Invariant Distribution of Promoter Activities in Escherichia coli

Cells need to allocate their limited resources to express a wide range of genes. To understand how Escherichia coli partitions its transcriptional resources between its different promoters, we employ a robotic assay using a comprehensive reporter strain library for E. coli to measure promoter activity on a genomic scale at high-temporal resolution and accuracy. This allows continuous tracking of promoter activity as cells change their growth rate from exponential to stationary phase in different media. We find a heavy-tailed distribution of promoter activities, with promoter activities spanning several orders of magnitude. While the shape of the distribution is almost completely independent of the growth conditions, the identity of the promoters expressed at different levels does depend on them. Translation machinery genes, however, keep the same relative expression levels in the distribution across conditions, and their fractional promoter activity tracks growth rate tightly. We present a simple optimization model for resource allocation which suggests that the observed invariant distributions might maximize growth rate. These invariant features of the distribution of promoter activities may suggest design constraints that shape the allocation of transcriptional resources

Prevalence and age-of-onset distributions of DSM IV mental disorders and their severity among school going Omani adolescents and youths: WMH-CIDI findings

<p>Abstract</p> <p>Background</p> <p>There is a dearth of studies exploring the magnitude of mental disorders amongst adolescents and youths in the Arab world. To our knowledge, this phase 2 survey in Oman is the first nationally representative school-based study to determine the prevalence of DSM-IV mental disorders (lifetime and over the preceding 12 months), their age-of-onset distributions and determine their severity over the past 12 months using the World Mental Health-Composite International Diagnostic Interview, the WMH-CIDI, used for international comparison.</p> <p>Methods</p> <p>A total of 1,682 (91.61%) students out of 1836 students who formed the phase 2 random sub-sample of a multi-stage, stratified, random sampling design (phase 1), participated in the face-to-face structured interview using the Arabic-version of WMH-CIDI 3.0.</p> <p>Results</p> <p>The phase 1 results using the General Health Questionnaire (GHQ-12) and Child Depression Inventory (CDI) showed depressive symptoms to be 17% prevalent in the larger sample of 5409 adolescents and youths. Amongst the phase 2 respondents from this sample, 13.9% had at least one DSM IV diagnostic label. The lifetime prevalence of Major Depressive Disorder (MDD) was 3.0%; Bipolar Mood Disorder (BMD) was 1%, Specific phobia 5.8% and Social phobia 1.6%. The female gender was a strong predictor of a lifetime risk of MDD (OR 3.3, 95% CI 1.7-6.3, <it>p </it>= 0.000); Any Mood Disorders (OR 2.5, 95% CI 1.4-4.3, p = 0.002) and Specific Phobia (OR 1.5, 95% CI 1.0-2.4, p = 0.047). The severity of illness for cases diagnosed with 12 month DSM IV disorders was found to be 80% lower in females (OR 0.2, 95%CI 0.0-0.8). The estimates over the previous 12 month period when compared with the lifetime prevalence showed a 25% to 40% lower prevalence for MDD, Specific phobia, Social phobia, Any Anxiety Disorders (AAD) and Any Mood disorders (AMD) while the rate was 80% lower for Separation Anxiety Disorder/Adult Separation Anxiety (SAD/ASA). Mood disorders were significantly lower in the 14-16 age groups (70% lower) in comparison to the older age groups and AMD showed a linear increase in prevalence across increasing age groups (<it>p </it>= 0.035).</p> <p>Conclusion</p> <p>The implications of the present findings are not clear cut, however this study endorses the adult CIDI studies findings that mental disorders do begin earlier in life. The relatively lower prevalence of DSM IV depressive disorders cautions against any conclusive interpretation of the inflated results based on the exclusive study of the depressive symptoms alone in the same sample in the same time period. The female gender proved to be a strong predictor of lifetime risk of MDD, any mood disorder and specific phobia. Under-reporting by males or some other gender-specific factors may have contributed to such a discrepancy. The odds of the severity of illness for cases with 12 month DSM IV disorders were significantly lower in females.</p

Can disordered mobile phone use be considered a behavioral addiction? An update on current evidence and a comprehensive model for future research

Despite the many positive outcomes, excessive mobile phone use is now often associated with potentially harmful and/or disturbing behaviors (e.g., symptoms of deregulated use, negative impact on various aspects of daily life such as relationship problems, and work intrusion). Problematic mobile phone use (PMPU) has generally been considered as a behavioral addiction that shares many features with more established drug addictions. In light of the most recent data, the current paper reviews the validity of the behavioral addiction model when applied to PMPU. On the whole, it is argued that the evidence supporting PMPU as an addictive behavior is scarce. In particular, it lacks studies that definitively show behavioral and neurobiological similarities between mobile phone addiction and other types of legitimate addictive behaviors. Given this context, an integrative pathway model is proposed that aims to provide a theoretical framework to guide future research in the field of PMPU. This model highlights that PMPU is a heterogeneous and multi-faceted condition

Dirac and Klein-Gordon equations with equal scalar and vector potentials

We study the three-dimensional Dirac and Klein-Gordon equations with scalar and vector potentials of equal magnitudes as an attempt to give a proper physical interpretation of this class of problems which has recently been accumulating interest. We consider a large class of these problems in which the potentials are noncentral (angular-dependent) such that the equations separate completely in spherical coordinates. The relativistic energy spectra are obtained and shown to differ from those of well-known problems that have the same nonrelativistic limit. Consequently, such problems should not be misinterpreted as the relativistic extension of the given potentials despite the fact that the nonrelativistic limit is the same. The Coulomb, Oscillator and Hartmann potentials are considered. This shows that although the nonrelativistic limit is well-defined and unique, the relativistic extension is not. Additionally, we investigate the Klein-Gordon equation with uneven mix of potentials leading to the correct relativistic extension. We consider the case of spherically symmetric exponential-type potentials resulting in the s-wave Klein-Gordon-Morse problem.Comment: 12 page

Porosity and permeability development in compacting chalks during flooding of nonequilibrium brines: Insights from long-term experiment

We report the complete chemical alteration of a Liège outcrop chalk core resulting from a 1072 flow-through experiment performed during mechanical compaction at 130°C. Chemical rock-fluid interactions alter the volumetric strain, porosity, and permeability in a nontrivial way. The porosity reduced only from 41.32% to 40.14%, even though the plug compacted more than 25%. We present a novel analysis of the experimental data, which demonstrates that the geochemical alteration does not conserve the volume of the solids, and therefore, the strain is partitioned additively into a pore volume and solid volume component. At stresses beyond yield, the observed deformation can be explained by grain reorganization reducing the pore space between grains and solid volume changes fromthe rock-fluid interactions. Themechanical and chemical effects are discussed in relation to the observed permeability development.publishedVersio

Psychometric properties of three measures of “Facebook engagement and/or addiction” among a sample of English speaking Pakistani university students

For researchers interested in measuring the construct of “Facebook engagement and/or addiction,” there are a number of existing measures including the Bergen Facebook Addiction Scale, the Facebook Intensity Scale, and the Addictive Tendencies Scale. Currently, there is limited data on the psychometric properties of these three scales, especially among South Asian samples. The present aim was to address this shortfall. A sample of 308 English-speaking Pakistani university students completed the scales, in their original English versions, on two occasions separated by four weeks. Results demonstrated that for each of the scales, across both administrations, satisfactory psychometric properties were found, including internal reliability, temporal stability, and construct validity. Moreover, for these three scales, using confirmatory factor analysis, a one-factor structure was generally found to be a good description of the data for both male and female samples. These data provide further evidence for the reliability and validity of three scales concerned with “Facebook engagement and/or addiction.

Clinical, ultrasound and molecular biomarkers for early prediction of large for gestational age infants in nulliparous women: an international prospective cohort study

Objective: To develop a prediction model for term infants born large for gestational age (LGA) by customised birthweight centiles. Methods: International prospective cohort of nulliparous women with singleton pregnancy recruited to the Screening for Pregnancy Endpoints (SCOPE) study. LGA was defined as birthweight above the 90th customised centile, including adjustment for parity, ethnicity, maternal height and weight, fetal gender and gestational age. Clinical risk factors, ultrasound parameters and biomarkers at 14–16 or 19–21 weeks were combined into a prediction model for LGA infants at term using stepwise logistic regression in a training dataset. Prediction performance was assessed in a validation dataset using area under the Receiver Operating Characteristics curve (AUC) and detection rate at fixed false positive rates. Results: The prevalence of LGA at term was 8.8% (n = 491/5628). Clinical and ultrasound factors selected in the prediction model for LGA infants were maternal birthweight, gestational weight gain between 14–16 and 19–21 weeks, and fetal abdominal circumference, head circumference and uterine artery Doppler resistance index at 19–21 weeks (AUC 0.67; 95%CI 0.63–0.71). Sensitivity of this model was 24% and 49% for a fixed false positive rate of 10% and 25%, respectively. The addition of biomarkers resulted in selection of random glucose, LDL-cholesterol, vascular endothelial growth factor receptor-1 (VEGFR1) and neutrophil gelatinase-associated lipocalin (NGAL), but with minimal improvement in model performance (AUC 0.69; 95%CI 0.65–0.73). Sensitivity of the full model was 26% and 50% for a fixed false positive rate of 10% and 25%, respectively. Conclusion: Prediction of LGA infants at term has limited diagnostic performance before 22 weeks but may have a role in contingency screening in later pregnancy

Selection-Driven Gene Loss in Bacteria

Gene loss by deletion is a common evolutionary process in bacteria, as exemplified by bacteria with small genomes that have evolved from bacteria with larger genomes by reductive processes. The driving force(s) for genome reduction remains unclear, and here we examined the hypothesis that gene loss is selected because carriage of superfluous genes confers a fitness cost to the bacterium. In the bacterium Salmonella enterica, we measured deletion rates at 11 chromosomal positions and the fitness effects of several spontaneous deletions. Deletion rates varied over 200-fold between different regions with the replication terminus region showing the highest rates. Approximately 25% of the examined deletions caused an increase in fitness under one or several growth conditions, and after serial passage of wild-type bacteria in rich medium for 1,000 generations we observed fixation of deletions that substantially increased bacterial fitness when reconstructed in a non-evolved bacterium. These results suggest that selection could be a significant driver of gene loss and reductive genome evolution

Sex- and Diet-Specific Changes of Imprinted Gene Expression and DNA Methylation in Mouse Placenta under a High-Fat Diet

Changes in imprinted gene dosage in the placenta may compromise the prenatal control of nutritional resources. Indeed monoallelic behaviour and sensitivity to changes in regional epigenetic state render imprinted genes both vulnerable and adaptable

The use and misuse of student samples: An empirical investigation of European marketing research

In spite of the five decade old debate on the merits of student samples, to date, no systematic review of the practice is undertaken. The need for such a review is warranted considering the impasse in the debate and inconsistencies among scholars in their approach to student sample usage. This paper thus presents a systematic review of student sample usage in European Marketing Research (EJM, IJRM and IMR during 2005–2014, inclusive) to highlight existing reporting practices, identify sub-domains of marketing where the usage is more prevalent and to report best practices. Results demonstrate that 99 (19.96 per cent) papers making generalization claims used student samples exclusively, had inconsistent reporting practices (e.g. demographic profile, limitations) and demonstrated trivial concern (e.g. bias estimation treatment, identification of moderators) for the implications of student sample usage on their study findings. In addition, 11 clusters representing sub-domains of marketing research and where the practice is prevalent are identified. These clusters provide novel direction to the debate on student sample usage by framing it away from the broader discipline of marketing and bringing it closer to the interests of scholars, i.e. linking it to sub-domains of marketing research. Finally, best practices related to student samples usage are reported to help academicians enhance the validity of their findings. Copyright © 2016 John Wiley & Sons, Ltd