481 research outputs found
Peachy Parallel Assignments (EduHPC 2018)
Peachy Parallel Assignments are a resource for instructors teaching parallel and distributed programming. These are high-quality assignments, previously tested in class, that are readily adoptable. This collection of assignments includes implementing a subset of OpenMP using pthreads, creating an animated fractal, image processing using histogram equalization, simulating a storm of high-energy particles, and solving the wave equation in a variety of settings. All of these come with sample assignment sheets and the necessary starter code.Departamento de Informática (Arquitectura y Tecnología de Computadores, Ciencias de la Computación e Inteligencia Artificial, Lenguajes y Sistemas Informáticos)Facilitar la inclusión de ejercicios prácticos de programación paralela en cursos de Computación Paralela o de alto rendimiento (HPC)Comunicación en congreso: Descripción de ejercicios prácticos con acceso a material ya desarrollado y probado
Unveiling multiple AGN activity in galaxy mergers
In this paper we present an overview of the MAGNA (Multiple AGN Activity)
project aiming at a comprehensive study of multiple supemassive black hole
systems. With the main goal to characterize the sources in merging systems at
different stages of evolution, we selected a sample of objects optically
classified as multiple systems on the basis of emission line diagnostics and
started a massive multiband observational campaign. Here we report on the
discovery of the exceptionally high AGN density compact group SDSS~J0959+1259.
A multiband study suggests that strong interactions are taking place among its
galaxies through tidal forces, therefore this system represents a case study
for physical mechanisms that trigger nuclear activity and star formation. We
also present a preliminary analysis of the multiple AGN system
SDSS~J1038+3921.}Comment: Proceedings paper for "XMM-Newton: The Next Decade" (held in 2016
May); accepted to be published in Astronomische Nachrichten / Astronomical
Notes (AN
A pathogen complex between the root knot nematode Meloidogyne incognita and Fusarium verticillioides results in extreme mortality of the inka nut (Plukenetia volubilis)
The combined infection of the root knot nematode Meloidogyne incognita and two Fusarium species led to high plant mortality of inka nut (Plukenetia volubilis) seedlings in pots after 80 days growth in two independent inoculation experiments. Inoculation of M. incognita juveniles and conidia of F. solani or F. verticillioides, simultaneously, increased plant mortality by 25-30%, compared with M. incognita alone (5-10% mortality). When inoculated with F. verticillioides at 20 days post nematode inoculation, plant mortality increased to 55%. Either of the Fusarium spp. alone caused some plant mortality, but less than when combined with M. incognita. The synergistic interaction of M. incognita and especially F. verticillioides demonstrates a lethal outcome for inka nuts. It appears that M. incognita creates favorable conditions that lead to enhanced effect and damage by the Fusarium species, especially F. verticillioides, leading to devastating levels of plant death
Shorter telomeres are associated with shell anomalies in a long-lived tortoise
Age-related telomere length (TL) variation is relatively well-described for mammals, birds and other model organisms. Nevertheless, it remains largely unknown in ectotherms, especially turtles and tortoises, which are extremely long-lived species with slow or negligible senescence. In this study, we described TL dynamics in wild spur-thighed tortoises (Testudo graeca), one of the chelonian species with the lowest aging rates. By combining cross-sectional (single) and longitudinal (capture–recapture) samplings, we assessed the relationship between TL and individual characteristics (sex, age, individual growth rate, body condition index, presence of shell anomalies). We did not find any association between TL and sex, individual growth rate, or body condition. However, the relationship with age remains uncertain, likely due to the complex dynamics of TL over time. Interestingly, shorter telomeres correlated significantly with shell anomalies, which are usually assumed as a fitness proxy for reptiles. Overall, our results suggest TL as a potential indicator for ontogenetic studies on tortoises, while its utility as a marker of biological age appears limited.This work was supported by Project PID2019-105682RA-I00 and TED2021-130381B-I00, funded by the Spanish Ministry of Science and Innovation (MCIN/AEI/10.13039/501100011033), the last also with the support of the European Union ‘NextGenerationEU/PRTR’. RCRC is supported by the European Union-Next Generation EU in the Maria Zambrano Programme (ZAMBRANO 21-26)
The shape of mammalian phylogeny: patterns, processes and scales
Mammalian phylogeny is far too asymmetric for all contemporaneous lineages to have had equal chances of diversifying. We consider this asymmetry or imbalance from four perspectives. First, we infer a minimal set of 'regime changes'-points at which net diversification rate has changedidentifying 15 significant radiations and 12 clades that may be 'downshifts'. We next show that mammalian phylogeny is similar in shape to a large set of published phylogenies of other vertebrate, arthropod and plant groups, suggesting that many clades may diversify under a largely shared set of 'rules'. Third, we simulate six simple macroevolutionary models, showing that those where speciation slows down as geographical or niche space is filled, produce more realistic phylogenies than do models involving key innovations. Lastly, an analysis of the spatial scaling of imbalance shows that the phylogeny of species within an assemblage, ecoregion or larger area always tends to be more unbalanced than expected from the phylogeny of species at the next more inclusive spatial scale. We conclude with a verbal model of mammalian macroevolution, which emphasizes the importance to diversification of accessing new regions of geographical or niche space
Dissecting the stellar content of Leo:A dwarf irregular caught in transition
Leo I is considered one of the youngest dwarf spheroidals (dSph) in the Local
Group. Its isolation, extended star formation history (SFH), and recent
perigalacticon passage (~1 Gyr ago) make Leo~I one of the most interesting
nearby stellar systems. Here, we analyse deep photometric Hubble Space
Telescope data via colour-magnitude diagram fitting techniques to study its
global and radially-resolved SFH. We find global star formation enhancements in
Leo I ~13, 5.5, 2.0, and 1.0 Gyr ago, after which it was substantially
quenched. Within the context of previous works focused on Leo I, we interpret
the most ancient and the youngest ones as being linked to an early formation
(surviving reionisation) and the latest perigalacticon passage (transition from
dIrr to dSph), respectively. We clearly identify the presence of very metal
poor stars ([Fe/H]~-2) ageing ~5-6 and ~13 Gyr old. We speculate with the
possibility that this metal-poor population in Leo I is related to the merging
with a low mass system (possibly an ultra-faint dwarf). This event would have
triggered star formation (peak of star formation ~5.5 Gyr ago) and accumulated
old, metal poor stars from the accreted system in LeoI. Some of the stars born
during this event would also form from accreted gas of low-metallicity (giving
rise to the 5-6 Gyr low-metallicity tail). Given the intensity and extension of
the 2.0 Gyr burst, we hypothesise that this enhancement could also have an
external origin. Despite the quenching of star formation around 1 Gyr ago (most
probably induced by ram pressure stripping with the Milky Way halo at
pericentre), we report the existence of stars as young as 300-500 Myr. We also
distinguish two clear spatial regions: the inner ~190 pc presents an
homogeneous stellar content (size of the gaseous star forming disc in LeoI from
~4.5 to 1 Gyr ago), whereas the outer regions display a clear positive age
gradient.Comment: 20 pages, 11+5 figures, accepted for publication in MNRA
Comportamiento diurno de toretes en pastoreo sobre praderas de Setaria sphacelata en trópico alto de Oxapampa, Perú
The aim of this study was to evaluate the influence of the age of bulls at grazing on their diurnal behaviour in Setaria sphacelata meadows. The forage variables were the availability and nutritive value of the diet, and the animal variables were body weight, size and frequency of bites, and diurnal behaviour. Four Brown Swiss x zebu crossed bulls with an initial live weight of 285.8 ± 18.1 kg that grazed in an area of 29 ha (11 paddocks) were selected from a group of 36 bulls. The evaluations were done when the animals reached the ages of 12 (T1), 15 (T2) and 18 (T3) months. A randomized complete block design was used. Forage availability showed differences (p<0.05) between treatments; however, the forage allocation and the nutritional quality of the diet did not compromise their performance. Bite weight was higher in T3 (0.87 ± 0.22 g per bite; p<0.05), but without differences in bite frequency. Grazing activity was similar for T1 (5.09 ± 0.95 h) and T2 (5.38 ± 0.44 h), but lower (p<0.05) for T3 (4.05 ± 0.22 h). Younger bulls (T1) spent less time ruminating, and more time in grazing and other activities. The highest frequency of grazing occurred at the end of the daytime (16:00 to 18:00 h). It is concluded that the age of bull influences their diurnal behaviour, causing older bulls spent less time in grazing and increase the size of bites and rumination time.El objetivo del estudio fue evaluar la influencia de la edad de toretes al pastoreo sobre su comportamiento diurno en praderas de Setaria sphacelata. Las variables forrajeras fueron la disponibilidad y valor nutritivo de la dieta, y las variables animales fueron el peso vivo, tamaño y frecuencia de bocados, y comportamiento diurno. De un lote de 36 toretes se seleccionaron cuatro toretes cruzados Brown Swiss x cebú con un peso vivo inicial de 285.8 ± 18.1 kg que pastoreaban en un área de 29 ha (11 potreros). Las evaluaciones se hicieron cuando los animales alcanzaron las edades de 12 (T1), 15 (T2) y 18 (T3) meses. Se utilizó un diseño en bloque completo al azar. La disponibilidad forrajera presentó diferencias (p<0.05) entre tratamientos; no obstante, la asignación forrajera y la calidad nutritiva de la dieta no comprometió su comportamiento. El peso de los bocados fue mayor en T3 (0.87 ± 0.22 g por bocado; p<0.05), pero sin diferencias en la frecuencia de bocados. La actividad de pastoreo fue similar para T1 (5.09 ± 0.95 h) y T2 (5.38 ± 0.44 h), pero inferior (p<0.05) para T3 (4.05 ± 0.22 h). Los toretes de menor edad (T1) dedicaron menos tiempo a la rumia, y mayor tiempo al pastoreo y otras actividades. La mayor frecuencia de pastoreo se presentó al finalizar el tiempo diurno (16:00 a 18:00 h). Se concluye que la edad de los toretes influye en su comportamiento diurno, haciendo que toretes de mayor edad dediquen menos tiempo al pastoreo e incrementen el tamaño de bocados y el tiempo de rumia
CAST constraints on the axion-electron coupling
In non-hadronic axion models, which have a tree-level axion-electron interaction, the Sun produces a strong axion flux by bremsstrahlung, Compton scattering, and axiorecombination, the "BCA processes." Based on a new calculation of this flux, including for the first time axio-recombination, we derive limits on the axion-electron Yukawa coupling gae and axion-photon interaction strength ga using the CAST phase-I data (vacuum phase). For ma <~ 10 meV/c2 we find ga gae < 8.1 × 10−23 GeV−1 at 95% CL. We stress that a next-generation axion helioscope such as the proposed IAXO could push this sensitivity into a range beyond stellar energy-loss limits and test the hypothesis that white-dwarf cooling is dominated by axion emission
Tacrolimus’s Time Below Therapeutic Range Is Associated With Acute Pancreatic Graft Rejection and the Development of De Novo Donor-specific Antibodies
Tacrolimus is pivotal in pancreas transplants but poses challenges in maintaining optimal levels due to recipient differences. This study aimed to explore the utility of time spent below the therapeutic range and intrapatient variability in predicting rejection and de novo donor-specific antibody (dnDSA) development in pancreas graft recipients. This retrospective unicentric study included adult pancreas transplant recipients between January 2006 and July 2020. Recorded variables included demographics, immunosuppression details, HLA matching, biopsy results, dnDSA development, and clinical parameters. Statistical analysis included ROC curves, sensitivity, specificity, and predictive values. A total of 131 patients were included. Those with biopsy-proven acute rejection (BPAR, 12.2%) had more time (39.9% ± 24% vs. 25.72% ± 21.57%, p = 0.016) and tests (41.95% ± 13.57% vs. 29.96% ± 17.33%, p = 0.009) below therapeutic range. Specific cutoffs of 31.5% for time and 34% for tests below the therapeutic range showed a high negative predictive value for BPAR (93.98% and 93.1%, respectively). Similarly, patients with more than 34% of tests below the therapeutic range were associated with dnDSA appearance (38.9% vs. 9.4%, p = 0.012; OR 6.135, 1.346–27.78). In pancreas transplantation, maintaining optimal tacrolimus levels is crucial. Suboptimal test percentages below the therapeutic range prove valuable in identifying acute graft rejection risk
Incidence of severe breakthrough SARS-CoV-2 infections in vaccinated kidney transplant and haemodialysis patients
Introduction: Given the increased COVID-19 observed in kidney transplant recipients (KTRs) and haemodialysis patients, several studies have tried to establish the efficacy of mRNA vaccines in these populations by evaluating their humoral and cellular responses. However, there is currently no information on clinical protection (deaths and hospitalizations), a gap that this study aims to fill. Methods: Observational prospective study involving 1,336 KTRs and haemodialysis patients from three dialysis units affiliated to Hospital Clínic of Barcelona, Spain, vaccinated with two doses of mRNA-1273 (Moderna) or BNT162b2 (Pfizer-BioNTech) SARS-CoV-2 mRNA vaccines. The outcomes measured were SARS-CoV-2 infection diagnosed by a positive RT-PCR fourteen days after the second vaccine dose, hospital admissions derived from infection, and a severe COVID-19 composite outcome, defined as either ICU admission, invasive and non-invasive mechanical ventilation, or death. Results: Six per cent (18/302) of patients on haemodialysis were infected, of whom four required hospital admission (1.3%), only one (0.3%) had severe COVID-19, and none of them died. In contrast, 4.3% (44/1034) of KTRs were infected, and presented more hospital admissions (26 patients, 2.5%), severe COVID-19 (11 patients, 1.1%) or death (4 patients, 0.4%). KTRs had a significantly higher risk of hospital admission than HD patients, and this risk increased with age and male sex (HR 3.37 and 4.74, respectively). Conclusions: The study highlights the need for booster doses in KTRs. In contrast, the haemodialysis population appears to have an adequate clinical response to vaccination, at least up to four months from its administration
- …