360 research outputs found

    N-Relaxion: Large Field Excursions from a Few Site Relaxion Model

    Full text link
    Relaxion models are an interesting new avenue to explain the radiative stability of the Standard Model scalar sector. They require very large field excursions, which are difficult to generate in a consistent UV completion and to reconcile with the compact field space of the relaxion. We propose an N-site model which naturally generates the large decay constant needed to address these issues. Our model offers distinct advantages with respect to previous proposals: the construction involves non-abelian fields, allowing for controlled high energy behaviour and more model building possibilities, both in particle physics and inflationary models, and also admits a continuum limit when the number of sites is large, which may be interpreted as a warped extra dimension.Comment: 7 pages, 2 figures; v2: version to appear in PR

    Alternative methods of determining hamstrings-to-quadriceps ratios: A comprehensive review

    Get PDF
    The hamstrings-to-quadriceps muscle strength ratio calculated by peak torque has been used as an important tool to detect muscle imbalance, monitor knee joint stability, describe muscle strength properties and functionality, and for lower extremity injury prevention and rehabilitation. However, this ratio does not consider other neuromuscular variables that can also influence the antagonist to agonist muscle relationship, such as torque produced at multiple angles of range of motion, explosive strength, muscle size, muscle fatigue, or muscle activation. The aim of this study was to comprehensively review alternative methods of determining the hamstrings-to-quadriceps ratio. These include ratios calculated by angle-specific torque, rate of torque development, muscle size, fatigue index, and muscle activation (measured by electromyography). Collectively, the literature demonstrates that utilizing alternative methods of determining the hamstrings-to-quadriceps ratio can be functionally relevant for a better understanding of the neuromuscular mechanisms underpinning the interaction of strength between hamstrings and quadriceps. However, there is insufficient evidence to recommend any of the alternative methods as sensitive clinical tools for predicting injury risk and monitoring knee joint integrity. Future longitudinal studies, along with injury incidence, are needed to further investigate all alternative methods of determining the hamstrings-to-quadriceps ratio. These have potential to offer insight into how athletes and the general population should be trained for performance enhancement and injury reduction, and may be used along with traditional methods for a thorough assessment of an individual\u27s H:Q muscle balance

    Effects of different combinations of concentric and eccentric resistance training programs on traditional and alternative hamstrings-to-quadriceps ratios

    Get PDF
    Resistance training is often recommended for combined increases in traditional and alternative hamstrings-to-quadriceps (H:Q) ratios in order to reduce knee strength imbalance and associated hamstrings and knee ligament injury risk. The aim of this study was to investigate the effect of different concentric and eccentric resistance training programs on traditional and alternative H:Q ratios. Forty male volunteers were assigned to one of 4 groups: concentric quadriceps and concentric hamstrings (CON/CON, n = 10), eccentric quadriceps and eccentric hamstrings (ECC/ECC, n = 10), concentric quadriceps and eccentric hamstrings (CON/ECC, n = 10), or no training (control (CNTRL), n = 10). Traditional conventional (CR) and functional (FR), alternative rate of torque development (RTD), muscle size (MS), and muscle activation (MA) H:Q ratios were measured before and after six weeks of unilateral nondominant knee extension–flexion resistance training performed on an isokinetic dynamometer. The ECC/ECC training significantly increased FR (pre = 0.75 ± 0.11; post = 0.85 ± 0.15), whereas the lack of training (CNTRL) decreased the RTD H:Q ratio (pre = 1.10 ± 0.67; post = 0.73 ± 0.33). There were no differences between groups for the other traditional and alternative ratios following resistance training protocols. These findings suggest eccentric exercise for quadriceps and hamstrings as the most beneficial training program for inducing increases in the traditional FR. However, different resistance training strategies may be needed to also elicit increases in the alternative RTD, MS, and MA H:Q ratios for fully restoring muscle balance and reducing potential hamstrings and knee ligament injury risk

    Physiology of stretch-mediated hypertrophy and strength increases: A narrative review

    Get PDF
    Increasing muscle strength and cross-sectional area is of crucial importance to improve or maintain physical function in musculoskeletal rehabilitation and sports performance. Decreases in muscular performance are experienced in phases of reduced physical activity or immobilization. These decrements highlight the need for alternative, easily accessible training regimens for a sedentary population to improve rehabilitation and injury prevention routines. Commonly, muscle hypertrophy and strength increases are associated with resistance training, typically performed in a training facility. Mechanical tension, which is usually induced with resistance machines and devices, is known to be an important factor that stimulates the underlying signaling pathways to enhance protein synthesis. Findings from animal studies suggest an alternative means to induce mechanical tension to enhance protein synthesis, and therefore muscle hypertrophy by inducing high-volume stretching. Thus, this narrative review discusses mechanical tension-induced physiological adaptations and their impact on muscle hypertrophy and strength gains. Furthermore, research addressing stretch-induced hypertrophy is critically analyzed. Derived from animal research, the stretching literature exploring the impact of static stretching on morphological and functional adaptations was reviewed and critically discussed. No studies have investigated the underlying physiological mechanisms in humans yet, and thus the underlying mechanisms remain speculative and must be discussed in the light of animal research. However, studies that reported functional and morphological increases in humans commonly used stretching durations of \u3e 30 min per session of the plantar flexors, indicating the importance of high stretching volume, if the aim is to increase muscle mass and maximum strength. Therefore, the practical applicability seems limited to settings without access to resistance training (e.g., in an immobilized state at the start of rehabilitation), as resistance training seems to be more time efficient. Nevertheless, further research is needed to generate evidence in different human populations (athletes, sedentary individuals, and rehabilitation patients) and to quantify stretching intensity

    METHYLPHENIDATE: PROCONVULSANT EFFECT AND ACTION ON ACETYL CHOLINESTERASE ACTIVITY IN YOUNG AND ADULT MICE

    Get PDF
    Objective: Methylphenidate (MPH) is a derivative of piperidine, structurally related to amphetamine. It is the most widely psychostimulant used in Brazil for treating attention deficit disorder and hyperactivity. This drug was investigated in an epilepsy model induced by pilocarpine and on acetylcholinesterase (AChE) activity in young and adult mice. Methods: The control group was treated with saline. The treated groups received MPH (2.5, 5, 10 or 20 mg/kg) in single dose, followed by pilocarpine (400mg/Kg). The groups were observed for1h after treatment. Results: MPH, in all doses, was efficacious in decreasing both the latency to first seizures and the survival percentage in young and adult animals. Determination of AChE activity in the hippocampus and striatum of young and adult animals, after pilocarpine-induced status epilepticus, demonstrated that pretreatment with MPH reduced AChE activity only in the striatum. Conclusion: Our findings suggest that MPH has proconvulsant action and cholinergic neurotransmission system can play a role in this effect

    Hippocampal Astrocytes in Migrating and Wintering Semipalmated Sandpiper

    Get PDF
    Seasonal migratory birds return to the same breeding and wintering grounds year after year, and migratory long-distance shorebirds are good examples of this. These tasks require learning and long-term spatial memory abilities that are integrated into a navigational system for repeatedly locating breeding, wintering, and stopover sites. Previous investigations focused on the neurobiological basis of hippocampal plasticity and numerical estimates of hippocampal neurogenesis in birds but only a few studies investigated potential contributions of glial cells to hippocampal-dependent tasks related to migration. Here we hypothesized that the astrocytes of migrating and wintering birds may exhibit significant morphological and numerical differences connected to the long-distance flight. We used as a model the semipalmated sandpipe

    THERMAL AND OXIDATION STABILITY OF SUNFLOWER METHANOLIC BIODIESEL AND BLENDS OF BIODIESEL/DIESEL

    Get PDF
    Resumo   A utilização de energias renováveis como o biodiesel tem despertado grande interesse industrial e ambiental. Neste trabalho foram avaliadas as propriedades físico-químicas de diesel, biodiesel, e de suas misturas nas proporções: B5 a B70, através de ensaios de ponto de fulgor, massa específica, viscosidade cinemática. Além de estudar a estabilidade térmica e oxidativa por TG/DTA. Como resultado foi observado que com o aumento do teor de biodiesel adicionado ao diesel foi observada uma melhoria na sua estabilidade térmica e um aumento do resíduo e através do DTA que misturas que contém biodiesel são mais voláteis que o diesel. Palavras-chave: Biodiesel, Girassol e Termogravimetria.   Abstract   The using of renewable energy like biodiesel has attracted great industrial interest and the environment. In this work we evaluate the physicochemical properties of diesel, biodiesel and their mixtures in proportions: B5 to B70, by testing the flash point, density, kinematic viscosity. Also, thermal and oxidative stability by TGA / DTA. It was verified that by increasing the content of biodiesel added to diesel was observed an improvement in thermal stability and an increase of the residue by DTA and the mixtures containing biodiesel which are more volatile than diesel. Key-words: Biodiesel, Sunflower, Thermogravimetry

    Experimental and computational studies of the interactions between carbon nanotubes and ionic liquids used for detection of acetaminophen

    Get PDF
    The interactions between multi-walled carbon nanotubes and different amounts of an ionic liquid (IL), as well asthe interactions between this system (used as electrochemical sensor) and acetaminophen (ACOP), were in-vestigated through both experimental and theoretical methodologies. Experiments indicated that there is anoptimal concentration of ionic liquid for ACOP detection. A host of techniques and model systems were em-ployed to investigate the adsorption and oxidation processes. To investigate the source of the increased elec-trochemical current in the presence of an IL, we computed the adsorption energy values of ACOP in the nanotube–IL system via Monte Carlo simulations and Density Functional Theory (DFT). DFT allowed us to explore thechanges in adsorption energy due to oxidation. Our theoretical results support the experimentalfindings thatmoderate amounts of IL modulates ACOP/ACOP+adsorption, pointing to a cooperative effect that tends to wanewith increasing amounts of IL pairs. We observed that the IL favors desorption of the oxidized species andfacilitates charge transfer from the ACOP to the nanotube. Therefore, our studies point towards multifactorialeffects with clear physical basis that modulates binding leading to an optimal ratio to promote ACOP detectionThe authors wish to thank the Brazilian research funding institu-tions Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq) and Fundação de Amparo à Pesquisa do Estado de São Paulo(FAPESP) for theirfinancial support (CNPq proc. 400223/2014-7,303596/2014-7, 306177/2016-1, 302801/2014-6, 154089/2016-8,573925/2008-9 and 573548/2008-0; FAPESP 2017/23416-9) andCAPES (Funcap–2133/2012/proc. 23038.007973/2012-90),PRONEM/FUNCAP/CNPq (PNE-0112-00048.01.00/16), PRONEX/FUNCAP (proc. PR2-0101-00030.01.00/15). This study wasfinanced inpart by the Coordenação de Aperfeiçoamento de Pessoal de NívelSuperior–Brasil (CAPES)–Finance Code 00. Camila P. Sousa thanksCAPES- PNPD for her grantinfo:eu-repo/semantics/publishedVersio

    A hybrid-hierarchical genome assembly strategy to sequence the invasive golden mussel Limnoperna fortunei

    Get PDF
    ABSTRACT Background: For more than 25 years, the golden mussel Limnoperna fortunei has aggressively invaded South American freshwaters, having travelled more than 5,000 km upstream across five countries. Along the way, the golden mussel has outcompeted native species and economically harmed aquaculture, hydroelectric powers, and ship transit. We have sequenced the complete genome of the golden mussel to understand the molecular basis of its invasiveness and search for ways to control it. Findings: We assembled the 1.6 Gb genome into 20548 scaffolds with an N50 length of 312 Kb using a hybrid and hierarchical assembly strategy from short and long DNA reads and transcriptomes. A total of 60717 coding genes were inferred from a customized transcriptome-trained AUGUSTUS run. We also compared predicted protein sets with those of complete molluscan genomes, revealing an exacerbation of proteinbinding domains in L. fortunei. Conclusions: We built one of the best bivalve genome assemblies available using a cost-effective approach using Illumina pair-end, mate pair, and PacBio long reads. We expect that the continuous and careful annotation of L. fortunei's genome will contribute to the investigation of bivalve genetics, evolution, and invasiveness, as well as to the development of biotechnological tools for aquatic pest control

    Biotinidase deficiency: Genotype-biochemical phenotype association in Brazilian patients

    Get PDF
    [EN] The association between the BTD genotype and biochemical phenotype [profound biotinidase deficiency (BD), partial BD or heterozygous activity] is not always consistent. This study aimed to investigate the genotype-biochemical phenotype association in patients with low biotinidase activity. Methods All exons, the 5'UTR and the promoter of the BTD gene were sequenced in 72 Brazilian individuals who exhibited low biotinidase activity. For each patient, the expected biochemical phenotype based on the known genotype was compared with the observed biochemical phenotype. Additional non-genetic factors that could affect the biotinidase activity were also analysed. Most individuals were identified by neonatal screening (n = 66/72). When consecutive results for the same patient were compared, age, prematurity and neonatal jaundice appeared to affect the level of biotinidase activity. The biochemical phenotype at the time of the second blood collection changed in 11/22 patients compared to results from the first sample. Three novel variants were found: c.1337T>C (p.L446P), c.1466A>G (p.N489S) and c.962G>A (p.W321*). Some patients with the same genotype presented different biochemical phenotypes. The expected and observed biochemical phenotypes agreed in 68.5% of cases (concordant patients). The non-coding variants c.-183G>A, c.-315A>G and c.-514C>T were present in heterozygosis in 5/17 discordant patients. In addition, c.- 183G>A and c.-514C>T were also present in 10/37 concordant patients. The variants found in the promoter region do not appear to have a strong impact on biotinidase activity. Since there is a disparity between the BTD genotype and biochemical phenotype, and biotinidase activity may be affected by both genetic and non-genetic factors, we suggest that the diagnosis of BD should be based on more than one measurement of plasma biotinidase activity. DNA analysis can be of additional relevance to differentiate between partial BD and heterozygosity.SIThis study received financial support from Fundo de Incentivo à Pesquisa e Eventos/Hospital de Clínicas de Porto Alegre (FIPE-HCPA) for research materials and publication fee. Post Graduate Program in Genetics and Molecular Biology (Universidade Federal do Rio Grande do Sul) funded the translation. ECN has a commercial affiliation (CTN Diagnósticos) which did not have any role or financial contribution to this research. TB have fellowship from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes). FS had fellowship from the Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS). IVDS, MRSC and PASF have fellowships from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). HB receives a research grant of Orphan Europe. The funders did no provide support in the form of salaries for any author, and did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section
    • …
    corecore