1,998 research outputs found
Massive Higher Spin Fields Coupled to a Scalar: Aspects of Interaction and Causality
We consider in detail the most general cubic Lagrangian which describes an
interaction between two identical higher spin fieldsin a triplet formulation
with a scalar field, all fields having the same values of the mass. After
performing the gauge fixing procedure we find that for the case of massive
fields the gauge invariance does not guarantee the preservation of the correct
number of propagating physical degrees of freedom. In order to get the correct
number of degrees of freedom for the massive higher spin field one should
impose some additional conditions on parameters of the vertex. Further
independent constraints are provided by the causality analysis, indicating that
the requirement of causality should be imposed in addition to the requirement
of gauge invariance in order to have a consistent propagation of massive higher
spin fields.Comment: 34 pages, comments, references and one Appendix added. Typos
corrected. Published versio
Recommended from our members
Journeys to Open Educational Practice: UKOER/SCORE Review Final Report
In 2008 the JISC Good Intentions report concluded that the landscape around learning materials had changed sufficiently to support a range of sustainable models for sharing. The report charted and acknowledged the long history of approaches to support sharing that had helped to shape the landscape.
Most of the models highlight a growing acknowledgement of the need to build and support open and sustainable communities to share practice and resources. Indeed such communities are often the key to sustaining the service, whichever model is adopted. This is the type of model most likely to encourage sharing between teachers as well as learners.
The growing OER community is taking collaborative approaches to tackling the ongoing challenges of raising awareness, licensing and trust issues, and standards and technologies. The challenge for the UK now is to ensure that our HE institutions are enabled to create policies, practices and support their staff to accelerate the transformations required to contribute and benefit from this global movement. It is also vital to ensure that we capture the real picture of use and re-use of such services and collections to inform future OER programmes.
HEFCE funding for OER initiatives followed this report in 2009 and has, in many ways, provided some of the scaffolding and support for a variety of individuals, communities and institutions to move forwards in their own journeys, whether they started years before in other contexts or had just joined on the road to open sharing
Efficient implementation of digital filters using novel reconfiguaration multiplier blocks (REMB)
Reconfigurable Multiplier Blocks (ReMB) offer significant complexity reductions in multiple constant multiplications in time-multiplexed digital filters. In this paper the ReMB technique is employed in the implementation of a half-band 32-tap FIR filter on both Xilinx Virtex FPGA and UMC 0.18micro m CMOS technologies. Reference designs have also been built by deploying standard time-multiplexed architectures and off-the-shelf Xilinx Core Generator system for the FPGA design. All designs are then compared for their area and delay figures. It is shown that, the ReMB technique
can significantly reduce the area for the multiplier circuitry and the coefficient store, as well as reducing the delay
Synthesis of reconfigurable multiplier blocks: part I: fundamentals
Reconfigurable Multiplier Blocks (ReMB) offer significant area, delay and possibly power reduction in time multiplexed
implementation of multiple constant multiplications. This paper and its companion paper (subtitled Part II- Algorithm) together present a systematic synthesis
method for Single Input Single Output (SISO) and Single
Input Multiple Output (SIMO) ReMB designs. This paper
presents the necessary foundation and terminology needed for
developing a systematic synthesis technique. The companion
paper illustrates the synthesis method through examples. The
method proposed achieves reduced logic-depth and area over
standard multipliers / multiplier blocks
Design guidelines for reconfigurable multiplier blocks
The newly proposed reconfigurable multiplier blocks offer
significant savings in area over the traditional multiplier blocks for time-multiplexed digital filters or any other system where only a subset of the coefficients that can be produced by the multiplier block is needed in a given time. The basic structure comprises a multiplexer connected to at least one input of an adder/subtractor that can generate several partial products, leading to better area utilization. The multiplier block algorithm complexity of a design increases logarithmically as the number of the multiplexers is increased. Design guidelines for the
maximum utilization of the reconfigurable multiplier block
structures are also presented
Synthesis of reconfigurable multiplier blocks: part II: algorithm
Reconfigurable Multiplier Blocks (ReMB) offer significant area, delay and possibly power reduction in time-multiplexed
implementation of multiple constant multiplications. This paper and its companion paper (entitled Part I- Fundamentals) together present a systematic synthesis
method for Single Input Single Output (SISO) and Single
Input Multiple Output (SIMO) ReMB designs. This paper
illustrates the synthesis method through examples. The
companion paper presents the necessary foundation and
terminology needed for developing a systematic synthesis
technique. The proposed method achieves reduced logic-depth
and area over standard multipliers / multiplier blocks
Efficient implementation of digital filters using novel reconfiguaration multiplier blocks (REMB)
Reconfigurable Multiplier Blocks (ReMB) offer significant complexity reductions in multiple constant multiplications in time-multiplexed digital filters. In this paper the ReMB technique is employed in the implementation of a half-band 32-tap FIR filter on both Xilinx Virtex FPGA and UMC 0.18micro m CMOS technologies. Reference designs have also been built by deploying standard time-multiplexed architectures and off-the-shelf Xilinx Core Generator system for the FPGA design. All designs are then compared for their area and delay figures. It is shown that, the ReMB technique
can significantly reduce the area for the multiplier circuitry and the coefficient store, as well as reducing the delay
A colour normalization method for giemsa-stained blood cell images
This paper presents a novel method for the colour normalization of Giemsa-stained peripheral blood cell images. The normalization is applied separately to the foreground and background regions. A rough estimation of the foreground-background regions is done by mathematical morphology and followed by a refined segmentation using histograms of these regions. Then an illumination independent response is calculated using the background region. The normalization is completed by transforming the foreground region according to a reference set. The proposed method has been tested on many images and has been found successful
Adaptive Gray World-Based Color Normalization of Thin Blood Film Images
This paper presents an effective color normalization method for thin blood film images of peripheral blood specimens. Thin blood film images can easily be separated to foreground (cell) and background (plasma) parts. The color of the plasma region is used to estimate and reduce the differences arising from different illumination conditions. A second stage nor- malization based on the database-gray world algorithm trans- forms the color of the foreground objects to match a reference color character. The quantitative experiments demonstrate the effectiveness of the method and its advantages against two other general purpose color correction methods: simple gray world and Retinex
Computer vision for microscopy diagnosis of malaria
This paper reviews computer vision and image analysis studies aiming at automated diagnosis or screening of malaria infection in microscope images of thin blood film smears. Existing works interpret the diagnosis problem differently or propose partial solutions to the problem. A critique of these works is furnished. In addition, a general pattern recognition framework to perform diagnosis, which includes image acquisition, pre-processing, segmentation, and pattern classification components, is described. The open problems are addressed and a perspective of the future work for realization of automated microscopy diagnosis of malaria is provided
- …