1,140 research outputs found
A Foundation Failure in Philadelphia
The foundation failure of the 22 story, steel framed, federal courthouse in Philadelphia occurred because of an inadequate geotechnical assessment of a complex geological condition. The founding elevations for caissons were improperly determined on materials that could not sustain the design load. This condition was further complicated by the presence of groundwater and poor concrete construction practices. These conditions resulted in an extensive and costly remedial measures which included a grouting program and the replacement of 14 faulty caissons
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Science, State, Justice, Commerce and Related Agencies (House)/Commerce, Justice, Science and Related Agencies (Senate): FY2006 Appropriations
This report monitors actions taken by the 109th Congress for the House’s
Science, State, Justice, Commerce, and Related Agencies (SSJC) and the Senate’s
Commerce, Justice, Science, and Related Agencies (CJS) FY2006 appropriations
legislation. Appropriations bills reflect the jurisdiction of the subcommittees of the
House and Senate Appropriations Committees in which they are considered.
Jurisdictions for the subcommittees of the House and Senate Appropriations
Committees changed at the beginning of the 109th Congress.
Comprehensive Analysis of Market Conditions in the Foreign Exchange Market: Fluctuation Scaling and Variance-Covariance Matrix
We investigate quotation and transaction activities in the foreign exchange
market for every week during the period of June 2007 to December 2010. A
scaling relationship between the mean values of number of quotations (or number
of transactions) for various currency pairs and the corresponding standard
deviations holds for a majority of the weeks. However, the scaling breaks in
some time intervals, which is related to the emergence of market shocks. There
is a monotonous relationship between values of scaling indices and global
averages of currency pair cross-correlations when both quantities are observed
for various window lengths .Comment: 13 pages, 10 figure
Early onset cannabis use and progression to other drug use in a sample of Dutch twins
One possible explanation of the commonly reported associations between early onset cannabis use and elevated risks of other illicit drug use is that early onset cannabis use increases access and availability to other drugs. It was this argument that in part motivated policy changes in the Netherlands that led to the de facto legalization of cannabis there. This study examines, using a co-twin control design, whether previously observed associ- ations between early onset cannabis use and elevated lifetime rates of other illicit drug use would also be observed in a sample of 219 same sex Dutch twin pairs discordant for cannabis use before age 18. After adjustment for covariates, rates of lifetime party drug use (OR = 7.4, 95% CI = 2.3-23.4), hard drug use (OR = 16.5, 95% CI = 2.4-111.3), but not regular cannabis use (OR= 1.3, 95% CI = 0.3-5.1) were significantly elevated in individuals who reported early onset cannabis use, relative to their co-twin who had not used cannabis by age 18. The elevated odds of subsequent illicit drug use in early cannabis users relative to their non early using cotwins suggests that this association could not be explained by common familial risk factors, either genetic or environmental, for which our co-twin methodology provided rigorous control. © 2006 Springer Science+Business Media, Inc
COrE (Cosmic Origins Explorer) A White Paper
COrE (Cosmic Origins Explorer) is a fourth-generation full-sky,
microwave-band satellite recently proposed to ESA within Cosmic Vision
2015-2025. COrE will provide maps of the microwave sky in polarization and
temperature in 15 frequency bands, ranging from 45 GHz to 795 GHz, with an
angular resolution ranging from 23 arcmin (45 GHz) and 1.3 arcmin (795 GHz) and
sensitivities roughly 10 to 30 times better than PLANCK (depending on the
frequency channel). The COrE mission will lead to breakthrough science in a
wide range of areas, ranging from primordial cosmology to galactic and
extragalactic science. COrE is designed to detect the primordial gravitational
waves generated during the epoch of cosmic inflation at more than
for . It will also measure the CMB gravitational lensing
deflection power spectrum to the cosmic variance limit on all linear scales,
allowing us to probe absolute neutrino masses better than laboratory
experiments and down to plausible values suggested by the neutrino oscillation
data. COrE will also search for primordial non-Gaussianity with significant
improvements over Planck in its ability to constrain the shape (and amplitude)
of non-Gaussianity. In the areas of galactic and extragalactic science, in its
highest frequency channels COrE will provide maps of the galactic polarized
dust emission allowing us to map the galactic magnetic field in areas of
diffuse emission not otherwise accessible to probe the initial conditions for
star formation. COrE will also map the galactic synchrotron emission thirty
times better than PLANCK. This White Paper reviews the COrE science program,
our simulations on foreground subtraction, and the proposed instrumental
configuration.Comment: 90 pages Latex 15 figures (revised 28 April 2011, references added,
minor errors corrected
Non-Gaussianities in N-flation
We compute non-Gaussianities in N-flation, a string motivated model of
assisted inflation with quadratic, separable potentials and masses given by the
Marcenko-Pastur distribution. After estimating parameters characterizing the
bi- and trispectrum in the horizon crossing approximation, we focus on the
non-linearity parameter , a measure of the bispectrum; we compute its
magnitude for narrow and broad spreads of masses, including the evolution of
modes after horizon crossing. We identify additional contributions due to said
evolution and show that they are suppressed as long as the fields are evolving
slowly. This renders -flation indistinguishable from simple
single-field models in this regime. Larger non-Gaussianities are expected to
arise for fields that start to evolve faster, and we suggest an analytic
technique to estimate their contribution. However, such fast roll during
inflation is not expected in N-flation, leaving (p)re-heating as the main
additional candidate for generating non-Gaussianities.Comment: 27 pages, 4 figures, extended references to match version accepted in
JCA
Can We Really Prevent Suicide?
Every year, suicide is among the top 20 leading causes of death globally for all ages. Unfortunately, suicide is difficult to prevent, in large part because the prevalence of risk factors is high among the general population. In this review, clinical and psychological risk factors are examined and methods for suicide prevention are discussed. Prevention strategies found to be effective in suicide prevention
include means restriction, responsible media coverage, and general public education, as well identification methods such as screening, gatekeeper training, and primary care physician education. Although the treatment for preventing suicide is difficult, follow-up that includes pharmacotherapy, psychotherapy, or both may be useful. However, prevention methods cannot be restricted to the individual. Community, social, and policy interventions will also be essentia
Planck 2015 results. XXVII. The Second Planck Catalogue of Sunyaev-Zeldovich Sources
We present the all-sky Planck catalogue of Sunyaev-Zeldovich (SZ) sources detected from the 29 month full-mission data. The catalogue (PSZ2) is the largest SZ-selected sample of galaxy clusters yet produced and the deepest all-sky catalogue of galaxy clusters. It contains 1653 detections, of which 1203 are confirmed clusters with identified counterparts in external data-sets, and is the first SZ-selected cluster survey containing > confirmed clusters. We present a detailed analysis of the survey selection function in terms of its completeness and statistical reliability, placing a lower limit of 83% on the purity. Using simulations, we find that the Y5R500 estimates are robust to pressure-profile variation and beam systematics, but accurate conversion to Y500 requires. the use of prior information on the cluster extent. We describe the multi-wavelength search for counterparts in ancillary data, which makes use of radio, microwave, infra-red, optical and X-ray data-sets, and which places emphasis on the robustness of the counterpart match. We discuss the physical properties of the new sample and identify a population of low-redshift X-ray under- luminous clusters revealed by SZ selection. These objects appear in optical and SZ surveys with consistent properties for their mass, but are almost absent from ROSAT X-ray selected samples
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