5,140 research outputs found
Unobtrusive and pervasive video-based eye-gaze tracking
Eye-gaze tracking has long been considered a desktop technology that finds its use inside the traditional office setting, where the operating conditions may be controlled. Nonetheless, recent advancements in mobile technology and a growing interest in capturing natural human behaviour have motivated an emerging interest in tracking eye movements within unconstrained real-life conditions, referred to as pervasive eye-gaze tracking. This critical review focuses on emerging passive and unobtrusive video-based eye-gaze tracking methods in recent literature, with the aim to identify different research avenues that are being followed in response to the challenges of pervasive eye-gaze tracking. Different eye-gaze tracking approaches are discussed in order to bring out their strengths and weaknesses, and to identify any limitations, within the context of pervasive eye-gaze tracking, that have yet to be considered by the computer vision community.peer-reviewe
An efficiency analysis of banking systems: a comparison of European and United States large commercial banks using different functional forms.
This paper aims at investigation the efficiency of European and U.S. commercial banks. Scale and scope economies indicators, as well as a measurement of X-efficiency are derived from three cost functions: Fourier flexible form, translog and Box-Cox. This allows checking the stability and the robustness of the evidence across the different specifications. Our results over the period 1995-98 show that overall the average cost curve is relatively flat with some evidence of scale efficiency gains. More puzzling are the results on the presence of scope economies.
On-screen point-of-regard estimation under natural head movement for a computer with integrated webcam
Recent developments in the field of eye-gaze tracking by vidoeoculography indicate a growing interest towards unobtrusive tracking in real-life scenarios, a new paradigm referred to as pervasive eye-gaze tracking. Among the challenges associated with this paradigm, the capability of a tracking platform to integrate well into devices with in-built imaging hardware and to permit natural head movement during tracking is of importance in less constrained scenarios. The work presented in this paper builds on our earlier work, which addressed the problem of estimating on-screen point-of-regard from iris center movements captured by an integrated camera inside a notebook computer, by proposing a method to approximate the head movements in conjunction with the iris movements in order to alleviate the requirement for a stationary head pose. Following iris localization by an appearance-based method, linear mapping functions for the iris and head movement are computed during a brief calibration procedure permitting the image information to be mapped to a point-of-regard on the monitor screen. Following the calculation of the point-of-regard as a function of the iris and head movement, separate Kalman filters improve upon the noisy point-of-regard estimates to smoothen the trajectory of the mouse cursor on the monitor screen. Quantitative and qualitative results obtained from two validation procedures reveal an improvement in the estimation accuracy under natural head movement, over our previous results achieved from earlier work.peer-reviewe
Search for Higgs Bosons in SUSY Cascade Decays and Neutralino Dark Matter
The Minimal Supersymmetric Extension of the Standard Model (MSSM) is a well
motivated theoretical framework, which contains an extended Higgs sector,
including a light Higgs with Standard Model-like properties in most of the
parameter space. Due to the large QCD background, searches for such a Higgs,
decaying into a pair of bottom quarks, is very challenging at the LHC. It has
been long realized that the situation may be ameliorated by searching for Higgs
bosons in supersymmetric decay chains. Moreover, it has been recently suggested
that the bobber decay channel may be observed in standard production channels
by selecting boosted Higgs bosons, which may be easily identified from the QCD
background. Such boosted Higgs bosons are frequent in the MSSM, since they are
produced from decays of heavy colored supersymmetric particles. Previous works
have emphasized the possibility of observing boosted Higgs bosons in the light
higgsino region. In this work, we study the same question in the regions of
parameter space consistent with a neutralino dark matter relic density,
analyzing its dependence on the non-standard Higgs boson, slepton and squark
masses, as well as on the condition of gaugino mass unification. In general, we
conclude that, provided sleptons are heavier than the second lightest
neutralinos, the presence of boosted Higgs is a common MSSM feature, implying
excellent prospects for observation of the light MSSM Higgs boson in the near
future.Comment: 30 pages, 9 figures. v2: New Xenon 100 results implemented, version
to appear in PR
Metastatic tumors to the stomach: clinical and endoscopic features.
AIM: To evaluate the clinical and endoscopic patterns in a large series of patients with metastatic tumors in the stomach. METHODS: A total of 64 patients with gastric metastases from solid malignant tumors were retrospectively examined between 1990 and 2005. The clinicopathological findings were reviewed along with tumor characteristics such as endoscopic pattern, location, size and origin of the primary sites. RESULTS: Common indications for endoscopy were anemia, bleeding and epigastric pain. Metastases presented as solitary (62.5%) or multiple (37.5%) tumors were mainly located in the middle or upper third of stomach. The main primary metastatic tumors were from breast and lung cancer and malignant melanoma. CONCLUSION: As the prognosis of cancer patients has been improving gradually, gastrointestinal (GI) metastases will be encountered more often. Endoscopic examinations should be conducted carefully in patients with malignancies, and endoscopic biopsies and information on the patient's clinical history are useful for correct diagnosis of gastric metastases
The role of long waves in the stability of the plane wake
This work is directed towards investigating the fate of three-dimensional
long perturbation waves in a plane incompressible wake. The analysis is posed
as an initial-value problem in space. More specifically, input is made at an
initial location in the downstream direction and then tracing the resulting
behavior further downstream subject to the restriction of finite kinetic
energy. This presentation follows the outline given by Criminale and Drazin
[Stud. in Applied Math. \textbf{83}, 123 (1990)] that describes the system in
terms of perturbation vorticity and velocity. The analysis is based on large
scale waves and expansions using multi scales and multi times for the partial
differential equations. The multiscaling is based on an approach where the
small parameter is linked to the perturbation property independently from the
flow control parameter. Solutions of the perturbative equations are determined
numerically after the introduction of a regular perturbation scheme
analytically deduced up to the second order. Numerically, the complete linear
system is also integrated. Since the results relevant to the complete problem
are in very good agreement with the results of the first order analysis, the
numerical solution at the second order was deemed not necessary. The use for an
arbitrary initial-value problem will be shown to contain a wealth of
information for the different transient behaviors associated to the symmetry,
angle of obliquity and spatial decay of the long waves. The amplification
factor of transversal perturbations never presents the trend - a growth
followed by a long damping - usually seen in waves with wavenumber of order one
or less. Asymptotical instability is always observed.Comment: accepted Physical Review E, March 201
Signals of CP Violation Beyond the MSSM in Higgs and Flavor Physics
We study an extension of the Higgs sector of the Minimal Supersymmetric
Standard Model (MSSM), considering the effects of new degrees of freedom at the
TeV scale, and allowing for sources of CP violation beyond the MSSM (BMSSM). We
analyze the impact of the BMSSM sources of CP violation on the Higgs collider
phenomenology and on low energy flavor and CP violating observables. We
identify distinct Higgs collider signatures that cannot be realized, either in
the case without CP violating phases or in the CP violating MSSM, and
investigate the prospects to probe them at the Tevatron and the LHC. The most
striking benchmark scenario has three neutral Higgs bosons that all decay
dominantly into W boson pairs and that are well within the reach of the 7 TeV
LHC run. On the other hand, we also present scenarios with three Higgs bosons
that have masses M_Hi > 150 GeV and decay dominantly into b bbar. Such
scenarios are much more challenging to probe and can even lie completely
outside the reach of the 7 TeV LHC run. We explore complementary scenarios with
standard MSSM Higgs signals that allow to accommodate a sizable B_s mixing
phase as indicated by D0, as well as the excess in B_s --> mu+ mu- candidates
recently reported by CDF. We find that, in contrast to the MSSM, a minimal
flavor violating soft sector is sufficient to generate significant corrections
to CP violating observables in meson mixing, compatible with EDM constraints.
In particular, a sizable B_s mixing phase, S_psiphi < 0.4, can be achieved for
specific regions of parameter space. Such a large B_s mixing phase would
unambiguously imply a sizable suppression of S_psiKs with respect to the SM
prediction and a BR(B_s --> mu+ mu-) close to the 95% C.L. upper bound reported
by CDF.Comment: 58 pages, 15 figures, 2 tables, v2 matches published versio
Shortened primary cilium length and dysregulated Sonic hedgehog signaling in Niemann-Pick C1 disease
The Niemann-Pick type C1 (NPC1) disease is a neurodegenerative lysosomal storage disorder due to mutations in the NPC1 gene, encoding a transmembrane protein related to the Sonic hedgehog receptor, Patched, and involved in intracellular trafficking of cholesterol. We have recently found that the proliferation of cerebellar granule neuron precursors is significantly reduced in Npc1-/- mice due to the downregulation of Shh expression. This finding prompted us to analyze the formation of the primary cilium, a non-motile organelle that is specialized for Shh signal transduction and responsible, when defective, for several human genetic disorders. In this study, we show that the expression and subcellular localization of Shh effectors and ciliary proteins are severely disturbed in Npc1-deficient mice. The dysregulation of Shh signaling is associated with a shortening of the primary cilium length and with a reduction of the fraction of ciliated cells in Npc1-deficient mouse brains and the human fibroblasts of NPC1 patients. These defects are prevented by treatment with 2-hydroxypropyl-β-cyclodextrin, a promising therapy currently under clinical investigation. Our findings indicate that defective Shh signaling is responsible for abnormal morphogenesis of the cerebellum of Npc1-deficient mice and show, for the first time, that the formation of the primary cilium is altered in NPC1 disease
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