1,317 research outputs found
The narrative approach for the identification of monetary policy shocks in small open economies
This paper reviews 22 years of UK monetary policy (1971-1992) using official record from the Quarterly Bulletin of the Bank of England. A definition of policy shocks, which allows for the exclusion of cases of interest rate increases, which were unrelated to the monetary policy objectives, is used. The empirical analysis shows that output displays the usual hump-shaped response after a shock to the policy indicator but adjustment to pre-shock levels is slow. Other variables also display theory-consistent behaviour. Based on this policy indicator monetary policy is found to cause very limited output fluctuation in a four year horizon. The policy indicator is found to outperform the intervention rate as a measure of policymonetary policy shocks, narrative approach, UK
Estimating the Euler Equation for Aggregate Investment with Endogenous Capital Depreciation
This paper looks at the empirical consequences of introducing endogenous capital depreciation in the standard neoclassical model with quadratic adjustment costs. To this end, we formulate an empirical specification that accommodates capital maintenance and utilization in the Euler equations for aggregate investment. The empirical estimates with data from the Canadian survey on Capital and Repair Expenditures show that, in contrast to the existing literature, the performance of the Euler equations is improved when we account for the impact of variable capital depreciation.Euler equation; endogenous depreciation; maintenance expenditures
Modelling and tracking objects with a topology preserving self-organising neural network
Human gestures form an integral part in our everyday communication. We use
gestures not only to reinforce meaning, but also to describe the shape of objects,
to play games, and to communicate in noisy environments. Vision systems that
exploit gestures are often limited by inaccuracies inherent in handcrafted models.
These models are generated from a collection of training examples which requires
segmentation and alignment. Segmentation in gesture recognition typically involves manual intervention, a time consuming process that is feasible only for a
limited set of gestures. Ideally gesture models should be automatically acquired
via a learning scheme that enables the acquisition of detailed behavioural knowledge only from topological and temporal observation.
The research described in this thesis is motivated by a desire to provide a framework for the unsupervised acquisition and tracking of gesture models. In any
learning framework, the initialisation of the shapes is very crucial. Hence, it would
be beneficial to have a robust model not prone to noise that can automatically correspond the set of shapes. In the first part of this thesis, we develop a framework
for building statistical 2D shape models by extracting, labelling and corresponding
landmark points using only topological relations derived from competitive hebbian learning. The method is based on the assumption that correspondences can
be addressed as an unsupervised classification problem where landmark points
are the cluster centres (nodes) in a high-dimensional vector space. The approach
is novel in that the network can be used in cases where the topological structure of
the input pattern is not known a priori thus no topology of fixed dimensionality is imposed onto the network.
In the second part, we propose an approach to minimise the user intervention
in the adaptation process, which requires to specify a priori the number of nodes
needed to represent an object, by utilising an automatic criterion for maximum
node growth. Furthermore, this model is used to represent motion in image sequences by initialising a suitable segmentation that separates the object of interest
from the background. The segmentation system takes into consideration some illumination tolerance, images as inputs from ordinary cameras and webcams, some
low to medium cluttered background avoiding extremely cluttered backgrounds,
and that the objects are at close range from the camera.
In the final part, we extend the framework for the automatic modelling and
unsupervised tracking of 2D hand gestures in a sequence of k frames. The aim
is to use the tracked frames as training examples in order to build the model and
maintain correspondences. To do that we add an active step to the Growing Neural Gas (GNG) network, which we call Active Growing Neural Gas (A-GNG) that
takes into consideration not only the geometrical position of the nodes, but also the
underlined local feature structure of the image, and the distance vector between
successive images. The quality of our model is measured through the calculation
of the topographic product. The topographic product is our topology preserving
measure which quantifies the neighbourhood preservation.
In our system we have applied specific restrictions in the velocity and the appearance of the gestures to simplify the difficulty of the motion analysis in the gesture representation. The proposed framework has been validated on applications
related to sign language. The work has great potential in Virtual Reality (VR) applications where the learning and the representation of gestures becomes natural
without the need of expensive wear cable sensors
The Balance Sheet Channel of Monetary Policy Transmission: Evidence from the UK
This paper examines the sensitivity of investment to cash flow using a panel of UK firms in manufacturing with a view to shedding some light on the existence of a balance sheet channel or financial accelerator. In addition to examining the impact of cash flow in different subsamples based on company size or financial policy (dividend payouts, share issues and debt accumulation), we also investigate the extent to which investment becomes more sensitive to cash flow in periods of monetary tightness. To this end, we employ a monetary tightness indicator constructed for the UK using the narrative approach pioneered by Romer and Romer. The results provide some support for the view that UK firms show greater investment sensitivity to cash flow during periods of tight monetary policy.Financial Constraints; Balance Sheet Channel, Investment.
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Perceiving, Measuring and Modeling Materials
This paper focuses in the interpretation of material properties of reflectivity and specularity assessed by the visual system under illumination consisting of both a focal and a diffuse component (the âsun-and-skyâ illumination assumption). This assumption provides for four kinds of luminance gradients: gradients of incident illumination, gradients of reflectivity, gradients of secondary self-illumination and gradients of shadowing. The analysis considers the dissociation of the material properties carried by specularity from the geometric properties of object shape, taking the sinusoidal surface as a canonical shape exemplar
Oral Hygiene Facilitators and Barriers in Greek 10 Years Old Schoolchildren
Aim: The aim of this study was to determine the oral hygiene facilitators and barriers for 10 years old Greek children, via a questionnaire and clinical examination.
Materials and Methods: This was a cross-sectional study of 266, 10 years old, children recruited from schools in 3 locations in Greece. Data were collected via questionnaires and clinical examination. Questionnaires referred to children\u27s oral hygiene knowledge, behavior and attitude as well as parents\u27 oral hygiene behavior and educational level. Children were clinically examined by two calibrated pediatric dentists using a WHO probe and artificial light to assess dental plaque (hygiene index-HI), gingivitis (simplified gingival index-GIs) and dental caries (DMFT-BASCD criteria).
Results: Regarding oral hygiene knowledge, although 80% of the children were literate of the proper means of oral hygiene, only 58.64% brushed their teeth twice daily and 36.84% used dental floss. Children\u27s oral hygiene knowledge was positively correlated with both parental brushing frequency (Ï = 0.175, p \u3c 0.05) and educational level (Ï = -0.216, p \u3c 0.05). Toothpaste use was reported by 92.11% of the children. Regarding children\u27s attitude, 62.28% were concerned whether their teeth were clean, with girls showing greater concern than boys (p \u3c 0.001). Their reported beliefs regarding brushing avoidance were boredom (84.06%), low oral health literacy (73.91%) and forgetfulness (56.52%).
Conclusion: Oral hygiene facilitators were found to be the concern about how clean were their teeth, oral health literacy of both children and parents and toothpaste appeal to children. Oral hygiene barriers were children\u27s boredom, low oral health literacy, forgetfulness and low socioeconomic level
ID Theft: A computer forensics\u27 investigation framework
The exposure of online identities grows rapidly nowadays and so does the threat of having even more impersonated identities. Internet users provide their private information on multiple web-based agents for a number of reasons, online shopping, memberships, social networking, and many others. However, the number of ID Theft victims grows as well, resulting to the growth of the number of incidents that require computer forensics investigation in order to resolve this type of crime. For this reason, it appears of value to provide a systematic approach for the computer forensics investigators aiming to resolve such type of computer based ID Theft incidents. The issues that demand individual examinations of this type of crime are discussed and the plan of an ID Theft computer forensics investigation framework is presented
Congenital Adrenal Hyperplasia: A Case Report with Premature Teeth Exfoliation and Bone Resorption
Congenital adrenal hyperplasia (CAH) is an inherited autosomal recessive disorder characterized by insufficient production of cortisol. The aim of this case report was to present a child with CAH, premature exfoliation of primary teeth and accelerated eruption of his permanent teeth related to bone resorption. A 4.5-year-old Caucasian boy with CAH and long-term administration of glucocorticoids was referred for dental restoration. Clinical examination revealed primary molars with worn stainless steel crowns, severe attrition of the upper canines, and absence of the upper incisors. Before the completion of treatment, abnormal mobility of the first upper primary molars and the lower incisors was detected, and a few days later the teeth exfoliated prematurely. Histologic examination revealed normal tooth structure. Alkaline phosphatase and blood cells values were normal. Eruption of the permanent dentition was also accelerated. Tooth mobility was noticed in the permanent teeth as soon as they erupted, along with bone destruction. Examination revealed an elevated level of receptor activator of nuclear factor-kB ligand and lower-than-normal osteoprotegerin and vitamin D levels. The patient was treated with vitamin D supplements, and his teeth have been stable ever since. CAH is a serious chronic disorder appearing in children with accelerated dental development and possibly premature loss of primary teeth
Analysis of digital evidence in identity theft investigations
Identity Theft could be currently considered as a significant problem in the modern
internet driven era. This type of computer crime can be achieved in a number of
different ways; various statistical figures suggest it is on the increase. It intimidates
individual privacy and self assurance, while efforts for increased security and
protection measures appear inadequate to prevent it. A forensic analysis of the digital
evidence should be able to provide precise findings after the investigation of Identity
Theft incidents. At present, the investigation of Internet based Identity Theft is
performed on an ad hoc and unstructured basis, in relation to the digital evidence.
This research work aims to construct a formalised and structured approach to digital
Identity Theft investigations that would improve the current computer forensic
investigative practice. The research hypothesis is to create an analytical framework to
facilitate the investigation of Internet Identity Theft cases and the processing of the
related digital evidence.
This research work makes two key contributions to the subject: a) proposing the
approach of examining different computer crimes using a process specifically based
on their nature and b) to differentiate the examination procedure between the victimâs and the fraudsterâs side, depending on the ownership of the digital media. The
background research on the existing investigation methods supports the need of
moving towards an individual framework that supports Identity Theft investigations.
The presented investigation framework is designed based on the structure of the
existing computer forensic frameworks. It is a flexible, conceptual tool that will assist
the investigatorâs work and analyse incidents related to this type of crime. The
research outcome has been presented in detail, with supporting relevant material for
the investigator. The intention is to offer a coherent tool that could be used by
computer forensics investigators. Therefore, the research outcome will not only be
evaluated from a laboratory experiment, but also strengthened and improved based on
an evaluation feedback by experts from law enforcement.
While personal identities are increasingly being stored and shared on digital media,
the threat of personal and private information that is used fraudulently cannot be
eliminated. However, when such incidents are precisely examined, then the nature of
the problem can be more clearly understood
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