Supersymmetric Extension of the Quantum Spherical Model

In this work, we present a supersymmetric extension of the quantum spherical model, both in components and also in the superspace formalisms. We find the solution for short/long range interactions through the imaginary time formalism path integral approach. The existence of critical points (classical and quantum) is analyzed and the corresponding critical dimensions are determined.Comment: 21 pages, fixed notation to match published versio

Untangling coastal diversity: how habitat complexity shapes demersal and benthopelagic assemblages in NW Iberia

Understanding species–habitat relationships is essential for ecosystem-based conservation. This study explores the significance of habitat characteristics and complexity for demersal and benthopelagic communities within a patchwork of coastal habitats, including rocky seabed, macroalgae formations, sandy bottoms, and a combination of rock and sand areas. Species and habitats were surveyed along the north-west (NW) Iberian continental shelf area of Viana do Castelo using baited remote underwater video stations (BRUVS). We found significant differences (p < 0.05) in species assemblages across habitats, with rocky substrates showing the highest diversity and abundance. Sand habitats showed the lowest species richness and abundance, underscoring the importance of habitat complexity to support marine life. Our study also emphasises the role of specific species in shaping the communities, identifying key species such as Trisopterus luscus, Diplodus vulgaris, and Ctenolabrus rupestris as the three most abundant in the region and significant contributors to the observed dissimilarities between habitats. By elucidating the impact of habitat complexity on marine life, our results offer essential baseline data, which serve as a kick-start point to inform sustainable management and conservation strategies for the long-term health and productivity of these vital ecological systems in the North-East Atlantic.Fundação para a Ciência e a Tecnologia | Ref. UIDB/04050/2020Fundação para a Ciência e a Tecnologia | Ref. LA/P/0069/2020Fundação para a Ciência e a Tecnologia | Ref. PD/BD/143088/2018Fundação para a Ciência e a Tecnologia | Ref. COVID/BD/153031/2022Fundação para a Ciência e a Tecnologia | Ref. PD/BD/150365/201

Block-windowed burst OFDM: A high-efficiency multicarrier technique

A block-windowed burst orthogonal frequency division multiplexing (OFDM) technique which is a multicarrier technique with power spectral density similar to the filtered OFDM approach, since it also employs smoother, non-rectangular windows, is presented. However, it does not need a cyclic prefix, which means the overall power and spectral efficiencies are higher. An appropriate receiver for typical time-dispersive channels, allowing 2 dB of gain relatively conventional OFDM schemes is also presented

Public employment redux

The public sector hires disproportionately more educated workers. To rationalize this finding, we propose a model with a perfectly competitive private sector, and non-Walrasian public sector. Our economy also features heterogeneity across individuals and jobs, and a simple sorting mechanism that generates underemployment - educated workers performing unskilled jobs. We find that the public-sector wage differential and excess underemployment account for 15 percent of the education bias, with the remaining accounted for by technology. In a counterintuitive fashion, we find that more compressed wages in the public sector raise inequality in the private sector

First examples of neutral and cationic indenyl nickel(II) complexes bearing arsine or stibine ligands: highly active catalysts for the oligomerisation of styrene

New indenyl nickel(II) complexes bearing arsine or stibine ligands synthesised by a new methodology exhibit very high catalytic activities for the oligomerisation of styrene

Recent changes on the abundance and distribution of non-indigenous macroalgae along the southwest coast of the Bay of Biscay

Twenty-three rocky shores along approximately 225 km on the southwest coast of the Bay of Biscay were sampled during the springs of 2014 and 2021, to explore changes in the distribution and abundance of four non-indigenous species (NIS) macroalgae (i.e., Asparagopsis armata, Grateloupia turuturu, Sargassum muticum, and Undaria pinnatifida) by using a semi-quantitative scale. Results showed relevant changes in the distribution and abundance of NIS. The kelp U. pinnatifida was recorded in 2021 for the first time on two shores. The distribution of G. turuturu showed an extension in its range of distribution of 200 km to the east. The other two target species S. muticum and A. armata were widely distributed along the whole 225 km of the studied area in 2014 and 2021, with higher abundance in 2021. Therefore, we strongly advise the necessity of future monitoring programs for these four NIS species. These monitoring programs will explore the progress of invasion and resilience of native species.This study was supported by the project ATLANTIDA (ref. NORTE-01-0145-FEDER-000040), supported by the Norte Portugal Regional Operational Program (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement and through the European Regional Development Fund (ERDF). This study was supported by the FCT-Foundation for Science and Technology through national funds within the scope of Contrato-Programa” UIDB/04050/2020 funded by national funds through the FCT I.P and, UIDB/04423/2020, UIDP/04423/2020. L. Guerrero-Meseguer was financed thanks to a grant from the Department of European Funds, University, and Culture of the Government of the Balearic Islands. P. Veiga was hired through the Regulamento do Emprego Científico e Tecnológico-RJEC from the Portuguese Foundation for Science and Technology (FCT) program (CEECIND/03893/2018)

Artificial substrates as sampling devices for marine epibenthic fauna: A quest for standardization

In temperate regions, macroalgae are naturally abundant habitat builders for many organisms of ecological and economic importance. Hence, macroalgae are good targets for monitoring studies based on colonization processes as, through them, it is possible to sample the epifauna that uses them as habitat. Nevertheless, macroalgae collection may not be sustainable, can compromise the survival of the target macroalgae populations and destroy fragile or threatened communities.The search for an adequate procedure that can overcome the problems related to destructive quantitative sampling of the epifauna associated with macroalgae and the development of a methodology that can be used for comparative macrofauna monitoring, regardless of the location, were the motivations for this study. The evaluation of the mobile epifauna associated with Artificial Substrates (AS) with different degrees of complexity and natural subtidal macroalgae was implemented, as a means to evaluate the viability of AS as an alternative approach for epifauna monitoring.Cystoseira baccata and Halidrys siliquosa were chosen as natural macroalgae. The hypotheses tested were (1) macroalgae and AS with similar structure will support similar assemblages of mobile epifauna; (2) different complexity AS will shelter different assemblages of mobile epifauna. The results obtained after 3 and 6 months showed that AS and macroalgae, both with similar structure, supported different assemblages of mobile epifauna, differing also when the time factor is considered. Moreover, different complexity AS supported different epifaunal assemblages. Our results also show that a period of colonization of 3 months was enough to accurately discriminate locations but the 3 additional months reinforce these differences and provide more coherent results with the species colonizing natural macroalgae in both locations studied. Hence, AS could be used as a valid, replicable, standard and representative alternative tool for monitoring studies.The present study was cofinanced by NextSea: Next generation monitoring of coastal ecosystems in a scenario of global change (operation NORTE-01-0145-FEDER-000032) and by FSE: Fundo Social Europeu, Portugal through NORTE 2020. Diego CarreiraFlores was supported by a PhD Fellowship (BD/Do*Mar/1010/2016) do Programa de Ciencia, Tecnologia e Gestao Marinha (Do*Mar), Portugal, operation number NORTE-08-5369-FSE-000039. This work was also supported by the strategic programme UID/BIA/04050/2019 funded by national funds through the FCT I.P, Portugal

Assessing the seasonal and spatial dynamics of zooplankton through DNA metabarcoding in a temperate estuary

Zooplankton are key components of estuarine trophic networks. However, routine monitoring is hindered by the difficulty of morphology-based identification. DNA-based methods allow us to circumvent some of these hurdles, providing precise species identifications regardless of the taxonomic expertise of the investigator or the developmental stage of the specimens. However, the process is dependent on the completeness of the reference libraries. In this study, we sought to evaluate the potential of DNA metabarcoding to assess the seasonal (summer, autumn, and early spring) and spatial dynamics of zooplankton (four locations spanning ca. 6 km) in the Lima estuary (NW Portugal). Two genetic markers were used: the cytochrome c oxidase subunit I and the V4 hypervariable region of the ribosomal 18S rRNA genes. Overall, 327 species were recovered, and both markers displayed minute overlap (7% were detected with both markers). Species richness, composition, and taxonomic distinctness were majorly influenced by the season, with a declining tendency from summer (highest number of exclusive species, n = 74) to spring. Second to season, the taxa composition was influenced by spatial variation where the most downstream site displayed the highest number of exclusive species, n = 53. A total of 16 non-indigenous species were detected using metabarcoding, but only one (Austrominus modestus) has been documented out in the estuary. In conclusion, both the seasonal and spatial gradients influenced the recovered richness, composition, and taxonomic distinctness, confirming the great aptitude of DNA metabarcoding for providing higher density monitoring and shedding new light on the composition and dynamics of complex zooplankton communities.FCT -Fundação para a Ciência e a Tecnologia(undefined