Morphological transition between diffusion-limited and ballistic aggregation growth patterns

In this work, the transition between diffusion-limited and ballistic aggregation models was revisited using a model in which biased random walks simulate the particle trajectories. The bias is controlled by a parameter $\lambda$, which assumes the value $\lambda=0$ (1) for ballistic (diffusion-limited) aggregation model. Patterns growing from a single seed were considered. In order to simulate large clusters, a new efficient algorithm was developed. For $\lambda \ne 0$, the patterns are fractal on the small length scales, but homogeneous on the large ones. We evaluated the mean density of particles $\bar{\rho}$ in the region defined by a circle of radius $r$ centered at the initial seed. As a function of $r$, $\bar{\rho}$ reaches the asymptotic value $\rho_0(\lambda)$ following a power law $\bar{\rho}=\rho_0+Ar^{-\gamma}$ with a universal exponent $\gamma=0.46(2)$, independent of $\lambda$. The asymptotic value has the behavior $\rho_0\sim|1-\lambda|^\beta$, where $\beta= 0.26(1)$. The characteristic crossover length that determines the transition from DLA- to BA-like scaling regimes is given by $\xi\sim|1-\lambda|^{-\nu}$, where $\nu=0.61(1)$, while the cluster mass at the crossover follows a power law $M_\xi\sim|1 -\lambda|^{-\alpha}$, where $\alpha=0.97(2)$. We deduce the scaling relations \beta=\n u\gamma and $\beta=2\nu-\alpha$ between these exponents.Comment: 7 pages, 8 figure

The formation of planetary disks and winds: an ultraviolet view

Planetary systems are angular momentum reservoirs generated during star formation. This accretion process produces very powerful engines able to drive the optical jets and the molecular outflows. A fraction of the engine energy is released into heating thus the temperature of the engine ranges from the 3000K of the inner disk material to the 10MK in the areas where magnetic reconnection occurs. There are important unsolved problems concerning the nature of the engine, its evolution and the impact of the engine in the chemical evolution of the inner disk. Of special relevance is the understanding of the shear layer between the stellar photosphere and the disk; this layer controls a significant fraction of the magnetic field building up and the subsequent dissipative processes ougth to be studied in the UV. This contribution focus on describing the connections between 1 Myr old suns and the Sun and the requirements for new UV instrumentation to address their evolution during this period. Two types of observations are shown to be needed: monitoring programmes and high resolution imaging down to, at least, milliarsecond scales.Comment: Accepted for publication in Astrophysics and Space Science 9 figure

Compilation, revision, and annotation of DNA barcodes of marine invertebrate Non-Indigenous Species (NIS) occurring in european coastal regions

The script developed to create the DNA sequence reference library is available at https://github.com/tadeu95/Curated-BINs-Reference-Library (accessed on 25 January 2023). Metabarcoding datasets will be made available upon request since they belong to a study that is not published yet.The introduction of non-indigenous species (NIS) is one of the major threats to the integrity of European coastal ecosystems. DNA-based assessments have been increasingly adopted for monitoring NIS. However, the accuracy of DNA-based taxonomic assignments is largely dependent on the completion and reliability of DNA barcode reference libraries. As such, we aimed to compile and audit a DNA barcode reference library for marine invertebrate NIS occurring in Europe. To do so, we compiled a list of NIS using three databases: the European Alien Species Information Network (EASIN), the Information System on Aquatic Non-indigenous and Cryptogenic Species (AquaNIS), and the World Register of Introduced Marine Species (WRiMS). For each species, we retrieved the available cytochrome c oxidase subunit I (COI) mitochondrial gene sequences from the Barcode of Life Data System (BOLD) and used the Barcode, Audit & Grade System (BAGS) to check congruence between morphospecies names and Barcode Index Numbers (BINs). From the 1249 species compiled, approximately 42% had records on BOLD, among which 56% were discordant. We further analyzed these cases to determine the causes of the discordances and attributed additional annotation tags. Of the 622 discordant BINs, after revision, 35% were successfully solved, which increased the number of NIS detected in metabarcoding datasets from 12 to 16. However, a fair number of BINs remained discordant. Reliability of reference barcode records is particularly critical in the case of NIS, where erroneous identification may trigger action or inaction when not required.This research was funded by national funds through the Foundation for Science and Technology (FCT I.P.), grant number PTDC/BIA-BMA/29754/2017 (NIS-DNA: Early detection and monitoring of non-indigenous species (NIS) in coastal ecosystems based on high-throughput sequencing tools) and by the “Contrato-Programa” UIDB/04050/2020. Financial support granted by the FCT I.P. to S.D. (CEECIND/00667/2017) is also acknowledged. A.S.L. (UI/BD/150871/2021) and J.T.F. (UI/BD/150910/2021) are supported by the Collaboration Protocol for Financing the Multiannual Research Grants Plan for Doctoral Students with financial support from FCT I.P. and the European Social Fund under the Northern Regional Operational Program—Norte2020

Identification of minority grapevine cultivars from Vinhos Verdes Portuguese DOC Region

The Portuguese Vinhos Verdes DOC Region retains a considerable biodiversity in grapevine varieties. Unfortunately, regional grapevine patrimony is in danger of disappearing. The present study was carried out in order to genotype, using 12 microsatellite loci, a group of 39 accessions of Vinhos Verdes DOC region, including underuse and minor varieties included in the wine list of varieties and also several unknown accessions with regional designations. The accessions analyzed were identified and grouped into 34 different genotypes, nine of them referred as new genotypes. Some new synonyms were detected, namely between Spanish and Portuguese cultivars. Misidentifications and wrong designations were also detected

Effect of carbonation on the chloride diffusion of mortar specimens exposed to cyclic wetting and drying

Carbonation and chloride ingress are the two main causes of corrosion in reinforced concrete structures. Despite the combined action of these mechanisms being a reality, there is little research on the effect of carbonation on the chloride diffusion in concrete. This work intends to study the influence of carbonation on chloride diffusion of mortar specimens. Cubic mortar specimens were cast with 0.55 of water-cement ratio. After curing, the specimens were subjected to 56 days of wetting and drying cycles. Half the samples were immersed for a day in a 3.5% NaCl solution and then placed for 6 days in a carbonation chamber (4%CO2); the other half were also kept a day in 3.5% NaCl, but after were kept during 6 days in laboratory environment. Afterwards, the depth of chlorides and CO2 penetration was evaluated. Complementary tests were also carried out, such as rapid chloride migration coefficient and water capillary absorption. The results show that carbonation has a direct influence on chloride penetration, decreasing it. The noncarbonated samples showed a profile with higher amount of chloride than carbonated ones. This fact can be related to the refinement of the mortar pores caused by carbonation and observed in water absorption tests

Avaliação de matriz cimentícia contendo cinzas volantes frente à ação combinada da carbonatação e dos iões cloreto

As cinzas volantes (CV) têm sido utilizadas para tornar a matriz cimentícia mais resistente à penetração de Cl- uma vez que tornam a estrutura porosa mais densa. Por outro lado, sabe-se que o Ca(OH) existente na matriz é parcialmente consumido pelas reações pozolânicas, facilitando o avanço da carbonatação. Considerando a ação conjunta destes agentes, especula-se sobre o comportamento da matriz. Foram moldados provetes com 40% de CV (substituição). Após 90 dias de cura os provetes foram submetidos a 12 ciclos de imersão (3,5% NaCl)/secagem (4% CO2) e 12 ciclos de referência,168 dias. Os resultados indicam que os provetes submetidos à ação combinada apresentam uma profundidade de carbonatação inferior em relação à ação exclusiva do CO2. Ao contrário, apresentam um perfil de Cl- com teores superiores quando comparados à ação exclusiva dos Cl-.

Luiz bandeira bridge: Assessment of a historical reinforced concrete (RC) bridge

The Luiz Bandeira Bridge is located along the Portuguese national road EN333-3, breaching the valley of the Vouga River, just northeast of the small village Sejães, in the district of Oliveira de Frades. It is considered to be the oldest concrete bridge in use in Portugal, and one of the oldest in Europe. Since this bridge is at risk of disappearing due to a construction of a dam, the Department of Civil Engineering of the University of Minho decided to launch a comprehensive study of Luiz Bandeira Bridge, in an attempt to preserve the memory of the past cataloguing the heritage for future reference. These studies include historical, geometrical and damage surveys, the physical and chemical characterization of existing structural materials, the assessment of the reinforcement detailing, dynamic characterization by determining the main frequencies and vibration modes and safety level. This work presents a comprehensive overview of the most important results of these studies