160 research outputs found
Architecture and Design of Generic IEEE-754 Based Floating Point Adder, Subtractor and Multiplier
The Floating point numbers are being widely used in various fields because of their great dynamic range, high precision and easy operation rules. In this paper, architecture of generic floating point unit is proposed and discussed. This generic unit is compatible with all three IEEE-754 binary formats. Further based on this architecture, floating point adder, subtractor and multiplier modules are designed and functionally verified for Virtex-4 FPGA. The design is working properly and giving accurate result up to the last point.
DOI: 10.17762/ijritcc2321-8169.15054
Evolving Lorentzian Wormholes
Evolving Lorentzian wormholes with the required matter satisfying the Energy
conditions are discussed. Several different scale factors are used and the
corresponding consequences derived. The effect of extra, decaying (in time)
compact dimensions present in the wormhole metric is also explored and certain
interesting conclusions are derived for the cases of exponential and
Kaluza--Klein inflation.Comment: 10 pages( RevTex, Twocolumn format), Two figures available on request
from the first author. transmission errors corrected
Quantum Perfect-Fluid Kaluza-Klein Cosmology
The perfect fluid cosmology in the 1+d+D dimensional Kaluza-Klein spacetimes
for an arbitrary barotropic equation of state is quantized by using
the Schutz's variational formalism. We make efforts in the mathematics to solve
the problems in two cases. For the first case of the stiff fluid we
exactly solve the Wheeler-DeWitt equation when the space is flat. After the
superposition of the solutions we analyze the Bohmian trajectories of the
final-stage wave-packet functions and show that the flat spaces and the
compact spaces will eventually evolve into finite scale functions. For the
second case of , we use the approximated wavefunction in the
Wheeler-DeWitt equation to find the analytic forms of the final-stage
wave-packet functions. After analyzing the Bohmian trajectories we show that
the flat spaces will be expanding forever while the scale function of the
contracting spaces would not become zero within finite time. Our
investigations indicate that the quantum effect in the quantum perfect-fluid
cosmology could prevent the extra compact spaces in the Kaluza-Klein theory
from collapsing into a singularity or that the "crack-of-doom" singularity of
the extra compact dimensions is made to occur at .Comment: Latex 18 pages, add section 2 to introduce the quantization of
perfect flui
Accelerating Universe from an Evolving Lambda in Higher Dimension
We find exact solutions in five dimensional inhomogeneous matter dominated
model with a varying cosmological constant. Adjusting arbitrary constants of
integration one can also achieve acceleration in our model. Aside from an
initial singularity our spacetime is regular everywhere including the centre of
the inhomogeneous distribution. We also study the analogous homogeneous
universe in (4+d) dimensions. Here an initially decelerating model is found to
give late acceleration in conformity with the current observational demands. We
also find that both anisotropy and number of dimensions have a role to play in
determining the time of flip, in fact the flip is delayed in multidimensional
models. Some astrophysical parameters like the age, luminosity distance etc are
also calculated and the influence of extra dimensions is briefly discussed.
Interestingly our model yields a larger age of the universe compared to many
other quintessential models.Comment: 18 pages, 9 figure
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Tophaceous gout in the sternoclavicular joint.
Gouty arthritis commonly occurs in peripheral synovial joints and involvement in the thoracic cage is extremely rare. We report a case of a 52-year-old presenting with a painful bony mass in her sternal notch. Imaging demonstrated a lobulated calcified and necrotic lesion causing mass effect on adjacent structures. Excision biopsy confirmed a benign cystic lesion with amorphous material containing needle-shaped refractile crystals suggestive of uric acid. Tophaceous gout was diagnosed. Presence of a periarticular mass with characteristics of gout should warrant investigation with biopsy and imaging. This can prevent misdiagnosis of malignancy and avoid unnecessary surgery in asymptomatic lesions
GHRH secretion from a pancreatic neuroendocrine tumor causing gigantism in a patient with MEN1.
Summary: A male patient with a germline mutation in MEN1 presented at the age of 18 with classical features of gigantism. Previously, he had undergone resection of an insulin-secreting pancreatic neuroendocrine tumour (pNET) at the age of 10 years and had subtotal parathyroidectomy due to primary hyperparathyroidism at the age of 15 years. He was found to have significantly elevated serum IGF-1, GH, GHRH and calcitonin levels. Pituitary MRI showed an overall bulky gland with a 3 mm hypoechoic area. Abdominal MRI showed a 27 mm mass in the head of the pancreas and a 6 mm lesion in the tail. Lanreotide-Autogel 120 mg/month reduced GHRH by 45% and IGF-1 by 20%. Following pancreaticoduodenectomy, four NETs were identified with positive GHRH and calcitonin staining and Ki-67 index of 2% in the largest lesion. The pancreas tail lesion was not removed. Post-operatively, GHRH and calcitonin levels were undetectable, IGF-1 levels normalised and GH suppressed normally on glucose challenge. Post-operative fasting glucose and HbA1c levels have remained normal at the last check-up. While adolescent-onset cases of GHRH-secreting pNETs have been described, to the best of our knowledge, this is the first reported case of ectopic GHRH in a paediatric setting leading to gigantism in a patient with MEN1. Our case highlights the importance of distinguishing between pituitary and ectopic causes of gigantism, especially in the setting of MEN1, where paediatric somatotroph adenomas causing gigantism are extremely rare. Learning points: It is important to diagnose gigantism and its underlying cause (pituitary vs ectopic) early in order to prevent further growth and avoid unnecessary pituitary surgery. The most common primary tumour sites in ectopic acromegaly include the lung (53%) and the pancreas (34%) (1): 76% of patients with a pNET secreting GHRH showed a MEN1 mutation (1). Plasma GHRH testing is readily available in international laboratories and can be a useful diagnostic tool in distinguishing between pituitary acromegaly mediated by GH and ectopic acromegaly mediated by GHRH. Positive GHRH immunostaining in the NET tissue confirms the diagnosis. Distinguishing between pituitary (somatotroph) hyperplasia secondary to ectopic GHRH and pituitary adenoma is difficult and requires specialist neuroradiology input and consideration, especially in the MEN1 setting. It is important to note that the vast majority of GHRH-secreting tumours (lung, pancreas, phaeochromocytoma) are expected to be visible on cross-sectional imaging (median diameter 55 mm) (1). Therefore, we suggest that a chest X-ray and an abdominal ultrasound checking the adrenal glands and the pancreas should be included in the routine work-up of newly diagnosed acromegaly patients
Integration of D-dimensional 2-factor spaces cosmological models by reducing to the generalized Emden-Fowler equation
The D-dimensional cosmological model on the manifold describing the evolution of 2 Einsteinian factor spaces,
and , in the presence of multicomponent perfect fluid source is
considered. The barotropic equation of state for mass-energy densities and the
pressures of the components is assumed in each space. When the number of the
non Ricci-flat factor spaces and the number of the perfect fluid components are
both equal to 2, the Einstein equations for the model are reduced to the
generalized Emden-Fowler (second-order ordinary differential) equation, which
has been recently investigated by Zaitsev and Polyanin within discrete-group
analysis. Using the integrable classes of this equation one generates the
integrable cosmological models. The corresponding metrics are presented. The
method is demonstrated for the special model with Ricci-flat spaces
and the 2-component perfect fluid source.Comment: LaTeX file, no figure
Weathering the storm: developing a user-centric weather forecast and warning system for Ireland
This paper appraises current usage and future weather service needs in Ireland. The data for this study were collected using a household preparedness questionnaire and focus groups with urban communities, rural dwellers, and marine users, farmers, students, and an island community. The questionnaire was used to collect data on weather warnings and preparedness following a category red severe weather warning. Data on participantsâ need for weather forecasts and warnings, current and future weather service requirements, and the effectiveness of the National Meteorological and Hydrological Service (NMHS) were collected from the focus groups.
Our analysis identifies the importance of accurate weather forecasts to the public and groups such as farmers as they plan their professional and private lives. Participants were aware of the weather warning system's color-coded structure, with the highest-level warnings considered most effective in capturing attention. Most participants spoke negatively about category yellow warnings, as they perceived them to be issued too frequently. Experience of warnings being issued and threats failing to materialize caused a minority of participants to ignore warnings and not take preparedness action. The professionalism of the NMHS was praised by focus group participants, and there was a high level of overall satisfaction with the quality of the national weather warning system (75.1% of survey participants were mostly or extremely satisfied).
Opportunities to improve weather services included enhanced communication with service users, improved web and app interfaces, a move to probabilistic forecasting, and weather warnings that encompass calls to action
D-branes, String Cosmology and Large Extra Dimensions
D-branes are fundamental in all scenarios where there are large extra
dimensions and the string scale is much smaller than the four-dimensional
Planck mass. We show that this current picture leads to a new approach to
string cosmology where inflation on our brane is driven by the large extra
dimensions and the issue of the graceful exit becomes inextricably linked to
the problem of the stabilization of the extra dimensions, suggesting the
possibility of a common solution. We also show that branes may violently
fluctuate along their transverse directions in curved spacetime, possibly
leading to a period of brane-driven inflation. This phenomenon plays also a
crucial role in many other cosmological issues, such as the smoothing out of
the cosmological singularities and the generation of the baryon asymmetry on
our three brane.Comment: LaTeX file, 4 page
Dilaton Contributions to the Cosmic Gravitational Wave Background
We consider the cosmological amplification of a metric perturbation
propagating in a higher-dimensional Brans-Dicke background, including a non
trivial dilaton evolution. We discuss the properties of the spectral energy
density of the produced gravitons (as well as of the associated squeezing
parameter), and we show that the present observational bounds on the graviton
spectrum provide significant information on the dynamical evolution of the
early universe.Comment: 26 pages, plain tex (to appear in Phys.Rev.D, 1 fig available from
the authors upon req.
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