144 research outputs found

    Weakly holomorphic modular forms in prime power levels of genus zero

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    Let Mk♯(N)M_k^\sharp(N) be the space of weight kk, level NN weakly holomorphic modular forms with poles only at the cusp at ∞\infty. We explicitly construct a canonical basis for Mk♯(N)M_k^\sharp(N) for N∈{8,9,16,25}N\in\{8,9,16,25\}, and show that many of the Fourier coefficients of the basis elements in M0♯(N)M_0^\sharp(N) are divisible by high powers of the prime dividing the level NN. Additionally, we show that these basis elements satisfy a Zagier duality property, and extend Griffin's results on congruences in level 1 to levels 2, 3, 4, 5, 7, 8, 9, 16, and 25

    El lagarto que nunca duerme: actividad del gecko del pampa Homonota uruguayensis

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    It is generally assumed that lizards are active whenever climatic conditions are favorable. Homonota uruguayensis (Vaz-Ferreira & Sierra de Soriano, 1961) is the only native gecko – and nocturnal lizard – living in the northern Pampa biome, and its ecology is poorly known. This study aimed at describing this species’ pattern of daily and annual activity and its relation with environmental temperatures. The study was conducted in the extreme south of Brazil (Rosário do Sul, State of Rio Grande do Sul), between May 2010 and January 2011 at a rocky outcrop located in the Pampa biome. The study was carried out in a total of four seasonal field trips, totalizing 1185 hours of field work. The data were collected, both during the day and the night in 6-hour shifts (duration of the sampling period). The area was randomly covered at each shift to record activity and microhabitat use by the lizards. In total 1541 specimens were recorded throughout the study. Homonota uruguayensis showed diurnal and nocturnal activity in the four seasons, with periods of daily activity varying significantly between all seasons in a cyclic and multimodal pattern, with no significant relation with environmental temperatures. There was no difference in activity related to sex and age classes. Most active lizards were found when air temperatures ranged from 14 °C to 32.9 °C (82% of active lizards) and substrate temperatures ranged from 10 °C to 32.9 °C (87% of active lizards).La suposición general ha sido que los lagartos son activos cuando las condiciones climáticas son favorables. Homonota uruguayensis (Vaz-Ferreira & Sierra de Soriano, 1961) es la única lagartija nativa – y la lagartija nocturna – que vive en el norte de bioma Pampa. La ecología de esta especie es poco conocida y este estudio tuvo como objetivo describir su patrón de actividad diaria y anual y su relación con las temperaturas ambientales. El estudio se llevó a cabo en el extremo sur de Brasil (Rosário do Sul, Rio Grande do Sul), a partir de mayo 2010 - enero 2011, en un afloramiento rocoso situado en el bioma Pampa. El estudio totalizó cuatro excursiones de campo estacionales y 1185 horas. Los datos fueron recogidos a lo largo de los turnos de 6 horas durante el día y la noche. El área fue recorrida aleatoriamente en cada turno siempre registrandose la actividad y el microhabitat utilizado por los lagartos. A lo largo del estudio, 1541 especímenes se registraron. Homonota uruguayensis presentó hábito diurno y nocturno en las cuatro estaciones, con períodos de actividad diaria variando significativamente entre todas las estaciones en forma cíclica y multimodal, no se observó relación significativa con las temperaturas ambientales. No fue constatada diferencia entre los sexos con relación a la actividad y las clases de edad. La mayoría de los lagartos activos fue encontrada a temperaturas del aire que variaron de 14 °C a 32,9 °C (82% de lagartos activos) y a temperaturas del sustrato entre 10 °C y 32,9 °C (87% de lagartos activos)

    Are lizards sensitive to anomalous seasonal temperatures? long-term thermobiological variability in a subtropical species

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    Alterations in thermal niches have been widely associated with the Anthropocene erosion of reptiles’ diversity. They entail potential physiological constraints for organisms’ perfor- mance, which can lead to activity restrictions and impact fitness and demography. Reptiles are ectotherms which rely on seasonal periodicity to maximize the performance of biological functions. Despite it, the ecological implications of shifts in local temperatures are barely explored at the seasonal scale. This study aims to assess how changes in air temperature and substrate temperature affect the activity, body temperature (Tb) and thermoregulation patterns of the sand lizard, Liolaemus arambarensis (an endangered, microendemic spe- cies from southern Brazil), throughout a four-year period. Field surveys were conducted monthly on a restricted population in a sand-dune habitat. The annual fluctuations of the seasonal temperatures led to significant changes in the activity and Tb of L. arambarensis and shaped thermoregulation trends, suggesting biological plasticity as a key factor in the face of such variability. Lizards tended to maintain seasonal Tb in mild and harsh seasons through increased warming/cooling efforts. Anomalous winter conditions seemed especially critical for individual performance due to their apparent high impact favouring/constraining activity. Activity and thermoregulation were inhibited in frigid winters, probably due to a vul- nerable physiology to intense cold spells determined by higher preferred body temperatures than Tb. Our results warn of a complex sensitivity in lizards to anomalous seasonal tempera- tures, which are potentially enhanced by climate change. The current work highlights the importance of multiannual biomonitoring to disentangle long-term responses in the thermal biology of reptiles and, thereby, to integrate conservation needs in the scope of global change

    When and where does Sphaenorhynchus surdus call in Southern Brazil?

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    When and where does Sphaenorhynchus surdus call in Southern Brazil? Research regarding temporal and spatial distribution of amphibians has been very important to better understanding the relationship between species and their environment. In this context, no information is available for species of Sphaenorhynchus Tschudi, 1838 in Rio Grande do Sul. Thus, the main purpose of this research was to describe the temporal and spatial distribution of Sphaenorhynchus surdus (Cochran, 1953) during calling activity as well as the main climatic factors associated to this activity. This research was conducted in three ponds in the northeastern region of this State, specifi cally in the municipalities of Vacaria and Bom Jesus. Fieldwork was carried out monthly from June 2006 to March 2008 and each expedition lasted two days and two nights. The results show that S. surdus presents calling season concentrated in the warmer seasons, during spring and summer. The peak of calling males was observed during the sunset and the fi rst hours of night; however, the calling activity was observed in all periods of day and night. Calling activity was primarily associated with water temperature (r2 = 0.43; F1.19 = 14.65, p = 0.01). Regarding the calling sites, water surface was the most representative substrate (42%), followed by shrubby vegetation (25%), including the ones above two meters, when all ponds were considered in the analysis.Estudos sobre distribuição espacial e temporal de anfíbios têm se mostrado importantes para o entendimento das relações entre as espécies e o ambiente. Nesse sentido, constata-se que essas informações acerca de espécies do gênero Sphaenorhynchus Tschudi, 1838 no Rio Grande do Sul ainda não foram levantadas. Esta pesquisa, cujo objetivo principal foi a caracterização da distribuição espacial e temporal de Sphaenorhynchus surdus (Cochran, 1953) durante atividade de vocalização, bem como a análise dos principais fatores climáticos associados a essa atividade, foi conduzida em três corpos d’água com diferentes características da região dos Campos de Cima da Serra, nos municípios de Bom Jesus e Vacaria. As expedições a campo aconteceram mensalmente com a duração de dois dias e duas noites entre junho de 2006 e março de 2008. Os resultados mostraram que S. surdus apresenta temporada de vocalização concentrada nas estações mais quentes do ano, primavera e verão, interrompendo nos meses mais frios, durante outono e inverno. O pico da atividade de vocalização foi no ocaso e nas primeiras horas da noite, porém a espécie apresentou atividade de vocalização em todos os períodos amostrados do dia e da noite. Dentre as variáveis analisadas, a temperatura da água foi a variável climática com maior infl uência sobre a abundância de indivíduos em atividade de vocalização (r2= 0,43; F1,19 = 14,65, p= 0,01). Quanto aos sítios de vocalização, a lâmina d’água obteve a maior representatividade (42%) dentre os substratos, seguida pela vegetação arbustiva (25%) incluindo alturas superiores a dois metros, quando considerados todos os banhados

    Anura, Hylidae, Dendropsophus nahdereri (Lutz and Bokermann, 1963): distribution extension and new state record

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    Dendropsophus nahdereri is included in the Dendropsophus marmoratus group. Its distribution is known from the Brazilian states of Paraná and Santa Catarina. Here we report new records of this species and briefly describe the habitat of calling males. We found new localities of occurrence of D. nahdereri in Brazilian states of Santa Catarina and Rio Grande do Sul. We collected calling males in temporary lentic water bodies surrounded by arboreal vegetation, inside and on the border of native forest, and inside Pinus plantations near native forest

    Anura, Hylidae, Dendropsophus nahdereri (Lutz and Bokermann, 1963): distribution extension and new state record

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    Dendropsophus nahdereri is included in the Dendropsophus marmoratus group. Its distribution is known from the Brazilian states of Paraná and Santa Catarina. Here we report new records of this species and briefly describe the habitat of calling males. We found new localities of occurrence of D. nahdereri in Brazilian states of Santa Catarina and Rio Grande do Sul. We collected calling males in temporary lentic water bodies surrounded by arboreal vegetation, inside and on the border of native forest, and inside Pinus plantations near native forest

    Liver biopsy-based validation, confirmation and comparison of the diagnostic performance of established and novel non-invasive non-alcoholic fatty liver disease indexes:Results from a large multi-center study

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    Background: Non-invasive tools (NIT) for non-alcoholic fatty liver disease (NAFLD) screening or diagnosis need to be thoroughly validated using liver biopsies.Purpose: To externally validate NITs designed to differentiate the presence or absence of liver steatosis as well as more advanced disease stages, to confirm fully validated indexes (n = 7 NITs), to fully validate partially validated indexes (n = 5 NITs), and to validate for the first time one new index (n = 1 NIT).Methods: This is a multi-center study from two Gastroenterology-Hepatology Departments (Greece and Australia) and one Bariatric-Metabolic Surgery Department (Italy). Overall, n = 455 serum samples of patients with biopsy-proven NAFLD (n = 374, including 237 patients with non-alcoholic steatohepatitis (NASH)) and Controls (n = 81) were recruited. A complete validation analysis was performed to differentiate the presence of NAFLD vs. Controls, NASH vs. NAFL, histological features of NASH, and fibrosis stages.Results: The index of NASH (ION) demonstrated the highest differentiation ability for the presence of NAFLD vs. Controls, with the area under the curve (AUC) being 0.894. For specific histological characterization of NASH, no NIT demonstrated adequate performance, while in the case of specific features of NASH, such as hepatocellular ballooning and lobular inflammation, ION demonstrated the best performance with AUC being close to or above 0.850. For fibrosis (F) classification, the highest AUC was reached by the aspartate aminotransferase to platelet ratio index (APRI) being ~0.850 yet only with the potential to differentiate the severe fibrosis stages (F3, F4) vs. mild or moderate fibrosis (F0–2) with an AUC > 0.900 in patients without T2DM. When we excluded patients with morbid obesity, the differentiation ability of APRI was improved, reaching AUC = 0.802 for differentiating the presence of fibrosis F2–4 vs. F0–1. The recommended by current guidelines index FIB-4 seemed to differentiate adequately between severe (i.e., F3–4) and mild or moderate fibrosis (F0–2) with an AUC = 0.820, yet this was not the case when FIB-4 was used to classify patients with fibrosis F2–4 vs. F0–1. Trying to improve the predictive value of all NITs, using Youden's methodology, to optimize the suggested cut-off points did not materially improve the results.Conclusions: The validation of currently available NITs using biopsy-proven samples provides new evidence for their ability to differentiate between specific disease stages, histological features, and, most importantly, fibrosis grading. The overall performance of the examined NITs needs to be further improved for applications in the clinic

    Liver biopsy-based validation, confirmation and comparison of the diagnostic performance of established and novel non-invasive non-alcoholic fatty liver disease indexes:Results from a large multi-center study

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    Background: Non-invasive tools (NIT) for non-alcoholic fatty liver disease (NAFLD) screening or diagnosis need to be thoroughly validated using liver biopsies.Purpose: To externally validate NITs designed to differentiate the presence or absence of liver steatosis as well as more advanced disease stages, to confirm fully validated indexes (n = 7 NITs), to fully validate partially validated indexes (n = 5 NITs), and to validate for the first time one new index (n = 1 NIT).Methods: This is a multi-center study from two Gastroenterology-Hepatology Departments (Greece and Australia) and one Bariatric-Metabolic Surgery Department (Italy). Overall, n = 455 serum samples of patients with biopsy-proven NAFLD (n = 374, including 237 patients with non-alcoholic steatohepatitis (NASH)) and Controls (n = 81) were recruited. A complete validation analysis was performed to differentiate the presence of NAFLD vs. Controls, NASH vs. NAFL, histological features of NASH, and fibrosis stages.Results: The index of NASH (ION) demonstrated the highest differentiation ability for the presence of NAFLD vs. Controls, with the area under the curve (AUC) being 0.894. For specific histological characterization of NASH, no NIT demonstrated adequate performance, while in the case of specific features of NASH, such as hepatocellular ballooning and lobular inflammation, ION demonstrated the best performance with AUC being close to or above 0.850. For fibrosis (F) classification, the highest AUC was reached by the aspartate aminotransferase to platelet ratio index (APRI) being ~0.850 yet only with the potential to differentiate the severe fibrosis stages (F3, F4) vs. mild or moderate fibrosis (F0–2) with an AUC > 0.900 in patients without T2DM. When we excluded patients with morbid obesity, the differentiation ability of APRI was improved, reaching AUC = 0.802 for differentiating the presence of fibrosis F2–4 vs. F0–1. The recommended by current guidelines index FIB-4 seemed to differentiate adequately between severe (i.e., F3–4) and mild or moderate fibrosis (F0–2) with an AUC = 0.820, yet this was not the case when FIB-4 was used to classify patients with fibrosis F2–4 vs. F0–1. Trying to improve the predictive value of all NITs, using Youden's methodology, to optimize the suggested cut-off points did not materially improve the results.Conclusions: The validation of currently available NITs using biopsy-proven samples provides new evidence for their ability to differentiate between specific disease stages, histological features, and, most importantly, fibrosis grading. The overall performance of the examined NITs needs to be further improved for applications in the clinic

    Liver biopsy-based validation, confirmation and comparison of the diagnostic performance of established and novel non-invasive non-alcoholic fatty liver disease indexes:Results from a large multi-center study

    Get PDF
    Background: Non-invasive tools (NIT) for non-alcoholic fatty liver disease (NAFLD) screening or diagnosis need to be thoroughly validated using liver biopsies.Purpose: To externally validate NITs designed to differentiate the presence or absence of liver steatosis as well as more advanced disease stages, to confirm fully validated indexes (n = 7 NITs), to fully validate partially validated indexes (n = 5 NITs), and to validate for the first time one new index (n = 1 NIT).Methods: This is a multi-center study from two Gastroenterology-Hepatology Departments (Greece and Australia) and one Bariatric-Metabolic Surgery Department (Italy). Overall, n = 455 serum samples of patients with biopsy-proven NAFLD (n = 374, including 237 patients with non-alcoholic steatohepatitis (NASH)) and Controls (n = 81) were recruited. A complete validation analysis was performed to differentiate the presence of NAFLD vs. Controls, NASH vs. NAFL, histological features of NASH, and fibrosis stages.Results: The index of NASH (ION) demonstrated the highest differentiation ability for the presence of NAFLD vs. Controls, with the area under the curve (AUC) being 0.894. For specific histological characterization of NASH, no NIT demonstrated adequate performance, while in the case of specific features of NASH, such as hepatocellular ballooning and lobular inflammation, ION demonstrated the best performance with AUC being close to or above 0.850. For fibrosis (F) classification, the highest AUC was reached by the aspartate aminotransferase to platelet ratio index (APRI) being ~0.850 yet only with the potential to differentiate the severe fibrosis stages (F3, F4) vs. mild or moderate fibrosis (F0–2) with an AUC > 0.900 in patients without T2DM. When we excluded patients with morbid obesity, the differentiation ability of APRI was improved, reaching AUC = 0.802 for differentiating the presence of fibrosis F2–4 vs. F0–1. The recommended by current guidelines index FIB-4 seemed to differentiate adequately between severe (i.e., F3–4) and mild or moderate fibrosis (F0–2) with an AUC = 0.820, yet this was not the case when FIB-4 was used to classify patients with fibrosis F2–4 vs. F0–1. Trying to improve the predictive value of all NITs, using Youden's methodology, to optimize the suggested cut-off points did not materially improve the results.Conclusions: The validation of currently available NITs using biopsy-proven samples provides new evidence for their ability to differentiate between specific disease stages, histological features, and, most importantly, fibrosis grading. The overall performance of the examined NITs needs to be further improved for applications in the clinic
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