New Approach for Unambiguous High-Resolution Wide-Swath SAR Imaging

The high-resolution wide-swath (HRWS) SAR system uses a small antenna for transmitting waveform and multiple antennas both in elevation and azimuth for receiving echoes. It has the potential to achieve wide spatial coverage and fine azimuth resolution, while it suffers from elevation pattern loss caused by the presence of topographic height and impaired azimuth resolution caused by nonuniform sampling. A new approach for HRWS SAR imaging based on compressed sensing (CS) is introduced. The data after range compression of multiple elevation apertures are used to estimate direction of arrival (DOA) of targets via CS, and the adaptive digital beamforming in elevation is achieved accordingly, which avoids the pattern loss of scan-on-receive (SCORE) algorithm when topographic height exists. The effective phase centers of the system are nonuniformly distributed when displaced phase center antenna (DPCA) technology is adopted, which causes Doppler ambiguities under traditional SAR imaging algorithms. Azimuth reconstruction based on CS can resolve this problem via precisely modeling the nonuniform sampling. Validation with simulations and experiment in an anechoic chamber are presented

Managing uncertainty in emerging economies:The interaction effects between causation and effectuation on firm performance

International audienceCausation and effectuation are acknowledged as two fundamental strategic decision-making logics that firms use to form strategies to cope with uncertainty. Using data collected from 312 software firms in an emerging economy, we explore the effects of causation and effectuation on firm performance. In addition, we investigate the contingent interaction effects between causation and effectuation on firm performance from the perspective of organizational ambidexterity. We find that (1) causation and effectuation have a positive interaction effect on firm performance when environmental uncertainty is (relatively) high, but have a negative interaction effect on firm performance when environmental uncertainty is (relatively) low; (2) causation has a positive effect on firm performance in emerging economies; and (3) effectuation has a positive effect on firm performance in emerging economies when environmental uncertainty is (relatively) high. Our findings suggest entrepreneurial firms in emerging economies use a combination of causation and effectuation in a more uncertain environment, and adopt causation as a priority in a less uncertain environment

VASCULAR LYMPHATIC MALFORMATION WITH UNCOMMON LOCALIZATION

Introdução: As malformações vasculares linfáticas são entidades raras que afetam os vasos linfáticos. Os autores relatam um caso clínico de uma malformação linfática abdomino-pélvica. Caso Clínico: 28 anos, Gesta 2, Para 1. Encaminhada à Unidade de Diagnóstico Pré-Natal, às 20 semanas, por imagem ecográfica sugestiva de malformação linfática abdomino-pélvica, confirmada por ressonância magnética fetal. Estudo citogenético fetal normal. Consulta de Cirurgia Pediátrica para informar o casal do prognóstico. Cesariana eletiva às 38 semanas. Observação do recém-nascido confirmou o diagnóstico pré-natal. A criança foi submetida, aos 18 meses, a esclerote¬rapia intralesional. Aos 4 anos, foi efetuada exérese cirúrgica da lesão por desenvolvimento de sintomas. Apresentou sempre desenvolvimento e crescimento normais. Discussão/Conclusões: O diagnóstico pré-natal é ecográfico; a ressonância magnética fetal permite confirmar o diagnóstico e define com maior rigor a extensão das lesões. Deve manter-se vigilância clínica e ecográfica, para deteção de sinais de descompensação ou hidrópsia e de compressão das estruturas adjacentes

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

MIMO SAR Using Orthogonal Coding: Design, Performance Analysis, and Verifications

Multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) is a promising technology in radar imaging which provides a better balance of azimuth resolution and swath width compared with traditional single-input single-output (SISO) SAR. It has the potential to help scientists and engineers to design ambitious SAR system with higher resolution and wider swath. This paper studies the principle of MIMO SAR using orthogonal coding waveform and then provides the performance analysis in resolution and swath width. By using orthogonal coding waveform, lower channel interference is obtained, which makes MIMO SAR achieve wider unambiguous range swath and lower azimuth ambiguity. Simulations are carried out by means of the system parameters of real spaceborne SAR platform. A ground-based MIMO SAR imaging system with up and down chirp modulation is also designed. The performances of MIMO SAR and SISO SAR are compared, and the validity and advantage of MIMO SAR are verified

An On-Demand Retrieval Method Based on Hybrid NoSQL for Multi-Layer Image Tiles in Disaster Reduction Visualization

Monitoring, response, mitigation and damage assessment of disasters places a wide variety of demands on the spatial and temporal resolutions of remote sensing images. Images are divided into tile pyramids by data sources or resolutions and published as independent image services for visualization. A disaster-affected area is commonly covered by multiple image layers to express hierarchical surface information, which generates a large amount of namesake tiles from different layers that overlay the same location. The traditional tile retrieval method for visualization cannot distinguish between distinct layers and traverses all image datasets for each tile query. This process produces redundant queries and invalid access that can seriously affect the visualization performance of clients, servers and network transmission. This paper proposes an on-demand retrieval method for multi-layer images and defines semantic annotations to enrich the description of each dataset. By matching visualization demands with the semantic information of datasets, this method automatically filters inappropriate layers and finds the most suitable layer for the final tile query. The design and implementation are based on a two-layer NoSQL database architecture that provides scheduling optimization and concurrent processing capability. The experimental results reflect the effectiveness and stability of the approach for multi-layer retrieval in disaster reduction visualization

Entrepreneurial bricolage and its effects on new venture growth and adaptiveness in an emerging economy

International audienceDriven by solid economic developments, emerging economies are experiencing significant institutional change, particularly in regulatory structures and market systems. Coupled with fierce market competition and reforms, serious challenges for the sustainable development of new ventures are created due to smallness and newness liabilities. This study examines how new ventures grow and adapt to the rapid environmental shifts in emerging economies by exploring the effects of entrepreneurial bricolage. This study found that entrepreneurial bricolage has a positive impact on both new venture growth and adaptiveness. Further, institutional voids have contrasting effects on these two relationships. The effectiveness of entrepreneurial bricolage on new venture growth is stronger in a context with serious institutional voids, while the effectiveness of entrepreneurial bricolage on new venture adaptiveness is weaker in a context with serious institutional voids. These findings not only enrich our knowledge on the implications of entrepreneurial bricolage, but also advance our understanding of the emerging economy context

Quantifying Disaster Physical Damage Using Remote Sensing Data—A Technical Work Flow and Case Study of the 2014 Ludian Earthquake in China

Abstract Disaster damage assessment is an important basis for the objective assessment of the social impacts of disasters and for the planning of recovery and reconstruction. It is also an important research field with regard to disaster mitigation and risk management. Quantitative assessment of physical damage refers to the determination of the physical damage state of the exposed elements in a disaster area, reflecting the aggregate quantities of damages. It plays a key role in the comprehensive damage assessment of major natural hazard-induced disasters. The National Disaster Reduction Center of China has established a technical work flow for the quantitative assessment of disaster physical damage using remote sensing data. This article presents a quantitative assessment index system and method that can be integrated with high-resolution remote sensing data, basic geographical data, and field survey data. Following the 2014 Ludian Earthquake in Yunnan Province, China, this work flow was used to assess the damage to buildings, roads, and agricultural and forest resources, and the assessment results were incorporated into the Disaster Damage Comprehensive Assessment Report of the 2014 Ludian Earthquake for the State Council of China. This article also outlines some possible improvements that can be addressed in future work

Risk factors of recurrence for resected T1aN0M0 invasive lung adenocarcinoma: a clinicopathologic study of 177 patients

Background: This study aimed at identifying risk factors of recurrence for completely resected pathologic T1aN0M0 lung adenocarcinomas. Methods: We reviewed the records of 177 T1aN0M0 invasive adenocarcinoma patients, and re-classified achieved surgical specimens according to the new International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS) lung adenocarcinoma classification. Impact on recurrence-free survival (RFS) for age, gender, smoking history, lymphovascular invasion (LVI) and new classification was analyzed by log-rank test and Cox regression. Two existing prognostic grouping schemes of new classification were compared, and subsequently, the correlation of high-grade group in the better prognostic grouping model with clinical data was investigated statistically. Results: The 5-year recurrence-free rate was 83.7%. The LVI and new adenocarcinoma classification were significantly associated with 5-year RFS (P = 0.012; P = 0.022, respectively). The designation of papillary predominant subtype in the low-grade group, along with lepidic-and acinar predominant subtype had more prognostic significance than the model of combining papillary-, solid- and micropapillary predominant subtypes as the high-grade group (P = 0.005 versus P = 0.181). This high-grade group has increased risk of recurrence in a multivariate Cox regression (adjusted HR 2.815, 95% CI: 1.239 to 6.397, P = 0.013), and is associated significantly more with male gender (adjusted OR 2.214, 95% CI: 1.050 to 4.668, P = 0.037), and, with borderline significance, the presence of LVI (adjusted OR 2.091, 95% CI: 0.938 to 4.662, P = 0.071). Conclusions: Our results showed that the solid-and micropapillary predominant subtype of IASLC/ATS/ERS classification remains the only risk factor for post-operative recurrence of T1aN0M0 adenocarcinomas, suggesting that they can be indicators of aggressive tumor behaviors.OncologySurgerySCI(E)PubMed中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)[email protected]