Superposition in nonlinear wave and evolution equations

Real and bounded elliptic solutions suitable for applying the Khare-Sukhatme superposition procedure are presented and used to generate superposition solutions of the generalized modified Kadomtsev-Petviashvili equation (gmKPE) and the nonlinear cubic-quintic Schroedinger equation (NLCQSE).Comment: submitted to International Journal of Theoretical Physics, 23 pages, 2 figures, style change

Spinal stabilization for patients with metastatic lesions of the spine using a titanium spacer

Anterior decompression in spinal metastases of the corporal type with impending (n=5) or present (n=36) neurological complications was performed in 41 patients. For reconstruction, a titanium cylinder was inserted after spondylectomy and augmented with an anterior plate. The titanium implant can easily be adjusted to the length needed without necessitating expensive additional equipment. Outside the patient the implant is filled with polymethylmetacrylate, facilitating plate transfixation for rotational locking. There was a 30-day mortality of 9.7%. Pain relief was apparent in 38 of 41 patients (92.7%), and motor improvement was manifest in 31 of 35 cases (88.6%). Six patients did not present with any neurological symptoms pre- or postoperatively. Neurological deterioration was registered in only 1 case (2.4%). Surgical efficacy was maintained until the death of the patients. Though tumor recurrence at a different spinal level led to consecutive surgery in 5 patients, no implant dislocation occurred during the observation period (maximum 44 months), characterizing the procedure as a mechanically reliable and safe technique

Bias Analysis in Entropy Estimation

We consider the problem of finite sample corrections for entropy estimation. New estimates of the Shannon entropy are proposed and their systematic error (the bias) is computed analytically. We find that our results cover correction formulas of current entropy estimates recently discussed in literature. The trade-off between bias reduction and the increase of the corresponding statistical error is analyzed.Comment: 5 pages, 3 figure

Experimental investigations on the fatigue resistance of automatically welded tubular X-joints for jacket support structures

The development within the offshore wind sector towards more powerful turbines combined with increasing water depth for new wind parks is challenging both the designer as well as the manufacturer of bottom fixed support structures. Besides XL-monopiles, the market developed an innovative and economic jacket support structure which is based on automatically manufactured tubular joints combined with standardized pipes. Besides the improvements for a serial manufacturing process the automatically welded tubular joints show a great potential in terms of fatigue resistance e.g. due to a smooth weld geometry without sharp notches. However, these benefits are not considered yet within the fatigue design process of automatically manufactured jacket substructures according to current standards due to the lack of suitable S-N curves. Therefore, 32 axial fatigue tests on single and double-sided automatically welded tubular X-joints have been performed to determine a new hot spot stress related S-N curve. Based on these constant amplitude fatigue tests a new S-N curve equal to a FAT 126 curve was computed which implicitly includes the benefits of the automatically welding procedure. © Published under licence by IOP Publishing Ltd

Health effects of WiFi radiation: a review based on systematicquality evaluation

Although WiFi contributes little to totalradiofrequency electromagnetic field (RF-EMF) exposure in our everyday environ-ment, concern has raised whether this spe-cific type of modulated RF-EMF causeshealth problems. The aim of this review isto evaluate all types of studies that investi-gated biological and health effects of WiFiexposure and fulfilled basic quality criteria.Eligible for inclusion were epidemiological,human experimental,in vivoandin vitrostudies using realistic WiFi exposure set-tings. We conducted a systematic literaturesearch for all papers published betweenJanuary 1997 and August 2020 followed by a quality review addressing blinding and dosimetry inexperimental studies and various types of biases in epidemiological studies. All studies fulfilling thequality criteria were descriptively summarized in terms of observation or absence of associations.From 1385 articles identified by the literature search, 23 fulfilled basic quality criteria: 6 epidemio-logical papers, 6 human experimental articles, 9in vivoarticles, and 2in vitroarticles. Whereasinvivoandin vitrostudies applied exposure levels up to 4 W/kg, human studies dealt with exposurelevels several orders of magnitude below the ICNIRP guidelines, which are typical for WiFi exposuresituations in the everyday environment. Numerous outcomes ranging from biological markers tosymptoms were mostly found not to be associated with WiFi exposure. Sporadic findings were notconsistent in terms of outcomes or exposure-response associations. This review based on a system-atic literature search and quality evaluation does not suggest detrimental health effects from WiFiexposure below regulatory limits

A note on entropic uncertainty relations of position and momentum

We consider two entropic uncertainty relations of position and momentum recently discussed in literature. By a suitable rescaling of one of them, we obtain a smooth interpolation of both for high-resolution and low-resolution measurements respectively. Because our interpolation has never been mentioned in literature before, we propose it as a candidate for an improved entropic uncertainty relation of position and momentum. Up to now, the author has neither been able to falsify nor prove the new inequality. In our opinion it is a challenge to do either one.Comment: 2 pages, 2 figures, 2 references adde

Soil fertility management for organic rice production in the Lao PDR

Rice is the most important agricultural commodity of the Lao People's Democratic Republic (Lao PDR), produced largely using traditional methods with limited inputs of fertilizers and other chemicals. The country has a wide diversity in rice production systems and rice varieties, with over 3000 different varieties recorded. The rich diversity and the production environment and methods are favorable for organic rice production. Investigations were carried out to describe soil fertility conditions, management practices, opportunities and problems associated with organic production methods for rice. Soils used for rice production are mostly of low fertility, with low organic matter and N-availability. In spite of this, virtually no fertilizer inputs are used for upland rice production. Inorganic fertilizer inputs for lowland rice production have increased rapidly over the past decade, but are still below 20 kg ha−1. The most important nutrient sources are rice straw and manure from buffalo and cattle. Chromolaena odorata plays an important role in nutrient cycling in upland rice systems and is sometimes added to lowland fields. In a range of fertility management studies, yield increase ranged from 2 to 89% for manure, straw or rice husk applied at modest rates (3 t ha−1), 32-156% for modest rates of inorganic fertilizer (60 kg N ha−1) and 36-167% for combined application of manure or crop residues with inorganic fertilizer. The response to locally produced commercial organic fertilizer was poor. The most promising inputs and strategies available to optimize yields in organic rice production systems are (1) optimizing use of locally available nutrients, mostly from manure, crop residues and weed biomass, (2) N addition through green manure and legumes growing in rotation and (3) additions of P through guano or rock-phosphate. The Lao PDR is fortunate to have substantial bat guano deposits in limestone caves. Extensive experience is available on straw and husk management for lowland systems and green manure species for upland production system

Risk-aware motion planning for automated vehicle among human-driven cars

We consider the maneuver planning problem for automated vehicles when they share the road with human-driven cars and interact with each other using a finite set of maneuvers. Each maneuver is calculated considering input constraints, actuator disturbances and sensor noise, so that we can use a maneuver automaton to perform higher-level planning that is robust against lower-level effects. In order to model the behavior of human-driven cars in response to the intent of the automated vehicle, we use control improvisation to build a probabilistic model. To accommodate for potential mismatches between the learned human model and human driving behaviors, we use a conditional value-at-risk objective function to obtain the optimal policy for the automated vehicle. We demonstrate through simulations that our motion planning framework consisting of an interactive human driving model and risk-aware motion planning strategy makes it possible to adapt to different traffic conditions and confidence levels

Random perfect lattices and the sphere packing problem

Motivated by the search for best lattice sphere packings in Euclidean spaces of large dimensions we study randomly generated perfect lattices in moderately large dimensions (up to d=19 included). Perfect lattices are relevant in the solution of the problem of lattice sphere packing, because the best lattice packing is a perfect lattice and because they can be generated easily by an algorithm. Their number however grows super-exponentially with the dimension so to get an idea of their properties we propose to study a randomized version of the algorithm and to define a random ensemble with an effective temperature in a way reminiscent of a Monte-Carlo simulation. We therefore study the distribution of packing fractions and kissing numbers of these ensembles and show how as the temperature is decreased the best know packers are easily recovered. We find that, even at infinite temperature, the typical perfect lattices are considerably denser than known families (like A_d and D_d) and we propose two hypotheses between which we cannot distinguish in this paper: one in which they improve Minkowsky's bound phi\sim 2^{-(0.84+-0.06) d}, and a competitor, in which their packing fraction decreases super-exponentially, namely phi\sim d^{-a d} but with a very small coefficient a=0.06+-0.04. We also find properties of the random walk which are suggestive of a glassy system already for moderately small dimensions. We also analyze local structure of network of perfect lattices conjecturing that this is a scale-free network in all dimensions with constant scaling exponent 2.6+-0.1.Comment: 19 pages, 22 figure