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Search Results: 1 - 10 of 138769 matches for " K. Siegl "
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Dietary patterns of infant and preschool children in Mwingi and Makueni districts of Ukambani region, eastern Kenya.
M Ndiku, K Jaceldo-Siegl, J Sabaté
African Journal of Food, Agriculture, Nutrition and Development , 2010,
Abstract: A cross -sectional study was conducted in the Ukambani region of eastern Kenya to describe dietary patterns of infants and preschool children. The purpose of the study was to provide region specific data on dietary patterns of children living in Mwingi (MW) a region that mainly grows pearl millet and Makueni (MA), a region that grows maize. A modified rapid, knowledge, practice and coverage (KPC) questionnaire and a 24-hr dietary recall were used to collect the data. A total of 403 households (201 – MW, 202 – MA) were surveyed from four randomly selected divisions of MW and MA districts. This yielded 629 surrogate 24-hr dietary recalls with 314 children from MW district and 315 children from MA district (49% boys and 51% girls). Intake of nutrients and food groups were compared between the two districts using t- test. On average, grains contributed 62-68 percent of total energy intake in both districts. Mean daily energy intake (mean ±SD) for all the children was 1056 ± 553 Kcal. Daily energy intake (1130 ± 595 Kcal) in MW children was 15% higher compared to MA children (983 ± 499 Kcal, p = 0.002). Boys had a 12% higher daily energy intake than girls (p = 0.005). The contribution to total energy from grains was 27% higher in MW children (p = 0.0001) and breast milk contribution to total energy intake was 50% less in MW children (p < 0.001). Consumption of fruits and vegetables was significantly lower in MW children (p<0.0001). Intakes of carbohydrate, protein and iron were higher in MW children and vitamin A intake was lower. Fat intake was the same in both districts for these children. Gender and geographical differences were observed in diets of children in Ukambani region, with the most prominent being the type and amount of cereal intake.
Florian Siegl
Eesti ja soome-ugri keeleteaduse ajakiri , 2012,
Abstract: In this paper linguistic traces of the Enets’ migration to the Taimyr Peninsula are addressed. Special attention is paid to Forest Enets–Ket contacts and a tentative etymology for the (Forest) Enets’ ethnonym for Kets and Selkups is offered. Of special importance is a likely Enets place name in Northern Evenkija, an area from which no Enets place names have been reported earlier. As the same area is inhabited by speakers of the northern dialect of Ket, this area should be seen as a possible contact area for the unusual case of pronoun borrowing in Forest Enets as discussed in Siegl (2008).
Surprising spectra of PT-symmetric point interactions
Petr Siegl
Physics , 2009,
Abstract: Spectra of the second derivative operators corresponding to the special PT-symmetric point interactions are studied. The results are partly the completion of those obtained in [1]. The particular PT-symmetric point interactions causing unusual spectral effects are investigated for the systems defined on a finite interval as well. The spectrum of this type of interactions is very far from the self-adjoint case despite of PT-symmetry, P-pseudo-Hermiticity and T-self-adjointness.
Imbalanced Oxidative Stress Causes Chlamydial Persistence during Non-Productive Human Herpes Virus Co-Infection
Bhupesh K. Prusty, Linda B?hme, Birgit Bergmann, Christine Siegl, Eva Krause, Adrian Mehlitz, Thomas Rudel
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047427
Abstract: Both human herpes viruses and Chlamydia are highly prevalent in the human population and are detected together in different human disorders. Here, we demonstrate that co-infection with human herpes virus 6 (HHV6) interferes with the developmental cycle of C. trachomatis and induces persistence. Induction of chlamydial persistence by HHV6 is independent of productive virus infection, but requires the interaction and uptake of the virus by the host cell. On the other hand, viral uptake is strongly promoted under co-infection conditions. Host cell glutathione reductase activity was suppressed by HHV6 causing NADPH accumulation, decreased formation of reduced glutathione and increased oxidative stress. Prevention of oxidative stress restored infectivity of Chlamydia after HHV6-induced persistence. We show that co-infection with Herpes simplex virus 1 or human Cytomegalovirus also induces chlamydial persistence by a similar mechanism suggesting that Chlamydia -human herpes virus co-infections are evolutionary shaped interactions with a thus far unrecognized broad significance.
Using the One-Lung Method to Link p38 to Pro-Inflammatory Gene Expression during Overventilation in C57BL/6 and BALB/c Mice
Stephanie Siegl, Stefan Uhlig
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0041464
Abstract: Introduction The mechanisms of ventilator-induced lung injury (VILI), including the role of MAP kinases, are frequently studied in different mouse strains. A useful model for such studies is the isolated perfused mouse lung. As a further development we present the one-lung method that permits to continue perfusion and ventilation of the right lung after removal of the left lung. This method was used to compare the effect of high pressure ventilation (HPV) on pro-inflammatory signaling events in two widely used mouse strains (C57BL/6, BALB/c) and to further define the role of p38 in VILI. Methods Lungs were perfused and ventilated for 30 min under control conditions before they were randomized to low (8 cm H2O) or high (25 cm H2O) pressure ventilation (HPV) for 210 min, with the left lung being removed after 180 min. In the left lung we measured the phosphorylation of p38, JNK, ERK and Akt kinase, and in the right lung gene expression and protein concentrations of Il1b, Il6, Tnf, Cxcl1, Cxcl2, and Areg. Results Lung mechanics and kinase activation were similar in both mouse strains. HPV increased all genes (except Tnf in BALB/c) and all mediators in both strains. The gene expression of mRNA for Il1b, Il6, Cxcl1 and Cxcl2 was higher in BALB/c mice. Backward regression of the kinase data at t = 180 min with the gene and protein expression data at t = 240 min suggested that p38 controls HPV-induced gene expression, but not protein production. This hypothesis was confirmed in experiments with the p38-kinase inhibitor SB203580. Conclusions The one-lung method is useful for mechanistic studies in the lungs. While C57BL/6 show diminished pro-inflammatory responses during HPV, lung mechanics and mechanotransduction processes appear to be similar in both mouse strains. Finally, the one-lung method allowed us to link p38 to gene expression during VILI.
Selected basis for PAR reduction in multi-user downlink scenarios using lattice-reduction-aided precoding
Siegl Christian,Fischer Robert
EURASIP Journal on Advances in Signal Processing , 2011,
Abstract: The application of OFDM within a multi-user downlink scenario is considered. Thereby, two problems occur. First, due to OFDM, the transmit signal exhibits a large peak-to-average power ratio (PAR). Second, the multi-user interferences have to be equalized (or precoded) at the transmitter side. In this article, we address combined precoding and PAR reduction. As precoding schemes sorted Tomlinson-Harashima precoding (sTHP) and its lattice-reduction-aided variant (LRA-THP) are considered. In order to reduce the PAR, we review the scheme selected sorting (SLS), which is a combined approach of PAR reduction and precoding with sTHP. Based on this idea, the novel PAR reduction scheme selected basis (SLB) is introduced which combines PAR reduction with the precoding approach LRA-THP. It can be shown that SLB achieves very good PAR reduction performance and hardly influences the error performance. Both schemes, SLB and SLS, are compared with simplified selected mapping (sSLM), the only PAR reduction scheme from the SLM family, which can be applied in multi-user downlink scenarios. The comparison is done on the basis that the respective schemes exhibit the same computational complexity. In terms of PAR reduction performance, it turns out that sSLM outperforms SLS, whereas the performance of sSLM and SLB is similar. Noteworthy, the great benefit of SLB or SLS is that no side information has to be communicated to the receiver as it is necessary with sSLM. Moreover, using SLB, full diversity error rate performance is possible with only low-PAR transmit signals.
Partial Transmit Sequences for Peak-to-Average Power Ratio Reduction in Multiantenna OFDM
Siegl Christian,Fischer RobertFH
EURASIP Journal on Wireless Communications and Networking , 2008,
Abstract: The major drawback of orthogonal frequency-division multiplexing (OFDM) is its high peak-to-average power ratio (PAR), which gets even more substantial if a transmitter with multiple antennas is considered. To overcome this problem, in this paper, the partial transmit sequences (PTS) method—well known for PAR reduction in single antenna systems—is studied for multiantenna OFDM. A directed approach, recently introduced for the competing selected mapping (SLM) method, proves to be very powerful and able to utilize the potential of multiantenna systems. To apply directed PTS, various variants for providing a sufficiently large number of alternative signal superpositions (the candidate transmit signals) are discussed. Moreover, affording the same complexity, it is shown that directed PTS offers better performance than SLM. Via numerical simulations, it is pointed out that due to its moderate complexity but very good performance, directed or iterated PTS using combined weighting and temporal shifting is a very attractive candidate for PAR reduction in future multiantenna OFDM schemes.
Bifurcation of nonlinear eigenvalues in problems with antilinear symmetry
Tomas Dohnal,Petr Siegl
Physics , 2015,
Abstract: Many physical systems can be described by nonlinear eigenvalues and bifurcation problems with a linear part that is non-selfadjoint e.g. due to the presence of loss and gain. The balance of these effects is reflected in an antilinear symmetry, like e.g. the PT-symmetry, of the problem. Under this condition we show that the nonlinear eigenvalues bifurcating from real linear eigenvalues remain real and the corresponding nonlinear eigenfunctions remain symmetric. The abstract results are applied in a number of physical models of Bose-Einstein condensation, nonlinear optics and superconductivity, and further numerical analysis is performed.
Hydrogen atom in space with a compactified extra dimension and potential defined by Gauss' law
Martin Bure?,Petr Siegl
Physics , 2014, DOI: 10.1016/j.aop.2014.12.017
Abstract: We investigate the consequences of one extra spatial dimension for the stability and energy spectrum of the non-relativistic hydrogen atom with a potential defined by Gauss' law, i.e. proportional to $1/|x|^2$. The additional spatial dimension is considered to be either infinite or curled-up in a circle of radius $R$. In both cases, the energy spectrum is bounded from below for charges smaller than the same critical value and unbounded from below otherwise. As a consequence of compactification, negative energy eigenstates appear: if $R$ is smaller than a quarter of the Bohr radius, the corresponding Hamiltonian possesses an infinite number of bound states with minimal energy extending at least to the ground state of the hydrogen atom.
On the metric operator for the imaginary cubic oscillator
Petr Siegl,David Krejcirik
Physics , 2012, DOI: 10.1103/PhysRevD.86.121702
Abstract: We show that the eigenvectors of the PT-symmetric imaginary cubic oscillator are complete, but do not form a Riesz basis. This results in the existence of a bounded metric operator having intrinsic singularity reflected in the inevitable unboundedness of the inverse. Moreover, the existence of non-trivial pseudospectrum is observed. In other words, there is no quantum-mechanical Hamiltonian associated with it via bounded and boundedly invertible similarity transformations. These results open new directions in physical interpretation of PT-symmetric models with intrinsically singular metric, since their properties are essentially different with respect to self-adjoint Hamiltonians, for instance, due to spectral instabilities.
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