714 research outputs found
Modes of covariability between sea surface temperature and wind stress intraseasonal anomalies along the coast of Peru from satellite observations (2000-2008)
The Tropical Rainfall Measuring Mission Microwave Imager sea surface temperature (SST) and QuikSCAT wind stress satellite data are used to investigate the intraseasonal upwelling variability along the coat of Peru over the period 2000-2008. Two regions of peak variance correspond to the central Peru region (Pisco region, 15 degrees S) and the northern Peru region (Piura region, 5 degrees S). A covariance analysis reveals a significant coherency between winds and SST anomalies off Pisco, consistent with Ekman pumping and transport dynamics. The upwelling cell consists in a meridionally extended fringe of colder (warmer) water extending as far as 250 km from the coast at 15 degrees S. In the Piura region, the intraseasonal covariability pattern is represented by two modes, one relevant to the direct Ekman dynamics and the other one associated with the remote forcing of intraseasonal oceanic Kelvin wave. Two regimes of variability are evidenced. A low-period regime (10-25 days) is the signature of Ekman transport/pumping dynamics and is remotely forced by the migratory atmospheric disturbances across the southeastern Pacific anticyclone. A high-period regime (35-60 day band) is associated with the combined forcing of oceanic equatorial Kelvin waves and migratory atmospheric disturbances in the midlatitudes. In particular, the modes of covariability exhibit a prominent similar to 50 day period energy peak. It is shown that this period arises from the impact of the first two baroclinic modes Kelvin wave, with the second baroclinic mode Kelvin wave being more influential on the Piura region
The effect of flares on total solar irradiance
Flares are powerful energy releases occurring in stellar atmospheres. Solar
flares, the most intense energy bursts in the solar system, are however hardly
noticeable in the total solar luminosity. Consequently, the total amount of
energy they radiate 1) remains largely unknown and 2) has been overlooked as a
potential contributor to variations in the Total Solar Irradiance (TSI), i.e.
the total solar flux received at Earth. Here, we report on the detection of the
flare signal in the TSI even for moderate flares. We find that the total energy
radiated by flares exceeds the soft X-ray emission by two orders of magnitude,
with an important contribution in the visible domain. These results have
implications for the physics of flares and the variability of our star.Comment: accepted in Nature Physic
The seasonal relationship between intraseasonal tropical variability and ENSO in CMIP5
The El Niño–Southern Oscillation (ENSO) is tightly linked to the
intraseasonal tropical variability (ITV) that contributes to energise the
deterministic ocean dynamics during the development of El Niño. Here, the
relationship between ITV and ENSO is assessed based on models from the
Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) taking into
account the so-called diversity of ENSO, that is, the existence of two types
of events (central Pacific versus eastern Pacific El Niño). As a first
step, the models' skill in simulating ENSO diversity is assessed. The
characteristics of the ITV are then documented revealing a large dispersion
within an ensemble of 16 models. A total of 11 models exhibit some skill in
simulating the key aspects of the ITV for ENSO: the total variance along the
Equator, the seasonal cycle and the characteristics of the propagation along
the Equator of the Madden–Julian oscillation (MJO) and the convectively
coupled equatorial Rossby (ER) waves. Five models that account realistically
for both the two types of El Niño events and ITV characteristics are used
for the further analysis of seasonal ITV ∕ ENSO relationship. The results
indicate a large dispersion among the models and an overall limited skill in
accounting for the observed seasonal ITV ∕ ENSO relationship.
Implications of our results are discussed in light of recent studies on the
forcing mechanism of ENSO diversity
Knowledge-based energy functions for computational studies of proteins
This chapter discusses theoretical framework and methods for developing
knowledge-based potential functions essential for protein structure prediction,
protein-protein interaction, and protein sequence design. We discuss in some
details about the Miyazawa-Jernigan contact statistical potential,
distance-dependent statistical potentials, as well as geometric statistical
potentials. We also describe a geometric model for developing both linear and
non-linear potential functions by optimization. Applications of knowledge-based
potential functions in protein-decoy discrimination, in protein-protein
interactions, and in protein design are then described. Several issues of
knowledge-based potential functions are finally discussed.Comment: 57 pages, 6 figures. To be published in a book by Springe
Facial expressions depicting compassionate and critical emotions: the development and validation of a new emotional face stimulus set
Attachment with altruistic others requires the ability to appropriately process affiliative and kind facial cues. Yet there is no stimulus set available to investigate such processes. Here, we developed a stimulus set depicting compassionate and critical facial expressions, and validated its effectiveness using well-established visual-probe methodology. In Study 1, 62 participants rated photographs of actors displaying compassionate/kind and critical faces on strength of emotion type. This produced a new stimulus set based on N = 31 actors, whose facial expressions were reliably distinguished as compassionate, critical and neutral. In Study 2, 70 participants completed a visual-probe task measuring attentional orientation to critical and compassionate/kind faces. This revealed that participants lower in self-criticism demonstrated enhanced attention to compassionate/kind faces whereas those higher in self-criticism showed no bias. To sum, the new stimulus set produced interpretable findings using visual-probe methodology and is the first to include higher order, complex positive affect displays
Self-regulation: differences by year and area in college students
Neste estudo procura-se analisar a existência de diferenças nas estratégias auto-regulatórias de alunos universitários em áreas de formação distintas. Participaram 518 alunos de três níveis (inicial, intermédio e final) das áreas de ciências e humanidades. Aplicou-se a escala “CHE – Comportamentos e hábitos de estudo e aprendizagem”, que avalia cinco dimensões: estratégias cognitivas de transformação e manipulação da informação, organização e planeamento de rotinas, gestão e monitorização, aquisição e selecção da informação, e reforço motivacional. Verificou-se uma maior utilização das estratégias cognitivas e metacognitivas de gestão e monitorização apesar dos resultados não indicarem diferenças substantivas entre os alunos diferenciados por nível e área. Os resultados podem indicar estabilidade nos comportamentos ou limitações no tipo de instrumento e amostra utilizada. O estudo de mudanças nestas estratégias deverá ser conduzido com recurso a delineamentos longitudinais. O impacto da estabilidade deverá ser ponderado na elaboração de projectos de intervenção.In this study we seek to analyze the existence of differences in self-regulating strategies of university students in distinct graduation areas. 518 students of three levels (initial, intermediate and final) of science and humanities fields participated. We used the scale “Behavior and study skill”, which evaluates five dimensions: cognitive strategies of transformation and manipulation of information, organization and planning of routines, management and monitoring, information acquisition and selection, and motivational reinforcement. A higher use of cognitive and metacognitive strategies of management and monitoring was noted although the results do not indicate major differences between students in different levels and graduation areas. The results can indicate stability in the behaviors or limitations in the type of instrument and in the sample used. The study of changes in these strategies must be carried out having in mind longitudinal outlines. The impact of the stability should be taken into account while elaborating intervention projects.(undefined
Acute kidney disease and renal recovery : consensus report of the Acute Disease Quality Initiative (ADQI) 16 Workgroup
Consensus definitions have been reached for both acute kidney injury (AKI) and chronic kidney disease (CKD) and these definitions are now routinely used in research and clinical practice. The KDIGO guideline defines AKI as an abrupt decrease in kidney function occurring over 7 days or less, whereas CKD is defined by the persistence of kidney disease for a period of > 90 days. AKI and CKD are increasingly recognized as related entities and in some instances probably represent a continuum of the disease process. For patients in whom pathophysiologic processes are ongoing, the term acute kidney disease (AKD) has been proposed to define the course of disease after AKI; however, definitions of AKD and strategies for the management of patients with AKD are not currently available. In this consensus statement, the Acute Disease Quality Initiative (ADQI) proposes definitions, staging criteria for AKD, and strategies for the management of affected patients. We also make recommendations for areas of future research, which aim to improve understanding of the underlying processes and improve outcomes for patients with AKD
Evolution of biogeochemical properties inside poleward undercurrent eddies in the southeast Pacific Ocean
Oceanic eddies are ubiquitous features of the circulation thought to be involved in transporting water mass properties over long distances from their source region. Among these is a particular type that has a core within the thermocline with little surface expression. Despite their significance, their role in ocean circulation remains largely undocumented by observations. This study characterizes the variations in internal biogeochemistry, disparities with external properties, and processes influencing the dissolved oxygen budget of poleward undercurrent eddies (PUDDIES) during their transit to oceanic waters. Employing a high-resolution coupled simulation of the Southeast Pacific, we document biogeochemical properties and processes associated with the nitrogen cycle inside PUDDIES and contrast them with those of the surrounding environment. Our findings reveal that PUDDIES capture a biogeochemical signal contingent upon their formation location along the coast, particularly associated with the core of the Peru–Chile Undercurrent at the core of the oxygen minimum zone (OMZ). While permeability at the periphery facilitates exchange with external waters, thereby modulating the original properties, the core signal retains negative oxygen (O2) anomalies and positive anomalies of other biogeochemical tracers. These anomalous conditions result in tracer values exceeding the 90th percentile of their distribution in the open ocean, in contrast to the formation zones, where anomalies only surpass the 50th percentile. This indicates that PUDDIES may play a role in modulating the average properties of the open ocean. Suboxic (O2<20 µM) cores are prevalent near the coast but decrease in abundance with distance from shore, giving way to a predominance of hypoxic (20 µM
< O2<45 µM) cores (predominating at 60 % in the open sea), suggesting core ventilation during transit. The principal mechanism governing O2 input to or output from the eddy core entails lateral and vertical advection, with vertical mixing supplying O2 to a lesser extent. Biological activity consumes O2 inside PUDDIES for around 6 to 12 months, especially intensely for the first 100 d, thus facilitating the persistence of low O2 conditions and extending the lifetime of biogeochemical anomalies within the core (up to 800 km offshore). Ammonium and nitrite deplete earlier in the eddy core with a decay rate greater than that of nitrate and nitrous oxide, while these accumulate in the open sea (up to 16 % and 100 % higher than the mean state, respectively). Our results suggest that southern regions of the southeast Pacific OMZ undergo greater deoxygenation and nutrient enrichment due to PUDDIES compared to northern regions. However, the combination of various physical conditions can generate zones with more pronounced changes in the nitrite (subsurface water masses due to interactions with the PUDDIES, such as at 30° S). The maximum contribution of NO2- takes place in particular along this latitude, with a 460 % increase compared to the mean state, near the coastal zone.
In summary, PUDDIES formed along the Chilean coast capture distinct biogeochemical “signatures” depending on where they form. In the north, minimal ventilation fosters suboxic conditions and denitrification – leading to deficits of nitrate (NO3-) and nitrous oxide (N2O) but high NO2- and ammonium (NH4+) – whereas central and southern subregions show increased NO3- and higher N2O. Moreover, cross-shore exchange between Equatorial Subsurface Water and Subantarctic Water further amplifies this variability, giving rise to eddies with diverse nutrient and oxygen properties as they move offshore.</p
BOLITA, an Arabidopsis AP2/ERF-like transcription factor that affects cell expansion and proliferation/differentiation pathways
The BOLITA (BOL) gene, an AP2/ERF transcription factor, was characterized with the help of an activation tag mutant and overexpression lines in Arabidopsis and tobacco. The leaf size of plants overexpressing BOL was smaller than wild type plants due to a reduction in both cell size and cell number. Moreover, severe overexpressors showed ectopic callus formation in roots. Accordingly, global gene expression analysis using the overexpression mutant reflected the alterations in cell proliferation, differentiation and growth through expression changes in RBR, CYCD, and TCP genes, as well as genes involved in cell expansion (i.e. expansins and the actin remodeling factor ADF5). Furthermore, the expression of hormone signaling (i.e. auxin and cytokinin), biosynthesis (i.e. ethylene and jasmonic acid) and regulatory genes was found to be perturbed in bol-D mutant leave
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