Charting the Algorithmic Complexity of Waypoint Routing

Modern computer networks support interesting new routing models in which traffic flows from a source sto a destination t can be flexibly steered through a sequence of waypoints, such as (hardware) middleboxes or (virtualized) network functions (VNFs), to create innovative network services like service chains or segment routing. While the benefits and technological challenges of providing such routing models have been articulated and studied intensively over the last years, less is known about the underlying algorithmic traffic routing problems. The goal of this paper is to provide the network community with an overview of algorithmic techniques for waypoint routing and also inform about limitations due to computational hardness. In particular, we put the waypoint routing problem into perspective with respect to classic graph theoretical problems. For example, we find that while computing a shortest path from a source s to a destination t is simple (e.g., using Dijkstra's algorithm), the problem of finding a shortest route from s to t via a single waypoint already features a deep combinatorial structure.</jats:p

Assessment of uncertainties in a complex modeling chain for predicting reservoir sedimentation under changing climate

Long-term predictions of reservoir sedimentation require an objective consideration of the preceding catchment processes. In this study, we apply a complex modeling chain to predict sedimentation processes in the Banja reservoir (Albania). The modeling chain consists of the water balance model WaSiM, the soil erosion and sediment transport model combination RUSLE-SEDD, and the 3d hydro-morphodynamic reservoir model SSIIM2 to accurately represent all relevant physical processes. Furthermore, an ensemble of climate models is used to analyze future scenarios. Although the capabilities of each model enable us to obtain satisfying results, the propagation of uncertainties in the modeling chain cannot be neglected. Hence, approximate model parameter uncertainties are quantified with the First-Order Second-Moment (FOSM) method. Another source of uncertainty for long-term predictions is the spread of climate projections. Thus, we compared both sources of uncertainties and found that the uncertainties generated by climate projections are 408% (for runoff), 539% (for sediment yield), and 272% (for bed elevation in the reservoir) larger than the model parameter uncertainties. We conclude that (i) FOSM is a suitable method for quantifying approximate parameter uncertainties in a complex modeling chain, (ii) the model parameter uncertainties are smaller than the spread of climate projections, and (iii) these uncertainties are of the same order of magnitude as the change signal for the investigated low-emission scenario. Thus, the proposed method might support modelers to communicate different sources of uncertainty in complex modeling chains, including climate impact models

Bovine polledness

The persistent horns are an important trait of speciation for the family Bovidae with complex morphogenesis taking place briefly after birth. The polledness is highly favourable in modern cattle breeding systems but serious animal welfare issues urge for a solution in the production of hornless cattle other than dehorning. Although the dominant inhibition of horn morphogenesis was discovered more than 70 years ago, and the causative mutation was mapped almost 20 years ago, its molecular nature remained unknown. Here, we report allelic heterogeneity of the POLLED locus. First, we mapped the POLLED locus to a ∼381-kb interval in a multi-breed case-control design. Targeted re-sequencing of an enlarged candidate interval (547 kb) in 16 sires with known POLLED genotype did not detect a common allele associated with polled status. In eight sires of Alpine and Scottish origin (four polled versus four horned), we identified a single candidate mutation, a complex 202 bp insertion-deletion event that showed perfect association to the polled phenotype in various European cattle breeds, except Holstein-Friesian. The analysis of the same candidate interval in eight Holsteins identified five candidate variants which segregate as a 260 kb haplotype also perfectly associated with the POLLED gene without recombination or interference with the 202 bp insertion-deletion. We further identified bulls which are progeny tested as homozygous polled but bearing both, 202 bp insertion-deletion and Friesian haplotype. The distribution of genotypes of the two putative POLLED alleles in large semi-random sample (1,261 animals) supports the hypothesis of two independent mutations

Soilless Tomato Production: Effects of Hemp Fiber and Rock Wool Growing Media on Yield, Secondary Metabolites, Substrate Characteristics and Greenhouse Gas Emissions

Replacement of rock wool by organic substrates is considered to reduce the environmental impact, e.g., through energy savings during production and waste prevention, caused by hydroponically produced crops. A suitable substrate for plant production is characterized by an optimal composition of air- and water-filled pores. In our study, we used hemp fibers as an organic alternative to rock wool in order to cultivate tomato plants in hydroponics for 36 weeks. The leaf area, plant length, and yields, as well as the quality of fruits including soluble solid contents, dry weight content, mineral composition, and contents of phenolic compounds caused by both substrates, were similar. Carotenoids were significantly increased in fruits from plants grown in hemp at some measuring dates. Nevertheless, higher emission rates of greenhouse gases such as N2O, CO2, and CH4 caused by hemp fiber compared to those emitted by rock wool during use are rather disadvantageous for the environment. While hemp proved to be a suitable substrate in terms of some physical properties (total pore volume, bulk density), a lower volume of air and easily available water as well as very rapid microbial decomposition and the associated high nitrogen immobilization must be considered as disadvantages.Peer Reviewe

The influence of orthopedic corsets on the incidence of pathological fractures in patients with spinal bone metastases after radiotherapy

Background: Clinical care of unstable spinal bone metastases in many centers often includes patient immobilization by means of an orthopedic corset in order to prevent pathological fractures. The aim of this retrospective analysis was to evaluate the incidence of pathological fractures after radiotherapy (RT) in patients with and without orthopedic corsets and to assess prognostic factors for pathological fractures in patients with spinal bone metastases. Methods: The incidence of pathological fractures in 915 patients with 2.195 osteolytic metastases in the thoracic and lumbar spine was evaluated retrospectively on the basis of computed tomography (CT) scans between January 2000 and January 2012 depending on prescription and wearing of patient-customized orthopedic corsets. Results: In the corset group, 6.8 and 8.0 % in no-corset group showed pathological fractures prior to RT, no significant difference between groups was detected (p = 0.473). After 6 months, patients in the corset group showed pathological fractures in 8.6 % and in no-corset group in 9.3 % (p = 0.709). The univariate and bivariate analyses demonstrated no significant prognostic factor for incidence of pathological fractures in both groups. Conclusions: In this analysis, we could show for the first time in more than 900 patients, that abandoning a general corset supply in patients with spinal metastases does not significantly cause increased rates of pathological fractures. Importantly, the incidence of pathological fracture after RT was small

Spectroscopic study of the magnetic ground state of Nb1−y_{1-y}Fe2+y_{2+y}

We have investigated single crystals and polycrystals from the series Nb$_{1-y}$Fe$_{2+y}$, $-0.004 \leq y \leq 0.018$ by electron spin resonance, muon spin relaxation and M\"ossbauer spectroscopy. Our data establish that at lowest temperatures all samples exhibit bulk magnetic order. Slight Fe-excess induces low-moment ferromagnetism, consistent with bulk magnetometry ($\simeq 0.06 ~\mu_B/{\rm Fe}$), Nb--rich and stoichiometric NbFe$_2$ display spin density wave order with small magnetic moment amplitudes of the order $\sim 0.001 - 0.01 ~\mu_B/{\rm Fe}$. This provides microscopic evidence for a modulated magnetic state on the border of ferromagnetism in NbFe$_2$.Comment: 7 pages, 9 figure