Fallen fragment sign

A 16-year-old boy presented at the emergency room after he fell on his left shoulder while playing American football. Plain radiographs showed a pathological fracture through a well- defined expansile radiolucent lesion within the proximal meta-diaphysis of the left humerus (Fig. A). The lesion caused cortical thinning and contained multiple linear cortical fragments within the central part of the lesion (arrows in Fig. A). Based on the age, location and the plain radiographic characteristics (“fallen fragment sign”), the diagnosis of a solitary bone cyst (SBC) was suggested

Space-Time Chip Equalization for Maximum Diversity Space-Time Block Coded DS-CDMA Downlink Transmission

In the downlink of DS-CDMA, frequency-selectivity destroys the orthogonality of the user signals and introduces multiuser interference (MUI). Space-time chip equalization is an efficient tool to restore the orthogonality of the user signals and suppress the MUI. Furthermore, multiple-input multiple-output (MIMO) communication techniques can result in a significant increase in capacity. This paper focuses on space-time block coding (STBC) techniques, and aims at combining STBC techniques with the original single-antenna DS-CDMA downlink scheme. This results into the so-called space-time block coded DS-CDMA downlink schemes, many of which have been presented in the past. We focus on a new scheme that enables both the maximum multiantenna diversity and the maximum multipath diversity. Although this maximum diversity can only be collected by maximum likelihood (ML) detection, we pursue suboptimal detection by means of space-time chip equalization, which lowers the computational complexity significantly. To design the space-time chip equalizers, we also propose efficient pilot-based methods. Simulation results show improved performance over the space-time RAKE receiver for the space-time block coded DS-CDMA downlink schemes that have been proposed for the UMTS and IS-2000 W-CDMA standards.Electrical Engineering, Mathematics and Computer Scienc

Multicarrier Block-Spread CDMA for Broadband Cellular Downlink

Effective suppression of multiuser interference (MUI) and mitigation of frequency-selective fading effects within the complexity constraints of the mobile constitute major challenges for broadband cellular downlink transceiver design. Existing wideband direct-sequence (DS) code division multiple access (CDMA) transceivers suppress MUI statistically by restoring the orthogonality among users at the receiver. However, they call for receive diversity and multichannel equalization to improve the fading effects caused by deep channel fades. Relying on redundant block spreading and linear precoding, we design a so-called multicarrier block-spread- (MCBS-)CDMA transceiver that preserves the orthogonality among users and guarantees symbol detection, regardless of the underlying frequency-selective fading channels. These properties allow for deterministic MUI elimination through low-complexity block despreading and enable full diversity gains, irrespective of the system load. Different options to perform equalization and decoding, either jointly or separately, strike the trade-off between performance and complexity. To improve the performance over multi-input multi-output (MIMO) multipath fading channels, our MCBS-CDMA transceiver combines well with space-time block-coding (STBC) techniques, to exploit both multiantenna and multipath diversity gains, irrespective of the system load. Simulation results demonstrate the superior performance of MCBS-CDMA compared to competing alternatives.Electrical Engineering, Mathematics and Computer Scienc

Iterated exaptation

This volume focuses on detailed studies of various aspects of Construction Morphology, and combines theoretical analysis and descriptive detail.status: publishe

Corpora and historical linguistics Corpora e linguística histórica

The present article aims to survey and assess the current state of electronic historical corpora and corpus methodology, and attempts to look into possible future developments. It highlights the fact that within the wide spectrum of corpus linguistic methodology, historical corpus linguistics has emerged as a vibrant field that has significantly added to the appeal felt for the study of language history and change. In fact, according to a historical linguist with more than fifty years of experience, "[w]e could even go as far as to say that without the support and new impetus provided by corpora, evidence-based historical linguistics would have been close to the end of its life-span in these days of rapid-changing life and research, increasing competition on the academic career track and the methodological attractions offered to young scholars" (RISSANEN, forthcoming). Historical corpora and other electronic resources have also made the study of language history attractive: working on them engages students in an individual and interactive way that they find appealing (CURZAN 2000, p. 81).<br>Este artigo objetiva fazer um levantamento e avaliar o estado da arte dos corpora históricos eletrônicos e da metodologia de estudos de corpora, assim como sugerir possíveis desenvolvimentos futuros na área. Destaca-se que dentro do espectro metodológico da linguística de corpus, a linguística de corpus histórica emergiu como um campo de investigação vibrante que tem adicionado interesse ao estudo da história e da mudança linguística. De acordo com um pesquisador da área com mais de cinqüenta anos de experiência, "pode-se dizer que sem o apoio e o novo ímpeto trazidos pelos corpora, a linguística histórica baseada em evidências teria estado próxima ao fim de sua vida nesses tempos de rápidas mudanças de vida e de pesquisa, aumentando a competição na carreira acadêmica e nas atrações metodológicas oferecidas aos jovens pesquisadores (RISSANEN, no prelo). Corpora históricos e outros recursos eletrônicos têm também tornado o estudo da história da língua atraente: eles engajam a atenção dos estudantes tanto de forma individual quanto interativa (CURZAN 2000, p. 81)