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R Fallows,
K McCoy,
J Hertza,
E Klosson,
B Estes,
I Stroescu,
Cm Salinas,
A Stringer,
S. Aronson,
W Macallister, [......],
T White,
J Gold,
A Vincent,
T Roebuck-Spencer,
A Bowles,
K Gilliland,
A Watts,
F Ahmed,
A Yon,
B Gordon
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ABSTRACT: Objective: The seminal paper on cerebellar cognitive affective syndrome by Schmahmann and Sherman (1998), and subsequent studies, has expanded our understanding of the role of the cerebellum beyond motor functioning to psychological and cognitive functioning. However, many of these studies have examined patients between 1 week and 5 years post-injury and have tended to exclude patients with prior neurological injuries. Thus, the objective of this case study was to examine cerebellar injury in the context of remote traumatic brain injury (TBI) and describe the long-term cognitive, psychological, and psychosocial sequelae of injury in a 33-year-old, right-handed, Caucasian veteran (S.M.). Method: At age 23, S.M. was referred for neuroimaging by psychiatry due to concern that a TBI from age 16 was the cause of recent onset aggressive behavior. Multiple neuroimaging studies showed no neuroanatomical sequelae of TBI, but revealed a right cerebellar arteriovenous malformation (AVM). Embolization resulted in >50% removal of the AVM, but uncovered an intranidal aneurysm. Repeat neuroimaging revealed a large hemorrhage within the cerebellum with the mass effect and hydrocephalus; subsequent treatment resulted in a complicated 5-month hospital stay. Results: Neuropsychological evaluation conducted 10 years after injury revealed deficits in basic attention, working memory, and information processing speed with relatively intact executive functioning and memory. Physical deficits, including ataxia, dysarthria, and spasticity, and psychological difficulties, including impulsivity and low frustration tolerance, were more prominent and caused significant psychosocial distress, impacting interpersonal relationships. Conclusions: This case highlights the cognitive residual of cerebellar injury and the potential long-term impact on psychological and social functioning.
Archives of Clinical Neuropsychology 09/2011; 26(6):470-567. · 2.18 Impact Factor
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ABSTRACT: The IETF has chartered a Virtual World Region Agent Protocol Working Group (VWRAP WG). This article briefly describes the history of virtual worlds, the architecture, protocols, and operation of Second Life (a currently prominent virtual world), and the emergence of standards efforts within the virtual world space. The authors detail the current efforts and timeline of the VWRAP WG.
IEEE Internet Computing 03/2010; · 2.00 Impact Factor
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ABSTRACT: Phased array antennas have and will continue to be a critically important component in the development of future wireless systems with applications in communications, radar, and satellite technologies. In spite of the significant advances in the design of modern phased array antennas, there continue to be significant and growing need for developing high performance systems that are also low cost and with beam steering capabilities. In this paper we describe some of the antenna array designs that focus on achieving this goal. We will start with one approach that is based on an analog phase-shifting approach and involves an integrated use of ferroelectric materials and the Continuous Transverse Stub (CTS) antenna array technologies. A complementary design which is based on digital beamforming and the utilization of the Hybrid Smart Antenna technique recently developed by our group will then be described. This will be followed with comments regarding the trade-off between the analog and digital phase shifting techniques. We will conclude the chapter with a description of a novel ultra-wideband and low profile ground plane which is based on a hybrid ferrite and Electromagnetic Band Gap (EBG) materials design. In all cases simulation results and experimental validation, whenever available, will be presented and aspects of the required future work to fully enable these technologies will be discussed.
Microwaves, Communications, Antennas and Electronics Systems, 2009. COMCAS 2009. IEEE International Conference on; 12/2009
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ABSTRACT: In this paper, the preliminary design and evaluation of a real time underwater 3D reconstruction system using multiple sonar views from an acoustic camera are presented. The proposed system which is called Acoustic Stereo Imaging (ASI) consists of two relatively inexpensive acoustic sensors situated above each other with known distance (D) between them. The acoustic sensors are multi-beam, high resolution sonars like the ProViewerE P900E-20 sonar and DIDSON sonar. The problem to solve is very similar to stereo vision in classic video camera systems. The ASI Vertical configuration consists of two sonars situated above each other and assumes that all beams of the first sonar are aligned with the corresponding beams in the second sonar. In this configuration, we have derived the ASI geometry which solves the well known correspondence problem in classical video stereo systems.
OCEANS 2009 - EUROPE; 06/2009
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ABSTRACT: Mine-like object classification from sidescan sonar images is of great interest for mine counter measure (MCM) operations. Because the shadow cast by an object is often the most distinct feature of a sidescan image, a standard procedure is to perform classification based on features extracted from the shadow. The classification can then be performed by extracting features from the shadow and comparing this to training data to determine the object. In this paper, a superellipse fitting approach to classifying mine-like objects in sidescan sonar images is presented. Superellipses provide a compact and efficient way of representing different mine-like shapes. Through variation of a simple parameter of the superellipse function different shapes such as ellipses, rhomboids, and rectangles can be easily generated. This paper proposes a classification of the shape based directly on a parameter of the superellipse known as the squareness parameter. The first step in this procedure extracts the contour of the shadow given by an unsupervised Markovian segmentation algorithm. Afterwards, a superellipse is fitted by minimizing the Euclidean distance between points on the shadow contour and the superellipse. As the term being minimized is nonlinear, a closed-form solution is not available. Hence, the parameters of the superellipse are estimated by the Nelder-Mead simplex technique. The method was then applied to sidescan data to assess its ability to recover and classify objects. This resulted in a recovery rate of 70% (34 of the 48 mine-like objects) and a classification rate of better than 80% (39 of the 48 mine-like objects).
IEEE Journal of Oceanic Engineering 11/2008; · 0.95 Impact Factor
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ABSTRACT: Reverberation and noise cause significant deterioration of audio quality and intelligibility to signals recorded in acoustic environments. Bayesian dereverberation infers knowledge about the system by exploiting the statistical properties of speech and the acoustic channel. In Bayesian frameworks, the signal can be processed either sequentially using online methods or in a batch using offline methods. This paper compares the two approaches for blind speech dereverberation by means of a previously proposed batch approach and a novel sequential approach. Results show that while both methods have different advantages, online processing leads to a more flexible solution.
Circuits and Systems, 2008. ISCAS 2008. IEEE International Symposium on; 06/2008
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ABSTRACT: Reverberation and noise cause significant deterioration of audio quality and intelligibility to signals recorded in acoustic environments. Noise is usually modeled as a common signal observed in the room and independent of room acoustics. However, this simplistic model cannot necessarily capture the effects of separate noise sources at different locations in the room. This paper proposes a noise model that considers distinct noise sources whose individual acoustic impulse responses are separated into source-sensor specific and common acoustical resonances. Further to noise, the signal is distorted by reverberation. Using parametric models of the system, recursive expressions of the filtering distribution can be derived. Based on these results, a sequential Monte Carlo approach for online dereverberation and enhancement is proposed. Simulation results for speech are presented to verify the effectiveness of the model and method.
Acoustics, Speech and Signal Processing, 2008. ICASSP 2008. IEEE International Conference on; 05/2008 · 4.63 Impact Factor
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P. Crump,
P. Leisher,
T. Matson,
V. Anderson,
D. Schulte, J. Bell,
J. Farmer,
M. DeVito,
R. Martinsen,
Y. K. Kim,
K. D. Choquette,
G. Erbert,
G. Trankle
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ABSTRACT: Etching microstructures into broad area diode lasers is found to lead to more uniform near field and increased power conversion efficiency, arising from increased slope. Self-consistent device simulation indicates that this improvement is due to an increase in the effective internal injection efficiency above threshold—the nonuniform near field leads to regions of inefficient clamping of the carrier density in the laser stripe. Measurements of spontaneous emission through the substrate confirm the predicted carrier profile. Both experiment and theory show that improved overlap between carrier and power distributions correlates with improved slope.
Applied Physics Letters 04/2008; · 3.84 Impact Factor
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ABSTRACT: There is considerable technological interest in developing new fuel-flexible combustion systems that can burn fuels such as hydrogen or syngas. Lean premixed systems have the potential to burn these types of fuels with high efficiency and low NOx emissions due to reduced burnt gas temperatures. Although traditional Scientific approaches based on theory and laboratory experiment have played essential roles in developing our current understanding of premixed combustion, they are unable to meet the challenges of designing fuel-flexible lean premixed combustion devices. Computation, with its ability to deal with complexity and its unlimited access to data, has the potential for addressing these challenges. Realizing this potential requires the ability to perform high fidelity simulations of turbulent lean premixed flames under realistic conditions. In this paper, we examine the specialized mathematical structure of these combustion problems and discuss simulation approaches that exploit this structure. Using these ideas we can dramatically reduce computational cost, making it possible to perform high-fidelity simulations of realistic flames. We illustrate this methodology by considering ultra-lean hydrogen flames and discuss how this type of simulation is changing the way researchers study combustion.
Journal of Physics Conference Series 09/2006; 46(1):1.
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ABSTRACT: For many explosives, only a fraction of the chemical energy is released in the detonation. Calorimetry data for TNT from Ornellas (1984) shows that when the ambient gas is inert, there is substantially less total energy released than when the ambient gas is air. This data indicates that burning of the explosion byproducts plays a key role in the overall energetics of the system. In this paper, we briefly discuss the models and the numerical methods used for the simulations and present the computational results. We also discuss future directions our work on the development of SDF explosives
HPCMP Users Group Conference, 2006; 07/2006
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ABSTRACT: We report on results of calibration and present distributions of
polarization degree of Mars surface from HST observations. Polarization
of light scattered by atmospheric aerosols gives information about
particles and their orientation.
02/2004; 35:1435.
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ABSTRACT: The lifetimes of positrons in argon and argon-nitrogen mixtures have been measured in more than one hundred experiments. With a high-resolution time-to-pulse-height converter the `shoulder' after the prompt peak has been studied. The results are interpreted to mean that (i) the τ2 component is due to the decay of orthopositronium, (ii) the shoulder is that part of the τ1 component arising from the decay of free positrons with energies below the Ore gap and (iii) the prompt peak includes the decay of parapositronium, positronium in excited states and metastable collision complexes, for example Are+, formed from positrons with energies higher than the threshold of the Ore gap.
Proceedings of the Physical Society 12/2002; 83(3):453.
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ABSTRACT: A 50 Mbits/sec burst-mode transceiver (TRx) has been demonstrated
that uses a small, integrated optical module. The design of this TRx has
potential in realizing a low cost module that will be suitable for the
access telecom networks
Lasers and Electro-Optics Society Annual Meeting, 1997. LEOS '97 10th Annual Meeting. Conference Proceedings., IEEE; 12/1997
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S. Bernabei,
R. Bell,
M. Chance,
T. K. Chu,
H. Corneliussen,
W. Davis,
G. Gettlefinger,
T. Gibney,
N. Greenough,
R. Hatcher, [......],
S. Hirschmann,
R. Isler,
D. Lee,
L. Blush,
R. Conn,
R. Doerner,
Y. Hirooka,
R. Lehmer,
L. Schmitz,
G. Tynan
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ABSTRACT: This paper presents an overview of the experiments conducted on PBX-M to evaluate the feasibility and effect of current profile and pressure profile control on the plasma stability. Utilizing the inaccessiblity of the lower hybrid waves, it has been possible to obtain a certain degree of power deposition localization and off-axis current drive. The effect of fast electron diffusion has been studied and found not to be a limiting factor; consequently, the current profile has been modified in a non-transient manner. More serious is the destabilization of global MHD modes, due to the change of the current profile, which can lead to disruption or to a rapid radial redistribution of the fast electron population. Experiments with ion Bernstein wave heating have shown that power can be deposited off-axis and that the ion temperature can be modified locally. Application of IBW into a strongly neutral beam (NBI) heated H-mode plasma causes a substantial increase of thermal and particle confinement in the core of the plasma: this produces a localized bootstrap current sufficient to significantly raise the value of q(0). We propose to refer to this condition as the CH-mode (or core high-confinement mode).
Fusion Engineering and Design. 01/1995; 26(1-4):83-88.
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Eos Transactions American Geophysical Union 01/1995; 76(13):129-129.
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S. Bernabei,
R. Bell,
M. Chance,
T. K. Chu,
M. Corneliussen,
W. Davis,
G. Gettlefinger,
T. Gibney,
N. Greenough,
R. Hatcher, [......],
S. Hirschman,
R. Isler,
D. Lee,
L. Blush,
R. Conn,
R. Doerner,
Y. Hirooka,
R. Lehmer,
L. Schmitz,
G. Tynan
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ABSTRACT: The experimental program of the Princeton Beta Experiment-Modified (PBX-M) tokamak [Phys. Fluids B2, 1271 (1990)] is directed toward tailoring plasma profiles to achieve greater stability and confinement and to gain access to the second stability region. Modification of the current density profile has been achieved with lower-hybrid current drive (LHCD), leading to a regime free of global magnetohydrodynamic modes, while raising the value of q(0) above unity. The diffusion of the fast electrons produced by LHCD has been examined using two-dimensional hard x-ray imaging. Ion Bernstein waves (IBW) have been used for ion heating: a preliminary analysis shows that ion heating was spatially localized and in agreement with theoretical calculations. Divertor biasing has modified the electric field inside the last closed surface, resulting in the formation of a transport barrier, which in turn has reduced the threshold power of neutral beam injection (NBI) for H-mode transition by 25%.
Physics of Fluids B Plasma Physics 01/1993; 5(7):2562-2570.
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M.E. Gore,
C. Viner,
M. Meldrum, J. Bell,
S. Milan,
A. Zuiable,
M. Slevin,
P.J. Selby,
P.I. Clark,
B. Millar,
J.A. Maitland,
I.R. Judson,
C. Tillyer,
J.S. Malpas,
T.J. Mcelwain
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ABSTRACT: 50 previously untreated patients with multiple myeloma received two-phase treatment: repeated cycles of 4 day infusion with vincristine, doxorubicin, and methylprednisolone (VAMP) followed by high-dose melphalan (HDM), with autologous bone marrow transplantation where possible. The overall response rate was 74% (37/50), with 25 patients (50%) achieving complete haematological and biochemical remission. These remissions were associated with a good quality of life as measured by performance status, pain grade, and the reversal of humoral immunosuppression. 6 patients died during the VAMP phase and there was 1 death related to HDM. The achievement of complete remission, as defined here, in such a high proportion of patients is exeptional and may represent a useful advance in the management of myeloma.
The Lancet 11/1989; · 38.28 Impact Factor
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V. I. Efremenko,
A. V. Fedotov,
P. A. Gorichev,
V. S. Kaftanov,
G. K. Kliger,
V. Z. Kolganov,
S. P. Krutchinin,
M. A. Kubantsev,
I. V. Makhlyueva,
M. M. Savitsky, [......],
A. A. Volkov,
V. G. Zaets, J. Bell,
C. T. Coffin,
W. Louis,
B. P. Roe,
R. T. Ross,
A. A. Seidl,
D. Sinclair,
E. Wang
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ABSTRACT: Backward protons from neutrino and antineutrino interactions in a
Ne-H2 mixture are studied. The inclusive characteristics of
the reactions are presented for both neutral- and charged-current events
and comparison with models are made. The data are in agreement with the
hypothesis of nuclear scaling.
Physical review D: Particles and fields 11/1980; 22:2581-2584.
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J. P. Berge,
D. Bogert,
R. Endorf,
R. Hanft,
J. A. Malko,
G. Moffatt,
F. A. Nezrick,
W. G. Scott,
W. Smart,
J. Wolfson, [......],
M. M. Savitsky,
V. G. Shevchenko, J. Bell,
C. T. Coffin,
H. T. French,
W. C. Louis,
B. P. Roe,
R. T. Ross,
A. A. Seidl,
D. Sinclair
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ABSTRACT: From a sample of charged-current antineutrino events in a Ne-H mixture
we have obtained a subsample of events having a backward proton in the
laboratory. The systematics of these backward-proton events are found to
be in agreement with previous results from backward-proton events
obtained using hadron and γ beams.
Physical review D: Particles and fields 08/1978; 18:1367-1369.
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ABSTRACT: The paper deals with development work on which the authors have been engaged since 1945 on machines for the transmission of pictures and facsimiles over land-lines and radio. Faithful tone reproduction of photographic material has been attained, and machines have been produced to fulfil the needs of the Press. Machines with more precise scanning, up to 500 lines per inch, have been developed. A method of controlled retoning of a picture is also described. Further developments have been made using an electrochemical action instead of photographic paper as the recording medium. Machines have been produced to receive tone pictures and to act either independently or as monitors to the photographic machines. Recent applications of the electrochemical recorder to facsimile and telegraph purposes are described.
Proceedings of the IEE - Part III: Radio and Communication Engineering. 12/1952;
