Generating random networks with given degree-degree correlations and degree-dependent clustering

Random networks are widely used to model complex networks and research their properties. In order to get a good approximation of complex networks encountered in various disciplines of science, the ability to tune various statistical properties of random networks is very important. In this manuscript we present an algorithm which is able to construct arbitrarily degree-degree correlated networks with adjustable degree-dependent clustering. We verify the algorithm by using empirical networks as input and describe additionally a simple way to fix a degree-dependent clustering function if degree-degree correlations are given.Comment: 4 pages, 3 figure

T-loop phosphorylation of Arabidopsis CDKA;1 is required for its function and can be partially substituted by an aspartate residue

As in other eukaryotes, progression through the cell cycle in plants is governed by cyclin-dependent kinases. Phosphorylation of a canonical Thr residue in the T-loop of the kinases is required for high enzyme activity in animals and yeast. We show that the Arabidopsis thaliana Cdc21/Cdc28 homolog CDKA; 1 is also phosphorylated in the T-loop and that phosphorylation at the conserved Thr-161 residue is essential for its function. A phospho-mimicry T161D substitution restored the primary defect of cdka; 1 mutants, and although the T161D substitution displayed a dramatically reduced kinase activity with a compromised ability to bind substrates, homozygous mutant plants were recovered. The rescue by the T161D substitution, however, was not complete, and the resulting plants displayed various developmental abnormalities. For instance, even though flowers were formed, these plants were completely sterile as a result of a failure of the meiotic program, indicating that different requirements for CDKA; 1 function are needed during plant development

Single-channel analysis of a ClC-2-like chloride conductance in cultured rat cortical astrocytes

AbstractThe single-channel behavior of the hyperpolarization-activated, ClC-2-like inwardly rectifying Cl− current (IClh), induced by long-term dibutyryl-cyclic-AMP-treated cultured cortical rat astrocytes, was analyzed with the patch-clamp technique. In outside-out patches in symmetrical 144 mM Cl− solutions, openings of hyperpolarization-activated small-conductance Cl− channels revealed burst activity of two equidistant conductance levels of 3 and 6 pS. The unitary openings displayed slow activation kinetics. The probabilities of the closed and conducting states were consistent with a double-barrelled structure of the channel protein. These results suggest that the astrocytic ClC-2-like Cl− current IClh is mediated by a small-conductance Cl− channel, which has the same structural motif as the Cl− channel prototype ClC-0

La investigación del ADN antiguo: Directrices sobre las precauciones, controles y el tratamiento de las muestras

The young discipline of palaeogenetics has developed into a successful and expectant field of archaeobiological research within the last decade. Palaeogenetic investigation (e.g. PCR, DNA sequencing) of ancient specimens is, however, susceptible to falsification by the presence of contamination from more recent times. Contamination which can lead to amplification of non-authentic sequences is known to stem from several sources: (i) human biomolecules derived from the persons performing the genetic experiments, perhaps also from the archeologists and other persons who have previously handled the specimens or (ii) edaphic DNA sequences derived primarily from bacterial or fungal growth upon the specimen. A third source of contamination can arise from (iii) substances used for conservation of specimens. Here we give advice on the correct processing of prehistoric bone samples when further molecular biological examination is required. Along with the demonstration of necessary precautions and working conditions, we further explain how an unequivocal DNA contamination monitoring is performed.La paleogenética se ha convertido en los últimos años en una disciplina coronada de éxito que ofrece grandes expectativas para el desarrollo de la investigación arqueobiológica. No obstante, la investigación paleogenética (p. ej: PCR, secuenciación del ADN) de especímenes antiguos es susceptible de ser falsificada por la presencia de una contaminación más reciente. Actualmente sabemos que la contaminación que provoca la amplificación de secuencias ''no auténticas" procede de las siguientes fuentes: (i) las biomoléculas humanas provienen de la persona que realiza el experimento genético o incluso también del arqueólogo u otras personas que previamente hayan tenido contacto con el espécimen; (ii) de secuencias de ADN edáficas derivadas básicamente del crecimiento bacterial o fúngico en el seno del espécimen. La tercera fuente de contaminación puede surgir de las substancias (iii) empleadas para la conservación del espécimen. El objetivo de este artículo consiste en aportar una serie de consejos sobre el modo correcto para tratar las muestras de material óseo prehistórico, en el caso que se pretenda realizar ulteriores exámenes biomoleculares. Con esta finalidad presentamos detalladamente las precauciones y condiciones necesarias de trabajo, así como una explicación de cómo puede controlarse la contaminación del ADN. Resulta prometedora la introducción de las herramientas y de la metodología paleogenéticas en el marco de la investigación arqueológica. Tal y como se observa en la mayoría de las publicaciones recientes, existe un gran número de cuestiones que pueden beneficiarse del estudio paleogenético. Cabe citar, entre otras, por ejemplo, los métodos para la reconstrucción de las estructuras sociales en la Prehistoria (a saber, la determinación de las relaciones de parentesco), o ciertas aplicaciones de la investigación paleopatológica. Por otra parte, el repertorio de técnicas disponibles para el análisis del ADN fósil, incluso del que está altamente degradado, permite elucidar, y en algunos casos dar respuesta, a antiguas cuestiones de interés general sobre la evolución de la humanidad. Con la ayuda de métodos más extensos y de un conjunto de técnicas de ADNa optimizadas eficazmente, la paleogenética, en tanto que joven disciplina, se establecerá por sí misma como un instrumento importante de la investigación arqueológica y antropológica. Sin duda alguna, la colaboración científica internacional permitiría una mayor y mejor aceptación de estos métodos en el seno de las disciplinas implicadas, así como fuera de ellas y, en consecuencia, llevaría a una mejor cualidad de la investigación dentro de las ciencias paleo genéticas. Cabe desear que en un futuro próximo se intensifique el intercambio de conocimientos y experiencias entre los grupos de trabajo que estudian las sociedades antiguas

Photoluminescence upconversion at GaAs/InGaP2 interfaces driven by a sequential two-photon absorption mechanism

This paper reports on the results of an investigation into the nature of photoluminescence upconversion at GaAs/InGaP2 interfaces. Using a dual-beam excitation experiment, we demonstrate that the upconversion in our sample proceeds via a sequential two-photon optical absorption mechanism. Measurements of photoluminescence and upconversion photoluminescence revealed evidence of the spatial localization of carriers in the InGaP2 material, arising from partial ordering of the InGaP2. We also observed the excitation of a two-dimensional electron gas at the GaAs/InGaP2 heterojunction that manifests as a high-energy shoulder in the GaAs photoluminescence spectrum. Furthermore, the results of upconversion photoluminescence excitation spectroscopy demonstrate that the photon energy onset of upconversion luminescence coincides with the energy of the two-dimensional electron gas at the GaAs/InGaP2 interface, suggesting that charge accumulation at the interface can play a crucial role in the upconversion process

Overcoming losses with gain in a negative refractive index metamaterial

On the basis of a full-vectorial three-dimensional Maxwell-Bloch approach we investigate the possibility of using gain to overcome losses in a negative refractive index fishnet metamaterial. We show that appropriate placing of optically pumped laser dyes (gain) into the metamaterial structure results in a frequency band where the nonbianisotropic metamaterial becomes amplifying. In that region both the real and the imaginary part of the effective refractive index become simultaneously negative and the figure of merit diverges at two distinct frequency points.Comment: 4 pages, 4 figure

School-Based Mental Health Services and Programs: A Review of the Literature

In Chapter 1, a rationale, a statement regarding the focus of my paper, and historical backgrounds of both community-based mental health services and the history surrounding school-based mental health (SBMH) services were provided. In Chapter 2, I review 15 studies dated between 2003 and 2017 addressing the results of school-based mental health programs involving either an in-school parental component or services delivered by clinicians in school settings and the implications SBMH presents for the educational system and its personnel. Studies reviewed are summarized in chronological order and include both quantitative data pertaining to changes in behavioral and academic qualities in children and adolescents deemed “at risk” or diagnosed with mental health disorders, as well as qualitative input related to factors contributing to the success of school-based interventions. In the final chapter, I summarize my findings and provide my conclusions and recommendations for future research

Ion Channel Involvement in Tumor Drug Resistance

Over 90% of deaths in cancer patients are attributed to tumor drug resistance. Resistance to therapeutic agents can be due to an innate property of cancer cells or can be acquired during chemotherapy. In recent years, it has become increasingly clear that regulation of membrane ion channels is an important mechanism in the development of chemoresistance. Here, we review the contribution of ion channels in drug resistance of various types of cancers, evaluating their potential in clinical management. Several molecular mechanisms have been proposed, including evasion of apoptosis, cell cycle arrest, decreased drug accumulation in cancer cells, and activation of alternative escape pathways such as autophagy. Each of these mechanisms leads to a reduction of the therapeutic efficacy of administered drugs, causing more difficulty in cancer treatment. Thus, targeting ion channels might represent a good option for adjuvant therapies in order to counteract chemo-resistance development

Control and Dynamic Competition of Bright and Dark Lasing States in Active Nanoplasmonic Metamaterials

Active nanoplasmonic metamaterials support bright and dark modes that compete for gain. Using a Maxwell-Bloch approach incorporating Langevin noise we study the lasing dynamics in an active nano-fishnet structure. We report that lasing of the bright negative-index mode is possible if the higher-Q dark mode is discriminated by gain, spatially or spectrally. The nonlinear competition during the transient phase is followed by steady-state emission where bright and dark modes can coexist. We analyze the influence of pump intensity and polarization and explore methods for mode control.Comment: 5 pages, 4 figure