890 research outputs found
Attack of the Clones: Legislative Approaches to Human Cloning in the United States
The legal concerns involving the application of cloning technology to humans should be of utmost concern, as the area is extremely complex. Cloning could potentially have great benefits or disastrous effects. Lawmakers have been careful to make certain that the legislation passed is comprehensive and useful for regulation of the ever-changing field of cloning. From debates on whether reproductive or therapeutic cloning should be permitted or banned, to concerns as to who has jurisdiction over cloning, the battle to develop cloning legislation has been difficult. However, this iBrief argues that the currently-proposed federal legislation is constitutional
Adiponectin: Genetic determinants and relations with subclinical cardiovascular disease
Cardiovascular disease (CVD) is a major cause of morbidity and premature death in Sweden and globally, which besides the substantial individual suffering, puts large restraints on the public health system. Adiponectin is a highly heritable trait, which is strongly associated with metabolic disturbances such as obesity and insulin resistance. Previous studies indicate that adiponectin may play a fundamental role in the development of CVD. However, further knowledge about pathways linking circulating adiponectin, genetic loci, and markers of early CVD is needed. Therefore, the overall aim of this thesis was to assess the genetic determinants of adiponectin, and the role of adiponectin in the development of subclinical CVD.
In Study I, we investigated the association between adiponectin and cardiac geometry and function in two cross-sectional samples of elderly and found that high adiponectin levels were associated with poorer cardiac function in men. This association was dependent on N-terminal pro-brain natriuretic peptide and this was more pronounced in individuals with prior CVD, which could indicate a counter-active effect in response to decreased cardiac function, potentially mediated by natriuretic peptides.
In Study II, we examined the role of adiponectin in vascular pathology in a cross-sectional study design where higher adiponectin levels were associated with a lower lipid-content in plaques and higher vessel wall elasticity, indicating less arterial pathology.
In Study III, we assessed oxidative stress and inflammatory markers in relation to adiponectin, where adiponectin was positively associated with the anti-oxidant glutathione and inversely associated with lipid peroxidation as well as epidermal growth factor. Our findings suggest that adiponectin is associated with a more beneficial oxidative stress profile.
In Study IV, we explored the impact of rare genetic loci on circulating adiponectin levels on a genome-wide scale. Besides several independent variants around the adiponectin gene, we found a rare coding variant in a gene upstream of adiponectin receptor 2 that was associated with higher adiponectin levels. If replicated in an independent sample, these findings can provide new insight to adiponectin biology.
In conclusion, we found that individuals with poor cardiac function had higher levels of adiponectin and the results suggested that natriuretic peptides had an important role in a potentially counter-active mechanism. In contrast, high adiponectin levels were associated with a more beneficial arterial, oxidative stress and inflammation profile. Finally, rare variation around the adiponectin gene and a potentially novel locus upstream of the adiponectin receptor 2 gene was associated with adiponectin levels
Dispersion modeling and analysis for multilayered open coaxial waveguides
This paper presents a detailed modeling and analysis regarding the dispersion
characteristics of multilayered open coaxial waveguides. The study is motivated
by the need of improved modeling and an increased physical understanding about
the wave propagation phenomena on very long power cables which has a potential
industrial application with fault localization and monitoring. The
electromagnetic model is based on a layer recursive computation of
axial-symmetric fields in connection with a magnetic frill generator excitation
that can be calibrated to the current measured at the input of the cable. The
layer recursive formulation enables a stable and efficient numerical
computation of the related dispersion functions as well as a detailed analysis
regarding the analytic and asymptotic properties of the associated
determinants. Modal contributions as well as the contribution from the
associated branch-cut (non-discrete radiating modes) are defined and analyzed.
Measurements and modeling of pulse propagation on an 82 km long HVDC power
cable are presented as a concrete example. In this example, it is concluded
that the contribution from the second TM mode as well as from the branch-cut is
negligible for all practical purposes. However, it is also shown that for
extremely long power cables the contribution from the branch-cut can in fact
dominate over the quasi-TEM mode for some frequency intervals. The main
contribution of this paper is to provide the necessary analysis tools for a
quantitative study of these phenomena
Reannihilation of self-interacting dark matter
We explore the phenomenology of having a second epoch of dark matter
annihilation into dark radiation long after the standard thermal freeze-out.
Such a hidden reannihilation process could affect visible sectors only
gravitationally. As a concrete realization we consider self-interacting dark
matter (SIDM) with a light force mediator coupled to dark radiation. We
demonstrate how resonantly Sommerfeld enhanced cross sections emerge to induce
the reannihilation epoch. The effect is a temporally local modification of the
Hubble expansion rate and we show that the Cosmic Microwave Background (CMB)
measurements -- as well as other observations -- have a high sensitivity to
observe this phenomenon. Special attention is given to the model region where
late kinetic decoupling and strong self-interactions can alleviate several
small-scale problems in the cold dark matter paradigm at the same time.
Interestingly, we find that reannihilation might here also simultaneously lower
the tension between CMB and low-redshift astronomical observations of
and . Moreover, we identify reannihilation as a clear signature to
discriminate between the phenomenologically otherwise almost identical vector
and scalar mediator realizations of SIDM.Comment: Version submitted to journal. Extended with improved estimates and
updated plots. 25 pages, 9 figures and 2 table
Loop Bound Analysis based on a Combination of Program Slicing, Abstract Interpretation, and Invariant Analysis
Static Worst-Case Execution Time (WCET) analysis
is a technique to derive upper bounds for the execution
times of programs. Such bounds are crucial
when designing and verifying real-time systems. A key
component for static derivation of precise WCET estimates
is upper bounds on the number of times different
loops can be iterated.
In this paper we present an approach for deriving
upper loop bounds based on a combination of standard
program analysis techniques. The idea is to bound the
number of different states in the loop which can influence
the exit conditions. Given that the loop terminates,
this number provides an upper loop bound.
An algorithm based on the approach has been implemented
in our WCET analysis tool SWEET. We evaluate
the algorithm on a number of standard WCET
benchmarks, giving evidence that it is capable to derive
valid bounds for many types of loops
Effect of calcium neutralization on elastic and swelling properties of crosslinked poly(acrylic acid) - correlation to inhomogeneities and phase behaviour
Crosslinked hydrogels of poly(acrylic acid) neutralized with calcium hydroxide were synthesized using free radical co-polymerization. The effects of the amount added calcium on the elastic modulus and swelling properties of the gels and the correlation to phase behaviour and structural changes within the gels were studied using texture analysis, gravimetric analysis, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and atomic force microscopy (AFM). It was found that the elastic modulus decreased nonlinearly with increasing amount of added calcium and that the swelling's dependence on the amount of added calcium was complicated. The maximum swelling increased with increasing amount of added calcium until a critical calcium content was reached, upon which the gels phase separated, with a strong decrease in swelling as a result. The changes in properties are explained by the fact that calcium affects the structure of the polymer network during synthesis and by the phase behaviour of the gels. Changes in the gel structure with the addition of calcium were detected with AFM. Furthermore, AFM revealed different phases on the nanometre scale for the sample with a calcium content around which phase separation is macroscopically observed. Finally, it was shown that the sulphur from the initiator potassium persulfate formed crystal like regions with high sulphur and calcium content upon drying of the hydrogels
Electromagnetic dispersion modeling and measurements for HVDC power cables
This paper provides a general framework for electromagnetic modeling, computation and measurements regarding the wave propagation characteristics of High-Voltage Direct Current (HVDC) power cables. The modeling is focused on very long (10 km or more) HVDC power cables and the relevant frequency range is therefore in the low-frequency regime of about 0-100 kHz. An exact dispersion relation is formulated together with a discussion on practical aspects regarding the computation of the propagation constant and the related characteristic impedance. Experimental time-domain measurement data from an 80 km long HVDC power cable is used to validate the model. It is concluded that a single-mode transmission line model is not adequate to account for the mismatch between the power cable and the instrumentation. A mismatch calibration procedure is therefore devised to account for the connection between the measurement equipment and the cable. A dispersion model is thus obtained that is accurate for early times of pulse arrival. To highlight the potential of accurate electromagnetic modeling, an example of high-resolution length-estimation is discussed and analyzed using statistical methods based on the Cramer-Rao lower bound. The analysis reveals that the estimation accuracy based on the present model (and its related model error) is in the order of 100 m for an 80 km long power cable, and that the potential accuracy using a perfect model based on the given measurement data is in the order of centimeters
Coherent transient data-rate conversion and data transformation
Temporal compressions of optical pulses and pulse trains have been performed by the photon-echo process in Tm-doped YAG at 793 nm. Single-pulse temporal compression by almost a. factor of 500 from 10 mu s to 22 ns and pulse train compression by a factor of 14 from 5 mu s to 350 ns with a high-speed frequency-tunable external-cavity diode laser are demonstrated. It is suspected that significantly higher compression could be obtained by improved control of the laser frequency and laser frequency chirps. Theoretically, Tm-doped YAG should be capable of compressing single pulses by almost a factor of 10(7)
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