110 research outputs found
Low-Rank Subspace Override for Unsupervised Domain Adaptation
Current supervised learning models cannot generalize well across domain
boundaries, which is a known problem in many applications, such as robotics or
visual classification. Domain adaptation methods are used to improve these
generalization properties. However, these techniques suffer either from being
restricted to a particular task, such as visual adaptation, require a lot of
computational time and data, which is not always guaranteed, have complex
parameterization, or expensive optimization procedures. In this work, we
present an approach that requires only a well-chosen snapshot of data to find a
single domain invariant subspace. The subspace is calculated in closed form and
overrides domain structures, which makes it fast and stable in
parameterization. By employing low-rank techniques, we emphasize on descriptive
characteristics of data. The presented idea is evaluated on various domain
adaptation tasks such as text and image classification against state of the art
domain adaptation approaches and achieves remarkable performance across all
tasks
"Pi of the Sky" - all-sky, real-time search for fast optical transients
An apparatus to search for optical flashes in the sky is described. It has
been optimized for gamma ray bursts (GRB) optical counterparts. It consists of
2x16 cameras covering all the sky. The sky is monitored continuously and the
data are analysed on-line. It has self-triggering capability and can react to
external triggers with negative delay. The prototype with two cameras has been
installed at Las Campanas (Chile) and is operational from July 2004. The paper
presents general idea and describes the apparatus in detail. Performance of the
prototype is briefly reviewed and perspectives for the future are outlined
3D time series analysis of cell shape using Laplacian approaches
Background:
Fundamental cellular processes such as cell movement, division or food uptake critically depend on cells being able to change shape. Fast acquisition of three-dimensional image time series has now become possible, but we lack efficient tools for analysing shape deformations in order to understand the real three-dimensional nature of shape changes.
Results:
We present a framework for 3D+time cell shape analysis. The main contribution is three-fold: First, we develop a fast, automatic random walker method for cell segmentation. Second, a novel topology fixing method is proposed to fix segmented binary volumes without spherical topology. Third, we show that algorithms used for each individual step of the analysis pipeline (cell segmentation, topology fixing, spherical parameterization, and shape representation) are closely related to the Laplacian operator. The framework is applied to the shape analysis of neutrophil cells.
Conclusions:
The method we propose for cell segmentation is faster than the traditional random walker method or the level set method, and performs better on 3D time-series of neutrophil cells, which are comparatively noisy as stacks have to be acquired fast enough to account for cell motion. Our method for topology fixing outperforms the tools provided by SPHARM-MAT and SPHARM-PDM in terms of their successful fixing rates. The different tasks in the presented pipeline for 3D+time shape analysis of cells can be solved using Laplacian approaches, opening the possibility of eventually combining individual steps in order to speed up computations
Active target TPC for study of photonuclear reactions at astrophysical energies
A setup designed to study photonuclear reactions at astrophysical energies -
an active target Time Projection Chamber was developed and constructed at the
Faculty of Physics, University of Warsaw. The device was successfully employed
in two experiments at the Institute of Nuclear Physics Polish Academy of
Sciences in Cracow, in which {\gamma}- and neutron-induced reactions with CO2
gas target were measured. The reaction products were detected and their momenta
reconstructed. Preliminary results are shown.Comment: Presented at Zakopane Conference on Nuclear Physics 202
The SERRATE protein is involved in alternative splicing in <em>Arabidopsis thaliana</em>
Howalternative splicing (AS) is regulated in plants has not yet been elucidated. Previously, we have shown that the nuclear cap-binding protein complex (AtCBC) is involved in AS in Arabidopsis thaliana. Here we show that both subunits of AtCBC (AtCBP20 and AtCBP80) interact with SERRATE (AtSE), a protein involved in the microRNA biogenesis pathway. Moreover, using a high-resolution reverse transcript-ase-polymerase chain reaction AS system we have found that AtSE influences AS in a similar way to the cap-binding complex (CBC), preferentially affecting selection of 50 splice site of first introns. The AtSE protein acts in cooperation with AtCBC: many changes observed in the mutant lacking the correct SERRATE activity were common to those observed in the cbp mutants. Interestingly, significant changes in AS of some genes were also observed in other mutants of plant microRNA biogenesis pathway, hyl1-2 and dcl1-7, but a majority of them did not cor-respond to the changes observed in the se-1mutant. Thus, the role of SERRATE in AS regulation is distinct from that of HYL1andDCL1, and is similar to the regu-lation of AS in which CBC is involved
Electronic system of the RPC Muon Trigger in CMS experiment at LHC accelerator (Elektroniczny system trygera mionowego RPC w eksperymencie CMS akceleratora LHC
This paper presents implementation of distributed, multichannel electronic measurement system for RPC - based Muon Trigger in the CMS experiment at LHC. The introduction shortly describes the research aims of LHC and shows the metrological requirements for CMS - good spatial and time resolution, and possibility to estimate multiple physical parameters from registered collisions of particles. Further the paper describes RPC Muon Trigger consisting of 200 000 independent channels for position measurement. The first part of the paper presents the functional structure of the system in the context of requirements put by the CMS experiment, like global triggering system and data acquisition. The second part describes the hardware solutions used in particular parts of the RPC detector measuremnt system and shows some test results. The paper has a digest and overview nature
An RPC-based Technical Trigger for the CMS Experiment
In the CMS experiment, sub-detectors may send special trigger signals, called "Technical Triggers", for special purposes like test and calibration. The Resistive Plate Chambers are part of the Muon Trigger System of the experiment, but might also produce a cosmic muon trigger as Technical Trigger to be used during the commissioning to the detectors, the CMS magnet Test Cosmic Challenge and the later running of CMS. The proposed implementation is based on the development of a new board, the RBC Balcony Collector (RBC); the test results on prototypes and their performance during the recent CMS Cosmic Challenge are presented
First measurements of the performance of the Barrel RPC system in CMS
During the summer 2006, a first integrated test of a part of the CMS experiment was performed at CERN collecting a data sample of several millions of cosmic rays events. A fraction of the Resistive Plate Chambers system was successfully operated. Results on the RPC performance are reported
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