Flexible electronics incorporate all the functional attributes of conventional rigid electronics in formats that have been altered to survive mechanical deformations. Understanding the evolution of ...device performance during bending, stretching, or other mechanical cycling is, therefore, fundamental to research efforts in this area. Here, we review the various classes of flexible electronic devices (including power sources, sensors, circuits and individual components) and describe the basic principles of device mechanics. We then review techniques to characterize the deformation tolerance and durability of these flexible devices, and we catalogue and geometric designs that are intended to optimize electronic systems for maximum flexibility.
To investigate whether sleep disturbances are bidirectionally related to anxiety and depression, and thus identify potential risk factors for each problem.
A systematic review was conducted on 9 ...studies (8 longitudinal, 1 retrospective) that assessed bidirectionality between a sleep disturbance, and anxiety or depression. Treatment studies were excluded, along with those solely based on clinical samples or cohorts at high risk of suffering from a sleep disturbance, anxiety and depression. Eligible studies were identified by searching PubMed, PsychINFO, Embase, and Scopus databases, and reference lists of eligible studies. Publication dates ranged from the beginning of each database to December 2011.
Syntheses of longitudinal studies suggested insomnia and sleep quality were bidirectionally related to anxiety and depression, and depression/anxiety, respectively. Childhood sleep problems significantly predicted higher levels of depression and a combined depression/anxiety variable, but not vice-versa. A one-way relationship was found where anxiety predicted excessive daytime sleepiness, but excessive daytime sleepiness was not associated with depression.
Definitive conclusions regarding bidirectionality cannot be made for most sleep disturbances due to the small number and heterogeneity of cohort samples used across studies. Nevertheless, best available evidence suggests insomnia is bidirectionally related to anxiety and depression. Clinical and theoretical implications are discussed.
Alvaro PK; Roberts RM; Harris JK. A systematic review assessing bidirectionality between sleep disturbances, anxiety, and depression.
2013;36(7):1059-1068.
Many studies have focused on the mechanisms underlying length and width determination in rod-shaped bacteria. Here, we focus instead on cell surface area to volume ratio (SA/V) and demonstrate that ...SA/V homeostasis underlies size determination. We propose a model whereby the instantaneous rates of surface and volume synthesis both scale with volume. This model predicts that these relative rates dictate SA/V and that cells approach a new steady-state SA/V exponentially, with a decay constant equal to the volume growth rate. To test this, we exposed diverse bacterial species to sublethal concentrations of a cell wall biosynthesis inhibitor and observed dose-dependent decreases in SA/V. Furthermore, this decrease was exponential and had the expected decay constant. The model also quantitatively describes SA/V alterations induced by other chemical, nutritional, and genetic perturbations. We additionally present evidence for a surface material accumulation threshold underlying division, sensitizing cell length to changes in SA/V requirements.
Display omitted
•Maintenance of a condition-dependent surface area to volume ratio (SA/V) sets bacterial size•Rates of volume and surface growth both scale with volume, producing SA/V homeostasis•Biosynthesis of surface material in the cytoplasm links surface growth rate to volume•A surface material accumulation threshold for division could underlie length control
Rod-shaped bacteria alter both their width and length to achieve a condition-dependent surface area to volume ratio, and this SA/V homeostasis arises because the rates of volume and surface synthesis both scale with cell volume.
Many bacterial species exhibit SA/V homeostasis, changing their size and shape to achieve an SA/V that is set by the ratio of surface synthesis to volume synthesis in a given growth condition.
SA/V ...homeostasis arises because the rate of surface growth scales with cell volume, and evidence suggests that this scaling is likely due to the biosynthesis of new peptidoglycan (PG) in the cytoplasm setting the rate of surface growth.
Reports in the literature of changes in growth rate and/or PG biosynthesis rate leading to changes in size and shape can be explained in the context of this framework.
The classic exponential ‘growth law’ relationship between cell size and growth rate can be equally well explained as a linear relationship between SA/V and growth rate.
The concentration of PG precursors could be a molecular indicator of whether cells must increase or decrease cellular SA/V.
An immediately observable feature of bacteria is that cell size and shape are remarkably constant and characteristic for a given species in a particular condition, but vary quantitatively with physiological parameters such as growth rate, indicating both genetic and environmental regulation. However, despite decades of research, the molecular mechanisms underlying bacterial morphogenesis have remained incompletely characterized. We recently demonstrated that a wide range of bacterial species exhibit a robust surface area to volume ratio (SA/V) homeostasis. Because cell size, shape, and SA/V are mathematically interconnected, if SA/V is indeed the natural variable that cells actively monitor, this finding has critical implications for our understanding of bacterial morphogenesis, placing fundamental constraints on the sizes and shapes that cells can adopt. In this Opinion article we discuss the broad implications that this novel perspective has for the field of bacterial growth and morphogenesis.
The association of obesity susceptibility variants with change in body mass index (BMI) across the life course is not well understood.
In ancestry-stratified models of 5962 European American (EA), ...2080 African American (AA) and 1582 Hispanic American (HA) individuals from the National Longitudinal Study of Adolescent to Adult Health (Add Health), we examined associations between 34 obesity single-nucleotide polymorphisms (SNPs) with per year change in BMI, measured by the slope from a growth-curve analysis of two or more BMI measurements between adolescence and young adulthood. For SNPs nominally associated with BMI change (P<0.05), we interrogated age differences within data collection Wave and time differences between age categories that overlapped between Waves.
We found SNPs in/near FTO, MC4R, MTCH2, TFAP2B, SEC16B and TMEM18 were significantly associated (P<0.0015≈0.05/34) with BMI change in EA and the ancestry-combined meta-analysis. rs9939609 in FTO met genome-wide significance at P<5e-08 in the EA and ancestry-combined analysis, respectively Beta(se)=0.025(0.004);Beta(se)=0.021(0.003). No SNPs were significant after Bonferroni correction in AA or HA, although five SNPs in AA and four SNPs in HA were nominally significant (P<0.05). In EA and the ancestry-combined meta-analysis, rs3817334 near MTCH2 showed larger effects in younger respondents, whereas rs987237 near TFAP2B, showed larger effects in older respondents across all Waves. Differences in effect estimates across time for MTCH2 and TFAP2B are suggestive of either era or cohort effects.
The observed association between variants in/near FTO, MC4R, MTCH2, TFAP2B, SEC16B and TMEM18 with change in BMI from adolescence to young adulthood suggest that the genetic effect of BMI loci varies over time in a complex manner, highlighting the importance of investigating loci influencing obesity risk across the life course.
Asparaginyl endopeptidases (AEPs) are proteases that have crucial roles in plant defense and seed storage protein maturation. Select plant AEPs, however, do not function as proteases but as ...transpeptidases (ligases) catalyzing the intra-molecular ligation of peptide termini, which leads to peptide cyclization. These ligase-type AEPs have potential biotechnological applications ranging from in vitro peptide engineering to plant molecular farming, but the structural features enabling these enzymes to catalyze peptide ligation/cyclization rather than proteolysis are currently unknown. Here, we compare the sequences, structures, and functions of diverse plant AEPs by combining molecular modeling, sequence space analysis, and functional testing in planta. We find that changes within the substrate-binding pocket and an adjacent loop, here named the "marker of ligase activity", together play a key role for AEP ligase efficiency. Identification of these structural determinants may facilitate the discovery of more ligase-type AEPs and the engineering of AEPs with tailored catalytic properties.
With the emergence of applications based on short-wavelength infrared light, indium arsenide quantum dots are promising candidates to address existing shortcomings of other infrared-emissive ...nanomaterials. However, III-V quantum dots have historically struggled to match the high-quality optical properties of II-VI quantum dots. Here we present an extensive investigation of the kinetics that govern indium arsenide nanocrystal growth. Based on these insights, we design a synthesis of large indium arsenide quantum dots with narrow emission linewidths. We further synthesize indium arsenide-based core-shell-shell nanocrystals with quantum yields up to 82% and improved photo- and long-term storage stability. We then demonstrate non-invasive through-skull fluorescence imaging of the brain vasculature of murine models, and show that our probes exhibit 2-3 orders of magnitude higher quantum yields than commonly employed infrared emitters across the entire infrared camera sensitivity range. We anticipate that these probes will not only enable new biomedical imaging applications, but also improved infrared nanocrystal-LEDs and photon-upconversion technology.
Many tumors increase uptake and dependence on glucose, cystine or glutamine. These basic observations on cancer cell metabolism have opened multiple new diagnostic and therapeutic avenues in cancer ...research. Recent studies demonstrated that smoking could induce the expression of xCT (SLC7A11) in oral cancer cells, suggesting that overexpression of xCT may support lung tumor progression. We hypothesized that overexpression of xCT occurs in lung cancer cells to satisfy the metabolic requirements for growth and survival. Our results demonstrated that 1) xCT was highly expressed at the cytoplasmic membrane in non-small cell lung cancer (NSCLC), 2) the expression of xCT was correlated with advanced stage and predicted a worse 5-year survival, 3) targeting xCT transport activity in xCT overexpressing NSCLC cells with sulfasalazine decreased cell proliferation and invasion in vitro and in vivo and 4) increased dependence on glutamine was observed in xCT overexpressed normal airway epithelial cells. These results suggested that xCT regulate metabolic requirements during lung cancer progression and be a potential therapeutic target in NSCLC.
Abstract Objectives To investigate the independent effects of depression and subtypes of anxiety on insomnia, and vice versa, and the independent effect of chronotype on insomnia, depression, and ...subtypes of anxiety. Methods In all, 318 South Australian high school students from grades 7–11 (age range, 12–18 years; mean, 14.97 ± 1.34) participated in this cross-sectional study. Validated self-report questionnaires were used to assess insomnia, depression, subtypes of anxiety, and chronotype. Results After confounder variables were controlled, insomnia predicted depression and panic disorder (PD), whereas insomnia was predicted by depression and generalized anxiety disorder (GAD). Obsessive–compulsive disorder (OCD), separation anxiety (SAD), and social phobia (SP) were not significantly related to insomnia. Eveningness predicted the models in which depression and PD predicted insomnia and vice versa. Eveningness also predicted the models in which insomnia was predicted by OCD, SAD, and SP. Conclusions Insomnia independently predicts depression and is predicted by depression and GAD, but not by other forms of anxiety. The independent prediction of insomnia on PD is unlikely to be clinically significant. Chronotype independently predicts and hence is a risk factor for insomnia and depression, but not subtypes of anxiety. Theoretical and clinical implications are discussed.
The rheology and the conditions for viscous flow of the dry granulite facies lower crust are still poorly understood. Viscous shearing in the dry and strong lower crust commonly localizes in ...pseudotachylyte veins, but the deformation mechanisms responsible for the weakening and viscous shear localization in pseudotachylytes are yet to be explored. We investigated examples of pristine and mylonitized pseudotachylytes in anorthosites from Nusfjord (Lofoten, Norway). Mutual overprinting relationships indicate that pristine and mylonitized pseudotachylytes are coeval and resulted from the cyclical interplay between brittle and viscous deformation. The stable mineral assemblage in the mylonitized pseudotachylytes consists of plagioclase, amphibole, clinopyroxene, quartz, biotite, ± garnet ± K‐feldspar. Amphibole‐plagioclase geothermobarometry and thermodynamic modeling indicate that pristine and mylonitized pseudotachylytes formed at 650–750°C and 0.7–0.8 GPa. Thermodynamic modeling indicates that a limited amount of H2O infiltration (0.20–0.40 wt. %) was necessary to stabilize the mineral assemblage in the mylonite. Diffusion creep is identified as the main deformation mechanisms in the mylonitized pseudotachylytes based on the lack of crystallographic preferred orientation in plagioclase, the high degree of phase mixing, and the synkinematic nucleation of amphiboles in dilatant sites. Extrapolation of flow laws to natural conditions indicates that mylonitized pseudotachylytes are up to 3 orders of magnitude weaker than anorthosites deforming by dislocation creep, thus highlighting the fundamental role of lower crustal earthquakes as agents of weakening in strong granulites.
Key Points
Multiple generations of pseudotachylytes and mylonites formed at 650–750°C and 0.7–0.8 GPa in dry anorthosites from Lofoten (Norway)
Strain localized in recrystallized pseudotachylytes deforming by diffusion creep
Earthquakes are agents of weakening in the dry and strong lower crust
PDF
