2,270 research outputs found
Childhood Maltreatment Predictors of Trait Impulsivity
This chapter provides a summary of empirical evidence linking childhood maltreatment and trait impulsivity. While biological contributors to impulsivity may be substantial, this review speculates that childhood and adolescent contributors may potentially alter the developmental trajectory of this personality trait in important ways. An analysis of original data (N = 401) regarding child maltreatment associations (childhood sexual abuse, physical abuse, sibling abuse, peer bullying, corporal punishment, and exposure to domestic violence) with trait impulsivity as measured by the Personality Inventory for the DSM-5 was also conducted. Adult respondents were assigned to extreme child abuse categories based on their retrospective self-reports. Co-occurrence rates for the various forms of maltreatment were modest (around 10%). While childhood sexual abuse was more closely associated with adult impulsivity among the men than the women, gender differences in these maltreatment relationships were otherwise minimal. Extreme childhood sexual abuse was a significant predictor of trait impulsivity and all other facets of the PID-5 Disinhibition domain (ds ranging from .52 to .80). Adult impulsivity was predicted by both childhood physical abuse (ds ranging from .23 to .28) and exposure to domestic violence during childhood (ds ranging from .21 to .32). The relative risk of adult respondents showing an elevation (\u3e 1.5 SDs) in trait Impulsivity was raised substantially by childhood histories of extreme sexual abuse (RR = 8.68), physical abuse (RR = 3.31), or exposure to parental domestic violence (RR = 4.08). Higher order interactions between these various forms of childhood maltreatment and Impulsivity were not found. The developmental psychopathology implications of these findings are discussed along with suggested directions for future research
Childhood Maltreatment and Adult Dispositional Mindfulness
Dispositional mindfulness has been conceptualized as both a trait and skill set for managing life stress. Levels of dispositional mindfulness appear to provide a meaningful barometer of emotional well-being and behavioral functioning. This chapter reviews selected literature regarding the potential effects of early life experience on the development of this important trait and coping skill. Empirical data regarding the developmental sources of this important psychological attribute has been surprisingly limited. Some prior research has implicated childhood maltreatment as disruptive to the development of this important coping skill. The present study examined the potential impact of six different forms of childhood maltreatment on dispositional mindfulness development. A number of parental relationship and resiliency protective factors were also added to the analysis. Survey respondents in this college sample (N = 978) completed indices of dispositional mindfulness, childhood maltreatment, parental relationship qualities, and resiliency factors. Respondents who described histories of sexual abuse, peer abuse, or sibling maltreatment showed lower levels of dispositional mindfulness. Parental temper was inversely related to dispositional mindfulness. Spirituality and larger childhood friendship circles provided favorable indicators. These results should encourage continued efforts to examine childhood maltreatment, early parent-child relationship qualities, and resiliency factors as potential sources of dispositional mindfulness development
B816: An Economic Analysis of a Maine Dairy Farm Anaerobic Digester
Anaerobic digestion is a method for decomposing organic matter, producing in the process, biogas, which is mostly methane. This process can be used to eliminate or reduce disagreeable and often environmentally harmful characteristics of wastes. During the autumn of 1984, the University of Maine began operation of an anaerobic digestion unit acquired from Agway, Inc., a large Northeastern agricultural cooperative. This system, installed at the Witter Animal Science Center, decomposes animal manures and ultimately produces electricity and hot water. A by-product of the system is a fertilizer with characteristics superior to fertilizers produced from biological wastes that have not undergone a process of anaerobic digestion. The research objectives were to (1) construct an economic-engineering model representing the waste to energy system, (2) quantify the benefits and costs of the system, (3) estimate the cash flows accruing over the lifespan of the system, (4) evaluate the model to determine the net present value of the system, and (5) evaluate alternative scenarios to determine the effect on economic feasibility.https://digitalcommons.library.umaine.edu/aes_bulletin/1051/thumbnail.jp
Diagnosing space telescope misalignment and jitter using stellar images
Accurate knowledge of the telescope's point spread function (PSF) is
essential for the weak gravitational lensing measurements that hold great
promise for cosmological constraints. For space telescopes, the PSF may vary
with time due to thermal drifts in the telescope structure, and/or due to
jitter in the spacecraft pointing (ground-based telescopes have additional
sources of variation). We describe and simulate a procedure for using the
images of the stars in each exposure to determine the misalignment and jitter
parameters, and reconstruct the PSF at any point in that exposure's field of
view. The simulation uses the design of the SNAP (http://snap.lbl.gov)
telescope. Stellar-image data in a typical exposure determines secondary-mirror
positions as precisely as . The PSF ellipticities and size, which
are the quantities of interest for weak lensing are determined to and accuracies respectively in each exposure,
sufficient to meet weak-lensing requirements. We show that, for the case of a
space telescope, the PSF estimation errors scale inversely with the square root
of the total number of photons collected from all the usable stars in the
exposure.Comment: 20 pages, 6 figs, submitted to PAS
Microgeometrical Tooth Profile Modification Influencing Efficiency of Planetary Hub Gears
Planetary hub systems offer desired speed and torque variation with a lighter, compact and coaxial construction than the traditional gear trains. Generated friction between the mating teeth flanks of vehicular planetary hubs under varying load-speed conditions is one of the main sources of power loss. Modification of gear tooth geometry as well as controlling the contacting surface topography is the remedial action. The paper studies the effect of tooth crowning and tip relief upon system efficiency. It includes an analytical elastohydrodynamic analysis of elliptical point contact of crowned spur gear teeth. The analysis also includes the effect of direct contact of asperities on the opposing meshing surfaces. Tooth contact analysis (TCA) is used to obtain the contact footprint shape as well as contact kinematics and load distribution. A parametric study is carried out to observe the effect of gear teeth crowning and tip relief with different levels of surface finish upon the planetary hubs’ power loss
Effect of Mesh Phasing on the Transmission Efficiency and Dynamic Performance of Wheel Hub Planetary Gear Sets
Transmission efficiency and refinement of planetary wheel hub gearing system are key design attributes for heavy and off-highway vehicles. Reduction of power loss, directly leading to the development of new generation ECO-axles requires analysis of gear contacting conditions for lubricated conjunctions to determine frictional performance. This is also affected by gear dynamics, which is a prerequisite for assessment of noise, vibration and harshness performance. Therefore, a combined tribo-dynamic analysis is essential. There is a dearth of such holistic analysis, particularly for the case of wheel hub planetary systems. The paper presents such an analysis, which has not hitherto been reported in literature. The inexorable interplay of transmission efficiency and noise, vibration and harshness refinement is demonstrated. The key attributes of noise, vibration and harshness refinement and transmission efficiency can pose contrary requirements and near-optimal conditions can be highlighted by mesh phasing of gearing contacts, thus alleviating the need for more complex gear teeth modifications entailing prohibitive manufacturing costs
Future Asymptotic Behaviour of Tilted Bianchi models of type IV and VIIh
Using dynamical systems theory and a detailed numerical analysis, the
late-time behaviour of tilting perfect fluid Bianchi models of types IV and
VII are investigated. In particular, vacuum plane-wave spacetimes are
studied and the important result that the only future attracting equilibrium
points for non-inflationary fluids are the plane-wave solutions in Bianchi type
VII models is discussed. A tiny region of parameter space (the loophole) in
the Bianchi type IV model is shown to contain a closed orbit which is found to
act as an attractor (the Mussel attractor). From an extensive numerical
analysis it is found that at late times the normalised energy-density tends to
zero and the normalised variables 'freeze' into their asymptotic values. A
detailed numerical analysis of the type VII models then shows that there is
an open set of parameter space in which solution curves approach a compact
surface that is topologically a torus.Comment: 30 pages, many postscript figure
Improved Performance and Stability of Organic Solar Cells by the Incorporation of a Block Copolymer Interfacial Layer
In a proof-of-concept study, this work demonstrates that incorporating a specifically designed block copolymer as an interfacial layer between a charge transport layer and the photoactive layer in organic solar cells can enhance the interface between these layers leading to both performance and stability improvements of the device. This is achieved by incorporating a P3HT50-b-PSSx block copolymer as an interfacial layer between the hole transporting and photoactive layers, which results in the improvement of the interfacial roughness, energy level alignment, and stability between these layers. Specifically, the incorporation of a 10Â nm P3HT50-b-PSS16 and a 13Â nm P3HT50-b-PSS23 interfacial layer results in a 9% and a 12% increase in device efficiency respectively compared to the reference devices. In addition to having a higher initial efficiency, the devices with the block copolymer continue to have a higher normalized efficiency than the control devices after 2200 h of storage, demonstrating that the block copolymer not only improves device efficiency, but crucially, prevents degradation by stabilizing the interface between the hole transporting layer and the photoactive layer. This study proves that appropriately designed and optimized block copolymers can simultaneously stabilize and improve the efficiency of organic solar cells
Renormalization group and perfect operators for stochastic differential equations
We develop renormalization group methods for solving partial and stochastic
differential equations on coarse meshes. Renormalization group transformations
are used to calculate the precise effect of small scale dynamics on the
dynamics at the mesh size. The fixed point of these transformations yields a
perfect operator: an exact representation of physical observables on the mesh
scale with minimal lattice artifacts. We apply the formalism to simple
nonlinear models of critical dynamics, and show how the method leads to an
improvement in the computational performance of Monte Carlo methods.Comment: 35 pages, 16 figure
Accurate model annotation of a near-atomic resolution cryo-EM map
Electron cryomicroscopy (cryo-EM) has been used to determine the atomic coordinates (models) from density maps of biological assemblies. These models can be assessed by their overall fit to the experimental data and stereochemical information. However, these models do not annotate the actual density values of the atoms nor their positional uncertainty. Here, we introduce a computational procedure to derive an atomic model from a cryo- EM map with annotated metadata. The accuracy of such a model is validated by a faithful replication of the experimental cryo-EM map computed using the coordinates and associated metadata. The functional interpretation of any structural features in the model and its utilization for future studies can be made in the context of its measure of uncertainty. We applied this protocol to the 3.3-Ã… map of the mature P22 bacteriophage capsid, a large and complex macromolecular assembly.With this protocol, we identify and annotate previously undescribed molecular interactions between capsid subunits that are crucial to maintain stability in the absence of cementing proteins or cross-linking, as occur in other bacteriophages.National Institutes of Health (U.S.) (Grant P41GM103832)National Institutes of Health (U.S.) (Grant R01GM079429)National Institutes of Health (U.S.) (Grant PN2EY016525)National Institutes of Health (U.S.) (Grant P01GM063210)Robert A. Welch Foundation (Grant Q1242
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