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Search Results: 1 - 10 of 10639 matches for " Andreas Velten "
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Reconstruction of hidden 3D shapes using diffuse reflections
Otkrist Gupta,Andreas Velten,Thomas Willwacher,Ashok Veeraraghavan,Ramesh Raskar
Computer Science , 2012, DOI: 10.1364/OE.20.019096
Abstract: We analyze multi-bounce propagation of light in an unknown hidden volume and demonstrate that the reflected light contains sufficient information to recover the 3D structure of the hidden scene. We formulate the forward and inverse theory of secondary and tertiary scattering reflection using ideas from energy front propagation and tomography. We show that using careful choice of approximations, such as Fresnel approximation, greatly simplifies this problem and the inversion can be achieved via a backpropagation process. We provide a theoretical analysis of the invertibility, uniqueness and choices of space-time-angle dimensions using synthetic examples. We show that a 2D streak camera can be used to discover and reconstruct hidden geometry. Using a 1D high speed time of flight camera, we show that our method can be used recover 3D shapes of objects "around the corner".
High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large Tunability
Andreas Schmitt-Sody,Andreas Velten,Ye Liu,Ladan Arissian,Jean-Claude Diels
International Journal of Optics , 2008, DOI: 10.1155/2008/865092
Abstract: We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth) and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature.
Viscous Cold Dark Matter in agreement with observations
Hermano Velten
Physics , 2013,
Abstract: We discuss bulk viscous cosmological models. Since the bulk viscous pressure is negative, viable viscous cosmological scenarios with late time accelerated expansion can in principle be constructed. After discussing some alternative models based on bulk viscous effects we will focus on a model very similar to the standard $\Lambda$CDM. We argue that a $\Lambda${\rm v}CDM model, where we assign a very small (albeit perceptible) bulk viscosity to dark matter is in agreement with available cosmological observations. Hence, we work with the concept of viscous Cold Dark Matter ({\rm v}CDM). At the level of the perturbations, the growth of {\rm v}CDM structures is slightly suppressed when compared with the standard CDM ones. Having in mind that the small scale problems of the $\Lambda$CDM model are related to an excess of clustering, our proposal seems to indicate a possible direction for solving the serious drawbacks of the CDM paradigm within the standard cosmological model.
Improving the Dietary Protein Quality by Amino Acid Fortification with a High Inclusion Level of Micro Algae (Spirulina platensis) or Insect Meal (Hermetia illucens) in Meat Type Chicken Diets  [PDF]
Carmen Neumann, Susanne Velten, Frank Liebert
Open Journal of Animal Sciences (OJAS) , 2018, DOI: 10.4236/ojas.2018.81002
Abstract: The objective of this study was to measure protein quality parameters (PPV, NPU and NPUstd) of chicken diets with complete substitution of soybean meal (SBM) by Spirulina meal (SM) or partly defatted Hermetia meal (HM). N balance experiments were based on the quantitative excreta collection method, divided into starter period (10 - 20 d) and grower period (25 - 35 d). The study utilized 70 all male meat type chicken (Ross 308). Data assessment applied the exponential N utilization model of the “Goettingen approach”. The control diet was based on wheat, corn and SBM. In four experimental diets SBM was completely substituted by SM or HM, but fortified with feed amino acids (AA) both on a basic level of supplementation (Lys and Met added equal to the control diet) and on an extended level (Lys, Met, Thr, Arg, Val, Ile, His added). At a basic level of AA supplementation, complete replacement of SBM by SM or HM in chicken diets depressed dietary protein quality significantly (p < 0.05). However, the extended level of AA supplementation improved protein quality parameters of the diets with both of the alternative proteins significantly (p < 0.05), but still generally not on par with the control diet. The observed responses were accentuated when the well-known effect of N intake on protein utilization was eliminated through the standardization of N intake by application of the “Goettingen approach”.
The Graded Inclusion of Algae (Spirulina platensis) or Insect (Hermetia illucens) Meal as a Soybean Meal Substitute in Meat Type Chicken Diets Impacts on Growth, Nutrient Deposition and Dietary Protein Quality Depending on the Extent of Amino Acid Supplementation  [PDF]
Carmen Neumann, Susanne Velten, Frank Liebert
Open Journal of Animal Sciences (OJAS) , 2018, DOI: 10.4236/ojas.2018.82012
Abstract: Three consecutive growth experiments were conducted to evaluate growth performance, whole body analyses and protein quality parameters from chicken diets with 50%, 75% and 100% substitution of soybean meal (SBM) by Spirulina meal (SM) or partly defatted Hermetia meal (HM). Each of the experiments was divided into a starter period (1 - 21 d) and a grower period (22 - 34 d). One-day-old male growing chickens (Ross 308) were randomly allotted to 48 floor pens making use of 6 birds/pen (Exp.1) or 7 birds/pen (Exp. 2, 3), and the experiments included a control diet (n = 12) and four experimental diets (n = 9). Experiment 1 examined a 50 % replacement of SBM by the alternative proteins under study, both on a basic and an advanced level of amino acid (AA) fortification to meet the recommended ideal amino acid ratio (IAAR). In experiment 2, 75% (starter diet) and 50% (grower diet) replacement of SBM was investigated. Experiment 3 investigated the effects of complete SBM substitution by SM or HM in starter and grower diets. In the second and third experiment diets with both of the alternative proteins and the control diet were AA supplemented to meet the current IAAR. In a further step, the calculated first limiting AA (LAA) was reduced to 80% of its requirement recommendation to allow for further evaluation of the individual AA efficiency according to the Goettingen approach. Different levels (50%, 75%, or 100%) of replacing SBM by HM or SM in chicken diets depressed dietary protein quality (p <
CpG oligonucleotide activates Toll-like receptor 9 and causes lung inflammation in vivo
Pascal Knuefermann, Georg Baumgarten, Alexander Koch, Markus Schwederski, Markus Velten, Heidi Ehrentraut, Jan Mersmann, Rainer Meyer, Andreas Hoeft, Kai Zacharowski, Christian Grohé
Respiratory Research , 2007, DOI: 10.1186/1465-9921-8-72
Abstract: Wild-type (WT) and TLR9-deficient (TLR9-D) mice received CpG-ODN intraperitoneally (1668-Thioat, 1 nmol/g BW) and were observed for up to 6 hrs. Lung tissue and plasma samples were taken and various inflammatory markers were measured.In WT mice, CpG-ODN induced a strong activation of pulmonary NFκB as well as a significant increase in pulmonary TNF-α and IL-1β mRNA/protein. In addition, cytokine serum levels were significantly elevated in WT mice. Increased pulmonary content of lung myeloperoxidase (MPO) was documented in WT mice following application of CpG-ODN. Bronchoalveolar lavage (BAL) revealed that CpG-ODN stimulation significantly increased total cell number as well as neutrophil count in WT animals. In contrast, the CpG-ODN-induced inflammatory response was abolished in TLR9-D mice.This study suggests that bacterial CpG-ODN causes lung inflammation via TLR9.Acute lung injury (ALI) or its severe form, the acute respiratory distress syndrome (ARDS) remains a major health problem. Recent studies have estimated the incidence of these conditions to be between 15 and 34 cases per 100,000 inhabitants per year showing an overall mortality rate of 30–40% [1-3]. Depending on the underlying etiologies ARDS can be differentiated into a direct (pulmonary) and an indirect (extrapulmonary) form (for details see [4]).ALI/ARDS are quite common in patients with sepsis [5] and sepsis-associated ARDS carries the highest mortality rates. Despite advances in the supportive care and mechanical ventilation strategies of ALI/ARDS, mortality rates remain unacceptably high [6-8]. As the pathophysiology of the disease is not fully understood, the treatment remains mainly supportive [9-13].Experimental models of sepsis show that bacteria and bacterial cell components induce the expression of inflammatory mediators in various tissues as well as in the blood stream [14-17]. Among these mediators, proinflammatory cytokines are regarded as a major cause for the development of organ dysfunc
Albert Ellis (1913-2007)
Leonor Lega,Emmett Velten
Revista Latinoamericana de Psicología , 2008,
Power spectrum for the Bose-Einstein condensate dark matter
Hermano Velten,Etienne Wamba
Physics , 2011, DOI: 10.1016/j.physletb.2012.01.071
Abstract: We assume that dark matter is composed of scalar particles that form a Bose-Einstein condensate (BEC) at some point during the cosmic evolution. Afterwards, cold dark matter is in the form of a condensate and behaves slightly different from the standard dark matter component. We study the large scale perturbative dynamics of the BEC dark matter in a model where this component coexists with baryonic matter and cosmological constant. The perturbative dynamics is studied using neo- Newtonian cosmology (where the pressure is dynamically relevant for the homogeneous and isotropic background) which is assumed to be correct for small values of the sound speed. We show that BEC dark matter effects can be seen in the matter power spectrum if the mass of the condensate particle lies in the range 15meV < m < 700meV leading to a small, but perceptible, excess of power at large scales.
Exploring non-linear cosmological matter diffusion coefficients
Hermano Velten,Simone Calogero
Physics , 2014,
Abstract: Since microscopic velocity diffusion can be incorporated into general relativity in a consistent way, we study cosmological background solutions when the diffusion phenomena takes place in an expanding universe. Our focus here relies on the nature of the diffusion coefficient $\sigma$ which measures the magnitude of such transport phenomena. We test dynamics where $\sigma$ has a phenomenological dependence on the scale factor, the matter density, the dark energy and the expansion rate.
Cosmology with matter diffusion
Simone Calogero,Hermano Velten
Physics , 2013, DOI: 10.1088/1475-7516/2013/11/025
Abstract: We construct a viable cosmological model based on velocity diffusion of matter particles. In order to ensure the conservation of the total energy-momentum tensor in the presence of diffusion, we include a cosmological scalar field $\phi$ which we identify with the dark energy component of the Universe. The model is characterized by only one new degree of freedom, the diffusion parameter $\sigma$. The standard $\Lambda$CDM model can be recovered by setting $\sigma=0$. If diffusion takes place ($\sigma >0$) the dynamics of the matter and of the dark energy fields are coupled. We argue that the existence of a diffusion mechanism in the Universe can serve as a theoretical motivation for interacting models. We constrain the background dynamics of the diffusion model with Supernovae, H(z) and BAO data. We also perform a perturbative analysis of this model in order to understand structure formation in the Universe. We calculate the impact of diffusion both on the CMB spectrum, with particular attention to the integrated Sachs-Wolfe signal, and on the matter power spectrum $P(k)$. The latter analysis places strong constraints on the magnitude of the diffusion mechanism but does not rule out the model.
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