ (signals that are designed for purposes other than navigation), and requires no knowledge of the modulation format or signal content. Example FDMA signals of opportunity include amplitude modulated (AM) broadcast signals, frequency modulated (FM) broadcast signals, and television signals. In principle, the system can operate simultaneously on these different types of signals, maximizing performance by exploiting heterogeneous signal qualities and using whatever signals are available at a particular location. As a result, the technology has the potential to provide positioning in Global Navigation Satellite System (GNSS) deprived environments, such as in urban canyons, and deep indoors. The proposed positioning technique operates by bringing portions of a signal received at reference and user locations together and adaptively correlation testing them. The correlation-testing is used to jointly estimate the differential time offset (DTO) and the differential frequency offset (DFO). In order to improve accuracy the DTO measurements are Doppler-smoothed using the DFO measurements. The DTO measurements are used to calculate ranging measurements that are used to obtain a position. The concept is experimentally validated on AM broadcast signals in the medium frequency (MF) and low frequency (LF) bands. Preliminary results indicate that the system provides a position solution in difficult environments, such as indoors. It is expected that expanding the system to incorporate more signals will result in significant performance gains

On All-loop Integrands of Scattering Amplitudes in Planar N=4 SYM

We study the relationship between the momentum twistor MHV vertex expansion of planar amplitudes in N=4 super-Yang-Mills and the all-loop generalization of the BCFW recursion relations. We demonstrate explicitly in several examples that the MHV vertex expressions for tree-level amplitudes and loop integrands satisfy the recursion relations. Furthermore, we introduce a rewriting of the MHV expansion in terms of sums over non-crossing partitions and show that this cyclically invariant formula satisfies the recursion relations for all numbers of legs and all loop orders.Comment: 34 pages, 17 figures; v2: Minor improvements to exposition and discussion, updated references, typos fixe

Nanotechnology and molecular cytogenetics: the future has not yet arrived

Quantum dots (QDs) are a novel class of inorganic fluorochromes composed of nanometer-scale crystals made of a semiconductor material. They are resistant to photo-bleaching, have narrow excitation and emission wavelengths that can be controlled by particle size and thus have the potential for multiplexing experiments. Given the remarkable optical properties that quantum dots possess, they have been proposed as an ideal material for use in molecular cytogenetics, specifically the technique of fluorescent in situ hybridisation (FISH). In this review, we provide an account of the current QD-FISH literature, and speculate as to why QDs are not yet optimised for FISH in their current form

Upper- and mid-mantle interaction between the Samoan plume and the Tonga-Kermadec slabs

Mantle plumes are thought to play a key role in transferring heat from the core\u2013mantle boundary to the lithosphere, where it can significantly influence plate tectonics. On impinging on the lithosphere at spreading ridges or in intra-plate settings, mantle plumes may generate hotspots, large igneous provinces and hence considerable dynamic topography. However, the active role of mantle plumes on subducting slabs remains poorly understood. Here we show that the stagnation at 660 km and fastest trench retreat of the Tonga slab in Southwestern Pacific are consistent with an interaction with the Samoan plume and the Hikurangi plateau. Our findings are based on comparisons between 3D anisotropic tomography images and 3D petrological-thermo-mechanical models, which self-consistently explain several unique features of the Fiji\u2013Tonga region. We identify four possible slip systems of bridgmanite in the lower mantle that reconcile the observed seismic anisotropy beneath the Tonga slab (VSH4VSV) with thermo-mechanical calculations