A Critical Examination Of Connectionist Cognitive Architectures

The dissertation represents a critical evaluation of the major connectionist theories of human cognitive architecture. The central connectionist thesis that artificial neural networks (ANNs) can serve as finitary models of human cognizers is examined and rejected. Connectionist theories, in contrast to the classical symbol-processing theories of cognitive architecture, cannot explain the productivity and systematicity of mental states. The reason for this is that ANN-based cognitive architectures cannot maintain representational states with compositional structure. Chapter One analyzes the implementational connectionism\u27s solution to the problem of compositionality. It is shown that neither the theory of weak nor of strong compositionality can solve this problem.;Chapter Two criticises the attempt to establish connectionism as an alternative theory of human cognitive architecture through the introduction of the symbolic/subsymbolic distinction. The reasons for the introduction of this distinction are examined and found to be unconvincing. Several experimental comparisons between the TDIDT class of symbolic learning systems and the class of artificial neural networks using the error backpropagation algorithm are discussed. It is argued that the differences in the performance of these two classes of learning systems are insignificant and are not systematic. Such evidence contradicts the view that ANNs define a new kind of subsymbolic computation.;Supporters of eliminative connectionism have argued for a pattern association and pattern recognition-based explanation of cognitive processes. They deny that explicit rules and symbolic representations play any role in cognition. Their argument is based to a large extent on Rumelhart and McClelland\u27s and MacWhinney and Leinbach\u27s connectionist models of learning of the past tenses of English verbs. Chapter Three presents an analysis of an experimental comparison between these models and the Symbolic Pattern Associator (SPA)--a learning system based on the classical architecture. It is shown that the SPA outperforms the connectionist models; moreover, the SPA can represent the acquired knowledge in the form of explicit rules. The analysis of this comparison leads to the conclusion that symbol-processing models have a far better chance of explaining complex cognitive phenomena in terms of rules and symbolic representations than eliminative connectionism

Republication: Targeting PI3KC2β Impairs Proliferation and Survival in Acute Leukemia, Brain Tumours and Neuroendocrine Tumours

BACKGROUND Eight human catalytic phosphoinositide 3-kinase (PI3K) isoforms exist which are subdivided into three classes. While class I isoforms have been well-studied in cancer, little is known about the functions of class II PI3Ks. MATERIALS AND METHODS The expression pattern and functions of the class II PI3KC2β isoform were investigated in a panel of tumour samples and cell lines. RESULTS Overexpression of PI3KC2β was found in subsets of tumours and cell lines from acute myeloid leukemia (AML), glioblastoma multiforme (GBM), medulloblastoma (MB), neuroblastoma (NB), and small cell lung cancer (SCLC). Specific pharmacological inhibitors of PI3KC2β or RNA interference impaired proliferation of a panel of human cancer cell lines and primary cultures. Inhibition of PI3KC2β also induced apoptosis and sensitised the cancer cells to chemotherapeutic agents. CONCLUSION Together, these data show that PI3KC2β contributes to proliferation and survival in AML, brain tumours and neuroendocrine tumours, and may represent a novel target in these malignancies

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

Peer reviewe

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

CMS Data Processing Workflows during an Extended Cosmic Ray Run

Peer reviewe

Aligning the CMS Muon Chambers with the Muon Alignment System during an Extended Cosmic Ray Run

Peer reviewe

Commissioning and performance of the CMS silicon strip tracker with cosmic ray muons

This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOPDuring autumn 2008, the Silicon Strip Tracker was operated with the full CMS experiment in a comprehensive test, in the presence of the 3.8 T magnetic field produced by the CMS superconducting solenoid. Cosmic ray muons were detected in the muon chambers and used to trigger the readout of all CMS sub-detectors. About 15 million events with a muon in the tracker were collected. The efficiency of hit and track reconstruction were measured to be higher than 99% and consistent with expectations from Monte Carlo simulation. This article details the commissioning and performance of the Silicon Strip Tracker with cosmic ray muons.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Alignment of the CMS silicon tracker during commissioning with cosmic rays

The CMS silicon tracker, consisting of 1440 silicon pixel and 15 148 silicon strip detector modules, has been aligned using more than three million cosmic ray charged particles, with additional information from optical surveys. The positions of the modules were determined with respect to cosmic ray trajectories to an average precision of 3-4 microns RMS in the barrel and 3-14 microns RMS in the endcap in the most sensitive coordinate. The results have been validated by several studies, including laser beam cross-checks, track fit self-consistency, track residuals in overlapping module regions, and track parameter resolution, and are compared with predictions obtained from simulation. Correlated systematic effects have been investigated. The track parameter resolutions obtained with this alignment are close to the design performance