For years researchers have tried to understand the molecular behavior of complex biomolecules through the development of small molecules that can partially mimic their function. Now researchers are ...implementing the reverse approach: using the structural and mechanistic knowledge obtained from those complex systems to design small molecules with defined properties and for specific applications. One successful strategy for constructing bioinspired, minimalistic molecules is to combine natural building blocks that provide functional elements with abiotic fragments that serve as structural scaffolds. Therefore pseudopeptidic compounds, most of them based on C 2 symmetric structures, represent a unique opportunity to explore and evaluate this approach. Some of these molecules are as simple as two amino acids connected by a diamino spacer. The results in this Account show how bioinspired minimalistic pseudopeptides can form ordered structures, participate in the recognition and transcription of information events in molecular devices, and catalyze reactions. This strategy allows researchers to design and prepare a variety of open-chain and macrocyclic compounds leading to systems that can self-aggregate to form hierarchically ordered micro- and nanostructures. In addition, small changes in the molecule or external stimuli can regulate the self-aggregation pattern. In the same way, researchers can also tune the molecular movements of simple pseudopeptides through environmental factors, providing a means to control new molecular devices. In addition, some of the prepared model compounds have shown interesting properties in molecular recognition and even as sensors for several targets of interest. Finally we have observed remarkable catalytic activities from these types of molecules, although those results are still far from the efficiency shown by natural peptides. This family of pseudopeptidic compounds offers the opportunity for the more elaborate design of relatively simple abiotic but bioinspired systems that display specific properties. In addition, the results can provide additional information that will increase the molecular understanding of the basic principles that underlie the extraordinary behavior of natural systems.
We study the relationship between the spatial distribution of imperviousness and the space‐time variability of rainfall, runoff generation, and hydrologic response. For this study we follow an ...analytical framework that is able to represent space‐time variability and use it to determine relationships for quantities commonly used in hydrology, for example, the amount of rainfall excess, the total runoff from a storm, the runoff ratio of developed land use to undeveloped land use, and the mean time and variance of the runoff time. The relationships are derived such that the space‐time variability of rainfall, runoff, and the hydrologic response, and their relative importance, can be identified and compared. In addition, the method allows the separation of pervious and impervious contributions to runoff and the estimation of their relative influence on the hydrologic response. We illustrate the estimation of the relationships from available data and apply them to two cases. In the first case, the space‐time variability of rainfall and its interaction with impervious cover is investigated. In the second case, we examine the impacts of the imperviousness pattern on runoff relationships. We find that the imperviousness and rainfall pattern can interact to either increase or decrease the average amount of rainfall excess. We also find that the influence of pervious and impervious contributions on the response can depend on the form of the overall imperviousness pattern. The proposed framework can be a useful tool for identifying the importance of different space‐time hydrologic components in mixed pervious‐impervious landscapes.
Cable-driven parallel robots are a special type of robot in which an end-effector is attached to a fixed frame by means of several cables. The position and orientation of the end-effector can be ...controlled by controlling the length of the cables. These robots present a wide range of advantages, and the control algorithms required have greater complexity than those in traditional serial robots. Measuring the cable tension is an important task in this type of robot as many control algorithms rely on this information. There are several well-known approaches to measure cable tension in cable robots, where a trade-off between complexity and accuracy is observed. This work presents a new device based on strain gauges to measure cable tension specially designed to be applied in cable-driven parallel robots. This device can be easily mounted on the cable near the fixed frame, allowing the cable length and orientation to change freely, while the measure is taken before the cable passes through the guiding pulleys for improved accuracy. The results obtained from the device show a strong repeatability and linearity of the measures
Melanin‐concentrating hormone (MCH) neurons within the hypothalamus are heterogeneous and can coexpress additional neuropeptides and transmitters. The majority of MCH neurons express vesicular ...transporters to package glutamate for synaptic release, and MCH neurons can directly innervate downstream neurons via glutamate release. Although glutamatergic signalling from MCH neurons may support physiological and behavioural roles that are independent of MCH (e.g., in glucose homeostasis and nutrient‐sensing), it can also mediate similar roles to MCH in the regulation of energy balance. In addition to energy balance, the MCH system has also been implicated in mood disorders, as MCH receptor antagonists have anxiolytic and anti‐depressive effects. However, the contribution of glutamatergic signalling from MCH neurons to mood‐related functions have not been investigated. We crossed Mch‐cre mice with floxed‐Vglut2 mice to delete the expression of the vesicular glutamate transporter 2 (Vglut2) and disable glutamatergic signalling specifically from MCH neurons. The resulting Mch‐Vglut2‐KO mice showed Vglut2 deletion from over 75% of MCH neurons, and although we did not observe changes in depressive‐like behaviours, we found that Mch‐Vglut2‐KO mice displayed anxiety‐like behaviours. Mch‐Vglut2‐KO mice showed reduced exploratory activity when placed in a new cage and were quicker to consume food placed in the centre of a novel open arena. These findings showed that Vglut2 deletion from MCH neurons resulted in anxiolytic actions and suggested that the anxiogenic effects of glutamate are similar to those of the MCH peptide. Taken together, these findings suggest that glutamate and MCH may synergize to regulate and promote anxiety‐like behaviour.
Disrupting glutamate release from MCH cells suppressed anxiety‐like behaviours when interacting with novel contexts, for example in a new home environment or when approaching a new food.
Introduction
The extent to which social media contributes to body image dissatisfaction and lower self-esteem is currently under debate
Objectives
This research seeks to study the relationship ...between the use of Instagram (one of the main platforms used by young people nowadays) and the degree of dissatisfaction with body image and the level of self-esteem among their younger users
Methods
A sample of 585 Spanish adults between 18 and 40 years old was used, to whom the Body Shape Questionnaire (BSQ), the Rosenberg Self-esteem Scale and the Social Comparison of Appearance Scale (PACS) were applied.
Results
A positive correlation was observed between the frequency of use of the social network and dissatisfaction with body image and low self-esteem. In addition, it was found that content observation time significantly predicts body dissatisfaction and low self-esteem. On the other hand, the type of content both published and observed, showed no effect on any of these variables, although it has been found that the relationship between the use of the platform and the study variables seems to be mediated by the tendency of their users to compare their appearance with others.
Conclusions
These results invite us to reflect on the use of social networks and their impact on constructs as relevant to the person as self-esteem and body image and on how different policies should be taken into account to prevent a negative impact on the mental health of their users
Disclosure
No significant relationships.
Uncertainties in the satellite world lines lead to dominant positioning errors. In the present work, using the approach presented in Puchades and Sáez (Astrophys. Space Sci. 352, 307–320,
2014
), a ...new analysis of these errors is developed inside a great region surrounding Earth. This analysis is performed in the framework of the so-called Relativistic Positioning Systems (RPS). Schwarzschild metric is used to describe the satellite orbits corresponding to the Galileo Satellites Constellation. Those orbits are circular with the Earth as their centre. They are defined as the nominal orbits. The satellite orbits are not circular due to the perturbations they have and to achieve a more realistic description such perturbations need to be taken into account. In Puchades and Sáez (Astrophys. Space Sci. 352, 307–320,
2014
) perturbations of the nominal orbits were statistically simulated. Using the formula from Coll et al. (Class. Quantum Gravity. 27, 065013,
2010
) a user location is determined with the four satellites proper times that the user receives and with the satellite world lines. This formula can be used with any satellite description, although photons need to travel in a Minkowskian space-time. For our purposes, the computation of the photon geodesics in Minkowski space-time is sufficient as demonstrated in Puchades and Sáez (Adv. Space Res. 57, 499–508,
2016
). The difference of the user position determined with the nominal and the perturbed satellite orbits is computed. This difference is defined as the U-error. Now we compute the perturbed orbits of the satellites considering a metric that takes into account the gravitational effects of the Earth, the Moon and the Sun and also the Earth oblateness. A study of the satellite orbits in this new metric is first introduced. Then we compute the U-errors comparing the positions given with the Schwarzschild metric and the metric introduced here. A Runge-Kutta method is used to solve the satellite geodesic equations. Some improvements in the computation of the U-errors using both metrics are introduced with respect to our previous works. Conclusions and perspectives are also presented.
The effects of a bimodal microstructure and porosity on the elastic modulus and yield strength of a Ti-13Ta-12Sn alloy foam was analyzed. In order to obtain a bimodal microstructure, the powder ...metallurgy approach was used, with the amount of Sn being chosen depending on a thermodynamic analysis, so that there could be a bcc solid solution after the consolidation process. The foams were obtained using an ammonium carbonate space holder (30, 40 and 50 v/v% porosity). Foams with a bimodal microstructure were synthetized by mixing 50 wt% of milled powder (at 50 h) + 50 wt% unmilled powder, while foam without a bimodal microstructure were synthetized using only milled powders. The elastic modulus and compression yield strength were experimentally measured and compared with estimations given by the Gibson-Ashby model and finite element analysis. The foams with a bimodal microstructure have shown a higher compression strength (over 70 MPa more) than the samples without bimodal microstructure, for all of the porosity values. The samples with bimodal microstructures, as well as 30, 40 and 50% porosity, have an elastic modulus smaller than 30 GPa and a yield strength over 120 MPa, therefore, having a great potential to be explored for biomedical applications.
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•The effects of a bimodal microstructure and porosity on the elastic modulus and strength of Ti-13Ta-12Sn foam was analyzed.•The samples with bimodal microstructures having a great potential to be explored for biomedical applications.•The foams with bimodal microstructure have shown higher compression strength than the samples without bimodal microstructure.
Ti-based alloys are being widely used as bio-implant materials because of their excellent properties. This work reports the synthesis of Ti–30Nb–13Ta–2Mn (wt. %) foams with and without bimodal ...microstructure using NaCl (0, 20 and 30 vol %) as space-holder particles (SHP). Samples with bimodal microstructure were obtained by mixing milled and un-milled powders in a proportion of 1:4. Samples without bimodal microstructure were synthesized using only un-milled powders. Hot pressing was used to consolidate the green samples using argon gas as protective atmosphere under 30 MPa at 780 °C for 30 min. The consolidated metallic foams were characterized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) to study their microstructure and phase analyses. The Young's modulus values were between 39 and 19 GPa, and the yield strength values were obtained between 180 and 400 MPa. From the mechanical properties point of view, samples with bimodal microstructure and with 20 and 30 vol % of NaCl have a great potential to be explored for biomedical applications due to their mechanical properties of Young's modulus smaller than 30 GPa and yield strength higher than 180 MPa. Further, the foams were modelled using finite element analysis (FEA) with random distribution of the pores in order to estimate the compressive behavior, and the Young's modulus measured using FEA was in an excellent agreement with the experimental data.
Urban development within a watershed can take on a wide and diverse range of spatial patterns. The terms “sprawl” and “clustered” development, for example, are frequent in the literature, spanning ...the spectrum of possible spatial patterns of urban development. The relationship between flood conditions and the spatial distribution of the urban development has been poorly studied, often because of limitations in streamflow data availability or the common use of lumped watershed models in urban hydrologic modeling. We study this relationship with an optimization-based approach that accounts directly for the spatial distribution of imperviousness to investigate how the urban spatial pattern will affect flood peaks and how it can be used to reduce or minimize undesirable impacts to water resources. We employ several water resources-based objective functions to perform optimizations that result in distinct spatial patterns of urbanization showing characteristics of both sprawl and clustered development, depending on the objective function used. We conclude that the approach followed here and the resulting optimized landscapes provide a helpful understanding of the important role played by the spatial form of the urban pattern when trying to minimize impacts to water resources. One objective function, crafted to approximate ecologically based imperviousness threshold policies, resulted in an optimized urbanization pattern suggesting that unintended consequences of low density sprawl may follow from such policies. This specific finding underscores the general value of our optimization-based approach for planning and managing new urban development around water resources.
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