Full Retrieval Research Articles

Efficient descriptor for full and partial shape matching

In this paper we present a new approach for full and partial shape retrieval based on a shape descriptor invariant to geometric transformations, reflection and deformation. The proposed description...

Towards a full retrieval of the deformation tensor F using convergent beam electron diffraction

A new method to retrieve the local lattice parameters and rotations in a crystal from off-axis convergent beam electron diffraction (CBED) patterns is presented and validated using Bloch wave dynamical simulations. The originality of the method is to use both the diffracted and transmitted beams and to use kinematical approximations in the fitting algorithm. The study is based on the deformation gradient tensor F which includes rotation and strain. Working on simulated images it is shown that (i) from a single direction of observation, seven parameters out of the nine parameters of F can be determined with an accuracy of 3×10−4 for the normal strain parameters εxx, εyy, and εzz, (ii) the unit cell volume can only be retrieved if the diffracted and transmitted beams are both included in the fitting and (iii) all the nine parameters of F can be determined by combining two directions of observation separated by about 20°.

Retrieving depth-direction information from TEM diffraction data under reciprocal-space sampling variation.

For full three-dimensional information retrieval from transmission electron microscope data, retrieving the third-dimension (beam-direction) information is an important challenge. Recently, we have developed an artificial-neural-network-based retrieval algorithm suitable for retrieving three-dimensional nanoscale crystal parameters like strain, including with noisy data (R.S. Pennington, W. Van den Broek, C.T. Koch, Phys. Rev. B 89 (20) (2014) 205409 [12]). In this work, we examine how reciprocal-space sampling conditions influence the retrieved crystal parameters, using crystal tilt as an example parameter, and demonstrate retrieval for 2.5 nm depth resolution. For noise-free data, we find that the total reciprocal-space area is the key parameter; however, when the data are noisy, the number of reciprocal-space points and the amount of noise are also influential. We also apply our algorithm to a simulated bent specimen, and recover the bending as expected. Guidelines for experimental applications are also discussed.

The Lotus transcather aortic valve: a next-generation repositionable, resheathable and recapturable prosthesis

Symptomatic severe aortic stenosis occurs in 2–4% of people aged over 65 years, with calcific degeneration being the predominant etiology in the developed world. Surgical valve replacement has been and remains the gold-standard treatment modality, yet a significant number of high-risk individuals are denied or refuse this potentially life-saving treatment. Transcatheter aortic valve replacement has proven efficacy in this high-risk cohort. Current-generation transcatheter aortic valve replacement devices, however, have significant limitations. The Lotus transcatheter device represents an evolution of this technology that allows full resheathing, repositioning and retrieval, which together with features designed to minimize para-prosthetic regurgitation address a number of the limitations of first-generation devices.

Hierarchical Geometry Verification via Maximum Entropy Saliency in Image Retrieval

We propose a new geometric verification method in image retrieval—Hierarchical Geometry Verification via Maximum Entropy Saliency (HGV)—which aims at filtering the redundant matches and remaining the information of retrieval target in images which is partly out of the salient regions with hierarchical saliency and also fully exploring the geometric context of all visual words in images. First of all, we obtain hierarchical salient regions of a query image based on the maximum entropy principle and label visual features with salient tags. The tags added to the feature descriptors are used to compute the saliency matching score, and the scores are regarded as the weight information in the geometry verification step. Second we define a spatial pattern as a triangle composed of three matched features and evaluate the similarity between every two spatial patterns. Finally, we sum all spatial matching scores with weights to generate the final ranking list. Experiment results prove that Hierarchical Geometry Verification based on Maximum Entropy Saliency can not only improve retrieval accuracy, but also reduce the time consumption of the full retrieval.

Transfemoral aortic valve replacement with the repositionable Lotus Valve System in high surgical risk patients: the REPRISE I study

To assess outcomes with a new fully repositionable and retrievable valve for transcatheter aortic valve replacement (TAVR). The Lotus Aortic Valve System is designed to facilitate precise positioning and minimise paravalvular regurgitation. REPRISE I enrolled symptomatic, high-surgical-risk patients with severe aortic stenosis. The primary endpoint (clinical procedural success) included successful implantation without major adverse cardiovascular or cerebrovascular events (MACCE). In all patients (N=11) the first Lotus Valve was successfully deployed. Partial resheathing to facilitate accurate placement was attempted and successfully performed in four patients; none required full retrieval. The primary endpoint was achieved in 9/11 with no in-hospital MACCE in 10/11. There was one major stroke; in another patient, discharge mean aortic gradient was 22 mmHg (above the primary endpoint threshold of 20 mmHg), but improved to 15 mmHg at 30 days. The cohort's mean aortic gradient decreased from 53.9±20.9 mmHg at baseline to 15.4±4.6 mmHg (p<0.001) at one year; valve area increased from 0.7±0.2 cm2 to 1.5±0.2 cm2 (p<0.001). Discharge paravalvular aortic regurgitation, adjudicated by an independent core laboratory, was mild (n=2), trivial (n=1), or absent (n=8). Four patients required a permanent pacemaker post-procedure. There were no deaths, myocardial infarctions or new strokes through one year. Initial results support proof-of-concept with the Lotus Valve for TAVR.

The next era of transcatheter aortic valve replacement: A case illustrating the benefit of a fully re‐positionable, re‐sheathable, and retrievable prosthesis

While transcatheter aortic valve replacement (TAVR) is an accepted treatment modality in appropriately selected patients there remain modest complication rates. New TAVR devices, through novel design features, may overcome some of these complications. We present the first case of full re-sheathing and retrieval of a Lotus Valve to facilitate a change in prosthesis size.

Averaging kernel prediction from atmospheric and surface state parameters based on multiple regression for nadir-viewing satellite measurements of carbon monoxide and ozone

Abstract. A current obstacle to the observation system simulation experiments (OSSEs) used to quantify the potential performance of future atmospheric composition remote sensing systems is a computationally efficient method to define the scene-dependent vertical sensitivity of measurements as expressed by the retrieval averaging kernels (AKs). We present a method for the efficient prediction of AKs for multispectral retrievals of carbon monoxide (CO) and ozone (O3) based on actual retrievals from MOPITT (Measurements Of Pollution In The Troposphere) on the Earth Observing System (EOS)-Terra satellite and TES (Tropospheric Emission Spectrometer) and OMI (Ozone Monitoring Instrument) on EOS-Aura, respectively. This employs a multiple regression approach for deriving scene-dependent AKs using predictors based on state parameters such as the thermal contrast between the surface and lower atmospheric layers, trace gas volume mixing ratios (VMRs), solar zenith angle, water vapor amount, etc. We first compute the singular value decomposition (SVD) for individual cloud-free AKs and retain the first three ranked singular vectors in order to fit the most significant orthogonal components of the AK in the subsequent multiple regression on a training set of retrieval cases. The resulting fit coefficients are applied to the predictors from a different test set of test retrievals cased to reconstruct predicted AKs, which can then be evaluated against the true retrieval AKs from the test set. By comparing the VMR profile adjustment resulting from the use of the predicted vs. true AKs, we quantify the CO and O3 VMR profile errors associated with the use of the predicted AKs compared to the true AKs that might be obtained from a computationally expensive full retrieval calculation as part of an OSSE. Similarly, we estimate the errors in CO and O3 VMRs from using a single regional average AK to represent all retrievals, which has been a common approximation in chemical OSSEs performed to date. For both CO and O3 in the lower troposphere, we find a significant reduction in error when using the predicted AKs as compared to a single average AK. This study examined data from the continental United States (CONUS) for 2006, but the approach could be applied to other regions and times.

Methylation and hydroxymethylation of CpG display dynamic landscapes in early embryo development and define differentiation into embryonic and placental lineages

Covalent modifications to cytosine provide important epigenetic information required for normal embryo development. 5’methylcytosine (5mC) has received most experimental attention while 5’hydroxymethyl cytosine (5hmC) has assumed recent prominence. Extant gold-standard methods of analysis of do not discriminate between 5mC and 5hmC hence most published methylomes have limits to their interpretation. Immunolocalization allows discrimination between the range of modifications, provides a genome-wide level of analysis, allows differential assessment of nuclear localisation, and is compatible with the limited DNA available within the early embryo. Using newly established methodology for full retrieval of these two antigens [1] we have reassessed the patterns of expression of 5mC and 5hmC across preimplantation development. Both the male and the female pronuclei show extensive and relatively stable staining of both 5mC and 5hmC across all stages of zygotic maturation. The analysis does not provide support for the oft claimed active global demethylation of the paternally-derived genome relative to that of the maternal-derived genome, and also provide no support for a role of 5hmC as an intermediate in such an active demethylation step. During the cleavage stage of development (2-cell to 8-cell) mC became progressively more associated with heterochromatic regions of the nucleus while 5hmC staining was the dominant modification in euchromatin. By the morulae stage several cells with inner positions in the embryo showed some reduced euchromatic staining of 5hmC and 5mC. Relative to trophectodermal cells, the pluripotent inner cell mass of blastocysts show a marked overall reduction in euchromatic of both 5hmC and 5mC staining, and a progressive reduction of mC staining from heterochromatic foci. The distinctively different landscapes of 5mC and 5hmC on the embryonic genome indicate that these modifications may provide different epigenetic information to the early embryo, and shows that differential changes in this landscape define the first differentiation events in the early embryo. Current claims of extensive remodelling of CpG in the zygote seem to be largely caused by dynamic changes in the conformation of chromatin in early development leading to extensive antigenic masking of these modifications. When this masking is removed a much greater level of stability of these modifications at a global level becomes evident.

Simulation of radio occultation measurements

This paper describes a wave propagator that can be used to simulate radio occultation measurements. The wave propagator is used to simulate a number of radio occultations based on European Centre for Medium-range Weather Forecasts ECMWF atmospheric profiles. The output from the wave propagator is used as input to a Full Spectrum Inversion FSI retrieval module, which calculates geophysical parameters. These parameters are compared to the ECMWF atmospheric profiles. We also compare the output from the wave propagator with that of a 3D ray tracer. Such comparisons can be used to reveal system errors and get a better understanding of the physics of the problem and the retrieval errors in the inversion of radio occultation measurements.

A knowledge-based BIM system for building maintenance

Abstract Decisions for building maintenance require integration of various types of information and knowledge created by different members of construction teams such as: maintenance records, work orders, causes and knock-on effects of failures, etc. Failing to capture and use this information/knowledge results in significant costs due to ineffective decisions. Majority of the current building maintenance systems mainly focus on capturing either information or knowledge. This research aims to develop an integrated system to capture information and knowledge of building maintenance operations when/after maintenance is carried out to understand how a building is deteriorating and to support preventive/corrective maintenance decisions. To develop the system, a number of case studies were investigated and interviews were conducted with professionals from different building maintenance departments in public organisations. This methodology helped identify the building maintenance process and the opportunities for knowledge capture and exchange. A taxonomy for building maintenance was then identified which enabled a formal approach for knowledge capture. The proposed system utilises the functions of information modelling techniques and knowledge systems to facilitate full retrieval of information and knowledge for maintenance work. The system consists of two modules; BIM module to capture relevant information and Case-Based Reasoning (CBR) module to capture knowledge. The system can help maintenance teams learn from previous experience and trace the full history of a building element and all affected elements by previous maintenance operations. It is concluded that the integrated knowledge-based BIM systems can provide advanced useful functions for construction operations. On the other hand, incorporating Knowledge Management principles embedded in CBR systems with Information Management principles embedded in BIM systems is a way forward for the transformation from ‘Building Information Modelling’ to ‘Building Knowledge Modelling’.

Event-related potential variations in the encoding and retrieval of different amounts of contextual information

Episodic memory events occur within multidimensional contexts; however, the electrophysiological manifestations associated with processing of more than one context have been rarely investigated. The effect of the amount of context on the ERPs was studied using two single and one double source memory tasks and by comparing full and partial context retrieval within a double source task. The single source tasks elicited waveforms with a larger amplitude during successful encoding and retrieval than the double source task. Compared with the waveforms elicited with a full source response, a partial source response elicited waveforms with a smaller amplitude, probably because the retrieval success for one context was combined with the retrieval attempt processes for the missing source. Comparing the tasks revealed that the larger the amount of contextual information processed, the smaller the amplitude of the ERPs, indicating that greater effort or further control processes were required during double source retrieval.

The impact of large scale ionospheric structure on radio occultation retrievals

Abstract. We study the impact of large-scale ionospheric structure on the accuracy of radio occultation (RO) retrievals. We use a climatological model of the ionosphere as well as an ionospheric data assimilation model to compare quiet and geomagnetically disturbed conditions. The presence of ionospheric electron density gradients during disturbed conditions increases the physical separation of the two GPS frequencies as the GPS signal traverses the ionosphere and atmosphere. We analyze this effect in detail using ray-tracing and a full geophysical retrieval system. During quiet conditions, our results are similar to previously published studies. The impact of a major ionospheric storm is analyzed using data from the 30 October 2003 "Halloween" superstorm period. At 40 km altitude, the refractivity bias under disturbed conditions is approximately three times larger than quiet time. These results suggest the need for ionospheric monitoring as part of an RO-based climate observation strategy. We find that even during quiet conditions, the magnitude of retrieval bias depends critically on assumed ionospheric electron density structure, which may explain variations in previously published bias estimates that use a variety of assumptions regarding large scale ionospheric structure. We quantify the impact of spacecraft orbit altitude on the magnitude of bending angle and retrieval error. Satellites in higher altitude orbits (700+ km) tend to have lower residual biases due to the tendency of the residual bending to cancel between the top and bottomside ionosphere. Another factor affecting accuracy is the commonly-used assumption that refractive index is unity at the receiver. We conclude with remarks on the implications of this study for long-term climate monitoring using RO.

Retrievals of sulfur dioxide from the Global Ozone Monitoring Experiment 2 (GOME-2) using an optimal estimation approach: Algorithm and initial validation

[1] We apply an optimal estimation algorithm originally developed for retrieving ozone profiles from the Global Ozone Monitoring Experiment (GOME) and the Ozone Monitoring Instrument (OMI) to make global observations of sulfur dioxide from the Global Ozone Monitoring Experiment 2 (GOME-2) on the MetOp-A satellite. Our approach combines a full radiative transfer calculation, retrieval algorithm, and trace gas climatologies to implicitly include the effects of albedo, clouds, ozone, and SO2 profiles in the retrieval. Under volcanic conditions, the algorithm may also be used to directly retrieve SO2 plume altitude. Retrieved SO2 columns over heavy anthropogenic pollution typically agree with those calculated using a two-step slant column and air mass factor approach to within 10%. Retrieval uncertainties are quantified for GOME-2 SO2 amounts; these are dominated by uncertainty contributions from noise, surface albedo, profile shape, correlations with other retrieved parameters, atmospheric temperature, choice of wavelength fitting window, and aerosols. When plume altitudes are also simultaneously retrieved, additional significant uncertainties result from uncertainties in the a priori altitude, the model's vertical layer resolution, and instrument calibration. Retrieved plume height information content is examined using the Mount Kasatochi volcanic plume on 9 August 2008. An a priori altitude of 10 km and uncertainty of 2 km produce degrees of freedom for signal of at least 0.9 for columns >30 Dobson units. GOME-2 estimates of surface SO2 are compared with in situ annual means over North America in 2008 from the Clear Air Status and Trends Network (CASTNET; r = 0.85, N = 65) and Air Quality System (AQS) and National Air Pollution Surveillance (NAPS; r = 0.40, N = 438) networks.

Evaluating subtopic retrieval methods: Clustering versus diversification of search results

To address the inability of current ranking systems to support subtopic retrieval, two main post-processing techniques of search results have been investigated: clustering and diversification. In this paper we present a comparative study of their performance, using a set of complementary evaluation measures that can be applied to both partitions and ranked lists, and two specialized test collections focusing on broad and ambiguous queries, respectively. The main finding of our experiments is that diversification of top hits is more useful for quick coverage of distinct subtopics whereas clustering is better for full retrieval of single subtopics, with a better balance in performance achieved through generating multiple subsets of diverse search results. We also found that there is little scope for improvement over the search engine baseline unless we are interested in strict full-subtopic retrieval, and that search results clustering methods do not perform well on queries with low divergence subtopics, mainly due to the difficulty of generating discriminative cluster labels.

Adaptive regularized filtering for BRDF model inversion and land surface albedo retrieval based on spectrum cutoff technique

A regularized inversion method is presented to invert the bidirectional reflectance distribution function (BRDF) model for albedo calculations. It is known as discrete ill-posed inverse problem. Essential issues that must be considered include solution existence, solution uniqueness, instability of the solution process, and geophysical meanings of solution. In order to robustly estimate BRDF models parameters, a spectrum cutoff technique is employed to suppress spurious oscillations due to poor angular distribution, sparse sample size, or both. We studied difficulties in estimating BRDF parameters and analyzed the cause of the instability in the solution, and then presented a novel algorithm. The proposed RSC (Regularized Spectrum Cutoff) method is based on improving the spectrum of the BRDF kernel matrix and can always find suitable BRDF parameters for sparse satellite observations. The algorithm is compared with the MODIS (Moderate Resolution Imaging Spectroradiometer) full retrieval (FR) algorithm, and it is tested to be suitable for the case of sufficient observations. Numerical experiments with POLDER (Polarization and Directionality of the Earth's Reflectances) BRDF datasets and MODIS images suggest that the developed spectrum cutoff method is adaptive and robust, and it is valuable for retrieving land surface BRDF and albedo.

Current methods for characterising mixing and flow in microchannels

This article reviews existing methods for the characterisation of mixing and flow in microchannels, micromixers and microreactors. In particular, it analyses the current experimental techniques and methods available for characterising mixing and the associated phenomena in single and multiphase flow. The review shows that the majority of the experimental techniques used for characterising mixing and two-phase flow in microchannels employ optical methods, which require optical access to the flow, or off-line measurements. Indeed visual measurements are very important for the fundamental understanding of the physics of these flows and the rapid advances in optical measurement techniques, like confocal scanning laser microscopy and high resolution stereo micro particle image velocimetry, are now making full field data retrieval possible. However, integration of microchannel devices in industrial processes will require on-line measurements for process control that do not necessarily rely on optical techniques. Developments are being made in the areas of non-intrusive sensors, magnetic resonance techniques, ultrasonic spectroscopy and on-line flow through measurement cells. The advances made in these areas will certainly be of increasing interest in the future as microchannels are more frequently employed in continuous flow equipment for industrial applications.

Advances in multidisciplinary treatment of rectal cancer

To summarize the advances in the multidisciplinary treatment of rectal cancer and to analyze the existing problems and development prospects. The full text database retrieval system of MEDLINE and the periodicals of CHKD were searched. The words “rectal cancer, diagnosis, surgery, chemotherapy, radiotherapy, targeted therapy, analysis” were used as key words for retrieval of literature concerning the values and clinical significance of rectal cancer multidisciplinary treatment from January, 2000 to December, 2007. Thirty papers were selected, of which 26 were used in analysis at last. Accurate preoperative staging of rectal cancer is a key factor in the multidisciplinary and comprehensive treatment of patients. A new therapy which is combined with radical operation can reduce the rate of local recurrence, prolong survival time, and particularly, promote the rate of sphincter preservation. Radical surgery combined with adjuvant therapy is still recognized as standard treatment modality for the patients with rectal cancer in stage II-III. Total removal of resectable metastases followed by prompt standard adjuvant therapy may extend survival time. The introduction of new chemical drugs, drugs of targeting therapy, and a regimen of combination therapy may improve outcomes in treatment for rectal cancer patients. A treatment standard for rectal cancer patients needs to be actively pursued. Compared with colon cancer patients, there has not been sufficient evidence to confirm that the total survival rate of rectal cancer patients after multidisciplinary and comprehensive treatments has been improved; therefore, it needs to be further studied.

Study on Bibliographic Database of TCM Periodicals Published in Republic of China

Object Under the premise of protecting periodicals published in Republic of China, these periodicals were processed with digitalization for the purpose of being utilized in a easy way. Methods Oracle 9i database software was used to establish database table structure. Periodicals published in Republic of China were selected, periodicals pictures were processed and the literature subjects were indexed before databases retrieval system of these periodicals was made and published. Results A full text data base retrieval system containing 20 kinds of periodicals published in Republic of China was established, to provide both retrieval from multi-angles and picture browsing of the full text. Conclusion Digitalization technique is a way of reproducible protection and utilization of periodicals published in Republic of China. Key words: TCM Periodicals Published in Republic of China; TCM Literature; Digitalization

Implant Site Development by Orthodontic Extrusion

To determine the effectiveness of orthodontic extrusion of nonrestorable teeth prior to implant placement for improving the alveolar bone and gingival characteristics of implant recipient sites. Electronic database searches of the following databases were conducted with the help of a senior health sciences librarian: Medline, PubMed, EMBASE, Scopus, Web of Science, and CINAHL Plus. Hand searches of the reference lists of selected articles were also conducted. Abstracts that appeared to fulfill the initial selection criteria were selected for full article retrieval. Retrieved articles were then carefully evaluated, and more specific selection criteria were applied. The authors conducted the selection processes independently, and any differences were resolved through discussion. An analysis of timing, type, and magnitude of forces applied was sought. Eighteen articles were considered for review. Most of the selected articles were case reports or case series describing orthodontic extrusion of periodontally hopeless maxillary anterior teeth. The results of the reported cases were evaluated individually and collectively with regard to various hard and soft tissue implant site characteristics. Clinically significant gains in alveolar bone and gingival tissue were reported in all cases, resulting in significant quantitative and qualitative improvements in the implant sites. Based on the available literature, orthodontic extrusion of nonrestorable teeth prior to implant placement appears to be a viable alternative to conventional surgical augmentative procedures in implant site development. No direct comparison to any other method was found, and therefore no conclusion could be made about its relative efficacy.