3,570 research outputs found
Towards High Performance Relativistic Electronic Structure Modelling: The EXP-T Program Package
Modern challenges arising in the fields of theoretical and experimental
physics require new powerful tools for high-precision electronic structure
modelling; one of the most perspective tools is the relativistic Fock space
coupled cluster method (FS-RCC). Here we present a new extensible
implementation of the FS-RCC method designed for modern parallel computers. The
underlying theoretical model, algorithms and data structures are discussed. The
performance and scaling features of the implementation are analyzed. The
software developed allows to achieve a completely new level of accuracy for
prediction of properties of atoms and molecules containing heavy and superheavy
nuclei
Predicting disclosure and help-seeking in university students with psychosocial problems based on stigma and attitudes towards disclosure and help-seeking
Despite high prevalence of mental health problems among university students, thereâs a gap between the need for help and the actual treatment received. This study investigated disclosure on distress and hazardous alcohol use and help-seeking behavior in a sample of 1,791 students of a Dutch university of applied sciences. Studentsâ perceived public and personal stigma, and attitudes towards disclosure and help-seeking were assessed as possible predictors of disclosure and help-seeking behavior. Results of the analysis of variance and logistic regression analysis indicated that perceived public and personal stigma did not predict disclosure and helpseeking behavior, but that attitudes towards disclosure and help-seeking did. Students with both distress and hazardous alcohol use have the least tendency to disclose their problems to family, friends or classmates, but at the same time they do tend to seek help. Disclosure and seeking help for mental health challenges are health promoting competencies that seem to need more attention in university students. Although further research needs to validate these findings, it is recommended to promote disclosure and help-seeking among students by investing in mental health literacy programs, to educate students about mental health issues, raise awareness on available mental health services and their potential benefits
Elements of care that matter:Perspectives of families with multiple problems
The severe and often persistent problems of families with multiple problems (FMP) call for better understanding of how interventions can improve outcomes in these families. Perspectives of FMP on the crucial elements of interventions may strongly support improvement by providing cues on how to realize positive change. We therefore explored the views of parents and children in FMP regarding helpful and less helpful elements of various interventions. We interviewed 24 parents and 4 children about their perspectives, using a semi-structured interview guide comprising themes that were chosen by the target group. Participants reported 11 elements that contribute to the effectiveness of care, categorized under three main themes: the characteristics of the practitioner, the content of interventions, and the structure of interventions. The perspectives of FMP show the following activities to be promising: routine reflection on the non-judgmental and positive approach of practitioners, more direct focus on children, focus on the underlying cause of behavior, activation of familiesâ social network, the school and other professionals around the family, and creation of more possibilities for long-term and flexible support. Perspectives of FMP on the content and provision of care should be better embedded in interventions. This may help to tailor interventions to their wishes and needs, which in turn can contribute to more positive outcomes of care
Challenges in lifestyle and community interventions research
Earlier this year the BMC portfolio was enriched by a new journal BMC Obesity. Here, we present the aims and objectives of the section on Lifestyle and Community Interventions. Innovative research is needed. Preventing or managing obesity requires addressing different determinants across multiple levels where diverse levers and stakeholders can play a critical role. Interactions of these determinants within and between systems need to be studied. How to leverage, manage and measure this complexity underlies the innovation that is needed in the next generation of obesity interventions. The ambition of the Lifestyle and Community Interventions section is to provide a space for innovative research, including research that falls outside the traditional comfort zone. We welcome studies of heterogeneous designs, including those of qualitative, quantitative, mixed and systems methodologies. Studies of interest include not only outcomes research of interventions but also process evaluation, cost effectiveness or cost-benefit analysis, and implementation and dissemination research. Innovations that integrate diverse intervention levers or combine primary and secondary levels of prevention are particularly encouraged. The general aim of BMC Obesity’ s Lifestyle and Community Interventions section is to advance our ability to decide on what combinations of approaches will be required to effectively and equitably prevent obesity
Screening and interlayer coupling in multilayer graphene field-effect transistors
With the motivation of improving the performance and reliability of
aggressively scaled nano-patterned graphene field-effect transistors, we
present the first systematic experimental study on charge and current
distribution in multilayer graphene field-effect transistors. We find a very
particular thickness dependence for Ion, Ioff, and the Ion/Ioff ratio, and
propose a resistor network model including screening and interlayer coupling to
explain the experimental findings. In particular, our model does not invoke
modification of the linear energy-band structure of graphene for the multilayer
case. Noise reduction in nano-scale few-layer graphene transistors is
experimentally demonstrated and can be understood within this model as well.Comment: 13 pages, 4 figures, 20 reference
An L Band Spectrum of the Coldest Brown Dwarf
The coldest brown dwarf, WISE 0855, is the closest known planetary-mass,
free-floating object and has a temperature nearly as cold as the solar system
gas giants. Like Jupiter, it is predicted to have an atmosphere rich in
methane, water, and ammonia, with clouds of volatile ices. WISE 0855 is faint
at near-infrared wavelengths and emits almost all its energy in the
mid-infrared. Skemer et al. 2016 presented a spectrum of WISE 0855 from 4.5-5.1
micron (M band), revealing water vapor features. Here, we present a spectrum of
WISE 0855 in L band, from 3.4-4.14 micron. We present a set of atmosphere
models that include a range of compositions (metallicities and C/O ratios) and
water ice clouds. Methane absorption is clearly present in the spectrum. The
mid-infrared color can be better matched with a methane abundance that is
depleted relative to solar abundance. We find that there is evidence for water
ice clouds in the M band spectrum, and we find a lack of phosphine spectral
features in both the L and M band spectra. We suggest that a deep continuum
opacity source may be obscuring the near-infrared flux, possibly a deep
phosphorous-bearing cloud, ammonium dihyrogen phosphate. Observations of WISE
0855 provide critical constraints for cold planetary atmospheres, bridging the
temperature range between the long-studied solar system planets and accessible
exoplanets. JWST will soon revolutionize our understanding of cold brown dwarfs
with high-precision spectroscopy across the infrared, allowing us to study
their compositions and cloud properties, and to infer their atmospheric
dynamics and formation processes.Comment: 19 pages, 21 figures. Accepted for publication in Ap
MadGraph/MadEvent v4: The New Web Generation
We present the latest developments of the MadGraph/MadEvent Monte Carlo event
generator and several applications to hadron collider physics. In the current
version events at the parton, hadron and detector level can be generated
directly from a web interface, for arbitrary processes in the Standard Model
and in several physics scenarios beyond it (HEFT, MSSM, 2HDM). The most
important additions are: a new framework for implementing user-defined new
physics models; a standalone running mode for creating and testing matrix
elements; generation of events corresponding to different processes, such as
signal(s) and backgrounds, in the same run; two platforms for data analysis,
where events are accessible at the parton, hadron and detector level; and the
generation of inclusive multi-jet samples by combining parton-level events with
parton showers. To illustrate the new capabilities of the package some
applications to hadron collider physics are presented:
1) Higgs search in pp \to H \to W^+W^-: signal and backgrounds.
2) Higgs CP properties: pp \to H jj$in the HEFT.
3) Spin of a new resonance from lepton angular distributions.
4) Single-top and Higgs associated production in a generic 2HDM.
5) Comparison of strong SUSY pair production at the SPS points.
6) Inclusive W+jets matched samples: comparison with the Tevatron data.Comment: 38 pages, 15 figure
Orbital transformations to reduce the 1-norm of the electronic structure Hamiltonian for quantum computing applications
Solid state NMR/Biophysical Organic Chemistr
THE TOOLS AND MONTE CARLO WORKING GROUP Summary Report from the Les Houches 2009 Workshop on TeV Colliders
This is the summary and introduction to the proceedings contributions for the
Les Houches 2009 "Tools and Monte Carlo" working group.Comment: 144 Pages. Workshop site
http://wwwlapp.in2p3.fr/conferences/LesHouches/Houches2009/ . Conveners were
Butterworth, Maltoni, Moortgat, Richardson, Schumann and Skand
Importance of B4 medium in determining organomineralization potential of bacterial environmental isolates
B4 precipitation medium has been used as the preferred medium for studying mineral precipitation using bacterial strains in vitro since pioneer studies were performed by Boquet and coworkers in 1973. Using this medium, several authors have demonstrated that some environmental isolates were able to precipitate minerals, yet others did not. The main goal of the current study is to understand whether pH and buffer conditions would have a significant effect on mineral precipitation results for environmental isolates grown on B4. For this study, a total of 49 strains isolated from natural environments from Puerto Rico were grown on B4 plates, and their CaCO3 precipitation potential was investigated. Our findings revealed a strong correlation between a lack of CaCO3 precipitation and the acidification of the B4 plates by the colonies. The ability to precipitate CaCO3 could be restored by buffering the B4 medium to a pH of 8.2. Buffering capacity of the medium was proposed to be involved in CaCO3 precipitation: acid-base titrations conducted on the individual ingredients of B4 showed that yeast extract has a poor buffering capacity between pH 6.5?7.5. This pH range corresponds to the pH of B4 plates 6.87 (ĂïżœĂ±0.05)] prior to the inoculation. This might explain why B4 is such a good precipitation medium: a small variation in the H+/OH? balance during microbial growth and precipitation produces rapid changes in the pH of the medium. Finally, an amorphous matrix was distributed within 90% of the examined crystals generated on B4 medium by the environmental strains. Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the free supplemental file.; B4 precipitation medium has been used as the preferred medium for studying mineral precipitation using bacterial strains in vitro since pioneer studies were performed by Boquet and coworkers in 1973. Using this medium, several authors have demonstrated that some environmental isolates were able to precipitate minerals, yet others did not. The main goal of the current study is to understand whether pH and buffer conditions would have a significant effect on mineral precipitation results for environmental isolates grown on B4. For this study, a total of 49 strains isolated from natural environments from Puerto Rico were grown on B4 plates, and their CaCO3 precipitation potential was investigated. Our findings revealed a strong correlation between a lack of CaCO3 precipitation and the acidification of the B4 plates by the colonies. The ability to precipitate CaCO3 could be restored by buffering the B4 medium to a pH of 8.2. Buffering capacity of the medium was proposed to be involved in CaCO3 precipitation: acid-base titrations conducted on the individual ingredients of B4 showed that yeast extract has a poor buffering capacity between pH 6.5?7.5. This pH range corresponds to the pH of B4 plates 6.87 (ĂïżœĂ±0.05)] prior to the inoculation. This might explain why B4 is such a good precipitation medium: a small variation in the H+/OH? balance during microbial growth and precipitation produces rapid changes in the pH of the medium. Finally, an amorphous matrix was distributed within 90% of the examined crystals generated on B4 medium by the environmental strains. Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the free supplemental file
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