Minimal mechanisms for vegetation patterns in semiarid regions

The minimal ecological requirements for formation of regular vegetation patterns in semiarid systems have been recently questioned. Against the general belief that a combination of facilitative and competitive interactions is necessary, recent theoretical studies suggest that, under broad conditions, nonlocal competition among plants alone may induce patterns. In this paper, we review results along this line, presenting a series of models that yield spatial patterns when finite-range competition is the only driving force. A preliminary derivation of this type of model from a more detailed one that considers water-biomass dynamics is also presented. Keywords: Vegetation patterns, nonlocal interactionsComment: 8 pages, 4 figure

Vegetation pattern formation in semiarid systems without facilitative mechanisms

Regular vegetation patterns in semiarid ecosystems are believed to arise from the interplay between long-range competition and facilitation processes acting at smaller distances. We show that, under rather general conditions, long-range competition alone may be enough to shape these patterns. To this end we propose a simple, general model for the dynamics of vegetation, which includes only long-range competition between plants. Competition is introduced through a nonlocal term, where the kernel function quantifies the intensity of the interaction. We recover the full spectrum of spatial structures typical of vegetation models that also account for facilitation in addition to competition.Comment: 21 pages, 3 figure

Optimization of the investment casting process

Rapid prototyping is an important technique for manufacturing. This work refers to the manufacture of hollow patterns made of polymeric materials by rapid prototyping technologies for its use in the preparation of ceramic molds in the investment casting process. This work is focused on the development of a process for manufacturing patterns different from those that currently exist due to its hollow interior design, allowing its direct use in the fabrication of ceramic molds; avoiding cracking and fracture during the investment casting process, which is an important process for the foundry industry

Optimiranje postupka kalupljenja u ljevačkom procesu

Rapid prototyping is an important technique for manufacturing. This work refers to the manufacture of hollow patterns made of polymeric materials by rapid prototyping technologies for its use in the preparation of ceramic molds in the investment casting process. This work is focused on the development of a process for manufacturing patterns different from those that currently exist due to its hollow interior design, allowing its direct use in the fabrication of ceramic molds; avoiding cracking and fracture during the investment casting process, which is an important process for the foundry industry.Brzo razvijanje prototipa važna je proizvodna tehnika. Ovaj se rad odnosi na proizvodnju šupljih kalupa izrađenih od polimerskih materijala pomoću tehnologija brzog razvijanja prototipa za uporabu u izradi keramičkih modela u postupku kalupljenja ljevačkog procesa. Ovaj rad je usmjeren na razvijanje postupka za proizvodnju kalupa drukčijih od onih kakvi trenutno postoje i to zbog svoje šuplje unutarnje izvedbe čime se omogućava izravna uporaba u izradi keramičkih modela te se izbje gava pucanje i lom tijekom postupka kalupljenja ljevačkog procesa koji predstavlja važan postupak u ljevaoničkoj industriji

Thyroid Hormone-Clearing Deiodinase 3 Protects from Cranio- Encephalic and Cardiac Congenital Abnormalities

Implications: Transient overexposure to TH during development may contribute to idiopathic congenital syndromes in humans (cleft palate, hydrocephalus, cardiac and Chiari malformations, others)https://knowledgeconnection.mainehealth.org/lambrew-retreat-2021/1054/thumbnail.jp

Characterization of Structures of Equivalent Tissue With a Pixel Detector

Research using hybrid pixel detectors in medical physics is on the rise. Timepix detectors have arrays of 256 × 256 pixels with a resolution of 55 μm. Here, and by using Timepix counts instead of Hounsfield units, we present a calibration curve of a Timepix detector analog to those used for CT calibration. Experimentation consisted of the characterization of electron density in 10 different kinds of tissue equivalent samples from a CIRS 062M phantom (lung, 3 kinds of bones, fat, breast, muscle, water and air). Radiation of the detector was performed using an orthodontic X-ray machine at 70 KeV and .06 second of tube current with a purpose-built aluminum collimator. Data acquisition was performed at 1 frame per second and taking 3 frames per phantom. We were able to find a curve whose behavior was similar to others already published. This will lead to the verification of the usage of Timepix for identification of different tissues in an organ

Characterization of carbon pastes as matrices in composite electrodes for use in electrochemical capacitors.

Carbon paste electrodes (CPEs) were prepared from carbon black powder with different binders (Silicon Oil or Nujol).Cyclic voltammetry, chronoamperometry and chronopotentiometry techniques and different electrolytes (1M HClO4 and 1MLiClO4) were used to characterize the capacitive response and evaluate the capacitance (F/cm2, F/g) of CPEs, with andwithout surface modification. The surface modification was carried out by applying a potential pulse (1.35 V vs. saturatedcalomel electrode, SCE) at a time of 300 s, where the growth of carbon-oxygen (C-O) species were induced on the surface ofthe electrode. The results show that modified electrodes enhanced the capacitance and the electrolytic system has animportant influence in the stability and reactivity of electrodes. The modified electrodes shows an importantpseudocapacitive behavior as result of a diffusion processes that involved an interfacial reaction between the C-O speciesformed during the electrochemical surface treatment and the protons present in the electrolyte