435 research outputs found
A phylogenetic comparative analysis on the evolution of sequential hermaphroditism in seabreams (Teleostei : Sparidae)
The Sparids are an ideal group of fish in which to study the evolution of sexual systems since they
exhibit a great sexual diversity, from gonochorism (separate sexes) to protandrous (male-first) and
protogynous (female-first) sequential hermaphroditism (sex-change). According to the size-advantage
model (SAM), selection should favour sex change when the second sex achieves greater reproductive
success at a larger body size than the first sex. Using phylogenetic comparative methods and a sample
of 68 sparid species, we show that protogyny and protandry evolve from gonochorism but evolutionary
transitions between these two forms of sequential hermaphroditism are unlikely to happen. Using male
gonadosomatic index (GSI) as a measure of investment in gametes and proxy for sperm competition,
we find that, while gonochoristic and protogynous species support the predictions of SAM, protandrous
species do not, as they exhibit higher GSI values than expected even after considering mating
systems and spawning modes. We suggest that small males of protandrous species have to invest
disproportionally more in sperm production than predicted not only when spawning in aggregations
with high levels of sperm competition, but also when spawning in pairs due to the need to fertilize
highly fecund females, much larger than themselves. We propose that this compensatory mechanism,
together with Bateman’s principles in sequential hermaphrodites, should be formally incorporated in
the SAM
Inclusive University didactics and technological devices: a case study
This paper provides a review of projects related to new technologies used to favour the teaching-learning processes and the inclusive practices in the University context for students with disabilities and with Specific Learning Disorders. Authors present a review of strategies, trajectories and perspectives activated in the national and international scene, aiming to guarantee a significant pedagogical framework of reference. Furthermore, the paper focuses on a meaningful path activated at the University of Macerata, the project Inclusion 3.0, a relevant example of new technologies in support of teaching- learning processes and inclusion practices among all students
Effects of Uncertainty of Outlet Boundary Conditions in a Patient-Specific Case of Aortic Coarctation
Computational Fluid Dynamics (CFD) simulations of blood flow are widely used to compute a variety of hemodynamic indicators such as velocity, time-varying wall shear stress, pressure drop, and energy losses. One of the major advances of this approach is that it is non-invasive. The accuracy of the cardiovascular simulations depends directly on the level of certainty on input parameters due to the modelling assumptions or computational settings. Physiologically suitable boundary conditions at the inlet and outlet of the computational domain are needed to perform a patient-specific CFD analysis. These conditions are often affected by uncertainties, whose impact can be quantified through a stochastic approach. A methodology based on a full propagation of the uncertainty from clinical data to model results is proposed here. It was possible to estimate the confidence associated with model predictions, differently than by deterministic simulations. We evaluated the effect of using three-element Windkessel models as the outflow boundary conditions of a patient-specific aortic coarctation model. A parameter was introduced to calibrate the resistances of the Windkessel model at the outlets. The generalized Polynomial Chaos method was adopted to perform the stochastic analysis, starting from a few deterministic simulations. Our results show that the uncertainty of the input parameter gave a remarkable variability on the volume flow rate waveform at the systolic peak simulating the conditions before the treatment. The same uncertain parameter had a slighter effect on other quantities of interest, such as the pressure gradient. Furthermore, the results highlight that the fine-tuning of Windkessel resistances is not necessary to simulate the post-stenting scenario
Switches, stability and reversals in the evolutionary history of sexual systems in fish
Sexual systems are highly diverse and have profound consequences for population dynamics and resilience. Yet, little is known about how they evolved. Using phylogenetic Bayesian modelling and a sample of 4614 species, we show that gonochorism is the likely ancestral condition in teleost fish. While all hermaphroditic forms revert quickly to gonochorism, protogyny and simultaneous hermaphroditism are evolutionarily more stable than protandry. In line with theoretical expectations, simultaneous hermaphroditism does not evolve directly from gonochorism but can evolve slowly from sequential hermaphroditism, particularly protandry. We find support for the predictions from life history theory that protogynous, but not protandrous, species live longer than gonochoristic species and invest the least in male gonad mass. The distribution of teleosts’ sexual systems on the tree of life does not seem to reflect just adaptive predictions, suggesting that adaptations alone may not fully explain why some sexual forms evolve in some taxa but not others (Williams’ paradox). We propose that future studies should incorporate mating systems, spawning behaviours, and the diversity of sex determining mechanisms. Some of the latter might constrain the evolution of hermaphroditism, while the non-duality of the embryological origin of teleost gonads might explain why protogyny predominates over protandry in teleosts
Characterization of gaze in handwriting of High and Low Frequency Word of Schoolchildren with Dyslexia
Writing is extremely important for our academic and professional life and can affect our performance in productive educational activities, favouring us or not. Schoolchildren with dyslexia bring difficulties and reduced school performance due to their condition of deprivation in written production. This is because schoolchildren with dyslexia have difficulty acquiring spelling knowledge and show poor phonological skills. This study aimed to characterize the performance of schoolchildren with dyslexia in “gaze” for the handwriting of High and Low-frequency words. A total of 24 schoolchildren participated in the study. They were between 8 to 11 years and 11 months of age, of both sexes, and they were attending the 3rd to the 5th year of Elementary School in the city of Marília-SP. The schoolchildren were divided into groups: GI, composed of 12schoolchildren with an interdisciplinary diagnosis of developmental dyslexia, and GII, composed of 12 schoolchildren with good academic performance, paired with GI according to the school grade level. These schoolchildren were submitted to computerized handwriting evaluation using a Brazilian adaptation of the Software Ductus. All schoolchildren were submitted to a copy of words already selected according to Brazilian Portuguese criteria of frequency and codification rule. A measure of “gaze” was used, that is, when the schoolchildren stopped their handwriting to search/look up at the screen to confirm the information about the words. The results indicated a significant difference between GI and GII, with GI schoolchildren performing more gaze when compared with GII, i.e., taking longer motor breaks to perform the gaze. Therefore, there was a rupture in the central processing with the peripheral when the child performed the gauze more times since he had to confirm the characteristics of this word during the writing process (difficulty in accessing the orthographic lexicon) and with that, there was a break in the movement of handwriting (since there was not enough information in the central plane to complete that motor memory and finish the word). It was concluded that there were gaps between the central (orthographic) and peripheral (motor pauses processes, suggesting deficits in the formation of motor programs for GI and the lack of automation of motor processes
Atomic-Scale Insights into Semiconductor Heterostructures: From Experimental Three-Dimensional Analysis of the Interface to a Generalized Theory of Interfacial Roughness Scattering
In this manuscript, we develop a generalized theory for the scattering process produced by interface roughness on charge carriers that is suitable for any semiconductor heterostructure. By exploiting our experimental insights into the three-dimensional atomic landscape of Ge/Ge-Si heterointerfaces obtained by atom probe tomography, we are able to define the full set of interface parameters relevant to the scattering potential, including both the in-plane and axial correlation inside real diffuse interfaces. Our experimental findings indicate a partial coherence of the interface roughness along the growth direction within the interfaces. We show that it is necessary to include this feature, previously neglected by theoretical models, when heterointerfaces characterized by finite interface widths are taken into consideration. To show the relevance of our generalized scattering model in the physics of semiconductor devices, we implement it in a nonequilibrium Green's function simulation platform to assess the performance of a Ge/Si-Ge-based terahertz quantum cascade laser
Speed and pressure of handwriting as critical issues of the contemporary age: A research in Italian students in early literacy
Among the present critical issues that pedagogy and special teaching have to
deal with it is possible to notice the contrast between writing and technology,
up to the pertinent field of prevention and observation of dysgraphies. The
authors present in the following article a study conducted in Italy aimed at
evaluating writing, specifically in the speed and pressure parameters in early
literacy using NeuroScript Movalyzer Software. The aim is to implement
suitable research paths to support the dissemination of observation procedures
and inclusive teaching practices, capable of enhancing the fluidity of writing
by all students
Network Physiology reveals relations between network topology and physiological function
The human organism is an integrated network where complex physiologic
systems, each with its own regulatory mechanisms, continuously interact, and
where failure of one system can trigger a breakdown of the entire network.
Identifying and quantifying dynamical networks of diverse systems with
different types of interactions is a challenge. Here, we develop a framework to
probe interactions among diverse systems, and we identify a physiologic
network. We find that each physiologic state is characterized by a specific
network structure, demonstrating a robust interplay between network topology
and function. Across physiologic states the network undergoes topological
transitions associated with fast reorganization of physiologic interactions on
time scales of a few minutes, indicating high network flexibility in response
to perturbations. The proposed system-wide integrative approach may facilitate
the development of a new field, Network Physiology.Comment: 12 pages, 9 figure
Photoluminescence from ultrathin Ge-rich multi-quantum wells observed up to room-temperature: experiments and modeling
Employing a low-temperature growth-mode, we fabricated ultrathin Si1-xGex/Si multiple quantum well (QW) structures with a well thickness of less than 1.5 nm and a Ge concentration above 60 % directly on a Si substrate. We identified an unusual temperature-dependent blueshift of the photoluminescence (PL) and an exceptionally low thermal quenching. We find that this behavior is related to the relative intensities of the no-phonon (NP) peak and a phonon-assisted replica that are the main contributors to the total PL signal. In order to investigate these aspects in more detail, we developed a strategy to calculate the PL spectrum employing a self-consistent multi-valley effective mass model in combination with second-order perturbation theory. According to our investigation, we find that while the phonon-assisted feature decreases with temperature, the NP feature shows a strong increase in the recombination rate. Besides leading to the observed robustness against thermal quenching, this causes the observed blueshift of the total PL signal.T.W. and K.B. were supported by the Stiftung der Deutschen Wirtschaft (sdw) and by the
Deutsche Forschungsgemeinschaft (DFG) through project B10 within the Collaborative
Research Center (CRC) 951 Hybrid Inorganic/Organic Systems for Opto-Electronics. HRTEM
measurements were financed by Xunta de Galica Grant No. GRC2014/008
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