Disentangling the effects of selection and influence is one of social science's greatest unsolved puzzles: Do people befriend others who are similar to them, or do they become more similar to their ...friends over time? Recent advances in stochastic actor-based modeling, combined with self-reported data on a popular online social network site, allow us to address this question with a greater degree of precision than has heretofore been possible. Using data on the Facebook activity of a cohort of college students over 4 years, we find that students who share certain tastes in music and in movies, but not in books, are significantly likely to befriend one another. Meanwhile, we find little evidence for the diffusion of tastes among Facebook friends—except for tastes in classical/jazz music. These findings shed light on the mechanisms responsible for observed network homogeneity; provide a statistically rigorous assessment of the coevolution of cultural tastes and social relationships; and suggest important qualifications to our understanding of both homophily and contagion as generic social processes.
We investigate the relationship between the extent of a city’s subway network, its population and its spatial configuration. For the 632 largest cities in the world we construct panel data describing ...population, measures of centralization calculated from lights at night data, and the extent of each of the 138 subway systems in these cities. These data indicate that large cities are more likely to have subways but that subways have an economically insignificant effect on urban population growth. Our data also indicate that subways cause cities to decentralize, although the effect is smaller than previously documented effects of highways on decentralization. For a subset of subway cities we observe panel data describing subway and bus ridership. For those cities we find that a 10% increase in subway extent causes about a 6% increase in subway ridership and has no effect on bus ridership.
We provide the first experimental estimation of the effects of the supply of publicly financed urban infrastructure on property values. Using random allocation of first-time street asphalting of ...residential streets located in peripheral neighborhoods in Mexico, we show that within two years of the intervention, households are able to transform their increased property wealth into significantly larger rates of vehicle ownership, household appliances, and home improvements. Increased consumption is made possible by both credit use and less saving. A cost-benefit analysis indicates that the valuation of street asphalting as capitalized into property values is about as large as construction costs.
•Cleavage of GABAergic proteins by calpain generates break down products identifiable in vitro and in vivo.•Calpain inhibition reduces the cleavage of GABAergic proteins in cultured neurons.•A ...calpain inhibitor partially reduces the cleavage of GABAergic proteins after status epilepticus.•Calpain inhibition might represent an alternative approach to block epileptogenesis.
Epileptogenesis is the processes by which a normal brain transforms and becomes capable of generate spontaneous seizures. In acquired epilepsy, it is thought that epileptogenesis can be triggered by a brain injury but the understanding of the cellular or molecular changes unraveling is incomplete. In the CA1 region of hippocampus less GABAergic activity precede the appearance of spontaneous seizures and calpain overactivation has been detected after chemoconvulsant-induced status epilepticus (SE). Inhibition of calpain overactivation following SE ameliorates seizure burden, suggesting a role for calpain dysregulation in epileptogenesis. The current study analyzed if GABAergic proteins (i.e., gephyrin, the vesicular GABA transporter and the potassium chloride co-transporter 2) undergo calpain-dependent cleavage during epileptogenesis. A time-dependent generation of break down products (BDPs) for these proteins was observed in the CA1 region of hippocampus after pilocarpine-induced SE. Generation of these BDPs was partially blocked by treatment with the calpain inhibitor MDL-28170. These findings suggest that calpain-dependent loss of GABAergic proteins might promote the erosion of inhibitory drive and contribute to hyperexcitability during epileptogenesis.
Wildfire is a recurrent phenomenon in Mediterranean ecosystems and contributes to soil degradation and desertification, which are partially caused by alterations to soil organic matter (SOM). The SOM ...composition from a Cambisol under a Mediterranean forest affected by a wildfire is studied in detail in order to assess soil health status and better understand of soil recovery after the fire event. The soil was sampled one month and twenty-five months after the wildfire. A nearby unburnt site was taken as control soil. Soil rehabilitation actions involving heavy machinery to remove burnt vegetation were conducted sixteen months after the wildfire. Immediately after fire the SOM increased in topsoil due to inputs from charred vegetation, whereas a decrease was observed in the underlying soil layer. Twenty-five months after fire soil-pH increased in fire-affected topsoil due to the presence of ashes, a decrease in SOM content was recorded for the burnt topsoil and similar trend was observed for the water holding capacity. The pyro-chromatograms of burned soils revealed the formation of additional aromatic compounds. The thermal cracking of long-chain n-alkanes was also detected. Solid-state 13C NMR spectroscopy supported the increase of aromatic compounds in the fire-affected topsoil due to the accumulation of charcoal, whereas the deeper soil sections were not affected by the fire. Two years later, soil parameters for the unburnt and burnt sites showed comparable values. The reduction of the relative intensity in the aromatic C region of the NMR spectra indicated a decrease in the charcoal content of the topsoil. Due to the negligible slope in the sampling site, the loss of charcoal was explained by the post-fire restoration activity, degradation, leaching of pyrogenic SOM into deeper soil horizons or wind erosion. Our results support that in the Mediterranean region, fire-induced alteration of the SOM is not lasting in the long-term.
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•Soil organic matter (SOM) as marker of post fire recovery.•Analytical pyrolysis shows SOM alterations at a molecular level.•Alteration of SOM quality is due to climate and post fire management activities.•Major changes exerted by fire on SOM are diluted 2years later.
Nuclear Factor Y (NF-Y) is a heterotrimeric complex formed by NF-YA/NF-YB/NF-YC subunits that binds to the CCAAT-box in eukaryotic promoters. In contrast to other organisms, in which a single gene ...encodes each subunit, in plants gene families of over 10 members encode each of the subunits. Here we report that five members of the Arabidopsis thaliana NF-YA family are strongly induced by several stress conditions via transcriptional and miR169-related post-transcriptional mechanisms. Overexpression of NF-YA2, 7 and 10 resulted in dwarf late-senescent plants with enhanced tolerance to several types of abiotic stress. These phenotypes are related to alterations in sucrose/starch balance and cell elongation observed in NF-YA overexpressing plants. The use of transcriptomic analysis of transgenic plants that express miR169-resistant versions of NF-YA2, 3, 7, and 10 under an estradiol inducible system, as well as a dominant-repressor version of NF-YA2 revealed a set of genes, whose promoters are enriched in NF-Y binding sites (CCAAT-box) and that may be directly regulated by the NF-Y complex. This analysis also suggests that NF-YAs could participate in modulating gene regulation through positive and negative mechanisms. We propose a model in which the increase in NF-YA transcript levels in response to abiotic stress is part of an adaptive response to adverse environmental conditions in which a reduction in plant growth rate plays a key role.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A novel compact device with spectrum analyzer characteristics has been designed, which allows the measuring of the maximum power received in multiple narrow frequency bands of 300 kHz, recording the ...entire spectrum from 78 MHz to 6 GHz; the device is capable of measuring the entire communications spectrum and detecting multiple sources of electromagnetic fields using the same communications band. The proposed device permits the evaluation of the cross-talk effect that, in conventional exposimeters, generates a mistake estimation of electromagnetic fields. The device was calibrated in an anechoic chamber for far-fields and was validated against a portable spectrum analyzer in a residential area. A strong correlation between the two devices with a confidence higher than 95% was obtained; indicating that the device could be considered as an important tool for electromagnetic field studies.
An efficient method to dissolve and recover waste expanded polystyrene with alternative natural oils.
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The disposal of expanded polystyrene contributes to the current pollution ...problem. To deal with such issues, there are different recycling methods. However, most of these options are expensive and environmentally unfriendly.
Herein, we report an alternative, environmentally friendly and cheaper recycling process for recovering expanded polystyrene at room temperature based on commercial essential oils used without further purification. Full dissolution of the polystyrene was achieved with a maximum ratio of 1:1 wt%. This dissolution time is at least four times faster than with limonene. Pure waste expanded polystyrene (WEP) was recovered with methanol and finally dried. All the essential oils were recovered and used again. The raw materials: WEP, the essential oils, and the recovered WEP were characterised using infrared spectroscopy, X-ray powder diffraction and thermal gravimetric analysis.
As an economic crop, pepper satisfies people's spicy taste and has medicinal uses worldwide. To gain a better understanding of Capsicum evolution, domestication, and specialization, we present here ...the genome sequence of the cultivated pepper Zunla-1 (C. annuum L.) and its wild progenitor Chiltepin (C. annuum var. glabriusculum). We estimate that the pepper genome expanded ∼0.3 Mya (with respect to the genome of other Solanaceae) by a rapid amplification of retrotransposons elements, resulting in a genome comprised of ∼81% repetitive sequences. Approximately 79% of 3.48-Gb scaffolds containing 34,476 protein-coding genes were anchored to chromosomes by a high-density genetic map. Comparison of cultivated and wild pepper genomes with 20 resequencing accessions revealed molecular footprints of artificial selection, providing us with a list of candidate domestication genes. We also found that dosage compensation effect of tandem duplication genes probably contributed to the pungent diversification in pepper. The Capsicum reference genome provides crucial information for the study of not only the evolution of the pepper genome but also, the Solanaceae family, and it will facilitate the establishment of more effective pepper breeding programs.
•Differential alterations in the plasma membrane expression of cation-chloride transporters were observed during epileptogenesis.•A shift in the cell surface expression of KCC2 and NKCC1 was detected ...during the early phase of epileptogenesis.•No change in the cell surface expression of KCC2 or NKCC1 was detected at the chronic stage.•Hyperexcitability during epileptogenesis may be a cumulative effect of multiple deficits impacting different aspects of GABAergic neurotransmission.
The process is commonly known as epileptogenesis refers to the cascade of molecular and cellular changes that transform the brain to make it hyperexcitable and capable of generate recurrent spontaneous seizures. Unfortunately, our understanding of the molecular changes that affect the brain during epileptogenesis remains incomplete. Recent evidence suggests that dysfunction of cation-chloride transporters (CCCs) might be one of the factors that contribute to the deficits in inhibitory neurotransmission observed during epileptogenesis. This study analyzed the cell surface expression of CCCs during epileptogenesis and during chronic epilepsy to evaluate if a loss of CCCs from the plasma membrane might contribute to hyperexcitability. Alterations in the plasma membrane expression of CCCs were mostly detected during the early phase of the epileptogenic period, suggesting that dysfunction of CCCs might contribute to the alterations in the chloride gradient previously detected. Together, the findings presented here suggest that aberrant regulation of the plasma membrane levels of CCCs might contribute to the impartment of GABAergic neurotransmission and that CCCs dysfunction might be relevant for the initial appearance of spontaneous seizures.
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