129,565 research outputs found
Revisiting lepton flavor violation in supersymmetric type II seesaw
In view of the recent measurement of reactor mixing angle and
updated limit on by the MEG experiment, we re-examine
the charged lepton flavor violations in a framework of supersymmetric type II
seesaw mechanism. Supersymmetric type II seesaw predicts strong correlation
between and mainly in terms of
the neutrino mixing angles. We show that such a correlation can be determined
accurately after the measurement of . We compute different factors
which can affect this correlation and show that the mSUGRA-like scenarios, in
which slepton masses are taken to be universal at the high scale, predicts for normal
hierarchical neutrino masses. Any experimental indication of deviation from
this prediction would rule out the minimal models of supersymmetric type II
seesaw. We show that the current MEG limit puts severe constraints on the light
sparticle spectrum in mSUGRA model if the seesaw scale lies within
- GeV. It is shown that these constraints can be relaxed and
relatively light sparticle spectrum can be obtained in a class of models in
which the soft mass of triplet scalar is taken to be non-universal at the high
scale.Comment: Minor changes in text; accepted for publication in Phys. Rev.
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Changes in forward light scatter parameters as a function of refractive error in young adults
Background/aims
Some aspects of visual performance worsen with increasing myopia. Whilst the underlying causes are not always clear, reduction in retinal image quality is often attributed to structural changes in the posterior myopic eye. Forward light scatter, originating principally from the cornea and lens, is known to produce veiling glare which subsequently reduces retinal image contrast. It is therefore of interest to investigate whether forward light scatter varies with refractive error.
Methods
Thirteen young-adult subjects (18–25 years), with mean spherical errors (MSE ± sd, D) RE, − 1.69 ± 2.02 (range 0.38 to − 4.75); LE, − 1.91 ± 1.94 (range 0.50 to − 4.63) underwent binocular assessment of forward light scatter using the AVOT light scatter test. Five glare annuli, with effective eccentricities ranging from 2 to 10°, were used to estimate parameters, k and n, which define the light scatter function of the eye. These were then used to calculate the area under the light scatter function (k′) and the total volume of light scatter (k″).
Results
Significant correlation was found between increasing myopia and k′ values (RE, p 0.05 for both eyes). Axial length was also not correlated with any of the light scatter parameters measured.
Conclusion
The preliminary data from this study provide evidence that some light scatter parameters may be correlated with refractive error. Further studies are needed to characterize how changes in the anterior media of the eye, and inclusion of a wider range of refractive errors, may affect forward light scatter
Web-based information systems development and dynamic organisational change: the need for emergent development tools
This paper considers contextual issues relating to the problem of developing web-based information
systems in and for emergent organisations. It postulates that the methods available suffer because of
sudden and unexpected changing characteristics within the organisation. The Theory of Deferred
Action is used as the basis for the development of an emergent development tool. Many tools for
managing change in a continuously changing organisation are susceptible to inadequacy. The insights
proposed are believed to assist designers in developing functional and relevant approaches within
dynamic organisational contexts
Active Authentication using an Autoencoder regularized CNN-based One-Class Classifier
Active authentication refers to the process in which users are unobtrusively
monitored and authenticated continuously throughout their interactions with
mobile devices. Generally, an active authentication problem is modelled as a
one class classification problem due to the unavailability of data from the
impostor users. Normally, the enrolled user is considered as the target class
(genuine) and the unauthorized users are considered as unknown classes
(impostor). We propose a convolutional neural network (CNN) based approach for
one class classification in which a zero centered Gaussian noise and an
autoencoder are used to model the pseudo-negative class and to regularize the
network to learn meaningful feature representations for one class data,
respectively. The overall network is trained using a combination of the
cross-entropy and the reconstruction error losses. A key feature of the
proposed approach is that any pre-trained CNN can be used as the base network
for one class classification. Effectiveness of the proposed framework is
demonstrated using three publically available face-based active authentication
datasets and it is shown that the proposed method achieves superior performance
compared to the traditional one class classification methods. The source code
is available at: github.com/otkupjnoz/oc-acnn.Comment: Accepted and to appear at AFGR 201
Forward-backward asymmetry in top quark production from light colored scalars in SO(10) model
The forward-backward asymmetry in top pair production at Tevatron has been
reconfirmed by the CDF collaboration with 5.3 fb^{-1} of accumulated data.
These measurements also report that the asymmetry is the largest in regions of
high invariant mass M_{t\bar{t}} and rapidity difference |\Delta Y|. We
consider light colored sextet scalars appearing in a particular
non-supersymmetric \10 grand unification model within the \bar{126} scalar
representation. These scalar states have masses in the range of 300
\text{GeV}-2 \text{TeV} consistent with the requirements of gauge coupling
unification and bounds on the proton lifetime. The cross section and the total
asymmetry can be simultaneously explained with the contributions of these
scalars within 1. We find that the simultaneous fitting of the cross
section, the total asymmetry and the asymmetries in different rapidity and
M_{t\bar{t}} bins gives only a marginal improvement over the SM contribution.
We also study various production mechanisms of these colored sextet scalars at
the LHC.Comment: 22 pages, 11 Figures, References added, Section III and V modified.
Version accepted for publication in JHE
C2AE: Class Conditioned Auto-Encoder for Open-set Recognition
Models trained for classification often assume that all testing classes are
known while training. As a result, when presented with an unknown class during
testing, such closed-set assumption forces the model to classify it as one of
the known classes. However, in a real world scenario, classification models are
likely to encounter such examples. Hence, identifying those examples as unknown
becomes critical to model performance. A potential solution to overcome this
problem lies in a class of learning problems known as open-set recognition. It
refers to the problem of identifying the unknown classes during testing, while
maintaining performance on the known classes. In this paper, we propose an
open-set recognition algorithm using class conditioned auto-encoders with novel
training and testing methodology. In contrast to previous methods, training
procedure is divided in two sub-tasks, 1. closed-set classification and, 2.
open-set identification (i.e. identifying a class as known or unknown). Encoder
learns the first task following the closed-set classification training
pipeline, whereas decoder learns the second task by reconstructing conditioned
on class identity. Furthermore, we model reconstruction errors using the
Extreme Value Theory of statistical modeling to find the threshold for
identifying known/unknown class samples. Experiments performed on multiple
image classification datasets show proposed method performs significantly
better than state of the art.Comment: CVPR2019 (Oral
Sparse Representation-based Open Set Recognition
We propose a generalized Sparse Representation- based Classification (SRC)
algorithm for open set recognition where not all classes presented during
testing are known during training. The SRC algorithm uses class reconstruction
errors for classification. As most of the discriminative information for open
set recognition is hidden in the tail part of the matched and sum of
non-matched reconstruction error distributions, we model the tail of those two
error distributions using the statistical Extreme Value Theory (EVT). Then we
simplify the open set recognition problem into a set of hypothesis testing
problems. The confidence scores corresponding to the tail distributions of a
novel test sample are then fused to determine its identity. The effectiveness
of the proposed method is demonstrated using four publicly available image and
object classification datasets and it is shown that this method can perform
significantly better than many competitive open set recognition algorithms.
Code is public available: https://github.com/hezhangsprinter/SROS
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