Multi-configurational Ehrenfest simulations of ultrafast nonadiabatic dynamics in a charge-transfer complex

Multi-configurational Ehrenfest (MCE) approaches, which are intended to remedy the lack of correlations in the standard mean-field Ehrenfest method, have been proposed as coherent-state based ansatze for quantum propagation [D. V. Shalashilin, J. Chem. Phys. 130, 244101 (2009)] and also as the classical limit of the variational Gaussian-based multiconfiguration time dependent Hartree (G-MCTDH) method [S. Romer and I. Burghardt, Mol. Phys. 111, 3618 (2013)]. In the present paper, we establish the formal connection between these schemes and assess the performance of MCE for a coherent-state representation of the classical-limit subsystem. As a representative model system, we address the ultrafast, coherent charge transfer dynamics in an oligothiophene-fullerene donor acceptor complex described by a two-state linear vibronic coupling model. MCE calculations are compared with reference calculations performed with the MC IDH method, for 10-40 vibrational modes. Beyond a dimensionality of 10 modes, it is shown that the correct representation of electronic coherence depends crucially on the sampling of initially unoccupied Gaussians

Structural studies of T4S systems by electron microscopy

Abstract: Type IV secretion (T4S) systems are large dynamic nanomachines that transport DNA and/or proteins through the membranes of bacteria. Analysis of T4S system architecture is an extremely challenging task taking into account their multi protein organisation and lack of overall global symmetry. Nonetheless the last decade demonstrated an amazing progress achieved by X-ray crystallography and cryo-electron microscopy. In this review we present a structural analysis of this dynamic complex based on recent advances in biochemical, biophysical and structural studies

An Anomalous Type IV Secretion System in Rickettsia Is Evolutionarily Conserved

Bacterial type IV secretion systems (T4SSs) comprise a diverse transporter family functioning in conjugation, competence, and effector molecule (DNA and/or protein) translocation. Thirteen genome sequences from Rickettsia, obligate intracellular symbionts/pathogens of a wide range of eukaryotes, have revealed a reduced T4SS relative to the Agrobacterium tumefaciens archetype (vir). However, the Rickettsia T4SS has not been functionally characterized for its role in symbiosis/virulence, and none of its substrates are known.Superimposition of T4SS structural/functional information over previously identified Rickettsia components implicate a functional Rickettsia T4SS. virB4, virB8 and virB9 are duplicated, yet only one copy of each has the conserved features of similar genes in other T4SSs. An extraordinarily duplicated VirB6 gene encodes five hydrophobic proteins conserved only in a short region known to be involved in DNA transfer in A. tumefaciens. virB1, virB2 and virB7 are newly identified, revealing a Rickettsia T4SS lacking only virB5 relative to the vir archetype. Phylogeny estimation suggests vertical inheritance of all components, despite gene rearrangements into an archipelago of five islets. Similarities of Rickettsia VirB7/VirB9 to ComB7/ComB9 proteins of epsilon-proteobacteria, as well as phylogenetic affinities to the Legionella lvh T4SS, imply the Rickettsiales ancestor acquired a vir-like locus from distantly related bacteria, perhaps while residing in a protozoan host. Modern modifications of these systems likely reflect diversification with various eukaryotic host cells.We present the rvh (Rickettsiales vir homolog) T4SS, an evolutionary conserved transporter with an unknown role in rickettsial biology. This work lays the foundation for future laboratory characterization of this system, and also identifies the Legionella lvh T4SS as a suitable genetic model

Externalizing Disorders as a Potential Risk Factor for Adolescent Males

Externalizing disorders, as described by DSM-V (2013), are an empirically supported group of mental health conditions characterized by impulsiveness, antisocial behaviors, and disruptive conduct. These include Conduct Disorder (CD), Oppositional Defiant Disorder (ODD), Attention-Deficit/Hyperactivity Disorder (ADHD), and Impulse Control Disorders (ICDs). Symptoms often emerge during childhood or adolescence, when brain development is still ongoing. A prematurely-developed prefrontal cortex, paired with reward-seeking and emotional responses in youth, can contribute to impulsive behaviors and limited ability to predict the consequences of one’s actions (Casey, Jones, & Hare, 2008). Compared to females, males tend to be diagnosed with higher rates of externalizing disorders (Kerr, Reinke, & Eddy, 2013), which may place them at higher risk for engaging in risky and/or harmful behaviors. Research indicates that youth with externalizing disorders engage in a number of risky/harmful behaviors that could have negative consequences. A meta-analysis by Allely (2014) suggests that certain externalizing disorders, such as ADHD, may be a risk factor for self-harm behaviors in child, adolescent, and adult populations. Further, those with externalizing disorders in late childhood tend to have co-morbid depression and are more prone to suicidal ideation and suicide attempts during late adolescence and early adulthood (Kerr, Reinke, & Eddy, 2013). Others have also found a strong connection between externalizing disorders and suicidal behaviors among youth (Beautrais, 2000; Goldston et al., 1998; Hills, Cox, McWilliams, & Sareen, 2005; Verona & colleagues, 2000; 2001; 2004). Moreover, externalizing disorders, such as ADHD or CD, are correlated with sexual offending behaviors, which may be a result of sexual disinhibition (Kafka, 2012). While diverse, persons who have engaged in sexually abusive behavior often evidence antisocial behaviors and diagnoses of ADHD and CD (Prendergast, 2004; Shields, 1995). Grant et al. (2009) additionally indicated that the presence of trauma may also contribute to behavioral problems that resemble externalizing disorders. The current study aims to investigate male adolescents with and without externalizing disorders (i.e., ADHD, ODD, CD, and ICDs) by investigating a sample of youth in a residential treatment facility for sexually abusive behaviors (N = 295). Data related to adolescents’ self-harm behaviors, suicidal ideation and/or attempts, sexual offending behaviors, arrest histories, and diagnostic mental health histories were gathered from archival records. Within the sample, 234 participants were diagnosed with at least one externalizing disorder, including ADHD (n = 209), ODD (n = 91), CD (n = 102), and ICDs (n = 50). Chi-square analyses and one-way ANOVAs will be conducted to explore relationships among externalizing disorders, presence and frequency of self-harm behaviors and/or suicide attempts, frequency and types of sexual offenses committed, and frequency and types of arrest. Presence of PTSD diagnoses and Adverse Childhood Experiences (ACE) will also be taken into consideration, as previous literature suggests that early sexual, physical, and emotional trauma may also contribute to behavioral problems and sexual offending behaviors in adolescents (Grant et al., 2009). The goal of the current study is to fill gaps within the literature by identifying areas of concern among adolescents with externalizing disorders. The findings from the current study will be discussed in terms of clinical implications regarding risk reduction, prevention, and treatment

Are Risky Behaviors and Substance Use Higher Among Adolescence with Externalizing Disorders?

Externalizing disorders, including Attention-Deficit Hyperactivity Disorder (ADHD), Oppositional Defiance Disorder (ODD), Conduct Disorder (CD), and Impulse Control Disorder (ICD), are characterized by behavioral disinhibition/disruptive behaviors (King at al., 2004) and have been linked to high rates of substance use (Brady et al., 1998; De Sanctis, et al., 2008; Flory & Lynam, 2003; King et al., 2004). Specifically, Substance Use Disorders (SUDs) are three times higher among adolescents with ADHD and ten times higher for those with CD compared to those without these disorders (Kuperman et al., 2001). Additionally, adolescents with externalizing disorders tend to use substances earlier compared to others (Lillehoj et al., 2005), with many exposed to/regular use of alcohol, nicotine, and marijuana by age 14 (King et al., 2004). Unfortunately, adolescents with comorbid externalizing disorders and SUDs have a poorer prognosis, tending to display more substance use compared to those with SUDs only (Randall et al., 1999). Parental substance abuse disorders have also been related to a higher risk of substance use among adolescents (Hawkins et al., 1992), perhaps due to factors like accessibility and genetic predisposition. Research also suggests high rates of other risky/illegal behaviors for adolescents with externalizing disorders, including an increased number of sexual partners, rates of pregnancy, and sexually transmitted infections among adolescent females with CD (Bardone et al., 1996; 1998). Criminal behavior is more frequent among adolescents with externalizing disorders and comorbid SUDs (Randall et al., 1999). Additional factors like behavioral disinhibition and sensation seeking, typically seen in adolescents with externalizing disorders, contribute to greater engagement in illegal activities (Hawkins et al., 1992). The current study seeks to investigate male adolescents with and without externalizing disorders (i.e., ADHD, ODD, CD, and ICD) by investigating a sample of youth in a residential treatment facility for sexually abusive behaviors (N = 295). Data related to adolescents’ substance use, criminal behavior, risky sexual behaviors, and participant/parental substance abuse history were gathered from archival records. Within the sample, 234 participants were diagnosed with at least one externalizing disorder, including ADHD (n = 209), ODD (n = 91), CD (n = 102), and ICD (n = 50). Chi-square analyses and one-way ANOVAs will be conducted to explore relationships among externalizing disorders, substance use, criminal behavior, and risky sexual behaviors. The results of this study intend to inform the literature by identifying important areas of concern among adolescents with externalizing disorders. Clinical implications from the findings of the current study will help to inform prevention, risk reduction, and therapeutic goals for the treatment of adolescents with externalizing disorders