Showing papers by "Christian Berger published in 2013"

Multi-Modal and Multi-Temporal Data Fusion: Outcome of the 2012 GRSS Data Fusion Contest

Abstract: The 2012 Data Fusion Contest organized by the Data Fusion Technical Committee (DFTC) of the IEEE Geoscience and Remote Sensing Society (GRSS) aimed at investigating the potential use of very high spatial resolution (VHR) multi-modal/multi-temporal image fusion. Three different types of data sets, including spaceborne multi-spectral, spaceborne synthetic aperture radar (SAR), and airborne light detection and ranging (LiDAR) data collected over the downtown San Francisco area were distributed during the Contest. This paper highlights the three awarded research contributions which investigate (i) a new metric to assess urban density (UD) from multi-spectral and LiDAR data, (ii) simulation-based techniques to jointly use SAR and LiDAR data for image interpretation and change detection, and (iii) radiosity methods to improve surface reflectance retrievals of optical data in complex illumination environments. In particular, they demonstrate the usefulness of LiDAR data when fused with optical or SAR data. We believe these interesting investigations will stimulate further research in the related areas.

Competition, Envy, or Snobbism? How Popularity and Friendships Shape Antipathy Networks of Adolescents

Abstract: This study examined how status (popularity) and friendship relations affected the development of adolescents' dislike relations (i.e., antipathy networks) over time. Three competing hypotheses were formulated about the role of status: antipathy relations result from either similarity in status (competition hypothesis) or dissimilarity in status when lower status peers reject higher status peers (envy hypothesis) or vice versa (snobbism hypothesis). Hypotheses were tested in a longitudinal sample of adolescents from Chile (fifth to sixth grade; 52% boys; N=273). Antipathy and friendship networks were examined simultaneously using longitudinal social network modeling (SIENA). Higher status adolescents were more likely to reject their lower status peers, in line with the snobbism hypothesis. Furthermore, best friends tended to agree upon which peers to reject over time.

Long-term live cell imaging and automated 4D analysis of drosophila neuroblast lineages.

Abstract: The developing Drosophila brain is a well-studied model system for neurogenesis and stem cell biology. In the Drosophila central brain, around 200 neural stem cells called neuroblasts undergo repeated rounds of asymmetric cell division. These divisions typically generate a larger self-renewing neuroblast and a smaller ganglion mother cell that undergoes one terminal division to create two differentiating neurons. Although single mitotic divisions of neuroblasts can easily be imaged in real time, the lack of long term imaging procedures has limited the use of neuroblast live imaging for lineage analysis. Here we describe a method that allows live imaging of cultured Drosophila neuroblasts over multiple cell cycles for up to 24 hours. We describe a 4D image analysis protocol that can be used to extract cell cycle times and growth rates from the resulting movies in an automated manner. We use it to perform lineage analysis in type II neuroblasts where clonal analysis has indicated the presence of a transit-amplifying population that potentiates the number of neurons. Indeed, our experiments verify type II lineages and provide quantitative parameters for all cell types in those lineages. As defects in type II neuroblast lineages can result in brain tumor formation, our lineage analysis method will allow more detailed and quantitative analysis of tumorigenesis and asymmetric cell division in the Drosophila brain.

FACS purification of Drosophila larval neuroblasts for next-generation sequencing

Abstract: Elegant tools are available for the genetic analysis of neural stem cell lineages in Drosophila, but a methodology for purifying stem cells and their differentiated progeny for transcriptome analysis is currently missing. Previous attempts to overcome this problem either involved using RNA isolated from whole larval brain tissue or co-transcriptional in vivo mRNA tagging. As both methods have limited cell type specificity, we developed a protocol for the isolation of Drosophila neural stem cells (neuroblasts, NBs) and their differentiated sibling cells by FACS. We dissected larval brains from fly strains expressing GFP under the control of a NB lineage-specific GAL4 line. Upon dissociation, we made use of differences in GFP intensity and cell size to separate NBs and neurons. The resulting cell populations are over 98% pure and can readily be used for live imaging or gene expression analysis. Our method is optimized for neural stem cells, but it can also be applied to other Drosophila cell types. Primary cell suspensions and sorted cell populations can be obtained within 1 d; material for deep-sequencing library preparation can be obtained within 4 d.

Removal of Optically Thick Clouds from Multi-Spectral Satellite Images Using Multi-Frequency SAR Data

Abstract: This study presents a method for the reconstruction of pixels contaminated by optical thick clouds in multi-spectral Landsat images using multi-frequency SAR data. A number of reconstruction techniques have already been proposed in the scientific literature. However, all of the existing techniques have certain limitations. In order to overcome these limitations, we expose the Closest Spectral Fit (CSF) method proposed by Meng et al. to a new, synergistic approach using optical and SAR data. Therefore, the term Closest Feature Vector (CFV) is introduced. The technique facilitates an elegant way to avoid radiometric distortions in the course of image reconstruction. Furthermore the cloud cover removal is independent from underlying land cover types and assumptions on seasonality, etc. The methodology is applied to mono-temporal, multi-frequency SAR data from TerraSAR-X (X-Band), ERS (C-Band) and ALOS Palsar (L-Band). This represents a way of thinking about Radar data not as foreign, but as additional data source in multi-spectral remote sensing. For the assessment of the image restoration performance, an experimental framework is established and a statistical evaluation protocol is designed. The results show the potential of a synergistic usage of multi-spectral and SAR data to overcome the loss of data due to cloud cover.

Neuroblast pattern and identity in the Drosophila tail region and role of doublesex in the survival of sex-specific precursors

Abstract: The central nervous system is composed of segmental units (neuromeres), the size and complexity of which evolved in correspondence to their functional requirements. In Drosophila, neuromeres develop from populations of neural stem cells (neuroblasts) that delaminate from the early embryonic neuroectoderm in a stereotyped spatial and temporal pattern. Pattern units closely resemble the ground state and are rather invariant in thoracic (T1-T3) and anterior abdominal (A1-A7) segments of the embryonic ventral nerve cord. Here, we provide a comprehensive neuroblast map of the terminal abdominal neuromeres A8-A10, which exhibit a progressively derived character. Compared with thoracic and anterior abdominal segments, neuroblast numbers are reduced by 28% in A9 and 66% in A10 and are almost entirely absent in the posterior compartments of these segments. However, all neuroblasts formed exhibit serial homology to their counterparts in more anterior segments and are individually identifiable based on their combinatorial code of marker gene expression, position, delamination time point and the presence of characteristic progeny cells. Furthermore, we traced the embryonic origin and characterised the postembryonic lineages of a set of terminal neuroblasts, which have been previously reported to exhibit sex-specific proliferation behaviour during postembryonic development. We show that the respective sex-specific product of the gene doublesex promotes programmed cell death of these neuroblasts in females, and is needed for their survival, but not proliferation, in males. These data establish the terminal neuromeres as a model for further investigations into the mechanisms controlling segment- and sex-specific patterning in the central nervous system.

Robust Extraction of Urban Land Cover Information From HSR Multi-Spectral and LiDAR Data

Abstract: This paper focuses on the description and demonstration of a simple, but effective object-based image analysis (OBIA) approach to extract urban land cover information from high spatial resolution (HSR) multi-spectral and light detection and ranging (LiDAR) data. Particular emphasis is put on the evaluation of the proposed method with regard to its generalization capabilities across varying situations. For this purpose, the experimental setup of this work includes three urban study areas featuring different physical structures, four sets of HSR optical and LiDAR input data, as well as statistical measures to enable the assessment of classification accuracies and methodological transferability. The results of this study highlight the great potential of the developed approach for accurate, robust and large-area mapping of urban environments. User's and producer's accuracies observed for all maps are almost consistently above 80%, in many cases even above 90%. Only few larger class-specific errors occur mainly due to the simple assumptions on which the method is based. The presented feature extraction workflow can therefore be used as a template or starting point in the framework of future urban land cover mapping efforts.

Abdominal-B and caudal inhibit the formation of specific neuroblasts in the Drosophila tail region

Abstract: The central nervous system of Drosophila melanogaster consists of fused segmental units (neuromeres), each generated by a characteristic number of neural stem cells (neuroblasts). In the embryo, thoracic and anterior abdominal neuromeres are almost equally sized and formed by repetitive sets of neuroblasts, whereas the terminal abdominal neuromeres are generated by significantly smaller populations of progenitor cells. Here we investigated the role of the Hox gene Abdominal-B in shaping the terminal neuromeres. We show that the regulatory isoform of Abdominal-B (Abd-B.r) not only confers abdominal fate to specific neuroblasts (e.g. NB6-4) and regulates programmed cell death of several progeny cells within certain neuroblast lineages (e.g. NB3-3) in parasegment 14, but also inhibits the formation of a specific set of neuroblasts in parasegment 15 (including NB7-3). We further show that Abd-B.r requires cooperation of the ParaHox gene caudal to unfold its full competence concerning neuroblast inhibition and specification. Thus, our findings demonstrate that combined action of Abdominal-B and caudal contributes to the size and composition of the terminal neuromeres by regulating both the number and lineages of specific neuroblasts.

Graph-Based Mapping of Urban Structure Types From High-Resolution Satellite Image Objects—Case Study of the German Cities Rostock and Erfurt

Abstract: Ongoing urbanization processes have increased the demand for monitoring, controlling, and modeling services, with urban structure types as an initial interest. While urban land cover (LC) can be derived directly from high-resolution satellite images, urban land use (LU) is achieved through analyzing a combination of structural, functional, spatial, morphological, and topological attributes of the various LC classes. The objective of this letter is to distinguish urban LU classes on the basis of distances between buildings incorporated into a graph-based concept. The method was developed using cadastral data (ALK) for the German city of Rostock, then applied to the LC building objects derived from Quickbird data. Building distribution was examined and distances between buildings were used as an attribute for graph generation. Two graph measures (beta index, clustering coefficient) were analyzed resulting in two groups of LU categories. Transferability to a different urban area was tested without adaptions. Similar building distribution and LC extraction quality were found to be crucial for transferability tests. Distances between buildings are an important property for deriving LU classes, but should be accompanied by additional LC attributes to improve LU separability.

Local Interpolation-based Polar Format SAR: Algorithm, Hardware Implementation and Design Automation

Abstract: In this paper we present a local interpolation-based variant of the well-known polar format algorithm used for synthetic aperture radar (SAR) image formation. We develop the algorithm to match the capabilities of the application-specific logic-in-memory processing paradigm, which off-loads lightweight computation directly into the SRAM and DRAM. Our proposed algorithm performs filtering, an image perspective transformation, and a local 2D interpolation, and supports partial and low-resolution reconstruction. We implement our customized SAR grid interpolation logic-in-memory hardware in advanced 14 nm silicon technology. Our high-level design tools allow to instantiate various optimized design choices to fit image processing and hardware needs of application designers. Our simulation results show that the logic-in-memory approach has the potential to enable substantial improvements in energy efficiency without sacrificing image quality.

Aprendizaje socioemocional en estudiantes de quinto y sexto grado: presentación y evaluación de impacto del programa BASE

Abstract: Se presenta el desarrollo y evaluacion de impacto de un programa para favorecer el bienestar y aprendizaje socioemocional en estudiantes de quinto y sexto ano de ensenanza general basica: el programa BASE. A partir de una revision teorica del aprendizaje socioemocional se fundamenta el enfasis del programa en el desarrollo de vinculos interpersonales de calidad y el desarrollo de las competencias necesarias para ello, integrando tanto factores a nivel del desarrollo individual como tambien del contexto que favorece este desarrollo, asi como la generacion de comunidades sanas y nutritivas. Se utilizo un diseno cuasi-experimental pre-post con grupo control para evaluar el impacto del programa. Los resultados muestran un impacto significativo positivo del programa en la autoestima, integracion social, y percepcion del clima escolar de los estudiantes que participaron de el en comparacion al grupo control. Se discuten los resultados del programa y sus posibles implicancias para el desarrollo de intervenciones en este campo.

Method and apparatus for estimating statistics in wireless systems

Abstract: Systems and methods are provided for processing a signal using simplified channel statistics. In an example implementation, a channel profile for a multipath channel is estimated by detecting, within a given range, a number of channel taps associated with a channel impulse response, and assigning each of those channel taps a uniform amplitude value corresponding to a constant signal strength. A signal may be received through the multipath channel and filtered based on the estimated channel profile.

Aprendizagem socioemocional em estudantes de quinta e sexta serie: apresentação e avaliação de impacto do programa BASE

Abstract: This article presents the development and impact evaluation of a program to enhance the wellbeing and socioemotional learning of 5th and 6th graders: The BASE program. Based on the theoretical framework of socioemotional learning, the emphasis of the program is oriented towards fostering quality interpersonal bounds and the development of competencies that are necessary for this, integrating both individual and contextual factors and the generation of healthy and nurturing communities. The study features a quasi-experimental pre-post design with a control group in order to assess the impact of the program. Results show a significant positive effect on self-esteem, social integration, and the perception of the school social climate of students who were part of the program, compared to their counterparts in the control group. These results are discussed in light of their potential implications for future educational interventions.

Method and apparatus for estimating noise covariance in a wireless network

Abstract: The present disclosure includes systems and techniques relating to processing received spatially diverse transmissions. In some implementations, an apparatus includes: circuitry configured to receive signals from separate communication inputs; circuitry configured to filter the signals to reduce noise, interference, or both; circuitry configured to estimate covariance of the separate communication inputs, including estimating a correlation between the separate communication inputs; and circuitry configured to apply the covariance estimation to the filtering circuitry to effect noise whitening and to force an underestimation of the correlation between the separate communication inputs as applied.

Channel processing with dedicated pilots utilizing information from broadcast pilots

Abstract: Systems, methods, and other embodiments associated with channel processing with dedicated pilots utilizing information from broadcast pilots are described. According to one embodiment, an method includes receiving, through a channel, i) a signal resource block that includes data and a dedicated pilot that is precoded and ii) at least one broadcast pilot that is not precoded. A channel property is deduced from the broadcast pilot; and the channel is processed by applying the channel property to the dedicated pilot. In one embodiment, the method includes estimating an effective channel by applying the channel property to the dedicated pilot.