Current role of ultrasound in hemodialysis access evaluation

: Physical examination (PE) is considered the backbone before vascular access (VA) placement, during maturation period and for follow-up. However, it may be inadequate in identifying suitable vasculature, mainly in comorbid patients, or in detecting complications. This review highlights the advantages of ultrasound imaging to manage VA before placement, during maturation and follow-up. Furthermore, it analyses the future perspectives in evaluating early and late VA complications thank to the availability of multiparametric platforms, point of care of ultrasound, and portable/wireless systems. Technical improvements and low-cost systems should favor the widespread ultrasound-based VA surveillance programs. This significant turning point needs an adequate training of nephrologists and dialysis nurses and the standardization of exams, parameters, and procedures

Basics for performing a high-quality color Doppler sonography of the vascular access

: In the last years, the systematic use of ultrasound mapping of the upper limb vascular network before the arteriovenous fistula (AVF) implantation, access maturation, and clinical management of late complications is widespread and expanding. Therefore, a good knowledge of theoretical outlines, instrumentation, and operative settings is undoubtedly required for a thorough examination. In this review, the essential Doppler parameters, B-Mode setting, and Doppler applications are considered. Basic concepts on the Doppler shift equation, angle correction, settings on pulse repetition frequency, operative Doppler frequency, gain are reported to ensure adequate and correct sampling of blood flow velocity. A brief analysis of the Doppler inherent artefacts (as random noise, blooming, aliasing, and motion artefacts) and the adjustment setting to minimize or eliminate the confounding artefacts are also considered. Doppler aliasing occurs when the pulse repetition frequency is set too low. This artefact is particularly frequent in vascular access sampling due to the high velocities range registered in the fistula's different segments. Aliasing should be recognized because its correction is crucial to analyse the Doppler signals correctly. Recent advances in instrumentation are also considered about a potential purchase of a portable ultrasound machine or a top-of-line, high-end, or mid-range ultrasound system. Last, the pulse wave Doppler setting for vascular access B-Mode and Doppler assessment is summarized

A new method for the identification of phytoplasmas in strawberries (Fragaria fragaria)

Motivation:Phytoplasmas are plant pathogens that generally inhabit the phloem and are transmitted from plant to plant by vector insects that feed on phloem. Their genome is small, with a high content of genes (1). The presence of extrachromosomal DNA has also been detected (2). Serological and molecular studies have shown that phytoplasmas contain a gene encoding a membrane protein and this is unique for each specie and helps to identify what type of phytoplasma is, according to its taxonomic classification (3). Different phytoplasmas had been detected and identified in strawberries plants (Fragaria fragaria). Symptoms observed on strawberries were yellow coloration of leaves, plant stunting, and reduced leaf size and the virescence were observed in the inflorescence. PCR analyses as well as sequencing of 16S ribosomal gene enabled the identification of phytoplasmas belonging to two ribosomal groups, namely stolbur and aster yellows, but the eficiency for this detection is not reliable. Here we are working to develop a new method to easily detect and identify this pathogen in plant samples before symptoms appear.Methods: 70 samples of strawberries infected with phytoplasma were tested, by,analysing leaves, crown and root in the strawberry plant to determine the most optimal zone to be sampled. The identification of phytoplasmas required a double PCRs  using phytoplasma universal primer pair P1/P7, followed by nested PCR with Fu5/Ru3 primers. Further nested PCR reactions on R16mF2/R1 amplicons were also performed with R16F2N/R2 primer pair, specific for phytoplasma belonging to aster yellow to determine their class. Asymptomatic samples were also analysed as negative controls in each PCR reaction. The amplified DNA was sequenced and the sequence analysed by Blast.Results:With this PCR method, the presence of phytoplasma was mainly detected in strawberries roots but not in leaves and crowns. This technique allowed us to detect presence of high amount of phytoplasma because a positive result in the first PCR, low amount with a positive result only in the second one, or no presence because negative result in both. Finally,, the sequencing of the amplified DNA, allowed us to determine if they belong to aster yellow or stolbur because they DNA identity.Conclusions: This new phytoplasma identification method is effective. It would be interesting to obtain a specific primer for each specie of phytoplasma and thus have a more precise method

Paying for parking : improving stated-preference surveys

This article describes an experiment which introduced random ranges into the variables used for the design of a stated preference survey and its effects on willingness to pay for parking. User behaviour at the time of parking was modelled to determine their willingness to pay in order to get to their final destination more quickly. Calculating willingness to pay is fundamental during the social and economic assessment of projects. It is important to correctly model how car parks and their users interact in order to get values which represent reality as closely as possible. Willingness to pay is calculated using a stated preference survey and by calibrating multinomial logit models, taking variable tastes into account. It is shown that a value with a low variability can be obtained for willingness to pay by correctly establishing the context of the choice and randomly changing the variables around an average value

Assessing the Gene Content of the Megagenome: Sugar Pine (Pinus lambertiana).

Sugar pine (Pinus lambertiana Douglas) is within the subgenus Strobus with an estimated genome size of 31 Gbp. Transcriptomic resources are of particular interest in conifers due to the challenges presented in their megagenomes for gene identification. In this study, we present the first comprehensive survey of the P. lambertiana transcriptome through deep sequencing of a variety of tissue types to generate more than 2.5 billion short reads. Third generation, long reads generated through PacBio Iso-Seq have been included for the first time in conifers to combat the challenges associated with de novo transcriptome assembly. A technology comparison is provided here to contribute to the otherwise scarce comparisons of second and third generation transcriptome sequencing approaches in plant species. In addition, the transcriptome reference was essential for gene model identification and quality assessment in the parallel project responsible for sequencing and assembly of the entire genome. In this study, the transcriptomic data were also used to address questions surrounding lineage-specific Dicer-like proteins in conifers. These proteins play a role in the control of transposable element proliferation and the related genome expansion in conifers

The role of Doppler ultrasonography in vascular access surveillance—controversies continue

: Chronic hemodialysis therapy required regular entry into the patient's blood stream with adequate flow. The use of arteriovenous fistulas and grafts is linked with lower morbidity and mortality than the use of catheters. However, these types of accesses are frequently affected by stenoses, which decrease the flow and lead to both inadequate dialysis and access thrombosis. The idea of duplex Doppler ultrasound surveillance is based on the presumption that in-time diagnosis of an asymptomatic significant stenosis and its treatment prolongs access patency. Details of performed trials are conflicting, and current guidelines do not support ultrasound surveillance. This review article summarizes the trials performed and focuses on the reasons of conflicting results. We stress the need of precise standardized criteria of significant access stenosis and the weakness of the metaanalyses performed

Stability of Switched Linear Discrete-Time Descriptor Systems with Explicit Calculation of a Common Quadratic Lyapunov Sequence

Abstract-In this paper, the stability of a switched linear regular descriptor system is considered. It will be shown that if a certain simultaneous triangularization condition on the subsystems is fulfilled and all the subsystems are stable then the switched system is stable under arbitrary switching. The result involves different descriptor matrices and extends to the singular case well-known results from the standard one. Furthermore, an explicit construction of a common Lyapunov sequence for a set of discrete-time regular linear descriptor subsystems is performed. The main novelty of the proposed approach is that the common Lyapunov sequence can be easily computed in comparison with previous works which either presented computationally-demanding methods or did not construct the common Lyapunov sequence explicitly

Locally Expansive Solutions for a Class of Iterative Equations

Iterative equations which can be expressed by the following form ( ) = ( , ( ), 2 ( ), . . . , −1 ( )), where ≥ 2, are investigated. Conditions for the existence of locally expansive 1 solutions for such equations are given

Modelling gender perception of quality in interurban bus services

This paper models how women and men perceive the quality of interurban bus services and proposes a new methodology for detecting the highest priority service variables to act on. Service quality perception was modelled using both ordered logit and ordered probit models using data from revealed preference surveys. The methodology for detecting different priority levels uses the graphic representation of the relationships between influence in the model and average evaluation by users. The modification of certain variables increases the knowledge of how woman evaluate quality in bus services to help promote the use of interurban public transport. Statistical analysis of the data provides some conclusions such as: the proportion of users increases as age decreases for both men and women; and women seem to make shorter and more frequent trips than men. The best model for this data set was ordered logit. As expected, the most relevant variable is the relationship between quality and price. Other important variables are the condition of the bus and the frequency of service